基于B方法的弹道计算机程序设计技术

针对任务关键性的武器装备控制领域,选用B方法来设计通用弹道计算机程序,显著地提高了软件的质量和可靠性。在开发过程中,利用抽象机机制对基本弹道计算机进行建模,并通过逐步精化的方法扩展弹道计算机功能,从而有效地控制了弹道计算参数之间的复杂关系,依赖不变式技术形式化地保证了软件运行时的安全性,并使得生成的程序具有良好的重用性和可扩展性。     

基于Web服务自动摘要系统的安全实现方案

在基于Web服务自动摘要系统的开发过程中,如何保障Web服务的安全是一个必须解决的难题。该文设计了一种利用SOAP消息头传递验证信息、基于会话的高效Web服务安全通信机制。实验证明,该安全通信方案满足了系统的安全需求。     

基于RBAC的扩展访问控制模型

权限管理是信息系统的重要环节,一个好的权限管理系统是成功的信息系统的重要因素。基于角色的权限控制策略提供了较高的灵活性和较低的管理负担,是目前研究的重点,文章在经典的基于角色的访问控制模型(RBAC)和基于任务的访问控制模型(TBAC)的基础上,对角色的管理和权限的定义进行了扩展,定义了更加灵活的基于角色的扩展权限控制模型XRBAC(Extended Role-Based Access Control)。     

基于SUIF自动产生具有OpenMP编译指示的并行程序

介绍了如何基于SUIF实现具有OpenMP编译指示的自动并行化工作,即利用SUIF系统所提供的遍(pass)、注释(annotation)和C抽象语法树等技术,通过对类Ctrec的修改,把并行注释转化为OpenMP编译指示,实现由串行程序到并行C程序的自动生成。     

同步语言Lustre的编译前端的设计与实现

同步语言Lustre所描述的反应系统通常应用在航空航天、国防建设等领域,对系统的正确性和安全性都要求很高。如果系统在运行时出现了正确性问题,很可能会导致系统崩溃,产生非常严重的后果。系统中的任何一个词法错误或者语法错误都应该受到重视,而且应该被及时纠正。因此,对Lustre语言进行正确的编译是十分重要的。传统的Lustre语言的编译器都采用OCaml语言描述,无法保证所有人员都能够很容易地理解和使用,而且,需要耗费开发人员大量的时间和精力。基于上述问题,提出了一种新型的Lustre语言编译器。新型的Lustre语言编译器前端主要采用C++语言进行描述,并对生成的抽象语法树的结构进行重新定义,简化了编译的过程。该编译前端会对一个经典的Lustre语言模型进行检测,通过对检测的结果进行分析,验证了该编译前端的可行性。     

Static analysis of JavaScript libraries in a scalable and precise way using loop sensitivity

Statically analyzing JavaScript applications often requires an analysis of JavaScript libraries because many JavaScript applications use libraries. However, static analysis techniques for JavaScript are not yet ready for analyzing libraries in a scalable and precise manner. Simply loading JavaScript libraries uses various dynamic features of JavaScript, which cause static analyzers to suffer from mutually intermingled problems of scalability and imprecision. In this paper, we present a loop‐sensitive analysis (LSA) technique, which can improve the analysis scalability when analyzing JavaScript libraries by enhancing the analysis precision of loops. The LSA technique distinguishes loop iterations when loop conditions can be determined to be either true or false precisely. We formalize LSA in the abstract interpretation framework in the presence of tricky language features such as exceptions and prove its soundness and precision theorems using Coq. We evaluate our LSA implementation with the analysis results of programs that use 5 JavaScript libraries and show that LSA significantly improves the analysis scalability and precision of an existing JavaScript static analyzer when analyzing JavaScript libraries. In addition, using the configurability of LSA, we experimentally show the correlation between scalability and precision in the analysis of JavaScript libraries. We found that even the analysis of simple programs that just load jQuery, which is the most popular JavaScript library, in a scalable way requires distinguishing not only the last 4 functions being called but also 40 iterations in each loop with 2‐level nested loops at least. Both the mechanization and implementation of LSA are publicly available.     

The Logarithmic Image Processing Model: Connections with Human Brightness Perception and Contrast Estimators

The logarithmic image processing (LIP) model is amathematical framework based on abstract linear mathematicswhich provides a set of specific algebraic and functionaloperations that can be applied to the processing of intensityimages valued in a bounded range. The LIP model has been provedto be physically justified in the setting of transmitted lightand to be consistent with several laws and characteristics ofthe human visual system. Successful application examples havealso been reported in several image processing areas, e.g.,image enhancement, image restoration, three-dimensional imagereconstruction, edge detection and image segmentation.The aim of this article is to show that the LIP model is atractable mathematical framework for image processing which isconsistent with several laws and characteristics of humanbrightness perception. This is a survey article in the sensethat it presents (almost) previously published results in arevised, refined and self-contained form. First, an introductionto the LIP model is exposed. Emphasis will be especially placedon the initial motivation and goal, and on the scope of themodel. Then, an introductory summary of mathematicalfundamentals of the LIP model is detailed. Next, the articleaims at surveying the connections of the LIP model with severallaws and characteristics of human brightness perception, namelythe brightness scale inversion, saturation characteristic, Weber'sand Fechner's laws, and the psychophysical contrast notion. Finally,it is shown that the LIP model is a powerful and tractable framework for handling the contrast notion. This is done througha survey of several LIP-model-based contrast estimators associated with special subparts (point, pair of points,boundary, region) of intensity images, that are justified bothfrom a physical and mathematical point of view.     

陶瓷材料的机械磨—放电复合加工技术研究

对陶瓷材料的金刚石砂轮磨削加工和放电加工机理进行了研究,并提出了机械磨—放电复合加工技术。由于该复合加工技术有效地结合了放电加工和机械磨削加工的特点,并且二者互为有利条件,因而能高效率、高质量地加工陶瓷材料。实验结果表明,该复合加工技术的加工效率是机械磨削加工的3倍左右,并且加工表面质量与机械磨削相近。