A Supermodel Framework Supporting Validated Upgrading of Reactive Systems

A software product is typically upgraded many times over its lifetime. Reactive systems are no exception, undergoing evolutionary version changes to add features and fix bugs. Evolving these stateful systems, such as email clients, software agents, smart cell phones, and personal digital assistants, is complicated by the fact that new versions of the software must deal correctly with legacy instances. Users of earlier versions have invested significant resources in creating the state of the legacy instance, and usually require that this state be upgraded appropriately when the new system version is activated. However, validating the correctness of this upgrading behavior is particularly difficult, whether through testing or automated reasoning techniques like theorem proving or model checking, because legacy states are typically unreachable to the new version of the software. This paper explores this problem and requirements for its solution. It then presents a simple and widely applicable upgrade framework, based upon the idea of a supermodel that allows upgrade behavior to be validated using mainstream approaches. Finally, it also gives techniques for simplifying the validation problem.     

Optimal design of a welded I-section frame using four conceptually different optimization algorithms

The purpose of this study is to investigate the suitability of four conceptually different optimization algorithms for specifically the optimal design of welded I-section frames. The cost function to be minimized is the volume of the frame. Constraints on lateral-torsional buckling as well as local buckling of the beam and column webs and flanges are taken into consideration. The algorithms evaluated include a genetic algorithm, a novel leap-frog gradient method without line searches, as well as an orthogonal search method requiring no gradients and the differential evolution technique. Received September 26, 2001 RID="*" ID="*"Part of this paper was presented at the World Congress on Structural and Multidisciplinary Optimization, June 4–8 2001, Dalian, China     

王照与胡适

王照与胡适的交往,缘于同梁漱溟的争论,反映出他们思想上的殊途同归之处:胡氏是充分的西化论者,强调世界文化的同一性,主张学习西方的物质文明和精神文明,主张一步一步的渐进改革。王氏也强调物质文明的重要性,又从"世上那有捷径可走"的直观的进化论出发,在改革的途径上与胡氏达成了共识。     

呼唤网络领域的安全保障

分析Internet在网络安全方面失控原因 ,提出在网络安全方面实施安全保障的战略构思和策略     

Hydration Characteristics of Sodium Sulfate Slag Cement System

The hydration characteristics by thermal analysis ( DTA ) were determined, and an isothermal calorimeter (IC) was used to study the pastes . The experimental results indicate: (1) The main hydration products of SSC are C-S-H( I ) gel with a low Ca/Si ratio, crystalline Thomsonite-type and AFt-type phases containing certain alkali cations; (2) No phases of the AFm-type and high alkaline Ca( OH)2 in SSC system could benefit the hydrated cements to improve its strength and durability; (3) Crystalline Thomsonite-type and AFt-type phases containing Na will greatly reduce free alkali and alleviate the harmness of alkali aggregate reaction ( AAR) in SSC system; (4) Similar to ordinary Portland cement( OPC), the hydration process of SSC could be classified into five stages : initial, induction, acceleration, deceleration and decay; (5) Regardless of the activator used, the apparent activation energy is higher with the increased slag in cement system, and the rising temperature could promote the hydration of SSC.     

基于Petri网的软件架构演化波及效应分析

Petri网是一种系统描述和分析的工具。在构造系统PSA模型的基础上,利用其可达标识图同样能分析软件架构演化中的构件删除、增加、修改以及合并与分解各种变化引起的波及效应,且算法直观、复杂度小;并为运用Petri网技术研究SA提供了一个新思路。     

Time Stepping Via One-Dimensional Padé Approximation

The numerical solution of time-dependent ordinary and partial differential equations presents a number of well known difficulties—including, possibly, severe restrictions on time-step sizes for stability in explicit procedures, as well as need for solution of challenging, generally nonlinear systems of equations in implicit schemes. In this note we introduce a novel class of explicit methods based on use of one-dimensional Padé approximation. These schemes, which are as simple and inexpensive per time-step as other explicit algorithms, possess, in many cases, properties of stability similar to those offered by implicit approaches. We demonstrate the character of our schemes through application to notoriously stiff systems of ODEs and PDEs. In a number of important cases, use of these algorithms has resulted in orders-of-magnitude reductions in computing times over those required by leading approaches.     

基于免疫粒子群集成的RNA二级结构预测算法

RNA二级结构预测在计算生物学中具有重要意义,针对RNA二级结构预测,提出了一种新的免疫粒子群集成算法,根据个体的浓度和适应值概率,利用免疫机制,在粒子群优化算法中设计了免疫替换算子,有效防止了粒子群优化算法易陷入局部最优的缺陷;通过集成技术,充分发挥各种粒子群优化算法的优点,实现协同演化,提高了算法的全局搜索能力。最后用免疫粒子群集成算法去预测RNA二级结构,实验证明了算法的有效性。     

支持软件演化的扩展SDDM软件过程模型

软件演化已成为软件生存周期中最重要的形态之一。对基于Petri网、具有面向对象特征的软件过程模型SDDM进行改进,引入时间Petri网和有色Petri网的思想,同时在标准化、角色模型、资源模型三个方面对其进行扩展,得到一个新的支持软件演化过程的扩展SDDM软件过程模型。     

一种支持可靠语义互操作的本体演化管理框架

准确描述本体之间的关联是保证信息系统语义互操作可靠性的关键。该文提出了一个本体演化管理框架MFI-3，它包括本体注册模型、变化模型、约束模型、演化信息模型和变化传播模型。这些模型能支持本体的基本内容注册、本体复用及复杂的演化。通过对基于本框架的本体演化信息进行计算，可以得到可靠的本体映射。