Parallel computations are used in many areas where large computation amounts are required and/or faster response is critical. The development of parallel algorithms and parallel programming are complicated and require additional knowledge. To ease the parallel programming and algorithm parallelization many tools are developed. One class of such tools is algorithm templates. The idea of algorithm templates is to separate the problem specific and general parts of the algorithm. The general part can be implemented as a reusable module. The problem specific part of the algorithm should be implemented by the user. When these ideas are used for parallel programming, the template has to specify the main parts of the parallel algorithm: partitioning, communications, mapping, synchronization. Master – slave algorithms are very popular and widely used in parallel programming. It is efficient both for homogeneous and heterogeneous parallel computers. Parallelization tools of master – slave algorithms using popular communication libraries are useful. Many problems of engineering, economics and other fields are formulated as optimization problems. Optimization problems are often complicated and computation intensive. Therefore the creation of automatic parallelization tools of popular branch and bound optimization algorithms is relevant. Grillage type foundations are popular in case of weak grounds. It consists of beams that are supported by piles or reside on other beams. In order to... [to full text]

Daugelyje mokslo sričių susiduriama su uždaviniais, kuriuos išspręsti esamais kompiuteriais užtruktų nepriimtinai ilgai arba neįmanoma dėl tų uždavinių dydžio ir skaičiavimų apimties. Lygiagrečiaisiais skaičiavimais siekiame spręsti uždavinius greičiau, arba spręsti didesnius uždavinius. Tačiau tiek lygiagrečiųjų algoritmų sudarymas, tiek jų programinis realizavimas yra sudėtingi procesai, reikalaujantys daug žinių ir įgūdžių. Taupant laiką ir pastangas, yra kuriami lygiagretinimo įrankiai, lengvinantys įvairių lygiagrečiųjų programų ar metodikų naudojimą. Šeimininkas – darbininkai algoritmai yra dažnai naudojami ir paplitę įvairiose lygiagrečiųjų skaičiavimų srityse. Lygiagrečiųjų ���eimininkas – darbininkai algoritmų programų kūrimo automatizavimas palengvina daugelio uždavinių sprendimą. Šeimininkas – darbininkai algoritmas efektyvus vykdant tiek homogeniniuose, tiek heterogeniniuose lygiagrečiuosiuose kompiuteriuose. Duomenims tarp procesorių perduoti naudojamos duomenų perdavimo bibliotekos sparčiai vystomos. Nemažai anksčiau kurtų lygiagretinimo įrankių naudoja PVM duomenų perdavimo biblioteką. Išpopuliarėjus MPI duomenų perdavimo bibliotekai aktualu pritaikyti įrankius jos naudojimui. Daug praktinių uždavinių gali būti formuluojami kaip optimizavimo uždaviniai. Daugelis optimizavimo uždavinių sudėtingi ir reikalaujantys daug skaičiavimų. Šakų ir rėžių algoritmo principai taikomi kuriant tikslius ir euristinius algoritmus optimizavimo uždavinių sprendimui. Optimizavimo... [to full text] / Parallel computations are used in many areas where large computation amounts are required and/or faster response is critical. The development of parallel algorithms and parallel programming are complicated and require additional knowledge. To ease the parallel programming and algorithm parallelization many tools are developed. One class of such tools is algorithm templates. The idea of algorithm templates is to separate the problem specific and general parts of the algorithm. The general part can be implemented as a reusable module. The problem specific part of the algorithm should be implemented by the user. When these ideas are used for parallel programming, the template has to specify the main parts of the parallel algorithm: partitioning, communications, mapping, synchronization. Master – slave algorithms are very popular and widely used in parallel programming. It is efficient both for homogeneous and heterogeneous parallel computers. Parallelization tools of master – slave algorithms using popular communication libraries are useful. Many problems of engineering, economics and other fields are formulated as optimization problems. Optimization problems are often complicated and computation intensive. Therefore the creation of automatic parallelization tools of popular branch and bound optimization algorithms is relevant. Grillage type foundations are popular in case of weak grounds. It consists of beams that are supported by piles or reside on other beams. In order to... [to full text]

Objective – research the pine wood nematodes Bursaphelenchus sp. situation in Lithuania. Goals: 1. Research of native pine wood nematode species composition in Lithuania; 2. Research of preconditions for harmful pine wood nematode species to enter Lithuania; 3. Research of conditions for non-native pine wood nematode species to establish, breed and spread; 4. Research of consequences if harmful species becomes established in Lithuania, anticipate pest management options. Object of the study – coniferous (pine) forests in Lithuania and companies, processing imported wood. Methods. Samples were taken in coniferous clearcuts and wood processing companies from the stained wood or wood with evidence of Monochamus activities. Nematodes were extracted sing Baermann method. Preconditions for nematodes to enter Lithuania, establish and spread were analysed using statistical and literature sources. Strengths, weaknesses, opportunities, threats (SWOT) analysis was applied to the situation of Bursaphelenchus in Lithuania. Results. 27 forest enterprises and 62 wood processing companies were studied. For the first time in Lithuania non-pathogenic species Bursaphelenchus mucronatus was found. Assessement of conditions for wood nematodes in the country (import assortment and volume, countries, host plants and potential vectors), real probability for harmful species, particularly Bursaphelenchus xylophilus, to enter, establish and spread was defined. Existing quarantine system might... [to full text]