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Parallel Version (parallel + version)
Selected AbstractsMRMOGA: a new parallel multi-objective evolutionary algorithm based on the use of multiple resolutionsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 4 2007Antonio López Jaimes Abstract In this paper, we introduce MRMOGA (Multiple Resolution Multi-Objective Genetic Algorithm), a new parallel multi-objective evolutionary algorithm which is based on an injection island approach. This approach is characterized by adopting an encoding of solutions which uses a different resolution for each island. This approach allows us to divide the decision variable space into well-defined overlapped regions to achieve an efficient use of multiple processors. Also, this approach guarantees that the processors only generate solutions within their assigned region. In order to assess the performance of our proposed approach, we compare it to a parallel version of an algorithm that is representative of the state-of-the-art in the area, using standard test functions and performance measures reported in the specialized literature. Our results indicate that our proposed approach is a viable alternative to solve multi-objective optimization problems in parallel, particularly when dealing with large search spaces. Copyright © 2006 John Wiley & Sons, Ltd. [source] Parallel protein folding with STAPLCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 14 2005Shawna Thomas Abstract The protein-folding problem is a study of how a protein dynamically folds to its so-called native state,an energetically stable, three-dimensional conformation. Understanding this process is of great practical importance since some devastating diseases such as Alzheimer's and bovine spongiform encephalopathy (Mad Cow) are associated with the misfolding of proteins. We have developed a new computational technique for studying protein folding that is based on probabilistic roadmap methods for motion planning. Our technique yields an approximate map of a protein's potential energy landscape that contains thousands of feasible folding pathways. We have validated our method against known experimental results. Other simulation techniques, such as molecular dynamics or Monte Carlo methods, require many orders of magnitude more time to produce a single, partial trajectory. In this paper we report on our experiences parallelizing our method using STAPL (Standard Template Adaptive Parallel Library) that is being developed in the Parasol Lab at Texas A&M. An efficient parallel version will enable us to study larger proteins with increased accuracy. We demonstrate how STAPL enables portable efficiency across multiple platforms, ranging from small Linux clusters to massively parallel machines such as IBM's BlueGene/L, without user code modification. Copyright © 2005 John Wiley & Sons, Ltd. [source] Parallel computation of arbitrarily shaped waveguide modes using BI-RME and Lanczos methodsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 4 2007A. M. Vidal Abstract This paper is devoted to the parallelization of a new method for solving large, structured eigenvalue problems, which appear in the electromagnetic modal analysis of arbitrarily shaped waveguides, typically present in many modern passive devices. This new method, based on the boundary integral-resonant mode expansion (BI-RME) technique and in the Lanczos method (for solution of the eigenvalue problem), was recently proposed by the authors, showing important advantages in terms of CPU time and memory over previously used solutions. As it will be fully described in this paper, the parallel version of such a new method allows further important savings in the overall CPU computation time. Comparative benchmarks and scalability issues related to the implemented parallel algorithm are discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Parallel simulation of unsteady hovering rotor wakesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2006C. B. Allen Abstract Numerical simulation using low diffusion schemes, for example free-vortex or vorticity transport methods, and theoretical stability analyses have shown the wakes of rotors in hover to be unsteady. This has also been observed in experiments, although the instabilities are not always repeatable. Hovering rotor wake stability is considered here using a finite-volume compressible CFD code. An implicit unsteady, multiblock, multigrid, upwind solver, and structured multiblock grid generator are presented, and applied to lifting rotors in hover. To allow the use of very fine meshes and, hence, better representation of the flow physics, a parallel version of the code has been developed, and parallel performance using upto 1024 CPUs is presented. A four-bladed rotor is considered, and it is demonstrated that once the grid density is sufficient to capture enough turns of the tip vortices, hover exhibits oscillatory behaviour of the wake, even using a steady formulation. An unsteady simulation is then performed, and also shows an unsteady wake. Detailed analysis of the time-accurate wake history shows that three dominant unsteady modes are captured, for this four-bladed case, with frequencies of one, four, and eight times the rotational frequency. A comparison with theoretical stability analysis is also presented. Copyright © 2006 John Wiley & Sons, Ltd. [source] Parallel solution of lifting rotors in hover and forward flightINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 1 2007C. B. Allen Abstract An implicit unsteady, multiblock, multigrid, upwind solver including mesh deformation capability, and structured multiblock grid generator, are presented and applied to lifting rotors in both hover and forward flight. To allow the use of very fine meshes and, hence, better representation of the flow physics, a parallel version of the code has been developed. It is demonstrated that once the grid density is sufficient to capture enough turns of the tip vortices, hover exhibits oscillatory behaviour of the wake, even using a steady formulation. An unsteady simulation is then presented, and detailed analysis of the time-accurate wake history is performed and compared to theoretical predictions. Forward flight simulations are also presented and, again, grid density effects on the wake formation investigated. Parallel performance of the code using up to 1024 CPU's is also presented. Copyright © 2006 John Wiley & Sons, Ltd. [source] Parallelization of the quantum dynamics code for cluster architecture and its applications to the Gross,Pitaevskii equationINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2006Adam Gorecki Abstract We present a parallel version of a quantum dynamics (QD) algorithm in a wave function representation. The algorithm has been optimized for a Linux cluster as well as for Cray T3E, using a parallel version of a three-dimensional FFT library. We have applied this algorithm for solving the nonlinear Gross,Pitaevskii equation (GPE), which describes the evolution of Bose,Einstein condensates (BEC) in the mean field approximation. Our method reduces the computational time and allows the study of nonlinear quantum systems. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Two-Step Testing in Employee Selection: Is score inflation a problem?INTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 2 2008Christopher D. Nye Unproctored Internet testing in employee selection has become increasingly popular over the past few years. However, there is a concern that cheating during unproctored administrations may influence the test results in terms of score inflation. The current research attempts to determine the extent of cheating on an unproctored Internet test of perceptual speed by analyzing data from a parallel version of the test administered in a proctored setting. Among a sample of 856 job applicants from nine European countries, there was no evidence that cheating occurred. In fact, evidence of an effect operating in the opposite direction was obtained. These results indicate that the use of unproctored Internet testing is appropriate for this type of test. [source] Parallel Algorithms for Dynamic Shortest Path ProblemsINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 3 2002Ismail Chabini The development of intelligent transportation systems (ITS) and the resulting need for the solution of a variety of dynamic traffic network models and management problems require faster-than-real-time computation of shortest path problems in dynamic networks. Recently, a sequential algorithm was developed to compute shortest paths in discrete time dynamic networks from all nodes and all departure times to one destination node. The algorithm is known as algorithm DOT and has an optimal worst-case running-time complexity. This implies that no algorithm with a better worst-case computational complexity can be discovered. Consequently, in order to derive algorithms to solve all-to-one shortest path problems in dynamic networks, one would need to explore avenues other than the design of sequential solution algorithms only. The use of commercially-available high-performance computing platforms to develop parallel implementations of sequential algorithms is an example of such avenue. This paper reports on the design, implementation, and computational testing of parallel dynamic shortest path algorithms. We develop two shared-memory and two message-passing dynamic shortest path algorithm implementations, which are derived from algorithm DOT using the following parallelization strategies: decomposition by destination and decomposition by transportation network topology. The algorithms are coded using two types of parallel computing environments: a message-passing environment based on the parallel virtual machine (PVM) library and a multi-threading environment based on the SUN Microsystems Multi-Threads (MT) library. We also develop a time-based parallel version of algorithm DOT for the case of minimum time paths in FIFO networks, and a theoretical parallelization of algorithm DOT on an ,ideal' theoretical parallel machine. Performances of the implementations are analyzed and evaluated using large transportation networks, and two types of parallel computing platforms: a distributed network of Unix workstations and a SUN shared-memory machine containing eight processors. Satisfactory speed-ups in the running time of sequential algorithms are achieved, in particular for shared-memory machines. Numerical results indicate that shared-memory computers constitute the most appropriate type of parallel computing platforms for the computation of dynamic shortest paths for real-time ITS applications. [source] Parallel deconvolution of large 3D images obtained by confocal laser scanning microscopyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2010Piotr Pawliczek Abstract Various deconvolution algorithms are often used for restoration of digital images. Image deconvolution is especially needed for the correction of three-dimensional images obtained by confocal laser scanning microscopy. Such images suffer from distortions, particularly in the Z dimension. As a result, reliable automatic segmentation of these images may be difficult or even impossible. Effective deconvolution algorithms are memory-intensive and time-consuming. In this work, we propose a parallel version of the well-known Richardson,Lucy deconvolution algorithm developed for a system with distributed memory and implemented with the use of Message Passing Interface (MPI). It enables significantly more rapid deconvolution of two-dimensional and three-dimensional images by efficiently splitting the computation across multiple computers. The implementation of this algorithm can be used on professional clusters provided by computing centers as well as on simple networks of ordinary PC machines. Microsc. Res. Tech., 2010. © 2009 Wiley-Liss, Inc. [source] Predicting reading and spelling difficulties in transparent and opaque orthographies: a comparison between Scandinavian and US/Australian childrenDYSLEXIA, Issue 2 2010Bjarte Furnes Abstract In this study, predictors of reading and spelling difficulties among children learning more transparent (Norwegian/Swedish) and less transparent (English) orthographies were examined longitudinally from preschool through Grade 2 using parallel versions of tests. A series of logistic regression analysis indicated three main findings. First, phonological awareness as a predictor of reading difficulties in the Scandinavian sample was time-limited to Grade 1, but remained as a significant predictor in the English-speaking sample. Second, phonological awareness predicted spelling difficulties similarly across orthographies. Third, preschool and kindergarten RAN was a significant predictor of reading and spelling difficulties at both Grades 1 and 2 across orthographies. The authors conclude that phonological awareness diminishes as a predictor of reading difficulties in transparent orthographies after the first years of schooling, that RAN is a better long-term predictor of reading difficulties, and that phonological awareness is associated with spelling difficulties similarly in transparent and opaque orthographies. Copyright © 2010 John Wiley & Sons, Ltd. [source] What the eyes already ,know': using eye movement measurement to tap into children's implicit numerical magnitude representationsINFANT AND CHILD DEVELOPMENT, Issue 2 2010Angela Heine Abstract To date, a number of studies have demonstrated the existence of mismatches between children's implicit and explicit knowledge at certain points in development that become manifest by their gestures and gaze orientation in different problem solving contexts. Stimulated by this research, we used eye movement measurement to investigate the development of basic knowledge about numerical magnitude in primary school children. Sixty-six children from grades one to three (i.e. 6,9 years) were presented with two parallel versions of a number line estimation task of which one was restricted to behavioural measures, whereas the other included the recording of eye movement data. The results of the eye movement experiment indicate a quantitative increase as well as a qualitative change in children's implicit knowledge about numerical magnitudes in this age group that precedes the overt, that is, behavioural, demonstration of explicit numerical knowledge. The finding that children's eye movements reveal substantially more about the presence of implicit precursors of later explicit knowledge in the numerical domain than classical approaches suggests further exploration of eye movement measurement as a potential early assessment tool of individual achievement levels in numerical processing. Copyright © 2009 John Wiley & Sons, Ltd. [source] The Mediating Role of Feedback Acceptance in the Relationship between Feedback and Attitudinal and Performance OutcomesINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 4 2009Frederik Anseel The purpose of this study was to increase our understanding of applicant perceptions of feedback by drawing upon feedback process models. In Study 1, participants (N=125) completed a personality questionnaire as a first stage of a selection simulation. Results showed that the effect of feedback on attitudes toward the organization was mediated by feedback acceptance. In Study 2, participants (N=252) completed two parallel versions of an in-basket exercise and received informative feedback between the two versions. Results showed that the effect of feedback on subsequent test performance was partially mediated by feedback acceptance. Together, these results highlight the important role of feedback acceptance in selection and suggest new strategies to enhance applicant perceptions in selection. [source] A parallel hybrid local search algorithm for the container loading problemINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 5 2004D. Mack Abstract In this contribution, a parallel hybrid local search algorithm for the three-dimensional container loading problem (CLP) is proposed. First a simulated annealing method for the CLP is developed, which is then combined with an existing tabu search algorithm to form a hybrid metaheuristic. Finally, parallel versions are introduced for these algorithms. The emphasis is on CLP instances with a weakly heterogeneous load. Numerical tests based on the well-known 700 test instances from Bischoff and Ratcliff are performed, and the outcome is compared with methods from other authors. The results show a high solution quality obtained with reasonable computing time. [source] A parallel block overlap preconditioning with inexact submatrix inversion for linear elasticity problemsNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 2 2002Igor E. Kaporin We present a parallel preconditioned iterative solver for large sparse symmetric positive definite linear systems. The preconditioner is constructed as a proper combination of advanced preconditioning strategies. It can be formally seen as being of domain decomposition type with algebraically constructed overlap. Similar to the classical domain decomposition technique, inexact subdomain solvers are used, based on incomplete Cholesky factorization. The proper preconditioner is shown to be near optimal in minimizing the so-called K -condition number of the preconditioned matrix. The efficiency of both serial and parallel versions of the solution method is illustrated on a set of benchmark problems in linear elasticity. Copyright © 2002 John Wiley & Sons, Ltd. [source] On the swapping algorithmRANDOM STRUCTURES AND ALGORITHMS, Issue 1 2003Neal Madras Abstract The Metropolis-coupled Markov chain method (or "Swapping Algorithm") is an empirically successful hybrid Monte Carlo algorithm. It alternates between standard transitions on parallel versions of the system at different parameter values, and swapping two versions. We prove rapid mixing for two bimodal examples, including the mean-field Ising model. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 22: 66,97, 2002 [source] Development and psychometric evaluation of an Arab version of the family peer relationship questionnaire,RESEARCH IN NURSING & HEALTH, Issue 5 2008Karen J. Aroian Abstract Little is known about parent and peer relationships in immigrant adolescents due to a dearth of culturally sensitive measures. We adapted the Family Peer Relationship Questionnaire (FPRQ) for Arab immigrant mothers and their adolescents. Mothers and adolescents completed parallel versions of the Arab FPRQ and measures of child behavior problems, child social relations, and maternal depression. Data analyses included confirmatory factor analysis and concurrent validity. The proposed four-factor structure was replicated in both the mother and child forms. Scores from the Arab FPRQ subscales and the other measures provided evidence of concurrent and discriminant validity, suggesting that the Arab FPRQ is a viable assessment tool. © 2008 Wiley Periodicals, Inc. Res Nurs Health 31:402,416, 2008 [source] | ||||||||||||||||||||||