An object design framework for structural engineering

Object-oriented principles have introduced several useful concepts for developing complex software systems. As a result, several methodologies have been suggested for the overall design of software systems based on these concepts. Methodologies and frameworks for designing objects that are to be part of the software systems are currently lacking. This paper proposes anobject design framework andmethodology, which utilizes the object-oriented concepts, for planning, organizing and designing structural engineering design objects. Design objects in an integrated structural engineering system are complex and often related to each other in various different ways. The paper also identifies several important relationships among structural engineering design objects. These relationships serve as communication channels through wich design objects send messages to and receive responses from each other. Several examples, drawn from reinforced concrete structures, will be presented to demonstrate the object design methodology and to illustrate how the framework is effective in reducing the complexity of design objects in an integrated structural engineering system.     

Supporting engineering applications by new data base processing concepts—An experience report

Data base management systems for nonstandard applications (nonstandard data base systems, NDBS), in particular for engineering applications, nowadays constitute one of the most important challenges in the area of data base research. Some major obstacles are concerned with problems of modeling and processing complex engineering objects. Some new system architectures have been proposed, and appropriate concepts for handling the new types of application objects have been developed over the past few years.Based on PRIMA, an NDBS-kernel prototype implementation, we motivate a workstation-oriented architecture for NDBS application systems. We explain a prototypical application system in the environment of VLSI-chip design, which serves as a practical examples in handling complex objects. Analyzing the weaknesses of this initial approach, we derive general concepts for application linkage, discussing, in particular, key issues for an efficient object processing and language binding.     

An aide for instruction on integrated engineering design and support

Effective management of engineering information is critically needed for the design of future complex engineering systems. Yet engineers are not trained in engineering data base management concepts. To help address this issue, a prototype integrated design system has been developed for the Air Force to aide research and instruction on key integration concepts, including (1) the use of a shared data base to eliminate redundancies and inconsistencies; (2) the use of a relational data base management system to store, locate, and retrieve data from the shared data base; (3) the development of interfacing programs to act as interpreters between the application programs and the common data base; and (4) the role of executive software to manage the integrated system. Key software used includes a computer-aided design system, a structural analysis program, various graphics packages, and a relational data base management system. To assess system flexibility, additional programs were added to the system. The design of the data base proved to be an important step in this implementation. Several methodologies useful in the design of the data base were investigated and subsequently used to organize the data base for the integrated design system. Results discussed include system development, and applications, as well as the effectiveness of the integrated system's configuration.     

Version management needs for structural engineering design

As design objects are created during the design process, it is not sufficient to represent only a single current state of each object. Instead, it will usually be necessary to represent a number of past and current states, existing parallel to each other at various design stages. This requirement has led to the development of various schemes to help manage and control multiple occurrences of a design object.In this paper versions of structural engineering design objects are defined and a scheme for organizing these versions is proposed. A design for a version manager in an object-based design system is then presented. The manager has limited capabilities but can be used as a step toward defining a more complete version management and control system.     

A flexible and extensible approach to automated CAD/CAM format classification

There are hundreds of distinct 3D, CAD and engineering file formats. As engineering design and analysis has become increasingly digital, the proliferation of file formats has created many problems for data preservation, data exchange, and interoperability. In some situations, physical file objects exist on legacy media and must be identified and interpreted for reuse. In other cases, file objects may have varying representational expressiveness.We introduce the problem of automated file recognition and classification in emerging digital engineering environments, where all design, manufacturing and production activities are “born digital.” The result is that massive quantities and varieties of data objects are created during the product lifecycle.This paper presents an approach to automated identification of engineering file formats. This work operates independent of any modeling tools and can identify families of related file objects as well as variations in versions. This problem is challenging as it cannot assume any a priori knowledge about the nature of the physical file object. Applications for these methods include support for a number of emerging applications in areas such as forensic analysis, data translation, as well as digital curation and long-term data management.     

Software concept for checking engineering designs for conformance with codes and standards

As we progress toward formalizing models for the knowledge used in the design process, we must also consider the structure of systems that can utilize and operate on the knowledge models. Engineering systems of the future will be comprised of many separate but integrated components. In the systems of the 1970s tightly coupled system integration was achieved through hand coding and through the introduction of data base management. In the next generation of systems it will not be possible to express easily the interaction between systems in the form of handwritten codes. A rule-based approach may be a better way to achieve loose coupling of complex systems. A prototype system for checking designed components for conformance with applicable standards is described in this paper. The integrated system consists of a code conformance checking package, a structural analysis package, an engineering data base management system, a production rule processing system, and an appropriate user interface. The system structure and the representation of the knowledge is emphasized.     

复杂对象版本的数学模型

复合组合对象的版本管理机制是工程数据库系统的重要组成部分。本文以支持工程设计方案的修改，选择及配置为主要目的，对ＣＯＨＯＲ复杂对象进行了版本扩展，提出了复杂对象版本的数学模型，并从语义角度讨论了ＤＡＴＦＥＡ版本管理系统的版本模型和基本操作等问题。     

C＋＋对象的持久化中的问题和解决方案

多媒体智能数据库系统ＭＩＤＳ（ｍｕｌｔｉｍｅｄｉａｉｎｔｅｌｌｉｇｅｎｔｄａｔａｂａｓｅｓｙｓｔｅｍ）是一个对象数据库管理系统．它的数据库编程语言是Ｐ＋＋，Ｐ＋＋个语言是一种基于Ｃ＋＋的语言．作者在Ｐ＋＋的实现过程中遇到了以下问题：首先，Ｃ＋＋的指针有二义性，它无法在语义上区分成员指针和引用指针，以及易失性指针和持久性指针，从而给事务管理中的对象加锁及其它方面带来问题．其次，具有虚拟函数或虚拟基类的对象中含有指向内存中的指针，而这些指针不是由程序员定义的．如果Ｃ＋个对象被持久化，这些指针在不同的程序调用中有可能无效．最后，如果作者用文件系统调用来存储对象，那么必须要设计复杂的Ｃａｃｈｅ系统和做大量对象的格式转化工作，这需要大量的空间和时间，所以他们采用了另外的一种方法──基于虚拟内存空间映射的存储方案．     

面向对象工程数据库管理系统O2S并发事务模型

Ｏ２Ｓ是我们在ＳＵＮ工作站上开发的一面向对象工程数据库管理。本文针对工程应用域事务的嵌套性，长时性，数据库逻辑分区性和涉及数据量大的四个显著特点，阐述了Ｓ２Ｓ的事务管理模型。对工程域事务的管理，数据库的恢复和封锁技术进行了讨论。     

DrawCAD: using deductive object‐relational databases in CAD

Computer‐aided design (CAD) involves the use of computers in the various stages of engineering design. CAD has large volumes of data with complex structures that need to be stored and managed effectively and properly. Database systems provide general purpose programs that can be used to access and manipulate large amounts of data stored in the database. They also provide an independence between the program accessing data and the database. It is therefore important to use database systems to store CAD data in the most efficient and effective manner for easy retrieval and better management. Graphical objects can be created, in CAD, by reusing previously created objects. The data of these objects have references to the other objects they contain. Deductive object‐relational databases not only provide direct support for the effective storage and efficient access to large amounts of data with complex structures on disk, but also perform the inferences and computations to obtain the complete data of graphical objects that reuse other objects. They should be able to play a major role in CAD systems. This is the idea behind the development of the DrawCAD system. DrawCAD is a CAD system built on top of the Relationlog object‐relational deductive database system. It facilitates the creation of graphical objects by reusing previously created objects. The DrawCAD system illustrates how CAD systems can be developed, using database systems to store and manage data and also perform the inferences and computations that are normally performed by the application program. Copyright © 2003 John Wiley & Sons, Ltd.     

A database model for object dynamics

To effectively model complex applications in which constantly changing situations can be represented, a database system must be able to support the runtime specification of structural and behavioral nuances for objects on an individual or group basis. This paper introduces the role mechanism as an extension of object-oriented databases to support unanticipated behavioral oscillations for objects that may attain many types and share a single object identity. A role refers to the ability to represent object dynamics by seamlessly integrating idiosyncratic behavior, possibly in response to external events, with pre-existing object behavior specified at instance creation time. In this manner, the same object can simultaneously be an instance of different classes which symbolize the different roles that this object assumes. The role concept and its underlying linguistic scheme simplify the design requirements of complex applications that need to create and manipulate dynamic objects. Edited by D. McLeod / Received March 1994 / Accepted January 1996     

面向对象数据库中对象的存储和操作算法

面向对象数据库管理系统的核心是把现实世界的描述为对象，数据库的存储，操作和管理都以对象为依据。对象可以是简单的，也可以是复杂的。复杂对象中引用了其它的对象。结合我们开发的面向对象的工程数据库管理系统论述了对复杂对象的物理存储，内存映象方法和对象操作方法的实现技术。     

基于模板的冷冲模CAD系统中的数据模型研究

工程数据模型决定了对象的存储方式和访问方式,该文讨论了在Windows平台上开发的基于模板的冷冲模CAD系统的数据模型,将知识、规则等语义信息与面向对象技术相结合,提出了语义对象数据模型。在模板中将设计信息按照对象之间的关系组织起来,加强了对数据的管理,并能表达多种复杂的语义等知识信息,同时介绍了工程数据库系统数据模型的逻辑设计和系统的体系结构。     

An object-oriented database management system for computer-aided design of tall buildings

An effective database and database management system is the key to the success of an integrated approach to software engineering applications in general, and Computer-Aided Design (CAD) for structural applications in particular. Due to the inherent nature of CAD data such as dynamic modeling, a wide range of data types, large data volume, etc., the traditional database models, such as hierarchical, network and relational models, are unable to handle the aforementioned applications satisfactorily. An object-oriented data modeling is known to be the most effective approach. However, many of the commercial object-oriented databases are designed for information management, and they are inadequate for CAD application due to the different features of the object-hierarchy and varying data management objectives during the design cycles. This paper presents a hierarchical index-based object-oriented database management model for CAD applications. To deal with the object hierarchy encountered in CAD for the design of tall buildings, the proposed database consists of several salient features: a hierarchical object model, its related storage structure, a data dictionary, a class factory and an index system. The proposed database management model has been implemented into an integrated CAD system for design application of tall buildings.     

面向对象的工程设计专家系统开发工具OOESTOOL

本文介绍了一个用C 语言开发的支持面向对象功能的工程设计专家系统开发工具OOESTOOL。我们以面向对象的软件开发方法分析并设计OOESTOOL的组成和结构,初步建立了面向对象的知识表示机制和面向对象推理系统,并讨论了面向对象的工程数据库的设计与实现。     

对象存储系统形式化研究

对象存储系统是近来兴起的存储领域研究热点，它改变了传统的存储模式，用对象接口取代了传统的块接口。作为下一代互联网存储模式的关键技术——对象存储，它的出现使得海量信息存储、数据异构灵活共享、存储系统的可扩性、信息安全等问题迎刃而解。对象作为对象存储系统的基本单位，它的管理将是系统管理的关键。为了更好地研究对象存储系统对象的管理，本文对对象的形式化做了系统的研究。首先根据对象存储系统的实际给出了对象存储系统中对象的形式化描述；接着我们给出了对象存储系统的形式化描述；最后讨论了对象存储系统中对象间的关系，并通过这些对象间的关系推导出一种对象存储系统模式。对象存储系统的形式化研究将有助于我们对对象管理做进一步研究。     

A communication model for structural design objects. I: Channels and medium

Design objects of integrated engineering systems frequently communicate data and information among each other. The data to be communicated is usually characterized by considerable variability in format and structure. This warrants the development of a uniform mechanism for communicating data and information among design objects. Recent advances in the object-oriented paradigm and the emerging agent-oriented paradigm gave promise to the development of such mechanism for inter-object communication that was difficult to achieve previously. This paper and its companion paper address this issue and propose an object communication model. Specifically, this paper identifies the communication channels among structural engineering design objects and proposes a communication medium based on messenger object for conveying message arguments and responses. The unified modeling language (UML) is used to present the model and its ingredients. A note on implementation of the messenger object, using C++ STL, is shown. Examples to demonstrate the capability of the communication model are presented. The proposed communication model will impose a uniform and consistent mechanism for communicating data and information among design objects. Other ingredients of the communication model such as performatives and protocols are addressed in the companion paper.     

一个面向对象工程数据库管理系统的总体设计

本文提出了一个适合ＣＡＤ工程应用的面向对象数据模型，在此基础上介绍了一个面向对象工程数据库管理系统的总体设计。最后，通过对工程数据中的四种常用典型对象类型的分析，简要地讨论了系统对象类的实现方法。     

A generic, object-oriented case-knowledge representation scheme, and its integration into a wider information management scenario

Abstract: A knowledge base management system (KBMS) realises a combination of techniques found in database management systems and knowledge-based systems. At the data model and knowledge representation level, many systems of this kind constitute a marriage of the relational data model and the rule-based reasoning. Experience has shown that either approach is restricted in the way it can express the demanding information and knowledge structures required for applications like decision support systems. Two new technologies offer an exciting new integrated approach to knowledge management. Object-oriented database management systems (OODBMS) provide an object model that supports powerful abstraction mechanisms to facilitate the modelling of highly structured information. Whereas case-based reasoning (CBR) systems are knowledge bases which organise their capabilities around a memory of past cases and the notion of similarity. Both types of system are built upon two fundamental concepts: 1) the retrieval of entities with potentially complex structure, called objects in the former, and cases in the latter type of system; 2) the organisation of those entities in collections with common characteristics. In an OODBMS such collections are termed extents, and in CBR they are usually called categories. In either system, the conceptual meta notion to represent both, objects as well as extents, and cases as well as categories, is the class.
Revolving around a Conceptual Case Class and extending a standard object model, this paper proposes a novel and general approach to represent case-knowledge and to build KBMSs. The work presented here is a spin-off of the design of an object query language within the ESPRIT project Lynx.