基于动量算法的常数模新算法

针对传统常数模算法收敛速度慢的缺点，提出了一种基于动量算法的常数模算法。该算法的权向量更新公式中添加了动量因子，以提高收敛速度。利用水声信道对算法的性能进行仿真研究，仿真结果表明：与常数模算法相比，该算法能较快收敛。     

Leveraging Sunken Investments in Communications Infrastructure: A Policy Perspective From the United States

Bridging the digital divide between information and technology haves and have-nots has waned from the top of the national policy agenda in the United States during a time in which the sunken investments of the 1990s need to be leveraged. A national information network now exists yet this infrastructure--largely hardware--needs to be continually modernized and parlayed with commitments to building human capacity, developing relevant content, and scaling socially beneficial technology applications, such as telemedicine, in order to optimize these initial multi-billion-dollar outlays. This article makes the case that sidestepping public-private initiatives aimed at accelerating digital opportunity is imprudent, given the mounting empirical evidence highlighting the payoffs of information and communications technologies, when properly integrated and applied, especially in enhancing the life chances of underserved Americans. Policy next steps should advance the goals of expanding universal service initiatives, including hastening broadband deployment to homes and learning institutions, and deepening programs which leverage the utility of the existing infrastructure, such as expanding human-capital development, producing relevant content, and innovating socially beneficial technology applications.     

Contests for cooperation—A new approach in German innovation policy

A new approach in German innovation policy organizes contests of proposals for developing innovation networks. Based on an overview of the different programs, we investigate the advantages and problems of such an approach. We find that this type of policy may have a relatively large impact and can, therefore, be regarded as a rather efficient instrument of innovation policy. Compared to conventional policies, administration of the program is a much more critical issue. The contest approach may stimulate learning effects on the side of the administration but may also require a high degree of flexibility. The main disadvantage is the additional time that is required for conducting the contest. As a distinct ‘picking the winner’ approach, the contest approach is not suited as a means for achieving a leveling-out of regional welfare.     

赫斯特指数的分析与应用

基于重标极差(R／S)分析基础上的赫斯特指数(H)是用来描述和标度传统的有效市场假说(EMH)是否成立的一个指标，本文以我国深圳成分指数为研究对象，通过对深成指的赫斯特指数的研究，结果表明该股票指数遵循有偏的随机游走(分形布朗运动)而非传统的随机游走模式。     

R.H.托尼教育改革活动初探

作为20世纪上半叶英国著名的教育改革家,R.H.托尼对当时英国的教育改革做出了巨大的贡献:一方面,通过为工人教育委员会创办研究班和一战后对该协会的领导,他在改善英国工人阶级命运的事业中进行了有益的探索;另一方面,他还扮演了工党和政府教育政策制定人的角色,帮助它们起草了许多意义重大的报告和法案,为全民教育在英国的实现打下了坚实的基础。     

过热液体R134a中活塞效应的数值模拟

针对一维密闭腔体中过热液体R134a的传热过程建立数学模型,并进行数值模拟研究。对计算区域左边界进行阶跃温差为1 K的等温加热,通过求解可压缩流体控制方程组,成功捕捉到流体内部存在的活塞效应,计算出其当量热导率,并分析过热程度对活塞效应的影响规律。结果表明：过热液体R134a中活塞效应当量热导率显著高于工质自身热导率,利用活塞效应可传递更高的热流密度,并实现更高的传热速率。     

利用D2R实现关系数据库与关联数据的语义模式映射

关系型数据库和关联数据的概念模型都基于现实世界的实体、属性及其关系而构建,具备建立映射和实现转换的可能性。两者语义模式映射的重点是关联关系的构建与表达。开源软件D2R的映射语言,通过核心要素ClassMap、PropertyBridge及其属性,支持关系数据库的SQL实现,支持将关系数据库不同实体之间、同一实体内部及与外部数据的关联关系构建为RDF链接。     

Accessibility of U.S. federal government home pages: Section 508 compliance and site accessibility statements

U.S. federal websites are required to be accessible for people with impairments. However, despite the existing regulations and guidelines, many federal websites continue to be inaccessible, and accessibility policy statements available on federal websites often do not provide any useful information. This paper provides three contributions to the research literature: (1) an accessibility evaluation of 100 federal home pages using both human and automated methods, (2) a content analysis of existing website accessibility policy statements, and (3) a discussion of the relationship between actual Section 508 compliance and the existing accessibility policy statements on a website. The paper concludes with recommendations for improving policy related to Section 508 compliance for websites.