Probabilistic analysis on mesh network fault tolerance

Mesh networks are among the most important interconnection network topologies for large multicomputer systems. Mesh networks perform poorly in tolerating faults in the view of worst-case analysis. On the other hand, such worst cases occur very rarely in realistic situations. In this paper, we study the fault tolerance of 2-D and 3-D mesh networks under a more realistic model in which each network node has an independent failure probability. We first observe that if the node failure probability is fixed, then the connectivity probability of these mesh networks can be arbitrarily small when the network size is sufficiently large. Thus, it is practically important for multicomputer system manufacture to determine the upper bound for node failure probability when the probability of network connectivity and the network size are given. We develop a novel technique to formally derive lower bounds on the connectivity probability for 2-D and 3-D mesh networks. Our study shows that these mesh networks of practical size can tolerate a large number of faulty nodes thus are reliable enough for multicomputer systems. For example, it is formally proved that as long as the node failure probability is bounded by 0.5%$0.5\%$, a 3-D mesh network of up to a million nodes remains connected with a probability larger than 99%$99\%$.     

A Dialectal Chinese Speech Recognition Framework

A framework for dialectal Chinese speech recognition is proposed and studied, in which a relatively small dialectal Chinese (or in other words Chinese influenced by the native dialect) speech corpus and dialect-related knowledge are adopted to transform a standard Chinese (or Putonghua, abbreviated as PTH) speech recognizer into a dialectal Chinese speech recognizer. Two kinds of knowledge sources are explored: one is expert knowledge and the other is a small dialectal Chinese corpus. These knowledge sources provide information at four levels: phonetic level, lexicon level, language level, and acoustic decoder level. This paper takes Wu dialectal Chinese (WDC) as an example target language. The goal is to establish a WDC speech recognizer from an existing PTH speech recognizer based on the Initial-Final structure of the Chinese language and a study of how dialectal Chinese speakers speak Putonghua. The authors propose to use context-independent PTH-IF mappings (where IF means either a Chinese Initial or a Chinese Final), context-independent WDC-IF mappings, and syllable-dependent WDC-IF mappings (obtained from either experts or data), and combine them with the supervised maximum likelihood linear regression (MLLR) acoustic model adaptation method. To reduce the size of the multi-pronunciation lexicon introduced by the IF mappings, which might also enlarge the lexicon confusion and hence lead to the performance degradation, a Multi-Pronunciation Expansion (MPE) method based on the accumulated uni-gram probability (AUP) is proposed. In addition, some commonly used WDC words are selected and added to the lexicon. Compared with the original PTH speech recognizer, the resulting WDC speech recognizer achieves 10-18% absolute Character Error Rate (CER) reduction when recognizing WDC, with only a 0.62% CER increase when recognizing PTH. The proposed framework and methods are expected to work not only for Wu dialectal Chinese but also for other dialectal Chinese languages and even other languages.     

一种J2EE服务器端软件测试用例的复用框架研究

JZEE框架实现了多层次的应用程序体系结构,同时也提出了多层次应用程序测试的需要．如何在服务器端多种容器环境内的测试中实现测试用例的复用成为影响测试效率的关键因素．本文通过分析测试JDBC标准符合性的工具CTS,研究了实现服年器端多种容器环境测试用例复用的基表框架．该框架在增加简单的环境辅助类基础上,利用面向对象的继承机制和Java语言的反射机制,实现了多种容器内测试时测试用例复用．经过扩展测试用例,该工具已成功应用于国家863项目数据库标准符合性测试．     

网络光盘库模型的建立和分析*

网络存储技术的广泛应用为近线存储设备应用于海量存储系统提供了新思路,而网络光盘库正是一种利用网络存储技术的新的存储方式。研究了可以通过IP网络接入海量存储系统中的网络光盘库的排队网络模型,并对其进行了仿真模拟,为光盘库在海量存储系统中的应用、设计和性能优化提供理论方法和实验依据。     

基于IP 网络的移动技术研究综述*

介绍了目前主要的几种移动技术在网络层、传输层和会话层上的实现, 如Mobile IP 、基于组播的移动技术、基于代理的MSOCKS 传输层移动方案、MIGRATE 移动技术等, 分析了它们主要的技术特性, 比较了它们的优缺点, 并总结了移动技术的发展趋势。     

基于自然语言的检索方法在图案数据库中的应用研究*

基于自然语言的检索方法已经应用到许多数据库系统中。根据图案数据库的特点,提出了一个基于自然语言的检索模型,论述了怎样将自然语言转换成查询语句（SQL语句）需要注意的一系列问题。     

可穿戴计算机无线显示系统

分析了目前流行的基于网络的各种远程显示控制技术,总结其实现远程显示控制的方法以及提高带宽利用率的策略,并针对不同技术的特点进行了比较。提出一种适用于可穿戴计算机的无线显示设计方案,采用软硬件结合的方法解决穿戴式计算机无线显示问题,最后提出了需要进一步研究解决的问题。     

Direct manipulation of FFD: efficient explicit solutions and decomposible multiple point constraints

Published online: 25 July 2001     

两级交互式多模型算法

在混合估计中,交互式多模型滤波器(IMM--Interacting Multiple Model)以其优越 的性能而受到广泛的研究.由于马尔可夫参数的限定,交互式多模型在模型数较多时会出现精 度下降,从而限制了它在高维参数空间建模的有效性.利用模型集的概念,首次提出了双马氏 过程的模型切换假设,从而构造出一种两级交互式多模型滤波器.通过辨识系统噪声的多个统 计参数比较了两级交互式多模型滤波器与常规交互式多模型滤波器.结果表明:对于大信噪比 信源(即小的量测噪声),两级交互式多模型滤波器与常规交互式多模型滤波器性能基本相当; 而对于小信噪比信源(即大的量测噪声),两级交互式多模型滤波器明显优于常规交互式多模型 滤波器.