舰船电力系统继电保护现状与发展趋势

舰船电力系统使命的特殊性及系统配置的独特性,使其继电保护方式不同于一般的陆地电力系统.在全面分析舰船电力系统保护特点的基础上,介绍了传统继电保护策略及其保护装置的动作特性,比较了国内外保护方案的差异,并结合近年来的新技术指出了舰船电力系统继电保护的发展方向.     

Hierarchical Non-linear Image Registration Integrating Deformable Segmentation

IntroductionSegmentation and registration are two impor-tant problems in the field of medical image analy-sis. Traditionally, solutions have been developedfor each of these two problems in relative isolationfrom the other, but with increasing dependence onthe existence of a solution for the other. For exam-ple, model-based segmentation methods[1,2]need toregister individual data sets to a common frame ofreference, so that statistics about the models canbe gathered to guide the evolution of the…     

平行导线磁场对点阵式霍尔电流传感器测量准确度的影响分析

针对研制的点阵式霍尔电流传感器工程应用中的抗干扰能力及安装要求问题,基于点阵式霍尔电流传感器模型和应用环境,建立平行导线磁场对霍尔电流传感器测量准确度影响的计算模型,提出该情况下传感器测量准确度的计算方法,发现传感器测量准确度与点阵个数、点阵半径、干扰源电缆与被测电缆的距离、干扰源电流与被测电流之比值大小有关。理论计算和实验结果都显示了算法的正确性和实用性,该算法对传感器的设计及安装具有指导意义。     

In-home power line communication media access control protocol based on collision resolution

Most existing media access control (MAC) protocols in power line communication (PLC) networks just discard the colliding data packets when collision occurs. The collision deteriorates throughput and delay performance of system under high traffic conditions. This article presents a novel media access scheme with fast collision resolution for in-home power line networks. It works by first recognizing the colliding stations through detecting the inserted unique ID sequence ahead of data packets, then the source nodes retransmitting their packets immediately after the collision slot. The proposed protocol maintains the benefits of ALOHA systems. It needs no scheduling overhead and is suitable for bursty sources, such as multimedia data packets. Computer simulations have demonstrated that this approach can achieve high throughput due to its ability of resolving collisions.     

45钢冷形变后预多边化处理的研究

本文用电镜观察、拉伸试验、硬度试验、差热分析等方法研究了45钢冷形变后的预多边化处理对随后的回复、再结品过程的影响.结果表明,预多边化处理可推迟回复进程,促进再结晶的进行.最后还探讨了预多边化处理对冷形变强化效果遗传性的影响.     

4Cr14Ni14W2Mo气阀钢不同原始状态对固溶处理所得组织的影响

本文探讨了4Cr14Ni14W2Mo 气阀钢三种原始状态对不同温度固溶处理所得组织(晶粒度、碳化物)的影响。研究表明,低温(1050℃)锻造后,固溶处理时不可能获得合理的组织(3—2级奥氏体晶粒,碳化物全溶于基体);高温(1240℃)锻造后,在1180℃固溶处理时,奥氏体晶粒为(3—2)级,碳化物基本全溶于基体。     

复合桩基础在航道护岸工程中的应用

由于复合桩基础的经济性,近年来受到越来越多的关注,但在航道护岸工程中应用较少,究其原因是航道护岸低桩承台复合桩基础受力更加复杂、技术上较难把握。通过分析航道护岸低桩承台复合桩基础竖向承载力和水平承载力,提出了复合桩基础设计控制原则:1)竖向整体安全度K≥2,地基承载力利用率ψ≥0.5。2)桩土联合承担水平力。制定了航道护岸复合桩基础的设计方法及流程,为类似工程提供参考。     

弹性车轮非线性有限元分析及疲劳强度校核

采用ABAQUS软件建立橡胶的mooney-rivlin本构模型以及整个弹性车轮的有限元模型,对弹性车轮在运营过程各工况下的应力情况和疲劳强度进行分析、校核,结果表明,各部件在运营组合工况下危险界面点均落在Goodman曲线内,且裕量充足,这种采用块状橡胶结构的弹性车轮结构设计合理,满足轻轨车辆的使用要求。     

高速铁路无砟轨道区段路基上拱整治技术

高速铁路桥涵过渡段路基上拱造成无砟轨道高程异常,超出扣件调整范围,成为高速铁路运营维护的一大难题。为恢复上拱段无砟轨道结构的稳定性、平顺性和线路允许速度,开展了路基上拱整治技术研究,提出合理整治措施,并予以实施。通过安装分层自动监测系统和钻芯取样,分析上拱原因。采用切割、减薄支承层、注浆植筋、落道整治等措施解决了无砟轨道高程超限问题。并制定了防排水措施。上述探索初步给出了一套完善、切实可行的高速铁路无砟轨道区段路基上拱整治技术和方法。     

A Novel Method for Character Segmentation in Natural Scenes

Introduction Nowadays the applications of scene text recog-nition are rapidly expanding with the developmentof portable digital imaging devices[1]. However,character extraction from scene images has alwaysbeen a challenging problem due to complex back-ground, uneven illumination, shadows and noise ofimages[2]. Besides, languages also impose anotherlevel of variation in text. Characters in such lan-guages as Chinese, Japanese and Korean are usual-ly composed of several strokes, which do not n…