The merging particle filter (MPF) is a population-based quasi-Bayesian algorithm for solving sequential Bayesian problems. The MPF algorithm at each time step consists of three procedures: evaluation of fitness to obs...
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ISBN:
(纸本)9781424481262
The merging particle filter (MPF) is a population-based quasi-Bayesian algorithm for solving sequential Bayesian problems. The MPF algorithm at each time step consists of three procedures: evaluation of fitness to observation, selection of samples in the population, and merging among multiple samples. The MPF has a certain similarity to evolutionary algorithms except that it is based on Bayesian approach and it provides a posterior probability density function rather than a optimum value. Population-based algorithms including the MPF is easy to implement on parallel computing systems. However, when we implement the MPF in a parallelcomputing system, much communication occurs between processing elements (PEs) and it could spoil the computational efficiency. In order to reduce the communication between PEs, we propose a bi-level hierarchical algorithm in which the MPF is locally performed in each PE and and communication between different PEs are treated separately. Although this hierarchical algorithm is similar to the island model in the genetic algorithm, it is derived on the basis of the Bayesian framework. We also confirm the efficiency of the proposed algorithm by an experiment of state estimation with a simple one-dimensional system model.
Operation stages of parallel computing systems development are considered in article. The basic accent is made on the step of computing process organization. The efficiency of parallel mathematical algorithms library ...
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ISBN:
(纸本)9789531841306
Operation stages of parallel computing systems development are considered in article. The basic accent is made on the step of computing process organization. The efficiency of parallel mathematical algorithms library development is substantiated on the example of linear equations set solution by Kramer method paralleling.
Multi-objective evolutionary algorithms have been shown to be effective optimization tools to search the complex tradeoff spaces of satellite constellation design. Often, the metrics that make up the design tradeoff r...
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Multi-objective evolutionary algorithms have been shown to be effective optimization tools to search the complex tradeoff spaces of satellite constellation design. Often, the metrics that make up the design tradeoff require lengthy function evaluation time, resulting in a decreased utility of serial multi-objective evolutionary algorithms. In this research, the authors implement two parallel processing multi-objective evolutionary algorithm paradigms, the master-slave and island models, on a heterogeneous system of processors and operating systems. The efficiency and effectiveness of each approach is studied in the context of a regional coverage design problem. The island scheme outperforms the master-slave model with respect to efficiency. A study of the search dynamics for each paradigm demonstrates that both reliably meet the goals of multi-objective optimization (progressing toward the Pareto-optimal front while maintaining a diverse set of solutions). A key conclusion of this research is that both paradigms provide excellent approximations of the true Pareto frontier using a single seed, and when combined across multiple trial runs, they find nearly the entire set of Pareto-optimal solutions.
Operating system virtualization has recently become a popular technique to achieve better resource utilization in so-called '' server farm '' environments. This technique provides a virtual hardware in...
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ISBN:
(纸本)9780889866379
Operating system virtualization has recently become a popular technique to achieve better resource utilization in so-called '' server farm '' environments. This technique provides a virtual hardware interface on top of which one can run multiple instances of popular operating systems. The Xen Virtual Machine Monitor is an implementation of operating system virtualization that supports live migration, the transfer of a virtual operating system from one physical machine to another with minimal down time. We have utilized this capability to implement a monitoring and dynamic reconfiguration daemon that attempts to equalize the load on all host nodes in a group of machines running Xen. We have also implemented a simulator for testing balancing algorithms. Experiments using these tools have provided insight into the redistribution of virtualized operating systems and how this differs from the more thoroughly-studied problem of process-level load balancing.
In this study we evaluate and compare the performance of our load balancing technique on irregular P2P systems embedded in two regular topologies: 1) Hypercube and 2) TreeP. Hypercube is one of the most studied interc...
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ISBN:
(纸本)9780889866379
In this study we evaluate and compare the performance of our load balancing technique on irregular P2P systems embedded in two regular topologies: 1) Hypercube and 2) TreeP. Hypercube is one of the most studied interconnection topologies and exhibits powerful interconnection features, while TreeP is Tree-based P2P network architecture and is based on a tessellation of a 1-D space. The load balancing technique employed is a two step strategy. In the first phase, it maps any irregular network topology to a regular one. In the second phase the load is balanced among the nodes using PSLB algorithm. In this paper we study and compare the performance of this two-step strategy on hypercube and TreeP topologies. This strategy is proven to be efficient and does not introduce a considerable overhead as shown in the experimental results.
This paper considers defect tolerance issues for parallel computing systems based on a new interconnection network, namely "Tori connected mESHes (TESH)." Key features of this network are the following: It i...
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This paper considers defect tolerance issues for parallel computing systems based on a new interconnection network, namely "Tori connected mESHes (TESH)." Key features of this network are the following: It is hierarchical, thus allowing exploitation of computation locality and systematic expansion up to a million processors, and it appears to be well-suited for VLSI/ULSI realization, including 3D implementation. The goal here is to present efficient reconfiguration algorithms for such hierarchical parallel computing systems. Despite the dramatic improvement in defect density in recent years, it is still necessary to provide redundancy and defect circumvention to achieve acceptable system-level yields for large multicomputer systems. The TESH-based parallelsystems are no exception. Therefore, we develop placement and routing algorithms that assign logical nodes to healthy physical nodes and configure switches to bypass the defective cells, switches, and links. Simulations indicate that the placement,(Or remapping) is nearly 100 percent effective, while the routing performance diminishes with increasing defect density for a given extent of redundancy. The approach scales up well because, in TESH networks, essentially the same kind of sparing is used at all levels.
Progress toward the development and validation of a fast, accurate, and cost effective aeroelastic method for several advanced parallelcomputing platforms is presented. The ENSAERO code, developed at NASA Ames Resear...
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Progress toward the development and validation of a fast, accurate, and cost effective aeroelastic method for several advanced parallelcomputing platforms is presented. The ENSAERO code, developed at NASA Ames Research Center, was selected for this research effort. To improve the performance, the capabilities of the constituent modules have been enhanced. The relative merits of four parallelcomputing environments are investigated: SGI workstation cluster, SGI Power Challenge machine, SGI Power Challenge cluster, and the IBM SP2 system. To assess the computational performance of the enhanced ENSAERO code, the results of unsteady Navier-Stokes simulations of the transonic how over a fully flexible aeroelastic arrow-wing body configuration are reported. In addition, to ensure that the modified version of ENSAERO performs to specifications and to evaluate the benefits of the enhancements, unsteady Euler/Navier-Stokes calculations for an AGARD standard aeroelastic configuration are done. To evaluate the level of accuracy of the enhanced system, the ENSAERO results are compared with established computational solutions and experimental data.
A parallel computational code for the numerical integration of the Navier-Stokes equations has been developed. The system of partial differential equations describing the non-steady flow of a viscous incompressible fl...
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A parallel computational code for the numerical integration of the Navier-Stokes equations has been developed. The system of partial differential equations describing the non-steady flow of a viscous incompressible fluid in three dimensions is considered and applied to the channel flow problem. A mixed spectral-finite difference technique for the numerical integration of the governing equations is devised: Fourier decomposition in both streamwise and spanwise directions and finite differences in the direction orthogonal to the solid walls are used, while a semi-implicit procedure of Runge-Kutta and Crank-Nicolson type is utilised for the advancement in time. A wavenumber parallelism is implemented for the execution of the calculations. Within each time step of integration, the computations are executed in two distinct phases, each phase corresponding to a different way of decomposing the computational domain, vertically and horizontally, respectively;in both phases of the whole calculation process, each portion of the computing domain is handled by a different CPU on a Convex SPP 1200/XA parallelcomputing system. Results are presented in terms of performance of the calculation procedure with the use of 2,4,6 and 8 processors respectively and are compared with the single-processor performance. Also the accuracy of the parallel algorithm has been tested, by analysing the evolution in time of small amplitude disturbances of the mean flow;a satisfactory agreement with the theoretical solution given by the hydrodynamic stability theory is found, provided that a given number of grid points in the y direction are present. (C) 1999 Elsevier Science B.V. All rights reserved.
For large scale structural analysis, the performance of a linear equation solver is very important for the overall efficiency of the analysis code. The multifrontal solver Is a very efficient direct solver for finite ...
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For large scale structural analysis, the performance of a linear equation solver is very important for the overall efficiency of the analysis code. The multifrontal solver Is a very efficient direct solver for finite element analysis. By using multiple fronts, it can considerably reduce the computing time spent on solving the system of linear equations arising from finite element analysis. To achieve good performance using the multifrontal solver, a good front partition must be obtained because the performance largely depends on the quality of the front partition, that is, the number of degrees of freedom on the partitioned fronts, In this study, graph-partitioning algorithms that are generally used to decompose a given domain for parallel computation are combined with the multifrontal solver to obtain good front partitions of irregular (unstructured) meshes. The influence of the partitioning quality on the performance of the multifrontal solver is also examined. For regular (structured) meshes, the multifrontal scheme can solve the system of linear equations much more efficiently than the single frontal scheme with the help of a simple front-partitioning algorithm. For large-scale problems with irregular meshes such as the finite element meshes of aerospace structures, the verification was made that the developed multifrontal solver combined with an efficient graph partitioner (Metis) and an appropriate mesh mapping scheme (weighted edge mapping) shows very good performance.
An improved method is presented to parameterize a smoothly time varying, symmetric, positive definite system mass matrix M(t) in terms of the instantaneous eigenfactors, namely, the eigenvalues and eigenvectors of M(t...
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An improved method is presented to parameterize a smoothly time varying, symmetric, positive definite system mass matrix M(t) in terms of the instantaneous eigenfactors, namely, the eigenvalues and eigenvectors of M(t), Differential equations are desired whose solutions generate the instantaneous spectral decomposition of M(t). The derivation makes use of the fact that the eigenvector matrix is orthogonal and, thus, evolves analogously to a higher-dimensional rotation matrix. Careful attention is given to cases where some eigenvalues and/or their derivatives are equal or near equal. A robust method is presented to approximate the corresponding eigenvector derivatives in these cases, which ensures that the resulting eigenvectors still diagonalize the instantaneous M(t) matrix, This method is also capable of handling the rare case of discontinuous eigenvectors, which may only occur if both the corresponding eigenvalues and their derivatives are equal.
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