A Unified Framework for Cohesion Measurement in Object-Oriented Systems

The increasing importance being placed on software measurement has led to an increased amount of research developing new software measures. Given the importance of object-oriented development techniques, one specific area where this has occurred is cohesion measurement in object-oriented systems. However, despite a very interesting body of work, there is little understanding of the motivation and empirical hypotheses behind many of these new measures. It is often difficult to determine how such measures relate to one another and for which application they can be used. As a consequence, it is very difficult for practitioners and researchers to obtain a clear picture of the state-of-the-art in order to select or define cohesion measures for object-oriented systems. This situation is addressed and clarified through several different activities. First, a standardized terminology and formalism for expressing measures is provided which ensures that all measures using it are expressed in a fully consistent and operational manner. Second, to provide a structured synthesis, a review of the existing approaches to measure cohesion in object-oriented systems takes place. Third, a unified framework, based on the issues discovered in the review, is provided and all existing measures are then classified according to this framework. Finally, a review of the empirical validation work concerning existing cohesion measures is provided. This paper contributes to an increased understanding of the state-of-the-art: a mechanism is provided for comparing measures and their potential use, integrating existing measures which examine the same concepts in different ways, and facilitating more rigorous decision making regarding the definition of new measures and the selection of existing measures for a specific goal of measurement. In addition, our review of the state-of-the-art highlights several important issues: (i) many measures are not defined in a fully operational form, (ii) relatively few of them are based on explicit empirical models as recommended by measurement theory, and (iii) an even smaller number of measures have been empirically validated; thus, the usefulness of many measures has yet to be demonstrated.     

面向对象软件内聚度度量数据分布的实证研究

度量数据的分布信息对于理解和使用面向对象软件度量有重要意义.人们对面向对象软件规模度量、耦合度度量乃至继承维度的度量数据的分布都有研究,但对除内聚度缺乏度LCOM之外的内聚度度量数据的分布却缺乏研究.已有的实证研究表明,LCOM并不是好的内聚度度量,因此探讨其他内聚度度量数据分布很有必要.对包括内聚度缺乏度、基于连通性的内聚度度量和基于相似性的内聚度度量总共17个度量指标在112个Java开源软件项目的分布情况进行实证研究,对每个度量指标的每个项目数据使用幂律分布和对数正态分布进行拟合,并使用荟萃分析方法对拟合结果进行了分析.实证研究结果表明,非规范化的内聚度量可使用对数正态分布和幂律分布拟合,但规范化的基于相似性的内聚度量（包括CC、LSCC、SCOM和SCC）需要排除方法数小于等于1或字段数为0的特殊类才能使用对数正态分布拟合,而基于连通性的内聚度度量（包括TCC、LCC、DCD和DCI）则只有对应的非规范化版本的数据才符合对数正态分布或幂律分布.实证研究可帮助人们更好地理解和使用内聚度度量,特别是可以帮助人们如何利用已有的方法确定内聚度度量的阈值.     

AML与面向对象建模

在面向对象建模中 ,状态机模型的继承是对象行为继承的重要组成部分 .为便于理解子类型的状态机模型与其父类型的状态机模型间的关系 ,我们研究了一种状态机模型及其继承的描述技术 ,从一定程度上解决了现有的状态机模型继承的描述技术中存在的一些问题 .本文在分析 AML中支持面向对象特征的主要设施的基础上 ,着重讨论了状态机模型的继承问题 .     

Package Coupling Measurement in Object-Oriented Software

The grouping of correlated classes into a package helps in better organization of modern object-oriented software. The quality of such packages needs to be measured so as to estimate their utilization. In this paper, new package coupling metrics are proposed, which also take into consideration the hierarchical structure of packages and direction of connections among package elements. The proposed measures have been validated theoretically as well as empirically using 18 packages taken from two open source software systems. The results obtained from this study show strong correlation between package coupling and understandability of the package which suggests that proposed metrics could be further used to represent other external software quality factors.     

基于有向带权图迭代的面向对象系统分解方法

针对如何从现存的系统中提取构件的问题,提出了一种基于有向带权图迭代分析的面向对象系统分解方法.它将面向对象系统抽象为一个有向带权图,使用迭代算法考察不同粒度的子图的独立性,并选择独立性高的作为候选构件.实验结果表明,该方法是一种有效的系统分解方法,在准确性上比现有系统分解方法有所提高.     

案例教学法在“面向对象程序设计”课程中的运用

案例教学法作为一种具有启发性和实践性的新型教学方法,在很多学科教学中有广泛的应用,通过在面向对象程序设计课程中的运用,使学生在学习知识的过程中体会到真正的面向对象的系统开发过程,极大提高了学生的学习兴趣和主动性,对培养学生的动手开发能力和提高学生的综合素质,具有良好的效果。     

面向对象方法在质谱全自动测量系统中的应用

简要介绍了质谱仪器的测量原理、应用领域及其系统结构,采用了J.Rumbaugh的对象建模技术对质谱全自动测量系统软件进行分析和设计,给出了样品分析子系统的对象模型、动态模型以及质谱全自动测量系统的功能模型。     

C++程序设计案例遴选

针对C++程序设计课程中缺乏经典项目案例的问题,分析了从IT公司、开源项目中选取C++开发案例的优缺点。从开源项目中选取了8个关注度高、适合大学低年级学生知识结构的案例,设计了一套定量化的评估指标,使用代码查询语言(Code Query Language,CQL)及代码分析工具CppDepend,对这些案例进行了定量评估,给出了遴选C++程序设计案例的建议。     

A Framework for Class Partitioning in Object-Oriented Databases

In order to support homogeneous distributed object oriented database systems we need to have a clear understanding of what is meant by partitioning a class and what are the different ways of doing so. In this paper, we concentrate on studying the different types of class partitioning schemes that can arise in object oriented databases. To come up with a general-purpose design methodology, we present a framework of devising partitioning schemes based on different types of methods and their classification. We also address the issue of fragmentation transparency by considering appropriate method transformation techniques. By laying down the foundation by articulating the concepts, representation, and implementation approaches for partitioning object databases, we facilitate further work on partitioning algorithms, query decomposition, optimization and transaction management for distributed OODBMS.     

一种面向对象数据库继承层次索引配置方法①

如何平衡面向对象数据库（OODB）索引的检索性能、维护开销、实现复杂度已经成为一个影响OODB性能的关键问题。提出一种OODB继承层次索引配置方法。通过开销模型评估各种索引配置的检索开销、存储开销、更新开销,根据数据库真实使用情况选择最优索引配置。通过实验,验证这种方法的准确性,并且同其他常见索引策略作对比。结果表明该方法可以为OODB提供性能最优的索引方案。     

Algorithms and Support for Horizontal Class Partitioning in Object-Oriented Databases

Horizontal partitioning is a logical database design technique which facilitates efficient execution of queries by reducing the irrelevant objects accessed. Given a set of most frequently executed queries on a class, the horizontal partitioning generates horizontal class fragments (each of which is a subset of object instances of the class), that meet the queries requirements. There are two types of horizontal class partitioning, namely, primary and derived. Primary horizontal partitioning of a class is performed using predicates of queries accessing the class. Derived horizontal partitioning of a class is the partitioning of a class based on the horizontal partitioning of another class. We present algorithms for both primary and derived horizontal partitioning and discuss some issues in derived horizontal partitioning and present their solutions. There are two important aspects for supporting database operations on a partitioned database, namely, fragment localization for queries and object migration for updates. Fragment localization deals with identifying the horizontal fragments that contribute to the result of the query, and object migration deals with migrating objects from one class fragment to another due to updates. We provide novel solutions to these two problems, and finally we show the utility of horizontal partitioning for query processing.     

A Critical Analysis of PSP Data Quality: Results from a Case Study

The Personal Software Process (PSP) is used by software engineers to gather and analyze data about their work. Published studies typically use data collected using the PSP to draw quantitative conclusions about its impact upon programmer behavior and product quality. However, our experience using PSP led us to question the quality of data both during collection and its later analysis. We hypothesized that data quality problems can make a significant impact upon the value of PSP measures—significant enough to lead to incorrect conclusions regarding process improvement. To test this hypothesis, we built a tool to automate the PSP and then examined 89 projects completed by ten subjects using the PSP manually in an educational setting. We discovered 1539 primary errors and categorized them by type, subtype, severity, and age. To examine the collection problem we looked at the 90 errors that represented impossible combinations of data and at other less concrete anomalies in Time Recording Logs and Defect Recording Logs. To examine the analysis problem we developed a rule set, corrected the errors as far as possible, and compared the original and corrected data. We found significant differences for measures such as yield and the cost-performance ratio, confirming our hypothesis. Our results raise questions about the accuracy of manually collected and analyzed PSP data, indicate that integrated tool support may be required for high quality PSP data analysis, and suggest that external measures should be used when attempting to evaluate the impact of the PSP upon programmer behavior and product quality.     

Using Many-Sorted Logic in the Object-Oriented Data Model for Fast Robot Task Planning

Search space explosion is a critical problem in robot task planning. This problem limits current robot task planners to solve only simple block world problems and task planning in a real robot working environment to be impractical. This problem is mainly due to the lack of utilization of domain information in task planning. In this paper, we describe a fast task planner for indoor robot applications that effectively uses domain information to speed up the planning process. In this planner, domain information is explicitly represented in an object-oriented data model (OODM) that uses many-sorted logic (MSL) representation. The OODM is convenient for the management of complex data and many-sorted logic is effective for pruning in the rule search process. An inference engine is designed to take advantage of the salient features of these two techniques for fast task planning. A simulation example and complexity analysis are given to demonstrate the advantage of the proposed task planner.     

与继承相关的C＋＋程序错误模式

文中分析了C 程序中与继承相关的错误模式，这些错误会引起程序的数据流异常和行为异常。给出了几种常见错误模式的表现形式，结合实例详细分析了这些错误模式的产生原因及特点，重点讨论了容易产生数据流异常的基类与派生类之间的状态一致性问题，得到错误模式的分类。最终达到使用错误模式指导程序分析，检测面向对象程序中的潜在异常，维护系统的安全的目的。     

与继承相关的C＋＋程序错误模式

分析了C 程序中与继承相关的错误模式，这些错误会引起程序的数据流异常和行为异常。给出了几种常见错误模式的表现形式，结合实例详细分析了这些错误模式的产生原因及特点，重点讨论了容易产生数据流异常的基类与派生类之间的状态一致性问题，得到错误模式的分类。最终达到使用错误模式指导程序分析，检测面向对象程序中的潜在异常，维护系统的安全的目的。     

Signatures: A language extension for improving type abstraction and subtype polymorphism in C++

C++ uses inheritance as a substitute for subtype polymorphism. We give examples where this makes the type system too inflexible. We then describe a conservative language extension that allows a programmer to define an abstract type hierarchy independent of any implementation hierarchies, to retroactively abstract over an implementation, and to decouple subtyping from inheritance. This extension gives the user more of the flexibility of dynamic typing while retaining the efficiency and security of static typing. With default implementations and views flexible mechanisms are provided for implementing an abstract type by different concrete class types. We first show how the language extension can be implemented in a preprocessor to a C++ compiler, and then detail and analyse the efficiency of an implementation we directly incorporated in the GNU C++ compiler.     

VLSI设计中容性交叉耦合对时序分析的影响

互连线间的容性交叉耦合已成为影响线路延迟的一个重要因素,因此本文将阶层设计中有意义的层次结构考虑到电路时序分析中,在存在静态敏化和动态敏化交叉耦合的电路中提出了局部伪交叉耦合和全局伪交叉耦合的概念,给出了一种利用模块间功能关系考虑由于模块间连接而产生的全局伪交叉耦合的综合的时序分析方法.实验数据证明,本文方法在不影响运行速度的前提下可以有效地识别出伪交叉耦合,提高了时序验证的准确性.     

Development and validation of a behavioural video coding scheme for detecting mental workload in manual assembly

Abstract

Manual assembly in the future Industry 4.0 workplace will put high demands on operators’ cognitive processing. The development of mental workload (MWL) measures therefore looms large. Physiological gauges such as electroencephalography (EEG) show promising possibilities, but still lack sufficient reliability when applied in the field. This study presents an alternative measure with a substantial ecological validity. First, we developed a behavioural video coding scheme identifying 11 assembly behaviours potentially revealing MWL being too high. Subsequently, we explored its validity by analysing videos of 24 participants performing a high and a low complexity assembly. Results showed that five of the behaviours identified, such as freezing and the amount of part rotations, significantly differed in occurrence and/or duration between the two conditions. The study hereby proposes a novel and naturalistic method that could help practitioners to map and redesign critical assembly phases, and researchers to enrich validation of MWL-measures through measurement triangulation.

Practitioner summary: Current physiological mental workload (MWL) measures still lack sufficient reliability when applied in the field. Therefore, we identified several observable assembly behaviours that could reveal MWL being too high. The results propose a method to map MWL by observing specific assembly behaviours such as freezing and rotating parts.

Abbreviations: MWL: mental workload; EEG: electroencephalography; fNIRS: functional near infrared spectroscopy; AOI: area of interest; SMI: SensoMotoric Instruments, ETG: Eye-Tracking Glasses; FPS: frames per second; BORIS: Behavioral Observation Research Interactive Software; IRR: inter-rater reliability; SWAT: Subjective Workload Assessment Technique; NASA-TLX: National Aeronautics and Space Administration Task Load Index; EL: emotional load; DSSQ: Dundee Stress State Questionnaire; PHL: physical load; SBO: Strategisch Basis Onderzoek     

高性能计算机系统中影响通信因素分析和优化策略的研究

高性能并行计算机系统中由于 CPU速度不断提高 ,通信机制成了影响系统性能的首要因素 .为了优化通信性能 ,本文从硬件和软件两方面综合分析了影响通信的因素 .从硬件上阐述了紧耦合策略 ,以及网络接口电路通过配置协处理器和较大容量存储器的策略 .从软件上提出了固定缓冲区策略和用户层通信策略 .在用户层通信策略中 ,阐述了管理监控进程办法和原子访问办法 ,重点说明了原子访问机制的思想和实施办法 .这些策略对提高机群系统的性能有重要意义     

Success Factors for Using Case Management System in Italian Courts

This study takes a first step toward understanding the effectiveness of e-court applications in Italy. The proposed research model to assess the success factors for using case management system was tested in two Italian courts. Analysis of survey data from 314 users, using structural equation modeling, reveals the explanatory role of the model and the salient contribution of system and information quality variables on court staff’s performance. Our findings have important implications for theory and practice.