In a previous work, rite generalized forward-backward (GFB) method was proposed to compute the scattering from targets on rough ocean-like surfaces. In this paper, we develop an acceleration of the GFB method bused on...
详细信息
In a previous work, rite generalized forward-backward (GFB) method was proposed to compute the scattering from targets on rough ocean-like surfaces. In this paper, we develop an acceleration of the GFB method bused on the fast multipole method (FMM). The FMM is adapted ro reduce the operational cost associated with the iterative computations in the target regions. The proposed method is shown to converge in a low number of iterations and allows a significant reduction in the computational and storage costs with respect to the conventional GFB formulation. (C) 2000 John Wiley & Sons, Inc.
In this paper, we present some iterative algorithms, mainly Schwarz algorithms, for an implicit two-sided obstacle problem. The monotonic convergence of the algorithms is proved. (C) 2001 Elsevier Science Ltd. All rig...
详细信息
In this paper, we present some iterative algorithms, mainly Schwarz algorithms, for an implicit two-sided obstacle problem. The monotonic convergence of the algorithms is proved. (C) 2001 Elsevier Science Ltd. All rights reserved.
The synthesis of strictly positive real H(2) controllers for collocated control of large space structures is addressed. To perform this synthesis, a convex optimization technique has already been developed using linea...
详细信息
The synthesis of strictly positive real H(2) controllers for collocated control of large space structures is addressed. To perform this synthesis, a convex optimization technique has already been developed using linear matrix inequalities. This existing technique is based on two design criteria: strict positive realness and the use Of H(2) norm as the criterion for optimization. It adopts a common Lyapunov solution to both of these criteria, which results in undesirable conservatism. To reduce this conservatism, a new synthesis technique based on iterative algorithms that can produce superior, noncommon Lyapunov solutions is proposed. Even if a common Lyapunov solution is infeasible, the proposed technique can yield feasible, strictly positive real H(2) controllers. An illustrated example is included.
It has been shown by some researchers that in a problem of weighted least-square (WLS) design of finite-impulse response (FIR) filters, bulk of the design computation is concerned with the evaluation of the inverse of...
详细信息
It has been shown by some researchers that in a problem of weighted least-square (WLS) design of finite-impulse response (FIR) filters, bulk of the design computation is concerned with the evaluation of the inverse of a matrix in order to solve a system of equations. In this paper, a new algorithm for the WLS design of FIR filters is presented, in which an iterative procedure is developed for the inversion of the matrix involved in the design. By imposing a mild constraint on the updation factor of the weighting function, the inverse of a matrix is expanded as a convergent power series. By investigating the properties of some of the matrices from the design formulation, a modified version of the series that converges rapidly is then proposed to evaluate the inverse in each iteration. It is shown,that due to the fast convergence of the power series, one needs to evaluate only the first two or three terms of the series except during the initial stages of the iterations, implying that the conventional operation for matrix inversion is simplified significantly.
A set of partial differential equations is developed to describe the mass-distributed and extensible tether satellite system. Supplemented with a range-rate control algorithm and proper boundary conditions, the system...
详细信息
A set of partial differential equations is developed to describe the mass-distributed and extensible tether satellite system. Supplemented with a range-rate control algorithm and proper boundary conditions, the system can be studied either by the numerical integration of the equations or by considering the stationary motion (configuration) in the system. The former approach is not adequate because (if the integration is possible) it requires very high mathematical skill and huge amount of computations. On the contrary, the stationary configuration is easier to determine and provides more valuable information about the system as a whole. The stable stationary configuration is essentially all that is needed to carry out a tether mission in space. An iterative algorithm to compute the stationary configuration and a method of its stability analysis is proposed. Finally, a numerical simulation is given.
The max-bisection problem is an NP-hard combinatorial optimization problem. In this paper an equivalent linearly constrained continuous optimization problem is formulated and a deterministic annealing algorithm is pro...
详细信息
The max-bisection problem is an NP-hard combinatorial optimization problem. In this paper an equivalent linearly constrained continuous optimization problem is formulated and a deterministic annealing algorithm is proposed for approximating its solution. The algorithm is derived from the introduction of a square-root barrier function, where the barrier parameter behaves as temperature in an annealing procedure and decreases from a sufficiently large positive number to 0. The algorithm searches for a better solution in a feasible descent direction, which has a desired property that lower and upper bounds on variables are always satisfied automatically if the step length is a number between 0 and 1. We prove that the algorithm converges to at least an integral local minimum point of the continuous problem if a local minimum point of the barrier problem is generated for a sequence of descending values of the barrier parameter with zero limit. Numerical results show that the algorithm is much faster than one of the best existing approximation algorithms while they produce more or less the same quality solution. (C) 2002 Published by Elsevier Science Ltd.
When concentrated roots exist, the precision of the dynamic flexibility method proposed previously by the authors is changed severely to be poor because a power series in the method closes in divergency. For this reas...
详细信息
When concentrated roots exist, the precision of the dynamic flexibility method proposed previously by the authors is changed severely to be poor because a power series in the method closes in divergency. For this reason, a dynamic flexibility method with hybrid shifting frequency is developed. This new dynamic flexibility method applies a hybrid shifting frequency technique, that is, two shifting frequency values, Deltaomega(1) and Deltaomega(2), are put up. So a hybrid shifting frequency system is obtained. In this system Deltaomega(1) is used to guarantee that the stiffness matrix of the system is always nonsingular, and Deltaomega(2) is employed to accelerate the convergence of the power series contained in the present system. Thus the dynamic flexibility method with hybrid shifting frequency is suitable to the concentrated root condition. However, the eigenvector derivative of this hybrid shifting frequency system is not the same as that of the original system. To give the eigenvector derivatives of the original system, the relationship between dynamic flexibility matrices of the original and the hybrid shifting frequency system is first established. Then the eigenvector derivatives of the original system can be found from the eigenvector derivatives of the hybrid shifting frequency system. In words, this method is powerful and suitable for any (constrained and free) structures with concentrated roots.
In this paper, a new notion of J-proximal mapping for a nonconvex lower semicontinuous subdifferentiable proper functional on Banach space is introduced. The existence and Lipschitz continuity of J-proximal mapping of...
详细信息
In this paper, a new notion of J-proximal mapping for a nonconvex lower semicontinuous subdifferentiable proper functional on Banach space is introduced. The existence and Lipschitz continuity of J-proximal mapping of a lower semicontinuous subdifferentiable proper functional are proved. By applying the concept, we introduce and study a new class of completely generalized quasi-variational inclusions in reflexive Banach spaces. A novel and innovative iterative algorithm for finding the approximate solutions is suggested and analyzed. The convergence criteria of the iterative sequences generated by the new iterative algorithm is also given. These algorithm and existence result generalize many known results under Hilbert space setting in recent literature to reflexive Banach spaces. (C) 2002 Elsevier Science B.V. All rights reserved.
In this paper, we introduce a new class of generalized co-complementarity problems in Banach spaces. An iterative algorithm for finding approximate solutions of these problems is considered. Some convergence results f...
详细信息
In this paper, we introduce a new class of generalized co-complementarity problems in Banach spaces. An iterative algorithm for finding approximate solutions of these problems is considered. Some convergence results for this iterative algorithm are derived and several existence results are obtained. (C) 2001 Elsevier Science Ltd. All rights reserved.
暂无评论