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Direct Position Determination of Unknown Signals in the Presence of Multipath Propagation

SENSORS 2018年第3期18卷 892-892页

作者： Du, Jianping Wang, Ding Yu, Wanting Yu, Hongyi Natl Digital Switching Syst Engn & Technol Res Ct Zhengzhou 450002 Henan Peoples R China

A novel geolocation architecture, termed "Multiple Transponders and Multiple Receivers for Multiple Emitters Positioning System (MTRE)" is proposed in this paper. Existing Direct Position Determination (DPD) methods take advantage of a rather simple channel assumption (line of sight channels with complex path attenuations) and a simplified MUltiple SIgnal Classification (MUSIC) algorithm cost function to avoid the high dimension searching. We point out that the simplified assumption and cost function reduce the positioning accuracy because of the singularity of the array manifold in a multi-path environment. We present a DPD model for unknown signals in the presence of Multi-path Propagation (MP-DPD) in this paper. MP-DPD adds non-negative real path attenuation constraints to avoid the mistake caused by the singularity of the array manifold. The Multi-path Propagation MUSIC (MP-MUSIC) method and the active set algorithm (ASA) are designed to reduce the dimension of searching. A Multi-path Propagation Maximum Likelihood (MP-ML) method is proposed in addition to overcome the limitation of MP-MUSIC in the sense of a time-sensitive application. An iterative algorithm and an approach of initial value setting are given to make the MP-ML time consumption acceptable. Numerical results validate the performances improvement of MP-MUSIC and MP-ML. A closed form of the Cramer-Rao Lower Bound (CRLB) is derived as a benchmark to evaluate the performances of MP-MUSIC and MP-ML.

关键词： direct position determination MUSIC algorithm maximum likelihood estimation convex QP multi-path geolocation active set algorithm

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Group Control Strategy of Welding Machine Based on Improved active set algorithm

Group Control Strategy of Welding Machine Based on Improved ...

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

作者： Chen Shujin Zhang Junjun Provincial key Lab of Advanced Welding Technology Jiangsu University of Science and Technology

In order to solve the group optimal control problem on welding machine of shipyard, this paper established the optimization model of operating parameters. Optimization object includes minimum the average waiting time of welding, the largest number of online welding machine and minimum transformer energy consumption. Group control system has nonlinear, multiconstraint characteristics, but the inequality constraints in this study are linear. When quadratic programming problem was solved by improved active set algorithm, the overall control strategy was obtained, which can achieve objective optimization by priority scheduling, multi-step optimization strategy, guaranteeing the production quality at the same time. This research provides a theoretical basis and foundation technology for the stable operation of welding machine group.

关键词： Welding machine Group control active set algorithm

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PROJECTION ONTO A POLYHEDRON THAT EXPLOITS SPARSITY

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SIAM JOURNAL ON OPTIMIZATION 2016年第3期26卷 1773-1798页

作者： Hager, William W. Zhang, Hongchao Univ Florida Dept Math Gainesville FL 32611 USA Louisiana State Univ Dept Math Baton Rouge LA 70803 USA

An algorithm is developed for projecting a point onto a polyhedron. The algorithm solves a dual version of the projection problem and then uses the relationship between the primal and dual to recover the projection. The techniques in the paper exploit sparsity. Sparse reconstruction by separable approximation (SpaRSA) is used to approximately identify active constraints in the polyhedron, and the dual active set algorithm (DASA) is used to compute a high precision solution. A linear convergence result is established for SpaRSA that does not require the strong concavity of the dual to the projection problem, and an earlier R-linear convergence rate is strengthened to a Q-linear convergence property. An algorithmic framework is developed for combining SpaRSA with an asymptotically preferred algorithm such as DASA. It is shown that only the preferred algorithm is executed asymptotically. Numerical results are given using the polyhedra associated with the Netlib LP test set. A comparison is made to the interior point method contained in the general purpose open source software package IPOPT for nonlinear optimization, and to the commercial package CPLEX, which contains an implementation of the barrier method that is targeted to problems with the structure of the polyhedral projection problem.

关键词： polyhedral projection SpaRSA active set algorithm dual active set algorithm DASA multilevel optimization

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An active set algorithm to estimate parameters in generalized linear models with ordered predictors

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COMPUTATIONAL STATISTICS & DATA ANALYSIS 2010年第6期54卷 1442-1456页

作者： Rufibach, Kaspar Univ Zurich Biostat Unit Inst Social & Prevent Med CH-8001 Zurich Switzerland

In biomedical studies, researchers are often interested in assessing the association between one or more ordinal explanatory variables and an outcome variable, at the same time adjusting for covariates of any type. The outcome variable may be continuous, binary, or represent censored survival times. In the absence of precise knowledge of the response function, using monotonicity constraints on the ordinal variables improves efficiency in estimating parameters, especially when sample sizes are small. An active set algorithm that can efficiently compute such estimators is proposed, and a characterization of the solution is provided. Flaying an efficient algorithm at hand is especially relevant when applying likelihood ratio tests in restricted generalized linear models, where one needs the value of the likelihood at the restricted maximizer. The algorithm is illustrated on a real life data set from oncology. (C) 2010 Elsevier B.V. All rights reserved.

关键词： Ordered explanatory variable Constrained estimation Least-squares Logistic regression Cox regression active set algorithm Likelihood ratio test under linear constraints

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Design and application of nature inspired computing approach for nonlinear stiff oscillatory problems

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NEURAL COMPUTING & APPLICATIONS 2015年第7期26卷 1763-1780页

作者： Khan, Junaid Ali Raja, Muhammad Asif Zahoor Syam, Muhammed I. Tanoli, Shujaat Ali Khan Awan, Saeed Ehsan Hamdard Univ Fac Engn Sci & Technol Islamabad Pakistan COMSATS Inst Informat Technol Dept Elect Engn Attock Pakistan UAE Univ Dept Math Sci Al Ain U Arab Emirates

In this paper, meta-heuristic intelligent approaches are developed for handling nonlinear oscillatory problems with stiff and non-stiff conditions. The mathematical modeling of these oscillators is accomplished using feed-forward artificial neural networks (ANNs) in the form of an unsupervised manner. The accuracy as well as efficiency of the model is subject to the tuning of adaptive parameters for ANNs that are highly stochastic in nature. These optimal weights are carried out with swarm intelligence and pattern search methods hybridized with an efficient local search technique based on constraints minimization known as active set algorithm. The proposed schemes are validated on various stiff and non-stiff variants of the oscillator. The significance, applicability and reliability of the proposed scheme are well established based on comparison made with the results of standard numerical solver.

关键词： Van der Pol oscillators Neural networks Swarm intelligence active set algorithm Pattern search

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The Stokes Flow with Friction

The Stokes Flow with Friction

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International Conference on Numerical Analysis and Applied Mathematics (ICNAAM)

作者： Kucera, Radek Satek, Vaclav Jarosova, Marta Kozubek, Tomas VSB Tech Univ Ostrava IT4Innovat Ostrava 70833 Czech Republic

ISBN: (纸本)9780735412873

Efficient methods for solving the Stokes problem with a friction effect simulated by the slip boundary condition are developed. The dual formulation of the problem arising from the finite element approximation leads to the minimization of the strictly quadratic function with few unknowns constrained by simple bounds. Two solution algorithms highly efficient in contact solid mechanics are tested: the active set strategy and the path-following variant of the interior point method. Numerical experiments conclude the paper.

关键词： Stokes Problem Slip Boundary Condition active set algorithm Interior Point Method

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Error estimation in nonlinear optimization

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JOURNAL OF GLOBAL OPTIMIZATION 2014年第2-3期59卷 327-341页

作者： Hager, William W. Mico-Umutesi, Delphine Univ Florida Dept Math Gainesville FL 32611 USA

Methods are developed and analyzed for estimating the distance to a local minimizer of a nonlinear programming problem. One estimate, based on the solution of a constrained convex quadratic program, can be used when strict complementary slackness and the second-order sufficient optimality conditions hold. A second estimate, based on the solution of an unconstrained nonconvex, nonsmooth optimization problem, is valid even when strict complementary slackness is violated. Both estimates are valid in a neighborhood of a local minimizer. An active set algorithm is developed for computing a stationary point of the nonsmooth error estimator. Each iteration of the algorithm requires the solution of a symmetric, positive semidefinite linear system, followed by a line search. Convergence is achieved in a finite number of iterations. The error bounds are based on stability properties for nonlinear programs. The theory is illustrated by some numerical examples.

关键词： Error bounds KKT conditions active set algorithm Nonconvex quadratic programming Nonlinear programming

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A Full Multigrid Method for Linear Complementarity Problems arising from Elastic Normal Contact Problems

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MATHEMATICAL MODELLING AND ANALYSIS 2014年第2期19卷 216-240页

作者： Zhao, Jing Vollebregt, Edwin A. H. Oosterlee, Cornelis W. Delft Univ Technol NL-2628 CD Delft Netherlands VORtech BV NL-2628 CD Delft Netherlands Ctr Math & Comp Sci NL-1090 GB Amsterdam Netherlands

This paper presents a full multigrid (FMG) technique, which combines a multigrid method, an active set algorithm and a nested iteration technique, to solve a linear complementarity problem (LCP) modeling elastic normal contact problems. The governing system in this LCP is derived from a Fredholm integral of the first kind, and its coefficient matrix is dense, symmetric and positive definite. One multigrid cycle is applied to solve this system approximately in each active set iteration. Moreover, this multigrid solver incorporates a special strategy to handle the complementarity conditions, including restricting both the defect and the contact area (active set) to the coarse grid, and setting all quantities outside contact to zero. The smoother is chosen by some analysis based on the eigenvectors of the iteration matrix. This method is applied to a Hertzian smooth contact and a rough surface contact problem.

关键词： full multigrid linear complementarity problems integral equation normal contact problems active set algorithm

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Stochastic numerical treatment for solving Troesch's problem

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INFORMATION SCIENCES 2014年 279卷 860-873页

作者： Raja, Muhammad Asif Zahoor COMSATS Inst Informat Technol Dept Elect Engn Attock Pakistan Int Islamic Univ Fac Engn & Technol Dept Elect Engn Islamabad Pakistan

In this article, the numerical techniques are presented for the solution of Troesch's problem based on neural networks optimized with three different methods including particle swarm optimization (PSO), active set (AS) and PSO hybridized with AS (PSO-AS) algorithms. The variable transformation is applied in order to convert the original problem to a transformed problem which is relatively less stiff to solve. Feed-forward artificial neural networks are used to model the transformed problem. Learning of adjustable parameters is made with PSO, AS and PSO-AS algorithms. The proposed methodologies are applied to a number of cases for stiff and non-stiff boundary value problems. The comparative analyses are carried out with other standard numerical solutions, as well as approximate analytical solver. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Troesch's problem Non-linear ODE Artificial neural network Particle swarm optimization algorithm active set algorithm Hybrid technique

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Maximum-likelihood estimation of a log-concave density based on censored data

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ELECTRONIC JOURNAL OF STATISTICS 2014年第1期8卷 1405-1437页

作者： Duembgen, Lutz Rufibach, Kaspar Univ Bern Inst Math Stat & Actuarial Sci CH-3012 Bern Switzerland F Hoffmann La Roche & Cie AG Biostat Oncol CH-4070 Basel Switzerland

We consider nonparametric maximum-likelihood estimation of a log-concave density in case of interval-censored, right-censored and binned data. We allow for the possibility of a subprobability density with an additional mass at +infinity, which is estimated simultaneously. The existence of the estimator is proved under mild conditions and various theoretical aspects are given, such as certain shape and consistency properties. An EM algorithm is proposed for the approximate computation of the estimator and its performance is illustrated in two examples.

关键词： active set algorithm binning cure parameter expectation-maximization algorithm interval-censoring qualitative constraints right-censoring

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