A C++ implementation of a finite element class system and its links to a graphical model of a structure are described. The principles underlying the finite element and graphical class systems are outlined, together wi...
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A C++ implementation of a finite element class system and its links to a graphical model of a structure are described. The principles underlying the finite element and graphical class systems are outlined, together with the reasoning behind the design. Two of the key points are (i) the finite element classes have a "lean" interface;(ii) the finite element objects (e.g. nodes and elements) are distributed around the graphical model objects (e.g. points, lines, sub-structures). Some of the advantages of adopting such an approach are outlined with reference to user interaction, mesh generation, and sub-structuring. (C) 1999 Elsevier Science Ltd and Civil-Comp Ltd. All rights reserved.
One task expected for the 21 st century is that when designing a system S , the fact will be respected that in it an information processing component C will exist, influencing the other components of S . In case C is ...
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One task expected for the 21 st century is that when designing a system S , the fact will be respected that in it an information processing component C will exist, influencing the other components of S . In case C is intended to simulate (using a simulation model m ), the simulation model used during the design of the system has to contain m . Especially the production systems and the logistic ones can serve as transparent illustrations of such a "model nesting", presenting the obstacles related to it and the surmounting of them.
Symbolic approaches to assist in the development of finite element formulations have been used since the late 1970s. Today, the symbolic mathematical software such as Mathematica, Maple, etc., has proved to be helpful...
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Symbolic approaches to assist in the development of finite element formulations have been used since the late 1970s. Today, the symbolic mathematical software such as Mathematica, Maple, etc., has proved to be helpful when testing formulations. In earlier work, the authors introduced a new way of integrating naturally symbolic concepts in numerical finite element codes, taking advantage of an object-oriented code organization. In this paper, we wish to prove on practical examples that the proposed approach is very attractive and promising today, lending to an alternative,way of conceiving finite element,rent codes. After presenting a state-of-the-art of symbolic approaches for finite element developments, we first give a practical application of symbolic developments (for discontinuous space-time formulations), and then examples of Computer Aided Software Engineering tools that can be introduced into such a finite element environment.
object-oriented (OO) systems development theory has rapidly evolved. Generally, there is a concern about the current inconsistent state of OO theory. There is a lack of a shared understanding of the basic concepts and...
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object-oriented (OO) systems development theory has rapidly evolved. Generally, there is a concern about the current inconsistent state of OO theory. There is a lack of a shared understanding of the basic concepts and of a common vocabulary for discussing them. Although recent efforts have contributed to organizing OO concepts, a complete model of OO based on the areas of analysis, design and programming is still lacking. This study develops and applies an approach to build such a definition of OO concepts using metamodeling. Metamodels of existing OO methodologies were created and then integrated into a single metamodel that defines OO concepts and their relationships. A number of useful applications of this OO metamodel are proposed, including in methodology development and selection. The main contribution of this approach is its focus on bridging the gap that exists between the OO analysis and design area and the area of OO programming. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.
For some time now, NGC has been developing on-line transient stability analysis tools. A particular need is the development of a facility that will help in the monitoring of intertrip schemes. This paper, therefore, d...
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For some time now, NGC has been developing on-line transient stability analysis tools. A particular need is the development of a facility that will help in the monitoring of intertrip schemes. This paper, therefore, describes the features of the General Intertrip Monitoring System (GIMS) facility developed for the NGC system and currently running on-line at the National Control Centre. The paper also demonstrates the operational experience in using this tool.
The text deals with the developement of an integrated object-oriented network - and modal split-model. The subtasks are a multimode network model, alternative paths within traffic networks, a multi-paths-algorithm, th...
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The text deals with the developement of an integrated object-oriented network - and modal split-model. The subtasks are a multimode network model, alternative paths within traffic networks, a multi-paths-algorithm, the combination of the defined subtasks within an integrated modal-split-model and the implementation of the developed model and algorithms. The subtasks, problems and solutions are shortly described.
Real-time systems engineers have, for some time, identified Java as an attractive programming language, but have been unable to exploit its benefits as it cannot provide the fundamental temporal predictability require...
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Real-time systems engineers have, for some time, identified Java as an attractive programming language, but have been unable to exploit its benefits as it cannot provide the fundamental temporal predictability required. However, this is all changing, as academic and industrial experts propose extensions to the Java environment. On the basis of this study, significant agreement has been found in how some of the critical areas of Java may be addressed for real-time, such as memory management and portability. However, areas such as scheduling and interprocess communication, have been contentious, even among expert opinion. This paper considers the current status of this exciting and emerging, soon to become, real-time programming language, with a focus on process control application. In addition, it will overview a preliminary performance assessment of the alleged real-time java virtual machine (JVM) from NewMonics Inc and compared upfront with the Sun JVM.
In the mid 1980s, the UK Science and Engineering Research Council funded a number of projects to develop computer-aided control system design (CACSD) environments. The flagship project was ECSTASY (Environment for Con...
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In the mid 1980s, the UK Science and Engineering Research Council funded a number of projects to develop computer-aided control system design (CACSD) environments. The flagship project was ECSTASY (Environment for Control System Theory and SYnthesis), a database-mediated framework for hosting a number of popular control systems design tools. As the ECSTASY project neared its completion, some of the most urgently requested features appeared in rival commercial packages, and the short-falls in tool provision that ECSTASY was designed to address apparently went away. Using as a benchmark the capabilities of the current generation of the popular CACSD package MATLAB, the prescience of the original ECSTASY proposal will be demonstrated. A couple of areas that the environment excelled in, the use of a common information model and common user interface, will be discussed in the context of recent work done in the University of Wales and elsewhere. Finally, two topics of particular interest to the authors, the proposed standard reference model for computer-aided control engineering and an object-oriented Unified Infonnation Model for CACSD will be revisited in the light of recent developments in internet computing.
Statistical environments such as S, R, XLisp-Stat, and others have had a dramatic effect on the way we, statistics practitioners, think about data and statistical methodology. However, the possibilities and challenges...
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Statistical environments such as S, R, XLisp-Stat, and others have had a dramatic effect on the way we, statistics practitioners, think about data and statistical methodology. However, the possibilities and challenges introduced by recent technological developments and the general ways we use computing conflict with the computational model of these systems. This article explores some of these challenges and identifies the need to support easy integration of functionality from other domains, and to export statistical methodology to other audiences and applications, both statically and dynamically. Existing systems can be improved in these domains with some already implemented extensions (see Section 5). However, the development of a new environment and computational model that exploits modern tools designed to handle many general aspects of these challenges appears more promising as a long-term approach. We present the architecture for such a new model named Omegahat. It lends itself to entirely new statistical computing paradigms. It is highly extensible at both the user and programmer level, and also encourages the development of new environments for different user groups. The Omegahat interactive language offers a continuity between the different programming tasks and levels via optional type checking and seamless access between the interpreted user language and the implementation language, Java. Parallel and distributed computing, network and database access, interactive graphics, and many other aspects of statistical computing are directly accessible to the user as a consequence of this seamless access. We describe the benefits of using Java as the implementation language for the environment and several innovative features of the user-level language which promise to assist development of software that can be used in many contexts. We also outline how this architecture can be integrated with existing environments such as R and S. The ideas are drawn from work wit
We present a constraint system, OF, of feature trees that is appropriate to specify and implement type inference for first-class messages. OF extends traditional systems of feature constraints by a selection constrain...
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We present a constraint system, OF, of feature trees that is appropriate to specify and implement type inference for first-class messages. OF extends traditional systems of feature constraints by a selection constraint x z, "by first-class feature tree" y, which is in contrast to the standard selection constraint x[f]y, "by fixed feature" f. We investigate the satisfiability problem of OF and show that it can be solved in polynomial time, and even in quadratic time if the number of features is bounded. We compare OF with Treinen's system EF of feature constraints with first-class features, which has an NP-complete satisfiability problem. This comparison yields that the satisfiability problem for OF with negation is NP-hard. Further we obtain NP-completeness, for a specific subclass of OF with negation that is useful for a related type inference problem. Based on OF we give a simple account of type inference for first-class messages in the spirit of Nishimura's recent proposal, and we show that it has polynomial time complexity: We also highlight an immediate extension of this type system that appears to be desirable but makes type inference NP-complete.
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