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Parallel Sparse Approximate Inverse Preconditioning on Graphic Processing Units

IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2013年第9期24卷 1852-1862页

作者： Dehnavi, Maryam Mehri Fernandez, David M. Gaudiot, Jean-Luc Giannacopoulos, Dennis D. MIT Cambridge MA 02139 USA McGill Univ Montreal PQ H3A 0E9 Canada Univ Calif Irvine Dept Elect Engn & Comp Sci Irvine CA 92697 USA

Accelerating numerical algorithms for solving sparse linear systems on parallel architectures has attracted the attention of many researchers due to their applicability to many engineering and scientific problems. The solution of sparse systems often dominates the overall execution time of such problems and is mainly solved by iterative methods. Preconditioners are used to accelerate the convergence rate of these solvers and reduce the total execution time. Sparse approximate inverse (SAI) preconditioners are a popular class of preconditioners designed to improve the condition number of large sparse matrices. We propose a GPU accelerated SAI preconditioning technique called GSAI, which parallelizes the computation of this preconditioner on NVIDIA graphic cards. The preconditioner is then used to enhance the convergence rate of the BiConjugate Gradient Stabilized (BiCGStab) iterative solver on the GPU. The SAI preconditioner is generated on average 28 and 23 times faster on the NVIDIA GTX480 and TESLA M2070 graphic cards, respectively, compared to ParaSails (a popular implementation of SAI preconditioners on CPU) single processor/core results. The proposed GSAI technique computes the SAI preconditioner in approximately the same time as ParaSails generates the same preconditioner on 16 AMD Opteron 252 processors.

关键词： numerical algorithms parallel algorithms graphics processors parallel programming conditioning

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Unified Method for Field-of-View-Limited Homing Guidance

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2022年第8期45卷 1415-1434页

作者： Dong, Wei Wang, Chunyan Wang, Jianan Son, Hungsun Xin, Ming Beijing Inst Technol Sch Aerosp Engn Beijing 100081 Peoples R China Ulsan Natl Inst Sci & Technol Dept Mech Engn Ulsan 44919 South Korea Univ Missouri Dept Mech & Aerosp Engn Columbia MO 65211 USA

Homing guidance requires maintaining the target lock-on condition within the seeker's field of view (FOV). This paper aims at developing a unified FOV-limited guidance framework from which a variety of two-dimensional (2D) and three-dimensional (3D) guidance laws can be derived. First, the unified method for 2D homing guidance is established by augmenting an arbitrary baseline guidance law with a biased command. To mitigate the effect on the baseline guidance law, this biased command is designed in the admissible range that respects the FOV limit and only takes effect when the lead angle approaches the FOV bound. For more practical relevance, the autopilot dynamic of any order is further considered explicitly in the design with a recursive approach. Then, the unified method for 3D homing guidance with coupling nonlinearity is developed by exploiting the geometric relation among space angles. Unlike existing similar results, the proposed design requires neither switch logic nor numerical algorithms, which allows for continuous guidance command and convenient implementation. With the proposed method, various illustrative guidance laws are derived to demonstrate the significance of the unified framework. Finally, numerical simulations with comparative study are conducted to support the analytical findings and show the superiority of the proposed method.

关键词： Homing Guidance Control Guidance Autopilot numerical Simulation numerical algorithms Rudder Flight Path Angle Optimal Control State Dependent Riccati Equation Terminal Sliding Mode

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A dislocation-based model for deformation and size effect in multi-phase steels

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INTERNATIONAL JOURNAL OF PLASTICITY 2015年 72卷 44-59页

作者： Lyu, Hao Ruimi, Annie Zbib, Hussein M. Washington State Univ Sch Mech & Mat Engn Pullman WA 99164 USA Texas A&M Univ Dept Mech Engn Doha Qatar

In this work, we investigate the mechanical behavior of multi-phase steels using a continuum dislocation dynamic model (CDD) coupled with a viscoplastic self-consistent (VPSC) model that accounts for both the effect of dislocations evolution inside the grain as well as grain grain interactions. Because the conventional viscoplasticity theory does not capture the grain size effect, we introduce an intrinsic length scale within the concepts of geometrically necessary dislocations (GND) by means of the Nye's dislocation tensor. The effect of the GND density is implemented into the model for the mean free path of dislocations and is shown to contribute to strain hardening. As a validation of this multiscale model, we investigate the mechanical behavior of various dual phase steels. The stress-strain response obtained from this approach is compared to experimental data found in the literature and reveal good agreement between experimental results and predictions. The model also predicts the evolution of dislocation densities in each phase and suggests the connection between underlying deformation mechanisms and macroscopic material hardening. The relation between flow stress and grain size is also investigated. The model predictions follow the Hall Fetch relation of strength versus grain size for grains larger than one micron meter but deviates from this relation for grains in the order of tens of nanometers. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Multiscale modeling Dislocations viscoplastic material Crystal plasticity numerical algorithms

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Vibration mode localization in two-dimensional systems

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AIAA JOURNAL 1997年第10期35卷 1653-1659页

作者： Xie, WC Wang, X University of Waterloo Waterloo Ontario N2L 3G1 Canada

The method of regular perturbation is applied to study vibration mode localization in randomly disordered weakly coupled two-dimensional cantilever-spring arrays. Localization factors, which characterize the average exponential rates of decay or growth of the amplitudes of vibration, are defined in terms of the angles of orientation. First-order approximate results of the localization factor are obtained using a combined analytical-numerical approach. The localization factors are symmetric about the cantilever and the horizontal and vertical axes passing through the cantilever at which vibration is originated. For the systems under consideration, the direction in which vibration is originated corresponds to the smallest localization factor;whereas the diagonal directions correspond to the largest rate of decay or growth of the amplitudes of vibration. When plotted in the logarithmic scale, the vibration modes are of a hill shape with the amplitudes of vibration decaying linearly away from the cantilever at which vibration is originated.

关键词： Cantilever Bending Stiffness Structural Dynamics Linear Vibrations Green's Function numerical algorithms Computer Memory Kinetic Energy

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Experimental and Visco-Plastic Self-Consistent evaluation of forming limit diagrams for anisotropic sheet metals: An efficient and robust implementation of the M-K model

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INTERNATIONAL JOURNAL OF PLASTICITY 2015年 73卷 62-99页

作者： Schwindt, C. Schlosser, F. Bertinetti, M. A. Stout, M. Signorelli, J. W. UNS CONICET Dept Engn Buenos Aires DF Argentina IFIR UNR CONICET Rosario Santa Fe Argentina

In the present work, an efficient formulation for the prediction of forming-limit diagrams (FLDs) based on the well-known Marciniak and Kuczynski (M-K) theory using a Visco-Plastic Self-Consistent (VPSC) crystal-plasticity model has been detailed. The present model extends the previous MK-VPSC implementation (Signorelli et al., Predictions of forming limit diagrams using a rate-dependent polycrystal self-consistent plasticity model, International Journal of Plasticity 25 (2009) 1-25) based on the Newton Raphson (N-R) method, which gives no guarantee of a robust iterative procedure. In order to avoid convergence problems and to reduce the computational cost of the coupled MK-VPSC scheme, a direct approach (DA) is proposed. The DA eliminates the need of the Jacobian evaluation associated with the N-R method as well as the iterative procedure tied to other possible minimization techniques. Moreover, the mechanical states outside and inside the groove are solved in the sample reference frame, avoiding the need to rotate the crystallographic orientations and the internal variables to the current band reference frame at each increment. In this way, only two calls to the material law are required per M-K increment, obtaining a more robust numerical procedure with a significant computational cost reduction. Interestingly, the requirement of more complex boundary conditions does not substantially increase the number of internal VPSC iterations to achieve a given tolerance. Simulation results show that the direct MK-VPSC approach is consistent with that based on the N-R method. The generalized boundary conditions in the polycrystal model allowed us to calculate either strain-rate ratio or stress ratio based FLDs. The effect of using either strain-rate ratio or stress ratio paths on the FLDs has been investigated by imposing three types of pre-straining on the sheet metals. Formability predictions for a randomly-textured FCC material and for textured FCC, BCC and HCP polycryst

关键词： Ductility Polycrystalline material Viscoplastic material numerical algorithms Forming limit

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Anisotropic and asymmetrical yielding and its distorted evolution: Modeling and applications

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INTERNATIONAL JOURNAL OF PLASTICITY 2016年 82卷 127-158页

作者： Li, H. Hu, X. Yang, H. Li, L. Northwestern Polytech Univ State Key Lab Solidificat Proc Sch Mat Sci & Engn Xian 710072 Peoples R China Res Inst Baosteel Automobile Steel Res Inst Shanghai 201900 Peoples R China

Characterizing the anisotropy/asymmetry-induced distortional yielding and subsequent evolution is still a challenge for potential usages of hard-to-deform materials. From perspective of multiple mechanisms, two types of yield functions are classified, viz., the principal shear stress-based models (SSM) and the stress invariants-based models (SIM);then a unified continuum-based discontinuous (CBD) framework is constructed, in which SSM and SIM are introduced to capture the distorted shape of the yielding, and an interpolation approach is adopted to smoothly present the nonlinear evolution of the distorted plasticity in the full stress space. Taking the CPB06 (Cazacu et al., 2006) and Yoon's criteria (Yoon et al., 2014) as typical SSM and SIM, the CBD framework is implemented in the explicit 3D-FE platform for practical usages by combining implicit algorithm and interpolation approach, and the Nelder-Mead (N-M) method and the genetic algorithm (GA) approach are evaluated for calibrating of CBD related to convergence, overlapping and accuracy. The evaluation proves that the GA-based method is suitable for CBD, and the SIM seems to be feasible for embedding into the CBD framework because of its solid physical basis and numerical robustness. Taking high strength titanium alloy tube (HSTC) as a case, the distorted plasticity evolution of the HSTT with six typical initial textures are characterized, then the correlations among initial textures, distorted behaviors and inhomogeneous deformation are quantitatively established to improve the multi-defect constrained formability in uniaxial tension/compression and mandrel bending. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Yield condition Anisotropic material Constitutive behaviour Finite elements numerical algorithms

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Ontology-Enabled Generation of Simulation Software for a Complex Dynamic System

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JOURNAL OF AEROSPACE INFORMATION SYSTEMS 2018年第7期15卷 462-470页

作者： Sankari, S. S. Uma Kumar, P. Sreenivasa Geethaikrishnan, C. Indian Inst Technol Madras Dept Comp Sci & Engn Artificial Intelligence & Database Res Lab Chennai 600036 Tamil Nadu India Indian Space Res Org Vikram Sarabhai Space Ctr Qual Assurance Mission Div Thiruvananthapuram 695022 Kerala India

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A generic anisotropic continuum damage model integration scheme adaptable to both ductile damage and biological damage-like situations

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INTERNATIONAL JOURNAL OF PLASTICITY 2015年 66卷 46-70页

作者： Mengoni, M. Ponthot, J. P. Univ Liege ULg Dept Aerosp & Mech Engn Nonlinear Computat Mech MN2L Liege Belgium

This paper aims at presenting a general versatile time integration scheme applicable to anisotropic damage coupled to elastoplasticity, considering any damage rate and isotropic hardening formulations. For this purpose a staggered time integration scheme in a finite strain framework is presented, together with an analytical consistent tangent operator. The only restrictive hypothesis is to work with an undamaged isotropic material, assumed here to follow a J(2) plasticity model. The only anisotropy considered is thus a damage-induced anisotropy. The possibility to couple any damage rate law with the present algorithm is illustrated with a classical ductile damage model for aluminium, and a biological damage-like application. The later proposes an original bone remodelling law coupled to trabecular bone plasticity for the simulation of orthodontic tooth movements. All the developments have been considered in the framework of the implicit non-linear finite element code Metafor (developed at the LTAS/(MNL)-L-2, University of Liege, Belgium - ***). (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Continuum damage mechanics Anisotropic material Elastic-plastic material Constitutive behaviour numerical algorithms

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Computation of general inner-outer and spectral factorizations

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 2000年第12期45卷 2307-2325页

作者： Oara, C Varga, A Univ Politech Fac Automat Control & Comp Bucharest Romania German Aerosp Ctr Inst Robot & Mechatron D-82234 Wessling Germany

In this paper, we solve two problems in linear systems theory: the computation of the inner-outer and spectral factorizations of a continuous-time system considered in the most general setting We show that these factorization problems rely essentially on solving for the stabilizing solution a standard algebraic Riccati equation of order usually much smaller than the McMillan degree of the transfer function matrix of the system, The proposed procedures are completely general, being applicable for a polynomial/proper/improper system whose transfer function matrix could be rank deficient and could have poles/zeros on the imaginary axis or at infinity. As an application we discuss the extension to the case of rational matrices of the complete orthogonal decomposition of a constant matrix. numerical refinements and examples illustrating the proposed approach, are discussed in detail.

关键词： descriptor systems inner-outer factorization matrix pencils numerical algorithms rational matrices spectral factorization system zeros

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DESIGNING REDUCED-ORDER LINEAR-MULTIVARIABLE CONTROLLERS USING EXPERIMENTALLY DERIVED PLANT-DATA

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1993年第1期16卷 53-58页

作者： FRAZIER, WG IRWIN, RD Ohio University Athens Ohio 45701

An iterative numerical algorithm for simultaneously improving multiple performance and stability robustness criteria for multivariable feedback systems is developed. The unsatisfied design criteria are improved by updating the free parameters of an initial, stabilizing controller's state-space matrices. Analytical expressions for the gradients of the design criteria are employed to determine a parameter correction that improves all of the feasible, unsatisfied design criteria al each iteration. A controller design is performed using the algorithm with experimentally derived data from a large space structure test facility. Experimental results of the controller's performance at the facility are presented.

关键词： Large Space Structures numerical algorithms Open Loop Controller Linear Quadratic Gaussian Mathematical Models Control System Design Algorithm Performance Frequency Domain NASA Marshall Space Flight Center Search Algorithm

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