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.     

形成性评估在英语专业教学中的运用探索

在当前英语专业教学改革中,改变传统的终结性评价单一评估模式,尝试并实施有效的教学评估模式至关重要.本文试图在英语专业教学中,引入形成性评估机制,在教学效果的评价体系方面进行理论和实践的探索与研究.其目的是在英语专业的教学体系中,形成完善的形成性评估体系建构,从而提高英语专业的教学水平.     

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．     

一汽丰田皇冠智能进入和启动系统(四)

5.结构和工作原理(1)钥匙●钥匙有一个内置收发器。当接收到振荡器提供的钥匙ID代码检查请求信号(约134kHz)后,此收发器将一个ID代码信号(约315MHz)发送给无线门锁接收器。这就使驾驶员拥有钥匙的无线ID代码检查成为可能●通过钥匙取消开关来停止智能进入和启动系统,或钥匙操作     

模块化随堂仿真实验在机械电子工程专业电子类课程教学中的应用

机械电子工程专业旨在培养能在生产一线从事机电产品设计制造、控制开发、应用研究和生产管理等工作的应用型高级专门人才。相比较于形象具体的机械类课程,电子类课程（特别是模拟电子技术）理论知识更加抽象,知识体系更加繁杂,实验学时安排有限,并且目前机电专业本科生电子类课程尚缺乏机械和电子融合元素,使学生难以形成机电一体化的系统思维。因此,有必要提出新的课堂教学方法和手段,变抽象理论为具体实践,增强机电融合元素,以利于机电类专业的学生更好地掌握电子理论知识,形成机电系统性分析思维。     

化学工程与工艺化工生产控制自动化及仪表研究

随着社会经济的快速发展,对化工生产的需求越来越大,生产也越来越智能化、自动化.作为国民经济生产的重要产业,化工的发展离不开人们的生活,为了促进化工的全面发展,生产必须实现全自动化.自动化需求主要体现在仪表和控制水平上,本文主要分析了仪表自动化生产的主要类型化工产品.     

高速公路通信系统的收费与监控应用解析

为了保障高速公路的通信安全,我国建立了高速公路信息通信系统,以便人们在使用公路的过程中进行收费与监控工作.本文以高速公路通信系统的建立为研究对象,着力于收费与监控两项内容,对这一系统如何应用于实践中进行分析与探讨.