条件接收系统中解扰器的设计与实现

介绍数字视频广播（Digital Video Broadcasting，DVB）条件接收系统的系统结构，详细分析了条件接收系统的工作原理，并给出条件接收系统的解扰器工作流程及实现方案。     

对客户端主动认证的条件接收系统的探讨

探讨一种基于客户端主动认证的条件接收系统。系统可以降低CA系统的处理负荷，提高网络带宽利用率，增大系统容量，同时可以支持多种业务。首先简要介绍现有条件接收系统，并指出其弊端，然后对基于客户端主动认证的条件接收系统及其关键技术进行论证，最后对系统的性能作简要分析。     

基于UDP/IP单向数据广播的加扰认证解决方案

条件接收系统是实施收费数据广播业务平台中的重要组成部分，为了实现基于DVB单向传输网络下的条件接收系统中授权问题，提出引入智能密码钥匙（USBkey）作为单向数据传输的终端用户身份认证及权限接收工具，提供一种采用对称密码体制和非对称密码体制结合安全认证方案，以实现单向传输过程中的高安全性和实时性需要。该方案在央视数据广播的条件接收系统中得以成功的实施。     

DVB通用接口的关键技术及实现方法

本文首先介绍了DVB条件接收系统的发展现状以及基本原理，然后针对机卡分离的DVB—CI通用接口技术和通用接口协议栈作了详细的阐述，对其接口从应用层到底层的协议特性和功能进行了分析和研究，并提出了通用接口的软件设计方法，实现数字电视条件接收功能，指明了DVB通用接口在条件接收系统中的作用重要性和广阔的应用前景。     

基于双重分组的密钥分配算法

实现数字电视授权管理的关键是条件接收，而条件接收的核心环节则是密钥的分配算法。本文在单一分组算法的基础上，提出了基于节目分组和用户分组的双重分组算法。与无分组或单一分组算法相比，该方案能够减少密钥传输的带宽消耗；而且，当单个用户加入或者退出授权时，只需要处理该用户的小组密钥而不影响其他小组，从而降低了系统开销，提高了系统灵活性。     

可下载条件接收系统安全性协议综述

可下载条件接收系统(DCAS)是一种双向认证授权体系,条件接收(CA)算法和密钥可以动态下载.随着互联网和数字电视为代表的数字化内容越来越丰富,条件接收系统(CAS)不断向可下载的条件接收系统(DCAS)转变已是大势所趋.本文回顾总结了主要的DCAS技术发展并对中国的DCAS发展趋势进行了展望.     

一种密钥分配方案在PPV条件接收系统中的应用

条件接收是实现PPV业务的重要技术，而其中的密钥分发效率和安全性又是影响条件接收系统性能的关键因素。文章在基于四层密钥分配方案的基础上，提出了平衡树分层模型及相应密钥分发方法，该方法具有最优的密钥分发效率。     

SOPCA 条件接收系统的设计与应用

数字电视条件接收系统是广泛电视信息安全的关键环节，目前国内实用的系统均为国外公司的产品，不利于国家信息安全的管理。在现有DVB（Digital Video Broadcasting)标准的基础上，提出了SOPCA （Software Platform of Connecting Appliance)条件接收系统，实现了节目传输流加扰、节目管理、用户管理、分层加密机制和IC卡控制等关键技术，完成了在自主知识产权的SOPCA嵌入式操作系统和硬件平台上的原型机应用。经过总体结构和具体性能的综合分析比较，在功能上优于其它同类系统，最后对系统功能的进一步完善进行了探讨。     

CA条件接受系统

详细论述了CA条件接受系统的原理以及关键技术，并针对实际情况给出了在数字电视系统中条件接收的实现方法。     

DVB-C条件接收系统中基于公共接口技术的机卡分离的设计与实现

本文首先介绍有线数字广播电视(DVB-C)条件接收系统的原理和相关标准，以及实现条件接收相关技术特点。然后，从运营商、用户和机项盒制造商以及CA厂家的角度出发，实现技术的选择性和竞争性，采用公共接口技术，给出了一种机卡分离方案的设计与实现。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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