1998 J. Li, A unified approach from elasticity to viscoelasticity to viscoplasticity of particle-rei
沿轴向指数分布的功能梯度Timoshenko梁的频率精确解
沿轴向指数分布的功能梯度Timoshenko梁的频率精确解邓昊;程伟【摘要】Based on the state space variable replacement,the transfer matrix equation of a Timoshenko beam with axially exponential distributed functional gradation was derived.The exact solution of natural frequencies of the structure with multiple boundary conditions was obtained by the transfer matrix method and compared with the available analytical solution.The results show that the relation curve between the frequency and the gradient of the material is continuous and smooth,and there is no jumping phenomenon.Meanwhile the finite element method was used to verify the results.The effects of shear stiffness and moment of inertia on the natural frequencies of the structure were analyzed by comparing the results according to different beam theories.The calculation results show that the method presented is clear in physical concept and can reduce the computational complexity and the amount of computation.%通过对状态空间变量进行变量替换,求得了沿轴向指数分布的功能梯度Timoshenko梁的状态空间传递矩阵方程.通过传递矩阵法计算了多种边界条件下结构固有频率的精确解,并与解析解进行对比.通过分析梯度参数对结构固有频率与模态振型的影响,该计算结果表明频率与材料梯度变量之间的关系曲线是连续光滑的,并未出现部分文献中的跳跃现象,并且采用有限元法该计算结果进行验证.通过对比不同梁理论的计算结果,定量的分析了剪切刚度和转动惯量对结构固有频率的影响.计算结果表明,该方法物理概念清晰,降低问题求解难度的同时可以减少计算量.【期刊名称】《振动与冲击》【年(卷),期】2017(036)006【总页数】7页(P91-96,113)【关键词】状态空间变量;传递矩阵法;固有频率;功能梯度材料;指数梯度【作者】邓昊;程伟【作者单位】北京航空航天大学航空科学与工程学院,北京100191;北京航空航天大学航空科学与工程学院,北京100191【正文语种】中文【中图分类】TV312工程中存在着大量的多相材料，为了使材料的性质从一相过渡到另一相，通常在两相材料之间使用沿轴向变化的功能梯度材料。
1998考研英语作文
1998考研英语作文In 1998, I decided to take the postgraduate entrance exam. It was a tough decision, but I knew it was the right path for me. The exam was challenging, and I spent countless hours studying and preparing. I was determined to succeed, and I pushed myself to the limit.The day of the exam arrived, and I felt a mix of nerves and excitement. The test was grueling, and there were moments when I doubted myself. But I persevered, and I gave it my all. When the results came out, I was overjoyed to see that I had passed. It was a moment of triumph and validation for all the hard work I had put in.Going to graduate school was a whole new experience for me. The workload was intense, and the pressure was high. But I was determined to excel, and I threw myself into my studies. I made new friends and learned from some of the best professors in the field. It was a time of growth and self-discovery, and I cherished every moment of it.After two years of hard work, I finally completed my master's degree. It was a bittersweet moment, as I said goodbye to the friends and mentors who had helped me along the way. But I was also filled with a sense of accomplishment and pride. I had proven to myself that I was capable of achieving my goals, and I was ready to take on whatever challenges lay ahead.Looking back on 1998, I realize that it was a year of transformation and growth. The decision to take the postgraduate entrance exam set me on a path that would shape my future in ways I could have never imagined. It was a year of hard work, perseverance, and ultimately, success. And for that, I will always be grateful.。
1998年全国硕士研究生入学考试英语试题及答案
Part I Structure and Vocabulary Sections A Directions:Beneath each of the following sentences, there are four choices marked A）,B）,C）andD）.Choose the one that best completes the sentence. Mark your answer on the ANSWER SHEET I by blackening the corresponding letter in the brackets with a pencil. （5 points）Example: have been to the Great Wall three times _____ 1979.A）from B）after C）for D）sinceThe sentence should read,"I have been to the Great Wall three times since 1979."Therefore, you should choose D）.1.I worked so late in the office last night that I hardly had time _____ the last bus .A）to have caught B）to catchC）catching D）having caught2.As it turned out to be a small house party, we _____ so formally.A）needn't dress up B）did not need have dressed upC）did not need dress up D）needn't have dressed up3.I apologize if I _____ you, but I assure you it was unintentional .A）offend B）had offendedC）should have offended D）might have offended4.Although a teenager, Fred could resist _____ what to do and what not to do .A）to be told B）having been toldC）being told D）to have been told5.Greater efforts to increase agricultural production must be made if food shortage _____ avoided .A）is to be B）can beC）will be D）has been6.Doing your homework is a sure way to improve your test scores, and this is especially true _____ it comes to classroom tests .A）before B）asC）since D）when7.There are over 100 night schools in the city, making it possible for a professional to be re-educated no matter _____ he does .A）how B）whereC）what D）when8.I've kept up a friendship with a girl whom I was at school _____ twenty years ago .A）about B）sinceC）till D）with9.He wasn't asked to take on the chairmanship of the society, _____ insufficiently popular with all members .A）being considerd B）consideringC）to be considered D）having considered10._____ for the timely investment from the general public,our company would not be so thriving as it is .A）Had it not been B）Were it notC）Be it not D）Should it not beSection BDirections:Each of the following sentences has four underlined parts marked A）,B）,C）and D）. Identify the part of the sentence that is incorrect and mark your answer on ANSWER SHEET I by blackening the corresponding letter in the bracketswith a pencil. （5 points）Example:A number of A） foreign visitors were taken B） to the industrial exhibition which C） they saw D） many new products.Part C） is wrong. The sentence should read,"A number of foreign visitors were taken to the industrial exhibition where they saw many new products."So you should choose C）.11.According to Darwin,randon changes that enhance a species' A） ability for surviving B） are C） naturally selected and passed on to succeeding D） generations.12.Neither rain nor snow keeps A） the postman from delivering our letters which B）we so much C） look forward to receive D） .13.If they will not accept A） a check, we shall have B）to pay the cash C） , though it would be D） much trouble for both sides .14.Having been A） robbed off B）economic importance,those states are not C）likely to count for very much D） in international political terms.15.The message will be A） that B）neither the market nor the government is capable of dealing with all of their C） uncontrollable practices D） .16.The logic of scientific development is such A） that separates B）groups of men working on C） the same problem in far-scattered D） laboratories are likely to arrive at the same answer at the same time.17.Yet not all of these races are intellectual inferior to A） the European races, and B）some may even have a C） freshness and vitality that can renew the energies D） of more advanced races.18.The A） more than 50,000 nuclear weapons in the hands of various nations today are more than B）ample destroying C） every city in the world several times over D） .19.The universe works in a way so far remove A） from what common sense would B）allow that C） words of any kind must necessarily be inadequate to explain it D） .20.The integration of independent states could best be A） brought about by first B）creaing a central organization with authorities C） over technical D） economic tasks.Sections CDirections:Beneath each of the following sentences, there are four choices marked A）,B）,C）and D）. Choose the one that best completes the sentence. Mark your answer on ANSWER SHEET I by blackening the corresponding letter in the brackets with a pencil. （10 points）Example:The lost car of the Lees was found _____ in the woods off the highway.A）vanishedB）scattered C）abandonedD）rejectedThe sentence should read,"The lost car of the Lees was found abandoned in the woods off the highway."Therefore, you should choose C）.21.The machine needs a complete _____ since it has been in use for over ten years .A）amending B）fittingC）mending D）renovating22.There were many people present and he appeared only for a few seconds, soI only caught a _____ of him .A）glance B）glimpseC）look D）sight23.I don't think it's wise of you to _____ your greater knowledge in front of the director, for it may offend him .A）show up B）show outC）show in D）show off24.The returns in the short _____ may be small,but over a number of years the investment will be well repaid .A）interval B）rangeC）span D）term25.A thorough study of biology requires _____ with the properties of trees and plants,and the habit of birds and beasts .A）acquisition B）discriminationC）curiosity D）familiarity26.She worked hard at her task before she felt sure that the results would _____ her long effort .A）justify B）testifyC）rectify D）verify27.I'm very glad to know that my boss has generously agreed to _____ my debt in return for certain services .A）take away B）cut outC）write off D）clear up28.Some journalists often overstate the situation so that their news may createa great _____ .A）explosion B）sensationC）exaggeration D）stimulation29.According to what you have just said,am I to understand that his new post _____ no responsibility with it at all? .A）shoulders B）possessesC）carries D）shares30.Sometimes the student may be asked to write about his _____ to a certain book or article that has some bearing on the subject being studied .A）comment B）reactionC）impression D）comprehension31.Please _____ yourself from smoking and spitting in public places,since the law fotbids them .A）restrain B）hinderC）restrict D）prohibit32.Without telephone it would be impossible to carry on the functions of _____ every business operation in the whole country .A）practically B）preferablyC）precisely D）presumably33.Preliminary estimation puts the figure at aroun$110 billion, _____ the $160 billion the President is struggling to get through the Congress .A）in proportion to B）in reply toC）in relation to D）in contrast to34.He is planning another tour abroad,yet his passport will _____ at the end of this month .A）expire B）exceedC）terminate D）cease35.All the off-shore oil explorers were in high spirits as they read _____ letters from their families .A）sentimental B）affectionateC）intimate D）sensitive36.Several international events in the early 1990s seem likely to _____ ,or at least weaken,the trends that emerged in the 1980s .A）revolt B）revolveC）reverse D）revive37.I was unaware of the critical points involved,so my choice was quite _____ .A）arbitrary B）rationalC）mechanical D）unpredictable38.The local people were joyfully surprised to find the price of vegetables no longer _____ according to the weather .A）altered B）convertedC）fluctuated D）modified39.The pursuit of leisure on the part of the employees will certainly not _____ their prospect of promotion .A）spur B）furtherC）induce D）reinforce40.In what _____ to a last minute stay of execution,a council announced that emergency funding would keep alive two aging satellites .A）applies B）accountsC）attaches D）amountsPart II Cloze TestDirections:For each numbered blank in the following passage, there are four choices marked A）,B）,C）,D）. Choose the best one and mark your answer on ANSWER SHEET I by blackening the corresponding letter in the brackets with a pencil. （10 points）Until recently most histroians spoke very critically of the Industrial Revolution. They 41 that in the long run industrialization greatly raised the standard of living for the 42 man. But they insisted that its 43 results during theperiod from 1750 to 1850 were widespread poverty and misery for the 44 of the English population. 45 contrast, they saw in the preceding hundred years from 1650 to 1750, when England was still a 46 agricultural country, a period of great abundance and prosperity.This view, 47 ,is generally thought to be wrong. Specialists 48 history and economics, have 49 two things:that the period from 1650 to 1750 was 50 by great poverty, and that industrialization certainly did not worsen and may have actually improved the conditions for the majority of the populace.41.A）admitted B）believed C）claimed D）predicted42.A）plain B）average C）mean D）normal43.A）momentary B）prompt C）instant D）immediate44.A）bulk B）host C）gross D）magnitude45.A）On B）With C）For D）By46.A）broadly B）thoroughly C）generally D）completely47.A）however B）meanwhile C）therefore D）moreover48.A）at B）in C）about D）for49.A）manifested B）approved C）shown D）speculated50.A）noted B）impressed C）labeled D）markedPart III Reading ComprehensionDirections:Each of the passages below is followed by some questions. For each question there are four answers marked A）,B）,C） and D）. Read the passages carefully and choose the best answer to each of the questions. Then mark your answer on the ANSWER SHEET I by blackening the corresponding letter in the brackets. （40 points）Passage 1Few creations of big technology capture the imagination like giant dams. Perhaps it is humankind's long suffering at the mercy of flood and drought that makes the ideal of forcing the waters to do our bidding so fascination. But to be fascinatedis also, sometimes, to be blind. Several giant dam projects threaten to do more harm than good.The lesson from dams is that big is not always beautiful. It doesn't help that building a big, powerful dam has become a symbol of achievement for nations and people striving to assert themselves. Egypt's leadership in the Arab world was cemented by the Aswan High Dam. Turkey's bid for First World status includes the giant Ataturk Dam.But big dams tend not to work as intended. The Aswan Dam, for example stopped the Nile flooding but deprived Egypt of the fertile silt that floods left - all in return for a giant reservoir of disease which is now so full of silt that it barely generates electricity.And yet, the myth of controlling the waters persists. This week, in the heart of civilized Europe, Slovaks and Hungarians stopped just short of sending in the troops in their contention over a dam on the Danube. The huge complex will probably have all the usual problems of big dams. But Slovakia is bidding for independence from the Czechs, and now needs a dam to prove itself.Meanwhile, in India, the World Bank has given the go ahead to the even more wrong headed Narmada Dam. And the bank has done this even though its advisors say the dam will cause hardship for the powerless and environmental destruction. The benefits are for the powerful, but they are far from guaranteed.Proper, scientific study of the impacts of dams and of the cost and benefits of controlling water can help to resolve these conflicts. Hydroelectric power and flood control and irrigation are possible without building monster dams. But when you are dealing with myths, it is hard to be either proper, or scientific. It is time that the world learned the lessons of Aswan. You don't need a dam to be saved.51.The third sentence of paragraph 1 implies that _____ .A）people would be happy if they shut their eyes to realityB）the blind could be happier than the sightedC） over excited people tend to neglect vital things.D）fascination makes people lose their eyesight52.In paragraph 5,"the powerless"probably refers to _____ .A）areas short of electricityB）dams without power stationsC）poor counrtries around IndiaD）common people in the Narmada Dam area53.What is the myth concerning giant dams?A）They bring in more fertile soil.B）They help defend the country.C）They strengthen international ties.D）They have univeral control of the waters.54.What the author tries to suggest may best be interpreted as _____ .A）"It's no use crying over spilt milk"B）"More haste, less speed"C）"Look before you leap"D）"He who laughs last laughs best"Passage 2Well, no gain without pain, they say. But what about pain without gain? Everywhere you go in America, you hear tales of corporate revival. What is harder to establish is whether the productivity revolution that businessmen assume they are presiding over is for real.The official statistics are mildly discouraging. They show that, if you lump manufacturing and services together, productivity has grown on average by 1.2% since 1987. That is somewhat faster than the average during the previous decade. And since 1991, productivity has increased by about 2% a year, which is more than twice the 1978 87 average. The trouble is that part of the recent acceleration is due to theusual rebound that occurs at this point in a business cycle, and so is not conclusive evidence of a revival in the underlying trend. There is, as Robert Rubin, the treasury secretary, says, a"disjunction"between the mass of business anecdote that points to a leap in productivity and the picture reflected by the statistics.Some of this can be easily explanied. New ways of organizing the workplace all that re engineering and downsizing - are only one contribution to the overalll productivity of an economy, which is driven by many other factors such as joint investment in equipment and machinery, new technology, and investment in education and training. Moreover, most of the changes that companies make are intended to keep them profitable, and this need not always mean increasing productivity:switching to new markets or improving quality can matter just as much.Two other explanations are more speculative. First, some of the business restructuring of recent years may have been ineptly done. Second, even if it was well done, it may have spread much less widely than people suppose.Leonard Schlesinger, a Harvard academic and former chief executive of Au Bong Pain, a rapidly growing chain of bakery cafes, says that much"re engineering"has been crude. In many cases, he believes, the loss of revenue has been greater than the reductions in cost. His colleague, Michael Beer, says that far too many companies have applied re engineering in a mechanistic fashion, chopping out costs without giving sufficent thought to long term profitability. BBDO's Al Rosenshine is blunter. He dismisses a lot of the work of re engineering consultants as mere rubbish -"the worst sort of ambulance cashing."55.According to the author, the American economic situation is _____ .A）not as good as it seemsB）at its turning pointC）much better than it seemsD）near to complete recovery56.The official statistics on productivity growth _____ .A）exclude the usual rebound in a business cycleB）fall short of businessmen's anticipationC）meet the expectation of business peopleD）fail to reflect the true state of economy57.The author raises the question"what about pain without gain?"because _____ .A）he questions the truth of"no gain without pain"B）he does not think the productivity revolution worksC）he wonders if the official statistics are misleadingD）he has conclusive evidence for the revival of businesses58.Which of the following statements is NOT mentioned in the passage?A）Radical reforms are essential for the increase of productivity.B）New ways of organizing workplaces may help to increase productivity.C）The reduction of costs is not a sure way to gain long term profitability.D）The consultants are a bunch of good for nothigns.Passage 3Science has long had an uneasy relationship with other aspects of culture. Think of Gallileo's 17th century trial for his rebelling belief before the Catholic Church or poet William Blake's harsh remarks against the mechanistic worldview of Isaac Newton. The schism between sceience and the humanities has, if anything, deepened in this century.Until recently, the seientific community was so powerful that it could affort to ignore its critics - but no longer. As funding for science has declined, scientists have attacked"antiscience"in several books, notably Higher Superstition, by Paul R.Gross, a biologist at the University of Verginia, and Norman Levitt, amathematician at Rutgers University; and The Demon Haunted World, by Car Sagan of Cornell University.Defenders of science have also voiced their concerns at meetings such as"The Flight from Science and Reason,"held in New York City in 1995, and"Science in theAge of （Mis）information,"which assembled last June near Buffalo.Antiscience clearly means different things to different people. Gross and Levitt find fault primarily with sociologists, philosophers and other academics who have questioned science's objectivity. Sagan is more concerned with those who believe in ghosts, creationism and other phenomena that contradict the scientific worldview.A survey of news stories in 1996 reveals that the antiscience tag has been attached to many other groups as well, from authorities who advocated the elimination of the last remaining stocks of smallpox virus to Republicans who advocated decreased funding for basic research.Few would dispute that the term applies to the Unabomber, those manifesto, published in 1995, scorns science and longs for return to a pretechnological utopia. But surely that does not mean environmentalists concerned about uncontrolled industrial growth are antiscience, as an essay in US News & World Report last May seemed to suggest.The environmentalists, inevitably, respond to such critics. The true enemies of science, argues Paul Ehrlich of Stanford University, a pioneer of environmental studies, are those who question the evidence supporting global warming, the depletion of the ozone layer and other consequences of industrial growth.Indeed, some observers fear that the antiscience epithet is in danger of becoming meaningless."The term 'antiscience' can lump together too many, quite different things,"notes Harvard University philosopher Gerald Holton in his 1993 work Science and Anti Science."They have in common only one thing that they tend to annoy or threaten those who regard themselves as more enlightened."59.The word"schism"（Line 4, Paragraph 1） in the context probably means _____ .A）confrontation B）dissatisfactionC）separation D）contempt60.Paragraphs 2 and 3 are written to _____ .A）discuss the cause of the decline of science's powerB）show the author's symphathy with scientistsC）explain the way in which science developsD）exemplify the division of science and the humanities61.Which of the following is true according to the passage?A）Environmentalists were blamed for antiscience in an essay.B）Politicans are not subject to the labeling of antiscience.C）The"more enlightened"tend to tag others as antiscienceD）Tagging environmentalists as"antiscience"is justifiable62.The author's attitude toward the issue of"science vs. antiscience"is _____ .A）impartial B）subjectiveC）biased D）puzzlingPassage 4Emerging from the 1980 census is the picture of a nation developing more and more regional competition, as population growth in the Northeast and Midwest reaches a near standstill.This development - and its strong implications for US politics and economy in years ahead - has enthroned the South as America's most densely populated region for the first time in the history of the nation's head counting.Altogether, the US population rose in the 1970s by 23.2 million people - numerically the third largest growth ever recorded in a single decade. Even so, that gain adds up to only 11.4 percent, lowest in American annual records except for the Depression years.Americans have been migrating south and west in larger number since World War II, and the pattern still prevails.Three sun belt states - Florida, Texas and California - together had nearly 10 million more people in 1980 than a decade earlier. Among large cities, San Diego moved from 14th to 8th and San Antonio from 15th to 10th - with Cleveland and Washington.DC,dropping out of the top 10.Not all that shift can be attributed to the movement out of the snow belt, census officials say, Nonstop waves of immigrants played a role, too - and so did bigger crops of babies as yesterday's"baby boom"generation reached its child bearing years.Moreover, demographers see the continuing shift south and west as joined by a related but newer phenomenon: More and more, Americans apparently are looking not just for places with more jobs but with fewer people, too. Some instances-●Regionally, the Rocky Mountain states reported the most rapid growth rate -37.1 percent since 1970 in a vast area with only 5 percent of the US population.●Among states, Nevada and Arizona grew fastest of all: 63.5 and 53.1 percent respectively. Except fro Florida and Texas, the top 10 in rate of growth is composed of Western states with 7.5 million people - about 9 per square mile.The flight from overcrowdedness affects the migration from snow belt to morebearable climates.Nowhere do 1980 census statistics dramatize more the American search for spacious living than in the Far West. There, California added 3.7 million to its population in the 1970s, more than any other state.In that decade, however, large numbers also migrated from California, mostly to other parts of the West. Often they chose - and still are choosing - somewhat colder climates such as Oregon, Idaho and Alaska in order to escape smog, crime and other plagues of urbanization in the Golden State.As a result, California's growth rate dropped during the 1970s, to 18.5 percent - little more than two thirds the 1960s growth figure and considerably below that of other Western states.63.Discerned from the perplexing picture of population growth the 1980 census provided, America in 1970s _____ .A）enjoyed the lowest net growth of population in historyB）witnessed a southwestern shift of populationC）underwent an unparalleled period of population growthD）brought to a standstill its pattern of migration since World dWar II64.The census distinguished itself from previous studies on population movement in that _____ .A）it stresses the climatic influence on population distributionB）it highlights the contribution of continuous waves of immigrantsC）it reveals the Americans' new persuit of spacious livingD）it elaborates the delayed effects of yesterday's"baby boom"65.We can see from the available statistics that _____ .A）California was once the most thinly populated area in the whole USB）the top 10 states in growth rate of population were all located in the WestC）cities with better climates benefited unanimously from migrationD）Arizona ranked second of all states in its growth rate of population66.The word"demographers"（Line 1, Paragraph 8） most probably means _____ .A）people infavor of the trend of democracyB）advocates of migration between statesC）scientists engaged in the studey of populationD）conservatives clinging to old patterns of lifePassage 5Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates.That the plates are moving is not beyond dispute. Africa and South America, forexample, are moving away from eath other as new material is injected into the sea floor between them. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined. The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readily be translated into motion with respect to the earth's interior. It is not possible to determine whether both continents are moving in opposite direcitons or whether one continent is stationary and the other is drifting away from it. Hot spots,anchored in the deeper layers of the earth, provide the measuring instruments needed to resolve the quesiton. From an analysis of the hot spot popultion it appears that the African plate is stationary and that it has not moved during the past 30 million years.The significance of hot spots is not confined to their role as a frame of reference. It now appears that they also have an important influence on the geophysical processes that propel the plates across the globe. When a continental plate come to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops seed fissures（cracks）; in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean. Thus just as earlier theories have explanied the mobility of the continents, so hot spots may explain their mutability（inconstance）.67.The author believes that _____ .A）the motion of the plates corresponds to that of the earth's interiorB）the geological theory about drifting plates has been proved to be trueC）the hot spots and the plates move slowly in opposite directionsD）the movement of hot spots proves the continents are moving apart68.That Africa and South America were once joined can be deduced from the fact that _____ .A）the two continents are still moving in opposite direcitonsB）they have been found to share certain geological featuresC）the African plates has been stable for 30 million yearsD）over 100 hot spots are scattered all around the globe69.The hot spot theory may prove useful in explaining _____ .A）the structure of the African platesB）the revival of dead volcanoesC）the mobility of the continentsD）the formation of new oceans70.The passage is mainly about _____ .A）the features of volcanic activitiesB）the importance of the theory about drifting platesC）the significance of hot spots in geophysical studiesD）the process of the formation of volcanoesPart IV English Chinese TranslationDirections:Read the following passage carefully and then translate the underlined sentences into Chinese. Your translation must be written clearly on the ANSWER SHEET II. （15 points）.They were, by far, the largest and most distant objects that scientists had ever decteded: a strip of enourmous cosmic clouds some 15 billion light years from earth. 71） But even more important, it was the farthest that scientists had been able to look into the past, for what they were seeing were the patterns and structures that existed 15 billion years ago. That was just about the moment that the universe was born. What the researchers found was at once both amazing and expected; the US National Aeronautics and Space Administratin's Cosmic Background Explorer satellite -Cobe-had disvocered landmark evidence that the universe did in fact begin with the primeval explosion that has become known as the Big Bang（the theory that the universe originated in an explosion from a single mass of energy）.72） The existence of the giant clouds was virtually required for the Big Bang, first put forward in the 1920s, to maintain its reign as the dominant explanation of the cosmos. According the the theory, the universe burst into being as a。
先进过程控制参考书目
Control ReferencesRecent Review ArticlesBequette, B.W. “Practical Approaches to Nonlinear Control: A Review of Process Applications,”in Nonlinear Model-based Process Control, NATO ASI Series, Ser. E, Vol. 353, pp. 3-32, R.Berber and C. Kravaris (eds.), Kluwer, Dordrecht (1998).Bequette, B.W., “Nonlinear Control of Chemical Processes: A Review,” Ind. Eng. Chem. Res. 30, 1391-1413 (1991).Garcia, C.E., D.M. Prett and M. Morari, “Model Predictive Control: Theory and Practice-A Survey,” Automatica, 25, 335-348 (1989).Henson, M.A. and D.E. Seborg, “Critique of Exact Linearization Strategies for Process Control,”J. Process Control, 1(3), 122-139 (1991).Kravaris, C. and J.C. Kantor, “Geometric Methods for Nonlinear Process Control. I.Background,” Ind. Eng. Chem. Res., 29, 2295-2310 (1990a)Kravaris, C. and J.C. Kantor, “Geometric Methods for Nonlinear Process Control. II. Controller Synthesis,” Ind. Eng. Chem. Res., 29, 2310-2324 (1990b)McLellan, P.J., T.J. Harris and D.W. Bacon, “Error Trajectory Descriptions of Nonlinear Controller Designs,” Chem. Eng. Sci., 45, 3017-3034 (1990).Morari, M., “Robust Process Control,” Chem. Eng. Res. Des., 65, 462-479 (1987). Rawlings, J.B., E.S. Meadows and K.R. Muske, “Nonlinear Model Predictive Control: A Tutorial and Survey,” Preprints ADCHEM ‘94, IFAC Symposium on the Advanced Control ofChemical Processes, Kyoto, Japan, May 25-27, 203-214 (1994).Seborg, D.E., T.F. Edgar and S.L. Shah, “Adaptive Control Strategies for Process Control: A Survey,” AIChE J., 32, 881-913 (1986)."Classic" Review ArticlesFoss, A.S., “Critique of Chemical Process Control Theory,” AIChE J., 19, 209-214 (1973). Lee, W. and V.W. Weekman, “Advanced Control Practice in the Chemical Process Industry: A View from Industry,” AIChE J., 22, 27-38 (1976).Morari, M., “Flexibility and Resiliency of Process Systems,” Comp. Chem. Engng., 7, 423-437 (1983).Ray, W.H., “Multivariable Process Control - A Survey,” Comp. Chem. Engng., 7, 367 (1983).Basic Process ControlBequette, B.W. An Introduction to Model-Based Control, Prentice Hall, Upper Saddle River, NJ (to31 August 1999 - B.W. BequetteCoughanowr, D.R. Process Systems Analysis and Control, 2nd ed., McGraw-Hill, New York (1991).Luyben, W.L., Process Modeling Simulation and Control for Chemical Engineers, 2nd ed., McGraw-Hill, New York (1990).Luyben, W.L. and M.L. Luyben, Essentials of Process Control, McGraw Hill (1997).Marlin, T.E., Process Control: Designing Processes and Control Systems for Dynamic Performance, McGraw Hill, New York (1995).Ogunnaike, B.A. and W.H. Ray, Process Dynamics, Modeling and Control, Oxford, New York (1994).Riggs, J.B., Chemical Process Control, Ferret Publishing, Lubbock, TX (1999).Seborg, D.E., T.F. Edgar and D.A. Mellichamp, Process Dynamics and Control, Wiley, New York (1989).Smith, C.A. and A.B. Corripio, Principles and Practice of Automatic Process Control, 2nd ed., Wiley, New York (1997).Stephanopoulos, G., Chemical Process Control, Prentice Hall, Englewood Cliffs (1984).Graduate Process ControlLevine, W.S. (ed.) The Control Handbook, CRC Press (1996).Morari, M. and E. Zafiriou, Robust Process Control, Prentice Hall, Englewood Cliffs (1989).Newell, R.B. and P.L. Lee, Applied Process Control - A Case Study, Prentice Hall, Englewood Cliffs (1989).Prett., D. and C. Garcia, Fundamental Process Control, Butterworths, Boston (1988).Ray, W.H., Advanced Process Control, Butterworths, Boston (1989). This is a paperback reprint of the original version published by McGraw-Hill in 1981.Skogestad, S. and I. Postlethwaite Multivariable Feedback Control. Analysis and Design, Wiley, New York (1996).Specialty Process ControlBuckley, P.S., W.L. Luyben and J.P. Shunta, Design of Distillation Control Systems, ISA, Research Triangle Park (1985).Henson, M.A. and D.E. Seborg (eds.), Nonlinear Process Control, Prentice Hall, Upper Saddle River, NJ (1997).Liptak, B.G. and K.Venczel (eds.) Instrument Engineers Handbook, Process Control Volume, Chilton Book Company, Radnor, PA (1985).Luyben, W.L., B.D Tyreus and M.L. Luyben, Plantwide Process Control, McGraw Hill (1999).Schork, F.J., Deshpande, P.B. and K.W. Leffew, Control of Polymerization Reactors, Marcel Dekker, New York (1993).Shinskey, F.G. Distillation Control, McGraw Hill, New York (1977).Shunta, J.P. Achieving World Class Manufacturing Through Process Control, Prentice Hall, Upper Saddle River, NJ (1995).Nonlinear Systems and ControlIsidori, A. Nonlinear Control Systems, 2nd ed., Springer-Verlag, New York (1989).Khalil, K. Nonlinear Systems, Macmillan, New York (1992).Mohler, R.R., Nonlinear Systems. Volume 1. Dynamics and Control, Prentice Hall, Englewood Cliffs (1991).Mohler, R.R., Nonlinear Systems. Volume 2. Applications to Bilinear Control, Prentice Hall, Englewood Cliffs (1991).Slotine, J.-J. E. and W. Li, Applied Nonlinear Control, Prentice Hall, Englewood Cliffs (1991).Adaptive, Digital and Predictive ControlAstrom, K.J. and B. Wittenmark, Computer Controlled Systems. Theory and Design, Prentice Hall, Englewood Cliffs (1984).Astrom, K.J. and B. Wittenmark, Adaptive Control, Addison Wesley, Reading, MA (1989). Bitmead, R.R., M. Gevers and V. Wertz, Adaptive Optimal Control - The Thinking Man's GPC, Prentice Hall, Englewood Cliffs (1990).Goodwin, G.C. and K.S. Sin, Adaptive Filtering Prediction and Control, Prentice Hall, Englewood Cliffs (1985).Roffel, B., P.J. Vermeer and P.A. Chin, Simulation and Implementation of Self-Tuning Controllers, Prentice Hall, Englewood Cliffs (1989).Soeterboek, R. Predictive Control. A Unified Approach, Prentice Hall, New York (1992).Chemical Process Control ConferencesArkun, Y. and W.H. Ray, Chemical Process Control - CPC IV, Elsevier, Amsterdam (1991). Edgar, T.F. and D.E. Seborg (eds.), Chemical Process Control II, Engineering Foundation, New York (1982).Foss, A.S. and M.M. Denn (eds.), Chemical Process Control, AIChE Symp. Ser. No. 159, Vol. 72 (1976).Kantor, J.C., C.E. Garcia and B. Carnahan, Chemical Process Control - CPC V, AIChE Symp. Ser.No. 316, Vol. 93 (1997).McAvoy, T.J., Y. Arkun and E. Zafiriou, Model Based Process Control, Pergamon Press, New York (1989).Morari, M. and T.J. McAvoy (eds.), Chemical Process Control - CPC III, Elsevier, Amsterdam (1986).Prett, D.M., C.E. Garcia and B.L. Ramaker, The Second Shell Process Control Workshop, Butterworths, Boston (1990).Prett, D.M. and M. Morari (eds.), Shell Process Control Workshop, Butterworths, Boston (1986).Linear and Optimal Control and EstimationChen, C.T. Linear System Theory and Design, Holt Rinehart & Winston, New York (1984).Gelb, A. (ed.) Applied Optimal Estimation, MIT Press, Cambridge, MA (1974).Kailath, T. Linear Systems, Prentice Hall, Englewood Cliffs (1980).Kirk, D.E. Optimal Control Theory, Prentice Hall, Englewood Cliffs (1970).Ljung, L. System Identification: Theory for the User, Prentice Hall , Upper Saddle River, NJ (1987).Stengel, R.F. Optimal Control and Estimation, Dover, NY (1994). This is a paperback reprint of the original version published by McGraw-Hill in 1986.Modeling, Simulation, Design and OptimizationAris, R. Mathematical Modeling Techniques, Pitman, San Francisco (1978).Bequette, B.W. Process Dynamics. Modeling, Analysis and Simulation, Prentice Hall, Upper Saddle River, NJ (1998).Biegler, L.T., I.E. Grossmann and A.W. Westerberg, Systematic Methods of Chemical Process Design, Prentice Hall, Upper Saddle River, NJ (1997).Close, C.M. and D.K. Frederick Modeling and Analysis of Dynamic Systems, 2nd ed., Houghton Mifflin, Boston (1993).Davis, M.E. Numerical Methods and Modeling for Chemical Engineers, Wiley, New York (1984). Denn, M.M. Process Modeling, Longman, New York (1986).Edgar, T.F. and D.M. Himmelblau, Optimization of Chemical Processes, McGraw-Hill, New York (1988).Finlayson, B.A. Nonlinear Analysis in Chemical Engineering, McGraw-Hill, New York (1980).Friedly, J.C. Dynamic Behavior of Processes, Prentice Hall, Englewood Cliffs (1972).Holland, C.D. Fundamentals and Modeling of Separation Processes, Prentice Hall, Englewood Cliffs (1975).Holland, C.D. and A.I. Liapis, Computer Methods for Solving Dynamic Separation Problems, McGraw-Hill (1983).Jenson, V.G. and G.V. Jeffreys Mathematical Methods in Chemical Engineering, Academic Press, New York (1977).Ramirez, W.F. Computational Methods for Process Simulation, Butterworths, Boston (1989).Riggs, J.B. An Introduction to Numerical Methods for Chemical Engineers, 2nd ed., Texas Tech University Press, Lubbock (1994).Seider, W.D., J.D. Seader and D.R. Lewin, Process Design Principles, Wiley (1999).Walas, S.M. Modeling with Differential Equations in Chemical Engineering, Butterworths (1989).Nonlinear Dynamics, Stability and Bifurcation TheoryAbraham, R.H. and C.D. Shaw Dynamics - The Geometry of Behavior. Part 1.Periodic Behavior (1984), Part 2. Chaotic Behavior (1984), Part 3. Global Behavior (1985), Part 4. Bifurcation Behavior (1988), Aerial Press, Santa Cruz.Arnold, V.I., Ordinary Differential Equations, MIT Press, Cambridge (1973).Boyce, W.E. and R.C. DiPrima, Elementary Differential Equations and Boundary Value Problems, 5th ed., Wiley, New York (1992).Golubitsky, M. and D.G. Schaeffer, Singularities and Groups in Bifurcation Theory, Springer-Verlag, New York (1985).Guckenheimer, J. and P. Holmes, Nonlinear Oscillations, Dynamical Systems, and Bifurcations of Vector Fields, Springer-Verlag, New York (1983).Hale J.K. and H. Kocak, Dynamics and Bifurcations, Springer-Verlag, New York (1991).Jackson, E.A. Perspectives of Nonlinear Dynamics, Volumes 1 and 2, Cambridge University Press, Cambridge (1991).Marek, M. and I. Schreiber Chaotic Behaviour of Deterministic Dissipative Systems, Cambridge University Press, Cambridge (1991).Moon, F.C. Chaotic and Fractal Dynamics, Wiley, New York (1992).Scheinerman, E.A. Invitation to Dynamical Systems, Prentice Hall, Upper Saddle River, NJ (1996). Strogatz, S.H. Nonlinear Dynamics and Chaos, Addison Wesley, Reading, MA (1994).Thompson, J.M.T. and H.B. Stewart, Nonlinear Dynamics and Chaos, Wiley, New York (1986). Tufillaro, N.B., T. Abbott and J. Reilly An Experimental Approach to Nonlinear Dynamics and Chaos, Addison-Wesley, Redwood City (1992).MATLAB-Based Control BooksKuo, B.C. and D.C. Hanselman MATLAB Tools for Control System Analysis and Design, Prentice Hall, Englewood Cliffs (1994).Ogata, K. Designing Linear Control Systems with MATLAB, Prentice Hall, Englewood Cliffs (1994).Journals - ControlAIChE JournalAmerican Control Conference (ACC) Proceedings (yearly)ASME Journal of Dynamic Systems, Measurement and ControlAutomatica (IFAC)Canadian Journal of Chemical EngineeringChemical Engineering CommunicationsChemical Engineering Research and DesignChemical Engineering ScienceComputers and Chemical EngineeringConference on Decision and Control (CDC) Proceedings (yearly)Control Engineering Practice (IFAC)Control Systems Magazine (IEEE)Industrial and Engineering Chemistry Research (I&EC Research)IEEE Transactions on Automatic ControlIEEE Transactions on Control System TechnologyInternational Federation of Automatic Control (IFAC) ProceedingsInternational Journal of ControlInternational Journal of Systems SciencesJournal of Process ControlProceedings of the IEESIAM Journal on Control and OptimizationThe following conference proceedings and magazines often provide interesting applied process control problems and solutions.Advances in Instrumentation and Control (ISA Annual Conference)Chemical Engineering Magazine (McGraw Hill)Chemical Engineering ProgressControl Systems Magazine (IEEE)Hydrocarbon Processing (petroleum refining and bulk organic chemicals)Instrumentation Technology (InTech, an instrumentation industry magazine)ISA (Instrument Society of America) TransactionsTAPPI Journal (pulp and paper industry)。
反洗钱英文教材
Key words:
Underlying crimes:基础/上游犯罪 Predicate offences: 基础/上游犯罪 Generate:产生 Proceeds:收益 Individual:个人 Behavioral pattern:行为方式 Conversion:转换 Transfer:转移 Concealment:隐藏 Disguise:伪装 Acquisition:获得 Possession: 占有
Use of legitimate business
Cash smuggling
Use of anonymous（匿名的）assets
1.3 The Definition of ML
ML is a process to legalize dirty money generated from crimes. Elements： —scope of underlying crimes/predicate offences （基础犯罪） —subject 主体（individuals or organizations） —mens rea（犯罪意图）（intentional故意 or negligent过失） —Behavioral patterns（行为方式）
These
is no everlasting banquet in the world. The friendship, however, will live forever. When I was doing Ph.D. research in Rotterdam, I collected Euro coins of 12 countries as a present for my son. I laundered the dirty coins to make them look nice. My laundering money, however, has nothing to do with my research topic ‗money laundering.‘
1998年英语考研阅读练习题
一、词汇emerge census regional competition implication politics economy densely decade gain annual migrate pattern prevail shift beltofficial immigrant role crop demographer apparently rapid composeflight affect statistics dramatize spacious crime plague considerably二、长难句1.This development -- and its strong implications for US politics and economy in years ahead -- has enthroned the South as America's most densely populated region for the first time in the history of the nation's head counting.2.As a result, California's growth rate dropped during the 1970s, to 18.5 percent -- little more than two thirds the 1960s' growth figure and considerably below that of other Western states.一、词汇scatter globe region isolated geologist boundary drift surface contrary interior trail dispute inject complementary feature span reminder detail respect interior opposite stationary instrument resolve analysis significance frame reference influence process propel domecrack entirely initiate formation explain mobility二、长难句1.Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate.2.The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readily be translated into motion with respect to the earth's interior.3.As the dome grows, it develops seed fissures (cracks); in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean.1998年考研英语真题阅读translation一、词汇distant object detect strip enormous pattern exist amaze evidence explosion originate single mass existence giant virtually maintain reign dominant explanation dense pure emit radiation condense compress gravity galaxy triumph refinement inflationary expand propel sort plausible consequence elementary convince二、长难句1.According the theory, the universe burst into being as a submicroscopic, unimaginable dense knot of pure energy that flew outward in all directions, emitting radiation as it went, condensing into particles and then into atoms of gas.2.If the small hot spots look as expected, that will be a triumph for yet another scientific idea, a refinement of the Big Bang called the inflationary universe theory.一、词汇step slip stove disaster compensate threaten respond label anticipate inch cape caution appropriate federal regulation protect customer court tide claim defendant involve prevent lawyer academic recommendation substantial weightissue guideline warn moderate二、长难句1.While warnings are often appropriate and necessary -- the dangers of drug interactions, for example -- and many are required by state or federal regulations, it isn't clear that they actually protect the manufacturers and sellers from liability if a customer is injured.2.As personal injury claims continue as before, some courts are beginning to side with defendants, especially in cases where a warning label probably wouldn't have changed anything.3.If the moderate end of the legal community has its way, the information on products might actually be provided for the benefit of customers and not as protection against legal liability.一、词汇revolve tap fashion typically hesitate reliability pathway senior analyst risk transaction establish access private major shift commerce available strategy pull software push transmit target updated monitor proceed contempt culture notion specific request promotion distinction fade prospect inevitable resort pioneer mix interactivity hospitality security attract enterprise wonder plunge二、长难句1.Some companies are limiting the risk by conducting online transactions only with established business partners who are given access to the company's private intranet.2.In the past year, however, software companies have developed tools that allow companies to "push" information directly out to consumers, transmitting marketing messages directly to targeted customers.3.The examples of Virtual Vineyards, , and other pioneers show that a Web site selling the right kind of products with the right mix of interactivity, hospitality, and security will attract online customers.。
三电平逆变器SHEPWM技术的所有解问题
三电平逆变器SHEPWM技术的所有解问题叶满园;李宋;蔡鸿【摘要】Aiming at the problem that the selective harmonic elimination pulse-width modulation (SHEPWM) of a multi-level inverter has a high dependence on the initial values of switching angle in the solving process of nonlinear equations,double-angle trigonometric functions are used in this paper to convert the nonlinear equations of SHEPWM of three-level neutral point clamped(NPC)inverter into an algebraic polynomial mode,and all the solutions in full modulation region can be obtained by using the"Solve"function in MATLAB to process the polynomial model without the need to know the initial values of switching angle. The trajectories of switching angles and the corresponding total harmonic distortion(THD)of line voltage,which vary with the modulation ratio,are also given. Moreover,the distribu?tion characteristics of the solutions of switching angles are analyzed and compared,which provides a theoretical refer?ence for the selection of switching angles in practical engineering. Finally,the correctness and feasibility of using the"Solve"function to compute the switching angles is verified by simulations and experiments.%针对多电平逆变器特定谐波消除SHEPWM(selective harmonic elimination pulse-width modulation)求解非线性方程组对开关角度初值依赖性高的问题,采用三角函数倍角关系将三电平中点钳位NPC(neutral point clamped)逆变器SHEPWM非线性方程组转换为代数多项式的模式,并利用MATLAB中的Solve函数对多项式模型进行求解,在无需开关角初值的情况下得到了全调制比下的所有解.给出了开关角及线电压谐波失真THD(total harmonics distortion)随调制比变化的轨迹,分析和比较了开关角解的分布特点,为实际工程中开关角度的选取提供了理论依据.最后仿真和实验验证了利用Solve函数所求开关角度的正确性和可行性.【期刊名称】《电力系统及其自动化学报》【年(卷),期】2017(029)010【总页数】5页(P18-21,29)【关键词】三电平逆变器;代数多项式;消谐模型;开关角初值【作者】叶满园;李宋;蔡鸿【作者单位】华东交通大学电气与自动化工程学院,南昌 330013;华东交通大学电气与自动化工程学院,南昌 330013;华东交通大学电气与自动化工程学院,南昌330013【正文语种】中文【中图分类】TM46420世纪80年代日本学者Nabael提出了三电平中点钳位NPC（neutral point clamped）逆变器，该拓扑具有容量大、输出电压谐波小、能量可双向流动等优点，而被广泛应用于高压变频及机车牵引等领域。
1998年真题作文
1998年真题作文In the picture stands a hen ,who holds a notice with words on it –hen herself has attended to promise that her eggs which contain shells ,egg whites and yolks are round without angles and corners.The picture does reveal certain disturbing social phenomenon , that is ,people tend to overlook the fact that the so-called promise, flourishing through all walks of life ,is the essential responsibility ,and thus extravagant emphasis on it is an unnecessary move. The public attaches due attention to the false promise . The private businessmen ,striving to make profits ,utilize chemistry such as plasticizer ,clenbuterol(这个单词是某种剂，但现在怎么查也查不到了，老师将就着看看吧，找个单词代替了也行！) and its like added up to products to promote their goods and services in competition with other businessmen . By doing so , their activities pose a threat to public mental and physical well-being , thereby cause heart disease , hypertension and cardiovascular disease .According to the survey conducted by Chinese Academy of Social Science (CASS),63.93% of people certainly insist that failure to realize the severity of the false promise will inevitably decrease the success of transaction .It is imperative to come up with countermeasures .To begin with ,manufacturers guarantee to turn out the products of good quality ; secondly, commercial enterprise swear to provide genuine commodities and polite and enthusiastic services ; last but not least ,administration departments assure to perform their tasks effectively and fairly without taking any bribes.1999年真题作文As is shown ,the first graph-US Population Growth Over Time, exhibits that number of population was nearly 0 in America in 1800 and until （这里用不用加个in？）2000 it appeared to be 260 million ;the pre-to post-number had increased on average 20 million within 20 years .However ,the other graph suggests that the number of the American species extinction had increased ranging from 10 million to 70million since in (这个in要不要呢？)1600 until 1900. The two graph do reveal a certain disturbing phenomenon ,that is ,people tend to overlook the fact that a large number of population has posed a threat to the wildlife and even cause the extinction of species .The public attaches due attention to environmental problems .For one thing ,the pollutants like monoxide ,dioxide ,sulfur builds(老师，这是你春季班给的句型，但我不知道build为何有s，还是sulfur builds是一个词？)up in the atmosphere and cause the degradation of air quality ;for the other thing , the industrial sewage dumped into rivers and lakes and dwindling tropical jungles both are responsible for the death of wildlife .According to the survey conducted by Chinese Academy of Social Science (CASS),63.93% of people insistently suppose that failure to realize the importance of wildlife protection will inevitably decrease our standard of living .It is imperative that the government come up with countermeasures, including both to raise the public awareness of protecting animals and to make the comprehensive rules and regulations in regard to environment preservation .2000年真题作文As is shown, in 1900 a large number of fishes stayed in the ocean, where people standing on the boat are fishing .Still, in 1995 when the marine biomass has suffered a great loss with the commercial fishing vessels rapidly increasing .These pictures do reveal a certain disturbing social phenomenon ,that is , people tend to overlook the fact that aquatic species are in the presence of extinction .The public attaches dueattention to the limited ocean resource . Extravagant fishing poses a threat to the diversity of what is in the sea .Were the tendency to continue as it is ,our future generation would never bother to think of excuse for us .According to the survey conducted by Chinese Academy of Social Science (CASS),63.93% of people insistently suppose that failure to realize the severity of lack of species will inevitably decrease the possibility of human survival .It is imperative that senior departmental officials appeal the public to be made aware of environment preservation .In addition ,the government makes a comprehensive rules and regulations in regard to protect the environment .Only by the way can we have a brilliant future .（第二段太骨感了，老师给点新内容吧！！）。
1998年考研英语真题解析
1998年全国硕士研究生入学统一考试英语试题分析Section I Cloze Test一、文章总体分析本文在关于工业革命对英国人民生活的影响问题上提出了两种对立的观点。
第一段讲述了第一种观点，是大部分历史学家的看法，即工业革命的直接结果是给英国大多数人民带来了普遍的贫穷和苦难。
第二段讲述的是另一种人普遍持有的观点，即工业革命不但没有加重这种贫困，反而使绝大多数人的生活得到了改善。
二、试题具体解析1.[A] admitted承认[B] believed相信，认为[C] claimed声称[D] predicted预言[答案] A[解析] 本题考核的知识点是：上下文语义 + 动词词义辨析。
难度：0.54文章开篇指出：Until recently most historians spoke very critically of the Industrial Revolution，接着第二句又谈到，in the long run industrialization greatly raised the standard of living。
显然，后一句是对前一句的让步。
第三句又以But开头，暗示与第二句有转折关系。
因此可以肯定，这里要表达的意思是历史学家不得不承认既成事实。
四个选项中，首先排除predicted，因为句子时态是过去时，表明"提高人们的生活水平"已经是事实，不存在"预测"了；其次believed和claimed都是表达人们肯定态度的词语，它们和首句所表达的含义自相矛盾；因此只有admitted可以承接上下文，表示一种让步，意为"直到最近，大多数的历史学家对工业革命仍持强烈的批评态度。
尽管他们承认从长远角度来看，工业革命已大大地提高了一般人的生活水平。
"2.[A] plain（man）衣着朴素或相貌平平的人[B] average（man）平民，普通人[C] mean平均的，吝啬的，卑鄙的[D] normal（man）正常人[答案] B[解析] 本题考核的知识点是：形容词词义辨析。
1998年考研英语试题及参考答案（3）
Passage 4When a Scottish research team startled the world by revealing 3 months ago that it had cloned an adult sheep, President Clinton moved swiftly. Declaring that he was opposed to using this unusual animal husbandry technique to clone humans , he ordered that federal funds not be used for such an experiment- although no one had proposed to do so--and asked an independent panel of experts chaired by Prinoeton President Harold Shapiro to report back to the White House in 90 days with recommendations for a na- tional policy on human cloning. That group--the National Bioethics Advisory Commission ( NBAC)-has been working feverishly to put its wisdom on paper, and at a meeting on 17 May, members agreed on anear-final draft of their recommendations.NBAC will ask that Clinton ' s 90-day ban on federal funds for human cloning be extended in- definitely , and possibly that it be made law. But NBAC members are planning to word the recom- mendation narrowly to avoid new restrictions on research that involves the cloning of human DNAor cells-routine in molecular biology. The panel has not yet reached agreement on a crucial ques- tion, however, whether to recommend legislation that would make it a crime for private funding to be used for human cloning.In a draft preface to the recommendations, discussed at the 17 May meeting, Shapiro sug- gested that the panel had found a broad consensus that it would be "morally unacceptable to at- tempt to create a human child by adult nuclear cloning. " Shapiro explained during the meeting that the moral doubt stems mainly from fears about the risk to the health of the child. The panel then informally accepted several general conclusions , although some details have not been settled.NBAC plans to call for a continued ban on federal government funding for any attempt to clone body cell nuclei to create a child. Because current federal law already forbids the use of fed-eral funds to create embryos ( the earliest stage of human offspring before birth) for research or toknowingly endanger an embryo' s life, NBAC will remain silent on embryo research. NBAC members also indicated that they will appeal to privately funded researchers and clinics not to try to clone humans by body cell nuclear transfer. But they were divided on whether to go further by calling for a federal law that would impose a complete ban on human cloning. Shapiro and most members favored an appeal for such legislation , but in a phone interview, he said this is- sue was still "up in the air. "63. We can learn from the first paragraph that__[A]federal funds have been used in a project to clone humans[B] the White House responded strongly to the news of cloning[C]NBAC was authorized to control the misuse of cloning technique[D]the White House has got the panel's recommendations on cloning64. The panel agreed on all of the following except that__[A]the ban on federal funds for human cloning should be made a law[B]the cloning of human DNA is not to be put under more control[C]it is crimtnal to use private funding for human cloning[D]it would be against ethical values to clone a human being65 . NBAC will leave the issue of embryo research undiscussed because__[A]embryo research is just a current development of cloning[B]the health of the child is not the main concern of embryo research[C]an embryo' s life will not be endangered in embryo research[D]the issue is expLicitly stated and settled in the law66. It can be inferred from the last paragraph that__[A]some NBAC members hesitate to ban human cloning completely[B]a law banning human cloning is to be passed in no time[C] privately funded researchers will respond positively to NBAC' s appeal[D]the issue of human cloning will soon be settledPassage 5Science, in practice, depends far less on the experiments it prepares than on the preparedness of the minds of the men who watch the experiments. Sir Isaac Newton supposedly discovered gravity through the fall of an apple. Apples had been falling in many places for centuries and thousands of people had seen them fall. But Newton for years had been curious about the cause of the orbital motion of the moon and planets. What kept them in place? Why didn' t they fall out of the sky? The fact that the apple fell down toward the earth and not up into the tree answered the question he had been asking himself about those lalger fruits of the heavens, the moon and the planets.How many men would have considered the possibility of an apple falling up into the tree? Newton did because he was not trying to predict anything. He was just wondering.His mind was ready for the unpredictable. Unpredictabllity is part of the essential nature of research. If you don' t have unpredictable things, you don' t have research. Scienltists tend to forget this when writing their cut and dried reports for the technical journals, but history is filled with examples of it.In talking to some scienlists, particularly younger ones, you might gather the impression that they find the "scientific melhod"a substitute for imaginative thought . I've attended research conferences where a scientist has been asked what he thinks about the advisability of continuing acertain experiment. The scientist has frowned, looked at the graphs, and said "the data are still inconclusive." "We know that, " the men from the budget office have said, "but what do you think? Is it worthwhile going on? What do you think we might expect?" The scientist has beenshocked at having even been asked to speculate.What this amounts to, of course, is that the scientist has become the victim of his own writ- ings. He has put forward unquestioned claims so consistently that he not only believes them him- self, but has convinced industrial and business management that they are true. If experiments are planned and carried out according to plan as faithfully as the reports in the science journals indi- cate , then it is perfectly logical for management to expect research to produce results measurable in dollars and cents. It is entirely reasonable for auditors to believe that scientists who know ex- actly where they are going and how they will get there should not be distracted by the necessity of keeping one eye on the cash register while the other eye is on the microscope. Nor, if regularity and conformity to a standard pattern are as desirable to the scientist as the writing of his papers would appear to reflect , is management to be blamed for discriminating against the "odd balls a-mong researchers in favor of more conventional thinkers who "work well with the team. "67. The author wants to prove with the example of Isaac Newton that __[A] inquiring minds are more important than scientific experiments[B] science advances when fruitful researches are conducted[C] scientists seldom forget the essential nature of research[D] unpredictability weighs less than prediction in scientific research68 . The author asserts that sclentists __[A] shouldn't replace "scientific method" with imaginative thought[ B] shouldn't neglect to speculate on unpredictable things[ C] should write more concise reports for technical journals[D]should be confident about their research findings69. It seems that some young scientists__[A]have a keen interest in prediction[B]often speculate on the future[C] think highly of creative thinking[D]stick to "scientific method"70. The author implies that the results of scientific research__[A]may not be as profitable as they are expected[B]can be measured in dollars and cents[C] rely on conformity to a standard pattern[D]are mostly underestimated by managementPart IV: English-Chinese Translation71) While there are almost as many definitions of history as there are historians,modern practice most closely conforms to one that sees history as the attempt to recreate and explain the significant events of the past. Caught in the web of its own time and place, each generation ofhistorians determines anew what is significant for it in the past. In thls search the evidence found is always incomplete and scattered; it is also frequently partial or partisan. The irony of the histo- rian' s craft is that its practitioners always know that their efforts are but contributions to an un- ending process .72) Interest in historical methods has arisen less through external challenge to the validity of history as an intellectual discipline and more from internal quarrels among historians themselves.While history once revered its affinity to literature and philosophy, the emerging social sciences seemed to afford greater opportunities for asking new questtons and providing rewarding ap- proaches to an understanding of the past. Social science methodologies had to be adapted to a dis- cipline governed by the primacy of historical sources rather than the imperatives of the contempo- rary world. 73) During this transfer , traditional historical methods were augmented by additional methodologies designed to interpret the new forms of evidence in the historical study.Methodology is a term that remains inherently ambiguous in the historical profession. 74 ) There is no agreement whether methodology refers to the concepts peculiar to historical work in general or to the research techniques appropriate to the various branches of historical inquiry. His-torians, especially those so blinded by their research interests that they have been accused of "tun- nel method , " frequently fall victim to the "technicist fallacy. " Also common in the natural sci- ences , the technicist fallacy mistakenly identifies the discipline as a whole with certain parts of its technical implementation. 75 ) It applies equally to traditional historians who view history as only the external and intemal criticism of sources, and to social science historians who equate their ac- tivity with specific techniques.。
1998考研英语一阅读
1998考研英语一阅读Title: The Evolution of Technology and EducationThe year 1998 marked a significant turning point in the intersection of technology and education, particularly in the context of the Graduate Record Examination (GRE) for English. As the internet began to gain traction and computer-based testing emerged as a viable option, the landscape of education underwent a profound transformation. This shift not only altered the way students approached exam preparation but also reshaped the very nature of standardized testing.One of the most prominent changes brought about by technology was the introduction of computer-adaptive testing (CAT). Unlike traditional paper-based exams, CAT dynamically adjusts the difficulty of questions based on the test-taker's responses. This personalized approach revolutionized the testing experience, offering a more accurate assessment ofindividual skills and knowledge. Moreover, it enabledefficient use of time and resources by focusing on areas of strength and weakness in real-time.Furthermore, the advent of computer-based testing facilitated greater accessibility and flexibility for candidates. Gone were the constraints of fixed test dates and limited testing centers. With the ability to schedule exams at their convenience and choose from a wider range of locations, aspirants could now tailor their preparation to suit their individual circumstances. This democratization of access leveled the playing field, allowing students from diverse backgrounds to compete on equal footing.In addition to logistical advantages, technology also revolutionized the preparation process itself. Interactive study materials, online practice tests, and virtual tutoring became integral components of exam readiness. These resources not only enhanced engagement and motivation but also providedinstant feedback and performance tracking. As a result, students could identify areas for improvement moreeffectively and refine their study strategies accordingly.Moreover, the integration of multimedia elements enriched the learning experience and catered to different learning styles. Audiovisual presentations, interactive simulations, and gamified exercises offered immersive learning opportunities, making complex concepts more digestible and engaging. This multimedia approach not only fostered deeper understanding but also encouraged creativity and critical thinking skills essential for success in academia and beyond.Furthermore, the rise of online forums and communities fostered collaborative learning environments where students could share insights, strategies, and resources. This sense of camaraderie and collective support not only alleviated the sense of isolation often associated with exam preparation but also enriched the overall learning experience. By harnessingthe collective wisdom of peers and mentors, aspirants could tap into a wealth of knowledge and expertise, accelerating their progress and fostering a sense of community.However, alongside these transformative developments came new challenges and concerns. The digital divide widened as disparities in access to technology and internet connectivity persisted, disproportionately affecting marginalized communities. Moreover, the reliance on computer-based testing raised concerns about security, fairness, and the potential for cheating. Safeguarding the integrity of exams became a paramount concern, prompting institutions to implement stringent measures to combat malpractice and uphold the validity of results.In conclusion, the year 1998 marked a watershed moment in the evolution of technology and education, particularly in the realm of standardized testing for English proficiency. The advent of computer-based testing revolutionized thetesting experience, offering greater accessibility, personalization, and flexibility. Moreover, it transformed the preparation process itself, leveraging multimedia resources and collaborative platforms to enhance learning outcomes. However, these advancements also posed new challenges related to equity, security, and integrity, underscoring the need for continued innovation and vigilance in the pursuit of educational excellence.。
1998英语大作文
1998英语大作文In the late 1990s, the world witnessed a significant transformation in the field of education due to the rapid advancement of technology. This essay aims to explore the profound impact that technology had on education during that period, focusing on how it revolutionized learning methods, accessibility, and the overall educational experience.The Advent of the Internet:The 1998 era was marked by the widespread adoption of the internet, which dramatically changed the way students accessed information. The internet provided a vast repository of knowledge that was previously inaccessible to the average student. This led to a paradigm shift in research and learning, as students could now find information on any topic with just a few keystrokes.The Rise of Online Learning:With the internet came the rise of online learning platforms. These platforms allowed students to take courses and attend lectures from the comfort of their homes. This wasparticularly beneficial for those who could not attend traditional schools due to geographical or financial constraints. The convenience of online learning also meant that students could learn at their own pace, which catered to different learning styles.Digital Communication:The 1998 era saw the emergence of digital communication tools such as email and chat rooms. These tools facilitated communication between students and teachers, making it easier to ask questions, submit assignments, and receive feedback. This improved communication also fostered a sense of community among students, even if they were physically distant.Educational Software:Educational software became a staple in classrooms duringthis time. These programs were designed to enhance learning by providing interactive lessons, simulations, and games. They catered to various subjects, from mathematics and science to language learning and history, making education more engaging and effective.Challenges and Considerations:Despite the numerous benefits, the integration of technology in education also presented challenges. Issues such asdigital divide, where access to technology was unequal, emerged as a significant concern. Additionally, there was a need for teachers to adapt to new teaching methods and for institutions to update their infrastructure to support technological advancements.Conclusion:The 1998 era was a pivotal time in the history of education, as technology began to redefine the learning process. While there were challenges, the overall impact was positive, paving the way for the modern, technology-driven educational landscape we know today. The integration of technology intoeducation during this period set the stage for continuous innovation and improvement in how knowledge is imparted and acquired.。
1998考研英语阅读
1998考研英语阅读In the year 1998, the Graduate Record Examination (GRE) English reading section was a pivotal part of the test that aimed to assess the reading comprehension and criticalthinking skills of prospective graduate students. The reading materials covered a range of topics, from scientific research to social issues, and were designed to challenge the test-takers' ability to understand complex texts and derive meaning from them.One of the passages may have discussed the impact of technological advancements on society, highlighting the benefits and drawbacks of rapid technological change. Itcould have included examples of how technology has improved communication, access to information, and the efficiency of various industries, while also raising concerns about privacy, job displacement, and the digital divide.Another passage might have focused on environmental issues, such as climate change or deforestation, examiningthe causes and consequences of these problems. It would have provided data and expert opinions to support various viewpoints, encouraging test-takers to consider thecomplexity of environmental challenges and the need for sustainable solutions.The 1998 GRE English reading section also likely included literary excerpts, requiring test-takers to analyze theauthor's use of language, tone, and style. These excerpts could have been from classic works of literature or contemporary pieces, offering a glimpse into different cultures and historical periods.Finally, the section would have concluded with questions that tested the test-takers' ability to infer meaning, summarize information, and make logical connections between ideas presented in the texts. These questions were designed to push beyond mere recall, requiring a deeper level of understanding and critical analysis.Overall, the 1998 GRE English reading section was a comprehensive evaluation of a candidate's ability to engage with and interpret complex written material, a skill crucial for success in graduate-level academic work.。
飞机健康管理系统的验证与确认
飞机健康管理(Aircraft health management，AHM)系统的验证与确认（Verification and validation ，V&V）是一个复杂的技术难题，但是为了确保AHM 系统的稳定、可靠，这个过程不可或缺。
AHM 系统的V&V 需要从两个主要方面入手。
其一，AHM 系统的本身；其二，AHM 系统的实施。
AHM 系统需要按照AHM 的需求来进行搭建，例如，AHM 系统要在给定时间内作出具有特定置信度的响应。
AHM 系统的实现需要融合多种技术手段，包含数据分析处理、故障诊断与隔离、基于人工智能的状态评估与计划等。
这里主要研究AHM 系统V&V 的内部与外部的影响以及由这些影响带来的技术难题。
1 现存的软件系统的V&V1.1 航电设备的V&V商用飞机上的软件是由美国联邦航空局（Federal Aviation Administration，简称FAA）来认证的，依据文件为RTCA 公司的DO-178B。
文献[1]解释了RTCA 公司的DO-178B 文件。
文中描述了DO-178B 的意图以及合理性，同时讨论了DO-178B 与美国联邦法规之间的关系。
DO-178B 规定软件的验证过程应包含以下几个方面：a.软件开发过程的验证b.软件开发周期内的数据检验c.软件的功能验证d.基于需求的测试与分析e.稳定性测试f.结构包容性分析2004年7月8日，NASA 颁布了NASA-STD-8719.13b 来对软件系统进行验证。
2009年11月11日，对该文件进行了更新，发布了最新版的替代文件NPR 7150.2A。
这种V&V 方式与认证手段与其他领域的类似。
1.3 航天器故障保护的V&VNASA 机器航天器的故障保护（Fault protection ，简称FP）软件是一种特殊的健康管理系统。
该系统在两个方面超越了普通的健康管理系统，具有推理能力和自我修复的能力，不是简单的避免故障。
1998考研英语真题
1998考研英语真题In 1998, the English subject was included in the national postgraduate entrance examination (also known as the "考研" in Chinese) for the first time. This move not only raised the bar for postgraduate students but also became a landmark event in the history of the Chinese education system. In this article, we will explore the significance of the 1998 English subject inclusion and examine its implications.I. BackgroundBefore 1998, the postgraduate entrance examination in China mainly focused on subjects such as Chinese, math, and politics. The addition of the English subject marked a significant step towards embracing globalization and promoting international exchanges in education. It aimed to cultivate professionals with advanced English proficiency and a broader global perspective.II. Implications1. Academic AdvancementThe inclusion of the English subject in the postgraduate entrance examination prompted students to enhance their English language skills. It created an incentive for individuals to further their studies in English literature, linguistics, and other related fields. As a result, the overall academic level in these disciplines has been significantly uplifted.2. International OpportunitiesThrough testing candidates' ability to comprehend and express themselves in English, the examination provided a fair and impartial evaluation of students' language proficiency. This standardized evaluation enabled Chinese students to pursue further studies abroad, opening up doors to international universities and research institutions. The inclusion of English in the examination broadened students' horizons and connected them to a global academic community.3. Teaching ReformThe 1998 English subject inclusion also brought about reforms in English language teaching. It emphasized the importance of communicative competence, listening skills, and real-life language situations. This shift in teaching methods led to the adoption of more interactive and practical approaches, ultimately improving the overall English language education system in China.III. Challenges and Solutions1. Equality in ResourcesThe inclusion of English in the postgraduate entrance examination exposed the unequal distribution of educational resources across regions. Students from more developed areas, with better English language education, were at an advantage compared to their counterparts in less developed regions. To address this issue, the government has implemented policies to provide equal access to quality English education, bridging the gap between different regions.2. Curriculum AdaptationThe inclusion of the English subject required adjustments to the existing curriculum. English teachers had to adapt teaching materials and methods to meet the new requirements. Through professional development training and the sharing of best practices, teachers were able to align their teaching approaches with the examination's expectations.IV. ConclusionThe inclusion of the English subject in the 1998 postgraduate entrance examination marked a significant milestone in China's education system. It not only stimulated academic advancement, but also created international opportunities for students. Furthermore, it led to reforms in English language teaching, emphasizing practical skills and fostering communicative competence. While challenges such as resource inequality and curriculum adaptation emerged, the government has actively worked to ensure equal opportunities and support for all students.In conclusion, the 1998 English subject inclusion in the postgraduate entrance examination played a crucial role in shaping the education landscape in China. It has contributed to the development of a more internationally-oriented academic community, bringing Chinese students closer to global academic standards.。
1998declarationofsentimentsofthenational...
1998 Declaration of Sentiments ofThe National Organization for WomenOn this twelfth day of July, 1998, the delegates of the National Organization for Women gather in convention on the one hundred and fiftieth year of the women's rights movement.We bring passion, anger, hope, love and perseverance to create this vision for the future: ∙We envision a world where women's equality and women's empowerment to determine our own destinies is a reality;∙We envision a world where women have equal representation in all decision-making structures of our societies;∙We envision a world where social and economic justice exist, where all people have the food, housing, clothing, health care and education they need;∙We envision a world where there is recognition and respect for each person's intrinsic worth as well as the rich diversity of the various groups among us;∙We envision a world where non-violence is the established order;∙We envision a world where patriarchal culture and male dominance no longer oppress us or our earth;∙We envision a world where women and girls are heard, valued and respected.Our movement, encompassing many issues and many strategies, directs our love for humanity into action that spans the world and unites women.But our future requires us to know our past.One hundred fifty years ago the women's rights movement grew out of the fight to abolishslavery. Angered by their exclusion from leadership and public speaking at abolitionist conventions and inspired by the power of the Iroquois women, a small dedicated group of women and men built a movement. After its inception, the movement was fractured by race. Our history is full of struggle against common bonds of oppression and a painful reality of separation. Nevertheless, these activists created a political force that achieved revolutionary change. They won property rights for married women; opened the doors of higher education for women; and garnered suffrage in 1920.In 1923, on the seventy-fifth anniversary of the historic Seneca Falls convention, feminists led the demand for constitutional equality for women to win full justice under the law in order to end economic, educational, and political inequality.Our foremothers -- the first wave of feminists -- ran underground railroads, lobbied, marched, and picketed. They were jailed and force fed, lynched and raped. But they prevailed. They started with a handful of activists, and today, the feminist movement involves millions of people every day.Standing on their shoulders, we launched the National Organization for Women in 1966, the largest and strongest organization of feminists in the world today. A devoutly grassroots, action-oriented organization, we have sued, boycotted, picketed, lobbied, demonstrated, marched, and engaged in non-violent civil disobedience. We have won in the courts and in the legislatures; and we have negotiated with the largest corporations in the world, winning unparalleled rights for women.The National Organization for Women and our modern day movement have profoundly changed the lives of women, men and children. We have raised public consciousness about the plight of women to such an extent that today the majority of people support equality for women.In the past 32 years, women have advanced farther than in any previous generation. Yet still we do not have full equality.We have moved more feminists than ever before into positions of power in all of the institutions that shape our society. We have achieved some measure of power to effect change in these institutions from within; yet still we are far from full equality in decision-making. We demand an equal share of power in our families and religions, in law, science and technology, the arts and humanities, sports, education, the trades and professions, labor and management, the media, corporations and small businesses as well as government. In no sphere of life should women be silenced, underrepresented, or devalued.Today, we reaffirm our demand for Constitutional equality for women and girls. Simultaneously, we are working with sister organizations to develop and pass a national women's equality act for the twenty-first century. And we participate in and advance a global movement for women and demand that the United States join the overwhelming majority of nations of the world in ratifying the United Nations Convention on the Elimination of All Forms of Discrimination Against Women without reservations, declarations, or understandings that would weaken this commitment.We reaffirm our commitment to the power of grassroots activism, to a multi-issue, multi-tactical strategy.We are committed to a feminist ideology and reaffirm our historic commitment to gaining equality for women, assuring safe, legal and accessible abortion and full reproductive freedom, combating racism, stopping violence against women, ending bigotry and discrimination based on sexual orientation and on color, ethnicity, national origin, economic status, age, disability, size, childbearing capacity or choices, or parental or marital status.We will not trade off the rights of one woman for the advancement of another. We will not be divided. We will unite with all women who seek freedom and join hands with all of the great movements of our time and all time, seeking equality, empowerment and justice.We commit to continue the mentoring, training, and leadership development of young and new activists of all ages who will continue our struggle. We will work to invoke enthusiasm for our goals and to expand ownership in this movement for current and future generations.We commit to continue building a mass movement where we are leaders, not followers, of public opinion. We will continue to move feminist ideals into the mainstream thought, and we will build our media and new technology capabilities to control our own image and message.How long and hard a struggle it was to win the right for women to vote. Today, we fight the same reactionary forces: the perversion of religion to subjugate women; corporate greed that seeks to exploit women and children as a cheap labor force; and their apologists in public office who seek to do through law what terrorists seek to accomplish through bullets and bombs. We will not submit, nor will we be intimidated. But we will keep moving forward.Those who carried the struggle for women's suffrage through to its end were not there at the start; those who started the struggle did not live to see the victory. Like those strong feminist activists, we will not let ourselves be dispirited or discouraged. Even when progress seems most elusive, we will maintain our conviction that the work itself is important. For it is the work that enriches our lives; it is the work that unites us; it is the work that will propel us into the next century. We know that our struggle has made a difference, and we reaffirm our faith that it will continue to make a difference for women's lives. Today, we dedicate ourselves to the sheer joy of moving forward and fighting back.© 1995-2012 National Organization for Women, All Rights Reserved. Permission granted for non-commercial use.。
1998年下半年全国高等自学考试英语写作基础试卷
1998年下半年全国高等自学考试英语写作基础试卷Ⅰ. Revise the following sentences according to the requirement. Write your version in the corresponding space on your answer sheet. (15)1.Job Milton is one of his favorite poets. (periodic sentence)2.Steve approached the dean’s office. He walked at a slow pace. (simple sentence with –ingphrase)3.After she was introduced by her assistant, the mayor began with an opening statement.(simple sentence with –ed phrase)4.Jones has been without work for six months. He is having trouble paying his bills. (simplesentence beginning with prepositional phrase)5.The rescuers were careful as they handled the rope. They lowered the frightened climberfrom the ledge. (simple sentence with by phrase beginning with carefully)6.The old woman sat in her rocking chair on the porch. She watched her grandchildren race byon their bikes. (simple sentence with –ing phrase)7.Michael wanted to go swimming, Jane decided to go shopping. (compound sentence)8.Montesquieu popularized the English system of checks and balances among the branches ofgovernment. This ideal was adopted as a model by the writers of the American constitution.(compound sentence)9.The gardener waters the flower beds regularly. Or the flowers droop and die. (complexsentence beginning with unless)10.When they arrived home, they unpacked their suitcases, took showers, and then they went tosleep after eating their lunch. (parallel structure)Ⅱ. Correct the errors I the following sentences and write down the correct sentences in the corresponding space on your answer sheet. (10)1. Mike decided to stop smoking he didn’t want to die of lung cancer.2. She tries to call home once a week. To stay in touch with her family.3. My movie idol is not only tall but also is handsome.4. They played while I was reading with the new pups in the basket.5. Having almost no money, my survival depended on my parents.Ⅲ. Choose the topic sentence:(Ⅰ) Choose the best topic sentence from each group below. Write the letter of the answer you have chosen in the corresponding space on your answer sheet. (8)1. A. University students can get scholarship if they are top students.B. University students are now enjoying better conditions than ever before.C. In the past university students couldn’t get a loan from the government.D. In some universities students don’t need to pay for their accommodation.2. A. The common housefly is very dangerous.B. The common housefly is found in many parts of the world.C. The common housefly carries germs everywhere it goes.D. The common housefly leaves thousands of germs on the food.3. A. The clock was once battered by bombs.B. It was built more than a hundred years ago.C. Big Ben is considered the world’s most famous clock.D. People in London like to check their clocks by Big Ben.4. A. In addition to the natural materials, modern man now has cloth which is madesynthetically.B. For example, he may have worn the skins of animals to celebrate his victories overthem.C. Modern man wears clothing for three purposes: for protection, for decoration, and formodesty.D. Not until recently was it possible to use only natural materials of various kinds for themaking of clothing.(Ⅱ) Read the following paragraphs and spot the topic sentence of each paragraph. Write the number of the topic sentence in the corresponding space on your answer sheet. (6)1.(1) Progress is gradually being made in the fight against cancer. (2) In the early 1900s,few cancer patients had any hope of long-term survival. (3) In the 1930s, less than one in five cancer victims lived more than five years. (4) In the 1950s, the ratio was one in four, and in the 1960s, it was one in three. (5) Currently, four of ten patients who get cancer this year will be alive five years from now. (6) The gain from one in four to four in tenrepresents about 69,000 lives saved each year.2.(1) Crime in the country, of course, is somewhat different from city crime. (2) Who wasever attacked while walking along the village street in Middleton? (3) The things that John Pooley has to watch for are people stealing tools and equipment from farm vehicles, or wood from the surrounding forests. (4) There are natural dangers too: he is so worried about the fire risk in forests that he has turned his bedroom window into a look-post.3.(1) Powerful computers capable of translating documents from one language into anotherhave been recently developed in Japan. (2) The process of machine translation is complex.(3) To translate a document from English into Japanese, for example, the computer firstanalyzes an English sentence, determining its grammatical structure and identifying the subject, verb, objects, and modifier. (4) Next, the words are translated by an English-Japanese dictionary. (5) After that, another part of the computer program analyzes the resulting awkward jumble of words and meanings and produces an intelligible sentence based on the rules of Japanese syntax and the machine’s understanding of what the original English sentence meant. (6) Finally, the computer produced translation is polished by a human bilingual editor.(Ⅲ) Read the following paragraphs carefully and select the best topic sentence from the four possible answers that follow each paragraph. Write the letter of the answer you have chosen in the corresponding space on your answer sheet. (6)1.Topic sentence:In the past, teachers made children sit still for hours. They made them memorize all sorts of things. In other words, the children had to go on repeating things until they knew them “by heart”. Today, many teachers wonder if it is possible to make children learn at all. They say you can only help them learn. They say you must let children learn and discover things for themselves.A)Educating a child is by no means an easy job.B) A teacher’s job is to make children learn.C)Education for children is to be emphasized.D)Children’s education is changing very rapidly.2.Topic sentence:To the tourists, it is a city of hurrying crowds, horn-blowing traffic jams, dirty streets and smelly subways－all in sharp contrast to such international symbols as Wall Street and the United Nations Building. But to most local inhabitants and commuters, it is simply an enormous and busy working field associated with business activities and goods manufacturing－a place to leave as soon as possible in the evening for the more peaceful atmosphere of the suburban areas. Meanwhile, New York remains to be the most populous, flourishing and prosperous metropolitan city in the western Hemisphere.A)New York is one of the largest cities in the world.B)New York is, in the tourist’s mind, a metropolitan city full of charm andexcitement.C)New York is, depending on one’s point of view, any one of the two cities.D)New York is, to most local inhabitants, a business and financial center.3.Topic sentence:The service line is frequently so long that a student gives up the idea of eating altogether.If she is patient enough to wait for food, she is lucky if she can find a place to eat. If she is particularly agile, she may work her way through the masses to a spot where she can eat it before it’s cold. Once seated, however, she is likely to find the atmosphere so choked with other bodies, noise, and dead air, that she loses her appetite. She cannot easily slip away at that point, either. Wedging her way out of the cafeteria, she discovers, is as miserable a matter as working her way in.A)The university is one of the biggest tourist attractions in town.B)The university cafeteria is one of the most crowded places on campus.C)The dining-hall is ugly and dirty and makes the students lose appetite.D)The City College always accepts more students than it can actually accommodate.Ⅳ. Rearrange the following numbered sentences so that they will read logically. Put the numbers in proper sequence in the corresponding space on your answer sheet. (5)1.Clearly, in agriculture and in industry, the progress of a country depends on the busy handsof its working people.2.Manual labor is one of the principal development resources in any industrializing country, asthe following examples demonstrate.3.And of course the manufacture as well as the maintenance of machines of all kinds needs alarge number of trained mechanics and technicians.4.To begin with, ploughing fields, planting and harvesting crops, and raising livestock areimportant to development and all require people who work with their hands.5.Secondly, mining natural resources, building roads and bridges, and constructing dams forirrigation and electrical power are also important to development and also require people who know how to use their hands skillfully.6.Finally, the establishment of efficient transportation and communication systems, essentialservices in a modernizing economy, relies heavily on a labor force of expert craftsmen whoⅤ. Read the following paragraphs and write down the numbers of the four irrelevant sentences in the corresponding space on your answer sheet. (10)A. (1) For hundreds of years, man has made use of the talents of monkeys. (2) Egyptian paintingsof 2000 B.C. show baboons gathering fruit for their masters. (3) Even in 1879, in Abyssinia, monkeys were still being used as torchbearers at feasts. (4) The monkeys would sit in a row ona bench and hold the lights until the guests went home. (5) Then the monkeys would eat. (6)Most of the world’s zoos contain a variety of monkeys for people to watch.B. (1) Pearls are gathered by men known as pearl divers. (2) Actually, these men do not dive. (3)They are lowered by a rope to the bottom of the sea. (4) But sky-divers jump from the planes.(5) Many tourists to Japan enjoy shopping for cultured pearls. (6) Pearl gatherers work in pairs,with in remaining at the surface to help the other return from his dive. (7) An experienced pearl diver can stay down about a minute and a half and can often make as many as thirty dives in one day.Ⅵ. Write a note according to the situation described. Write your version in the corresponding space on your answer sheet. (15)You are Wang Lan. You need to write a note to make an appointment. You would like to discuss some problems in translation with your teacher and ask him/her to arrange a suitable time for the meeting if he/she finds the time you have suggested inconvenient for him/her and let you know about the arrangement. Make sure to include at least the following points: purpose, time, date, place. (40－70 words)Ⅶ. Write a letter using the information given below. Write your version in the corresponding space on your answer sheet. (25)You are Li Nan, chairman of the History Department. You want to invite Professor Herb Jason, a well-known scholar of Chinese history, to come to your university to attend an international conference on Chinese history. The conference will be held from July 23－26. You’l l cover his travel expenses. (120－170 words)Your letter should cover the following points:1) make some compliments about him;2) the purpose of the invitation;3) the time and place of the conference;4) ask him to tell you his time of arrival;5) ask him a favor of presenting a lecture to your students during his stay;6) promise to meet him at the airport.。
反射系数相位与群时延混合法+调谐耦合级联带通滤波器
反射系数相位与群时延混合法调谐耦合级联带通滤波器李良苏涛姜立伟底浩（西安电子科技大学天线与微波技术国家重点实验室，西安，710071）******************摘要：本文通过具体调试实例验证了反射系数相位与群时延混合法调谐耦合级联带通滤波器的可行性。
文章对比了反射系数群时延法和耦合带宽法，综合其优点提出相位与时延混合的方法，定性地分析了该方法减少读数次数，降低读数误差，提高调谐效率的特点并以实例验证。
关键词：反射系数相位，群时延，耦合带宽，滤波器调谐，级联耦合Tuning Coupled Cascaded Bandpass Filter Using Mixed Method of Reflection Coefficient Phase and Group DelayLi Liang, Su Tao, Jiang Liwei, Di Hao（National Key Laboratory of Antennas and Microwave Technology, Xidian Univ., Xi’an, 710071）Abstract: In this paper, a tuning example is used to prove the practicability of mixed method of reflection coefficient and group delay. The auther also makes a comparison between reflection coefficient group delay method and coupling bandwidth method and proposes a mixed method of phase and group delay which has both advatages of two former method. An performance analysis has been made to examine the characteristics of less reading times, low error rate and high efficiency in tuning.Keywords: reflection coefficient phase; group delay; coupling bandwidth; filter tuning; cascaded coupling1 引言微波滤波器是通信设备中不可或缺的无源器件。
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(Received in final revisedform 15 August 1996)
Abstract--This paper presents a novel approach to determine the overall elastic-viscoplastic behavior of a particle-reinforced metal-matrix composite. It is built upon the linkage from elasticity to viscoelasticity through the correspondence principle, and then from viscoelasticity to viscoplasticity by means of the concept of secant viscosity and an energy approach. Albeit approximate, this theory is analytically tractable, and capable of delivering the stress-strain relations of the composite system under various applied strain rates. The theory embodies the nonlinear, rate-dependent, and work-hardening nature of the constitutive equations of the ductile matrix, as well as the elasticity of both matrix and inclusions. The influence of particle concentration, elastic stiffness, and applied strain rate on the overall dilatational and deviatoric stress-strain behaviors are examined in detail. The theory is finally applied to predict the response of a silicon-carbide/aluminum system and the result is found to be in accord with experimental observations. © 1998 Elsevier Science Ltd. All rights reserved
A UNIFIED APPROACH FROM ELASTICITY TO VISCOELASTICITY TO VISCOPLASTICITY OF PARTICLE-REINFORCED SOLIDS*
J. Li a n d G. J. W e n g Department of Mechanical and Aerospace Engineering, Rutgers University, New Brunswick, NJ 08903, U.S.A.
*Dedicated to the memory of James F. Bell. 193
194
J. Li and G. J. Weng
be described by a modern unified theory, its constitutive relation can also be cast into a form which involves a proportional constant between the viscoplastic strain-rate and the deviatoric stress. If this coefficient is identified as the "secant viscosity", then it would play the role of shear viscosity in a viscoelastic matrix. When the shear viscosity is identified with this secant viscosity of the viscoplastic matrix at a given stage of deformation, the instantaneous overall viscoelastic response could then be used to construct the response of the viscoplastic composite. Unlike the ordinary viscosity, however, this secant viscosity continues to change in the course of deformation, and therefore the shear viscosity must be successively updated in the process. Such a successive replacement of shear viscosity of the Maxwell matrix by the secant viscosity of the viscoplastic matrix will require an explicit result for the viscoelastic response after Laplace inversion. Moreover, the rate forms of the Laplace inversion will have to be used over the total forms due to the continuous change of secant viscosity. In order to give a clear exposition of this new method, we shall focus on the particle-reinforced system in which elastic spherical particles are homogeneously dispersed in an elastic-viscoplastic matrix. This perspective is to a great extent prompted by the recent success in obtaining the rate-independent elastoplastic behavior of a two-phase composite by making use of the known elastic properties of a system with an identical microgeometry. In a series of papers Weng and his co-workers (Tandon and Weng, 1988; Weng, 1990; Qiu and Weng, 1992) have used the secant moduli of the ductile matrix as the elastic moduli of the elastic matrix to estimate the overall elastoplastic response. This method has yielded results which are consistent with the exact solutions (Qiu and Weng, 1992, 1995) and experimental data (Tandon and Weng, 1988). When coupled with an energy approach, it also coincides with the bounds and estimates developed by Ponte Castaneda (1991) and Willis (1991). Detailed discussions on the latter subject can be found in Qiu and Weng (1992, 1993) and Hu (1996). The rationale there was that, if the secant shear-modulus of the elastic-plastic matrix could be captured accurately, then so would the elastoplastic response. Similarly, in an elastic-viscoplastic system, if the secant viscosity of the ductile matrix can be captured then so would its overall response. Due to the rate form of the constitutive equation, however, a viscoelastic composite must now serve as the direct comparison material. Decomposition of the total strain rate into the elastic and viscoplastic rates further has led us to choose a Maxwell material as the comparison viscoelastic matrix. H. CONSTITUTIVE EQUATION OF THE VISCOPLASTICMATRIX There exists an extensive body of literature on the constitutive modeling of viscoplastic solids• These models display various degrees of sophistication, with some directed towards cyclic and non-proportional loadings. Clearly it is not the intention of this article to take issue on this subject. For the present purpose of finding the stress-strain behavior of a particle-reinforced composite under a monotonic loading, it suffices to invoke the simplest unified theory which is capable of accounting for the nonlinear and strain-hardening behavior of the viscoptastic matrix. In general the total strain-rate of the matrix can be decomposed into the elastic and viscoplastic components E/j = ~,y+ E0