V-型皱褶芯材承压的均质化等效模型

采用代理模型获得V-型皱褶芯材等效屈服应力、等效平台应力和几何参数之间的关系,并据此提出了一种承受静力/准静力面外压缩的V-型皱褶芯材均质化等效模型。计算结果与试验结果的对比表明:皱褶芯材的均质化等效模型可以很好地模拟原结构的弹塑性力学特性,并能大大减少计算耗时。对于皱褶夹芯板在结构中,特别是抗坠毁吸能结构中的应用,本文的等效模型提供了一种高效率的计算及优化手段。     

Permeability analysis of fractured vuggy porous media based on homogenization theory

Based on the characteristics of fractured vuggy porous media,a novel mathematical model was proposed to model fluid flow in such media on fine scale,i.e.,the discrete fracture-vug network model.The new model consists of three systems:porous rock system,fracture system,and vug system.The fractures and vugs are embedded in porous rock,and the isolated vugs could be connected via the discrete fracture network.The flow in porous rock and fractures follows Darcy's law,and the vugs system is free fluid region.Usi...     

磁路独立组合转子复合励磁发电机的设计

复合励磁发电机在移动电源领域有着广泛的应用前景。该文提出了一种磁路独立组合转子复合励磁发电机,介绍了其结构和磁路特点。在此基础上,提出了电机的电磁设计方法,并推导了电机重要参数E0、Xad、Xaq的计算方法。设计了一台额定功率为25kW的样机,样机试验结果表明,设计计算值准确,电机性能均达到了要求。     

基于Qt/Embedded的断路器故障诊断专家系统

设计了基于Qt/Embedded多线程机制的断路器故障诊断专家系统,提出一种综合故障仿真、故障模拟、数学模型分析结果及业内专家经验、文献资料等建立断路器故障诊断专家系统知识库的方法。针对断路器知识库的特点,选用产生式规则及框架表达知识,设计了专家系统的推理机制。最后,对专家系统的有效性进行了试验验证。     

漏电断路器的故障分析

简单介绍了漏电断路器的性能和保护种类,举例说明漏电断路器的常见故障现象及原因分析。     

微型程序控制器在低压供电系统中的应用

在低压供电系统中通常利用传统继电器设计控制线路,主要是因为复杂的接线造成的低可靠性和不能灵活地满足用户不同的控制要求。在低压供电系统中用微型程序控制器代替传统继电器可以显著地提高可靠性,可以灵活地满足用户不同的控制要求,大大提高了成套开关设备的性价比。     

金属氧化物避雷器短路试验(压力释放试验)的重要性分析

为了保证避雷器即使发生故障也不会损坏其他设备或者影响人身安全,短路试验是一项非常重要的试验。由于试验回路电压或容量的关系,在有些短路试验中,避雷器的短路电流第一个峰值达不到要求的试验电流有效值的1.7-2.5倍,通过短路电流的时间往往也不足0.2秒。如果所进行的试验不符合这一要求,将不能真正考验避雷器压力释放装置是否能够起到防爆作用。     

Selection of minimal tripping times for distance protection using fault trees with time dependencies

Correct coordination between protection relays is an essential requirement to maintain stability and integrity of electrical power systems. Time settings of protection relays have to be adapted to time characteristics of electrical power systems and time settings of other protections. In the paper, fault trees with time dependencies (FTTD) are used for selecting time delay settings of remote back-up distance protections. In FTTD, events and gates are characterized by time parameters, which are derived from time characteristics of protection devices and the inherent delays of protection equipment. Two case studies are presented. First, the coordination of protections for the simple transmission line composed of two identical sections is studied. Next, the transmission line that contains two sections of different lengths and transformer between them is analyzed. In both cases, formulae for time delays of protections are derived. According to calculations executed for the first case, our method gives time delays that often are significantly smaller than values suggested by generally recommended and accepted rules.     

LTB145D1／B-2STANDS型断路器储能回路缺陷分析及改进方法

通过分析LTBl45D1／B-2STANDS型断路器储能装置工作原理及故障原因,提出了可靠的改进方案,使得在弹簧未储能的情况下能可靠闭锁合闸回路,同时也能有效保护储能电机。     

一种多频感应测井仪激励电路设计

多频感应测井是一种新兴的技术,有诸多传统测井技术无法比拟的优点。激励电路的设计是仪器重要的一环,它决定了仪器的感应强度。本文通过分析激励频率、效率和放大类型的关系,解析E类放大器的工作原理,从最优化激励效果的角度,提出了多频感测井激励电路的设计思路,并通过仿真软件进行参数仿真设计。仿真实验结果验证了所选择激励电路的正确性及先进性,为后续测井仪器激励电路的设计提供了依据。