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991.
为了实现在国产数控锥齿轮铣齿机上加工摆线齿端齿盘,对摆线齿端齿盘的切齿加工原理和加工方法进行了研究.基于摆线齿端齿盘的结构特点,提出了采用整体刀盘加工摆线齿端齿盘的加工方法,并通过改变刀盘半径和刀刃圆弧半径对轮齿齿长曲率和齿高曲率进行了修正.基于摆线齿端齿盘的切齿加工原理,提出了加工摆线齿端齿盘的刀盘参数以及机床调整参数的计算方法,对摆线齿端齿盘进行了刀盘干涉检查.通过实际的切齿加工、齿形误差检测以及接触区着色检验,验证了在国产数控锥齿轮铣齿机上采用整体刀盘加工摆线齿端齿盘的加工原理和加工方法的正确性和可行性. 相似文献
992.
993.
针对广州地铁A7型车正线运行过程中出现的辅助逆变器并网异常问题,通过对列车故障现象以及系统日志文件的分析,采用反向论证法排查电路控制系统,得出并网异常故障的原因及提出地铁列车控制电路系统的相关调试建议. 相似文献
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996.
为研究流体特性及管道参数等对长距离管道系统运行的影响,以海上采油树液压控制系统为原型,采用AMESim建立了长管道液压系统的仿真模型.研究了管道参数及流体属性对管道压力损失及动态特性的影响,并分析了影响长管道液压冲击的因素及改善方法.表明在管道直径、液压油属性不变的前提下,随着管道长度的增加,管道压力损失不断增大,系统负载的速度及位移响应时间增加;随着管道直径的减小,负载速度响应及位移响应逐渐降低,响应时间增加;随着粘度的增加,管道压力损失增加,负载响应时间增加;而流体密度对管道的压力损失、负载速度响应及负载位移响应的变化影响较小.随着管道长度的增加和管道直径的减小,压力冲击峰值有减小的趋势,通过安装蓄能器对压力冲击有明显的改善作用.分析了影响长管道液压系统动态特性的因素,优化了系统参数匹配,对长管道液压系统的设计提供了参考,对实际液压系统的设计具有指导意义. 相似文献
997.
The laser soldering process was introduced in Micro‐USB electronic packaging in this paper. Numerical modeling and analysis was used for laser process parameter design, because experimental measurements of peak temperature and soldering stress are expensive and often intractable. Accurate knowledge of the residual stress and distortion is a prerequisite for the reliability of the electric connector. The present work proposes a three‐dimensional transient heat transfer model of Micro‐USB package laser soldering process. The calculated thermal cycles and distribution are subsequently used to calculate the distortion and thermal stresses. Meanwhile, the effect of process parameters on residual stress and pin distortion was discussed, and the tensile strength, microstructure, and residual stresses of laser soldering were tested. It can be concluded that the proper laser soldering parameters and power can improve the mechanical property of solder joints on Micro‐USB connector. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
998.
Yong Li Li Qiu Depeng Jin Li Su Pan Hui Lieguang Zeng 《Wireless Communications and Mobile Computing》2015,15(3):527-537
Groups of people with mobile phones using short‐range connections such as WiFi and Bluetooth to propagate messages can be modeled as, with regard to regular absence of end‐to‐end connection, mobile social networks (MSNs), which can be exploited to offload a significant amount of mobile content from the overloaded infrastructure networks such as 3G. The study of content transmission delay for the applications of mobile content dissemination in MSNs is an important problem, because to enhance the network capacity, the traffic is offloaded at the cost of inducing longer delay. In contrast to existing works, which ignore the factors of contact duration limits and large content size, we present a contact duration aware framework to model the content dissemination process in MSNs, give an explicit expression for the average content dissemination delay, and reveals its relationship with various system parameters of content size, users’ selfishness, number of involved subscribers, infecting ratio, and so on. We apply our proposed model to real‐life traces to assess its reliability by comparing the theoretical results with measured statistics and present extensive upshots to evaluate the influence of various parameters on system performance. The results demonstrate the accuracy of our proposed framework and reveal that system parameters of content size, system infecting ratio and intragroup transmission are the most important factors to influence the content dissemination delay. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
999.
Chunwei Song Rongxiang Zhao Zheng Zeng Minglei Zhu 《IEEJ Transactions on Electrical and Electronic Engineering》2015,10(4):465-473
We present a six‐leg voltage source inverter (VSI) with a single DC link to feed a three‐phase inductive load. The space vector pulse width modulation (SVPWM) of the six‐leg inverter is studied in detail. The novel switching strategy in one sampling period for H bridge is proposed to avoid the 180° phase shift of the PWM signals for upper and lower side switches. Based on the novel switching strategy, a dead‐time elimination SVPWM is proposed, which can be easily implemented on a digital signal processor. Experimental results are presented to demonstrate the validity and features of the proposed novel SVPWM. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
1000.
Aidong Zeng Qingshan Xu Maosheng Ding Kazuto Yukita Katsuhiro Ichiyanagi 《IEEJ Transactions on Electrical and Electronic Engineering》2015,10(4):396-403
Storage devices are indispensable elements in a microgrid to compensate for the power imbalance between loads and the distributed generator (DG) output. Different storage strategies give diverse performances in adjustment speed and capacity. Based on the performance of different storage devices and the features of power imbalance curve in different periods, a classification control strategy is proposed in this paper. First, storage devices are given priorities according to the adjusting speed, and the power imbalance curve is divided into two periods according to the changing speed. During an emergency, all the storages are employed to compensate the rapidly increasing power imbalance; during the steady period, storage device with higher priority is employed to track the instantaneous component of power imbalance, while storage device with lower priority is used to replace the kWh output of higher priority storage. The proposed strategy is tested in a microgrid within the subdistribution network of IEEE RBTS Bus6 system using Monte Carlo methods. Simulation results indicate that the classification control strategy could endow the system with fast adjusting ability through coordination between storages. Reliability indices of the testing system are utilized to demonstrate that the classification control strategy could improve the stability of the microgrid and reliability of the distribution network. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献