Volume optical storage systems suffer from numerous sources of noise and interference, the effects of which can seriously degrade retrieved data fidelity and produce unacceptable bit-error rates (BER's), We examin...
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Volume optical storage systems suffer from numerous sources of noise and interference, the effects of which can seriously degrade retrieved data fidelity and produce unacceptable bit-error rates (BER's), We examine the problem of reliable two-dimensional data retrieval in the context of recently developed soft-decision methods for iterative decoding. We describe a novel near-optimal algorithm in which each pixel on the page is treated as a starting point for a simple iterative procedure so that a highly parallel, locally connected, distributed computational model emerges whose operation is well suited to the page-oriented memory (POM) interface format. We study the use of our two-dimensional distributed data detection (2D(4)) algorithm with both incoherent (linear) and coherent (nonlinear) finite-contrast POM channel models. We present BER results obtained using the 2D4 algorithm and compare these with three other typical methods [i.e., simple thresholding (THA), differential encoding (DC) and the decision feedback Viterbi algorithm (DFVA)]. The BER improvements are shown to have a direct impact on POM storage capacity and density and this impact is quantified for the special case of holographic POM, In a Rayleigh resolved holographic POM system with infinite contrast, we find that 2D(4) offers capacity improvements of 84%, 56%, and 8% as compared with DC, THA, and DFVA respectively, with corresponding storage density gains of 85%, 26%, and 9%, In the case of finite contrast (C = 4), similar capacity improvements of 93%, 18%, and 4% produce similar density improvements of 98%, 21%, and 6%, Implementational issues associated with the realization of this new distributed detection algorithm are also discussed and parallel neural and focal plane strategies are considered, A 2 cm(2) lambda = 0.1 mu m digital VLSI real estate budget will support a 600 x 600 pixel 2D(4) focal plane processor operating at 40 MHz with less than 1.7 W/cm(2) power dissipation.
algorithmic enhancements are described that enable large computational reduction in mean square-error data clustering. These improvements are incorporated into a parallel data-clustering tool, P-CLUSTER, designed to e...
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algorithmic enhancements are described that enable large computational reduction in mean square-error data clustering. These improvements are incorporated into a parallel data-clustering tool, P-CLUSTER, designed to execute on a network of workstations. Experiments involving the unsupervised segmentation of standard texture images were performed. For some data sets, a 96 percent reduction in computation was achieved.
In this paper, we show a simple parallel algorithm for polynomial evaluation. By this method, we only need 2N/p + log(2) p steps on p processors (where p less than or equal to O(N-1/2)) to evaluate a polynomial of deg...
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In this paper, we show a simple parallel algorithm for polynomial evaluation. By this method, we only need 2N/p + log(2) p steps on p processors (where p less than or equal to O(N-1/2)) to evaluate a polynomial of degree N on an SIMD computer or an MIMD computer, which is a decrease of log(2) p steps as compared with the p-order Homer method [S. Lakshmivarahan and S. K. Dhall, Analysis and Design of parallel algorithms, McGraw-Hill, New York, 1990], and also a decrease of (2log(2) p)1/2 steps as compared with some other algorithms on an MIMD computer [J. I. Munro and M. Paterson, J. Comput. System Sci., 7 (1973), pp. 189-198, K. Maruyama, IEEE Trans. Comput., C-22 (1973), pp. 2-5]. The new algorithm is simple in structure and easy to implement.
The paper presents a new parallel method for transient stability analysis of power systems. For simplicity, the classical power system model is adopted. The implicit trapezoidal rule is used to discretise the set of d...
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The paper presents a new parallel method for transient stability analysis of power systems. For simplicity, the classical power system model is adopted. The implicit trapezoidal rule is used to discretise the set of differential equations which describes the transient stability problem. As is well known. these discretised nonlinear algebraic equations are almost invariably solved by a Newton procedure. A parallel-in-time relaxed Newton method is proposed to solve the overall set of discretised equations concurrently on all the time steps. The proposed method has been tested on Cray-T3D by the use of PVM system. The test results show that the proposed method presents a good compromise between parallelism-in-time and convergence. Some important aspects for parallel transient stability analysis have been clarified.
Fractal dimension is an important parameter that can be used in various applications, such as, estimation of roughness in an image, texture segmentation, surface roughness estimation and many others. A number of techn...
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Fractal dimension is an important parameter that can be used in various applications, such as, estimation of roughness in an image, texture segmentation, surface roughness estimation and many others. A number of techniques for fractal dimension computation in the digital domain have been reported in the literature. A parallel implementation of the Differential Box Counting technique is reported in this paper. The accuracy and computational complexity of the parallel implementation are also discussed. (C) 1998 Elsevier Science B.V. All rights reserved.
This paper focuses on the inverse dynamics formulation of manipulators that is suitable for parallel computation, and a corresponding nonrecursive Newton-Euler formulation is presented. In order to illustrate its pote...
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This paper focuses on the inverse dynamics formulation of manipulators that is suitable for parallel computation, and a corresponding nonrecursive Newton-Euler formulation is presented. In order to illustrate its potential parallelism, a simple parallel scheduling scheme is proposed, and the parallel computational efficiency for the inverse dynamics of the basic three Links of a PUMA 560 robot is analyzed. Compared with other algorithms, the theoretical computation cost of this parallel algorithm, in which factors such as communications overhead are ignored, is smaller.
A general framework for unconstrained minimization of a nonlinear function using parallel processors is presented. The basic idea underlying the proposed parallel variable transformation algorithm is to transform the ...
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A general framework for unconstrained minimization of a nonlinear function using parallel processors is presented. The basic idea underlying the proposed parallel variable transformation algorithm is to transform the variables into more than one space of smaller dimension simultaneously and compute candidate solutions on the latter spaces in parallel. The candidate solutions obtained are then used to generate an improved solution to the original problem. Global convergence and the linear rate of convergence of the algorithm are established under suitable conditions. Two recently proposed parallel optimization algorithms, the parallel gradient distribution (PGD) algorithm and the unconstrained parallel variable distribution (PVD) algorithm, are shown to belong to the class of parallel variable transformation (PVT) algorithms. An earlier parallel algorithm called the updated conjugate subspaces (UCS) method is also shown to be a particular case of the PVT algorithm. Specific algorithmic schemes are also suggested.
The discretized linear elasticity problem is solved by the preconditioned conjugate gradient (pcg) method. Mainly we consider the linear isotropic case but we also comment on the more general linear orthotropic proble...
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The discretized linear elasticity problem is solved by the preconditioned conjugate gradient (pcg) method. Mainly we consider the linear isotropic case but we also comment on the more general linear orthotropic problem. The preconditioner is based on the separate displacement component (sdc) part of the equations of elasticity. The preconditioning system consists of two or three subsystems (in two or three dimensions) also called inner systems, each of which is solved by the incomplete factorization peg-method, i.e., we perform inner iterations. A finite element discretization and node numbering giving a high degree of partial parallelism with equal processor load for the solution of these systems by the MIC(O) peg method is presented. In general, the incomplete factorization requires an M-matrix. This property is studied for the elasticity problem. The rate of convergence of the peg-method is analysed for different preconditionings based on the sdc-part of the elasticity equations. In the following two parts of this trilogy we will focus more on parallelism and implementation aspects. (C) 1998 John Wiley & Sons, Ltd.
We propose a perspective volume graphics rendering algorithm on SIMD mesh-connected computers and implement the algorithm on the parallel Algebraic Logic (PAL) computer. The algorithm is a parallel ray casting algorit...
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ISBN:
(纸本)0819429074
We propose a perspective volume graphics rendering algorithm on SIMD mesh-connected computers and implement the algorithm on the parallel Algebraic Logic (PAL) computer. The algorithm is a parallel ray casting algorithm. It decomposes the 3D perspective projection into two transformations that can be implemented in the SIMD fashion to solve the data redistribution problem caused by non-regular data access patterns in the perspective projection.
In this paper, we discuss a nonadaptive group testing algorithm that identifies up to two defects. The number of required tests in our algorithm is not optimal, but our search procedure is less complex than that of ot...
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In this paper, we discuss a nonadaptive group testing algorithm that identifies up to two defects. The number of required tests in our algorithm is not optimal, but our search procedure is less complex than that of other well known algorithms using fewer tests. We go on to discuss a simple two stage modification of our algorithm which dramatically reduces the number of sufficient tests. (C) 1998 Elsevier Science B.V.
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