北京理工大学 北理工 2006年信号与系统 考研真题及答案解析
北理工《信号与系统》习题答案第2章答案(纯手写)
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(NEW)北京理工大学信息与电子学院《826信号处理导论》历年考研真题汇编
2006年北京理工大学426信号处理 导论考研真题
2005年北京理工大学426信号处理 导论考研考研真题
2003年北京理工大学426信号处理 导论考研真题
2002年北京理工大学411信号与系 统考研真题
2012年北京理工大学826信号处理 导论考研真题
2011年北京理工大学826信号处理 导论考研真题
2009年北京理工大学826信号处理 导论考研真题
2008年北京理工大学826信号处理 导论考研真题
2007年北京理工大学426信号处理 导论考研真题
2001年北京理工大学411信号与系 统考研真题
2000年北京理工大学411信号与系 统考研真题
目 录
2012年北京理工大学826信号处理导论考研真题 2011年北京理工大学826信号处理导论考研真题 2009年北京理工大学826信号处理导论考研真题 2008年北京理工大学826信号处理导论考研真题 2007年北京理工大学426信号处理导论考研真题 2006年北京理工大学426信号处理导论考研真题 2005年北京理工大学426信号处理导论考研真题 2004年北京理工大学426信号处理导论考研真题 2003年北京理工大学426信号处理导论考研真题 2002年北京理工大学411信号与系统考研真题 2001年北京理工大学411信号与系统考研真题 2000年北京理工大学411信号与系统考研真题
北京理工大学 北理工 2006年管理学 考研真题及答案解析
北京理工大学2006年攻读硕士学位研究生入学考试试题科目代码： 471 科目名称：管理学一、名词解释(每小题4分，共20分)1、战略计划2、分工与协作原则3、全面质量管理4、沟通5、控制二、单项选择题(每小题3分，共30分)1、YSC是一家英国公司，并正在准备上市，该公司擅长找出成功管理者的性格特征及共同点。
他们通过大量调查发现，成功的中小企业家具备的诸多特征中有这样一条：对事对人充满热诚，希望企业改善，满足感在乎对企业进行优越的改变，却不在乎地位及金钱。
这一分析结论令国内一些中小企业家不服，不相信管理层不是以金钱为主要目标。
请问以下哪种说法最能解释这一现象?A．按照马斯洛的理论，人们的需求存在多种层次，金钱对有些人来说需要，对有些人来说不需要。
B．按照赫兹伯格的双因素理论，金钱确实是激励因素，该公司的调查结果有问题。
C．不同的地域文化，不同的经济发展水平，不同的价值观会对不同的人的需求产生不同的影响。
D．国外的一些调查往往和国外的一些理论一样，不适合中国，没有必要盲目借鉴和照搬。
2、张斌的专业是艺术设计，却在公司的生产部门工作。
近来销售部的经理提出把所有印刷品的设计任务都交给张斌来做，包括宣传手册、产品目录、海报，甚至报纸或杂志上的广告。
张斌很想有这样一个发挥自己艺术设计专长的机会。
而他所在的生产部门经理了解到他想离开的想法后说：“你是我们这儿很有价值的一位员工，我想我们肯定能做些什么，让你留下来。
公司有一个大的营销部门并不意味着我的部门就不能做一些专业的营销工作。
我给你一些附带的工作，比如，为我们的产品设计包装，怎么样?这不就能发挥你的艺术特长了吗?”如果你是该公司总经理，刚刚在某高校进修了管理学课程，你会如何看待这件事? A．生产部门经理为了能迎合张斌的喜好，对部门的工作进行一些不太恰当的调整。
B．生产部门经理为了挽留人才，调整部门工作，符合因人设职的管理原则。
C．生产部门经理没有学过马斯洛需要层次论。
北京理工大学信号与系统考研复习题
目录目录 (1)复习题一 (2)答案 (4)复习题二 (8)答案 (13)复习题三 (25)答案 (40)复习题四 (71)答案 (72)复习题五 (74)答案 (81)复习题六 (96)答案 (97)复习题七 (99)复习题八 (108)复习题一1.1 选择题（每小题可能有一个或几个正确答案，将正确的题号填入[ ]内） 1．f （5-2t ）是如下运算的结果————————（ ） （1）f （-2t ）右移5 （2）f （-2t ）左移5 （3）f （-2t ）右移25 （4）f （-2t ）左移251.2 是非题（下述结论若正确，则在括号内填入√，若错误则填入×） 1．偶函数加上直流后仍为偶函数。
（ ）2. 不同的系统具有不同的数学模型。
（ ）3. 任何信号都可以分解为偶分量与奇分量之和。
（ ） 4．奇谐函数一定是奇函数。
（ ） 5．线性系统一定满足微分特性 （ ）1.3 填空题1．=⋅t t cos )(δ=+t t 0cos )1(ωδ=-⋅)(cos )(0τωδt t=--)2()cos 1(πδt t=--⎰∞∞-dt t t )2()cos 1(πδ ⎰+∞∞-=⋅tdt t cos )(δ⎰+∞∞-=tdt t 0cos )(ωδ ⎰∞-=td ττωτδ0cos )(⎰+∞∞-=+tdt t 0cos )1(ωδ⎰∞-=+td ττωτδ0cos )1(2．=⋅-at e t )(δ=⋅-t e t )(δ⎰∞--=td e ττδτ)(⎰∞∞--=--dt t e t t )1(][22δ⎰∞∞--=dt e t at )(δ1.4 简答题1．画出题图一所示信号f （t ）的偶分量f e （t ）与奇分量f o （t ）。
图一2．)(t f 如图二所示，试画出)(t f 的偶分量)(t f e 和奇分量()o f t 的波形。
t图二3．某线性时不变系统在零状态条件下的输入e （t ）与输出r （t ）的波形如题图三所示，当输入波形为x （t ）时，试画出输出波形y （t ）。
北京理工大学真题2006年(含答案)
北京理工大学2006年Part ⅠReading Comprehension (40 points)Directions: In this part there are four passages for you to read. After each passage there are five questions, below each of whom there are four answers marked A, B, C and D. Chouse the best answer and mark the corresponding letter with a pencil on the Machine-Scoring Answer Sheet with a single line through the center.Passage OneI was introduced to the concept of literacy animator in Oladumi Arigbede's (1994) article on high illiteracy rates among women and school dropout rates among girls. According to Arigbede, literacy animators view their role as assisting in the self-liberating development of people in the world who are struggling for a more meaningful life. Animators are a family of deeply concerned and committed people whose gut-level rejection of mass human pauperization compels them to intervene on the side of the marginalized. Their motivation is not derived from a love of literacy as merely another technical life skill, and they accept that literacy is never culturally or ideologically neutral.Arigbede writes from her experiences as an animator working with women and men in Nigeria. She believes that literacy animators have to make a clear choice about whose culture and whose ideology will be fostered among those with whom they work. Do literacy educators in the United States consider whether the instruction they pursue conflicts with their students' traditional cultures or community, or fosters illiteracies in learners' first or home languages or dialects and. in their orality?Some approaches to literacy instruction represent an ideology of individualism, control, and competition. Consider, for example, the difference in values conveyed and represented when students engage in choral reading versus the practice of having one student read out loud to the group. To identify as a literacy animator is to choose the ideology of "sharing, solidarity, love, equity, co-operation with and respect of both nature and other human beings". Literacy pedagogy that matches the animator ideology works on maintaining the languages and cultures of millions of minority children who at present are being forced to accept the language and culture of the dominant group. It might lead to assessment that examines the performance outcomes of a community of literacy learners and the social significance of their uses of literacy, as opposed to measuring what an individual can do as a reader and writer on a standardized test. Shor (1993) describes literacy animators as problerm-posing, community-based, dialogic educators. Do our teacher-education textbooks on reading and language arts promote the idea that teachers should explore problems from a community-based dialogic perspective?1. A literacy animator is one who ______.A. struggles for a more meaningful lifeB. frees people from poverty and illiteracyC. is committed to marginalize the illiterateD. is concerned with what is behind illiteracy2. The author suggests that literacy educators in the US in a way ______.A. promote students' home languagesB. force students to accept their cultureC. teach nothing but reading and writingD. consider literacy as of non-neutral nature3. Arigbede worked with Nigerians probably to ______.A. teach American customs and ideologyB. make a choice of culture to be fosteredC. reject the values of the dominant classD. help maintain Nigerian language and culture4. According to the author, "choral reading" may represent ______.A. individualismB. collectivismC. competitionD. immersion5. Animator ideology emphasizes more on ______.A. the social function of literacyB. students' performance in testsC. the dominant group's languageD. the attainment of life skillsPassage TwoAccording to one survey of 12, 000 people, about 30 percent of those making New Year's resolutions say they don't even keep them into February. And only about 1 in 5 actually stays on track for six months or more, reports eDiets, com, a consumer diet and fitness Web site.But don't let those odds make you reach for the nearest bag of potato chips. Experts say you can keep those resolutions long term, even if you're struggling now."The motivation comes from within, and so when you find that you're declining in your healthy eating program, and then just ask yourself, 'Is this going to get me the results that I want?'" says Leslie Stewart, a registered dietitian and licensed nutritionist."And if you're doing something every day to eat healthy, then that's going to pay off in the long run."Stewart advises to use what she calls the 90 -10 eating rule."If you're eating healthy 90 percent of the time, then 10 percent of the time, you can cut yourself some slack and eat pleasurably."She says she believes that "healthy eating is evolution instead of resolution."The same principle can be applied to a lagging exercise resolution, too.Staying motivated is key to long-term success, and reviewing original goals can help strengthen a weakening workout program.Adding variety to a fitness regime also can prevent you from hanging up those exercise shoes. After a few weeks of well-intentioned workouts, boredom may be creeping into your routine.Setting goals too high is another common mistake, "If you're not running a marathon at the end of the month, don't worry," said Mayo Clinic experts. A too intense workout—and the resulting pain and stiffness—is discouraging and may force most to abandon a program. Starting slowly is key.But if your goals already have fallen by the wayside, Uria says to start up again immediately."A little setback is OK; get back on the horse and ride... drive toward that goal," he says.6. According to the author, only about 20% people keeping their resolutions does not necessarily mean that ______.A. the figure is rather depressing and unexpected as wellB. those who have made their resolution should give up their effortC. whoever keep their resolutions should start eating potato chipsD. long-term resolutions are not important for those facing troubles7. What is the idea behind the 90-10 eating rule acording to the passage?A. You should keep eating healthy 90% of the time.B. You should feel to eat 10% of the time.C. You should learn to eat healthy gradually.D. Sudden change will be more efficient and effective.8. Which of the following you should avoid to keep yourself interested in exercise?A. Hanging up your exercise shoes if you feel tired.B. Keeping boredom away from your daily activity.C. Making a schedule with too high goals in it.D. Running a marathon at the beginning of the month.9. How many suggestions at least have been introduced concerning the exercise resolution?A. FourB. FiveC. SixD. Seven10. What is critically important in making long-lerm resolutions successful?A. You should be struggling with yourself all the time.B. You should constantly evaluate the results you want.C. You should try to keep yourself motivated.D. You should try your best to diversify your fitness practice.Passage ThreeOur present generation of cultural critics, arriving after the assault of postmodernism and the increasingly widespread commercialization of culture, has been cast adrift, without any firm basis for judgments. Publications and institutions to support serious criticism, in this view, either no longer exist or are few in number.Critics today, it is also claimed, are too cozy behind the ivied walls of academe, content to employ a prose style that is decipherable only to a handful of the cognoscenti. The deadly dive of Uniersity critics into the shallow depths of popular culture, moreover, reveals the unwillingness of these critics to uphold standards. Even if the reasons offered are contradictory, these Jeremiahs huddle around their sad conclusion that serious cultural criticism has fallen into a morass of petty bickering and bloated reputations.Such narratives of declension, a staple of American intellectual life since the time of the Puritans, are misplaced, self-serving, and historically inaccurate, so difficult to prove. Has the level of criticism declined in the last 50 years? Of coarse the logic of such an opinion depends on the figures that are being contrasted with one another. Any number of cultural critics thriving today could be invoked to demonstrate that cultural criticism is alive and well.But many new and thriving venues for criticism and debate exist today, and they are not limited solely t6 the discussion of literary works. Actually, they became so entrusted with their own certitude and political judgments that they beacme largely irrelevant. Today the complaint is that literary culture lacks civility. We live in an age of commercialism and spectacle. Writers seek the limelight, and one way to bask in it is to publish reviews that scorch the landscape, with Dale Peck as the famous, but not a typical case in point. Heidi Julavits, in an essay in The Believer, lamented the downfall of serious fiction and reviewing. She surveyed a literary culture that had embraced "snark", her term for hostile, self-serving reviews.The snark review, according to Julavits, eschews a serious engagement with literature in favor of a sound-bite approach, an attempt to turn the review into a form of entertainment akin to film reviews or restaurant critiques. A critic found cultural criticism to be in "critical condition". For him, the postmodern turn to theory, in its questioning of objectivity, cut the critical, independent ground out from under reviewers. The rise of chain bookstores and blockbuster best sellers demeaned literary culture, making it prey to the commercial values of the market and entertainment.The criticism does not seem discontinuous. Nor should we forget that civility rarely reigned in the circles of New York intellectuals. The art critic Clement Greenberg physically pummeled the theatre critic Lionel Abel after Abel rejected the view that Jean Wahl, the French philosopher, was anti-Semitic. Though Robert Peck has the reputation of a literary hatchet man, so far as I know his blows thus far have all been confined to the printed page.Cultural criticism has certainly changed over the years. The old day's of the critic who wielded unchallenged authority have happily passed. Ours is a more pluralistic age, one not beholden to a narrow literary culture. The democratization of criticism—as in the Amazon system of readers' evaluating books—is a messy affair, as democracy must be. But the solution to the problems of criticism in the present is best not discovered in the musty basements of nostalgia and sentiment for the cultual criticism of a half-century gone. Rather the solution is to recognize, as John Dewey did almost a century ago, that the problems of democracy demand more democracy, less nostalgia for a golden age that never was, and a spirit of openness to what is new and invigorating in our culture.11. What is the possible connection between cultural critics and publications and institutions?A. Cultural critics attack postmodernism and commercialization cherished by publications and institutions.B. Postmodernism and commercialization are attacked by the serious publications and institutions.C. Cultural criticism is short of judgments and will not exist without the support of publications and institutions.D. Publications and institutions show almost no interest in serious cultural criticism.12. How do the university critics like the serious cultural criticism?A. Cultural criticism is not serious enough when the articles are written in the cozy prose style.B. Popular culture is so prevailing that serious critics are not willing to keep to the shallow standards.C. Serious cultural criticism is full of insignificant quarrels and the public do not really trust it.D. Cultural critics have become so serious as to tell the stories imbued with American intellectual Puritanism.13. What is the author's opinion of the current complaint about the literary expansion into the other fields?A. When literary critics discuss issues with political judgments, their views are likely to be meaningless.B. It is reasonable for writers to seek limelight since we are living in the age of commercialism.C. Critics should be encouraged to write and publish poignant articles which would scorch the landscape.D. It is the critics' responsibility to lament the downfall of serious fiction and reviewing.14. What does "the snark review" refer to according to Heidi Julavits?A. Cultural reviews which are unfriendly and selfless.B. Literary reviews avoiding serious criticism.C. Entertainment reviews in the film industry.D. Postmodern reviews independent of objectivity.15. In order to find a way out the current dilemma for the cultunal criticism, the author suggests that ______.A. we should return to the old days when the critics passed their judgments without challengesB. pluralism should be held back, reinforcing the unchallenged authority in the literary criticismC. democriatic criticism should not be adopted because it is rather messy as proved in the Amazon systemD. we should encourage more democracy, dismiss nostalgia and cultivate an open attitudePassage FourIn July, almost unnoticed by the national press, a deadly bird virus arrived on a pheasant farm in Surrey. Experts from the Department for the Environment, Food and Rural Affairs (Defra) identified Newcastle disease, a virus usually mortal to turkeys and geese but not humans, in a flock of 9,000 pheasant chicks imported from France ahead of the shooting season.Within hours of the diagnosis, veterinary experts had swung into action, throwing up a 3km exclusion zone around the farm near Cobham and culling 10,000 birds. The carcasses were burned and premises cleaned to stop the virus escaping. It was four weeks before Defra's Veterinary Exotic Diseases Division felt it was safe for poultry move virus has reached Turkey, similar emergency plans are being readied by officials from Defra and other agencies. The scenario they are preparing for is that the H5Nlvirns, which so far has led to the culling of billions of chickens in south-east Asia and 60 human deaths, will soon arrive on these shores.What happens next depends on where the outbreak occurs, whether it can be contained, and most important of all—whether it mutates to become infectious between people. So far, only poultry workers or those directly exposed to chicken faeces or blood are thought to be at risk, though direct human-to-human transmission cannot be ruled out."Every time a new person gets infected with the virus there is a small chance that person will trigger a pandemic," said Neil Ferguson, a scientist at Imperial College, who has been running simulations on what might happen were H5N1 to reach Britain. "It's a very small chance, probably 1 in a 1,000, 1 in 10,00O or less."Should diseased birds reach Britain, the first step for veterinary officials would be to contain the outbreak as they did with Newcastle disease. An amber alert would be sounded and samples sent to the Veterinary Laboratory Agency (VLA) in Weybridge, Surrey. If lan Brown, the head of avian virology, there, confirms the cause of death as HSN1, the alert level will be raised to red and a whole series of emergency procedures, from quarantine,restriction of poultry movements to culling, will swing into action. Other agencies, such as the Department of Health—the Health Protection Agency and the Ministry of Defence, would be brought into the loop. In the event that the outbreak cannot be contained, Defra may have to consider mass culling programmes and the possibility of vaccination.At this point, with the risk of the virus spreading to human populations, the Department of Health would appoint a UK national influenza pandemic committee to coordinate the response of hospital trusts and local authorities. The Civil Contingency Secretariat (CCS) of the Cabinet will also be alerted and Cobra, the emergency committee which coordinates Whitehall's response to terrorism, readied for a possible breakdown in civil order.The Department of Health's pandemic preparedness plan published in March envisages as many as 54,000 Britons dying in the first few months of a flu pandemic. But in June, CCS officials warned that that could be an underestimate. The more likely figure, they said, was 700,000—a projection the Department of Health is expected to take on board when it updates its pandemic plan later this month.In the most serious case, officials estimate there would be as many death sin the 12 weeks of an epidemic as there usually are in a year. At the peak of the pandemic, 19,000 people would require hospital beds, prompting councils to requisition schools to accommodate the sick.To treat the dying, the government would begin drawing down its stockpiles of Tamiflu (药名), an anti-viral drug that treats flu. But with only 14m courses, enough for a quarter of the population, likely to be available, sooner or later rationing would have to be imposed, with health professionals and essential civil servants the first in line. The govenment would also come under pressure to release stores of its precious flu vaccine. At present there are contingency plans for just two to three million doses. But there is no guarantee that vaccines which protect against annual human flu strains will also work against H5N1.The consequences hardly bear thinking about. Earlier this year, in a dress rehearsal in the East Midlands codenames Operation Arctic Circle, officials quickly concluded that mass mortuaries would be needed to bury the dead. But no one knows whether, in the event of a pandemic, any of these measures will prove effective. John Avizienius, senior scientific officer at the RSPCA and a member of Defra's avian influenza stakeholder group, said: "All you can do is plan for the worst case scenario."The fear is that wild geese moving from western China to Siberia may have spread the virus to several species of ducks and gulls that briefly visit British shores on their annual migration north. These ducks, many of which may not show signs of illness, may be passing on the virus to poultry on British farms.In the hope that they are not, Defra and the Wildfowl and Wetland announced last week that they would be conducting tests on 11,000 wild birds—three times the normal level. "The risk of avian influenza spreading from eastern Russia to the UK via migrating birds is still low," said Defra's chief vet, Debby Reynolds. "However, we have said all along that we must remain on the look out."16. What does the "scenario" in Para. 2 mean to Turkey?A. Turkey will be exposed to the nationwide aggression of the deadly virus as the most severely attacked country on these shores.B. Turkey must kill billions of chicken and other kinds of poultry.C. Turkey has to be responsible for the arrival of HSN1 on these shores.D. All the veterinary experts in Turkey will soon swing into action.17. What is, according to Nell Ferguson, the possible risk of bird flu if one gets infected?A. Anyone's infection will trigger pandemic though it is probably one in ten thousand.B. That each time a person gets infected with the virus will cause an enormous pandemic bird-flu.C. The person infected with the virus will do great harm to people around him.D. It is impossible that the virus infection of a certain person will cause a national bird virus spreading.18. The change of alert colors from amber to red implies that ______.A. all poultry workers must leave their working places as soon as possible.B. the officials in the Department of Health must call for much more of international assistance.C. the most serious situation of bird-flu has appeared.D. the change of the color functions greatly as the weather reports do.19. What are the steps taken by the Department of Health of UK with the risk of the virus spreading to human population?A. The Department of Health required Civil Contingency Secretariat to publish documents for the pandemic preparedness.B. The Department of Health required the UK national committee to co-work with hospital trusts and local authorities.C. The Department of Health required Civil Contingency Secretariat to make a pandemic plan as soon as possible.D. The Department of Health requires every hospital to store Tamiflu, the precious flu vaccine.20. British government's fear of the wild geese from western China to Siberia is due to ______.A. the domestic ducks and gulls infected by the imported geese to Britain.B. the poultry on British farms has been infected by the immigrated wide geese.C. the migration of the wild geese every winter.D. British shores infected by the geese virus.Part ⅡTranslation (40 points)Part A Translate the following short paragraphs into Chinese. (20 points)21. Everyone has something they are ashamed of, afraid of or that they feel guilty about. Each of us, in our own way, has devised a neat little method of handling our dark side. We may know how to hide it. Few of us know how to heal it. When we refuse to admit what we have done in the past, we block out path to the future. No matter how terrible we think we are, how bad we belive we have been, how law we think we have fallen, we can clean our minds and begin again.22. We expend so much energy trying to fix who we are, we rarely get to know ourselves. If we realized how precious the gist of life is, we would not waste a moment trying to improve it. If we really understood how precious we are to the gift of life, we would not waste time trying to fix ourselves.23. We cannot draw to us more than we believe we are worth. Everything that happens to us and every choice we make is a reflection of what we believe about who we are. Our inspiration comes from our self-acceptance. Our motivation comes from our self-reliance. When we accept ourselves and rely on ourselves, we feel good about ourselves. When you feel good about something, you believe in it. When you believe in it, it will work for you!24. It is of little consequence what your past has been. What matters to you and for you is right now. It is not your concern what others may be saying or doing. When you are taking care of yourself, you have very little time to pay attention to others. People can love you or hate you, ignore you or dote on your every word. No matter what anyone else may think or do or say, it has very little impact on who you really are. It is only in your mind that you build or destroy the esteem for your "self". Selfesteem begins and ends with you. When you have it, you have it and no one can take it away from you.Part B Translate the following paragraph into English.现在，成千上万的美国人沉湎于对身材苗条的追求之中。
北京理工大学 2006 年电磁学(324)考研真题
北京理工大学2006 年攻读硕士学位研究生入学考试试题 科目代码: 324科目名称: 电磁学一、填空题（每题 6 分，共 30 分）1．真空中电磁波的传播速度大小是 ，它 （是，否）随参考系变化。
2．把单位正电荷从电偶极子轴线的中点 O 沿任意路径移到无穷远处，则静电力对它做的功为 。
Figure 13．在磁感应强度为 B 的均匀磁场中，作一个半径为 r 的半球面 S 。
S 的边界线所在平面的法线方向单位矢量 n 与 B 的夹角为 α，则通过 S 的磁通量为。
Figure 24．一段导线在垂直于均匀磁场的平面内运动，已知导线绕其一端以角速度 ω 转动时产生的电动势与导线以垂直于导线方向的速度 v 作平动时的电动势相同，则导线的长度为 。
5．加在平行板电容器极板上的电压的变化率为 611.010 V s -⨯⋅，在电容器内产生 1.0 A 的位移电流，则该电容器的电容量为 F μ。
二、计算题（每题 20 分，共 120 分）1．半径为 R 的半球面上均匀带电，电荷面密度 为 σ。
试求球心处的电场强度。
2．如 Figure 3 所示为一无限长带电体系，其横截面由两个半径分别为 1R 和 2R 的圆相交而成，而两圆中心相距为 a （12a R R <+）。
半径为 1R 的区域内充满电荷体密度为 ρ 的均匀正电荷，半径为 2R 的区域内充满电荷体密度为 ρ- 的均匀负电荷。
试求重叠区域内的电场强度。
3．半径为 R 的无限长圆柱形带电体的电荷体密度为 Ar （r R ≤），r 为带电体内一点到圆柱体轴线的距离，A 为常数。
选择距离圆柱体轴线为 L （L R >）处为电势能的零点，计算圆柱体内各点的电势。
4．如 Figure 4 所示，等边三角形平面回路 ACDA 放在磁感应强度为 B 的均匀磁场中，磁场方向垂直于回路平面。
回路上的 CD 段为滑动导线，它以匀速 v 远离 A 端运动，并始终保持回路是等边三角形。
信号与线性系统名校真题解析及典型题精讲精练
１．【北京理工大学】 已知 ｆ（ｔ）的波形如下图所示，试作出 ｆ（－２ｔ－１）的波形。
Ｄ．０ Ｄ．２ｆ（１）
Ｄ．－３
２．【中国矿业大学】 已知 ｆ（－０．５ｔ）的波形如图所示，画出 ｙ（ｔ） ＝ｆ（ｔ＋１）ε（－ｔ）的波形。
— ２—
３．【中国矿业大学】
若 ｆ（ｔ）是已录制声音的磁带，则下列叙述错误的是（ ）
Ａ．线性时不变系统
Ｂ．非线性时不变系统
Ｃ．线性时变系统
Ｄ．非线性时变系统
（２）某连续系统满足 ｙ（ｔ） ＝Ｔ[ ｆ（ｔ）] ＝ｔｆ（ｔ），其中 ｆ（ｔ）为输入信号，则该系统为（ ）
Ａ．线性时不变系统
Ｂ．非线性时不变系统
Ｃ．线性时变系统
Ｄ．非线性时变系统
３【北京航空航天大学】
判断下列叙述的正误，正确的打“√”，错误的打“×”。
Ａ．对于有界激励信号产生有界响应的系统是稳定系统
Ｂ．系统稳定性是系统自身的性质之一。
Ｃ．系统是否稳定与激励信号有关
Ｄ．当 ｔ趋于无穷大时，ｈ（ｔ）趋于有限值或 ０，则系统可能稳定。
— ４—
第二章 连续时间系统的时域分析
【考情分析】
本章的考题主要涉及连续时间系统的时域分析。 重点考点： １．ＬＴＩ系统的零输入响应，零状态响应和全响应 ２．单位冲激响应的求解 ３．卷积积分的定义、性质及应用
ｔ）ｅ－ｊ６ｔ ３
的频谱
Ｙ（ｊω）。
４．【江苏大学】
若实信号
ｆ（ｔ）的傅里叶变换为
Ｆ（ｊω） ＝Ｒ（ｊω）＋ｊＸ（ｊω），则信号
ｙ（ｔ） ＝
１[ ２
ｆ（ｔ）＋ｆ（－ｔ）]
的
傅里叶变换为 （ ）
— ９—
Ａ．２Ｒ（ｊω）
Ｂ．Ｒ（ｊω）
北京理工大学06年研究生入学考试量子力学试题及答案(5)
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北京理工大学2006年
一、（20分）若粒子势能由 V (x) 变为 V ( x) C ，其中 C 为 常数，讨论能量本征值和相应的本征函数的变化情况。 解： 势能不显含时间，粒子波函数满足定态薛定谔方程
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北理工06-08年历年真题讲解_自动化
北京理工大学自动化学院自动化专业——2006年真题及解析科目一：代码810 科目名称自动控制理论第 1 页 共 51 页一、真题北京理工大学2006年自动控制理论考试试题一、根轨迹方法 （25分）单位反馈系统如图1，其中()()21+=s s s G 。
为简便起见，图中用R 表示r(t)的Laplace 变换R(s)。
其余的符号和以后的图均采用这种简便记法。
（1）设()K s G c =,画出根轨迹图；（2）确定K 的值，使闭环系统单位阶跃响应的最大超调量为π-=e M p 。
计算相应的上升时间r t ； （3）设计控制器()()11++=Ts Ts K s G c c αα使最大超调量p M 保持不变，上升时间为83π=r t ，并使闭环系统尽可能地简单。
图1：单位反馈系统二、状态空间方法 （30分）第 2 页 共 51 页考虑系统 ⎪⎩⎪⎨⎧+=+=DuCx y BuAx x 。
（1）先设 ⎥⎥⎥⎦⎤⎢⎢⎢⎣⎡---=210100100a a a A （ⅰ）证明：若()()()2122101223,λλλλ≠--=+++=其中s s a s a s a s s f ，则可通过状态空间中的线性变换Tx x=ˆ，将状态空间表达式（1）变为⎪⎩⎪⎨⎧+=+=Du xC y u B x A x ˆˆˆˆˆˆ。
（2）其中 ⎥⎥⎥⎦⎤⎢⎢⎢⎣⎡==2211000ˆλλλJ A T 可取为 ⎥⎥⎥⎦⎤⎢⎢⎢⎣⎡=222221112101λλλλλT （ⅱ）设 ⎥⎥⎥⎦⎤⎢⎢⎢⎣⎡-=110001000A 求At Jt e e 和。
（ⅲ）A 同（ⅱ）， [][]100,011==C B T第 3 页 共 51 页判断系统的可控性和可观测性。
若系统不可控或不可观测，确定不可控或不可观测的模态；（ⅳ）A,B,C 同（ⅲ），D=0，()[]()t x x T,1110-=是状态方程在初态()0x 下的解，证明()()()0,30≥∀=-t t u e t x x t T ，并解释这个结果。
北理信号与系统课后答案选解第一章作业参考答案
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= ∫ x(t )δ (t )dt + 2 x(t )δ (t − 2)dt
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= x(0) ∫ δ (t )dt + 2 x(2) ∫ δ (t − 2)dt
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1.26 试判断下列每一个离散时间系统是否是线性系统和是不变系统。 (a)解：线性：
(b)解：线性：
课 后
a x1[n] + b x 2 [n] → y[n] = (a x1[n] + b x2 [n]) − 2(a x1[n − 1] + b x2 [n − 1]) = a( x1[n] + 2 x1[n − 1]) + b( x2 [n] x2 [n − 1]) = a y1 (t ) + b y 2 (t )
时不变性：
(d)解：线性：
时变：
(f) 解：线性：
课 后
a x1[n] + b x 2 [n] → y[n] = (a x1[4n + 1] + b x2 [4n + 1]) = a y1[n] + b y 2 [n]
时变：
ˆ[n] = x[4n − n0] x[n − n0] → y ≠ y[n − n0] = x[4(n − n0)] = x[4n − 4 n0]
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北京理工大学信息系统信号历年考研真题
2016年826信号与系统部分一、简答（5×6=30分）1.物理上是否存在这样的信号，既持续时间有限，又频带宽度有限？说出理由2.)(x t 如下图，画出)15.-0(x +t 的波形3.一个线性时不变系统，初试时刻无储能，当输入)(1t x 为单位阶跃信号，即)()(1t u t x =时，系统的输出为)(2)()(y 21t t u e t t δ+=-，试通过时域方法计算输入为)()(x 2t u e t t -=时，系统的零状态响应)(y 2t 4.计算)]([)(x )1(3t u e dtd t t --=的傅立叶变换)(ΩX 5.如图所示系统，输入为)(x t，输出为)(y t ，该系统的三个子系统的单位冲激响应分别为)(h 1t ，)(h 2t ，)(h 3t ，其中)(u )(h 1t t =，)()(h 3t t δ=，)(h 2t 由微分方程)(2)(2)(y 11'1t x t y t =+ 确定。
试利用拉普拉斯变换求该系统的系统函数)(s H 和单位冲激响应)(h t二、（25分）两种调制器如下图所示。
图中，输入信号)(x t频谱)(ΩX 、系统)(ΩM H 的单位冲激响应)(h m t 、)(p 1t 和)(p 2t 的波形分别如图a 、b 、c 、d 所示，且T10<<Ω，T <<τ（1）（15分）试画出已调信号)(y 1t 和)(y 2t 的频谱)(1ΩY 和)(2ΩY ，并说明)(1ΩY 和)(2ΩY 有何区别（2）（10分）试判断能否在接收端通过滤波器)(1ΩH 和)(2ΩH 分别恢复出信号)(x t 。
若能恢复，设计给出)(1ΩH 和)(2ΩH 。
若不能恢复，请给出理由三、（20分）已知一个系统的结构如图a ，输入信号)(x t的频谱)(ΩX 、理想低通滤波器频率响应)(ΩH 和周期信号)(p t 的波形分别如b 、c 、d 所示（1）（12分）分别画出图a 中A B C D 处的信号频谱（2）（8分）如果上述系统中信号)(p t 的周期改为原周期的一半，画出D 处的频谱四、（15分）图为一个线性系统模型，假设已知该反馈系统是稳定的，试证明若)z (H 在z=1处有极点，则该系统能够跟踪输入单位阶跃序列)()(x n u n =，即0)]()([lim n =-+∞→n x n y数字信号处理部分一、简答（20分）1.（5分）已知信号)1(*)3()(21+-+=n x n x n y ，其中)()21()(1n u n x n =，)()41()(2n u n x n=，利用Z 变换性质求)(n y 的Z 变换)(Z Y 2.（5分）已知序列)3()1()(2)(-+-+=n n n n x δδδ的5点DFT 为)(k X ，求)()(2k X k Y =的DFT 的逆变换)(n y 3.（4分）设实连续信号是频率为12.85Hz 的正弦信号，现用100Hz 的采样频率对其进行采样，并利用N=1000点DFT 分析信号的频谱。
一个《信号与系统》考了147分的考研者的经历
一个《信号与系统》考了147分的考研者的经历信号与系统我考了147，总分438！我考的成绩挺平均：政治83，英语，77，数学131，专业课信号与系统147分，总分438。
但我在这里不说别的，只说说我复习专业课的经验。
由于我工作很不顺心，所以才有了考研的想法，本来打算边工作边考。
后来在一次老同学的聚会上，原来的同学有几个关系好的鼓励我要好好复习。
所以我就下了决心辞去了工作考，因此复习时我特别认真和重视，下定决心要比别人付出双倍时间和金钱。
我在六月初买了专业课的课本和参考书，然后利用公司的上网条件搜集到了我要用得的资料（这个工作确实太花时间，我几乎用了整整三个月天天趴在网上搜集，对工作影响大了，老板批评了我几次，后来在老板炒我鱿鱼之前我先交了辞职书了）我在7月以前是利用空闲时间学习，主要看了上海交大胡光锐和中科大徐守时的信号与系统，还有北理工的数字信号处理，然后决定先学信号与系统后学数字信号处理。
7月后就抓紧一切可以利用的时间学习了，甚至上班也偷偷看。
用一个月细读了清华大学郑均理信号与系统上下二册，并对照答案看过了大多数课后题（第一版的课后题包含了全部第二版的课后题，因此第一版的答案可以用）。
8月结合笔记细读了西安交大刘树堂翻译的奥本海姆的信号与系统，并对照答案做课后题（也是用第一版的答案，题号要自己找）。
这本书不愧为经典，后悔没早点看。
课后题基础题没做，提高题几乎全作了，有一些明显不像考试题得只看了看答案的思想。
用时一个月。
9月先把上交胡光锐的解题指导，和张小虹的学习指导与实践的例题看完了，用时15天。
然后开始做第一次作试卷，做了8份杂的+上交大7份+中科大的11份，受打击极大，不过还是硬着头皮挑会做得先做了，留下了不会的和所有的数字信号处理的题。
这个时候是我第一次也是唯一一次产生放弃的念头。
我的感谢我在母校上研的老同学们，是他们的鼓励让我坚定了一定要坚持到底的信念。
10月开始辞职在家全力复习，从10月1号开始做西安交大的15份卷子，感觉能做的题目占到了一半。
北京理工大学第二学期2006级复变函数与积分变换试题(A卷)参考答案
课程编号：07000048北京理工大学2007—2008学年第二学期20XX 级复变函数与积分变换试题A 卷班级_______ 姓名_________ 学号_______成绩__________一 (10) (1) 求区域})Re(:{0>z z 在映射i iz w +=下的像。
解答：像为{w |Im(w ) > 1}（映射过程图略）。
(2) 判别函数)Re()(22z i z z f -=在复平面上哪些点处可导，哪些点处解析。
解答： f (z ) 仅在 x ＝y 处可导，在整个复平面上无解析点。
二（6）设函数)()(y cx y i bxy ax z f 2323+++=在复平面的某个区域D 内解析，试确定c b a ,,的值。
解答：a ＝－1，b ＝3，c ＝－3.三（6）求解析函数iv u z f +=)( 满足：y x u )(12-=，i f -=)(2。
解答：.)1()12()1(2)(222--=-+-+-=z i x x y i y x z f四（58）计算下列积分：（1）⎰C dz z )Re(，其中曲线C 分别是从点1-到点1的I)直线段，II)上半单位圆，III)下半单位圆。
解答：I ）0； II ）i 2π-；III ）i 2π； （2）dz i z ze C z ))((22-+⎰，其中积分路径C 从点0到点i 的任意光滑曲线。
解答：31121))((22i e dz i z ze C z -⎪⎭⎫ ⎝⎛-=-+⎰； （3）i dz z z dz z z z dz z z z z dz z z z z z z z 2)2(1)2(||)2()2(12122121π-=-+-=--⎰⎰⎰⎰====； （4）i z z dz z z 6)2)(12(12π-=--⎰=；（5）i e dz z z e z z π12)1(12153=-+⎰=-； （6）i dz z z z z 15)5)(1(12||2π-=+-⎰=； （7）0102>+⎰+∞αα,cos dx xx 解答：απαe dx x x 21cos 02=+⎰+∞； （8）i dz e z i z z 32||12π=⎰=-； （9）i dz z z z z π211cos 265=+⎰=.五（12）(I) 求函数65)(2+-=z z z z f 在点0=z 处的Taylor 级数展开式； 解答：);2|(| ,31213121)(00111<⎪⎭⎫ ⎝⎛-=⎪⎭⎫ ⎝⎛-=∑∑+∞=+∞=+++z z z z f n n n n n n n n (II) 求函数))(()(242--=z z z h 在圆环域311<-<z 内的罗伦级数展开式。