Oracle工程数据库中的面向对象设计技术

数据库技术在工程领域的应用越来越广泛。同传统数据库比较，对工程数据库则有许多新的要求，如能够完成强大的建模能力和高效的面向对象的处理能力，能满足网络化和实时分布式处理能力。结合面向对象技术的关系数据库是对传统事务处理数据库的扩展，利用面向对象技术建立数据库的模型。可以在满足工程数据库的要求基础上减少创建应用的过程，是下一代数据库的一个研究方向。以主流数据库Oracle 8i为主，讨论了面向对象的技术特点，最后以实际工程数据库的对象建模为例作了阐述。     

基于正反向工程的模型驱动的软件开发过程研究

主要探讨基于正反向工程的模型驱动的软件开发过程。本文把建模过程分为系统建模与数据库建模两个过程,首先介绍了两款主流的建模工具,然后给出这两款建模工具的建模流程,并且阐述在正反向工程中选择建模工具的依据;其次,以PowerDesigner为例叙述了具体的基于建模工具的开发流程;最后,给出结论。     

基于PowerDesigner的员工医疗保险系统的数据库设计

阐述利用PowerDesigner进行数据库设计的方法,并结合员工医疗保险系统数据库设计的实际情况,重点论述如何利用PowerDesigner中的CDM和PDM建立数据库概念数据模型和物理数据模型的过程,并通过实践验证该建模工具在数据库建立方面是便利的、高效的.     

基于SPEM的CMM软件过程元模型

软件企业在实施CMM(capability maturity modelfor software)的过程中面临最主要的障碍是如何将CMM 软件过程模型转换成可实施的、体现组织过程特征的CMM实施过程模型.可以利用模型驱动架构MDA来支持CMM模型转换,其首要问题是建立CMM软件过程元模型.通过分析CMM软件过程,给出了面向CMM的软件过程工程元模型SPEM的扩展策略,提出了一个基于SPEM的CMM软件过程元模型一-SPM-CMM.该元模型既支持CMM软件过程的抽象语法和规则语义,也支持利用UML CASE工具操作CMM软件过程模型.     

UML动态模型在关系数据库操作中的应用

UML作为一种面向对象的标准建模语言,在关系数据库系统的建模领域也得到了广泛的应用.用UML为关系数据库模式建立的模型比ER模型表达力更强,但目前的UML数据库建模技术主要强调静态模型.概述了如何使用UML动态建模方法为关系数据库操作建模.在建立的框架的基础上可为原子数据库操作建模,进而为更复杂的数据库操作建模.这种方法将为用户和开发者提供对整个系统的一个统一视角,将UML的强大功能扩展到数据库领域.     

一种基于XML的数据库动态建模方法在工程飞行模拟器中的应用研究

针对目前飞行仿真中静态建立数据库模型的方法所存在的问题进行分析,提出了一种基于XML的动态自动建立数据库模型的方法.利用XML文件作为数据格式转换的中间介质,通过XML技术中的DOM生成和解析XML文件,实现了数据库模型参数在不同数据源之间的传输,然后基于得到的参数进行数据库动态建模.该方法已经在某飞行模拟器数据库开发中得到应用.     

基于Vega的虚拟漫游系统的设计与实现

分析了Vega的组成结构和视景数据库的建立.使用MultiGen建模工具构建模型、利用VC6.0开发环境和Vega的库函数,以某部队的营房建设为虚拟对象,设计并实现了虚拟漫游系统.系统可提供自动漫游、自由漫游和漫游记录以及施工过程的信息查询等功能.用户可以随意在该营区漫游.     

主动数据库规则集的Petri网建模

讨论了利用Petri网作为建模工具对主动数据库中ECA规则集的建模问题.建立了存储ECA规则状态的Pelri网子网结构,用此子网可构造出单奈规则的Petri网结构,再由单条规则的Petri网构造整个规则集的Petri网模型.结果表明,用Petri网建模能准确地表达主动数据库规则集的语义,并且有利于进一步分析规则集的动态行为特征.     

基于Creator的飞行视景数据库建模技术

讨论利用专业建模工具MultiGen Creator建立民航飞行视景数据库的相关技术,针对其中各类模型的特点提出相应的优化建模方法。结合遥感数据及地面实拍数据,以中国西部某机场为原型,建立一套完整的飞行视景数据库。实验结果表明,该数据库兼顾了实时性和逼真性的要求,在仿真系统驱动下运行良好,完全满足飞行模拟训练的要求。     

新闻发布系统的数据库建模和系统实现

本文介绍了一个典型的新闻发布系统数据库的建模和系统实现，重点是其数据库的逻辑建模，以及ERA模型在逻辑建模中的应用。在建模过程中，应用了数据库规范化理论，减少了冗余数据，提高了系统的可维护性。最后，简要说明了建立在数据库建模基础上的系统实现。     

Conceptual Data Modeling for Spatiotemporal Applications

Many exciting potential application areas for database technology manage time-varying, spatial information. In contrast, existing database techniques, languages, and associated tools provide little built-in support for the management of such information. The focus of this paper is on enhancing existing conceptual data models with new constructs, improving their ability to conveniently model spatiotemporal aspects of information. The goal is to speed up the data modeling process and to make diagrams easier to comprehend and maintain. Based on explicitly formulated ontological foundations, the paper presents a small set of new, generic modeling constructs that may be introduced into different conceptual data models. The ER model is used as the concrete context for presenting the constructs. The semantics of the resulting spatiotemporal ER model, STER, is given in terms of the underlying ER model. STER is accompanied by a textual counterpart, and a CASE tool based on STER is currently being implemented, using the textual counterpart as its internal representation.     

A methodology for the choice of the initial conditions in the model updating of welded joints using the fuzzy finite element method

The implementation of the fuzzy finite element method in the model updating procedure and its application to the modelling of welded joints has been highlighted in this paper, which describes a methodology for setting up the best possible initial conditions for the updating process. The subset selection and the estimation of the initial nominal values of the parameters, copes well with the problems of ill-conditioned matrices in the updating process. The novel aspect of this approach is the use of the fuzzy finite element method as a large scale sensitivity analysis in the preliminary updating exercise and as tool for tracking the initial lengths of the offsets employed in the partly rigid beams used for modelling the joints. The result is an updated model with physical meaning that may be used to predict the dynamics of big structures containing all kinds of different welded joints. The developed study is applied on a case study of a bus frame.     

A CASE tool for conceptual database design

The paper describes a Computer Aided Software Engineering (CASE) tool to support conceptual database modelling. One popular approach for conceptual database modelling is use of the Entity-Relationship (ER) model. The paper proposes the use of an Enhanced Entity-Relationship (EER) model for conceptual database modelling. This Enhanced Entity-Relationship model extends the Entity-Relationship model by incorporating the generalization/specialization, aggregation and categorization abstractions. The CASE tool, which is based on the Enhanced Entity-Relationship model, is known as the Enhanced Entity-Relationship Diagrammer (EERD). In addition, the CASE tool supports direct visual query and update based on the EERM.     

Adaptive restoration of complex geometry parts through reverse engineering application

After a certain number of hours of running, no two mechanical components are completely the same due to normal wear or foreign object damage. A nominal CAD model from a component designer is different from its corresponding worn one and therefore cannot be directly used for tool path generation for build up and machining repair processes. This is the main reason that most repair process used for complex geometry parts, such as gas turbine blades, is currently carried out manually and is called the “Black Art”.This paper proposes a defects-free model-based repair strategy to generate correct tool paths for build up process and machining process adaptive to each worn component through the reverse engineering application. Based on 3D scanning data, a polygonal modelling approach is introduced in this paper to rapidly restore worn parts for direct use of welding, machining and inspection processes. With this nominal model, this paper presents the procedure to accurately define and extract repair error, repair volume and repair patch geometry for the tool path generation, which is adaptive to each individual part. The tool paths are transferred to a CNC machine for the repairing trials. Further research work is performed on repair geometry extraction algorithm and repair module development within the reverse engineering environment.     

Towards the construction of workflow-suitable conceptual modelling techniques

Despite their high-level and graphical nature, workflow specifications require a significant amount of implementation detail — for example application programming interface, database access and programming mechanisms for information flow — for a more comprehensive validation than is currently possible. This is currently recognized as a deficiency in workflow conceptualization. Although conceptual modelling techniques are available which are expressive, comprehensive and precise enough, we believe, their concepts and features are not specialized enough for workflow domains. In this paper, we offer a comparative insight into techniques which characterize different aspects and approaches of workflow specifications. These are: structured process modelling, object-oriented modelling, behavioural process modelling and business-oriented modelling. In particular, we determine gaps for workflows capturing operational business transaction processing, for example those of insurance claims, bank loans and government-related registration. For technique construction, we describe five workflow suitability principles.     

Interactive Rendering of Deforming NURBS Surfaces

Non-uniform rational B-splines (NURBS) has been widely accepted as a standard tool for geometry representation and design. Its rich geometric properties allow it to represent both analytic shapes and free-form curves and surfaces precisely. Moreover, a set of tools is available for shape modification or more implicitly, object deformation. Existing NURBS rendering methods include de Boor algorithm, Oslo algorithm, Shantz’s adaptive forward differencing algorithm and Silbermann’s high speed implementation of NURBS. However, these methods consider only speeding up the rendering process of individual frames. Recently, Kumar et al. proposed an incremental method for rendering NURBS surfaces, but it is still limited to static surfaces. In real-time applications such as virtual reality, interactive display is needed. If a virtual environment contains a lot of deforming objects, these methods cannot provide a good solution. In this paper, we propose an efficient method for interactive rendering of deformable objects by maintaining a polygon model of each deforming NURBS surface and adaptively refining the resolution of the polygon model. We also look at how this method may be applied to multi-resolution modelling.     

MES系统PA模块中Oracle存储过程的设计与实现

MES项目的开发是基于三层结构的B／S模式,在基于Oracle数据库的ADO应用程序的开发过程中,为了提高执行速度和降低网络流量,往往要在应用程序中调用Oracle数据库服务器端的存储过程。本文介绍如何使用OLEDB和ADO调用返回记录集的Oracle存储过程。     

基于PowerDesigner的通信台站数据库的设计

介绍了通信台站数据库的设计过程.通过对通信保障业务流程的了解,结合通信台站的组织结构特点和其在通信保障体系中的作用,在分析了系统实际需求的基础上,总结出其涉及的实体对象及关系.利用建模工具PowerDesigner建立了概念数据模型,进而生成物理数据模型,并在物理层让它们与SQL Server 2000建立了连接,最终在SQL Server 2000中成功生成了数据库.     

基于类面向对象的模型表达与反应器模拟模型系统研究

提出了基于类面向对象的模型结构化表达方法,形成由模型框架、模型类和模型实例构成的继承层次,并应用到天然气等离子体合成乙烯乙炔反应器模拟研究中。同时考虑到模拟模型在多种条件下的优化,以星形模式设计描述模型关系。另外针对等离子体系的特点还讨论了以RGB三色素的不同合成描述温度分布的方法。最后介绍了反应器模拟模型系统的结构和功能。