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A specific rod model based efficient analysis and design of hanger installation for self-anchored suspension bridges with 3D curved cables

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ENGINEERING STRUCTURES 2016年 110卷 184-208页

作者： Sun, Yuan Zhu, Hong-Ping Xu, Dong Huazhong Univ Sci & Technol Sch Civil Engn & Mech Wuhan 430074 Peoples R China Tongji Univ Sch Civil Engn Dept Bridge & Tunnel Engn Shanghai 200092 Peoples R China

Hanger installation is important in constructing self-anchored suspension bridges. The installation plan is obtained from comparative studies of concerned information in tentative construction steps. The comparisons are generally performed manually using detailed nonlinear finite element method (NFEM), particularly for those with 3D curved cables. However, the procedure is complex and time consuming. Thus, this study proposes an efficient method to analyze mainly concerned parameters of hanger installation plan, through which automatically optimized strategy of updating ideal construction steps is developed to yield the plan totally by linear coordinate iteration. To realize it, an indiscrimination coordinate rod model (ICRM) combined with coordinate iteration-based methods (CIMs) is proposed for the modeling of the construction steps. The ICRM simulates the major deformation system of the total bridge with specific rods, and then the CIMs identify its equilibrium by linear algorithms to solve the coordinates directly. On the basis, NFEM can be avoided and the design efficiency is greatly improved for the plan. The effectiveness of the proposed method is demonstrated by comparison case studies, field test verification and application discussion in a real-scale bridge. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Hanger installation Construction step analysis numerical algorithms Nonlinear finite element method Suspension bridge Unstrained length

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Methodically unified procedures for a conditional approach to outlier detection, clustering, and classification

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INFORMATION SCIENCES 2021年 560卷 504-527页

作者： Kulczycki, Piotr Franus, Krystian Polish Acad Sci Ctr Informat Technol Data Anal Methods Syst Res Inst Warsaw Poland AGH Univ Sci & Technol Fac Phys & Appl Comp Sci Div Informat Technol & Syst Res Krakow Poland

The subject of this study is three fundamental procedures of contemporary data analysis: outlier detection, clustering and classification. These issues are considered in a conditional approach ? the introduction of specific (e.g., current) values to the model allows, in practice, a significantly precise description of the reality under research. The same methodology has been used for all three of the above tasks, and it considerably facilitates the interpretations, potential modifications and practical applications of the material investigated. Using non-parametric methods frees the procedures under investigation from a distribution in the considered dataset. This paper contains a complete set of formulas that allow easy implementation of the presented material in real-world problems. ? 2020 Elsevier Inc. All rights reserved.

关键词： Data analysis Data mining Outlier detection Clustering Classification Conditional approach Distribution-free methods numerical algorithms

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DSF chain for biorthogonal polynomials and its application to matrix eigenvalue problems

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2019年 347卷 273-295页

作者： Mukaihira, Atsushi Tsuboi, Yoshimasa Doshisha Univ Fac Sci & Engn Kyotanabe Kyoto Japan

A discrete-time integrable system, called the DSF chain, is derived from the compatibility condition of spectral equations for biorthogonal polynomials associated with the discrete Schur flow. The DSF algorithm for computing eigenvalues of a type of matrix eigenvalue problem is designed. A discrete analogue of the Miura transformation between the discrete Schur flow and the qd-algorithm is constructed. Two special solutions to the DSF chain related to q-special functions are presented. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Schur flow Qd-algorithm Matrix eigenvalue problems numerical algorithms Integrable systems Biorthogonal polynomials

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Sequential simulation and neural network in the stress-strain curve identification over the large strains using tensile test

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ARCHIVE OF APPLIED MECHANICS 2017年第6期87卷 1077-1093页

作者： Jenik, Ivan Kubik, Petr Sebek, Frantisek Hulka, Jiri Petruska, Jindrich Honeywell Technol Solut Turanka 100-1387 Brno 62700 Czech Republic Brno Univ Technol Inst Solid Mech Mechatron & Biomec Fac Mech Engn Tech 2896 2 Brno 61669 Czech Republic Inst Appl Mech Resslova 972-3 Brno 60200 Czech Republic

Two alternative methods for the stress-strain curve determination in the large strains region are proposed. Only standard force-elongation response is needed as an input into the identification procedure. Both methods are applied to eight various materials, covering a broad spectre of possible ductile behaviour. The first method is based on the iterative procedure of sequential simulation of piecewise stress-strain curve using the parallel finite element modelling. Error between the computed and experimental force-elongation response is low, while the convergence rate is high. The second method uses the neural network for the stress-strain curve identification. Large database of force-elongation responses is computed by the finite element method. Then, the database is processed and reduced in order to get the input for neural network training procedure. Training process and response of network is fast compared to sequential simulation. When the desired accuracy is not reached, results can be used as a starting point for the following optimization task.

关键词： Ductility Constitutive behaviour Metallic materials numerical algorithms Optimization Elastic-plastic deformation

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Distribution of points on a sphere with application to star catalogs

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2000年第1期23卷 130-137页

作者： Bauer, R Bauer Engn Enterprises Langhorne PA 19047 USA

A new framework is introduced to analyze the spatial distribution of stars in a catalog, namely, the Voronoi diagram/Delaunay triangulation. The Voronoi diagram is a subdivision of the celestial sphere into polygonal cells, one for each star, so that the cell for star P consists of the region on the sphere closer to P than to any other star. The Delaunay triangulation is the topological dual with the important property that each spherical cap circumscribing a triangle contains no stars in its interior. Measures of the uniformity in star density and geometric arrangement based on the Voronoi diagram/Delaunay triangulation are presented and compared with existing measures, Methods to generate uniformly distributed points on the sphere, which serve as useful test cases for stellar attitude determination analysis, are formulated and compared. One such method, based on a spherical spiral, is easy to implement and yields a very uniform distribution of points. Finally, the Voronoi density reduction method is introduced to select stars for an onboard catalog from a larger candidate set. The candidate with the smallest Voronoi cell is removed, and the Voronoi diagram of the reduced set is constructed. This process is repeated until the desired number of stars remains.

关键词： Space Shuttle Attitude Determination algorithms Spacecraft Attitude Data Structures Satellites Earth Space Shuttle Missions numerical algorithms Geometry Functions Computer Memory

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Density Matrix Renormalization Group for Dummies

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JOURNAL OF COMPUTATIONAL AND THEORETICAL NANOSCIENCE 2008年第7期5卷 1277-1288页

作者： De Chiara, Gabriele Rizzi, Matteo Rossini, Davide Montangero, Simone INFM CNR NEST I-56126 Pisa Italy Scuola Normale Super Pisa I-56126 Pisa Italy BEC INFM CNR I-38050 Trento Italy Univ Trent Dipartimento Fis I-38050 Trento Italy

We describe the Density Matrix Renormalization Group algorithms for time dependent and time independent Hamiltonians. This paper is a brief but comprehensive introduction to the subject for anyone willing to enter in the field or write the program source code from scratch. An open source version of the code can be found at: http://***.

关键词： numerical algorithms One-Dimensional Systems Static and Dynamic Simulations

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Using permuted graph bases in H_∞ control

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AUTOMATICA 2013年第6期49卷 1790-1797页

作者： Mehrmann, Volker Poloni, Federico TU Berlin Inst Math D-10623 Berlin Germany Univ Pisa Dipartimento Informat I-56127 Pisa Italy

We present a new numerical method (based on the computation of deflating subspaces) for the gamma-iteration in H-infinity, control in the extended matrix pencil formulation. We introduce a permuted graph representation of these subspaces, which avoids the known difficulties that arise when the iteration is based on the solution of algebraic Riccati equations but at the same time makes use of the special symmetry structures that are present in the problems. We use this representation to perform both the deflation of spurious infinity eigenvalues of the even pencils and the implementation of the inverse-free sign iteration. We show that the new method returns accurate results and is applicable in many situations where conventional methods fail. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Algebraic Riccati equations Robust control numerical algorithms Inverse-free algorithms Matrix sign iteration

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Discrete Total Variation with Finite Elements and Applications to Imaging

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JOURNAL OF MATHEMATICAL IMAGING AND VISION 2019年第4期61卷 411-431页

作者： Herrmann, Marc Herzog, Roland Schmidt, Stephan Vidal-Nunez, Jose Wachsmuth, Gerd TU Chemnitz Fac Math D-09107 Chemnitz Germany Julius Maximilians Univ Wurzburg Fac Math & Comp Sci Lehrstuhl Math 6 Emil Fischer Str 40 D-97074 Wurzburg Germany Brandenburgische Tech Univ Cottbus Senftenberg Inst Math Chair Optimal Control Pl Deutsch Einheit 1 D-03046 Cottbus Germany

The total variation (TV)-seminorm is considered for piecewise polynomial, globally discontinuous (DG) and continuous (CG) finite element functions on simplicial meshes. A novel, discrete variant (DTV) based on a nodal quadrature formula is defined. DTV has favorable properties, compared to the original TV-seminorm for finite element functions. These include a convenient dual representation in terms of the supremum over the space of Raviart-Thomas finite element functions, subject to a set of simple constraints. It can therefore be shown that a variety of algorithms for classical image reconstruction problems, including TV-L-2 denoising and inpainting, can be implemented in low- and higher-order finite element spaces with the same efficiency as their counterparts originally developed for images on Cartesian grids.

关键词： Discrete total variation Dual problem Image reconstruction numerical algorithms

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A Novel Real-Time Filtering Method to General Nonlinear Filtering Problem Without Memory

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IEEE ACCESS 2021年 9卷 119343-119352页

作者： Shi, Ji Chen, Xiuqiong Yau, Stephen Shing-Toung Capital Normal Univ Beijing Adv Innovat Ctr Imaging Theory & Technol Acad Multidisciplinary Studies Beijing 100048 Peoples R China Tsinghua Univ Yau Math Sci Ctr Beijing 100084 Peoples R China Tsinghua Univ Dept Math Sci Beijing 100084 Peoples R China Yanqi Lake Beijing Inst Math Sci & Applicat Beijing 101408 Peoples R China

In this paper, the filtering problem for the general time-invariant nonlinear state-observation system is considered. Our work is based on the Yau-Yau filtering framework developed by S.-T. Yau and the third author in 2008. The key problem of Yau-Yau filtering framework is how to compute the solution to forward Kolmogorov equation (FKE) off-line effectively. Motivated by the supervised learning in machine learning, we develop an efficient method to numerically solve the FKE off-line from the point of view of optimization. Specifically, for the off-line computation part, the computation of the solution to a FKE is reduced to computing a linear system of equations by making the temporal inverse transformation and the loss function optimization, and we store the results for the preparation of on-line computation. For the on-line computation part, the unnormalized density function is approximated by a complete polynomial basis, and then the estimation of the state is computed using the stored off-line data. Our method has the merits of easily implementing, real-time and memoryless. More importantly, it can be applicable for moderate-high dimensional cases. numerical experiments have been carried out to verify the feasibility of our method. Our algorithm outperforms extended Kalman filter, unscented Kalman filter and particle filter both in accuracy and costing time.

关键词： Real-time systems Kalman filters Approximation algorithms Mathematical model Density functional theory Supervised learning Optimization Duncan-Mortensen-Zakai equation nonlinear filtering forward Kolmogorov equation estimation theory numerical algorithms

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OPTIMAL DISCRETE-TIME STATIC OUTPUT-FEEDBACK DESIGN - A W-DOMAIN APPROACH

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1992年第5期15卷 1175-1183页

作者： HA, C LY, UL University of Washington Seattle Washington 98195

Presented in this paper is an alternative design methodology for optimal discrete-time control-law synthesis (i..e, what we call a W-design method). The proposed method solves an optimal static output-feedback design for sampled-data systems with a given known sampling time. The overall scheme involves the formulation of an exact optimal control problem for discrete-time systems using a state-space transformation and an equivalent quadratic cost function in the w domain. A one-to-one relationship between a set of stabilizing feedback gains in the w domain and those in the traditional z domain has been established. The optimal output-feedback gain obtained from the minimization of the equivalent cost functional expressed in the w domain will yield the same optimum solution as the one obtained traditionally in the z domain. An attractive feature of this procedure is that design solutions can be obtained using only continuous-time-domain techniques. The procedure is demonstrated with the synthesis of a longitudinal-axis stability augmentation system for a commercial transport.

关键词： Full State Feedback Continuous Time Algebraic Riccati Equation Sampled Data Systems Stability Augmentation Systems Closed Loop System Angle of Attack numerical algorithms Frequency Domain Riccati Equations Airspeed

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