电子词典的设计研究

电子词典的设计过程中要考虑诸多的技术问题,其核心环节是通过编程实现数据的索引和调用关系,高效地组织数据,进而构造出“个性化”的词典软件是设计者的目标,它将数据库和全文检索技术融为一体,同时有软件自身的丰富的特点和功能。文中对一个英文电子词典的设计思想进行表述,并讨论设计相关细节。     

Design and implementation of low-cost emulators for microprocessors

Most emulators currently available require a fairly complex host for their operation. The paper considers a low-cost software-intensive approach to emulator design for a variety of microprocessors. The (minimal) hardware requirements are described; then the software and operation of the emulator are discussed in detail. The execution of various types of command is analysed. Finally, the implementation of the emulator design is summarized.     

A survey on search-based software design

This survey investigates search-based approaches to software design. The basics of the most popular meta-heuristic algorithms are presented as background to the search-based viewpoint. Software design is considered from a wide viewpoint, including topics that can also be categorized as software maintenance or re-engineering. Search-based approaches have been used in research from the high architecture design level to software clustering and finally software refactoring. Enhancing and predicting software quality with search-based methods is also taken into account as a part of the design process. The background for the underlying software engineering problems is discussed, after which search-based approaches are presented. Summarizing remarks and tables collecting the fundamental issues of approaches for each type of problem are given. The choices regarding critical decisions, such as representation and fitness function, when used in meta-heuristic search algorithms, are emphasized and discussed in detail. Ideas for future research directions are also given.     

Computer-aided ergonomics: a case study of incorporating ergonomics analyses into workplace design

One of the primary goals of computer-aided ergonomics is to develop software tools that allow ergonomics information to be accessed at the earliest stages of design. This case study discusses a PC-based software program that allows a designer to quantify a worker's biomechanical risk for injury based on a proposed workplace design. The program couples an established software tool for biomechanical analysis, the Three-Dimensional Static Strength Prediction Program (3DSSPP), with a widely used computer-aided design software package, AutoCAD. The use of this "3DSSPP/AutoCAD interface" in the proactive analysis of an automotive assembly task is described and the results compared with an independent assessment using observations of workers performing the same task. Both studies yield similar conclusions, suggesting that proactive use of software such as the 3DSSPP/AutoCAD interface may be a valid tool in evaluating proposed workplace designs. In this context, issues in the analysis of workplace designs regarding the use of supporting ergonomic tools, assumptions, and posture selection are discussed.     

Design pattern evolutions in QVT

One of the main goals of design patterns is to design for change. Many design patterns leave some room for future changes and evolutions. The application of design patterns leads to adaptable software since the design pattern instances could be changed with minimal impact on other parts of the system. Such changes, called the evolution of a design pattern instance in this paper, typically involve the addition or removal of a group of model elements, such as classes, attributes, operations, and relationships. However, the possible evolutions of each design pattern are often not explicitly documented. Missing a part of the evolution process may result in inconsistent evolutions. In this paper, we present our approach to assist the evolution processes of design patterns by model transformation technology. We provide a formal foundation for our approach by defining the predicates that can be used to describe the properties of each design pattern, software system design, and design pattern evolutions. We also provide tool support to automate the evolution processes based on the Query, View, and Transformation standard. A case study of a large open-source software system is conducted to illustrate and evaluate our approach.     

Design of minimal order stable observers for linear functions of the state via realization theory

Abstract--The design of a minimal order stable observer and a minimal order observer with arbitrary poles that estimates a vector linear function of the state of a multivariable system is discussed. It is shown that both problems can be solved in a straightforward manner using partial realization theory, and several new results are given. These include a strong bound for the dimension of the minimal order stable observer and a simple necessary condition to design the minimal order observer with arbitrary poles that estimates a vector linear function of the state of a multiple-output system. Necessary and sufficient conditions are given for designing a minimal order observer with arbitrary poles for the case of estimating a vector linear function of the state of a single-output system and the case of estimating a scalar linear function of the state of a multiple-output system. A procedure to carry out the design in each of these cases is described. No restrictions whatsoever (except stability) are placed on the possible values of the observer poles. A significant observation of this paper is that the dynamics of the observer are constrained (in all cases) only by the gain matrix in the feedback law to be estimated and the output structure of the given system.     

A case history development of a foolproofing interfacedocumentation system

The authors discuss information transmission errors occurring between design engineers involved in software development and describe an interface design documentation system that can prevent them. The equivalence of human errors in software design and hardware manufacturing activities is established. The characteristics that must be included in an interface documentation system to prevent communication errors in software design activities, based on foolproofing principles that were identified for hardware manufacturing, are discussed. Utilizing these characteristics, an example of an interface documentation system for software products which control measuring equipment is presented. Its effects on the resultant number of communication errors between hardware and software engineers is subsequently experimentally evaluated     

Development of an Intelligent Wheelchair Using Computer Graphics Animation and Simulation

A new robot simulator JC-1 is used as a control software development tool in a project in progress where an intelligent wheelchair for a blind user is being developed. The intelligent wheelchair is planned to be able to fulfill simple symbolic commands like "follow wall" or "follow object" and using the JC-1 simulator an evaluation team which includes e.g. the user, a rehabilitation engineer and a software engineer, can check control algorithms and user interface routines before constructing a real wheelchair prototype. The JC-1 simulator models the environment using simplified boundary- representation where objects, robot sensors and actuators are presented as symbolic objects in the graphics data-base of the simulator. In the JC-1 simulator a robot controller under development controls the motion of the graphical model of the robot while simulator commands or other robot controllers can be used to control the movement of disturbing obstacles. Computer graphics animation and simulation help to find fundamental design errors at an early design stage and as this paper suggests, enable the user of the final product to take part in to the designing process of the robot controller. Benefits and difficulties of using computer graphics simulation in the wheelchair development process are discussed.     

Entropy metrics for software design evaluation

Several metrics for the quality assessment of a software system design are discussed. The metrics are based on the entropy function of communication information theory. The design of software systems is viewed as a trade-off between the information contained within a subsystem and the information shared among the subsystems of a given system. Since information can be shared in different ways by different system designs, we can compute the excess entropy and thereby rank different design alternatives. Consequently, the quality improvement due to reconfigurations can be determined by calculating the excess entropies for each reconfiguration.     

Windows环境下塔板设计软件的开发

现有的塔板设计软件一般是在ＤＯＳ或ＵＮＩＸ操作系统下运行的，使用上有不少缺陷，针对塔板设计过程的特点，我们以Ｗｉｎｄｏｗｓ作为操作系统，以功能很强的ＶｉｓｎａｌＢａｓｉｃ作为开发工具，开发了一个新的塔板设计软件ＴＣＤ，与其他塔板设计软件相比，ＴＣＤ具有良好的用户界面，人机对话功能和图形功能，易学易用，用ＴＣＤ既可以进行新塔设计，也可以对旧塔进行校核和改造设计，具有良好的实用价值。     

Analyzing Software Safety

With the increased use of software controls in critical realtime applications, a new dimension has been introduced into software reliability–the "cost" of errors. The problems of safety have become critical as these applcations have increasingly included areas where the consequences of failure are serious and may involve grave dangers to human life and property. This paper defines software safety and describes a technique called software fault tree analysis which can be used to analyze a design as to its safety. The technique has been applied to a program which controls the flight and telemetry for a University of California spacecraft. A critical failure scenario was detected by the technique which had not been revealed during substantial testing of the program. Parts of this analysis are presented as an example of the use of the technique and the results are discussed.     

Graceful Object-Based Performance Evolution

Object-based design and development are thought to facilitate graceful evolution of functionality, and thus enhance the reusability of software components. They can also facilitate graceful performance evolution. The performance of a layered object-based component can be made tunable to meet changing needs by permitting clients to ‘plug in’ appropriate implementations for its constituent components through generic parameters. If the components and their constituents are carefully designed, then performance tuning is possible without direct modification to the internal details of the participating components, thus significantly lowering the cost for performance evolution. The contribution of this paper is to software practice. It explains how software engineers can build performance-tunable components using C++ templates. It includes empirical results confirming that tuning produces expected performance improvements with minimal code change. The results are especially significant because they are scalable to arbitrarily large and heavily layered software components and subsystems. © 1997 by John Wiley & Sons, Ltd.     

Design Stability Measures for Software Maintenance

The high cost of software during its life cycle can be attributer largely to software maintenance activities, and a major portion of these activities is to deal with the modifications of the software. In this paper, design stability measures which indicate the potential ripple effect characteristics due to modifications of the program at the design level are presented. These measures can be generated at any point in the design phase of the software life cycle which enables early maintainability feedback to the software developers. The validation of these measures and future research efforts involving the development of a user-oriented maintainability measure, which incorporates the design stability measures as well as other design measures, are discussed.     

A minimal mass deployable structure for solar energy harvesting on water canals

This paper produces a design for a minimal mass, deployable support structure for a solar panel covering of water canals. The results are based upon the minimal mass properties of tensegrity structures. The efficient structure is a tensegrity system which has an optimal complexity (i.e. an optimal number of members) for minimal mass. This optimal complexity is derived in this paper, along with deployable schemes which are useful for construction, repairs, for Sun following, and for servicing. It is shown that the minimal structure naturally has deployable features so that extra mass is not needed to add the multifunctional features. The design of bridge structures with tensegrity architecture will show an optimal complexity depending only on material choices and external loads. The minimization problem considers a distributed load (from weight of solar panels and wind loads), subject to buckling and yielding constraints. The result is shown to be a Class 1 Tensegrity substructure (support structure only below the deck). These structures, composed of axially-loaded members (tension and compressive elements), can be easily deployable and have many port-able applications for small spans. The focus of this paper is an application of these minimal mass tensegrity concepts to design shading devices to prevent or reduce evaporation loss, while generating electric power with solar panels as the cover. While the economics of the proposed designs are far from finalized, this paper shows a technical solution that uses the smallest material resources, and shows the technical feasibility of the concept.     

Software process representation and analysis for framework instantiation

Object-oriented frameworks are currently regarded as a promising technology for reusing designs and implementations. However, developers find there is still a steep learning curve when extracting the design rationale and understanding the framework documentation during framework instantiation. Thus, instantiation is a costly process in terms of time, people, and other resources. These problems raise a number of questions including: "How can we raise the level of abstraction in which the framework instantiation is expressed, reasoned about and implemented?" "How can the same high-level design abstractions that were used to develop the framework be used during framework instantiation instead of using source code as is done currently?" "How can we define extended design abstractions that can allow framework instantiation to be explicitly represented and validated?" We present an approach to framework instantiation based on software processes that addresses these issues. Our main goal is to represent the framework design models in an explicit and declarative way, and support changes to this design based on explicit instantiation tasks based on software processes while maintaining system integrity, invariants, and general constraints. In this way, the framework instantiation can be performed in a valid and controlled way.     

一种软件设计决策的优选方法

在软件维护和演化的工业实践中,软件设计者往往依赖主观经验或直觉对软件的设计进行修改来应对变化的需求。但这导致了决策随意性和不可重现性。结合质量属性的度量将软件设计决策进行量化,从而显式地表示、记录这些经验和直觉。并通过记录所有备选的修改,用于指导将来的软件演化。给出一个基于质量属性度量和决策历史的设计决策优选方法框架,结合一个工业应用的实例进行分析,并讨论了实际应用的效果和可能的改进。     

Data structures in context-addressed cellular memories

This report discusses the capability of an associative memory to search some useful data bases. The report utilizes a simplified cell and a collection of assembler language instructions to show how sets and trees can be searched in the memory. An OR rail and an EXCLUSIVE-OR rail are discussed in relation to their use to search-ordered and unordered sets, strings, and tree data structures. Linked data structures are also discussed. This report is oriented toward the software aspects of the associative memory to lead to further research in the design of high-level languages that utilize the capability of the rails.     

An active-architecture approach to COTS integration

COTS software products are increasingly becoming standard components for building integrated information systems. At the same time, the growth of electronic trading, turbulent market conditions, and a project-style approach to business have created a demand for information systems that can be rapidly adapted to changing business process demands. However, the ongoing development of COTS products is unpredictable as their developers and source code are rarely available. Flexible information systems use COTS components because they cost-effectively supply required component functionality. A software architecture can capture a system design as a set of interacting components and capture the role of COTS software in "implementing" certain components.     

广义系统降阶正常观测-控制器与双互质分解

首先讨论了真镇定带前通的广义系统的最小阶正常观测-控制器的设计问题,然后 基于降阶观测-控制器,明确给出了广义系统双互质分解的一种新的状态空间实现.相应的 控制器参数化可以保证是因果的,因此本文的结果更具实际意义.     

A simple method to derive minimal cut sets for a non-coherent fault tree

Minimal cut sets (or prime implicants: minimal combinations of basic event conditions leading to system failure) are important information for reliability/safety analysis and design. To obtain minimal cut sets for general non-coherent fault trees, including negative basic events or multi-valued basic events, a special procedure such as the consensus rule must be applied to the results obtained by logical operations for coherent fault trees, which will require more steps and time. This paper proposes a simple method for a non-coherent fault tree, whose top event is represented as an AND combination of monotonic sub-trees. A "monotonic" sub-tree means that it does not have both positive and negative representations for each basic event. It is proven that minimal cut sets can be obtained by a conventional method for coherent fault trees. An illustrative example of a simple event tree analysis shows the detail and characteristics of the proposed method.