Selectors Make Set-Based Analysis Too Hard

A set-based program analysis establishes constraints between sets of abstract values for all expressions in a program. Solving the system of constraints produces a conservative approximation to the program's runtime flow of values. Some practical set-based analyses use explicit selectors to extract the relevant values from an approximation set. For example, if the analysis needs to determine the possible return values of a procedure, it uses the appropriate selector to extract the relevant component from the abstract representation of the procedure. In this paper, we show that this selector-based approach complicates the constraint solving phase of the analysis too much and thus fails to scale up to realistic programming languages. We demonstrate this claim with a full-fledged value flow analysis for case-lambda, a multi-branched version of lambda. We show how both the theoretical underpinnings and the practical implementation become too complex. In response, we present a variant of set-based closure analysis that computes equivalent results in a much more efficient manner.     

易于移植的测试图形程序编译器

利用ＵＮＩＸ的词法、语法分析器的自动生成工具ｌｅｘ、ｙａｃｅ，方便地构造了编译器的前端，同时提供了修改前端的便利。并还定义了面向测试图形的描述性中间语言，以此作为移植的基础上。     

利用测量头测量圆孔中心操作的简化

利用机床提供的顾客软体 (变量 ) ,通过三点确定一个圆心的公理 ,精确测定圆心位置座标     

Petri网模型代码映射研究

为了简化仿真系统的实现过程,分析总结了Petri网到程序代码的映射准则,从Petri网的基本元素和关系入手,根据逻辑关系建立映射的三类原子语句,并通过两种合成方式形成分子语句。以原型Petri网为例,遍历可达标识图的各种分支路径,提出循环路径到循环结构语句的代码映射方法。最后给出了带抑制弧的扩展Petri网和受控Petri网的代码映射方案,为Petri网向程序代码的转换提供了理论依据。     

并发程序切片原型系统的设计与实现

并发程序切片是并发程序分析的一种重要手段。针对多线程共享变量通信机制,在通过程序分析工具CodeSurfer获取程序基本信息的基础上构造程序可达图,生成以程序状态和语句二元组为节点的并发程序依赖图,实现了基于程序可达图的并发程序切片原型系统。初步实验结果表明,与传统的切片方法相比,采用基于程序可达图的并发程序切片方法,可有效地解决依赖关系不可传递问题,获得高精度的并发程序切片。     

转炉煤气回收和放散自动控制系统改进

针对在煤气回收和放散调试过程中发现的问题,通过改进转炉煤气回收和放散控制系统,增加气动三通阀控制联锁信号,保证放散的高度可靠性和煤气自动回收的高度安全性。     

A novel logic-based automatic approach to constructing compliant security policies

It is significant to automatically detect and resolve the incompliance in security policy.Most existing works in this field focus on compliance verification,and few of them provide approaches to automatically correct the incompliant security policies.This paper proposes a novel approach to automatically transform a given security policy into a compliant one.Given security policy Π and delegation policy M declared by logic programs,the approach automatically rewrites Π into a new one ΠM which is compliant with M and is readable by the humans.We prove that the algorithm is sound and complete under noninterference assumption.Formally,we show that the security policy query evaluation algorithm with conflict and unsettlement resolution still works very well on ΠM.The approach is automatic,so it doesn’t require a administrator with excess abilities.In this sense,our proposal can help us to save much manpower resource in security management and improves the security assurance abilities.     

FLASH虚拟现实技术课件的设计与实现

交互式多媒体课件具有:虚拟现实、动态模拟、过程演示、人机交互等特点,其在教学过程中发挥出的独特优势是传统PPT课件无法替代的。文章讨论了利用FLASH动画制作功能和其提供的ActionScript2.0编程平台,制作"数字电路——二进制异步计数器"教学演示课件的方法和实现过程中的问题。主要介绍了本课件的设计方法,所要完成的功能和开发的过程,设计的重点、设计思想、难点技术和解决方案。     

COMPILE-TIME ANALYSIS AND OPTIMIZATION OF EXPLICITLY PARALLEL PROGRAMS*

Data flow analysis has been used by compilers in diverse contexts, from optimization to register allocation. Traditional analysis of sequential programs has centered on scalar variables. More recently, several researchers have investigated analysis of array sections for optimizations on modern architectures. This information has been used to distribute data, optimize data movement and vectorize or parallelize programs. As multiprocessors become more common-place. we believe there will be considerable interest in explicitly parallel programming languages. In this paper, we extend traditional analysis to array section analysis for parallel languages which include additional control and synchronization structures.

We show how to compute array section data flow information, i.e., Communication Sets, for a class of parallel programs. To illustrate its use, we show how this information can be applied in compile-time program partitioning. Information about array accesses can also be used to improve estimates of program execution time used to direct runtime thread scheduling.     

主机数据流量检测的实现

分布式网络环境中主机数据流量的异常通常反映出主机是否遭受病毒、木马等恶意程序的入侵而成为网络攻击中的傀儡机,因此,对主机数据流量进行监测可以尽早发现潜在的危险。研究了基于Cisco路由器的主机数据流量检测的基本方法,并给出了具体的程序实现方法和网络硬件环境配置方法。