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parallel computation of the inertia matrix of a tree type robot using one directional recursion of Newton-Euler formulation

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JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS 1996年第1期15卷 33-39页

作者： Pu, HJ Muller, M Abdalla, E Abdelatif, L Bakr, E Eldin, HAN BERG UNIV GESAMTHSCH WUPPERTAL GRP AUTOMAT CONTROL & TECH CYBERNET D-42097 WUPPERTAL GERMANY HELWAN UNIV CAIRO EGYPT

This paper is devoted to the computation of the inertia matrix of a tree structured multi-arm robot system. Based on the PPO-Recursion proposed by the authors for the inertial, coupling, and gravitational dynamics of a robot [9], a parallel algorithm for computing the inertia matrix of chain structure robot has been achieved [10]. In the paper the PPO-Recursion is extended to be applied for the tree structured robot after. Appropriate interpretation of the dynamic properties of the branching link in the tree structure is introduced. The proposed algorithm offers high parallelism and is being under the realization in a transputer network.

关键词： robotics robot dynamics parallel computation

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parallel computation of unsteady incompressible viscous flows around moving rigid bodies using an immersed object method with overlapping girds

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JOURNAL OF computationAL PHYSICS 2005年第1期207卷 151-172页

作者： Tai, CH Zhao, Y Liew, KM Nanyang Technol Univ Sch Mech & Prod Engn Singapore 639798 Singapore Nanyang Technol Univ Nanyang Ctr Supercomp & Visualisat Singapore 639798 Singapore

A novel immersed object method is developed for simulating two-dimensional unsteady incompressible viscous flows around arbitrarily moving rigid bodies. It has been implemented in a parallel unstructured finite volume incompressible Navier-Stokes solver, based on the artificial compressibility (AC) approach using a higher-order characteristics-based upwind scheme and matrix-free implicit dual time-stepping. In the immersed object method, an object is immersed in the flow field, and it is supposed to contain frozen fluid, which moves like a solid body. This is realized by introducing source terms in the momentum equations during the AC sub-iterations. An internal mesh within the object is employed to search and locate all the Eulerian nodes within the object in every time step for imposing the source terms. Unlike many existing methods, this method does not require complex searching, extrapolation and interpolation to find the intersections of the object boundary with the unstructured background mesh and assign flow condition onto the object boundary. If it is necessary to capture the boundary layer accurately, then a dense overlapping grid can then be constructed around the object for further refined calculation. The immersed object method has been used to simulate steady and unsteady incompressible viscous flows over a stationary circular cylinder, rotating square cylinder and moving disk in cavity. The results agree well with published numerical solutions and experimental measurements. (c) 2005 Elsevier Inc. All rights reserved.

关键词： immersed object method overlapping grids characteristics-based method matrix-free implicit method parallel computation unstructured grid unsteady incompressible viscous flow

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parallel computation of aeroacoustics of industrially relevant complex-geometry aeroengine jets

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COMPUTERS & FLUIDS 2019年 178卷 166-178页

作者： Wang, Zhong-Nan Tyacke, James Tucker, Paul Boehning, Peer Univ Cambridge Dept Engn Cambridge CB2 1PZ England Rolls Royce Deutschland Aeroacoust D-15827 Blankenfelde Mahlow Germany

Jet noise is still a distinct noise component when a commercial aircraft is taking off. A parallel high-fidelity simulation framework for industrial jet noise prediction is presented in this paper. This framework includes complex geometry meshing and Ffowcs Williams-Hawkings (FW-H) surface placement during preprocessing, a parallel hybrid RANS-LES flow solver coupled with an FW-H acoustic solver in the simulation and mean and unsteady data processing after the simulation. The use of this framework is demonstrated through two jet noise prediction cases: in-flight heated jets and installed ultra-high bypass ratio (UHBPR) engines. These simulations can provide more insight than experimental tests into jet flow physics for engineering model improvement. Additional advantages are also shown in the cost and turnaround time. Thus there is great potential for high-fidelity jet noise simulations to partly replace rig tests for industrial use in the future. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： parallel computation Hybrid LES-RANS Jet noise prediction

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parallel computation of Adaptive Filtering Algorithms on Multi-Core Systems

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JOURNAL OF SIGNAL PROCESSING SYSTEMS FOR SIGNAL IMAGE AND VIDEO TECHNOLOGY 2012年第3期69卷 253-265页

作者： Lee, Dong-hwan Ahn, Jaewoo Sung, Wonyong Seoul Natl Univ Dept Elect Engn & Comp Sci Seoul 151744 South Korea

The performance of recent CPUs has been rapidly increasing with the help of parallel architectural supports, such as SIMD (Single Instruction Multiple Data) extensions and multi-core architecture. However, efficient use of such parallel supports for adaptive filtering is difficult due to feedback loops that induce the data dependency problem. In this paper, efficient parallel computation of adaptive filters is studied for multi-core architecture with SIMD arithmetic support. Control- and data-level parallel computation methods are considered, where the former finds parallelism in the evaluation of one output sample, while the latter processes multiple output samples at a time to increase the degree of parallelism. The control-level parallel approach frequently utilizes the pipelining technique to uncover the parallelism, whereas the data-level approach employs a parallel computation method for linear recurrence equations to resolve the dependency. Not only adaptive transversal LMS (Least Mean Square) but also gradient adaptive lattice (GAL) and QR-decomposition based least-square lattice (QRD-LSL) filters are implemented on a PC that employs both SIMD and multi-core architecture.

关键词： parallel computation Adaptive filter LMS GAL QRD-LSL Multi-core Single Instruction Multiple Data (SIMD) architecture

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parallel computation of viscous incompressible flows using Godunov-projection method on overlapping grids

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS 2002年第5期39卷 441-463页

作者： Pan, H Damodaran, M Nanyang Technol Univ Sch Mech & Prod Engn Div Thermal & Fluids Engn Singapore 639798 Singapore

The Godunov-projection method is implemented on a system of overlapping structured grids for solving the time-dependent incompressible Navier-Stokes equations, This projection method uses a second-order fractional step scheme in which the momentum equation is solved to obtain the inter-mediate velocity field which is then projected on to the space of divergence-free hector fields. The Godunov procedure is applied to estimate the non-linear convective term in order to provide a robust discretization of this terms at high Reynolds number. In order to obtain the pressure field, a separate procedure is applied in this modified Godunov-projection method. where the pressure Poisson equation is solved. Overlapping grids are used to discretize the flow domain, as they offer the flexibility of simplifying the grid generation around complex geometrical domains. This combination of projection method and overlapping grid is also parallelized and reasonable parallel efficiency is achieved. Numerical results are presented to demonstrate the performance of this combination of the Godunov-projection method and the overlapping grid. Copyright (C) 2002 John Wiley Sons, Ltd.

关键词： numerical simulation viscous flow unsteady flow projection method overlapping grid parallel computation

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parallel computation of configuration space

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ROBOTICA 1996年第2期14卷 205-212页

作者： Gonzalez, JS Jones, DI Instituto de Investigaciones en Matematicas y en Sistemas Departamento de Electronica y Automatizacion Universidad Nacional Autonoma de Mexico Apartado Postal 20–276 Admon - No 20 01000 Mexico DF (Mexico) School of Electronic Engineering and Computer Systems University of Wales Dean Street Bangor Gwynedd LL57IUT North Wales (UK).

Many motion planning methods use Configuration Space to represent a robot manipulator's range of motion and the obstacles which exist in its environment. The Cartesian to Configuration Space mapping is computationally intensive and this paper describes how the execution time can be decreased by using parallel processing. The natural tree structure of the algorithm is exploited to partition the computation into parallel tasks. An implementation programmed in the occam2 parallel computer language running on a network of INMOS transputers is described. The benefits of dynamically scheduling the tasks onto the processors are explained and verified by means of measured execution times on various processor network topologies. It is concluded that excellent speed-up and efficiency can be achieved provided that proper account is taken of the variable task lengths in the computation.

关键词： configuration space parallel computation obstacles motion planning

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parallel computation of probabilistic skyline queries using MapReduce

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JOURNAL OF SUPERCOMPUTING 2021年第1期77卷 418-444页

作者： Gavagsaz, Elaheh Eqbal Lahoori Inst Higher Educ Mashhad Razavi Khorasan Iran

In recent years, numerous applications have been continuously generating large amounts of uncertain data. The advanced analysis queries such as skyline operators are essential topics to extract interesting objects from the vast uncertain dataset. Recently, the MapReduce system has been widely used in the area of big data analysis. Although the probabilistic skyline query is not decomposable, it does not make sense to implement the probabilistic skyline query in the MapReduce framework. This paper proposes an effective parallel method called parallel computation of probabilistic skyline query (PCPS) that can measure the probabilistic skyline set in one MapReduce computation pass. The proposed method takes into account the critical sections and detects data with a high probability of existence through a proposed smart sampling algorithm. PCPS implements a new approach to the fair allocation of input data. The experimental results indicate that our proposed approach can not only reduce the processing time of the probabilistic skyline queries, but also achieve fair precision with varying dimensionality degrees.

关键词： Probabilistic skyline query Uncertain data Multidimensional database parallel computation

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parallel computation of natural convection in trapezoidal porous enclosures

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MATHEMATICS AND COMPUTERS IN SIMULATION 2004年第3期65卷 221-229页

作者： Kumar, BR Kumar, BP Indian Inst Technol Dept Math Parallel Comp Lab Kanpur 208016 Uttar Pradesh India

In this study, coupled non-linear partial differential equations governing the natural convection from an isothermal wall of a trapezoidal porous enclosure have been solved numerically by finite element method (FEM) in conjunction with GMRES, a Krylov subspace based solver. In view of the enormous amount of computation, a parallel numerical algorithm for incomplete LU-conjugate gradient (ILU-CG) solver on eight-noded ANUPAM cluster under MIMD paradigm based on ANULIB message passing library has been developed. parallel computations have been carried out for various values of flow and geometric parameters both under Darcian and non-Darcian assumptions on the porous model. Cumulative heat fluxes and Nusselt number (Nu) associated with convection process are presented through computer generated plots. (C) 2004 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： parallel computation natural convection porous enclosure finite element method ILU-CGM

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parallel computation of flow in heterogeneous media modelled by mixed finite elements

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JOURNAL OF computationAL PHYSICS 2000年第2期164卷 258-282页

作者： Cliffe, KA Graham, IG Scheichl, R Stals, L AEA Technol Didcot OX11 0RA Oxon England Univ Bath Dept Math Sci Bath BA2 7AY Avon England Old Dominion Univ Dept Comp Sci Norfolk VA 23529 USA

In this paper we describe a fast parallel method for solving highly ill-conditioned saddle-point systems arising from mixed finite element simulations of stochastic partial differential equations (PDEs) modelling flow in heterogeneous media. Each realisation of these stochastic PDEs requires the solution of the linear first-order velocity-pressure system comprising Darcy's law coupled with an incompressibility constraint. The chief difficulty is that the permeability may be highly variable, especially when the statistical model has a large variance and a small correlation Length. For reasonable accuracy, the discretisation has to be extremely fine. We solve these problems by first reducing the saddle-point formulation to a symmetric positive definite (SPD) problem using a suitable basis for the space of divergence-free velocities. The reduced problem is solved using parallel conjugate gradients preconditioned with an algebraically determined additive Schwarz domain decomposition preconditioner. The result is a solver which exhibits a good degree of robustness with respect to the mesh size as well as to the variance and to physically relevant values of the correlation Length of the underlying permeability field. Numerical experiments exhibit almost optimal levels of parallel efficiency. The domain decomposition solver (DOUG, http://***/(similar to)parsoft) used here not only is applicable to this problem but can be used to solve general unstructured finite element systems on a wide range of parallel architectures. (C) 2000 Academic Press.

关键词： Raviart-Thomas mixed finite elements second-order elliptic problems divergence-free space heterogeneous media groundwater flow domain decomposition parallel computation

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parallel computation OF 2-POINT BOUNDARY-VALUE-PROBLEMS VIA PARTICULAR SOLUTIONS

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JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS 1993年第1期79卷 5-29页

作者： MIELE, A WANG, T 1. Aero-Astronautics Group Rice University Houston Texas

Nonlinear two-point boundary-value problems (TPBVP) can be reduced to the iterative solution of a sequence of linear problems by means of quasilinearization techniques. Therefore, the efficient solution of linear problems is the key to the efficient solution of nonlinear problems. Among the techniques available for solving linear two-point boundary-value problems, the method of particular solutions (MPS) is particularly attractive in that it employs only one differential system, the original nonhomogeneous system, albeit with different initial conditions. This feature of MPS makes it ideally suitable for implementation on parallel computers in that the following requirements are met: the computational effort is subdivided into separate tasks (particular solutions) assigned to the different processors;the tasks have nearly the same size;there is little intercommunication between the tasks. For the TPBVP, the speedup achievable is of O(n), where n is the dimension of the state vector, hence relatively modest for the differential systems of interest in trajectory optimization and guidance. This being the case, we transform the TPBVP into a multi-point boundary-value problem (MPBVP) involving m time subintervals, with m-l continuity conditions imposed at the interface of contiguous subintervals. For the MPBVP, the speedup achievable is of O(mn), hence substantially higher than that achievable for the TPBVP. It reduces to O(m) if the parallelism is implemented only in the time domain and not in the state domain. A drawback of the multi-point approach is that it requires the solution of a large linear algebraic system for the constants of the particular solutions. This drawback can be offset by exploiting the particular nature of the interface conditions: if the vector of constants for the first subinterval is known, the vector of constants for the subsequent subintervals can be obtained with linear transformations. Using decomposition techniques together with the discret

关键词： 2-POINT BOUNDARY-VALUE PROBLEMS MULTIPOINT BOUNDARY-VALUE PROBLEMS MODIFIED QUASI-LINEARIZATION ALGORITHM METHOD OF PARTICULAR SOLUTIONS SEQUENTIAL ALGORITHMS parallel ALGORITHMS, parallel computation TRAJECTORY OPTIMIZATION TRAJECTORY GUIDANCE

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