A framework for automatic generation of security controller

This paper concerns the study, the development and the synthesis of mechanisms for guaranteeing the security of complex systems, i.e. systems composed of several interacting components. A complex system under analysis is described as an open system, i.e. a system in which an unspecified component (a component whose behaviour is not fixed in advance) interacts with the known part of the system. Within this formal approach, we propose techniques that aim at synthesize controller programs able to guarantee that, for all possible behaviours of the unspecified component, the system should work properly, e.g. it should be able to satisfy a certain property. For performing this task, we first need to identify the set of necessary and sufficient conditions that the unspecified component has to satisfy in order to ensure that the whole system is secure. Hence, by exploiting the satisfiability procedures for temporal logic, we automatically synthesize an appropriate controller program that forces the unspecified component to meet these conditions. This will ensure the security of the whole system. In particular, we contribute within the area of the enforcement of security properties by proposing a flexible and automated framework that goes beyond the definition of how a system should behave to work properly. Indeed, while the majority of the related work focuses on the definition of monitoring mechanisms, we also address the synthesis problem. Moreover, we describe a tool for the synthesis of secure systems which is able to generate appropriate controller programs. This tool is also able to translate the synthesized controller programs into the ConSpec language. ConSpec programs can be actually deployed for enforcing security policies on mobile Java applications by using the run‐time framework developed in the ambit of the European Project S3MS. Copyright © 2010 John Wiley & Sons, Ltd.     

BR0-代数三种理想的关系和性质

为了进一步研究BR0一代数的结构．首先在BR0-代数中给出了蕴涵理想,O-理想和V-理想的定义;其次,讨论了BR0-代数中这三种理想的关系;最后,研究了BR0-代数中理想的一些性质,并证明了极大理想存在定理．     

Extended space method for parameter identifiability of DAE systems

Mathematical models of physical systems often have parameters that must be identified from physical data. This makes the analysis of the parameter identifiability of the given model system an essential prerequisite. Thus far, several methods have been proposed for analyzing the parameter identifiability of ordinary differential equation (ODE) systems. But, to the best of our knowledge, the parameter identifiability of differential algebraic equation (DAE) systems has scarcely been analyzed as a specific topic. Traditional differential algebraic (DA) methods developed for ODE systems are often applied directly on DAE systems. These methods, however, are not always applicable, e.g., when the prime ideal condition is not satisfied by a DAE system. In this paper, we propose a novel method to analyze the identifiability of DAE systems, based on the concept of space extension, through which the algebraic and differential variables can be decoupled. Furthermore, an inherent, low-dimensional, regular ODE system can be obtained, which is the external equivalent of the original DAE system. Subsequently, the differential algebraic (DA) method can then be used to analyze the identifiability of the low-dimension ODE system. Theoretical analysis is also presented for the proposed method. Two examples, including a simplified interaction model and an isothermal reactor system, are presented to illustrate the detailed steps and effectiveness of the proposed method.     

PLC在DU1909组合镗床上的应用

介绍了欧姆龙 C6 0 P可编程序控制器在组合镗床上的改造应用。根据机床的工艺要求 ,运用布尔代数和其它方法 ,设计了梯形图软件 ,在实际应用中取得了良好的效果     

线性方程组的基本理论在配平化学方程式中的应用——改进的线性代数法

利用线性方程组的基本理论对现有的配平化学方程式的方法-线性代数法加以改进，通过增加一行元素，将电子表征向量体现出来，使之适用于一切化学反应方程式的配平，实例证明改进后的方法比其他配平化学方程式方法更优越，尤其是对复杂的方程。     

Estimation with the nested logit model: specifications and software particularities

The paper discusses the nested logit model for choices between a set of mutually exclusive alternatives (e.g. brand choice, strategy decisions, modes of transportation, etc.). Due to the ability of the nested logit model to allow and account for similarities between pairs of alternatives, the model has become very popular for the empirical analysis of choice decisions. However the fact that there are two different specifications of the nested logit model (with different outcomes) has not received adequate attention. The utility maximization nested logit (UMNL) model and the non-normalized nested logit (NNNL) model have different properties, influencing the estimation results in a different manner. This paper introduces distinct specifications of the nested logit model and indicates particularities arising from model estimation. The effects of using various software packages on the estimation results of a nested logit model are shown using simulated data sets for an artificial decision situation. Financial support by the German Research Foundation (DFG) through the research project #BO1952/1 and the SFB 649 “Economic Risk” is gratefully acknowledged. The authors would like to thank two anonymous reviewers for their helpful and constructive comments.     

A refined difference field theory for symbolic summation

In this article we present a refined summation theory based on Karr’s difference field approach. The resulting algorithms find sum representations with optimal nested depth. For instance, the algorithms have been applied successively to evaluate Feynman integrals from Perturbative Quantum Field Theory.     

故障诊断系统中分布式计算的研究和实现

本文概述了某故障诊断软件平台的总体结构，分析了作为软件平台核心部分的诊断 平台的结构和功能，研究了诊断平台系统的数据结构和分布式任务管理策略，最后，讨论了有关实现方面的问题。     

PEPA Queues: Capturing Customer Behaviour in Queueing Networks

Queueing network formalisms are very good at describing the spatial movement of customers, but typically poor at describing how customers change as they move through the network. We present the PEPA Queues formalism, which uses the popular stochastic process algebra PEPA to represent the individual state and behaviour of customers and servers. We offer a formal semantics for PEPA Queues, plus a direct translation to PEPA, allowing access to the existing tools for analysing PEPA models. Finally, we use the ipc/DNAmaca tool-chain to provide passage-time analysis of a dual Web server example.