This article is concerned with a numerical simulation of shape optimization of the Oseen flow around a solid body. The shape gradient for shape optimization problem in a viscous incompressible flow is computed by the ...
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This article is concerned with a numerical simulation of shape optimization of the Oseen flow around a solid body. The shape gradient for shape optimization problem in a viscous incompressible flow is computed by the velocity method. The flow is governed by the Oseen equations with mixed boundary conditions containing the pressure. The structure of continuous shape gradient of the cost functional is derived by using the differentiability of a minimax formulation involving a Lagrange functional with a function space parametrization technique. A gradient type algorithm is applied to the shape optimization problem. Numerical examples show that our theory is useful for practical purpose and the proposed algorithm is feasible. (C) 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 26: 1642-1659, 2010
We propose an adaptive notch filter that realizes the phase shift of the all-pass filter by the expression of Fourier sine series. The method of controlling the weights of the all-pass filter formed by IIR filters is ...
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We propose an adaptive notch filter that realizes the phase shift of the all-pass filter by the expression of Fourier sine series. The method of controlling the weights of the all-pass filter formed by IIR filters is well known. However, these adaptive notch filters have not been put to practical use due to the peculiar stability problems of IIR filters and the problem of determining the degree of the IIR filter. The proposed adaptive notch filter is always stable since the all-pass filter is formed by exponential filters. Furthermore, the adaptive algorithm is a simple gradient-based algorithm and convergence of weights is guaranteed. The degree of the all-pass filter depends only on the required steepness of the elimination characteristic and does not depend on the number of narrowband signals that are to be eliminated. Furthermore, the proposed method is suitable for practical use because the elimination characteristic is hardly influenced by a broadband signal added to the narrowband signal. The analytical results and a rigorous verification of the above features by computer simulation are presented. (C) 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(5): 8-14, 2010;Published online in Wiley Inter Science (***). DOI 10.1002/ecj.10256
This paper presents the problem of shape optimization of two-dimensional viscous flow governed by the time-dependent Navier-Stokes equations. The minimization problem of the viscous dissipated energy was established i...
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This paper presents the problem of shape optimization of two-dimensional viscous flow governed by the time-dependent Navier-Stokes equations. The minimization problem of the viscous dissipated energy was established in the fluid domain. The discretization of Navier-Stokes equations is accomplished using a new stabilized finite element method in space and finite difference in time. This new method does not need a stabilization parameter or calculation of high-order derivatives. We derive the structures of the discrete Eulerian derivative of the cost functional by a discrete adjoint method with a function space parametrization technique. A gradient-type optimization algorithm with a mesh adaptation technique and a mesh moving strategy is effectively implemented. Copyright (C) 2009 John Wiley & Sons, Ltd.
This paper presents an optimized distributed multiple-input multiple-output (OD-MIMO) for cooperative communication in wireless relay networks. The set of cooperating nodes is a priori unknown. In order to avoid the c...
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This paper presents an optimized distributed multiple-input multiple-output (OD-MIMO) for cooperative communication in wireless relay networks. The set of cooperating nodes is a priori unknown. In order to avoid the centralized stream and pilot allocation procedure, a fixed signature vector (SV) is assigned for each node in the network. We analyze the constraints of the proposed scheme, and derive an optimization criterion for the decision of the SVs. A gradient-based algorithm for SV design is provided. Simulation results show that the performance loss of OD-MIMO compared to centralized distributed MIMO is small for large number of cooperative relay nodes.
In this paper, numerical aspects of a sensitivity control for the semi-active suspension system with a magnetorheological (MR) damper are investigated A 2-dof quarter-car model together with a 6th order polynomial mod...
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In this paper, numerical aspects of a sensitivity control for the semi-active suspension system with a magnetorheological (MR) damper are investigated A 2-dof quarter-car model together with a 6th order polynomial model for the MR damper are considered. For the purpose of suppressing the vertical acceleration of the sprung-mass, the square of the vertical acceleration is defined as a cost function and the current input to the MR damper is adjusted in the fashion that the current is updated in the negative gradient of the cost function. Also, for improving the ride comfort, a weighted absolute velocity of the sprung-mass is added to the control law. The implementation of the proposed algorithm requires only the measurement of the relative displacement of the suspension deflection. The local stability of the equilibrium point of the closed loop nonlinear system is proved by investigating the eigenvalues of the linearized one. Through simulations, the passive suspension, the skyhook control, and the proposed sensitivity control are compared.
In order to solve the problems of slow tracking speed and low accuracy in vehicle mobile satellite communication system, a new step tracking algorithm based on the steepest descent method was proposed. This algorithm ...
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ISBN:
(纸本)9781424455379
In order to solve the problems of slow tracking speed and low accuracy in vehicle mobile satellite communication system, a new step tracking algorithm based on the steepest descent method was proposed. This algorithm adjusted the tracking direction and step size by the steepest descent method, and set the proper threshold to stop tracking. The simulation results showed that the numbers of tracking were reduced to17 steps and tracking accuracy is improved.
A type-2 fuzzy neural system (T2FNS) is proposed in this paper for process control. The structure of the system is presented and the rules for updating its parameters are derived using the gradient algorithm. The effe...
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ISBN:
(纸本)9781424452262
A type-2 fuzzy neural system (T2FNS) is proposed in this paper for process control. The structure of the system is presented and the rules for updating its parameters are derived using the gradient algorithm. The effectiveness of the proposed approach is evaluated on a laboratory setup that regulates the speed of a DC motor and the experimental results are compared with those obtained with the use of a type-1 fuzzy neural system (T1FNS). It is seen that T2FNS results in reduced oscillations around the set point in the presence of load disturbances.
In general conditions, most blind source separation algorithms are established on noisy-free model and ignore the noise that affects the quality of separated sources. Firstly, this paper introduces an improved natural...
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In general conditions, most blind source separation algorithms are established on noisy-free model and ignore the noise that affects the quality of separated sources. Firstly, this paper introduces an improved natural gradient algorithm based on bias removal technology to estimate the demixing matrix under noisy environment. Then the discrete wavelet transform technology is applied to the separated signals to further remove noise. In order to improve the separation effect, this paper analyzes the deficiency of hard threshold and soft threshold, and proposes a new wavelet threshold function based on the wavelet decomposition and reconfiguration. The simulations have verified that this method improves the signal noise ratio （SNR） of the separation results and the separation precision.
We present two different implementations of the Fourier domain preconditioned conjugate gradient algorithm (FD-PCG) to efficiently solve the large structured linear systems that arise in optimal volume turbulence esti...
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We present two different implementations of the Fourier domain preconditioned conjugate gradient algorithm (FD-PCG) to efficiently solve the large structured linear systems that arise in optimal volume turbulence estimation, or tomography, for multi-conjugate adaptive optics (MCAO). We describe how to deal with several critical technical issues, including the cone coordinate transformation problem and sensor subaperture grid spacing. We also extend the FD-PCG approach to handle the deformable mirror fitting problem for MCAO. (c) 2006 Optical Society of America
In order to solve the problems of slow tracking speed and low accuracy in vehicle mobile satellite communication system, a new step tracking algorithm based on the steepest descent method was proposed. This algorithm ...
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In order to solve the problems of slow tracking speed and low accuracy in vehicle mobile satellite communication system, a new step tracking algorithm based on the steepest descent method was proposed. This algorithm adjusted the tracking direction and step size by the steepest descent method, and set the proper threshold to stop tracking. The simulation results showed that the numbers of tracking were reduced to17 steps and tracking accuracy is improved.
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