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李金田 《涪陵师范学院学报》2004,20(5):67-68
介绍了四臂电桥、变量器电桥、双T电桥测量阻抗的原理,总结了三种电桥的优缺点。为了实现阻抗的高精度测量,提出了在不同的频率范围内,应选用不同的电桥法。在阻抗的实际测量中,具有指导性作用。 相似文献
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在全国中学生物理竞赛中,利用平衡电桥法进行阻值测量是一类比较常见的实验。测量一般电阻的阻值常采用惠斯登电桥,测量电表内阻时也可采用汤姆孙电桥。 相似文献
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测量电阻的一种比较准确的方法是电桥法,但一般电桥不适合测量高值电阻,本文旨在介绍一种改进电桥,用它来测高值电阻,其系统误差较小,可达到准确测量的目的。 相似文献
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项飞羽 《贵州教育学院学报》2004,15(4):29-30
介绍用交流电桥换臂法测量电容的原理,并与交流电桥不换臂法从实验数据、实验结果、实验误差等方面进行分析和比较,从而得出交流电桥换臂法测量较为精确。 相似文献
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对电桥灵敏度及自组惠斯登电桥换臂测量的数据处理进行了探讨。指出换臂前后电桥的灵敏度发生了变化,换臂前后两个测量结果的可置信度不同,两次测量结果应被认定为非等精度测量值,其合成方法应遵循非等精度测量值合成法则。 相似文献
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用惠斯通电桥测电阻的原理如图1,电桥平衡时下式成立 (1)应用合分比原理可进一步得到 (2) 由于导线电阻和接触电阻的存在,给测量带来很大误差,尤其是测量低电阻时(低电阻用双电桥),误差更大。为了消除导线电阻和接触电阻给测量带来的误差,我们利用电桥的多次平衡法测量, 相似文献
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本文详细介绍了模拟乘法器在单相功率测量、三相功率测量、电桥测量以及百分比误差测量等方面的应用 相似文献
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用单臂电桥测量电阻是普通物理实验中常用的一种电阻测量方法。依据单臂电桥的工作原理,通过理论分析和数学推导,分析了影响单臂电桥灵敏度的各种因素,给出了获得最大灵敏度时电桥应具备的条件。最后通过实验进一步验证了推导出的结论。 相似文献
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杜思义 《重庆大学学报(英文版)》2003,2(2)
1. Introduction In the structural damage identification, the confirmation of parameters sensitive to damage is the foremost, namely to decide what parameters are to be adopted, the next is to distinguish damaged from undamaged, and to determine the position and severity of damages. For local damage, an identifying parameter should be a local quantity and accord the following 4 basic conditions: 1) it is sensitive to local damages and is a monotone function depicting the severity of structural … 相似文献
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颜桂云 《福建工程学院学报》2012,(1):12-16
为检验在役混凝土拱桥的承载能力与动力特性,对某净跨为134.7m的拱桥进行荷载试验。测试结构静态的应变、桥面挠度、拱肋挠度、吊索变形、吊索索力等结构静力反应。同时,测试了结构自振频率、动挠度及加速度等结构动力反应,根据动挠度计算得出冲击系数。将实测值与理论值进行对比分析。结果表明,应变校验系数在0.7~1.0之间,实测的挠度、吊索索力、频率及冲击系数均小于理论值,说明桥梁具有较好承载力和整体竖向刚度较好。试验方法与分析结果为今后评估与鉴定同类型桥梁提供理论依据和技术参考。 相似文献
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宗教教职人员是社会中宗教组织的发起者、组织者,又是宗教群体的领导者。他们一方面起到沟通神与信徒之间的“桥梁”作用,另一方面又是联结党和政府与信教群众的“桥梁”。第一重作用使得他们在履行上帝赋予其任务时具有了神圣的地位,而这成为发挥第二重“桥梁”作用的前提和基础。第二重作用应是所有宗教教职人员的根本出发点和落脚点。对于宗教教职人员的培养不仅要努力提高他们的宗教学识,更主要的方面在于培养宗教人士的爱国意识。 相似文献
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针对银川北二环一号桥的具体特点,在主梁标高控制、斜拉索索力测试和控制、主梁截面应力监测等方面作了详细的陈述,为同类型桥梁的施工控制提供技术参考。 相似文献
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Zhang YZ Zhou YC Liu L Lu Y Hirofumi Y 《Journal of Zhejiang University. Science. B》2007,8(6):416-421
Objective: There are no detailed reports of three-dimensional measurement of abutment teeth in mastication, because it is knotty to observe the rotation in chewing directly, and inexact to estimate indirectly. This work studies the three-dimensional stability of rigidly fixed bridge under the stresses of distributed loads and concentrated loads by optical method that gives the tip angle and rotation angle calculated directly based on measurement data. Methods: The specimen, taken from a 25-year-old male, was a left mandible without the second premolars and the first molars. As abutments, first premolar and second molar have complete periodontium. The specimen was soaked in formaldehyde solution. The bridge was fixed between two abutment teeth (first premolars and second molars), and the mandible was cemented in a steel box. The load was increased from 0 kg to 23 kg. Laser holographic technique was used to measure the three-dimensional bit shift of the dens, both buccolingual bit shift and mesiodistal bit shift, and determine tip angle and rotation angle. Results: The effects of stress distribution on the rigidly fixed bridge were evaluated, and stabilization of the bridge under the stresses of distributed loads and concentrated loads, respectively, were analyzed. The results showed that the tips of two abutments were very similar, and no distinct difference was observed between the distributed load and the concentrated load. However, the maximum rotation angle for the distributed load was two to four times as large as that for the concentrated load. In the experiment, the tip angle of the abutment teeth was no more than 0.65 degree, and the rotation angle was no more than 0.60 degree. All maximum angles occurred in the second molar. Conclusion: The fixed bridge is considered to be safe. In addition, a method for measuring the rotation angle was provided effectively. 相似文献