In this paper we consider the problem of multidisciplinary design and optimization (MDO) of a diffuser for a steady, incompressible magnetohydrodynamic (MHD) flow. Given a fixed diffuser shape, the optimizer should fi...
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In this paper we consider the problem of multidisciplinary design and optimization (MDO) of a diffuser for a steady, incompressible magnetohydrodynamic (MHD) flow. Given a fixed diffuser shape, the optimizer should find the distribution of the wall magnets that will maximize the static pressure increase from inlet to outlet. This design problem is solved through the use of a genetic algorithm based optimization program coupled with a finite element based MHD simulation program. For MHD simulation, a least-squares finite element method (LSFEM) based program has been developed. The use of LSFEM allows the use of equal order approximation functions for all unknowns and is stable for high Reynolds numbers. Optimization was accomplished using a micro-genetic algorithm (GA) based program. The micro-GA is capable of searching the design space with a population much smaller than that required by classical GA. The optimization was performed on a parallel computer composed of commodity PC components. Results show that an applied magnetic field with the proper strength and distribution can significantly improve the static pressure rise over the case of no magnetic field. (C) 2001 Elsevier Science B.V. All rights reserved.
This paper describes a Wrapper Generator for wrapping high performance legacy codes as Java/CORBA components for use in a distributed component-based problem-solving environment. Using the Wrapper Generator we have au...
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ISBN:
(纸本)9780780398023
This paper describes a Wrapper Generator for wrapping high performance legacy codes as Java/CORBA components for use in a distributed component-based problem-solving environment. Using the Wrapper Generator we have automatically wrapped an MPI-based legacy code as a single CORBA object, and implemented a problem-solving environment for molecular dynamicsimulations. Performance comparisons between runs of the CORBA object and the original legacy code on a cluster of workstations and on a parallel computer are also presented.
Asynchronous parallelcomputing can result in high message generation rates, thus triggering network congestion. We characterize the communication requirements of a large class of supercomputing applications falling u...
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Asynchronous parallelcomputing can result in high message generation rates, thus triggering network congestion. We characterize the communication requirements of a large class of supercomputing applications falling under the category of fixed-point problems amenable to solution by parallel iterative methods. In particular, we concentrate on asynchronous iterative algorithms whose communication/computation ratio is especially high resulting in degraded effective throughput if communication is not managed properly. Second, we show the effects of network contention and asynchrony on application performance in a local-area network environment and investigate methods of solution. Our approach is based on a congestion control algorithm called 'warp control' whose adaptive properties are exploited to yield significant performance enhancements when network contention is high. Although tested in a LAN environment for experimental control purposes, our solution follows the end-to-end paradigm and refrains from exploiting special MAC-layer properties to achieve applicability to general WAN environments. Third, we provide a framework wherein efficient congestion control can be facilitated, encompassing methods acting at the application layer as well as the transport/network layer, with emphasis on application-driven control. We conclude with a discussion of our experimental results and special issues arising in high-bandwidth ATM networks. (C) 1997 Elsevier Science B.V.
computing resources which are transparently available to the user via networked environments are commonly called a metacomputer. In this sense, a metacomputer is a network of heterogeneous, computational resources lin...
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computing resources which are transparently available to the user via networked environments are commonly called a metacomputer. In this sense, a metacomputer is a network of heterogeneous, computational resources linked by software in such a way that they can be used as easily as a single computational unit. During the last few years our work has been concentrated on developing methods and tools to provide a transparent and vendor independent hardware management system to the users. Solving this problem up to a high abstraction level will bring the idea of metacomputing a large step closer to its fruition. After reviewing the metacomputing approaches in Europe and the States, we will break down the task force into almost independent units. One of these, the resource access and allocation problem, the project computing Center Software was focused on. This paper takes a closer look at CCS. Its underlying model which uses abstract views for specifying system components and the general purpose Resource Description Language will be sketched. We will explain how it is possible to support Wide-Area Network access and unstable connection lines. Afterwards, we will present the system and vendor independent batch processing facility usable for arbitrary programming environments. On-going activities and an enhancement of the CCS methodology to solve a core problem in wide-area metacomputing will conclude this paper.
The typical workstation in a LAN is idle for long periods of time. Within the concept of a hypercomputer this free, distributedcomputing power can be placed at the disposal of the user. The main problem with this app...
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The typical workstation in a LAN is idle for long periods of time. Within the concept of a hypercomputer this free, distributedcomputing power can be placed at the disposal of the user. The main problem with this approach is the permanently changing load situation in the network. We show that heterogeneous partitioning with respect to the load situation at startup and dynamic load balancing throughout the entire computation are essential techniques for obtaining high efficiency with the hypercomputer approach. We describe a parallel programming platform called THE PARFORM, which supports these two features and therefore proves faster than related approaches. Performance measurements and a scalability model for an explicit finite difference solver of a partial differential equation conclude the paper.
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