山东科技大学研究生入学考试初试试题2007年 电路
山东科技大学系统工程2008,2009,2011--2019年考研真题
一、简答题（每题10分，共100分）1、简述系统的特性。
2、简述系统工程方法论的内容，并列举典型的系统工程方法论。
3、简述系统分析的内涵及意义。
4、简述系统结构和功能的关系。
5、回答系统模型的定义，并说明对模型的要求。
6、简述系统仿真的内涵。
7、简述不确定性决策的条件。
8、简述切克兰德方法论的主要内容和工作过程。
9、简述系统工程方法的特点。
10、简述费用和效益的含义。
二、计算题（共20分）根据图1所描述系统基本结构的有向图建立邻接矩阵A，并求其可达矩阵M。
S2S5S4图1三、综合题（共30分）请解释SWOT分析法的主要内容，并结合自身实际情况基于SWOT分析法做出研究生教育的生涯规划。
山东科技大学2008年招收硕士学位研究生入学考试一、定义（每题5分，共30分）1．系统工程2．系统分析3．系统仿真4．柔性战略5．技术创新6．黑箱方法二、简答题（每题5分，共30分）1．当代系统工程的新发展包括哪些内容？2．系统分析的原则有哪些？3．模型的简化有哪几个方法？4．SD中有哪些基本DYNAMO方程？5．一般系统论的基本观点？6．决策分析的程序？三、作图题（每题12分，共24分）1．绘出闭环控制系统的框图。
2．绘出系统评价程序示意图。
四、计算题 （共46分）1．有如下判断矩阵A ，求其权值，并进行一致性检验，其中：随机一致性指标R.I=0.58 （18分）A=⎪⎪⎪⎪⎭⎫ ⎝⎛1535113131312．某个体户由外地往北京运菜，如北京市场好，可按原价卖出3车；如市场为中可卖2车；如市场差，只能卖1车，每车6000千克，每千克赚1元。
如超过以上市场情况多运，则多运的部分要便宜处理，每千克损失5角。
按照以往的统计规律市场好的概率为0.3，中为0.5，差为0.2，求该问题的全情报价值。
（14分）3．某汽车股份公司根据2005年汽车需求量预测，制定了以下三个车身开发目标方案：1）全面引进技术，进口设备；2）全部依靠自己的力量，改造生产线；3）自行改造为主，技术引进为辅。
山东科技大学电路2007年考研真题
山东科技大学2007年招收硕士学位研究生入学考试 电路试卷一、单项选择题：(本大题共12小题，每小题5分，总计60分)在下列各题中，有四个备选答案，请将其中唯一正确的答案写到答题纸上，不要写在试卷上！1、图示正弦交流电路中，负载L Z 获得最大功率时，L Z 应为A.5Ω B. ()j35+ΩC. ()j35−ΩD.j3−Ω答 ( )LSU 2、若变压器的初级线圈和次级线圈的电感均为2H,线圈间的互感也为2H,则该变压器为A. 为理想变压器B. 线圈的匝数比为2C. 为全耦合变压器D. 以上三点全不正确 答( ） 3、今有10μF 的电容元件，充电到100 V 后从电路中断开，经10 s 后电压下降到36.8 V ，则该电容元件的绝缘电阻为 A. 100k Ω B. 1M Ω C. 10M Ω D. 20M Ω 答（ ）4、RLC 串联电路的R =4k Ω，L =4H ，C =1µF 。
该电路的暂态响应属于A. 衰减振荡情况B. 振荡情况C. 临界情况D. 非振荡情况 答( )5、图示正弦交流电路中，若21C L ωω>，且电流有效值A 41=I ，A 32=I ，则I 等于A. 7AB. 5A C1AD.2A答 ( )2C6、图示二端网络的电压电流关系为A. U I =+25B. U I =−25C. U I =−−25D. U I =−+25 答( )7、电路如图所示, 当t =0时开关断开, 已知()()i i 12000−−==,则()i 20+等于A.L L L I 112+SB. 0C.L L L I 212+SD.12L I S 答()28、图示电容元件的()u 00=，()i t =02. A ，则t 由0至50s 期间电容吸收能量为A.50 JB. 100 JC. 250 JD. 500 J答()02.9、图示正弦RLC 并联电路,测得图中各电流有效值分别为I =5A, I R =4A,I L =3A, 则i C 等于A. 1AB. 2AC. 6AD. 4A 答( )C+-10、图示正弦交流电路中，已知°∠=05SI &A ，则电路复功率(功率复量)S ~等于A. ()j3648−V AB. ()j3648+V AC.()j4836−V AD.()j4836+V A答 ( )Ωj3SI11、图示并联的有互感线圈的等效电感为A. L 1+L 2+2MB. L 1+L 2－2MC.L L M L L M 122122−+−D.L L M L L M122122−++ 答( )L 212、图示电路中i S =+(2410cos t )A ，则10Ω电阻消耗的功率为A. 20WB. 160WC. 80WD. 200W 答( )01.F二、非客观题( 本 大 题15分 ) 求图示电路中的i 1、i 2。
山东科技大学信号与系统2007--2019年考研真题
yf
(k)
2[(1 )k 2
1]U
(k)
。求系统的单位响应
h(k )
。（12分）
九、系统的微分方程为：
d 3 y(t) 5 d 2 y(t) 8 d y(t) d f (t) 3 f (t) ，请画出该系统
dt 3
dt 2
dt
dt
的信号流图，并判断其是否稳定。（14分）
山东科技大学2009年研究生入学考试 信号与系统试题
一、填空题（每空2分，共12分）
1、信号 f (t) (t) et (t) 的傅立叶变换等于
。
2、积分 e2t (t)dt 等于
。
3、信号 f (t) (1 t)et (t) 的拉普拉斯变换等于
。
4、象函数 F (z) z , z 1，原序列为
）
七、已知序列 f (k) 的 F (z) 如下，求初值 f (0) , f (1) 及终值 f (¥ ) 。 （12分）
（1） F (z) =
z2 + z + 1 ,
(z - 1)(z + 1)
2
z >1
（2） F (z) =
z2
, z>2
(z - 2)(z - 1)
、、离散时间系统，当激励 f (k) kU (k) 时，其零状态响应为
f (1) ,
f (k - 2) z 2 F ( z ) f ( 2) f (1) z 1
四．（15 分） 某LTI连续系统，其初始状态一定，已知当激励为 f (t ) 时，其全响应为 y1 e t cos( t ), t 0 ; 若初始状态不变时，激励为 2 f ( t ) 时，其
山东科技大学电工电子技术2004--2007,2014--2019年考研初试真题
一、填空(每题2分，共8分，答案请写在答题纸上)1. 如图所示理想电路，R = 1Ω，I =1A ，Us =5V ，Uab = ①Uab2. 在三相四线制供电的照明配电系统中，三相电流的相位对称，三相电流有效值分别为1A ，1A ，2A 。
系统中性线上的电流有效值为 ②3. 星形连接的三相电源，相电压为U ，其线电压为 ③4. 在放大电路中，若测得某NPN 型三极管的三个引脚的电位分别为9V , 2.5V , 3.2V , 则这三个极分别为 ④二、判断题(每题2分，共8分，对应题号答案请写在答题纸上，打√或×)5. 三相异步电动机的磁场是静止的（⑤）6. 正常运行中的单相电力变压器，输入电压不变输出功率增加时，铁芯内的磁通量不会发生明显变化（⑥ ）7. 阻容性负载的交流电路中，电流的相位滞后于电压（⑦） 8. 异步电动机内同步磁场的转速与电机的极对数无关（⑧）三、计算(每题12分，共96分)9. 放大电路的空载电压放大倍数A 100O =，输入电阻i 9r K =Ω，输出电阻O 1r K =Ω，试问：（1）输入端接到S U 10mV =，1S R K =Ω的信号源上，开路电压OC U 应等于多少？（2）输出端再接上9L R K =Ω的负载电阻时，负载上的电压OL U 应等于多少？这时的电压放大倍数u A 是多少？10. 如图所示电路中，已知V U S 121=，V U S 122=，Ω=11R ，Ω=22R ，Ω=23R ，Ω=44R ，求各支路电流。
11. 如图所示的交流电路中，已知1Ω2Ω，L Ω，X C =124Ω，试求：(1)并联等效阻抗Ｚ，(2)电路总电流I ，(3)支路电流1I 和2I12. 用叠加定理求图中的电流I 。
13. 下图是两级集成运算放大器组成的电路。
（1）按图中参数求u o。
（2）图中R7和R8换作20KΩ，求u o。
uu14. 下图所示的分压式偏置放大电路中，已知U CC = 12V, R C = 2KΩ，R E = 2KΩ，R B1 = 20KΩ，R B2 =10KΩ，R L = 6KΩ，晶体管的 =37.5。
2007年考研试题及答案A
一、填空题（30分）：1. （6分）由晶闸管构成的三相半波可控整流电路，当输入交流电压为t u ωsin 3112=，纯阻性负载且其值为10R =Ω，当控制角45α=时，输出平均电压为 ，输出的功率因数是 。
2．（6分）由晶闸管构成的单相桥式全控整流电路，当输入交流电压为t u ωsin 1412=，负载为反电动势且直流侧串联平波电抗器，已知60V, L=2E R =∞=Ω，，当控制角30α=时，输出平均电压为 ，输出平均电流为 。
3．（3分）缓冲电路( Snubber Circuit ) 的作用是 。
4．（3分）在交流供电系统中，当基波电流为140A I =，各次谐波电流分别为35792A, 1A, 0.5A, 0.2A I I I I ====, 则电流谐波总畸变THD 为 。
5．（3分）在逆变电路中，对于同一桥臂的开关管要采取“先断后通”的方法，也就是死区时间的设定，其目的是 。
6．（6分）单相桥式电压型逆变电路，180导通角，d 560V U =，则输出电压的基波有效值是 ，当只考虑10次以内的谐波电压时，输出电压的有效值是 。
7．（3分）在SPWM （Sinusoidal Pulse Width Modulation ）控制的三相逆变电路中，设定的开关管的开关频率是20KHz ，逆变电路输出交流电压的频率为400Hz ，那么SPWM 控制电路中载波频率和调制波频率应分别设置为 和 。
二、简答题（60分）：1． （7分）IGBT 在过流及短路过程中，系统如何检测并实施保护的？2． （7分）为什么晶闸管的触发信号通常不使用直流信号？ 3． （7分）试说明有关晶闸管和电力晶体管的关断过程？4． （7分）请叙述电力二极管的反向恢复过程，在高频开关电路中，应选择什么型号的二极管？5． （8分）利用晶闸管SCR 构成的简易照明延时开关电路如图1所示，HL 是灯泡，SB 是开关，试分析此电路的工作原理。
山东科技大学电路真题2009
一、单项选择题（本大题共20个小题，每小题都是4分，共计80分），下列各题中，每小题四个答案，将其中唯一的正确答案写到答题纸上，不要写在试卷上。
1. 图示电路中，7 V电压源吸收功率为（答案必须写到答题纸上）A. 14B. -7 WC. -14 WD. 7 W2. 图示电路中，若使I增加为2I，8Ω电阻应换为（答案必须写到答题纸上）A. 0 ΩB. 3 ΩC. 2 ΩD. 1 Ω3. 图示电路中N为线性含源网络，当U S=10V时，测得I=2A；U S=20V 时，测得I=6A；则当U=-20V时，I应为（答案必须写到答题纸上）SA. -6 AB. -10 AC. 8 AD. -8 A4. RC 充电电路如图示，电流源S ()i t I =，0t ≥，电容电压由零到达某一电压U 所需的时间为（答案必须写到答题纸上）A. ln(1)URC RI -B. ln(1)U RC RI-- C. RCD. ln RC U5. 若冲激电压()()V u t t δ=，则该冲激电压的强度为 （答案必须写到答题纸上）A. 1 VB. ∞C. 1 GD. 1 Wb6. 若一阶电路的时间常数为2s ，则零输入响应每经过2s 将衰减为原来值的（答案必须写到答题纸上）A. 50%B. 36.8%C. 25%D. 13.5%7．二阶电路电流i 的微分方程为22d 0d ii t+=，则电流i 随时间t 变化的形式可表示为（答案必须写到答题纸上）A. cos()A t ψ+B. cos 3A tC. cos A tD. 12cos3sin3A t A t +8． 如图示正弦RC 串联电路中，电压C u 与电流i 的相位关系为 （答案必须写到答题纸上）A. i 超前C u 角90°B. i 滞后C u 角90°C. i 超前C u 某一小于90°的角度D. i 滞后C u 某一小于90°的角度9.已知图示正弦电压u t ω=V，1u t ω=V ，则图中电压表的读数应等于（答案必须写到答题纸上） A. 1V B. 7V C. 5VB8-610. 如图示正弦交流电路，角频率1rad/s ω=时，(复)阻抗Z 为 （答案必须写到答题纸上）A. (2j2)+ΩB. (2j2)-ΩC.45Ω°D.45-Ω°11. 如图示无源二端网络N 的平均功率20P =W ，功率因数cos 0.8λϕ==(滞后)，则其无功功率Q 等于（答案必须写到答题纸上） A. 12varB. 12-varC. 15varD. 15-var12. 某负载所取的功率为72kW ，功率因数为0.75(电感性，滞后)，则其视在功率为（答案必须写到答题纸上）A. 72kVB. 4kVAC. 96kVAD. 81.6kVA13. RLC 串联谐振电路的电感增至原来的4倍时，谐振频率应为原来的 （答案必须写到答题纸上）A. 4倍B. 2倍C.12倍 D.14倍 14. 若20∶1理想降压变压器的次级线圈中0.6Ω电阻的电压为6V ，则该变压器的次级电流和初级电流为（答案必须写到答题纸上） A. 10A ，5AB. 5A ，10AC. 10A ，0.5AD. 0.5A ，10A15. 正弦稳态电路如图示，电源()u t 1的角频率10rad/s ω=，要使正弦电压u 2为最大，则电容C 应为（答案必须写到答题纸上） A. 0.01 F B. 2 F C. 0.005 FD. ∞16. 在图中，若已知某对称三相电路线电压AC173.230U =∠- °V ，线电流B2150I=∠- °A ，则该电路的三相功率P 等于（答案必须写到答题纸上） A. 0 B. 300W C. 433W D. 520WB11-417. 对称三相电源的A 相电压u t t A sin sin3=+()22021102ωωV ，星形联结时线电压的有效值为（答案必须写到答题纸上）A. 380VB. 426VC. 220VD. 245V18. 若i =12i i +，且i t 110=sin ωA ，210i =()sin 290t ω+°A ，则i 的有效值为（答案必须写到答题纸上）A. 20AB. 202AC. 10AD.19. 如图示正弦全波整流波形i 的有效值为10A ，半波整流波形i 1的有效值为（答案必须写到答题纸上）A. 102AB.AC. AD. 104A20. 如图示三相电路，已知三相电源对称，三个线电流有效值均相等I A =I B =I C =10A ，则中线电流有效值I N 等于（答案必须写到答题纸上） A. 10A B. 0 C. 14.14A D. 7.32A二、(15分) 试求图示电路中的电流I 。
2007年硕士生入学考试专业课试题下载英语
2007年硕士生入学考试专业课试题下载英语科目代码：211 请在答题纸（本）上做题，在此试卷可草稿纸上做题无效！山东科技大学2007年招收硕士学位研究生入学考试英语（单）试卷Part 1 Reading Comprehension (40%)Questions 1 to 5 are baded on the following passage.The common cold is the world?s most widespread illness, which probably why there are more myths a-bout it than any of the other plagues that flesh is heir to.The most widespread fallacy(谬误)of all is that colds are caused by cold. They are not. They are caused by viruses passage on from person to person. Y ou catch a cold by coming into contact, directly or indirectly, with someone who already has one. If cold causes colds, it would be reasonable to expect the Eskimos to suffer from them permanently. But they do not. And in isolated arctic regions explorers have reported being free from colds until coming into contact again with infected people from the outside world by way of packages and mail dropped from airplanes.During the First World War soldiers who spent long periods in the trenches(战壕),cold and wet, showed no increased tendency to catch colds.In the Second War prisoners at the notorious Auschwitxz concntration camp, naked and starving, were astonished to find that they seldom had colds.At the Common Cold Research Unit in England, volunteers took part in Experiments in which they submit-ted to the discomforts of being cold and wet for long stretches of time. After taking hot baths, they put on bath-ing suits, allowedthemselves to be wet with cold water, and then stood about dripping wet in drafty room. Some wore wet socks all day while others excised in the rain until close to exhaustion. Not one of the volunteers came down with a cold unless a cold virus was actually dropped in his nose.If, then, cold and wet have nothing to do with catching colds, why are they more prevalent in the winter? Despite the most pains-taking research, no one has yet found the answer. One explanation offered by scientists is that people tend to stay togeher indoors more in cold weather than at other times, and this makes it easier for cold viruses to be passed on.No one yet found a cure for the cold. There are drugs and pain suppressors(止痛片)such as aspirin, but all they do is relieve the symptoms.1. According to the passage, there are more myths about the common cold than any other human disease because .(A)it spreads very quickly(B)it is the most widespread illness(C)the climate of the world is getting colder and colder(D)few people can catch colds2. We learn from the passage that .(A) the Eskimos do not suffer from colds at all(B) colds are caused by cod(c) people suffer from colds just because they like to stay indoors(D) a person may catch a cold by touching someone who already has one3. Artic explorers may catch colds when .(A) they are working in he isolated arctic regions(B) they are writing reports in terribly cold weather(C) they are free from work in the isolated arctic regions(D) they are coming into contact with the outside world4. During the First World War, soldiers who spent long periods in cold and wet trenches .(A) often caught colds(B) never caught colds(C) did not show increased tendency to catch colds(D) seldom caught colds5. What does the passage mainly discuss?(A) The experiments on the common cold.(B) The myths about the common cold.(C) An explanation of the reason and the way people catch colds.(D) The continued spread of common colds.Questious 6 to 10 are based on the following passage.Much attention is presently being given to what is termed “fouctional illteracy”, this should not be con-fused with the problem of illiteracy, that is, the inability to read and write. Current United Nations Education, Scientific and Cultural Organization (UNESCO) figures indicate that 99 percent of all Americans are literate, the same figure asigned to nations such as Britain, Germany. Functional illiteeacy, by contrast, is concemed with how much difficulty people have in actually using and writing skills in everyday situations. This might be interpreted, for example, as the relative ablity to understand federal income tax forms, or printed instructions, or how well someone can write a letter of complaint, or apply for a joy in writing.There are no agreed-upon definitions of what functional illiteracy is and, in practice, definitions vary wide-ly. For manyyears, reading tests have been used throughout the country which define reading ability by grade level. “Tenth-grade reading level”, for instance, would be the average reading score of all pupils who have completed ten years of school. There are, of course, many different reading tests. One defini-tion of functional illitracy holds that anyone is “illitterate”who reads at less than an eighth-grade level. Another common definition uses a twelfth-grade level(the last year of high school in the U.S.).There seems to be general agreement that at least one-tenth of all Americans are fouctionally illiterate in English to some degiee. It is also hardly surprising that those nations which (like the U.S.).There seems to be general agreement that at least one-tenth of all Americans are fouctionlly illiterate in English to some degree. It is also hardly surprising that those nations which (like the U.S.) have paid mast at-tention to this concept, and which have nation wide tesing, have found the greatest problems. As one educator humorously put it, “Reading tests cause illiteracy”. Canada, for example, which also has a large non-English speaking immigrant popultion, has recently found that manyof her citiziens, too, are functionally illierate. The attention given to this problem, therefore, therefore, reflects the fact that in North America schools as well as pupil sare continually tested.6. According to the passage, “fouctional illiteracy” is .(A) the ability to read and write(B) the inability to read and write(C) the relative ability to read and write in everyday situations(D) the inability to read and write in everyday situations7. What is the definition of fouctional illiteracy?(A) It refers to anyone who reads at less than eighth-grade level(B) It refers to anyone who reads at less than twelfth-grade level(C) It refers to anyone who reads at less than tenth-grde level(D) There is no clear definition8. It can be learned from the passage that .(A) Canada and the U.S. have fouctionally illiterate population because they hardly paid any attention to the problem(B) fouctional illiteracy may have been caused at least in part by unsuccessful design of reading tests(C) non-Enish speaking immigrant population constitute the majority of all the fouctionally illiterate(D) it is impractical to determine what fouctional illiteracy really is as different situations set different re-quirements9. It can be inferred frem the passage that .(A) over one-tenth of Americans population have difficulty in using and writing skills in everyday situations(B) in North America nation-wide tests are given to test pupils? fouctional iteracy(C) Canadians are generally at a higher lever of fouctional literacy than Americans are(D) teaching of English reading and writing has turned out toe a failure in Canada and the U.S10. This passage was written mainly to .(A) analyze different definitions of fouctional illiteracy(B) discuss the reasons for fouctional illiteracy(C) compare different ways to get rid of illiteracy(D) introduce the problem of functional illiteracyQuestions 11 to 15 are based on the following passage.Some people believe that international sport creates good will between the nations and that if countries play games together they will learn to live together. Others say that the opposite is true: that international contests encourage false national pride and lead to misunderstanding and hatred. There is probably some truth in both arguments, but I recent years the Olympic Games have done little to support the view that sports encourages international brotherhood. Not only was there the tragic (悲惨的) incident involving the murder of athletes, but the Games were also ruined by lesser incidents caused principally by minor national contests.One country received its second medals with vilible indignation(愤怒) after the hockey (曲棍球) final. There had been noisy scenes t the end of the hockey match. The losers objecting to the final decisions. They were convinced that one of their goals should not have been disallowed and that that their opponent?s victory was unfair. Their manager wa in a rage when he said, “This wasn?t hockey . Hockey and the International Hockey Federation are finished. ” The president of the Federtion said later that such behavior could result in the suspension(暂令停止参加) of the team for at least three years.The American basketball team announced that they would yield first place to Russia, after a disputable end to their contest. The game had ended I disorder. It was thought at first that the United States had won, by a single point, but it was announced that there were three seconds still to play. A Russian player thev thew the ball from one end of the court to the oth-er, and another player player popped it into the basket. It was the first time the USA had ener lost an Olympic basketball match. An appepl jurydebated the matter for four and a half hours before announcing that the result would atand. The American players then voted not to receive the sil-ver medals.Incidents of this kind will continue as long as sport is played competitively rather than for the love of the game. The suggestion that athletes shoould compete as individuals, or in non-national teams, might be too much to hope for. But in the present organization of the Olympics there is far too much that encourages aggressive patriotism.11. According the author, reent Olympic Games have .[A] created goodwill between the nations[B] bted only false national pride[C] barely showed any international friendship[D] led to more and more misunderstanding and hatred12. What did the manager mean by saying, “Hockey and the International Hockey Federation are finished”?[A] His team would no loger take part in international games[B] Hockey and the Federation are both ruined by the unfair decisions[C] There should by no more hockey mtches organized by the Federation[D] The Federation should be dissolved13. The basketbal example implied that[A] too much patriotism was displayed in the incident[B] the announcment to prolong the match wa wrwng[C] the appeal jury wa too hesitant in makig the decision[D] the American team was right in rejecting the silver medals14. The author gves the two examples in paragraphs 2 and 3 to show .[A] how false national pride led to undesirable incidents ininternational games[B] that sportsmen have been more obedient than they used to be[C] that competitiveness in the games discourages international friendship[D] that unfair decisions are common in Olmpic Games15. What conclusion can be drawn from the passage?[A] The organization of the Olympic Games must be improved[B] Athletes should compete as individuals in the Olympic Games[C] sport should be played competitively rather than for the love of the game[D] International contests are liable for misunderstanding between nations Questions 16 to 20 are based on the following passageNow the Bush team is pushing hard an idea which is inherited from the Clinton asininistra-tion and which, in some way, build on the debt-relief initiative. For the very poorest coun-tries, America strongly favors maving from loans to grants, though other industrial-country do-nors are still doubtful of the wissom of this. Giving grants, they argue, will cut future aid flows beaause some of the funding for loans on generous terms comes from money which has been repaid(归还) to donors.America takes the view that, since many developing-country loans will never be repaid, mainly because the recipients (接受者) cannot affford to make large payments to their creditors, it makes more sense to treat them as grants in the first place. The Bush administration has threatened to hold up the fouds used for this sort of aid, International Develop-ment Assistance (IDA), if itcannot persuade everyone else to come on boaed. All members talded about having made progress in this area, but it remains a stumbling block.Work is also under way in the IMF and the G7 to reform the international system. This now has two objectives. One is to make it harder for terrorist organizations to obtain funding by cracking down on money-laundering and increasing financial transparency. The other is to reduce the occurrence and severity of financial crises in emerging-market countries. On this American views seem to have prevailed. The G7 meeting on April 19th and 20 ended with an unexpected decision 'to proceed with an American plan to include collective action clauses in fu-ture loans taken out by emerging-market governments. The idea is that in the event of a delay of payment-such as that by Argentina last December-a government could negotiate with a “super-majority” of its creditors to restructure its debts, rather than, as now, have a small mi-nority of creditors a ble to weaken such attempts.This market-based approach is still controversial, and implementing it could be difficult given the previous reluctance of governments to include such calauses in loan contracts (lest they appear to be signaling a readiness to default(拖欠) even as they borrow). Work on IMF paans for more far-reacjomg reforms of supreme debt, on which the Bush team recently appeared to pour cold water, is to proceed at the same time. The two approaches, said the G7, are “com-plementary”.16. According to the passage, America favors moving from loans to grants on the purpose of .[A] making more meoney for the donors[B] relieving debt of the poorest countries[C] solving the problem of poverty completely[D] collecting more money for future aid to other countries17. It can be seen that the undertaking of moving from loans to grants .[A] makes no progress at all [B] makes progress smoothly[C] still face some difficulties [D] achieve its success in near future18. The purpose of the reform of the international financlal systemincludes .[A] relieving the debt of poor countries[B] establishing a global financial market[C] distributing mony more fairly in the world[D] preventing the possible financial crisis and terrorists to raise money through the system19. It can be inferred from para. 3 that present .[A] a country can never expect to reconstruct its debts[B] a country can reconstreuct its debt with the permission of IMF[C] a country in default canot reconstuct its debts without the permission of all of its creditors[D] a country in defanlt can reconstruct its debts by acquiring the permssion of most of its creditors20. The implementing of the market-based approach may get to be smoother if .[A] American does more to help the poor[B] the Bush team doesn?t pour cold water[C] the emerging-market countries try harder[D] the governments of creditors are always ready to restructure the debts of its debtorsPart ⅡCloze (10%)Directions: There are 20 blanks in the following passage. For each blank there are four choices marked [A],[B],[C] and [D] on the right side of the paper. Y ou should choose the ONE that best fits into the passage. Then mark the corresponding letter on Answer Sheet with a single line through the centre.Small business owners must accept the bur-dens of entrepreneurship(企业家的职责). Being in business for yourself 21 your full atten-tion. Y ou seldom leave the office or shop at 5 PM.22 do you leave job problems there. They follow you home as business homework. This means less time for your 23 life.The 24 you sought can put you on the 25 . Y ou don?t report to a boss. But you do try as had as possible to serve your. customer. They are your “26 ”. Y ou also have to com-pete with creditors, employees, suppliers, and tax collectors. In other words, you are never really 27 .Samll firms can seldom 28 to hire e-nough employees so that each can specialize. Y ou may have to prepare ads, 29 records, make sales calls, and collect bad debts. Y ou must be able to “wear many hats”. 30 all these tasks takes up lots of time. But you cannot 31 long-range planning. Y ou have to 32 goals and develop plans to meet them. Give too 33 time to management and your business will fail.The major cause of business 34 is poor management. Of every three business that start, two fail . nearly half fail in the first five years. A person with limited talents may be a- ble to hold a job in a large firm because others will pick up the slack(松懈，懈怠). When you are in business 35 yourself, there is no one to “carry you”.Even if your firm 36 , you may still have little money to spend .you may work hard for months and not take a penny out, except for the salary you pay yourself. The reason is you may have to 37 your profits in the firm for long-eterm growth.38 you may need to meet short-term 39 for cash. Y ou may not even be able to draw a salary until the firm becomes a truly going 40 .21. [A] conside [B] acquires [C] requires [D] inquires22. [A] Nor [B] Also [C] So [D] Either23. [A] institutional [B] personal [C] intimate [D] secret24. [A] prosperity [B] property [C] fortne [D] independence25. [A] spot [B] button [C] horizon [D] period26. [A] superior [B] manager [C] boss [D] director27. [A] lucky [B] free [C] relaxed [D] happy28. [A] afford [B] resort [C] grant [D] entitle29. [A] mange [B] break [C] keep [D] establish30. [A] Assuming [B] Marnaging [C] Regulating [D] Performing31. [A] deny [B] discard [C] refuse [D] ncglect32. [A] set [B] construct [C] make [D] create33. [A] few [B] reductron [C] failure [D] slight34. [A] depression [B] reductron [C] failure [D] lack35. [A] by [B] for [C] upon [D] from36. [A] booms [B] succeeds [C] fails [D] enlarges37. [A] reinvest [B] resolve [C] reserve [D] reproduce38. [A] But [B] And [C] While [D] Or39. [A] obligations [B] demands [C] requirements [D] necessaries40. [A] accomplishment [B] charity [C] concern [D] estatePart ⅢV ocabulary and Structure (15%)41. my great surprise, Idiscovered that the watch was broken.(A)To (B)For (C)On (D)With42. As far as the structure is concerned, the house isn?t the price they are ask.(A)worthy (B)worthy of (C)worthwhile (D)worth of43. It?ll be sure beat carrying a lot of water of to boil it at the campsite.(A)to have (B)have (C)having (D)had44.We all know that Mr.Wang is training his son .(A)in real earnest (B)on purpose (C)in an easygoing way(D)out of mind45. They visited many places their stay in shanghai.(A)in (B)for (C)during (D)on46. Astronomers believe that here are small, very cold lumps that stay poised in spacethe furthest planet.(A)beyond (B)before (C)behind (D)below47. I have so much work to do that a holiday for me this year is .(A)in question (B)out of question (C)out of the question (D)at random48. Students generally look their teachers.(A)up (B)up to (C)into (D)until49. The teacher won?t dismiss the class it is time.(A)for (B)if (C)so (D)until50. We countless enemy encirclements and blockades until we finally arrived at our destination.(A) broke through (B)broke with (C)broke into (D)broke in51. Sales of home computer have in recent years.(A)taken in (B)taken off (C)taken for (D)taken from52. Y ou may not believe it, but Einstein is said to have noaptitude language learning when he was young.(A)towards (B)of (C)for (D)with53. During the flood of 1927, the Red Cross out of emergency headquarters in Mississippi, set up temporary shelters for the homeless.(A)operates (B)is operating (C)has operated (D)operating54．As a masterpiece, a work of art must transcend the ideals of the period in which it was created.(A)Ranks (B)The ranking (C)To be randed (D)For being randed55.Of all the factors affecting agricultural yields, weather is the one the most.(A)it influences farmers (B)that influences farme rs(C)farmers that it influenes (D)why farmers influence it56. He was left alone, with to take care of him.(A)someone (B)no one (C)not one (D)anyone57. Bruce and John have arrived, but students in the class aren?t here yet.(A)other (B)the other (C)the others (D)others58. As the chairman will be hospitalized for quite a long time, some one should be appointed chairman.(A)alternative (B)temporary (C)substitute (D)secondary59. If, despite all this, we walk with of realizing our long-cherished dream of rebirth and reconstruction, it is because the conditions for doing so now exist.(A)convince (B)conviction (C)conflict (D)confirmation60. Despite all his efforts and merits, Mr.Smith is not a good teacher.(A)much of (B)adequate to (C)qualified (D)somewhat for61. offering good job prospects and easy living, Atlanta is acity where African Americans have had a chance to express their culture and flourish.(A)Beside (B)Besides (C)Except (D)Except for62. Altough the students dislike the material they are studying right now, their instructor has no to change the syllabus.(A)purpose (B)motivation (C)ambition (D)authority63. His efforts to improve the company have been very .(A)effective (B)efficient (C)efficacious (D)effetively64. looked more affluent, the price could have gone up to 400 rupees.(A)If had I (B)Had I (C)I had (D)I had been65. The travels of Marco Polo in the 12th century would not have been so well knownFor the book he wrote while in jail.(A)it not have been (B)is not been (C)had it ont been (D)has not been66. On entering te office, the teacher canght sight of the gift by his students.(A)was sent (B)being sent (C)sent (D)sending67. Our school singing group is going to give performance next month; don?t moss it.(A)an alive (B)a living (C)a live (D)a life68. The television with my concentration when I was writing.(A)distured (B)interfered (C)troubled (D)bothered69. Children?s clothes have to be strong to hard wear.(A)stand in for (B)stand in to (C)stand up for (D)stand up to70. So that nobody wants to swim in it.(A)the river is dirty (B)dirty is the river(C)is the river dirty (D)dirty the river isPart ⅣTranslation (20%)Professor Arthur Shimamura, of the University of California at Berkeley, says there are three main ways in which mental fouction changes.The forst is mental speed, for example how quickly ypu can react to fast moving incidents on the road. Drivers in their late teens react quickly but tend to drive too fast, while the over sixties are more cautious but rect more sloely. The near-inevitable slowing with age also partly explains why soccer players are seen as old in their thirties, while golf professionals are still in their prime at that age. This type of mental slowing results from a reduction in the efficiency with which the brain?s neurons work.The fact that asults find it harder to learn musical instruments than children points to a second type of mental loss with age – a reduction in learning capacity. The parts of the brain known as the temporal lobes control new learning, and are particulrly vulnerable to the effets of aging. This means that, as we get older, we take longer to learn a new language, are slower to master new routines and technologics at work, and we have to rely more on diaries and other mental ads.‘Working memory’is the third brain system which which is vulnerable to the effect of aging. Working memory is the brain?s …blackboard?, where we juggle from moment to moment the things we have to deep in mind when solving problems, planning tasks an generally organizing our day-to-day life. Absent-mindedness occurs at all ages because of imperaections in the working memory system –so, for instance, you may continually lose your glasses, or find yourself walking into a room of ypur house only to find that you cannot remember what you came for.Such absent-mindedness tends to creep up on us as we ageand occurs because our plans ansd intentions, which are chalked up on the ental blackboard, are easily wiped out by stray thoughts and other distractions. Stress and preoccupation can also cause such absent-mindedness, in addition to age-related changes in the brain. The frontal lobes of the brain –located behind the forehead and above the eyes –ate where the working memory system is located . Like the temporal lobes, which handle new learning, the frontal lobes are more vulnerable to the aging process than other parts of the brain.PartⅤWriting (15%)Directions: For this part, you are required to write a short essay Going Out to See the World. Y ou should write at least 150 words following the outline given below in Chinese:1. 旅行的好处2. 旅行的弊端3. 你的观点Going Out to See the W orld。
山东科技大学837电路2019年考研真题
）的三个电阻接为星型。
图7
A.
B.
C.
D.
6、有三个电阻阻值 R1﹥R2﹥R3,将它们接到电压为 U 的电源上，哪一说法是正确的：（⑥ ）
A.串联时 R3 上的
C.串联时 R2 获得的功率最大 D.并联时 R3 获得的功率最大
7、在图 8 所示正弦交流电路中，已知 I 10A，则图中 I R 为( ⑦ )
A. R 6 B. R C. R 2 D. R 3
图3
2、电路如图 4 所示，已知 US1= 8V，US2= 4V。若用图 5 所示的电路代替图 1 所示的电
路，该等效理想电压源的参数 US 为( ②
)。
A. 4 V
B. 12 V
2019 年山东科技大学 硕 士 研 究 生 入 学 考 试 专 业 课 真 题
一、填空题(每空 5 分,共计 35 分）请将答案写到答题纸上！
1、如图1所示电路中的电压源的电流i ___①____A，受控电流源两端的电压u _
②___V。
图1
图2
2、如图 2 所示电路中 AB 端口的输入电阻 R= _ ③ __Ω，AB 端口的电压 U = _④___V，
4、当 t=0 时,开关 S 由 1→2，求电感电压和电流。（14 分）
5、如图所示稳态电路中，已知 R =1 ，L
1= c
3
。求：AB 端的输入阻抗
ZAB(10 分)
6、已知电路
A
为线性无源电路。当
E 1
10V
, IS2
1A 时， U 3V ；当
E 1
5V ,IS 2
1A 时，U
若 AB 端接入一个可变电阻，则该电阻获得的最大功率 P= _⑤____W。
山东科技大学2005-2008年招收硕士学位研究生入学考试试题
科目代码：417 请在答题纸（本）上做题，在此试卷及草稿纸上做题无效！山东科技大学2005-2008年招收硕士学位研究生入学考试煤矿开采学试卷一、问答题（共7小题，每小题7 分，共49 分）1、简述阶段内的再划分方式，并说明各适用于何种条件？2、简述采煤方法的含义，并说明我国常用的采煤方法有那几种？3、简述区段无煤柱护巷的理论依据、无煤柱护巷的方法及适用条件。
4、试分析采用倾斜长壁采煤法时，仰斜、俯斜开采的工艺特点。
5、煤田划分为井田时，考虑哪些主要因素？6、简要分析急倾斜煤层开采有哪些主要特点？7、简述矿井服务年限与生产能力的关系，并说明为什么要考虑储量备用系数？二、论述题（共4 小题，每小题12 分，共48 分）1、分析综采放顶煤开采技术的优越性及存在的主要问题。
2、论述深矿井开采中的地压显现特征，并说明巷道地压控制的途径。
3、分析上、下山开采的基本特点及下山开采的适用条件。
4、试分析我国煤矿井田开拓的发展方向。
三、绘图题（共4 小题，53 分）1、绘图（用剖面图）说明机采工作面单体支架的两种布置方式及特点。
（12 分）2、绘图说明开采水平大巷布置方式有哪几种？分别说明其适用条件？（15 分）3、绘图说明近距离煤层群上、下工作面同采时的最小错距，并写出其计算公式。
（12 分）4、根据单一煤层走向长壁采煤法采区巷道布置平面图，绘出沿上山位置（1-1）的剖面图。
（14 分）科目代码：419 请在答题纸（本）上做题，在此试卷及草稿纸上做题无效！山东科技大学2006年招收硕士学位研究生入学考试煤矿开采学试卷一、问答题（共8 小题，每小题7 分，共56 分）1.简述阶段内的再划分方式有哪几种？，各适用于何种条件？2.长壁采煤法有哪几种主要采煤工艺？简述我国采煤工艺的发展过程。
3.何谓采煤方法？我国较广泛采用的采煤方法有哪几种？4.简要说明采区上、中、下部车场基本类型有那些？5.综采放顶煤长壁采煤法主要有哪几种类型及其适用条件？6.简述环行式井底车场的基本类型及其调车方式？7.井田开拓方式按开采准备方式如何分类？8.何谓矿井工业储量及矿井可采储量？如何用公式表示二者之间的关系？二、论述题（共4 小题，每小题12 分，共48 分）1.与走向长壁采煤法相比，倾斜长壁采煤法的特点及适用条件是什么？2. 试述采区上山的位置及其选择？采区上山布置的类型有那些？3. 试述如何确定合理的水平垂高？4.试述采用方案比较法确定矿井开采设计方案时，一般应比较的主要项目和内容以及方案比较法的步骤？三、绘图说明题（共4 小题，46 分）1.绘图说明适宜的沿空掘巷的巷道位置及掘进时机？（12分）2.绘图说明采区下部卧式底板绕道车场形式及其适用条件（10分）3.厚煤层分层开采时区段分层平巷的布置方式有哪些？绘图说明内错式布置方式及其适用条件？（10 分）4.绘图说明单一倾斜长壁采煤法仰斜开采巷道布置，并标出巷道名称及其主要生产系统？（14 分）一、简答题（共7小题，每小题8分，共56分）1、选择采煤方法的影响因素有哪些？2、选择开拓延深方案的原则和要求是什么？3、斜井开拓方式的井筒布置有几种？其适用条件如何？4、简述为什么确定矿井服务年限时要考虑储量备用系数？5、采区上山布置有哪些类型？采区参数主要包括哪些内容？6、矿井技术改造的目的是什么？技术改造的内容包括那几个方面？7、简述仰斜和俯斜开采的特点。
山东科技大学2011-2016年招收硕士学位研究生入学考试电路试卷
山东科技大学2011-2016年招收硕士学位研究生入学考试电路试卷山东科技大学2011年招收硕士学位研究生入学考试电路试卷山东科技大学2012年招收硕士学位研究生入学考试电路试卷一、单项选择题：(本大题共10小题，每小题4分，总计40分)在下列各题中，有四个备选答案，请将其中唯一正确的答案写到答题纸上，不要写在试卷上！1.图示二端电路中与理想电压源并联的电阻RA. 对端口电压有影响B. 对端口电流有影响C. 对端口电压与端口电流均有影响D. 对U支路的电流有影响S(答案必须写到答题纸上)2.图所示电路中0N 为无源线性电阻网络，当S U =0，S 4I =A 时，26U =V ；当S U =8 V 时，电流源S I 不吸收也不产生功率；则当S U = 12 V 时，电流源吸收的功率应为A. 16 WB. 14 WC. 12 WD. 10 W(答案必须写到答题纸上)3. 图示正弦交流电路，角频率1rad/s ω=时，(复)阻抗Z 为 A.(2j2)+ΩB.(2j2)-Ω45Ω°45-Ω°(答案必须写到答题纸上)4. 某负载所取的功率为72kW ，功率因数为0.75(电感性，滞后)，则其视在功率为 A.72kVB.81.6kVAC.96kVAD. 54kVA（答案必须写到答题纸上）5.RLC 串联谐振电路的电感增至原来的4倍时，谐振频率应为原来的A.12倍B.2倍C.4倍D.14倍 (答案必须写到答题纸上)6.若20∶1理想降压变压器的次级线圈中0.6Ω电阻的电压为6V ，则该变压器的次级电流和初级电流为 A. 10A ，5A B. 5A ，10A C. 10A ，0.5A D. 0.5A ，10A（答案必须写到答题纸上）7. 如图示正弦全波整流波形i 的有效值为10A ，半波整流波形i 1的有效值为A.102AC. A D. 104A(答案必须写到答题纸上)8．如图所示电路零输入响应的性质为 A. 过阻尼 B. 临界阻尼 C. 欠阻尼 D. 无阻尼(答案必须写到答题纸上)9.二端口网络Y 参数中，y 22是二端口的 A. 输出端导纳B. 输入端开路时的出端导纳 C. 输入端短路时的转移导纳D. 以上皆非(答案必须写到答题纸上)10．某电阻电路仅含一个独立电压源，其电压为S ()u t ，若已知其中某条支路的电流2S S ()0.5()0.2()i t u t u t ⎡⎤=+⎣⎦A ；则此电路属于A. 线性、时不变电路B. 非线性、时不变电路C. 线性、时变电路D. 非线性、时变电路(答案必须写到答题纸上)二、（20分）电路如图T2所示，试写出节点方程并求其节点电压及i 1、i 2。
山东科技大学数据结构与操作系统2007-2008,2010-2018年考研初试真题
《数据结构》部分
一、简答题（30分，每题5分）
1、串、数组、广义表从元素间关系上可以看成线性结构，它们与
一般意义上的线性表相比有何特殊性？
2、借助栈可以实现更复杂的操作，请简述如何利用栈实现对表达
式中括号是否匹配的检验。
3、基于关键字比较的查找算法所能达到最优时间复杂度是？能否
设计一种与问题规模无关的查找算法？请给出基本思路。
4、图的广度优先遍历与树的何种遍历策略相似？请给出简单解释。
5、《数据结构》中经常采用“树形化组织”的方式来整理数据，
比如折半查找表、二叉排序树、大顶堆/小顶堆等，请简述这样
做的优点。
6、何为稳定的排序方法？何为不稳定的排序方法？哪些排序算法
是不稳定的？
二、综合应用题（40分，每题10分）
1、假设用于通信的电文共有8个字母A,B,C,D,E,F,G,H组成，字
母在电文中出现的频率分别是{0.2，0.04，0.06，0.02，0.12，
0.24，0.25，0.07}。
①试为这8个字符设计哈夫曼编码；
②试设计另一种由二进制表示的等长编码方案；。
山东科技大学《电路（自动化）》历年考研真题汇编
目 录2011年山东科技大学《832电路（自动化）》考研真题2012年山东科技大学《845电路（自动化）》考研真题2014年山东科技大学《827电路（自动化）》考研真题2016年山东科技大学《827电路（自动化）》考研真题2017年山东科技大学《820电路（自动化）》考研真题2018年山东科技大学《820电路（自动化）》考研真题2019年山东科技大学《820电路（自动化）》考研真题2011年山东科技大学《832电路（自动化）》考研真题4.已知电路如图1-4所示，则该电路响应的性质为A.衰减振荡C.非振荡B.无阻尼的振荡D.临界的非振荡答（）写到答题纸上6<__20t h—L=JL f 图1-45,含理想变压器电路的相株模型如图I-5所示，打£应为A.I2ZCTVB.8N0°VC.4Z0°VD.G答（）写到答题纸上6.如图1-6所示为对称三相电路，电源线电压叫=3湘V,二角形联结负载其阻抗Z=（JK+j241£J,功率表采用如图接法，则此时功率表读数为A.1772W答（）写到答题纸上B.5I34W C.997W D.766SW7.值为如图1-7所示正弦全波整流波形j的有效值为EA,半波整流波形匕的有效A,贝A2B气A「号A DU 答（写到答顾纸上图1-7正弦电流通过电感元件时, A.U^L—d/C u=coLi 下列关系式中正确的是R;-VB.I=—j--coLD./=j mlXj答（写到答题纸上-r^-一的拉氏反变换式是妒十6$+8A.2曜—4L C,4广_您，B.2e^+4c-J, D.4c^+2c)答（写到答题纸上m若-•个二端口网络y参数方程为―仁堂二板'剧该二端口网络具有A.对称性和互易性C.互易性B.对称性D.不对称也不互易答（）写到答题纸上二、〔本大题20分）在图2所示电路中,已知&=死=1（）。
，/f=4Q，心=岳=8项, #6=2。
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07年
一、单项选择题：(本大题共12小题，每小题5分，总计60分)
在下列各题中，有四个备选答案，请将其中唯一正确的答案写到答题纸上，不要写在试卷上！
1、图示正弦交流电路中，负载L Z 获得最大功率时，L Z 应为
A. 5Ω
B.
()j35+Ω
C.
()j35-
Ω
D.
j3-Ω
答 ( )
L
S
U
2、若变压器的初级线圈和次级线圈的电感均为2H,线圈间的互感也为2H,则该变压器为
A. 为理想变压器
B. 线圈的匝数比为2
C. 为全耦合变压器
D. 以上三点全不正确 答( )
3、今有10μF 的电容元件，充电到100 V 后从电路中断开，经10 s 后电压下降到36.8 V ，则该电容元件的绝缘电阻为 A. 100k Ω B. 1M Ω C. 10M Ω D. 20M Ω 答（ ）
4、RLC 串联电路的R =4k Ω，L =4H ，C
=1μF。
该电路的暂态响应属于
A. 衰减振荡情况
B. 振荡情况
C. 临界情况
D. 非振荡情况 答( )
5、图示正弦交流电路中，若2
1
C L ωω>，且电流有效值A 41=I ，A 32=I ，
则I 等于
A. 7A
B. 5A
C 1A D.
2A
答 ( )
2
C
6、图示二端网络的电压电流关系为
A. U I =+25
B. U I =-25
C. U I =--25
D. U I =-+25 答( )
7、电路如图所示, 当t =0时开关断开, 已知()()i i 12000--==,则()i 20+等于
A.
L L L I 112
+S
B. 0
C.
L L L I 212
+S
D.
12
L I S
答(
)
2
8、图示电容元件的()u 00=，()i t =02. A ，则t 由0至50s 期间电容吸收能量为
A.50 J
B. 100 J
C. 250 J
D. 500 J
答(
)
02.
9、图示正弦RLC 并联电路,测得图中各电流有效值分别为I =5A, I R =4A,
I L =3A, 则i C 等于
A. 1A
B. 2A
C. 6A
D. 4A 答( )
C
+-
10、图示正弦交流电路中，已知︒∠=05S I A ，则电路复功率(功率复量)S ~
等
于
A. ()j3648-V A
B. ()j3648+V A
C. ()j4836-
V A
D.
()j4836+
V A
答 ( )
Ω
j3S
I
11、图示并联的有互感线圈的等效电感为
A. L 1+L 2+2M
B. L 1+L 2－2M
C.
L L M
L L M
122
122-+- D.
L L M
L L M
122
122-++
答( )
L 2
12、图示电路中i S =+
(2410cos t )A ，则10Ω电阻消耗的功率为
A. 20W
B. 160W
C. 80W
D. 200W 答( )
01.
F
二、非客观题( 本 大 题15分 ) 求图示电路中的i 1、i 2。
三、非客观题( 本 大 题10分 )
求图示电路中的电流I 。
四、非客观题( 本 大 题15分 )
图示对称三相电路中，已知电源线电压U l =380V ，R =40Ω，1
30ωC
=Ω
，
求三相负载功率P 。
C
A
B
1
ωC
五、非客观题( 本 大 题15分 )
图示R 、L 、C 串联谐振电路品质因数Q 0100=。
若接上电压为10 V 、内阻为1Ω的电源，则有载品质因数为多少？
R
1H
六、非客观题
( 本 大 题15分 )
求图示电路中的零状态响应i t C ()。
δ(t )A
t
七、非客观题( 本 大 题10分 )
试画出图示电路的网络函数
U s U s o S ()()。
1H
o
八、非客观题( 本 大 题10分 )
电路如图所示。
已知感性负载的等效阻抗Z L =3+j3.8Ω，由频率f=50Hz ，电压U S =220V 的正弦电源供电，电源的额定容量S N =10kV A 。
(1)求负载吸收的功率及功率因数。
(2)若在负载处用并联电容的方法将功率因数提高到0.9，求需并联的电容值。
⋅。