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In this paper, we study the quadratic model updating problems by using symmetric low-rank correcting, which incorporates the measured model data into the analytical quadratic model to produce an adjusted model that matches the experimental model data, and minimizes the distance between the analytical and updated models. We give a necessary and sufficient condition on the existence of solutions to the symmetric low-rank correcting problems under some mild conditions, and propose two algorithms for finding approximate solutions to the corresponding optimization problems. The good performance of the two algorithms is illustrated by numerical examples. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper formulates, analyses and discusses 2D and 3D static and dynamic model problems in the orthopaedic practice. Finite element approximations, algorithms and iterative methods for constrained optimization are discussed. Since the conjugate gradient method is one of the most effective methods for both unconstrained and constrained optimization, it can be applied without or with preconditioning for solving the basic step of the discretized problem. A comparison of several preconditioned conjugate gradient methods is discussed. The problems discussed are applied to analyses of real patients. Finally, the the numerical results are discussed. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The local neighborhood search method is one of the efficient strategies for approximation algorithms for many combinatorial problems contained in the NP-complete class. To evaluate this kind of approximation method, the average case analysis is considered to be better than the worst case analysis. This paper considers the 0 - 1 knapsack problem, one of the representative problems included in the NP-complete class of problems. Then the behavior of the local neighborhood search method is analyzed for the problem using a flow model we proposed on a previous occasion. By comparing the analytical result for the 0 - 1 knapsack problem instances with up to 200 variables, we show that the flow model is useful as the means of analyzing the behavior of the local neighborhood search method for the 0 - 1 knapsack problem. [ABSTRACT FROM AUTHOR]

This paper aims at the realization of a discrete-time lossless scattering system, and proposes a plane-rotation algorithm in which the pipelined processing can be applied. In the proposed method, the CORDIC algorithm is divided into unit operations. The operational cells realizing the individual unit operation are connected in cascade to reconstruct the CORDIC algorithm into a pipeline. This configuration by the cascade connection realizes the pipelined processing and has a high modularity since the structure is a linear array of the unit cells. Next, the operational error in the proposed algorithm is classified into the error due to the finite operation and the error due to the finite word-length. A design for the algorithm is presented based on the result of analysis. The feature of the proposed design method is that the necessary operations can be extracted from the specified range of the finite operation error and the rotation angle, while minimizing the finite word-length error of the algorithm. Finally, application examples are shown for the wave digital filter and the sinusoidal pair oscillator. [ABSTRACT FROM AUTHOR]

Explicit finite-element programs, such as DYNA3D, are frequently used to solve large structural problems, such as automobile impacts, that involve tens of thousands of shell elements. Since the explicit finite-element programs do not use a stiffness matrix, the major cost of the calculation is the evaluation of the force vector. A significant part of that cost is the evaluation of the constitutive models. The standard algorithm for integrating J2 plasticity at the stress points is the radial return method. An iterative variation of radial return is commonly used to impose the zero normal stress condition within the shell elements. In this paper we explore several different non-iterative methods that impose the zero normal stress condition in an approximate manner. We show that the cost of the constitutive evaluation can be reduced by 25 per cent without introducing significant errors. [ABSTRACT FROM AUTHOR]