CRH3C型高速动车组DC110V接地故障的分析及排除

文章介绍了DC110 V接地故障对动车组的影响,阐述了DC110 V供电系统和它的负载分配情况,总结了DC110V接地的检测方法,重点论述如何利用这些检测方法及时发现处理CRH3C型高速动车组DC110 V接地故障,对于提高铁路运输质量安全具有重大意义。     

随机工资下DC型企业年金的最优资产配置策略——基于鞅方法求解

研究了当工资为一个随机过程时,缴费确定型(DC)企业年金如何对股票、国债以及银行存款进行最优资产配置的问题。假设企业年金的投资目标为最终财富的期望效用函数最大化,利用鞅方法给出了此优化问题的解析解。结果表明,企业年金的最优投资策略由三部分组成:Merton投机策略、工资的收入效应投机策略以及工资的随机效应对冲策略。     

小议直流电动钻机的功率测算及其集电环的维护

随着钻井新工艺的发展,出现了采用水平井、方向井、超深井等来寻找油气的趋势,使得石油钻机必须突破传统的结构型式,以满足各类钻井的要求。在当今世界能源紧缺的情况下,节约能源减少石油钻井生产时的能源消耗,显得更为重要。面对此情况,我们必须对直流电动钻机由无功功率大而引起的发电机功率消耗大的现状加以改进。对影响直流电动钻机集电环使用寿命的问题进行了探讨。     

浅析35kV变电站直流系统改造方案

随着科技和管理的进步,变电站直流系统正朝着自动化和免维护的方向发展,对直流系统要求的不断提高使得直流系统的改造势在必行,本文从分析当前35kV变电站直流系统存在的问题入手,以此提出改造目标,并对直流系统的改造措施进行简要分析。     

高电压直流耐压试验对电缆寿命的影响

直流耐压试验主要是为了检测绝缘体耐压性能的一种方法,通过试验可以对纸绝缘电缆的性能强弱进行判断,以保证电缆在电力系统中能持续发挥作用。目前,直流耐压试验已经广泛运用于各种电缆的检测,可以及时发现电缆潜在的缺陷,提醒技术人员尽快更换电缆以维护系统运行。由于直流耐压试验过程中遇到各种阻碍因素,导致了试验对电缆寿命造成不利的影响,文章针对这一问题展开深入分析。     

Airport traffic complexity and environment efficiency metrics for evaluation of ATM measures

For a given (current or planned) traffic demand, different air traffic management measures could result in different airport traffic complexity and efficiency. This paper presents the research on the relationship between airport traffic complexity and time and environmental efficiency for different air traffic control (ATC) tactics applied to the given or planned airport layout. Emphasis is placed on the evaluation of airport traffic complexity, aircraft fuel consumption, gas emissions and time efficiency for different ATC tactics and/or airport airfield layouts. For busy airports during peak hours, arrival queuing delays, taxi-in, taxi-out times and departure queuing delays increase, which induces additional unnecessary fuel consumption, gas emission and time inefficiency. In order to find a tool which could indicate potential delay generators, a measure of airport traffic complexity – called Dynamic Complexity is proposed. Experiments were performed for airports with different airfield layouts, for different traffic demands and ATC applied tactics using SIMMOD simulation model. Traffic situations were analyzed and delays were measured. The values of airport traffic complexity, fuel consumption and gas emissions were also determined. A comparative analysis of the results show: first, the proposed airport traffic complexity metric quite satisfactorily reflects the influence of traffic characteristics upon the environmental state of the system, and second, different ATM strategic and tactical measures (airport airfield infrastructure development and applied ATC tactics) could significantly reduce traffic complexity and increase time and environmental efficiency at the airport.     

基于IGBT的PWM大功率直流伺服驱动

本文介绍ＩＧＢＴ、ＥＸＢ８４１和ＬＥＭ模块在大功率ＰＷＭ直流伺服驱动系统中的应用和系统抗干扰设计。使用效果表明，基于ＩＧＢＴ的设计，可提高大功率直流伺服系统的可靠性和性能、减小体积、降低成本。     

基于MCS-51直流调速系统设计及仿真

设计一个以电动机作为被控对象,用8031单片机作控制器的数字化直流调速系统。该系统的特点是用单片机取代模拟触发器、电流调节器、速度调节器及逻辑切换等硬件。对系统进行了硬件及软件设计,最后应用Matlab仿真软件对系统进行了仿真,给出了仿真结果。     

简易旋转倒立摆及控制装置

本系统是针对简易旋转倒立摆而设计的自动调节装置,使用12C5A60S2单片机控制L298驱动进而控制直流电机。使摆杆处于动态平衡的装置。通过角度传感器采集摆杆的状态数据,实时调整直流电机的转向和转速,以调整摆臂的角度,使摆杆恢复到动态平衡状态。在非平衡状态下,通过角度传感器的实时检测,能够通过功能键设计,使摆杆能稳定到一定的角度。