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迈克尔逊干涉仪测定金属线胀系数实验分析——升温测量和降温测量 被引量:3
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作者 汤国富 范婷 《大学物理实验》 2015年第1期24-26,47,共4页
利用迈克尔逊干涉仪可精确测量微小长度这一特性来测定金属在一定温度变化范围内,热胀冷缩的微小长度变化,从而得到一种更加精确测量金属线胀系数的新方法。并分别进行了升温测量和降温测量。后经对实验结果及实验误差的对比分析,结果显... 利用迈克尔逊干涉仪可精确测量微小长度这一特性来测定金属在一定温度变化范围内,热胀冷缩的微小长度变化,从而得到一种更加精确测量金属线胀系数的新方法。并分别进行了升温测量和降温测量。后经对实验结果及实验误差的对比分析,结果显示,降温测量相比升温测量,可极大地减小实验误差,提高实验精度。 展开更多
关键词 金属线胀系数 迈克尔逊干涉仪 升温测量 降温测量 最小二乘法
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压接型IGBT器件升温曲线测量方法
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作者 钟岩 张一鸣 +2 位作者 邓二平 谢露红 黄永章 《半导体技术》 CAS 北大核心 2022年第12期1014-1026,共13页
利用热网络模型和有限元仿真分析了压接型IGBT器件升降温曲线不具有等效性的原因,研究了压接型IGBT器件升温曲线的测量方法,对比了大电流通态压降(V_(CE))法和大电流阈值电压(V_(GE,th))法的测量原理,对压接型器件的适用性和测量准确度... 利用热网络模型和有限元仿真分析了压接型IGBT器件升降温曲线不具有等效性的原因,研究了压接型IGBT器件升温曲线的测量方法,对比了大电流通态压降(V_(CE))法和大电流阈值电压(V_(GE,th))法的测量原理,对压接型器件的适用性和测量准确度等。仿真结果表明,接触热阻在升温和降温阶段受压力的影响出现了不同的变化趋势,导致了升降温曲线的非等效性。实验结果表明,大电流V_(GE,th)法有效降低了压力对测量带来的影响,测量更为准确,测量误差基本在1 K以内,低于大电流V_(CE)法,为压接型IGBT器件进一步的多物理场耦合研究和老化监测提供了参考。此外,实验结果还表明压接型IGBT器件在升降温过程中,压力变化越大,升降温曲线的差异越明显。 展开更多
关键词 压接型IGBT器件 升降温等效性 升温曲线测量 大电流通态压降(V_(CE))法 大电流阈值电压(V_(GE th))法
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熔点仪升温速率在线测量系统 被引量:1
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作者 王维峰 施江焕 励丽 《计量技术》 2016年第5期27-30,共4页
针对检定熔点仪升温速率的测量系统存在的二等铂电阻温度计直径较大、安装困难的不足,为提高熔点仪升温速率在线测量水平,利用OMEGA铠装热电偶直径小、稳定性好的特性,提出一种基于OMEGA铠装热电偶和525A多功能校准器相结合的熔点仪... 针对检定熔点仪升温速率的测量系统存在的二等铂电阻温度计直径较大、安装困难的不足,为提高熔点仪升温速率在线测量水平,利用OMEGA铠装热电偶直径小、稳定性好的特性,提出一种基于OMEGA铠装热电偶和525A多功能校准器相结合的熔点仪升温速率在线测量系统;同时提出了采用混合滤波方法优化稳定性。实测数据表明:应用本文测量系统所测得的升温速率能够满足要求。 展开更多
关键词 升温速率在线测量系统 熔点仪 铠装热电偶
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An experiment discovery about gravitational force changes in materials due to temperature variation 被引量:1
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作者 Fan Liangzao Feng Jinsong Liu Wuqing 《Engineering Sciences》 EI 2010年第2期9-11,共3页
The authors discovered in first time that the weight of materials or its gravitational force by earth related to its temperature and its ferromagnetism. An experiment was designed to elevate the temperatures of six di... The authors discovered in first time that the weight of materials or its gravitational force by earth related to its temperature and its ferromagnetism. An experiment was designed to elevate the temperatures of six different materials (Au, Ag, Cu, Fe, Al, Ni) up to 600 ℃and precisely measured their weights. It is found all the materials weigh about 0.33 ‰ - 0. 82 ‰ less. For example the weight of silver sample weighted by a precision electronic scale in a manner of special design decreases about 0.8 ‰, when its temperature is elevated to 600 ℃. Thus different metals' gravitational forces or weights are adjusted with temperature variation. 展开更多
关键词 metal gravitational force internal energy of mass ferromagnetic materials NDFEB
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Shock Tube Measurement of Ethylene Ignition Delay Time and Molecular Collision Theory Analysis
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作者 Xiao-he Xiong Yan-jun Ding +1 位作者 Shuo Shi Zhi-min Peng 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第6期761-766,I0002,共7页
In this study, 75% and 96% argon diluent conditions were selected to determine the ig- nition delay time of stoichiometric mixture of C2Ha/O2/Ar within a range of pressures (1.3-:3.0 arm) and temperatures (1092-17... In this study, 75% and 96% argon diluent conditions were selected to determine the ig- nition delay time of stoichiometric mixture of C2Ha/O2/Ar within a range of pressures (1.3-:3.0 arm) and temperatures (1092-1743 K). Results showed a logarithmic linear rela- tionship of the ignition delay time with the reciprocal of temperatures. Under both two diluent conditions, ignition delay time decreased with increased temperature. By multiple linear regression analysis, the ignition delay correlation was deduced. According to this correlation, the calculated ignition delay time in 96% diluent was found to be nearly five times that in 75% diluent. To explain this discrepancy, the hard-sphere collision theory was adopted, and the collision numbers of ethylene to oxygen were calculated. The total collision numbers of ethylene to oxygen were 5.99×10^30 s^-1cm^-3 in 75% diluent and 1.53×10^29 s^-1cm^-3 in 96% diluent (about 40 times that in 75% diluent). According to the discrepancy between ignition delay time and collision numbers, viz. 5 times corresponds to 40 times, the steric factor can 展开更多
关键词 Shock tube ETHYLENE Ignition delay Molecule collision
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Evaluation of Cloud Feedback at Local Scale: Warming or Cooling?
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作者 Esmaiel Malek 《Journal of Environmental Science and Engineering(B)》 2015年第4期216-226,共11页
Clouds affect the climate by positive and negative feedback. To study these effects at local scale, a radiation station was set up, which used two CM21 Kipp & Zonen pyranometers (one inverted), and two CG1 Kipp & ... Clouds affect the climate by positive and negative feedback. To study these effects at local scale, a radiation station was set up, which used two CM21 Kipp & Zonen pyranometers (one inverted), and two CG1 Kipp & Zonen pyrgeometers (one inverted) in Logan, Utah, USA. The pyranometers and pyrgeometers were ventilated using four CV2 Kipp & Zonen ventilation systems. Ventilation of pyranometers and pyrgeometers prevent dew, frost and snow accumulation, which otherwise would disturb the measurement. Knowing that available energy (Rn) as Rn = Rsi - Rso + Rli - Rio where Rsi and Rso are downward and upward solar radiation, respectively, and Rli and Rio as atmospheric and terrestrial, respectively, the effects of cloudiness were evaluated on a daily and annual basis. The results indicate that for the partly cloudy days of 4 and 5 September, 2007, cloudiness caused less available energy (Rn) in the amounts of-1.83 MJ·m^-2·d^-1 and -3.83 MJ·m^-2·d^-1 on these days, respectively. As shown, due to cloudiness at the experimental site, the net radiation loss was 2,804 - 4,055 = -1,251 MJ·m^-2·d^-1, which indicates a negative feedback due to cloudiness. 展开更多
关键词 Cloud feedback PYRANOMETER pyrgeometer.
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