Z箍缩直线变压器驱动源原型模块设计

介绍了用于Z箍缩驱动器的快脉冲直线型变压器驱动源(LTD)原型模块设计和初步实验结果。该模块采用32个子块并联,每个子块由两台100kV/100nF脉冲电容器和一只200kV多间隙气体开关串联组成。32只开关由4路高压脉冲分别触发。模块直径为2.9m,厚度约27cm。电路模拟结果表明,在±90kV充电电压下,输出电流幅值为1.0MA,电流上升时间(10%~90%)约118.6ns。初步实验结果表明,在约90mΩ近似匹配电阻负载上获得的电流为995kA,上升时间(10%~90%)为120.8ns,脉冲宽度约335.2ns。实验结果与电路模拟结果较为接近。     

基于阻抗匹配条件的树枝状超材料吸收器

基于树枝状金属结构单元的电磁谐振特性,设计了一种双面大小树枝状结构的超材料吸收器,该结构分别是正面二级树枝及正对的背面三级树枝.通过仿真模拟设计了不同的阻抗匹配方式,调节相应的结构参数,找到了阻抗匹配对吸收特性的影响.在最佳的阻抗匹配条件下,得到最大吸收率.实验测量表明,阻抗匹配条件下双面大小树枝模型可以实现90.01%吸收率.增加样品层数可以有效的增加吸收率,3层样品就可以达到99%以上的吸收率,实现工程意义的完美吸收.     

基于多Agent的无线传感器网络分层融合框架研究

客户端/服务器（C/S）模式和移动代理（MA）模式是无线传感器网络中的两种最主要的计算模式,MA计算模式可以弥补C/S计算模式能量消耗大、延时长等方面的不足。为了更好的降低能量消耗和缩短网络中数据融合时间,提出一种基于多Agent的无线传感器网络分层融合框架。将无线传感器网络监测区域分层若干个区域,将每个小的监测区域分为簇头―sink和簇头―簇成员节点两层,由sink节点根据用户需求向每个监测区域派遣移动Agent并完成数据采集和数据融合。这种模式可以有效地缩短网络中数据融合时间和降低能量消耗。     

Challenges of partial discharge diagnostics of low-voltage cables

Partial discharge measurement is one of the most important diagnostic methods to detect local faults in insulation systems. Detection of local faults in low-voltage cables would be attractive for condition assessment of power plant secondary cables. The construction of low-voltage cables is different from the medium and high voltage ones, preventing the direct application of the already developed models and methods. An analysis of partial discharge detection and evaluation methods for low-voltage cable diagnostics are given in this paper. Some laboratory measurement results are also presented and the identified issues are described in this paper.     

桥梁拉索损伤声发射监测研究进展

大量索承体系桥梁即将达到20–30年的拉索寿命期,开展有效的拉索损伤监测方法研究有利于保障大桥结构安全。本文简要论述了现有桥梁拉索损伤检测及监测方法的适用性,重点综述了近40年来声发射技术应用于桥梁拉索监测的研究进展,以及在腐蚀、疲劳、断丝等损伤监测方面所取得的研究成果。结合实测数据在采集、数据处理过程中的难点及参数分析盲点,探讨了现有研究成果应用于特大桥梁拉索损伤监测仍需解决的问题,并针对性地提出了研究思路。     

Investigation of the electrical conductivity of powdered dielectrics

Results are reported of an investigation into the temperature dependence of the electrical conductivity of some powdered oxides and complex oxide systems with different grain sizes and different relative density of the specimens. Using spectral analysis the transport numbers of impurity ions are determined for some powdered technical dielectrics. Such data might be useful when choosing the insulating material for tubular electrical heating elements and high-temperature cables.     

Fiber optic aerial cables

While conventional cable elements can tolerate strains on the order of 1%, optical fibers cannot. As aerial cables may suffer contraction and elongation from low temperatures and high ice or wind loads, or high temperatures, respectively, proper designs have to provide the cables with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress. The well-suited loose tube buffer design, the way of calculation, and a list of reference cable plants are presented.     

Fiber optic aerial cables

While conventional cable elements can tolerate strains on the order of 1%, optical fibers cannot. As aerial cables may suffer contraction and elongation from low temperatures and high ice or wind loads, or high temperatures, respectively, proper designs have to provide the cables with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress. The well-suited loose tube buffer design, the way of calculation, and a list of reference cable plants are presented.     

Three-dimensional non-linear coupling and dynamic tension in the large-amplitude free vibrations of arbitrarily sagged cables

This paper presents a model formulation capable of analyzing large-amplitude free vibrations of a suspended cable in three dimensions. The virtual work-energy functional is used to obtain the non-linear equations of three-dimensional motion. The formulation is not restricted to cables having small sag-to-span ratios, and is conveniently applied for the case of a specified end tension. The axial extensibility effect is also included in order to obtain accurate results. Based on a multi-degree-of-freedom model, numerical procedures are implemented to solve both spatial and temporal problems. Various numerical examples of arbitrarily sagged cables with large-amplitude initial conditions are carried out to highlight some outstanding features of cable non-linear dynamics by accounting also for internal resonance phenomena. Non-linear coupling between three- and two-dimensional motions, and non-linear cable tension responses are analyzed. For specific cables, modal transition phenomena taking place during in-plane vibrations and ensuing from occurrence of a dominant internal resonance are observed. When only a single mode is initiated, a higher or lower mode can be accommodated into the responses, making cable spatial shapes hybrid in some time intervals.     

PTS装置工作模式及波形调节

为了对即将建成的PTS装置的实验能力进行分析,对装置的工作模式及波形调节能力进行了分析。装置具有三种工作模式:短脉冲模式、长脉冲模式和波形调节模式。在不同的工作模式下,装置可以进行不同负载的实验研究。在基本工作模式下,在15 nH负载上输出前沿90 ns、幅值8~10 MA脉冲电流。通过电路模拟,对装置在三种工作模式下预计的负载电流输出进行了分析,短脉冲模式下装置负载电流的上升时间约90 ns,长脉冲模式时约200 ns,波形调节模式时可以达到400 ns。模拟结果表明,通过调节激光触发气体开关的触发方式和脉冲输出开关及装置其他参数,PTS装置可以输出脉冲前沿100~400 ns、波形形状在一定范围可调的强电流脉冲。