网络防火墙技术应用分析

介绍了防火墙的概念、组成原理及几种典型的防火墙系统,对如何加强防火墙的防护作用进行了分析。     

Estimator Choice and Fisher's Paradox: A Monte Carlo Study

This paper argues that Fisher's paradox can be explained away in terms of estimator choice. We analyse by means of Monte Carlo experiments the small sample properties of a large set of estimators (including virtually all available single-equation estimators), and compute the critical values based on the empirical distributions of the t-statistics, for a variety of Data Generation Processes (DGPs), allowing for structural breaks, ARCH effects etc. We show that precisely the estimators most commonly used in the literature, namely OLS, Dynamic OLS (DOLS) and non-prewhitened FMLS, have the worst performance in small samples, and produce rejections of the Fisher hypothesis. If one employs the estimators with the most desirable properties (i.e., the smallest downward bias and the minimum shift in the distribution of the associated t-statistics), or if one uses the empirical critical values, the evidence based on US data is strongly supportive of the Fisher relation, consistently with many theoretical models.     

知识经济背景下高等教育改革

知识经济是以知识为基础,以科技为核心,以人力资源为依托,建立在知识的生产、创新、流通、分配和应用上的经济模式,同时又是信息化、网络化、创新化和智力化的新型经济形态.知识经济作为一个新经济形态,为高等教育提供了广阔的发展空间,知识经济的发展依赖于教育的发展.我们要注重教育方式的变革,提高学生对知识创新能力的培养,使学生具有独立获取知识的能力,具有开拓精神,使我们的高等教育培养出千千万万知识经济时代需要的高级人才.     

网络环境下图书馆信息服务创新初探

信息资源网络化给图书馆的生存和发展带来了巨大的冲击,图书馆惟有创新才有出路。本文提出转变观念是信息服务创新的前提;加强网络信息资源的开发利用是信息服务创新的基础;技术创新是信息服务创新的手段;高素质的图书馆员是信息服务创新的关键。     

日本都道府县防灾无线网的建设及借鉴

日本是世界上灾害管理通信系统建设领先的国家,相关经验对我国灾害管理通信系统的建设有着重要的借鉴意义。都道府县防灾无线网是日本灾害管理通信系统的重要组成部分,已具备了较为成熟的建设模式和应用经验。本文介绍了日本灾害管理通信系统的框架、都道府县防灾无线网的体系架构及其通信系统组成,选择了神奈川县、长野县和三重县作为典型案例,对这三个县的防灾无线网的建设和应用情况作了分析,并借鉴日本的经验,结合我国的实际,提出了五个方面的建设建议。     

Efe fathers: one among many? A comparison of forager children's involvement with fathers and other males

The study reported describes Efe (pygmy) forager one-, two-, and three-year-olds' involvement with males. The Efe of northeastern Zaïre were chosen because their social organization allows us to examine hypotheses based on studies in Western, technologically complex societies about the distinctive role fathers play in the lives of their young children. Behavioral observations of Efe children's day-to-day activities with fathers, men and boys were recorded using a focal subject sampling technique (Altmann, 1974). Two behavioral measures were created to capture the extent to which males were involved with children: Social engagement describes males' involvement with children and social attention describes eavesdropping by children on males' everyday activities. Eight one-year-olds, 7 two-year-olds and 8 three-year-olds were each observed for six, one-hour observation sessions that were distributed evenly over the daylight hours. Data were analyzed using the traditional measure of involvement (e.g., adult males) and using a newly developed measure of the involvement of the average individual (e.g., average adult mate). Comparisons at each of the ages showed that fathers were consistently like other men in the extent to which children participated in social activities with them and watched their activities. Only fathers' level of social engagement declined significantly as children grew older. Boys' role relative to other males became increasingly distinctive as children aged. The findings suggest that Efe fathers may not be unique in the same sense assumed by Western study ideals, and raise questions about the special status given to fathers in Western theory and data. The patterning of mate involvement with children is discussed in terms of Efe community life, and in terms of Efe children's developing understanding of their relationship with fathers and other males.     

具体应用中的矛盾分析法之种种

矛盾分析法在科学认识中的具体应用,可作多侧面的展开,形成多方面的更为具体的科学方法。这些具体科学方法可概括为,矛盾的定性分析法、矛盾的定位分析法、矛盾的定点分析法、矛盾的定量分析法、矛盾的定势分析法、矛盾的历史过程分析法、矛盾的逻辑过程分析法、矛盾的系统分析法、矛盾的对立面互补分析法等等.它们均体现哲学方法与具体科学方法的一致性。     

A study of simulated annealing and a revised cascade algorithm for image reconstruction

We describe an image reconstruction problem and the computational difficulties arising in determining the maximum a posteriori (MAP) estimate. Two algorithms for tackling the problem, iterated conditional modes (ICM) and simulated annealing, are usually applied pixel by pixel. The performance of this strategy can be poor, particularly for heavily degraded images, and as a potential improvement Jubb and Jennison (1991) suggest the cascade algorithm in which ICM is initially applied to coarser images formed by blocking squares of pixels. In this paper we attempt to resolve certain criticisms of cascade and present a version of the algorithm extended in definition and implementation. As an illustration we apply our new method to a synthetic aperture radar (SAR) image. We also carry out a study of simulated annealing, with and without cascade, applied to a more tractable minimization problem from which we gain insight into the properties of cascade algorithms.     

光纤扭转对循环延迟线偏振控制系统特性影响的研究

借助模式耦合理论和矩阵光学的知识,对引入光纤扭转机构后的延迟线偏振控制系统的偏振转换特性进行了分析,推导出了描述该系统偏振特性的琼斯矩阵,得到了光纤扭转对系统偏振特性影响的理论模型。     

分析Chiral分层媒质特性的一般方法(英文)

提出了一套系统方法用于求解任意导体片位于界面的Chiral分层媒质的谐振频率,衰减因子和电磁场分布。文中的分析是在Fourier变换域的并矢格林函数和矩阵分析的基础上来进行的,给出的公式的最大价值在于它提供了求解Chiral分层媒质问题的方法论。