A new algorithm for the extraction of the surface waves for the Green''''s function in layered dielectrics

There exist the complicated waveguide modes as well as the surface waves in the electromagnetic field induced by a horizontal electric dipole in layered lossless dielectrics between two ground planes. In spectral domain, all these modes can be characterized by the rational parts with the real poles of the vector and scalar potentials. The accurate extraction of these modes plays an important role in the evaluation of the Green's function in spatial domain. In this paper, a new algorithm based on rational approximation is presented, which can accurately extract all the real poles and the residues of each pole simultaneously. Thus, we can get all the surface wave modes and waveguide modes, which is of great help to the calculation of the spatial domain Green's function. The numerical results demonstrated the accuracy and efficiency of the proposed method.     

EH—GRBAC：遍在计算环境中基于知识的访问控制原型

In pervasive computing environment, users can access to various information, resources and services at anytime and anywhere, so access control has become an exigent security problem. In the traditional access control modes, the decisions o[ access control are entirely dependent on the results of authentication. The access control can-not provide the security-relevant fault-tolerant function. But in pervasive computing environment, because of the var-ious reasons, security system can't assure the results of the authentication are absolutely correct. So we propose touse the knowledge-based access control, which can discovery some rules and knowledge from the previous process ofaccess control and combine these rules with traditional access controls to perfect the security system. The essence ofknowledge-based access control is to add some intelligent authentication function into the process of access control. In the paper, we expatiate the idea and principle of knowledge-based access control, as well as the advances of this method. Furthermore, we implement a prototype, called EH-GRBAC, which can discovery historical knowledge from the history of users' using resources to reinforce GRBAC. In the paper, we also explain the architecture and the details of EH_GRBAC.     

On 2-Site Voronoi Diagrams Under Geometric Distance Functions

We revisit a new type of Voronoi diagram, in which distance is measured from a point to a pair of points. We consider a few more such distance functions, based on geometric primitives, namely, circles and triangles, and analyze the structure and complexity of the nearest- and furthest-neighbor 2-site Voronoi diagrams of a point set in the plane with respect to these distance functions. In addition, we bring to notice that 2-point site Voronoi diagrams can be alternatively interpreted as 1-site Voronoi diagrams of segments, and thus, our results also enhance the knowledge on the latter.     

Design and Implementation of a Concurrency Control Mechanism in an Object-Oriented Database System

This paper presents a practical concurrency control mechanism-Object-Locking in OODBMS.Object-Locking can schedule transactions,each of them can be considered as a sequence of high level operations defined on classes.By the properties of parallelity and commutativity between high level operations,proper lock modes for each operation are designed and the compatibility matrix is constructed.Wiht these lock modes,phantoms are kept away from databases and a high degree of concurrency is achieved.     

Huge Page Friendly Virtualized Memory Management

With the rapid increase of memory consumption by applications running on cloud data centers,we need more efficient memory management in a virtualized environment.Exploiting huge pages becomes more critical for a virtual machine's performance when it runs large working set size programs.Programs with large working set sizes are more sensitive to memory allocation,which requires us to quickly adjust the virtual machine's memory to accommodate memory phase changes.It would be much more efficient if we could adjust virtual machines'memory at the granularity of huge pages.However,existing virtual machine memory reallocation techniques,such as ballooning,do not support huge pages.In addition,in order to drive effective memory reallocation,we need to predict the actual memory demand of a virtual machine.We find that traditional memory demand estimation methods designed for regular pages cannot be simply ported to a system adopting huge pages.How to adjust the memory of virtual machines timely and effectively according to the periodic change of memory demand is another challenge we face.This paper proposes a dynamic huge page based memory balancing system(HPMBS)for efficient memory management in a virtualized environment.We first rebuild the ballooning mechanism in order to dispatch memory in the granularity of huge pages.We then design and implement a huge page working set size estimation mechanism which can accurately estimate a virtual machine's memory demand in huge pages environments.Combining these two mechanisms,we finally use an algorithm based on dynamic programming to achieve dynamic memory balancing.Experiments show that our system saves memory and improves overall system performance with low overhead.     

Web Block Extraction System Based on Client-Side Imaging for Clickable Image Map

We propose a new Web information extraction system. The outline of the system and the algorithm to extract information are explained in this paper. A typical Web page consists of multiple elements with different functionalities, such as main content, navigation panels, copyright and privacy notices and advertisements. Visitors to Web pages need only a little of the pages. A system to extract a piece of Web pages is needed, our system enables users to extract Web blocks only by setting clipping areas with their mouse. Web blocks are clickable image maps. Imaging and detecting hyperlink areas on client-side are used to generate image maps. The specialty of our system is that Web blocks perfect layouts and hyperlinks on the original Web pages. Users can access and manage their Web blocks via Evernote, which is a cloud storage system. And HTML snippets for Web blocks enable users to easily reuse Web contents on their own Web site.     

Output digitization of simple measure‑preserving linear systems

We examine three simple linear systems from the viewpoint of ergodic theory. We digitize the output and record only the sign of the output at integer times. We show that even with this minimal output we can recover important information about the systems. In particular, for a two-dimensional system viewed as a flow on the circle, we can determine the rate of rotation. We then use these results to determine the slope of the trajectories for constant irrational flow on the two-dimensional torus. To achieve this, we randomize the system by partitioning the state space and only recording which partition the state is in at each integer time. We show directly that these systems have entropy zero. Finally, we examine two four-dimensional systems and reduce them to the study of linear flows on the two-dimensional torus.     

Distributed Storage Cluster Design for Remote Mirroring Based on Storage Area Network

With the explosion of information nowadays, applying data storage safety requirements has become a new challenge, especially in high data available cluster environments. With the emergence of Storage Area Networks （SANs）, storage can be network-based and consolidated, and mass data movements via Fiber Channels （FCs） can be of very high speed. Based on these features, this paper introduces a dual-node storage cluster designed for remote mirroring as a concurrent data replication method to protect data during system failures. This design takes full advantage of a SAN system＇s benefits, and it adopts a synchronous protocol to guarantee a fully up-to-date data copy on the remote site. By developing a Linux kernel module to control the I/O flow and by using the technologies of software Logic Unit Number （LUN） masking, background online resynchronization and a self-management daemon, we have achieved a reliable mirroring system with the characteristics of server-free data replication, fault tolerance, online disaster recovery and high performance. In this study, we implemented the design in a remote mirror subsystem built on a software Fiber Channel Storage Area Network （FC-SAN） system.     

Known-key distinguishers on type-1 Feistel scheme and near-collision attacks on its hashing modes

We present some known-key distinguishers for a type-1 Feistel scheme with a permutation as the round function. To be more specific, the 29-round known-key truncated differential distinguishers are given for the 256-bit type-1 Feistel scheme with an SP （substitution-permutation） round function by using the rebound attack, where the S-boxes have perfect differential and linear properties and the linear diffusion layer has a maximum branch number. For two 128-bit versions, the distinguishers can be applied on 25- round structures. Based on these distinguishers, we construct near-collision attacks on these schemes with MMO （Matyas- Meyer-Oseas） and MP （Miyaguchi-Preneel） hashing modes, and propose the 26-round and 22-round near-collision attacks for two 256-bit schemes and two 128-bit schemes, respectively. We apply the near-collision attack on MAME and obtain a 26-round near-collision attack. Using the algebraic degree and some integral properties, we prove the correctness of the 31-round known-key integral distinguisher proposed by Sasaki et al. We show that if the round function is a permutation, the integral distinguisher is suitable for a type-1 Feistel scheme of any size.     

Coverage Modeling and Reliability Analysis Using Multi-state Function

Fault tree analysis is an effective method for predicting the reliability of a system.It gives a pictorial representation and logical framework for analyzing the reliability.Also,it has been used for a long time as an effective method for the quantitative and qualitative analysis of the failure modes of critical systems.In this paper,we propose a new general coverage model (GCM) based on hardware independent faults.Using this model,an effective software tool can be constructed to detect,locate and recover fault from the faulty system.This model can be applied to identify the key component that can cause the failure of the system using failure mode effect analysis (FMEA).     

基于ASP．NET的自定义规则动态页面自动生成系统的设计与实现

介绍在ASP．NET平台下,一些具有一致功能的模块,可在不需要重复编程的情况下,自动生成与这些功能模块对应的动态页面。对于客户端呈现出的各种不同的动态页面,在应用程序中只需一个特别设计的页面对象类,作为生成实际动态页面的应用基类。该基类不但定义了如何生成动态页面,而且能处理客户端用户提交的不同事件处理需求。     

基于网页模糊分类的用户兴趣度分析方法

了解用户的兴趣是电子商务网站实现个性化的基础,该文提出了一种分析用户兴趣度的新方法,该方法首先根据网站主索引页上的超链接将网站上的网页模糊分类,并通过对Web日志的统计,得出各交叉页的模糊度,然后综合考虑用户浏览网页的时间长度、点击网页的次数,利用模糊综合评判得出用户对于各网页分类的兴趣度,再与各网页分类的平均兴趣度水平作对比,从而发现用户的兴趣所在,实验表明该方法是有效的。     

基于网页可达性和访问率的电子超市网站链接结构优化方法

定义了链接可达性和网页可达性的概念．为计算网页可达性，设计了计算到达网页路 径的路径树生成算法(PTSA)．建立了一种极大化网页访问率与可达性之间相关性的网站链接 结构调整的数学模型，并提出将PTSA嵌入禁忌搜索的求解方法．试验结果表明本文的方法可 以帮助网站设计者改进网站的链接结构．     

ASP.NET下利用动态网页技术生成静态HTML页面的方法

介绍了一种在ASP.NET环境下利用动态网页技术生成静态HTML页面的方法.利用这种技术,网站内容管理人员在添加网页时直接利用后台管理发布程序就把页面存放成HTML静态文件,它有生成页面简单、快速的优点.这种技术对于访问量大的网站尤其适用,可以减轻服务器端运行程序和读取数据库的压力,提高了网站的数据存取效率,生成的静态页面也更利于搜索引擎收录.     

Correlation-Based Web Document Clustering for Adaptive Web Interface Design

A great challenge for web site designers is how to ensure users' easy access to important web pages efficiently. In this paper we present a clustering-based approach to address this problem. Our approach to this challenge is to perform efficient and effective correlation analysis based on web logs and construct clusters of web pages to reflect the co-visit behavior of web site users. We present a novel approach for adapting previous clustering algorithms that are designed for databases in the problem domain of web page clustering, and show that our new methods can generate high-quality clusters for very large web logs when previous methods fail. Based on the high-quality clustering results, we then apply the data-mined clustering knowledge to the problem of adapting web interfaces to improve users' performance. We develop an automatic method for web interface adaptation: by introducing index pages that minimize overall user browsing costs. The index pages are aimed at providing short cuts for users to ensure that users get to their objective web pages fast, and we solve a previously open problem of how to determine an optimal number of index pages. We empirically show that our approach performs better than many of the previous algorithms based on experiments on several realistic web log files. Received 25 November 2000 / Revised 15 March 2001 / Accepted in revised form 14 May 2001     

网页关注度的一种计算算法研究

提出了一种简单且高效的网页关注度计算算法。通过对网页关注度的计算,可以在网页展现时满足用户的信息检索需求。该算法针对不同用户的不同需求,可以让相同网页对不同用户体现出不同的关注度。对算法进行了详细描述,给出了算法的Java实现,并用实例对算法进行了验证,结果证明了算法的有效性。     

利用母版页实现网站的快速结构化

如何简洁快速地对网站中的网页实现一致的风格和布局,并集中处理网页通用功能,以节省网页的开发和维护工作量,是网站建设所共同面对的问题。通过对ASP.NET2.0中的一项新技术——母版页的深入研究,分析了它的构成要素,并结合实例介绍了利用它来解决这类问题的基本原理。     

一种基于最大频繁项目集的挖掘事务间关联规则方法

Web事务间关联规则挖掘是通过发现网页之间的关联关系来预测用户的兴趣。提出一种新的事务间关联规则挖掘方法,通过对MAFIA算法改进,得到最大频繁项目集的同时得到对应的共有用户集,通过对事务内到事务间最大频繁项目集的转换,分析不同用户之间的关系,分析用户对网站上不同网页的访问数据,直接发现不同用户之间的关联关系来预测用户的兴趣。该方法经试验证明能够更加全面的预测用户感兴趣的网页,更好地为用户提供个性化服务。     

WWW缓冲挖掘中基于粗糙集的用户模糊兴趣建模

如何有效充分地利用WWW缓冲中的信息，其关键是建立一个合适的用户兴趣模型和构造合适的兴趣挖掘算法。用户的兴趣是一个相对模糊的概念，简单兴趣模型通过（词条，权重）来刻画兴趣，但是它的表示粒度太小，不能贴切地描述用户的兴趣。文中在充分分析WWW缓冲模型的基础上提出了基于粗糙集的用户模糊兴趣概念。利用该方法可以对WWW缓冲中的网页文档和文档集合进行统一建模，这为利用用户历史兴趣信息和进行兴趣匹配提供了便利。     

数据挖掘技术在Web预取中的应用研究

WWW以其多媒体的传输及良好的交互性而倍受青睐,虽然近几年来网络速度得到了很大的提高,但是由于接入Internet的用户数量剧增以及Web服务和网络固有的延迟,使得网络越来越拥护,用户的服务质量得不到很好的保证。为此文中提出了一种智能Web预取技术,它能够加快用户浏览Web页面时获取页面的速度。该技术通过简化的WWW数据模型表示用户浏览器缓冲器中的数据,在此基础上利用数据挖掘技术挖掘用户的兴趣关联规则,存放在兴趣关联知识库中,作为对用户行为进行预测的依据。在用户端,智能代理负责用户兴趣的挖掘及基于兴趣关联知识库的Web预取,从而对用户实现透明的浏览器加速。