LTL is closed under topological closure

We constructively prove that for every LTL formula φ, the smallest safety property containing the property expressed by φ is also expressible in LTL. It immediately follows that LTL admits the safety-liveness decomposition: any property expressed by an LTL formula is equivalent to the intersection of a safety property and a liveness property, both of them expressible in LTL. Our proof is based on constructing a minimal deterministic counter-free Büchi automaton that recognizes the smallest safety property containing the property expressed by φ.     

企业档案信息化标准规范研究情况综述

档案信息化标准是企业信息化标准的一个组成部分,文章从企业档案信息化标准规范和企业档案信息化中的数据标准两个方面对企业档案信息化标准研究情况进行了概述,强调企业档案信息化标准应当采用新技术,使得在信息技术持续快速更新和数字对象机器元数据的存储量不断扩大的条件下能够保证数据资源的长久保存,预测和考虑未来技术的创新趋势,使当前的标准和规范能适用十年以后的发展。     

Abstraction and composition: a verification method for co-operating systems

Behaviour of systems is described by formal languages: the sets of all sequences of actions. Regarding abstraction, alphabetic language homomorphisms are used to compute abstract behaviours. To avoid loss of important information when moving to the abstract level, abstracting homomorphisms have to satisfy a certain property called simplicity on the concrete (i.e. not abstracted) behaviour. To be suitable for verification of so called co-operating systems, a modified type of satisfaction relation for system properties (approximate satisfaction) is considered. The well known state space explosion problem is tackled by a compositional method formalized by so called co-operation products of formal languages.     

Towards dependable development tools for embedded systems: a case study in software verification

This case study describes the specification and formal verification of the key part of SPaS, a development tool for the design of open loop programmable control developed at the University of Applied Sciences in Leipzig. SPaS translates the high-level representation of an open loop programmable control into a machine executable instruction list. The produced instruction list has to exhibit the same behaviour as suggested by the high-level representation. We discuss the following features of the case study: characterization of the correctness requirements, design of a verification strategy, the correctness proof, and the relation to the Common Criteria evaluation standard.     

Conscious worst case definition for risk assessment, part I: A knowledge mapping approach for defining most critical risk factors in integrative risk management of chemicals and nanomaterials

This paper helps bridge the gap between scientists and other stakeholders in the areas of human and environmental risk management of chemicals and engineered nanomaterials. This connection is needed due to the evolution of stakeholder awareness and scientific progress related to human and environmental health which involves complex methodological demands on risk management. At the same time, the available scientific knowledge is also becoming more scattered across multiple scientific disciplines. Hence, the understanding of potentially risky situations is increasingly multifaceted, which again challenges risk assessors in terms of giving the ‘right’ relative priority to the multitude of contributing risk factors. A critical issue is therefore to develop procedures that can identify and evaluate worst case risk conditions which may be input to risk level predictions. Therefore, this paper suggests a conceptual modelling procedure that is able to define appropriate worst case conditions in complex risk management. The result of the analysis is an assembly of system models, denoted the Worst Case Definition (WCD) model, to set up and evaluate the conditions of multi-dimensional risk identification and risk quantification. The model can help optimize risk assessment planning by initial screening level analyses and guiding quantitative assessment in relation to knowledge needs for better decision support concerning environmental and human health protection or risk reduction. The WCD model facilitates the evaluation of fundamental uncertainty using knowledge mapping principles and techniques in a way that can improve a complete uncertainty analysis. Ultimately, the WCD is applicable for describing risk contributing factors in relation to many different types of risk management problems since it transparently and effectively handles assumptions and definitions and allows the integration of different forms of knowledge, thereby supporting the inclusion of multifaceted risk components in cumulative risk management.     

嵌入式系统的软硬件协同设计

随着电子系统的复杂化，系统设计已成为一门重要学科。传统的反复试验法已经越来越不适应时代的关键。近年来，发展迅速的软硬件协同设计技术越来越受到人们的重视。它是在系统目标要求的指导下，通过综合分析系统软硬件功能及现有资源，最大限度地挖掘系统软硬件之间的并发性，协同设计软硬件体系结构，以使系统工作在最佳工作状态，本文系统地阐述了软硬件协同设计技术的特点及设计过程中应该注意的问题。     

国外湿法制粒机的最新动态观察与探讨

对德国Alexanderwerk公司设计出的G1/100型湿法制粒机的结构、特性、技术规格和适用范围进行详细阐述,从中可以看出此款湿法制粒机有很多优点,有较好的应用前景。     

Differences in basic standards of common cements

Considering that norms relating to cement are applied according to geographic scope, political or economic, can produce significant differences between them. In order to analyze the regulatory differences that may occur, this paper studied the regulations of the common basic standards for cement NCh (Chile), ASTM and UNE applied in Spain.These differences manifest themselves in different classifications of cement, differences in specification, differences in the tests performed to fulfill given specifications, differences in the degree of development of regulations and its relation to legal codes and enforced.I conclude that the regulations present differences in the case of the ASTM and UNE regulations, makes for greater harmonization difficult time. Cement standards including additions, contribute a product with lower environmental impact.     

气吹敷设光缆工程施工实践

根据一些光缆线路工程施工经验体会，就气吹敷设单管单缆而选用高密度聚乙烯塑料管和需用气吹敷设专用设备的特征，结合埋式光缆施工的开沟、布管、吹缆等工序，具体介绍光缆管道路由选择原则及气吹敷设光缆的施工方法。对施工过程中容易发生和出现的有可能会影响施工质量的问题，提出了一些事先预防、事后处理解决的做法，道出了经验之谈。