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2023年考研英语一真题及答案(Word版)

2023年考研英语一真题及答案一、完形填空考察了丝绸之路上的驿站话题，选项没有什么特别难的词或者短语，文章逻辑也很好懂，考到了并列逻辑和举例逻辑，只要考生认真读题应该拿到不错的分数Use of EnglishCaravanserais were roadside inns that were built along the Silk Road in areas includingChina, North Africa and the Middle East. They were typically __1__ outside the walls of a city or village and were usually funded by governments of __2__.This word “Caravanserais” is a __3__ of the Persian word “karvan”, which means a group of travellers or a caravan, and seray, a palace or enclosed building. The Perm caravan was used to __4__ groups of people who travelled together across the ancient network for safety reasons, __5__ merchants, travellers or pilgrims.From the 10th century onwards, as merchant and travel routes become more developed, the __6__ of the Caravanserais increased and they served as a safe place for people to rest at night. Travellers on the Silk Road __7__ possibility of being attacked by thieves or being __8__ to extreme conditions. For this reason, Caravanserais wer e strategically placed __9__ they could be reached in a day’s travel time.Caravanserais served as an informal __10__ point for the various people who travelled the Silk Road. __11__, those structures became important centers for culture __12__ and interaction, with travelers sharing their cultures, ideas and beliefs, __13__ talking knowledge with them, greatly __14__ the development of several civilizations.Caravanserais were also an important marketplace for commodities and __15__ in the trade of goods along the Silk Road. __16__, it was frequently the first stop merchants looking to sell their wares and __17__ supplies for their own journeys. It is __18__ that around 120000 to 15000 caravanserais were built along the Silk Road, __19__ only about 3000 are known to remain today, many of which are in __20__.1、答案：C. located2、答案：A. privately3、答案：D. combination4、答案：C. describe5、答案：C. such as6、答案：A. construction7、答案：B. faced8、答案：B. subjected9、答案：A. so that10、答案：D. meeting11、答案：D. As a result12、答案：C. exchange13、答案：C. as well as14、答案：B. influencing15、答案：A. aided16、答案：B. indeed17、答案：D. stock up on18、答案：A. believed19、答案：D. although20、答案：A. ruins二、阅读理解Text 1The weather in Texas may have cooled since the recent extreme heat, but the temperature will be high at the State Board of Education meeting in Austin this month as officials debate how climate change is taught in Texas schools.Pat Hardy, who sympathized with views of the energy sector, is resisting the proposed change to science standards for pre-teen pupils. These would emphasise the primacy of human activity in recent climate change and encourage discussion of mitigation measures.Most scientists and experts s harply dispute Hardy’s views. “They casually dismiss the career work of scholars and scientists as just another misguided opinion.” says Dan Quinn, senior communications strategist at the Texas Freedom Network, a non-profit group that monitors public education，“What millions of Texas kids learn in their public schools is determined too often by the political ideology of partisan board members, rather than facts and sound scholarship.”Such debate reflects fierce discussion discussions across the US and around the world, as researchers, policymakers, teachers and students step up demands for a greater focus on teaching about the facts of climate change in schools.A study last year by the National Center for Science Education, a non-profit group of scientists and teachers, looking at how state public schools across the country address climate change in science classes, gave barely half of US states a grade B+ or higher. Among the 10 worst performers were some of the most populous states, including Texas, which was given the lowest grade (F) and has a disproportionate influence because its textbooks are widely sold elsewhere.Glenn Branch, the centre’s deputy director, cautions that setting state-level science standards is only one limited benchmark in a country that decentralises decisions to local school boards. Even if a state is considered a high performer in its science standards, “that does not mean it will be taught”, he says.Another issue is that while climate change is well integrated into some subjects and at some ages — such as earth and space sciences in high schools — it is notas well represented in curricula for younger children and in subjects that are more widely taught, such as biology and chemistry. It is also less prominent in many social studies courses.Branch points out that, even if a growing number of official guidelines and textbooks reflect scientific consensus on climate change, unofficial educational materials that convey more slanted perspectives are being distributed to teachers. They include materials sponsored by libertarian think-tanks and energy industry associations.21. In paragraph 1, the weather in Texas is mentioned to答案：C. indicate the atmosphere at the board meeting22. What does Quinn think of Hardy?答案：B. She denies the value of scientific work.23. The study mentioned in Paragraph 5答案：A. Climate education is insufficient at state public school24. According to Branch, state-level science standards in the US答案：C. have limited influence25. It is implied in the last paragraph that climate change teaching in some schools答案：D. can be swayed by external forcesText 2Communities throughout the region have been attempting to regulate short-term rentals since sites like Airbnb took off in the 2010s. Now, with record-high home prices and historically low inventory, there’s an increased urgency in such regulation, particularly among those who worry that developers will come in and buy up swaths of housing to flip for a fortune on the short-term rental market.In New Hampshire, where the rental vacancy rate has dropped below 1 percent, housing advocates fear unchecked short-term rentals will put further pressure on an already strained market. The state Legislature recently voted against a bill that would’ve made it illegal for towns to create legislation restricting short-term rentals.“We are at a crisis level on the supply of rental housing, so anytime you’re taking the tool out of the toolkit for communities to address thi s, you’re potentially taking supply off the market that’s already incredibly stressed,’’ said Nick Taylor, executive director of the Workforce Housing Coalition of the Greater Seacoast. Without enough affordable housing in southern New Hampshire towns, “em ployers are having a hard time attracting employees, and workers are having a hard time finding a place to live,’’ Taylor said.However, short-term rentals also provide housing for tourists, a crucial part of the economies in places like Nantucket, Cape Cod, or the towns that make up New Hampshire’s Seacoast and Lakes Region, pointed out Ryan Castle, CEO of the Cape Cod & Islands Association of Realtors. “A lot of workers are servicing the tourist industry, and the tourism industry is serviced by those people coming in short term,’’ Castle said, “and so it’s a cyclical effect.’’Short-term rentals themselves are not the crux of the issue, said Keren Horn, an affordable housing policy expert at the University of Massachusetts Boston. “I think individual s being able to rent out their second home is a good thing. If it’s their vacation home anyway, and it’s just empty, why can’t you make money off it?’’ Horn said. Issues arise, however, when developers attempt to create large-scale short-term rental facilities —de facto hotels —to bypass taxes and regulations. “I think the question is, shouldn’t a developer who’s really building a hotel, but disguising it as not a hotel, be treated and taxed and regulated like a hotel?’’ Horn said.At the end of 2018, Governor Charlie Baker signed a bill to rein in those potential investor-buyers. “The bill requires every rental host to register with the state, mandates they carry insurance, and opens the potential for local taxes on top of a new state levy,’’ the Globe reported. Boston took things even further, limiting who is authorized to rent out their home, and requiring renters to register with the city’s Inspectional Services Department.Horn said similar registration requirements could benefit other strugglingcities and towns. The only way to solve the issue, however, is by creating more housing. “If we want to make a change in the housing market, the main one is we have to build a lot more.’’26.Which of the following is true of New England?答案：A. Its housing supply is at a very low level.27.The bill mentioned in the Paragraph 2 was intended to?答案：D. allow a free short-term rental market.28 . Compared with Castle, Tailor is more likely to support?答案：B in increase in a affordable housing29. What does Horn emphasize in paragraph 3?答案：C the necessity to stop developers from evading taxes.30. Horn holds that imposing registration requirements is答案：D an inadequate solution.Text 3If you’re heading for your nearest branch of Waterstones in search of the Duchess of Sussex’s new children’s book The Bench, you might have to be prepared to hunt around a bit; the same may be true of The President's Daughter, the new thriller by Bill Clinton and James Patterson. Both of these books are published next week by Penguin Random House, a company currently involved in a stand-off with Waterstones.The problem began late last year, when Penguin Random House confirmed that it had introduced a credit limit with Waterstones “at a very significant level”. The trade magazine The Bookseller reported that Waterstones branch managers were being told to remove PRH books from prominent areas such as tables, display spaces and windows, and were “quietly retiring them to their relevant sections”.PRH declined to comment on the issue, but a spokesperson for Waterstones told me: “Waterstones are currently operating with reduced credit terms from PRH, the only publisher in the UK to place any limitations on our ability to trade. We are not boycotting PRH titles but we are doing our utmost to ensure that availability for customers remains good despite the lower overall levels of stock. We do this generally by giving their titles less prominent positioning within our bookshops. “We are hopeful with our shops now open again that normality will return and that we will be allowed to buy appropriately. Certainly, our shops are exceptionally busy and book sales are very strong. The sales for our May Books of the Month surpassed any month since 2018.”In the meantime, PRH authors have been the losers - as have customers, who might expect the new titles from the country’s biggest publisher to be prominently displayed by its biggest book retailer. Big-name PRH authors may suffer a bit, but it’s those mid-list authors, who normally rely on Waterstones staff’s passion for promoting books by lesser-known writers, who will be praying for an end to the dispute.It comes at a time when authors are already worried about the consequences of the proposed merger between PRH and another big publisher, Simon & Schuster - the reduction in the number of unaligned UK publishers is likely to lead to fewer bidding wars, lower advances, and more conformity in terms of what is published. And one wonders if PRH would have been confident enough to deal with Waterstones in the way it has if it weren’t quite such a big company (it was formed with the merger of Penguin and Random House in 2013) and likely to get bigger.“This is all part of a wider change towards concentration of power and cartels. Literary agencies are getting bigger to have the clout to negotiate better terms with publishers, publishers consolidating to deal with Amazon,” says Lownie. “The publishing industry talks about diversity in terms of authors and staff but it also needs a plurality of ways of delivering intellectual contact, choice and different voices. After all, many of the most interesting books in recent years have come from small publishers.”We shall see whether that plurality is a casualty of the current need among publishers to be big enough to take on all-comers.31. the author mentions two books in the paragraph 1 to present ____答案：A. an ongoing conflict32. Why did Waterstones shops retire PRH books to their relevant sections?答案：C. to respond to PRH's business move33. What message did the spokesman of Waterstones seem to convey?答案：A. their customers remain royal34. What can be one consequence of the current dispute?答案：A Sales of books by mid-list PRH writers fall off considerably35. Which of the following statements best represents Lownie`s view?答案：D The merger of publishers is a worrying trendText 4Scientific papers are the recordkeepers of progress in research. Each year researchers publish millions of papers in more than 30,000 journals. The scientific community measures the quality of those papers in a number of ways, including the perceived quality of the journal (as reflected by the title’s impact factor) and the number of citations a specific paper accumulates. The careers of scientists and the reputation of their institutions depend on the number and prestige of the papers they produce, but even more so on the citations attracted by these papers.In recent years, there have been several episodes of scientific fraud, including completely made-up data, massaged or doctored figures, multiple publications of the same data, theft of complete articles, plagiarism of text, and self-plagiarism. And some scientists have come up with another way to artificially boost the number of citations to their work.Citation cartels, where journals, authors, and institutions conspire to inflate citation numbers, have existed for a long time. In 2016, researchers developed an algorithm to recognize suspicious citation patterns, including groups of authors that disproportionately cite one another and groups of journals that cite each other frequently to increase the impact factors of their publications. Recently, I cameacross yet another expression of this predatory behavior: so-called support service consultancies that provide language and other editorial support to individual authors and to journals sometimes advise contributors to add a number of citations to their articles and the articles of colleagues. Some of these consultancies are also active in organizing conferences and can advise that citations be added to conference proceedings. In this manner, a single editor can drive hundreds of citations in the direction of his own articles or those of colleagues that may be in his circle.How insidious is this type of citation manipulation? In one example, an individual—acting as author, editor, and consultant—was able to use at least 15 journals as citation providers to articles published by five scientists at three universities. The problem is rampant in Scopus, which includes a high number of the new “international” journals. In fact, a listing in Scopus seems to be a criterion to be targeted in this type of citation manipulation.36 According paragraph1, the careers of scientists can be determined by________答案：B how many times their papers are cited37 The support service consultancies tend to _________.答案：C ask authors to include extra citation38 the function of the milk cow to journals is to ________.答案：A boost citation counts for certain authors39. What can be learned about Scopus from the last two paragraph?答案：[B] It has the capability to identify suspicious citation40. What should an author do to deal with citation manipulation?答案：[D]Reveal their misconduct三、新题型考察了排序题，出题形式与往年略有差异，给出了三个既定选项位置，并给出了8个选项，首段空缺，虽然出题形式略有差异但解题思路和难度并无差异，只要能看出指代即可轻松判断出首段，整体难度中等。

英语语法---限定词

限定词（determiner）限定词的先后顺序: 前位---中位---后位(一个名词中心词之前不可并用两个前位限定词或两个中位限定词)冠词的表意功能(1)The ten of them have passed the final examination.Ten of them have passed the final examination.Ten of the (these/his) students have passed the final examination.(2)They asked to stop counting presidential votes for a second time.(3)Every boy and every girl___(have) his merits.Every young man, young lady,and child ___(be) requested to take part.Many a person___(be) going to the take the test.(4)Other or anotherCalifornia covers a large area than __________state except Alaska and Texas.Out of the three foreign guests, one is from Frankfurt, ______two are from Vienna.. Don'.los.heart.Hav.___try.There's room for _________people in the back of the bus.(5). ing.We'l.hav.____.five-da.holiday.(6)冠词的用法Who is ___captain of your team?. Mr.Reaga.wa.electe.___Presiden.o.th.Unite.State.i.1980.Charles Dickens,__author of David Copperfield, was a distinguished English novelist.As ____physician, he does not deserve much praise.He was covered with snow from ___head to __foot.The relation between ___teacher and ___student is excellent.This room serves the triple purpose of ___study, ___bedroom and ____sitting room. The old man was sitting in a chair, ___pipe in ___hand.He sat at ___ table, ___coat off, ___head down, and __pen in ___hand.What kind of ___man is he?What sort of ___book do you want?The work is ____pleasure to me.She has developed ___love for labour.Physics is ____ science.He spoke with _____ enthusiasm which inspired us all.Do you like ___ music of ___film?Phonetics is ____science of speech sounds。

教师资格认定考试初级中学英语模拟题24

教师资格认定考试初级中学英语模拟题24一、单项选择题在每小题列出的四个备选项中选择一个最佳答案。

1. In English if a word begins with a [l] or a [r], t（江南博哥）hen the next sound must be a vowel. This is a(n)______.A.assimilation ruleB.sequential ruleC.deletion ruleD.grammar rule正确答案：B[解析] 考查音系规则。

序列规则指支配音素水平组合的音系规则。

2. English consonants can be classified into stops, fricatives, nasals, etc. in terms of ______.A.manner of articulationB.openness of mouthC.place of articulationD.voicing正确答案：A[解析] 考查辅音的分类。

辅音根据发音方式(manner of articulation)的不同可以分为爆破音、摩擦音、鼻音、滑音、边音和塞擦音。

3. Operations which left patients ______ and in need of long periods of discovery time now leave them feelingrelaxed and comfortable.A.exhaustedB.unhealthyC.upsetD.fearful正确答案：A[解析] exhausted“精疲力竭的”；unhealthy“不健康的”；upset“苦恼的、不适的”；fearful“担心的、可怕的”。

结合句意“以前病人手术后精疲力竭，需长时间才能恢复，现在手术后的病人却感到既轻松又舒适。

”可知答案为A。

小马网校托福机经背景整理

小马网校托福机经背景—加州“麦当劳”也讲“风水”托福机经,托福机经背景,托福阅读机经背景小马过河网校为大家带来了托福阅读机经背景：加州“麦当劳”也讲“风水”!托福机经背景是同学们进行托福备考的重要资料，小马网校为您提供最全最快的机经背景知识!加州“麦当劳”也讲“风水”。

众所周知，托福机经背景知识不仅开拓考生的思维，而且让考生熟悉托福经常考试的题材、背景知识，让考生更好的适应托福考试，所以如果有其他问题可以请登录小马网校进行免费咨询。

Calif. McDonald's tries fengshui themeThe only familiar signs at the McDonald's in California are the golden arches, the drive-through and the menu. Gone are the plastic furniture, Ronald McDonald and the red and yellow palette that has defined the world's largest hamburger chain. Leather seats,earth tones, bamboo plants and water trickling down glass panels have taken their place.The makeover elements are meant to help diners achieve happiness and fortune -- whether they realize it or not.That's because the restaurant was redesigned using the principles of fengshui, the ancient Chinese practice of arranging objects and numbers to promote health, harmony and prosperity.The concept is an unlikely fit with fast food. But the restaurant's owners say the designs are aimed at creating a soothing setting that will encourage diners to linger over their burgers and fries, and come back again.The makeover is part of the attempt by McDonald's Corp. in recent years to remodel hundreds of its restaurants to attract more patrons with unique decor and amenities.It also fits into McDonald's larger corporate practice of catering to local tastes, such as a fondue-style burger in France or a pita-wrapped "McArabia" sandwich in the Middle East."We can't look too cookie cutter," Mark Brownstein, one of three owners of the restaurant, said about the new decor.The basic principles of fengshui include placing strategic representations of five natural elements -- earth, water, fire, metal and wood -- around the room to increase the flow of chi, or energy.Fengshui (pronounced fungshway) has been employed in the designs of high-rises, banks,even zoo exhibits, and has been popularized by countless coffee table books and TV shows. It's also used in the designs of the Panda Express Chinese food chain.The McDonald's in this Los Angeles suburb boasts wood ceiling, silver-coated chairs, plus red accents throughout the dining area to symbolize fire and "good luck, laughter and prosperity," said Brenda Clifford, who designed the dining area.Customers are responding positively, whether or not they recognize the fengshui elements.如今，在加利福尼亚一家麦当劳餐厅能看到的眼熟标识恐怕只剩下金色拱门、“得来速”和菜单了。

英语2试题及答案

英语2试题及答案一、选择题（每题2分，共20分）1. What does the word "abandon" mean?A. To leave behindB. To pick upC. To continueD. To embrace答案：A2. Fill in the blank: "The weather is very ______ today."A. hotB. coldC. warmD. cool答案：A3. Which of the following is not a verb?A. runB. jumpC. fastD. walk答案：C4. Choose the correct preposition to complete the sentence: "The book is ______ the table."A. onB. inC. atD. under答案：A5. What is the past tense of "read"?A. redB. readC. readedD. reads答案：B6. Which sentence is grammatically correct?A. She don't like apples.B. She doesn't like apples.C. She don't likes apples.D. She doesn't likes apples.答案：B7. What is the comparative form of "big"?A. biggerB. bigC. bigestD. biger答案：A8. Which word is a synonym for "famous"?A. obscureB. renownedC. unknownD. common答案：B9. Choose the correct article to complete the sentence: "Yesterday was ______ hottest day of the year."A. aB. anC. theD. /答案：C10. What does "alibi" mean?A. A legal defenseB. A place of workC. A reason for not being present at a particular placeD. A type of food答案：C二、填空题（每题2分，共20分）1. The opposite of "happy" is ______.答案：sad2. The word "because" is used to show ______.答案：reason3. The past tense of "am" is ______.答案：was4. The word "library" is a ______.答案：noun5. "They are" can be contracted to ______.答案：they're6. The word "although" is used to show ______.答案：contrast7. The comparative form of "happy" is ______.答案：happier8. The word "university" is a ______.答案：noun9. "She is" can be contracted to ______.答案：she's10. The word "however" is used to show ______.答案：contrast三、阅读理解（每题2分，共20分）Read the following passage and answer the questions.Passage:Last week, I went to the beach with my family. It was a sunny day, and we had a great time playing in the sand and swimming in the sea. In the evening, we had a barbecue and watched the sunset. It was a perfect day.1. What did the family do at the beach?答案：They played in the sand and swam in the sea.2. What was the weather like?答案：It was sunny.3. What did they do in the evening?答案：They had a barbecue and watched the sunset.4. How was the day described?答案：It was a perfect day.5. Who went to the beach?答案：The family.四、翻译题（每题2分，共20分）1. 请将以下句子翻译成英文：我昨天去了图书馆。

中科院考博英语真题200203

中国科学院2002年3月博士研究生入学考试试题PAPT Ⅱ STRUCTURE & VOCABULARY (25 minutes, 15 points)Section A (0.5 point each)Directions: Choose the word or words below each sentence that best complete the statement, and mark the corresponding letter of your choice with a single bar across the square brackets on your Machine scoring Answer Sheet.16. Knowing that the cruel criminal has done a lot of unlawful things, I feel sure that I have no__________ but to report him to the local police.A. timeB. chanceC. authorityD. alternative17. Behind his large smiles and large cigars, his eyes often seemed to _______regret.A. teem withB. brim withC. come withD. look with18. There is only one difference between an old man and a young one: the young one has aglorious future before him and the old one has a __________future behind him.A. splendidB. conspicuousC. uproariousD. imminent19. That tragedy distressed me so much that I used to keep indoors and go out only __________necessity.A. within reach ofB. for fear ofC. by means ofD. in case of20. A young man sees a sunset and, unable to understand or express the emotion that it__________in him, concludes that it must be the gateway to a world that lies beyond.A. reflectsB. retainsC. rousesD. radiates21. __________the heat to a simmer and continue to cook for another 8-10 minutes or until mostof the water has evaporated.A. Turn offB. Turn overC. Turn downD. Turn up22. Banks shall be unable to__________, or claim relief against the first 15% of any loan orbankrupted debt left with them.A. write offB. put asideC. shrink fromD. come over23. I am to inform you, that you may, if you wish, attend the inquiry, and at the inspectorsdiscretion state your case __________or through an entrusted representative.A. in personB. in depthC. in secretD. in excess24. In his view, though Hong Kong has no direct cultural identity, local art is thriving by “being__________,”being open to all kinds of art.A. gratifyingB. predominatingC. excellingD. accommodating25. In some countries preschool education in nursery schools or kindergartens _________the lstgrade.A. leadsB. precedesC. forwardsD. advances26. Desert plants __________two categories according to the way they deal with the problem ofsurviving drought.A. break downB. fall intoC. differ inD. refer to27. In the airport, I could hear nothing except the roar of aircraft engines which _____all othersounds.A. dwarfedB. diminishedC. drownedD. devastated28. Criticism without suggesting areas of improvement is not __________and should be avoidedif possible.A. constructiveB. productiveC. descriptiveD. relative29. The Committee pronounced four members expelled for failure to provide information in the__________of investigations.A. caseB. chaseC. causeD. course30. Since neither side was ready to _____what was necessary for peace, hostility was resumed in1980.A. precedeB. recedeC. concedeD. intercede31. Such an __________act of hostility can only lead to war.A. overtB. episodicC. ampleD. ultimate32. __________both in working life and everyday living to different sets of values, andexpectations places a severe strain on the individual.A. RecreationB. TransactionC. DisclosureD. Exposure33. It would then be replaced by an interim government, which would __________be replaced bya permanent government after four months.A. in stepB. in turnC. in practiceD. in haste34. Haven't I told you I don't want you keeping _______with those awful riding-about bicycleboys?A. companyB. acquaintanceC. friendsD. place35. Consumers deprived of the information and advice they needed were quite simply________every cheat in the marketplace.A. at the mercy ofB. in lieu ofC. by courtesy ofD. for the price ofPART Ⅲ CLOZE TEST (15 minutes, 15 points)Directions: There are 15 questions in this part of the test. Read the passage through. Then, go back and choose one suitable word or phrase marked A, B, C or D for each blank in the passage. Mark the corresponding letter of the word or phrase you have chosen with a single bar across the square brackets on your Machine-scoring Answer Sheet.At least since the Industrial Revolution, gender roles have been in a state of transition. As a result, cultural scripts about marriage have undergone change. One of the more obvious__46__has occurred in the roles that women__47__. Women have moved into the world of work and have become adept at meeting expectations in that arena,__48__maintaining their family roles of nurturing and creating a (n)__49__that is a haven for all family members.__50__many women experience strain from trying to “do it all,” they often enjoy t he increased__51__that can result from playing multiple roles. As women's roles have changed, changing expectations about men's roles have become more__52__. Many men are relinquishing their major responsibility__53__the family provider. Probably the most significant change in men's roles, however, is in the emotional__54__of family life. Men are increasingly__55__to meet the emotional needs of their families,__56__their wives.In fact, expectations about the emotional domain of marriage have become more significant for marriage in general. Research on__57__marriage has changed over recent decades points to the increasing importance of the emotional side of the relationships and the importance of sharing in the “emotion work”__58__to nourish marriages and other famil y relationships. Men and women want to experience marriages that are interdependent,__59__both partners nurture each other, attend and respond to each other, and encourage and promote each other. We are thus seeingmarriages in which men's and women's roles are becoming increasingly more__60__.46. A. incidents B. changes C. results D. effects47. A. take B. do C. play D. show48. A. by B. while C. hence D. thus49. A. home B. garden C. arena D. paradise50. A. When B. Even though C. Since D. Nevertheless51. A. rewards B. profits C. privileges D. incomes52. A. general B. acceptable C. popular D. apparent53. A. as B. of C. from D. for54. A. section B. constituent C. domain D. point55. A. encouraged B. expected C. advised D. predicted56. A. not to mention B. as will as C. including D. especially57. A. how B. what C. why D. if58. A. but B. only C. enough D. necessary59. A. unless B. although C. where D. because60. A. pleasant B. important C. similar D. manageablePART ⅣREADING COMPREHENSION (60 minutes, 30 points)Directions: Below each of the following passages you will find some questions or incomplete statements. Each question or statement is followed by four choices marked A, B, C and D. Read each passage carefully, and then select the choice that best answers the question square brackets on your Machine scoring Answer Sheet.Passage 1The man who invented Coca-cola was not a native Atlantan, but on the day of his funeral every drugstore in town testimonially shut up shop. He was John Styth Pemberton, born in 1883 in Knoxville, Georgia, eighty miles away. Sometimes known as Doctor, Pemberton was a pharmacist who,during the Civil War, led a cavalry troop under General Joe Wheeler. He settled in Atlanta in 1869, and soon began brewing such patent medicines as Triplex liver Pills and Globe of Flower Cough Syrup. In 1885, he registered a trademark for something called French Wine Coca—Ideal Nerve and Tonic Stimulant; a few months later he formed the Pemberton Chemical Company and recruited the services of a bookkeeper named Frank M. Robinson, who not only had a good head for figures but, attached to it, so exceptional a nose that he could audit the composition of a botch of syrup merely by sniffling it. In 1886—year in which, as contemporary Coca-Cola officials like to point out, Conan Doyle unveiled Sherlock Holmes and France unveiled the Statue of Liberty—Pemberton unveiled a syrup that he called Coca-Cola. It was a modification of his French Wine Coca. He had taken out the wine and added a pinch of caffeine, and, when the end product tasted awful, had thrown in some extract of cola nut and a few other oils, blending the mixture in a three-legged iron pot in his back yard and swishing it around with an oar. He distributed it to soda fountains in used beer bottles, and Robinson, with his flowing bookkeeper's script, presently devised a label, on which “Coca-Cola” was written in the fashion that is still employed. Pemberton looked upon his mixture less as a refreshment than as a headache cure, especially for people whose headache could be traced to over-indulgence.On a morning late in 1886, one such victim of the night before dragged himself into an Atlanta drugstore and asked for a dollop of Coca-Cola. Druggists customarily stirred a teaspoonful of syrup into a glass of water, but in this instance the man on duty was too lazy to walk to thefresh-water tap, a couple of feet off. Instead, he mixed the syrup with some soda water, which was closer at hand. The suffering customer perked up almost at once, and word quickly spread that the best Coca-Cola was a fizzy one.61. What does the passage tell us about John Styth Pemberton?A. He was highly respected by Atlantans.B. He ran a drug store that also sells wine.C. He had been a doctor until the Civil War.D. He made a lot of money with his pharmacy.62. Which of the following was unique to Frank M. Robinson, working with the Pemberton'sCompany?A. Skills to make French wine.B. He ran a drug store that also sells wine.C. He had been a doctor until the Civil War.D. Ability to work with numbers.63. Why was the year 1886 so special to Pemberton?A. He took to doing a job like Sherlock Holmes's.B. He brought a quite profitable product into being.C. He observed the founding ceremony of Statue of Liberty.D. He was awarded by Coca-Cola for his contribution.64. One modification made of French Wine Coca formula was__________.A. used beer bottles were chosen as containersB. the amount of caffeine in it was increasedC. it was blended with oils instead of waterD. Cola nut extract was added to taste65. According to the passage, Coca-Cola was in the first place prepared especially for__________.A. the young as a soft drinkB. a replacement of French Wine CocaC. the relief of a hangoverD. a cure for the common headache66. The last paragraph mainly tells__________.A. the complaint against the lazy shop-assistantB. a real test of Coca-Cola as a headache cureC. the mediocre service of the drugstoreD. a happy accident that gave birth to Coca-ColaPassage 2Between 1883 and 1837, the publishers of a “penny press” proved that a low-priced paper, edited to interest ordinary people, could win what amounted to a mass circulation for the times and thereby attract an advertising volume that would make it independent. These were papers for the common citizen and were not tied to the interests of the business community, like the mercantile press, or dependent for financial support upon political party allegiance. It did not necessarily follow that all the penny papers would be superior in their handling of the news and opinion functions. But the door was open for some to make important journalistic advances.The first offerings of a penny paper tended to be highly sensational; human interest storiesovershadowed important news, and crime and sex stories were written in full detail. But as the penny paper attracted readers from various social and economic brackets, its sensationalism was modified. The ordinary reader came to want a better product, too. A popularized style of writing and presentation of news remained, but the penny paper became a respectable publication that offered significant information and editorial leadership. Once the first of the successful penny papers had shown the way, later ventures could enter the competition at the higher level of journalistic responsibility the pioneering papers had reached.This was the pattern of American newspapers in the years following the founding of the New York sun in 1833. The Sun, published by Benjamin Day, entered the lists against 11 other dailies. It was tiny in comparison; but it was bright and readable, and it preferred human interest features to important but dull political speech reports. It had a police reporter writing squibs of crime news in the style already proved successful by some other papers. And, most important, it sold for a penny, whereas its competitors sold for six cents. By 1837 the Sun was printing 30,000 copies a day, which was more than the total of all 11 New York daily newspapers combined when the Sun first appeared. In those same four years James Gordon Bennett brought out his New York Herald (1835), and a trio of New York printers who were imitating Day's success founded the Philadelphia Public Ledger (1836) and the Baltimore Sun (1837). The four penny sheets all became famed newspapers.67. What does the first p aragraph say about the “penny press?”A. It was known for its in-depth news reporting.B. It had an involvement with some political parties.C. It depended on the business community for survival.D. It aimed at pleasing the general public.68. In its early days, a penny paper often__________.A. paid much attention to political partiesB. provided stories that hit the pubic tasteC. offered penetrating editorials on various issuesD. covered important news with inaccuracy69. As the readership was growing more diverse, the penny paper__________.A. improved its contentB. changed its writing styleC. developed a more sensational styleD. became a tool for political parties70. The underlined word “ventures” in Paragraph 2 can best be replaced by__________.A. editorsB. reportersC. newspapersD. companies71. What is true about the Philadelphia Public Ledger and the Baltimore Sun?A. They turned out to be failures.B. They were later purchased by James Gordon Bennett.C. They were also founded by Benjamin Day.D. They became well-known newspapers in the U.S.72. This passage is probably taken from a book on__________.A. the work ethics of the American mediaB. the technique in news reportingC. the history of sensationalism in American mediaD. the impact of mass media on American societyPassage 3Forget what Virginia Woolf said about what a writer needs—a room of one‟s own. The writer she has in mind wasn't at work on a novel in cyberspace, one with multiple hypertexts, animated graphics and downloads of trancey, charming music. For that you also need graphic interfaces, RealPlayer and maybe even a computer laboratory at Brown University. That was where Mark Amerika—his legally adopted name; don't ask him about his birth name—composed much of his novel Grammatron isn't just a story. It's an online narrative(grammatron. com) that uses the capabilities of cyberspace to tie the conventional story line into complicated knots. IN the four years it took to produce—it was completed in 1997—each new advance in computer software became another potential story device. “I became sort of dependent on the industry,” jokes Amerika, who is also the author of two novels printed on paper. “That's unusual for a writer, because if you just write on paper the …technology‟is pretty stable.”Nothing about Grammatron is stable. At its center, if there is one, is Abe Golam, the inventor of Nanoscript, a quasi-mystical computer code that some unmystical corporations are itching to acquire. For much of the story, Abe wanders through Prague-23, a virtual“city” in cyberspace where visitors indulge in fantasy encounters and virtual sex, which can get fairly graphic. The reader wanders too, because most of Grammatron's 1,000-plus text screens contain several passages in hypertext. To reach the next screen just double-click. But each of those hypertexts is a trapdoor that can plunge you down a different pathway of the story. Choose one and you drop into a corporate-strategy memo. Choose another and there's a XXX-rated sexual rant. The story you read is in some sense the story you make.Amerika teaches digital art at the University of Colorado, where his students develop works that straddle the lines between art, film and literature. “I tell them not to get ca ught up in mere plot,” he says. Some avant-garde writers-Julio Cortazar, Italo Calvino-have also experimented with novels that wander out of their author's control. “But what makes the Net so exciting,” says Amerika, “is that you can add sound, randomly ge nerated links, 3-D modeling, animation.” That room of one's own is turning into a fun house.73. The passage is mainly to tell__________.A. differences between conventional and modern novelsB. how Mark Amerika composed his novel GrammatronC. common features of all modern electronic novelsD. why mark Amerika took on a new way of writing74. Why does the author ask the reader to forget what Virginia Woolf said about the necessities ofa writer?A. Modern writers can share rooms to do the writing.B. It is not necessarily that a writer writes inside a room.C. Modern writers will get nowhere without a word processor.D. It is no longer sufficient for the writing in cyberspace.75. As an on-line narrative, Grammatron is anything but stable because it__________.A. provides potentials for the story developmentB. is one of the novels at grammatron. comC. can be downloaded free of chargeD. boasts of the best among cyber stories76. By saying that he became sort of dependent on the industry, Mark Amerika meant that ______.A. he could not help but set his Grammatron and others in Industrial RevolutionB. conventional writers had been increasingly challenged by high technologyC. much of his Grammatron had proved to be cybernetic dependentD. he couldn't care less new advance in computer software77. As the passage shows, Grammatron makes it possible for readers to__________.A. adapt the story for a video versionB. “walk in” the story and interact with itC. develop the plots within the author's controlD. steal the show and become the main character78. Amerika told his students not to__________.A. immerse themselves only in creating the plotB. be captivated by the plot alone while readingC. be lagged far behind in the plot developmentD. let their plot get lost in the on-going storyPassage 4In 1993, a mall security camera captured a shaky image of two 10-year-old boys leading much smaller boy out of a Liverpool, England, shopping center. The boys lured James Bulger, 2,away from his mother, who was shopping, and led him on a long walk across town. The excursion ended at a railroad track. There, inexplicably, the older boys tortured the toddler, kicking him, smearing paint on his face and pummeling him to death with bricks before leaving him on the track to be dismembered by a train. The boys, Jon Venables and Robert Thompson, then went off to watch cartoon.Today the boys are 18-year-old men, and after spending eight years in juvenile facilities, they have been deemed fit for release-probably this spring. The dilemma now confronting the English justice system is how to reintegrate the notorious duo into a society that remains horrified by their crimes and skeptical about their rehabilitation. Last week Judge Elizabeth Butler-Sloss decided the young men were in so much danger that they needed an unprecedented shield to protect them upon release. For the rest of their lives, Venables and Thompson will have a right to anonymity. All English madia outlets are banned from publishing any information about their whereabouts or the new identities the government will help them establish. Photos of the two or even details about their current looks art also prohibited.In the U. S., which is harder on juvenile criminals than England, such a ruling seems inconceivable. “We're clearly the most punitive in the industrialized world,” says Laurence Steinberg, a Temple University professor who studies juvenile justice. Over the past decade, the trend in the U. S. has been to allow publication of ever more information about underage offenders. U. S. courts also give more weight to press freedom than English courts, which, for example, ban all video cameras.But even for Britain, the order is extraordinary. The victim's family is enraged, as are the ever-eager British tabloids. “What right have they got to be given special protection as adults?” asks Bulger's mother Denise Fergus. Newspaper editorials have insisted that citizens have a right to know if Venables or Thompson move in next door. Says conservative Member of Parliament Humfrey Malins：“It almost leaves you with the feeling that the nastier the crime, the greater the chance for a passpor to a completely new life.”79. What occurred as told at the beginning of the passage?A. 2 ten-year-olds killed James by accident in play.B. James Bulger was killed by his two brothers.C. Two mischievous boys forged a train accident.D. A little kid was murdered by two older boys.80. According to the passage, Jon Venables and Robert Thompson__________.A. have been treated as juvenile delinquentsB. have been held in protective custody for their murder gameC. were caught while watching cartoons eight years agoD. have already served out their 10 years in prison81. The British justice system is afraid that the two young men would__________.A. hardly get accustomed to a horrifying general publicB. be doomed to become social outcasts after releaseC. still remain dangerous and destructive if set freeD. be inclined to commit a recurring crime82. According to the British courts, after their return to society, the two adults will be__________.A. banned from any kind of press interviewB. kept under constant surveillance by policeC. shielded from being identified as killersD. ordered to report to police their whereabouts83. From the passage we can infer that a US counterpart of Vanables or Thompson would__________.A. have no freedom to go wherever he wantsB. serve a life imprisoment for the crimeC. be forbidden to join many of his relativesD. no doubt receive massive publicity in the U. S.84. As regards the mentioned justice ruling, the last paragraph mainly tells that__________.A. it is controversial as it goes without precedentB. the British media are sure to do the contraryC. Bulger's family would enter all appeal against itD. conservatives obviously conflict with LiberalsPassage 5Can the Internet help patients jump the line at the doctor's office? The Silicon Valley Employers Forum, a sophisticated group of technology companies, is launching a pilot program to test online “virtual visits” between doctors at three big local medical groups about and 6,000 employees and their families. The six employers taking part in the Silicon Valley initiative, including heavy hitters such as Oracle and Cisco Systems, hope that online visits will mean employees won't have to skip work to tend to minor ailments or to follow up on chronic conditions. “Which our long commutes and traffic, driving 40 miles to your doctor in your hometown can be a big chunk of time,” says Cindy Conway, benefits director at Cadence Design Systems, one of the participating companies.Doctors aren't clamoring to chat with patients online for free; they spend enough unpaid time on the phone. Only 1 in 5 has ever E-mailed a patient, and just 9 percent are interested in doing so,according to the research firm Cyber Dialogue. “We are not stupid,” says Stirling Somers, executive director of the Silicon Valley employers group. “Doctors getting paid is a critical p iece in getting this to work.” In the pilot program, physicians will get $ 20 per online consultation, obout what they get for a simple office visit.Doctors also fear they'll be swamped by rambling E-mails that tell everything but what's needed to make a diagnosis. So the new program will use technology supplied by Healinx, an Alameda, Calif—based start-up. Healinx's “Smart Symptom Wizard” questions patients and turns answers into a succinct message. The company has online dialogues for 60 common conditions. The doctor can then diagnose the problem and outline a treatment plan, which could include E-mailing a prescription or a face-to-face visit.Can E-mail replace the doctor's office? Many conditions, such as persistent cough, require stethoscope to discover what's wrong-and to avoid a malpractice suit. Even Larry Bonham, head of one of the doctor's groups in the pilot, believes the virtual doctor's visits offer a “very narrow” sliver of service between phone calls to an advice nurse and a visit to the clinic.The pilot program, set to end in nine months, also hopes to determine whether online visits will boost worker productivity enough to offset the cost of the service. So far, the Internet's record in the health field has been underwhelming. The experi ment is “a huge roll of the dice for Healinx”, notes Michael Barrett, an analyst at Internet consulting firm Forester Research. If the “Web visits” succeed, expect some HMOs (Health Maintenance Organizations) to pay for online visits. If doctors, employers, and patients aren't satisfied, figure on one more E-health start-up to stand down.85. The Silicon Valley employers promote the E-health program for the purpose of__________.A. rewarding their employeesB. gratifying the local hospitalsC. boosting worker productivityD. testing a sophisticated technology86. What can be learned about the on-line doctors' visits?A. They are a quite promising business.B. They are funded by the local government.C. They are welcomed by all the patients.D. They are very much under experimentation.87. Of the following people, who are not involved in the program?A. Cisco System employees.B. Advice nurses in the clinic.C. Doctors at three local hospitals.D. Oracle at three local hospitals.88. According to Paragraph 2, doctors are__________.A. reluctant to serve online for nothingB. not interested in Web consultationC. too tired to talk to the patients onlineD. content with $ 20 paid per Web visit89. “Smart Symptom Wizard” is capable of__________.A. making diagnosesB. producing prescriptionsC. profiling patients's illnessD. offering a treatment plan90. It can be inferred from the passage that the future of online visits will mostly depend onwhether__________.A. the employers would remain confident in themB. they could effectively replace office visitsC. HMOs would cover the cost of the serviceD. new technologies would be available to improve the E-health projectPAPER TWOPART ⅤTRANSLATION (25 minutes, 10 points)Directions: Put the following passage into English. Write your English version in the proper space on your Answer Sheet Ⅱ.伟大艺术的美学鉴赏和伟大的科学观念的理解都需要智慧。

OSHA现场作业手册说明书

DIRECTIVE NUMBER: CPL 02-00-150 EFFECTIVE DATE: April 22, 2011 SUBJECT: Field Operations Manual (FOM)ABSTRACTPurpose: This instruction cancels and replaces OSHA Instruction CPL 02-00-148,Field Operations Manual (FOM), issued November 9, 2009, whichreplaced the September 26, 1994 Instruction that implemented the FieldInspection Reference Manual (FIRM). The FOM is a revision of OSHA’senforcement policies and procedures manual that provides the field officesa reference document for identifying the responsibilities associated withthe majority of their inspection duties. This Instruction also cancels OSHAInstruction FAP 01-00-003 Federal Agency Safety and Health Programs,May 17, 1996 and Chapter 13 of OSHA Instruction CPL 02-00-045,Revised Field Operations Manual, June 15, 1989.Scope: OSHA-wide.References: Title 29 Code of Federal Regulations §1903.6, Advance Notice ofInspections; 29 Code of Federal Regulations §1903.14, Policy RegardingEmployee Rescue Activities; 29 Code of Federal Regulations §1903.19,Abatement Verification; 29 Code of Federal Regulations §1904.39,Reporting Fatalities and Multiple Hospitalizations to OSHA; and Housingfor Agricultural Workers: Final Rule, Federal Register, March 4, 1980 (45FR 14180).Cancellations: OSHA Instruction CPL 02-00-148, Field Operations Manual, November9, 2009.OSHA Instruction FAP 01-00-003, Federal Agency Safety and HealthPrograms, May 17, 1996.Chapter 13 of OSHA Instruction CPL 02-00-045, Revised FieldOperations Manual, June 15, 1989.State Impact: Notice of Intent and Adoption required. See paragraph VI.Action Offices: National, Regional, and Area OfficesOriginating Office: Directorate of Enforcement Programs Contact: Directorate of Enforcement ProgramsOffice of General Industry Enforcement200 Constitution Avenue, NW, N3 119Washington, DC 20210202-693-1850By and Under the Authority ofDavid Michaels, PhD, MPHAssistant SecretaryExecutive SummaryThis instruction cancels and replaces OSHA Instruction CPL 02-00-148, Field Operations Manual (FOM), issued November 9, 2009. The one remaining part of the prior Field Operations Manual, the chapter on Disclosure, will be added at a later date. This Instruction also cancels OSHA Instruction FAP 01-00-003 Federal Agency Safety and Health Programs, May 17, 1996 and Chapter 13 of OSHA Instruction CPL 02-00-045, Revised Field Operations Manual, June 15, 1989. This Instruction constitutes OSHA’s general enforcement policies and procedures manual for use by the field offices in conducting inspections, issuing citations and proposing penalties.Significant Changes∙A new Table of Contents for the entire FOM is added.∙ A new References section for the entire FOM is added∙ A new Cancellations section for the entire FOM is added.∙Adds a Maritime Industry Sector to Section III of Chapter 10, Industry Sectors.∙Revises sections referring to the Enhanced Enforcement Program (EEP) replacing the information with the Severe Violator Enforcement Program (SVEP).∙Adds Chapter 13, Federal Agency Field Activities.∙Cancels OSHA Instruction FAP 01-00-003, Federal Agency Safety and Health Programs, May 17, 1996.DisclaimerThis manual is intended to provide instruction regarding some of the internal operations of the Occupational Safety and Health Administration (OSHA), and is solely for the benefit of the Government. No duties, rights, or benefits, substantive or procedural, are created or implied by this manual. The contents of this manual are not enforceable by any person or entity against the Department of Labor or the United States. Statements which reflect current Occupational Safety and Health Review Commission or court precedents do not necessarily indicate acquiescence with those precedents.Table of ContentsCHAPTER 1INTRODUCTIONI.PURPOSE. ........................................................................................................... 1-1 II.SCOPE. ................................................................................................................ 1-1 III.REFERENCES .................................................................................................... 1-1 IV.CANCELLATIONS............................................................................................. 1-8 V. ACTION INFORMATION ................................................................................. 1-8A.R ESPONSIBLE O FFICE.......................................................................................................................................... 1-8B.A CTION O FFICES. .................................................................................................................... 1-8C. I NFORMATION O FFICES............................................................................................................ 1-8 VI. STATE IMPACT. ................................................................................................ 1-8 VII.SIGNIFICANT CHANGES. ............................................................................... 1-9 VIII.BACKGROUND. ................................................................................................. 1-9 IX. DEFINITIONS AND TERMINOLOGY. ........................................................ 1-10A.T HE A CT................................................................................................................................................................. 1-10B. C OMPLIANCE S AFETY AND H EALTH O FFICER (CSHO). ...........................................................1-10B.H E/S HE AND H IS/H ERS ..................................................................................................................................... 1-10C.P ROFESSIONAL J UDGMENT............................................................................................................................... 1-10E. W ORKPLACE AND W ORKSITE ......................................................................................................................... 1-10CHAPTER 2PROGRAM PLANNINGI.INTRODUCTION ............................................................................................... 2-1 II.AREA OFFICE RESPONSIBILITIES. .............................................................. 2-1A.P ROVIDING A SSISTANCE TO S MALL E MPLOYERS. ...................................................................................... 2-1B.A REA O FFICE O UTREACH P ROGRAM. ............................................................................................................. 2-1C. R ESPONDING TO R EQUESTS FOR A SSISTANCE. ............................................................................................ 2-2 III. OSHA COOPERATIVE PROGRAMS OVERVIEW. ...................................... 2-2A.V OLUNTARY P ROTECTION P ROGRAM (VPP). ........................................................................... 2-2B.O NSITE C ONSULTATION P ROGRAM. ................................................................................................................ 2-2C.S TRATEGIC P ARTNERSHIPS................................................................................................................................. 2-3D.A LLIANCE P ROGRAM ........................................................................................................................................... 2-3 IV. ENFORCEMENT PROGRAM SCHEDULING. ................................................ 2-4A.G ENERAL ................................................................................................................................................................. 2-4B.I NSPECTION P RIORITY C RITERIA. ..................................................................................................................... 2-4C.E FFECT OF C ONTEST ............................................................................................................................................ 2-5D.E NFORCEMENT E XEMPTIONS AND L IMITATIONS. ....................................................................................... 2-6E.P REEMPTION BY A NOTHER F EDERAL A GENCY ........................................................................................... 2-6F.U NITED S TATES P OSTAL S ERVICE. .................................................................................................................. 2-7G.H OME-B ASED W ORKSITES. ................................................................................................................................ 2-8H.I NSPECTION/I NVESTIGATION T YPES. ............................................................................................................... 2-8 V.UNPROGRAMMED ACTIVITY – HAZARD EVALUATION AND INSPECTION SCHEDULING ............................................................................ 2-9 VI.PROGRAMMED INSPECTIONS. ................................................................... 2-10A.S ITE-S PECIFIC T ARGETING (SST) P ROGRAM. ............................................................................................. 2-10B.S CHEDULING FOR C ONSTRUCTION I NSPECTIONS. ..................................................................................... 2-10C.S CHEDULING FOR M ARITIME I NSPECTIONS. ............................................................................. 2-11D.S PECIAL E MPHASIS P ROGRAMS (SEP S). ................................................................................... 2-12E.N ATIONAL E MPHASIS P ROGRAMS (NEP S) ............................................................................... 2-13F.L OCAL E MPHASIS P ROGRAMS (LEP S) AND R EGIONAL E MPHASIS P ROGRAMS (REP S) ............ 2-13G.O THER S PECIAL P ROGRAMS. ............................................................................................................................ 2-13H.I NSPECTION S CHEDULING AND I NTERFACE WITH C OOPERATIVE P ROGRAM P ARTICIPANTS ....... 2-13CHAPTER 3INSPECTION PROCEDURESI.INSPECTION PREPARATION. .......................................................................... 3-1 II.INSPECTION PLANNING. .................................................................................. 3-1A.R EVIEW OF I NSPECTION H ISTORY .................................................................................................................... 3-1B.R EVIEW OF C OOPERATIVE P ROGRAM P ARTICIPATION .............................................................................. 3-1C.OSHA D ATA I NITIATIVE (ODI) D ATA R EVIEW .......................................................................................... 3-2D.S AFETY AND H EALTH I SSUES R ELATING TO CSHO S.................................................................. 3-2E.A DVANCE N OTICE. ................................................................................................................................................ 3-3F.P RE-I NSPECTION C OMPULSORY P ROCESS ...................................................................................................... 3-5G.P ERSONAL S ECURITY C LEARANCE. ................................................................................................................. 3-5H.E XPERT A SSISTANCE. ........................................................................................................................................... 3-5 III. INSPECTION SCOPE. ......................................................................................... 3-6A.C OMPREHENSIVE ................................................................................................................................................... 3-6B.P ARTIAL. ................................................................................................................................................................... 3-6 IV. CONDUCT OF INSPECTION .............................................................................. 3-6A.T IME OF I NSPECTION............................................................................................................................................. 3-6B.P RESENTING C REDENTIALS. ............................................................................................................................... 3-6C.R EFUSAL TO P ERMIT I NSPECTION AND I NTERFERENCE ............................................................................. 3-7D.E MPLOYEE P ARTICIPATION. ............................................................................................................................... 3-9E.R ELEASE FOR E NTRY ............................................................................................................................................ 3-9F.B ANKRUPT OR O UT OF B USINESS. .................................................................................................................... 3-9G.E MPLOYEE R ESPONSIBILITIES. ................................................................................................. 3-10H.S TRIKE OR L ABOR D ISPUTE ............................................................................................................................. 3-10I. V ARIANCES. .......................................................................................................................................................... 3-11 V. OPENING CONFERENCE. ................................................................................ 3-11A.G ENERAL ................................................................................................................................................................ 3-11B.R EVIEW OF A PPROPRIATION A CT E XEMPTIONS AND L IMITATION. ..................................................... 3-13C.R EVIEW S CREENING FOR P ROCESS S AFETY M ANAGEMENT (PSM) C OVERAGE............................. 3-13D.R EVIEW OF V OLUNTARY C OMPLIANCE P ROGRAMS. ................................................................................ 3-14E.D ISRUPTIVE C ONDUCT. ...................................................................................................................................... 3-15F.C LASSIFIED A REAS ............................................................................................................................................. 3-16VI. REVIEW OF RECORDS. ................................................................................... 3-16A.I NJURY AND I LLNESS R ECORDS...................................................................................................................... 3-16B.R ECORDING C RITERIA. ...................................................................................................................................... 3-18C. R ECORDKEEPING D EFICIENCIES. .................................................................................................................. 3-18 VII. WALKAROUND INSPECTION. ....................................................................... 3-19A.W ALKAROUND R EPRESENTATIVES ............................................................................................................... 3-19B.E VALUATION OF S AFETY AND H EALTH M ANAGEMENT S YSTEM. ....................................................... 3-20C.R ECORD A LL F ACTS P ERTINENT TO A V IOLATION. ................................................................................. 3-20D.T ESTIFYING IN H EARINGS ................................................................................................................................ 3-21E.T RADE S ECRETS. ................................................................................................................................................. 3-21F.C OLLECTING S AMPLES. ..................................................................................................................................... 3-22G.P HOTOGRAPHS AND V IDEOTAPES.................................................................................................................. 3-22H.V IOLATIONS OF O THER L AWS. ....................................................................................................................... 3-23I.I NTERVIEWS OF N ON-M ANAGERIAL E MPLOYEES .................................................................................... 3-23J.M ULTI-E MPLOYER W ORKSITES ..................................................................................................................... 3-27 K.A DMINISTRATIVE S UBPOENA.......................................................................................................................... 3-27 L.E MPLOYER A BATEMENT A SSISTANCE. ........................................................................................................ 3-27 VIII. CLOSING CONFERENCE. .............................................................................. 3-28A.P ARTICIPANTS. ..................................................................................................................................................... 3-28B.D ISCUSSION I TEMS. ............................................................................................................................................ 3-28C.A DVICE TO A TTENDEES .................................................................................................................................... 3-29D.P ENALTIES............................................................................................................................................................. 3-30E.F EASIBLE A DMINISTRATIVE, W ORK P RACTICE AND E NGINEERING C ONTROLS. ............................ 3-30F.R EDUCING E MPLOYEE E XPOSURE. ................................................................................................................ 3-32G.A BATEMENT V ERIFICATION. ........................................................................................................................... 3-32H.E MPLOYEE D ISCRIMINATION .......................................................................................................................... 3-33 IX. SPECIAL INSPECTION PROCEDURES. ...................................................... 3-33A.F OLLOW-UP AND M ONITORING I NSPECTIONS............................................................................................ 3-33B.C ONSTRUCTION I NSPECTIONS ......................................................................................................................... 3-34C. F EDERAL A GENCY I NSPECTIONS. ................................................................................................................. 3-35CHAPTER 4VIOLATIONSI. BASIS OF VIOLATIONS ..................................................................................... 4-1A.S TANDARDS AND R EGULATIONS. .................................................................................................................... 4-1B.E MPLOYEE E XPOSURE. ........................................................................................................................................ 4-3C.R EGULATORY R EQUIREMENTS. ........................................................................................................................ 4-6D.H AZARD C OMMUNICATION. .............................................................................................................................. 4-6E. E MPLOYER/E MPLOYEE R ESPONSIBILITIES ................................................................................................... 4-6 II. SERIOUS VIOLATIONS. .................................................................................... 4-8A.S ECTION 17(K). ......................................................................................................................... 4-8B.E STABLISHING S ERIOUS V IOLATIONS ............................................................................................................ 4-8C. F OUR S TEPS TO BE D OCUMENTED. ................................................................................................................... 4-8 III. GENERAL DUTY REQUIREMENTS ............................................................. 4-14A.E VALUATION OF G ENERAL D UTY R EQUIREMENTS ................................................................................. 4-14B.E LEMENTS OF A G ENERAL D UTY R EQUIREMENT V IOLATION.............................................................. 4-14C. U SE OF THE G ENERAL D UTY C LAUSE ........................................................................................................ 4-23D.L IMITATIONS OF U SE OF THE G ENERAL D UTY C LAUSE. ..............................................................E.C LASSIFICATION OF V IOLATIONS C ITED U NDER THE G ENERAL D UTY C LAUSE. ..................F. P ROCEDURES FOR I MPLEMENTATION OF S ECTION 5(A)(1) E NFORCEMENT ............................ 4-25 4-27 4-27IV.OTHER-THAN-SERIOUS VIOLATIONS ............................................... 4-28 V.WILLFUL VIOLATIONS. ......................................................................... 4-28A.I NTENTIONAL D ISREGARD V IOLATIONS. ..........................................................................................4-28B.P LAIN I NDIFFERENCE V IOLATIONS. ...................................................................................................4-29 VI. CRIMINAL/WILLFUL VIOLATIONS. ................................................... 4-30A.A REA D IRECTOR C OORDINATION ....................................................................................................... 4-31B.C RITERIA FOR I NVESTIGATING P OSSIBLE C RIMINAL/W ILLFUL V IOLATIONS ........................ 4-31C. W ILLFUL V IOLATIONS R ELATED TO A F ATALITY .......................................................................... 4-32 VII. REPEATED VIOLATIONS. ...................................................................... 4-32A.F EDERAL AND S TATE P LAN V IOLATIONS. ........................................................................................4-32B.I DENTICAL S TANDARDS. .......................................................................................................................4-32C.D IFFERENT S TANDARDS. .......................................................................................................................4-33D.O BTAINING I NSPECTION H ISTORY. .....................................................................................................4-33E.T IME L IMITATIONS..................................................................................................................................4-34F.R EPEATED V. F AILURE TO A BATE....................................................................................................... 4-34G. A REA D IRECTOR R ESPONSIBILITIES. .............................................................................. 4-35 VIII. DE MINIMIS CONDITIONS. ................................................................... 4-36A.C RITERIA ................................................................................................................................................... 4-36B.P ROFESSIONAL J UDGMENT. ..................................................................................................................4-37C. A REA D IRECTOR R ESPONSIBILITIES. .............................................................................. 4-37 IX. CITING IN THE ALTERNATIVE ............................................................ 4-37 X. COMBINING AND GROUPING VIOLATIONS. ................................... 4-37A.C OMBINING. ..............................................................................................................................................4-37B.G ROUPING. ................................................................................................................................................4-38C. W HEN N OT TO G ROUP OR C OMBINE. ................................................................................................4-38 XI. HEALTH STANDARD VIOLATIONS ....................................................... 4-39A.C ITATION OF V ENTILATION S TANDARDS ......................................................................................... 4-39B.V IOLATIONS OF THE N OISE S TANDARD. ...........................................................................................4-40 XII. VIOLATIONS OF THE RESPIRATORY PROTECTION STANDARD(§1910.134). ....................................................................................................... XIII. VIOLATIONS OF AIR CONTAMINANT STANDARDS (§1910.1000) ... 4-43 4-43A.R EQUIREMENTS UNDER THE STANDARD: .................................................................................................. 4-43B.C LASSIFICATION OF V IOLATIONS OF A IR C ONTAMINANT S TANDARDS. ......................................... 4-43 XIV. CITING IMPROPER PERSONAL HYGIENE PRACTICES. ................... 4-45A.I NGESTION H AZARDS. .................................................................................................................................... 4-45B.A BSORPTION H AZARDS. ................................................................................................................................ 4-46C.W IPE S AMPLING. ............................................................................................................................................. 4-46D.C ITATION P OLICY ............................................................................................................................................ 4-46 XV. BIOLOGICAL MONITORING. ...................................................................... 4-47CHAPTER 5CASE FILE PREPARATION AND DOCUMENTATIONI.INTRODUCTION ............................................................................................... 5-1 II.INSPECTION CONDUCTED, CITATIONS BEING ISSUED. .................... 5-1A.OSHA-1 ................................................................................................................................... 5-1B.OSHA-1A. ............................................................................................................................... 5-1C. OSHA-1B. ................................................................................................................................ 5-2 III.INSPECTION CONDUCTED BUT NO CITATIONS ISSUED .................... 5-5 IV.NO INSPECTION ............................................................................................... 5-5 V. HEALTH INSPECTIONS. ................................................................................. 5-6A.D OCUMENT P OTENTIAL E XPOSURE. ............................................................................................................... 5-6B.E MPLOYER’S O CCUPATIONAL S AFETY AND H EALTH S YSTEM. ............................................................. 5-6 VI. AFFIRMATIVE DEFENSES............................................................................. 5-8A.B URDEN OF P ROOF. .............................................................................................................................................. 5-8B.E XPLANATIONS. ..................................................................................................................................................... 5-8 VII. INTERVIEW STATEMENTS. ........................................................................ 5-10A.G ENERALLY. ......................................................................................................................................................... 5-10B.CSHO S SHALL OBTAIN WRITTEN STATEMENTS WHEN: .......................................................................... 5-10C.L ANGUAGE AND W ORDING OF S TATEMENT. ............................................................................................. 5-11D.R EFUSAL TO S IGN S TATEMENT ...................................................................................................................... 5-11E.V IDEO AND A UDIOTAPED S TATEMENTS. ..................................................................................................... 5-11F.A DMINISTRATIVE D EPOSITIONS. .............................................................................................5-11 VIII. PAPERWORK AND WRITTEN PROGRAM REQUIREMENTS. .......... 5-12 IX.GUIDELINES FOR CASE FILE DOCUMENTATION FOR USE WITH VIDEOTAPES AND AUDIOTAPES .............................................................. 5-12 X.CASE FILE ACTIVITY DIARY SHEET. ..................................................... 5-12 XI. CITATIONS. ..................................................................................................... 5-12A.S TATUTE OF L IMITATIONS. .............................................................................................................................. 5-13B.I SSUING C ITATIONS. ........................................................................................................................................... 5-13C.A MENDING/W ITHDRAWING C ITATIONS AND N OTIFICATION OF P ENALTIES. .................................. 5-13D.P ROCEDURES FOR A MENDING OR W ITHDRAWING C ITATIONS ............................................................ 5-14 XII. INSPECTION RECORDS. ............................................................................... 5-15A.G ENERALLY. ......................................................................................................................................................... 5-15B.R ELEASE OF I NSPECTION I NFORMATION ..................................................................................................... 5-15C. C LASSIFIED AND T RADE S ECRET I NFORMATION ...................................................................................... 5-16。

tpo54三篇阅读原文译文题目答案译文背景知识

托福阅读tpo54全套解析阅读-1 (2)原文 (2)译文 (4)题目 (5)答案 (9)背景知识 (10)阅读-2 (10)原文 (10)译文 (12)题目 (13)答案 (18)背景知识 (20)阅读-3 (25)原文 (26)译文 (27)题目 (28)答案 (33)背景知识 (35)阅读-1原文The Commercialization of Lumber①In nineteenth-century America, practically everything that was built involved wood.Pine was especially attractive for building purposes.It is durable and strong, yet soft enough to be easily worked with even the simplest of hand tools.It also floats nicely on water, which allowed it to be transported to distant markets across the nation.The central and northern reaches of the Great Lakes states—Michigan, Wisconsin, and Minnesota—all contained extensive pine forests as well as many large rivers for floating logs into the Great Lakes, from where they were transported nationwide.②By 1860, the settlement of the American West along with timber shortages in the East converged with ever-widening impact on the pine forests of the Great Lakes states. Over the next 30 years, lumbering became a full-fledged enterprise in Michigan, Wisconsin, and Minnesota. Newly formed lumbering corporations bought up huge tracts of pineland and set about systematically cutting the trees. Both the colonists and the later industrialists saw timber as a commodity, but the latter group adopted a far more thorough and calculating approach to removing trees. In this sense, what happened between 1860 and 1890 represented a significant break with the past. No longer were farmers in search of extra income the main source for shingles, firewood, and other wood products. By the 1870s, farmers and city dwellers alike purchased forest products from large manufacturingcompanies located in the Great Lakes states rather than chopping wood themselves or buying it locally.③The commercialization of lumbering was in part the product of technological change. The early, thick saw blades tended to waste a large quantity of wood, with perhaps as much as a third of the log left behind on the floor as sawdust or scrap. In the 1870s, however, the British-invented band saw, with its thinner blade, became standard issue in the Great Lakes states' lumber factories.Meanwhile, the rise of steam-powered mills streamlined production by allowing for the more efficient, centralized, and continuous cutting of lumber. Steam helped to automate a variety of tasks, from cutting to the carrying away of waste. Mills also employed steam to heat log ponds, preventing them from freezing and making possible year-round lumber production.④For industrial lumbering to succeed, a way had to be found to neutralize the effects of the seasons on production. Traditionally, cutting took place in the winter, when snow and ice made it easier to drag logs on sleds or sleighs to the banks of streams. Once the streams and lakes thawed, workers rafted the logs to mills, where they were cut into lumber in the summer. If nature did not cooperate—if the winter proved dry and warm, if the spring thaw was delayed—production would suffer. To counter the effects of climate on lumber production, loggers experimented with a variety of techniques for transporting trees out of the woods. In the 1870s, loggers in the Great Lakes states began sprinkling water on sleigh roads, giving them an artificial ice coating to facilitate travel. The ice reduced the friction and allowed workers to move larger and heavier loads.⑤But all the sprinkling in the world would not save a logger from the threat of a warm winter. Without snow the sleigh roads turned to mud. In the 1870s, a set of snowless winters left lumber companies to ponder ways of liberating themselves from the seasons. Railroads were one possibility.At first, the remoteness of the pine forests discouraged common carriers from laying track.But increasing lumber prices in the late 1870s combined with periodic warm, dry winters compelled loggers to turn to iron rails. By 1887, 89 logging railroads crisscrossed Michigan, transforming logging from a winter activity into a year-round one.⑥Once the logs arrived at a river, the trip downstream to a mill could be a long and tortuous one.Logjams (buildups of logs that prevent logs from moving downstream) were common—at times stretching for 10 miles—and became even more frequent as pressure on the northern Midwest pinelands increased in the 1860s. To help keep the logs moving efficiently, barriers called booms (essentially a chain of floating logs) were constructed to control the direction of the timber. By the 1870s, lumber companies existed in all the major logging areas of the northern Midwest.译文木材的商业化①在19世纪的美国，几乎所有建筑材料都含有木材。

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History of infrared detectorsA.ROGALSKI*Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str.,00–908 Warsaw, PolandThis paper overviews the history of infrared detector materials starting with Herschel’s experiment with thermometer on February11th,1800.Infrared detectors are in general used to detect,image,and measure patterns of the thermal heat radia−tion which all objects emit.At the beginning,their development was connected with thermal detectors,such as ther−mocouples and bolometers,which are still used today and which are generally sensitive to all infrared wavelengths and op−erate at room temperature.The second kind of detectors,called the photon detectors,was mainly developed during the20th Century to improve sensitivity and response time.These detectors have been extensively developed since the1940’s.Lead sulphide(PbS)was the first practical IR detector with sensitivity to infrared wavelengths up to~3μm.After World War II infrared detector technology development was and continues to be primarily driven by military applications.Discovery of variable band gap HgCdTe ternary alloy by Lawson and co−workers in1959opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design.Many of these advances were transferred to IR astronomy from Departments of Defence ter on civilian applications of infrared technology are frequently called“dual−use technology applications.”One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies,as well as the noticeable price decrease in these high cost tech−nologies.In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays(FPAs).Development in FPA technology has revolutionized infrared imaging.Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.Keywords:thermal and photon detectors, lead salt detectors, HgCdTe detectors, microbolometers, focal plane arrays.Contents1.Introduction2.Historical perspective3.Classification of infrared detectors3.1.Photon detectors3.2.Thermal detectors4.Post−War activity5.HgCdTe era6.Alternative material systems6.1.InSb and InGaAs6.2.GaAs/AlGaAs quantum well superlattices6.3.InAs/GaInSb strained layer superlattices6.4.Hg−based alternatives to HgCdTe7.New revolution in thermal detectors8.Focal plane arrays – revolution in imaging systems8.1.Cooled FPAs8.2.Uncooled FPAs8.3.Readiness level of LWIR detector technologies9.SummaryReferences 1.IntroductionLooking back over the past1000years we notice that infra−red radiation(IR)itself was unknown until212years ago when Herschel’s experiment with thermometer and prism was first reported.Frederick William Herschel(1738–1822) was born in Hanover,Germany but emigrated to Britain at age19,where he became well known as both a musician and an astronomer.Herschel became most famous for the discovery of Uranus in1781(the first new planet found since antiquity)in addition to two of its major moons,Tita−nia and Oberon.He also discovered two moons of Saturn and infrared radiation.Herschel is also known for the twenty−four symphonies that he composed.W.Herschel made another milestone discovery–discov−ery of infrared light on February11th,1800.He studied the spectrum of sunlight with a prism[see Fig.1in Ref.1],mea−suring temperature of each colour.The detector consisted of liquid in a glass thermometer with a specially blackened bulb to absorb radiation.Herschel built a crude monochromator that used a thermometer as a detector,so that he could mea−sure the distribution of energy in sunlight and found that the highest temperature was just beyond the red,what we now call the infrared(‘below the red’,from the Latin‘infra’–be−OPTO−ELECTRONICS REVIEW20(3),279–308DOI: 10.2478/s11772−012−0037−7*e−mail: rogan@.pllow)–see Fig.1(b)[2].In April 1800he reported it to the Royal Society as dark heat (Ref.1,pp.288–290):Here the thermometer No.1rose 7degrees,in 10minu−tes,by an exposure to the full red coloured rays.I drew back the stand,till the centre of the ball of No.1was just at the vanishing of the red colour,so that half its ball was within,and half without,the visible rays of theAnd here the thermometerin 16minutes,degrees,when its centre was inch out of the raysof the sun.as had a rising of 9de−grees,and here the difference is almost too trifling to suppose,that latter situation of the thermometer was much beyond the maximum of the heating power;while,at the same time,the experiment sufficiently indi−cates,that the place inquired after need not be looked for at a greater distance.Making further experiments on what Herschel called the ‘calorific rays’that existed beyond the red part of the spec−trum,he found that they were reflected,refracted,absorbed and transmitted just like visible light [1,3,4].The early history of IR was reviewed about 50years ago in three well−known monographs [5–7].Many historical information can be also found in four papers published by Barr [3,4,8,9]and in more recently published monograph [10].Table 1summarises the historical development of infrared physics and technology [11,12].2.Historical perspectiveFor thirty years following Herschel’s discovery,very little progress was made beyond establishing that the infrared ra−diation obeyed the simplest laws of optics.Slow progress inthe study of infrared was caused by the lack of sensitive and accurate detectors –the experimenters were handicapped by the ordinary thermometer.However,towards the second de−cade of the 19th century,Thomas Johann Seebeck began to examine the junction behaviour of electrically conductive materials.In 1821he discovered that a small electric current will flow in a closed circuit of two dissimilar metallic con−ductors,when their junctions are kept at different tempera−tures [13].During that time,most physicists thought that ra−diant heat and light were different phenomena,and the dis−covery of Seebeck indirectly contributed to a revival of the debate on the nature of heat.Due to small output vol−tage of Seebeck’s junctions,some μV/K,the measurement of very small temperature differences were prevented.In 1829L.Nobili made the first thermocouple and improved electrical thermometer based on the thermoelectric effect discovered by Seebeck in 1826.Four years later,M.Melloni introduced the idea of connecting several bismuth−copper thermocouples in series,generating a higher and,therefore,measurable output voltage.It was at least 40times more sensitive than the best thermometer available and could de−tect the heat from a person at a distance of 30ft [8].The out−put voltage of such a thermopile structure linearly increases with the number of connected thermocouples.An example of thermopile’s prototype invented by Nobili is shown in Fig.2(a).It consists of twelve large bismuth and antimony elements.The elements were placed upright in a brass ring secured to an adjustable support,and were screened by a wooden disk with a 15−mm central aperture.Incomplete version of the Nobili−Melloni thermopile originally fitted with the brass cone−shaped tubes to collect ra−diant heat is shown in Fig.2(b).This instrument was much more sensi−tive than the thermometers previously used and became the most widely used detector of IR radiation for the next half century.The third member of the trio,Langley’s bolometer appea−red in 1880[7].Samuel Pierpont Langley (1834–1906)used two thin ribbons of platinum foil connected so as to form two arms of a Wheatstone bridge (see Fig.3)[15].This instrument enabled him to study solar irradiance far into its infrared region and to measure theintensityof solar radia−tion at various wavelengths [9,16,17].The bolometer’s sen−History of infrared detectorsFig.1.Herschel’s first experiment:A,B –the small stand,1,2,3–the thermometers upon it,C,D –the prism at the window,E –the spec−trum thrown upon the table,so as to bring the last quarter of an inch of the read colour upon the stand (after Ref.1).InsideSir FrederickWilliam Herschel (1738–1822)measures infrared light from the sun– artist’s impression (after Ref. 2).Fig.2.The Nobili−Meloni thermopiles:(a)thermopile’s prototype invented by Nobili (ca.1829),(b)incomplete version of the Nobili−−Melloni thermopile (ca.1831).Museo Galileo –Institute and Museum of the History of Science,Piazza dei Giudici 1,50122Florence, Italy (after Ref. 14).Table 1. Milestones in the development of infrared physics and technology (up−dated after Refs. 11 and 12)Year Event1800Discovery of the existence of thermal radiation in the invisible beyond the red by W. HERSCHEL1821Discovery of the thermoelectric effects using an antimony−copper pair by T.J. SEEBECK1830Thermal element for thermal radiation measurement by L. NOBILI1833Thermopile consisting of 10 in−line Sb−Bi thermal pairs by L. NOBILI and M. MELLONI1834Discovery of the PELTIER effect on a current−fed pair of two different conductors by J.C. PELTIER1835Formulation of the hypothesis that light and electromagnetic radiation are of the same nature by A.M. AMPERE1839Solar absorption spectrum of the atmosphere and the role of water vapour by M. MELLONI1840Discovery of the three atmospheric windows by J. HERSCHEL (son of W. HERSCHEL)1857Harmonization of the three thermoelectric effects (SEEBECK, PELTIER, THOMSON) by W. THOMSON (Lord KELVIN)1859Relationship between absorption and emission by G. KIRCHHOFF1864Theory of electromagnetic radiation by J.C. MAXWELL1873Discovery of photoconductive effect in selenium by W. SMITH1876Discovery of photovoltaic effect in selenium (photopiles) by W.G. ADAMS and A.E. DAY1879Empirical relationship between radiation intensity and temperature of a blackbody by J. STEFAN1880Study of absorption characteristics of the atmosphere through a Pt bolometer resistance by S.P. LANGLEY1883Study of transmission characteristics of IR−transparent materials by M. MELLONI1884Thermodynamic derivation of the STEFAN law by L. BOLTZMANN1887Observation of photoelectric effect in the ultraviolet by H. HERTZ1890J. ELSTER and H. GEITEL constructed a photoemissive detector consisted of an alkali−metal cathode1894, 1900Derivation of the wavelength relation of blackbody radiation by J.W. RAYEIGH and W. WIEN1900Discovery of quantum properties of light by M. PLANCK1903Temperature measurements of stars and planets using IR radiometry and spectrometry by W.W. COBLENTZ1905 A. EINSTEIN established the theory of photoelectricity1911R. ROSLING made the first television image tube on the principle of cathode ray tubes constructed by F. Braun in 18971914Application of bolometers for the remote exploration of people and aircrafts ( a man at 200 m and a plane at 1000 m)1917T.W. CASE developed the first infrared photoconductor from substance composed of thallium and sulphur1923W. SCHOTTKY established the theory of dry rectifiers1925V.K. ZWORYKIN made a television image tube (kinescope) then between 1925 and 1933, the first electronic camera with the aid of converter tube (iconoscope)1928Proposal of the idea of the electro−optical converter (including the multistage one) by G. HOLST, J.H. DE BOER, M.C. TEVES, and C.F. VEENEMANS1929L.R. KOHLER made a converter tube with a photocathode (Ag/O/Cs) sensitive in the near infrared1930IR direction finders based on PbS quantum detectors in the wavelength range 1.5–3.0 μm for military applications (GUDDEN, GÖRLICH and KUTSCHER), increased range in World War II to 30 km for ships and 7 km for tanks (3–5 μm)1934First IR image converter1939Development of the first IR display unit in the United States (Sniperscope, Snooperscope)1941R.S. OHL observed the photovoltaic effect shown by a p−n junction in a silicon1942G. EASTMAN (Kodak) offered the first film sensitive to the infrared1947Pneumatically acting, high−detectivity radiation detector by M.J.E. GOLAY1954First imaging cameras based on thermopiles (exposure time of 20 min per image) and on bolometers (4 min)1955Mass production start of IR seeker heads for IR guided rockets in the US (PbS and PbTe detectors, later InSb detectors for Sidewinder rockets)1957Discovery of HgCdTe ternary alloy as infrared detector material by W.D. LAWSON, S. NELSON, and A.S. YOUNG1961Discovery of extrinsic Ge:Hg and its application (linear array) in the first LWIR FLIR systems1965Mass production start of IR cameras for civil applications in Sweden (single−element sensors with optomechanical scanner: AGA Thermografiesystem 660)1970Discovery of charge−couple device (CCD) by W.S. BOYLE and G.E. SMITH1970Production start of IR sensor arrays (monolithic Si−arrays: R.A. SOREF 1968; IR−CCD: 1970; SCHOTTKY diode arrays: F.D.SHEPHERD and A.C. YANG 1973; IR−CMOS: 1980; SPRITE: T. ELIOTT 1981)1975Lunch of national programmes for making spatially high resolution observation systems in the infrared from multielement detectors integrated in a mini cooler (so−called first generation systems): common module (CM) in the United States, thermal imaging commonmodule (TICM) in Great Britain, syteme modulaire termique (SMT) in France1975First In bump hybrid infrared focal plane array1977Discovery of the broken−gap type−II InAs/GaSb superlattices by G.A. SAI−HALASZ, R. TSU, and L. ESAKI1980Development and production of second generation systems [cameras fitted with hybrid HgCdTe(InSb)/Si(readout) FPAs].First demonstration of two−colour back−to−back SWIR GaInAsP detector by J.C. CAMPBELL, A.G. DENTAI, T.P. LEE,and C.A. BURRUS1985Development and mass production of cameras fitted with Schottky diode FPAs (platinum silicide)1990Development and production of quantum well infrared photoconductor (QWIP) hybrid second generation systems1995Production start of IR cameras with uncooled FPAs (focal plane arrays; microbolometer−based and pyroelectric)2000Development and production of third generation infrared systemssitivity was much greater than that of contemporary thermo−piles which were little improved since their use by Melloni. Langley continued to develop his bolometer for the next20 years(400times more sensitive than his first efforts).His latest bolometer could detect the heat from a cow at a dis−tance of quarter of mile [9].From the above information results that at the beginning the development of the IR detectors was connected with ther−mal detectors.The first photon effect,photoconductive ef−fect,was discovered by Smith in1873when he experimented with selenium as an insulator for submarine cables[18].This discovery provided a fertile field of investigation for several decades,though most of the efforts were of doubtful quality. By1927,over1500articles and100patents were listed on photosensitive selenium[19].It should be mentioned that the literature of the early1900’s shows increasing interest in the application of infrared as solution to numerous problems[7].A special contribution of William Coblenz(1873–1962)to infrared radiometry and spectroscopy is marked by huge bib−liography containing hundreds of scientific publications, talks,and abstracts to his credit[20,21].In1915,W.Cob−lentz at the US National Bureau of Standards develops ther−mopile detectors,which he uses to measure the infrared radi−ation from110stars.However,the low sensitivity of early in−frared instruments prevented the detection of other near−IR sources.Work in infrared astronomy remained at a low level until breakthroughs in the development of new,sensitive infrared detectors were achieved in the late1950’s.The principle of photoemission was first demonstrated in1887when Hertz discovered that negatively charged par−ticles were emitted from a conductor if it was irradiated with ultraviolet[22].Further studies revealed that this effect could be produced with visible radiation using an alkali metal electrode [23].Rectifying properties of semiconductor−metal contact were discovered by Ferdinand Braun in1874[24],when he probed a naturally−occurring lead sulphide(galena)crystal with the point of a thin metal wire and noted that current flowed freely in one direction only.Next,Jagadis Chandra Bose demonstrated the use of galena−metal point contact to detect millimetre electromagnetic waves.In1901he filed a U.S patent for a point−contact semiconductor rectifier for detecting radio signals[25].This type of contact called cat’s whisker detector(sometimes also as crystal detector)played serious role in the initial phase of radio development.How−ever,this contact was not used in a radiation detector for the next several decades.Although crystal rectifiers allowed to fabricate simple radio sets,however,by the mid−1920s the predictable performance of vacuum−tubes replaced them in most radio applications.The period between World Wars I and II is marked by the development of photon detectors and image converters and by emergence of infrared spectroscopy as one of the key analytical techniques available to chemists.The image con−verter,developed on the eve of World War II,was of tre−mendous interest to the military because it enabled man to see in the dark.The first IR photoconductor was developed by Theodore W.Case in1917[26].He discovered that a substance com−posed of thallium and sulphur(Tl2S)exhibited photocon−ductivity.Supported by the US Army between1917and 1918,Case adapted these relatively unreliable detectors for use as sensors in an infrared signalling device[27].The pro−totype signalling system,consisting of a60−inch diameter searchlight as the source of radiation and a thallous sulphide detector at the focus of a24−inch diameter paraboloid mir−ror,sent messages18miles through what was described as ‘smoky atmosphere’in1917.However,instability of resis−tance in the presence of light or polarizing voltage,loss of responsivity due to over−exposure to light,high noise,slug−gish response and lack of reproducibility seemed to be inhe−rent weaknesses.Work was discontinued in1918;commu−nication by the detection of infrared radiation appeared dis−tinctly ter Case found that the addition of oxygen greatly enhanced the response [28].The idea of the electro−optical converter,including the multistage one,was proposed by Holst et al.in1928[29]. The first attempt to make the converter was not successful.A working tube consisted of a photocathode in close proxi−mity to a fluorescent screen was made by the authors in 1934 in Philips firm.In about1930,the appearance of the Cs−O−Ag photo−tube,with stable characteristics,to great extent discouraged further development of photoconductive cells until about 1940.The Cs−O−Ag photocathode(also called S−1)elabo−History of infrared detectorsFig.3.Longley’s bolometer(a)composed of two sets of thin plati−num strips(b),a Wheatstone bridge,a battery,and a galvanometer measuring electrical current (after Ref. 15 and 16).rated by Koller and Campbell[30]had a quantum efficiency two orders of magnitude above anything previously studied, and consequently a new era in photoemissive devices was inaugurated[31].In the same year,the Japanese scientists S. Asao and M.Suzuki reported a method for enhancing the sensitivity of silver in the S−1photocathode[32].Consisted of a layer of caesium on oxidized silver,S−1is sensitive with useful response in the near infrared,out to approxi−mately1.2μm,and the visible and ultraviolet region,down to0.3μm.Probably the most significant IR development in the United States during1930’s was the Radio Corporation of America(RCA)IR image tube.During World War II, near−IR(NIR)cathodes were coupled to visible phosphors to provide a NIR image converter.With the establishment of the National Defence Research Committee,the develop−ment of this tube was accelerated.In1942,the tube went into production as the RCA1P25image converter(see Fig.4).This was one of the tubes used during World War II as a part of the”Snooperscope”and”Sniperscope,”which were used for night observation with infrared sources of illumination.Since then various photocathodes have been developed including bialkali photocathodes for the visible region,multialkali photocathodes with high sensitivity ex−tending to the infrared region and alkali halide photocatho−des intended for ultraviolet detection.The early concepts of image intensification were not basically different from those today.However,the early devices suffered from two major deficiencies:poor photo−cathodes and poor ter development of both cathode and coupling technologies changed the image in−tensifier into much more useful device.The concept of image intensification by cascading stages was suggested independently by number of workers.In Great Britain,the work was directed toward proximity focused tubes,while in the United State and in Germany–to electrostatically focused tubes.A history of night vision imaging devices is given by Biberman and Sendall in monograph Electro−Opti−cal Imaging:System Performance and Modelling,SPIE Press,2000[10].The Biberman’s monograph describes the basic trends of infrared optoelectronics development in the USA,Great Britain,France,and Germany.Seven years later Ponomarenko and Filachev completed this monograph writ−ing the book Infrared Techniques and Electro−Optics in Russia:A History1946−2006,SPIE Press,about achieve−ments of IR techniques and electrooptics in the former USSR and Russia [33].In the early1930’s,interest in improved detectors began in Germany[27,34,35].In1933,Edgar W.Kutzscher at the University of Berlin,discovered that lead sulphide(from natural galena found in Sardinia)was photoconductive and had response to about3μm.B.Gudden at the University of Prague used evaporation techniques to develop sensitive PbS films.Work directed by Kutzscher,initially at the Uni−versity of Berlin and later at the Electroacustic Company in Kiel,dealt primarily with the chemical deposition approach to film formation.This work ultimately lead to the fabrica−tion of the most sensitive German detectors.These works were,of course,done under great secrecy and the results were not generally known until after1945.Lead sulphide photoconductors were brought to the manufacturing stage of development in Germany in about1943.Lead sulphide was the first practical infrared detector deployed in a variety of applications during the war.The most notable was the Kiel IV,an airborne IR system that had excellent range and which was produced at Carl Zeiss in Jena under the direction of Werner K. Weihe [6].In1941,Robert J.Cashman improved the technology of thallous sulphide detectors,which led to successful produc−tion[36,37].Cashman,after success with thallous sulphide detectors,concentrated his efforts on lead sulphide detec−tors,which were first produced in the United States at Northwestern University in1944.After World War II Cash−man found that other semiconductors of the lead salt family (PbSe and PbTe)showed promise as infrared detectors[38]. The early detector cells manufactured by Cashman are shown in Fig. 5.Fig.4.The original1P25image converter tube developed by the RCA(a).This device measures115×38mm overall and has7pins.It opera−tion is indicated by the schematic drawing (b).After1945,the wide−ranging German trajectory of research was essentially the direction continued in the USA, Great Britain and Soviet Union under military sponsorship after the war[27,39].Kutzscher’s facilities were captured by the Russians,thus providing the basis for early Soviet detector development.From1946,detector technology was rapidly disseminated to firms such as Mullard Ltd.in Southampton,UK,as part of war reparations,and some−times was accompanied by the valuable tacit knowledge of technical experts.E.W.Kutzscher,for example,was flown to Britain from Kiel after the war,and subsequently had an important influence on American developments when he joined Lockheed Aircraft Co.in Burbank,California as a research scientist.Although the fabrication methods developed for lead salt photoconductors was usually not completely under−stood,their properties are well established and reproducibi−lity could only be achieved after following well−tried reci−pes.Unlike most other semiconductor IR detectors,lead salt photoconductive materials are used in the form of polycrys−talline films approximately1μm thick and with individual crystallites ranging in size from approximately0.1–1.0μm. They are usually prepared by chemical deposition using empirical recipes,which generally yields better uniformity of response and more stable results than the evaporative methods.In order to obtain high−performance detectors, lead chalcogenide films need to be sensitized by oxidation. The oxidation may be carried out by using additives in the deposition bath,by post−deposition heat treatment in the presence of oxygen,or by chemical oxidation of the film. The effect of the oxidant is to introduce sensitizing centres and additional states into the bandgap and thereby increase the lifetime of the photoexcited holes in the p−type material.3.Classification of infrared detectorsObserving a history of the development of the IR detector technology after World War II,many materials have been investigated.A simple theorem,after Norton[40],can be stated:”All physical phenomena in the range of about0.1–1 eV will be proposed for IR detectors”.Among these effects are:thermoelectric power(thermocouples),change in elec−trical conductivity(bolometers),gas expansion(Golay cell), pyroelectricity(pyroelectric detectors),photon drag,Jose−phson effect(Josephson junctions,SQUIDs),internal emis−sion(PtSi Schottky barriers),fundamental absorption(in−trinsic photodetectors),impurity absorption(extrinsic pho−todetectors),low dimensional solids[superlattice(SL), quantum well(QW)and quantum dot(QD)detectors], different type of phase transitions, etc.Figure6gives approximate dates of significant develop−ment efforts for the materials mentioned.The years during World War II saw the origins of modern IR detector tech−nology.Recent success in applying infrared technology to remote sensing problems has been made possible by the successful development of high−performance infrared de−tectors over the last six decades.Photon IR technology com−bined with semiconductor material science,photolithogra−phy technology developed for integrated circuits,and the impetus of Cold War military preparedness have propelled extraordinary advances in IR capabilities within a short time period during the last century [41].The majority of optical detectors can be classified in two broad categories:photon detectors(also called quantum detectors) and thermal detectors.3.1.Photon detectorsIn photon detectors the radiation is absorbed within the material by interaction with electrons either bound to lattice atoms or to impurity atoms or with free electrons.The observed electrical output signal results from the changed electronic energy distribution.The photon detectors show a selective wavelength dependence of response per unit incident radiation power(see Fig.8).They exhibit both a good signal−to−noise performance and a very fast res−ponse.But to achieve this,the photon IR detectors require cryogenic cooling.This is necessary to prevent the thermalHistory of infrared detectorsFig.5.Cashman’s detector cells:(a)Tl2S cell(ca.1943):a grid of two intermeshing comb−line sets of conducting paths were first pro−vided and next the T2S was evaporated over the grid structure;(b) PbS cell(ca.1945)the PbS layer was evaporated on the wall of the tube on which electrical leads had been drawn with aquadag(afterRef. 38).。

2023届高考英语阅读理解专练(6)科教科普类

（6）科教科普类一、An extremely rare manuscript(手稿) signed by English naturalist Charles Darwin is expected to fetch up to $790,000 at a Sotheby's auction next month.The document contains a passage from the famous 1859 work On the Origin of Species, in which Darwin put forth his theory of evolution. The document was once thought to be a deserted page from an earlier manuscript of the work. But experts now understand it was written in 1865 and sent to the editor of the Autographic Mirror who had requested a signed writing sample from Darwin."While some of Darwin's notes and manuscript pages have survived over the last hundred or more years, he was known to keep revising his publications, often throwing away pages from working drafts as waste paper, making them extremely rare," Sotheby's said in a statement.On the Origin of Species was voted the most influential academic book of all time in a public poll held during Academic Book Week in 2015. The book offers Darwin's revolutionary idea that species evolve over generations in the process of natural selection.Darwin backed up his theory with evidence collected during his 1831-1836 voyage on the H.M.S. Beagle, during which he observed and collected specimens(标本)from a number of species. On the Galapagos Islands off the coast of Ecuador, Darwin noted that the finches(鸣雀) on the island were similar to finches on the mainland; however, the availability of different foods in each area had led to differences in beak shapes. The manuscript will be placed on display at Sotheby's in New York between Nov.30 and Dec 8, and online bids will be accepted between Nov. 25 and Dec. 8. The auction house estimates that the document will fetch between $600,000 and $790,000. The auction, which is titled Age of Wonder, will also include a first edition of On the Origin of Species and a copy of scientific paper by Darwin and another naturalist.1.What do we know about the manuscript?A.It's a page of On the Origin of Species.B.It's a draft of Darwin's scientific paper.C.It's a signed writing sample to an editor.D.It's waste paper from Darwin's study.2.What makes Darwin's On the Origin of Species the most influential academic book?A. His methods of research.B. His adventure on the sea.C. The rare manuscript.D. His theory of evolution.3.What does the underlined phrase "backed up" mean in Paragraph 5?A. supportedB.explainedC.declaredD.created4.What is the purpose of the auction?A. To put the manuscript on sale.B. To display Darwin's works.C. To vote the best academic books.D. To release a new discovery.二、Researchers from Singapore said in their new study that in older adults, doing housework was tied to a better memory and attention span, and stronger legs, which helps prevent falls. Shiou-Liang Wee, a researcher said, “Housework is a purposeful activity performed by many older adults and represents a significant share of their self-reported physical activity.”For the study, Wee’s team investigated nearly 500 healthy Singaporeans between 21 and 90 years of age. Among younger participants, 36% said they engaged in enough physical activity to meet the goal researchers set as beneficial, as did 48% of older participants. But 61% of younger and 66% of older participants met this target only through housework, the study revealed.After taking other types of regular physical activity into consideration, the researchers found that housework was tied with sharper mental abilities and better physical capacity, but only among the older participants. Scores on tests of mental ability were as much as 8% higher among those who did lots of housework, compared with those who did little, Lee’s team found.And among older participants, balance and the time it took to stand up from sitting, which the investigators used as an indication of physical ability, were better for those who did lots of housework than for those who didn’t.Dr. Maria Carney, chief of geriatric(老年病的) medicine at Northwell Health, N.Y., noted that exercise benefits your brain, and housework is exercise that also involves mental activity and requires detailed thought processes to complete. Physical activity increases blood circulation to your muscles and your brain, which helps mental function. Housework can be an important part of your exercise routine. Carney said, “It’s a task you’ve got to plan for. You’ve got to use devices; you’ve got to use equipment. There’s planning involved, so there’s mental exercise along with physical exercise.”5.According to Paragraph 1, what do we know about the study?A. Older adults benefit from doing housework.B. Older adults doing housework do not fall.C. Doing housework is a rising trend in Singapore.D. Doing housework is older adults’ favorite exercise.6.Which of the following was considered in the study by the researchers?A. Participants’ ages, sexes and occupations.B. Goals of physical ability participants set.C. Ways in which participants do housework.D. Types of physical activity participants do.7.What are the research findings based on?A. Research data.B. Scientific theory.C. Related documents.D. Daily observation.8.What is the last paragraph mainly about?A. Why tools are used in doing housework.B. How housework works for mental ability.C. What physical activities should be done.D. Who are more suitable to do housework.三、We all know that unpleasant feeling when we’re talking about something interesting and halfway through our sentence we’re interrupted. But was that really an interruption? The answer depends on whom you ask, according to new research led by Katherine Hilton from Stanford University.Using a set of controlled audio clips (录音片段), Hilton surveyed 5,000 American English speakers to better understand what affects people’s perceptions of interruptions. She had participants listen to audio clips and then answer questions about whether the speakers seemed to be friendly and engaged, listening to one another, or trying to interrupt.Hilton found that American English speakers have different conversational styles. She identified two distinct groups: high and low intensity speakers. High intensity speakers are generally uncomfortable with moments of silence in conversation and consider talking at the same time a sign of engagement. Low intensity speakers find it rude to talk at the same time and prefer people speak one after another in conversation.The differences in conversational styles became evident when participants listened to audio clips in which two people spoke at the same time but were agreeing with each other and stayed on topic, Hilton said. The high intensity group reported that conversations where people spoke at the same time when expressing agreement were not interruptive but engaged and friendlier than the conversations with moments of silence in between speaking turns. In contrast, the low intensity group perceived any amount of simultaneous (同时) chat as a rude interruption, regardless of what the speakers were saying.“People care about being interrupted, and those small interruptions can have a massive effect on the overall communication,” Hilton said. “Breaking apart what an interruption means is essential if we want to understand how humans interact with each othe r.”9.What does Hilton’s research focus on?A. What interruptions mean to people.B. Whether interruption is good or not.C. How to avoid getting interrupted.D. Why speakers interrupt each other.10.What do participants of the study need to do?A. Record an audio clip.B. Answer some questions.C. Listen to one another.D. Have a chat with a friend.11.What do low intensity speakers think of simultaneous chat?A. It’s important.B. It’s interesting.C. It’s inefficient.D. It’s impolite.12.What can we l earn from Hilton’s research?A. Human interaction is complex.B. Communication is the basis of life.C. Interruptions promote thinking.D. Language barriers will always exist. 四、It is generally acknowledged that the older we get the more slowly we react. However, the new findings suggest that mental speed—the speed at which we can deal with issues requiring rapid decision-making—does not change substantially over decades.Under the leadership of Dr Mischa von Krause and Dr Stefan Radev, psychologists at Heidelberg University evaluated data from a large-scale online experiment with over a million participants. They came to the conclusion that the speed of cognitive information processing remains largely stable between the ages of 20 and 60, and onlydeteriorates at higher ages.In the online experiment, subjects had to press a button to sort pictures of people into the categories “white” or “black” and words into the categories “good” or “bad”. According to Dr Mischa von Krause, the content focus was of minor importance. Instead, the researchers used the large number of data as an example of a response-time task to measure the duration of cognitive decisions.When evaluating the data, Dr Mischa von Krause and his colleagues noted that, on average, the response time of the test subjects rose with increasing age. However, with the aid of a mathematical model, they were able to show that this phenomenon was not due to changes in mental speed. They think that older test subjects are slower mainly because they reply more cautiously and concentrate more on avoiding mistakes. At the same time, motor function speed slows down during the course of adult life: older participants in the experiment needed longer to press the appropriate key after they had found the right answer.Another finding of the study was that average information processing speed only progressively declined with participants over the age of 60. “It looks as though, in the course of our life, we don’t need to fear any substantial los ses of mental speed—particularly not in the course of a typical working life,” says Dr Mischa von Krause.13.What is the common assumption about the adults’ mental speed?A. It declines with age.B. It is faster at the old age.C. It is not affected by the age.D. It is constantly changing with age.14.What does the underlined word “deteriorates” in Paragraph 2 mean?A. Stays stable.B. Becomes worse.C. Changes suddenly.D. Increases rapidly.15.What does Dr Mischa von Krause think causes the older subject s’ response time to rise?A. Their emotional stability.B. The decline of mental speed.C. Their mature and cautious nature.D. The lack of exercise for the older.16.What is the purpose of the text?A. To describe an online experiment.B. To appeal to people to respect the elderly.C. To tell people how to improve mental speed.D. To reveal the conclusion of an online experiment.五、I’ve just asked Julie Gray, a biologist at the University of Sheffield, which species she thinks would be the last one s standing if we don’t take transformative(变革性的) action on climate change. “I don’t think it will be humans. I think we’ll go quite early on,” says Gray. Humans probably won’t be among the survivors, partly because humans produce young extremely slowly and generally just one or two at a time.It may seem like just a thought experiment. But discussing which species are able to survive climate change is disturbingly concrete. As a report stated recently, one in four species currently faces extinction, which is closely linked to climate change. While the seriousness of climate change is undeniable, we can make some educated guesses about which species will have a better shot at going far.According to Jen Lau, a biologist at University Bloomington, heat tolerant and drought resistant plants, like those found in deserts, are more likely to survive. So are plants whose seeds can be spread over long distances, for example by wind or ocean currents. Plants that can adjust their flowering times may also be better able to deal with higher temperatures.We can also look to history as a guide. Cockroaches(蟑螂) adapted to an increasingly dry Australia tens of millions of years ago, by starting to dig holes in soil to hide. Cockroaches also tend to not be picky eaters. Having broad diets means that climate change will be less of a threat to them.Furthermore, species called “mobile generalists” by experts can move and adapt to different environments and are more likely to last long in face of climate change. For example, deer in the US are common in suburban areas and manage to live where forests have been removed or are regularly disturbed.Certainly, some animals would also survive if they could find a buffer: an area that is relatively protected fro m climate change’s consequences, such as deep sea canyons(峡谷), underground caves.17.What does the author probably think of the answer given by Gray?A. Ridiculous.B. Unreasonable.C. Upsetting.D. Exciting.18.Which of the following can replace the underlined part in Paragraph 2?A. Peacefully wait.B. Quickly die out.C. Greatly change.D. Possibly survive.19.Which of the following species is likely to survive climate change?A. Trees growing in the rainforest and flowering at fixed time every year.B. Animals good at digging holes and not particular about food.C. Creatures mainly living in trees and spending most time sleeping.D. Fishes that do not enjoy deep diving and like to stay in a bay.20.Which of the following is the best title for the text?A. How Climate Will Change in the FutureB. What Species May Survive Climate ChangeC. Why Some Species Have Broader DietsD. Where Species Can Hide in Climate Change六、Humans have always assumed that there is a huge gulf between animal behavior and human development. However, recent research into animals shows that animals are continuously designing innovative methods to finish their tasks. Examining the nature and results of their creativity can help us understand evolution.Research shows that animals can also be creative. By inventing new behavioral patterns and adjusting their behavior to new contexts, as well as to changes in social and ecological environments, researchers show that animal innovation can also be diverse. For instance, chimpanzees(黑猩猩) use tools such as sharp spines and stalks to remove the hearts of palm vegetables from trees. Herring gulls(鸥) find out quite a cruel way of killing rabbits-drowning them in the sea.Innovative species tend to survive when they enter new places, but novel behavior cannot be recognized unless "normal" behavior is studied. Researchers can now count and document the innovations that have been created by species, which would help them to quantify their creativity. Studies also show us that all animals are not equally inventive, with primates(灵长类) tending to be more innovative due to their bigger brains.The greatest scientific significance has been the innovation shown by animals such as apes, capuchins and macaques among primates. These species of primates possess the biggest brains compared to their body sizes. They are also heavy tool users. Their broad diets and complex forms of learning are also insightful. They show an evolutionary strategy that gives them new solutions to life's challenges.However, even if these animals show innovativeness, they do not have the ability to improve upon the solutions of others. Unless they share information accurately andcopy each others' inventions, their creative inventions are likely to disappear before they can be innovated further. This ability can be managed only by humans, for we are able to build on shared knowledge.21.What does the underlined word "gulf" in the first paragraph mean?A. Difference.B. Conflict.C. Balance.D. Connection.22.Why does the author mention "chimpanzees" and "herring gulls" in paragraph 2?A. To explain a rule.B. To support a viewpoint.C. To explain a natural phenomenon.D. To compare the two species.23.What aspect of animals does the last paragraph mainly talk about?A. Their failure to share information accurately.B. Their unwillingness to learn from each other.C. Their inability to take creativity forward.D. Their ability to cooperate effectively.24.Where is this text most likely from?A. A biography.B. A book review.C. A short story.D. A science report.七、In habitats across the planet, animals periodically drop everything to walk, fly or swim to a new place. Wildlife such as whales and geese learn migration paths by following their parents. Others, including small songbirds, gain the distance and direction of their migration within their genetic code. And some animals use a combination of genetics and culture to guide their migration.Another group of migrators does not quite fit either model, and researchers have only recently started to figure out how they find their way. Take the Cory’s shearwater, an oceangoing sea bird that migrates over the Atlantic every year. The young do not migrate with their parents, so culture cannot explain their journeys. And the exact paths vary wildly from individual to individual, making genetics equally unlikely. Cory’s shearwaters are long-lived, rarely producing young successfully before age nine. This leaves an opening for learning and practice to develop their migration patterns. Researchers call this the “exploration-refinement”, and until now it has been hypothetical (假设的) because of difficulties in tracking migratory animals’ movements.But a team of researchers has done that by attaching small geolocators to more than150 of the birds aged four to nine. They found that younger birds traveled longer distances, for longer periods, and had more diverse paths than older birds. “We finally have evidence of the ‘exploratio n-refinement’ for migratory birds,” says Letizia Campioni, who led the study. Younger Cory’s shearwaters are able to fly just as fast as the adults—but they do not, suggesting that the young do more exploring, which gradually fades as they mature and settle into a preferred course.Although it may seem less efficient than other strategies, “exploration refinement could be beneficial to birds and other organisms in a rapidly changing world due to unpredictable man-made changes,” says Barbara Frei. “It mi ght be safer to repeat a behavior that was recently successful than to rely on patterns that were perfected long ago but might no longer be safe.”25.What is the first paragraph mainly about?A.It describes animals’ habitats.B.It talks about migration models.C.It compares different species.D.It introduces a tracking technology.26.What does the underlined word “this” in paragraph 3 refer to?A.The opening for learning and practice.B.The unique living habit of Cory’s shearwaters.C.The way Cory’s shea rwaters form their migration patterns.D.The process scientists track Cory’s shearwaters’ movements.27.What does Letizia’s study find about the younger Cory’s shearwaters?A.They travel as much as adult birds.B.They move in a predictable manner.C.They lower the speed for exploration.D.They look for a course with their parents.28.What can we conclude from the last paragraph?A.Man-made changes make migration easier.B.Animals make a safer journey via a fixed track.C.Course exploration contributes to birds’ adaptability.D.A combination of strategies assures migration success.八、A good conversation should proceed like a tennis match: players each take turns responding, knowing instinctively(本能)when to speak and when to listen. This kind of complicated and back-and-forth talk is often considered to be possessed only byhumans. However, according to a recent study, animals also seem to know when to speak and when to listen.The study involved over 300 animals including birds, mammals(哺乳动物), insects, and frogs which practice turn-taking behavior. These animals alternate their call and response in a similar way humans communicate. Monkeys, for example, often exchange calls to locate each other in the wild and figure out whether they know one another.While forms of communication are mostly sound-based, several species have more creative forms of viewable communication. Baby monkeys let their parents know they want to be carried with arm gestures, while birds, insects and frogs can get their messages across through colorful displays.Kobin Kendrick, the main co-author on the study, says that making comparisons among animals that take turns when communicating can give us a better understanding of how this feature evolved in humans and our ancestors. "We know very little about the evolution and origin of the human language, so any possibility of gaining insight into it is worth going after," he says.Additionally, while the idea of turn-taking might bring to mind a picture of orderly, well-mannered animals, Kendrick stresses that this isn't always the case. Owl(猫头鹰) chicks may try to outdo each other by making louder sounds in an effort to attract favor from their mothers during feeding. "This can be seen as an exception to the rule, highlighting the importance of turn-taking in general," says Kendrick.One problem with the study is that researchers themselves don't know how to communicate with others outside their particular species of interest. Kendrick stresses another goal of the study is to create a wider framework that can bring together all the different researches on turn-taking, allowing scientists to conduct more cross-species comparisons. "We all believe strongly these fields can benefit from each other, and we hope the study will drive more cross talk between humans and animals in the future," says Kendrick.29.What can we learn about the turn-taking behavior?A. It is a unique human quality.B. It is an acquired athletic skill.C. It occurs between familiar relations.D. It features complexity and interaction.30.Which of the following is a form of visual intercommunication?A.Frogs show skin colors.B. Bees release smells.C. Eagles scream in the sky.D. Monkeys exchange calls.31.Why are "owl chicks" mentioned in paragraph 5?A. To propose a definition.B. To give a contrast.C. To present an argument.D. To make a prediction.32.What aspect of research does the last paragraph highlight?A. Research budget.B. Research range.C. Research frequency.D. Research background.答案以及解析一、1.答案：C解析：细节理解题。

Aspects of the Heavy-Quark Photoproduction in the Semihard Approach

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dz d2 p1⊥ d2 k⊥
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× [z 2 + (1 − z )2 ]

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,
(2)
2 2 2 where D1 ≡ p2 1⊥ + mQ and D2 ≡ (k⊥ − p1⊥ ) + mQ . Here, αem = 1/137 is the electromagnetic coupling constant and eQ is the electric charge of the produced heavy-quark. Details on the relevant variables and kinematics can be found at [8]. The scale µ in the strong coupling constant in general is taken to be equal to the gluon virtuality, µ2 = k2 , in close connection with the BLM scheme [12]. In the leading ln(1/x) approximation, αs should take a constant value. When the transverse momenta of the incident partons are suﬃciently smaller than those from the produced heavy-quarks, the result from the collinear approach is recovered. In Eq. (2) the unintegrated gluon function was allowed to depend also on the scale µ2 , 2 taken here as µ2 = p2 ⊥ + mQ , since some parametrizations take this scale into account in the

应用光伏学题库

一、选择题（在下列每题的四个选项中，只有一个选项是符合试题要求的。

请把答案填入答题框中相应的题号下。

每小题1分，共10分）二、填空题（本大题共10小题，每小题1分，共10分）§01. ★Photovoltaics (often abbreviated as PV ) is a simple and elegant method of harnessing the sun's energy .2. ★PV devices (solar cells) are unique in that they directly convert the incident solar radiation into electricity , with no noise, pollution or moving parts, making them robust, reliable and long lasting.3. ★Photovoltaics is the process of converting sunlight directly into electricity using solar cells .4. ★The first photovoltaic device was demonstrated in 1839 by Edmond Becquerel, as a young 19 year old working in his father‘s laboratory in Fra nce.5. ★The first practical photovoltaic device was demonstrated in the 1950s.6. ★★Research and development of photovoltaics received its first major boost from the space industry in the 1960s.§11. ★A photon is characterized by either a wavelength, denoted by λ, or equivalently an energy, denoted by E.2. ★★There is an inverse relationship between the energy of a photon (E ) and the wavelength of the light (λ) given by the equation: ，.3. ★★The photon flux is defined as the number of photons per second per unit area.4. ★★★The total power density emitted from a light source can be calculated by integrating the spectral irradiance over all wavelengths or energies of interest.5. ★★In the analysis of solar cells, the photon flux is often needed as well as the spectral irradiance.6. ★The blackbody sources which are of interest to photovoltaics, emit light in the visible region.7. ★★★The spectral irradiance from a blackbody is given by Plank's radiation law.8. ★★The peak wavelength of the spectral irradiance is determined by differentiating the spectral irradiance and solving the derivative when it equals 0. The result is known as Wien‗s Law: ()2900p m T λμ=.9. ★★★Solar radiation in space: sun H D R H ⨯=220.H sun =5.961×107W/m 2.10. ★The solar radiation outside the earth's atmosphere have been defined as a standard value called air masszero (AM0) and takes a value of 1.353 kW/m 2.11. ★The spectral irradiance from a blackbody at 6000 K (at the same apparent diameter as the sun when viewedfrom earth); from the sun‘s photosphere as observed just outside earth‘s atmosphere (AM0); and from the sun‘s photosphere after having passed through 1.5 times the thickness of earth‘s atmosphere (AM1.5G).12. ★★The Air Mass is defined as: ()θcos 1AM =,2h s 1AM ⎪⎭⎫ ⎝⎛+=. where θ is the angle from the vertical (zenithangle).13. ★★When the sun is directly overhead, the Air Mass is 1.14. ★The standard spectrum at the Earth's surface is called AM1.5G (the G stands for global and includes bothdirect and diffuse radiation) or AM1.5D (which includes direct radiation only), these calculations give approximately 970 W/m 2 for AM1.5G 。

Photobioreactors for mass cultivation of algae

ReviewPhotobioreactors for mass cultivation of algaeC.U.Ugwu *,H.Aoyagi,H.UchiyamaInstitute of Life Sciences and Bioengineering,University of Tsukuba,1-1-1Tennodai,Tsukuba City,Ibaraki 305-8572,JapanReceived 16October 2006;received in revised form 30January 2007;accepted 31January 2007Available online 26March 2007AbstractAlgae have attracted much interest for production of foods,bioactive compounds and also for their usefulness in cleaning the envi-ronment.In order to grow and tap the potentials of algae,eﬃcient photobioreactors are required.Although a good number of photo-bioreactors have been proposed,only a few of them can be practically used for mass production of algae.One of the major factors that limits their practical application in algal mass cultures is mass transfer.Thus,a thorough understanding of mass transfer rates in pho-tobioreactors is necessary for eﬃcient operation of mass algal cultures.In this review article,various photobioreactors that are very promising for mass production of algae are discussed.Ó2007Elsevier Ltd.All rights reserved.Keywords:Algae;Biomass;Mass transfer;Mixing;Photobioreactors1.IntroductionAlgae are grown either in open culture systems or closed systems (photobioreactors).Early attempts to grow algae in open ponds were conceived by Germans (Europe)during the world war II.At that time,algae were grown mainly as food supplements.As industrialization began,some groups of workers in Carnegie Institute at Washington imple-mented mass cultivation of algae for CO 2abatement (Bur-lew,1953).Between early 1970s and late 1970s,commercial production of algae was initiated in East Europe,Israel and Japan.During these periods,algae were grown commer-cially in open ponds as healthy food.In Africa,Lake Chad and Lake Texcoco were the major sources of Spirulina bio-mass for the people living in those areas.As a matter of fact,the purpose of growing algae depended on the speciﬁc needs of the people.In the United States,algal pond sys-tems were developed for water treatment.The biomass recovered was converted to methane,which was a major source of energy (Burlew,1953;Oswald and Golueke,1960).As time went on,algal biomass became very impor-tant in the ﬁeld of aquaculture (Muller-Feuga,2000).Recently,algae have attracted much attention due to their potentials in the production of ﬁne chemicals (Borowitzka,1999;Lorenz and Cysewski,2000)and as useful supple-ments in humans and animals (Dallaire et al.,2007).Algae have also found application in other areas such as in immo-bilization systems for production of some extracellular compounds (Chetsumon et al.,1994),and also for biosorp-tion of heavy metals (Wilde and Benemann,1993;Lodeiro et al.,2005;Karthikeyan et al.,2007).Some studies have also indicated the importance of algae in carbon dioxide ﬁxation (Benemann,1997;Sung et al.,1999;Chae et al.,2006).Given the advantages of closed systems over open ponds,a good number of them (ranging from laboratory to industrial scale)photobioreactors have been proposed.Closed photobioreactors have attracted much interest because they allow a better control of the cultivation con-ditions than open systems.With closed photobioreactors,higher biomass productivities are obtained and contamina-tion can be easily prevented.It is anticipated that algal bio-technology would pave way to the development of Closed Ecological Life Support System (CELSS)(Lee and Palsson,1995;Cogne et al.,2005).Despite that a good number of0960-8524/$-see front matter Ó2007Elsevier Ltd.All rights reserved.doi:10.1016/j.biortech.2007.01.046*Corresponding author.Tel./fax:+81298537212.E-mail address:cugwu@.tsukuba.ac.jp (C.U.Ugwu).Available online at Bioresource Technology 99(2008)4021–4028photobioreactors have been investigated,only very few of them can eﬀectively utilize solar energy for mass produc-tion of algae.One of the major setbacks in mass production of algae is lack of eﬃcient photobioreactors.To improve algal productivity,a thorough understanding of some aspects of hydrodynamic and mass transfer of photobiore-actors is required.Most outdoor photobioreactors are characterized by largely exposed illumination surfaces.From this point of view,ﬂat-plate,horizontal and inclined tubular photobior-eactors are promising except for the diﬃculty in scaling them up.Photobioreactors such as bubble-column,airlift, and stirred-tank have good scalability though their use in outdoor cultures is limited since they have low illumination surface areas.In this review article,some photobioreactor designs that are promising for mass cultivation of algae are critically examined.Furthermore,some aspects of hydrodynamics and mass transfer characteristics of these photobioreactors are brieﬂy discussed.2.PhotobioreactorsAlgal culture systems can be illuminated by artiﬁcial light,solar light or by both.Naturally illuminated algal culture systems with large illumination surface areas include open ponds(Hase et al.,2000),ﬂat-plate(Hu et al.,1996),horizontal/serpentine tubular airlift(Camacho Rubio et al.,1999),and inclined tubular photobioreactors (Ugwu et al.,2002).Generally,laboratory-scale photobior-eactors are artiﬁcially illuminated(either internally or externally)usingﬂuorescent lamps or other light distribu-tors.Some of these photobioreactors include bubble col-umn(Degen et al.,2001;Ogbonna et al.,2002;Chini Zittelli et al.,2003),airlift column(Harker et al.,1996; Kaewpintong et al.,2007),stirred-tank(Ogbonna et al., 1999),helical tubular(Hall et al.,2003),conical(Watanabe and Saiki,1997),torus(Pruvost et al.,2006),and seaweed-type(Chetsumon et al.,1998)photobioreactors.Furthermore,some photobioreactors can be easily tem-pered.Tempering could simply be achieved by placing a photobioreactor in a constant temperature room.This approach is limited to compact rge-scale outdoor systems such as tubular photobioreactors cannot be easily tempered without high technical eﬀorts. However,several commercially available photobioreactors, for example,BIOSTAT photobioreactors(developed by Sartorius BBI Systems Inc.)can be readily tempered.Also, some eﬀorts were undertaken to design temperature-con-trolled photobioreactors,such as double-walled inter-nally-illuminated photobioreactor with a heating and cooling water circuit(Pohl et al.,1988).2.1.Open pondsCultivation of algae in open ponds has been extensively studied in the past few years(Boussiba et al.,1988;Tredici and Materassi,1992;Hase et al.,2000).Open ponds can be categorized into natural waters(lakes,lagoons,ponds)and artiﬁcial ponds or containers.The most commonly used sys-tems include shallow big ponds,tanks,circular ponds and raceway ponds.One of the major advantages of open ponds is that they are easier to construct and operate than most closed systems.However,major limitations in open ponds include poor light utilization by the cells,evaporative losses, diﬀusion of CO2to the atmosphere,and requirement of large areas of land.Furthermore,contamination by preda-tors and other fast growing heterotrophs have restricted the commercial production of algae in open culture systems to only those organisms that can grow under extreme condi-tions.Also,due to ineﬃcient stirring mechanisms in open cultivation systems,their mass transfer rates are very poor resulting to low biomass productivity.Table1summarizes the advantages and limitations of open ponds.Table1Prospects and limitations of various culture systems for algaeCulture systems Prospects LimitationsOpen ponds Relatively economical,easy to clean up aftercultivation,good for mass cultivation of algae Little control of culture conditions,diﬃculty in growing algal cultures for long periods,poor productivity,occupy large land mass,limited to few strains of algae,cultures are easily contaminatedVertical-column photobioreactors High mass transfer,good mixing with low shear stress,low energy consumption,high potentials forscalability,easy to sterilize,readily tempered,good forimmobilization of algae,reduced photoinhibition andphoto-oxidation Small illumination surface area,their construction require sophisticated materials,shear stress to algal cultures,decrease of illumination surface area upon scale-upFlat-plate photobioreactors Large illumination surface area,suitable for outdoorcultures,good for immobilization of algae,good lightpath,good biomass productivities,relatively cheap,easy to clean up,readily tempered,low oxygen build-up Scale-up require many compartments and support materials,diﬃculty in controlling culture temperature, some degree of wall growth,possibility of hydrodynamic stress to some algal strainsTubular photobioreactors Large illumination surface area,suitable for outdoorcultures,fairly good biomass productivities,relativelycheap Gradients of pH,dissolved oxygen and CO2along the tubes,fouling,some degree of wall growth,requires large land space4022 C.U.Ugwu et al./Bioresource Technology99(2008)4021–4028In order to overcome the problems with open ponds, much attention is now focused on development of suitable closed systems such asﬂat-plate,tubular,vertical-column and internally-illuminated photobioreactors.2.2.Flat-plate photobioreactorsFlat-plate photobioreactors have received much atten-tion for cultivation of photosynthetic microorganisms due to their large illumination surface area.The work presented by Milner(1953)paved way to the use ofﬂat culture vessels for cultivation of algae.Following this work,Samson and Leduy(1985)developed aﬂat reactor equipped withﬂuo-rescence lamps.A year later,Ramos de Ortega and Roux (1986)developed an outdoorﬂat panel reactor by using thick transparent PVC materials.As time went on,exten-sive works on various designs of vertical alveolar panels andﬂat plate reactors for mass cultivation of diﬀerent algae were reported(Tredici and Materassi,1992;Hu et al.,1996; Zhang et al.,2002;Hoekema et al.,2002).Generally,ﬂat-plate photobioreactors are made of transparent materials for maximum utilization of solar light energy.Accumula-tion of dissolved oxygen concentrations inﬂat-plate photo-bioreactors is relatively low compared to horizontal tubular photobioreactors.It has been reported that with ﬂat-plate photobioreactors,high photosynthetic eﬃciencies can be achieved(Hu et al.,1996;Richmond,2000).Flat-plate photobioreactors are very suitable for mass cultures of algae.However,they also have some limitations as indi-cated in Table1.2.3.Tubular photobioreactorsAmong the proposed photobioreactors,tubular photo-bioreactor is one of the most suitable types for outdoor mass cultures.Most outdoor tubular photobioreactors are usually constructed with either glass or plastic tube and their cultures are re-circulated either with pump or preferably with airlift system.They can be in form of hor-izontal/serpentine(Chaumont et al.,1988;Molina et al., 2001),vertical(Pirt et al.,1983),near horizontal(Tredici and Chini Zittelli,1998),conical(Watanabe and Saiki, 1997),inclined(Lee and Low,1991;Ugwu et al.,2002) photobioreactor.Aeration and mixing of the cultures in tubular photobi-oreactors are usually done by air-pump or airlift systems. Advantages and limitations of tubular photobioreactors are shown in Table1.Tubular photobioreactor are very suitable for outdoor mass cultures of algae since they have large illumination surface area.On the other hand,one of the major limitations of tubular photobioreactor is poor mass transfer.It should be noted that mass transfer(oxy-gen build-up)becomes a problem when tubular photobior-eactors are scaled up.For instance,some studies have shown that very high dissolved oxygen(DO)levels are eas-ily reached in tubular photobioreactors(Torzillo et al., 1986;Richmond et al.,1993;Molina et al.,2001).Also,photoinhibition is very common in outdoor tubu-lar photobioreactors(Vonshak and Torzillo,2004).When a tubular photobioreactor is scaled up by increasing the diameter of tubes,the illumination surface to volume ratio would decrease.On the other hand,the length of the tube can be kept as short as possible while a tubular photobior-eactor is scaled up by increasing the diameter of the tubes. In this case,the cells at the lower part of the tube will not receive enough light for cell growth(due to light shading eﬀect)unless there is a good mixing system.In any case, eﬃcient light distribution to the cells can be achieved by improving the mixing system in the tubes(Ugwu et al., 2003,2005a).Also,it is diﬃcult to control culture temperatures in most tubular photobioreactors.Although they can be equipped with thermostat to maintain the desired culture temperature,this could be very expensive and diﬃcult to implement.It should also be noted that adherence of the cells of the walls of the tubes is common in tubular photobioreactors.Furthermore,long tubular photobioreactors are charac-terized by gradients of oxygen and CO2transfer along the tubes(Camacho Rubio et al.,1999;Ugwu et al.,2003).The increase in pH of the cultures would also lead to frequent re-carbonation of the cultures,which would consequently increase the cost of algal production.2.4.Vertical-column photobioreactorsVarious designs and scales of vertical-column photobi-oreactors have been tested for cultivation of algae(Choi et al.,2003;Vega-Estrada et al.,2005;Garcı´a-Malea Lo´pez et al.,2006;Kaewpintong et al.,2007).Vertical-column photobioreactors are compact,low-cost,and easy to oper-ate monoseptically(Sa´nchez Miro´n et al.,2002).Further-more,they are very promising for large-scale cultivation of algae.It was reported that bubble-column and airlift photobioreactors(up to0.19m in diameter)can attain a ﬁnal biomass concentration and speciﬁc growth rate that are comparable to values typically reported for narrow tubular photobioreactors(Sa´nchez Miro´n et al.,2002). Some bubble column photobioreactors are equipped with either draft tubes or constructed as split cylinders.In the case of draft tube photobioreactors,intermixing occurs between the riser and the downcomer zones of the photobi-oreactor through the walls of the draft tube.A summary of the prospects and limitations of vertical-column photobior-eactors is shown in Table1.2.5.Internally-illuminated photobioreactorsAs mentioned earlier,some photobioreactors can be internally illuminated withﬂuorescent lamps.Fig.1shows a typical internally-illuminated photobioreactor.The pho-tobioreactor is equipped with impellers for agitation of the algal cultures.Air and CO2are supplied to the cultures through the spargers.This type of photobioreactor can alsoC.U.Ugwu et al./Bioresource Technology99(2008)4021–40284023be modiﬁed in such a way that it can utilize both solar and artiﬁcial light system(Ogbonna et al.,1999).In that case, the artiﬁcial light source is switched on whenever the solar light intensity decreases below a set value(during cloudy weather or at night).There are also some reports on the use of opticﬁbers to collect and distribute solar light in cylindrical photobioreactors(Mori,1985;Matsunaga et al.,1991).One of the major advantages of internally-illu-minated photobioreactor is that it can be heat-sterilized under pressure and thus,contamination can be minimized. Furthermore,supply of light to the photobioreactor can be maintained continuously(both day and night)by integrat-ing artiﬁcial and solar light devices.However,outdoor mass cultivation of algae in this type of photobioreactor would require some technical eﬀorts.3.Hydrodynamics and mass transfer characteristics of photobioreactorsAlthough relationship between hydrodynamics and mass transfer has been extensively investigated and corre-lated in bioreactors for heterotrophic cultures,only a few studies on these aspects are available in phototrophic cul-tures.Hydrodynamics and mass transfer characteristics that are applicable in photobioreactors include;the overall mass transfer coeﬃcient(k L a),mixing,liquid velocity,gas bubble velocity and gas holdup.The overall mass transfer coeﬃcient(k L a)is the most commonly used parameters for assessing the performance of photobioreactors.The term k L a is generally used to describe the overall volumetric mass transfer coeﬃcient in photobioreactors.The volumetric mass transfer coeﬃcient (k L a)of photobioreactors is dependent on various factors such as agitation rate,the type of sparger,surfactants/anti-foam agents and temperature.Mixing time can be deﬁned as the time taken to achieve a homogenous mixture after injection of tracer solution. Lee and Bazin(1990)deﬁnes mixing time as the time taken for a small volume of dye solution added to the liquid to transverse the reactor.Generally,mixing time is deter-mined in photobioreactors using tracer substances such as dyes.However,mixing time can also be measured by sig-nal-response method using tracer and pH electrode(Cam-acho Rubio et al.,1999;Ugwu et al.,2003;Pruvost et al.,2006).Furthermore,computationalﬂuid dynamics(CFD) was used to evaluate global mixing in torus photobioreac-tor(Pruvost et al.,2006;Sato et al.,2006).Mixing time is a very important parameter in designing photobioreactors for various biological processes.Good mixing would ensure high cell concentration,keep algal cells in suspension,eliminate thermal stratiﬁcation,help nutrient distribution,improve gas exchange as well as reduce the degree of mutual shading and lower the proba-bility of photoinhibition(Janvanmardian and Palsson, 1991).It was also reported that when the nutritional requirements are suﬃcient and the environmental condi-tions are optimized,mixing aimed at inducing turbulent ﬂow would result in high yield of algal biomass(Hu et al.,1996).Bosca et al.(1991)demonstrated that the pro-ductivity of alga is higher in mixed culture than in an unmixed one under the same condition.Various mixing systems are currently used in algal cultures depending on the type of photobioreactors.In open pond systems,paddle wheels were used to induce turbulentﬂow(Boussiba et al., 1988;Hase et al.,2000).In stirred-tank photobioreactors, impellers were used in mixing algal cultures(Ogbonna et al.,1999;Mazzuca Sobczuk et al.,2006).In tubular pho-tobioreactors,mixing can be done by bubbling air directly or indirectly via airlift systems(Ogbonna and Tanaka, 2001;Tredici and Chini Zittelli,1998)or by installing static mixers inside the tubes(Ugwu et al.,2002).Mixing systems that utilized baﬄes in bubble-column photobioreactors were also demonstrated in algal cultures(Merchuk et al., 2000;Degen et al.,2001).In bubble-column and large diameter tubular photobi-oreactors,demarcation exists between the light-illuminated and dark surfaces.Thus mixing strategies should be intro-duced in cultures to circulate algal cells between the light-illuminated and dark regions of the photobioreactors (Molina Grima et al.,1999;Ugwu et al.,2005b;Mazzuca Sobczuk et al.,2006).Increase in aeration rate would improve mixing,liquid circulation,and mass transfer between gas and liquid phases in algal cultures.However,high aeration could cause shear stress to algal cells(Mazzuca Sobczuk et al., 2006;Kaewpintong et al.,2007).Gas bubble velocity is a measure of cultureﬂow rates in tubular photobioreactors (plugﬂow regime)since algal cultures are circulated along with gas bubbles.Whenﬁne spargers are used to increase gas dispersion inside horizontal tubular photobioreactors, relatively large bubbles are produced.However,the bub-bles coalesce duringﬂow to form interface between the liquid broth,gas and the walls of the tube.The contact area between the liquid and the gas is reduced,thereby,resulting to poor mass transfer rates.Gas bubble velocity and size of the bubbles are depen-dent on the liquidﬂow rate.By increasing the gasﬂow rate, the bubble diameter increases,which consequently,would increase the gas bubble velocity.The rate of gas circulation may be interrupted when baﬄes or static mixers are installed inside the reactors to increase gas dispersion.4024 C.U.Ugwu et al./Bioresource Technology99(2008)4021–4028However,the mixer elements would help to break down the large bubbles intoﬁne ones thereby,improving the mass transfer rates.Some studies have indicated that relation-ship exists between superﬁcial gas velocity,bubble velocity and the overall mass transfer coeﬃcient in bioreactors(Lu et al.,1995;Wongsuchoto et al.,2003;Couvert et al., 2004).In some photobioreactors,the relationship between superﬁcial gas velocity and the overall mass transfer coeﬃ-cient(k L a)studied in various algal cultures can be evalu-ated(Table2).In concentric tube airlift photobioreactor (which was used for Phaeodactylum tricornutum cultures), it was reported that at superﬁcial gas velocity of 0.055m sÀ1,the k L a of about0.02sÀ1was obtained(Con-treras et al.,1998).This k L a value was about the same as the one reported by Ogbonna et al.(1998)(with3-L inter-nally-illuminated photobioreactor)for Chlorella pyrenoid-osa cultures at superﬁcial gas velocity of0.009m sÀ1.In 6-L inclined tubular which was used for cultivation of Chlorella sorokiniana,the k L a of about0.003sÀ1(at super-ﬁcial gas velocity of0.02m sÀ1)was obtained(Ugwu et al., 2002).Merchuk et al.(2000)reported that by varying the superﬁcial gas velocity(5.4–82·10À4)in13-L bubble-col-umn photobioreactor(which was tested for cultivation of Porphyridium sp.),the k L a obtained was in range of1.7 and 4.7·10À3sÀ1.With3-Lﬂat plate photobioreactor (which was used for cultivation of Synechocystis aquatilis cultures),the k L a obtained was0.002sÀ1at superﬁcial gas velocity of0.009m sÀ1(Zhang et al.,2002).At superﬁ-cial gas velocity of0.024m sÀ1,the k L a reported in2-L split-cylinder internal-loop airlift photobioreactors(which was used for cultivation of Haematococcus pluvialis cul-tures)was0.009sÀ1(Vega-Estrada et al.,2005).By using 200-L airlift tubular horizontal photobioreactors(at super-ﬁcial gas velocity of0.16m sÀ1),the k L a reported was about0.014sÀ1(Camacho Rubio et al.,1999).In the case of200-L external-loop airlift tubular,which was tested for outdoor cultures of Phaeodactylum tricornutum,k L a of 0.006sÀ1was obtained at superﬁcial gas velocity of 0.25m sÀ1(Acie´n Ferna´ndez et al.,2001).It should be noted that comparison of the k L a based on only superﬁcial gas velocity could be misleading considering the diﬀerences in photobioreactor scales(volume),geometry,algal strains and cultures as well as the methods used for such studies.Furthermore,liquid velocity is a measure of liquidﬂow and degree of turbulence in photobioreactors.Some degree of turbulence is required in photobioreactors to ensure that all the cells are frequently exposed to light(Carlozzi,2003; Pruvost et al.,2006).Also,solid velocity would give an indication of how algal cells can be uniformly transported along the tube length as the cultures are aerated.Solid velocity is also a very impor-tant parameter for the determination of hydrodynamics and mass transfer characteristics of bioreactors.Couvert et al. (2004)reported that the nature(i.e.,shape,size,and poros-ity)and quantity of solids have an inﬂuence on the mass transfer of bioreactors.In intense algal cultures,cells can aggregate to form some clumps inside photobioreactors. In narrow bore tubes,these clumps may settle such that they cannot be re-circulated uniformly along the tubes.Another important aspect of hydrodynamics which has been used in characterizing photobioreactor design is gas holdup.Gas holdup is described as the fraction of the reac-tor volume taken by the gas.This can be estimated as the volume of the liquid displaced by the gas(expansion of liquid volume)due to aeration.Gas holdup is very impor-tant in photobioreactor design as it determines the circula-tion rate,the gas residence time,as well as the overall mass transfer rate(k L a).Some studies have demonstrated that relationship exist between gas holdup,bubble size,gas–liquid interfacial surface area and the overall mass transfer coeﬃcient,k L a(Chisti,1998;Vandu et al.,2005).4.Mass cultivation of algaeA good number of photobioreactors can be used in pro-duction of various algal products.Apparently,while many photobioreactors are easily operated at laboratory scale, only few of them can be successfully scaled up to pilot scale. Scale-up of photobioreactors can be done by increasing the length,diameter,height or the number of compartments of the culture systems(depending on the type of photobioreac-tor).These scale-up strategies are very challenging,mainlyTable2Relationship between the superﬁcial velocities and overall mass transfer coeﬃcient(k L a)in various cultures systemsPhotobioreactor Volume(L)Superﬁcial velocity(m sÀ1)k L a(sÀ1)Strain ReferencesConcentric tube airlift120.0550.020PhaeodactylumtricornutumContreras et al.(1998)Internally-illuminated30.0090.020Chlorella pyrenoidosa Ogbonna et al.(1998) Airlift tubular horizontal2000.1600.014Porphyridium cruentum Camacho Rubio et al.(1999)Bubble-column13 5.4–82·10À4 1.7–4.7·10À3Porphyridium sp.Merchuk et al.(2000)External-loop airlift tubular2000.2500.006Phaeodactylumtricornutum Acie´n Ferna´ndez et al. (2001)Inclined tubular60.0200.003Chlorella sorokiniana Ugwu et al.(2002) Flat-plate30.0090.002Synechocystis aquatilis Zhang et al.(2002)Split-cylinder internal-loop airlift 20.0240.009Haematococcus pluvialis Vega-Estrada et al.(2005)C.U.Ugwu et al./Bioresource Technology99(2008)4021–40284025due to diﬃculty in maintaining optimum light,temperature, mixing,and mass transfer in photobioreactors.Nevertheless,few large-scale photobioreactors with rela-tively good biomass productivities have been developed. Table3shows the algal biomass productivities reported with diﬀerent types and scales of outdoor photobioreactors. In200-L airlift tubular photobioreactor(which was used for outdoor cultivation of Phaeodactylum tricornutum),bio-mass productivity of 1.20–1.50g LÀ1dÀ1was obtained (Camacho Rubio et al.,1999;Acie´n Ferna´ndez et al., 2001).Furthermore,with200-L airlift-driven-tubular pho-tobioreactor tested for outdoor cultivation of Phaeodacty-lum tricornutum,biomass productivity of 1.90g LÀ1dÀ1 was attained(Molina et al.,2001).In11-L undular row tubular photobioreactor(for Arthrospira platensis),the pro-ductivity reported was about2.7g LÀ1dÀ1(Carlozzi,2003). Furthermore,about0.27g LÀ1dÀ1was obtained in440-L outdoorﬂat-plate photobioreactor,which was used for cul-tivation of Nannochlorospis(Cheng-Wu et al.,2001).In55-L bubble column photobioreactor(for outdoor cultivation of Haematococcus pluvialis),the biomass productivity obtained was0.06g LÀ1dÀ1(Garcı´a-Malea Lo´pez et al.,2006).Also,in25,000-L outdoor photobioreac-tor(developed for commercial production of astaxanthin from Haematococcus pluvialis),about0.05g LÀ1dÀ1was obtained(Olaizola,2000).It should be noted that aside from volumetric productivity(productivity per unit of reac-tor volume per unit of time)algal biomass productivity can be evaluated in photobioreactors based on areal productiv-ity(productivity per unit of occupied-land area per unit of time),photosynthetic eﬃciency or biomass yield(g-biomass per unit of solar radiation).5.Conclusion and perspectivesDespite that a great deal of work has been done to develop photobioreactors for algal cultures,more eﬀorts are still required to improve photobioreactor technologies and know-how of algal cultures.Photobioreactor develop-ment is perhaps,one of the major steps that should be undertaken for eﬃcient mass cultivation of algae.The major issue in the design of eﬃcient photobioreactors should be their capacity to maximize the outdoor solar rge-scale outdoor photobioreactors should have large volume and occupy less land space.In addition,they should have transparent surfaces,high illumination surfaces,high mass transfer rates and should as well,be able to give high biomass yields.Furthermore,design and construction of any photobioreactor should depend on the type of strain,the target product,geographical loca-tion,as well as the overall cost of production.It should be noted that for mass cultivation of algae, vast areas of land are required.This is actually a very seri-ous setback of algal cultivation in many developed coun-tries.Thus,the increasing population and consequently, the exorbitant cost of land have attracted the attention of many scientists to look for alternative cultivation sites.In order to reduce the cost of producing algal biomass and products,intensive eﬀorts should be made to increase the algal biomass productivity.Also,high-value metabolites should be produced to compromise the technical costs involved in algal production.Given that outdoor photobioreactors are usually natu-rally illuminated using solar light,biomass productivities (in such systems)would depend on the prevailing weather conditions in a particular locality.Although commercial cultivation of algae is done in developed countries,there are seasonal variations in temperatures and solar light energy throughout the year in most of these regions.Due to these problems,it is diﬃcult to carry out outdoor mass cultivation of algae all year round in such regions.How-ever,in most tropical developing countries,outdoor cul-tures of algae can be maintained for relatively long period of time in a year because there is neither winter nor cold seasons in those regions.Thus,tropical develop-ing countries might be potential cultivation sites for com-mercial production of algal products. AcknowledgementsThe authors acknowledge theﬁnancial support provided to them by Japan Society for Promotion of Science(JSPS). ReferencesAcie´n Ferna´ndez,F.G.,Ferna´ndez Sevilla,J.M.,Sa´nchez Pere´z,J.A., Molina Grima,E.,Chisti,Y.,2001.Airlift-driven external loop tubular photobioreactors for outdoor production of microalgae:assessment of design and performance.Chem.Eng.Sci.56,2721–2732. Benemann,J.R.,1997.CO2mitigation with microalgal systems.Energy Convers.Manage.38,475–479.Table3Productivity of algal strains reported in some outdoor photobioreactorsPhotobioreactors Volume(L)Photosynthetic strain Productivity(g LÀ1dÀ1)ReferenceAirlift tubular200Porphyridium cruentum 1.50Camacho Rubio et al.(1999) Airlift tubular200Phaeodactylum tricornutum 1.20Acie´n Ferna´ndez et al.(2001) Airlift tubular200Phaeodactylum tricornutum 1.90Molina et al.(2001)Inclined tubular 6.0Chlorella sorokiniana 1.47Ugwu et al.(2002)Undular row tubular11Arthrospira platensis 2.70Carlozzi(2003)Outdoor helical tubular75Phaeodactylum tricornutum 1.40Hall et al.(2003)Parallel tubular(AGM)25,000Haematococcus pluvialis0.05Olaizola(2000)Bubble-column55Haematococcus pluvialis0.06Garcı´a-Malea Lo´pez et al.(2006) Flat plate440Nannochloropsis sp.0.27Cheng-Wu et al.(2001)4026 C.U.Ugwu et al./Bioresource Technology99(2008)4021–4028。

图像处理Shock capturing, level sets, and PDE based methods in computer vision and image processing

Shock capturing,level sets,and PDE based methodsin computer vision and image processing:a review ofOsher Õs contributionsRonald P.Fedkiwa,1,Guillermo Sapiro b,2,Chi-Wang Shu c,*,3aDepartment of Computer Science,Stanford University,Stanford,CA 94305,USA b Department of Electrical and Computer Engineering,University of Minnesota,Minneapolis,MN55455,USAc Division of Applied Mathematics,Brown University,182George Street Box F,Providence,RI 02912,USAReceived 11December 2001;received in revised form 4September 2002;accepted 27September 2002AbstractIn this paper we review the algorithm development and applications in high resolution shock capturing methods,level set methods,and PDE based methods in computer vision and image processing.The emphasis is on Stanley Osher Õs contribution in these areas and the impact of his work.We will start with shock capturing methods and will review the Engquist–Osher scheme,TVD schemes,entropy conditions,ENO and WENO schemes,and numerical schemes for Hamilton–Jacobi type equations.Among level set methods we will review level set calculus,numerical techniques,ﬂuids and materials,variational approach,high codimension motion,geometric optics,and the compu-tation of discontinuous solutions to Hamilton–Jacobi equations.Among computer vision and image processing we will review the total variation model for image denoising,images on implicit surfaces,and the level set method in image processing and computer vision.Ó2003Elsevier Science B.V.All rights reserved.Keywords:Shock capturing method;Level set method;Computer vision;ImageprocessingJournal of Computational Physics 185(2003)309–/locate/jcp*Corresponding author.Tel.:1-401-863-2549;fax:1-401-863-1355.E-mail addresses:fedkiw@ (R.P.Fedkiw),guille@ (G.Sapiro),shu@ (C.-W.Shu).1Research supported in part by an ONR YIP and PECASE award N00014-01-1-0620,NSF DMS-0106694,and NSF ACI-0121288.2Research supported by the Oﬃce of Naval Research,the Oﬃce of Naval Research Young Investigator Award,the Presidential Early Career Awards for Scientists and Engineers (PECASE),a National Science Foundation CAREER Award,and the National Science Foundation Learning and Intelligent Systems Program (LIS).3Research supported by ARO grant DAAD19-00-1-0405,NSF Grants DMS-9804985,ECS-9906606,and DMS-0207451,NASA Langley grant NCC1-01035and AFOSR Grant F49620-02-1-0113.0021-9991/03/$-see front matter Ó2003Elsevier Science B.V.All rights reserved.doi:10.1016/S0021-9991(02)00016-5310R.P.Fedkiw et al./Journal of Computational Physics185(2003)309–3411.IntroductionThis paper is written on the occasion of Stanley OsherÕs60th birthday and serves as a review paper on a few selected areas in high resolution shock capturing schemes,level set methods,and PDE based methods in computer vision and image processing.The emphasis is on Stanley OsherÕs contribution in these areas and the impact of his work.Shock capturing numerical methods have seen revolutionary developments over the past20years.These are methods which deal with the numerical solutions of PDEs with discontinuous solutions.Such PDEs include nonlinear hyperbolic systems such as Euler equations of compressible gas dynamics.The problems are diﬃcult because traditional linear numerical methods are either too diﬀusive,or give unphysical os-cillations near the discontinuities which can lead to nonlinear instabilities.The class of high resolution numerical methods overcomes this diﬃculty to a large extent.Level set methods have seen tremendously expanded applications in many areas over the past15years. This has been made possible by theﬂexibility of the level set formulation in dealing with dynamic evolu-tions and topological changes of curves and surfaces,and by the mathematical theory and numerical tools developed in the past15years in studying these methods.PDE based methods in computer vision and image processing have been actively studied in the past few years.Again,the rapid development of mathematical models,solution tools such as level set methods,and high resolution numerical schemes has made PDE based method one of the major tools in computer vision and image processing.Stanley Osher has made inﬂuential contributions to all theseﬁelds.A distinctive feature of his research is that he emphasizes both fundamental problems in algorithm design and analysis,and practical consider-ations for the applications of the algorithms.This seems also to be the objective of the Journal of Com-putational Physics.It is thus not a surprise that a signiﬁcant portion of OsherÕs journal publications have appeared in the Journal of Computational Physics.This is particularly the case for OsherÕs work over the past15years.OsherÕs work has been highly inﬂuential,an indication of this being the citation statistics.For example,according to the ISI database,which lists papers in selected journals of high impact since1975,the 87papers of Osher listed there have been collectively cited about2500times(as on July1,2002,the same below).Among these,12papers have been cited over100times each.The top four highly cited papers of Osher include the paper of Osher and Sethian[145]on level set methods,cited538times;the paper of Harten et al.[78]on ENO schemes,cited314times;and the two papers of Shu and Osher[168,169]on ENO schemes,cited251and250times,respectively.We remark that all these four papers were published in the Journal of Computational Physics.The organization of this paper is as follows.Section2is devoted to high resolution shock capturing methods for problems with discontinuous or otherwise nonsmooth solutions.Section3contains a review of the very popular level set methods.In Section4we address PDE based methods in computer vision and image processing,andﬁnally in Section5we give some concluding remarks.Before ending this section,we remark that early in his career,Osher did a lot of research on the study of linear stability forﬁnite diﬀerence and other numerical methods for hyperbolic,parabolic,and other types of PDEs,especially those for initial-boundary value problems.This includes for example the work in[127] which followed up on a seminal paper of Kreiss[100]and used Toeplitz matrices in an elegant way to derive what was later called the GKS condition[73],and the work in[128]where stability conditions for initial-boundary value problems for parabolic equations were obtained,generalizing the work of Varah[186].In [111],Majda and Osher extended KreissÕwell posedness condition for initial-boundary value problems for hyperbolic equations to those with uniformly characteristic boundaries.In[110],Majda and Osher ana-lyzed the reﬂection of singularities at the boundary for nongrazing reﬂection for hyperbolic equations.In [112],Majda and Osher showed how error propagates globally within the domain of dependence for nu-merical approximations to coupled hyperbolic systems.The paper by Majda et al.[109]was theﬁrst torecommend the use of smooth cutoﬀfunctions on the frequency domain for spectral methods to conﬁne errors to local regions near propagating discontinuities and for stability.Sharp estimates on the region of propagation were obtained.These cutoﬀs are now widely used in the literature and the paper is still frequently cited,45times total,including many in recent years.Finally,in [49],Engquist et al.ob-tained wavelet based fast algorithms for linear hyperbolic and parabolic equations,and in [46,55,56],Engquist et al.considered numerical methods for high frequency asymptotics for geometric optics.These might be considered nonlinear,since the eikonal equation is.We shall not review in detail these early works of Osher on linear methods in the remaining part of this paper,as they are less directly related to the objectives of JCP.2.High resolution shock capturing methodsShock capturing methods refer to a class of numerical methods for solving problems containing dis-continuities (shocks,contact discontinuities,or other discontinuities),which can automatically ‘‘capture’’these discontinuities without special eﬀort to track them.A typical situation would be the solution of a hyperbolic conservation law,either a scalar equation or a system,either in one spatial dimensionu t þf ðu Þx ¼0ð2:1Þor in multiple (say three)spatial dimensionsu t þf ðu Þx þg ðu Þy þh ðu Þz ¼0:ð2:2ÞA well-known system of conservation laws is the Euler equations for inviscid ﬂuid ﬂow dynamics.The Euler equations are rather interesting because the presence of discontinuities forces one to consider weak solu-tions where the derivatives of solution variables can fail to exist.While a contact discontinuity is essentially linear,the nonlinear nature of a shock wave discontinuity allows it to develop as the solution progresses forward in time even if the data are initially smooth.A main ingredient of shock capturing methods is the conservation form of a scheme,namely,a scheme approximating (2.1)is in the formd u j d t þ1D x ^f j þ12 À^f j À12 ¼0;ð2:3Þwhere u j is an approximation to either the point value u ðx j ;t Þor the cell average u ðx j ;t Þ¼ð1=D x ÞR x j þðD x =2Þx j ÀðD x =2Þu ðx ;t Þd x of the exact solution of (2.1),and ^f j þ12is a numerical ﬂux which typically depends on a few neighboring points^f j þ12¼^f ðu j Àk ;u j Àk þ1;...;u j þm Þand satisﬁes the following two conditions:it is consistent with the physical ﬂux f ðu Þin the sense ^fðu ;u ;...;u Þ¼f ðu Þ,and it is at least Lipschitz continuous with respect to all its arguments.Notice that (2.3)is written in a semi-discrete method of lines form,while in practice the time variable t must also be discretized.Conservative schemes in the form of (2.3)are especially suitable for computing solutions with shocks,because of the important Lax–Wendroﬀtheorem,which states that solutions to such schemes,if convergent,would converge to a weak solution of (2.1).In particular,this means that the computed shocks will propagate with the correct speed.Almost all shock capturing schemes,including those developed by Osher and his collaborators,are of the conservation form (2.3).However,there are certain situations where a relaxation on the strict conservation would be beneﬁcial and would not hurt the convergence to weak solutions under suitable additional assumptions.The work of Osher and Chakravarthy [134]on the R.P.Fedkiw et al./Journal of Computational Physics 185(2003)309–341311312R.P.Fedkiw et al./Journal of Computational Physics185(2003)309–341‘‘weak conservation form’’for schemes on general curvilinear coordinates,and the work of Fedkiw et al.[60]on‘‘ghostﬂuid’’method,which treats theﬂuid interface in a nonconservative fashion,are such examples.2.1.First order monotone schemesIn the late1970s and early1980s,designing goodﬁrst order monotone schemes for(2.1)and(2.2),which give monotone shock transitions and can be proven to converge to the physically relevant weak solutions (e.g.[39]),was an active research area.The Godunov scheme is a scheme with the least numerical dissi-pation amongﬁrst order monotone schemes,however it is costly to evaluate for complexﬂux functions fðuÞ,and itsﬂux is only Lipschitz continuous but not smoother.The Lax–Friedrichs scheme is easy to evaluate and very smooth but is excessive dissipative.In[47,48],Engquist and Osher designed monotone schemes for the transonic potential equations and for general scalar conservation laws,which are relatively easy to evaluate,are C1smooth,and have a small dissipation almost comparable with Gudonov schemes.The main idea is to approximate everything by rarefaction waves(multi-valued solutions suitably integrated over for shocks).These Engquist–Osher schemes soon became very popular,especially for implicit type methods and steady state calculations,for which the extra smoothness of the numericalﬂuxes helped a lot.Similar schemes for Hamilton–Jacobi equations were given by Osher and Sethian[145].Later,Osher[129]and Osher and Solomon[147]generalized these schemes to systems of conservation laws,obtaining what was later referred to as the Osher scheme in the literature.The Osher scheme for systems has a closed form formula(for Euler equations of gas dynamics and many other systems),hence no iterations are needed,unlike the Godunov scheme.It is smoother(C1)than the Godunov scheme and also has smaller dissipation than the simpler Lax–Friedrichs scheme.Applications of the Osher scheme to the Euler equations can be found in Chakravarthy and Osher[24].In[143],Osher and Sanders designed a conservative procedure to handle locally varying time and space grids forﬁrst order monotone schemes,and proved convergence to entropy solutions for such schemes. These ideas have been used later by Berger and Colella on their adaptive methods,e.g.[9].2.2.High resolution TVD schemesFirst order monotone schemes are certainly nice in their stability and convergence to the correct entropy solutions,however they are too diﬀusive for most applications.One would need to use many grid points to get a reasonable resolution,which seriously restricts their usefulness for multi-dimensional simulations.In the1970s and early and mid1980s,the so-called‘‘high resolution’’schemes,i.e.,those schemes which are at least second order accurate and are stable when shocks appear,were developed.These started with the earlier work of,e.g.,the FCT methods of Boris and Book[13],and the MUSCL schemes of van Leer [185],and moved to HartenÕs TVD schemes[77].Osher and his collaborators did extensive research on TVD schemes,and contributed signiﬁcantly towards the analysis of such methods,during this period. These include the schemes developed and analyzed in[131,132,135],and the very high order(measured by truncation errors in smooth,monotone regions)TVD schemes in[136].2.3.Entropy conditionsThe entropy condition is an important feature for conservation laws.Because weak solutions are not unique,entropy conditions are needed to single out a unique,physically relevant solution.Osher and his collaborators did extensive research on designing and analyzing entropy condition satisfying numerical methods for conservation laws.In[113],Majda and Osher proved that the traditional second order Lax–Wendroﬀscheme,although linearly stable,is not L2stable when solving nonlinear conservation laws with discontinuous solutions.They then provided a recipe of adding artiﬁcial viscosities,such that the scheme maintained second order ac-curacy yet could be proven convergent to the entropy solution.This scheme is however oscillatory,hence not very practical in applications.In[131],Osher provided a general framework to study systematically entropy conditions for numerical schemes.This was followed by the work of Osher and Chakravarthy[135]in the study of high resolution schemes and entropy conditions,the work of Osher[132]on generalized MUSCL schemes,the work of Osher and Tadmor[148]on entropy condition and convergence of high resolution schemes,and the work of Brenier and Osher[14]on entropy condition satisfying‘‘maxmod’’second order schemes.Entropy con-dition satisfying approximations for the full potential equation of transonicﬂow were given in[140].2.4.ENO schemesIn the mid1980s it was realized that TVD schemes,despite their excellent stability and high resolution properties,have serious deﬁciency in that they degenerate toﬁrst order at smooth extrema of the solution [135].Thus,even though TVD schemes can be designed to any order of accuracy,see for example the schemes up to13th order accurate in[136],practical TVD schemes are referred to as second order schemes since the global L1errors of any TVD scheme can only be second order,even for smooth,nonmonotone solutions.In[79],Harten and Osher relaxed the TVD restriction,and replaced it by a UNO restriction,in that the total number of numerical extrema does not increase and their amplitudes could be allowed to increase slightly.The UNO scheme in[79]is uniformly second order accurate including at smooth extrema. However,it was soon realized that the UNO restriction was still too strong and excluded schemes of higher than second order.Thus,the concept of ENO,or essentially nonoscillatory,schemes wasﬁrst given by Harten et al.[78]in1987.The clever idea is that of an adaptive stencil,which is chosen based on the local smoothness of the solution,measured by the Newton divided diﬀerences of the numerical solution.Thus the order of accuracy of the scheme is never reduced,however the local stencil automatically avoids crossing discontinuities.Such schemes allow both the number of numerical extrema and their amplitudes to in-crease,however such additional oscillations are controlled on the level of truncation errors even if the solution is not smooth.ENO schemes have been extremely successful in applications,because they are simple in concept,allow arbitrary orders of accuracy,and generate sharp,monotone(to the eye)shock transitions together with high order accuracy in smooth regions of the solution including at the extrema.The original ENO schemes in[78]are in the cell averaged form,namely they areﬁnite volume schemes approximating an integrated version of(2.1).Finite volume schemes have the advantage of easy handling of nonuniform meshes and general geometry in multi-space dimensions,however they are extremely costly in multi-space dimensions,when the order of accuracy is higher than2,because then it is not possible to equate cell averages with point values,as they only agree up to second order accuracy,and a complex reconstruction procedure is needed to obtain point values from cell averages for evaluating the numerical ﬂuxes.The cost is also associated with the high order numerical quadratures needed for evaluating the integration of the numericalﬂuxes along cell boundaries in ter,Shu and Osher [168,169],developedﬁnite diﬀerence based ENO schemes using point values of the numerical solution,but still in conservation form(2.3).An important observation made in[168]and[169]is that the numericalﬂux^fjþ12in(2.3)is not a high order approximation to the physicalﬂux at xjþ12:the diﬀerence between the nu-mericalﬂux^fjþ12and the physicalﬂux fðujþ12Þis OðD x2Þ.This is a common mistake among practitioners ofﬁnite diﬀerence schemes.If a high order interpolation on the point values u j is performed to obtain a highorder approximation to ujþ12,and a numericalﬂux is chosen to approximate fðujþ12Þto a high order ac-curacy,then the scheme is only second order accurate.Correct choice of the numericalﬂuxes to obtain R.P.Fedkiw et al./Journal of Computational Physics185(2003)309–341313arbitrarily high order accuracy is given in[168,169].The approach in[169]is especially simple.A detailed description of the construction and comparison ofﬁnite volume andﬁnite diﬀerence ENO schemes can be found in the lecture notes[167].Also in[168],a class of nonlinearly stable high order Runge–Kutta time discretization methods is de-veloped.Termed TVD time discretizations,these Runge–Kutta methods have become very popular and have been used in many schemes.See e.g.[69]for a review of such methods.Analysis of ENO schemes was given in Harten et al.[80].Applications of ENO schemes to2D and3D compressibleﬂows,including turbulence and shearﬂow calculations,were given in Shu et al.[170].Triangle based second order nonoscillatory schemes were given in Durlofsky et al.[42].Nonoscillatory self-similar maximum principle satisfying high order shock capturing schemes were given in Liu and Osher[106]. Eﬃcient characteristic projection in upwind diﬀerence schemes was given in Fedkiw et al.[63].Convex ENO schemes without usingﬁeld-by-ﬁeld projection were given in Liu and Osher[107].Chemically reactive ﬂows were simulated in[62,179].The popularity of ENO schemes is demonstrated by the citation statistics:among OsherÕs four most highly cited papers mentioned in the introduction,three of them are about ENO schemes,i.e.[78,168,169]. The top cited paper of Osher,[145],is on level set methods but also uses second order ENO schemes for the numerical solutions and is where the construction of ENO schemes for general Hamilton–Jacobi equations began.2.5.WENO schemesAn improvement of ENO scheme is the WENO(weighted ENO)scheme,which wasﬁrst developed by Liu et al.[108].Both ENO and WENO use the idea of adaptive stencils in the reconstruction procedure based on the local smoothness of the numerical solution to automatically achieve high order accuracy and nonoscillatory property near discontinuities.ENO uses just one(optimal in some sense)out of many candidate stencils when doing the reconstruction;while WENO uses a convex combination of all the candidate stencils,each being assigned a nonlinear weight which depends on the local smoothness of the numerical solution based on that stencil.WENO improves upon ENO in robustness,better smoothness of ﬂuxes,better steady state convergence,better provable convergence properties,and more eﬃciency.WENO schemes have been further developed later by Jiang and Shu[90]forﬁfth order accurateﬁnite diﬀerence schemes in one and several space dimensions,by Hu and Shu[82]and Shi et al.[166]for third and fourth order accurateﬁnite volume schemes in two space dimensions using arbitrary triangulations,and by Balsara and Shu[6]on very high order WENO schemes.A detailed description can again be found in the lecture notes[167].2.6.Hamilton–Jacobi equationsWe will now move to the description of OsherÕs work in designing schemes for solving Hamilton–Jacobi equations.Further discussions on this topic will also be given in Section3on level set methods.Consider the1D Hamilton–Jacobi equation/tþHð/xÞ¼0;ð2:4Þwhich becomesð/xÞt þHð/xÞx¼0ð2:5Þafter taking a spatial derivative of the entire equation.Setting u¼/x in Eq.(2.4)results inu tþHðuÞx ¼0;ð2:6Þ314R.P.Fedkiw et al./Journal of Computational Physics185(2003)309–341R.P.Fedkiw et al./Journal of Computational Physics185(2003)309–341315 which is a scalar conservation law.Thus in one spatial dimension,a direct correspondence between Hamilton–Jacobi equations and conservation laws can be drawn.The solution u to conservation law is the derivative of a solution/to a Hamilton–Jacobi equation.Conversely,the solution/to a Hamilton–Jacobi equation is the integral of a solution u to a conservation law.This observation leads to a number of useful facts.For example,since the integral of a discontinuity is a kink(discontinuity inﬁrst derivative),solutions to Hamilton–Jacobi equations can develop kinks in the solution even if the data are initially smooth.In addition,solutions to Hamilton–Jacobi equations cannot generally develop a discontinuity(unless the corresponding conservation law solution develops a delta function).Thus,solutions/to Eq.(2.4)are typically continuous.Furthermore,since conservation laws can have nonunique solutions,one needs to apply an entropy condition to pick out the‘‘physically’’relevant solution to Eq.(2.4).Viscosity solutions for Hamilton–Jacobi equations wereﬁrst proposed by Crandall and Lions[37]in order to pick out the physically relevant solution.In addition,monotoneﬁrst order accurate numerical methods wereﬁrst proven to converge by Crandall and Lions in[38].In[130],Osher gave explicit formulas for solutions to the Riemann problems for nonconvex conservation laws and Hamilton–Jacobi equations. See also the multi-dimensional Riemann solver of Bardi and Osher[7].These are important for numerical schemes such as Godunov schemes using such Riemann solvers as building blocks.In[145],Osher and Sethian,in the context of discussing level set methods,provided aﬁrst order monotone scheme(an adaptation of the Engquist–Osher scheme[48])and a second order ENO scheme based on the framework of Shu and Osher[168,169].In[146],Osher and Shu developed high order ENO schemes for solving Hamilton–Jacobi equations,using various building blocks including the Lax–Fried-richsﬂux,the local Lax–Friedrichsﬂux,and the Roeﬂux with an entropyﬁx.In[101],Lafon and Osher developed high order2D triangle based nonoscillatory schemes for solving Hamilton–Jacobi equations. Later,Jiang and Peng[89]designed WENO schemes for solving Hamilton–Jacobi equations on rectangular meshes and Zhang and Shu[195]designed WENO schemes for solving Hamilton–Jacobi equations on arbitrary triangular meshes.WENO scheme turns out to be very useful as theﬁfth order WENO scheme in [89]reduces the numerical errors by more than an order of magnitude over the third order accurate HJ ENO scheme on the same mesh for typical applications.2.7.Additional topicsEven though it does not exactlyﬁt the title of this section,the work of Lagnado and Osher[102,103]is worth mentioning.These papers concern solving an inverse problem to compute the volatility in the Eu-ropean options Black–Scholes model,and they were theﬁrst to use PDE techniques to solve this inverse problem,via gradient descent and Tychonoﬀregularization,allowing the volatility,a coeﬃcient in a parabolic equation to be a function of the independent variables,stock price and time.These papers have attracted a lot of attention after their publication.Also worth mentioning is the work of Fatemi et al.[57]on using ENO schemes to solve the hy-drodynamic models of semiconductor device simulations.This was theﬁrst work of using high order shock capturing methods in semiconductor device simulations,and has led to many further develop-ments,e.g.[23,88].3.Level set methodsOsherÕs most cited paper was[145],joint with Sethian,which introduced the level set method for dy-namic implicit surfaces.The key idea was the Hamilton–Jacobi approach to numerical solutions of a time dependent equation for a moving implicit surface.The basic idea is as follows.Deﬁne an implicit surface as the zero isocontour of a function/ð~xÞ,and suppose that the velocity of each point on the implicit surface isgiven by~Vð~xÞ.Given this velocityﬁeld,we wish to move all the points on the surface with this velocity.The simplest way to do this is to solve the ordinary diﬀerential equationd~xd t¼~Vð~xÞð3:1Þfor every point~x on the implicitly deﬁned surface,i.e.,for all~x with/ð~xÞ¼0.This is the Lagrangian formulation of the interface evolution equation.Since there is generally an inﬁnite number of points on the front,this means discretizing the front into aﬁnite number of pieces.For example,one could use segments in two spatial dimensions or triangles in three spatial dimensions.This is not so hard to accomplish if the connectivity does not change and the surface elements do not distort too much.Unfortunately,even the most trivial velocityﬁelds can cause large distortion of boundary elements and the accuracy of the method can deteriorate quickly if one does not periodically modify the discretization in order to account for these deformations by smoothing and regularizing inaccurate surface elements.In order to avoid problems with instabilities,deformation of surface elements,and complicated surgical procedures for topological repair of interfaces,Osher and Sethian[145]proposed using the implicit function/both to represent the interface and to evolve it.The evolution of the implicit function/is governed by the simple convection equation /tþ~VÁr/¼0:ð3:2ÞThis is an Eulerian formulation of the interface evolution since the interface is captured by the implicit function/as opposed to being tracked by interface elements as in a Lagrangian formulation.Eq.(3.2)is sometimes referred to as the level set equation.The velocityﬁeld given in Eq.(3.2)can come from a number of external sources.For example,when the/ð~xÞ¼0isocontour represents the interface between two dif-ferentﬂuids,the interface velocity is calculated using the two-phase Navier–Stokes equations.In general,one does not need to specify tangential components when devising a velocityﬁeld.Since the local unit normal to the interface,~N,and r/point in the same direction,~TÁr/¼0for any tangent vector ~T implying that the tangential velocity components vanish when plugged into the level set equation.For example,in two spatial dimensions with~V¼V n~NþV t~T,the level set equation/ t þV n~NþV t~TÁr/¼0ð3:3Þis equivalent to/tþV n~NÁr/¼0:ð3:4ÞFurthermore,since~NÁr/¼r/jr/j Ár/¼jr/j2jr/j¼jr/j;ð3:5ÞEq.(3.4)can be rewritten as/tþV n jr/j¼0;ð3:6Þwhere V n is the component of velocity in the normal direction(the normal velocity).Eq.(3.6)is also known as the level set equation.Eq.(3.2)tends to be used for externally generated velocityﬁelds while Eq.(3.6) tends to be used for(internally)self-generated velocityﬁelds.3.1.Level set calculusIn a series of papers that followed[145],Osher and coworkers introduced a level set calculus for the practical treatment of discretized implicit surfaces deﬁned by time evolving partial diﬀerential equations. 316R.P.Fedkiw et al./Journal of Computational Physics185(2003)309–341。

北京高考英语阅读理解专项训练

阅读理解I was sitting in a chemistry lab class during my first year of university, nervous about the experiment we were to perform. I grabbed a pipette and, as I feared, my hand started to shake. The experience was disheartening. I was hoping to pursue a career in science, but I started to wonder whether that would be possible. I thought my dreams had crashed to the ground.I was a boy born with brain damage. My family managed to find good doctors where we lived, in Leningrad (now St. Petersburg), Russia, and I took part in clinical trials testing new treatments. Shortly after my first birthday, I started walking and it became clear my intelligence function was unaffected. So, in some sense, I was lucky. Still, I couldn’t do some things growing up. Both hands shook, especially when I was nervous or embarrassed. My left hand was much worse than my right, so I learned to write and do simple tasks with my right hand, but it wasn’t easy to do anything precisely.As a teenager, I faced a lot of bullying at school. Feeling alone, I joined a study group called “The natural world”. I thought that getting into the world of animals would keep me away from people. That’s how I came into the field of biology. At university, I enjoyed the lectures in my science classes. Many lab tasks proved impossible, however. As I struggled with my mood, I read a book about depression. From then on, the physiology of mental disorders became my scientific passion. I looked into what was being done locally and was excited to discover a lab that did behavioral experiments in rats to study depression.At the end of my second year, I approached the professor of the lab to see whether I could work with her. I was afraid to admit I couldn’t do some lab tasks. To my relief, she was completely supportive. She set me to work performing behavioral experiments for others in the lab with the help of colleagues. I loved the supportive atmosphere and stayed there to complete my master’s and Ph.D．I’ve come to realize that my hands aren’t the barrier I thought they were. By making use of my abilities and working as part of a team, I’ve been able to follow my passions. I’ve also realized that there’s much more to being a scientist than performing the physical labor. I may not collect all the data in my papers, but I’m fully capable of designing experiments and interpreting results, which, to me, is the most exciting part of science.1．What was the author’s dream?A．To live a normal life.B．To become a scientist.C．To get a master’s degree.D．To recover from depression.2．The author said he was lucky in Paragraph 2 because .A．he didn’t lose the function of both handsB．he learned how to walk at the age of oneC．his family could afford to see good doctorsD．his brain damage didn’t affect his intellectual capacity3．From the passage, it is clear that .A．the author’s own depression inspired him to help others with mental disordersB．the author was surrounded by a team who urged him to further his studyC．the author’s loneliness moved him towards the world of biologyD．the author finally finished the lab tasks on his own4．What message does the author want to express?A．Loving yourself makes a difference.B．Opportunity follows prepared people.C．A bright future begins with a small dream.D．The sun somehow shines through the storm.A snake-robot designer, a technologist, an extradimensional physicist and a journalist walk into a room. The journalist turns to the crowd and asks: Should we build houses on the ocean? Like a think-tank panel, members of the team dream up far-out answers to the crucial problem, such as self-driving housing units that could park on top of one another in the coastal city center.The setting is X, the enterprise which considers more than 100 ideas each year, in areas ranging from clean energy to artificial intelligence. Although only a tiny percentage become “projects” with far-reaching creativity, these projects exist, ultimately, to change the world, like Waymo, the biggest self-driving-car company. In the past 60 years, something strange has happened. As the academic study of creativity has thrived (蓬勃发展), the label innovation may have covered every tiny change of a soda can or a toothpaste flavor, but the rate of productivity growth has been mostly declining since the 1970s. John Fernald, an economist, points out that the notable exception to the post-1970 decline in productivity occurred when businesses throughout the economy finally figured out the breakthrough technology-information technology. John Fernald says, “It’s possible that productivity took off, because we picked all the low-hanging fruitfrom the IT wave. ”Actually, the world economy continues to harvest the benefits of IT. But where will the next technology shock come from?Breakthrough technology results from two distinct activities-invention and innovation. Invention is typically the work of scientists and researchers in labs, while innovation is an invention put to commercial use. Seldom do the two activities occur successfully under the same roof. They tend to thrive in opposite conditions; while competition and consumer choice encourage innovation, invention has historically progressed in labs that are protected from the pressure to generate profit.Allowing well-funded and diverse teams to try to solve big problems is what gave us the computer and the Internet. Today, we fail to give attention to planting the seeds of this kind of ambitious research, while complaining about the harvest. “Companies are really good at combining existing breakthroughs in ways that consumers like. But the breakthroughs come from patient and curious scientists, not the rush to market,” says Jon Gertner, the author of The Idea Factory.“Technology is a tall tree, ” John Fernald said. “But planting the seeds of invention and harvesting the fruit of innovation are entirely distinct skills, often mastered by different organizations and separated by many years. ” As for me, both of them are essential for technology, although they are relatively independent. I don’t think X is a planter or a harvester, actually. It is like building taller ladders. Nobody knows for sure what, if anything, the employees at such enterprises are going to find up on those ladders. But they’re reaching. At least someone is. 5．What is the main purpose of the first two paragraphs?A．To present the process of group discussion.B．To illustrate X’s worry about big problems.C．To reveal the importance of the crazy ideas.D．To stress the varied backgrounds of the team.6．What can we learn from the passage?A．Breakthroughs must stand the test of the market.B．Innovation on necessities can promote productivity.C．Invention develops slowly under the pressure of profit.D．The harvest of innovation lies in some ambitious research.7．Regarding John Fernald’s view on technology, the author is ____.A．supportive B．cautiousC．uncertain D．critical8．What can be inferred about X from the passage?A．It will focus on innovation.B．It will have its outcome soon.C．It may give in to its fruitless reality.D．It may bring an encouraging outlook.Every year, young, talented, and ambitious nature conservationists from all over the world shoot their shot for the Future For Nature (FFN) Award, an honorable international award.The Future For Nature aims to:·Reward and fund individuals for their outstanding efforts in the protection of species of wild animals and plants.·Stimulate award winners to sustain their dedicated work.·Help winners to raise their profile, extend their professional network and strengthen their funding basis.Benefits·The winners each receive 50,000 euros and may make their own decision to spend the money in the service of nature conservation.·FFN offers the winners a platform and brings their stories to the attention of conservationists, financiers and a wide audience, allowing them to increase their impact and gain more access to funds.·FFN is building a growing family of winners, dedicated people who form a community of people with the same interest. FFN offers them the opportunity to meet each other and continue to learn with each other in order to continue their fight for nature as efficiently and effectively as possible.QualificationsThe candidate：·Must be born on or after the 31st May 1988 and before the 31st May 2005.·Is able to explain his/her conservation work in fluent English (written and spoken).·Has achieved substantial and long-term benefits to the conservation status of one or more animal or plant species.·Must be determined to continue his/her conservation work, as the award aims to stimulate the winner’s future work. It is not an “end of career” prize.Additional RemarksFor the 2023 Future For Nature Award, we are again searching for natural leaders, who have proven that they can make a difference in species’ survival.From all applications, 6 to 10 nominees (被提名者) will be selected. These applicants will be asked to provide additional information, which will be used to select the final awardees. Ultimately, three inspiring wildlife heroes are selected as the winners.Application Process: Apply online through the Apply Now link.Application Deadline: May 1st, 2023.9．Which is one of the aims of the Future For Nature?A．To aid more green groups.B．To fund academic education.C．To inspire conservation efforts.D．To raise environmental awareness. 10．The winners will get the chance to ________.A．consult top specialists B．meet like-minded peopleC．benefit the local community D．promote self-created platforms11．To apply for the 2023 Future For Nature Award, candidates must ________.A．meet the age requirement B．apply via mail by the deadlineC．turn in the application in English D．provide additional personal informationArguably, the biggest science development of the year to date has been the images of the very depths of the universe taken by the James Webb Space Telescope (JWST). Those images beg a comparison between the external and internal universes that science is bent on observing and understanding.Decades ago, astrophysicist Carl Sagan famously said, “The universe is also within is. We’re made of star-stuff. We are a way for the universe to know itself. ” He was commenting then on the reality that our internal universe was as complex and as fantastic as the outer space.There are many similarities between the progress we’ve made in understanding the universe and in piecing together life’s inner workings. Like the technological developments that took us from Galileo’s telescope to the Hubble to the JWST, life science tools have also improved rapidly. From early light microscopes to modern super-resolution ones, these developments have afforded researchers a deep look into biology’s infinitesimal (无限小的) landscape. Learning that living things were composed of cells was, not a terribly long time ago, a revolutionary observation. Since then, scientists have been able to dive ever deeper into the components of life.Going beyond merely observing the complicated makeup of organisms, life scientists can now discover the workings of molecules (分子). And that is where scanning the universe differs from peering into biology. Understanding the universe, especially from a functional standpoint, is not necessarily an immediate urgency. Understanding biology on that level is. Simply observing the amazing internal structure of cells is not enough. Biologists must also characterize how all those parts interact and change in different environments and when faced with various challenges. Being able to image a virus or bacterium is nice at the level of basic science. But knowing how viruses gain entry into cells and spread, infect, and disable can literally save lives. Through time, biology has risen to this mechanistic challenge. Not only can life science tools produce images of cell components, even more importantly, they can help predict the effects of drugs on receptors, of immune cells on foreign invaders (入侵者), and of genetic perturbations (基因干扰) on development and aging.This is not to belittle the work of scientists researching into universe. They should rightly be praised for delivering views of impossibly distant, impossibly massive phenomena. My aim is to celebrate these accomplishments while at the same time recognizing that science’s inward search for detail and insight is equally impressive and, in my view, more urgent. The output of both the outward and inward explorations should stimulate wonder in everyone. After all, it’s all star-stuff. 12．Why does the author quote Carl Sagan’s comment in Paragraph 2?A．To introduce the background.B．To prove an assumption.C．To make a comparison.D．To present an idea.13．Like the study of the universe, life science has been advancing in ________.A．study approaches B．system managementC．research facilities D．technology integration14．We can infer from Paragraph 4 that biologists’ work is ________.A．practical B．risky C．flexible D．popular15．As for life science, which would the author agree with?A．It has received universal recognition.B．It should enjoy priority in development. C．It can be applied in the majority of areas.D．It is more complicated than space science.Technology seems to discourage slow, immersive reading. Reading on a screen, particularly a phone screen, tires your eyes and makes it harder for you to keep your place. So online writing tends to be more skimmable and list-like than print. The cognitive neuroscientist Mary Walt argued recently that this “new norm” of skim reading is producing “an invisible, game-changing transformation” in how readers process words. The neuronal circuit that sustains the brain’s capacity to read now favors the rapid absorption of information, rather than skills developed by deeper reading, like critical analysis.We shouldn’t overplay this danger. All readers skim. Skimming is the skill we acquire as children as we learn to read more skillfully. From about the age of nine, our eyes start to bounce around the page, reading only about a quarter of the words properly, and filling in the gaps by inference. Nor is there anything new in these fears about declining attention spans. So far, the anxieties have proved to be false alarms. “Quite a few critics have been worried about attention span lately and see very short stories as signs of cultural decline,” the American author Selvin Brown wrote. “No one ever said that poems were evidence of short attention spans.”And yet the Internet has certainly changed the way we read. For a start, it means that there is more to read, because more people than ever are writing. If you time travelled just a few decades into the past, you would wonder at how little writing was happening outside a classroom. And digital writing is meant for rapid release and response. An online article starts forming a comment string underneath as soon as it is published. This mode of writing and reading can be interactive and fun. But often it treats other people’s words as something to be quickly harvested as fodder to say something else. Everyone talks over the top of everyone else, desperate to be heard.Perhaps we should slow down. Reading is constantly promoted as a social good and source of personal achievement. But this advocacy often emphasizes “enthusiastic”, “passionate” or “eager” reading, none of which adjectives suggest slow, quiet absorption.To a slow reader, a piece of writing can only be fully understood by immersing oneself in the words and their slow comprehension of a line of thought. The slow reader is like a swimmer who stops counting the number of pool laps he has done and just enjoys how his body feels and moves in water.The human need for this kind of deep reading is too tenacious for any new technology to destroy. We often assume that technological change can’t be stopped and happens in one direction, so that older media like “dead-tree” books are kicked out by newer, more virtual forms. In practice, older technologies can coexist with new ones. The Kindle has not killed off the printed book any more than the car killed off the bicycle. We still want to enjoy slowly-formed ideas and carefully-chosen words. Even in a fast-moving age, there is time for slow reading.16．What is the author’s attitude towards Selvin Brown’s opinion?A．Favorable.B．Critical.C．Doubtful.D．Objective. 17．The author would probably agree that .A．advocacy of passionate reading helps promote slow readingB．digital writing leads to too much speaking and not enough reflectionC．the public should be aware of the impact skimming has on neuronal circuitsD．the number of Internet readers is declining due to the advances of technology18．What does the underlined word “tenacious” in Paragraph 6 probably mean? A．Comprehensive.B．Complicated.C．Determined.D．Apparent. 19．Which would be the best title for the passage?A．Slow Reading Is Here to StayB．Digital Technology Prevents Slow ReadingC．Screen vs. Print: Which Requires Deep Reading?D．Reading Is Not a Race: The Wonder of Deep ReadingIt was the day of the big cross-country run. Students from seven different elementary schools in and around the small town of 100-Mile House, British Columbia, were warming up and walking the route through thick evergreen forest.I looked around and finally saw David standing by himself off to the side by a fence. He was small for ten years old, with messy red hair. But his usual big toothy grin was absent today. Iwalked over and asked him why he wasn’t with the other children. The only response he gave me was he had decided not to run. What was wrong? He had worked so hard for this event! David’s cerebral palsy (脑瘫) prevented him from walking or running like other children, but at school his peers thought of him as a regular kid. He always participated to the best of his ability in whatever they were doing. It just took him longer. He had stubbornly run a total of twenty three kilometres in practice runs to prepare for that day’s two-and-a-half-kilometre run, and he had asked me to come and watch. We sat down together on some steps, but David wouldn’t look at me.I quietly said, “David, if you don’t want to run today, no one is going to make you. But if you’re not running because you’re afraid someone is going to laugh, that’s not a good enough reason. There will always be someone who will laugh and say mean things. Are you going to let them get in your way? If you really want to run, David, then you run!” I held my breath as David took this in. Then he looked at the field and said, “I’m gonna run.”The starter’s gun sounded. But he had only gone a few metres before he tripped and fell flat on the ground. My heart sank. As I started to shout encouragement, David picked himself up and started again. All the other runners had disappeared over the hill. But it didn’t matter. He had worked for it, and he wouldn’t give up!I waited anxiously by the finish line as the most runners completed and another race had begun. Still no David! I started to feel sick. Had I done the wrong thing? Could he have become lost? Finally, a small figure emerged from the forest. David raised his arms in triumph as he crossed the finish line to wild cheers and applause. He caught my eye, flashed me a toothy grin and said, “That was easy!”20．What made David unable to run like other children?A．His mental problem.B．His physical condition.C．His laziness.D．His hesitation.21．David decided to run because ________.A．he was encouraged to B．he wanted to be the firstC．he was laughed into doing it D．he knew it was a shorter distance 22．Which of the following can best describe David?A．Brave and talkative.B．Out-going and kind-hearted.C．Lively and hard-working.D．Optimistic and strong-willed.23．By using the phrase “a toothy grin” in the last sentence, the writer intends to tell us about David’s ________.A．competence in finishing a run B．positive attitude towards lifeC．ability to win cheers and applause D．efforts to catch others’ attentionMaking use of the wind, the water or, for more than half of all plant species, animals, plants disperse (散播) seeds far and wide. Frugivores — animals such as gibbons that feed on the fleshy fruits of plants — eat and then excrete (排泄) seeds away from the original tree. The African savanna elephant can carry seeds up to a record-breaking distance of 65 kilometres. This ability to shift geographical ranges will be crucial to plants when it comes to surviving climate change. However, just like all gibbon species, the African savanna elephant is endangered, its population down by 60 percent over the past 50 years.Researchers in Denmark and the USA have published a new study into how the loss of seed-dispersing animals could affect the resilience (恢复力) of forests and other natural ecosystems. According to their research, this loss has already reduced the ability of plants to move in pace with climate change by 60 percent, and in some areas by as much as 95 percent.Evan Fricke, lead author of the study, explains that in order to reach these results, they pulled together existing data from all previous studies and used machine learning to develop models that could estimate the seed dispersal potential of any animal, even ones that are now extinct.The researchers found that, historically, the decline of seed-dispersing animals has had the greatest influence on plants across the temperate (温带的) regions of North and South America, Europe and southern Australia. “Our temperate ecosystems have lost a lot of the natural seed-dispersal function that they would have had.” explains Fricke, referring to large mammals that were once widespread in these regions.Nevertheless, the poor conservation status of many seed-dispersing tropical animals puts plants in regions such as Southeast Asia and Madagascar most at risk today. Without the preservation of such animals, global seed dispersal could decline by a further 15 percent. “The direct implication of this decline is that many plant species will be unable to keep pace with a changing climate,” says Fricke. “That means the potential loss not only of plant biodiversity but of the ecosystem functions that those plants provide.”As wildlife is lost, plants can no longer adapt and survive and forests become less sustainable, which reduces the amount of carbon they can store. They also lose their ability to support wildlife. Whole ecosystems are disrupted. The conclusion, Fricke says, is clear: we must conserve currently endangered species and restore the populations of important seed dispersers. “Independent of climate change, rewilding has the potential to benefit our ecosystems, but in a changing climate, it has the added benefit of increasing the climate resilience of those ecosystems,” he says.24．The author mentions the African savanna elephant in Paragraph 1 is to ________. A．highlight the problem B．predict the endingC．express an opinion D．provide a solution25．What does Fricke conclude from the study?A．plants disperse seeds by way of animals excreting them.B．rewilding can promote the climate resilience of our ecosystems.C．seed-dispersing animals could hardly affect the natural ecosystems.D．the loss of seed-dispersing animals has little influence on temperate regions.26．Which would be the best title of the passage?A．The Resilience of EcosystemsB．The Conservation of Seed-dispersing AnimalsC．Animals That Spread Seeds Are Essential — And Under ThreatD．Animals That Spread Seeds Are Endangered — And Well ProtectedIn 1840, the French painter Paul Delaroche saw the first daguerreotype — an early photographic process — and declared that “from today, painting is dead”. One can understand him feeling threatened by the technology, but we know now he was dead wrong: instead, that year marked the birth of the art of photography.Throughout history, there’s been fierce debate about the boundary between science and the arts. It continues in the form of the great AI debate. In February this year, the winning photo in an Australian photography competition was created entirely by artificial intelligence; and months earlier, a man used text-to-image software to take out the top prize in the Colorado Art Fair. The software can use billions of online images, identified by digital labelling from innovations like alt text. But the question remains: do AI art generators copy or steal other artists’ work?“Unlike copying/stealing, there’s also taking inspiration,” artist Koach argues. “This accumulation (积累) of seeing and remembering art from other artists will, at one point, become apparent and trigger inspiration. Isn’t this the machine’s way of ‘taking inspiration’?”The artistic community seems split. Some celebrate the removal of barriers into the art industry; anyone can be an artist these days. Others are joining class actionis, accusing the tech companies of stealing art without credit, consent or compensation.As a journalist, I’m fascinated but horrified by the development. Apps like Stable Diffusion, Dall-E and Midjourney can imagine a deserted island in the style of Monet. But if you ask for images of a CEO, it’s generally an older white male. Nurses? Almost all female. While humans are biased (有偏见的), technology is copying the unfairness at scale.By contrary, Koach is keen to reframe AI art as simply another design tool. “The artist and the technology are intertwined throughout the creative process,” he says. He looks for a hopeful future: “AI art might shift our values away from, ‘Does this image have all the colours, compositions and styles that I want to?” ‘Is this image meaningful or special in some other way?’.”But if we want to live with this technology, we need to be proactive. Learn about the complexity and bias within AI and keep a close eye on where it’s going. Regulate the industry to protect users and creators. And outsmart the algorithms (算法).27．What can we learn from the first two paragraphs?A．The appearance of AI art signals the death of painting.B．There is still no clear line between science and the arts.C．Photos created by artificial intelligence are widely favored.D．AI art generators like text-to-image software are innovative.28．As for AI art, what would the artist Koach agree with?A．AI art will change our values about technology.B．AI art will make everyone an artist in the future.C．The creation of AI art is inspired by other artists.D．AI artists are more creative due to the technology.29．What shows the bias copied by technology?A．The technology is a threat to traditional artists.B．Tech companies are stealing other artists’ workC．Apps can paint a deserted island in Monet’s style.D．Al has a fixed image of a particular type of person.30．Regarding the development of AI art, the author suggests .A．making AI art another art design tooB．taking active steps to control the situationC．copying Monet’s painting style and worksD．preventing the use of AI in the production of artworksGive a little sunshine!The Council on Aging (COA) runs a telephone friendship project called the Sunshine Call Program, matching over-60s with a friendly volunteer for a daily chat over the phone. The aim is simple-to help ease the loneliness and repair social networks.Sheila, 77, a retired teacher, lived alone. She has been receiving calls from Rianne, a volunteer, for over two months.“Talking to Rianne is something I really look forward to—a breath of fresh air. We talk about everything—theatre, her work, books we’ve read…Listening to someone else’s life enriches you and gives you something positive to focus on.”“At the beginning, I had no expectation of how the phone calls would go, but it’s wonderful that it’s led to a genuine friendship. Rianne helps me a lot …”Are you ready to add a little sunshine to a senior’s life?The Sunshine Call Program initially links a volunteer with an isolated (独居的) senior for a daily call. When comfortable, the volunteer introduces a second senior to the call. Then another, until there are four seniors to one。

TPO听力27-30

TPO-27Conversation 11. Why does the woman go to the information desk?●She does not know where the library computers are located.●She does not know how to use a computer to locate the information she needs.●She does not have time to wait until a library computer becomes available.●The book she is looking for was missing from the library shelf.2. Why does the man assume that the woman is in Professor Simpson’s class?●The man recently saw the woman talking with Professor Simpson.●The woman mentioned Profe ssor Simpson’s name.●The woman is carrying the textbook used in Professor Simpson’s class.●The woman is researching a subject that Professor Simpson specialized in.3. What can be inferred about the geology course the woman is taking?●It has led the woman to choose geology as her major course of study.●It is difficult to follow without a background in chemistry and physics.●The woman thinks it is easier than other science courses.●The woman thinks the course is boring.4. What topic does the woman need information on?●The recent activity of a volcano in New Zealand●Various types of volcanoes found in New Zealand●All volcanoes in New Zealand that are still active●How people in New Zealand have prepared for volcanic eruptions5. What does the man imply about the article when he says this:●It may not contain enough background material.●It is part of a series of articles.●It might be too old to be useful.●It is the most recent article published on the subject.Lecture 16. What is the lecture mainly about?●The transplantation of young coral to new reef sites●Efforts to improve the chances of survival of coral reefs●The effects of water temperature change on coral reefs●Confirming the reasons behind the decline of coral reefs7. According to the professor, how might researchers predict the onset of coral bleaching in the future?●By monitoring populations of coral predators●By monitoring bleach-resistant coral species●By monitoring sea surface temperatures●By monitoring degraded reefs that have recovered8. Wh at is the professor’s opinion about coral transplantation?●It is cost-effective.●It is a long-term solution.●It is producing encouraging results.●It does not solve the underlying problems.9. Why does the professor discuss refugia? [Choose two answers]●To explain that the location of coral within a reef affects the coral’s ability to survive●To point out why some coral species are more susceptible to bleaching than others●To suggest that bleaching is not as detrimental to coral health as first thought●To illustrate the importance of studying coral that has a low vulnerability to bleaching10. What does the professor imply about the impact of mangrove forests on coral-reef ecosystems?●Mangrove forests provide habitat for wildlife that feed on coral predators.●Mangrove forests improve the water quality of nearby reefs.●Mangrove forests can produce sediments that pollute coral habitats.●Mangrove forests compete with nearby coral reefs for certain nutrients.11. According to the professor, what effect do lobsters and sea urchins have on a coral reef?●They protect a reef by feeding on destructive organisms.●They hard a reef by taking away important nutrients.●They filter pollutants from water around a reef.●They prevent a reef from growing by preying on young corals.Lecture 212. What does the professor mainly discuss?●Some special techniques used by the makers of vintage Cremonese violins●How the acoustical quality of the violin was improved over time●Factors that may be responsible for the beautiful tone of Cremonese violins●Some criteria that professional violinists use when selecting their instruments13. What does the professor imply about the best modern violin makers?●They are unable to recreate the high quality varnish used by Cremonese violin makers.●Their craftsmanship is comparable to that of the Cremonese violin makers.●They use wood from the same trees that were used to make the Cremonese violins.●Many of them also compose music for the violin.14. Why does the professor discuss the growth cycle of trees?●To clarify how modern violin makers select wood●To highlight a similarity between vintage and modern violins●To explain why tropical wood cannot be used to make violins●To explain what causes variations in density in a piece of wood15. What factor accounts for the particular density differential of the wood used in the Cremonese violins?●The trees that produced the wood were harvested in the spring●The trees that produced the wood grew in an unusually cool climate●The wood was allowed to partially decay before being made into violins●.The wood was coated with a local varnish before it was crafted into violins16. The professor describes and experiment in which wood was exposed to a fungus before being made into a violin. What point does the professor make about the fungus?●It decomposes only certain parts of the wood.●It is found only in the forests of northern Italy.●It was recently discovered in a vintage Cremonese violin.●It decomposes only certain species of trees.17. Why does the professor say this:●To find out how much exposure students have had to live classical music●To use student experiences to support his point about audience members●To indicate that instruments are harder to master than audience members realize●To make a point about the beauty of violin musicConversation 21. Why has the student come to see the professor?●To find out her reaction to a paper he recently submitted●To point out a factual error in an article the class was assigned to read●To ask about the suitability of a topic he wants to write about●To ask about the difference between chinampas and hydroponics2. What does the professor imply about hydroponics?●It was probably invented by the Aztecs.●It is a relatively modern development in agriculture.●It requires soil that is rich in nutrients.●It is most successful when extremely pure water is used.3. Why does the professor describe how chinampas were made?●To emphasize that the topic selected for a paper needs to be more specific●To encourage the student to do more research●To point out how much labor was required to build chinampas●To explain why crops grown on chinampas should not be considered hydroponic4. What does the professor think about the article the student mentions?●She is convinced that it is not completely accurate.●She believes it was written for readers with scientific backgrounds.●She thinks it is probably too short to be useful to the student.●She has no opinion about it, because she has not read it.5. What additional information does the professor suggest that the student include in his paper?● A comparison of traditional and modern farming technologies●Changes in the designs of chinampas over time●Differences in how various historians have described chinampas●Reasons why chinampas are often overlooked in history booksLecture 36. What does the professor mainly discuss?●Comparisons between land animals and ocean-going animals of the Mesozoic era●Comparisons between sauropods and modern animals●Possible reasons why sauropods became extinct●New theories about the climate of the Mesozoic era7. What point does the professor make when she compares blue whales to large land animals?●Like large land animals, blue whales have many offspring.●Like large land animals, blue whales have proportionally small stomachs.●The land environment provides a wider variety of food sources than the ocean.●The ocean environment reduces some of the problems faced by large animals.8. According to the professor, what recent finding about the Mesozoic era challenges an earlier belief?●Sauropod populations in the Mesozoic era were smaller than previously believed.●Oxygen levels in the Mesozoic era were higher than previously believed.●Ocean levels in the Mesozoic era fluctuated more than previously believed.●Plant life in the Mesozoic era was less abundant than previously believed.9. Compared to small animals, what disadvantages do large animals typically have? [Choose two answers]●Large animals require more food.●Large animals have fewer offspring.●Large animals use relatively more energy in digesting their food.●Large animals have greater difficulty staying warm.10. Why does the professor discuss gastroliths that have been found with sauropod fossils?●To show that much research about extinct animals has relied on flawed methods●To show that even an incorrect guess can lead to useful research●To give an example of how fossil discoveries have cast doubt on beliefs about modern animals ●To give an example of a discovery made possible by recent advances in technology11. What did researchers conclude from their study of sauropods and gastroliths?●That gastroliths probably helped sauropods to store large quantities of plant material in theirstomachs●That sauropods probably used gastroliths to conserve energy●That sauropods may not have used gastroliths to aid in their digestion●That sauropods probably did not ingest any stonesLecture 412. What is the lecture mainly about?●Various ways color theory is used in different fields●Various ways artists can use primary colors●Aspects of color theory that are the subject of current research●The development of the first theory of primary colors13. What does the professor imply about the usefulness of the theory of primary colors?●It is not very useful to artists.●It has been very useful to scientists.●It is more useful to artists than to psychologists.●It is more useful to modern-day artists than to artists in the past.14. Why does the professor mention Isaac Newton?●To show the similarities between early ideas in art and early ideas in science●To explain why mixing primary colors does not produce satisfactory secondary colors●To provide background information for the theory of primary colors●To point out the first person to propose a theory of primary colors15. According to the pro fessor, what were the results of Goethe’s experiments with color? [Choose two answers]●The experiments failed to find a connection between colors and emotions.●The experiments showed useful connections between color and light.●The experiments provided valuable information about the relationships between colors.●The experiments were not useful until modern psychologists reinterpreted them.16. According to the professor, why did Runge choose the colors red, yellow and blue as the three primary colors?●He felt they represented natural light at different times of the day.●He noticed that they were the favorite colors of Romantic painters.●He performed several scientific experiments that suggested those colors.●He read a book by Goethe and agreed with Goethe’s choices of colors.17. What does the professor imply when he says this?●Many people have proposed theories about primary colors.●Goethe discovered the primary colors by accident.●Goethe probably developed the primary color theory before reading Runge’s le tter.●Goethe may have been influenced by Runge’s ideas about primary colors.TPO-28Conversation 11. What is the conversation mainly about?●Criticisms of Dewey’s political philosophy●Methods for leading a discussion group●Recent changes made to a reference document●Problems with the organization of a paper2. Why is the student late for his meeting?●Seeing the doctor took longer than expected.●No nearby parking spaces were available.●His soccer practice lasted longer than usual.●He had problems printing his paper.3. What revisions does the student need to make to his paper? [Choose three answers]●Describe the influences on Dewey in more detail●Expand the introductory biographical sketch●Remove unnecessary content throughout the paper●Use consistent references throughout the paper●Add an explanation of Dewey’s view on individuality4. Why does the professor mention the political science club?●To encourage the student to run for club president●To point out that John Dewey was a member of a similar club●To suggest an activity that might interest the student●To indicate where the student can get help with his paper5. Why does the professor say this:●To find out how many drafts the student wrote●To encourage the student to review his own work●To emphasize the need for the student to follow the guidelines●To propose a different solution to the problemLecture 16. What is the lecture mainly about?●The importance of Locke’s views to modern philosophical thought●How Descartes’ view of knowledge influenced tre nds in Western philosophy●How two philosophers viewed foundational knowledge claims●The difference between foundationalism and methodological doubt7. Why does the professor mention a house?●To explain an idea about the organization of human knowledge●To illustrate the unreliability of our perception of physical objects●To clarify the difference between two points of view about the basis of human knowledge●To remind students of a point he made about Descartes in a previous lecture8. What did Locke believe to the most basic type of human knowledge?●Knowledge of one’s own existence●Knowledge acquired through the senses●Knowledge humans are born with●Knowledge passed down from previous generations9. According to the professor, what was Descartes’ purpose f or using methodological doubt?●To discover what can be considered foundational knowledge claims●To challenge the philosophical concept of foundationalism●To show that one’s existence cannot be proven●To demonstrate that Locke’s views were essentially corre ct10. For Descartes what was the significance of dreaming?●He believed that his best ideas came to him in dreams●He regarded dreaming as the strongest proof that humans exist.●Dreaming supports his contention that reality has many aspects.●Dreaming illustrates why human experience of reality cannot always be trusted.11. According to Descartes, what type of belief should serve as a foundation for all other knowledge claims?● A belief that is consistent with what one sees and hears● A belief that most other people share● A belief that one has held since childhood● A belief that cannot be falseLecture 212. What is the main purpose of the lecture?●To show that some birds have cognitive skills similar to those of primates●To explain how the brains of certain primates and birds evolved●To compare different tests that measure the cognitive abilities of animals●To describe a study of the relationship between brain size and cognitive abilities13. When giving magpies the mirror mark test, why did researchers place the mark on magpies’ throats?●Throat markings trigger aggressive behavior in other magpies.●Throat markings are extremely rare in magpies.●Magpies cannot see their own throats without looking in a mirror.●Magpies cannot easily remove a mark from their throats.14. According to the professor, some corvettes are known to hide their food. What possible reasonsdoes she provide for this behavior? [Choose two answers]●They are ensuring that they will have food to eat at a later point in time.●They want to keep their food in a single location that they can easily defend.●They have been conditioned to exhibit this type of behavior.●They may be projecting their own behavioral tendencies onto other corvids.15. What is the professor’s attitude toward the study on p igeons and mirror self-recognition?●She is surprised that the studies have not been replicated.●She believes the study’s findings are not very meaningful.●She expects that further studies will show similar results.●She thinks that it confirms what is known about magpies and jays.16. What does the professor imply about animals that exhibit mirror self-recognition?●They acquired this ability through recent evolutionary changes.●They are not necessarily more intelligent than other animals.●Their brains all have an identical structure that governs this ability.●They may be able to understand another animal’s perspective.17. According to the professor, what conclusion can be drawn from what is now known about corvettes’ brains?●The area in corvids’ brains tha t governs cognitive functions governs other functions as well.●Corvids’ brains have evolved in the same way as other birds’ brains, only more rapidly.●Corvids’ and primates’ brains have evolved differently but have some similar cognitive abilities.●The cognitive abilities of different types of corvids vary greatly.Conversation 21. Why does the man go to see the professor?●To learn more about his student teaching assignment●To discuss the best time to complete his senior thesis●To discuss the possibility of changing the topic of his senior thesis●To find out whether the professor will be his advisor for his senior thesis2. What is the man’s concern about the second half of the academic year?●He will not have time to do the necessary research for his senior thesis.●He will not be allowed to write his senior thesis on his topic choice.●His senior thesis advisor will not be on campus.●His student teaching requirement will not be complete before the thesis is due.3. What does the man imply about Professor Johnson?●His sabbatical may last longer than expected.●His research is highly respected throughout the world.●He is the English department’s specialist on Chaucer.●He is probably familiar with the literature of the Renaissance.4. Why does the man want to write his senior thesis on The Canterbury Tales? [Choose two answers]●He studied it during his favorite course in high school.●He has already received approval for the paper from his professor.●He thinks that the knowledge might help him in graduate school.●He has great admiration for Chaucer.5. Why does the professor say this:●She is uncertain whether the man will be able to finish his paper before the end of the summer.●She thinks the man will need to do a lot of preparation to write on a new topic.●She wants to encourage the man to choose a new advisor for his paper.●She wants the man to select a new topic for his paper during the summer.Lecture 36. What is the lecture mainly about?●The differences in how humans and plants sense light●An explanation of an experiment on color and wavelength●How plants sense and respond to different wavelengths of light●The process by which photoreceptors distinguish wavelengths of light7. According to the professor, what is one way that a plant reacts to changes in the number of hours of sunlight?●The plant absorbs different wavelengths of light.●The plant begins to flower or stops flowering.●The number of photoreceptors in the plant increases.●The plant’s rate of photosynthesis increases.8. Why does the professor think that it is inappropriate for certain wavelength of light to be named “far-red”?●Far-red wavelengths appear identical to red wavelengths to the human eye.●Far-red wavelengths have the same effects on plants as red wavelengths do.●Far-red wavelengths travel shorter distances than red wavelengths do.●Far-red wavelengths are not perceived as red by the human eye.9. What point does the professor make when she discusses the red light and far-red light that reaches plants?●All of the far-red light that reaches plants is used for photosynthesis.●Plants flower more rapidly in response to far-red light than to red light.●Plants absorb more of the red light that reaches them than of the far-red light.●Red light is absorbed more slowly by plants than far-red light is.10. According to the professor, how does a plant typically react when it senses a high ratio of far-red light to red light?●It slows down its growth.●It begins photosynthesis.●It produces more photoreceptors.●It starts to release its seeds.11. In the Pampas experiment, what was the function of the LEDs?●To stimulate photosynthesis●To simulate red light●To add to the intensity of the sunlight●To provide additional far-red lightLecture 412. What does the professor mainly discuss?●Evidence of an ancient civilization in central Asia●Archaeological techniques used to uncover ancient settlements●The controversy concerning an archaeological find in central Asia●Methods used to preserve archaeological sites in arid areas13. What point does the professor make about mound sites?●They are easier to excavate than other types of archaeological sites.●They often provide information about several generations of people.●They often contain evidence of trade.●Most have been found in what are now desert areas.14. Why does the professor compare Gonur-depe to ancient Egypt?●To point out that Gonur-depe existed earlier than other ancient civilizations●To emphasize that the findings at Gonur-depe are evidence of an advanced civilization●To demonstrate that the findings at these locations have little in common●To suggest that the discovery of Gonur-depe will lead to more research in Egypt15. What does the professor imply about the people of Gonur-depe?●They avoided contact with people from other areas.●They inhabited Gonur-depe before resettling in Egypt.●They were skilled in jewelry making.●They modeled their city after cities in China.16. Settlements existed at the Gonur-depe site for only a few hundred years. What does the professor say might explain this fact? [Choose two answers]●Wars with neighboring settlements●Destruction caused by an earthquake●Changes in the course of the Murgab River●Frequent flooding of the Murgab River17. What is the professor’s opinion about the future of the Gonur-depe site?●She believes it would be a mistake to alter its original form.●She doubts the ruins will deteriorate further.●She thinks other sites are more deserving of researchers’ attention.●She is not convinced it will be restored.TPO-29Conversation 11. What is the conversation mainly about?●What the deadline to register for a Japanese class is●Why a class the woman chose may not be suitable for her●How the woman can fix an unexpected problem with her class schedule●How first-year students can get permission to take an extra class2. Why does the man tell the woman that Japanese classes are popular?●To imply that a Japanese class is unlikely to be canceled●To explain why the woman should have registered for the class sooner●To encourage the woman to consider taking Japanese●To convince the woman to wait until next semester to take a Japanese class3. Why does the man ask the woman if she registered for classes online?●To explain that she should have registered at the registrar’s office●To find out if there is a record of her registration in the computer●To suggest a more efficient way to register for classes●To determine if she received confirmation of her registration4. What does the man suggest the woman do? [Choose two answers]●Put her name on a waiting list●Get the professor to sign a form granting her permission to take the class●Identify a course she could take instead of Japanese●Speak to the head of the Japanese department5. What does the man imply when he points out that the woman is a first-year student?●The woman has registered for too many classes.●The woman should not be concerned if she cannot get into the Japanese class●The woman should not register for advanced-level Japanese classes yet●The woman should only take required courses at this timeLecture 16. What does the professor mainly discuss?●Causes of soil diversity in old-growth forests●The results of a recent research study in a Michigan forest●The impact of pedodiversity on forest growth●How forest management affects soil diversity7. According to the professor, in what way is the soil in forested areas generally different from soil in other areas?●In forested areas, the soil tends to be warmer and moister.●In forested areas, the chemistry of the soil changes more rapidly.●In forested areas, there is usually more variability in soil types.●In forested areas, there is generally more acid in the soil.8. What does the professor suggest are the three main causes of pedodiversity in the old-growth hardwood forests she discusses? [Choose three answers]●The uprooting of trees●The existence of gaps●Current forest-management practices●Diversity of tree species●Changes in climatic conditions9. Why does the professor mention radiation from the Sun?●To point out why pits and mounds have soil with unusual properties●To indicate the reason some tree species thrive in Michigan while others do not●To give an example of a factor that cannot be reproduced in forest management●To help explain the effects of forest gaps on soil10. Why does the professor consider pedodiversity an important field of research?●It has challenged fundamental ideas about plant ecology.●It has led to significant discoveries in other fields.●It has implications for forest management.●It is an area of study that is often misunderstood.11. Why does the professor give the students an article to read?●To help them understand the relationship between forest dynamics and pedodiversity●To help them understand how to approach an assignment●To provide them with more information on pits and mounds●To provide them with more exposure to a controversial aspect of pedodiversityLecture 212. What is the main purpose of the lecture?●To explain how musicians can perform successfully in theaters and concert halls with pooracoustics●To explain how the design of theaters and concert halls has changed over time●To discuss design factors that affect sound in a room●To discuss a method to measure the reverberation time of a room13. According to the lecture, what were Sabine’s contr ibutions to architectural acoustics? [Choose two answers]●He founded the field of architectural acoustics.●He developed an important formula for measuring a room’s reverberation time.●He renewed architects’ interest in ancient theaters.●He provided support for using established architectural principles in the design of concert halls.14. According to the professor, what is likely to happen if a room has a very long reverberation time?●Performers will have to make an effort to be louder.●Sound will not be scattered in all directions.●Older sounds will interfere with the perception of new sounds.●Only people in the center of the room will be able to hear clearly.15. Why does the professor mention a piano recital? [Choose two answers]●To illustrate that different kinds of performances require rooms with different reverberationtimes●To demonstrate that the size of the instrument can affect its acoustic properties●To cite a type of performance suitable for a rectangular concert hall●To exemplify that the reverberation time of a room is related to its size16. According to the professor, what purpose do wall decorations in older concert halls serve?●They make sound in the hall reverberate longer.●They distribute the sound more evenly in the hall.●They make large halls look smaller and more intimate.●They disguise structural changes made to improve sound quality.17. Why does the professor say this:●To find out if students have understood his point●To indicate that he will conclude the lecture soon●To introduce a factor contradicting his previous statement●To add emphasis to his previous statementConversation 21. Why does the student go to see the professor?●To explain why he may need to hand in an assignment late●To get instruction on how to complete an assignment●To discuss a type of music his class is studying●To ask if he can choose the music to write about in a listening journal2. What does the student describe as challenging?●Comparing contemporary music to earlier musical forms●Understanding the meaning of songs that are not written in English●Finding the time to listen to music outside of class●Writing critically about musical works3. Why does the student mention hip-hop music?●To contrast the ways he responds to familiar and unfamiliar music。

福建省漳州市东山第二中学2022-2023学年高三上学期期中考试英语试题(原卷版)

例: How much is the shirt?
A.￡19.15. B.￡9.18. C.￡9.15.
答案是C。
1. Where is the library?
A. Next to the bank.
B. Opposite the bank.
C Across from Washington Street.
A.Tasty Beer.B.Local cuisine.
C.Seaside flowers.D.Mountain scenery.
B
Tik Tok? Why not? Making our channel was my grandson Kevin’s idea from the start. It’s his fault that I’ve got nearly 5 million followers. We were just sitting in the kitchen one day, and he filmed me chatting. I can barely remember what I said I think something about clocks? That’s what I thought he was telling me to do: tick tock, a clock! It was meant to be a joke, but overnight that video got 1 million views.
A. Future exams. B. Mountain climbing. C. Weekend plan.
第二节(共15小题;每小题1.5分，满分22.5分)
听下面5段对话或独白。每段对话或独白后有几个小题，从题中所给的A、B、C三个选项中选出最佳选项。听每段对话或独白前，你将有时间阅读各个小题，每小题5秒钟;听完后，各小题将给出5秒钟的作答时间。每段对话或独白读两遍。

高中英语真题：Unit5Thepowerofnature_43

Unit5Thepowerofnature第一部分阅读理解（共两节，满分40分）第一节（共15小题，每小题2分，满分30分）AA new collection of photos brings an unsuccessful Antarctic voyage back to life.Frank Hurley’s pictures would be outstanding----undoubtedly first-rate photo-journalism---if they had been made last week. In fact, they were shot from 1914 through 1916, most of them after a disastrous shipwreck (海滩), by a cameraman who had no reasonable expectation of s urvival. Many of the images were stored in an ice chest, under freezing water, in the damaged wooden ship.The ship was the Endurance, a small, tight, Norwegian-built three-master that was intended to take Sir Ernest Shackleton and a small crew of seamen and scientists, 27 men in all, to the sout hernmost shore of Antarctica’s Weddell Sea. From that point Shackleton wanted to force a passage by dog sled(雪橇) across the continent. The journey was intended to achievemore than what Captain Robert Falcon Scott had done. Capt ain Scott had reached the South Pole early in 1912 but had di ed with his four companions on the march back.As writer Caroline Alexander makes clear in her forceful and well-researched story The Endurance, adventuring was even then a thoroughly commercial effort. Scott’s last journey, complete d as he lay in a tent dying of cold and hunger, caught the worl d’s imagination, and a film made in his honor drew crowds. Sh ackleton, a onetime British merchant-navy officer who had got to within 100 miles of the South Pole in 1908, started a business before his 1914 voyage to make money from movie and still photography. Frank Hurley, a conf ident and gifted Australian photographer who knew the Antarc tic, was hired to make the images, most of which have never before been published.1. What do we know about the photos taken by Hurley?A. They were made last weekB. They showed undersea sceneriesC. They were found by a cameramanD. They recorded a disastrous adventure2 Who reached the South Pole first according to the text?A. Frank HurleyB. Ernest ShackletonC. Robert Falcon ScottD. Caroline Alexander3 What does Alexander think was the purpose of the 1914 vo yage?A. Artistic creationB. Scientific researchC. Money makingD. Treasure huntingBPassenger pigeons（旅鸽）once flew over much of the United States in unbelievable num bers. Written accounts from the 18th and 19th centuries descr ibed flocks（群）so large that they darkened the sky for hours.It was calculated that when its population reach its highest poi nt, there were more than 3 billion passenger pigeons – a num ber equal to 24 to 40 percent of the total bird population in the United States, making it perhaps the most abundant birds in t he world. Even as late as 1870 when their numbers had alrea dy become smaller, a flock believed to be 1 mile wide and 32 0 miles (about 515 kilometers) long was seen near Cincinnati. Sadly, the abundance of passenger pigeons may have been their undoing. Where the birds were abundant, people believ ed there was an ever-lasting supply and killed them by the thousands. Commercial hunters attracted them to small clearings with grain, waited un til pigeons had settled to feed, then threw large nets over the m, taking hundreds at a time. The birds were shipped to large cities and sold in restaurants.By the closing decades of the 19th century, the hardwood fore sts where passenger pigeons nested had been damaged by A mericans’ need for wood, which scattered（驱散）the flocks and forced the birds to go farther north, where cold temperatures and spring storms contributed to their decline. S oon the great flocks were gone, never to be seen again.In 1897, the state of Michigan passed a law prohibiting the killi ng of passenger pigeons, but by then, no sizable flocks had b een seen in the state for 10 years. The last confirmed wild pig eon in the United States was shot by a boy in Pike County, O hio, in 1900. For a time, a few birds survived under human car e. The last of them, known affectionately as Martha, died at the Cincinnati Zoological Garden in September 1, 1914.4 In the 18th and early 19th centuries, passenger pigeons __ _____.A．were the biggest bird in the world.B．lived mainly in the south of America.C．did great harm to the natural environment.D．were the largest population in the US.5 The underlined word “undoing” probably refers to the pigeo ns’ _______.A．escape B．ruin C．liberation D．evolution6 What was the main reason for people to kill passenger pig eons?A．To seek pleasure. B．To save other birds.C．To make money. D．To protect crops.7 What can we infer about the law passed in Michigan? A．It was ignored by the public. B．It was declared too late. C．It was unfair. D．It was strict.CSurviving Hurricane Sandy(飓风桑迪)Natalie Doan,14, has always felt lucky to live in Rockaway, N ew York. Living just a few blocks from the beach, Natalie can see the ocean and hear the wave from her house. “It’s the oc ean that makes Rockaway so special,” she says.On October 29, 2012, that ocean turned fierce. That night, Hu rricane Sandy attacked the East Coast, and Rockaway was hi t especially hard. Fortunately, Natalie’s family escaped to Bro oklyn shortly before the city’s bridge closed.When they returned to Rockaway the next day, they found the ir neighborhood in ruins. Many of Natalie’s friends had lost the ir homes and were living far away. All around her, people wer e suffering, especially the elderly. Natalie’s school was so da maged that she had to temporarily attend a school in Brooklyn .In the following few days, the men and women helping Rocka way recover inspired Natalie. Volunteers came with carloads of donated clothing and toys. Neighbors devoted their spare ti me to helping others rebuild. Teenagers climbed dozens of fli ghts of stairs to deliver water and food to elderly people trapp ed in powerless high-rise buildings.“My mom tells me that I can’t control what happens to me,” Natalie says. “but I can always choose how I deal with it.”Natalie’s choice was to help.She created a website page matching survivors in need with d onors who wanted to help. Natalie posted introduction about a boy named Patrick, who lost his baseball card collection whe n his house burned down. Within days, Patrick’s collection wa s replaced.In the coming months, her website page helped lots of kids: C hristopher, who received a new basketball; Charlie, who got a new keyboard. Natalie also worked with other organizations to bring much-need supplies to Rockaway. Her efforts made her a famous p erson. Last April, she was invited to the White House and hon ored as a Hurricane Sandy Champion of Change.Today, the scars(创痕)of destruction are still seen in Rockaway, but hope is in the air. The streets are clear, and many homes have been rebuilt . “I can’t imagine living anywhere but Rockaway,” Natalie decl ares. “My neighborhood will be back, even stronger than before.”8. When Natalie returned to Rockaway after the hurricane ,she found______.A. some friends had lost their livesB. her neighborhood was destroyedC. her school had moved to BrooklynD. the elderly were free from suffering9. According to paragraph4,who inspired Natalie most?A. The people helping Rockaway rebuild.B. The people trapped in high-rise building.C. The volunteers donating money to survivors.D. Local teenagers bringing clothing to elderly people.10. How did Natalie help the survivors?A. She gave her toys to the kids.B. She took care of younger children.C. She called on the White House to help.D. She built an information sharing platform.11.What does the story intend to tell us?A. Little people can make a big difference.B. A friend in need is a friend indeed.C. East or West, home is best.D. Technology is power.DWhat Theresa Loe is doing proves that a large farm isn’t prere quisite for a modern grow-your-own lifestyle. On a mere 1/10 of an acre in Los Angeles, Loe and her family grow, can（装罐）and preserve much of the food they consume.Loe is a master food preserver, gardener and canning expert. She also operates a website, where she shares her tips and r ecipes, with the goal of demonstrating that everyone has the ability to control what’s on their plate.Loe initially went to school to become an engineer, but she quickly learned that her enthusiasm was mainly about growin g and preparing her own food. “I got into cooking my own foodand started growing my own herbs (香草) and foods for that fresh flavor,” she said. Engineer by day, Loe learned cooking at night school. She ultimately purchase d a small piece of land with her husband and began growing t heir own foods.“I teach people how to live farm-fresh without a farm,” Loe said. Through her website Loe emp hasizes that “anybody can do this anywhere.” Got an apartme nt with a balcony （阳台）? Plant some herbs. A window? Perfect spot for growing. Start with herbs, she recommends, because “they’re very forg iving.” Just a little of the herbs “can take your regular cooking to a whole new level,” she added. “I think it’s a great place to start.”“Then? Try growing something from a seed, she said, li ke a tomato or some tea.”Canning is a natural extension of the planting she does. With every planted food, Loe noted, there’s a moment when it’s bur sting with its absolute peak flavor. “I try and keep it in a time c apsule in a canning jar,” Loe said. “Canning for me is about k nowing what’s in your food, knowing where it comes from.”In addition to being more in touch with the food she’s eating, a nother joy comes from passing this knowledge and this desire for good food to her children: “Influencing them and telling them your opinion on not only being careful what we eat but un derstanding the bigger picture,” she said, “that if we don’t take care of the earth, no one will.”12.The underlined word “prerequisite” (Pare. 1) is closest in m eaning to “______”.A. recipeB. substituteC. requirementD. challenge13. Why does Loe suggest starting with herbs?A. They are used daily.B. They are easy to grow.C. They can grow very tall.D. They can be eaten uncooked.14. According to Loe, what is the benefit of canning her planted foods?A. It can preserve their best flavor.B. It can promote her online sales.C. It can better her cooking skills.D. It can improve their nutrition.15. What is the“the bigger picture” (Para. 6) that Loe wishes h er children to understand?A. The knowledge about good food.B. The way to live a grow-our-own life.C. The joy of getting in touch with foods.D. The responsibility to protect our earth.第二节（共5小题，每小题2分，满分10分）根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。

Diffraction at HERA

$Diffraction at HERA$

a rXiv:h ep-ph/973245v15Mar1997DIFFRACTION AT HERA Nicol`o Cartiglia Columbia University,Nevis Laboratories,136South Broadway,Irvington N.Y.,10533USA Representing the H1and ZEUS Collaborations ABSTRACT Recent results on diﬀraction at HERA,as measured by the H1and ZEUS collaborations,are reviewed.Results on the photon-proton total hadronic cross section,on vector meson production both at small and large photon virtuality and on photon diﬀraction are presented.The experimental signature of diﬀraction at HERA,as well as the selection methods used by the two collaborations are explained.Contents1Introduction42Diﬀraction and total cross section4 3Total cross section at HERA6 4Kinematics of diﬀractive events at HERA75Experimental signature of diﬀraction at HERA95.1Rapidity gaps (9)5.2Leading proton in theﬁnal state (11)6Models for diﬀractiveγ∗p scattering127Vector meson production:γp→Vp157.1Experimental signature and selection methods forγp→Vp (17)7.2Light vector meson production at Q2=0 (18)7.3Vector meson production with a hard scale (22)7.3.1Slope parameter b and R=σL/σT vs Wγp and Q2 (23)7.3.2Determination ofα′at large Q2 (25)I P7.3.3Restoration of SU(4)symmetry at high Q2 (26)8Photon diﬀraction:γp→X Y278.1Experimental signature and selection methods forγp−→XY..278.1.1Maximum pseudorapidityηmax(ZEUS,H1) (28)8.1.2Largest rapidity gap(H1) (28)8.1.3Leading proton measurement(ZEUSMX) (30)8.2Determination ofαand test of factorization (31)I Pat Q2≃0Ge V2 (32)8.2.1Determination ofαI P8.2.2Determination ofαat large Q2 (33)I P8.2.3Comparison of the results (37)8.3Measurement of the slope parameter b in diﬀractive DIS (39)8.4Partonic structure of diﬀractive exchange (39)8.4.1QCDﬁt to the diﬀractive structure function (39)8.4.2Jet structure (41)8.5σdif/σtot as a function of Q2 (43)9Central rapidity gaps44 10Conclusions46 11Acknowledgements471IntroductionPhoton-proton collisions have been extensively studied inﬁxed target experiments up to centre of mass energies,Wγp,of about20GeV,using both real and virtual photons.At the HERA collider at DESY,820GeV protons collide with27.5GeV electrons or positrons.The HERA physics program is very rich,ranging from non-perturbative to perturbative QCD,heavy-ﬂavour physics and to the measurement of the quark and gluon densities in the proton and in the photon.Two general purpose detectors,H11and ZEUS2,operate at HERA and are instrumented with high resolution calorimeters and tracking chambers.The results presented here have been obtained using data collected during1994 and1995,for a total of about9pb−1.More detailed presentations on individual subjects can be found in many proceedings3.2Diﬀraction and total cross sectionHistorically,hadronic diﬀraction processes and total cross sections have been de-scribed using the concept of‘pomeron exchange’.The simplest way to introduce the concept of pomeron is within the framework of Regge theory4,5.Consider the example shown in Fig.1:π−p→πo n where t is the4-momentum transfer. According to quantum numbers conservation,this reaction might happen via the exchange of a virtualρ0,a2,g hadron.If the values of the masses and spins of these particles are plotted on the right hand side of the spin-t plane(where t is positive),they lie almost on a straight line determining a’trajectory’of particles. The general expression for a straight line trajectory is:α(t)=α(0)+α′·t,whereα(0)is the intercept andα′the slope.The most important trajectories are approximately linear with a universal slopeα′=0.9Ge V2;theﬁrst particle on a trajectory gives the name to the trajectory itself(in the above example theρtrajectory is exchanged).Regge theory predicts that the properties of a t-channel reaction(that happens on the left hand side of the spin-t plane,where t is negative,via the exchange of oﬀmass shell particles),π−p→πo n for example,are determined by the parameters of the trajectory formed by the exchanged particles on the right hand side of the spin-t plane(theρtrajectory in the case above).α(t) p n π−πFigure1:Schematic diagram forπ−p→πo n scattering and the exchanged trajectory.Let’s consider the dependence of the total cross section(a t-channel process) with the square of the centre of mass energy s.According to Regge theory it is parametrized as:σtot(s)∝ k sαk(0)−1,(1) whereαk(0)=1,..n,are the intercepts of the trajectories ing only two main trajectories,σtot(s)for p¯p,pp,K±p,π±p,γp have beenﬁtted by Don-nachie and Landshoﬀ6with an expression of the form:σtot(s)=Xs0.0808+Ys−0.4525,where X,Y are parameters which depend on the exchangedﬁeld.Theﬁrst tra-jectory,called pomeron trajectory,has interceptαI P(0)=1.0808while the second term,which represents an eﬀective meson trajectory,has interceptαk(0)=0.545. At high enough energy,only the pomeron term is important.The pomeron,iden-tiﬁed as theﬁrst particle of the pomeron trajectory,is responsible for the rise of the total cross section as a function of the centre of mass energy.Since the bulk of the processes contributing to the total cross section has very small p t,the pomeron exchanged in these reactions is called‘soft pomeron’.The soft pomerontrajectory has interceptαI P(0)≃1.08and slopeα′≃0.25Ge V2.Fig.2schematically shows three diﬀerent types of diﬀractive reactions:elastic scattering(a),single diﬀraction(b),where one of the incoming particle dissociates, and double diﬀraction(c),where both incoming particles dissociate.In diﬀractive scattering the hadronization of theﬁnal states X and Y with masses M2Y,M2X happens independently,as shown in Fig.2(d).If the centre of mass energy√lnM 2x P P a a’b Y b b’b’blnM 2y yln(s)a)c)b)d)P I aI a XX P I Figure 2:Diagrams for three diﬀerent types of diﬀractive reactions:elastic scattering (a),single diﬀraction (b)where one of the incoming particle fragments and double diﬀraction (c).(d)shows energy ﬂow as a function of rapidity for ln(s)≫ln(M 2Y )+ln(M 2X ).ExperimentW γp 167<W γp <194H1σγp tot =165±2±11µbTable 1:Summary of experimental results on the measurements of σtot at HERA.3Total cross section at HERA The values of the total hadronic γp cross section at HERA as measured by the H17and ZEUS 8collaborations are shown in Fig.3together with a compilation of low energy results.The Donnachie and Landshoﬀparametrizations including (dotted line)or not (solid line)recent CDF 9results and the ALLM 10parametriza-tion (dashed line)are also shown.The HERA data are in agreement with these predictions and therefore with the assumption that also at HERA ‘soft’pomeronexchange is responsible for the increase of σγp tot as a function of the centre of massenergy.The diﬀractive cross section represents a large fraction of the total cross sec-tion:at HERA,for example,the diﬀractive and non diﬀractive parts are,accord-ing to the H1collaboration 7,σγp dif =69.2±13.2µb and σγp non −dif =96.1±17.9µb,giving σdif /σtot =(42±8)%,while according to the ZEUS collaboration8σdif /σtot =(36±8)%.110100100150200Figure 3:Total γp cross section as a function of W γp .The results are shown together with two parametrizations from Donnachie and Landshoﬀthat include (dotted line)or not (solid line)recent CDF results and with the ALLM parametrization (dashed line).4Kinematics of diﬀractive events at HERAIn Fig.4,a diagram for diﬀractive ep scattering is shown.A photon γ∗(Q 2)with virtuality −q 2=Q 2is emitted at the electron vertex ∗.Depending on the value of Q 2,the events are divided into two large families:photoproduction,for Q 2<4Ge V 2,and deep inelastic scattering (DIS),for Q 2>4Ge V 2.s =(k +p)2is de-ﬁned as the centre of mass energy squared of the ep system while W γp 2=(q +p)2is used to indicate the centre of mass energy of the virtual photon-proton (γp)system.At large Q 2,in the frame where the proton has inﬁnite momentum,the variable x Bj =Q 2∗The symbol γis used for quasi real photon while the symbol γ∗is used for virtual photon.tum fraction of the pomeron in the proton.Figure4:Diagram for diﬀractive scattering at HERA.If the reaction is elastic or single diﬀractive(or photon diﬀraction as sometimessingle diﬀraction is called for the HERA regime),then the quantities t and xI Pcan be determined either from the scattered proton or from the system M X.If the longitudinal and transverse momentum of the scattered proton,p′z,p′⊥,are measured,then xI Pand t are calculated as:x L≃p′z/E p−→x I P=1−x L(2)t=(P−P′)2≃−(p′⊥)2xL(3) where m p is the proton mass.If the proton is not observed,a measurement ofxI Pcan be obtained as:x I P =(P−P′)·qW2+Q2−m2p,(4)where M X is the mass of the system X.t can be reconstructed from the system X only for some exclusive reactions,such as vector meson production,where the resolution on p′⊥is accurate enough.5Experimental signature of diﬀraction at HERAOne of the main issues concerning diﬀraction at HERA is the experimental method to separate diﬀractive from non-diﬀractive events.For some exclusive reactions the distinction is actually quite easy.Let’s consider for example exclusiveρ0 production and decay:γp−→ρ0pρ0−→π+π−.The central detector is empty,except for the two tracks coming from theρ0decay. This topology is very unusual and the background from‘non-pomeron’exchange is negligible.Inclusiveγdiﬀraction,γp→Xp,is on the other hand more diﬃcult to identify.Two quantities can help in the distinction:a rapidity gap in theﬁnal state particles production and/or the presence of a highly energetic scattered proton.5.1Rapidity gapsθflow Energy3.5 1.50-1.5peeDetectorηFigure5:Energyﬂow vsηfor non diﬀractive ep scattering at HERA.Fig.5schematically shows the energyﬂow as a function of pseudorapidityηfor non diﬀractive ep scattering at HERA†.Aside from the recoil electron,two maingroups of particles can be identiﬁed:particles produced at high rapidity in the hadronization of the proton remnant,and particles produced in the hadronization of the photon-parton system,typically at small or negative rapidity.In deep inelastic scattering,for example,the struck parton is deﬂected and emerges from the proton remnant at an angleθq.It is useful to express this angle as the diﬀerence in pseudorapidity between the struck parton and the proton remnant:∆η=ηproton remnant−ηparton.(5) Since the pseudorapidity interval covered by a system with centre of mass energy √m2p)(6) with m p the proton mass,then we can show that the pseudorapidity interval between the proton remnant and the struck quark is:∆η∼ln(Wγp2m2p)∼ln(1m2p)is the total rapidity covered by theγ-p system and ln(x Bj W2γpIP, R 3.5 1.50-1.5flowEnergyvisible gape epDetectorηFigure 6:Energy ﬂow vs ηfor diﬀractive ep scattering at HERA.I P exchange:αI P (0)∼1⇒p(∆η)∼e 0ρ,a 2,f 2,ωexchange:αR (0)∼0.5⇒p(∆η)∼e −∆ηπexchange:απ(0)∼0⇒p(∆η)∼e −2∆η.Therefore,even though ρ,πand I P are colourless exchanges,only I P exchange produces rapidity gaps that are not suppressed as the gap width increases.It is therefore possible to operationally deﬁne diﬀraction 15by the presence of a rapidity gap:diﬀractive events are those which lead to a large rapidity gap in ﬁnal state phase space and are not exponentially suppressed as a function of the gap width.5.2Leading proton in the ﬁnal stateIn diﬀractive events,the incoming beam particles,when they do not dissociate,conserve a large fraction of their initial momentum.At HERA the diﬀractively scattered proton carries on average more than 99%of its initial momentum.The cross sections for non diﬀractive processes to produce so energetic protons is very small compared with the diﬀractive cross section making the detection of a high energy proton a clean tag for diﬀractive physics.Fig.7schematically shows the spectra of leading protons generated from diﬀerent mechanisms:at x L ≃1single diﬀraction is almost the sole component,while moving away from x L =1double diﬀraction and reggeon exchange become important.Traditionally,x L =0.9has been used to indicate the x L value at which the diﬀractive and not diﬀractive part of the spectrum are equal.Leading protons can also be produced in ‘standard’DIS events as part of the proton remnant jet,but they have on average a much lower x L value.A recent release of the LEPTO MonteCarlo 16,on the other hand,includes leading protons production in the fragmentation of the proton remnant with a cross section comparable to reggeon exchange.Note that the distinction between the diﬀerent mechanisms for leading protons production is somehow arbitrary and there might be a lot of overlap.PomeronDISxLR, Doubl. Diff0.9 1.0.5 dNdxLFigure 7:Spectra of leading proton generated from diﬀerent mechanisms:pomeron exchange (dashed line),reggeon exchange and double diﬀraction (dotted line)and ‘standard DIS (solid line)as a function of x L .In the transverse plane,leading protons have rather small momentum,with a typical p 2⊥distribution of the form:dNPomeron)with QCD concepts(like gluons).Here we present a brief description of some of the ideas on which the models are based.-Factorization of vertices and pomeron structure function:Factoriza-tion considers the I Pp vertex as independent of the I Pγ∗interaction.A universal pomeronﬂux factor f I P/p(x I P,t)characterises the I Pp vertex and parametrizations obtained fromﬁts to pp and p¯p diﬀractive data can be used in ep collisions.Sev-eral diﬀerent expressions for f I P/p(x I P,t)have been proposed17–19which all include an exponential dependence on t of the type e−b|t|with b∼5-8Ge V−2and a de-pendence on the pomeron longitudinal momentum xI Pof the type∼1/x I P.These models express the diﬀractiveγ∗p cross section asσγ∗p(Q2,β,xI P ,t)∝f I P/p(xI P,t)·σγ∗I P(Q2,β),(9)and describe deep inelasticγ∗p andγ∗I P interactions in the same way:the incom-ingγ∗interacts with one component of the target leaving behind a remnant.For γ∗I P interaction the scaling variable that plays the same role of x Bj is:β=Q2M2X+Q2.(10)Theγ∗I P cross section can then be written as:σγ∗I P tot (Q2,β)=4π2αemnot well deﬁned in terms of partons;in particular,factorization is not a natural consequence.To compare the predictions from this approach to those of the previ-ous type of model,an eﬀective I P structure function,F I P2eﬀ.(Q2,β),is introduced. In this picture,the interaction of the q¯q state generates a diﬀerent value ofαI P than the interaction of the q¯q g state25with an eﬀectiveαI Pincreasing at smallx I P (xI P≃10−4).Therefore the q¯q and q¯q gﬂuctuations have diﬀerent pomeronﬂuxes breaking the factorization mechanism.According to26,factorization is also broken by the exchange of longitudinal photons.The states are characterised by the transverse and longitudinal momentum(k⊥,z)of the q¯q pair(taken as an example)and by the quark mass(m q).The radius r2⊥of the state depends on the inverse of k2⊥·Q2and m2q:1M2X1Conversely,if r2⊥is small either because k2⊥·Q2(high Q2DIS events)or m2q (production of charm or bottom q¯q pair)is large,then the gluon-quark coupling is small and pQCD can be applied.-Soft color interaction:in this model28,diﬀractive scattering is viewed as dominated by the exchange of one‘hard’gluon plus non-perturbative color interactions to allow a color singletﬁnal state.7Vector meson production:γp→VpIn the range of centre of mass energy Wγp up to20GeV covered by pre-HERA experiments,this process has been described very successfully within the frame-work of Vector Dominance Model(VDM)29.In this model,the photon is assumed toﬂuctuate into a virtual vector meson which then interacts elastically with the proton via the exchange of a pomeron,Fig.9(a).From VDM one expects:σγp→Vp=4παdt)t=0=A·σ2tot,(13) with A=constant.Then we can express the elastic cross section at any t value as: dσγp→Vpdt)t=0·e f(t)=A·σ2tot·e f(t),(14) where f(t)is the functional dependence of the cross section on t.For vector meson production,according to Regge theory,f(t)can be written as:f(t)=t·(b0+2α′I P·ln(Wγp 2/W2)),(15)where b0and W20are ing eq.15into eq.14,integrating over t and writing explicitly the dependence from the centre of mass energy Wγp,we obtain:σγp→Vp(Wγp)∝(Wγp2)2·(αI P(0)−1)It is very important to note that this reasoning is based on the assumption,sup-ported by pre-HERA data,that the same underlying exchange governs both the total and vector meson cross section.Recent papers30–32have shown that the situation at HERA,given the large value of Wγp,might be qualitatively diﬀerent if a hard scale is present in the interaction.Under these circumstances,the process is calculable in QCD.The approach outlined in Section(6)is used:the photonﬂuctuates into a q¯q pair whichﬁrst interacts with the target and then the meson is formed Fig.9(b).TheVector Meson Vector MesonIPIPb)a)Figure9:Diﬀerent models forγp→Vp:(a)vector meson dominance,(b)photon diﬀraction. scale of the interaction is given by the reciprocal of theﬂuctuation radius r2⊥and therefore,if either k2⊥·Q2,t or m2q is large,the process is hard.Since the transverse momentum k2⊥generated at the photon-quark vertex is diﬀerent for longitudinally and transversely polarised photons,withσγL·p dominated by large k2⊥andσγ⊥·p dominated by small k2⊥,early papers dealt only with the former photon tely33also predictions forσγ⊥·p have been made.The pQCD approach has been used to calculate the magnitude and energy dependence of the cross section for photoproduction of J/ψmesons30,where the charm mass ensures a hard scale,and production ofρ0mesons at high Q231.In both cases,the q¯q pair resolves the gluonic contents of the proton giving a cross section proportional to the proton gluon distribution squared‡:σVp∝[αs(¯q2)¯x g(¯x,¯q2)]2.(17) The energy dependence is therefore no longer determined by the pomeron intercept but by the rise of the gluon distribution at low x Bj.VM decay mode ref.ref.X XX XX XXXX§References from44to51are contribution to ICHEP1996,Warsawing on each detector forward coverage),the event looks elastic and is included in the sample.On the contrary,if M Y is large,energy deposition in the calorimeter can be used as a veto.The CDF Collaboration 52measured the mass spectrum ofthe system Y in p¯p diﬀraction to be dN /dM 2Y =1/M n Y with n =2.2.This result,however,has not been obtained in the very low mass region and therefore should be used only as an indication.A more direct method used by both the H1and ZEUS collaborations is to model the visible energy deposition due to high M Y states as a function of n to determine which value ﬁts the data best and use it to perform the background subtraction.Yc)e b)a)YDiffractive p-dissociation with high M Figure 10:Double dissociation background to single dissociation.b)If the mass M Y of the excited proton system is small the event looks like single diﬀraction and is included in the sample of elastic vector meson production.c)For large M Y ,energy deposition in the calorimeter can be used as a veto.7.2Light vector meson production at Q 2=0The energy dependence of the total cross sections for light mesons (ρ0,ω,φ)and J/ψphotoproduction,as measured by ZEUS and H1are shown in Fig.11.TheRegge theory prediction σγp →Vp (W γp )∝W 0.22γp is clearly supported by the data.A summary of experimental results on the measurements of σtot ,b and r 0400in pho-toproduction is given in Tab.3.The b values are consistent with parametrizations of low energy data and with the ‘shrinkage mechanism’expected in Regge the-Reactionσ(µb)r0400ZEUS10.4±0.6±1.1ZEUS LPS9.9±0.8±1.1H110.9±2.4±1.1ZEUS LPS 5.3±0.8±1.1ZEUS10.0±1.2±1.4ZEUS7.3±1.0±0.8dt=A·e b·t+c·t2,(18) where c is called‘curvature’.The local slope parameter,deﬁned as:b(t)=ddt)=b+2ct(19)is a decreasing function of t.An example is given in Fig.12for the case of the ρ0meson.Fits to hadronic scattering data yield to very similar results:b= 11.7Ge V−2and c=3.16GeV−4for pp scattering and b=9.9Ge V−2and c=3.47GeV−4forπp scattering measured at s=400Ge V2in the interval 0.02<|t|<0.66Ge V2.The common behaviour of the cross section as a function of t is due to the very similar hadronic form factors for pion,proton and photon.The parameter b has been recently measured by the ZEUS collaboration inρ0 photoproduction using data from the Leading Proton Spectrometer54.This is theFigure11:Total and elastic vector meson photoproduction measurements as a function of Wγp.The curve overlapped toσtot is the DL parametrization Wγp0.16.The other lines are curves of the form Wγp0.22and Wγp0.80.ﬁrst diﬀractive cross section measurement at HERA in which the forward scattered proton is detected and its momentum measured.This makes possible a direct determination of the squared four-momentum t exchanged at the proton vertex. The LPS consists of siliconµ-strip detectors placed close to the proton beam by means of rentrant Roman pots and detects forward going protons scattered at angles≤1mrad.The momentum of the proton is measured using the elements (quadrupoles and dipoles)of the proton beam line,and it is reconstructed with a resolution of∆p/p≃0.3%at p≃820GeV/c.The total systematic error on the measurement of b in this analysis is11%,the main source being the uncertainty on the acceptance(∼7%),and the uncertainty coming from the unfolding of the beam transverse momentum spread(∼7%).It should be noted that the uncertainty coming from the proton dissociation background is negligible,when compared to analyses which do not make use of the LPS:for LPS tagged eventsthe contamination has been estimated to be0.21±0.15%while a previous ZEUS result estimated the contamination to be11±6%.Tagging with the LPS a leading proton with a value of x L<0.97has also allowed to select a clean sample of photoproduction double diﬀractiveρ0events,γp→ρ0X. Using the transverse momentum from the decay pions,the slope parameter b has been determined to be bγp→ρ0X=5.3±0.8±1.1Ge V−2.Fig.13and Table3LPSshow the results for both single and double diﬀraction.Fixed target experiments showed,at much lower Wγp,that vector mesons retained the helicity of the photon(s-channel helicity conservation,SCHC).This eﬀect was also investigated at HERA.The results can be expressed in terms of the r0400spin-density matrix element which gives the probability for the meson to have zero helicity.As shown in the Tab.3,all the measurements are consistent with a zero value for r0400,as required by SCHC.Figure12:Measurement of the slope parameter for the reactionγp→ρ0p.A quadratic function in t,dσFigure13:(a)Slope parameter b for the reactionγp→ρ0p as obtained from the measurement of the scattered proton.The value b=9.8has been modiﬁed to b=9.9in theﬁnal analysis.(b) Slope parameter b for the reactionγp→ρ0X obtained by tagging a low energy proton in the LPS and measuring p2t in the tracking chamber.7.3Vector meson production with a hard scaleIn contrast to the previous results,the cross sections for J/ψphotoproduction and light vector meson production at high Q2show a signiﬁcant rise with Wγp. In particular,for the J/ψcase the rise is clearly visible within the range of HERA data while for the light vector mesons the rise is observed in comparison with lower energy data.Fig.11and Fig.14show the eﬀect for the J/ψandρ0case.dependence used in the parametrizations The rise is inconsistent with the W0.22γpof low energy hadronic data.The measured behaviour can be described instead by perturbative QCD models if a rise at small x Bj of the gluon momentum density in the proton is assumed.Both the shape of the rise and the normalisation could in principle be used to discriminate between models of the gluon distributions but since the latter suﬀers from large theoretical uncertainty,only the shape is used. Fig.15shows the experimental results and the expectation based on diﬀerent gluon parametrizations for theρ0cross section as a function of x Bj in four diﬀerent Q2bins.The comparison is still dominated by experimental errors but since the parametrizations are quite diﬀerent,potentially this approach can be an invaluable tool to rule out many of the current options.These results show that the cross section for vector meson production in the presence of a hard scale has a steeper energy dependence than the total hadronic γp cross section.50101010110Figure 14:γp →ρ0p cross section as a function of W γp for diﬀerent <Q 2>values (as indi-cated in the picture).The lines are the results of ﬁts to the form σ∝W γp k ,the values of k are shown in parenthesis.7.3.1Slope parameter b and R =σL /σT vs W γp and Q 2The slope parameter b is related to the eﬀective radius of the interaction R by:R =1994 ZEUS preliminaryFigure15:γp→ρ0p cross section as a function of x Bj for diﬀerent values of<Q2>.The lines are prediction from a calculation based on pQCD using diﬀerent gluon distributions.4-5GeV−2is approximately equal to what is expected from the size of the proton.Both the H1and ZEUS collaborations have studied the ratio between the longitudinal and transverse cross section forρ0production,R=σLσT∝Q2σ⊥≃Q2γ+1)2.(22)Q 2+M 2VM[ GeV 2]b [ G e V 2]02468101214Figure 16:Exponential slope b for vector meson production as a function of Q 2+M 2VM .Since γdecreases with Q 2,a less steep dependence is obtained that seems to ﬁtthe data quite well.Within the current experimental accuracy,R does not seemQ 2 [ GeV 2]R =σL /σT -1012345678Figure 17:Ratio R =σL /σ⊥for the reaction γp →ρ0p as a function of the photon virtualityQ 2.to depend on W γp .7.3.2Determination of α′I Pat large Q 2As we have seen,where Regge theory holds,the value of b should increase withenergy according to the ‘shrinkage’mechanism.The HERA data on photopro-duction of ρ0,φ,ωare consistent with this prediction.At high Q 2there are no pre-HERA measurements of the ‘shrinkage’mechanism.According to 56,α′I P ≃=0.2Ge V −2.Therefore the value of the slope parameter b should increase by ∼1.5Ge V −2going from low energy,W γp ∼10GeV,to the HERA regime,W γp ∼100GeV,for all exclusive reactions of the kind γ∗p →Vp.On the other hand,according to 57,the value of α′I P is expected to be α′I P ∼1/Q 2for reactions where the hard QCD regime dominates,leading to a ﬂat behaviour of b as a function of W.Fig.18shows the b values for the ρ0measurements as a function of W γp at high Q 2.The experimental data are still dominated by statistical errors and therefore no meaningful conclusion can be drawn.On the plot,the expected trend of b vsW γp is plotted if a value of α′I P =0or 0.25is assumed.0246810Figure 18:Exponential slope b for the reaction γp →ρ0p as a function of W γp .On the plot,the expected trend of b vs W γp is plotted if a value of α′I P =0or 0.25is assumed.7.3.3Restoration of SU(4)symmetry at high Q 2According to the SU(4)ﬂavour symmetry,when M 2V ≪Q 2,the ratio amongcross sections for diﬀractive vector meson production should depend only on the mesons wavefunction and quark charges 55:ρ:ω:φ:J /Ψ=[12(u¯u +d ¯d)]2:[12(u¯u −d ¯d)]2:[s¯s ]2:[c¯c ]2=9:1:2:8.(23)。