101 research outputs found

    Green functions of currents in the odd-intrinsic parity sector of QCD

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    Greenovy funkce proudů umožňují studium resonancí v nízkoenergetické limitě QCD. Jejich použitím můžeme konstruovat např. amplitudy či rozpa- dové šířky procesů. Porovnáním teoretických předpovědí s experimentálními měřeními můžeme stanovit hodnoty parametrů teorie a získat tak ucelenější obraz o chování QCD procesů. V námi zkoumaném sektoru liché parity existuje celkem pětice netriviální tří-bodových Greenových funkcí, neboli korelátorů. Korelátory V V P a V AS již byly studovány v [1], zatímco výpočet AAP byl proveden v [2]. V této práci se tedy zabýváme dosud nestudovanými Greenovými funkcemi V V A a AAA přičemž předkládáme kompletní výpočet přispívajících Feynmanových diagramů v antisymetrickém tensorovém formalismu, který splňuje vysoko- energetické chování v rámci OPE, jak bylo rovněž ukázáno v [2]. Získané výsledky poté aplikujeme na studium fenomenologie. Dále, v práci se rovněž zabýváme studiem dvou čtyř-bodových Gre- enových funkcí, V V PP a V V V V , přičemž uvádíme pouze popis našich výpočtů, které, vzhledem k jejich komplikované tensorové struktuře, nemo- hou být v této práci obsaženy ve své kompletní formě. Na závěr pak uvádíme popis kódu 'Mercury',...Green functions of currents allow us to study resonances in the low- energy limit of QCD. Using them, we can construct amplitudes or decay widths of processes. By a comparison of the theoretical predictions with experimental measurements we can determine the values of parameters of the theory and obtain a more comprehensive understanding about the be- haviour of QCD processes. In our investigated topic, an odd-parity sector of QCD, exist five nontriv- ial three-point Green functions, also referred to as correlators. Correlators V V P and V AS have already been studied in [1], whilst a calculation of AAP was provided in [2]. In this thesis we therefore deal with the Green functions V V A and AAA that have not yet been studied before. We present a complete calculation of the contributing Feynman diagrams in the anti- symmetric tensor formalism that satisfies high-energy behaviour within the OPE framework, as was shown also in [2]. The obtained results are submit- ted to phenomenological studies. Further, we also present an introduction to our calculations of the four- point Green functions V V PP and V V V V . The calculations were carried out both in the antisymmetric tensor and vector formalism but due to the complicated tensor structure of the results, the calculations can not be shown here in their...Ústav částicové a jaderné fyzikyInstitute of Particle and Nuclear PhysicsMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

    Sledování vlivu průtočného průřezu kolem palivového proutku na vzniku krize přestupu tepla

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    Bakalářská práce pojednává o krizi přestupu tepla v jaderném reaktoru. Popisuje konstrukci palivových článků v jaderném reaktoru, přestup tepla v AZ jaderného reaktoru a jev krize přestupu tepla. Je popsáno měření teploty pomocí termočlánků. V praktické části je představeno experimentální zařízení ZČU pro zaznamenání krize přestupu tepla a je proveden návrh nového průtočného kanálu včetně nového imitátoru palivového proutku. Následně je ověřena jeho funkčnost a je porovnán s původním imitátorem palivového proutku.ObhájenoThe bachelor thesis describes the critical heat flux in a nuclear reactor. It describes the design of fuel elements in a nuclear reactor, heat transfer in a nuclear reactor and the phenomenon of the critical heat flux. Furthemore it describes temperature measurement using thermocouples. In the practical part, the experimental equipment of the ZČU for recording the critical heat flux is presented and the design of a new flow channel including a new fuel rod imitator is carried out. Subsequently, its functionality is verified and compared with the original fuel rod imitator

    Spiral extrusion die design using modified differential evolution algorithm

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    In this work, a spiral extrusion die for industrial production of plastic foil has been designed using a modified differential evolution algorithm. The proposed method managed to provide a die design that was compliant with all demands of the foil manufacturer and lowered the production cost. Third-Party software is used to compute the die characteristics from the geometry designed by modified differential evolution. © 2019, Brno University of Technology. All rights reserved

    Orthogonal Learning Firefly Algorithm

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    The primary aim of this original work is to provide a more in-depth insight into the relations between control parameters adjustments, learning techniques, inner swarm dynamics and possible hybridization strategies for popular swarm metaheuristic Firefly Algorithm (FA). In this paper, a proven method, orthogonal learning, is fused with FA, specifically with its hybrid modification Firefly Particle Swarm Optimization (FFPSO). The parameters of the proposed Orthogonal Learning Firefly Algorithm are also initially thoroughly explored and tuned. The performance of the developed algorithm is examined and compared with canonical FA and above-mentioned FFPSO. Comparisons have been conducted on well-known CEC 2017 benchmark functions, and the results have been evaluated for statistical significance using the Friedman rank test. © 2020 The Author(s).Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; European Regional Development Fund under the Project CEBIA-Tech [CZ.1.05/2.1.00/03.0089]; Internal Grant Agency of Tomas Bata University [IGA/CebiaTech/2020/001]; COST (European Cooperation in Science & Technology) under Action, Improving Applicability of NatureInspired Optimisation by Joining Theory and Practice (ImAppNIO) [CA15140]IGA/CebiaTech/2020/001; European Cooperation in Science and Technology, COST: CA15140; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LO1303, MSMT-7778/2014; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/03.008

    Self-organizing migrating algorithm with clustering-aided migration and adaptive perturbation vector control

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    The paper proposes the Self-organizing Migrating Algorithm with CLustering-aided migration and adaptive Perturbation vector control (SOMA-CLP). The SOMA-CLP is the next iteration of the SOMA-CL algorithm, further enhanced by the linear adaptation of the prt control parameter used to generate a perturbation vector. The latest CEC 2021 benchmark set on a single objective bound-constrained optimization was used for the performance measurement of the improved variant. The proposed algorithm SOMA-CLP results were compared and tested for statistical significance against four other SOMA variants. © 2021 ACM.IGA/CebiaTech/2021/00

    SOMA-CLP for competition on bound constrained single objective numerical optimization benchmark: A competition entry on bound constrained single objective numerical optimization at the genetic and evolutionary computation conference (GECCO) 2021

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    The paper represents a competition entry for the competition on bound constrained single objective numerical optimization at The Genetic and Evolutionary Computation Conference (GECCO) 2021 by a novel algorithm titled Self-organizing Migrating Algorithm with CLustering-aided migration and adaptive perturbation vector control (SOMA-CLP). © 2021 Owner/Author.IGA/CebiaTech/2021/00

    Analysing knowledge transfer in SHADE via complex network

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    In this research paper a hybridization of two computational intelligence fields, which are evolutionary computation techniques and complex networks (CNs), is presented. During the optimization run of the success-history based adaptive differential evolution (SHADE) a CN is built and its feature, node degree centrality, is extracted for each node. Nodes represent here the individual solutions from the SHADE population. Edges in the network mirror the knowledge transfer between individuals in SHADE's population, and therefore, the node degree centrality can be used to measure knowledge transfer capabilities of each individual. The correlation between individual's quality and its knowledge transfer capability is recorded and analyzed on the CEC2015 benchmark set in three different dimensionality settings-10D, 30D and 50D. Results of the analysis are discussed, and possible directions for future research are suggested.Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; Internal Grant Agency of Tomas Bata University [IGA/CebiaTech/2018/003]; COST (European Cooperation in Science & Technology), Improving Applicability of NatureInspired Optimisation by Joining Theory and Practice (ImAppNIO) [CA15140]; COST (European Cooperation in Science & Technology), HighPerformance Modelling and Simulation for Big Data Applications (cHiPSet) [IC1406]; European Regional Development Fund under the Project CEBIA-Tech [CZ.1.05/2.1.00/03.0089

    Explaining SOMA: The relation of stochastic perturbation to population diversity and parameter space coverage

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    The Self-Organizing Migrating Algorithm (SOMA) is enjoying a renewed interest of the research community, following recent achievements in various application areas and renowned performance competitions. In this paper, we focus on the importance and effect of the perturbation operator in SOMA as the perturbation is one of the fundamental inner principles of SOMA. In this in-depth study, we present data, visualizations, and analysis of the effect of the perturbation on the population, its diversity and average movement patterns. We provide evidence that there is a direct relation between the perturbation intensity (set by control parameter prt) and the rate of diversity loss. The perturbation setting further affects the exploratory ability of the algorithm, as is demonstrated here by analysing the parameter space coverage of the population. We aim to provide insight and explanation of the impact of perturbation in SOMA for future researchers and practitioners. © 2021 ACM.IGA/CebiaTech/2021/00

    Relation of neighborhood size and diversity loss rate in particle swarm optimization with ring topology

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    Measuring the population diversity in metaheuristics has become a common practice for adaptive approaches, aiming mainly to address the issue of premature convergence. Understanding the processes leading to a diversity loss in a metaheuristic algorithm is crucial for designing successful adaptive approaches. In this study, we focus on the relation of the neighborhood size and the rate of diversity loss in the Particle Swarm Optimization algorithm with local topology (also known as LPSO). We argue that the neighborhood size is an important input to consider when designing any adaptive approach based on the change of population diversity. We used the extensive benchmark suite of the IEEE CEC 2014 competition for experiments. © 2021, Brno University of Technology. All rights reserved.Univerzita Tomáše Bati ve Zlíně: IGA/CebiaTech/2021/00

    Soil Microbial Functional Diversity under the Single-Season Influence of Traditional Forest Management in a Sessile Oak Forest of Central Europe

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    This one-year study focuses on the responses of a soil environment to the implementation of traditional forest management practices in oak-hornbeam stands with the following treatments: cut (C), cut + litter raking (CR), cut + grazing (CG), cut + litter raking + grazing (CRG) and control (Ctrl). The cut was conducted in 2018 through extremely heavy thinning. In autumn of 2017 and 2018, we sampled the soils, focusing on microbial functional diversity (FD) assessments using BIOLOG EcoplateTM. After one season, the FD was the highest in the Ctrl stand and the lowest in the CRG stand. Furthermore, we detected significant seasonal differences in soil reaction, nitrate nitrogen content, phosphatase activity and microbial biomass among the treatments. In particular, the Ctrl stand was defined via FD indices and biochemical and biological soil properties that contrasted mainly with those of the CRG stand defined by the content of mineral nitrogen forms. The soil properties did not differ substantially in the remaining treatments. Of the 31 carbon sources defining FD, 6 were treatment-specific (putrescine, L-arginine, L-serine, L-threonine, D-cellobiose and glycogen), while the remaining carbon sources mainly displayed either uniform high or low activity across the treatments.O
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