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Parameter Identification for Elastic-plastic Material Models from Experimental Data
Jeník, Ivan ; Šebek, František (referee) ; Kubík, Petr (advisor)
This master's thesis deals with the identification of the material flow curve from record of tensile test of smooth cylindrical specimen. First, necessary theory background is presented. Basic terms of incremental theory of plasticity, tensile test procedure and processing its outputs are described. Furthermore, possibilities of mathematical expression of the elastic-plastic material constitutive law, thus mathematical expression of the material flow curve itself. Mechanism of ductile damage of material is explained briefly as well. Overview of recent methods of the flow curve identification is given, focused on cases, when the stress distribution in a specimen is not uniaxial. That is either kind of analytic correction of basic formulas derived for uniaxial stress state, or application of mathematical optimization techniques combined with numerical simulation of the tensile test. Also unusual method of neural network is mentioned. For 8 given materials, the flow curve identification was performed using different methods. Namely by analytic correction, optimization, sequential identification and neural network. Algorithms of the last two methods were modified. Based on assessment of obtained results, application field and adjusting the parameters of single algorithms was recommended. It showed up, that an effective way to the accurate and credible results is the combination of different methods during flow curve identification procedure.
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Materials of pietra dura artistic technique: composition, properties, provenance and possible identification
Jaroměřský, Štěpán ; Přikryl, Richard (advisor) ; Kuchařová, Aneta (referee)
Pietra dura or Florentine mosaic is a method of assembling thin slices of variously colored minerals and rocks into meaningful patterns or scenes. This artistic technique experienced a significant flourishing in Rudolfine Prague, where many works were created by this technique with materials that have not been described in detail yet. Although decorative carbonate rocks are frequently found in works made by the technique of pietra dura, decorative siliceous materials of jasperoid character, colored red, ochre or green, are equally important. This diploma thesis deals with the mineralogical and material research of these siliceous materials. One of the main objectives of the thesis was to explore possible discriminatory characteristics of siliceous materials from Czech localities, especially from the Kozákov area, which is historically documented as a deposit of jasperoid materials since at least the 16th century. The focus of the thesis lies in a set of mineralogical-petrographic and analytical methods of research. Using optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, powder X-ray diffraction, Raman spectroscopy, Mössbauer spectroscopy and observation in ultraviolet light, it was possible to determine the minerals contained in the studied jasperoid materials....
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Methods of Stakeholder Identification in Evaluation
Strašilová, Eva ; Remr, Jiří (advisor) ; Tuček, Milan (referee)
This text deals with the issue of identification of stakeholders in the evaluation. The concept of stakeholders is defined first, and the characteristics of the evaluation approaches are presented. Later is presented the position of the world evaluation societies on the stakeholders. There are four methods of stakeholder identification: 1) Brainstorming, 2) General list, 3) Questions and 4) The snowball method. Own research focuses on methods of identification of stakeholders in evaluations in the Czech Republic. Data sources are evaluations of OP and ROP programs. Secondary and content data analysis was used to analyse the data. The result of the research is that specific methods of stakeholder identification have not been applied in OP and ROP evaluations. Based on the results of the research, a new procedure for identification of stakeholders in the evaluation was formulated.
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Parameter Identification for Elastic-plastic Material Models from Experimental Data
Jeník, Ivan ; Šebek, František (referee) ; Kubík, Petr (advisor)
This master's thesis deals with the identification of the material flow curve from record of tensile test of smooth cylindrical specimen. First, necessary theory background is presented. Basic terms of incremental theory of plasticity, tensile test procedure and processing its outputs are described. Furthermore, possibilities of mathematical expression of the elastic-plastic material constitutive law, thus mathematical expression of the material flow curve itself. Mechanism of ductile damage of material is explained briefly as well. Overview of recent methods of the flow curve identification is given, focused on cases, when the stress distribution in a specimen is not uniaxial. That is either kind of analytic correction of basic formulas derived for uniaxial stress state, or application of mathematical optimization techniques combined with numerical simulation of the tensile test. Also unusual method of neural network is mentioned. For 8 given materials, the flow curve identification was performed using different methods. Namely by analytic correction, optimization, sequential identification and neural network. Algorithms of the last two methods were modified. Based on assessment of obtained results, application field and adjusting the parameters of single algorithms was recommended. It showed up, that an effective way to the accurate and credible results is the combination of different methods during flow curve identification procedure.
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Vibration evaluation and identification in mechanical engineering
Kozánek, Jan
This paper deals with parametric identification in mechanical engineering domain. We assume a linear mathematical model of vibrating machine in discrete form and in frequency domain, defined by stiffness, viscous damping and mass matrices and by the corresponding resolvent. Parametric identification is understood as the evaluation of the measured data from dynamic experiments and its methods can be divided into "indirect" (obtaining spectral and modal properties - modal analysis methods) and "direct" (determination of the coefficient matrices of the mathematical model). We mention also the parametric identification methods for parametric and evolutive dynamic systems , the loss of asymptotic stability and dynamic systems with weak nonlinearities.
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