2004-2005期末信号 A卷
北京联合大学2004-2005学年第一学期《大学英语》期末考试卷及答案(A卷)
北京联合大学《大学基础英语》2004一2005学年第一学期期末考试试卷（A卷）班级姓名学号成绩Part I Listening Comprehension (20%)Section One Conversations (10%)Directions: In this section, you will hear 10 short conversations.At the end of each conversation, a question will be asked about what was said.Both the conversations and the questions will be spoken once.After each question there will be a pause. During the pause,you must read the four choices markedA,B, C and D , and decide which is the BEST answer.1.A.at a meeting B.in the office C.in the city D.out of the town2.A.30 minutes B.20 minutes c. 25 minmutes D.15 minutes3.A.go to work by bicyele B. take a taxi to workc.go to work on foot D.go to work by bus4.A.Physics is very difficult. B.He will probably take physics.c.He will not take physics. D.Physics is his favorite subject.5.A. to see her friends in New York B. to have a tourc. to visit her parents in New York D.to New York with her parents6.A. music B.readimg a book C. a long qucuc D. waiting7.A.a clcrk B. a waiter C. a postman D. a salesman8.A.They shouldn't go to the theatre. B. The subway is slower than a car.C.The subway is faster than a car.D.They can go to the theatre without a car.9.A.He agreed that it was a good meeting. B.He thought it was not a good proposal.C.Her support would have helped him this morning.D.Her support would count for nothing.10.A.If she will do the job. B. What the woman is goimg to do.C.How the woman's health is.D.If the weather is goodSection TwoPassages (10%)Directions: In this section, you will hear 3 passages.At the end of each passage, you will hear some questions.Both the passages and the questions will be spoken only once.After you hear a question, you mnst choose the best answer from the four choices marked A,B, C and D.Questions ll to 13 are based on the passage you have just heard.11.A. its rivers B. the sea C. the gold and silver D. its mountains12.A. to spend a holiday B. to ski on mountainsC. to look for gold and silverD.to travel in Colorado13.A.People living in the cities and towns most like to dig gold in the moumntains.B. Many of them serve in the army and air force and govemment agencies.c. Only a few work in the industries.D.Many of them work in agriculture.Questions 14 to 17are based on the passage you have just heard.14.A.the care and proper selection of dogs for family petsB. different kinds of dogzsc.different kinds of books about dogsD.the responsibility of the parents15.A. from a pet store B.from friendsC. from the books about rarious kinds of dogsD. from the owner of the dogs16.A.Because they are easy to train. B. Because they are aggressive.c.Because thay are big. D.Because they proride companionship as well as protection17.A.when your children are young B. when you live in the city.c. when the space is limited. D.when you live with your parents. Questions 18 to 20 are based on the passage you harve just heard.18.A.. because there are msny developimg nstions.B. becanse people use too msny man-made materials.c.becatuse we have more snd more industries.D.because we are building more comfortable houses.19.A. industry B.health C. the funure of our children D. elean air20.A.No one knows where the society is going-B.People don 't welcome the rapid development of moden society.c.The speaker is womied about the fuure of our modem society.D.Man can do nothing about the problem of pollution.Part l Readling Conprehension (30%)Passage OneSuicide is on the rise in parts of AsiaoA person thinking sbeut taking lhis own life ofen exhibits waning signs, such ss depression,anxiety,hostility oranger.Learming to recogmize these zigns may save someone s life.Most sucides are the conseqtuence of depression.Tesve sigas distinguish resal depressicn fiom oceasional unhsppiness: 1.xviewing thingsonly in the mot negzative terus. The depresed peson its convinced that life will never get beter.2.Avoiding friends and social activities.Safden withdrawal is a signal of distes. 3.Chsnging daily potrenmis dramstieally.when a good sleper suddenly becomes an insomnisc,alighn eater develops a gpreedy appetie, a quiet person funs extrernusely sactive, and there s a chsnce he 's sufEering from depression.Not all depressei pecple are suicidal.Many older adults know that perils (危险) of sadness will pass.They aze more likely to seekprofessionsl heip. Youme people and younger adits often think depresiion will neyer endExperts tel us some suicidal people proride clear-cut sigals of their plan. For instance, some youths send notes or cas.ette tapes toreveal their feelings of depression or helplessness. So leam the signs and do something: life is too important to risk,1.The writer believes thatA. even occasional unhappiness will inevitably lead to suicideB.an emotional person will most likely commit suicideC.all depressed people are suicids1D.suicide can be prevented if ceitain signs are recognized2.According to the passAge, a peTson attempting suicide often shows the following signs EXCEPT thatA. he belieses that life will never get betterB. a previously quiet peason suddenly becomes unasually activeC. be is seeking professional helpD. be suddenly stays away from social activities3.The word "insomniasc” (Para.2,Line 3 ' most probably meansA.a sleepless personB. an unhappy personc. a talkative person D.a senisitive person4. It can be inferred from the passage thatA. suicide is on the decline in other parts of the worldB.before trying to commit suicide, one usually shows some signsc. a person without friends is sure to commit snicideD.older adults never attempt suicide5. Which of tihe following may be the title for the passage?A.An Inevitable Pesult of DepressionB.Suicide Can Be PreventedC.Suicide Is On the RiseD. Danger of Changing Daily Pattems Passge IwoBathing in the soea in England a hundred years ago was not quite the lght-bearted amusement fthat it is today. There was DO runing down ftom the hotel to the beach in a batb robe,加subathing or lying about 咖the sands in bathigdes ater the dip (侵泡).Everything had to be done in an orderly and extemely polite mamer Mixed bathing wass not alowed anywhere. Men and women each had their separate part of the beach and they were nDot supposed to meet im the water.Bathing clothes were also closely cotolled Men usally wore simpl bathing dawers and no more, but women were obliged (被迫)to wear thick, cumbersome woolen guments that corvered them completely fom head to foot., These satisfhed the demands of modesty, but fthey rmust have been extenely umcomfotable for swinming.Even thus decently covered, women were not supposed to show themselves om the beachwhile in bathing costume. They had to wait tbeir tum for a bathing machine. a sot of woodkan cabin om whels which was drawn night down to the water's edge by horses. On its seaward side a sort of hood or camopy (伞盖) stetched outwards and dowwads over he water, completely hiding the batber wtal she was actually in the sea. There was a bathing woman in atendance, part of whose duty was to dip. in otber words, to seize the batbher as soon as she emerged and dip ber frcibly under water two or three times. This was supposed to be for the benefit of her health and no doubt it wasall right in the hands of the gentle. But mosot bathing women mere reverse of the geale. and to be diped by them must have bee a steuouss (艰苦的) fom ofexercise.6. Modem bathersA wear thick, ucomfortable bathing clotbesB. use hose-drawm bathing machinesC. aen't alowed to sumbatheD. have mixed bathing om the beach and im the sea7. Women wore uonortble bating clothes becauseA it porected from coldB. it Was considered bad moanners to show auy fleshC. itmade it easier to smwimnD. it was requird by the rgulations8. Why was the bathing muachines used?"A So that the horses could drimnk at the water's gate.B. So that the hood could be projected towards the seaC, So that the bather could hide from tbe seaD. So that tbe bather could be screened umtil she was in the a9. A bathing -woman's job was toA. ated to the bathing machineB. dip the atendaceC. force the bather to emerge ftom the bathing machineD. force the bather under the water when sbe came out of the machine10. A sitblet title for this pasage would beA. Sea Bating through the AgsB. Bathimg cothes through the AgesC. Sea HorsesD. Hundred Years of Sum BathingPassage ThreeThe loudest outery(强烈反对)about povety (贫困) seemed to come in the wealhiest coumty -by for in the world. According to most calculations, tbough most of tbe 19541970 period the United States had a standard of living well above Europe's and may times above the world average. Y'et protests about erinding porverty, humger and dreadful need poceed (继续下去》more fom the United States than from counties with cn-6fcieth of ther living (An anmual per capita income of eight dllas 1s typcal of mch of Africa and Asia and not a ltle of South America). It would衣em suange t如these psople ( were they only avare of the fxct?)y that Amernican ndicals demand a retreat froman American commitment 0o the fr comers of tbe globe 50 that tbe mobey thus saved can be spent raising the standard of living of udepriliged (下层的) Amercans.What this last print suggests is not s0 mnch that hummn wnts are mever to be stastfied though this is doubtles toue. and the Americn suburbanite (郊区居民) deprived ofhis second car ad his color ” suffers just a acutely韶a African farmer in peed of a second cow and a screen door. Rather, it suggests the esteat of contempoary break of social nonns - the emaeiation of the individual self. People have leamed that their wants are scare and their right ought to be satisfed. They have leamed to consider any obstacle to personal fullment a intolenble insult. They have greatly expanded the circle of self awaen族They加longer accet shap laninations份日) op individual desires im the nane of the group. The amoumnt of potential buman discontet has always been infnite - misery, failure, msfting bitress,hatred, enry beyond eling It bhas usally failed of uterace (讲言表达) , and in the past it vwas accepted pasvely as being beyond belp.11. According to the passage most complaints over a poor living standard were made by those who came from___A. the United StatesB. Asian coumtriesC. the European CommityD. Commonwealth ofNations12 The average income for each Ameican a year during the 60s was most ikely in the bigborod of .___A. 1120 dllarsB. 40 dllarsC.320 dllrsD. 80 dllrs13. n onder to inprove the staodand of living of poor Amenicas, dhe exuemits in the Stotes demand.___A. a fll tax elief on cizeas lving oveveasB. a stop to arms race gainst ations far awyC. a cw im financial stace 0 poor coutiesD. a farorable blaoce of tade nih foreiepe coumties14. The real cause for dhe most fctuste people to potest about porety lies in.A.enhsocod consciousnes of selfB. their ece sthtusC. limiations of bumam maueD. contlict in lass itees15. Fom the last sentracte, in e国bwe safely infered that outry about poverty in effect involves people'sA ahilty to sufer a hadife B. unestanding of their rightsC. polial atiude tmurd the govermeatD. mbole outlook o fferent EfestylesPart III Vocabulary and Structure(20%)1. The city is planning a public to awaken people to the problem of the environment pollution.A. CampaignB. missionC. paintingD. rescue .2. The Party calls on us to___ the West and a lot of uiversity students go there ater graduation.A. ExpandB. explodeC. exploitD. execute3. "Here you are at last" ongrily bis mother.A. ClaimedB. exclaimedC. liedD. leaned4. His first year at Oxford bore__ fruir be pubihied ro bo sad ten papers.A. CriticalB. abundantC. militaryD. relative5. The weather sieututs a series of cold days in te future.A. Reflected B restricted C. nepleced D. prdctedd6. ltis nceary dhat pacpl.and: ipove these olfashioned aircnais.A. MolilyB. elaily C bonity D. satindy .7. Thoghbhe is imerir to sowe stuft in fc,be is the____ m muge of the busimessA. TopicalB. speficialC. ritalD. rtual8. There is ofena___ loss of sigh is old ageA. TrvingB. competive C popressive D. executivee9. The back paint o fbe dor porides a___ for tbe whit wll.A. Conest B contast C. comsct D. conat10. The dortor._the: ptie to be operzed xt cace.A. CousetedB. brkedC. aiciedD. unloled11. Ow itucto_ that we should not te anyone about tis.A. QualtyB. decay . c pecty D. bother12. Hearing a cry for belp. the youmg mom nushed to the bamk and.into the rives to save the cowning bory.A. BestedB. plomgedC. devoledD. rteated13. Yom ither's rcewmsr_ it wam treal recovery and please keep am ep唱him further.A. AmkwrdB. supeficinlC. psblD. imfnite14, Though dtey sid woting aboat it Ihom they wushawew__ int de conse ofitA petated B. reulated C. fusuated D. Desxnbed15. Since be is my boss, he paid mea.five huwdued pounds a mouth.A steady B. prior C. novel D. louely16_.__ by their quality I decided to place a big order for tbe productA Having impressed B. Being impressed C. Impressed D. Impressing17. To our supise the bride's mother didn't.at the wedding ceremoay.A. rm intoB. fl uponC. showD. cut of18.the efot and good will of everyone inroled the Christnas party Wwas a great sucess.A As oif B. Thanks to C. Upto D. Delighted with19. The auhor is of the opinion that early success may prove bamful to a person'salroundd development,A in the long nmn B. for the time being C. all day lomg D. side by side20. The city govenment's frst____ is to buildl a Bew ainport lhis yearA Loan B. sting C. depatpent D. piority21. Jobm said that he owed it.his teacher that he wom the first price in the English spech contest.A from B.of . C. to D.at22. Qalifed dploas(外交的sbouldbe able to___ whatever statoms they find teselres imA show up B. mm into : C. imbue with D. cope with23. If James hadn'tbeen there to_ the awlkward moments, the meeting would have beena disaster.A snoo over . B. limk u C. branch out D. pickp24. I'm somry, but I relly can't so out with you tomighet; I have to.my homework.A .nm outof B. catchup om C. make room for D. smeak of to23. The problem our atindes towurd thnking not in nidiculous govemmen regulations.A lies in B. believes in Cin D. speialies in26. Tim always keeps a certaim anoumt of moaey.m case of an energency.m.B. im useC. on handD. on business27.was a very besutful birthday present that Mary got fom ber auntA. ThisB. That D.It28. Bobby is a small staff in this company, but he tlks to everyone inp the ofie asifhe_ the boss.A. IsB. wereC. hadbeenD. has been29. This place馆as rportedto.an eathquake reistered 7.5 o如tbe Richer scale yesterday.A have bad B. have C. have been had D. be having30. The youmg man adnmited _errors in judgment om more than one occasion.A tomake B. making C. to have made D. made31. A womanwho__ the acident said that both cars were going at high speed wben they crasbedA riolated B. obeyed C. witbessed D. screaned32. People did not see the bomb dropping but they could bear the. several miles away.A extension B. esplosion C. secunity D. spectators .33. The company began by specalizing im nadios but has now decided to nto computers.A branch out B. tum dovn C. take stock D. coumut on34. Ata very ealy age sbeA. PreupedB. sbieldedC. dsigisbedD. moirated35. le wese told tbat tbe foall game had been___ mtil the floming Fidary becouse of the bad wenber.A, signed B. sought C. quified D. posponed36. Jim etetrd de Speech Comtes wileous wch hope, not tinking that he would.. witb the fnst paizeA. EaduφB. est out .C. put downD.ip中.37. Saoking i,,tor mamy ditses swch程lung eamcer, hean amack and high blood peswe,A. Pgessire B teortical C. respousible D. amkwurd38. A the disasston the epeleiee Camre中w谐oy good ides xbout the Dew电uB____A. RlativityB. regulationsC. speisD. taleas39. No mter bow for awy Bb was. bis parents wee. tatbe would come brck o see tbem an the Sping Ftiral.A recmmendeddB selected C. iled D. cominced40. The anpocr's sytes Ta n tfcient a m got om aplame wih a boub without being dcoredA desoasmnionB pese C. eplosion D. secuityPartIV Cloze (10%)Dietioas: Please山im tbe blanks wih the erat words from the testBalscing wons md school was dicu "1 ws sarying中late shudying. and going to wok early ervery moming I was haring a haxrdcocetating i els, and a hud ia u the job beaure I was 10 imod." she say But she ended__2_ wid twe A's in her finst semeser amyway.Picilla decided_ 3_ purue m acbaeloeyr majcr and in the smmme of 1991, she got ber finst oportaity t如Teally best_ 4_ herioe in he aubjet The achelogian Botld chool of Wwashington Stue Uunrersty wws sponoring a smr retrch pojtet糕消it_3_ the Souke Rire im Wetingpon Pisxila erer herel_ 6_ he wonk, and pojer sperisors mre ipesed_ 7_ dbe eadof the smmmer oflhe prefeson efered ber a jo. "He ad "We pw wa coumnet tor a poper in Nerth Dakom We wanto_ 8_you it you're wlling to tike a semetser of fom so"he 9_ was a drepion fou Pici's pursait of ber BA.“But by the Ioo longer doubted fatTrould utiantl fmish shoo 10_ I felt coforabl gabbing this oposis; she saysPart V Translatio (20%)Secian A Put tbe flomig retroces into Chinese (10%)She plomnged into the paints naod before I lhew it she bad mept sevenal ferce stroibes ad slushes of bhue on the absoutely emifed cavas In Confucian plosop the family plays 1 cecbal tole -蹈oicanteso that leads people t1o worlk for the hopor of的e faul nt just ftor temebre.,Ibey felt confortble asing bis adrice on a mide amge of atte icluding the odbeharior of teir piters across山e ocam4. Succes, which eancounges rpreition of eld bwehurioc. 船non smeatly a good a 1eacber as tilue Known 10 mls趣and wide. for hts boo d BrielHiusony ef Time. Stepben Hmking ts a st物clem博tm more ways to aee Setim B Put the floig sealeaces ine Engih a09) i. 他在尝试制定促进恩考艺术的新计划时脑子里闪过了一个绝妙的主意。
四川大学 模电期末考试试题及答案
四 川 大 学 期 末 考 试 试 题 (A 卷)（2004 ——2005 学年第 二 学期）课程号：30307240 课序号： 课程名称：模拟电子技术基础 任课教师： 成绩： 适用专业年级：03级电气、制造 学生人数： 印题份数： 学号： 姓名：考 试 须 知四川大学学生参加由学校组织或由学校承办的各级各类考试，必须严格执行《四川大学考试工作管理办法》和《四川大学考场规则》。
有考试违纪作弊行为的，一律按照《四川大学学生考试违纪作弊处罚条例》进行处理。
四川大学各级各类考试的监考人员，必须严格执行《四川大学考试工作管理办法》、《四川大学考场规则》和《四川大学监考人员职责》。
有违反学校有关规定的，严格按照《四川大学教学事故认定及处理办法》进行处理。
（注意：本试题共6页五大题，请全部做在答题纸上） 一、填空题（每空1分，共12分）1、 型场效应管放大电路可采用自给偏压电路，而 型场效应管放大电路只能采用分压式偏置电路。
2、为提高功率放大电路的功率和效率，三极管应工作在 类状态，而要避免交越失真，则应工作在 类状态。
3、某三极管三个电极的电位分别为：V A =1V ，V B =11.3V 、V C = 12V ，则三极管对应的电极是：A 为 极、B 为 极、C 为 极。
晶体管属 型三极管。
4、正弦波振荡电路产生振荡的条件是 ，负反馈放大电路产生自激振荡的条件是 。
5、某放大电路输出电阻为7.5 k Ω，不带负载时输出电压为2V ，接入2.5k Ω的负载电阻后，输出电压为 V 。
6、某负反馈放大电路，V V F A O V V 2=,0495.0=,2000= 输出反馈系数开环电压增益则输入电压i V= V 。
注：1试题字迹务必清晰，书写工整。
本题 6 页，本页为第 1 页2 题间不留空，一般应题卷分开教务处试题编号：3务必用A4纸打印学号：姓名二、单项选择题（每题2分，共20分）1、电路如图所示，其中D Z1的稳定电压为8V，D Z2的稳定电压为10V，它们的正向压降为0.7V，则输出电压为（）A:18V B:2V C:8.7V D:10.7V2、对于共集电极放大电路的特点，其错误的结论是（）A：输入电阻高，且与负载有关B：输出电阻小，且与信号源内阻有关C：电压放大倍数小于1，且接近等于1 D：电流放大倍数小于13、桥式RC正弦波振荡器中的RC串并联网络的作用为（）A：放大负反馈B：选频负反馈C：选频正反馈D：稳幅正反馈4、设乙类功率放大电路电源电压为±16V，负载电阻R L=16Ω，V CES=0V，则对每个功率管的要求为（）A：P CM≥8W V BR(CEO)≥16V B：P CM≥1.6W V BR(CEO)≥16VC：P CM≥8W V BR(CEO)≥32V D：P CM≥1.6W V BR(CEO）≥32V5、在图示整流滤波电路中，若负载R L开路，则输出电压ν0为（）A：0.9ν 2 B：1.2ν 2 C：2ν 2 D：22ν 2本题 6 页，本页为第 2 页教务处试题编号：学号：姓名6、能将矩形波变成三角波的电路为（）A：比例运算电路B：微分电路C：积分电路D：加法电路7、运算放大电路如图所示，在该电路中反馈组态为（）A：串联电压负反馈B：串联电流负反馈C：并联电流负反馈D：无反馈8、下图中示出了放大电路及其输入、输出波形，若要使ν0波形不失真，则（）A：R C增大B：R B增大C：V CC减小D：νi增大9、在多级直流放大器中，零点漂移影响最严重的是（）A、输入级；B、中间级；C、输出级；D、增益最高的那一级10、同相比例放大电路具有（）A：电压并联负反馈B：电流并联负反馈C：电压串联负反馈D：电流串联负反馈三、、是非题(判断正误, 对打√，错打×)（每题1分，共10分）1、1、温度升高，在本征半导体中自由电子数增多，而空穴数目不变。
2004-2005期末信号 A卷
9、写出连续系统无失真传输的时域条件和频域条件。
A卷
第 2 页 共 5 页
10、某系统的系统函数为 H ( s )
( s 2 )( s 1) ( s 0 . 5 )( s 2 . 5 )( s 3 )
，求：系统的单位冲激
பைடு நூலகம்
响应的初值 h ( 0 ) 和终值 h ( ) 。
五（10 分）根据下列描述离散系统的不同形式，分别求出各系统的系统函数 H(z)。 （1） y ( k ) 2 y ( k
1) y ( k 2 ) f ( k 1) f ( k 2 ) ；
（2） H ( E )
E
6E
3
2
17 E 19
2
8E
17 E 10
；(其中 E 为差分算子或位移算子)
（3）系统的单位序列响应 h（k）的波形如图 5 所示。
A卷
第 4 页 共 5 页
西北工业大学命题专用纸
六（10 分）已知系统的状态空间方程为
x 1 1 1 x 2
0
x 1 1 f 3 x 2 0
)d
A卷
第 1 页 共 5 页
4、已知信号 f(t)=
s in 2 t t
cos 1000t
，求其频谱函数 F ( j ) 。
sin 2 t 进行理想抽样时的最大允许抽样间隔 T。 5、求信号 f ( t ) 2t
2
6、求单边拉氏变换 F ( s )
e
(s2)
二（10 分）图 2 所示系统， （1）求系统函数 H ( s )
05电本信号与系统期末考试AB卷标准答案
05电本信号与系统期末考试AB卷标准答案一、选择题：（每小题2分，共40分，请把每道选择题唯一正确答1．积分dt t t e t )]()(['2δδ+?∞∞--等于：（）（A ）0 （B ）1 （C ）2 （D ）3 2．序列和)2()4sin(-∑-∞=n n kn δπ等于：（）（A ）1 （B ）u(k) （C ）u(k-2) （D ）)2(-k δ 3．序列卷积和)4()2()2()1(-*+--*+k k u k k u δδ等于：（）（A ）)(k δ （B ）)1(-k δ （C ）)1(-k u （D ）)3(-k u 4．已知某系统的单位样值响应)(2)(n u n h n =，则该系统的因果性和稳定性：（）（A ）因果，稳定（B ）因果，不稳定（C ）非因果，稳定（D ）非因果，不稳定5．已知某离散系统单位样值响应为：)1(2)()(-+=n n n h δδ，输入序列为：)2(3)1(2)(-+-=n n n x δδ，则该系统的零状态输出为：（）（A ）)3(6)2(7)1(2-+-+-n n n δδδ （B ）)3()2()1(-+-+-n n n δδδ（C ）)3(6)2(4)1(2-+-+-n n n δδδ （D ）)3(6)2(7)1(-+-+-n n n δδδ 6．dt t f t t )()(0?∞∞--δ的结果为：（）（A ）)(t f （B ）)(0t t f - （C ）)(0t t f + （D ）)(0t f 7．已知一因果序列)(n f 的Z 变换式为)2)(1(12)(+++=z z z z z F ，则)(n f 的初值为：（）（A ）0 （B ）1 （C ）0.5 （D ）28．一LTI 无失真传输系统，它的幅度特性和相位特性要求为：（）（A ）幅度特性为常数，相位特性无要求（B ）幅度特性和相位特性均无要求（C ）幅度特性无要求，相位特性的斜率为-t 0 （D ）幅度特性为常数，相位特性的斜率为-t 0 9．若一LTI 系统输入为)(1t e 时，输出为)(1t r ，输入为)(2t e 时，输出为)(2t r ，则输入为)]()([21t e t e a +，输出为：（）（A ）)()(21t r t r + （B ）)()(21t r t ar + （C ）)()(21t ar t ar + （D ）)()(21t ar t r + 10．一理想低通滤波器的截止频率为c w ，下列信号经该滤波器滤波后信号不失真的是（cw w 2=）：（）（A ）)2cos(wt （B ）)2cos()cos(wt wt + （C ）)cos(wt （D ）)3cos(wt 11．请选出)2()1(2)()(-+--=t u t u t u t f 的波形图：（）12．若)()]([s F t f L =，则])()([00at e t t u t t f L ---为：（）（A ）0)(st e a s F -+ （B ）0)()(t a s e s F +- （C ）0)()(t a s e a s F +-+ （D ）0)(st e s F - 13．下列选项不．属于状态变量法分析系统的优点的是：（）（A ）便于研究系统内部物理量的变化（B ）便于研究多输入多输出系统（C ）可研究非线性系统或时变系统（D ）便于研究系统的频率响应特性14．已知1)]([2-=z zn x Z ，（1>z ），则)](3[n x Z n 为：（）（A ）12-z z ，1>z （B ）932-z z，1>z（C ）12-z z ，3>z （D ）932-z z，3>z15．求)()3/1()()5.0()(n u n u n y n n +=的Z 变换为：（）0-11tf(t)(A)12021tf(t)(B)120-11tf(t)(C)120-11tf(t)(D)12（A ）3121-+-z z z z ，21>z （B ）3121-+-z z z z ，31>z （C ）3121+++z z z z ，21>z （D ）3121+++z z z z ，31>z 16．已知)]2(/[)12()]([++=s s s t f L ，则)(t f 的初值)0(+f 为：（）（A ）0．5 （B ）2 （C ）0 （D ）3 17．若FE )()]([w F t f =，则FE ])()([0t jw e t f dtt df +为：（）（A ）)()(0w w F w jwF -+ （B ）)()(0w w F w jwF ++ （C ）jw w F w w F /)()(0+- （D ）jw w F w w F /)()(0++ 18．一个频谱受限的信号)(t f ，如果频谱只占据m w -到m w +的范围，则信号)(t f 可以用等间隔的抽样值唯一表示。
北京科技大学线性代数04--05第一学期期末考试卷
北京科技大学2004—2005年第一学期（A 卷）学院________ 班级_________ 姓名__________ 学号_________一．选择题（共12分，每题2分）1．设121213()2534223xx x f x x x----=-, 则()f x 中3x 的系数为〔 〕.(A)3- (B)2 (C)6 (D) 32．设,,A B C 为n 阶方阵且A C B E =，则下述结论正确的是〔 〕. (A)A B C E = (B)C A B E = (C) B A C E = (D)B C A E =3．设有向量组：(1,0,1),(1,1,1),(0,0,1)TTTαβγ==-=，则下列向量组中线性无关的是〔 〕. (A) ,,αββγγα+-+ (B) ,2,2αββγγα--- (C) ,,αββγγα--- (D) ,,αββγ+4．A 是一个三阶实矩阵，它的特征值123,,λλλ互不相同，123,,ααα分别是相应的特征向量，则下述结论正确的是〔 〕.(A) A 一定相似于对角阵 (B) A 可逆(C) 123,,ααα相互正交 (D) 123,,ααα可能线性相关5．设A 是m n ⨯矩阵，若()R A r n =<，则n 元线性方程组A x b = 〔 〕.(A) 不一定有解 (B) 有无穷多解 (C) 有唯一解 (D) 无解6．下列矩阵中为初等矩阵的是〔 〕. (A) 100013001⎛⎫ ⎪ ⎪ ⎪⎝⎭ (B) 200022002⎛⎫ ⎪⎪⎪⎝⎭(C) 010001100⎛⎫ ⎪ ⎪ ⎪⎝⎭ (D) 001013100⎛⎫⎪⎪ ⎪⎝⎭二．填空题（共18分，每空3分）1. 设 101311011A ⎛⎫⎪=-- ⎪ ⎪⎝⎭,012034200B ⎛⎫⎪= ⎪ ⎪⎝⎭, 则秩()AB B -= 。
2．若三阶非零方阵B 的每一列都是方程组1231231232202030x x x x x ax x x x +-=⎧⎪-+=⎨⎪+-=⎩的解，则a = ，B = 。
北京邮电大学 2004-2005学 年第一学期通信原理试卷附答案
F 1 , K pa F 2 , K F , K pa北京邮电大学 2004-2005学 年第一学期期末试卷附答案一. 填空（每空 1 分，共 16 分）1. 调相信号 s (t ) = A c cos ϒ≤2π f c t + K P m (t )/ƒ，其解析信号（即复信号）的表达式为 ，其复包络的表示式为。
2. 循环平稳过程的定义是。
3. 用基带信号 m (t ) = 2 cos 4000π t 对载波c (t ) = 20 c os 2π f c t 进行调频，若调频的调制指 数是β f = 9 ，则调频信号的时域表达式s (t )=，其信号带宽B = Hz 。
4. 若多级线性网络的第一、二、……及第n 级的噪声系数及功率增益各为 1 、2、…、 n，则级联后的总噪声系数F 为 。
5. 一 MPAM 数字通信系统每隔 0.1ms 以独立等概方式在信道中传送 128 个可能电平之一，该系统的符号传输速率为 波特，相应的信息传输速率为bit/s 。
6. 数字 PAM 信号的平均功率谱密度取决于及。
7. 在 条件下，BPSK 和 QPSK 的平均误比特率相同，但后者的功率谱主瓣带宽是前者的一半。
SC = B l og 2 1+8. 仙农信道容量公式N 0 B 是在 条件下推导得到的。
c 1 29. 利用线性反馈移存器产生 m 序列的充要条件是。
m 序列应用于扩频通信，可利用 m 序列的 特性进行解扩。
10. 最小码距为d min = 7 的线性分组码可以保证纠正 个错，或可保证检测 个错。
二、选择填空（每空 1 分，共 14 分）从下面所列答案中选择出恰当的答案，将对应英文字母填入空格中，每空格只能选一个答案(a) 减小(b )增大(c )不影响 (d )AMI (e )Manchester(f )CMI (g )HDB3 (h )系统在载频附近的群时延(i )时延(j )在信息序列中引入剩余度 (k )对有剩余度的消息进行减小剩余(l )可靠性 (m )有效性 (n )编码信道 (o )恒参 (p )调制信道 (q )随参 (r )等于 8bit (s )等于 4bit(t )小于 4bit (u )大于 4bit1. AM 信号通过带通系统，当带通系统在信号带宽内的幅频特性是常数，相频特性是近似线性时，通过带通系统后信号包络的 等于 。
南昌大学期末试卷信号处置期末试卷(2004.12,1,本)
f(t)
(1)
……
……
…… -2 -1 0 1 2 ……..
ห้องสมุดไป่ตู้
t
得分 评阅人
五、（8 分）
得分 评阅人
已知实信号 f(t)的最高频率为 fm (Hz)，试计算对下各信号进行理想 抽样的最小抽样频率。要求写出理由。1、f(2t)；2、f(t/2)；3、f(t)f(2t)；
4、f(t)×f(2t)。
六．（12 分）系统的微分方程为 y’’(t)+5y’(t)+6y(t)=2f’(t)+8f(t)，写出系统模拟图：当
。
A． 1 F ( j)F ( j2) ； 2
B． 1 F ( j)F ( j ) ；
2
2
C． F ( j )F ( j2) ； 2
D． 2F( j)F( j2) 。
7．已知 x(t)的波形如下图所示，其函数表达式是
。
f(t) 1
01 2 345t
1
A．f (t) = u (t) - 2u (t - 2) + u (t -3) ； B．f (t) = u (t -1) - 2 u (t - 2) + u (t - 3) ； C．f (t) = u (t - 1) - 2 u (t - 3) + u (t - 4) ； D．f(t) = u (t - 1) + u (t - 3) - u (t - 4)。
C． u(n) (n) (n 1) (n m)
n
D． u(n) (k)
k
5．信号 x(t) 4Sin[ (t 3)] Cos[ (t 3)]与 (t 3) )之积为
。
6
6
A．4δ(t + 3)； B．0； C．δ(t + 3)； D．-δ(t + 3)
南山职业技术学院2004—2005学年第1学期期末考试试卷(A)
南山职业技术学院2004—2005学年第1学期期末考试试卷(A)03计算机应用 (专业) VC++ 6.0 程序设计(课程名称)一、填空题（每空1分，共25分）1、Visual C++6.0开发环境界面由标题栏、_______、工具栏、项目工作区、_______、输出窗口以及_______等组成。
2、View菜单中的命令主要用来_______窗口和工具拦的显示方式，_______调试时所用的各个窗口等。
3、项目工作区窗口包含三个页面，它们分别是_______页_______页_______页。
4、类是对一类客观对象的_______和_______进行抽象后的，以数据、代码和函数共同封装为形式的描述。
5、类中包括三种模式，他们分别是： (1) _______ (2) _______(3)_______ 。
6、对象是其相应类的_______，也就是说类的各种操作都是在对象这种_______上发生的。
7、构造函数是一种特殊的类成员函数，当程序创建_______时，首先会自动执行类的构造函数。
构造函数与类拥有_______的名字，在构造函数中，用户可以执行初始化类成员_______，_______内存空间等操作。
8、C++语言在重载函数的使用方面有一个重大的突破，那就是允许具有相同函数名的函数在同一个_______中出现，这些函数可以完成不同的功能带有不同数目、不同类型的_______，这就叫函数的重载。
9、在面向对象程序设计中，一个类可以继承其它类的特性，其中被继承的类称为_______，而继承类称为_______。
10、所谓虚拟函数，就是指某个函数在基类中被声明为_______函数，而该函数又在_______中被重新定义。
二、选择题（每小题1分，共15分）1、项目名为：EX_SDIHello的单文档Vc++程序，MFC为用户自动创建了4个主要的类，请选择：（1）视图类_______ （2）应用程序类_______（3）主框架窗口类_______ （4）文档类_______(A) CEx_SDIHelloApp (B) CEx_SDIHelloDoc(C) CEx_SDIHelloView (D) CmainFrame2、项目名为：EX_SDIHello的单文档Vc++程序中的应用程序类，有下列代码：BOOL CE_SDIHelloApp::InitInstance() { ……………..CStringleDocTemplate *pDocTemplate;pDocTemplate = new CSingleDocTemplate(IDR_MAINFRAME,RUNTIME_CLASS(CEx_SDIHelloDoc),RUNTIME_CLASS(CMainFrame),RUNTIME_CLASS(CEx_SDIHelloView));AddDocTemplate(pDocTemplate);………………}其功能是_________。
信号05年期末试题
(D)
je2 2 j
6、已知信号f(t)的奈奎斯特角频率为ω0，则信号f(t)cos(ω0t)的奈硅斯特角 频率为 (A) ω0 (B) 2ω0 (C) 3ω0 (D) 4ω0 7、信号 f(t) = (1-t)e-2t(t)的拉普拉斯变换F(s)等于 (A)
1 ( s 2) 2
(B)
d d d [ f1 (t ) f 2 (t )] [ f1 (t )] [ f 2 (t )] (D) f (t ) (t ) f (t ) (B) dt dt dt
3、用差分方程描述的系统为线性时变系统的是 (A) y (k ) 2 y (k 1) y (k 2) 2 f (k ) (B) y (k ) 2 y (k 1) y (k 2) 2 f (k )
F (s)
12、已知 f(t) 波形如题12图所示， 试画出f(2t-1)ε(t)的波形.
f(t)
1
f (2t-1)ε(t)
t
o
1 3
t
o
题 12 图
13、某因果信号的拉普拉斯变换为 F ( s)
2 ，则该信号的傅里叶变换为 s( s 2)
;
F ( j )
14、 已知 频谱函数F (j ) 4Sa( ) cos(2 ), 则原函数 f(t) =
2 | F ( j ) | d
1 2 1 2
2 F ( j )d
(B)
1 2
| F ( j ) | d
(D)
1 2
j 3 | F ( j ) | e d
Ⅱ、填空题（共5小题，每小题4分，共20分）
11、信号
f (t ) e2 t [ (t 1) (t 2)] 的单边拉普拉斯变换为
Grammer(1)
班级： 姓名： 学号：密封线内禁止答题英语语法 考试卷 A 卷 第 1 页 共 5 页 2022-03-23南 京 信 息 职 业 技 术 学 院 试 卷2004/ 2005学年第1学期期末考试A 卷课程名称： 英语语法 考试时间：100分钟 命题人 赵小云 04 年 12 月 26 日 审批人 年 月 日使用班级： 00411P ，00412P 考试成绩：Part Ⅰ Choose one answer that best completes the sentence. (50 minutes) 1. There was no choice next morning _____________ my tale of the Belleville supper.A. but turn inB. but turning inC. but to turn inD. but turned in2. _____________ in mind as well as in body, the child needs more than medical care.A. SickB. Be sickC. Because sickD. For sick 3. To postpone _____________ the debt will ruin our business reputation. A. to pay B. paying C. pay D. paid4. Because of rising cost, we spent _____________ money on the project as had been planned.A. twice muchB. twice as muchC. twiceD. twice as more 5. _____________ a solution to the problem of water shortage, we have to put all our efforts together.A. Being worked outB. Working outC. Work outD. To work out 6. Mrs. Newman hurried home after work, only _____________ both her kids gone for the movie.A. findingB. foundC. to findD. having found 7. The village was so quiet that they did not anticipate _____________ any trouble.A. meetingB. to meetC. to be metD. being met 8. If we had had adequate time to prepare, the results _____________ much better.A. would beB. wereC. had beenD. would have been 9. Read the book carefully _____________ you’ll find lots of information related to our research.A. ifB. orC. soD. and10. Why not _____________ to Professor Smith for advice? He is an expert in this field.A. goB. your goingC. to goD. you go11. The kids lay face down on the beach, their backs _____________ to the sun. A. exposing B. exposed C. having exposed D. were exposing12. She trusted her Dad, but couldn’t help _____________ television images of floods and people _____________ to treetops, wet and cold. A. to recall, clinging B. recall, clingC. recalling, clingingD. recalling, cling13. Only when I myself became a mother, _____________ the value of my parents’ advice.A. did I realizeB. I realizedC. I had realizedD. did I realized14. The doctor insisted that the patient _____________ to hospital immediately.A. admitB. admitsC. be admittedD. to be admitted15. Think about them not as though they were dissociated, but as though each _____________ one aspect of a single unity. A. were B. was C. had been D. is 16. Like a lot of black kids, we never _____________ it without our Momma. A. will make B. would make C. make D. would have made 17. He commented that it was probably the first time that ice _____________ on the Sahara in several thousand years.A. had rainedB. has rainedC. rainedD. is raining 18. But for the reader ’s sake, I _____________: “I am the only daughter of a Mexican family of six sons.”A. should write C. wroteC. writeD. should have written19. He read it very slowly. As if he _____________ each line over and密封线内禁止答题over.A. were readingB. readC. readsD. was reading 20. The house was gone, _____________ others that had lined the street. A. as was B. as were C. that was D. that were 21. Don’t take his remarks too seriously. He’s so upset that I don’t think he really knows what _____________.A. he saidB. he’s sayingC. he’d saidD. he says 22. Don’t telephone me after eight. _____________ a dinner party. A. We’ve had B. We’re to have C. We’ll be having D. We’re having23. I want _____________ the renovations before I start thinking about redecorating.A. to get done withB. to have got done withC. to be got down withD. to have been down with 24. _____________ next weekend rather than the one after.A. I’d prefer them to comingB. I’d prefer them to comeC. They’d be preferred to comingD. They’d be preferred to come 25._____________ the most serious challenge in our history and we depend on you, our allies, for support.A. We are now facingB. We now get facedC. We are getting facedD. We are now faced26. I could mention other examples of your bad work, but _____________ to say that your performance has been unsatisfactory. A. it suffices B. suffices it C. it suffice D. suffice it 27. It’s Saturday, and quite time you _____________ off work till Monday morning.A. leftB. leaveC. to leaveD. had left 28. I’d rather you _____________ anything about what we have just discussed.A. hadn’t saidB. not to sayC. won’t sayD. didn’t say29. If they didn’t like the apart ment, they _____________ there so long.A. wouldn’t s tayB. won’t stayC. wouldn’t have stayedD. won’t have stayed30. I _____________ rude to him, but I feel he had given me every justification.A. may have beenB. can have beenC. must have beenD. ought to have been 31. He wears glasses all the time. His eyesight _____________ any better. A. mustn’t be getting B. can’t be getting C. shan ’t b e getting D. won’t be getting32. They offered him the job on the strength of his letter. He _____________ an interview.A. mustn’t even have to haveB. shouldn’t even have to haveC. didn’t even have to haveD. mightn’t even have to have 33. Some actresses like to be surrounded by a crowd of people all the time, while others _____________ on their own instead. A. have got to be B. had better be C. would rather be D. might as well be34. These indoor plants need some sunlight now. _____________ them out at least once every two weeks.A. You would putB. You had better putC. You may well putD. You might as well put 35. He _____________ but his wife successfully opposed the idea. A. would like have emigrated B. would like to have emigrated C. had better have emigrated D. would rather have emigrated 36. He could really frighten me, and yet at the same time he _____________ the most gentle and courteous of men. A. could be B. was able to be C. might be D. ought to be37. Most of the news on the front pages of both daily newspapers _____________ the progress of the peace conference.A. is concernedB. are concerningC. concernsD. concern 38. Our school team _____________ to take part in the tournament, but our principal is not very keen on the idea.A. has been askedB. has been askingC. have been askedD. have been asking39. He is one of those people who by the general opinion of the world密封线内禁止答题_____________ both infamous and unhappy.A. are countedB. is countedC. are countingD. in counting40. Most of the luggage _____________ into the boot of the car. However there are still two bags left.A. have been puttingB. has been puttingC. have been putD. has been put41. For many young people, the late 1960s _____________ a period of revolt against the moral values that had been the strength and pride of the past generations. A. has been B. have been C. was D. were42. No one in this group of contenders _____________ a chance of beating the current speed record.A. are standingB. is standingC. standD. stands43. About $250,000 of medical supplies _____________ among families affected by the epidemic. A. has distributed B. have distributedC. has been distributedD. have been distributed 44. The variety of plans submitted for the new gallery _____________ the range of current architecture.A. have indicatedB. is indicatedC. indicateD. indicates 45. _____________ disappointment, send us your holiday application form as soon as possible.A. so as to avoidB. To avoidC. For avoidingD. Avoiding 46. Frank says he ’s taught a thousand people how to fly, and all of them are still alive _____________ the tale.A. in order to tellB. so as to tellC. tellingD. to tell 47. _____________ into a lengthy discussion, the council decided to set up a subcommittee to deal with the matter.A. Not to getB. In order not to getC. For not gettingD. So as not to get 48. I was surprised at what he said, _____________. A. so as to say the least B. only to say the least C. in order to say the least D. to say the least 49.In their house it ’s Lorna who makes all the important decisions, _____________.A. so as to speakB. only to speakC. so to speakD. just for speaking50. Having discussed the first item on the agenda at great length, the committee went on _____________ the remainder.A. dealing briefly withB. for dealing briefly withC. to deal briefly withD. deal briefly with51. The policeman couldn ’t swear _____________ the accused man at the scene of the crime.A. to having seenB. to have seenC. having seenD. so as to see52. He ’s a good person _____________ if ever you ’re in a tough time. A. to be with him B. to be withC. just to be with himD. in order to be with53. Investors must be careful _____________ with worthless shares from the large number of companies that are going bankrupt. A. not to be left B. not being left C. not to leave D. of not being left54. The country must step up the construction of the deep ports required _____________.A. of unloading oil tankersB. for unloading of oil tankersC. of the unloading oil tankersD. for the unloading of oil tankers 55. I know my hair needs _____________, but I don ’t have time to go to have it cut.A. being cutB. be cutC. cuttingD. to cut 56. His carelessness is such _____________ it unlikely that he will pass the examination.A. as to makeB. as to makingC. so as to makeD. only to make57. It was a bit of shock: I _____________ so much for a sandwich and a glass of beer.A. am not used to payB. am not used to payingC. haven ’t got used to payD. did not used to paying58. As a senior student, you are supposed to know better than just密封线内禁止答题_____________ until the examination time.A. fooled aroundB. to fool aroundC. having fooled aroundD. to have fooled around59. Mark does not take his schoolwork seriously. _____________, no one expects a millionaire ’s son to work hard.A. HoweverB. ConverselyC. But thenD. Nevertheless 60. James Joyce ’s novels are difficult to understand and impossible _____________ into another language.A. to translateB. for translationC. to translate itD. being translated61. When the children returned home, _____________, parents began to complain.A. covered in dustB. covering in dustC. to be covered in dustD. having covered in dust62. Since he completed his degree, he has had three jobs, _____________ than the last. A. each one better B. each one to be better C. each one was better D. each one has been better63. The children had a week ’s holidays, _____________ because of an influenza epidemic.A. the school has closedB. the school being closedC. the school to be closedD. the school be closed64. They decided to re-visit Edinburgh, _____________ by the beauty of its buildings on a previous visit.A. struckB. to be struckC. having been struckD. being struck65._____________ with other children of the same age, Robert is very tall.A Comparing B. To compare C. Compared D. Being compared 66._____________, he was confined for four months in psychiatric hospital.A. Having been declared insaneB. Being declared insane caughtC. Having declared insaneD. Declaring insane67. “Who was at the door?” “_____________ was a priest or someone wanting to talk about religion.” A. He B. It C. This D. There68. The four goals showed that the team had lost _____________ their old abilities.A. no one ofB. nothing ofC. no ofD. none of69. I suppose _____________ never occurred to you to ask the police for assistance.A. somethingB. anythingC. itD. that70. Committee members are quarrelling, _____________ of being responsible for the error.A. each accusing the otherB. one accusing anotherC. each accusing otherD. one accusing the otherPart ⅡFill in the blanks with the appropriate form of the verbs inbrackets. (25 minutes)71. As regard absolute proof, there is none. If there _____________(be),it _____________(be) a bad sign.72. We are going to have an exam tomorrow. I wish the teacher _____________(give, not) us one. 73. I ’d rather you _____________(call) tomorrow afternoon. I shall be entertaining visitors.74. If only you _____________(tell) Jackie what I said.75. It ’s very late. It ’s time we _____________(be) leaving.76. I thought I had a dollar in my pocket, but there ’s none. I _____________(spend) it.77. They each _____________(play) several instruments.78. Many a famous pop singer _____________ (ruin) by drugs.79. Neither of the room _____________(be) very big, but bother of them _____________(be) cool and airy. 80. Some cattle _____________(be) peacefully grazing between the forest and the river.81. Her means _____________(reduced, greatly) when here husband suddenly lost his job.82. The statistics _____________(show) that, in general, women live longer than men and both groups live longer than they did 100 years ago.密封线内禁止答题83. Very large quantities of aid _____________(need).84. A series of debates between the major candidates _____________(schedule) for the Labor Day weekend. 85. A servant or two _____________(accompany) her.86. I should prefer _____________(stay) at home rather than _____________(go out) in this weather.87. I prefer _____________(do) things to _____________(read) books. 88. The speaker said he would confine himself _____________(try) _____________(answer) four questions.89. The committee could see no alternative _____________(follow) the plan in its original form.90. He couldn ’t have passed the exam without resorting _____________(cheat).Part Ⅲ Correct errors in following sentences. It is not necessary towrite the whole sentence on the Answer Sheet. Write the wrong part and the correct part separately. (15 minutes) 91. It ’s a pity I have grown up. If I was a boy again, I would train myself to havecourage.92. Not only he can swim but also he can dance.93. I often hear grown-up people to say what you should do and what you should not do.94. I couldn ’t stand the weather at first but I used to it now. 95. I recall the time I studyed in high school.96. You can only locate the place where the book is in. 97. We talked about something happened in high school. 98. That is she told me.99. She couldn ’t swim, nor did I.100. The exam is coming. Now I have no alternative but reading the books.。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
9、写出连续系统无失真传输的时域条件和频域条件。 NhomakorabeaA卷
第 2 页 共 5 页
10、某系统的系统函数为 H ( s )
( s 2 )( s 1) ( s 0 . 5 )( s 2 . 5 )( s 3 )
，求：系统的单位冲激
响应的初值 h ( 0 ) 和终值 h ( ) 。
s(t)= co s1 0 0 0 t, t
0, f (t) 1 S a ( t) cos 1000t, t
,
。求响应 y(t).
A卷
第 3 页 共 5 页
图3
西北工业大学命题专用纸
四（10 分）图 4 为线性时不变零状态因果离散系统， （1）写出系统的差分方 程； （2）求系统函数 H（z） ，画出 H（z）的零、极点分布图； （3）写出系 统的模频特性与相频特性的表达式。
y = 0 . 5 1
x1 + 1 f x2
（1）系统的状态转移矩阵 (t ) ； （2）冲激响应矩阵 h (t ) 。
A卷
第 5 页 共 5 页
；(其中 E 为差分算子或位移算子)
（3）系统的单位序列响应 h（k）的波形如图 5 所示。
A卷
第 4 页 共 5 页
西北工业大学命题专用纸
六（10 分）已知系统的状态空间方程为
x 1 1 1 x 2
0
x 1 1 f 3 x 2 0
)d
A卷
第 1 页 共 5 页
4、已知信号 f(t)=
s in 2 t t
cos 1000t
，求其频谱函数 F ( j ) 。
sin 2 t 进行理想抽样时的最大允许抽样间隔 T。 5、求信号 f ( t ) 2t
2
6、求单边拉氏变换 F ( s )
e
(s2)
编号：
西北工业大学考试试题（卷）
2004 开课学院 八院 --2005 课程 学年第 信号与系统 2 小时 2 学期
成 绩 80
学时
考试日期 2005.7.4 考生班级
考试时间 学 号
考试形式（闭） （A）卷 姓 名
一、解答题（每小题 5 分，共 50 分） 1、已知离散信号 f1(k)与 f2(k)的波形如图 1 所示，设 y ( k ) y(-2),y(2)的值。
f 1 ( k ) f 2 ( k ) ,求：
西北工业大学命题专用纸
2、求信号 f(k)=(k+3)U(k)的 Z 变换 F(z)，并指出其收敛域。
3、求下列各式的值： （1） 2 ( t )
sin 2 t t
dt
（2）
t
( cos
2
) (1
2
二（10 分）图 2 所示系统， （1）求系统函数 H ( s )
Y (s) F (s)
； （2）求 K 为何值时
系统为临界稳定系统； （3）求在临界稳定条件下系统的单位冲激响应 h(t)。 （注意箭头方向！ ）
西北工业大学命题专用纸
三（10 分）图 3（a）所示系统中， H (j ) 为理想低通滤波器的传输函数，其图 形如图 3（b）所示， ( )
五（10 分）根据下列描述离散系统的不同形式，分别求出各系统的系统函数 H(z)。 （1） y ( k ) 2 y ( k
1) y ( k 2 ) f ( k 1) f ( k 2 ) ；
（2） H ( E )
E
6E
3
2
17 E 19
2
8E
17 E 10
s 2
的原函数 f(t)。
西北工业大学命题专用纸
7、已知离散系统的系统函数 H ( z ) 求 A 的取值范围。
z
0 .5 z 1
2
0 . 5 ( A 1) z 3 A
，欲使系统稳定工作，
8、已知离散系统的系统矩阵 A=
5 3
1 1
，求该系统的自然频率。