Computer Science Journal (AGH University of Science and Technology, Krakow)
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Niching in Evolutionary Multi-agent Systems
Get PDFNiching is a group of techniques used in evolutionary algorithms, useful inseveral types of problems, including multimodal or nonstationary optimiza-tion. This paper investigates the applicability of these methods to evolutionarymulti-agent systems (EMAS), a hybrid model combining the advantages of evo-lutionary algorithms and multi-agent systems. This could increase the efficiencyof this type of algorithms and allow to apply them to a wider class of prob-lems. As a starting point, a simple but flexible EMAS framework is proposed.Then, it is shown how to extend this framework in order to introduce niching,by adapting two classical niching methods. Finally, preliminary experimentalresults show the efficiency and the simultaneous discovery of multiple optimaby this modified EMAS
Volunteer Computing Simulation using Repast and Mason
Get PDFVolunteer environments usually consist of a large number of computing nodes,with highly dynamic characteristics, therefore reliable models for a planning ofthe whole computing are highly desired. An easy to implement approach to mo-delling and simulation of such environments may employ agent-based universalsimulation frameworks, such as RePast or MASON. In the course of the paperthe above-mentioned simulation frameworks are adapted to support simulationof volunteer computing. After giving implementation details, selected resultsconcerning computing time and speedup are given and are compared with theones obtained from an actual volunteer environment
COMPARING PARALLEL PROGRAMMING ENVIRONMENTS FOR THE JOINT INVERSION OF GEOELECTRICAL DATA
Get PDFThe article presents the comparison of the implementation of the inverse problem in geoelectricalmethods in two different parallel computational environments. Combination of MonteCarlo method and Multistart algorithm was applied in the inversion process. Parallelizationwas done by fine grain decomposition. Execution time, speed-up and efficiency received forparallel algorithms in both computational environments were presented and analyzed
EXTENDING THE SHEBA PROPAGATION MODEL TO REDUCE PARAMETER-RELATED UNCERTAINTIES
Get PDFHeliophysics is the branch of physics that investigates the interactions and cor-relation of different events across the Solar System. The mathematical modelsthat describe and predict how physical events move across the solar system (ie.Propagation Models) are of great relevance. These models depend on parame-ters that users must set, hence the ability to correctly set the values is key toreliable simulations. Traditionally, parameter values can be inferred from dataeither at the source (the Sun) or arrival point (the target) or can be extrapo-lated from common knowledge of the event under investigation. Another way ofsetting parameters for Propagation Models is proposed here: instead of guess-ing a priori parameters from scientific data or common knowledge, the model isexecuted as a parameter-sweep job and selects a posteriori the parameters thatyield results most compatible with the event data. In either case (a priori anda posteriori), the correct use of Propagation Models requires information toeither select the parameters, validate the results, or both. In order to do so, itis necessary to access sources of information. For this task, the HELIO projectproves very effective as it offers the most comprehensive integrated informationsystem in this domain and provides access and coordination to services to mineand analyze data. HELIO also provides a Propagation Model called SHEBA,the extension of which is currently being developed within the SCI-BUS project(a coordinated effort for the development of a framework capable of offering toscience gateways seamless access to major computing and data infrastructures)
INFORMATION RETRIEVAL USING ASSOCIATION LISTS
Get PDFThe paper presents the main models of information retrieval in text. The idea of association list and its use for information retrieval is introduced. The paper contains the evaluation results of the algorithms under discussion
ELONGATION CUTOFF TECHNIQUE: PARALLEL PERFORMANCE
Get PDFIt is demonstrated that the elongation cutoff technique (ECT) substantially speeds up thequantum-chemical calculation at Hartree-Fock (HF) level of theory and is especially wellsuited for parallel performance. A comparison of ECT timings for water chains with thereference HF calculations is given. The analysis includes the overall CPU (central processingunit) time and its most time consuming steps
PARALLEL AND DISTRIBUTED CALCULATIONS SUPPORTED AND MANAGED BY THE RELATIONAL DATABASE
Get PDFA simple, based on a relational database, system, for a management of a parallel and a distributedcomputer calculations, is presented. In the proposed system, the parallel calculationsare carried out according to a master/slave model. Because an input and an output data ofprograms are stored directly in the database, the use of files is reduced to a minimum. Themanagement system allows for a combination of computing power of many computers forsolving a single numerical problem
BENCHMARKING HIGH PERFORMANCE ARCHITECTURES WITH NATURAL LANGUAGE PROCESSING ALGORITHMS
Get PDFNatural Language Processing algorithms are resource demanding, especially when tuning toinflective language like Polish is needed. The paper presents time and memory requirementsof part of speech tagging and clustering algorithms applied to two corpora of the Polishlanguage. The algorithms are benchmarked on three high performance platforms of differentarchitectures. Additionally sequential versions and OpenMP implementations of clusteringalgorithms were compared
TEXT SUMMARIZING IN POLISH
Get PDFThe aim of this article is to describe an existing implementation of a text summarizer forPolish, to analyze the results and propose the possibilities of further development. Theproblem of text summarizing has been already addressed by science but until now there hasbeen no implementation designed for Polish. The implemented algorithm is based on existingdevelopments in the field but it also includes some improvements. It has been optimized fornewspaper texts ranging from approx. 10 to 50 sentences. Evaluation has shown that it worksbetter than known generic summarization tools when applied to Polish
ENHANCING REGULAR EXPRESSIONS FOR POLISH TEXT PROCESSING
Get PDFThe paper presents proposition of regular expressions engine based on the modified Thompson’salgorithm dedicated to the Polish language processing. The Polish inflectional dictionaryhas been used for enhancing regular expressions engine and syntax. Instead of usingcharacters as a basic element of regular expressions patterns (as it takes place in BRE orERE standards) presented tool gives possibility of using words from a natural language orlabels describing words grammar properties in regex syntax