TE试题1

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本科光纤通信试题答案(卷一)

1) 为了得到较高的信噪比，对光接收机中的前置放大器的要求是______。

A. 高增益B. 低噪声C. 低增益、低噪声D. 高增益、低噪声2) 对于半导体激光器，当外加正向电流达到某一值时，输出光功率将急剧增加，这时输出的光为______，这个电流称为______电流。

A. 自发辐射光，阈值B. 自发辐射光，阀值C. 激光，阈值D. 激光，阀值3) SDH线路码型一律采用______。

A. HDB3码B. AIM码C. NRZ码D. NRZ码加扰码4) 在SiO2单模光纤中，材料色散与波导色散互相抵消，总色散等于零时的光波长是______。

A. 0.85 μmB. 1.05 μmC. 1.27 μmD. 1.31 μm5) 在阶跃型光纤中，导波的传输条件为______。

A. V＞0B. V＞VcC. V＞2.40483D. V＜Vc6) DFA光纤放大器作为光中继器使用时，其主要作用是______。

A. 使信号放大并再生B. 使信号再生C. 使信号放大D. 降低信号的噪声7) 目前，掺铒光纤放大器的小信号增益最高可达______。

A. 40 dB左右B. 30 dB左右C. 20 dB左右D. 10 dB左右8) 对于2.048 Mb/s的数字信号，1 UI的抖动对应的时间为______。

A. 488 nsB. 2048 nsC. 488 μsD. 2048 μs9) 通常,影响光接收机灵敏度的主要因素是______。

A. 光纤色散B. 噪声C. 光纤衰减D. 光缆线路长度10) 在薄膜波导中，导波的基模是______。

A. TE0B. TM0C. TE1D. TM12. 写出下列缩写的中文全称（共10分，每题1分）1)GVD (群速度色散)2)STS (同步转移信号)3)ISDN (综合业务数字网)4)AWG (阵列波导光栅)5)OC (光载波)6)WGA (波导光栅路由器)7)GIOF (渐变折射率分布)8)OTDM (光时分复用)9)SCM副载波调制（SCM，Subcarrier modulation）。

te软件工程模拟卷1

南京理工大学课程考试试卷(学生考试用)课程名称：软件工程基础(A)学分： 4 教学大纲编号：试卷编号：考试方式：闭卷满分分值：100 考试时间：120 分钟组卷日期：2010年12 月25 日组卷教师(签字)：叶庆生审定人(签字)：张宏学生班级：学生学号：学生姓名：11. 软件测试中常用的静态测试方法是（A）和（B）。

（B）用来检查模块或子程序间的调用是否正确。

分析方法（白盒方法）中常用的方法是（C）方法。

非分析方法（黑盒方法）中常用的方法是（D）方法和（E）方法。

（E）方法根据输出对输入的依赖关系设计测试用例。

供选择的答案：A、B：①引用分析②算法分析③可靠性分析④效率分析⑤接口分析⑥操作性分析C、D、E：①路径测试②等价类③因果图④归纳测试⑤综合测试⑥追踪⑦深度优先⑧排错⑨相对图二．填空（每空1分，共10分）1.结构化方法总的指导思想是________。

它的基本原则是功能的________与抽象。

2. 探索型类型的原型模型是把原型用于开发的________阶段，目的是要弄清________，确定所期望的特性，并探索各种方案的可行性。

3. 要把数据流图（DFD）转换成软件结构，首先必须研究DFD的类型。

各种软件系统，一般可分为________和________两类。

4. 技术可行性是对要开发项目的功能、________、________进行分析，确定在现有的资源条件下，技术风险有多大，项目是否能实现。

5. 对于软件的独立性的衡量，根据模块的外部特征和内部特征，提出了两个定性的度量标准，即：________和________。

三．解释名词（每小题2分，共10分）(1) 软件(2) 可行性分析(3) 信息隐藏(4) α测试和β测试(5) 测试和调试四．简要回答下列问题（每小题4分，20分）1. 软件工程是指什么？软件工程的性质是什么？2.试比较程序流程图与PAD图的特点。

3. 文档的作用是什么？4. 抛弃型原型模型开发和进化型原型模型开发有何区别？5. 试画出Jackson方法所用的结构图的三种基本结构。

微波技巧与天线试题1[最新]

1、TE 波和TM 波的最低次模分别为11TE 和 10TM （错）2、将0≠z E 而0=z H 的波称为TE 波（错）3、描述光纤传输特性主要是色散和损耗（对）4、辐射电阻越大，有效长度越短，天线的辐射能力越强（错）5、天线通信的最佳功率max 85.0f f opt = （对）6、智能天线技术使得空分多址（SDMA ）成为可能（对）7、若无耗线处于行波状态时，则终端反射系数为11=Γ，且0Z Z in =（错）8、相速度可以用来表示波能量的传输速度（错）9、多径效应造成了天线系统传输过程中信号的衰落（对）10、天线接收的功率可分为三个部分：接收天线的再辐射功率、负载吸收的功率和媒质的损耗功率。

（对）(a) 微波是介于超短波与红外线之间的波，频率范围从 300 MHz 到 3000 GHz 。

光波属于电磁波谱的可见光段，工作波长为纳米量级。

(b) 由于微波在电磁波谱中的特殊位置，所以具有以下特性似光性和似声性、穿透性、非电离性、信息性、宽频带特性、热效应特性、散射特性、抗低频干扰特性、视距传播性、分布参数的不确定性、电磁兼容和电磁环境污染等(c) 某矩形波导中的信号能够单模传输，那么它一般工作于 10TE 模式，截止波长为_2a _,其中a 为波导宽边尺寸。

如果转接成圆型波导馈入基站仍然为单模，那么它此时工作于11TE 模式。

圆柱波导传输场一般可采用分离变量法求解，由于匹配边界条件的缘故，如果支撑场解中的第一类贝塞尔函数带有求导符号，那么必定为TE 模，其余场分量利用支撑场和纵横关系求出。

(d) 圆型波导虽然损耗比矩形波导小，但是由于其中存在固有的极化简并等问题，一般不用于长距离传输系统。

对于腔式谐振器器件，由于损耗主要来源于腔体的金属壁和腔内填充的介质，所以采用开放式或半开放式谐振器有利于获得更小的损耗。

作为封闭谐振体的改进版，可以采用由两块平行金属板构成开式结构的法布里——珀罗谐振器，这种谐振器稳定工作的条件是120111d d R R ⎛⎫⎛⎫≤--≤ ⎪⎪⎝⎭⎝⎭。

2020年9月大学英语四级考试真题答案与解析(第1套)

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电机与拖动基础试题库及答案

《电机与拖动基础》试题库及答案第一部分直流电机一、填空题： 1、直流电动机的工作原理是把能转化为能。

直流发电机的工作原理是把能转化为能。

（直流电；机械；机械；直流电）2、直流发电机的工作原理用定则判断感应电动势的方向。

直流电动机的工作原理用定则判断电磁力的方向。

（右手；左手）3、并励直流发电机自励建压的条件是_______;_______;_______。

(主磁路存在剩磁；并联在电枢两端的励磁绕组极性要正确，使励磁电流产生的补充磁通方向与剩磁磁通方向相同；励磁回路的总电阻必须小于临界电阻)4、可用下列关系来判断直流电机的运行状态，当_______时为电动机状态，当_______时为发电机状态。

（E a 〈U ；E a 〉U ）5、直流发电机的绕组常用的有_______和_______两种形式。

（叠绕组；波绕组）6、直流发电机电磁转矩的方向和电枢旋转方向_______，直流电动机电磁转矩的方向和电枢旋转方向_______。

（相反；相同）7、电动势常数e C 与转矩常数T C 之间的关系为______。

（T C =9.55e C ）二、选择题1、电机的电流小于额定电流，称为（）运行。

（1）（1）欠载（2）过载（3）额定2、电机的电流大于额定电流，称为（）运行。

（2）（1）欠载（2）过载（3）额定3、某直流电机它的电枢与二个励磁绕组串联和并联，那么该电机为( )电机。

（3）（1）他励（2）并励（3）复励（4）串励 4、直流发电机主磁极磁通产生感应电动势存在于（）中。

（1）（1）电枢绕组；（2）励磁绕组；（3）电枢绕组和励磁绕组5、直流发电机电刷在几何中线上，如果磁路不饱和，这时电械反应是（）（3）（1）去磁；（2）助磁；（3）不去磁也不助磁。

三、计算题1、一台并励直流电动机,铭牌数据如下:P N =3.5kW ，U N =220V ，I N =20A ，n N =1000r/min,电枢电阻R a =1Ω，△U b =1V ，励磁回路电阻R 1=440Ω，空载实验：当U=220V,n=1000r/min 时，I 0=2A ，试计算当电枢电流I a =10A 时,电机的效率（不计杂散损耗）。

(完整版)射频试题(判断选择计算-含答案)

判断题：1、无耗传输线终端短路，当它的长度大于四分之一波长时，输入端的输入阻抗为容抗，将等效为一个电容。

2、无耗传输线上驻波比等于1时，则反射系数的模等于0。

3、阻抗圆图上，|Γ|=1的圆称为单位圆，在单位圆上，阻抗为纯电抗，驻波比等于无限大。

4、只要无耗传输终端接上一个任意的纯电阻，则入射波全部被吸收，没有反射，传输线工作在匹配状态。

5、在传输线上存在入射波和反射波，入射波和反射波合成驻波，驻波的最大点电压值与最小点上的电压值的比即为传输线上的驻波比。

6、导纳圆图由等反射系数圆、等电抗圆和等电阻圆组成，在一个等电抗圆上各点电抗值相同。

7、圆波导的截止波长与波导的截面半径及模式有关，对于TE11模，半径越大，截止波长越短。

8、矩形波导的工作模式是TE10模，当矩形波导传输TE10模时，波导波长（相波长）与波导截面尺寸有关，矩形波导截面的窄边尺寸越小，波导波长（相波长）越长。

9、在矩形谐振腔中，TE101模的谐振频率最小。

10、同轴线是TEM传输线，只能传输TEM波，不能传输TE或TM波。

11、矩形波导传输的TE10波，磁场垂直于宽边，而且在宽边的中间上磁场强度最大。

12、圆波导可能存在“模式简并”和“极化简并”两种简并现象。

13、矩形波导中所有的模式的波阻抗都等于377欧姆。

14、矩形谐振腔谐振频率和腔体的尺寸与振荡模式有关，一般来讲，给定一种振荡模式，腔体的尺寸越大，谐振频率就越高。

15、两段用导体封闭的同轴型谐振腔，当它谐振在TEM模时，其长度等于半波长的整数倍。

16、对称振子天线上的电流可近似看成是正弦分布，在天线的输入端电流最大。

17、对称振子天线既可以作发射天线，也可以作接收天线，当它作为发射天线时，它的工作带宽要比作为接收天线时大。

18、天线阵的方向性图相乘原理指出，对于由相同的天线单元组成的天线阵，天线阵的方向性图可由单元天线的方向性图与阵因子相乘得到。

19、螺旋天线的工作模式有法向模、轴向模和边射模三种，其中轴向模辐射垂直极化波。

2024年全国硕士研究生招生考试英语一真题考研英语一

2024年全国硕士研究生入学统一考试英语(一)试题Section I Use of EnglishDirections:Read the following text.Choose the best word(s) for each numbered blank and mark A,B,C or D on the ANSWER SHEET.(10 points)There's nothing more welcoming than a door opening for you. 1 the need to be touched to open or close, automatic doors are essential in 2disabled access to buildings and helping provide general3to commercial buildings.Self-sliding doors began to emerge as a commercial product in 1960 after being invented six years4by Americans Dee Horton and Lew Hewitl. They5as a novelty feature, but as their use has grown, their 6 have extended within our technologically advanced world.Particularly7in busy locations or during times of emergency, the doors8crowdmanagement by reducing the obstacles put in people's way.9 making access both in and out of buildings easier for people, the difference in the way many of these doors open helps reduce the total area10 by them. Automatic doors often open to the side, with the panels sliding across one another. Replacing swing doors, these 11 smaller buildings to maximise the usable space inside without having to12 the way for a large, sticking-out door. There are many different types of automatic door, with each13 specific signals to tell them when to open.14 these methods differ, the main15 remain the same.Each automatic door system 16 the light, sound weight or movement in their vicinity as a signal to open. Sensor types are chosen to 17 the different environments they are needed in.18,a busy street might not19 a motion-sensored door, as it would constantly be opening for passers-by. A pressure sensitive mat would be more20 to limit the surveyed area.1.[A]Through [B]Despite [C]Besides [D]Without2.[A]revealing [B]demanding [C]improving[D]tracing3.[A]experience [B]convenience[C]guidance [D]reference4.[A]previously[B]temporarily [C]successively [D]eventually5.[A]held on [B]started out[C]settled down [D]went by6.[A]relations [B]volumes [C]benefits[D]sources7.[A]useful[B]simple [C]flexible [D]stable8.[A]call for [B]yield to [C]insist on [D]act as9.[A]As well as[B]In terms of [C]Thanks to [D]Rather than10.[A]connected[B]shared [C]represented [D]occupied11.[A]allow[B]expect [C]require [D]direct12.[A]adopt [B]lead [C]clear[D]change13.[A]adapting te [B]deriving from [C]relying on[D]pointing at14.[A]Once [B]Since [C]Unless [D]Although15.[A]records [B]positions [C]principles[D]reasons16.[A]controls [B]analyses[C]produces [D]mixes17.[A]decorate [B]compare [C]protect [D]complement18.[A]In conclusion [B]By contrast [C]For example[D]Above all19.[A]identify [B]suit[C]secure [D]include20.[A]appropriate[B]obvious [C]impressive [D]delicateSection II Reading ComprehensionPart ADirections:Read the following four texts. Answer the questions below each text by choosing A,B,C or D. Mark your answers on the ANSWER SHEET.(40 points)Text 1Nearly 2000 years ago, as the Romans began to pull out of Scotland, they left behind a curious treasure:10 tons of nails, nearly a million of the things. The nail hoard was discovered in 1960 in a four-metre-deep pit covered by two metres of gravel.Why had the Romans bunied a million nails? The likely explanation is that the withdrawal was rushed, and they didn't want the local Caledonians getting their hands on 10 tons of weapon-grade iron. The Romans buried the nails so deep that they would not be discovered for almost two millennia.Later civilisations would value the skilled blacksmith's labour in a nail even more than the raw material. As Roma Agrawal explains in her new delightful book Nuts and Bolts, early 17th-century Virginians would sometimes bum down their homes if they were planning to relocate. This was an attempt to recover the valuable nails, which could be reused after sifting the ashes. The idea that one might bum down an entire house just to reclaim the nails underlines how scarce, costly and valuable the simple-seeming technology was.The price of nails fell by 90%between the late 1700s and mid-1900s,as economist Daniel Sichel points out in a research paper. According to Sichel, although the falling price of nails was driven partly by cheaper iron and cheaper energy, most of the credit goes to nail manufactures who simply found more efficient ways to turn steel into nails.Nails themselves have changed over the years, but Sichel studied them because they haven't changed much. Roman lamps and Roman chariots are very different from LED strips and sports cars,but Roman nails are still clearly nails. It would be absurd to try to track the changing price of sports cars since 1695,but to ask the same question of nails makes perfect sense.I make no apology for being obsessed by a particular feature of these objects: their price. I am an economist, after all. After writing two books about the history of inventions, one thing Ive leamt is that while it is the enchantingly sophisticated technologies that get all the hype, it's thecheap technologies that change the world.The Gutenberg printing press transformed civilisation not by changing the nature of writing but by changing its cost-and it would have achieved little without a parallel collapse in the price of surfaces to write on, thanks to an often-overlooked technology called paper. Solar panels had few niche uses until they became cheap; now they are transforming the global energy system.21.The Romans buried the nails probably for the sake of[A]saving them for future use[B]keeping them from rusting[C]letting them grow in value[D]hiding them from the locals22.The example of early 17th-century Virginians is used to[A]highlight the thriftiness of early American colonists[B]illustrate the high status of blacksmiths in that period[C]contrast the attitudes of different civilisations toward nails[D]show the preciousness of nail-making technology at that time23.What played the major role in lowering the price of nails after the late 1700s?[A]Increased productivity.[B]Wider use of new energies.[C]Fiercer market competition.[D]Reduced cost of raw materials.24.It can be leamed from Paragraph 5 that nails[A]have undergone many technological improvements[B]have remained basically the same since Roman times[C]are less studied than other everyday products[D]are one of the world's most significant inventions25.Which of the following best summarises the last two paragraphs?[A]Cheap technologies bring about revolutionary change.[B]Technological innovation is integral to economic success.[C]Technology defines people's understanding of the world.[D]Sophisticated technologies develop from small inventions.Text 2Parenting tips obtained from hunter-gatherers in Africa may be the key to bringing up more contented children, researchers have suggested. The idea is based on studies of communities such as the Kung of Botswana, where each child is cared for by many adults. Kung children as young as four will help to look after younger ones and baby-wearing", in which infants are carried in slings, is considered the norm.According to Dr Nikhil Chaudhary, an evolutionary anthropologist at Cambridge University, these practices, Known as all oparenting, could lead to less anxiety for children and parents.Dr Annie Swanepoel, a child psychiatrist, believes that there are ways to incorporate them into western life. In Germany, one scheme has paired an old people's home with a nursery. The residents help to look after the children, an arrangement akin to alloparenting. Another measure could be encouraging friendships between children indifferent school years to miror the unsupervised mixed-age playgroups in hunter-gatherer communities.In a paper published in the Journal of Child Psychology and Psychiatry, researchers said that the western nuclear family was a recent invention which family broke with evolutionary history. This abrupt shift to an "intensive mothering narrative", which suggests that mothers should manage childcare alone, was likely to have been harmful. "Such narratives can lead to maternal exhaustion and have dangerous consequences, "they wrote.By contrast, in hunter-gatherer societies adults other than the parents can provide almost half of a child's care. One previous study looked at the Efe people of the Democratic Republic of Congo. It found that infants had an average of 14 alloparents a day by the time they were 18 weeks old and were passed between caregivers eight times an hour.Chaudhary said that parents now had less childcare support from family and social networks than during most of humans'evolutionary history,but introducing additional caregivers could reduce stress and maternal depression,which could have a“knock-on"benefit to a child's wellbeing.An infant bom to a hunter-gatherer society could have more than ten caregivers-this contrasts starkly to nursery settings in the UK where regulations call for a ratio of one carer to four children aged two to three.While hunter-gatherer children leamt from observation and imitation in mixed-age playgroups,researchers said that western"instructive teaching",where pupils are asked to sit still,may contribute to conditions such as attention deficit hyperactivity disorder.Chaudhary said that Britain should explore the possibility that older siblings helping their parents“might also enhance their own social development”26.According to the first two paragraph,alloparenting refers to the practice of[A]sharing child care among community members[B]assigning babies to specific adult caregivers[C]teaching parenting details to older children[D]carrying infants around by their parent27.The scheme in Germany is mentioned to illustrate[A]an attempt to facilitate intergenerational communication[B]an approach to integrating alloparenting into western culture[C]the conventional parenting style in western culture[D]the differences between western African ways ofliving28.According to Paragraph 4,the"intensive mothering narrative"_[A]alleviate parenting pressure[B]considerate family relationships[C]results in the child-centered family[D]departs from the course of evolution29.According to paragraph 6,what can we lean about nursery in the UK?[A]They tend to fall short of official requirements.[B]They have difficulty finding enough caregivers.[C]They ought to improve their carer-to-child ratio.[D]They should try to prevent parental depression.30.Which of the following would be the best title?[A]Instructive teaching:a dilemma for anxious parents[B]For a happier family,learn from the hunter-gatherers[C]Mix-aged playgroup,a better choice for lonely children[D]Tracing the history of parenting:from Africa to EuropeText 3Rutkowski is a Polish digital artist who uses classical painting styles to create dreamy fantasy landscapes.He has made illustrations for games such as Sony's Horizon Forbidden West,Ubisoft's Anno,Dungeons&Dragons,and Magic:The Gathering.And he's become a sudden hit in the new world of text-to-image AI generation.His distinctive style is now one of the most commonly used prompts in the new open-source AI art generator Stable Diffusion,which was launched late last month.The tool,along with other popular image-generation AI models,allows anyone to create impressive images based on text prompts.For example,type in"Wizard with sword and a glowing orb of magic fire fights a fierce dragon GregRutkowski,"and the system will produce something that looks not a milion miles away from works in Rutkowski's style.But these open-source programs are built by scraping images from the Internet,often without permission and proper attribution to artists.As a result,they are raising tricky questions about ethics and copyright.And artists like Rutkowski have had enough.According to the website Lexica,which tracks over 10 million images and prompts generated by Stable Diffusion,Rutkowski's name has been used as a prompt around 93,000 times.Some of the world's most famous artists,such as Michelangelo,Pablo Picasso,and Leonardo da Vinci,brought up around 2,000 prompts each or less.Rutkowski's name also features as a prompt thousands of times in the Discord of another text-to-image generator,Midjourney.Rutkowski was initially surprised but thought it might be a good way to reach new audiences.Then he tried searching for his name to see if a piece he had worked on had been published.The online search brought back work that had his name attached to it but wasn't his.“It's been just a month.What about in a year?I probably won't be able to find my work out there because[the internet]will be flooded with AI art,"Rutkowski says."That's concerning."“There is a coalition growing within artist industries to figure out how to tackle or mitigate this,"says Ortiz.The group is in its early days of mobilization,which could involve pushing for new policies or regulation.One suggestion is that AI models could be trained on images in the public domain,and AI companies could forge partnerships with museums and artists,Ortiz says.31.What can be leamed about Rutkowski from the first two paragraphs?[A]He is enthusiastic about AI generation painting.[B]He is popular with the users of an Al art generator.[C]He attracts admiration from other illustrators.[D]He specializes in classical painting digitalization.32.The problem with open-source AI art generators is that they[A]lack flexibility in responding to prompts[B]produce artworks in unpredictable styles[C]make unauthorized use of online images[D]collect user information without consent33.After searching online,Rutkowski found[A]a unique way to reach audiences[B]a new method to identify Al images[C]AI-generated work bearing his name[D]heated disputes regarding his copyright34.According to Ortiz,AI companies are advised to[A]campaign for new policies or regulations[B]offer their services to public institutions[C]strengthen their relationships with AI users[D]adopt a different strategy for Al model training35.What is the text mainly about?[A]Artists'responses to Al art generation.[B]AI's expanded role in artistic creation.[C]Privacy issues in the application of Al.[D]Opposing views on AI development.Text 4The miracle of the Chesapeake Bay lies not in its depths,but in the complexity of its natural construction,the interaction of fresh and saline water and the mix of land and water.The shallows provide homes for hundreds of species while storing floodwaters,filtering pollutants from water,and protecting nearby communities from potentially destructive storm surges.All this was put at great risk late last month,when the US Supreme Court issued a ruling in an Idaho case that provides the EPA far less authority to regulate wetlands and waterways.Specifically,a 5-4 majority decided that wetlands protected by the EPA under it Clean Water Act authority must have a“continuous surface connection”to bodies of water.This narrowing of the regulatory scope was a victory for builders,mining operators and other commercial interests often at odds with environmental rules.And it carries"significant repercussions for water quality and flood control throughout the US,"as Justice Brett Kavanaugh observed.In Maryland,the good news is that there are many state laws in place that provide wetlands protections.But that's a very shortsighted view,particularly when it comes to the Chesapeake Bay.The reality is that water and the pollutants that so often come with it,don't respect state boundaries.The Chesapeake draws from a 64000-square-mile watershed that extends to Virginia,Pennsylvania,New York,West Virginia,the District of Columbia and Delaware.Will thosejurisdictions extend the same protections now denied under Sackett V.EPA?Perhaps some,but all?That seems unlikely.It is too easy,and misleading,to see such court rulings as merely standing up for the rights of land owners when the consequences can be so dire for their neighbors.And it's reminder that they EPA's involvement in the Chesapeake Bay program has long been crucial as the means to transcend the influence of deep-pocketed special interests in neighboring states.Pennsylvania farmers,to use one telling example,aren't thinking about next year's blue crab harvest in Maryland when they decide whether to spread animal waste on their fields,yet the runoff into nearby creeks can have enormous impacts downstream.And so we would also call on state lawmakers from Richmond to Albany to consider reviewing their own wetlands protections and see for themselves the enormous stakes involved.We can't offer them a trip to the Chesapeake Bay model.It's been gone since the 1980s but perhaps a visit to Blackwater National Wildlife Refuge in Dorchester County where American bald eagles fly over tidal marshes so shallow you could not paddle a boat across them but teaming with aquatic life.It's worth the scenic drive.36.The Chesapeake Bay is described in Paragraph 1 as[A]a value natural environment[B]a controversial conservation area[C]a place with commercial potential[D]a headache for nearby communities37.The U.S.Supreme Court's ruling in the Idaho case[A]reinforces water pollution control[B]weakens the EPA's regulatory power[C]will end conflicts among local residents[D]may face opposition from mining operators38.How does the author feel about the future of the Chesapeake Bay?[A]Worried.[B]Puzzled.[C]Relieved[D]Encouraged.39.What can be inferred about the EPA's involvement in the Chesapeake BayProgram?[A]It has restored the balance among neighboring jurisdictions.[B]It has triggered a radical reform in commercial fisheries.[C]It has set a fine example of respecting state authorities.[D]It has ensured the coordination of protection efforts.40.The author holds that the state lawmakers should[A]be cautious about the influence of landowners[B]attach due importance to wetlands protections[C]recognize the need to expand wildlife refugesPart BDirections:Read the following comments on a report about American museums returning artifacts to their countries of origin and a list of statements summarizing the comments.Choose the best statement from the list A-G for each numbered name(41—45).There are two extra choices which you do not need to use.Mark your answers on the ANSWER SHEET.(10 points)(41)HannabSimply,there are people in Nigeria who cannot travel to the Smithsonian Institution to see that part of their history and culture represented by the Benin Bronzes.These should be available to them as part of their cultural heritage and history and as a source of national pride.There is no good reason that these artifacts should be beyond the ordinary reach of the educational objectives or inspiration of the generations to which they were left.They serve no purpose in a museum in the United States or elsewhere except as curious objects.They cannot be compared to works of art produced for sale which can be passed from hand to hand and place to place by purchase.(42)BuckWe know very exact reproductions of artwork can be and are regularly produced.Perhaps museums and governments might explore some role for the use of nearly exact reproductions as a means of resolving issues relating to returning works of art and antiquities.The context of any exhibit is more important to me than whether the object being displayed is 2,000 years old or 2 months old.In many cases the experts have a hard time agreeing on what is the real object and what is a forgery.Again,the story an exhibit is trying to tell is what matters.The monetary value of the objects on display is a distant second place in importance.(43)SaraWhen visiting the Baltimore Museum of Art,I came across a magnificentlSth-century Chinese sculpture.It inspired me to learm more about the culture that it represented.Artifacts in museums have the power to inspire,and perhaps spark that need to learn and understand the nature of their creators.Having said that,I do feel that whatever artifacts find their way to public museums should,in fact,be sanctioned as having been obtained on loan,legally purchased,or obtained by treaty.Stealing artifacts from other peoples'cultures is obscene;it robs not only the physical objects,but the dignity and spirit of their creators.(44)VictorAncient art that is displaced in foreign countries should be returned.…(缺失)(45)JuliaTo those of you in the comments section,by all means,who are having strong feeling about artifacts being removed from cities in the US and Britain,I would ask you to consider…(缺失)[A]It is clear that countries of origin have never been compensated for stolen artifacts.[B]It is a flawed line of reasoning to argue against returning artifacts to their countries of origin.[C]Museum visitor can still learn as much from artifacts copies after the originals are returmed.[D]Reproductions,even if perfectly made,cannot take the place of the authentic objects.[E]The real value of artifacts can only be recognized in their countries of origin rather than anywhere else[F]Ways to get artifacts from other countries must be decent and lawful.[G]Concern over security is no excuse for refusing to return artifacts to their countries of origin. 参考答案：41.E 42.C 43.F 44.G 45.BPart CDirections:Read the following text carefully and then translate the underlined segments into Chinese.Your translation should be written clearly on the ANSWER SHEET.(10 points)“Elephants never forget”—or so they say—and that piece of folklore seems to have some foundation.The African savanna elephant also known as the African bush elephant,is distributed across 37 African countries.(46)They sometimes travel more than sixty miles to find food or water,anc are very good at working out where other elephants are—even when they are out of ing tracking devices,researchers have shown that they have"remarkable spatial acuity",when finding their way to waterholes,they headed off in exactly the right direction,on one occasion from a distance of roughly thirty miles.What is more,they almost always seem to choose the nearest water hole.(47)The researchers are convinced that the elephants always know precisely where they are in relation to all the resources they need,and can therefore take shortcuts,as well as following familiar routes.Although the cues used by African elephants for long-distance navigation are not yet understood,smell may well play a part.Elephants are very choosy eaters,but until recently litle was known about how they selected their food.(48)One possibility was that they merely used their eyes and tried out the plants they found,but that would probably result in a lot of wasted time and energy,not least because their eyesight is actually not very good.(49)The volatile chemicals produced by plants can be carried a long way,and they are very characteristic:Each plant or tree has its own particular odor signature.What is more,they can be detected even when they are not actually visible.New research suggests that smell is a crucial factor in guiding elephants—and probably other herbivores—to the best food resources.The researchers first established what kinds of plant the elephants preferred either to eat or avoid when foraging freely.They then set up a“food station”experiment,in which they gave elephants a series of choices based only on smell.(50)The experiment showed that elephants may well use smell to identify patches of trees that are good to eat,and secondly to assess the quality ofthe trees within each patch.Free-ranging elephants presumably also use this information to locate their preferred food.参考译文：(46)它们有时跋涉六十多英里寻找食物或水，并且非常善于寻找其他大象的位置——即使它们不在视线范围内。

1第一部分电喷发动机试题答案

汽车维修工技能考核试题第一部分电喷发动机维修试题集一、填空题1、对丰田系列有分电器式电子点火发动机，在调整基本点火提前角时必须跨接诊断座中的_TE1_和__E1__两接脚。

2、柴油机排气中最主要的有害成分是__炭烟__。

3、EGR（废气再循环）装置的主要作用是减少__NOx__的排放量。

4、NO X的产生机理主要是__高温__和__富氧___两个条件。

5、三元催化转换器只能在空燃比为__14.7:1__附近较狭小的范围内起作用。

6、翼片式空气流量计中有一__燃油泵____触点，当发动机停转时该触点__断开_。

7、曲轴位置传感器输出的Ne信号的作用是_反映曲轴转速__，G信号的作用是__判别缸位__。

8、氧传感器的输出信号随排气中的__氧__的含量而变化，当混合气的空燃比大于14.7时，它输出近__0__V的电压信号；当混合气的空燃比小于14.7时，它输出近__1__V 的电压信号。

9、发动机转速越高则所需的点火提前角__越大__；发动机的负荷越大则所需的点火提前角__越小___。

10、过稀的混合气可能使点火电压__高于__正常值。

11、对于具有可变进气通道控制的发动机，低速时使进气通道_细__而__长_；高速时使进气通道__短__而__粗__。

12、混合气过浓或过稀都会使废气中的__HC___含量增高。

13、空气流量计根据测量原理的不同可以分为：__翼片式_____、_热线式____、___热膜式___、__卡门涡旋式____等四种。

14、发动机对外无功率输出的情况下稳定的运转状态称为__怠速___工况。

15、汽油机对点火系统的三个基本要求分别是：_足够的电压__、_足够的能量__、__点火正时_。

16、点火线圈实质上是一个脉冲变压器，常见的有_开磁路式__和__闭磁路式_两种形式。

17、汽油机喷油嘴按电磁线圈的控制方式不同可分为_电压__驱动式和_电流__驱动式两种。

18、霍尔效应传感器输出数字电压信号，当金属片进入磁隙中时，其输出的电压信号从__0V__变为_12V__；而当金属片离开磁隙时，输出电压信号从__12V_变为__0V__。

微波试题 (1)

微波技术基础一、填空题（40分，每空2分）1、传输线的工作状态是指沿线电压、电流及阻抗的分布规律。

对于均匀无耗传输线，根据终端所接负载阻抗的大小和性质的不同其工作状态分为三种：行波状态、驻波状状态、行驻波状态。

2、驻波状态下=Γ|| 1 ，=ρ ∞ 。

行波状态下=Γ|| 0 ，=ρ 13、均匀无耗传输线的特性阻抗为0Z ，终端负载获得最大功率时，负载阻抗=L Z 0Z 。

4、长线和短线的区别在于：前者为分布参数电路，后者为集中参数电路。

5、阻抗圆图的正实半轴为电压波腹点或电流波节点的轨迹，负实半轴为电压波节点或电流波腹点的轨迹。

6、圆波导传输的主模为 TE11 模，微带线传输的主模为准TEM 模。

7、在矩形波导中，当工作波长λ给定时，若要实现10TE 单模传输，则波导尺寸必须满足a a 2<<λ，b 2>λ。

8、二端口微波网络组合方式有级联方式、串联方式、并联方式。

9、归一化阻抗=Z ~0Z Z = Γ-Γ+11二、简答题（25分，1--3题各五分，4题十分）1、电磁波的波型是如何划分的，有哪几种波型。

答：根据导波系统中电磁波按纵向场分量的有无，可分为三种波型：--------------2分（1）横磁波（TM 波），又称电波（E 波）:0=H Z，0≠E Z ；-----------------1分（2）横电波（TE 波），又称磁波（H 波）：0=EZ，0≠H Z ；----------------1分（3）横电磁波（TEM ）：0=EZ，0=H Z 。

---------------------------------1分2、微波传输线的特性阻抗和输入阻抗的定义是什么？答：（1）传输线的特性阻抗定义为传输线上入射波电压)(z U i 与入射波电流)(z Ii之比，或反射电压)(z U r与反射波电流)(z I r之比的负值，即)()()()(0z z z z IU I U z rrii-==-------3分（2）输入阻抗的定义为该处电压U(z)与电流I(z)之比，即)()()(z I z U z z in =-----2分 3、什么是简并波？答：由于不同的m 、n 代表不同的波形，具有不同的场分布；------------------2分但对同一组m 、n 值TE 波和TM 波有相同的截止波长（频率）。

2022-2023年注册电气工程师《电气工程师发输变电专业》预测试题1(答案解析)

2022-2023年注册电气工程师《电气工程师发输变电专业》预测试题（答案解析）全文为Word可编辑，若为PDF皆为盗版，请谨慎购买！第壹卷一.综合考点题库(共50题)1.某医院以10kV三芯电缆供电，10kV配电室位于二楼，请问可以选用下列哪几种电缆外护层？（）A.聚氯乙烯B.聚乙烯C.乙丙橡皮D.交联聚乙烯正确答案：B、C本题解析：《电力工程电缆设计规范》（GB 50217—2018）第3.4.1-3条规定，在人员密集场所或有低毒性要求的场所，应选用聚乙烯或乙丙橡皮等无卤外护层，不应选用聚氯乙烯外护层。

医院是人员密集区，防火有低毒性要求，故不宜选用聚氯乙烯，可选用乙丙橡皮和聚乙烯，而交联聚乙烯是电缆绝缘层，不是电缆外护层。

2.架空线路杆塔的接地装置由较多水平接地极或垂直接地极组成时，垂直接地极的间距及水平接地极的间距应符合下列哪一项规定？（）A.垂直接地极的间距不应大于其长度的两倍，水平接地极的间距不宜大于5mB.垂直接地极的间距不应小于其长度的两倍，水平接地极的间距不宜大于5mC.垂直接地极的间距不应大于其长度的两倍，水平接地极的间距不宜小于5mD.垂直接地极的间距不应小于其长度的两倍，水平接地极的间距不宜小于5m正确答案：D本题解析：《交流电气装置的接地设计规范》（GB/T 50065—2011）第5.1.8条规定，当接地装置由较多水平接地极或垂直接地极组成时，垂直接地极的间距不应小于其长度的2倍；水平接地极的间距不宜小于5m。

3.A.见图AB.见图BC.见图CD.见图D正确答案：C本题解析：4.发电厂、变电站220kVGIS装置设4条钢接地线，未考虑腐蚀时，满足热稳定条件的最小接地线截面是下列哪项数值？（单相接地短路电流36kA，两相接地短路电流16kA，三相短路电流40kA，短路的等效持续时间0.7s）（）A.167.33mm2B.430.28mm2C.191.24mm2D.150.6mm2正确答案：D 本题解析：《交流电气装置的接地设计规范》（GB/T 50065—2011）第4.4.5条规定，气体绝缘金属封闭开关设备区域专用接地网与变电站总接地网的连接线，不应少于4根。

TE 试题(1)

一、填空题：1．IPC-A-610D中的3F是指产品的：2．公司的四大文化包括：3．ESD是指：4．ISO9000是：；ISO14000是：5．很多半导体中，主要有型半导体和型半导体，它们都是电中性。

PN结具有6．多级放大电路常见的耦合方式有7．二极管的结构按PN结形成的方式可分为：8．PN结具有单向导电性，所以半导体二极管可作为：等电路的主要器件。

9．按线路的接法，三极管放大电路分：10．22万伏= KV；1μA= A；1mH= H;1pF= F.11. 正弦量的三要素是：12．稳压二极管工作在状态。

13．电阻单位是：，用表示；电感单位是：，用表示，电容的单位是：，用表示。

14．三极管分：PNP和型两种，三个极分别是：15．三极管的三个工作区是：16．场效应管又称极型晶体管，它的三个极分别是：17．有一电阻负载，它需要一个直流电压为110V，直流电流为3A的电源，采用桥式整流电路，求变压器副边有效电压V2= 。

18．三极管和场效应管是一种可控开关器件，利用三极管的和来实现开关的接通与关断。

19．色环电阻的计算，红黑黄金：；棕蓝黄银：20．有一电阻标记为153，其阻值为：。

二、选择题：1．你每天的工们静电检查属于：（）A．你的防静电监督员B．你的主管C．技术人员D．你自己2．当你在处于静电敏感件时，你应该：（）A．在任何接地的工作场地B．胶袋运送它们C．将器件远离离子风机D．在导电地面穿着导电鞋并在坐下时带上防静电手线3．两种常见的防静材料：（）A．厚纸板和纸B．导体和静电耗散材料C．泡沬材料D．绝缘体和导4．焊接IC时，Jabil有几种标准方法：（）A．热风枪B．点对点式焊接C．拖焊D．异形烙铁5．使用热风枪返修无铅元件，温度设定为：（）A．350℃~400℃B．280℃~320℃C．183℃~220℃D．217℃~230℃6．下列哪些电容有极性：（）A ．电解电容B ．陶瓷电容C ．SMT 瓷片电容D ．A 与B 项7．贴片元件移位超过焊盘的最大限度是多少可以接收：（）A ．大于或等于二分之一B ．小于或等于二分之一C ．大于或等于四分之一D ．小于或等于四分之一8．非静电物品应远离我们的电子产品（）厘米A ．50B ．30C ．25D ．359．解决任何工事问题应：（）A ．逐级上报B ．找经理B ．找好朋友商量 D ．自己处理10．关于IC 说法不正确的是：（）A ．BGA 也属于ICB ．IC 内部是一个小型电路C ．IC 都有方向D ．IC 不具备电阻，电容功能11．PN 结加反向电压时，其耗尽层会变：（）A ．变窄B ．变宽C ．不变12．三极管放大作用的本质是：（）A ．电流控制作用B ．电压控制作用C ．电阻控制作用13．场效应管放大作用的本质是：（）Ａ．电压控制作用Ｂ．电流控制作用 C ．电阻控制作用14．NPN 和PNP 三极管的区别是：（）Ａ．由两种不同材料的硅和锗制成Ｂ．渗入的杂质元素不同Ｃ．P 区和Ｎ区的位置不同 15．三极管工作在放大区时，集电结（）；发射结（）。

2021《LTE初级认证考试》试题及答案解析1

2021《LTE初级认证考试》试题及答案解析1考号姓名分数一、单选题(每题1分,共100分)1、配置EPG-M 2012A 节点S11网络接口的IP地址需要用以下哪些命令（）A.[edit services epg sgw control-plane protocols gtp interfacess11] address-range address-rangeB.[edit services epg sgw] s11-vip-address s11-vip-address;C.[edit services epg sgw user-plane protocols gtp ran-network]address-range address-range;D.[edit services epg sgw control-plane protocols gtp interfacess4s11] address-range address-range;答案：D2、EPC HSS与AAA之间的接口是（）A.ShB.S6aC.WxD.SWx答案：D3、对于FDD，SSS在slot0和slot10的倒数第__个OFDM符号上A.0B.1C.2D.3答案：C4、关于下行物理信道的描述，哪个不正确:A.PDSCH、PMCH以及PBCH映射到子帧中的数据区域上B.PMCH与PDSCH或者PBCH不能同时存在于一个子帧中C.PDSCH与PBCH不能存在于同一个子帧中D.PDCCH、PCFICH以及PHICH映射到子帧中的控制区域上答案：C5、哪些不属于LTE层2？A.MAC层B.RLC层C.MM层D.PDCP层答案：C6、天线工程参数不包括A.天线极化方式B.天线高度C.天线下倾角D.天线方位角答案：A7、关于小区搜索，以下描述错误的是( ）A.A、小区搜索过程是UE和小区取得时间和频率同步，并检测小区ID的过程。

B.B、检测PSCH（用于获得5ms时钟，并获得小区ID组内的具体小区ID）C.C、检测SSCH（用于获得无线帧时钟、小区ID组、BCH天线配置）D.D、读取PCH（用于获得其它小区信息）答案：C8、波束赋形（TM7）使用的参考信号为（）A.port 0B.port 1C.port 5D.port 7答案：C9、LTE上行多天线技术称作（）A.MU-MIMOB.SU-MIMOC.4x4MIMOD.2x2MIMO答案：A10、TD-LTE中，TM8双流波束赋形模式相比较与TM3模式的速率优势体现于（）A.高SINR的情形B.中低SINR的情形C.所有SINR的情形D.答案：B11、LTE上行链路的物理层传输不包括下面哪项A.PRACHB.PUCCHC.PRRCHD.PUSCH答案：C12、优化工作中最基本的工作是A.切换优化B.起呼优化C.掉话优化D.覆盖优化答案：D13、S1接口的用户面终止在什么上？A.SGWB.MMEC.MMHD.SAW答案：A14、每个PDCP实体承载几个RB数据？A.只能1个B.只能两个C.只能三个D.多个答案：A15、天线性能参数不包括A.天线增益B.天线极化方式C.天线波束宽度D.天线高度答案：D16、LTE系统中，完成调度功能的调度器位于e-Node __层A.MAC层B.物理层C.网络层D.传输层答案：A17、停止进程号为21的进程的命令格式为:A.kill -p 21B.kill -1 21C.kill -6 21D.kill -9 21答案：D18、TD-LTE的PBCH采用()种发射模式A.SFBCB.CDDCC.TSTDD.FSTD答案：A19、哪些不属于下行影响覆盖的因素？A.频段B.合路损耗C.天线分集增益D.天线下倾角答案：C20、LTE系统中的PHICH承载的信息是（）A.针对PUCCH的反馈信息B.针对PUSCH的反馈信息C.针对PDSCH的反馈信息D.针对PDCCH的反馈信息答案：B21、以下不包括属于无竞争随机接入过程的为A.随机接入前导序列分配B.随机接入前导序列C.随机接入响应D.发送L2/L3消息答案：D22、发射模式(TM)中，下面哪一项的说法是错误的（）A.TM1是单天线端口传输：主要应用于单天线传输的场合B.TM2适合于小区边缘信道情况比较复杂，干扰较大的情况，有时候也用于高速的情况C.TM3是大延迟分集：合适于终端（UE）高速移动的情况D.TM4是Rank1的传输：主要适合于小区边缘的情况答案：D23、OMC客户端不能运行在以下哪个操作系统上（）A.Windows98B.WindowsXPC.Windows7D.Windows2000答案：A24、以下关于SRVCC的哪个说法是错误的（）A.SRVCC发生在UE漫游到LTE覆盖的边缘地区时。

《微波技术与天线》试题真题(A卷)

任课教师
考场教室
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2. BJ－100 型矩形波导（ a b 22.86 10.16mm 2 ）填充相订对介电常数 r 2.1 的介质，信号频率 f 10GHz ，求
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TE10 波的相波长 P 和相速度 vP 。
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1. 微波是指频率范围为 300MHz～3000GHz 的电磁波，它有着不同于其它无线电波的特点，诸如 _____________________ 、 ____________________ 、 ______________________、_____________________、

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3. 求电长度为，特性阻抗为 Z 0 的传输线段的散射参量矩阵。
4. 今有一段矩形波导，当终端短路时，测得某一波节位置 d1 15cm ，相邻另一个波节位置 d 3 17cm ；当终端接喇叭天线后，从 d1 向波源方向测得最近波节点位置 d 2 16.5cm ，驻波比 2 ，
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三、计算题（每题 10 分，共 40 分）
1. 均匀无耗传输线终端接 Z L 100 ，测得终端电压反射系数的相角 2 180 和电压驻波比 1.5 。计算终端电压反射系数 2 和传输线特性阻抗 Z 0 。
其中11te模的场分布和矩形波导中的场分布很相似因此圆波导中11te模很容易通过矩形波导中过渡得到而且11te模的最长容易实现单模传输

新初一语法提升试题一(解析版)

新初一语法提升试题一学校:___________姓名：___________班级：___________考号：___________一、语音题从选项中找出其画线部分与其他三个单词的画线部分读音不同的选项。

1．A．pattern B．brave C．action D．cat 2．A．examination B．educate C．empty D．enemy 3．A．bear B．wear C．near D．pear4．A．care B．copy C．certain D．coin 5．A．Chinese B．teacher C．touch D．Christmas【答案】1．B 2．A 3．C 4．C 5．D【解析】1．pattern/ˈpætn/；brave/breɪv/；action/ˈækʃn/；cat/kæt/。

根据音标可知，选项B的划线部分发音与其他三项的划线部分不同。

故选B。

2．examination/ɪɡˌzæmɪˈneɪʃn/；educate/ˈedʒukeɪt/；empty/ˈempti/；enemy/ˈenəmi/。

根据音标可知，选项A的划线部分发音与其他三项的划线部分不同。

故选A。

3．bear/beə(r)/；wear/weə(r)/；near/nɪə(r)/；pear/peə(r)/。

根据音标可知，选项C的划线部分发音与其他三项的划线部分不同。

故选C。

4．care/keə(r)/；copy/ˈkɒpi/；certain/ˈsɜːtn/；coin/kɔɪn/。

根据音标可知，选项C的划线部分发音与其他三项的划线部分不同。

故选C。

5．Chinese/ˌtʃaɪˈniːz/；teacher/ˈtiːtʃə(r)/；touch/tʌtʃ/；Christmas/ˈkrɪsməs/。

根据音标可知，选项D的划线部分发音与其他三项的划线部分不同。

故选D。

写出下列单词划线部分(元音字母)的音标6．face/ /7．these / /8．time / /9．go / /10．use/ /11．but/ /12．stop / /13．cat / /14．desk / /15．him/ /【答案】6．eɪ 7．i: 8．aɪ 9．əʊ 10．ju: 11．ʌ 12．ɒ 13．ᴂ 14．e 15．ɪ【解析】6．根据face的音标/feɪs/，可知划线的部分音标是/eɪ/，故填eɪ。

模拟试卷一及答案

试题（一）一、Single Choice Exam 单选题1. 下面哪条是碳水化合物独特的生理功能？（）A. 供给热能B. 构成机体组织成分C. 是维持神经系统正常活动不可或缺的物质D. 抗生酮作用2. 下面哪种氨基酸为半必需氨基酸？（）A. 亮氨酸B. 赖氨酸C. 蛋氨酸D. 半胱氨酸3. 膳食纤维摄入过少易导致：（）A. 肥胖症和胆石症B. 便秘和憩室病C. 大肠癌D. 以上都包括4. 关于维生素描述正确的是：（）A. 是维持人体正常功能的一类高分子有机化合物B. 体内完全不能合成C. 需要量很小D. 可构成身体组织5. 下面哪种食物含维生素B1最丰富？（）A. 精白米B. 富强粉C. 糙米D. 玉米6. 癞皮症是由于缺乏？（）A. 维生素B6B. 维生素B1C. 维生素B2D. 维生素A7. 体内唯一不能合成的营养素是：（）A. 矿物质B. 蛋白质C. 维生素D. 碳水化合物8. 低蛋白饮食就是指每日膳食中的蛋白质含量为（）A. 占全天总热能的10%B. <60gC. <40gD. 饮食中几乎不含蛋白质9. 膳食纤维是（）A. 单糖类物质B. 双糖类物质C. 可被消化吸收的多糖D. 不能被消化吸收的多糖10. 食品中所含热能和营养素能满足人体需要的程度被称为：（）A. 食品的营养素密度B. 食品的营养价值C. 食品的热能密度D. 食品营养质量指数11. 大豆具有降低血脂作用是因为含有（）。

A. 黄酮类B. 植物红细胞凝集素C. 植酸D. 酚糖苷12. 谷类中第l限制氨基酸是哪一种（）。

A. 蛋氮酸+胱氯酸B. 赖氨酸C. 色氨酸D. 苏氨酸13. 营养学正式成为一门学科的时间是：（）A. 1925年B. 1934年C. 1938年D. 1949年14. 下列哪些食品老年人不宜多食，以免引起高胆固醇血症（）。

A. 动物脑、鱼子B. 蛋黄、动物肝C. 牛奶、瘦肉D. 鸡蛋、贝类15. 谷粒中含B族维生素较多的部位是（）。

stem测试题

stem测试题
STEM测试题可以包含各种不同的问题，主要涉及科学、技术、工程和数学领域。

以下是一些可能的STEM测试题：
1. 编程题：编写一个程序，实现某种特定的功能或算法。

2. 数学题：解决一个涉及数学概念或技巧的问题。

3. 科学题：解释某个科学现象或实验结果，或者设计一个实验来测试某个假设。

4. 技术题：评估一个技术产品或系统的性能，或者解决一个与技术相关的问题。

5. 工程题：设计一个工程系统或产品，以满足特定的需求或目标。

这些题目只是示例，实际的STEM测试题可能更加复杂或具体，取决于测试的目的和目标受众。

1、在MRI扫描脉冲序列中的TR、TE分别代表( )

MRI部分考查试题一、选择题(每题3分,共60分)1、在MRI扫描脉冲序列中的TR、TE分别代表（）A 回波时间、重复时间B重复时间、回波时间C 回波时间、反转时间D重复时间、反转时间2、在MRI扫描图像中，T1WI适于显示（）A 水肿B 出血C 解剖结构D 液体3、注射Gd-DTPA后，不应采用的成像方法有（）A SE序列的T1加权成像B GRE序列的T1加权成像C T2加权成像D T1加权辅以脂肪抑制技术4、STIR序列是IR脉冲序列的一个类型，主要是在T1WI中抑制（）的短TI高信号。

A 脑脊液B 脂肪C 血液D 肌肉5、Flair 用于T2WI和PDWI中抑制（）的高信号，在中枢神经检查中意义大。

A 脑脊液B 脂肪C 血液D 肌肉6、目前在MRI成像中，成像速度最快的技术是（_）A SEB GREC GRASSD EPI7、影响MRI图像质量的最重要因素是（_ ）A FOVB NEXC SNRD CNR8、MR图像中的包裹伪影是可以完全消除的伪影，只要扩大（）A SNRB NEXC FOVD CNR9、MR图像中的磁敏感性伪影主要来源于出血的血肿所含的金属和（）成份。

A 铁B 铝C 铜D 铅10、MRI增强扫描对比剂应选用（）A 泛影葡胺B 优维显C 泛影钠D 二乙三胺五乙酸钆11、在磁共振检查时，不属于相对禁忌的是（）A 胰岛素泵B 心脏起搏器C 神经刺激器D 导联线12、下列哪一项不是MRI的优势（）A 不使用任何射线，避免了辐射损伤B 对骨骼，钙化及胃肠道系统显示效果好C 可以多方位直接成像D 对颅颈交界区病变的显示能力13、在SE序列中，T1加权像是指（）A 长TR，短TE所成的图像B长TR，长TE所成的图像C 短TR，短TE所成的图像D短TR，长TE所成的图像14、在SE序列中，T2加权像是指（）A 长TR，短TE所成的图像B长TR，长TE所成的图像C 短TR，短TE所成的图像D短TR，长TE所成的图像15、在SE序列中，质子密度加权像是指（）A 长TR，短TE所成的图像B长TR，长TE所成的图像C 短TR，短TE所成的图像D短TR，长TE所成的图像16、低浓度顺磁造影剂对质子弛豫时间的影响为（）A T1缩短，T2改变不大B T1缩短，T2延长C T1延长，T2缩短D T1缩短，T2缩短17、脂肪抑制技术可以改善下述哪一项伪影（）A 运动伪影B化学位移伪影C 卷褶伪影 D 截断伪影18、早期脑梗塞最适宜的扫描方式为（）A T1权成像B T2加权成像C 弥散加权成像D 质子加权像19、下列造影技术中，哪些不属于MR水成像范畴( )A MR胰胆管造影B MR尿路造影C MR血管造影D MR腮腺造影20、严格来讲，MRCP、MRU采用的是哪种成像方式（）A T1加权B T2加权C 重T2加权D 弥散加权二、问答题：(每题20分,共40分)1.简述磁共振颅脑扫描常规步骤？2.磁共振运动伪影如何分类，及其补偿方法？MRI部分考查试题答案与评分标准一、选择题(每题3分,共60分)1-10 BCCBA DCCAD11-20 BBCBA ABCCC二、问答题(每题20分,共40分)（一）每答对一条得4分1.线圈头线圈2.体位仰卧，头先进，眶耳线垂直台面。

第一部分直流电机试题

第三章直流电机一、填空1. 直流电机的电枢绕组的元件中的电动势和电流是。

答：交流的。

2. 一台并励直流电动机，如果电源电压和励磁电流f I 不变，当加上一恒定转矩的负载后，发现电枢电流超过额定值，有人试在电枢回路中接一电阻来限制电流，此方法。

串入电阻后，电动机的输入功率1P 将，电枢电流a I ，转速n 将，电动机的效率η将。

答：不行，不变，不变，下降，下降。

3. 一台并励直流电动机拖动恒定的负载转矩，做额定运行时，如果将电源电压降低了20℅，则稳定后电机的电流为倍的额定电流（假设磁路不饱和）。

答：1.25倍。

4. 并励直流电动机，当电源反接时，其中a I 的方向，转速方向。

答：反向，不变。

5. 直流发电机的电磁转矩是转矩，直流电动机的电磁转矩是转矩。

答：制动，驱动。

6. ★电枢反应对并励电动机转速特性和转矩特性有一定的影响，当电枢电流a I 增加时，转速n 将，转矩T e 将。

答：下降，增加。

7. 直流电动机电刷放置的原则是：。

答：空载时正、负电刷之间获得最大的电动势，这时被电刷短路的元件的电动势为零。

8. 直流电动机调速时，在励磁回路中增加调节电阻，可使转速，而在电枢回路中增加调节电阻，可使转速。

答：升高，降低。

9. 电磁功率与输入功率之差，对于直流发电机包括损耗；对于直流电动机包括损耗。

答：空载损耗功率，绕组铜损耗。

10. ★串励直流电动机在负载较小时，a I ；当负载增加时，T e ，a I ；n 随着负载增加下降程度比并励电动机要。

答：小，增加，增加，严重。

11. 并励直流电动机改变转向的方法有，。

答：将电枢绕组的两个接线端对调，将励磁绕组的两个接线端对调，但二者不能同时对调。

12. 串励直流电动机在电源反接时，电枢电流方向，磁通方向，转速n 的方向。

答：反向，反向，不变。

13. 当保持并励直流电动机的负载转矩不变，在电枢回路中串入电阻后，则电机的转速将。

微波技术基础期末试题一与参考答案汇编

模；
要保证单模传输，工作波长的范围为 2.286cm<λ<4.572 cm
（3）λ=3cm
p
3.98 cm
1
c
2
vp
v
3.98108 m/s
1
c
2
vg v
1
c
2
2.26 108
m/s
六、由一个二端口网络如图所示，传输线的特性阻抗Z0=200Ω，并联阻抗分别为 Z1=100Ω和Z2=j200Ω，求网络的归一化散射矩阵参量S11和S21，和网络的插入衰减（dB形式）、插入相移与输入驻波比（15 分）（第四章）
和等效电导
二、传输线理论工作状态（7 分）（第二章）在特性阻抗Z0=200Ω的传输线上，测得电压驻波比ρ=2，终端为电压波节点，
传输线上电压最大值 Umax =10V，求终端反射系数、负载阻抗和负载上消耗的功率。
解： 2
1 1
1 3
由于终端为电压波节点，因此
2
1 3
由 2
ZL ZL
Z0 Z0
λ/4
Z0
Z1
Z2
1
解：归一化传输矩阵
A
Z0
Z1
0
cos
1
j
sin
j sin cos
1
Z0 Z2
0
1
其中，
2
4
2
因此
1
A
Z
0
Z1
0
1
0 j
1
j 0
Z0 Z2
0
1
Z0
j
1
Z2 Z02 Z1Z
2
1
Z0 Z1

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TE 部修理員工(技朮員)詴題
1. 現有一SMT 電容及一SMT 電阻 ,電容上的標記為225 ,電阻上的標記為103 , 詴寫出該電容的電容值及電阻電阻值.
答: 电容 22 X 105 PF=2.2uF, 电阻 10 X 103 Ohm=10K.
2. 電解電容,陶瓷電容,鉭電容,SMT 瓷片電容中哪些具有极性. 答: 電解電容,鉭電容.
3. 在圖示電路中詴計算出: a) AB 間的電阻 R AB.
b) 電流I .
c) R 2 上消耗的功率 .
答: 1/R 24 = 1/R 2 + 1/R 4 R 24 = 1 K Ohm.
1/R AB = 1/R 1 + 1/(R 3 + R 24) => R AB = 1 K Ohm. I = V/ R AB
P R2 = ½ X ½ X ½ X P = 1/8 V I
4 .詴畫出一固定偏置共射放大電路,并寫出發射极,集電极,基极電流三者之間的關系.
V Ie= I b + Ib
5 .寫出對應的二進制數或十進制數 . R1 R2 2K 2K 1K R4
R3
2K B
A
I
6.寫出下列門電路的邏輯表達式 .
a) 圖1的邏輯表達式 .
C = A.B
b) 圖2的邏輯表達式 .
D=C(AB)
7. 有一正弦電流般的表達式為I = 10Sin(200π t + π/2), 詴求 : a) 最大電流I max . = 10
b) 有效值I 1 . = 10 / 1.414
c) 平均值I aver . = 0.
d) 畫出電流的波形圖 (I 与 t 的關系).
8 . 有一整流電路如右圖所示 ,詴計算其I max ,如無MN 線以右部分詴求U AB . 如無PQ 線以右部分詴求U AB.
I max = 12/R L
如無MN 線以右部分 UAB = 24
如無PQ 線以右部分 UAB=24/1.414
A
B
与門
非門
圖1
C
A B C
D
与非門
圖 2
〜24V
LM7812
C 2
R L
A
B M N
P
Q C 1
9 . 有一如下運算放大電路,請計算其放大倍數及說明R1 的作用.
A=R2/R3=10k/2k=5
R1 的作用:平衡电阻。

10 . 寫出下列DOS命令:
在C:\下建立一子目錄Jabil ,并將C:\從下所有擴展名為exe的文件拷貝至目錄Jabil下.
Cd c:
C:\Md Jabil
C:\copy *.exe jabil\
11 .寫出拆下208腳QFP IC ,BGA的工藝流程以及重裝BGA的工藝流程.
1．将板置于机器上，对好位置=》加热=》温度达到后=》操作机器移下零件2．将BGA装上机器=》加热=》温度达到后=》操作机器贴BGA至板上
12 .寫出厂74LS244的作用及工作電壓. .
8位缓冲寄存器5V
13 .若有一部ICT或FVT的坏机,請詳述Jabil的處理流程(至包裝位).
再确认=》修理=》再测试=》合格后=》送下一流程
14現有一部ICT坏机,測出電容C值有偏差,其在電路板上的連線如下圖,,詴述詳細的處理步驟.
拆下C，用万用表电容档测量是否在公差范围内。

如在公差内，则再同样方法测量C1。

如不在公差内，判C坏。

并换好料上板再
測詴點1
U o U i
R 2 10 K
R 3 2
R 1
重测ICT。

同样方法可以适用于旁边的电阻，直至问题
解决，ICT 测试通过为止。

測詴點2
15 . 詴述換下坏料的處理方法,及連續發現三快坏机的處理方法.
详细填好有关记录/报表，入电脑，将坏料交生产线作MRB处理。

連續發現三快坏机，填坏机表，通知上司。

16 . 請簡述對單片計算机有何認識.
17 .請畫出D触發器的工作時序圖案.
18 . 將以下英文翻譯為中文或寫出縮寫的全寫.
a)英譯中:
File--- 文件Search--- 搜索Refresh--- 刷新Delete---删除Reset--- 复位Exit--- 退出Insufficient--- 不足够Oxide---氧化Rework--- 返工Parallel---平行/并行
b)寫出下列縮寫的全寫:
BGA--- Ball Grid Array PLL--- Phase Lock Loop
1.文件管理分层次,根子目录成树形.
一个存储容量大的磁盘可以存放成千上万个磁盘文件,为了有效地管理提高查询速度,从PC-DOS 2.0起,采用了多级目录管理磁盘文件,每一级目录要形象地视为一层,多级目录就有多层目录.第一层目录(最外层目录)是由格式化命令FORMAT建立的,只有一个目录项,开机后一般情况下进入第一层目录.最外层目录称为根目录,第二层以后的目录叫子目录,是由MD命令建立的,每一层上允许并列多个子目录项.每一个子目录项有一个目录名,保存在与之相邻的外一层相关的目录中,通过这种关联方式,形成树形目录结构.
2.文件说明四要素,四素合为一参数.
文件说明是DOS的一个重要参数,它可以告诉DOS在何处找到指定的磁盘文件.该参数通常由磁盘驱动器标志符、路径、文件名和扩展名四部分组成,其格式是:
[d:][path] file [.ext]
在实际使用时根据不同情况选择其中的某一部分或几部分.但是,无论使用了几部分,都要把它们当做一个参数处理,即连续输入严禁插入空格或其它键.
3.当前默认可省略,其它选项按需列.
"当前"参数指当前正在操作中的制备参数、目录参数,常用的有磁盘驱动器标志符和路径,只要继续使用当前驱动器、当前目录 (d:)、(path) 就可以省略.假设当前驱动器 C: 当前目录在SFY下,查询LSY.PRG文件,使用命令C:\SFY>DIR LSY.PRG即可,若查询A盘WPS 子目录中的LWS.WPS文件,由于盘号、目录发生了改变, (d:)、(path) 两参数必需给出.即: C:\SFY>DIR A:\WPS\LWS.WPS
有些DOS 命令的操作分常规操作模式和特定操作模式,常规操作模式的规格参数在DOS 命令中已经设定,不用外带任何参数即能完成所需操作,这类参数属于默认参数,默认参数项可以省略.命令格式为:
C:\>FORMAT A:
4.命令在前参数后,命令参数间空格.
多数DOS命令都带有一个或几个参数,它们的一般格式是:命令 [参数] [参数]...
在使用DOS命令过程中,有时打入的命令、参数都正确,但是机器提示错误信息,一般错在没有按规定使用空格键.为此输入命令时注意以下几点:
①先打入命令后输入参数。

②命令与参数、参数与参数之间以空格键隔开。

③文件说明各部分之间不加空格符。