2017年华侨大学832信号与系统考研专业课真题试卷
2017年华侨大学考研试题834电路+
华侨大学2017年硕士研究生入学考试专业课试卷（答案必须写在答题纸上）招生专业电气工程科目名称电路科目代码834一、计算题（注：本大题共10小题，共126分）1、试用回路电流法求图1所示电路的电压u。
（12分）图1图22、电路节点编号如图2所示，请选择适合的参考节点，用节点电压法求解1V电压源的功率，并说明是提供还是消耗。
（15分）。
3、如图3所示电路，N R为不含独立源的线性纯电阻电路，其内部结构不详。
已知：当u s=1V，i s=1A时，u2=1V，当u s=10V，i s=2A时，u2=6V。
求当u s=4V，i s=10A时的电压u2。
（12分）图3图4共4页第1页4、图4所示电路中，开关合在位置1时已达稳定状态，0t =时开关由位置1合向位置2，用三要素法求0t ≥时的()L i t 。
(12分)5、图5所示的正弦稳态电路，已知电源的频率为f 时，电流表A 和A 1的读数分别为0和1A ，若电源的频率变为0.5f 而幅值不变，则电流表A 的读数为多少？(12分)图5图66、已知图6中对称三相电源的相电压为2200A U ︒=∠ ，220120BU ︒=∠- ，220120C U ︒=∠ ，L Z j =Ω，126Z j =+Ω，求1I ，2I ，3I 。
（15分）7、图7所示的电路中，1R =Ω，12L ω=Ω，232L ω=Ω，耦合因数1k =，132Cω=Ω。
求电流1I ，和电压2U 。
（12分）图7图88、已知图8所示二端口的Z 参数矩阵为10 8 5 10Z ⎡⎤=Ω⎢⎥⎣⎦求R 1、R 2、R 3、r 的值。
（12分）共4页第2页9、如图9所示电路原处于零状态。
0t =时刻，开关S 闭合，用运算法（拉普拉斯变换法）求()L i t ，(0)t >。
（12分）图9图1010、图10所示非线性电阻电路中，非线性电阻的伏安特性为32u i i =+，如果()0.1cos V s u t t ω= 时，试用小信号分析法求回路中的电流i 。
【2016年华侨大学考研真题考研真题】844专业课试卷
5．下表所列真值表的逻辑功能所表示的逻辑器件是（ 输入
）。 输出
I7 I6 I5 I4 I3 I2 I1 I0 Y2 Y1 Y0 1 ××××××× 1 1 1
0 1 ×××××× 1 1 0
0 0 1 ××××× 1 0 1
0 0 0 1 ×××× 1 0 0
0 0 0 0 1 ××× 0 1 1
华侨大学 2016 年硕士研究生入学考试专业课试卷
（答案必须写在答题纸上）
招生专业 电子科学与技术、电子与通信工程 科目名称 专业基础综合（信号与系统、数字电路）
科目代码 844
数字电路部分（75 分）
一、选择题（3 分/每题，共 21 分， 单选题）。
1．-91 的补码是（ ）。
A．01011011
C． F(A, B,C) m(0, 2,3, 4)
D． F(A, B,C) m(2, 4,6,7)
4．下列各函数等式中无冒险现象的函数式有（ ）。
A． F AC BC
B． F BC AC AB
C． F BC AC AB AB
D． F BC AC AB BC AB AC
4、积分式 4 (t2 3t 2)[ (t) 2 (t-2)]dt 的积分结果是（ 4
A．14
B．24
C．26
5、下列哪个系统不属于因果系统（ ）
A. 离散 LTI 系统的 h(n) 0 n 0 B. 累加器
） D．28
C. LTI 系统 h(t) e2tu(t) ，
D. y(n) x(n) x(n 1) 。
四、计算题(每小题 8 分，共 24 分)
1、已知因果线性时不变系统，其初始状态为零，冲激响应 h(t) (t) 2e2tu(t) ，系统的
华侨大学信号与系统2009—2018(缺2017)年考研真题试题
（3)在如图(b)所示系统中，若要求 y(t) f1(t) ，试确定 f2 (t) 的周期 T 及框图中 H ( j) 。
5、（12 分）系统如图示，设激励为 f(t)，响应为 y(t)。 (1)求系统的微分方程及系统函数 H (s) ，并判断系统能否无失真传输；
(2)为使系统的零状态响应为 y(t) cos 2(t 1) 2sin 2(t 1)e(t 1) (t 1) ，求激励 f(t)。
，
h4
t
t ，试求：
（1） H1 j，并粗略画出其图形；
（2）整个系统的冲激响应 h(t) ；
（3）当输入为
f
(t)
sin 3ct
cos
c 2
t
时，求输出信号
y(t)
。
（15 分）
f (t)
h1 t
h3 t
h4 t y(t)
H2 j
共4页 第4页
5
华侨大学 2012 年硕士研究生入学考试专业课试卷
2、判断下述命题是否正确，并加以验证或说明（共 16 分，每小题各 8 分）：
（1）若 r(t)
et (t) (t
k
3k)
，则
r(t)Leabharlann Aet，0t
3 ，且
A
1 1 e3
。
（2）理想滤波器的幅频特性如图（a）所示，相频特性() 0 。当滤波器的输入信号
f(t)是 T=1ms 的方波时（如图（b）所示），则滤波器的输出为： 0.5 0.424sin 2 103t 。
5、已知系统函数
H (s)
2s 5 s2 5s
6
，分别画出直接形式和并联形式的信号流图，并利
用所画并联形式的流图建立状态空间方程。
华侨大学管理信息系统2009--2015,2017考研专业课真题试卷
先进的财务管理系统，利用先进的信息技术推动公司管理水平不断迈向新台阶。
理论上民航业好像很简单，上海航空公司信息技术部王经理说：“民用航空运输业就是把客人从甲地送到乙地”。
当然实际上要做的远多于此，也远比运输过程复杂。
关于航线、班次、时刻、营销策略、运行控制、人员配置和其他资源配置的决策都必须依据相关可用的信息做出。
可用的信息越多越及时，做出的决策就越好。
上海航空公司深知要做到这一点，关键是要把所有关于其运营、市场、财务和客户的数据整合起来，加以综合性分析。
如何使公司关键业务部门及时有效地访问到决策所需的信息，对于做出正确的决策是很重要的。
例如，商务部门可能需要信息来回答这样一些问题：旅客的旅行需求是什么？旅客预订的规律如何？每个航班的旅客数量、票价和收益如何？应该新开哪些航线？调整哪些航线？运行部门需要知道：航班运行问题的关键因素在哪里？航班应该如何调整、有多少机组资源可用、航班运行质量如何？由于所有这类信息都出自同一个权威性的来源，上海航空公司经理才能对未来的发展提出战略设想。
关键业务部门也能及时捕捉到市场的微妙变化，并进行需求预测。
由于上海航空公司能以更加智能和有效的方式利用其信息，使得这家航空公司在当今充满挑战的中国民航市场中更好地运营。
请你根据以上材料回答以下几个问题：（1）航空公司客运业务需要做些什么决策？每项决策需要什么信息？（2）案例中的“同一个权威性的来源”指什么？（3）你认为哪一类信息系统可以回答上海航空公司的商务部门和运行部门的问题？请说明系统的输入和输出？2.某公司是国内500强且在上市的大型企业。
为了提高管理水平和管理规范化程度，公司准备投入巨资实施ERP项目。
经过一番调研和比较后，公司决定委托某著名咨询公司为其实施信息化。
咨询方派出小组到该公司进行了实地调研后，给出一套调研咨询报告和流程重组、ERP实施方案。
方案的要点是：希望公司按照国际先进的管理模式，彻底改造企业原有的业务和运作流程，严格按ERP软件所给出的模式工作。
华侨大学自动控制原理2009--2017考研专业课真题试卷
1 初始状态 x 0 ，输入 u t 为单位阶跃函数。 1 9. （本题共 15 分） 离散系统见图所示， 其中传递函数为 G( s) 采样周期 T 1s 。试分析系统的稳定性。
r (t ) e (t ) Ts
H (s)
10 ，H ( s ) 1 ， s( s 1)
。其中 r，n 为输入，c 为输出。 K 0 , K1 , T 均为常数。
3． （本题共 15 分）单位反馈系统的闭环传递函数为
G( s)
( 1 s 1)( 1 s 1) ( m s 1) (T1 s 1)(T2 s 1) (Tn s 1)
求系统在单位斜坡函数作用下的稳态误差。
3、 （本题共 15 分）单位反馈系统的闭环传递函数为
G (s) ( 1 s 1)( 1 s 1) ( m s 1) (T1 s 1)(T2 s 1) (Tn s 1)
求系统在单位斜坡函数作用下的稳态误差。
4、 （本题共 20 分）已知单位反馈系统的开环传递函数 Gk ( s )
G ( s) H ( s)
20
K ( s 5) ( s 1)( s 3)
3
1
1
847
20 ( )
20 fT 0 1 A 0 0 0 0 0 0 0 1 b 0 1 0 1 -1 -2
o
( A, b)
1 j
1 0
0 0 11 0
20
T=1s
4
Ts
(z)
r (t )
1 e s
1 s ( s 1)
c(t )
G (s)
e * (t )
y (t )
共 3 页
大学信号与系统考题及答案
华侨大学信息科学与工程学院《信号与系统》期末考试试卷(A 卷)题 目 一 总 分 核分人 复查人 得分题目部分，（卷面共有100题，100分，各大题标有题量和总分）评卷人 得分一、解答题（100小题，共100分）1．画出下列各复合函数的波形。
(1)21()(4)f t U t =- (2)22()sgn(1)f t t =- (3)3()sgn[cos()]f t t π=2．分别判断题图所示各波形是连续时间信号还是离散时间信号，若是离散时间信号是否为数字信号？3．若输入信号为0cos()t ω，为使输出信号中分别包含以下频率成分：(1)0cos(2)t ω (2)0cos(3)t ω (3)直流请你分别设计相应的系统(尽可能简单)满足此要求，给出系统输出与输入的约束关系式。
讨论这三种要求有何共同性、相应的系统有何共同性。
4．电容1C 与2C 串联，以阶跃电压源()()t Eu t υ=串联接入，试分别写出回路中的电流()i t 及每个电容两端电压1()C t υ、2()C t υ的表示式。
5．求图所示电路中，流过电阻R 中的稳态电流i(t)恒为零时激励电压0sin ()t U t ω中的ω值。
6．已知12,2()0,2t t f t t ⎧-≤⎪=⎨>⎪⎩，2()(5)(5)f t t t δδ=++-，3()(1)(1)f t t t δδ=++-，画出下列各卷积的波形。
(1)112()()()s t f t f t =* (2)2122()()()()s t f t f t f t =** (3)313()()()s t f t f t =*7．如图所示电路，激励信号()sin ()e t U t =电感起始电流为零，求响应0()u t ，指出其自由响应和强迫响应分量，大致画出波形。
8．求下图所示系统的单位冲激响应()h t 。
9．已知1()1p H p p-=+，()()te t e U t =-求零状态响应并粗略画出输入输出波形。
2017年华侨大学考研试题826机械设计
5. 带传动在工作时，假定小带轮为主动轮，则带内应力的最大值发生在带
6. 在一定转速下，要减轻链传动的运动不均匀和动载荷，应 C. 增大链节距，减小链轮齿数 7. 蜗杆直径 d1 的标准化，是为了 A. 有利于测量 C. 有利于实现自锁 厚度 A. 减小 C. 不变 A. 单头、小导程角 C. 多头、小导程角 10. 采用变位蜗杆传动时 A. 仅对蜗杆进行变位 11. 与齿轮传动相比较， C. 同时对蜗杆与蜗轮进行变位 不能作为蜗杆传动的优点。 A. 传动平稳，噪声小 B. 传动效率高 C. 可产生自锁 D. 传动比大 12. 角接触轴承承受轴向载荷的能力，随接触角α 的增大而 A．增大 C. 不变 B. 减小 D．不定 。 B. 增加 D. 不能确定 的蜗杆。 B. 单头、大导程角 D. 多头、大导程角 。 B. 仅对蜗轮进行变位
轮
5. 在不完全液体润滑滑动轴承设计中， 限制 p 值的主要目的是 6. 阿基米德蜗杆传动变位的主要目的是为了
； 限制 pv 值的主
四、分析题：(本题共 15 分) （答案必须写在答题纸上） 在图示传动系统中，1 为蜗杆，2 为蜗轮，3 和 4 为斜齿圆柱齿轮，5 和 6 为直齿锥齿轮。 若蜗杆 1 主动，要求输出齿轮 6 的转速方向如图所示。若要使Ⅱ、Ⅲ轴上所受轴向力互 相抵消一部分，试确定（请将图自行移到答题纸上） ： 1） Ⅰ、Ⅱ、Ⅲ轴的转速方向（在图中标示） ； 2） 蜗杆 1、蜗轮 2 及斜齿轮 3 和 4 的螺旋线方向（在图中标示） ； 3） 蜗轮 2、斜齿轮 3、斜齿轮 4 和锥齿轮 5 在啮合点处的受力方向（Ft、Fr、Fa 在图中 画出） 。
8. 液体摩擦径向滑动轴承在所受外载荷不变的条件下， 当轴颈的转速增加时， 最小油膜
9. 起吊重物用的手动蜗杆传动，宜采用
华侨大学《信号与系统》证明题题库(A)答案
华侨大学信息科学与工程学院2010-2011学年二学期课程考试试卷答案(A 卷)课程名称：信号与系统 考试时间：120分钟 年级：xxx 级专业： xxx题目部分，（卷面共有50题，100分，各大题标有题量和总分） 一、证明（50小题，共100分）1．证明（1）设12112()nn i i nic c c c H p p p p p λλλλ==+++=++++∑则1()()()i nti i H p t c eu t λδ-==∑又12112()nnii nic c c c H p p p p p ααλαλαλαλ=+=+++=++++++++∑()11()()()()[()()]i nnk ttittiii i H p t c eu t ec eu t H p t e ααλααδδ----==∴+===∑∑（2）设()122()()rrc c c H p p p p λλλ=++++++则112()()()()r kr H p t c c t c t e u t δ-=+++而1221()12()()()()()()()[()()]rrr tr tc c c H p p p p H p t c c t c t eu t eH p t αλαααλαλαλαδδ----+=++++++++++=++=综合（1）（2）故[()()]()()tH p t e H p a t αδδ-=+得证2．证明[()()]()f t t t dt δϕ∞-∞''⎰{}()()[()]()()()()[()()]()[()()()()]()()[()]()()[()]()()()()[()()]()()()()[(f t t d t f t t t t f t t dtt f t t f t t dt f t t d t f t t d t f t t t t f t t dt f t t t t f ϕδϕδδϕδϕϕϕδϕδϕδδϕϕδδ∞∞∞-∞-∞-∞∞-∞∞∞-∞-∞∞∞-∞-∞''''==-'''=-+''=-+''''=--+-⎰⎰⎰⎰⎰{})()]()[()()()()]()[()()()()]t t dtt f t t f t t dt t f t t f t t dtϕδδϕδϕϕ∞∞-∞-∞∞∞-∞-∞''''''''''=+++⎰⎰⎰⎰()[()()2()()()()](0)(0)2(0)(0)(0)(0)t f t t f t t f t t dtf f f δϕϕϕϕϕϕ∞-∞''''''=++''''''=++⎰[(0)()]()[2(0)()]()[(0)()]()f t t dt f t t dt f t t dt δϕδϕδϕ∞∞∞-∞-∞-∞''''''=+-+⎰⎰⎰()()(0)()2(0)()(0)()f t t f t f t f t δδδδ''''''''∴=-+在这里利用了以下公式： ()()()()(0)()()(0)()()(1)(0)k k k t t dt t t dt t t dt ϕδϕδϕϕδϕϕ∞-∞∞-∞∞-∞⎧=⎪⎪''=-⎨⎪⎪=-⎩⎰⎰⎰ 3．证明2()()t t t dt δϕ∞-∞''⎰222()[()]()()()[()]t t d t t t t t t t dt ϕδϕδδϕ∞∞∞-∞-∞-∞''''==-⎰⎰2()2()()()t t t dt t t t dt δϕδϕ∞∞-∞-∞⎡⎤'''=-+⎢⎥⎣⎦⎰⎰22{2()()()[2()]}{()()()[()]}t t t t t t dt t t t t t t dt ϕδδϕδϕδϕ∞∞∞∞-∞-∞-∞-∞''''=----⎰⎰2()[2()]()2()()2()()()t t dt t t t dt t t t dt t t t dt δϕδϕδϕδϕ∞∞∞∞-∞-∞-∞-∞''''=+++⎰⎰⎰⎰2(0)[2()]()t t dt ϕδϕ∞-∞==⎰2()2()t t t δδ''∴=32()[()][2()]t t t t t t t δδδ''''===0证明()()(1)!()n n n t t n t δδ=-用归纳法()()(1)0!()t t t t δδδ==-()()()[()]()()()[()]t t t dt t t d t t t t t t t dt δϕϕδϕδδϕ∞∞∞∞-∞-∞-∞-∞''==-⎰⎰⎰()()()()()()t t t dt t t dt t t dt ϕδϕδϕδ∞∞∞-∞-∞-∞'=---⎰⎰⎰22()()(1)1!()()2()(1)2!()t t t t t t t t δδδδδδ'∴=-=-''==-⋅又33()()()[()]t t t dt t t d t δδϕδ∞∞-∞-∞'''''=⎰⎰33()()()[()]t t t t t t dt ϕδδϕ∞∞-∞-∞'''''=-⎰2()[3()()]t t t t t dt δϕϕ∞3-∞'''=-+⎰233()()()()t t t dt t t t dt δϕδϕ∞∞-∞-∞'''''=--⎰⎰(3)2()()t t dt δϕ∞-∞=-⋅⎰3()(32)()(1)3!()t t t t δδδ3'''∴=-⨯=-由归纳法可得()()(1)!()nn nt t t δδ=-4．证明：()()(3)tk r t e u t t k δ+∞-=-∞=*-∑其波形如下图所示。
2017年华侨大学真题710英语综合硕士研究生专业课考试试题
华侨大学2017年硕士研究生入学考试专业课试卷（答案必须写在答题纸上）招生专业英语语言文学科目名称英语综合科目代码710Part I Error Correction (10 points)Directions: In the following passage there are 10 mistakes, one in each numbered line. Read the passage and correct the mistakes. If you change a word, cross it out and write the substitute in the corresponding blank. If you add a word, put the insertion mark (∧) in the right place and write the word you want to add in the blank. If you delete a word, cross it out and put a slash (/) in the blank.Meanwhile, Qin Zongquan, who take charge of Caizhou a. _ take → took _ Province, ∧now managing to recruit soldiers to strengthen b. _was ∧now _his own troop. For this reason, Zongquan appointed Xu as c. _ troop → troops_ governor of Guangzhou Province and then tried to assembleXu’s soldiers to suppress the agrarian rebellion led by HuangChao. Xu, but, hesitated to lead his soldiers to follow the 1. ________________ command of Zongquan, so Zongquan dispatched his owntroops to trounce the troops of Xu. Known that he was not 2. ________________able to win the battle, Xu led his own soldiers and fled south. 3. ________________They plundered everywhere they arrived until they enteredLinting County via Nankang County. Soon afterwards theycaptured Zhangpu County and now there are tens of 4. ________________ thousands of soldiers in the army. Xu was suspicious andjealous in nature, and those commanders which were capable 5. ________________and talented were mostly killed for one or another reason.Chao himself was quite frightening that he might also be 6. ________________killed some day.When the troops arrived Nan’an County, Chao 7. _______________ persuaded his own forward commander to start rebel 8. _______________ against Xu. Chao said, ‘It is because of the threat underXu that we abandoned our ancestral tombs and wives andchildren to come over here to be thefts and robbers. It isagainst own will. Now Xu was sceptical and suspicious,and capable commanders and talented officers were sure to 9. _______________be killed. Every one of us cannot guarantee one’s own safetyeven for a single day, let alone achieve any success!’The forward commander was thoroughly disillusioned byChao. They looked into each other’s eyes and burst into tears.Soon afterwards, Chao and his forward commander selecteddozens of vigorous soldiers to ambush Xu among the bambooforest. These soldiers awaited Xu’s pass by and then jumped 10. _______________out from the forest to capture him. Xu was then imprisoned.Part II Grammar (30 points)(I) There are ten sentences in this section. Beneath each sentence there are four words or phrases marked A, B, C, and D. Choose the word or phrase that best completes the sentence. (10 points)1. He ought to dismiss the unqualified employees under his supervision, ________?A. should heB. ought heC. shouldn’t heD. oughtn’t he2. Sid spends as much time working as he ________.A. travels C. is travellingB. does travelling D. has been travelling3. My deskmate is a reserved person who seldom speaks to me. The underlined part means ________.A. talkativeB. considerateC. quietD. outgoing4. Some English words have no exact ________ in Chinese.A. equivalentsB. equitiesC. equalsD. equalities5. When Columbus embarked ________ his historic voyage, he never imagined that the world history would enter into a new era.A. uponB. inC. atD. to6. It is ________ stealing to take a thing away without permission of its owner.A. nothing better than C. anything rather thanB. nothing less than D. anything but7. The committee decided to call the meeting ________ because of the typhoon.A. onB. offC. aboutD. against8. If computers ________, many problems on space flight could not have been solved.A. had not been invented C. were not inventedB. are not invented D. have not invented9. Holland has two-thirds the inhabitants of the state of New York, ________ Holland.A. that size is four times of C. which size is four times ofB. which size is four times of D. which is four times the size of10. Having sought asylum in the West for many years, they were ________ granted it.A. definitelyB. fairlyC. eventuallyD. merely(II) There are ten sentences in this section. Each sentence has four parts underlined. The four underlined parts are marked A, B, C, and D. Identify the one underlined part that is wrong. (10 points)1. He suffers from diabetes, which are a kind of chronic disease.A B C D2. There are less diseases in the frigid zones than there are in the torrid zones.A B C D3. They are in the possession of a large amount of new information.A B C D4. The youth whom they said was the most advanced in the group was the leader.A B C D5. This propose was generally considered as not very practical.A B C D6. Many families managed to make do with very little income.A B C D7. Did you try to support your son? Did you give him any encouraged advice?A B C D8. We had all heard that it was a great dam, as modern than any of its kind in the world.A B C D9. It may have been at Christmas when John gave Mary a handbag.A B C D10. It is for he sat up all night with the patient that the doctor looks tired and sleepy.A B C D(III) Rewrite the sentences as required without altering their meanings. (10 points)1. We were eating dinner. Our guests arrived.Use ‘while’.2. The fields don’t require irrigation. The weather is dry in the summer.Use ‘until’.3. Many boys, having had few advantages in their youth, have nevertheless done great things for their country.Use ‘though’.4. How many days are there in February if it is a leap year?Use ‘29’.5. He said, ‘We love our county.’Put the sentence into an indirect speech.6. The other day I met a twelve-year-old boy.Put the sentence into an attributive clause.7. A new law is enacted. The law will increase social security taxes by thirty percent.Use ‘though’.8. John made her tell him everything.Transform the sentence into a passive-voice sentence.9. The meeting was cancelled because of the flu epidemic.Use ‘call’.10. You will make yourself more tired, keeping on your feet.Use ‘if’.Part III Reading Comprehension (50 points)Directions: There are 4 passages in this part. Each passage is followed by four questions or incomplete statements. For each question or statement, there are four choices marked A, B, C, and D. Choose only ONE that best answers the question or finishes the incomplete statement.Passage OneQuestions 1 to 5 are based on the following passage:The fridge is considered a necessity. It has been so since the 1960s when packaged food first appeared with the label: “store in the refrigerator.”In my fridgeless Fifties childhood, I was fed well and healthily. The milkman came daily, the grocer, the butcher, the baker, and the ice-cream man delivered two or three times a week. The Sunday meat would last until Wednesday and surplus bread and milk became all kinds of cakes. Nothing was wasted, and we were never troubled by rotten food. Thirty years on, food deliveries have ceased, fresh vegetables are almost unobtainable in the country.The invention of the fridge contributed comparatively little to the art of food preservation.A vast way of well-tried techniques already existed—natural cooling, drying, smoking, salting, sugaring, bottling…What refrigeration did promote was marketing—marketing hardware and electricity,marketing soft drinks, marketing dead bodies of animals around the globe in search of a good price.Consequently, most of the world’s fridges are to be found, not in the tropics where they might prove useful, but in the wealthy countries with mild temperatures where they are climatically almost unnecessary. Every winter, millions of fridges hum away continuously, and at vast expense, busily maintaining an artificially-cooled space inside an artificially-heated house—while outside, nature provides the desired temperature free of charge.The fridge’s effect upon the environment has been evident, while its contribution to human happiness has been insignificant. If you don’t believe me, try it yourself, invest in a food cabinet and turn off your fridge next winter. You may miss the hamburgers, but at least you’ll get rid of that terrible hum.1.The statement “In my fridgeless Fifties childhood, I was fed well and healthily.” (Line 1,Para.2) suggests that _______.A) the author was well-fed and healthy even without a fridge in his fiftiesB) the author was not accustomed to use fridges even in his fiftiesC) there was no fridge in the author’s home in the 1950sD) the fridge was in its early stage of development in the 1950s2.Why does the author say that nothing was wasted before the invention of fridges?A) People would not buy more food than was necessary.B) Food was delivered to people two or three times a week.C) Food was sold fresh and did not get rotten easily.D) People had effective ways to preserve their food.3.Who benefited the least from fridges according to the author?A) Inventors.B) Consumers.C) Manufacturers.D) Travelling salesmen.4.Which of the following phrases in the fifth paragraph indicates the fridge’s negative effecton the environment?A) “Hum away continuously”.B) “Climatically almost unnecessary”.C) “Artificially-cooled space”.D) “With mild temperatures”.5.What is the author’s overall attitude toward fridges?A) Neutral.B) Critical.C) Objective.D) Compromising.Passage TwoQuestions 6 to 10 are based on the following passage:The human brain contains 10 thousand million cells and each of these may have a thousand connections. Such enormous numbers used to discourage us and cause us to dismiss the possibility of making a machine with human-like ability, but now that we have grown used to moving forward at such a pace we can be less sure. Quite soon, in only 10 or 20 years perhaps, we will be able to assemble a machine as complex as the human brain, and if we can we will. It may then take us a long time to render it intelligent by loading in the right software or by altering the architecture but that too will happen.I think it certain that in decades, not centuries, machines of silicon will arise first to rival and then exceed their human ancestors. Once they exceed us they will be capable of their own design. In a real sense they will be able to reproduce themselves. Silicon will have ended carbon’s long control. And we will no longer be able to claim ourselves to be the finest intelligence in the known universe.As the intelligence of robots increases to match that of humans and as their cost declines through economies of scale we may use them to expand our frontiers, first on earth through their ability to withstand environments, harmful to ourselves. Thus, deserts may bloom and the ocean beds be mined. Further ahead, by a combination of the great wealth this new age will bring and the technology it will provide, the construction of a vast, man-created world in space, home to thousands or millions of people, will be within our power.6.In what way can we make a machine intelligent?A) By making it work in such environments as deserts, oceans or space.B) By working hard for 10 or 20 years.C) By either properly programming it or changing its structure.D) By reproducing it.7.What does the writer think about machines with human-like ability?A) He believes they will be useful to human beings.B) He believes that they will control us in the future.C) He is not quite sure in what way they may influence us.D) He doesn’t consider the construction of such machines possible.8.The word “carbon” (Line 4, Para.2) stands for _________.A) intelligent robotsB) a chemical elementC) an organic substanceD) human beings9. A robot can be used to expand our frontiers when _______.A) its intelligence and cost are beyond questionB) it is able to bear the rough environmentC) it is made as complex as the human brainD) its architecture is different from that of the present ones10.It can be inferred from the passage that _______.A) after the installation of a great number of cells and connections, robots will be capableof self-reproductionB) with the rapid development of technology, people have come to realize the possibilityof making a machine with human-like abilityC) once we make a machine as complex as the human brain, it will posses intelligenceD) robots will have control of the vast, man-made world in spacePassage ThreeQuestions 11 to 15 are based on the following passage:It is, everyone agrees, a huge task that the child performs when he learns to speak, and the fact that he does so in so short a period of time challenges explanation.Language learning begins with listening. Individual children vary greatly in the amount of listening they do before they start speaking, and late starters are often long listeners. Most children will “obey” spoken instructions some time before they can speak, though the word obey is hardly accurate as a description of the eager and delighted cooperation usually shown by the child. Before they can speak, many children will also ask questions by gesture and by making questioning noises.Any attempt to trace the development from the noises babies make to their first spoken words leads to considerable difficulties. It is agreed that they enjoy making noises, and that during the first few months one or two noises sort themselves out as particularly indicative of delight, distress, sociability, and so on. But since these cannot be said to show the baby’s intention to communicate, they can hardly be regarded as early forms of language. It is agreed, too, that from about three months they play with sounds for enjoyment, and that by six months they are able to add new sounds to their repertoire. This self-imitation leads on to deliberate imitation of sounds made or words spoken to them by other people. The problem then arises as to the point at which one can say that these imitations can be considered as speech.11.By “…challenges explanation” (Line 2, Para.1) the author means that ________.A) no explanation is necessary for such an obvious phenomenonB) no explanation has been made up to nowC) it’s no easy job to provide an adequate explanationD) it’s high time that an explanation was provided12.The third paragraph is mainly about ______.A) the development of babies’ early forms of languageB) the difficulties of babies in learning to speakC) babies’ strong desire to communicateD) babies’ intention to communicate13.The author’s purpose in writing the second paragraph is to show that children ______.A) usually obey without asking questionsB) are passive in the process of learning to speakC) are born cooperativeD) learn to speak by listening14.From the passage we learn that _______.A) early starters can learn to speak within only six monthsB) children show a strong desire to communicate by making noisesC) imitation plays an important role in learning to speakD) children have various difficulties in learning to speak15.The best for this passage would be ______.A) How Babies Learn to SpeakB) Early Forms of LanguageC) A Huge Task for ChildrenD) Noise Making and Language LearningPassage FourQuestions 16 to 20 are based on the following passage:Psychologists take opposing views of how external rewards, from warm praise to cold cash, affect motivation and creativity. Behaviorists, who study the relation between actions and their consequences, argue that rewards can improve performance at work and school. Cognitive researchers, who study various aspects of mental life, maintain that rewards often destroy creativity by encouraging dependence on approval and gifts from others.The latter view has gained many supporters, especially among educators. But the careful use of small monetary rewards sparks creativity in grade-school children, suggesting that properly presented inducements indeed aid inventiveness, according to a study in the June Journal of Personality and Social Psychology.“If kids know they’re working for a reward and can focus on a relatively challenging task, they show the most creativity,” says Robert Eisenberger of the University of Delaware in Newark. “But it’s easy to kill creativity by giving rewards for poor performance or creating too much anticipation for rewards.”A teacher who continually draws attention to rewards or who hands out high grades for ordinary achievement ends up with uninspired students, Eisenberger holds. As an example of the latter point, he notes growing efforts at major universities to tighten grading standards and restore failing grades.In earlier grades, the use of so-called token economies, in which students handle challenging problems and receive performance-based points toward valued rewards, shows promise in raising effort and creativity, the Delaware psychologist claims.16.Psychologists are divided with regard to their attitudes toward ______.A) the choice between spiritual encouragement and monetary rewardsB) the amount of monetary rewards for student’ creativityC) the study of relationship between actions and their consequencesD) the effects of external rewards on students’ performance17.What is the response of many educators to external rewards for their students?A) They have no doubts about them.B) They have doubts about them.C) They approve of them.D) They avoid talking about them.18.Which of the following can best raise students’ creativity according to RobertEisenberger?A) Assigning them tasks they have not dealt with before.B) Assigning them tasks which require inventiveness.C) Giving them rewards they really deserve.D) Giving them rewards they anticipate.19.It can be inferred from the passage that major universities are trying to tighten theirgrading standards because they believe ______.A) rewarding poor performance may kill the creativity of studentsB) punishment is more effective than rewardingC) failing uninspired students helps improve their overall academic standardsD) discouraging the students’ anticipation for easy rewards is a matter of urgency20.The phrase “token economies” (Line 1, Para.5) probably refers to ________.A) ways to develop economyB) systems of rewarding studentsC) approaches to solving problemsD) methods of improving performancePart IV Linguistics (30 points)(I) Define the following terms with examples where necessary. (9 points)(1) arbitrariness(2) phonology(3) inflectional morphemes(II) Put “T” for true and “F” for false for the following statements. (10 points)(1) Languages cannot be used to refer to things which are present or not present, real or imagined matters in the past, present, or future. ( )(2) Complete synonyms, i.e. synonyms that are mutually substitutable under all circumstances, are rare. ( )(3) A perlocutionary act is the act performed by or resulting from saying something; it is the consequence of, or the change brought about by the utterance; it is the act performed by saying something. ( )(4) When someone is not saying in an explicit and straightforward manner what he means to say, rather he is trying to put across his message in an implicit, roundabout way, we can say he is using indirect language. ( )(5) Homonymy refers to the phenomenon that words having different meanings have the sameform, i.e., different words are identical in sound or spelling, or in both. ( )(III) Discuss briefly the similarities and differences between language acquisition and second language acquisition. (5 points)(IV) Try to think of a context in which the following sentences can be used for other purposes than just stating fact. (6 points)(1) The music of the movie is good.(2) You have been keeping my notes for a whole week now.Part V British and American Literature (30 points)(I) Fill in the following blanks with appropriate items of information. (10 points)1.Paradise Lost, written by _____①____, is an epic based on the biblical story of Satan,Adam and Eve.2. Tom Jones, a novel written by ②, offers a panoramic view of EnglishSociety in the author’s times.3. Laurence Sterne’s _______③_______is an experimental novel with its unusual narrativestrategies.4. The publication of Lyrical Ballads in 1798 by William Wordsworth (1770-1850) and_______④_________ (1772-1834), is a significant event in English literary history.5. A Tale of Two Cities, set in London and Paris is ________⑤______s’ best-knownhistorical novel.6. _________⑥__________, the tragic story of a pure country girl, has been read as one ofThomas Hardy’s best-known novel.7. ________⑦_________ and _______⑧______ are the most important authors of AmericanTranscendentalism.8. The Wings of the Dove (1902), The Ambassadors (1903) and The Golden Bowl (1904) weresuccessful novels by __________⑨_________ in the early 20th century.9. In 1961, Joseph Heller published his__________⑩___________, a classic of BlackHumor.(II) Comment briefly on ANY ONE of the following topics. (20 points)1. Gothic fiction2. Chaucer’s The Canterbury Tales3. A story by or novel by Nathanial Hawthorne。
华侨大学2017年《830光学》考研专业课真题试卷
（答案必须写在答题纸上）
招生专业 科目名称
光学工程 光学 1)什么是光学系统的孔径光阑和视场光阑? (10 分) (2) 什么叫理想光学系统？(10 分) (3) 什么是理想光学系统的分辨率？写出望远镜的分辨率表达式。(10 分) 2 一个直径为 400mm 的玻璃球，折射率为 1.52。球内有两个小气泡，看上去一个恰好在 球心，另一个从最近的方向去看，在球表面和中心的中间，求两气泡的实际位置。(15 分) 3 一架幻灯机的投影镜头的焦距为 7.5 cm．当屏幕离镜头 8 m 远时呈清晰图像．现将屏 幕拉至 10 m 远处，镜头须改变多少位置才能再呈清晰图像？ (20 分) 4 一架显微镜，物镜焦距为 4mm，中间像成在第二焦面（像方焦点）后 160mm 处，如 果目镜为 20 倍，则显微镜的总放大率为多少？(15 分) 5 用波长＝500 nm (1 nm＝10-9 m)的单色光垂直照射在由两块玻璃板(一端刚好接触成 为劈棱)构成的空气劈形膜上． 劈尖角＝2×10-4 rad． 如果劈形膜内充满折射率为 n＝1.40 的液体．求从劈棱数起第五个明条纹在充入液体前后移动的距离．(20 分) 6 在某个单缝衍射实验中，光源发出的光含有两秏波长1 和2，垂直入射于单缝上．假 如1 的第一级衍射极小与2 的第二级衍射极小相重合，试问 (20 分) (1) 这两种波长之间有何关系？ (10 分) (2) 在这两种波长的光所形成的衍射图样中，是否还有其他极小相重合？(10 分) 7 在双缝干涉实验装置中，幕到双缝的距离 D 远大于双缝之间的距离 d．整个双缝装置 放在空气中．对于钠黄光，＝589.3 nm(1nm=10 9m)，产生的干涉条纹相邻两明条纹的 角距离(即相邻两明条纹对双缝中心处的张角)为 0.20°．(20 分) (1) 对于什么波长的光，这个双缝装置所得相邻两明条纹的角距离将比用钠黄光测 得的角距离大 10％？ (10 分) (2) 假想将此整个装置浸入水中(水的折射率 n＝1.33)， 相邻两明条纹的角距离有多 大？ (10 分) 8 有三个偏振片叠在一起,已知第一个偏振片与第三个偏振片的偏振化方向相互垂直,一 束光强为 I0 的自然光垂直入射在偏振片上，已知通过三个偏振片后的光强为 I0 / 16．求 第二个偏振片与第一个偏振片的偏振化方向之间的夹角．(10 分)
华侨大学832信号与系统2016-2017年考研专业课真题试卷
（1） 求系统的冲激响应
（2） 求输出响应 r t 。
5、(12 分)离散系统如图示
xn +
z 1
++
+
yn
+
0.2 0.8
z 1
（1）写出系统的差分方程式； （2）求系统函数并画出零极点图； （3）求系统的单位脉冲响应。
共 5 页 第 4页
招生专业 信华息侨与大通信学工2程017年考研专业课真题试卷（原版）
科目名称
信号与系统
科目代码 832
6、(15 分)离散系统如图示
xn
1 2
z 1
1 4
yn
z 1
1 3
（1）求系统函数； （2）画出系统的零极点图并判断系统的稳定性； （3）求系统的单位脉冲响应； （4）定性地画出幅频响应特性曲线。
7、（12 分）已知系统的传输算子表达式为 H ( p)
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华侨华大侨学大2学021071年7年硕考士研研专究业生课入学真考题试试专卷业（课原试版卷）
作为激励信号，用时域卷积法求系统的零状态响应。
h1(t)
et
r(t)
h2 (t) h1(t) h3(t)
图 2.1
2、 (15 分 )图 示 系 统 中 ， 已 知 f t e jnt t , n为整数 ， n
s t cos t t ，系统函数 H 如下图示，试画出 A,B,C 各点信号的频
2010信号与系统(B)_(答案)
华侨大学2010 — 2011学年《信号与系统》考试试卷（Ｂ）答案一、请填入正确答案（共30分，每小题3分）：（1）0sin[(3)(2)]t t dt ωδ∞--⎰=t ωsin -。
（2）dtt t t )('))sin(31(3δπ⎰∞∞-++=π。
（3）周期序列)305.2cos(50+k π的周期N = 4 。
（4）已知f （t ）的频带宽度为Δω，则⎪⎭⎫⎝⎛-321t f 的频带宽度为ω∆21。
（5）连续信号占有的频带宽度为0-10KHz ，经采样间隔为T 的采样，为保证能够从采样数据信号中恢复出原始信号，则采样频率最小应为 20KHz 。
（6）若)()()(t h t f t y *=，则=*)3()3(t h t f )3(31t y 。
（7）信号 )3()()(--=t t t f εε的单边拉氏变换为se 31--。
（8）系统信号流图如图所示，则系统函数H （s ）=()()Y s F s =cs b s a+-。
F （s ）Y （s ）abc1/s1（9）()cos()()2x n n n πε=的Z 变换()X z ＝122+z z 。
（10）某因果系统的系统函数1221)(234++++=s s s s s H ,则该系统是否为稳定系统？不稳定 。
二、基本概念题：（每小题6分，共12分）（1）证明π=⎰∞∞-dt tt sin证明：0sin sin =∞∞-⎥⎦⎤⎢⎣⎡=⎰ωt t F dt t t()[]()πωπωωω===⎥⎦⎤⎢⎣⎡===/2002sin g t Sa F t t Fπ=∴⎰∞∞-dt tt sin（2）设系统的初始状态为x (0)，激励为 f (t )，设系统的全响应y (t)与激励和初始状态的关系如下，试判断下列系统是否为线性的、时不变的、因果的、稳定的？()()ττd f )0(x e t y t1t t2⎰-+=解：a. 响应满足分解特性，零输入响应显然是初始状态的线性函数，即零输入线性。
华侨大学考研试题845信号与系统(2015年~2016年)
4
8
3
（1）系统的单位样值响应；
（2）画出系统级联形式的信号流图； （3）判断此系统是否稳定并说明理由。
7、（10 分）系统的流图如图所示，列出对应的状态方程和输出方程并写成矩阵形式。
共4页 第5页
（2）已知信号 f (t) 的拉氏变换 L[ f (t)] = F (s) ，求下列函数的单边拉氏变换。
1）1 − eαt ；
2） sin t + 2cost ；
3） te−2t
3、其他基本概念题（共 14 分，第 1 题 8 分，第 2 题 6 分）：
∫ （1= ） f (t) t(sin π t ) ⋅ (sin 2π t ) ，求积分 ∞ t2 (sin π t )2 (sin 2π t )2 dt 。
（答案必须写在答题纸上）
招生专业 科目名称
信息与通信工程 信号与系统
科目代码
845
第一部分、简答题（共 62 分）
1、请填入正确答案（共 30 分，每小题各 3 分）：
（1）积分 cos3t t 2 dt
。
2
4
（2） x[n] e j( 3 )n e j( 3 )n ，该序列的周期为
。
科目代码 845
第二部分、计算题（共 90 分）
1、（10 分）如图所示 LTI 组合系统，试求： 1) 将组合系统的冲激响应表示为各子系统冲激响应的函数；
2) 若 h= 1(t) h= 4 (t) u (t ) , h= 2 (t) h= 3(t) 5δ (t ) , h5 (t) = e−2tu (t ) ，求组合系统的冲激响应；
（2）求该系统的逆系统的阶跃响应；
（3）若该系统与另一因果 LTI 系统 S 并联得到的系统具有 t 的冲激响应，求系统 S 的单
华侨大学823信号与系统2021年考研专业课初试大纲
华侨大学硕士研究生招生考试初试自命题科目考试大纲招生学院：信息科学与工程学院招生专业：信息与通信工程/交通运输科目名称：信号与系统1、考试形式与试卷结构（1）试卷满分值及考试时间本试卷满分为150分，考试时间为180分钟。
（二）答题方式答题方式为闭卷、笔试。
试卷由试题和答题纸组成；答案必须写在答题纸（由考点提供）相应的位置上。
（三）试卷内容结构考试考试内容主要包括：信号与系统的基本概念(10%)，连续信号与系统的时域分析(10%)，连续信号与系统的频域分析(20%)，连续信号与系统的复频域分析(20%)，离散信号与系统的时域分析(10%)，离散信号与系统的Z域分析 (20%)，系统的状态空间分析(10%)。
（四）试卷题型结构第一部分简答题（60分）1．填空题（30分），共10小题；2．基础题（15分），共2-3道；3．其他基本概念题（15分），共2-3道；第二部分计算题（90分），共6-8题二、考查目标课程考试的目的在于测试考生关于信号与系统相关的基本概念、基本理论、基础知识的掌握情况以及信号与系统的综合分析能力。
三、考查范围或考试内容概要第一部分信号与系统的基本概念1.信号的描述和分类 信号的描述方法；确定信号与随机信号、连续信号与离散信号、周期信号与非周期信号、能量信号与功率信号； 2.信号的基本特性3.信号的基本运算相加和相乘；翻转、平移和展缩；信号的导数和积分；信号的差分和迭分；4.几个重要信号 连续时间阶跃信号；连续时间冲激信号；广义函数和δ函数的性质；阶跃序列和脉冲序列； 5.系统的描述 系统模型；系统的输入输出描述；系统的状态空间描述；系统的特性和分类。
第二部分连续信号与系统的时域分析 1.连续时间基本信号 奇异信号；正弦信号；指数信号； 2.卷积积分 卷积的定义；卷积的图解法；卷积性质；常用信号的卷积公式； 3.系统的微分算子方程微分算子和积分算子；LTI系统的微分算子方程；电路系统算子方程的建立； 4.连续系统的零输入响应零输入响应算子方程；简单系统的零输入响应；一般系统的零输入响应；5.连续系统的零状态响应连续信号的δ(t)分解；基本信号δ(t)激励下的零状态响应；一般信号f(t) 激励下的零状态响应。
华侨大学考研试题844专业基础综合(信号与系统、数字电路)(2015年~2016年)
2、某线性时不变系统的系统函数 H ( jω) =
2
，则该系统的单位冲激响应为
( jω + 2)( jω + 3)
h(n) _______。
3 、 在 RLC 串 联 谐 振 电 路 中 ， 品 质 因 数 Q 值 越 大 ， 则 谐 振 电 路 的 选 择 性 越 ________________。
共5页 第5页
5
华侨大学 2016 年硕士研究生入学考试专业课试卷
（答案必须写在答题纸上）
招生专业 电子科学与技术、电子与通信工程 科目名称 专业基础综合（信号与系统、数字电路）
科目代码 844
数字电路部分（75 分）
一、选择题（3 分/每题，共 21 分， 单选题）。
1．-91 的补码是（ ）。
− 1 ≤ t ≤ 2 t >1/ 2
1 2
，计算其傅里叶变换。（提示：利用微、积分特
3、考虑一个 LTI 系统，其输入和输出关系通过如下方程联系：
∫ y(t) = t e−(t−τ ) x(τ − 2)dτ ,求该系统的单位冲激响应和阶跃响应。 −∞
数字电路部分（75 分）
一、选择题（3 分/每题，共 21 分， 单选题）。
5．下表所列真值表的逻辑功能所表示的逻辑器件是（ 输入
）。 输出
I7 I6 I5 I4 I3 I2 I1 I0 Y2 Y1 Y0 1 ××××××× 1 1 1 0 1 ×××××× 1 1 0 0 0 1 ××××× 1 0 1 0 0 0 1 ×××× 1 0 0 0 0 0 0 1 ××× 0 1 1 0 0 0 0 0 1 ×× 0 1 0 0 0 0 0 0 0 1×0 0 1
D． (t) u(t)
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于
。 （5）若 y t x t h t ,则 y 2t
0
。 。
（6）信号 f t t d 的单边拉普拉斯变换为
（7）设 f t 为一有限带宽信号，频带宽度为 2kHz，试求 f 2t 的奈奎斯特 抽样率 f N ，抽样间隔 TN 。
。 。
（2）信号 x k e j 0.2 k e j 0.3k 的周期为 （3）已知冲激序列 T t 为 。
n
t nT ，其三角函数形式的傅里叶级数
t （4）设 f t 的频谱函数为 F j ，则 f 3 的频谱函数等 2
a0
y t
图 1.3.1
（2）证明： Sa 2 t dt
共 5 页
第 2 页
招生专业 科目名称
信息与通信工程 信号与系统
科目代码
832
（3）若图示信号 f t 的傅里叶变换 F j R jX ，求 y t 的傅里叶 变换 Y j 。
7、 （12 分）已知系统的传输算子表达式为 H ( p )
华侨大学 2017 年硕士研究生入学考试专业课试卷
（答案必须写在答题纸上）
招生专业 科目名称
信息与通信工程 信号与系统
科目代码
832
第一部分、简答题（共 60 分） 1、请填入正确答案（共 30 分，每小题各 3 分）： （1）积分
t
2
3t 1 2t 1 dt =
范围。
E s
H 1 s K
Y s
H 2 s
图 1.2.2
3、其他基本概念题（共 15 分，每小题各 5 分） （1）某连续系统的框图如图 2 所示，写出该系统的微分方程和传输算子 H p 。
f t
y t
y t a1
若输入信号为
et 5 3 cos t 2 cos 2t 0.5 cos 3t cos10 4 t
（1） 求系统的冲激响应 （2） 求输出响应 r t 。
5、(12 分)离散系统如图示
xn +
+ + 0 .2
z 1
+ +
z 1
y n
0.8
f t A cos t
y t C
B
H
图 2.2
共 5 页 第 3 页
招生专业 科目名称
信息与通信工程 信号与系统
科目代码
832
3、(12 分)电路及其激励 x t 如图所示，试用复频域分析法,求 t 0 时的 uC t ， 并指出零输入响应和零状态响应。
1 2 1F it uC t
（8）离散信号 x k 的单边 Z 变换 X z z 2 1 z 1 6 z 2 ， 冲序列表示，则 x k
2
x k 用单位脉
。 。
（9）信号 f k k 1 k 1 的 Z 变换式 F z
（10）已知 f1 k 0 , 1 , 2 , 3 , 4 ， f 2 k 1 , 1 , 1 , 1 , 0 , 0 0 k 0 k
2 1
1
f 1 t
f 2 t
1 t
0
1
0 1
2
t
图 1.2.1 （2）图示系统中 K 0 ，若系统具有 H s
H1 s
Y s 2 的特性，已知 E s
1 ，求 a) H 2 s ；b) 欲使 H 2 s 是稳定系统的系统函数，求 K 的取值 s3
（1）写出系统的差分方程式； （2）求系统函数并画出零极点图； （3）求系统的单位脉冲响应。
共 5 页
第 4页
招生专业 科目名称
信息与通信工程 信号与系统
科目代码
832
6、(15 分)离散系统如图示
xn
1 2
z 1
1 4
1
1 3
y n
（1）求系统函数； （2）画出系统的零极点图并判断系统的稳定性； （3）求系统的单位脉冲响应； （4）定性地画出幅频响应特性曲线。
，则卷积 f1 k f 2 k 。
共 5 页 第 1 页
招生专业 科目名称
信息与通信工程 信号与系统
科目代码
832
2、基础题（共 15 分，第 1 小题 5 分，第 2 小题 10 分) （1）信号 f1 t 和 f 2 t 的波形如图 1.2.1 所示，设 f t f1 t f 2 t ，求 f 0 。
xt 1H
1
i L t
2
0
xt 2e t t
4、(14 分)设有一系统，其频率响应为
H j
10 4 10 4 2 2 sin sin 4 6 6 10 4 10
2 0
f t
1 2
y t
t
-4
0
4
t
图 1.3.2 第二部分、计算题（共 90 分） 1、(10 分)图 2.1 所示系统由几个子系统组成，各子系统的冲激响应为
h1 t t ， h2 t t 1 ， h3 t t ，试求此系统的冲激响应 h t ；若以 e t e t t 作为激励信号，用时域卷积法求系统的零状态响应。
h1 (t)
et h2 (t )
h1 (t)
h3 (t )
r (t )
图 2.1
2、(15 分)图示系统中，已知 f t
n
e t , n为整数 ，
jnt
s t cos t
频谱图。
t ，系统函数 H 如下图示，试画出 A,B,C 各点信号的