Semantics and verification of monitors and systems of monitors and processes

In this paper we present a sound and complete semantics for the monitor concept of C.A.R. Hoare. First a method for specification of monitors, introduced by O.-J. Dahl, is reviewed. This method is based on the relation between the historic sequence of monitor procedure calls and the historic sequence of monitor procedure exits. Based on such specifications and our new monitor semantics we present a method by which it is possible to prove that a concrete monitor is an implementation of an abstract one. In the last part of the paper an axiomatic semantics for systems of concurrent processes and monitors is introduced. The method supports verification by separation of concerns: Properties of the communication to and from each process are proven in isolation by a usual Hoare style axiomatic semantics, while abstract monitors are also specified in isolation by the method reviewed in the first part of the paper. These properties of the components of the system are then used in a new proof rule to conclude properties of the complete system. Stein Gjessing received a Ph.D. (actually a Dr. philos.) from the University of Oslo (Norway) in 1985. Presently he is an Associate Professor at the Institute of informatics, University of Oslo, Norway. Dr. Gjessings research interests are in the area of concurrent and distributed programming, operating systems, formal specification and verification and programming languages.     

Models and Complexity of Problems of Design and Reconstruction of Telecommunication and Transport Systems

This article considers network synthesis problems arising in the design and exploitation of telecommunication and transportation systems. A formalization of network synthesis problems on graphs is proposed in which constraints on cut capacities are given and possibilities of failing some network components are taken into account. Approaches to the solution and analysis of the complexity of the considered problems are described.     

Teamcenter与NX集成客户化定制技术研究与实现

PDM产品实施过程中一项重要工作是系统集成与客户化定制。对Teamcenter Engineering(简称Teamcenter)与NX系统集成客户化定制中业务建模、属性映射等相关技术进行了研究,提出了Teamcenter与NX集成客户化定制的技术思路,并以客户化定制NX工程图纸标题栏为例,介绍了Teamcenter与NX集成定制实现的关键步骤及方法。     

椭圆拉伸变形长短轴的计算及应用

在CAD应用软件程序编制中,椭圆的长短轴是很重要的参数。应用相关数学知识推导出6个计算公式,可利用这些公式确定椭圆沿坐标轴拉伸变形后的长短轴大小与位置并在CAD软件中实现与之相关的功能。     

IPSEC与防火墙协同工作设计与实现

IPSEC提供网络层的安全服务，通过对IP报文的加密和验证，保证数据在传输过程中的安全．由于IPSEC封装了报文中一些重要信息，使得IPSEC与防火墙不能同时有效地工作．本文提出一种分层IPSEC(Layered IP Security，L_IPSEC)思想，即将协议头和数据部分分别进行安全处理．并将这种分层思想与分布式处理技术结合，设计与实现一种IPSEC与防火墙协同工作方案．     

智能业务和软交换互通的设计与实现

电信业的快速发展及下一代网络的全面建设促进智能业务与软交换实现互通。文中首先介绍了互通的种类和方案，并重点讲述了智能网和软交换互通过程中模型的重要部分——软交换侧的SSP。在此基础上，提出了智能网和软交换互通的实现方案，并且以智能用的典型业务FPH为例简明分析了方案，对利用业务服务器实现软交换中的智能业务进行了插述和分析。     

Kohonen与Madaline用于解析重叠光谱测定钨和钼

首先应用Kohonen网络对钨、钼的混合吸收光谱进行波长选择，在全光谱中优选最能代表光谱特征的波长，被选波长处吸光度作为Madaline网络的输入，设定输出目标函数为G（λ）＝∑Aiexp[-4(ln20）(λ-t）^2/2]，进行解析重叠光谱，同时测定了钨和钼，该法利用特征光谱代表全谱进行光谱解析，减少了解析光谱中大量的数据。     

智能业务和软交换互通的设计与实现

电信业的快速发展及下一代网络的全面建设促进智能业务与软交换实现互通.文中首先介绍了互通的种类和方案,并重点讲述了智能网和软交换互通过程中模型的重要部分--软交换侧的SSP.在此基础上,提出了智能网和软交换互通的实现方案,并且以智能网的典型业务FPH为例简明分析了方案,对利用业务服务器实现软交换中的智能业务进行了描述和分析.     

Binary perfect and extended perfect codes of lengths 15 and 16 and of ranks 13 and 14

Inaccuracies in computations in the paper of the authors on classification of perfect binary codes of lengths 15 and 16 and of rank 13 are fixed. An explicit construction of all extended perfect codes of length 16 and rank 13 with a given kernel size is presented. Perfect binary codes of length 15 and rank 14 obtained by the general doubling construction are classified.     

Definition and analysis of hardware- and software-fault-tolerantarchitectures

A structured definition of hardware- and software-fault-tolerant architectures is presented. Software-fault-tolerance methods are discussed, resulting in definitions for soft and solid faults. A soft software fault has a negligible likelihood or recurrence and is recoverable, whereas a solid software fault is recurrent under normal operations or cannot be recovered. A set of hardware- and software-fault-tolerant architectures is presented, and three of them are analyzed and evaluated. Architectures tolerating a single fault and architectures tolerating two consecutive faults are discussed separately. A sidebar addresses the cost issues related to software fault tolerance. The approach taken throughout is as general as possible, dealing with specific classes of faults or techniques only when necessary     

Oracle与Sybase体系结构的分析与研究

文章就当前非常流行的两大数据库系统Oracle和Sybase的体系结构、数据存储、备份处理及安全管理,从结构原理、应用等方面进行了系统地分析,总结了两系统的共性和个性,以利于实际应用。     

XML和数据库之比较与转换

本文比较了XML与数据库的优缺点，并探讨了XML与数据库相互转换的问题。     

Measures of controllability and observability and residues

The relationship between two measures of controllability and observability is derived, given a linear time-invariant system. Both of the measures are based on angles between various subspaces of the state space. It is shown that these measures can be used to bound the norm of the residues of the transfer function     

网络侦听以及反侦听的原理和实现

首先简要介绍了网络侦听的原理及其潜在的安全隐患,讲述了侦听技术在Unix和Windows环境下的几种实现技术;说明了如何检测侦听器的存在;最后提出了一种切实可行的、用来消除网络侦听的方案。     

存储系统NAS和SAN的差异和统一

分析了目前已经实现的主流网络存储技术SAN和NAS之间的差异,比较了它们之间在各方面的优劣,描述了多种实现NAS和SAN融合的手段,指出网络化存储必然相统一和融合发展,得出了IP之上存储是未来发展方向的结论。     

艺术设计美学的教育与本土化研究

设计美学是一个横跨多个学科,研究和阐释美学元素在设计中的应用与表现的美学理论,它在不同专业领域会因为人们对美学不同的认知和定位具有不同的解读,这也决定了设计美学这门学科有着极为丰富的内涵和外延。这个诞生于西方国家的美学理论在传入中国以后,开始在本土生根、开花和结果,然而平心而论,这些还远远不够。究其原因,是没有很好地与本土文化结合,因此研究出一套具有本土特色的设计美学教育法则就显得十分必要。     

反向规范化综合方法的研究及实现

提出一种将关系数据库向XML映射的新方法-反向规范化综合方法,阐述该方法的基本思想和实现步骤,即将规范化的表格连接成原来的非规范化的表,并转换成相应的XML DOM,最后进行XML DOM合并.这一方法已经在银行贷款系统中进行了实现和应用.     

复杂工程建模和模拟的验证与确认

综述国内外建模和模拟(Modeling and Simulation,MS)的验证与确认(Verification and Validation,VV)的相关概念、术语、规范、置信度评估方法和应用等方面的发展和研究进展,概括MS的VV中的几个关键问题,构建复杂工程MS的VV的知识指南,为MS的VV技术真正走向应用提供参考.     

传感网与物联网的进展与趋势

文章概括地论述了当前IT前沿技术中的热点：传感网、物联网的由来、进展与趋势,阐述了从因特网到物联网,从数字化、网络化到智能化的进展与融合,以及它们的汇聚所引发的IT第三次浪潮对产业革命和社会发展的影响与作用;文中提出传感器核心芯片和传感网接入因特网技术,是当前IT前沿技术攻关的瓶颈,并由此引出了物联网与智慧地球的新理念和战略性新兴产业;文中分析了物联网向融合化、嵌入化、可信化、智能化发展的技术趋势和向标准化、服务化、开放化、工程化发展的管理应用趋势。