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42nd Annual IEEE/IFIP International conference on Dependable Systems and Networks (DSN)

作者： Sloan, Joseph Kumar, Rakesh Bronevetsky, Greg Univ Illinois Urbana IL 61801 USA Lawrence Livermore Natl Lab Livermore CA USA

ISBN: (纸本)9781467316255

The increasing size and complexity of High-Performance Computing systems is making it increasingly likely that individual circuits will produce erroneous results, especially when operated in a low energy mode. Previous techniques for Algorithm - Based Fault Tolerance (ABFT) [20] have been proposed for detecting errors in dense linear operations, but have high overhead in the context of sparse problems. In this paper, we propose a set of algorithmic techniques that minimize the overhead of fault detection for sparse problems. The techniques are based on two insights. First, many sparse problems are well structured (e.g. diagonal, banded diagonal, block diagonal), which allows for sampling techniques to produce good approximations of the checks used for fault detection. These approximate checks may be acceptable for many sparse linear algebra applications. Second, many linear applications have enough reuse that preconditioning techniques can be used to make these applications more amenable to low-cost algorithmic checks. The proposed techniques are shown to yield up to 2x reductions in performance overhead over traditional ABFT checks for a spectrum of sparse problems. A case study using common linear solvers further illustrates the benefits of the proposed algorithmic techniques.

关键词： ABFT sparse linear algebra numerical methods error detection

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Comparison of statistical and optimisation-based methods for data-driven network reconstruction of biochemical systems

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IET SYSTEMS BIOLOGY 2012年第5期6卷 155-U53页

作者： Asadi, B. Maurya, M. R. Tartakovsky, D. M. Subramaniam, S. Univ Calif San Diego Dept Mech & Aerosp Engn La Jolla CA 92093 USA Univ Calif San Diego Dept Bioengn La Jolla CA 92093 USA Univ Calif San Diego Grad Program Bioinformat La Jolla CA 92093 USA Univ Calif San Diego Dept Chem & Biochem Cellular & Mol Med La Jolla CA 92093 USA

Data-driven reconstruction of biological networks is a crucial step towards making sense of large volumes of biological data. Although several methods have been developed recently to reconstruct biological networks, there are few systematic and comprehensive studies that compare different methods in terms of their ability to handle incomplete datasets, high data dimensions and noisy data. The authors use experimentally measured and synthetic datasets to compare three popular methods - principal component regression (PCR), linear matrix inequalities (LMI) and least absolute shrinkage and selection operator (LASSO) - in terms of root-mean-squared error (RMSE), average fractional error in the value of the coefficients, accuracy, sensitivity, specificity and the geometric mean of sensitivity and specificity. This comparison enables the authors to establish criteria for selection of an appropriate approach for network reconstruction based on a priori properties of experimental data. For instance, although PCR is the fastest method, LASSO and LMI perform better in terms of accuracy, sensitivity and specificity. Both PCR and LASSO are better than LMI in terms of fractional error in the values of the computed coefficients. Trade-offs such as these suggest that more than one aspect of each method needs to be taken into account when designing strategies for network reconstruction.

关键词： LASSO coefficient accuracy value data-driven network reconstruction design strategies root-mean-squared error Biology and medical computing Systems theory applications in biology and medicine biochemical systems network theory (graphs) biological network data linear algebra (numerical analysis) Optimisation techniques LMI principal component analysis principal component regression regression analysis optimisation sensitivity geometric mean optimisation-based methods specificity geometric mean Combinatorial mathematics statistical-based methods linear matrix inequalities biochemistry mean square error methods PCR average fractional error geometry Interpolation and function approximation (numerical analysis) RMSE mathematical operators least absolute shrinkage-and-selection operator Other topics in statistics

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A Restarted Iterative Homotopy Analysis Method for Three-dimensional Image Segmentation

A Restarted Iterative Homotopy Analysis Method for Three-dim...

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3rd International conference on Image Processing theory, Tools and applications (IPTA)

作者： Rada, Lavdie Chen, Ke Ghanbari, Behzad Univ Liverpool Ctr Math Imaging Tech Liverpool L69 7ZL Merseyside England

ISBN: (纸本)9781467325851;9781467325837

Total variational segmentation models provide effective tools for identifying all features and their boundaries in two and three dimensional images and have been proven to be useful and successful. Speeding up a simulation is one of the remaining challenges. In this paper we propose a restarted homotopy analysis method to improve the computational efficiency in three-dimensional image segmentation. T he algorithm replaces the nonlinear variational problem by a sequence of linear approximations by working with linear equations instead of nonlinear ones which lead to efficient energy minimization while maintaining the segmentation quality. Experimental results will show that the computational efficiency is significantly improved.

关键词： approximation theory image reconstruction image segmentation iterative methods linear algebra

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A Connectivity-preserving flocking algorithm for multi-agent dynamical systems with bounded potential function

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IET CONTROL theory AND applications 2012年第6期6卷 813-821页

作者： Wen, G. Duan, Z. Su, H. Chen, G. Yu, W. Peking Univ Coll Engn State Key Lab Turbulence & Complex Syst Beijing 100871 Peoples R China Huazhong Univ Sci & Technol Dept Control Sci & Engn Wuhan 430074 Peoples R China City Univ Hong Kong Dept Elect Engn Hong Kong Hong Kong Peoples R China Southeast Univ Dept Math Nanjing 210096 Jiangsu Peoples R China

Without assuming that the communication topology can remain its connectivity frequently enough and the potential function can provide an infinite force during the evolution of agents, the flocking problem of multi-agent systems with second-order non-linear dynamics is investigated in this study. By combining the ideas of collective potential functions and velocity consensus, a connectivity-preserving flocking algorithm with bounded potential function is proposed. Using tools from the algebraic graph theory and matrix analysis, it is proved that the designed algorithm can guarantee the group of multiple agents to asymptotically move with the same velocity while preserving the network connectivity if the coupling strength of the velocity consensus term is larger than a threshold value. Furthermore, the flocking algorithm is extended to solve the flocking problem of multi-agent systems with a dynamical virtual leader by adding a navigation feedback term. In this case, each informed agent only has partial velocity information about the leader, yet the present algorithm not only can guarantee the velocity of the whole group to track that of the leader asymptotically, and also can preserve the network connectivity. Finally, some numerical simulations are provided to illustrate the theoretical results.

关键词： Spatial variables control dynamical virtual leader infinite force numerical simulations network connectivity multi-agent systems velocity consensus term algebraic graph theory Combinatorial mathematics partial velocity information Stability in control theory Nonlinear control systems numerical analysis path planning matrix algebra multi-robot systems asymptotic stability connectivity-preserving flocking algorithm graph theory feedback algebra communication topology bounded potential function network theory (graphs) nonlinear dynamical systems matrix analysis Other numerical methods navigation feedback term second-order nonlinear dynamics multiagent dynamical systems Expert systems and other AI software and techniques asymptotic leader tracking Mobile robots collective potential functions coupling strength

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Chaotic Optimization Method without Initial Sampling Parameter Tuning - Empirical Comparisons of Two Approaches in Various Problems

Chaotic Optimization Method without Initial Sampling Paramet...

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IEEE International conference on Systems, Man, and Cybernetics

作者： Takashi Okamoto Hironori Hirata Graduate School of Engineering Chiba University Chiba Japan

ISBN: (纸本)9781479906505

The chaotic optimization method is a global optimization method to solve unconstrained optimization problems. Its superior search capability has been confirmed through applications to optimization problems which have high dimensional and multi-peaked objective functions. However, the chaotic optimization method has a drawback in that a parameter called initial sampling parameter has to be tuned on each optimization problem. In this study, we consider two approaches to perform the chaotic optimization method without the initial sampling parameter tuning. One is the initial sampling estimation method based on the characteristics of the chaotic optimization method. In this method, the sampling parameter at which the search trajectory bifurcates from the fixed point convergence to the two periodic solution trajectory, which is called the first bifurcating parameter, is computed from the approximation matrix to Hessian obtained by the quasi-Newton method. Then, suitable initial sampling parameter is estimated using this information. The other is the descent sign vector method. In this method, a descent sign vector extracted from a gradient vector is used as a search direction of a search point. Then, its moving distance is determined so that its search process shifts from the global search to the local search. We compare two methods and their hybrid method through numerical experiments for various optimization problems.

关键词： Globa Optimization Nonlinear Optimization Chaos Parameter Tuning linear Stability theory

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Fuzzy approximation-based indirect adaptive controller for multi-input multi-output non-affine systems with unknown control direction

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IET CONTROL theory AND applications 2012年第17期6卷 2619-2629页

作者： Boulkroune, A. M'Saad, M. Farza, M. Univ Jijel Dept Automat Control LAJ Ouled Aissa 18000 Jijel Algeria Univ Caen CNRS UMR 6072 GREYCENSICAEN F-14050 Caen France

A fuzzy approximation-based indirect adaptive control is investigated for a class of unknown non-affine non-linear systems with unknown control direction. An equivalent model in affine-like form is first derived for the original non-affine system by using a Taylor series expansion. Next, a fuzzy indirect adaptive control is designed based on this affine-like equivalent model. In this control scheme, the adaptive fuzzy systems are used to appropriately approximate the equivalent affine model's unknown non-linearities, whereas the Nussbaum gain function is used to deal with the unknown control directions (being closely related to the sign of control gain matrix). A decomposition property of the control gain matrix is fully exploited in the controller design and the stability analysis. It is proven that, under some appropriate assumptions, the proposed control scheme can achieve that all the signals in the closed-loop control system are bounded and the tracking errors converge to a small neighbourhood around zero. Effectiveness of the developed scheme is illustrated by two simulation examples.

关键词： fuzzy approximation-based indirect adaptive controller equivalent affine model unknown nonlinearity control nonlinearities tracking errors adaptive control affine-like form closed-loop control system Multivariable control systems affine transforms affine-like equivalent model Combinatorial mathematics multiinput multioutput nonaffine systems stability control system synthesis Stability in control theory stability analysis Control system analysis and synthesis methods Nussbaum gain function Nonlinear control systems Integral transforms adaptive fuzzy systems decomposition property Fuzzy control MIMO systems unknown nonaffine nonlinear systems closed loop systems series (mathematics) fuzzy systems matrix algebra algebra control gain matrix Self-adjusting control systems unknown control directions fuzzy indirect adaptive control design nonlinear control systems Interpolation and function approximation (numerical analysis) fuzzy control approximation theory tracking controller design Taylor series expansion

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numerical methods for the biomechanics of growing trees

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COMPUTERS & MATHEMATICS WITH applications 2012年第3期64卷 289-309页

作者： Guillon, Thomas Dumont, Yves Fourcaud, Thierry CIRAD UMR AMAP F-34398 Montpellier 5 France Univ Montpellier 2 UMR AMAP F-34398 Montpellier 5 France

Modelling the biomechanics of growing trees is a non-classical problem, as the usual framework of structural mechanics does not take into account the evolution of the domain geometry due to growth processes. Incremental approaches have been used in rod theory to bypass this problem and to model the addition of new material points on an existing deformed structure. However, these approaches are based on the explicit time numerical algorithm of an unknown continuous model, and thus, the accuracy of the numerical results obtained cannot be analysed. A new continuous space-time formulation has been recently proposed to model the biomechanical response of growing rods. The aim of this paper is to discretise the corresponding non-linear system of partial differential equations and the linearised system in order to compare the numerical results with analytical solutions of the linearised problem. The finite element method is implemented to compute the space boundary problem and different time integration schemes are considered to solve the associated initial value problem with a special attention to the forward Euler method which is the analogue of the previously used incremental approach. The numerical results point out that the accuracy of the time integration schemes strongly depends on the value of the parameters. The forward Euler method may present slow convergence property and errors with significant orders of magnitude. Nevertheless, attention must be paid to implicit methods since, for specific values of the parameters and large time steps, they may lead to spurious solutions that may come from numerical instabilities. Hence, the second order Heun's method is an interesting alternative even if it is more time consuming. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Plant growth model Rod theory Surface growth problem Partial differential equation Hermite finite element Time integration scheme

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Is A ∈ ℂn,n a general H-matrix?

Is A ∈ ℂn,n a general H-matrix?

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作者： Bru, Rafael Giménez, Isabel Hadjidimos, Apostolos Institut de Matemàtica Multidisciplinar Universitat Politcnica de Valéncia Valéncia Spain Department of Computer and Communication Engineering University of Thessaly GR-383 33 Volos Greece

H-matrices play an important role in the theory and applications of numerical linear algebra. So, it is very useful to know whether a given matrix A∈Cn,n, usually the coefficient of a complex linear system of algebraic equations or of a linear Complementarity Problem (A∈Rn, n, with aii>0 for i=1,2,...,n in this case), is an H-matrix;then, most of the classical iterative methods for the solution of the problem at hand converge. In recent years the set of H-matrices has been extended to what is now known as the set of General H-matrices, and a partition of this set in three different classes has been made. The main objective of this work is to develop an algorithm that will determine the H-matrix character and will identify the class to which a given matrix A∈Cn,n belongs;in addition, some results on the classes of general H-matrices and a partition of the non-H-matrix set are presented. © 2010 Elsevier Inc. All rights reserved.

关键词： Matrix algebra

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applications of Lie groups and Lie algebra to computer vision: A brief survey

Applications of Lie groups and Lie algebra to computer visio...

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2012 International conference on Systems and Informatics, ICSAI 2012

作者： Xu, Qiang Ma, Dengwu Department of Ordnance Science and Technology Naval Aeronautical and Astronautical University Yantai China

ISBN: (纸本)9781467301992

Recent years an extensive literature appears using the Lie groups theory to solve the problems of computer vision. Lie groups theory is the natural representation of a space of transformations. Lie algebra is the tangent space of Lie groups at the identity. From Lie groups to Lie algebra, we can establish a mapping from the multiplicative structure to an equivalent vector space representation, which makes correlation calculation become rational and precise. Based on the linear structure of Lie algebra, many statistical learning methods can be readily applied. This survey briefly reviews the different approaches about the use of Lie groups theory that have been developed by research;introducing the mathematical background of Lie groups theory corresponding to computer vision;describing the main approaches in details according two categories. © 2012 IEEE.

关键词： Computer vision

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Robust dynamical compensator design for discrete-time linear periodic systems

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JOURNAL OF GLOBAL OPTIMIZATION 2012年第2期52卷 291-304页

作者： Lv, Lingling Duan, Guangren Su, Haibin Harbin Inst Technol Ctr Control Theory & Guidance Technol Harbin 150001 Peoples R China

This paper considers dynamical compensators design for purpose of pole assignment for discrete-time linear periodic systems. Similar to linear time-invariant systems, it is pointed out that the design of a periodic dynamical compensator can be converted into the design of a periodic output feedback controller for an augmented system. Utilizing the recent result on output feedback pole assignment, parametric solutions for this problem are obtained. The design approach can be used as a basis for the robust dynamical compensator design for this type of systems. Combined with a robustness index presented in this paper, robust dynamical compensator design problem is converted into a constrainted optimization problem. A numerical example is employed to illustrate the validity and feasibility of the methods.

关键词： Parametric dynamical compensator Robust dynamical compensator linear discrete periodic systems Pole assignment

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