伏安法测电阻实验的改进及误差分析

伏安法测电阻是电学的基本实验之一.该方法简单易行,在电阻测量中得到广泛应用.然而,该方法难以避免电表内阻对测量结果的影响.本文提出一种不增加测量电路复杂度便可消除电表内阻影响的新方法,即采用内接和外接法测量两个电阻的阻值,将内接和外接法的计算公式联立,便可消除电表内阻的影响,从而得到电阻的测量值.实验采用Origin软件进行数据分析,估算了待测电阻的阻值及其不确定性.结果 表明,该方法的计算结果在误差范围内与标准值相吻合,验证了该方法的可靠性.     

自旋阀巨磁电阻位移传感器测金属线膨胀系数

巨磁电阻在测量微弱磁场的变化较其他传感器具有体积小、灵敏度高等优点.比较了多层膜巨磁电阻和自旋阀巨磁电阻的区别,按其特性设计一个采用自旋阀巨磁电阻的位移传感器,并用此位移传感器精确测量金属的线膨胀系数.与各大高校在此实验中用普通方法测金属线膨胀系数的方法相比,该自旋阀巨磁电阻位移传感器测量金属线膨胀系数的方法有操作简便、测量精确,以及将力学量用电学量测量,并将物理数字化,便于电脑采集等优点.     

基于神经网络的异步电机直接转矩控制中的定子电阻辨识研究

主要采用直接转矩控制的矿井输送机在低速运行时因定子电阻受温度等条件的变化而变化,导致电机磁链观测不准确,电机转速转矩脉动大。为实现定子电阻的准确辨识,设计了基于BP神经网络的定子电阻辨识器,它以转速推算值与实际测量转速误差作为BP神经网络输入,采用梯度下降算法训练系统参数实现定子电阻辨识。仿真结果表明,该方法对定子电阻辨识精度较高,系统响应速度较快,电机转矩脉动减小,直接转矩控制系统低速运转时性能得到改善。     

电阻噪声实验教学系统设计与实现

设计了一套便携式电阻噪声实验教学系统。对电阻的1/f噪声和热噪声进行了理论分析,提出了利用惠斯通电桥构成电阻噪声测量电路,并论证了电桥测量电阻噪声的可行性。介绍了系统的组成框架,电路输出的电阻噪声经过低噪声差动放大器放大,再由USB数据采集卡采集并传输给上位机;上位机采用Labview软件实现对噪声数据的读取和分析,对数据进行FFT变换和功率谱计算,从而观察到了电阻噪声的特性。为了观察和记录实验过程,利用Labview提供的IMAQ Vision视觉模块,结合USB摄像头实现了视频显示和录制。经测试,该系统能快速检测出电阻噪声信号,并观测到电阻1/f噪声和热噪声的特性,可满足实验教学要求。     

应用等强度梁测定电阻应变片灵敏系数

介绍了采用等强度梁和与测量片并联电阻的方式测定电阻应变片的灵敏系数的方法。该方法与用电桥测出的方法相比,结构简单,数据精确。     

伏安法测电阻及拓展应用

电阻的测量历来是高考的热点,也是高考难点．中学电学实验核心内容是电阻测量,伏安法测电阻是实验的基本方法,其他如等效替代法、半偏法等等都是在此基础上演化出来的．深刻理解伏安法测电阻要诣是做好实验的关键,在很多复杂多变的测量电阻的电路设计中,其本质思想都是伏安法测电阻．本文从伏安法测电阻实验原理出发,给出伏安法测电阻实验电路,拓展一些常用的测量电阻方法．     

细胞膜离子通道电流检测仿真实验教学设备研制

生物体内带电离子通过细胞膜上蛋白质流动产生的离子通道跨膜电流测量是依靠膜片钳放大器来实现的,仪器成本高昂。将膜片钳-离子通道测量实验应用于本科生教学受到教学经费的制约。利用计算机仿真技术模拟实验操作环境,对封接电阻检测电路测量。仪器硬件系统采用封接时负压注射器的运动带动滑竿可变电阻来模拟封接过程的电阻变化,软件系统采用MSP430监控软件和微机显示分析处理软件,研制出细胞膜离子通道电流仿真实验教学设备。此仪器的应用实现了开展离子通道电流测量的实验教学的目的,更好地促进了学生掌握细胞膜离子通道电流检测技术。     

绝缘电阻的测量

绝缘强度直接影响着人们的安全 ,所以电器设备绝缘强度的测量就显得非常重要。本文介绍了用电容充电法测量绝缘电阻的方法 ,该方法可以测量绝缘介质的表面电阻、体电阻和综合电阻。既经济、实用 ,又便于掌握 ,是实验室测量绝缘电阻的有效方法     

电学学习"口诀"两例

1伏安法测电阻 电阻的测量是近年来高考的热点,也是高考难点.在很多复杂多变的测量电阻的电路设计中,其本质思想都是伏安法测电阻.方法如下：     

替代法测电阻与伏安法测电阻的联系

替代法测电阻是运用等效替代原理快捷地推理出结论,只运用了一些概念性的电学知识,与电学规律没有多大的关联,而伏安法测电阻则需运用欧姆定律等电学规律测量被测电阻,两种测量电阻的方法在表面上有巨大差异,似乎在测电阻知识体系中出现了一条鸿沟。因此,有必要在教学中讲清楚替代法测电阻服从的电学规律,找出替代法测电阻与伏安法测电阻之间的联系,在测电阻的方法上为学生架起一座融会贯通的桥梁。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.