华北水利水电大学《机械控制工程基础》历年考研真题(2005-2005)完整版

- １ -2005—2006学年第二学期《 数控机床与编程技术》卷 供（04机电班）使用一、判断题（正确的填“T ”，错误的填“F ”。

每题1分，满分20分）1、（ ）YT 类硬质合金中含钴量愈多,刀片硬度愈高,耐热性越好,但脆性越大。

2、（ ）主偏角增大，刀具刀尖部分强度与散热条件变差。

3、（ ）对于没有刀具半径补偿功能的数控系统，编程时不需要计算刀具中心的运动轨迹，可按零件轮廓编程。

4、（ ）一般情况下，在使用砂轮等旋转类设备时，操作者必须带手套。

5、（ ）数控零件加工程序的输入输出必须在MDI （手动数据输入）方式下完成。

6、（ ）退火的目的是改善钢的组织，提高其强度，改善切削加工性能。

7、（ ）平行度、对称度同属于位置公差。

8、（ ）需渗碳淬硬的主轴，上面的螺纹因淬硬后无法车削，因此要车好螺纹后，再进行淬火。

9、（ ）外圆车刀装的低于工件中心时，车刀的工作前角减小，工作后角增大。

10、（ ）加工偏心工件时，应保证偏心的中心与机床主轴的回转中心重合。

11、（ ）全闭环数控机床的检测装置，通常安装在伺服电动机上。

12、（ ）只有当工件的六个自由度全部被限制，才能保证加工精度。

13、（ ）在编写圆弧插补程序时，若用半径R 指定圆心位置，不能描述整圆。

14、（ ）低碳钢的含碳量不大于0.025％。

15、（ ）数控车床适宜加工轮廓形状特别复杂或难于控制尺寸的回转体零件、箱体来零件、精度要求高的回转体类零件、特殊的螺旋类零件等。

16、（ ）可以完成集合造型（建模）刀位轨迹计算及生成后置处理程序输出功能的编程方法，被称为图形交互式自动编程。

17、（ ）液压传动中，动力元件是液压缸，执行元件是液压泵，控制元件是油箱。

18、（ ）恒线速控制的原理是当工件的直径越大，进给速度越慢。

19、（ ）数控机床的伺服系统由伺服驱动和伺服执行两个部分组成。

20、（ ）CIMS 是指计算机集成制造系统，FMS 是指柔性制造系统。

第一章液压与气压传动概述1.液体传动有哪两种形式？它们的主要区别是什么？2.液压传动有哪些基本组成部分?试说明各组成部分的作用。

3.液压传动有哪些优缺点?4.如何绘制常用液压元件的图形符号?第三章液压泵与液压马达1.液压泵的基本工作条件是什么？简述外啮合齿轮泵的工作原理。

2.什么是液压泵的排量？理论流量？实际流量？容积损失和容积效率？3.齿轮泵的压力提高主要受到哪些因素影响？可以采用哪些措施来提高齿轮泵的压力？4.某液压泵的工作压力为10.0MPa，转速为1450.0 r／min，排量为46.2mL/r,容积效率为0.95，总效率为0.9。

求泵的实际输出功率和驱动该泵所需的电机功率。

5.已知液压泵的额定压力为P n,额定流量为q n,如不计管路压力损失，试确定在图3-1所示各工况下，泵的工作压力P(压力表读数)各为多少？图3-16.轴向柱塞泵如何实现双向变量泵功能?7.双作用叶片泵的叶片底部为什么要通入压力油？压力油是如何引入到叶片泵的底部的？8.双作用叶片泵的叶片在转子上是如何安装了？为什么要这么安装？在安装双作用叶片泵时，如果让电动机的转向与规定的方向相反，会产生什么后果？9.一泵当负载压力为 8MPa 时，输出流量为 96L/min ，而负载压力为 10MPa 时，输出流量为 94L/min 。

用此泵带动一排量 q=80cm 3 /r 的液压马达，当负载转矩为 120N·m 时，液压马达的机械效率为 0.94 ，其转速为 1100r/min ，求此时液压马达的容积效率。

（提示：先求马达的负载压力）10.某液压泵的输出压力为5MPa,排量为10mL/r,机械效率为0.95,容积效率为0.9,当转速为1200r/min时,泵的输出功率和驱动泵的电动机功率各为多少?=168mL/r,在额定压力29.5MPa和11.某液压泵的转数为950r/min,排量为Vp同样转速下,测得的实际流量为150L/min,额定工况下的总效率为0.87,求:。

华北水利水电学院2005年攻读硕士学位研究生招生命题考试 工程流体力学试题注意事项：1、答案全部答在答题纸上，写在试卷上无效；2、考试时间180分钟（3个小时），满分150分。

(一)是非题（本大题13小题, 每小题3分, 共39分）（对的填Y，错的填N）1．静止与运动的的液体都能承受切应力。

（）2．雷诺数反映了惯性力与粘滞力的对比关系（）3．总水头损失是总体水流运动克服流体粘性所损耗的全部能量。

（）4．边界层内的液流一定是势流。

（）5．小扰动在超声速气流中的传播范围只能在马赫锥内( )6．明渠中急流的Fr数必大于1。

（）7．真空表明该处压强小于大气压。

（）8．有旋运动的旋转角速度必为零。

（）9．紊流的切应力只与流体的脉动有关。

（）10．圆管层流的水头损失与流速的一次方成正比。

（）11．在管径逐渐扩大的管流中，雷诺数沿程增大。

（）12．若孔口与管嘴的直径相同，作用水头也相同，则孔口流速必大于管嘴的流速（）13．水泵的扬程是指水泵的提水高度。

（）（二）选择题（本大题3小题, 每小题3分, 共9分，唯一性选择）1. 液流沿程水头损失系数与雷诺数 Re 和边壁粗糙度都有关时，表明该液流属()( 1 )层流区；( 2 )紊流光滑区；( 3 )紊流过渡粗糙区；( 4 )紊流粗糙区。

2. 亚声速气流通过收缩喷管，速度最大可达到 ( )。

(1) 超声速； (2) 声速；(3) 亚声速；(4) 两倍音速。

3. 恒定平面流场中的一条流线上，必有 ( )(1) 各点的流函数值相等(2) 各点的流函数值沿程增大(3) 各点的流函数值沿程减小 (4) 不能确定（三）简述题（本大题2小题, 每小题8分, 共16分）1．正激波前后，密度、压强和气流速度有何变化？（8分）2．简述绕流阻力的组成及影响因素。

（8分）第 1 页共 3 页第 2 页共 3 页第 3 页共 3 页。

华北水利水电大学电机学考试试卷及参考答案3一、单项选择题（5’）1.异步电机运行时，定子绕组___。

A、短路B、开路C、接交流电源D、接直流电源答案：C2.三相异步电动机，启动时电抗器___定子回路。

A、并联入B、串联入C、切除并联D、切除串联答案：B3.TDK系列同步电机是___。

A、防护式B、开启式C、封闭式D、立式答案：B4.TD系列同步电机是___。

A、防护式B、开启式C、封闭式D、立式答案：A5.TDG系列同步电机是___。

A、防护式B、开启式C、封闭式D、立式答案：C6.直流电机调速时，如果保持其电枢电流为额定值，则称为___。

A、恒功率调速B、恒转矩调速C、弱磁调速D、恒调速答案：A7.电力系统中测量大电流的变压器叫做____。

A、自耦变压器B、电压互感器C、电流互感器D、双绕组变压器答案：C8.异步电机的转速总是___同步转速。

A、大于B、小于C、等于D、不一定答案：B9.对直流电动机而言，其电枢线圈里的电流方向是___的，产生的电磁转矩是的。

A、单方向，单方向B、交变，单方向C、单方向，交变D、交变，交变答案：B10.三相异步电动机直接启动的启动电流___，使供电变压器二次电压下降___。

A、小，大B、大，大C、大，小D、小，小答案：B二、多项选择题（5’）1.他励直流电动机启动方法有___。

A、直接启动B、星角启动C、电枢回路串电阻启动D、降电压启动答案：ACD2.直流电力拖动系统中的直流电动机有___。

A、并励B、串励C、他励D、复励答案：ABCD3.从变压器的短路试验可以求出___。

A、变比kB、铁损C、铜损D、短路阻抗答案：CD4.调速的性能指标主要有___。

A、调速范围B、静差率C、调速的平滑性D、调速的经济型答案：ABCD5.异步电机的优点是___。

A、结构简单B、价格低廉C、运行可靠D、适用性强答案：ABCD6.积复励直流电机的机械特性特点为___。

A、不允许空载运行B、启动转矩大C、过载倍数强D、是一条斜直线答案：BC7.三相异步电机调速的方法有___。

考研英语新题型全真试题（2005-2008）2005Part BDirections:In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of the numbered blanks. There are two extra choices, which do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. (10 points)Canada’s premiers (the leaders of provincial governments), if they have any breath left after complaining about Ottawa at their late July annual meeting, might spare a moment to do something, together, to reduce health-care costs.They’re all groaning about soaring health budgets, the fastest-growing component of which are pharmaceutical costs.41. ________What to do? Both the Romanow commission and the Kirby committee on health care -- to say nothing of reports from other experts -- recommended the creation of a national drug agency. Instead of each province having its own list of approved drugs, bureaucracy, procedures and limited bargaining power, all would pool resources, work with Ottawa, and create a national institution.42. ________But “national” doesn’t have to mean that. “National” could mean interprovincial -- provinces combining efforts to create one body.Either way, one benefit of a “national” organization would be to negotiate better prices, if possible, with drug manufacturers. Instead of having one province -- or a series of hospitals within a province -- negotiate a price for a given drug on the provincial list, the national agency would negotiate on behalf of all provinces.Rather than, say, Quebec, negotiating on behalf of seven million people, the national agency would negotiate on behalf of 31 million people. Basic economics suggests the greater the potential consumers, the higher the likelihood of a better price.43. ________A small step has been taken in the direction of a national agency with the creation of the Canadian Coordinating Office for Health Technology Assessment, funded by Ottawa and the provinces. Under it, a Common Drug Review recommends to provincial lists which new drugs should be included. Predictably, and regrettably, Quebec refused to join.A few premiers are suspicious of any federal-provincial deal-making. They (particularly Quebec and Alberta) just want Ottawa to fork over additional billions with few, if any, strings attached. That’s one reason why the idea of a national list hasn’t gone anywhere while drug costs keep rising fast.44. ________Premiers love to quote Mr. Romanow’s report selectively, especially the partsabout more federal money. Perhaps they should read what he had to say about drugs: “A national drug agency would provide governments more influence on pharmaceutical companies in order to constrain the ever-increasing cost of drugs.”45. ________So when the premiers gather in Niagara Falls to assemble their usual complaint list, they should also get cracking about something in their jurisdiction that would help their budgets and patients.[A] Quebec’s resistance to a national agency is provincialist ideology. One of thefirst advocates for a national list was a researcher at Laval University.Quebec’s Drug Insurance Fund has seen its costs skyrocket with annualincreases from 14.3 per cent to 26.8 per cent![B] Or they could read Mr. Kirby’s report: “the substantial buying power of suchan agency would strengthen the public prescription-drug insurance plans tonegotiate the lowest possible purchase prices from drug companies.”[C] What does “national”mean? Roy Romanow and Senator Michael Kirbyrecommended a federal-provincial body much like the recently createdNational Health Council.[D] The problem is simple and stark: health-care costs have been, are, and willcontinue to increase faster than government revenues.[E] According to the Canadian Institute for Health Information, prescription drugcosts have risen since 1997 at twice the rate of overall health-care spending.Part of the increase comes from drugs being used to replace other kinds oftreatments. Part of it arises from new drugs costing more than older kinds.Part of it is higher prices.[F] So, if the provinces want to run the health-care show, they should prove theycan run it, starting with an interprovincial health list that would endduplication, save administrative costs, prevent one province from beingplayed off against another, and bargain for better drug prices.[G] Of course the pharmaceutical companies will scream. They like divided buyers;they can lobby better that way. They can use the threat of removing jobs fromone province to another. They can hope that, if one province includes a drugon its list, the p ressure will cause others to include it on theirs. They wouldn’tlike a national agency, but self-interest would lead them to deal with it.2006Part BDirections:In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of the numbered blanks. There are two extra choices, which do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. (10 points)On the north bank of the Ohio River sits Evansville, Ind., home of David Williams, 52, and of a riverboat casino where gambling games are played. During several years of gambling in that casino, Williams, a state auditor earning $35,000 a year, lost approximately $175,000. He had never gambled before the casino sent him a coupon for $20 worth of gambling.He visited the casino, lost the $20 and left. On his second visit he lost $800. The casino issued to him, as a good customer, a Fun Card, which when used in the casino earns points for meals and drinks, and enables the casino to track the user’s gambling activities. For Williams, these activities become what he calls electronic morphine.(41) ________. In 1997 he lost $21,000 to one slot machine in two days. In March 1997 he lost $72,186. He sometimes played two slot machines at a time, all night, until the boat locked at 5 a.m., then went back aboard when the casino opened at 9 a.m. Now he is suing the casino, charging that it should have refused his patronage because it knew he was addicted. It did know he had a problem.In March 1998, a friend of Williams’s got him involuntarily confined to a treatment center for addictions, and wrote to inform the casino of Williams’s gambling problems. The casino included a photo of Williams among those of banned gamblers, and wrote to him a “cease admissions” letter. Noting the medical/psychological nature of problem gambling behaviors, the letter said that before being readmitted to the casino he would have to present medical/psychological information demonstrating that patronizing the casino would pose no threat to his safety or well-being.(42) ________.The Wall Street Journal reports that the casino has 20 signs warning: “Enjoy the fun... and always bet with your head, not over it.” Every entrance ticket lists a toll-free number for counseling from the Indiana Department of Mental Health. Nevertheless, Williams’s suit charges that the casino, knowing he was “helplessly addicted to gambling,” intentionally worked to “l ur e” him to “engage in conduct against his will.” Well.(43) ________.The fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) says “pathological gambling”involves persistent, recurring and uncontrollable pursuit less of money than of thrill of taking risks in quest of a windfall.(44) ________. Pushed by science, or what claims to be science, society is reclassifying what once were considered character flaws or moral failings as personality disorders akin to physical disabilities.(45) ________.Forty-four states have lotteries, 29 have casinos, and most of these states are to varying degrees dependent on -- you might say addicted to -- revenues from wagering.And since the first Internet gambling site was created in 1995, competition for gambler s’ dollars has become intense. The Oct. 28 issue of Newsweek reported that 2 million gamblers patronize 1,800 virtual casinos every week. With $3.5 billion being lost on Internet wagers this year, gambling has passed pornography as the Web’s most profitable business.[A] Although no such evidence was presented, the casino’s marketing departmentcontinued to pepper him with mailings. And he entered the casino and usedhis Fun Card without being detected.[B] It is unclear what luring was required, given his compulsive behavior. And inwhat sense was his will operative?[C] By the time he had lost $5,000 he said to himself that if he could get back toeven, he would quit. One night he won $5,500, but he did not quit.[D] Gambling has been a common feature of American life forever, but for a longtime it was broadly considered a sin, or a social disease. Now it is a socialpolicy: the most important and aggressive promoter of gambling in Americais government.[E] David Williams’s suit should trouble this gambling nation. But don’t bet on it.[F] It is worrisome that society is medicalizing more and more behavioralproblems, often defining as addictions what earlier, sterner generationsexplained as weakness of will.[G] The anonymous, lonely, undistracted nature of online gambling is especiallyconductive to compulsive behavior. But even if the government knew how tomove against Internet gambling, what would be its grounds for doing so?2007Part BDirections:In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of the numbered blanks. There are two extra choices, which do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. (10 points)A. Set a Good Example for Your KidsB. Build Your Kids’ Work SkillsC. Place Time Limits on Leisure ActivitiesD. Talk about the Future on a Regular BasisE. Help Kids Develop Coping StrategiesF. Help Your Kids Figure Out Who They AreG. Build Your Kids’ Sense of ResponsibilityHow Can a Parent Help?Mothers and fathers can do a lot to ensure a safe landing in early adulthood for their kids. Even if a job’s starting salary seems too small to satisfy an emerging adult’s need for rapid content, the transition from school to work can be less of a setback if the start-up adult is ready for the move. Here are a few measures, drawn from my book Ready or Not, Here Life Comes, that parents can take to prevent what call “work-life unreadiness.”41You can start this process when they are 11 or 12. Periodically review their emerging strengths and weaknesses with them and work together on any shortcomings, like difficulty in communicating well or collaborating. Also, identify the kinds of interests they keep coming back to, as these offer clues to the careers that will fit them best.42Kids need a range of authentic role models – as opposed to members of their clique, pop stars and vaunted athletes. Have regular dinner-table discussions about people the family knows and how they got where they are. Discuss the joys and downsides of your own career and encourage your kids to form some ideas about their own future. When asked what they want to do, they should be discouraged from saying “I have no idea.” They can change their minds 200 times, but having only a foggy view of the future is of little good.43Teachers are responsible for teaching kids how to learn; parents should be responsible for teaching them how to work. Assign responsibilities around the houseand make sure homework deadlines are met. Encourage teenagers to take a part-time job. Kids need plenty of practice delaying gratification and deploying effective organizational skills, such as managing time and setting priorities.44Playing video games encourages immediate content. And hours of watching TV shows with canned laughter only teaches kids to process information in a passive way. At the same time, listening through earphones to the same monotonous beats for long stretches encourages kids to stay inside their bubble instead of pursuing other endeavors. All these activities can prevent the growth of important communication and thinking skills and make it difficult for kids to develop the kind of sustained concentration they will need for most jobs.45They should know how to deal with setbacks, stress and feeling of inadequacy. They should also learn how to solve problems and resolve conflicts, ways to brainstorm and think critically. Discussions at home can help kids practice doing these things and help them apply these skills to everyday life situations.What about the son or daughter who is grown but seems to be struggling and wandering aimlessly through early adulthood? Parents still have a major role to play, but now it is more delicate. They have to be careful not to come across as disappointed in their child. They should exhibit strong interest and respect for whatever currently interests their fledging adult (as naive or ill conceived as it may seem) while becoming a partner in exploring options for the future. Most of all, these new adults must feel that they are respected and supported by a family that appreciates them.2008Part BDirections:In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of the numbered blanks. There are two extra choices, which do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. (10 points)The time for sharpening pencils, arranging your desk, and doing almost anything else instead of writing has ended. The first draft will appear on the page only if you stop avoiding the inevitable and sit, and stand up, or lie down to write. (41) __________. Be flexible. Your outline should smoothly conduct you from one point to the next, but do not permit it to railroad you. If a relevant and important idea occurs to you now, work it into the draft. (42) ________Grammar, punctuation, and spelling can wait until you revise. Concentrate on what you are saying. Good writing most often occurs when you are in hot pursuit of an idea rather than in a nervous search for errors.(43) ________Your pages will be easier to keep track of that way, and ,if you have to clip a paragraph to place it elsewhere, you will not lose any writing on the other side.It you are working on a word processor, you can take advantage of its capacity to make additions and deletions as well as move entire paragraphs by making just a few simple keyboard commands. Some software programs can also check spelling and certain grammatical elements in your writing. (44) ________ .These printouts also easier to read than the screen when you work on revisions.Once you have a first draft on paper, you can delete material that is unrelated to your thesis and add material necessary to illustrate your points and make your paper convincing. The students who wrote “ The A & P as a State of Mind” wisely dropped a paragraph that questioned whether Sammy displays chauvinistic attitudes toward women. (45) ________Remember that your initial draft is only that. You should go through the paper many times “and then again” working to substantiate an clarify your ideas. You may even end up with several entire versions of the paper. Rewrite. The sentences within each paragraph should be related to a single topic. Transitions should connect one paragraph to the next so that there are no abrupt or confusing shifts. Awkward or wordy phrasing or unclear sentences and paragraphs should be mercilessly poked and prodded into shape.A)To make revising easier, leave wide margins and extra space between linesso that you can easily add words, sentences, and corrections. Write on onlyone side of the paper.B)After you have clearly and adequately, developed the body of your paper,pay particular attention to the introductory and concluding paragraphs. It’sprobably best to write the introduction last, after you know precisely whatyou are introducing. Concluding paragraphs demand equal attentionbecause they leave the reader with a final impression.C)It’s worth remembering, however, that though a clean copy fresh off aprinter may look terrific, it will read only as well as the thinking and writingthat have gone into it. Many writers prudently store their data on disks and print their pages each time they finish a draft to avoid losing any material because of power failures or other problems.D)It make no difference how you write, just so you do. Now that you havedeveloped a topic into a tentative thesis, you can assemble your notes an begin to flesh out whatever outline you have made.E)Although this is an interesting issue, it has nothing to do with the thesis,which explains how the setting influences Sammy’s decision to quit his job.Instead of including that paragraph, she added one that described crabbed response to the girls so that she could lead up to the A & P “policy” he enforces.F)In the final paragraph about the significance of the setting in “A & P”, thestudent brings together the reasons Sammy quit his job by referring to his refusal to accept store policies.G)By using the first draft as a means of thinking about what you want to say,you will very likely discover more than your notes originally suggested.Plenty of good writers don’t use outlines at all but discover ordering principles as they write. Do not attempt to compose a perfectly correct draft the first time around.2009Coinciding with the groundbreaking theory of biological evolution proposed by British naturalist Charles Darwin in the 1860s, British social philosopher Herbert Spencer put forward his own theory of biological and cultural evolution. Spencer argued that all worldly phenomena, including human societies, changed over time, advancing toward perfection. 41.____________.American social scientist Lewis Henry Morgan introduced another theory of cultural evolution in the late 1800s. Morgan, along with Tylor, was one of the founders of modern anthropology. In his work, he attempted to show how all aspects of culture changed together in the evolution of societies.42._____________.In the early 1900s in North America, German-born American anthropologist Franz Boas developed a new theory of culture known as historical particularism. Historical particularism, which emphasized the uniqueness of all cultures, gave new direction to anthropology. 43._____________ .Boas felt that the culture of any society must be understood as the result of a unique history and not as one of many cultures belonging to a broader evolutionary stage or type of culture. 44._______________.Historical particularism became a dominant approach to the study of culture in American anthropology, largely through the influence of many students of Boas. But a number of anthropologists in the early 1900s also rejected the particularist theory of culture in favor of diffusionism. Some attributed virtually every important cultural achievement to the inventions of a few, especially gifted peoples that, according to diffusionists, then spread to other cultures. 45.________________.Also in the early 1900s, French sociologist ?mile Durkheim developed a theory of culture that would greatly influence anthropology. Durkheim proposed that religious beliefs functioned to reinforce social solidarity. An interest in the relationship between the function of society and culture—known as functionalism—became a major theme in European, and especially British, anthropology.[A] Other anthropologists believed that cultural innovations, such as inventions, had a single origin and passed from society to society. This theory was known as diffusionism.In order to study particular cultures as completely as possible, Boas became skilled in linguistics, the study of languages, and in physical anthropology, the study of human biology and anatomy.[C] He argued that human evolution was characterized by a struggle he called the “survival of the fittest,” in which weaker races and societies must eventually be replaced by stronger, more advanced races and societies.[D] They also focused on important rituals that appeared to preserve a people’s social structure, such as initiation ceremonies that formally signify children’s ent rance into adulthood.[E] Thus, in his view, diverse aspects of culture, such as the structure of families, forms of marriage, categories of kinship, ownership of property, forms of government, technology, and systems of food production, all changed as societies evolved.[F]Supporters of the theory viewed as a collection of integrated parts that work together to keep a society functioning.[G] For example, British anthropologists Grafton Elliot Smith and W. J. Perry incorrectly suggested, on the basis of inadequate information, that farming, pottery making, and metallurgy all originated in ancient Egypt and diffused throughout the world. In fact, all of these cultural developments occurred separately at different times in many parts of the world.2010Part BDirections:In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of the numbered blanks. There are two extra choices, which do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. (10 points)[A] The first and more important is the consumer’s growing preference for eating out; the consumption of food and drink in places other than homes has risen from about 32 percent of total consumption in 1995 to 35 percent in 2000 and is expected to approach 38 percent by 2005. This development is boosting wholesale demand from the food service segment by 4 to 5 percent a year across Europe, compared with growth in retail demand of 1 to 2 percent. Meanwhile, as the recession is looming large, people are getting anxious. They tend to keep a tighter hold on their purse and consider eating at home a realistic alternative.[B] Retail sales of food and drink in Europe’s largest markets are at a standstill, leaving European grocery retailers hungry for opportunities to grow. Most leading retailers have already tried e-commerce, with limited success, and expansion abroad. But almost all have ignored the big, profitable opportunity in their own backyard: the wholesale food and drink trade, which appears to be just the kind of market retailers need.[C] Will such variations bring about a change in the overall structure of the food and drink market? Definitely not. The functioning of the market is based on flexible trends dominated by potential buyers. In other words, it is up to the buyer, rather than the seller, to decide what to buy .At any rate, this change will ultimately be acclaimed by an ever-growing number of both domestic and international consumers, regardless of how long the current consumer pattern will take hold.[D] All in all, this clearly seems to be a market in which big retailers could profitably apply their scale, existing infrastructure and proven skills in the management of product ranges, logistics, and marketing intelligence. Retailers that master the intricacies of wholesaling in Europe may well expect to rake in substantial profits thereby. At least, that is how it looks as a whole. Closer inspection reveals important differences among the biggest national markets, especially in their customer segments and wholesale structures, as well as the competitive dynamics of individual food and drink categories. Big retailers must understand these differences before they can identify the segments of European wholesaling in which their particular abilities might unseat smaller but entrenched competitors. New skills and unfamiliar business models are needed too.[E] Despite variations in detail, wholesale markets in the countries that have been closely examined—France, Germany, Italy, and Spain—are made out of the same building blocks. Demand comes mainly from two sources: independent mom-and-pop grocery stores which, unlike large retail chains, are two small to buy straight from producers, and food service operators that cater to consumers when they don’t eat at home. Such food service operators range from snack machines to large institutional catering ventures, but most of these businesses are known in the trade as “horeca”: hotels, restaurants, and cafes. Overall, Europe’s wholesale market for food and drink isgrowing at the same sluggish pace as the retail market, but the figures, when added together, mask two opposing trends.[F] For example, wholesale food and drink sales come to $268 billion in France, Germany, Italy, Spain, and the United Kingdom in 2000—more than 40 percent of retail sales. Moreover, average overall margins are higher in wholesale than in retail; wholesale demand from the food service sector is growing quickly as more Europeans eat out more often; and changes in the competitive dynamics of this fragmented industry are at last making it feasible for wholesalers to consolidate.[G] However, none of these requirements should deter large retailers (and even some large good producers and existing wholesalers) from trying their hand, for those that master the intricacies of wholesaling in Europe stand to reap considerable gains.41 →42→43→44→E→452011Part BDirections:In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list A-G to fit into each of the numbered blanks. There are two extra choices, which do not fit in any of the gaps. Mark your answers on ANSWER SHEET 1. (10 points)[A] No disciplines have seized on professionalism with as much enthusiasm as the humanities. You can, Mr Menand points out, became a lawyer in three years and a medical doctor in four. But the regular time it takes to get a doctoral degree in the humanities is nine years. Not surprisingly, up to half of all doctoral students in English drop out before getting their degrees.[B] His concern is mainly with the humanities: Literature, languages, philosophy and so on. These are disciplines that are going out of style: 22% of American college graduates now major in business compared with only 2% in history and 4% in English. However, many leading American universities want their undergraduates to have a grounding in the basic canon of ideas that every educated person should posses. But most find it difficult to agree on what a “general education” should look like. At Harvard, Mr Menand notes, “the great books are read because they have beenread”-they form a sort of social glue.[C] Equally unsurprisingly, only about half end up with professorships for which they entered graduate school. There are simply too few posts. This is partly because universities continue to produce ever more PhDs. But fewer students want to study humanities subjects: English departments awarded more bachelor’s degrees in 1970-71 than they did 20 years later. Fewer students requires fewer teachers. So, at the end of a decade of theses-writing, many humanities students leave the profession to do something for which they have not been trained.[D] One reason why it is hard to design and teach such courses is that they can cut across the insistence by top American universities that liberal-arts educations and professional education should be kept separate, taught in different schools. Many students experience both varieties. Although more than half of Harvard undergraduates end up in law, medicine or business, future doctors and lawyers must study anon-specialist liberal-arts degree before embarking on a professional qualification.[E] Besides professionalizing the professions by this separation, top American universities have professionalised the professor. The growth in public money for academic research has speeded the process: federal research grants rose fourfold between 1960and 1990, but faculty teaching hours fell by half as research took its toll. Professionalism has turned the acquisition of a doctoral degree into a prerequisite for a successful academic career: as late as 1969a third of American professors did not possess one. But the key idea behind professionalisation, argues Mr Menand, is that “the knowledge and skills needed for a particular specialization are transmissible but not transferable.”So disciplines acqui re a monopoly not just over the production of knowledge, but also over the production of the producers of knowledge.[F] The key to reforming higher education, concludes Mr Menand, is to alter the way in which “the producers of knowledge are produced.”Othe rwise, academics will。

华北水利水电大学机电控制工程基础考试试卷及参考答案3一、单项选择题（5’）1.控制系统中，基本环节的划分，是根据（ ）。

A 、元件或设备形式B 、系统的物理结构C 、环节的连接方式D 、环节的数学模型答案：D2.若受控对象存在较大的延迟和惯性，效果较好的控制方式是（ ）。

A 、比例环节B 、积分环节C 、比例微分控制D 、比例积分控制答案：C3.已知道系统输出的拉氏变换为()22)(n n s s s Y ωω+=,那么系统处于（ ）。

A 、欠阻尼B 、过阻尼C 、临界阻尼D 、无阻尼答案：C4.控制系统的稳态误差反映了系统的（ ）。

A 、稳态误差精度B 、相对稳定性C 、快速性D 、平稳性答案：A5.若系统的特征方程为s^2+4s+1=0，则此系统的稳定性为（ ）。

A 、稳定C 、不稳定D 、无法判断答案：B6.一阶系统的传递函数为153+s ；其单位阶跃响应为（ ）。

A 、51te --B 、533te --C 、555te --D 、53te --答案：B7.t a t f =)(的Z 变换)(z F 为（ ）。

A 、T a z z+B 、T a z -1C 、T a z z-D 、T a -11答案：C8.决定系统静态性能和动态性能的是系统传递函数的（ ）。

A 、零点和极点B 、零点和传递系数C 、极点和传递系数D 、零点、极点和传递系数答案：D9.令线性定常系统的传递函数的分母多项式为零，则可得系统的（ ）。

B、特征方程C、差分方程D、状态方程答案：B10.没有稳态误差的系统称为（）。

A、恒指系统B、无差系统C、有差系统D、随动系统答案：A11.线性系统和非线性系统的根本区别在于（）。

A．线性系统有外加输入，非线性系统无外加输入B．线性系统无外加输入，非线性系统有外加输入C．线性系统满足迭加原理，非线性系统不满足迭加原理D．线性系统不满足迭加原理，非线性系统满足迭加原理答案：C12.对复杂的信号流图直接求出系统的传递函数可以采用（）。

附表二
华北水利水电大学
2021年硕士研究生入学考试初试科目考试大纲
机械工程材料科目（科目代码：925）考试大纲
考试形式和试卷结构
一、试卷分值及考试时间
考试时间180分钟（3个小时），满分150分。

二、考试基本要求
本考试大纲适用于报考华北水利水电大学机械专业学位下设的先进材料与成型控制技术培养方向的专业型硕士研究生入学考试。

机械工程材料考试是为招收上述学科培养方向的硕士研究生而设置的具有选拔功能的水平考试。

其目的是科学、公平、有效地测试学生大学本科阶段对机械工程材料知识的掌握情况，以保证被录取者具有基本的专业基础，并便于学校优选拔。

三、试卷内容及结构
《机械工程材料》包括材料的结构与组成、材料的力学行为、二元合金相图与相变基础、金属材料的改性（金属热处理原理与工艺）、工业用钢及铸铁等5个部分。

1.材料的结构与组成（15%）.
2.材料的力学行为（15%）.
3.二元合金相图与相变基础（25%）.
4.金属材料的改性（金属热处理原理与工艺）（25%）.
5.工业用钢及铸铁（20%）.
四、试卷题型结构
主要题型有：选择、填空题（30分）；简答、简述题（60分）；综合、计算题（60分）。

试卷满分为150分。

命题学院（签盖）：
2020年6月30日。