交流传动电力机车网侧谐波分析与对策

就交流传动电力机车网侧谐波进行了较为详细的分析,根据不同系统的特点及其影响提出应采取的措施和建议,为电力机车总体及其主电路重大部件的设计,以及供电系统相关参数的选择,提供了参考。     

IGBT模块中续流二极管关断过程失效机理分析

鉴于IGBT模块中的续流二极管在关断过程中会发生瞬变,文章从二极管的设计准则出发,研究续流二极管发生失效的机理,并结合一个IGBT模块中二极管失效的具体案例进行分析,给出了二极管失效的几种原因,并提出了避免其失效的几种方法。     

Optimal Genetic View Selection Algorithm for Data Warehouse

To efficiently solve the materialized view selection problem, an optimal genetic algorithm of how to select a set of views to be materialized is proposed so as to achieve both good query performance and low view maintenance cost under a storage space constraint. First, a pre-processing algorithm based on the maximum benefit per unit space is used to generate initial solutions. Then, the initial solutions are improved by the genetic algorithm having the mixture of optimal strategies. Furthermore, the generated infeasible solutions during the evolution process are repaired by loss function. The experimental results show that the proposed algorithm outperforms the heuristic algorithm and canonical genetic algorithm in finding optimal solutions.     

RESEARCH ON REUSE-BASED WEB SERVICES COMPOSITION

Softwarereuseisalwaysanimportantissueto researchforimprovingtheproductivityofsoftware developmentinsoftwareengineeringfield.Free man[1]dividedthesoftwaredevelopmentprocessin to"developmentforreuse"and"developmentwith reuse",whichconsideredsoftwarereusew…     

REAL-TIME LICENSING MANAGEMENT OF SECURE MULTIMEDIA CONTENT DELIVERY

Media Commerce is now becoming a new trend which results from faster development of network bandwidth and high availability of multimedia technologies, how to protect media content from being used in a rightviolated way is one of most important issues to take into account. In this paper, a novel and efficient authorization and authentication Digital Rights Management (DRM) schema is proposed firstly for secure multimedia delivery, then based on the schema, a real-time digital signature algorithm built on Elliptic Curve Cryptography (ECC) is adopted for fast authentication and verification of licensing management, thus secure multimedia delivery via TCP/RTP can efficiently work with real-time transaction response and high Quality of Service (QoS) . Performance evaluations manifest the proposed schema is secure, available for real-time media stream authentication and authorization without much effected of QoS. The proposed schema is not only available for Client/Server media service but can be easily extended to P2P and broadcasting network for trusted rights management.     

高压储能电容器直流局部放电检测仪的研制

为了评估高压储能电容器的性能，基于RLC平衡检测阻抗法和血（相邻放电脉冲时间间隔）分析法，研制了高压储能电容器直流局部放电检测仪．该仪器主要由具有良好抗干扰能力的60—250kHz检测硬件和能进行数据处理与统计分析的局部放电分析软件组成．对含有内部、接触、重叠典型缺陷的高压储能电容器模型进行了直流局部放电测试，△t分布及放电量谱图表明，该检测仪能较好地检测出有缺陷的电容器局部放电产生的原因及其绝缘状态．     

驾驶员如何保护颈腰脊椎？

驾驶员在开车时，眼睛长时间盯牢前方、脖子挺直，容易导致颈部肌肉痉挛。而坐姿腰部所承受压力是站立姿势的两倍，长期久坐就会使腰部的腰椎关节和肌肉以及韧带造成粘连，引起腰肌劳损等症。保护颈椎与腰部的肌肉是竖脊肌，将竖脊肌锻炼强大是改善腰部力量的根本。竖脊肌锻炼的目标就是让后背肌肉群变得强壮有力。     

《设备状态监测与故障诊断》课程教学研究

对<设备状态监测与故障诊断>课程教学内容及教学方法进行了探讨,基于教学中存在的问题,提出并强调要加强教材建设、实验教学、利用多媒体教学、双语教学、交互式教学以及培养学生利用网络资源进行自学的能力来引导学生主动思考等多个教学要点.     

探路国有企业混合所有制经济改革

发展混合所有制经济是一个时代的呼喊,在其背后是改革与转型的历史性命题。混合所有制更是被视为国企改革的突破口和试金石,牵动着国企、民企等各方面敏感的神经。     

2018年度长江上游航道维护性疏浚工程后评价

系统评估2018年长江上游航道维护性疏浚工程实施效果,为今后航道维护工程提供技术参考。基于年度水情及航道疏浚滩段分布情况,分析维护性疏浚方案设计、施工时机和频次、施工过程的动态管理及航道可持续性等。结果显示,2018年长江上游干线航道维护性疏浚工程总体效果良好,滩段选择及疏浚方案设计与河道演变规律基本适应;疏浚时机及频次基本合理,最大程度地缓解了与通航的矛盾;但由于维护性疏浚未大幅改变河道水流特性和河床边界,因此天然河段浅滩航道可持续性较差,仍需加强观测,必要时采取其他整治措施。