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COMPUTER SCIENCE (CN-csci)

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The main areas of interest of the journal are theoretical aspects of computer science, soft computing, HPC, cloud and distributed processing and simulation, multimedia systems and computer graphics, and natural language processing.

New!   Aktualny numer: 2025 - Vol. 26 - No. 4

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Language: EnglishSubject: search.filters.subject.parallel computing

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Now showing 1 - 8 of 8
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    A parallel approach for metaheuristics solving the labs problem using CPU and GPU
    (Wydawnictwa AGH, 2025) Żurek, Dominik; Piętak, Kamil; Pietroń, Marcin; Kisiel-Dorohinicki, Marek
    This paper contributes to solving the low autocorrelation binary sequence (LABS) problem that remains an open hard-optimization problem with many applications. The current direction of research is focused on developing algorithms dedicated to parallel architectures such as GPGPU or multi-core CPUs. The paper follows this direction and proposes new heuristics developed from the steepest-descent local search algorithm that extends the notion of a neighborhood of a given sequence. The introduced algorithms utilize the parallel nature of multicore CPUs and provide an effective method for solving the LABS problem. The efficiency levels of SDSL and the new algorithm are presented; to ensure an effective comparison, they were both implemented in the same manner. The comparison shows that exploring the larger neighborhood improves the efficiency of the search method.
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    A parallel algorithm of icsym forcomplexsymmetric linear systems in quantum chemistry
    (Wydawnictwa AGH, 2018) Zhang, Yingchun; Lv, Quanyi; Xiao, Manyu; Xie, Gongnan; Breitkopf, Piotr
    Computational effort is a common issue for solving large-scale complex symmetric linear systems, particularly in quantum chemistry applications. In order to alleviate this problem, we propose a parallel algorithm of improved conjugate gradient-type iterative (ICSYM). Using three-term recurrence relation and or- thogonal properties of residual vectors to replace the tridiagonalization process of classical CSYM, which allows to decrease the degree of the reduce-operator from two to one communication at each iteration and to reduce the amount of vector updates and vector multiplications. Several numerical examples are implemented to show that high performance of proposed improved version is obtained both in convergent rate and in parallel efficiency.
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    Dynamic tile free scheduling for code with acyclic inter-tile dependence graphs
    (Wydawnictwa AGH, 2017) Bielecki, Włodzimierz; Skotnicki, Piotr
    Free scheduling is a task ordering technique under which instructions are executed as soon as their operands become available. Coarsening the grain of computations under the free schedule, by means of using groups of loop nest statement instances (tiles) in place of single statement instances, increases the locality of data accesses and reduces the number of synchronization events, and as a consequence improves program performance. The paper presents an approach for code generation that allows for the free schedule for tiles of arbitrarily nested affine loops at run-time. The scope of the applicability of the introduced algorithms is limited to tiled loop nests whose inter-tile dependence graphs are cycle-free. The approach is based on the polyhedral model. Results of experiments with the PolyBench benchmark suite, demonstrating significant tiled code speed-up, are discussed.
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    One-dimensional fully automatic h-adaptive isogeometric finite element method package
    (Wydawnictwa AGH, 2016) Lipski, Paweł; Paszyński, Maciej
    This paper deals with an adaptive finite element method originally developed by Prof. Leszek Demkowicz for hierarchical basis functions. In this paper, we investigate the extension of the adaptive algorithm for isogeometric analysis performed with $B$-spline basis functions. We restrict ourselves to $h$-adaptivity, since the polynomial order of approximation must be fixed in the isogeometric case. The classical variant of the adaptive FEM algorithm, as delivered by the group of Prof. Demkowicz, is based on a two-grid paradigm, with coarse and fine grids (the latter utilized as a reference solution). The problem is solved independently over a coarse mesh and a fine mesh. The fine-mesh solution is then utilized as a reference to estimate the relative error of the coarse-mesh solution and to decide which elements to refine. Prof. Demkowicz uses hierarchical basis functions, which (though locally providing $C^{p−1}$ continuity) ensure only $C^0$ on the interfaces between elements. The CUDA C library described in this paper switches the basis to $B$-spline functions and proposes a one-dimensional isogeometric version of the $h$-adaptive FEM algorithm to achieve global $C^{p−1}$ continuity of the solution.
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    FPGA-based multi-core processor
    (Wydawnictwa AGH, 2013) Wójcik, Wojciech; Długopolski, Jacek
    The paper presents the results of investigations concerning the possibility of using programm able logic devices (FPGA) to build virtual multi-core processors dedicated specifically towards particular applications.The paper shows the designed architecture of a multi-core processor specialized to perform a particular task, and it discusses its computational efficiency depending on the number of cores used. An evaluation of the results is also discussed.
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    Heterogeneous GPU&CPU cluster for High Performance Computing in cryptography
    (Wydawnictwa AGH, 2012) Marks, Michał; Jantura, Jarosław; Niewiadomska-Szynkiewicz, Ewa; Strzelczyk, Przemysław; Góźdź, Krzysztof
    This paper addresses issues associated with distributed computing systems and the application of mixed GPU&CPU technology to data encryption and decryption algorithms. We describe a heterogenous cluster HGCC formed by two types of nodes: Intel processor with NVIDIA graphics processing unit and AMD processor with AMD graphics processing unit (formerly ATI), and a novel software framework that hides the heterogeneity of our cluster and provides tools for solving complex scientific and engineering problems. Finally, we present the results of numerical experiments. The considered case study is concerned with parallel implementations of selected cryptanalysis algorithms. The main goal of the paper is to show the wide applicability of the GPU&CPU technology to large scale computation and data processing.
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    Parallel algorithm for sorting animal pedigrees
    (Wydawnictwa AGH, 2009) Gierdziewicz, Maciej
    In many analyses of animal genotype with the methods of quantitative genetics there is a need to account for relationships among individuals. Incorrectly calculated relationship coefficients may lead to biased estimates. The number of software packages exist which deal with that problem, however, in many of them it is assumed that pedigrees of the individuals are sorted chronologically, but in real data sets - containing information on traits and pedigrees - birth dates are often missing. In extreme cases, when (almost) no birth dates are present, the ordering must be made by comparing - at least once - each pair of individuals separately, since it is not sufficient to compare adjacent elements in order to check whether the data set is sorted. Two versions of parallel computer programs were compared, with constant or variable distance between elements of compared pairs. The results indicate that the second algorithm is more efficient.
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    Comparing parallel programming environments for the joint inversion of geoelectrical data
    (Wydawnictwa AGH, 2009) Pięta, Anna; Bała, Justyna
    The article presents the comparison of the implementation of the inverse problem in geoelectrical methods in two different parallel computational environments. Combination of Monte Carlo method and Multistart algorithm was applied in the inversion process. Parallelization was done by fine grain decomposition. Execution time, speed-up and efficiency received for parallel algorithms in both computational environments were presented and analyzed.