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Systematic approach to MUSIC estimation with minimisation of its cost function

ELECTRONICS LETTERS 1999年第8期35卷 620-621页

作者： Choi, YH Dongyang Univ Sch Informat & Commun Engn Kyungbook 750711 South Korea

Based on the minimisation of a cost function, a systematic approach to MUSIC estimation is proposed for the arrival angles of the signals impinging on a sensor array. The proposed method, which employs Brent's method for the task together with bisection bracketing, can significantly reduce the computational burden compared to the conventional algorithm for computing the whole spatial spectrum.

关键词： signal arrival angle minimisation computational algorithm array signal processing Optimisation techniques multiple signal characterisation sensor array spatial spectrum MUSIC estimation Signal processing and detection direction-of-arrival estimation Brent method cost function minimisation bisection bracketing

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An oscillation suppressing semi-Lagrangian solver for advection equation

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COMPUTER PHYSICS COMMUNICATIONS 1999年第1期116卷 121-135页

作者： Xiao, F Yabe, T Ebisuzaki, T RIKEN Inst Phys & Chem Res Sci Computat Lab Wako Saitama 35101 Japan Tokyo Inst Technol Dept Energy Sci Midori Ku Yokohama Kanagawa 226 Japan

This work presents a Fortran code to solve the advection equation in 1, 2 and 3 dimensions. The scheme is based on a rational interpolation function. Not only the interpolation profile itself but also its first-order spatial derivatives are predicted by the governing equation. Using the Lagrangian invariant solution of the advection to evaluate the gradients makes the method compact. The scheme is indeed constructed over only one mesh cell. The method has third-order accuracy in the smooth region and appears to be able to suppress spurious numerical oscillations near great gradients. (C) 1999 Elsevier Science B.V.

关键词： computational algorithm advection equation semi-Lagrangian method rational function oscillation preventing

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A global control algorithm in the plane

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DYNAMICS AND CONTROL 1998年第4期8卷 377-385页

作者： Kaya, CY Noakes, JL Univ S Australia Sch Math The Levels SA 5095 Australia Univ Western Australia Dept Math Nedlands WA 6907 Australia

The controllability theory may at times lead to a control law as can be seen in the control theory literature. In this paper, a global control algorithm is proposed for nonlinear systems in the sc-called linear-analytic form in the plane. The algorithm is motivated by a theorem by Hunt, which gives sufficient conditions for the global controllability of linear-analytic systems on a 2-dimensional manifold. It is verified that the algorithm is globally convergent under the given assumptions. A computational form of the algorithm is presented. Some computational aspects are also discussed.

关键词： nonlinear control systems global controllability computational algorithm

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Mathematical modeling and computer simulation of transient flow in centrifuge cascade pipe network with optimizing techniques

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COMPUTERS & MATHEMATICS WITH APPLICATIONS 1998年第4期36卷 63-76页

作者： Malik, MN Afzal, M Tariq, GF Ahmed, N Dr AQ Khan Res Labs Rawalpindi Pakistan Quaid I Azam Univ Dept Math Islamabad Pakistan

Mathematical model and computer simulation for solution of transient flow in the complex pipe network of centrifuge cascade has been made to predict the behavior of its different components and their mutual interaction. To make it more practical and efficient, a number of technical aspects ignored in other models have been included. All possible fittings of the system have been included and optimizing techniques developed to simulate the components and to achieve fast solution are presented. The model is especially developed to cater flow of gas in complex low pressure network having number of feedback or recycling loops. The system of partial and ordinary differential equations along with a number of algebraic equations arising from the physical network have been analyzed and solved. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词： transient flow model pipe network flow simulation ordinary and hyperbolic partial differential equations computational algorithm stiff system of equations pipe network component modeling

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computational algorithm to predict peak profiles in preparative high-performance chromatography

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KOREAN JOURNAL OF CHEMICAL ENGINEERING 1995年第5期12卷 512-515页

作者： Row, KH Larin, AV Department of Chemical Engineering Inha University Inchon Korea Institute of Physical Chemistry Russian Academy of Sciences Moscow Russian Federation

The computational algorithm and tire Prep-LEAR program have been performed on the basis of the LEA model of chromatography. This program intends for calculation of peak profiles in non-linear high-performance chromatography and uses unsimplified adsorption isotherm equations The computational algorithm and program have been tested by applying these to experimental data of thymine adsorption under conditions of reversed-phase highperformance liquid chromatography. The results of numerical calculations for different sample size introduced agree satisfactorily with experimental data and show the characteristic properties of high-performance chromatography, The usefulness of the Prep-LEAR program was confirmed by predicting peak profiles in preparative adsorption chromatographic processes

关键词： peak profiles preparative chromatography non-linear adsorption isotherm LEA model computational algorithm prep-LEAR program

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An algorithm for simulating solid objects suspended in stratified flow

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COMPUTER PHYSICS COMMUNICATIONS 1997年第1-3期102卷 147-160页

作者： Xiao, F Yabe, T Ito, T Tajima, M TOKYO INST TECHNOL GRAD SCH NAGATSUTADEPT ENERGY SCIMIDORI KUYOKOHAMAKANAGAWA 227JAPAN

An efficient difference algorithm for computing directly deformation less solid objects suspended in stratified flow in 2D has been developed. The objects are represented by colour functions (or density functions) and predicted by a sharpness preserving scheme that is able to prevent the numerical diffusion across the sharp interface, Pressure distribution is then calculated by a unified solver and the solid object is treated as a mass of material of high sound speed, The motion of the solid object is decomposed into translation and rotation, and the force as well as the torque that cause change in the motion of the solid body are evaluated by an averaging calculation over the region occupied by the solid body. Calculations are conducted on a fixed grid system, Operations for reconstructing moving interfaces or dealing with inner boundary conditions are not necessary.

关键词： computational algorithm fluid dynamics stratified flow suspended objects

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Observations of convergence and uniqueness of node-based bone remodeling simulations

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ANNALS OF BIOMEDICAL ENGINEERING 1997年第2期25卷 261-268页

作者： Fischer, KJ Jacobs, CR Levenston, ME Carter, DR DEPT VET AFFAIRS MED CTR REHABIL RES & DEV CTRPALO ALTOCA STANFORD UNIV DEPT ENGN MECHBIOMECH ENGN PROGRAMSTANFORDCA 94305

Some investigators have indicated that mathematical theories and computational models of bone adaptation may not converge and that the density solutions from such simulations are dependent on the initial density distribution. In this study, two-dimensional finite element models were used to investigate the effect of initial density distribution on the final density distribution produced using a node-based bone remodeling simulation. The first model was a generic long bone, and the second was a proximal femur. For each model, we conducted time-dependent, node-based, linear rate-law bone remodeling simulations. Five initial density conditions were used with the generic long bone and three with the proximal femur, Remodeling simulations were performed, and the largest average nodal density differences at the end of the simulations were 0.000010 g/cm(3) and 0.000006 g/cm(3) for the generic long bone and proximal femur models, respectively. Results illustrate that, for a given set of loads and a given finite element model, the node-based bone adaptation algorithm can yield a unique density distribution, In conjunction with previous studies, this finding suggests that uniqueness of the density solution is dependent on both the mathematical theory and the computational implementation.

关键词： initial conditions density distribution finite element model bone load estimation computational algorithm

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computational methods for performance evaluation of a statistical multiplexer supporting bursty traffic

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IEEE-ACM TRANSACTIONS ON NETWORKING 1996年第3期4卷 386-397页

作者： Wu, GL Mark, JW UNIV WATERLOO DEPT ELECT & COMP ENGNWATERLOOON N2L 3G1CANADA

A statistical multiplexer supporting a number of bursty sources is modeled as a discrete time, single server queueing system with an infinite buffer. The probability generating function (PGF) method is used to analyze the queueing behavior. The PGF method requires the determination of a large number of boundary values and, hence, the roots of the characteristic equation. An iterative algorithm to evaluate the characteristic roots is proposed. When the arrival process is a superposition of independent processes, a decomposition approach is used to reduce the state space involved in the computational algorithm. Additionally, the computational algorithm is made efficient through the establishment of conditions under which all the roots are either real or nonnegative real numbers. A set of equations to recursively compute the moments of the queue length are established. Sample applications of the computational methods to evaluate the performance of a multiplexer supporting voice and video sources, modeled by two-state Markov and L-state MMPP processes, respectively, demonstrate the viability of the proposed methods.

关键词： Multiplexing Queueing Theory Discrete Time Systems Probability Iterative Methods State Space Methods Recursive Functions computational Complexity Markov Processes Stochastic Processes Visual Communication Telecommunication Traffic computational Methods Performance Evaluation Statistical Multiplexer Bursty Traffic Bursty Sources Discrete Time Single Server Queueing System Infinite Buffer Probability Generating Function Method Boundary Values Characteristic Equation Iterative algorithm Arrival Process Decomposition Approach State Space computational algorithm Queue Length Moments Recursive Method Voice Source Video Source Two State Markov Processes L State MMPP Processes Markov Modulated Poisson Process Multiplexing Iterative algorithms Aggregates Quantum Computing Probability Streaming Media Traffic Control computational Complexity Poisson Equations Queueing Analysis

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Solving equations simulating the steady-state behavior of the multi-stage flash desalination process

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DESALINATION 1996年第2期107卷 171-193页

作者： ElDessouky, H Bingulac, S KUWAIT UNIV DEPT ELECT & COMP ENGNSAFAT 13060KUWAIT

The paper presents an algorithm for solving the equations simulating the steady-state behavior of the multi-stage flash(MSF) desalination process. The model can be used either for designing new plants or analysis and optimization of existing units. The set of equations relating the large number of design and operating variables for any stage (i-th stage) in MSF plants is broken down into three subsets. The first subset contains equations describing processes in the tubes of the preheater inside the flashing chamber. The second subset deals with the processes inside the flashing chamber. These two subsets of equations are subsequently solved iteratively involving only a single variable for each subset. These variables are: (1) saturation temperature T-vi of the flashed-off vapor and (2) temperature of the unevaporated brine flowing from the chamber. The third subset of equations considers the existing interactions between the first two subsets. This subset defines the mass of vapor formed by flashing D-i in the i-th stage. All equations in the above-mentioned subsets are solved by a reliable and efficient one-dimensional fixed-point iteration. The main advantages of this method are less sensitivity to initial guesses, fewer iterations to obtain the required solution, and no need for calculating derivatives. The algorithm is implemented using the computer-aided design (CAD) interative package L-A-S (Linear Algebra and Systems). Detailed results are presented to show the dependence of the important factors controlling the fresh water cost, which are plant performance ratio, specific heat transfer area, specific brine flow rate, and specific cooling water now rate, on the most significant two design variables, namely the total number of stages and the top brine temperature. The predicted data hem the model are compared with published data of a typical MSF plant in operation at Kuwait. The agreement was found to be very good.

关键词： MSF desalination process modelling and simulation of MSF plants stage-by-stage algorithm non-linear equations computational algorithm

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Constructing a multi-dimensional oscillation preventing scheme for the advection equation by a rational function

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COMPUTER PHYSICS COMMUNICATIONS 1996年第2-3期94卷 103-118页

作者： Xiao, F Yabe, T Nizam, G Ito, T TOKYO INST TECHNOL DEPT ENERGY SCIMIDORI KUYOKOHAMAKANAGAWA 226JAPAN

We recently developed a numerical scheme for solving advection equations based on a rational interpolation function. The scheme shows properties in suppressing spurious numerical oscillations near great gradients and sharing high accuracy in the smooth region. Results in one dimension were reported in a previous paper (F. Xiao, T. Yabe and T. Ito, Comput. Phys. Commun. 93 (1996) 1). In this paper, we, for completion, present the two- and three-dimensional versions of the scheme without directional splitting. Formula are derived in the way such as to recover the CIP method (T. Yabe, T. Aoki, Comput. Phys. Commun. 60 (1991) 219;T. Yabe, T. Ishikawa, P.Y. Wang, T. Aoki, Y. Kadota and F. Ikeda, Comput. Phys. Commun. 66 (1991) 233) by switching. The oscillation preventing quality of the scheme in two and three dimensions is tested by sample calculations.

关键词： computational algorithm advection equation rational function multi-dimensional scheme oscillation preventing

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