Control of mass transport in the vapour growth of bulk crystals of CdTe and related compounds

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英概一句话简答完整版(余志远版本)

英概一句话简答完整版（余志远版本）1. What is the full name of the United Kingdom?It is the United Kingdom of Great Britain and Northern Ireland.2. What are the two large island that make up the British Isles?They are Great Britain and Ireland.3. What are the four political divisions of the United Kingdom?They are England, Scotland, Wales and Northern Ireland.4. Why does the United Kingdom have a mild climate, even though it lies farther north than our Heilongjiang Province?Because Britain’s climate is in fluenced by the Gulf Stream.5. How many metropolitan areas does England have?England has seven metropolitan areas.6. What is the backbone of England?It is the Pennines.7. What is the largest lake in the British Isles?It is Lough Neagh.8. From what languages is English derived?England is mainly derived from the Anglo-Saxon and Norman-French languages.9. What is an eisteddfod?An eisteddfod is a Welsh festival of poetry, music and other arts.10. What have the Scottish people been famous for?The Scottish people have been famous for their close-knit clans, colorful plaid kilts, and skill as fierce warriors.11. How long was Britain under the Roman occupation?Britain was under the Roman occupation for nearly 400 years.12. Why was the Roman impact upon the Britons surprisingly limited?The R oman impact on the Britons was surprisingly limited because the R omans always treated the Britons as a subject people of slave class and they never intermarried with the native Britons.13. When did the Anglo-Saxons begin to settle in Britain?The Anglo-Saxons began to settle in Britain in the 5th century.14. When did England begin to be Christianized?England began to be Christianized in 579.15. What was the result of the Synod of Whi tby in Yorkshire in 664?The result of the Synod of Whi t by was that the Roman missionaries gained the upper hand over the Cel t ic missionaries.16. What was Harold doing when he was informed of the invasion of Northumbria by Tostig and Harold Hardrada?He was in the south preparing to resist the expected attack from Normandy.17. Where did Harold defeat Tostig and Hardrada?Harold defeated Tostig and Harold Hardrada at Stanford Bridge.18. By whom was William crowned King of England in Westminster A bbey?William was crowned King of England in Westminster Abbey by the Archbishop of York.19. What did William do after he suppressed the Saxon risings in the north?He built a string of defense castles to ensure his military control of the whole country.20. Was the Norman Conquest the last successful invasion of England?Yes. The Norman Conquest was the last successful invasion of England because England has never been invaded since.21. Why did William I give his barons large estates in England?William I gave large estates to his barons because he wanted to get a promise of military service and a proportion of the land’s produce.22. What was the peculiar feature of the feudal system of England?All landowners, big and small, took the oath of allegiance for the land they held, not only to their immediate lord, but also to the king.23. Why did William I have the Domesday Book compiled?William I had the Domesday Book compiled because he wanted to have a reliable record of all his land, his ten ants and their possessions and to discover how much his tenants could be asked to pay by way of taxes.24. What was William I ‟s policy towards the church?He wanted to keep it completely under his control, but at the same time to uphold its power.25. Why did Henry II make Thomas Becket Archbishop of Canterbury?He thought that Thomas Becket would assist him in carrying out legal reforms.26. What brought Henry II into collision with Thomas Becket, the Archbishop of Canterbury?The exceptional privileges enjoyed by the clergy brought Henry II into collision wi t h Thomas Becket.27. What are the two aspects of the Norman legacy that contributed to great domestic unrest in England in the 12th and 13th centuries?One was England’s possession of territor y in France. The other was Norman adherence to Roman Catholicism.28. Who was the French national heroine during the Hundred Year‟s War who helped the French to drive the English out of France?Joan of Arc.29. When did the government establish rules for the first time to keep down wages?The government established rules for the first time to keep down wages in 1351.30. How many peasant in Kent and Essex were killed by Richard II ‟s troops?40,000 peasants in Kent and Essex were killed by Richard II’s troops.31. What were the emblems of the Houses of York and Lancaster?The emblem of the House of York was a white rose and the emblem of the House of Lancaster was a red rose.32. What was the impact of the Wars of the Roses on feudalism in England?The Wars of the Roses dealt a death blow to feudalism in England.33. How did Elizabeth I try to avoid troubling Parliament too often for pounds?She tried to avoid troubling Parliament by making strict economies at Court.34. What questions did Elizabeth I treat as personal and private?These questions were her religion, her marriage, her foreign policy, the succession to the throne, and her finance.35. How did Elizabeth I manage to maintain in friendly relationship with France?She managed to maintain a friendly relationship with France through her marriage alliances which were never materialized.36. When was Mary Queen of Scots executed?Mary Queen of Scots was executed in 1587.37. What did the destruction of the Spanish Armada show?It show ed England’s superiority as a naval power.38. What was the long-term result of the Gunpowder Plot?The long-term result of the Gunpowder Plot has been an annual celebration of November 5, when a bonfire is lit to burn a guy and a firework display is arranged.39. What was Puritanism noted for?It was noted for simple dress, high moral standards and very egalitarian attitudes.40. What is a constitutional monarchy?A constitutional monarchy is one whose power is limited by Parliament.41. What did the Whigs stand for in the early 19th century?They stood for a reduction in Crown patronage, sympathy towards Nonconformists, and care for the interests of merchants and bankers.42. Why did changes in farming methods affect lives of millions in the 18th century?Changes in farming methods affected lives of millions in the 18th century England because village and agriculture were the backbone of England at that time.43. What did the land owners want to do in the late 18th and early 19th centuries?They wanted to replace the small farms cultivated on the “open-field” system by larger, economically more efficient farms with hedge-divided fields.44. Why was King George III nicknamed “Farmer George”?King George III was nicknamed “Farmer George” because he was very enthusiastic about agricultural changes at Winsor.45. What were the two events which most alarmed the British ruling classes in the closing decades of the 18th century?They were the American War of Independence and the French R evolution.46. When did the British begin to transport convicts to Australia?The British began to transport convicts to Australia in 1788.47. What was the result of the general strike of 1926?The strike failed. The miners were forced to return to work with longe r hours and lower wages even than before. Yet, outside the mining district, the strike seemed to have improved relations between the workers and the middle classes. 48. Why d4id Edward VIII abdicate in 1936 after a reign of 10 months?Edward VIII abdicated because he wanted to marry Wallis Simpson, a twice-divorced American.49. When did Britain finally become a full member of the European Economic Community?Britain finally became a full member of the European Economic Communi t y in January,1973.50. Why was Mrs. Thatcher removed from office in 1990?It was because of her opposition to European Union and her imposition of an extremely unpopular flat-rate “poll tax” in place of property taxes to pay or local government service.51. What are the economic problems Britain is now faced wi th?Britain is now faced wi t h a low rate of industrial growth, unemployment, and a rising inflation rate.52. What percentage of British workers are employed in service industries?More than 70% of British workers are employed in service industries.53. Why were early factories located near the coal fields?Because coal powered the steam engines that moved the machinery.54. In which British industry did the Industrial Revolution begin?The Industrial Revolution bega n in Britain’s textile industry.55. Where are oil and natural gas found in Britain?Oil and natural gas are found under the North Sea.56. Why is it that Britain imports more clothing than it exports?Because many countries with lower labor costs can produce clothing more cheaply than the British can.57. Which area in Britain is called the “Silicon Glen”?The area between Glasgow and Edinburgh in Scotland is called the “Silicon Glen”.58. What is the county of Kent in southeastern England famous for?It is famous for its beautiful blossoms of its apple and cherry orchards in springtime.59. What are Britain‟s most important imports?British imports include chemicals, clothing, foods, machinery, metals, motor vehicles, paper and newsprint, petrole um products, and textiles.60. What are Britain‟s most important exports?British exports are aerospace equipment, chemicals and pharmaceuticals, foods and beverages, machinery, motor vehicles, petroleum, and scientific and medical equipment.61. Where does the Sovereign‟s coronation take place?The Sovereign’s coronation takes place at Westminster Abbey in London.62. When is the Sovereign‟s birthday officially celebrated?It is officially celebrated in June every year.63. What does the Duke of Edinburgh do when the Queen pays state visits to foreign governments?He accompanies her.64. Where does the Queen‟s expendi ture arising from public duties come from?The Queen’s expenditure arising from public duties comes from the Civil List and governm ent departments.65. What does the term “parliament” originally mean?The term “parliament” originally means a meeting for a parley or discussion.66. What is the main function of the House of Lords?The main function of the House of Lords is to bring the wide experience of its members into the process of law-making.67. What is the Speaker‟s task in the House of Commons?His task is to preside over the House and enforce the rules of order.68. How many counties are there in England and Wales?There are 53 counties in England and Wales.69. What are the three island areas where single-tier authorities were introduced in Scotland?They are the Orkneys, the Shetlands and the Western Isles.70. How do local authorities in Great Britain raise revenue?They raise revenue through the council tax.71. What are the two main branches of the law in Britain?They are criminal law and civil law.72. How many types of criminal courts are there in Scotland?There are three types of criminal courts in Scotland. They are the High Court of Justiciary, the sheriff court, and the district court.73. What is the difference between solemn procedure and summary procedure?In solemn procedure, a defendant is tried by a judge sitting with a jury. In summary procedure the judge sits without a jury.74. What are the three divisions of the High Court?They are the Family Division, the Chancery Division, and the Queen’s Bench Division.75. What is the ul timate court of appeal in civil cases throughout the United Kingdom?It is the House of Lords.76. Who directly controls London‟s Metropolitan Police Force?The Home Secretary controls London’s Metropolitan Police Force.77. What are the chief aims of the penal system?The chief aims are to deter the potential law-breaker, and to reform the convicted offender.78. How many prisons are there in Northern Ireland?There are 4 prisons in Northern Ireland.79. How long can a court probation order last?A court probation order can last between 6 months and 3 years.80. What courses (or schemes) and services are provided in all prisons?Training courses, educational schemes, medical services and welfare services are provided in all prisons.81. Are British people obliged to use the National Health Service?No. They are not obliged to use the service.82. What are services for elderly people aimed at?Services for elderly people are aimed at helping them live at home whenever possible.83. What is the aim of the social security system?The aim of the social security is to secure a basic standard of living for people in financial need.84. At what age do men and women generally retire?Men generally retire at the age of 65, and women at the ate of 60.85. What are the two established churches in Britain?They are the Church of England in England and the Church of Scotland in Scotland.86. How many provinces does the Church of England have?The Church of England has two provinces: Canterbury and York.87. When were the first women priests ordained in Britain?They were ordained in March 1994.88. Who founded the Salvation Army in the East of London in 1865?William Booth, a great follower of John Wesley, founded the Salvation Army.89. Where do the people in London go to see the Christmas decorations?They go to Oxford Street, Regent Street and Piccadilly to see the Christmas decorations.90. Why is December 26th called “Boxing Day”?December 26th is called Boxing Day because i t was formerly the custom to give “Christmas boxes”, or gifts of money, to servants and tradesmen on this day.91. How many kinds of state secondary schools are there in Great Britain?Three. They are grammar school, secondary modern school and comprehensive school.92. When was the Open University founded? When did it begin its first courses?It was founded in 1969, and i t began its first courses in 1970.93. Why is the Open University so named?It is so named because it is “open” to all to become students.94. How much money is spent on press advertising every year in Great Britain?About ￡5,100 million.95. How much time do British people spend a day watching television?People spend an average of over three and a half hours a day watching television.96. How are the state-run television channels BBC1 and BBC2 financed?They are financed from the sale of television licences.97. How are independent channels ITV and C4 funded?They are funded entirely by advertising.98. When did the BBC begin to provide regular television broadcasts?The BBC began to provide regular television broadcasts in 1936.99. Which sport is regarded as typically English?Cricket is the most typically English sport.100. What is a “copyright” library?It is a library which is entitled to receive a free copy of every book published in the United Kingdom.1. How does the United States rank among the countries of the world in population and area?The United States of America is the third-largest country in the world in population and the fourth-largest country in area.2. What are the two major mountain ranges in the United States?They are the Appalachian Highlands and the R ocky Mountains.3. What is the Continental Divide, or Great Divide?The Continental Divide, or Great Divide, is an imaginary line that separates streams that flow into the P acific Ocean fromthose that flow into the Atlantic.4. What are the five Great Lakes of the United States?They are Erie, Huron, Michigan, Ontario, and Superior.5. How many geographical regions can be found in the United States? What are they?There are seven geographical regions in the United States. They are New England, the Middle Atlantic States, the southern States, the Midwestern States, the R ocky Mountain states, the Southwestern States, and the Pacific Coast States and the New States.6. What states are in New England?New England is made up of six states of the North-East. They are Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut.7. Apart from Now York City, what other large cites are located in the Middle Atlant ic region? Philadelphia, Pittsburgh, Buffalo, and Newark.8. What is the Midwest famous for?The Midwest is famous for its large stretches of fertile soil.9. What states make up the Pacific Coast Region?The region known as the Pacific Coast includes the western parts of Washington and Oregon and nearly all of California.10. What role does tourism play in Hawaii‟s economy?Tourism is Hawaii’s most important industry.11. What is the population of the United States? How does it rank in the world?The Uni t ed States is the third most populous country in the world after China and India, with a population of 267 million (estimated) in April 1997.12. What is the reason for the growth of population in Florida?It is because of its warm climate and convenience in doing business with and traveling to Central and South America. 13. Which are the five biggest cities, in terms of population, in the United States?New York, Los Angeles, Chicago, San Francisco, Philadelphia.14. Why are people moving so often in the United States?People often move from one place to another for various reasons: to look for better job opportunity or for better climate or for other goals.15. What are some of the consequences of the outflow of city residents to the suburbs?The movement brings serious consequences to big cities: rising unemployment rate, the increase of the number of poor people, the worsening of city living conditions and the fall of government revenues.16. Which are the three largest groups of Hispanics?The Chicanos, the Puerto Ricans and the Cuban-Americans.17. Why do many Puerto Ricans go to the United States?They are drawn to the United States by better job opportunities.18. What explanation do experts give for the success of Asian-Americans?The experts attribute the success to Asian cultural tradition: emphasis on education, hard work and family.19. What was the fate of Japanese-Americans in WWII?The Japanese-Americans were taken to relocation centers in isolated parts of the western mountain and plains states and stayed behind barbed wires.20. Can you give an example to show the awakening of American Indians?Many Indians are taking legal steps to demand compensation for land and resources grabbed from them illegally.21. What is one of the explanations of how the early Indians came to the Americans?One of the explanations is the Indians crossed from Asia on the landbridge that connected Siberia and Alaska.22. How did the Plymouth settlers manage to survive?The neighboring Indians came to teach them how to grow corn and they succeeded in having a good harvest.23. In what way were the Puritans different from the Pilgrims?The Pilgrims were mostly poor, labouring people while the Puritans were wealthy, well-educated gentlemen.24. Did the War of Independence start with the adoption of the Declaration of Independence?No. I t started when clashes took place at Concord and Lexington.25. What was the chief weakness of the Articles of Confederation?The chief weakness was the document failed to set up a government that could function.26. What was the significance of the adoption of the Bill of Rights?The adoption of the Bill of Rights in addition to the Consti t ution completed the foundation of the American constitutional system.27. Why did American territorial expansion threaten British interest?Because some Americans wanted to take advantage of the war in Europe to expand into Canada. This ran counter to British interest.28. What was the Compromise of 1850?The Compromise of 1850 was an arrangement which kept a balance between free and slave states in the Senate.29. Why did the Civil War break out?The Civil War broke out because the southern states left the Union and formed a new nation but president Lincoln was determined to maintain the Union.30. How did the government help in the development of American economy?The government carried out the policy of trade protectionism.31. What were the three features in the growth of American economy at the beginning of the 20th century? Large corporation, urbanization and new technology were the three features.32. What was the basic demand of the Progressive Movement?The basic demand was government regulation of economic and social conditions.33. Why did the United States pursue a policy of pro-Ally partiality in the early part of WWI?Because of ethnic ties, cultural tradition, social background, economic interests and successful British propaganda, the U.S. government pursued such a policy.34. What were the immediate causes that led the United States into the war?The immediate causes were Germany’s unlimited submarine warfare and Germany’s attempt to get Mexico into the war against the United States.35. What government policies in the 1920s helped big business?The policies of tariff protection, favorable tax rates and little government restrictions contributed to high profits of big businesses.36. How did many Americans view their country after WWI?They believed that American political, economic and social institutions were the best in the world.37. What was the experience of WWI veterans demanding payment of bonuses in Washington D.C. in 1932? They were driven out of the capital by military force directed by General McArthur.38. What were some of the personal characteristics of F.D.R. that helped him in doing his work as president? He had a sure sense of what was practical or possible, a strong sense of timing and was a great communicator.39. What were the two guiding principles underlying American diplomatic activities in WWII?The first was to win the war; the second was to bring the Soviet Union into a postwar world order under American leadership.40. What was the basic reason for the postponement of the opening of the Second Front?It was a reflection of the desire of not letting the Soviet Union expand into eastern and central Europe too quickly.41. What was the postwar strategy of the United States?The strategy was American leadership of the world and open market for American goods and capi t al.42. What was the theory put forward by the Soviet Union in around 1946?There could be no long-term peaceful co-existence between socialism and capitalism.43. What was the immediate cause of the Berlin crisis in 1948?The Soviet Union cut off Western routes to West Berlin.44. What decision did President Truman make to deal wi th the Berlin crisis?He decided to mobilize all possible American cargo planes to airlift supplies into West Berlin.45. What effect did the Berlin blockade have on the people in West Berlin and western occupied zones?it pushed the people in West Berlin and western occupied zones further to the side of the United States because they were grateful for American airlifts.46. What measure did the United States take in the Cuban Missile Crisis?The Uni t ed States introduced a naval blockade around Cuba and demanded the dismantlement and withdrawal of the missiles from Cuba.47. Did the allies of the United States give their full support to the U.S. in the Vietnam War?No , some criticized the Uni t ed States for escalation of the war, some refused to support American war efforts.48. What is the significance of the Shanghai Communique?The key thing is American commitment to a one China policy.49. What is the importance of the Civil Rights Act of 1964?The Act outlawed racial discrimination in housing and employment.50. What is the Port Huron Statement about?The Port Huron Statement was the platform of the Students for a Democratic Society ( SDS ) which condemned racism, poverty amidst plenty, big corporations and the Cold War.51. How does the United States rank among the countries of the world in the total value of its economic production?The United States ranks first among the countries of the world in the value of its economic production.52. What kind of system is the United States economy based on?The United States economy is based on a free enterprise system.53. What are the factors that have helped build the United States into the economic giant it is today?The United States has one of the world’s most varied populations, and the vast space and resources of the land, the ideals of freedom and economic opportuni t y, and hard work by the people have helped build the United States into the economic giant it is today.54. What are the major natural resources in the United States?Fertile soil, forests, water, and minerals are the major natural resources in the United States.55. What are some of the leading farm products in the United States?They are corn, wheat, beef cattle, milk, soybeans, cotton, chickens and eggs, and hogs.56. What has helped make U.S farms the most efficient in the world?The use of modern farm machinery and agricultural methods has helped make U.S. farms the most efficient in the world.57. What areas have long been major U.S centers of manufacturing?The Midwest and Northeast.58. How does California rank among the states in the value of i ts manufactured goods?California ranks first among the states in the value of i t s manufactured goods.59. What are the problems the U.S economy has faced form time to time?They are recessions, depressions and inflation.60. Why is the poverty rate higher in the United States than in several other industrialized nations, including Canada, Australia, and Germany?Because they have more generous social programs for the poor and a higher minimum wage than the United States. 61. What role has the Constitution played?The Constitution has been the basis for the evolution of governmental institutions and for political stability, economicgrowth and social progress in the United States.62. What were the weaknesses of the Articles of Confederation?The weaknesses were: there was no national executive to enforce the laws and there was no n ational court system and Congress had no power to tax, nor to regulate trade between states.63. What mechanism did the writers of the Consti tution introduce to provide safeguards?They introduced the mechanism of separation of powers and checks and balances.64. What are the three branches of the government?They are the legislative, the executive and the judicial.65. How is the American president elected?The voters vote for the electors and the electors vote for the president. But as soon as the votes of the voters are counted the number of electors for each candidate is known and who has won the election is known.66. According to the Consti tution, what judicial power does the President have?He has the power to give reprieves and pardons in federal criminal cases.67. How are the two chambers of Congress made up?The Senate is composed of two members from each state, with a total number of 100 while membership in the House of Representatives is based on population. Currently the House has 435 members.68. What are the two special powers of the Senate?One is to confirm presidential appointments and the other is to ratify treaties by a tow-thirds vote.69. What is the composition of the federal court system?The federal court system consists of a supreme court, 11 courts of appeals, 91 district courts ( including one for the District of Columbia and one for Puerto Rico ) and three courts of special jurisdiction.70. What is the cause for the decline of the influence of political parties?The near destruction of the patronage system and the wide use of direct primaries in the selection of delegates to the party national conventions contribute to the decline of the influence of political parties.71. Is there any single sex educational insti t ution in the U.S.?Yes, there are qui t e a number.72. Why is it that responsibility for education fall on the state?Because it is laid down in the Tenth Amendment to the Constitution.73. Why are there many variations in the education system of the 50 states?Because each state is expected to develop policies for the education within its boundary.74. Who is the chief executive officer under the local board of education?The superintendent of schools.75. What are the three types of high schools?They are comprehensive, academic, vocational and technical schools.76. Why does the number of graduate school enrollment keep climbing?Because an advanced degree is viewed as a major way to move ahead in the career.77. What are the fields favored by postgraduates?Those fields that would not only make students easily employed but would provide them wi t h rewarding jobs.78. What is the guiding principle of community college?It is higher education for everyone and the philosophy that equality must mena equal opportunity for self-realization and for the recognition of individual difference.79. What are the two focuses of the reform in the 1980s?They are the raising of the standards of teaching and learning and the restructuring of the schools.80. Are the goals set out in the plan “America 2000” easy to achieve?No, they are very difficult to achieve.81. Who were the writers of the first American writings?。

牛油果主要病虫害及其防治

热带农业科技Tropical Agricultural Science &Technology 2024,47(1)：6-10牛油果主要病虫害及其防治毛加梅，黄建，付小猛，杨虹霞，郭俊，王自然，岳建强*（云南省农业科学院热带亚热带经济作物研究所，云南保山678000）摘要摘要：：概述世界各地牛油果的主要害虫种类（蝇类、蛾类、蚧类、螨类，半翅目和鞘翅目类）、主要病害种类（根腐病、炭疽病、疮痂病等真菌性病害以及细菌性软腐病和溃疡病）和病虫害防治现状。

近年来国内牛油果种植面积快速扩张，文章提出从科学合理选园、加强检验检疫、合理选种、选择适宜防治措施等方面来预防和防治牛油果病虫害。

关键词关键词：鳄梨；害虫；病害；防治中图分类号：S667.9文献标识码：A文章编号：1672-450X （2024）01-0006-05Main Diseases and Insect Pests of Avocado and the ControlMAO Jiamei,HUANG Jian,FU Xiaomeng,YANG Hongxia,GUO Jun WANG Ziran,YUE Jianqiang *Institute of Tropical and Subtropical Cash Crops,YAAS,Banshan 678000,ChinaAbstract:The major pest species (flies,moths,scale,mites,hemiptera and coleoptera ）,major disease species (fungal diseas-es such as root rot,anthracnose,scab,and bacterial soft rot and canker ）and pest control status on avocados in the world were summarized.In recent years,the planting area of avocado has expanded rapidly in China.This paper puts forward some measurements against avocado diseases and pests from the perspective of scientific and rational orchard selection,strengthening inspection and quarantine,rational seed selection,and selecting appropriate control methods.words Key words::Persea americana ;insects;diseases;control————————————收稿日期：2023-06-25基金项目：云南省重大科技专项计划（202202AE090004）；保山市科技计划项目（2018kj03）作者简介：毛加梅（1987－），女，助理研究员，主要从事果树病虫害研究工作。

The control of urban sprawl

The Control of Urban SprawlChris Couch and Jay KarechaThe Past.It can be argued that the improvements in systems urban transportation in the late 19th century led to the first wave of urban sprawl in Britain. The last quarter of that century saw a dramatic fall in the density of new working class housing developments as the introduction of suburban railways, horse-buses and later, trams, permitted the colonisation of large areas of cheap land beyond the urban periphery. However, the dependency upon public transport routes tended to lead to a star-shaped pattern of urban growth that retained some access to the countryside through the ‘green wedges’ that remained between the growth corridors.Control of this urban sprawl was one of the earliest reasons for the introduction of town planning in Great Britain. The Housing, Town Planning Etc, Act 1909, for the first time permitted local authorities to prepare town planning schemes for land beyond the existing urban area that was liable to be developed in the foreseeable future. Although there was no attempt to limit the amount of land to be developed, land use zoning and controls over the density of development gave planners an opportunity to determine and manage the pattern and form of urban growth.By the end of the first world war, new housing policies were introduced to meet an acute housing shortage. The Ministry of Health for the first time subsidised the building of council housing (social housing) from central government funds. Influenced by the ‘Garden Cities Movement’ and the Tudor Walters Report (1918), the Ministry encouraged the building of large low density ‘cottage estates’ on the edge of major cities. Changing economic circumstances also led to a boom in speculative private housebuilding for owner occupation. These estates too comprised sprawling, low density, housing built on green field sites. These twin strands of residential expansion were both supported by and encouraged investment in urban public transport systems, most notably in extensions to the London Underground.By the end of the twenties there was growing concern and opposition to the unprecedented scale and extent of urban sprawl that seemed to be enveloping every city in the country. A new Town and Country Planning Act had been passed in 1932 but with little effect on sprawl. In particular,“there was one aspect of suburban development which caused particular public and political concern in the 1930s building boom. This was the tendency for arterial roads to be subject to ill-considered ribbon development of cheaper housing extending out well beyond the more continuous built-up areas. The practice saved the developers the cost of building proper residential roads, but damaged the scenic quality and undermined the efficiency and safety of main roads by mixing local and through traffic. It was disliked even by many of the right-wing opponents of town and country planning” (Ward, 1994, p48).The Restriction of Ribbon Development Act 1935, gave highway authorities specific powers to prevent this abuse. Nevertheless, neither Act had any significant impact on the total volume of urban sprawl, especially as around one third of the new housing was planned and developed by local authorities themselves and most of the rest was facilitated and controlledby other public policies in some shape or form. Between 1922 and 1939 over 340,000 hectares of rural land were converted to urban uses: a 40% increase in the total urban area of the country (Ward, 1994, p49). It was therefore inevitable that questions would be asked about how sprawl might be controlled and whether its form should be better planned. Supporters of the ‘Garden Cities Movement’ had long argued that urban growth could be accommodated in planned and self-contained satellite towns that would combine ‘the best of town and country’ and avoid the monotony and lack of amenity of ever-sprawling suburbs. Another strand of argument called for the introduction of ‘green belts’ around and between cities to prevent unplanned urban incursions into the countryside and the coalescence of adjoining settlements.In his Greater London Plan of 1944, Patrick Abercrombie put forward proposals for the planning of the capital in four rings: an inner urban ring (the pre-1914 city) which would be subject to urban renewal; a suburban ring (mainly developed between 1919 and 1939) where little change was anticipated; a green belt where virtually all urban development would be prohibited; and an outer country ring where a number of satellite towns were proposed to accommodate London’s need for growth and the overspill caused by the renewal of the inner ring.The New Towns Act 1946, allowed the Government to establish New Town Development Corporations to develop new or satellite towns around London and other major cities as a mechanism for containing urban growth and sprawl within planned settlements. The Town and Country Planning Act 1947, extended the obligation to produce development plans to all local planning authorities in order to plan the use and development of land throughout the country. Land saving, controlling urban expansion and a disdain for suburbia were emerging issues debated by planners during the post-war years. In 1955 Circular 42/55 allowed local planning authorities to formally incorporate ‘green belts’ into statutory development plans, so providing them with greater powers to control and limit urban sprawl than they had ever had before.But urban sprawl continued, partly fuelled by a massive programme slum-clearance in all the major cities. Urban populations fell as cleared areas were rebuilt at lower densities and many cleared households were moved out to new peripheral council estates, expanded towns and new towns. At the same time economic growth combined with low interest rates supported a second boom in speculative building for owner occupation, only this time demand was coming from households who were car-owners and able to consider living at ever greater distances from the urban core and no longer tied to public transport routes. Urban sprawl began to fill the rural gaps in the star-shaped city and create more circular urban forms, divorcing more urban dwellers from easily experiencing the countryside.Throughout the period of the slum clearance programmes, from the 1930s to the 1960s the major cities had been losing population. Until late in the period this reduction in urban density was perceived as beneficial for it was associated with (though not the cause of) improvements in housing conditions and public health. It also provided space for new schools and other amenities. However, between the late 1960s and early 1970s there was to be a sea-change in urban policy. Whereas falling urban densities had been perceived as beneficial, the huge falls in urban populations now being recorded were perceived as problematic, particularly as the local tax base began to decline at the same time as residual (non-migrating, non-sprawling) populations were tending to be disproportionately old, poor and dependent upon local authority services. Local communities were increasingly critical of the slum clearance process and the lack of quality in the replacement housing offered, be it in situ or in overspill locations. At the same time central government was becoming concerned about the costs of slum clearance and seeking cheaper alternatives less demanding upon public expenditure. By 1968 it was also becoming apparent that many inner city areasharboured concentrations of social problems and deprivation. This powerful cocktail of pressures led to the beginnings of a new policy known as urban regeneration. Slum clearance was to be replaced by area improvement and attempts were made to reverse urban decline and tackle deprivation through a series of new managerial and fiscal measures. Thus from this period urban sprawl is not only seen as a problem of inefficient urban growth that detracted from the amenity of the countryside but also as a phenomenon that damaged the inner cities and therefore needed to be brought under yet further control. (It is interesting to note however that echoes of the ‘slum clearance’ type policies have again re-emerged in UK cities (such as Liverpool) where under-populated areas are again being cleared to be replaced with lower density housing under the Housing Market Renewal Initiative.)The urban regeneration approach is typified by Merseyside County Council whose strategy proposed to:“Concentrate investment and development within the urban county and particularly in those areas with the most acute problems, enhancing the environment and encouraging housing and economic expansion on derelict and disused sites. It would restrict development on the edge of the built-up areas to a minimum. There would bea reciprocal effort to enhance and conserve the natural features of the county’s openland and its agriculture while ensuring that its capacity to meet the county’s needs for leisure, recreation and informal education is exploited” (Merseyside County Council, 1975, p8, quoted in Couch, 2003).Such an approach was complemented by central government’s ‘Urban Programme’, which, since 1968 had been an instrument for subsidising public investment in inner urban areas, and the ‘Inner Areas Partnerships’ instigated under the Inner Urban Areas Act 1978. Although critical of the partnership idea, the incoming Conservative Government in 1979 maintained a commitment to urban regeneration that facilitated the re-use of vacant and derelict urban land by means of ‘Enterprise Zones’, ‘Urban Development Corporations’ and ‘Urban Development/City Grant’. This so-called ‘property-led’ approach to urban regeneration saw major successes in the redevelopment of urban land during the 1980s and early 1990s that undoubtedly contributed to a slackening in the rate of urban sprawl. Declining urban populations and a downturn in economic activity, especially in the north of England, also reduced demand for urban expansion.However, the Conservative Government had an ambivalent view of green belts and the release of land for housing development. Initially the government sought to reduce the effectiveness of green belts in order to facilitate more private housing development but so moves were opposed by an alliance of environmentalists and Conservative MPs whose constituencies might the be recipients of unwanted urban sprawl. In 1984 the government settled for housing circulars (9/80 Land for Private Housebuilding and 15/84 Land for Housing) that required local planning authorities to consult with housebuilders to ensure a five-year supply of developable land. This ‘predict and provide’ method of determining the amount of land to be zoned for housing inevitably had the effect of requiring constant additions to the amount of rural land zoned for future urbanisation on the periphery of cities: in other words the circulars encouraged urban sprawl.At this point it is worth noting some characteristics of the relationship between successive governments and the property development industry. It was developers who played a large part in encouraging the government to take seriously the problem of derelict urban land (the waste of a valuable resource). And it was private housebuilders who lobbied to maintain a steady supply of developable rural land. On the other hand, by the mid-1970s, with the exception of London, there was virtually no new private housing investment within existing urban areas of the major conurbations in England and the conventional wisdom of the time suggested that private investment could not be attracted because of a host of socio-economicand environmental factors. Liverpool City Council in 1975 took the unprecedented step of offering for sale housebuilding land in the inner city. They had one bidder: Wimpey, who, paying around £75 per building plot, successfully built and sold a development of more than 150 dwellings. Further developments followed. Also in Liverpool, Barretts successful converted and sold blocks of redundant council flats. Thus began what has now become commonplace: at the right price private developers proved themselves willing and able to invest heavily in the redevelopment and regeneration of inner urban areas.Virtually all British governments since the 1950s, especially those on the right, have been committed to the idea of a ‘property owning democracy’ within which encouraging home ownership (owner occupation) has been an important policy goal. The effect of this has been to increase owner occupation in Great Britain from 29% in 1951 to 70% in 2001. By the millennium more than 80% of all new housing was built speculatively for owner occupation. This has significant implications for the dynamics and control of urban sprawl. Virtually all control of urban sprawl involves the state intervening in the private market, hardly any investment is controlled through the direction of public investment. An essential feature of the private owner occupied housing market is the need to maintain, and preferably increase, property values. In these circumstances land with development potential is ever more valuable, the profits from development higher, and the pressure for development greater. It is this pressure that has to be controlled by the planning system if urban sprawl is to be brought under control.Through much of the 1980s the Thatcher Government pursued a neo-liberal ideology, viewing town and country planning as little more than an unnecessary impediment to private enterprise. However, towards the end of the decade their approach began to change. A combination of an emerging international concern for the environment (The Brundtland Commission had reported in 1987) and in 1988 the Department of the Environment introduced a series of Planning Policy Guidance Notes (PPGs) in order to clarify and strengthen the aims of aims of development plans across the country. An important driver of policy change at this time was the publication of This Common Inheritance (The Environment White Paper (Cabinet Office, 1990) which required a review of all planning policies in light of the conclusions of the Brundtland Report.One of the most important PPGs affecting urban sprawl was PPG3 ‘Housing’. First published in 1988 and slightly modified in 1992 this document pursued the ‘predict and provide’ approach in order to ensure ‘a continuous supply of housing land which addressed market demand’ although in a modest concession to the environmental lobby there was the ‘encouragement of local authorities to make optimum use of brownfield sites’. To be fair to the Government, by the mid-1990s they had stated another, parallel policy goal of increasing the amount of housing to be built on existing urban land, to over 50%.It was the ‘new’ Labour Government, elected in 1997 that moved away from the inevitability of ‘predict and provide’ to a more sophisticated approach to housing land allocations and release known as ‘plan, monitor and manage’. What this meant in practice was that a revised PPG3 ‘Housing’, in 2000, called for a ‘sequential’ approach to the release of housing land in which local authorities should ‘provide sufficient land, giving priority to re-using previously developed land within urban areas, bringing empty homes back into use and converting existing buildings, in preference to the development of Greenfield sites’ (Lowe H, 2003, p18). Figure 1 provides an indication of the growing effectiveness of planning and urban regeneration policies in controlling the sprawl of housing developments beyond existing urban areas. It shows the proportion of new dwellings built on previously developed land rising from around 55% in 1989 to over 60% in 2002.Figure 1. The proportion of new dwellings built on previously developed land.Another dimension of policy that is relevant to the control of urban sprawl is contained in PPG6 ‘Town Centres and Retailing’. Since 1996, PPG6 has required a sequential approach to commercial development whereby: ‘there should be a preference in the first instance for town centres, followed only then by edge-of-centre sites and out-of-centre schemes where these are well served by public transport’ (Mappin G & Allmendinger P, 2000, p194).Figure 2 shows how the growth of out-of-centre retail schemes have gradually been brought under stricter control in recent years.Figure102030405060199519961997199819992000Figure 2. Major Out of Centre Retail and Leisure Applications.A recent evaluation of PPG6 published by the ODPM found retailers and developers are tending to alter ‘their development strategies and store formats to keep them in line with PPG6….One of the clear effects of PPG6 has been to bring about an increase in the number of refusals of applications for out of town development’ (CB Hillier Parker, 2004, p10). It was also found that:“in the comparison retail sector, one of the most marked effects of PPG6 has been toeffectively bring to an end the supply of new regional shopping centres….In the retailwarehouse sector, the evidence suggests that the supply pipeline has fallen, and thereare examples of new edge-of-centre retail warehouse developments, which successfully combine the benefits of this format with a more central location…whilst…In the convenience sector…there is evidence of an increase in openings of town centre stores and neighbourhood stores, and a significant decline inthe pipeline of out-of-centre stores” (C B Hillier Parker, 2004, pp11-12).However, the same research also comments that whilst the policy guidance purports to cover all ‘key town centre uses’, there has been, in practice, a strong emphasis on the planning and control of retail developments, with ‘little or no useful guidance on leisure, offices and other town centre uses’ (ODPM, 2004, p8). The data indicates that the amount and proportion of out of town and out of centre leisure developments increased over the period 1994 – 2001 (ODPM, 2004, p63)A third element of policy guidance, PPG13 ‘Transport’ has sought to:o Promote choice (of mode of transport) by increasing the relative advantage of means of travel other than the car, especially walking, cycling and public transport;o Reducing dependence on the private car; ando Increasing the competitiveness and attractiveness of urban centres against peripheral development (Carr C & Docherty I, 2000, p220)However, it is in the field of transport policy that government policy has been least successful. The provision and quality of transport infrastructure has some causal relationship with urban sprawl. But whilst the laying down of suburban railways and tramways helped shape suburban growth in the late 19th and early 20th centuries, the more recent car-based suburbanisation process has needed no such investment. Instead, in more recent times, it is urban sprawl that has tended to dictate the location of peri-urban highway investment and to a lesser extent, the provision of public transport services. Indeed, the failure to provide adequate opportunities and support for walking, cycling and public transport in the UK, especially in areas of urban sprawl, has led to a continuing growth in the use of the motor vehicle for more and longer journeys, as shown in figure 3.Figure 3. Road Traffic Volumes.Whilst the aims of this policy guidance are laudable, it remains to be seen over time how effective they will be in achieving more sustainable patterns of urban development and reducing urban sprawl. One of the more intractable problems lies with the transport system. Whilst policies may call for a shift in modal split, decades of under-investment in provision for public transport, cycling and walking make significant changes in patterns of travel extremely difficult to achieve.Nevertheless, today, in 2004, the rate at which urban sprawl is occurring in Britain is lower than at almost any time over the last century. This has been achieved by a combination of socio-economic circumstances combined with strong planning controls at the urban fringe and effective subsidies and managerialist interventions to encourage the regeneration of older urban areas.The issue facing policy makers is whether these policies can remain effective into the future and whether they should be strengthened to reduce urban sprawl still further and encourage the type of compact urban development that the Government and the environmental lobby now favour.The FutureThe question now is how can policy be developed to further reduce urban sprawl and to reduce the adverse impacts of such sprawl? Beyond the trite ambitions for more ‘compact cities’, ‘decentralised concentration’, ‘greening the city’ and ‘reducing car-dependency’ there are difficult questions about the precise nature of the policies to be developed, their implementation, effectiveness, side-effects and political acceptability.The following discussion is structured around two issues:• How might urban sprawl be reduced, through policy changes at the national and local levels of planning?• How might the adverse social, economic and environmental consequences of urban sprawl be reduced?The evidence used in the discussion has been derived from:• the findings of the Liverpool/Wirral case studies about the causes and consequences of urban sprawl;• the conclusions of the URBS PANDENS ‘Stakeholder Workshop’ held in Vienna in January 2004.• policy debates in the planning literature;• a survey of expert opinion in North West England1.How might urban sprawl be reduced, through policy changes at the national and local levels of planning?Evidence from the Wirral case study.From our own earlier paper (Couch & Karecha 2003a), based on a study of trends in Wirral MBC, we noted a number of causal influences on urban sprawl, particularly in relation to residential locational choice.Changes in housing costs appeared to be a very significant influence. Firstly, particularly in the inner areas of Wirral and amongst younger householders, being in an area of affordable housing was a frequently cited influence on household locational choice. That is to say lower dwelling prices stimulated their demand. On the other hand, amongst movers to the outer areas of Wirral, ‘trading-up’ was the most frequently cited reason for moving. This would conform with the notion of owner occupied housing as an investment good and suggest that rising dwelling prices affected their locational choice and stimulated demand in the outer areas.Income levels appeared to be significant in that those likely to be on lower incomes (those not in employment and non-car owners) are more influenced in their location decisions by proximity to shopping facilities, railway stations and bus links: features that are more difficult to provide in sprawling locations. On the other hand those likely to be on higher incomes (professionals and managers and 2+ car owners) were slightly more influenced in their location decisions by quietude and proximity to countryside/coast: features more associated with sprawl.Infrastructure investment was an influence on some groups. Movers in all areas and especially the elderly frequently identified good road connections as a very important or crucial influence. The elderly were also frequently influenced by proximity to a railway station and being in an area of good bus services.Age structure clearly had important implications for urban sprawl. The elderly identified many more very important or crucial influences on household location decisions than younger age groups. Household structure was also important. The inner and outer areas exhibited quite different characteristics in terms of household types, with single adults, sharing adult households and single-parent families more represented amongst movers to the inner areas1 It was our intention to survey expert opinion using the Delphi technique. However, despite contacting a number of experts from the private and public sectors, the response rate in the first round of consultation was poor. We therefore modified the process and rather than have a series of successive rounds of consultation in order to move towards consensus on policy, we moved straight to the preparation of our own draft paper and invited expert comment through interviews and correspondence.and adult couples, two-parent families and the single elderly more represented amongst movers to the outer areas.The quality of the environment was an important influence on household location decisions. Being in a low crime neighbourhood and being in a quiet neighbourhood were amongst the most frequently cited influences on location decisions in all areas and across all age groups. In the outer areas and amongst the elderly, proximity to the countryside/coast was another very frequently cited environmental or landscape influence. On the other hand being near a park was of only limited influence on any group.However, within a labour market area, such as Wirral, neither a change in the place of work nor a desire for greater proximity between home and work seemed to be significant causes of household moves or choice of location.These findings suggest that any future policies intended to reduce residential urban sprawl need to:• Tackle perceived levels of crime and lack of quietude and environmental quality in existing urban neighbourhoods;• Improve the profitability to owner-occupiers of home ownership in existing urban neighbourhoods.• Deal with the issue of owner-occupied housing being an investment good and the perception that house prices increase faster in peripheral locations.Evidence from the ‘Stakeholder Workshop’.As part of the workshop activity around 30 stakeholders (expert professional planners and academics from the seven case study areas) were asked to rank 13 possible causes of urban sprawl in terms of their importance. Each individual stakeholder was limited to voting for a maximum of only 4 possible causes. The results are shown in table 1 below.Table 1. Stakeholder ranking of the importance of potential causes of urban sprawl.Causal factor Number of votes achievedPersonal lifestyle choices and behaviour 23Land use planning and property taxation22Dwelling prices and income changes 18Infrastructure investment 17Land speculation 11Economic change 6Inward investment 6Quality of landscape 4Demographic or household changes 4Social segregation 4Migration 1Lack of space in the inner city 1Quality of townscape 0Whilst the exercise might be criticised on a number of grounds (the definitions of some factors are ambiguous; the stakeholders were not randomly selected nor evenly representative of the case study areas), the results are nevertheless interesting.Overall there was an impressively high level of expert agreement about the major factors causing urban sprawl in a variety of different cities across Europe. Personal lifestyle choices and behaviour are perceived to be the most important cause. Coupled with the third mostimportant cause, dwelling prices and income changes, this clearly suggests that there is a strong demand-side dimension to the creation of urban sprawl. To this extent it may be argued that developers are merely responding to the desire of the population to live at certain densities; in certain types of environment; in certain locations; in affordable and, in the case of owner occupation, profitable dwellings.On the other hand there is also expert agreement that the planning system can encourage urban sprawl through land use zoning and providing infrastructure investments such as highways and utility services. Other important factors are thought to be local variations in property taxes and land speculation by potential developers.Thus responding to these arguments, governments wishing to control urban sprawl would need to:• Reduce household demand for urban sprawl, either by satisfying that demand in other locations or changing the nature of that demand;• Strengthen land-use zoning policies against urban sprawl, and/or strengthen the implementation of existing policies;• Re-orientate infrastructure investments away from areas of potential urban sprawl;• Reduce spatial differences in local property tax yields;• Limit the scope for land speculation at or near the urban fringe.Evidence from the survey of expert opinion in North West EnglandRespondents were asked to consider changes in planning policy that would reduce urban sprawl in North West England.At the national/regional scale of planning, the bulk of responses focused on the importance of brownfield development and development within existing urban areas, and the protection (and also the extension) of the greenbelt, as central aspects of policy responses/actions for the reduction of urban sprawl. It was also argued that there was scope for more effective implementation and enforcement of existing land use planning policies that were not being adhered to as strongly as they might be. Other responses discussed the merits of improving the quality of existing urban areas as a measure to stem the demand for and the attractiveness of ‘urban sprawl’ residential locations. There was also some discussion over whether environmental issues could be raised in terms of importance, over and above economic and social matters. One suggestion was that quality residential development could be channelled into land adjacent to rural settlements, with the view being that this could be preferable to sprawling suburbs. A further suggestion was that settlements could be categorised to form a hierarchical list starting with ‘the most preferred settlement for development’, moving to ‘the least preferred settlement’, ordered according to categories such as accessibility.At the metropolitan/city scale of planning, the discussion focused on the challenge of making cities attractive to people other than the young. There was some comment on having very clear and firm boundaries for urban areas set in local plans, and also having more precise and directive details for example on matters such as site capacities. A suggestion was made that by a better integration of (public) transport planning and land use planning, that urban sprawl could be reduced.At the local/neighbourhood scale of planning, there was some debate as to whether urban sprawl could be addressed at this level with some participants believing that it was not possible. Among the suggestions among those who did answer, was the view that the promotion of mixed communities might form part of the solution for reducing urban sprawl, presumably because it was felt that this could create places where the more affluent would。

全自动运行系统控制中心与备用控制中心切换方案

DOI: 10.3969/j.issn.1673-4440.2023.08.0015全自动运行系统控制中心与备用控制中心切换方案薛强, 张永会（卡斯柯信号有限公司，上海 200071）摘要：城市轨道交通全自动运行系统专业性强、技术设备复杂、时效性强，在极端灾害发生时，控制中心有可能陷入瘫痪状态，导致控制中心各专业系统无法完成正常的功能，进而影响城市轨道交通的正常运营。

备用控制中心为城市轨道交通全自动运行系统的必备配置，系统整体的可用性和安全性在备用控制中心加持下有较大改善。

结合信号系统、通信系统、综合监控系统主备控制中心系统内部冗余切换机制、设备典型配置、系统接口切换影响及切换场景，在此基础上给出主备控制中心切换设计方案的优劣势比较，为城市轨道交通全自动运行系统建设中主备控制中心系统切换设计提供借鉴和指导。

关键词：城市轨道交通；全自动运行；信号系统；通信系统；综合监控系统；控制中心；备用控制中心中图分类号：U239.5 文献标志码：A 文章编号：1673-4440(2023)08-0078-05Switching Scheme of OCC and BOCC in Fully Automatic OperationXue Qiang, Zhang Yonghui(CASCO Signal Ltd., Shanghai 200071, China)Abstract: Fully automatic operation system has the characteristics of strong professionalism, complex technical equipment and strong timeliness in urban rail transit. However, operating control center (OCC) may become paralyzed in times of extreme disasters, resulting in the failure of all professional systems to complete normal functions, thus affecting the normal operation of urban rail transit.The backup operational control center (BOCC) is deﬁ ned as the essential conﬁ guration of the fully automatic operation system of urban rail transit, and the overall availability and safety of system are greatly improved with the addition of BOCC. This paper analyzes the internal redundant switching mechanism, the typical configuration of the equipment, and the impact of switching between the interfaces of the core professional system and the switching scenarios of the core system of OCC and BOCC of signal systems, data communication system and integrated supervision and control systems.Based on the above description and the comparison of the advantages and disadvantages of switching收稿日期：2023-02-21；修回日期：2023-08-09第一作者：薛强（1986—），男，高级工程师，本科，主要研究方向：城市轨道交通信号系统，邮箱：******************.cn。

地铁站疏散Modeling the pedestrian’s movement and simulating evacuation

Modeling the pedestrian’s movement and simulating evacuation dynamics onstairsYunchao Qu,Ziyou Gao ⇑,Yao Xiao,Xingang LiSchool of Trafﬁc and Transportation,Beijing Jiaotong University,Beijing 100044,Chinaa r t i c l e i n f o Article history:Received 23December 2013Received in revised form 15May 2014Accepted 22May 2014Available online 26June 2014Keywords:Pedestrian ﬂowStaircase movement Dynamic characteristics Social force modela b s t r a c tThis paper presents an enhanced social force model to describe the pedestrian’s movement and evacua-tion dynamics on pared with original models that described the pedestrian’s planar motion,our model introduces some mechanisms of the staircase movement,such as the inﬂuence of staircase geometry,the restriction of the step size and the optimal velocity selection.The body shape of each pedestrian is regarded as a set of three circles to precisely quantify the movement.In addition,the rotation dynamics are included into the model to describe the congestion effect.The improved model can obtain individual velocity under different staircase geometries and the ﬂow characteristics of the evacuation dynamics.Some empirical data and a series of observations captured in two subway stations in Beijing are applied to study the characteristics and further validate the model.The results show that our model performs well consistent with the observed data.At last,simulations are implemented to ﬁnd the solutions of estimating the evacuation time and evaluating the capacity of stair.Ó2014Elsevier Ltd.All rights reserved.1.IntroductionStairs are widely used in all kinds of buildings,especially in large scale public places,i.e.,subway stations,shopping malls and ofﬁce buildings.Walking on stairs is very common and important in our daily lives,and scientiﬁc design and effective utilization of stairs are urgently needed for designers and managers (Peacock et al.,2009).In emergency,such as power failure,ﬁre,earthquake or other hazards,the elevators may be out of commission,and the stairs become the primary escape routes.If there are too many peo-ple crowded on stairs,they will pack closer together or even lead to some dangerous situations (Shields and Boyce,2009).Knowing the ﬂow characteristics and predicting the egress time are the key points to grasp the evacuation dynamics and make emergency response plans on stairs (Graat et al.,1999;Oven and Cakici,2009).The characteristics of pedestrian staircase movement are deter-mined by organizational,constructional and behavioral factors:the organizational factors,i.e.,preparation for emergencies;the constructional factors,i.e.,the staircase geometry including riser height,tread depth and step width (Graat et al.,1999;Fujiyama and Tyler,2010);the behavioral factors,i.e.,responses and move-ment characteristics of pedestrians (Yang et al.,2012;Ma et al.,2012).The study of the staircase movement is an interdisciplinaryﬁeld with different focuses,such as biomechanics,physics,physiol-ogy,phycology,computer science,safety science (i.e.,Hankin and Wright,1958;Fruin,1971;Predtechenskii and Milinskii,1978;Templer,1992;Batty,1997;Helbing et al.,2000;Hase and Yamazaki,2002;Nelson et al.,2002;Hoskin,2004;Pauls,2005;Trew,2005;Casburn et al.,2007;Hostikka et al.,2007;Galea et al.,2008;Kretz et al.,2008;Seer,2008;Xu and Song,2009;Fujiyama and Tyler,2010;Galea et al.,2010;Hoskins,2011;Halsey et al.,2012;Yang et al.,2012;Peacock et al.,2012;Burghardt et al.,2013).To make quantitative analyses and detailed descriptions of staircase movement,many researches have carried out a lot of sur-veys,experiments and evacuation drills on stairs,and have collected large amounts of experimental and observational data of staircase movement (please see Table 1for details).In these studies,the ﬂow characteristics of staircase movement are described in individual level and collective level.Pedestrian ﬂow in low densities reﬂects the characteristics in the individual level,and walking speed is inﬂu-enced by physiological feature and body function,such as gender,age,height,weight,heart rate,rate of oxygen consumption and rate of energy expenditure (Irvine et al.,1990;Teh and Aziz,2002;Halsey et al.,2012).It is also inﬂuenced by stairway geometries and movement direction.Pedestrian ﬂow in high densities reﬂects the characteristics in the collective level.The collective behaviors include pedestrians’self-organized behaviors and optimal route choice behaviors (i.e.,Helbing et al.,2000,2005;Moussaid et al.,2011).The researches of pedestrian ﬂow in the collective level focus on three aspects,(1)evaluating evacuation time,(2)reproducing/10.1016/j.ssci.2014.05.0160925-7535/Ó2014Elsevier Ltd.All rights reserved.⇑Corresponding author.Tel.:+861051688193.E-mail address:zygao@ (Z.Gao).fundamental diagram,and(3)describingﬂow characteristics,i.e., inﬂow,outﬂow,capacity.Staircase movement is a complicated three-dimensional move-ment,and modeling the movement is a quite challenging work. Nowadays,researches have integrated behavioral and construc-tional factors,and have established many models to analyze the ﬂow characteristics and simulate evacuation processes in both sin-gle-story and multi-story buildings(Table1).In our work,we mainly focus on the case of single-story staircases.These models are classiﬁed into two categories:macroscopic model and micro-scopic model(Zheng et al.,2009).The macroscopic models regard the crowd as a single entity,and focus onﬁtting the expression of fundamental diagram.Linear,piecewise linear and non-linear functions(i.e.,Fruin,1971;Warren,1984;Tanaboriboon et al., 1986;Weidmann,1993;Lam and Cheung,2000;Proulx,2002; Peacock et al.,2012;Hoskins and Milke,2012)have been applied to describe relationship between velocity and density under differ-ent stair geometries.Compared with macroscopic models,the microscopic models are able to precisely describe the individual behavior,qualitatively explain the evacuation dynamics and reproduce some self-orga-nized phenomena(Helbing et al.,2000).These microscopic models are spatial-discrete models(cellular automation model,i.e., Kirchner et al.,2004;Huang and Guo,2008;Schadschneider and Seyfried,2009)and spatial-continuous models(social force model, i.e.,Helbing et al.,2000).These models have been applied to reveal two-dimensional planar movement,but few of them have described the three-dimensional staircase movement(Song et al., 2006;Pelechano and Malkawi,2008;Xu and Song,2009;Ma et al.,2012).In addition,the spatial-discrete models are some restricted to describe the staircase movement,such as grid size,fatigue factor,route selection,and uneven use of stairs (Pelechano and Malkawi,2008).Although the spatial-continuous models are advantageous to solve most of the aforementioned problems,these models are quite rare.Social force model(Helbing and Molnar,1995)is a well-known spatial-continuous model in theﬁeld of pedestrianﬂow.The model can reproduce several self-organized phenomena,such as lane forming,arching queue,shock waves and clogging effects (Helbing et al.,2005,2007).Moussaid et al.(2011)have proposed a heuristics-based model to replace the social force with a heuris-tics intelligent optimum function.Based on the heuristic social force model,this paper introduced some special rules and estab-lished an enhanced model to describe the mechanisms of pedes-trian movement and evacuation dynamics on stairs.Firstly,the body shape of each pedestrian is regarded as a set of three circles (Thompson and Marchant,1995).Compared with traditional sin-gle-circle shape(i.e.,Helbing et al.,2000),the three-circle shape precisely represents the projection of human body and describes the rotation movement when two pedestrians collide with others. Secondly,pedestrians usually walk more carefully on stairs than on planar,so two‘safety rules’are proposed to describe staircase movement behavior.Theﬁrst rule is that a pedestrian wants to walk upstairs/downstairs with integral steps at a time,and the step-size is restricted by the staircase geometry,such as tread depth,riser height and step width.The second rule is that a pedes-trian tends to walk along the sides,i.e.,holding handrails,propping up against walls.Thirdly,the relaxation time is extended to a var-iable in our model.The relaxation time is deﬁned that a pedestrian tends to correspondingly adapt his/her actual velocity to desired velocity with a certain characteristic time s(i.e.,Helbing et al., 2000;Moussaid et al.,2011).The relaxation time is mostlyTable1The state-of-the-art of staircase movement.Author(s)Year Method Model EvacuationprocessWalking speed NoteDynamics FD Geometry Direction Hankin and Wright1958Data analysis–s d s d–Fruin1971Data analysis–s d s s Planning methodPredtechenskii and Milinskii1978Data analysis Planning model s d s s Planning methodTanaboriboon et al.1986Macro Linear function s d s s Fundamental diagram Weidmann1993Macro Non-linear function s d d d–Frantzich1996Data analysis–s d d d–Graat et al.1999Data analysis–s d s s Capacity estimation Lam and Cheung2000Macro BPR function s d d d Fundamental diagram,capacityestimation Proulx et al.2002Data analysis Non-linear function d d s s SFPENelson and Mowrer2002Data analysis Non-linear function d d s s SFPEHoskin2004Softwaresimulation Coordinate-basedmodeld d d d Simulex32Pauls2005Data analysis–d s s s–Hostikka et al.2007Data analysis–d d s s–Kretz et al.2008Data analysis–s d d d Pedestrian movement on long stairs Seer et al.2008Data analysis–d d s s Flow characteristicsPelechano and Malkawi2008SoftwaresimulationGrid based model d s s s Literature review(STEPS,EXODUS)Galea et al.2008Software Evacuation model d s s s Merging behavior at interactions Xu and Song2009Micro Multi-grid model d s s s Flow characteristics,such as in and outﬂow Fujiyama and Tyler2010Macro Linear function s s d d Individual walking speed Galea et al.2010Data analysis–d d s s Evacuation softwareHoskins2011Macro Linear function d d d d Fundamental diagramYang et al.2012Data analysis–d d d s Evacuation drillLei et al.2012Softwaresimulation–d s s s Software(FDS,EVAC) Hoskins and Milke2012Data analysis–s d s s NISTPeacock2012Data analysis–d d d s NIST,different measurement methods Ma et al.2012Data analysis CA d s s s SimulationBurghardt et al.2013Data analysis–s d s s Fundamental diagramd Represents the factor is included and s represents the factor is not included.190Y.Qu et al./Safety Science70(2014)189–201assumed to be a constant in previous models,but it is not inade-quate to describe the staircase movement.As mentioned before, the individual walking speed on stairs is inﬂuenced by many fac-tors,such as staircase size,movement direction,and physical char-acteristics.For example,pedestrians spend more energy on walking upstairs than downstairs,spend more time on walking steep stairs than gentle stairs.Pedestrians with different age, weight or gender may require different relaxation times when walking on different stairs.Considering the inﬂuence factors,the relaxation time is formulated as a linear function of individual weight,moving height,and the slope of stairs.The linear function is similar to the model(Fujiyama and Tyler,2010),and some parameters are introduced to distinguish the upstairs and down-stairs movement.In this paper,some empirical data in literatures are collected and new observations from subway stations are conducted.In Sec-tion2,the characteristics of pedestrianﬂow on the stairs are dis-cussed.Based on the data and analysis,the constructional and behavioral factors are introduced to the social force model to pre-cisely describe the individual staircase moment in Section3.To validate the model,a series of simulations are implemented,and the simulation results are compared with the observational and empirical data in Section4.Simulations are implemented to ana-lyze theﬂow characteristics and the evacuation process in subway stations in Section5.Finally,the conclusions and the further work are given in Section6.2.Data collection andﬂow characteristics on stairs2.1.Empirical data of pedestrian speedOccupant speed is a very important element of pedestrianﬂow, and pedestrian speed on stairs is mainly affected by the slope of stairway,depth of tread,height of riser,and presence and location of handrails(Gwynne et al.,2009).Graat et al.(1999)had found that speed and capacity on stairs were higher with a normal (30°)slope than a steep(38°)slope.Kretz et al.(2008)had found that some pedestrian accelerate when walking upward a short stairway,and the mean upward walking speed on the short stair-way was found to be roughly twice as large as the one on the long stairway.Fujiyama and Tyler(2010)had proposed a model to pre-dict the walking speed based on the weight,leg power and the gra-dient of the stairs.The evacuation process of a large number of people is another major concern for researchers and designers. During the evacuation,the evacuation process something likes a queuing system that contains the processes of congestion forming, propagation and dissipation(Ma et al.,2012).Besides,the stair width and capacity will affect the route/exit choice behaviors and the evacuation efﬁciency(Lei et al.,2012).Researches have obtained many observational and experimen-tal data of staircase movement.However,this study here is not intended to be an exhaustive review of all researches.The refer-ences which mentioned both staircase geometry and individual speed are taken into consideration.Ten instances of staircase are included in our paper,and more detailed data can be found in the literatures(i.e.,Weidmann,1993;Frantzich,1996;Fujiyama and Tyler,2010;Hoskins,2011;Peacock et al.,2012).From Table2, it is found that walking speeds listed in the studies are different. This may be caused by natural variation of individual capability, staircase geometry,density of crowd and other factors.Besides, different measurement methods of calculating travel distances and areas on stairs may lead to different results(Hoskins and Milke,2012).Fujiyama and Tyler(2010)have made some experi-ments and found that average upstairs and downstairs speeds were0.58m/s and0.67m/s,respectively.Peacock et al.(2012) have mentioned that average downstairs speeds in their study of 0.48±0.16m/s were observed to be quite similar to the range of literature values.Kretz et al.(2008)have pointed that the density also affected the individual speed.Ma et al.(2012)have made a series of evacuation drills to obtain the average downstairs speed of0.547m/s.Even though different researchers have come up with different values for movement on stairs,most give a maximum for density of4.5–5.5pedestrians/m2,a maximum for speed of0.7–1.2m/s,and maximum for capacity of0.8–1.5pedestrians/(m s).2.2.Observations in subway stationsSomeﬁre drill evacuations of ofﬁce buildings have been imple-mented by National Institute of Standards and Technology(NIST), and the collected staircase movement data have included a range of stair geometries and occupant densities(Peacock et al.,2012; Hoskins and Milke,2012).However,in those studies,the local speed and the density were inaccurately estimated according to the collected data.It was because the cameras did not fully record the whole of staircase movement.In the drills,cameras were set every twoﬂoors to record an overhead view of occupant move-ment.The view of each camera only covered the main landing area plus tread depth area for about4–6steps of one story.Between every two cameras,there was a mid-landing,where pedestrian movement was a planar movement,but not a staircase movement. It was impossible to dissociate the planar movement on mid-land-ing from the video,so the calculations of the travel distance and travel time of staircase movement were inaccurate.To precisely investigate the pedestrian movement characteristics on stairs,we improved the method of video recording,and conducted observa-tions of whole staircase movement in two stations of Beijing sub-way Line1.The two stations are Sihui East Station(ascendingﬂow)and Xidan Station(descendingﬂow).The Sihui East Station is a termi-nal station and all the passengers should get off the train and go to the transfer hall;therefore,the pedestrianﬂow on the observed stair is an ascendingﬂow.The Xidan Station is also a transferTable2Individual horizontal speeds in ten instances of staircases with different geometries.ID Riser height(mm)Tread depth(mm)Gradient(°)Horizontal speed(m/s)Source Note#H120021043.60.361("),0.509(;)a Frantzich(1996)Narrow stair #H215030519.00.427("),0.601(;)Lam(2000)MTR #H316327131.00.417("),0.569(;)Lam(2000)KCR #H419027035.10.423(")Kretz(2008)Long stairs #H515029027.30.538("),0.581(;)Fujiyama(2010)Elder people #H615726730.50.590("),0.721(;)Fujiyama(2010)Young people #H718623838.00.488(;)a Peacock(2012)11-Floors #H819125436.90.440(;)a Peacock(2012)18-Floors #H915028028.20.547(;)Ma(2012)SWFC #H1014028026.50.53(;)Yang(2012)Stair No.2#a The speeds were converted to horizontal speeds.Y.Qu et al./Safety Science70(2014)189–201191station and the passengers can get on or off the train by the stair, and there is an escalator on one side of the stair to relieve the coun-tering passengerﬂows.Therefore,the pedestrianﬂow is a descend-ingﬂow.The schematic diagram of the observation stations is shown in Fig.1,and the information of the stairs is shown in Table3.A HD camera was set on the transfer hall to record the trail of each passenger.The observations in the subway stations were made during the afternoon rush hours of weekend(17:30–18:30,Sunday)on May 12,2013.In our observations,383pedestrians(216males,167 females)were collected at the selected staircases in Xidan Station, and221pedestrians(129males,92females)were collected in Sihui East Station.Most of the pedestrians were young and mid-dle-aged people,and their ages mostly ranged from25to55years old.The proportion of children and elderly was very low.In our observations,most of the pedestrians carried light bags and walked in a normal speed on staircases.Because the camera was not right above on the observed region, the passengers were sometimes overlapped in the video.Each pedestrian was recorded by individual characteristics,such as gen-der,age,body size,hair,shirt and pants.Then,the pedestrians were recognized by their features,entering and leaving time.The speed of each pedestrian was calculated by the travel time(leaving time minus entering time)dividing the travel distance on the stairs.The video recordings were processed semi-manually,and the dynamic evacuation characteristics,such as average density,speed andﬂow,were analyzed.Take Xidan station for example,the evac-uation dynamic characteristics and a snapshot were illustrated in Fig.2a–c).It was found that the curve of time-varying density was divided into several segments,and each segment represented a stream of pedestrians entering and leaving the stairs.During the observation,some measures,such asﬂow restriction and guidance, had been adopted to avoid crowdedness,so the density of pedestri-ans on stairs was in a normal(low)level.There were eight local maximum points exceeding1.0pedestrians/m2,and the maximal density was about1.6(1/m2).Velocity showed an opposite trend of density.The velocityﬂuc-tuated between0.4m/s and1.0m/s,and the average velocity was about0.57m/s.The volatility of individual velocities might be caused by different individual capability and desired velocity.In a low density,the pedestrians who walked fast would overtake front pedestrians who walked slowly and blocked them.When the density became larger,the pedestrians began to slow down and follow with others,and then queues might form on stairs.In Fig.2d),the acquainted or familiar people might walk abreast, which is regarded as‘subgroup behavior’(Yang et al.,2012).If they walked slower than the surrounding people,they would form a dynamic bottleneck.Additionally,lane-forming phenomenon was also found.In Fig.3a),the distributions of the speeds during the observa-tions followed normal distributions,which were similar with the reference(Peacock et al.,2012).The average velocities of walking upstairs and downstairs were0.55m/s and0.63m/s,respectively. Affected by gravity,going upstairs was slower than going down-stairs.By gathering the observed data of unidirectionalﬂow,the relationships between the velocity and the density were shown in Fig.3(b).The velocity decreased as the density increased.It should be noted that,in a low density,the velocity of going upstairs was a little higher than downstairs.It was because some of the pedestrians were hurried out of station and ran more than one steps at one time.3.Modeling the pedestrian’s movement on stairs3.1.Body shapesIn the existing models,the projection of a pedestrian’s body shape is usually regarded as a square(i.e.,Kirchner et al.,2004), a rectangular(i.e.,Song et al.,2006;Weng et al.,2007),a circle (i.e.,Helbing et al.,2000),an ellipse(i.e.,Chraibi et al.,2010)or a set of three circles(Thompson and Marchant,1995).In these geo-metrical shapes,the three-circle shape has some geometrical and computational advantages on modeling the staircase movement. First of all,the three-circle shape is a better alternative to describe the pedestrian’s body shape.It is because the occupied space of one pedestrian is restricted by the stairs,and the shoulder width of the pedestrian is larger than lateral width(Xu and Song,2009).In addi-tion,a pedestrian walks with a relative slow speed on stairs,and his/her space requirement keeps almost constant.Secondly,in social force model,the distance of closest approach of two pedes-trians is a key parameter when calculating the self-driven force, the repulsive force and the contact force.The closet distance between two single-circle or three-circle shapes can be easily cal-culated(Thompson and Marchant,1995);however,the calculation of the closest distance of two ellipses is surprisingly difﬁcult (Zheng and Palffy-Muhoray,2007).For the convenience of calcula-tion,the three-circle shape is a better alternative than ellipse shape.Therefore,the three-circle shape is chosen to describe pedestrian’s body shape,and the schematic diagram is shown in Fig.4.3.2.Modiﬁed social force modelThe well-known social force model(Helbing and Molnar,1995; Helbing et al.,2000)is a microscopic force-based model that can reproduce several self-organized phenomena,such as lane form-ing,arching queue,shock waves and clogging effects(Helbing et al.,2005,2007;Moussaid et al.,2011).The model describes pedestrians’movement behavior by introducing the self-driven force~f Di,the contact force with pedestrians~f Cijand walls(obstacles) ~f Ciw.The self-driven force can be calculated by Eq.(1),and the total force~f exerted on pedestrian i can be formulated as Eq.(2).192Y.Qu et al./Safety Science70(2014)189–201~f D i ¼m ~m desiÀ~m isð1Þ~f i ¼~f D i þXj~f C ij þXw~f C iwð2ÞMoussaid et al.(2011)have proposed a heuristics-based modelto replace the social force with a heuristics intelligent optimum function,which can be regarded as a so-called collision prediction process.The model can overcome some difﬁculties in the original versions.Based on the model,we use the three-circle shape,intro-duce some special rules and establish an enhanced model todescribe the staircase movement.In our model,the modiﬁcations are concentrated on the calculations of optimal direction selection,self-driven force and contact force.3.2.1.Selecting optimal direction In Eq.(1),the desired velocity ~m des i can be obtained by the mag-nitude m des i multiplies by the direction ~e des iof desired velocity.The calculation of ~e desi is called ‘optimal direction selection’,which isTable 3Detailed step sizes.ID StationStep number Width (mm)Depth (mm)Height (mm)Gradient (°)Flow direction#O1Xidan Station 16240030014025.0Descending ﬂow #O2Sihui East Station15190033015726.1Ascending ﬂow(b) Change of pedestrian density with time inthe observation of staircase #O1(c) Change of pedestrian speed with time inthe observation of staircase #O1(d) A snapshot of the observations in staircase #O2(a) Change of pedestrian flow with time inthe observation of staircase #O1 Fig.2.Processed data and a snapshot.Y.Qu et al./Safety Science 70(2014)189–201193an important component of the model(Moussaid et al.,2011).In our work,the body shape is extended to three-circle shape,and the calculation becomes a little complex.To make a clear state-ment,some notation and deﬁnitions are given as follow:for pedes-trian i,the large circle’s radius is r i1,the small circle’s radius is r i2, the mass is M i,the maximum velocity is v0i,the location is~l i,the velocity is~m i and the desired destination is~D i.Assume that pedestrian i moves at the velocity v0i along the direction of direction a,and will contact with pedestrian j after D t time.The i0and j0represent the locations of i and j at time t+D t.Then,fðaÞ¼v0iÁD t is the distance to theﬁrst collision with other pedestrian or obstacle in the direction a.If no collision is expected to occur,f(a)is set to a default value d max,which repre-sents the‘maximum horizon distance’of pedestrian i.The calcula-tion of furthest distance without collision f(a)can be improved as follows:l ixm ðtþD tÞ¼l ixmðtÞþv ix D t;l iy mðtþD tÞ¼l iy mðtÞþv iy D tðm;n2f1;2;3gÞl jxn ðtþD tÞ¼l jxnðtÞþv jx D t;l jy nðtþD tÞ¼l jy nðtÞþv jy D tðl ixm ðtþD tÞÀl jxnðtþD tÞÞ2þðl iymðtþD tÞÀl jynðtþD tÞÞ2¼ðr imþr jnÞ2ð3ÞPut theﬁrst two items into the third item,we can get a qua-dratic equation with moving time D t.Given the locations and velocities of pedestrians i and j,the D t can be easily solved.Then, the value fða i m j nÞand dðaÞcan be calculated asfða i m j nÞ¼min f v i Deltat;d max g;fðaÞ¼min f fða i m j nÞg;aÃ¼argmin f dðaÞg dðaÞ¼d2maxþfðaÞÀ2d max fðaÞcosða0ÀaÞð4ÞThe optimal velocity direction~e¼ðcos aÃ;sin aÃÞ;here,aÃ¼argmin f dðaÞg is the optimal direction.Fig.5illustrates the calculation.3.2.2.Self-driven forces and contact forcesThe pedestrian’s staircase movement is a three-dimensional motion,which contains horizontal and vertical motion.Pedestrian should change his/her center of gravity to ascend or descend the stairs,which are shown in Fig.6(a)and(b).The complicated move-ment includes the pedestrian’s physiological activity and energy transformation.In our work,we mainly focus on the pedestrians’horizontal optimal choice and crowding behaviors,so the vertical motion is approximately regarded as a linear motion,which is shown in Fig.6(c).In horizontal motion,pedestrians not only over-take front people with slower speeds but also have to notice the steps and prevent themselves from falling down from stairs.To mathematically depict horizontal movement,some assumptions and rules are introduced to simplify the movement,which is illus-trated in Fig.6(d).Theﬁrst assumption is that a pedestrian wants to move forward within n steps(n is integer).And the pedestrian’s desired destina-tion of next footstep is the center of the forward step.For example, in Fig.6d),pedestrian often moves forward with integer steps,i.e., one step(point A)or two steps(point B).When he/she moves for-ward with non-integer step,i.e.,2.5steps(point C),he/she will move to the edge of the step,and may feel unstable,unsafe or even fall down from the stairs.Therefore,point C is not considered in our model.The pedestrian’s horizontal footstep length is deﬁned as d h¼nDcos b,and is restricted by the tread depths D and riser heights H of the step.Here,b is the included angle between the optimal direction aÃand the x-coordinate.If the pedestrian is obstructed by other pedestrians or obstacles,he/she will slow down and avoid collision,and the footstep length does not exceed the maximal dis-tance fðaÃÞ(Eq.(4))in the optimal direction aÃ.Finally,the footstep length is expressed as:d h¼minnDcos b;fðaÃÞ&'ð5ÞAccording to the model(Moussaid et al.,2011),a pedestrian maintains a distance from theﬁrst obstacle in the chosen walking direction that ensures a time to collision of at least a relaxation time s.In other words,desired velocity of pedestrian i is formu-lated as v des i¼d h s.Additionally,pedestrian’s speed is assumed to not exceed a maximum velocity v max.Then,the horizontal maxi-mum velocity is v max cos h,and the angle h represents the slope of the stair tan h¼HÀÁ.The horizontal desired velocity v des i can be formulated as Eq.(6):v desi¼mind hs;vmaxcos hð6Þ(a) Probability distribution(b) Fundamental diagramFig.3.Speed and fundamental diagram of theobservations.194Y.Qu et al./Safety Science70(2014)189–201。

化学英语考试题及答案

化学英语考试题及答案一、选择题（每题2分，共20分）1. What is the chemical symbol for oxygen?A. OB. OHC. H2OD. O22. Which of the following is not a basic unit of a chemical element?A. AtomB. MoleculeC. ProtonD. Electron3. What is the law of conservation of mass?A. Mass is neither created nor destroyed in a chemical reaction.B. Mass is always created in a chemical reaction.C. Mass is always destroyed in a chemical reaction.D. None of the above.4. What is the correct chemical formula for water?A. H2OB. H2O2C. O2HD. OH-5. Which of the following is a noble gas?A. Oxygen (O)B. Helium (He)C. Carbon (C)D. Nitrogen (N)6. What is the valency of hydrogen in the compound HCl?A. +1B. -1C. +2D. -27. Which of the following is a compound?A. Oxygen gas (O2)B. Carbon dioxide (CO2)C. Hydrogen gas (H2)D. Nitrogen gas (N2)8. What is the common name for the chemical NaCl?A. SodiumB. ChlorineC. Table saltD. Baking soda9. What is the atomic number of carbon?A. 6B. 16C. 12D. 810. What is the process of a substance changing from a solidto a liquid state called?A. SublimationB. VaporizationC. MeltingD. Condensation二、填空题（每空1分，共10分）11. The chemical equation for the combustion of methane is__________.Answer: CH4 + 2O2 → CO2 + 2H2O12. The symbol for the element with atomic number 17 is__________.Answer: Cl13. The process of a substance changing from a liquid to agas is known as __________.Answer: Vaporization14. The chemical formula for calcium carbonate is __________. Answer: CaCO315. The valency of chlorine in the compound KCl is __________. Answer: -116. The noble gas that is used in balloons is __________.Answer: Helium (He)17. The atomic number of oxygen is __________.Answer: 818. The process of a substance changing from a gas to aliquid is known as __________.Answer: Condensation19. The chemical symbol for the element with the highest atomic mass is __________.Answer: Og (Oganesson)20. The law that states the total mass of the reactants equals the total mass of the products in a chemical reaction is known as the __________.Answer: Law of Conservation of Mass三、简答题（每题5分，共20分）21. Explain the difference between a pure substance and a mixture.Answer: A pure substance consists of a single type of particle, while a mixture is composed of two or moredifferent substances that are not chemically combined.22. What is an acid and what are its properties?Answer: An acid is a substance that donates hydrogen ions (H+) when dissolved in water. Properties of acids include a sour taste, the ability to change the color of certain indicators, and the ability to react with bases to form salts and water.23. Describe the process of photosynthesis.Answer: Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigments. It involves theconversion of carbon dioxide and water into glucose and oxygen in the presence of light energy.24. What is a chemical equilibrium and how is it represented? Answer: Chemical equilibrium is the state in a reversible reaction where the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in the concentrations of reactants and products. It is represented by the equilibrium constant expression, Kc, which is the ratio of the concentrations of products to reactants raised to their respective stoichiometric coefficients.四、计算题（每题5分，共10分）25. If 10 grams of sodium bicarbonate (NaHCO3) are dissolved in water and reacted with an excess of hydrochloric acid (HCl), calculate the volume。

齿轨列车齿轨轮轨切换车载ATP控制研究

齿轨列车齿轨轮轨切换车载ATP控制研究刘浚锋1，2，蒋彪3，王成1，2（1．北京全路通信信号研究设计院集团有限公司，北京 100070；2．北京市高速铁路运行控制系统工程技术研究中心，北京 100070；3．湖南轨道交通控股集团有限公司，长沙 410000）摘要：介绍山地齿轨列车的特点以及在国内起步的状况，分析信号系统在齿轨列车安全控制的特殊性。

着重对山地齿轨列车“入齿”和“出齿”过程中信号系统的控制策略进行描述，并对齿轨列车在齿轨区和轮轨区进行切换运营时信号系统安全防护曲线的计算进行分析和论述，提出停车切换和动态切换的方法。

关键词：齿轮列车；入齿控制；出齿控制；ATP曲线计算中图分类号：U284.48 文献标志码：A 文章编号：1673-4440(2023)08-0072-06Research on On-board ATP Control ofGear Rail and Wheel Rail Switching of Rack Railway TrainsLiu Junfeng1, 2, Jiang Biao3, Wang Cheng1, 2(1. CRSC Research & Design Institute Group Co., Ltd., Beijing 100070, China)(2. Beijing Engineering Technology Research Center of Operation Control Systems for High Speed Railways, Beijing 100070, China)(3. Hunan Rail Transit Holding Group Co., Ltd., Changsha 410000, China)Abstract: This paper introduces the characteristics of mountain rack railway trains and their starting status in China. The particularities of the signal system in the safety control of the rack railway trains are analyzed.The control strategy of the signal system in the process of "gear in" and "gear out" of the mountain rack railway trains is described emphatically. It also analyzes and discusses the calculation of safety protection curves of signal system when a rack railway train switches between the gear rail area and the wheel rail area. The methods of stationary-train switching and dynamic switching are proposed.Keywords: rack railway train; "gear in" control; "gear out" control; A TP curve calculationDOI: 10.3969/j.issn.1673-4440.2023.08.014收稿日期：2022-08-29；修回日期：2023-06-13基金项目：北京全路通信信号研究设计院集团有限公司科研项目（2300-K1200045.03）第一作者：刘浚锋（1976—），男，工程师，硕士，主要研究方向：城市轨道交通信号系统控制，邮箱：liujunfeng@ 。

Glider Flying Handbook说明书

Glider Flying Handbook2013U.S. Department of TransportationFEDERAL AVIATION ADMINISTRATIONFlight Standards Servicei iPrefaceThe Glider Flying Handbook is designed as a technical manual for applicants who are preparing for glider category rating and for currently certificated glider pilots who wish to improve their knowledge. Certificated flight instructors will find this handbook a valuable training aid, since detailed coverage of aeronautical decision-making, components and systems, aerodynamics, flight instruments, performance limitations, ground operations, flight maneuvers, traffic patterns, emergencies, soaring weather, soaring techniques, and cross-country flight is included. Topics such as radio navigation and communication, use of flight information publications, and regulations are available in other Federal Aviation Administration (FAA) publications.The discussion and explanations reflect the most commonly used practices and principles. Occasionally, the word “must” or similar language is used where the desired action is deemed critical. The use of such language is not intended to add to, interpret, or relieve a duty imposed by Title 14 of the Code of Federal Regulations (14 CFR). Persons working towards a glider rating are advised to review the references from the applicable practical test standards (FAA-G-8082-4, Sport Pilot and Flight Instructor with a Sport Pilot Rating Knowledge Test Guide, FAA-G-8082-5, Commercial Pilot Knowledge Test Guide, and FAA-G-8082-17, Recreational Pilot and Private Pilot Knowledge Test Guide). Resources for study include FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-2, Risk Management Handbook, and Advisory Circular (AC) 00-6, Aviation Weather For Pilots and Flight Operations Personnel, AC 00-45, Aviation Weather Services, as these documents contain basic material not duplicated herein. All beginning applicants should refer to FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge, for study and basic library reference.It is essential for persons using this handbook to become familiar with and apply the pertinent parts of 14 CFR and the Aeronautical Information Manual (AIM). The AIM is available online at . The current Flight Standards Service airman training and testing material and learning statements for all airman certificates and ratings can be obtained from .This handbook supersedes FAA-H-8083-13, Glider Flying Handbook, dated 2003. Always select the latest edition of any publication and check the website for errata pages and listing of changes to FAA educational publications developed by the FAA’s Airman Testing Standards Branch, AFS-630.This handbook is available for download, in PDF format, from .This handbook is published by the United States Department of Transportation, Federal Aviation Administration, Airman Testing Standards Branch, AFS-630, P.O. Box 25082, Oklahoma City, OK 73125.Comments regarding this publication should be sent, in email form, to the following address:********************************************John M. AllenDirector, Flight Standards Serviceiiii vAcknowledgmentsThe Glider Flying Handbook was produced by the Federal Aviation Administration (FAA) with the assistance of Safety Research Corporation of America (SRCA). The FAA wishes to acknowledge the following contributors: Sue Telford of Telford Fishing & Hunting Services for images used in Chapter 1JerryZieba () for images used in Chapter 2Tim Mara () for images used in Chapters 2 and 12Uli Kremer of Alexander Schleicher GmbH & Co for images used in Chapter 2Richard Lancaster () for images and content used in Chapter 3Dave Nadler of Nadler & Associates for images used in Chapter 6Dave McConeghey for images used in Chapter 6John Brandon (www.raa.asn.au) for images and content used in Chapter 7Patrick Panzera () for images used in Chapter 8Jeff Haby (www.theweatherprediction) for images used in Chapter 8National Soaring Museum () for content used in Chapter 9Bill Elliot () for images used in Chapter 12.Tiffany Fidler for images used in Chapter 12.Additional appreciation is extended to the Soaring Society of America, Inc. (), the Soaring Safety Foundation, and Mr. Brad Temeyer and Mr. Bill Martin from the National Oceanic and Atmospheric Administration (NOAA) for their technical support and input.vv iPreface (iii)Acknowledgments (v)Table of Contents (vii)Chapter 1Gliders and Sailplanes ........................................1-1 Introduction....................................................................1-1 Gliders—The Early Years ..............................................1-2 Glider or Sailplane? .......................................................1-3 Glider Pilot Schools ......................................................1-4 14 CFR Part 141 Pilot Schools ...................................1-5 14 CFR Part 61 Instruction ........................................1-5 Glider Certificate Eligibility Requirements ...................1-5 Common Glider Concepts ..............................................1-6 Terminology...............................................................1-6 Converting Metric Distance to Feet ...........................1-6 Chapter 2Components and Systems .................................2-1 Introduction....................................................................2-1 Glider Design .................................................................2-2 The Fuselage ..................................................................2-4 Wings and Components .............................................2-4 Lift/Drag Devices ...........................................................2-5 Empennage .....................................................................2-6 Towhook Devices .......................................................2-7 Powerplant .....................................................................2-7 Self-Launching Gliders .............................................2-7 Sustainer Engines .......................................................2-8 Landing Gear .................................................................2-8 Wheel Brakes .............................................................2-8 Chapter 3Aerodynamics of Flight .......................................3-1 Introduction....................................................................3-1 Forces of Flight..............................................................3-2 Newton’s Third Law of Motion .................................3-2 Lift ..............................................................................3-2The Effects of Drag on a Glider .....................................3-3 Parasite Drag ..............................................................3-3 Form Drag ...............................................................3-3 Skin Friction Drag ..................................................3-3 Interference Drag ....................................................3-5 Total Drag...................................................................3-6 Wing Planform ...........................................................3-6 Elliptical Wing ........................................................3-6 Rectangular Wing ...................................................3-7 Tapered Wing .........................................................3-7 Swept-Forward Wing ..............................................3-7 Washout ..................................................................3-7 Glide Ratio .................................................................3-8 Aspect Ratio ............................................................3-9 Weight ........................................................................3-9 Thrust .........................................................................3-9 Three Axes of Rotation ..................................................3-9 Stability ........................................................................3-10 Flutter .......................................................................3-11 Lateral Stability ........................................................3-12 Turning Flight ..............................................................3-13 Load Factors .................................................................3-13 Radius of Turn ..........................................................3-14 Turn Coordination ....................................................3-15 Slips ..........................................................................3-15 Forward Slip .........................................................3-16 Sideslip .................................................................3-17 Spins .........................................................................3-17 Ground Effect ...............................................................3-19 Chapter 4Flight Instruments ...............................................4-1 Introduction....................................................................4-1 Pitot-Static Instruments ..................................................4-2 Impact and Static Pressure Lines................................4-2 Airspeed Indicator ......................................................4-2 The Effects of Altitude on the AirspeedIndicator..................................................................4-3 Types of Airspeed ...................................................4-3Table of ContentsviiAirspeed Indicator Markings ......................................4-5 Other Airspeed Limitations ........................................4-6 Altimeter .....................................................................4-6 Principles of Operation ...........................................4-6 Effect of Nonstandard Pressure andTemperature............................................................4-7 Setting the Altimeter (Kollsman Window) .............4-9 Types of Altitude ......................................................4-10 Variometer................................................................4-11 Total Energy System .............................................4-14 Netto .....................................................................4-14 Electronic Flight Computers ....................................4-15 Magnetic Compass .......................................................4-16 Yaw String ................................................................4-16 Inclinometer..............................................................4-16 Gyroscopic Instruments ...............................................4-17 G-Meter ........................................................................4-17 FLARM Collision Avoidance System .........................4-18 Chapter 5Glider Performance .............................................5-1 Introduction....................................................................5-1 Factors Affecting Performance ......................................5-2 High and Low Density Altitude Conditions ...........5-2 Atmospheric Pressure .............................................5-2 Altitude ...................................................................5-3 Temperature............................................................5-3 Wind ...........................................................................5-3 Weight ........................................................................5-5 Rate of Climb .................................................................5-7 Flight Manuals and Placards ..........................................5-8 Placards ......................................................................5-8 Performance Information ...........................................5-8 Glider Polars ...............................................................5-8 Weight and Balance Information .............................5-10 Limitations ...............................................................5-10 Weight and Balance .....................................................5-12 Center of Gravity ......................................................5-12 Problems Associated With CG Forward ofForward Limit .......................................................5-12 Problems Associated With CG Aft of Aft Limit ..5-13 Sample Weight and Balance Problems ....................5-13 Ballast ..........................................................................5-14 Chapter 6Preflight and Ground Operations .......................6-1 Introduction....................................................................6-1 Assembly and Storage Techniques ................................6-2 Trailering....................................................................6-3 Tiedown and Securing ................................................6-4Water Ballast ..............................................................6-4 Ground Handling........................................................6-4 Launch Equipment Inspection ....................................6-5 Glider Preflight Inspection .........................................6-6 Prelaunch Checklist ....................................................6-7 Glider Care .....................................................................6-7 Preventive Maintenance .............................................6-8 Chapter 7Launch and Recovery Procedures and Flight Maneuvers ............................................................7-1 Introduction....................................................................7-1 Aerotow Takeoff Procedures .........................................7-2 Signals ........................................................................7-2 Prelaunch Signals ....................................................7-2 Inflight Signals ........................................................7-3 Takeoff Procedures and Techniques ..........................7-3 Normal Assisted Takeoff............................................7-4 Unassisted Takeoff.....................................................7-5 Crosswind Takeoff .....................................................7-5 Assisted ...................................................................7-5 Unassisted...............................................................7-6 Aerotow Climb-Out ....................................................7-6 Aerotow Release.........................................................7-8 Slack Line ...................................................................7-9 Boxing the Wake ......................................................7-10 Ground Launch Takeoff Procedures ............................7-11 CG Hooks .................................................................7-11 Signals ......................................................................7-11 Prelaunch Signals (Winch/Automobile) ...............7-11 Inflight Signals ......................................................7-12 Tow Speeds ..............................................................7-12 Automobile Launch ..................................................7-14 Crosswind Takeoff and Climb .................................7-14 Normal Into-the-Wind Launch .................................7-15 Climb-Out and Release Procedures ..........................7-16 Self-Launch Takeoff Procedures ..............................7-17 Preparation and Engine Start ....................................7-17 Taxiing .....................................................................7-18 Pretakeoff Check ......................................................7-18 Normal Takeoff ........................................................7-19 Crosswind Takeoff ...................................................7-19 Climb-Out and Shutdown Procedures ......................7-19 Landing .....................................................................7-21 Gliderport/Airport Traffic Patterns and Operations .....7-22 Normal Approach and Landing ................................7-22 Crosswind Landing ..................................................7-25 Slips ..........................................................................7-25 Downwind Landing ..................................................7-27 After Landing and Securing .....................................7-27viiiPerformance Maneuvers ..............................................7-27 Straight Glides ..........................................................7-27 Turns.........................................................................7-28 Roll-In ...................................................................7-29 Roll-Out ................................................................7-30 Steep Turns ...........................................................7-31 Maneuvering at Minimum Controllable Airspeed ...7-31 Stall Recognition and Recovery ...............................7-32 Secondary Stalls ....................................................7-34 Accelerated Stalls .................................................7-34 Crossed-Control Stalls ..........................................7-35 Operating Airspeeds .....................................................7-36 Minimum Sink Airspeed ..........................................7-36 Best Glide Airspeed..................................................7-37 Speed to Fly ..............................................................7-37 Chapter 8Abnormal and Emergency Procedures .............8-1 Introduction....................................................................8-1 Porpoising ......................................................................8-2 Pilot-Induced Oscillations (PIOs) ..............................8-2 PIOs During Launch ...................................................8-2 Factors Influencing PIOs ........................................8-2 Improper Elevator Trim Setting ..............................8-3 Improper Wing Flaps Setting ..................................8-3 Pilot-Induced Roll Oscillations During Launch .........8-3 Pilot-Induced Yaw Oscillations During Launch ........8-4 Gust-Induced Oscillations ..............................................8-5 Vertical Gusts During High-Speed Cruise .................8-5 Pilot-Induced Pitch Oscillations During Landing ......8-6 Glider-Induced Oscillations ...........................................8-6 Pitch Influence of the Glider Towhook Position ........8-6 Self-Launching Glider Oscillations During Powered Flight ...........................................................8-7 Nosewheel Glider Oscillations During Launchesand Landings ..............................................................8-7 Tailwheel/Tailskid Equipped Glider Oscillations During Launches and Landings ..................................8-8 Aerotow Abnormal and Emergency Procedures ............8-8 Abnormal Procedures .................................................8-8 Towing Failures........................................................8-10 Tow Failure With Runway To Land and Stop ......8-11 Tow Failure Without Runway To Land BelowReturning Altitude ................................................8-11 Tow Failure Above Return to Runway Altitude ...8-11 Tow Failure Above 800' AGL ..............................8-12 Tow Failure Above Traffic Pattern Altitude .........8-13 Slack Line .................................................................8-13 Ground Launch Abnormal and Emergency Procedures ....................................................................8-14 Abnormal Procedures ...............................................8-14 Emergency Procedures .............................................8-14 Self-Launch Takeoff Emergency Procedures ..............8-15 Emergency Procedures .............................................8-15 Spiral Dives ..................................................................8-15 Spins .............................................................................8-15 Entry Phase ...............................................................8-17 Incipient Phase .........................................................8-17 Developed Phase ......................................................8-17 Recovery Phase ........................................................8-17 Off-Field Landing Procedures .....................................8-18 Afterlanding Off Field .............................................8-20 Off-Field Landing Without Injury ........................8-20 Off-Field Landing With Injury .............................8-20 System and Equipment Malfunctions ..........................8-20 Flight Instrument Malfunctions ................................8-20 Airspeed Indicator Malfunctions ..........................8-21 Altimeter Malfunctions .........................................8-21 Variometer Malfunctions ......................................8-21 Compass Malfunctions .........................................8-21 Glider Canopy Malfunctions ....................................8-21 Broken Glider Canopy ..........................................8-22 Frosted Glider Canopy ..........................................8-22 Water Ballast Malfunctions ......................................8-22 Retractable Landing Gear Malfunctions ..................8-22 Primary Flight Control Systems ...............................8-22 Elevator Malfunctions ..........................................8-22 Aileron Malfunctions ............................................8-23 Rudder Malfunctions ............................................8-24 Secondary Flight Controls Systems .........................8-24 Elevator Trim Malfunctions .................................8-24 Spoiler/Dive Brake Malfunctions .........................8-24 Miscellaneous Flight System Malfunctions .................8-25 Towhook Malfunctions ............................................8-25 Oxygen System Malfunctions ..................................8-25 Drogue Chute Malfunctions .....................................8-25 Self-Launching Gliders ................................................8-26 Self-Launching/Sustainer Glider Engine Failure During Takeoff or Climb ..........................................8-26 Inability to Restart a Self-Launching/SustainerGlider Engine While Airborne .................................8-27 Self-Launching Glider Propeller Malfunctions ........8-27 Self-Launching Glider Electrical System Malfunctions .............................................................8-27 In-flight Fire .............................................................8-28 Emergency Equipment and Survival Gear ...................8-28 Survival Gear Checklists ..........................................8-28 Food and Water ........................................................8-28ixClothing ....................................................................8-28 Communication ........................................................8-29 Navigation Equipment ..............................................8-29 Medical Equipment ..................................................8-29 Stowage ....................................................................8-30 Parachute ..................................................................8-30 Oxygen System Malfunctions ..................................8-30 Accident Prevention .....................................................8-30 Chapter 9Soaring Weather ..................................................9-1 Introduction....................................................................9-1 The Atmosphere .............................................................9-2 Composition ...............................................................9-2 Properties ....................................................................9-2 Temperature............................................................9-2 Density ....................................................................9-2 Pressure ...................................................................9-2 Standard Atmosphere .................................................9-3 Layers of the Atmosphere ..........................................9-4 Scale of Weather Events ................................................9-4 Thermal Soaring Weather ..............................................9-6 Thermal Shape and Structure .....................................9-6 Atmospheric Stability .................................................9-7 Air Masses Conducive to Thermal Soaring ...................9-9 Cloud Streets ..............................................................9-9 Thermal Waves...........................................................9-9 Thunderstorms..........................................................9-10 Lifted Index ..........................................................9-12 K-Index .................................................................9-12 Weather for Slope Soaring .......................................9-14 Mechanism for Wave Formation ..............................9-16 Lift Due to Convergence ..........................................9-19 Obtaining Weather Information ...................................9-21 Preflight Weather Briefing........................................9-21 Weather-ReIated Information ..................................9-21 Interpreting Weather Charts, Reports, andForecasts ......................................................................9-23 Graphic Weather Charts ...........................................9-23 Winds and Temperatures Aloft Forecast ..............9-23 Composite Moisture Stability Chart .....................9-24 Chapter 10Soaring Techniques ..........................................10-1 Introduction..................................................................10-1 Thermal Soaring ...........................................................10-2 Locating Thermals ....................................................10-2 Cumulus Clouds ...................................................10-2 Other Indicators of Thermals ................................10-3 Wind .....................................................................10-4 The Big Picture .....................................................10-5Entering a Thermal ..............................................10-5 Inside a Thermal.......................................................10-6 Bank Angle ...........................................................10-6 Speed .....................................................................10-6 Centering ...............................................................10-7 Collision Avoidance ................................................10-9 Exiting a Thermal .....................................................10-9 Atypical Thermals ..................................................10-10 Ridge/Slope Soaring ..................................................10-10 Traps ......................................................................10-10 Procedures for Safe Flying .....................................10-12 Bowls and Spurs .....................................................10-13 Slope Lift ................................................................10-13 Obstructions ...........................................................10-14 Tips and Techniques ...............................................10-15 Wave Soaring .............................................................10-16 Preflight Preparation ...............................................10-17 Getting Into the Wave ............................................10-18 Flying in the Wave .................................................10-20 Soaring Convergence Zones ...................................10-23 Combined Sources of Updrafts ..............................10-24 Chapter 11Cross-Country Soaring .....................................11-1 Introduction..................................................................11-1 Flight Preparation and Planning ...................................11-2 Personal and Special Equipment ..................................11-3 Navigation ....................................................................11-5 Using the Plotter .......................................................11-5 A Sample Cross-Country Flight ...............................11-5 Navigation Using GPS .............................................11-8 Cross-Country Techniques ...........................................11-9 Soaring Faster and Farther .........................................11-11 Height Bands ..........................................................11-11 Tips and Techniques ...............................................11-12 Special Situations .......................................................11-14 Course Deviations ..................................................11-14 Lost Procedures ......................................................11-14 Cross-Country Flight in a Self-Launching Glider .....11-15 High-Performance Glider Operations and Considerations ............................................................11-16 Glider Complexity ..................................................11-16 Water Ballast ..........................................................11-17 Cross-Country Flight Using Other Lift Sources ........11-17 Chapter 12Towing ................................................................12-1 Introduction..................................................................12-1 Equipment Inspections and Operational Checks .........12-2 Tow Hook ................................................................12-2 Schweizer Tow Hook ...........................................12-2x。

《空中交通管制英语通话用语实战指南》

《空中交通管制英语通话用语实战指南》下载温馨提示:该文档是我店铺精心编制而成，希望大家下载以后，能够帮助大家解决实际的问题。

文档下载后可定制随意修改，请根据实际需要进行相应的调整和使用，谢谢!并且，本店铺为大家提供各种各样类型的实用资料，如教育随笔、日记赏析、句子摘抄、古诗大全、经典美文、话题作文、工作总结、词语解析、文案摘录、其他资料等等，如想了解不同资料格式和写法，敬请关注!Download tips: This document is carefully compiled by theeditor.I hope that after you download them,they can help yousolve practical problems. The document can be customized andmodified after downloading,please adjust and use it according toactual needs, thank you!In addition, our shop provides you with various types ofpractical materials,such as educational essays, diaryappreciation,sentence excerpts,ancient poems,classic articles,topic composition,work summary,word parsing,copy excerpts,other materials and so on,want to know different data formats andwriting methods,please pay attention!Title: A Practical Guide to Air Traffic Control Communication in EnglishIntroduction:Air traffic control (ATC) is a vitalponent of aviation safety, and effectivemunication between air traffic controllers and pilots is paramount. In the global airspace, English has been designated as the standard language for aviationmunication. This guide aims to provide aprehensive understanding of the essential phrases and procedures used in ATC English conversations.1. Standard Phrases:ATCmunication relies heavily on standardized phrases to ensure clarity and avoid misunderstandings. For instance, "Cleared to land" means the pilot is given permission to land, while "Maintain altitude" instructs the pilot to stay at their current height. " Roger" is an acknowledgment, indicating the message has been understood, and "Wilco" means the pilot willply with the instructions.2. Reading Back Instructions:Pilots are required to read back ATC instructions to confirmprehension. For example, if an ATC says, "Delta 456, turn right heading 270," the pilot would respond, "Right turn 270, Delta 456."3. Emergency Situations:In emergencies, specific phrases are used. "Mayday, Mayday, Mayday" signals a life-threatening situation, while "Pan-Pan, Pan-Pan, Pan-Pan" indicates urgency but not immediate danger. For example, "Delta 456, we have a medical emergency on board, requesting immediate assistance."4. Weather Communications:ATC often provides weather updates. " Visibility 6000 meters, clouds scattered at 3000, overcast at 9000" means visibility is 6 kilometers, with scattered clouds at 3000 feet and a solid cloud cover at 9000 feet.5. Clearance and Departure:Controllers issue takeoff clearances like, "United 123, cleared for takeoff runway 27." Pilots confirm with, "Cleared for takeoff runway 27, United 123."6. Approach and Landing:Controllers guide pilots during approach with phrases such as, "Delta 456, descend to 2000 feet, maintain visual approach." The pilot responds, "Descending to 2000 feet, maintaining visual, Delta 456."7. Radio Silence:When nomunication is necessary, ATC might say, "Radio silence please, radar contact established." This means they are tracking the aircraft visually or by radar and no furthermunication is needed.Conclusion:Mastering ATC English is crucial for safe and efficient flight operations. Regular practice and understanding of these standard phrases and procedures can significantly enhancemunication between controllers and pilots, ensuring the smooth flow of air traffic worldwide. Remember, clear, concise, and accuratemunication saves lives in the sky.This guide serves as a starting point; for in-depth knowledge, regular training and familiarization with International Civil Aviation Organization's (ICAO) Aviation English standards are rmended. Happy flying!。

运输作战支援作文英文

运输作战支援作文英文Transportation combat support is crucial in military operations. It involves the movement of troops, equipment, and supplies to the battlefield. Without effective transportation support, the success of military missions would be greatly compromised.The transportation of troops and equipment to the front lines requires careful planning and coordination. It involves the use of various modes of transportation, including trucks, aircraft, and ships. Each mode of transportation has its own unique challenges and requirements, and it is essential to have a well-coordinated logistics system in place to ensure the smooth flow of supplies and personnel.In addition to the transportation of troops and equipment, combat support also involves the movement of medical supplies, fuel, and ammunition to the front lines. These supplies are essential for sustaining the troops andensuring their effectiveness in combat. Without a reliable transportation system, the delivery of these critical supplies would be severely hampered, putting the success of the mission at risk.The transportation of troops and supplies in a combat environment is often fraught with danger. It requires the use of specialized vehicles and equipment to navigate through hostile terrain and avoid enemy fire. Additionally, the threat of ambushes and roadside bombs adds an extra layer of complexity to transportation operations in a combat zone.In order to ensure the success of transportation combat support operations, military units must work closely with logistics and transportation specialists to develop effective plans and strategies. This may involve the use of advanced technology and equipment to enhance the efficiency and safety of transportation operations in a combat environment.Overall, transportation combat support plays a criticalrole in ensuring the success of military operations. It requires careful planning, coordination, and the use of specialized equipment to transport troops, equipment, and critical supplies to the front lines. Without effective transportation support, the ability of military units to carry out their missions would be severely compromised.。

大型军事公路英语作文

大型军事公路英语作文In the realm of modern warfare, the concept of military highways has evolved to encompass more than just a means of troop movement. These highways are critical infrastructures that serve multiple purposes, from facilitating rapid deployment to enhancing logistical support. This essay will delve into the strategic significance of military highways, exploring their role in national defense and their impact on military operations.Strategic MobilityOne of the primary advantages of military highways is their ability to provide strategic mobility. These roads are designed to withstand heavy loads and are built with the capability to support the movement of armored vehicles, artillery, and other military equipment. This allows for the swift repositioning of forces in response to emerging threats, ensuring that military units can be where they are needed most, when they are needed.Logistical SupportMilitary highways also play a pivotal role in logistical support. They enable the efficient transportation of supplies, fuel, and ammunition to front-line troops. In times of conflict, these highways can become lifelines, ensuring that troops are well-supplied and can sustain operations overextended periods. The maintenance of these roads is therefore a top priority for military planners.Economic ImpactBeyond their military applications, military highways can also have a significant economic impact. They can serve as a catalyst for regional development, connecting remote areas to urban centers and facilitating trade. This dual-use nature of military highways makes them an important consideration for policymakers, who must balance military needs with economic development goals.Security ConcernsHowever, the construction and maintenance of military highways are not without their challenges. Security concerns are paramount, as these roads can become targets for sabotage or attacks by adversaries. Measures must be taken to safeguard these critical assets, including the use of surveillance and the deployment of protective forces.Environmental ConsiderationsLastly, the environmental impact of military highways must be considered. The construction process can disrupt ecosystems and lead to habitat loss. Sustainable practices and careful planning are essential to mitigate these effects and ensure that the development of military highways does not come at the expense of the environment.In conclusion, military highways are a multifaceted component of a nation's defense strategy. They are not only vital forthe rapid deployment and logistical support of militaryforces but also contribute to economic growth and regional development. As such, they require careful planning, robust security measures, and an awareness of environmental implications to ensure their effectiveness and sustainability.。

小学上册第十次英语第二单元期中试卷

小学上册英语第二单元期中试卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1. A frog has long _______ for jumping.2.My favorite animal is a ______ (猫) because they are gentle.3.I like to ___ (listen) to podcasts.4.How many fingers do we have on one hand?A. FourB. FiveC. SixD. Seven5.What is the main ingredient in chocolate?A. CocoaB. SugarC. MilkD. Butter答案:A6. A parrot can live for many ______ (年).7.I enjoy going to the ____.8.What do we wear on our feet?A. HatB. GlovesC. ShoesD. Scarf答案:C9.The __________ (观鸟) activity is fun and educational.10.Which animal lives in a hive?A. AntB. BeeC. SpiderD. Fly11.The __________ is a famous city known for its architecture and canals. (威尼斯)12.What is the capital of Vanuatu?A. Port VilaB. LuganvilleC. SantoD. Tanna答案:A13.What is the capital city of Nicaragua?A. ManaguaB. LeónC. GranadaD. Matagalpa14.The _____ (sage) plant is drought-resistant.15.The law of conservation of mass states that mass cannot be _______ or destroyed.16.__________ (化学史) provides context for modern practices in the field.17.What is the capital of Chile?A. SantiagoB. QuitoC. Buenos AiresD. Lima答案:A18.I enjoy the sound of __________ falling on the ground. (雨)19.What do you call a set of instructions for making something?A. RecipeB. FormulaC. ManualD. Guide答案:A20. A fish lives in _________ (水).21.What do you call a large area of land that is inhabited by animals?A. HabitatB. EcosystemC. BiomeD. All of the above22.I love to ___ (travel/study) languages.23. A __________ has a distinctive call that sounds like a laugh.24.Which is a mode of transportation?A. TableB. CarC. PhoneD. Chair答案:B25.What is the main ingredient in bread?A. FlourB. SugarC. RiceD. Salt26.What is 15 + 5?A. 20B. 21C. 22D. 23答案:A27.The ______ is what keeps us grounded on Earth.28.The ________ (networking) helps build connections.29.The _____ (土壤质量) affects plant growth significantly.30. A ________ (植物资源利用策略) enhances productivity.31.The ______ is a large ball of gas that gives us light.32.My ________ (奶奶) makes the best cookies in the world.33.We have a ______ (丰富的) educational system.34.We picked ________ from the tree.35.My brother has a ______ (小马). He takes care of it every ______ (天).36.The __________ range runs along the border of the United States and Canada. (落基山脉)37.The ancient Egyptians worshipped gods like ______ (拉) and ______ (伊西斯).38.physical map) shows terrain features like mountains and rivers. The ____39. A squirrel gathers ______ (坚果) in autumn.40.Solar panels convert sunlight into _______ energy.41. A frog can leap from one place to another very ______ (远).42.What is the capital of Sweden?A. OsloB. StockholmC. CopenhagenD. Helsinki答案:B43.I want to _______ (学习) how to cook.44. A sedimentary rock that is formed from the remains of plants and animals is called ______.45. A ____(climate refugee) is displaced due to climate change.46.The chemical formula for sodium acetate is ______.47.My ________ (玩具名称) brings happiness to my life.48.Which fruit is red and often used to make juice?A. BananaB. GrapeC. AppleD. Orange答案:C49.The ________ was an ancient civilization in South America.50.I like to ________ (evaluate) options carefully.51.The ________ (地形) can be very rugged.52.The ancient Greeks held competitions in the ________.53.What do you call a small house for a dog?A. KennelB. CageC. BarnD. Shed54.The _______ (鬣狗) laughs at night.55.What do you call a baby tegu?A. HatchlingB. KitC. PupD. Calf56.What is the common name for the respiratory organ in humans?A. HeartB. LungsC. LiverD. Kidneys答案:B57.Which season comes after summer?A. FallB. WinterC. SpringD. Autumn答案:A58.I write a diary every day to share my thoughts and ______ (感受). It helps me understand myself better.59.What is the opposite of "happy"?A. GladB. SadC. JoyfulD. Excited答案:B60.I drink __________ in the morning.61.The penguin waddles on the _______ (企鹅在_______上摇摆).62.What is the capital of Italy?A. RomeB. FlorenceC. MilanD. Venice63.The _____ (elephant/giraffe) is tall.64.I like to ________ my friends.65.The process of combining elements to form compounds is called ______.66. A _______ is a small plant that grows close to the ground.67.What is the main purpose of the Hubble Space Telescope?A. To study the EarthB. To study the MoonC. To observe distant galaxiesD. To communicate with aliens68.The __________ (历史的连接) link us to our roots.69. A _____ (植物科学) can lead to advancements in agriculture.70. A chemical equilibrium occurs when the rates of forward and reverse reactions are ______.71. A snail leaves a ______ (黏糊糊的) trail behind.72.What do you call a sweet, baked treat made from chocolate?A. CakeB. BrownieC. CookieD. All of the above答案:D73.My friend is a _____ (艺术家) who draws cartoons.74.We listen to ___ (music).75.The __________ (历史的复杂性) requires careful study.76.What is the name of the animal that lives in a hive and makes honey?A. AntB. BeeC. FlyD. Spider答案:B77.I need to _____ (finish/start) my homework.78.The _____ (根部) store energy for the plant.79.I enjoy participating in school ______ (活动) because I get to meet new friends and learn new skills.80.I like to play ______ (棋类游戏) with my friends after school.81.The currency used in Japan is ________ (日本使用的货币是________).82.The girl sings very ________.83.What do we call the small pieces of glass used for decoration?A. MarbleB. BeadsC. GemsD. Mosaic答案:D84.The badger is known for its digging ______ (能力).85.I like to make ______ for my friends.86.The __________ Ocean is located between Africa and Australia.87.The leaves change color in the ______.88.Rockets are used to launch spacecraft into ______.89.Planting a variety of flowers can create a more colorful and ______ landscape. (种植多样的花卉可以创造出更丰富多彩的景观。

平顶山“PEP”2024年小学三年级下册F卷英语第三单元测验卷(有答案)

平顶山“PEP”2024年小学三年级下册英语第三单元测验卷(有答案)考试时间：90分钟（总分:110）A卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、填空题：The periodic table lists all known _______. (元素)2、听力题：The concept of ecological balance highlights the importance of maintaining ______ in nature.3、听力题：He is very ___. (happy)4、听力题：I like to swim in the ________.5、听录音排序。

6、听力题：The law of conservation of mass states that mass cannot be _____ in a chemical reaction.7、What sound does a cow make?A. MeowB. BarkC. MooD. Roar答案: C8、What is the primary color of the sky?A. GreenB. BlueC. YellowD. Red9、听力题：The children are _____ in the classroom. (talking)10、填空题：The horse gallops across the ______ (田野). It looks very ______ (自由).11、填空题：I like to play ________ (排球) during PE class.12、听力题：The _____ (moon/sun) is bright.13、听力题：His favorite book is about a ________.14、What do we call the process of natural selection?A. EvolutionB. AdaptationC. MutationD. Speciation答案:A15、填空题：The raccoon washes its food in _________. (水)16、听力题：The Cold War involved a space race between the USA and the ________ Union.17、What is the capital of Italy?A. RomeB. VeniceC. MilanD. Florence答案: A18、听力题：It is _____ (sunny) today.In physical education class, we do ______ (锻炼) to stay fit. Exercise is important for a healthy ______ (生活).20、听力题：The chemical symbol for platinum is ______.21、听力题：The chemical symbol for nickel is ______.22、填空题：I saw a ________ in the garden today.23、填空题：My dog enjoys _______ (散步) with me.24、sustainable practices) guide responsible behaviors. 填空题：The ____25、听力题：The butterfly is _______ (fluttering) around.26、填空题：I like to take photos of ________ (风景) when I travel to capture beautiful memories.27、听力题：The __________ is home to many unique species of animals.28、听力题：I want to go ___ the zoo. (to)29、听力题：The chemical formula for rhenium dioxide is _____.30、听力题：The tree has _____ (leaves/branches).31、填空题：The ______ (小鸟) builds its home carefully.32、填空题：The _____ (种植者) gives us tips on how to grow vegetables.33、听力题：The baby is ______ (sleeping) in the crib.I enjoy ______ new things. (learning)35、What is the main language spoken in the UK?A. FrenchB. SpanishC. EnglishD. German36、听力题：The chemical formula for sodium dichromate is _____.37、What is the capital of Switzerland?A. ZurichB. GenevaC. BernD. Basel答案:C38、What is the opposite of light?A. HeavyB. DarkC. BrightD. Clear答案:B39、填空题：The __________ (历史的反思能力) enriches our understanding.40、What do you call a person who studies plants?A. BotanistB. ZoologistC. GeologistD. Biologist答案: A41、填空题：The invention of the bicycle changed personal _____.42、填空题：I saw a ________ at the zoo yesterday.43、What is the term for a baby iguana?a. Hatchlingb. Kitc. Pupd. Chick答案:a44、填空题：I can race my ________ (玩具) down a ramp.45、What is the largest mammal in the world?A. ElephantB. Blue whaleC. GiraffeD. Hippopotamus答案:B46、Which fruit is red and often used in pies?A. BananaB. CherryC. OrangeD. Grapes答案:B47、填空题：I watched a _______ (小鸟) build its nest.48、What do we call the central part of an atom?A. ElectronB. ProtonC. NucleusD. Neutron答案:C49、What is the name of the famous detective created by Arthur Conan Doyle?A. Hercule PoirotB. Sam SpadeC. Sherlock HolmesD. Philip Marlowe答案: C50、What do you call a large bird that cannot fly?A. PenguinB. SparrowC. EagleD. Falcon答案:A51、听力题：A tornado is a fast-moving ______.52、听力题：I wear _____ (帽子) in winter.53、听力题：Bases feel ______ and can be slippery.54、Which of these is a common dairy product?A. BreadB. CheeseC. PastaD. Rice答案:B55、填空题：The __________ (历史的交互影响) shape our experiences.56、填空题：A rabbit's nose is very ______ (敏感).57、听力题：A _______ is a reaction that involves the breaking of chemical bonds.58、What do we call the process of converting a solid into a liquid?A. EvaporationB. MeltingC. FreezingD. Condensation答案:B59、What is the name of the famous American singer known for "Firework"?A. Katy PerryB. Taylor SwiftC. Ariana GrandeD. Demi Lovato答案：A60、选择题：What do we call a food that is cooked over an open flame?A. BoiledB. GrilledC. BakedD. Fried61、What is the name of the famous mouse character?A. Donald DuckB. Mickey MouseC. GoofyD. Pluto答案:B62、What do we call the imaginary line dividing the Earth into Northern and Southern Hemispheres?A. EquatorB. Prime MeridianC. Tropic of CancerD. Tropic of Capricorn63、What do we call the process of turning a gas into a liquid?A. EvaporationB. CondensationC. FreezingD. Sublimation答案:B64、听力题：A __________ is a mixture of two or more metals.65、听力题：The ice cream is ___ (cold/hot).66、填空题：A _______ (小螃蟹) scuttles along the beach.67、What is the largest organ inside the human body?A. HeartB. LiverC. BrainD. Skin答案:B. Liver68、填空题：The __________ (历史的复杂性) makes it a fascinating subject to study.69、What is the name of the famous ancient city in Greece?A. AthensB. SpartaC. CorinthD. DelphiThe __________ (历史的见证者) recount significant moments.71、填空题：A skunk sprays a strong ______ (气味) when threatened.72、填空题：My uncle loves to __________. (钓鱼)73、填空题：_____ (herb) are often used in cooking.74、What is the name of the famous American landmark located in South Dakota?A. Mount RushmoreB. Statue of LibertyC. Golden Gate BridgeD. Grand Canyon答案：A75、听力题：The ice cream is ______ (yum) and creamy.76、填空题：A _____ (植物访谈) can share knowledge among communities.77、What do you call a young female bird?A. ChickB. HenC. DoveD. Sparrow78、听力题：The _______ can be a symbol of peace.79、填空题：A _______ (鸭子) loves to swim.80、填空题：I like to pretend I'm a chef with my kitchen ________ (玩具名称).81、填空题：________ (植物保护工作) involves many strategies.82、填空题：My ________ (玩具) has a beautiful design.We can _____ (cultivate) a variety of plants.84、听力题：The main role of DNA is to store _____ information.85、s are popular for their ______ (耐旱) qualities. 填空题：Sugar di86、听力题：The chemical formula for iron(III) oxide is __________.87、听力题：Some plants can _______ in different climates.88、选择题：What do you call a story that teaches a lesson?A. NovelB. FableC. BiographyD. Myth89、听力题：I drink _____ (water/coffee) with lunch.90、听力题：The Earth's atmosphere is vital for protecting ______ life.91、What is the shape of a basketball?A. SquareB. RectangleC. OvalD. Circle答案：D92、选择题：What is the opposite of big?A. SmallB. HugeC. TallD. Wide93、What do we call the first month of the year?A. DecemberB. JanuaryC. FebruaryD. March答案:B94、选择题：Which animal is known as "man's best friend"?A. CatB. DogC. RabbitD. Hamster95、听力题：In a chemical reaction, substances change into new __________.96、What do we call the study of the Earth’s features?A. GeographyB. HistoryC. SociologyD. Biology97、听力题：Objects in motion tend to stay in _______.98、填空题：The kangaroo hops to _______ (寻找) food.99、What do you call a person who studies fish?A. IchthyologistB. BiologistC. ZoologistD. Marine biologist100、填空题：A whale is a __________ (大型) marine animal.。

物资考试题库(选择题)

物资考试题库一、单项选择题1、商品流通包括的四个环节是（A）。

A．采购、储存、生产、销售B．购进、储存、运输、销售C．购进、储存、保管、销售D．购进、存储、验收、出库2、仓储管理工作中的基础、关键、中心分别是（D）。

A．入库、搞好保管保养、出库B．出库、入库、搞好保管保养C．出库、搞好保管保养、入库D．入库、出库、搞好保管保养3、基本不受气候条件影响的货物应储存在（B）内。

A．库房B．货场C．货棚D．仓库4、大批量进货、零星发货的货物应储存在（B）。

A．人力仓库B．半机械化仓库C．机械化仓库D．自动化仓库5、适合大型仓库的仓储组织形式是（B）。

A．小组负责制B．专业分工制C．直线制D．个人负责制6、位于仓库一切管理工作首位的是（A）。

A．安全工作B．财务工作C．人事工作D．教育工作7、及时验收有利于（A）。

A．不延误索赔期B．确保质量C．提高效率D．降低成本8、属于验收凭证的是（C）。

A．合格证、质保书、说明书B．送货单、领料单C．合格证、质保书、D．装箱单9、条码的主要识别器（B）。

A．条码扫描仪B．条码阅读器C．条码译码器D．以上都是10、外观质量验收内容包括（B）。

A．商品质量、表面受损、缺陷情况B．外包装、外观受损、受潮、霉变、锈蚀情况C．数量、表面受潮、缺陷、规格情况D．重量、商品内在质量、缺陷情况11、储存商品在“三一致”（性能一致，养护措施一致，消防方法一致）的前提下，把库房、货物划分为若干保管区域来保管库存商品的方法是（A）。

A．分区分类法B．先进先出法C．科学堆码法D．专仓专储法12、仓库检查的内容包括（C）。

A．查数量、查质量、查保管条件、查验收工具、查隐患B．查数量、查质量、查保管条件、查隐患、查安全C．查数量、查质量、查保管条件、查验收工具、查安全D．查数量、查质量、查隐患、查验收工具、查安全13、合理盈亏的处理是（A）。

A．报盈亏B．报亏C．报盈D．报损14、（C）是指在一定的温度下，每立方米的空气中能容纳水汽量的最大限度。

雅思作文 transport in metropolis f

雅思作文transport in metropolis f The solutions to the pressing issue of traffic congestions, especially in metropolis, have been a frequent topic of discussion. However, 24/7 free public transport service would not tackle this issue; therefore, other effective measures would be in great need.Theoretically, providing 24/7 free public transport, like underground and bus, could produce some positive outcomes, among which stands out convenience. This means that commuters could travel by any mode of public transport at any time. Moreover, it is free of charge, which might slightly ease the financial burden on the poor or people of middle class. Certainly, this would attract more public transport users,so the number of private cars may be reduced considerably.However, this approach would exert more negative outcomes if it is carried out. One main disadvantage is the low-quality public service. By making it free of charge, public transport service would, of course, degrade to a certain degree, since the vehicle will be crowded and even suffocating.. Another problem is that few people would use public transport at late night or in the very early morning; this would be a great waste in terms of public funds. Undoubtedly, people's financial burden would be heavier.To solve traffic gridlock, we need to implement reasonable city road plan. It is true that some traffic jam is caused by inappropriate city roadplan and construction. Thanks to high technology, it is also possible to install CCTV to make traffic forecast to drivers. Other strategies could exert significant effects, too, such as controlling and improving signal timing and restricting peak-hour curbside park.In conclusion, 24/7 free public transport would not be an effective measure to resolve traffic congestion in the long term; hence other strategies need to be implemented at the same time.。

防踩踏事件作文

防踩踏事件作文英文回答：Mass Gathering Event Safety。

Introduction。

Mass gatherings, with their large crowds and potential for stampedes, pose a significant safety risk. Ensuring the safety of attendees at these events requires careful planning and preparation by organizers, law enforcement, and emergency responders.Crowd Management。

Effective crowd management is essential to prevent stampedes. This includes controlling the flow of patrons through the venue using crowd barriers, signage, and security personnel. It is also crucial to have designated evacuation routes and procedures in place in case of anemergency.Security。

Security measures are essential to deter potential threats and respond to incidents. This includes conducting thorough searches for weapons and other dangerous items, as well as having a sufficient number of security personnel present at the event.Communication。

交通指挥英语作文高中

交通指挥英语作文高中英文：Traffic control is an essential part of managing the flow of vehicles and pedestrians on the road. It is important to have effective traffic control measures in place to ensure the safety and efficiency of the transportation system.One of the key aspects of traffic control is the use of traffic signals. Traffic signals, such as traffic lights and pedestrian signals, help to regulate the flow oftraffic and ensure that vehicles and pedestrians can move safely through intersections. For example, when the traffic light turns red, it signals to drivers that they must stop, allowing pedestrians to cross the road safely. This helps to prevent accidents and keep the traffic moving smoothly.Another important aspect of traffic control is the use of traffic signs and road markings. These signs andmarkings provide important information to drivers, such as speed limits, lane markings, and directions. For example, a "yield" sign indicates to drivers that they must give the right of way to other vehicles, while a "no parking" sign informs drivers that they cannot park in a certain area. Road markings, such as crosswalks and stop lines, also help to guide and control the flow of traffic.In addition to traffic signals, signs, and markings, traffic control also involves the use of traffic police and other law enforcement officers. These officers help to enforce traffic laws and regulations, and ensure that drivers and pedestrians follow the rules of the road. For example, they may direct traffic at busy intersections, issue citations for traffic violations, and respond to accidents and emergencies.Overall, effective traffic control is essential for ensuring the safety and efficiency of the transportation system. By using a combination of traffic signals, signs, markings, and law enforcement, we can help to prevent accidents, reduce congestion, and keep the traffic flowingsmoothly.中文：交通指挥是管理道路上车辆和行人流动的重要部分。

贵阳“PEP”2024年小学六年级下册第10次英语第4单元期末试卷

贵阳“PEP”2024年小学六年级下册英语第4单元期末试卷考试时间：90分钟（总分:140）A卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、听力题：The ________ (canyon) is carved by water.2、What do we call the process of a caterpillar becoming a butterfly?A. MetamorphosisB. GrowthC. EvolutionD. Transformation答案: A3、填空题：I have a kind _____ (邻居).4、听力题：The Milky Way galaxy is a spiral ______.5、听力题：The rabbit is ________ in the grass.6、听力题：The law of conservation of mass states that mass cannot be _____ in a chemical reaction.7、What is the name of the famous landmark in India?A. Great WallB. Taj MahalC. Eiffel TowerD. Colosseum答案：B8、What is the currency used in the USA?A. DollarB. EuroC. YenD. Pound9、填空题：My favorite season is ________ (春天). The flowers bloom, and the weather is ________ (温暖) and sunny.10、听力题：The __________ is the amount of space occupied by a substance.11、选择题：What do we call a person who creates art?A. ArtistB. PainterC. SculptorD. All of the above12、填空题：Garden tools include ______ (铲子) and rakes.13、听力题：I see a big __ in the sky. (bird)14、选择题：What is the color of a typical grape?A. RedB. GreenC. PurpleD. All of the above15、听力题：My brother is a great ________.16、填空题：My brother is a __________ (游戏设计师).17、填空题：I like to play ______ with my cousins.18、听力题：The antelope's speed is unmatched, making it one of the swiftest creatures on ____.19、听力题：They are ___ a drawing. (making)A volcano erupts when ______ comes to the surface.21、填空题：We have a ______ (愉快的) family day every month.22、听力题：The color of an object depends on the light it ______.23、听力题：I see a _______ (ladybug) on a leaf.24、填空题：The ______ (绿色技术) often utilizes plant resources.25、填空题：A frog can catch insects with its ______ (舌头).26、填空题：Martin Luther King Jr. is known for his role in the ________ rights movement.27、听力题：The flowers are _____ (colorful/grey).28、填空题：The hamster is a very popular _________. (宠物)29、填空题：The sunflowers turn to face the _______ each day.30、What is the main ingredient in a smoothie?A. MilkB. YogurtC. FruitD. Ice答案:C31、听力题：I ________ to play games.32、Which of these is a mode of transportation?A. BicycleB. SofaC. TableD. Bed答案: AA _____ (自然景观) can inspire artists.34、填空题：The ________ is a tiny creature that flies.35、填空题：We will celebrate my ________ (生日) with a party.36、听力题：A suspension is a mixture where particles are ______.37、填空题：My sister is _______ than I am.38、听力题：A __________ is the measure of how tightly packed particles are in a substance.39、听力题：The sandwiches are ___ (fresh/old).40、听力题：We will _____ (play/study) after school.41、听力题：My dad is a ______. He knows how to fix computers.42、How many players are there in a rugby team?A. 11B. 13C. 15D. 17答案: C43、What is the capital of Sudan?A. KhartoumB. OmdurmanC. Port SudanD. Nyala答案:A44、听力题：His favorite hobby is ________.45、填空题：It’s nice to hear the __________ during a light rain. (滴答声)A barn owl hunts at ______.47、What is the capital of Iceland?A. ReykjavikB. OsloC. HelsinkiD. Stockholm答案: A48、Which tool is used for measuring temperature?A. BarometerB. ThermometerC. RulerD. Stopwatch答案: B49、填空题：A kitten loves to play with ______ (毛线).50、填空题：The explorer traveled to many _____ (国家).51、听力题：Granite is an example of an ______ rock that forms from cooled magma.52、What is the term for a young camel?A. CalfB. FoalC. KidD. Calf答案:A53、What is the primary color that, when mixed with blue, creates green?A. YellowB. RedC. OrangeD. Purple答案:A54、填空题：The __________ (科学研究) contribute to knowledge.55、听力题：The chemical formula for lithium phosphate is _____.Comets originate from the Oort ______.57、Which animal says "meow"?A. DogB. CatC. CowD. Sheep答案：B58、填空题：I like to make up stories with my ________ (玩具名称).59、听力题：Sediment is made up of tiny pieces of ______, minerals, and organic matter.60、填空题：The ________ is a famous landmark in Paris, France.61、听力题：The capital of Mexico is __________.62、填空题：The ________ is a famous ancient site in Greece.63、填空题：The __________ is a large lake located in Africa. (坦噶尼喀湖)64、听力题：The chemical formula for ammonia is _____.65、听力题：I want to _____ (go/stay) home now.66、What do you call the sweet food made from milk and sugar that is often served as a dessert?A. PuddingB. CustardC. CreamD. Gelato答案: B67、填空题：The capital of Uganda is ________ (坎帕拉).68、Which animal is known for its ability to fly?A. FrogB. FishC. BirdD. Snake答案: C69、What is the term for a planet's revolution around the sun?A. RotationB. OrbitC. RevolutionD. Translation70、填空题：The __________ (历史的根源) trace back to ancient times.71、填空题：I enjoy playing with my ________ on sunny days.72、What is the name of the famous American national park known for its geysers?A. YellowstoneB. YosemiteC. Grand CanyonD. Zion答案: A73、Which animal is known for its ability to change color?a. Chameleonb. Turtlec. Frogd. Goldfish答案:A74、填空题：My _____ (小猫) likes to climb.75、填空题：On sunny days, I love to go __________ with my family. (徒步旅行)76、听力题：The formula for calcium carbonate is ______.77、填空题：I enjoy taking my ________ (玩具名称) on trips.78、听力题：A solution is made of a solvent and a _______.79、听力题：Many _______ are used in traditional medicine.80、填空题：I enjoy _______ (参加)科学实验.81、Which bird is known for its colorful feathers?A. SparrowB. ParrotC. PigeonD. Penguin答案: B82、听力题：I can run ______ fast. (very)83、填空题：The __________ (历史的反思) helps societies grow.84、听力题：The chemical formula for potassium sulfide is __________.85、听力题：The __________ is a famous area known for its traditional medicine.86、听力题：I like to play ______ (basketball) with my friends.87、What is the primary color that mixes with black to create gray?A. WhiteB. RedC. BlueD. Yellow答案:A88、填空题：_____ (温室) help plants grow in any season.89、听力题：A __________ is a small-scale representation of the earth's features.90、What do you call a baby pig?A. CalfB. PigletC. KitD. Fawn答案:B91、填空题：My dad is an _____ (工程师) who builds roads.92、填空题：The capital of Togo is ________ (洛美).93、填空题：My sister enjoys __________ (参与公共事务).94、听力题：The dog is ______ in the yard. (barking)95、How many planets are in our solar system?a. Eightb. Ninec. Tend. Eleven答案:A96、听力题：In a chemical reaction, substances are transformed into new _____ (substances).97、听力题：The cake is _____ (delicious/yummy).98、选择题：What is the main ingredient in a soup?A. MilkB. WaterC. MeatD. Vegetables99、填空题：The _____ (rainbow) appears after a storm.100、填空题：The ______ (小鸟) builds a nest for its eggs.。

惠州2024年10版小学3年级下册P卷英语第1单元寒假试卷

61、What is the name of the famous wizarding school in Harry Potter? A. Hogwarts B. Durmstrang C. Beauxbatons D. Ilvermorny 答案:A
62、听力题： The ______ helps us understand social issues.
53、Which of these is a vegetable? A. Apple B. Carrot C. Banana D. Grape
54、听力题： It is _____ (cold) today.
55、填空题： The ________ was a vital moment in the history of social movements.
59、What is the capital of New Zealand? A. Wellington B. Auckland C. Christchurch D. Hamilton 答案: A
60、What is the largest planet in our solar system? a. Earth b. Mars c. Jupiter d. Saturn 答案:c
65、What is the term for a baby kangaroo? A. Cub B. Kit C. Joey D. Calf 答案: C
66、What is the main ingredient in bread? A. Sugar B. Yeast C. Flour D. Water 答案: C
56、What do you call the liquid part of blood? A. Plasma B. Platelets C. Cells D. Clots 答案: A

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ployed to find the desired direction for crystal cutting. The crystal slices cut in various orientations are mounted in epoxy for polishing in preparation for chemical etching. For defect morphology investigation, chemical etching by E ~ solution 5is the major method in this work. This etchant is suitable for the formation of characteristic etch pits on all major faces, and for the identification ofthe different polarity of the (111 )A and ( l l l ) B faces. The E ~ solution is particularly useful to identify the various defects such as dislocations, twin boundaries, subgrain, and multi-grain boundaries. This is important to observe small differences between grains and adjacent single crystal regions. All of the etched faces in this work were low index faces, such as (100), (110), and (111) causing etch pits of regular shapes. The dislocation density is based on the use of Nakagawa etchant. 6
INTRODUCTION Cadmium telluride is a very attractive opto-electronic material for many applications. The inherent advantages of the vapor growth method are based on lower growth temperatures relative to the melt growth. However, an effective application of this technique for the production of CdTe single crystals was limited by the low vapor growth rate. The very fast vapor growth (VFVG) technique developed in this laboratory 1 provided an effective method to grow CdTe single crystals at high growth rates up to 40 mm/day. This is by far the highest vapor growth rate of CdTe and related IIVI compounds 2reported to date. Therefore, the vapor growth rate of CdTe is now comparable to the rates obtained by the melt method (about 2 mm/h) and provides a definite potential for commercial applica*Present address: Institute of Physics, Chinese Academy of Sciences, Beijing, P.R. China. (Received October 21, 1994; revised May 1, 1995)
Journal of Electronic Materials, Vol. 24, No. 8, 1995
Regular Issue Paper
Defects in CdTe Single Crystals Grown by Very Fast Vapor Growth Technique
H. WIEDEMEIER and G.H. WU*
EXPERIMENTAL PROCEDURES
The overall experimental procedures have been reported previously in detail2 The CdTe source material was synthesized from high purity (99.9999% with respect to metals) elements Cd and Te at about 880900~ Further improvement of the purity and sto-
ichiometry of the CdTe source material was achieved by sublimation under a dynamic vacuum. About 7-20 g purified CdTe source material were loaded into the growth ampoule of 15 mm inner diameter and 8-10 cm length. Most of the bulk single crystals were grown at a temperature of about 900~ some were grown at 830 or 870~ A specially designed furnace and temperature profile employed in this work are similar to that used for the HgCdTe single crystal growth from the vapor reported previously.4 A schematic diagram of the ampoule geometry and temperature profile has been shown earlier. 1 An additional heater established a temperature peak near the growth region about 20~ higher than the temperature in the source zone. This modified Piper-Polish profile can provide high temperature gradients (dT/dx) up to 40~ when the growth temperature differences between the source and seed interface are only 5-10~ Changing the power supply to the additional heater, the temperature gradient can be adjusted from about 5--40~ in the growth region. A translation system of step motors provided ampoule pulling rates from 3 to 40 mndday. After completion of the growth process, the as-grown bulk crystals are separated from the seed, and the growth direction and the orientation of the natural facets are determined by Laue x-ray back diffraction techniques. This technique was alsoeier and Wu
Fig. 1. Chemically etched (E~-2 solution) longitudinal cross section of a CdTo seed crystal (magn. 19 X) grown at 830~ and a dT/dx of 5~
Department of Chemistry, Rensselaer Polytechnic Institute, Troy, NY 12180 Single crystals of CdTe were obtained by the very fast vapor growth technique. The four major defects, namely, multi-grains, lamellar, lateral, and micro-twins, which are fatal to the single crystallinity, were eliminated or limited by increasing the growth stability. This investigation indicates that the latent heat under high growth rate conditions should not be neglected. A model is developed to explain the effects of latent heat on the growth stability at the interface. A relationship between crystal morphologies and growth conditions was established. It strongly suggests that the above defects are growth stability related. The origin of twinning, dominated by growth stability, is discussed in this paper. K e y w o r d s : CdTe, defects, growth stability, single crystal, twins, very fast vapor growth