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A modified downhill simplex algorithm interpolation response surface method for structural reliability analysis

ENGINEERING COMPUTATIONS 2020年第4期37卷 1423-1450页

作者： Su, Hailiang Lan, Fengchong He, Yuyan Chen, Jiqing South China Univ Technol Sch Mech & Automot Engn Guangzhou Peoples R China South China Univ Technol Sch Business Adm Guangzhou Peoples R China

Purpose Because of the high computational efficiency, response surface method (RSM) has been widely used in structural reliability analysis. However, for a highly nonlinear limit state function (LSF), the approximate accuracy of the failure probability mainly depends on the design point, and the result is that the response surface function composed of initial experimental points rarely fits the LSF exactly. The inaccurate design points usually cause some errors in the traditional RSM. The purpose of this paper is to present a hybrid method combining adaptive moving experimental points strategy and RSM, describing a new response surface using downhill simplex algorithm (DSA-RSM). Design/methodology/approach In DSA-RSM, the operation mechanism principle of the basic DSA, in which local descending vectors are automatically generated, was studied. Then, the search strategy of the basic DSA was changed and the RSM approximate model was reconstructed by combining the direct search advantage of DSA with the reliability mechanism of response surface analysis. Findings The computational power of the proposed method is demonstrated by solving four structural reliability problems, including the actual engineering problem of a car collision. Compared to specific structural reliability analysis methods, the approach of modified DSA interpolation response surface for structural reliability has a good convergent capability and computational accuracy. Originality/value This paper proposes a new RSM technology based on proxy model to complete the reliability analysis. The originality of this paper is to present an improved RSM that adjusts the position of the experimental points judiciously by using the DSA principle to make the fitted response surface closer to the actual limit state surface.

关键词： Structural reliability analysis Response surface method downhill simplex algorithm Uncertainty Limit state function Probability of failure

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Considering multiple process observables to determine material model parameters for FE-cutting simulations

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2021年第11-12期113卷 3419-3431页

作者： Hardt, Marvin Bergs, Thomas Rhein Westfal TH Aachen Lab Machine Tools & Prod Engn WZL Campus Blvd 30 D-52074 Aachen Germany Fraunhofer Inst Prod Technol IPT Steinbachstr 17 D-52074 Aachen Germany

Analyzing the chip formation process by means of the finite element method (FEM) is an established procedure to understand the cutting process. For a realistic simulation, different input models are required, among which the material model is crucial. To determine the underlying material model parameters, inverse methods have found an increasing acceptance within the last decade. The calculated model parameters exhibit good validity within the domain of investigation, but suffer from their non-uniqueness. To overcome the drawback of the non-uniqueness, the literature suggests either to enlarge the domain of experimental investigations or to use more process observables as validation parameters. This paper presents a novel approach merging both suggestions: a fully automatized procedure in conjunction with the use of multiple process observables is utilized to investigate the non-uniqueness of material model parameters for the domain of cutting simulations. The underlying approach is two-fold: Firstly, the accuracy of the evaluated process observables from FE simulations is enhanced by establishing an automatized routine. Secondly, the number of process observables that are considered in the inverse approach is increased. For this purpose, the cutting force, cutting normal force, chip temperature, chip thickness, and chip radius are taken into account. It was shown that multiple parameter sets of the material model can result in almost identical simulation results in terms of the simulated process observables and the local material loads.

关键词： Inverse identification Machining model parameters downhill simplex algorithm Johnson-Cook model Cutting simulation

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Using Covariance Matrix Adaptation Evolution Strategies for solving different types of differential equations

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SOFT COMPUTING 2019年第5期23卷 1643-1666页

作者： Chaquet, Jose M. Carmona, Enrique J. Univ Nacl Educ Distancia Escuela Tecn Super Ingn Informat Dept Inteligencia Artificial Madrid Spain

A novel mesh-free heuristic method for solving differential equations is proposed. The new approach can cope with linear, nonlinear, and partial differential equations (DE), and systems of DEs. Candidate solutions are expressed using a linear combination of kernel functions. Thus, the original problem is transformed into an optimization problem that consists in finding the parameters that define each kernel. The new optimization problem is solved applying a Covariance Matrix Adaptation Evolution Strategy. To increase the accuracy of the results, a downhill simplex local search is applied to the best solution found by the mentioned evolutionary algorithm. Our method is applied to 32 differential equations extracted from the literature. All problems are successfully solved, achieving competitive accuracy levels when compared to other heuristic methods. A simple comparison with numerical methods is performed using two partial differential equations to show the pros and cons of the proposed algorithm. To verify the potential of this approach with a more practical problem, an electric circuit is analyzed in depth. The method can obtain the dynamic behavior of the circuit in a parametric way, taking into account different component values.

关键词： Differential equations Covariance Matrix Adaptation Evolution Strategies Gaussian kernel downhill simplex algorithm

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Dynamic Hassan Nelder Mead with simplex Free Selectivity for Unconstrained Optimization

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IEEE ACCESS 2018年 6卷 39015-39026页

作者： Musafer, Hassan A. Mahmood, Ausif Univ Technol Baghdad Fac Elect & Elect Engn Baghdad 35010 Iraq Univ Bridgeport Dept Comp Sci & Engn Bridgeport CT 06604 USA Univ Bridgeport Fac Comp Sci & Engn Bridgeport CT 06604 USA

We propose a free selective simplex for the downhill Nelder Mead simplex algorithm (1965), rather than the determinant simplex that forces its elements to perform a single operation, such as reflection. Unlike the Nelder-Mead algorithm, the elements of the proposed simplex select various operations of the algorithm to form the next simplex. In this way, we allow non-isometric reflections similar to that of the Nelder Mead, triangle simplex, but with rotation through an angle, permitting the proposed algorithm to have more control over the simplex, to change its size and direction for better performance. As a consequence, the solution that comes from the proposed simplex is always dynamic adaptive in size and orientation to different landscapes of mathematical functions. The proposed algorithm is examined in a large collection of different structures and classes of optimization problems. Additionally, comparisons are made with two enhanced, up-to-date versions of the Nelder-Mead algorithm. The numerical results show that Hassan Nelder Mead is stable due to non-dependence on the number of parameters processed. It also performs a higher accuracy for high dimensions compared with the other algorithms and a faster convergence rate toward global minima with respect to the number of simplex gradient estimates.

关键词： Unconstrained optimization selective simplex Spendley-Hext-Himsworth algorithm Nelder-Mead algorithm downhill simplex algorithm

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Research on Locomotive Evolution Based on Worm-Shaped Configuration of Self-reconfigurable Robot Hit MSR II

Research on Locomotive Evolution Based on Worm-Shaped Config...

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The 2011 International Conference on Electric and Electronics(EEIC 2011)

作者： Yanhe Zhu Xiaolu Wang Xindan Cui Jingchun Yin Jie Zhao State Key Laboratory of Robotics and System Harbin Institute of Technology

In this paper, we constructed a three-dimensional dynamic simulator for Hit MSR II which is a module self-reconfigurable robot system composed of single-rotational-freedom modules. downhill simplex Optimization algorithm were used to evolve the locomotion of the robot ensuring that it is possible to get access to the relatively more optimized locomotion gaits parameters after large enough numbers of iterative calculations under a certain evaluation function. What's more. We selected worm-shaped configuration to research on the validation of locomotive evolution both in simulation and experiment.

关键词： self-reconfigurable robot 3D control simulator worm locomotive evolution downhill simplex algorithm

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AN OUT-OF-BOX APPROACH TO INTEGRATE AN OPTIMIZATION algorithm AND MAAP5 FOR PARAMETER IDENTIFICATION

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NUCLEAR TECHNOLOGY 2010年第3期172卷 237-245页

作者： Tsai, Chih-Ming Wang, Shih-Jen Chiang, Show-Chyuan Inst Nucl Energy Res Longtan Township 32546 Taoyuan County Taiwan Taiwan Power Co Taipei 10016 Taiwan

The modular accident analysis program (MAAP) is a fast-running severe accident analysis tool with which the timing of key events and source terms in a severe accident are assessed. The idea of combining MAAP and an optimization algorithm to identify the realistic accident parameters in terms of minimizing the discrepancies between the plant data and the simulation results is straightforward. In 2008 Chien and Wang first compiled the combination of the MAAP4 source codes and a simplex code as a computer-aided tool for the loss-of-coolant accident (LOCA) of the Kuosheng nuclear power plant (NPP). The break area and break elevation were successfully identified. However, in that approach to putting the idea into practice was that hard data dependence exists between MAAP and the optimization algorithm. Tedious tracing and modification work is required to ensure all plant variables in MAAP source codes with the exception of the adjusted accident parameters are identical at the beginning of every simulation. The plant- and accident-specific development features also easily limit the applications of this idea to the nuclear industry, like being boxed in. In this study a so-called "out-of-box" approach is proposed that can omit the limits of the idea applications on severe accident management. A parameter identification tool developed in this approach for the same postulated LOCA of the Kuosheng NPP is carried out for verification and validation. It demonstrates the advantages of successful parameter identification, less programming efforts, and no plant- and accident-specific features.

关键词： downhill simplex algorithm parameter identification MAAP5

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High accuracy and fast acquisition time of polarisation nulling-based OSNR monitor

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ELECTRONICS LETTERS 2010年第2期46卷 152-U75页

作者： Floridia, C. Rocha, M. de Lacerda de Moraes, J. C. Bezerra, E. W. CPqD Fdn Campinas SP Brazil Univ Sao Paulo EESC BR-05508 Sao Paulo Brazil

A technique for improving the performance of an OSNR monitor based on a polarisation nulling method with the downhill simplex algorithm is demonstrated. Establishing a compromise between accuracy and acquisition time, the monitor has been calibrated to 0.72 dB/390 ms and 0.98 dB/320 ms, over a range of nearly 21 dB. As far as is known, these are the best values achieved with such an OSNR monitoring method.

关键词： downhill simplex algorithm optical fibre networks optical fibre polarisation optical signal-to-noise ratio monitor polarisation nulling method

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New adapted Gaussian basis sets for the relativistic closed shell atoms from helium to barium generated with the generator coordinate Dirac-Fock method

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INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY 2005年第5期103卷 523-528页

作者： de Macedo, LGM Morgon, NH Haiduke, RLA Barbosa, RC da Silva, ABF Univ Sao Paulo Inst Quim Sao Carlos Dept Quim & Fis Mol BR-13560970 Sao Carlos SP Brazil Univ Estadual Campinas Inst Quim BR-13083970 Campinas SP Brazil

The generator coordinate Dirac-Fock (GCDF) method and the downhill simplex algorithm were applied to generate new adapted Gaussian basis sets for relativistic closed shell atoms from He (Z = 2) to Ba (Z = 56). These new basis sets have a size reduction of about 30% when compared to previous GCDF adapted basis sets, and are as compact as some corresponding nonrelativistic Gaussian basis sets. The truncation error is in a millihartree order of magnitude and the optimization scheme adopted here allowed the l(-) and l(+) relativistic symmetries to be different. (c) 2005 Wiley Periodicals, Inc.

关键词： relativistic Gaussian basis sets generator coordinate Dirac Fock method downhill simplex algorithm

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New adapted Gaussian basis sets for the relativistic closed shell atoms from helium to barium generated with the generator coordinate Dirac-Fock method

New adapted Gaussian basis sets for the relativistic closed ...

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12th Brazilian Symposium of Theoretical Chemistry

关键词： relativistic Gaussian basis sets generator coordinate Dirac Fock method downhill simplex algorithm

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A comparative study of Powell's and downhill simplex algorithms for a fast multimodal surface matching in brain imaging

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COMPUTERIZED MEDICAL IMAGING AND GRAPHICS 2001年第4期25卷 287-297页

作者： Bernon, JL Boudousq, V Rohmer, JF Fourcade, M Zanca, M Rossi, M Mariano-Goulart, D Nucl Med Serv Serv Med Interne Montpellier France

Multimodal images registration can be very helpful for diagnostic applications. However, even if a lot of registration algorithms exist, only a few really work in clinical routines. We developed a method based on surface matching and compared two minimization algorithms: Powell's and downhill simplex. We studied the influence of some factors (chamfer map computation, number and order of parameters to determine, minimization criteria) on the final accuracy of the algorithm. Using this comparison, we improved some processing steps to allow a clinical use, and selected the simplex algorithm which presented the best results. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： registration multimodality chamfer matching Powell's method downhill simplex algorithm

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