机车牵引电机电器故障可靠性诊断分析系统

为了提高机车研究、设计、制造以及维修水平,提高机车牵引电机、电器设备的可靠度,有必要开发机车牵引电视、电器故障可靠性诊断系统.文中介绍了在WINDOWS98下开发的机车牵引电机、电器故障可靠性诊断分析系统的设计方法和实现技术,主要包括系统目标、系统设计及实现中的关键技术.     

Supply Chain Models with Mutual Commitments and Implications for Social Responsibility

In today's increasingly globalized environment, more and more companies recognize the mutual dependence of supply chain partners in value creation. When making business decisions, they take into consideration their partners’ bottom line profitability, especially in emerging markets. The question is, is this kind of practice sustainable? This study makes an attempt to formalize this issue by examining a stylized two‐party supply chain model in which each player maximizes its own profit while making a certain commitment to its partner. We compare five different games between the two supply‐chain partners, which reflect different power positions of the players and different levels of commitment. We identify conditions under which both players are better off with mutual commitments than without, a situation we call win–win. We show that win–win can be achieved if and only if the mutual commitments are comparable. Thus, the recognition of mutual dependence of the supply chain members needs to be translated into reciprocal concerns. In addition, different players’ commitments play different roles but together they have a similar effect as a profit sharing contract. Finally, we discuss the implications of our findings in the context of socially responsible operations. In particular, our analyses show that it is possible to care about the supply chain partners’ bottom line without sacrificing one's own profitability, and our models can be used as a tool to determine the commitment levels by evaluating the predicted outcome.     

Testing Branching Process Estimators of Cascading Failure with Data from a Simulation of Transmission Line Outages

We suggest a statistical estimator to quantify the propagation of cascading transmission line failures in large blackouts of electric power systems. We use a Galton‐Watson branching process model of cascading failure and the standard Harris estimator of the mean propagation modified to work when the process saturates at a maximum number of components. If the mean number of initial failures and the mean propagation are estimated, then the branching process model predicts the distribution of the total number of failures. We initially test this prediction on failure data generated by a simulation of cascading transmission line outages on two standard test systems. We discuss the effectiveness of the estimator in terms of how many cascades need to be simulated to predict the distribution of the total number of line outages accurately.     

运动电荷的库仑定律与电场

在讨论库仑定律时，一般注重分析静态形式，没有分析运动电荷的库仑定律与电场，本文针对此问题就运动电荷的库仑定律及电场进行分析与讨论。     

新型全电动式注塑机直拉式电动射移机构

采用射移丝杠安装于机架方式的全电动式注塑机电动射移机构,易造成推力块的力臂结构长度过长。当喷嘴顶 靠于模具时,由于过大偏载力矩的作用而产生上翘现象。针对性地设计开发了新型直拉式电动射移机构。该机构将注 射单元通过直拉式射移机构直拉于定模板上,大大减小了全电动式注塑机射移力系的封闭回路里出力机构的射移丝杠 中心线与机筒中心线的距离,使机架不再需要承受原有设计由于射移最终阶段喷嘴顶紧模具浇口产生的顶靠力,从而大 大改善了射移机构和喷嘴的受力情况,同时也简化了机架结构,进而减轻了机架的结构重量。     

具有能量回馈的纯电动车驱动控制系统

针对纯电动汽车驱动系统在能量回馈过程中的系统效率不高的问题,设计了以TMS320LF2407为核心的硬件及软件系统,利用SVPWM调制技术结合磁链跟踪技术的控制方法,实现制动过程中电机产生的制动能量回馈到蓄电池中;并在搭建的双电机对拖试验台上进行实验。实验数据表明,永磁同步电机驱动系统具有较高的系统效率,系统效率85%以上的工作点占72. 73%,能够回收较多的能量,提高了续驶里程。     

电力工业与火电行业生态效率实证分析

电力工业具有高消耗、高污染、高排放的特点,是导致大气污染的主要因素之一,因此提升电力工业生态效率是我国节能减排与应对气候变化的有效途径,也是整个电力工业特别是火电行业持续健康发展的基础。本文利用2001-2011年全国电力工业及火电行业的发电量、装机容量、从业人员、原料投入以及SO2、CO2排放数据,采用数据包络分析方法计算了整个电力工业和火电行业的生态效率,结果表明,火电行业虽然经过了一系列的节能减排改造,但是火电为主的行业结构特点是直接影响电力工业生态效率偏低的主要因素。根据统计结果,对改进电力工业和火电行业生态效率进行了分析,并建议我国电力工业要从国家层面、行业主管部门和电力企业共同挖掘节能减排空间,实现电力工业低碳、绿色发展。     

“电力系统继电保护”课程教学改革的思考

从电力系统继电保护的发展、课程的设置、教学内容的选择及教学方法等方面,结合教学实践中继电保护课程的特点,针对继电保护课程的教学改革提出了的相应的看法和意见,探讨了提高专业课教学效果的有效方法,并提出将电力系统继电保护与微型机继电保护统一讲授的教学思想,使学生既掌握了电力系统继电保护原理的基础理论,同时对继电保护发展领域的新知识、新技术也有一定的了解。     

基于有限元方法的抽油杆管磨损量预测

针对在斜直井、定向井、水平井等井中采取有杆泵采油作业时,由于抽油杆屈曲以及井眼弯曲导致抽油杆严重偏磨的问题,建立了抽油杆动态行为有限元分析方法。利用能量法原理,将抽油杆发生偏磨时产生的摩擦功与金属磨损消耗的能量联系起来,确定了有杆抽油系统杆管偏磨磨损量预测模型,利用有限元分析得到的接触力可以定量分析杆管柱的磨损量。结果表明,有限元方法模拟效果较好,可用于预测井下杆管偏磨情况,对油田采取合理的防偏磨措施具有重要的指导意义。     

弛张振荡电路的理论分析和实验研究

通过对非线性电路的理论分析 ,证实了非线性电路非稳定态的存在 ,即产生弛张振荡的依据 .并通过实验观察到弛张振荡的现象