电大9月份考试传感器与测试技术第三次作业.doc

专业好文档2013年9月份考试传感器与测试技术第三次作业一、填空题（本大题共20分，共 10 小题，每小题 2 分）1. _ 电容传感器因多极电容及平均效应，所以分辨力高，精度高，量程大（测量范围大），对刻划精度和安装精度要求可有所降低，是一种很有发展前途的传感器2. _ 是指传感器在允许误差限内，其被测量值的范围，而量程则是指传感器在测量范围内的上限（最高）值和下限（最低）值之差。3. 滑动觉传感器被用于工业机器人手指把持面与操作对象之间的 _ ，以实现实时控制指部的 _ 。4. 机器人上常用的位移传感器有 _ 、 _ 和 _ 。5. 常用调制器把直流信号先变成某种频率的 _ ，经交流放大器放大后，再通过 _ ，使交流信号重新恢复到原来的 _ 。6. 图像处理中编码的作用是 _ 7. 信息与信号的关系是 _ 。8. 半导体温度传感器常采用 _ 代替二极管作为感温元件。9. 光导摄像管是一种兼有 _ 功能和 _ 功能的真空管。10. 为了避免通过交流电时产生感抗，或有交变磁场时产生感应电动势，金属热电阻在绕制时要采用 _ 绕制法。二、计算题（本大题共40分，共 4 小题，每小题 10 分）1. 磁电式线速度传感器的线圈平均直径D=25mm，气隙磁感应强度B=6000Gs。希望传感器的灵敏度k600（mVcms），求工作线圈的匝数N应为多少？2. 求正弦信号x(t)=Asint的均方值x2 。3. 已知信号x（t）试求信号x（0.5t），x（2t）的傅里叶变换。4. 利用电涡流位移传感器和频率计数器测某轴的转速。欲使频率计所读频率的数值等于12转速的数值（如f=50Hz，表示n= 25rmin）。问齿盘的齿数z为多少?若使f的数值等于n，z又为多少?三、简答题（本大题共20分，共 4 小题，每小题 5 分）1. 电阻应变式测力传感器的工作原理？2. 试说明光栅位移测量系统的四细分原理。3. 什么是热电偶的分度表？4. 有源滤波器由运算放大器和RC网络组成。它与无源滤波器相比，具有哪些优点？四、综合分析题（本大题共20分，共 2 小题，每小题 10 分）1. 用应变片组成电桥测力F，贴片见图3。试回答下列问题： 1、在图3a与图3b两种情况下，应分别将应变片接在电桥哪两个臂上？ 2、在图3a与图3b两种情况下，应分别采取什么措施，抵消温度变化引起的电阻变化？2. 一电涡流测振仪测量某主轴的轴向振动。已知，传感器的灵敏度为15mV/mm，最大线性范围6mm。现将传感器安装在主轴右侧，见图2a。用记录仪记录振动波形，见图b。问： 1、传感器与被检测金属的安装距离l为多少毫米时，可得到较好的测量效果？ 2、轴向振幅的最大值A为多少？ 3、主轴振幅的基频是多少？答案：一、填空题（20分，共 10 题，每小题 2 分）1. 参考答案：容栅式解题方案：容栅式电容传感器因多极电容及平均效应，所以分辨力高，精度高，量程大（测量范围大），对刻划精度和安装精度要求可有所降低，是一种很有发展前途的传感器评分标准：一空一分2. 参考答案：测量范围解题方案：测量范围是指传感器在允许误差限内，其被测量值的范围，而量程则是指传感器在测量范围内的上限（最高）值和下限（最低）值之差。评分标准：一空1分3. 参考答案：相对运动夹紧力解题方案：滑动觉传感器被用于工业机器人手指把持面与操作对象之间的相对运动，以实现实时控制指部的夹紧力。评分标准：一空一分4. 参考答案：旋转变压器；差动变压器；感应同步器；解题方案：评分标准：5. 参考答案：交流信号解调器被测信号解题方案：常用调制器把直流信号先变成某种频率的交流信号，经交流放大器放大后，再通过解调器，使交流信号重新恢复到原来的被测信号。评分标准：一空一分6. 参考答案：用最少量的编码位（亦称比特）来表示图像，以便更有效地传输和存储。解题方案：编码的作用是用最少量的编码位（亦称比特）来表示图像，以便更有效地传输和存储。评分标准：一空一分7. 参考答案：信息的载体称为信号 信息则蕴涵于信号之中解题方案：此题考察信息与信号的关系。评分标准：8. 参考答案：晶体三极管解题方案：此题考察半导体温度传感器的原理。评分标准：9. 参考答案：光电转换 扫描解题方案：此题考察光导摄像管的原理。评分标准：10. 参考答案：双线无感解题方案：此题考察金属热电阻抗干扰的方法。评分标准：二、计算题（40分，共 4 题，每小题 10 分）1. 参考答案：已知D=25mmO.025m，k600（mVcms） 60（Vms），B=6000Gs=0.6T 因为ENBLv，kEv NBL，LD×0.025 所以Nk（BL）=1274匝解题方案：评分标准：2. 参考答案：解题方案：评分标准：3. 参考答案：解题方案：评分标准：4. 参考答案：解题方案：评分标准：三、简答题（20分，共 4 题，每小题 5 分）1. 参考答案：电阻应变式测力传感器是将力作用在弹性元件上，弹性元件在力作用下产生应变，利用贴在弹性元件上的应变片将应变转换成电阻的变化。然后利用电桥将电阻变化转换成电压（或电流）的变化，再送入测量放大电路测量。最后利用标定的电压（或电流）和力之间的对应关系，可测出力的大小或经换算得到被测力。 解题方案：评分标准：2. 参考答案：空间相角彼此相差4的四个光电元件接收光栅的莫尔条纹的光强信号（即在一个莫尔条纹间距中装四个光电元件），并将其转换为电信号。图6中，A为0°接收光-电管，B为90°接收光电管，C为180°接收光电管，D为270°接收光电管。由A、B、C、D得到相位差90°的四个光电信号，经整形为四个脉冲。因此，光栅每移动一个栅距，就可得到四个脉冲，完成四细分。解题方案：评分标准：3. 参考答案：是热电偶温度传感器在冷端温度为0的条件下，输出热电动势的毫伏值与热端温度之间的对应关系，采用表格表示。不同材料组成的热电极有不同的分度表。常用热电极材料有铜-康铜、镍铬-考铜、镍铬-镍硅。解题方案：评分标准：4. 参考答案：（1）有源滤波器不用电感线圈，因而在体积、重量、价格、线性度等方面具有明显的优越性，便于集成化。（2）由于运算放大器输入阻抗高，输出阻抗低，可以提供良好的隔离性能，并可提供所需增益。（3）可以使低频截止频率达到很低范围。解题方案：评分标准：四、综合分析题（20分，共 2 题，每小题 10 分）1. 参考答案：解题方案：评分标准：2. 参考答案：1、取其传感器线性范围的1/2,即取L3mm时，线性度最好，测量范围最大。 2、因为输出ykx，由图b知 y45mV k15mV/mm 所以 x45/15mm3mm（峰-峰值） 振幅 Ax/2=3/2mm1.5mm 3、由图2b知，主轴振动周期 T20/2ms10ms10×10-3s频率 ?1/T1/10-2Hz100Hz解题方案：评分标准："If we don't do that it will go on and go on. We have to stop it; we need the courage to do it."His comments came hours after Fifa vice-president Jeffrey Webb - also in London for the FA's celebrations - said he wanted to meet Ivory Coast international Toure to discuss his complaint.CSKA general director Roman Babaev says the matter has been "exaggerated" by the Ivorian and the British media.Blatter, 77, said: "It has been decided by the Fifa congress that it is a nonsense for racism to be dealt with with fines. You can always find money from somebody to pay them."It is a nonsense to have matches played without spectators because it is against the spirit of football and against the visiting team. It is all nonsense."We can do something better to fight racism and discrimination."This is one of the villains we have today in our game. But it is only with harsh sanctions that racism and discrimination can be washed out of football."The (lack of) air up there Watch mCayman Islands-based Webb, the head of Fifa's anti-racism taskforce, is in London for the Football Association's 150th anniversary celebrations and will attend City's Premier League match at Chelsea on Sunday."I am going to be at the match tomorrow and I have asked to meet Yaya Toure," he told BBC Sport."For me it's about how he felt and I would like to speak to him first to find out what his experience was."Uefa has opened disciplinary proceedings against CSKA for the "racist behaviour of their fans" during City's 2-1 win.Michel Platini, president of European football's governing body, has also ordered an immediate investigation into the referee's actions.CSKA said they were "surprised and disappointed" by Toure's complaint. In a statement the Russian side added: "We found no racist insults from fans of CSKA."Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunda.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he'll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it's not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it won't. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).cause there