Input-parallel output-parallel configuration of boost half bridge DC-DC converter with control strategy

The concept of connecting two boost half bridge DC-DC converter modules in input-paral- lel output-parallel configuration is presented. The input-parallel-output-parallel （IPOP） converter consists of multiple boost half bridge （BHB） DC-DC converter modules which are connected in par- allel at the input and output side. This kind of converter is an attractive solution for high power ap- plications. The correlation between input current sharing （ICS） and output current sharing （OCS） of the IPOP converter basic modules is described. Two loop control strategies, consisting of input cur- rent loop and output voltage loop, have been developed to achieve equal ICS and OCS in this present work. The control strategy for the IPOP configuration of boost haft bridge DC-DC converter has been verified for different load conditions （half load and full load）, The IPOP system proposed here is comprising of two modules but it can be extended to three or more. The performance of the pro- posed system along with the control strategy is verified by simulation in MATLAB using Simpower tool. Finally the satisfactory simulation results are obtained.     

接触网硬点检测系统设计与实现

电力机车在运行过程中,接触硬点过大是造成机车受电弓离线的重要原因之一,因此必须通过接触网硬点检测系统排查硬点故障。该检测系统充分利用先进的检测技术,改善了电力机车的运行环境,提高了安全系数。     

SOI基光学电流传感器的设计与仿真

将光纤与微电子机械系统(MEMS)技术相结合,设计了一种新颖的检测50Hz高压交流电的光学电流传感器(OCS)。用ANSYS软件分析了器件的模态、动态响应与热膨胀特性,并通过Matlab软件模拟了器件的工作性能。模拟计算表明:ANSYS与理论公式得到的结果基本一致;传感器的量程为100~3600A,对于大电流下的灵敏度可达到0.02dB/A,温度变化±50K时传感器相应的测试误差为0.2%。     

微机电光学电流传感器的设计

提出了一种检测50Hz交流电的微机电光学电流传感器。通过电磁学、微机电与光学方法说明了传感器的敏感原理与光学转换原理,结合工艺条件给出了器件的设计要求,并利用matlab软件模拟分析了传感器的仿真测试结果。计算表明,器件可以测试1~7.2kA的交流电,大电流下的灵敏度可达到0.01dB/A以上。     

OCS表面活性剂中试产品应用于大庆原油的界面张力性能研究

研究了OCS表面活性剂中试产品在强碱NaOH条件下应用于大庆不同原油时的油-水界面张力特性。结果表明,对于大庆采油一厂至四厂的原油,OCS表面活性剂质量分数在0.1％～0.3％、NaOH质量分数在0.6％～1.2％的范围内,油-水界面张力可达到超低(约10~(-3)mN/m数量级),能够满足大庆油田复合驱用表面活性剂使油-水界面张力达到超低的要求。研究结果还表明,聚合物的加入有利于原油-表面活性剂体系间超低界面张力的形成。     

IP多媒体子系统在线计费费率功能模块的设计与实现

在3G IMS系统中,在线实时计费是非常重要的一种计费单元,而费率功能模块是该计费系统的核心.由于3G IMS计费系统处理的是多种复杂应用与服务混合的计费内容,所以对费率功能模块的设计与实现提出了较高的要求,并成为当前的研究热点之一.在分析IMS在线计费系统的基础之上,对复杂应用和服务进行了研究,提出了费率功能模块的针...     

福建电信天翼预付费业务综述

本文主要介绍了基于福建电信的移动智能网平台上开发的针对C网手机的实时预付费智能业务的功能特点,以及涉及的关键技术和相关协议。     

OBS光网络技术及最新进展

光纤传输技术和光网络技术的发展使得光网络成为现代高速宽带网络的基础骨干网。光突发交换是一种介于光路交换和光分组交换之间的很有发展潜力的交换模式,它结合了两者的优势又克服了两者的缺点。重点阐述了光突发交换的概念和关键技术,并介绍了光突发交换目前的研究进展。     

企业统一通讯平台核心技术研究

统一通讯（简称UC即Unified Communications）是指把计算机技术与传统通讯技术融为一体的新通讯模式,作为一种解决方案和应用,其核心内容是：让人们无论任何时间、任何地点,都可以通过任何设备、任何网络,获得数据、图像和声音的自由通讯。     

Synthesis and characterization of novel citric acid-based polyester elastomers

In this paper we report successful simple synthesis of unique elastic polyesters by carrying out catalyst-free polyesterification of multifunctional non-toxic monomers: 1,8-octanediol (OD), citric acid (CA) and sebacic acid (SA). The chemical, physical, and surface chemical properties of the resulting copolyester polyoctanediol citrate/sebacate [p(OCS)] have been investigated. This new material was characterized by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-ToF-MS), nuclear magnetic resonance spectroscopy (NMR), thermal analysis (TA), mechanical tests, photo-acoustic Fourier-transform infrared spectroscopy (PA-FTIR), X-ray photoelectron spectroscopy (XPS) and swelling experiments. We demonstrate that the chemical structure, morphology, physical integrity and surface chemistry of the synthesized co-polymer can be controlled by simply varying the initial acid concentration (CA/SA) in the pre-polymer. This novel p(OCS) polymer exhibits versatility in mechanical properties, hydration and hydrolytic degradation as determined by the chemical structure of the polyester elastomer.