面向行为的需求建模研究及实现

需求建模是需求工程中的重要步骤。提出了一种面向行为的需求建模方法,首先将目标系统问题域划分成多个子问题域,然后在子问题域里建立多个视点,在每个视点内,根据需求建立多个场景。对于每个场景,用行为描述语言建立场景行为模型,视点内所有场景的行为模型组合构成视点行为模型,目标系统所有视点的行为模型组合构成系统行为模型。在行为模型的基础上,提出了一系列特性以及其验证方法,用于验证行为模型的正确性以及系统特性。基于以上方法,设计和实现了面向行为的需求建模工具BRMT),以辅助开发人员从行为的角度进行需求建模。     

对象动态行为的建模方法及支撑工具

该文提出了一种基于对象数据模型的,同时又具有面向对象方法特征的对象行为模型。随后介绍了用这种模型描述对象动态行为的方法和步骤。最后简要地介绍了作者开发的一个支持这种建模过程的工具系统。     

一种面向对象的生产系统模拟工具-OSim的开发

介绍了一种面向对象的生产系统模拟工具OSim的体系结构和特点，以及应用Osim进行生产系统建模的方法和过程。面向对象的生产系统模拟模型的开发分为5个步骤：面向过程的建模，面向被动资源的建模，面向主动资源的建模，面向产品／物料的建模，层次化模型的建立。其中，面向对象的技术、基于活动网络的建模和层次化建模在生产系统建模中是非常重要的。     

OOCP∶面向对象的化工过程计算机辅助开发环境（Ⅰ）－面向对象方法建立过程系统模型

从过程系统的角度说明了面向对象概念，完成了对化工过程的多层次抽象，建立了近２０个化工类，并提出了用面向对象方法建立化工单元和过程系统面向方程模型的思想。文中介绍了化工类库的分类方法，类库定义、类库组织形式和面向对象建模机制等，可以看出，面向对象方法能快速、方便地建立新的化工单元和系统的面向方程模型，克服了传统设计方法中面向方程法模拟流程难以建模和利用已有模型产生新单元模型的缺点，为迅速、有效地建立化工模型探索了一条新途径。这也是作者提出的基于Ｗｉｎｄｏｗｓ的面向对象化工过程计算机辅助开发环境─ＯＯＣＰ的核心内容。     

一种软件需求描述语言的设计与实现

提出了一种面向软件行为的需求建模方法和需求描述语言BDL,介绍了需求描述语言的设计和实现方法。利用此需求建模可以根据用户的需求信息寻找出目标系统的有效行为,建立目标系统的行为模型。该行为模型可以帮助用户和开发人员正确认识和理解目标系统的行为,而且能为以后自动检测系统的各种特性提供良好的基础。     

面向CPS系统仿真的建模方法研究与设计

CPS仿真建模在构建CPS系统时具有重要意义,不仅能够在系统开发过程中对系统进行验证和测试,而且是模型驱动开发中的重要环节。CPS系统通过精化和提炼可分为物理实体和计算实体,采用具有动态连续性、基于时间的运动状态行为模型构建物理实体;计算实体模型则采用基于有限状态机的离散系统行为模型进行构建。通过面向时间的状态精化对两种行为模型进行扩展,将两种扩展模型进行融合,完成CPS系统的建模仿真。分析了构建计算实体模型的统一建模语言(UML)以及构建物理实体模型的simulink/RTW建模工具的可行性,提出了基于UML框架的两种异质模型融合方法。     

基于时序逻辑的软件行为需求描述

计算机软件的运行,归根到底是一个动态的过程,可以看作是由多个运行场景所组成的。传统的软件需求建模过程,包括面向对象建模,都是通过从需求规约中提取系统参与者,即角色,然后建立它们之间的联系以及它们的动作。而软件行为学,则是通过提取需求规约中的场景,来建立行为模型,继而确定参与角色。通过时序逻辑的方法来描述软件需求中的行为,并给出行为精化的过程,为软件行为学的研究奠定了基础。     

面向主体设计方法研究

面向Agent方法是分析复杂系统问题空间的有效途径,它和面向对象技术的比较在很多方面具有巨大的优点,面向对象设计方法的一切优点都可以被面向主体所吸收和容纳,特别在用Agent技术解决问题的方法及应用方面.通过一个例子来说明用Agent技术构建系统逻辑模型的过程.主体成为软件系统的基本单元,为协同工作提供了服务层次上的封装,整个系统的行为由构成系统的各个主体的交互、协作和协调决定.面向Agent建模方法提供了一系列的操作规程,据此可将现实系统以既定逻辑模型的形式描述出来.     

基于时序逻辑的软件行业需求描述

计算机软件的运行,归根到底是一个动态的过程,可以看作是由多个运行场景所组成的.传统的软件需求建模过程,包括面向对象建模,都是通过从需求规约中提取系统参与者,即角色,然后建立它们之间的联系以及它们的动作.而软件行为学,则是通过提取需求规约中的场景,来建立行为模型,继而确定参与角色.通过时序逻辑的方法来描述软件需求中的行为,并给出行为精化的过程,为软件行为学的研究奠定了基础.     

面向对象的建模思想及其在液压仿真中的应用

传统的液压仿真软件主要提供仿真运行的机制、通用的数据结构和函数，建模的任务就是把实际系统中元件之间的相互作用关系转换成在数据结构内部对数据的操作。这种建模方法不利于用户在一个具有实际含义的层次上观察模型的行为，也不利于对仿真模型的修改、扩充和重用。为了改进传统建模方法，仿真软件应采用面向对象的建模方法。一、面向对象的建模技术面向对象的思想是在仿真语言Simula中提出来的，它既是一种程序设计方法，同时又是一种认知方法。对象之间的继承性实现了从一般到特殊的演绎过程，类的概念反映了从特殊到一般的归纳现象…     

Comprehending object and process models: an empirical study

We report the results of an empirical study comparing user comprehension of object oriented (OO) and process oriented (PO) models. The fundamental difference is that while OO models tend to focus on structure, PO models tend to emphasize behaviour or processes. Proponents of the OO modeling approach argue that it lends itself naturally to the way humans think. However, evidence from research in cognitive psychology and human factors suggests that human problem solving is innately procedural. Given these conflicting viewpoints, we investigate empirically if OO models are in fact easier to understand than PO models. But, as suggested by the theory of cognitive fit, model comprehension may be influenced by task-specific characteristics. We therefore compare OO and PO models based on whether the comprehension activity involves: 1) only structural aspects, 2) only behavioral aspects, or 3) a combination of structural and behavioral aspects. We measure comprehension through subjects' responses to questions designed along these three dimensions. Results show that for most of the simple questions, no significant difference was observed insofar as model comprehension is concerned. For most of the complex questions, however, the PO model was found to be easier to understand than the OO model. In addition to describing the process and the outcomes of the experiments, we present the experimental method employed as a viable approach for conducting research into various phenomena related to the efficacy of alternative systems analysis and design methods. We also identify areas where future research is necessary, along with a recommendation of appropriate research methods for empirical examination     

基于依赖关系的模块变更概率度量：一个实验分析

模块变更预测对于面向对象软件的开发和维护工作具有重要意义。针对软件的模块变更预测问题,首先在软件类之间依赖关系的基础上提出了一种轻量级的模块变更概率计算方法,然后利用Logistic回归模型对Eclipse 2.0系统进行了实验分析。实验结果表明：一方面,基于依赖关系的模块变更概率度量捕获了与传统面向对象度量不同的信息;另一方面,当与传统的面向对象度量一起使用时,它们能够在统计意义上显著地提高模块变更预测的准确性。     

Hybrid method of FG‐FFT and PO for radiation calculation from antennas around an electrically large conducting platform

An efficient hybrid scheme combining fitting Green's function (FG) fast Fourier transform (FFT) and physical optics (PO) is presented to investigate radiation from antennas around an electrically large conducting platform. The whole region is divided into full wave region and PO one. Similar to hybrid method of integral equation FFT (IE‐FFT) and PO, this hybrid method features acceleration by FFT, fewer unknowns, less computing time than traditional IE‐FFT. Differently, realization of FG‐FFT is established by fitting the Green's function onto the nodes of a uniform Cartesian grid, not by Lagrange interpolation. Several examples are given to prove the hybrid method of FG‐FFT and PO in this letter featuring higher accuracy and being not sensitive to both grid spacing and the expansion order compared to hybrid method of IE‐FFT and PO.     

A graph-based generic type system for object-oriented programs

We present a graph-basedmodel of a generic type system for an OO language. The type system supports the features of recursive types, generics and interfaces, which are commonly found in modern OO languages such as Java. In the classical graph theory, we define type graphs, instantiation graphs and conjunction graphs that naturally illustrate the relations among types, generics and interfaces within complex OO programs. The model employs a combination of nominal and anonymous nodes to represent respectively types that are identified by names and structures, and defines graph-based relations and operations on types including equivalence, subtyping, conjunction and instantiation. Algorithms based on the graph structures are designed for the implementation of the type system. We believe that this type system is important for the development of a graph-based logical foundation of a formal method for verification of and reasoning about OO programs.     

Class movement and re-location: An empirical study of Java inheritance evolution

Inheritance is a fundamental feature of the Object-Oriented (OO) paradigm. It is used to promote extensibility and reuse in OO systems. Understanding how systems evolve, and specifically, trends in the movement and re-location of classes in OO hierarchies can help us understand and predict future maintenance effort. In this paper, we explore how and where new classes were added as well as where existing classes were deleted or moved across inheritance hierarchies from multiple versions of four Java systems. We observed first, that in one of the studied systems the same set of classes was continuously moved across the inheritance hierarchy. Second, in the same system, the most frequent changes were restricted to just one sub-part of the overall system. Third, that a maximum of three levels may be a threshold when using inheritance in a system; beyond this level very little activity was observed, supporting earlier theories that, beyond three levels, complexity becomes overwhelming. We also found evidence of ‘collapsing’ hierarchies to bring classes up to shallower levels. Finally, we found that larger classes and highly coupled classes were more frequently moved than smaller and less coupled classes. Statistical evidence supported the view that larger classes and highly coupled classes were less cohesive than smaller classes and lowly coupled classes and were thus more suitable candidates for being moved (within an hierarchy).     

OOram与面向对象方法

OOram（Object Oriented Role Analysis and Modeling）是挪威工业研究中心和奥斯陆大学提出的一种新一代面向对象软件工程方法,与众多其它面向对象方法相比较,其鲜明的特点是引入了角色模型的概念,将传统面向对象方法中的对象模型和类模型统一为单一的角色模型。文章提出了理想的面向对象开发方法所应具备的特性,简要介绍了OOram方法,并与其他面向对象方法作了比较。     

MSA火灾报警系统中图像型火源定位研究

图像型火灾探测系统是MSA(Multi-Step-Alarm)火灾系统中的重要环节,其重要任务之一是对监控场景中的火源进行精确定位。而在实际应用中,由于安装等因素的原因,要获取摄像机的图像坐标系与世界坐标系之间转换的关键参数非常困难。提出了一种基于双灭点的图像透视投影的坐标转换方法,该方法通过分析世界坐标系中4个点在图像坐标系中的位置关系,可以实现图像坐标系与世界坐标系之间的转换。实验结果证明该方法简便实用。     

UML类结构的形式化

为面向对象建模概念建立坚实的语义基础,越来越受到人们的重视。通过提供精确的概念特征定义,可建立精确的面向对象的行为模型和结构模型,便于对模型进行严格的分析。ＵＭＬ是一种被推荐的面向对象建模语言,ＲＡＩＳＥ是欧洲流行的一种形式方法,该文使用ＲＡＩＳＥ来表达ＵＭＬ类结构的含义。     

Cognitive activities in OO development

The cognitive activities performed by systems designers during systems development include problem understanding, problem decomposition and solution specification. One aspect of object-oriented (OO) approaches to system design that appeals to many adopting organizations is the purported naturalness, i.e. the consistency of OO approaches with these cognitive activities of problem solving. Essentially, OO aims to abstract components of the problem of system development to a high level that parallels problem solving in the world the system represents. In other words, knowing how a problem is solved in the real world informs one about how the OO system solves the problem. Thus, the OO development process and the resulting OO model are believed to be consistent with innate cognitive activities and consistent with the problem/real world, respectively. A cognitive mapping method was used to ask graduate students experienced with OO techniques about their perceptions of what is complex (difficult to understand) about OO systems. Their responses include a set of concepts, categories of similar concepts and cognitive maps that reveal what they believe is difficult about using OO techniques. Evaluating these perceptions in terms of the cognitive activities of system design reveals problem decomposition was perceived as the activity that caused the most difficulties related to learning OO techniques. Problem understanding was the goal of the participants, while the solution activity ranked lower in importance but contained many issues essential to systems development and influenced problem understanding.     

整数DCT变换中变换基的通用生成算法

H.264是ITU与ISO联合共同开发的具有高编码效率、高压缩质量的视频新标准。整数变换是其提高压缩性能最主要的改进方法之一,基于同样的整数变换过程的变换基可以不唯一,因此在整数变换的理论确定后,寻找变换基是一件重要的工作,提出了一种通用的变换基生成算法。该方法通过分析整数DCT变换的原理,指出了整数变换矩阵应该满足的4个约束条件,以满足正交性约束为出发点,导出了整数矩阵元素之间的数量关系,并辅以另外3个约束条件,采用搜索的方法寻找变换基。实验结果表明,该算法在经过几十步的搜索后,就能找出所有可用的变换基,JVT参考模型用到的变换基也在其中。