We propose a method for accelerating iterative algorithms for solving symmetric linear complementarity problems. The method consists in performing a one-dimensional optimization in the direction generated by a splitti...
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We propose a method for accelerating iterative algorithms for solving symmetric linear complementarity problems. The method consists in performing a one-dimensional optimization in the direction generated by a splitting method even for non-descent directions. We give strong convergence proofs and present numerical experiments that justify using this acceleration.
The propose of this paper is to present a modified block iterative algorithm for finding a common element between the set of solutions of the fixed points of two countable families of asymptotically relatively nonexpa...
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The propose of this paper is to present a modified block iterative algorithm for finding a common element between the set of solutions of the fixed points of two countable families of asymptotically relatively nonexpansive mappings and the set of solution of the system of generalized mixed equilibrium problems in a uniformly smooth and uniformly convex Banach space. Our results extend many known recent results in the literature.
We prove some existence theorems for solutions of a certain system of multivariate nonexpansive operator equations and calculate the solutions by using the generalized Mann and Halpern iterative algorithms in uniforml...
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We prove some existence theorems for solutions of a certain system of multivariate nonexpansive operator equations and calculate the solutions by using the generalized Mann and Halpern iterative algorithms in uniformly convex and uniformly smooth Banach spaces. The results of this paper improve and extend the previously known ones in the literature.
In this paper, we use the dual variable to propose a new cyclic iterative algorithm for solving the multiple-set split common fixed-point problem of averaged operators in Hilbert spaces. Inspired by the idea of parall...
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In this paper, we use the dual variable to propose a new cyclic iterative algorithm for solving the multiple-set split common fixed-point problem of averaged operators in Hilbert spaces. Inspired by the idea of parallel iterative algorithms, we also introduce two mixed iterative algorithms which combine the process of cyclic and parallel together. Under mild assumptions, we prove weak convergence of the proposed iterative sequences in Hilbert spaces. As applications, we obtain several iterative algorithms to solve the multiple-set split feasibility problem.
An iterative procedure for the restoration of event related potentials (ERP) is proposed and implemented. The method makes use of assumed or measured statistical information about latency variations in the individual ...
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An iterative procedure for the restoration of event related potentials (ERP) is proposed and implemented. The method makes use of assumed or measured statistical information about latency variations in the individual ERP components. The signal model used for the restoration algorithm consists of a time-varying linear distortion and a positivity/negativity constraint. Additional preprocessing in the form of low-pass filtering is needed in order to mitigate the effects of additive noise. Numerical results obtained with real data show clearly the presence of enhanced and regenerated components in the restored ERP's. The procedure is easy to implement which makes it convenient when compared to other proposed techniques for the restoration of ERP signals.
In a previous work, we have shown the very high power of asynchronism for parallel iterative algorithms in a global context of grid computing. In this article, we study the interest of coupling load balancing with asy...
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In a previous work, we have shown the very high power of asynchronism for parallel iterative algorithms in a global context of grid computing. In this article, we study the interest of coupling load balancing with asynchronism in these algorithms. We propose a non-centralized version of dynamic load balancing which is best suited to asynchronism. After showing, by some experiments on a given ODE problem, that this technique can efficiently enhance the performance of our algorithms, we give some general conditions for the use of load balancing to obtain good results with this kind of algorithm.
In this paper we study the development of parallel algorithms to solve advection-diffusion equations. Both synchronous and asynchronous algorithms contexts are considered. The solver we present is based on the multisp...
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In this paper we study the development of parallel algorithms to solve advection-diffusion equations. Both synchronous and asynchronous algorithms contexts are considered. The solver we present is based on the multisplitting Newton method that provides a coarse-grained scheme. Experiments are carried out in an heterogeneous grid environment in which both parallel algorithms are analyzed. Experiments allow us to draw some conclusions about the use of parallel iterative algorithms in a grid computing environment.
The authors describe a procedure to transform a class of sequential iterative algorithms to systems of (uniform) recurrent equations (REs) from which systolic arrays can automatically be derived. They derive an equiva...
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The authors describe a procedure to transform a class of sequential iterative algorithms to systems of (uniform) recurrent equations (REs) from which systolic arrays can automatically be derived. They derive an equivalent class of systems of recurrent equations for a class of sequential iterative algorithms. First, they construct two formal models: A for the class of sequential algorithms they consider and R for the REs. Then they construct a procedure which maps an algorithm in A on a corresponding one in R. The essence of the method is to find the trace of the variables in the former algorithm. The method described is general and can be implemented in a design system for systolic arrays.< >
The point response resolution of a gamma camera deteriorates with increased distance from the face of the collimator. This results in reconstruction artifacts that are seen as shape distortion and density non-uniformi...
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The point response resolution of a gamma camera deteriorates with increased distance from the face of the collimator. This results in reconstruction artifacts that are seen as shape distortion and density non-uniformity. For parallel, fan, and cone beam geometries, iterative reconstruction algorithms have been developed which eliminate these artifacts by incorporating the three-dimensional spatially varying geometric point response into models for the projection and backprojection operations which also model photon attenuation. The algorithms have been tested on an IBM 3090-600S supercomputer. The iterative EM reconstruction algorithm is 50 times longer with geometric response and photon attenuation models than without modeling these physical effects. We have demonstrated an improvement in image quality in the reconstruction of projection data collected from a single photon emission computed tomography (SPECT) imaging system. Using phantom experiments, we observe that the modeling of the spatial system response imposes a smoothing without loss of resolution.
This paper investigates the possibility of developing a SPECT system that combines the high spatial resolution of position sensitive photomultiplier tubes (PSPMTs) with the excellent performance of iterative reconstru...
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This paper investigates the possibility of developing a SPECT system that combines the high spatial resolution of position sensitive photomultiplier tubes (PSPMTs) with the excellent performance of iterative reconstruction algorithms. A small field of view (FOV) camera based on a PSPMT and a pixelized scintillation crystal made of CsI(TI) have been used for the acquisition of the projections. With the use of maximum likelihood expectation maximization (ML-EM) and ordered subsets expectation maximization (OSEM) slices of the object are obtained while three-dimensional (3D) reconstruction of the object is carried out using a modified marching cubes (MMC) algorithm. The spatial resolution of tomographic images obtained with the system was 2-3 mm. The spatial resolution of a conventional system that uses filtered backprojection (FBP) for slices reconstruction was more than 9 mm. (C) 2002 Elsevier Science Ltd. All rights reserved.
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