The recent development of the symmetric Galerkin approach to boundary element analysis (BEA) has been demonstrated to be superior to the collocation method for medium to large problems. This fact has been shown in bot...
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The recent development of the symmetric Galerkin approach to boundary element analysis (BEA) has been demonstrated to be superior to the collocation method for medium to large problems. This fact has been shown in both heat conduction and elasticity. Accounts of collocation multi-zone analysis techniques have also been prevalent in the literature, dealing with multiple boundary integral relations associated with portions of overall objects. This technique results in overall system matrices with a blocked, sparse, but unsymmetric character. It has been shown that multi-zone techniques can produce smaller solution times than a single zone analysis for large problems. These techniques are useful for multi-material problems as well. This paper presents an approach for combining the benefits of both techniques resulting in a Galerkin multi-zone method, that is overall unsymmetric but contains a significant amount of block symmetry. A condensation technique in the multi-zone solver is shown to exploit the symmetry of the Galerkin formulation as well as the blocked sparsity of the multi-zone technique. This method is compared to collocation multi-zone on two elasticity problems from the literature. It is concluded that an appropriate implementation of the symmetric Galerkin multi-zone BEA indeed has the potential to be superior to the collocation based multi-zone BEA, for medium to large-scale elasticity problems. (C) 1997 by John Wiley & Sons, Ltd.
A novel framework for multi-resolution optimization methodology is developed for parallel/distributed simulation environments. The architecture is constructed with multiple clusters hierarchically arranged with each l...
A novel framework for multi-resolution optimization methodology is developed for parallel/distributed simulation environments. The architecture is constructed with multiple clusters hierarchically arranged with each level solving different degrees of abstracted problems. Creation and deletion of clusters are executed dynamically during the search operation. A higher level cluster evaluates a wider search space with low resolution, whereas a lower level cluster investigates a smaller search space which is more promising for containing the global optimum. Each cluster consists of a controller (expert system) and agents (GA), where the agents evaluate the parameters of the problem of variable structure which allocates more computing resources to promising search subspaces. This article describes the prototyping of the hierarchical distributed genetic algorithms (HDGA) in an object-oriented simulation environment and provides preliminary experimental results. The results are promising, and many theoretical questions concerning robustness of the approach are raised for future research. (C) 1996 Academic Press, Inc.
A multiresolutional search paradigm is employed to design optimal fuzzy logic controllers in a variable structure simulation environment, The initial search space is evaluated with a coarse resolution and some of the ...
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A multiresolutional search paradigm is employed to design optimal fuzzy logic controllers in a variable structure simulation environment, The initial search space is evaluated with a coarse resolution and some of the subspaces are selected as candidate regions for global optimum, New optimization processes are then created to investigate the candidate search spaces in detail, a process which continues until a solution is found, This search paradigm was implemented using hierarchical distributed genetic algorithms (HDGA's)-search agents solving different degrees of abstracted problems. Creation/destruction of agents is executed dynamically during the operation based on their performance, In the application to fuzzy systems, the HDGA investigates design alternatives such as different types of membership functions and the number of the fuzzy labels, as well as their optimal parameter settings, all at the same time, This paradigm is demonstrated with an application to the design of a fuzzy controller for an inverted pendulum.
This article presents an approach to embedding expert systems within an object oriented simulation environment. The basic idea is to create classes of expert system models that can be interfaced with other model class...
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This article presents an approach to embedding expert systems within an object oriented simulation environment. The basic idea is to create classes of expert system models that can be interfaced with other model classes. An expert system shell is developed within a knowledge-based design and simulation environment which combines artificial intelligence and systems modeling concepts. In the given framework, interruptible and distributed expert systems can be defined as components of simulations models. This facilitates simulation modeling of knowledge-based controls for flexible manufacturing and many other autonomous intelligent systems. Moreover, the structure of a system can be specified using a recursive system entity structure (SES) and unfolded to generate a family of hierarchical structures using an extension of SES pruning called recursive pruning. This recursive generation of hierarchical structures is especially appropriate for design of multilevel flexible factories. The article illustrates the utility of the proposed framework within the flexible manufacturing context.
The objectives of Human engineering (HE) are generally viewed as increasing human performance, reducing human error, enhancing personnel and equipment safety, and reducing training and related personnel costs. There a...
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The objectives of Human engineering (HE) are generally viewed as increasing human performance, reducing human error, enhancing personnel and equipment safety, and reducing training and related personnel costs. There are other benefits that are thoroughly consistent with the direction of the Navy of the future, chief among these is reduction of required numbers of personnel to operate and maintain Navy ships. The Naval Research Advisory Committee (NRAC) report on Man-Machine Technology in the Navy estimated that one of the benefits from increased application of man-machine technology to Navy ship design is personnel reduction as well as improving system availability, effectiveness, and safety The objective of this paper is to discuss aspects of the human engineering design of ships and systems that affect manning requirements, and impact human-performance and safety The paper will also discuss how the application of human engineering leads to improved performance, and crew safety, and reduced workload, all of which influence manning levels. Finally, the paper presents a discussion of tools and case studies of good human engineering design practices which reduce manning.
A multiparadigm approach for the solution of ordinary differential equations is proposed. The approach consists of augmenting a numerical continuous simulation environment with a knowledge-based system that can provid...
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Advances in massively parallel platforms are increasing the prospects for high performance discrete event simulation. Still the difficulty in parallel programming persists and there is increasing demand for high level...
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ISBN:
(纸本)9780818675393
Advances in massively parallel platforms are increasing the prospects for high performance discrete event simulation. Still the difficulty in parallel programming persists and there is increasing demand for high level support for building discrete event models to execute on such platforms. We present a parallel DEVS-based (Discrete Event System Specification) simulation environment that can execute on distributed memory multicomputer systems with benchmarking results of a class of high resolution, large scale ecosystem models. Underlying the environment is a parallel container class library for hiding the details of message passing technology while providing high level abstractions for hierarchical, modular DEVS models. The C++ implementation working on the Thinking Machines CM-5 demonstrates that the desire for high level modeling support need not be irreconcilable with sustained high performance.
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