基于重复控制技术的逆变电源研究

将重复控制技术应用于单相全桥逆变电源,构成了一种低成本、高性能的波形控制系统。介绍了该重复控制系统的设计方法,分析了系统的稳定性。实验表明,采用重复控制技术使系统具有良好的稳态特性。     

夹钳式承载架结构及应用介绍

介绍了一种在特大型变压器运输中采用的夹钳车承栽架的基本结构,分析了承栽架应具有的各个自由度,并对夹钳式承栽架的不同方案进行了比较和分析。     

电力负荷管理系统的现状及发展

介绍了电力负荷管理系统的基本现状，并对该系统为适应新形势下供电部门的需求而必须完善和加强的功能做了详细的说明。     

集中荷载作用下R.C.双向受弯约束梁斜截面抗剪强度的计算

在13根集中荷载作用下钢筋砼双向受弯约束梁斜截面抗剪试验研究的基础上，采用等效梭形截面法，将双向受弯约束梁转化为单向受弯约束梁，并推出集中荷载作用下钢筋混凝土双向受弯约束梁斜截面抗剪强度的计算方法．     

Microforms in Gravel Bed Rivers: Formation, Disintegration, and Effects on Bedload Transport

This research aims to advance current knowledge on cluster formation and evolution by tackling some of the aspects associated with cluster microtopography and the effects of clusters on bedload transport. The specific objectives of the study are (1) to identify the bed shear stress range in which clusters form and disintegrate, (2) to quantitatively describe the spacing characteristics and orientation of clusters with respect to flow characteristics, (3) to quantify the effects clusters have on the mean bedload rate, and (4) to assess the effects of clusters on the pulsating nature of bedload. In order to meet the objectives of this study, two main experimental scenarios, namely, Test Series A and B (20 experiments overall) are considered in a laboratory flume under well-controlled conditions. Series A tests are performed to address objectives (1) and (2) while Series B is designed to meet objectives (3) and (4). Results show that cluster microforms develop in uniform sediment at 1.25 to 2 times the Shields parameter of an individual particle and start disintegrating at about 2.25 times the Shields parameter. It is found that during an unsteady flow event, effects of clusters on bedload transport rate can be classified in three different phases: a sink phase where clusters absorb incoming sediment, a neutral phase where clusters do not affect bedload, and a source phase where clusters release particles. Clusters also increase the magnitude of the fluctuations in bedload transport rate, showing that clusters amplify the unsteady nature of bedload transport. A fourth-order autoregressive, autoregressive integrated moving average model is employed to describe the time series of bedload and provide a predictive formula for predicting bedload at different periods. Finally, a change-point analysis enhanced with a binary segmentation procedure is performed to identify the abrupt changes in the bedload statistic characteristics due to the effects of clusters and detect the different phases in bedload time series using probability theory. The analysis verifies the experimental findings that three phases are detected in the bedload rate time series structure, namely, sink, neutral, and source.     

ТДГ3．15万kVA主变压器经济运行分析

根据电力变压器功率损耗的分析，找到ТДГ3．15万kVA2台主变压器的功率损耗与负荷率β的函数关系，并对该2台主变压器的经济运行进行了探讨，计算出了经济运行点。     

基于神经元网络的快速监控功能

应用神经元网络理论和计算机仿真实验相结合的方法,对用快速监控理论解决带钢头部厚度超差问题进行了研究。针对板带材轧制过程是一个复杂的非线性过程,难以建立精确数学模型的问题,提出了用神经元网络实现快速监控功能的方法,仿真证明,该方法对于及时地消除厚度偏差的后遗性有着比其他控制方法更好的效果。     

Repair of notched beam under dynamic load using piezoelectric patch

In this paper, the repair of a cracked beam under an external dynamic load employing the electro-mechanical characteristic of piezoelectric material to induce a local moment is presented. Conceptually, an external voltage is applied to actuate a piezoelectric patch bonded on the beam to effect closure of a crack so that the singularity at the crack tip under dynamic load may be decreased. Globally, this has the effect of altering the resonant frequency of the cracked beam towards that of the healthy beam, which is the criterion used for the repair. To demonstrate the repair methodology, a cantilever beam is used as an illustration, where the repair moment coefficient and the voltage required are mathematically derived. The relationship between repair moment coefficient, crack parameters and length of piezoelectric patch is investigated. The difference between the proposed repair criterion and an earlier published criterion for cracked beam under static load is also shown. A numerical example is used to study the effectiveness of the proposed repair methodology and its results are compared with those from 3-D finite element analyses using ABAQUS 6.4 as one means of verification.     

钻孔嵌岩灌注桩承载特性试验研究

钻孔嵌岩灌注桩已成为高层建筑较常用的基础形式之一．在南昌地区某工程中，通过对钻孔灌注桩进行静载试验，分析研究了钻孔嵌岩灌注桩的承载特性和荷载传递机理，对此类桩的侧摩阻力与端阻力的问题进行了探讨。     

WEB应用系统性能测试的实现

对WEB应用系统进行合理的性能测试是保证系统质量的一个重要过程。以某远程教学系统为案例,借助于测试工具Load Runner,从负载反应层面对系统性能进行验证,并对测试结果进行分析,以保证系统的合理优化。