Using objects to handle calculation control in finite element modelling

Interaction between objects in object-oriented finite element systems is an important issue. The technique of using agent objects is described in this paper, and is applied to equation solvers, and to overall calculation control in finite element modelling systems. In particular, the method is used for sub-structure based solution, and in multi-threaded environments. The technique enables control and communication between objects to be handled in a clear and systematic manner.     

Part-whole relations in object-centered systems: An overview

Knowledge bases, data bases and object-oriented systems (referred to in the paper as Object-Centered systems) all rely on attributes as the main construct used to associate properties to objects; among these, a fundamental role is played by the so-called part-whole relation. The representation of such structural information usually requires particular semantics together with specialized inference and update mechanisms, but rarely do current modelling formalisms and methodologies give it a specific, ‘first-class’ dignity. The main thesis of this paper is that the part-whole relation cannot simply be considered as an ordinary attribute: its specific ontological nature requires to be understood and integrated within data-modelling formalisms and methodologies. On the basis of such an ontological perspective, we survey the conceptual modelling issues involving part-whole relations, and the various modelling frameworks provided by knowledge representation and object-oriented formalisms.     

高层建筑结构CAD系统的数据模式

用面向对象的分析方法对高层建筑结构CAD系统进行了分析,通过对基本对象及其之间关系,作用的抽象,运用面向对象的设计方法建立了高层建筑 基本对象模型,采用面向对象技术和关系数据库相结合的方法,构造和初步建立了高层建筑结构的工程数据库,能够较好地解决高层建筑结构集成化CAD系统的数据组织和管理问题。     

Knowledge-based system development for assisting structural design

The development of software systems that really assist engineering design requires an important modelling effort. Computational treatment of these problems is carried out through the application of software engineering and knowledge engineering techniques. Both fields have significantly evolved during the last few years, and now advanced methodologies for the development of conventional software systems and knowledge-based systems, emphasizing different modelling principles, are available. In particular, both object-oriented modelling and knowledge modelling present useful individual characteristics that are complementary. The article analyses the need for integration of those useful modelling aspects, and presents an integrated scheme for the development of knowledge-based design systems (KBDS’s). By way of illustration, the modelling scheme proposed is applied to the development of a KBDS in a specific domain of structural design.     

Object-oriented programming for engineering software development

The representation of engineering systems in a manner suitable for computer processing is an important aspect of software development for computer aided engineering. The process of abstraction is a well-known technique for developing data representations. Objects are a mechanism for representing data using abstraction, and object-oriented languages are languages for writing programs to manipulate objects. The paper shows through examples the advantages of object-oriented programming for developing engineering software. Mathematical graphs are used as an abstraction for two problems: (1) sorting activities in a schedule and (2) ordering nodes and elements in a finite element mesh. Classes of objects are developed for generic graphs, activity procedence graphs, and graphs of elements meshes. Object-oriented program development leads to modular programs and a substantial reuse of code for the two problems.     

Comparison of Some Data Models for Engineering Objects

Many proposals using object-oriented data models for engineering objects have appeared in the literature. These data models try to represent the data in engineering systems more naturally by organizing it logically and/or physically into objects relevant to the engineering applications using the database. In this article we review and examine several of these proposed data models to identif important properties of the models. We show that none of the data models excels in all areas, but each has desirable properties.     

Object-oriented design and programming in medical decision support.

The concept of object-oriented design and programming has recently received a great deal of attention from the software engineering community. This paper highlights the realisable benefits of using the object-oriented approach in the design and development of clinical decision support systems. These systems seek to build a computational model of some problem domain and therefore tend to be exploratory in nature. Conventional procedural design techniques do not support either the process of model building or rapid prototyping. The central concepts of the object-oriented paradigm are introduced, namely encapsulation, inheritance and polymorphism, and their use illustrated in a case study, taken from the domain of breast histopathology. In particular, the dual roles of inheritance in object-oriented programming are examined, i.e., inheritance as a conceptual modelling tool and inheritance as a code reuse mechanism. It is argued that the use of the former is not entirely intuitive and may be difficult to incorporate into the design process. However, inheritance as a means of optimising code reuse offers substantial technical benefits.     

A Domain-Specific Metamodel for Multimedia Processing Systems

In this paper, we introduce 4MPS, a metamodel for multimedia processing systems. The goal of 4MPS is to offer a generic system metamodel that can be instantiated to describe any multimedia processing design. The metamodel combines the advantages of the object-oriented paradigm and metamodeling techniques with system engineering principles and graphical models of computation. 4MPS is based on the classification of multimedia processing objects into two main categories: Processing objects that operate on data and controls, and Data objects that passively hold media content. Processing objects encapsulate a method or algorithm. They also include support for synchronous data processing and asynchronous event-driven Controls as well as a configuration mechanism and an explicit life cycle state model. Data input to and output from Processing objects is done through Ports. Data objects offer a homogeneous interface to media data, and support for metaobject-like facilities such as reflection and serialization. The metamodel can be expressed in the language of graphical models of computation such as the Dataflow Networks and presents a comprehensive conceptual framework for media signal processing applications. 4MPS has its practical validation in several existing environments, including the author's CLAM framework.     

A data model for processes based on relative time

Advanced database applications such as automated manufacturing, scheduling, and computer-aided software engineering, demand an explicit representation of processes, including their decomposition into subprocesses, where subprocesses may be repeated or shared. Temporal information on these processes is inherently relative to particular temporal frames of reference, that may be different from that of a complex process containing them. We suggest the Rtime object-oriented data model in which processes are first-class citizens and complex processes are built, using standard type constructors, from their component processes. The relative timing of component processes is a key feature of the suggested model. It allows for a modular construction of complex process objects that may be repeated and shared. Standard object-oriented query languages can be used for temporal queries on processes, by providing an operator for translating timing information between different temporal frames of reference.     

面向对象数据库系统的代数模型

区别于传统的关系数据库，面向对象的数据库系统需要全新的理论及方法上的基础。我们希望能够并面向对象的数据库系统与软件工程中的形式化方法，尤其是抽象数据类型、系统的代数规范等结合起来。类似于代数数据类型理论，本文提出了对象、对象类型及抽象对象类型的代数模型。     

A relationship-based and object-oriented software for monitoring management during geotechnical excavation

The efficient management of monitoring data is necessary for large geotechnical engineering projects. The development of an information management, prediction and warning software system for geotechnical monitoring is presented in this study. Seven categories of property objects that describe the hierarchical relationships among the monitoring objects, as well as two objects that represent and manage the construction progress, are proposed based on the requirements of geotechnical monitoring, data flow and the monitoring objectives of the site. The corresponding data structure and database were established using the object-oriented method in the Visual C++ environment. The software integrated various types of information and document management schemes, including data input and processing, CAD drawing visualisation, data modelling and prediction, as well as an early warning function. The applied case studies indicate that the software system is highly flexible and reliable and can be widely applied to monitor the sites of various geotechnical construction projects, such as tunnels, underground caverns, slopes and foundation pits.     

Knowledge object modeling

Knowledge objects are an integration of the object-oriented paradigm with logic rules. The proper integration provides a flexible and powerful environment, as rule-based components provide facilities for deductive retrieval and pattern matching, and object-oriented components provide a clear intuitive structure for programs in the form of class hierarchies. Based on the knowledge object concept, this paper presents a factor-centered representation language, Factor++, which models logic rules into the object-oriented paradigm, and a scheduling system, Schedular, using the Factor++ framework The construction of Schedular demonstrates that by using an object-oriented representation of knowledge objects, users can be given explicit control of the object hierarchy to customize the system to their particular needs, which includes letting users select among scheduling and other methods. In Schedular, rules are designed as derivation rules and constraint rules. The purpose of rules is either to restrict object structure and behavior, or to infer new data from the existing data. Rules are arranged in positions so that object methods are automatically firing up if environment changes are detected by these rules     

The evaluation of access costs in object databases

Unfortunately, there is at present nothing to assist the system architect at design-time to determine whether a proposed architecture based on an object-oriented database system will perform as required. The problem is complex, the choice of suitable modelling approach difficult, and a construction of a model is often abstruse. In this paper we concentrate on a major model component: that describing the access of objects in a centralised database. We present the background for the research (modern corporate IS architectures), the choices we have made, the prototype design, and the mathematical model of the cost of object database access. We conclude the paper by describing a validation of the model and how it can be generalised. The paper has a number of objectives: first, to dispel the myth that performance modelling of object-oriented systems is an immensely difficult task; second, to show that techniques which have been in existence for some time for modelling are applicable, with some modification, to aspects of object-oriented database performance prediction; and, third, to detail a specific case study of access cost modelling which provides enough information to be replicated by other workers across a number of object-oriented database products.     

基于三维实体模型的钢结构工业厂房CAD/CAM软件后处理系统

为提高钢结构工业厂房设计的准确性、精确度和工作效率,为某钢结构工业厂房CAD/CAM软件研制出基于三维实体模型的后处理系统.该系统基于面向对象的编程技术,抽象出描述实际结构零件几何信息、结构特征和设计条件的智能型实体对象.将对象以及对象之间的层次关系和逻辑关系存储在AutoCAD图形数据库中,形成三维实体模型,用于直观、准确和完整地表现具有复杂空间关系和细部构造的真实结构;实现数据库对象的建立、编辑、查询、显示和数据整理等操作.该系统结合具体结构形式的特点,实现用于施工图设计和深化设计的全部关键功能.     

A review of object orientation and knowledge processing in office models

The purpose of this paper is to provide an analysis of the alternative modelling systems for office information systems. More specifically, we are interested in identifying the current research trends of merging office modelling ideas together with concepts that owe their origin to the object-oriented paradigm and to artificial intelligence. In this respect an office model is defined as encompassing three domains: passive office objects; dynamically defined and manipulated office procedures; and goal-directed office tasks. Following this definition we exploit the potential of using the object-oriented and knowledge representation techniques for modelling each of the three domains using evidence from real-world applications.     

A model for manufacturing systems simulation with a control dimension

The objective of this article is related to the potential improvement of computer simulation as applied to manufacturing systems. Through our contacts with the operational environment, we have observed that simulation is not used to its full potential. One remark is that existing tools are not adapted to modelling the decision process: they fall short of offering effective integration into the control process of production. Control is usually limited to scheduling and does not lend itself to practical application. In order to enhance the capabilities of computer simulation and make it more responsive to today’s industrial needs, we present a way of introducing such control into simulation by pursuing generic and applicable concepts. The core concepts that constitute the framework of our research are a global structure supporting the co-ordination and co-operation relations; a local structure presenting a typology of industrial control adapted to our needs; a control centre, the main concept used to introduce control into simulation. The modelling language used is UML and the model is implemented using the object-oriented language JAVA. An industrial application was carried out in the company Alcatel with the help of the Apollo platform.     

Development of a feature-based and object-oriented concurrent engineering system

Product information modeling is critical to the integration of mechanical CAD/CAM systems and to the implementation of a concurrent engineering system. This paper presents a recent development of a feature-based and object-oriented concurrent engineering system with its focus on a product information modeling technique implemented in the system. The technique was developed to capture product definition data including form features and their spatial relationships and to store them as an object-oriented information model during the design process. The paper also describes the implementation of the information modeling technique and its application to manufacturing process planning in an object-oriented environment.     

To model objects in information systems and user interfaces: implications for object-oriented methods

Abstract. A general way of contrasting the object-oriented to the function-oriented approach, called 'object-order' and 'function-order', is proposed in this paper. In addition, when modelling information systems, there is a third principle of ordering, 'subject-order'. Object and function-order are used to define the two approaches to modelling information systems and in human-computer interaction, in ways that are compatible to the corresponding distinction in programming. The conditions for selecting either of the two approaches are, however, not discussed here.
By means of an object-ordered method, e.g. Jackson System Development (JSD), an object-ordered model is produced, and the user interface that can be derived from the model is object-ordered too. However, other guidelines in JSD support subject-order. A function-ordered interface can be derived from the subject-ordered model. A computer system designed by means of an object-organized method may therefore obtain an interface that is partially object-ordered and partially function-ordered. Other object-oriented methods give guidelines for designing function-oriented interfaces without relating these guidelines to the model.
The system designer may benefit from having three principles of ordering when modelling a system. However, a user may be confused by an interface that sometimes gives preference to objects, sometimes to functions.     

持久对象访问的自动捕获

本文提出持久对象访问的自动捕捉技术，该技术是面向对象数据库系统在保持对象级的并发控制、版本管理和约束检查的条件下，实现持久对象与易变对象访问方式的一致性，进而实现面向对象数据库与程序设计语言的无缝结合的关键技术．