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The LFOPC leap-frog algorithm for constrained optimization

COMPUTERS & MATHEMATICS WITH APPLICATIONS 2000年第8-9期40卷 1085-1096页

作者： Snyman, JA Univ Pretoria Dept Mech & Aeronaut Engn Multidisciplinary Design Optimizat Grp ZA-0002 Pretoria South Africa

This paper describes an accurate and reliable new algorithm (LFOPC) for solving constrained optimization problems, through a three-phase application of the well-established leap-frog method for unconstrained optimization, to penalty function formulations of the original constrained problems. The algorithm represents a considerable improvement over an earlier version (LFOPCON) which requires the judicious choice of parameter settings for efficient use. The current algorithm automatically executes normalization and scaling operations on the gradients of the constraints. This results in a robust algorithm that, apart from convergence tolerances, requires virtually no parameter settings. The method has been well tested, on both standard analytical test problems and practical engineering design problems. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： constrained optimization leap-frog method robust algorithm penalty function formulations

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Solving Problems on Special Classes of Graphs

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Electronic Notes in Discrete Mathematics 2000年 5卷 266-269页

作者： Raghavan, Vijay Spinrad, Jeremy P. EECS Dept Vanderbilt University Nashville TN 37235 United States

Most papers which solve a problem on a graph class assume there is a promise that the input is in the class. Thus, the algorithm could produce incorrect output, or fail to terminate in the time bound claimed, if the input is not in the class. We propose a stricter notion of solving problems on special classes of graphs. If a graph G is not in the class, the algorithm may either answer the problem correctly, or announce that G is not in the class. We call such an algorithm a robust algorithm. This talk describes robust algorithms for problems on classes where no robust algorithm was known previously, shows that some problems which can be solved on classes in polynomial time given a promise that the graph is in the class are intractable for robust algorithms, and poses open problems. We show that the clique problem on unit disk graphs can be solved robustly. Previous solutions needed a geometric model as input. We also show that no robust polynomial algorithm solves independent set on well-covered graphs unless P = NPM. © 2002 Elsevier Ltd. All rights reserved.

关键词： NP-complete robust algorithm unit disk graph well-covered graph

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Probing of two-dimensional grid patterns by means of camera based image processing

Probing of two-dimensional grid patterns by means of camera ...

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Conference on Machine Vision Applications in Industrial Inspection VIII

作者： Schroeck, M Doiron, T Inst Phys High Technol Jena Germany

ISBN: (纸本)0819435848

Camera based probes and machine vision have found increased use in coordinate measuring machines over the past years and the calibration of artifacts for these probes has become an important task for NIST. Until recently these artifacts have been calibrated using one or two dimensional measuring machines with electro-optic microscopes or scanning devices as probes. These sensors evaluate only a small section of the edge of a grid mark, and irregularities in this particular spot from local deformations or contamination influence the measurement result. Since these measurements result in a single number based on the entire field of view, the influence of small irregularities are not easily detected. Since different probes scan different parts of the grid mark edge they may give systematically different positions of the mark. The conversion to video based sensors has allowed more flexibility it edge detection, although most instruments still use least squares fits as the substitute geometry of straight edges. This method is very susceptible to noise and edge irregularities. We present some experiments for finding the sub-pixel edge point locations and fitting the set of edge points to a line using a fairly simple least sum of absolute deviations fit. Data from a high accuracy 2D measuring machine is used to show the strengths of the algorithms.

关键词： robust algorithm computer vision edge finding least sum of absolute deviations

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Intergrid-boundary definition method for overset unstructured grid approach

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AIAA JOURNAL 2000年第11期38卷 2077-2084页

作者： Nakahashi, K Togashi, F Sharov, D Tohoku Univ Dept Aeronaut & Space Engn Sendai Miyagi 9808579 Japan Sci Applicat Int Corp Ctr Appl Computat Sci Adv Technol Grp Mclean VA 22102 USA

The use of the overset concept for the unstructured grid method is relatively unexplored. However, the overset approach can extend the applicability of the unstructured grid method for real engineering problems without much need for code development. The multiple moving-body problem is one of those applications. Improvement in local resolution for Euler/Navier-Stokes computations on unstructured grids is another use of the overset concept. An efficient and robust algorithm to localize the intergrid boundaries for the overset unstructured grid method is proposed. Simplicity and automation in the intergrid-boundary definition are realized using the wall distance as a basic parameter. The neighbor-to-neighbor jump search algorithm is efficiently utilized in the method. The robustness and efficiency of the search is improved by the use of subsidiary grids that are generated as a byproduct of the Delaunay triangulation method. The basic procedure of the present method is described for a multielement airfoil problem. The effects of the overset method on the solution accuracy and the convergence are tested by ONERA M6-wing. The capability of the method is demonstrated by application to an airplane-rocket boaster separation problem.

关键词： Unstructured Grid Supersonic Airplane Rockets Search algorithm robust algorithm Airfoil Angle of Attack Freestream Mach Number Courant Friedrichs Lewy Stokes Problem

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robust algorithms for principal component analysis

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PATTERN RECOGNITION LETTERS 1999年第9期20卷 927-933页

作者： Yang, TN Wang, SD Natl Taiwan Univ Dept Elect Engn Taipei 106 Taiwan

In this paper, we address the issues related to the design of fuzzy robust principal component analysis (FRPCA) algorithms. The design of robust principal component analysis has been studied in the literature of statistics for over two decades. More recently Xu and Yuille proposed a family of online robust principal component analysis based on statistical physics approach. We extend Xu and Yuille's objective function by using fuzzy membership and derive improved algorithms that can extract the appropriate principal components from the spoiled data set. The difficulty of selecting an appropriate hard threshold in Xu and Yuille's approach is alleviated by replacing the threshold by an automatically selected soft threshold in FRPCA. Artificially generated data sets are used to evaluate the performance of various PCA algorithms. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： principal component analysis robust algorithm noise clustering neural networks fuzzy theory

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Improvement for solving the mix-up problem in constant modulus arrays

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ELECTRONICS LETTERS 1999年第25期35卷 2161-2163页

作者： Volani, K Constantinides, AG Univ London Imperial Coll Sci Technol & Med Dept Elect & Elect Engn London SW7 2BT England

The authors propose an efficient and computationally fast algorithm for solving the mix-up problem in complex arrays. The Lagrange multiplier theory is used in the optimisation of the constant modulus algorithm (CMA) cost function and the input data are processed in blocks. Furthermore, a simplification of the CMA cost function is proposed that leads to a robust algorithm for solving this problem. Simulations are presented to support the analysis.

关键词： mix-up problem Communication channel equalisation and identification QAM array signal processing quadrature amplitude modulation cost function blind adaptive equalisers blind equalisers adaptive equalisers constant modulus arrays Lagrange multiplier theory Signal processing and detection constant modulus algorithm robust algorithm CMA cost function

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robust interference calculation for curved solids - Computation of tangent points and construction of intersection graph

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Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering 1999年第3期65卷 423-428页

作者： Nakamura, Hiroyuki Higashi, Masatake

This paper extends the method for the construction of the intersection graph, which was proposed by the authors for polyhedral solids, to curved solids. In order to be robust against numerical errors, the method exploits the topological connectivity properties of the edge-face intersection points. Furthermore, as a part of the algorithm for the construction of the intersection graph, this paper presents a new method for the computation of the tangent points between an intersection curve and a boundary curve of a surface.

关键词： Interference calculation robust algorithm Solid model Symbol processing Tangent points

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Configuring RBF neural networks

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ELECTRONICS LETTERS 1998年第7期34卷 684-685页

作者： Sohn, I Ansari, N New Jersey Inst Technol Dept Elect & Comp Engn Newark NJ 07102 USA

A novel method (based on the characteristics of scatter matrices and frequency-sensitive competitive learning) for training the hidden layer of a radial basis fraction neural network is proposed. The method is demonst... 详细信息

关键词： RBF neural network S-matrix theory SBC feedforward neural nets frequency-sensitive competitive learning hidden layer radial basis function neural network robust algorithm scatter matrix training unsupervised learning

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algorithm for the Wigner distribution of noisy signals realisation

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ELECTRONICS LETTERS 1998年第7期34卷 622-624页

作者： Stankovic, LJ Ruhr Univ Bochum Signal Theory Grp D-44780 Bochum Germany

A simple robust algorithm which efficiently represents signals with a very high amount of noise is presented, according to the expressions for the mean, variance and the optimal window width of the Wigner distribution... 详细信息

关键词： Wigner distribution Wigner distribution filtering theory interference (signal) noise noisy signals representation robust algorithm signal representation time-varying filtering time-varying filters

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robust algorithms for face-based representations

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COMPUTER-AIDED DESIGN 1997年第2期29卷 135-146页

作者： Higashi, M Torihara, F Takeuchi, N Sata, T Saitoh, T Hosaka, M TOKYO DENKI UNIV CHIYODA KUTOKYO 101JAPAN

This paper proposes a new face-based data structure and robust algorithms for processing polyhedra. The face-based structure is introduced for representing designers' intentions and constraints on faces without redundancy as well as machining features for the faces, and for handling computational errors. To construct the algorithms, the following three principles are employed. Fundamental data are coefficients of plane equations, and coordinate values of vertices which include computational errors are treated as secondary. Incidence tests among geometrical elements such as vertices, edges and faces are performed based on a determinant value of four faces. A local topological structure, where many faces intersect near a point and ambiguities of the topology remain, is determined as a tree structure so as not to make small faces according to the global feature of the shape in terms of a sequence of the face segments and edge classification as concave and convex. In this paper, the incidence test is explained geometrically. algorithms for Boolean set operations are presented along with classification of incidence patterns, and some examples executed with them are shown. Copyright (C) 1996 Elsevier Science Ltd

关键词： solid modelling face-based representation robust algorithm

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