A survey of efficiency-estimation methods for in-service induction motors

Condition monitoring of electric motors avoids severe economical losses resulting from unexpected motor failures and greatly improves the system reliability and maintainability. Efficiency estimation, which shares many common requirements with condition monitoring in terms of data collections, is expected to be implemented in an integrated product. This brings more considerations into the selection of the efficiency-estimation methods. This paper presents the results of an up-to-date literature survey on efficiency-estimation methods of in-service motors, particularly with considerations of the motor-condition-monitoring requirements. More than 20 of the most commonly used methods are briefly described and classified into nine categories according to their physical properties. Six categories of these methods are more related to in-service testing and are compared in a table summarizing the required tests and measurements, intrusion level, and average accuracy. Estimation of the rotor speed and the stator resistance, the two stumbling blocks of various efficiency-estimation methods, is also carefully studied; commonly used methods are summarized. Based on the survey results, four efficiency-estimation methods are suggested as candidates for nonintrusive in-service motor-efficiency estimation and condition-monitoring applications. Another contribution of this paper is that a general approach for developing nonintrusive motor-efficiency-estimation methods is proposed, incorporating rotor speed, stator resistance, and no-load loss estimations.     

低温冰箱内温度场的有限元分析

认为有限元分析方法FEM(funite elementmethod)是一种应用非常广泛的数值计算方法;介绍了ANSYS有限元分析软件,并利用ANSYS软件对一台低温冰箱内的温度场进行计算和分析;提出了优化箱内温度场均匀分布的措施.     

高速锯床防护罩抗冲击能力的有限元分析

利用ANSYS/LS_DYNA的动力学分析功能对GS3050型超高速数控锯床安全防护罩的抗冲击能力进行了数值分析,对刀具碎片侵彻有机玻璃的过程进行了数值模拟.结果表明,采用厚度为15 mm的改性丙烯酸脂有机玻璃作为GS3050锯床的安全防护罩是可靠的.数值分析和试验的结果吻合.     

包钢无缝厂轧管机辊缝伺服系统的调试

在原有轧管机管壁人工控制的基础上 ,引入液压伺服系统及自反馈控制 ,完成对管壁轧制的自动控制     

关于食品生产监管信息化建设的思考

本文对全国食品生产监管信息化系统建设进行探讨,对信息化系统的建设方法和亟待解决的问题加以分析。     

Metallic Graphene Nanoribbons

Isolated graphene nanoribbons(GNRs)usually have energy gaps,which scale with their widths,owing to the lateral quantum confinement effect of GNRs.The absence of metallic GNRs limits their applications in device interconnects or being one-dimensional physics platform to research amazing properties based on metallicity.A recent study published in Science provided a novel method to produce metallic GNRs by inserting a symmetric superlattice into other semiconductive GNRs.This finding will broader the applications of GNRs both in nanoelectronics and fundamental science.     

IPM智能功率模块在高精度惯导测试设备中的应用

为满足高精度惯导测试设备的需要,针对我国目前直流伺服系统仍采用IGBT、晶闸管为主功率电路的现状,采用第五代智能功率模块IPM开发了一款新型的直流伺服系统;该系统相对于采用传统功率器件的伺服系统在性能指标与可靠性方面都有极大地提高,电流环带宽达到了1kHz.同时具有很好的电磁兼容性;应用于某高精度惯导测试设备0.001°/s速率检测,速率精度为0.0×10°,速率平稳度为9.2×10-5,结果表明,IPM智能功率模块应用于惯导测试设备中,系统性能稳定,伺服精度高,尤其是在功率密度和抗干扰性能方面表现突出,具有很好的应用前景.     

基于覆盖次数的叠前振幅归一化处理在大庆油田的应用

振幅一致性处理对连片处理至关重要,尤其对叠前偏移,因为各个区块的施工因素不同,区块间的能量差异很大,这样在叠前偏移处理中会导致严重的偏移噪音(边界划弧现象),影响了成像质量.利用基于覆盖次数的振幅归一化处理技术,对大庆油田松辽盆地徐家围子断陷连片叠前时间偏移的振幅一致性进行处理,在保证原始地震道不丢失的前提下,很好地解决了叠前偏移的能量一致性问题,见到了明显的应用效果.