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STRUCTURAL, THERMODYNAMICS AND PHYSICAL PROPERTIES OF Zn Sn Al ALLOYS
Drápala, J. ; Musiol, J. ; Petlák, D. ; Vodárek, V. ; Smetana, B. ; Zlá, S. ; Kostiuková, G. ; Kroupa, Aleš ; Sidorov, V.E.
Some results of thermodynamic, structural and physical properties of Al-Sn-Zn alloys are presented in our paper. The ternary Al-Sn-Zn alloys were prepared in a resistance furnace in evacuated ampoules. The alloys were studied metallographically, their micro-hardness and X-ray micro-analysis (EDX, SEM) of individual phases were measured. Temperatures of phase transitions (liquidus, solidus, invariant reactions, etc.) were obtained using the DTA method (Setaram SETSYS 18 (TM)). The long time annealing (250, 300, 350 degrees C, 3, 7, 14 or 28 days) was used in order to achieve the thermodynamic equilibrium. The results were confronted with thermodynamic modelling of the ternary Al Sn Zn system in the Institute of Physics of Materials AS of the Czech Republic in Brno. We have studied density (by gamma-absorption method), electrical resistivity (by contactless method in rotating magnetic field) and magnetic susceptibility (by Faraday's method) of some Al-Sn-Zn alloys containing up to 10 at.% of aluminum and up to 65 at.% of zinc. The increasing of zinc content resulted in the decrease of the density and susceptibility values, except for one sample. The resistivity values practically didn't depend on the zinc content in the crystalline state, whereas a maximum was found for one of the samples in the liquid state. This work has been made in the frame of COST Action MP0602 project 'Advanced Solder Materials for High-Temperature Application'.
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Thermodynamics of adsorption of natural organic matter onto activated carbon
Hirsch, Karel ; Pivokonský, Martin (advisor) ; Čermáková, Lenka (referee)
The presence of natural organic matter (NOM) in water resources can significantly affect the organoleptic properties of water, inhibit the processes of drinking water treatment and may be harmful to organisms and to human health. That is why the drinking water treatment process is therefore emphasizes the elimination of natural organic matter by the best available techniques. To remove NOM is currently proving to be the most effective adsorption process on the activited carbon (AC). The process of adsorption of natural substances on activated carbon affects many factors. Important factors affecting adsorption are the solution properties such as pH, ionic strength (IS), chemical composition and temperature of the solution. Due to different water temperatures, depending on the season, the temperature can significantly affect the process of NOM adsorption on activated carbon in drinking water treatment. The authors in their works devoted primarily to the effect of pH on adsorption and in the literature is shown little information on the effect of water temperature on the adsorption of natural organic matter. This thesis deals with thermodynamics of adsorption of natural organic matter to activated carbon. Bachelor's thesis in the form of research describes the basic properties of thermodynamics of...
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The Nature of Entrepreneurship: Society, the Individual and the Firm
Kapustin, Victor ; Benáček, Vladimír (advisor) ; Balcar, Petr (referee)
Entrepreneurship is often perceived as a crucial component of economic growth and social development. Studies into entrepreneurship inform policy design, thus the diverse understanding of entrepreneurship among scholars can create confusion in policy design. The current state of the field of entrepreneurial research is examined in order to identify the need for a universal definition of entrepreneurship. After a synthesis and analysis of prior research is conducted to identify the various links in perspectives, a new definition and framework is suggested. The resulting framework sees entrepreneurship as an autocatalytic process of creation of meaning and the consequent retention of said meaning in the structure of a new venture. The elements of this framework (autocatalytic process, creation of meaning, and retention in structure) can be assigned varying degrees of importance corresponding to differing perspectives, while simultaneously ensuring the presence of each element. The developed framework can be used to better inform the decisions of scholars and policy makers, due to the uncovering of the complex relationships between society, individuals and firms.
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Mineral assemblages, alteration reactions and transport model of the greisen formation in the Horní Blatná granite pluton, Krušné hory Mts.
Heřmanská, Matylda ; Dolejš, David (advisor) ; Štemprok, Miroslav (referee)
English abstract Hydrothermal systems related to highly evolved granitic magmas host diverse mineralization styles and provide an important source of economic metals. This master thesis concentrates on description and interpretation of geological structure, petrographic and textural variability, alteration zoning and calculation of time-integrated fluid fluxes recorded in highly evolved granites and tin-mineralized greisens of the Horní Blatná massif in the Western Krušné hory pluton. The massif is a composite intrusion, which consists of a large number of intrusive units emplaced during two stages. The first stage is represented by sparsely porphyritic fine-grained low-lithian annite granites that can be correlated with marginal granites (G2) of the Fichtelgebirge (Smrčiny) batholith or with intermediate granites (Walfischkopf type) of the Western Krušné hory (Erzgebirge) pluton. Intrusive batches of the second stage progressively evolve from medium- to coarse-grained serial high-lithian annite and zinnwaldite granites with topaz and rare tourmaline towards aphyric fine-grained zinnwaldite (or trilithionite) granites. This suite corresponds to the EIB2 and EIB3 facies of the younger intrusive complex in the Western Krušné hory (Erzgebirge) pluton and it can be compared to the G3 Waldstein and G4 units in...
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Nerovnosti a jejich aplikace
TESAŘOVÁ, Jaroslava
This Thesis deals with mathematical inequalities, their use in mathematics and applications to thermodynamics. The main emphasis is placed on proofs of inequalities and solving examples. The following thing explains the mathematical concept such as norm or metric, needed to understand these procedures, and also some of basic concepts of thermodynamics. To understand this Thesis the knowledge of analysis and thermodynamics is required.
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Entropy and Consumerism in Pynchon's Works
Litochleb, Daniel ; Roraback, Erik Sherman (advisor) ; Robbins, David Lee (referee)
In his works, Pynchon engages the difficult concept of entropy and exposes how certain trends in contemporary culture and society, such as consumerism, exhibit tendencies similar to those of entropy. This observation has disturbing implications for contemporary culture and society, such as eventual cultural heat-death, where new ideas cease to develop, because all the useful intellectual energy has been exhausted. Therefore, I have decided to examine this concept of entropy and how Pynchon engages it in his works "Entropy," The Crying of Lot 49 and Gravity's Rainbow, which expose the main contributors to greater entropy and the disturbing implications of this concept for contemporary culture and society, some of which we are witnessing even today. The two main scientific types of entropy, thermodynamic and that of information theory, are explored by Pynchon in his early short story "Entropy," which I have analyzed in the second chapter of this thesis. As such, this short story provides an unobstructed view of Pynchon's early engagement with the concept of entropy, which increases in complexity in his later works The Crying of Lot 49 and Gravity's Rainbow. The Crying of Lot 49, explored in the third chapter of this thesis, indicates a considerable development of and change in Pynchon's perspective...
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Mathematical and computational modeling of shape-memory alloys
Benešová, Barbora ; Roubíček, Tomáš (advisor) ; Krejčí, Pavel (referee) ; Stefanelli, Ulisse (referee)
This dissertation thesis is concerned with developing a mesoscopic model for sin- gle crystalline shape-memory alloys including thermo-dynamically consistent thermo- mechanical coupling - here the term "mesoscopic" refers to the ability of the model to capture fine spatial oscillations of the deformation gradient by means of gradient Young measures. Existence of solutions to the devised model is proved in a "phase-field-like approach" by a scale transition from a microscopic model that features a term related to the interfacial energy; this scale transition from a physically relevant model justifies the mesoscopic relaxation. Further, existence of solutions is also proved by backward- Euler time discretization which forms a conceptual numerical algorithm. Based on this conceptual algorithm a computer implementation of the model has been developed and further optimized in the rate-independent isothermal setting; some calculations using this implementation are also presented. Finally, refinements s of the analysis in the convex case as well as a limit of the phase-field-like approach in this case are exposed, too.
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Termodynamická analýza procesů v polymerní elektrolytické membráně palivového článku
Pavelka, Michal ; Maršík, František (advisor) ; Málek, Josef (referee)
Thermodynamic analysis of processes in electrolytic fuel cell membrane Michal Pavelka April 12, 2012 Abstract Hydrogen fuel cells1 may become a key technology of 21st century, and it is important to be able to describe their behavior, therefore. In this work we focus on hydrogen fuel cells with a polymer-electrolyte membrane. For the membrane we adopt an existing model2 . We for- mulate the model in the framework of the mixture theory which we develop similarly as has been done in the classical textbook of Mazur and de Groot3 . However, refining the concept of potential energy of a material point, we introduce new terms called internal potential ener- gies which enable us to describe macroscopic consequences of internal forces between water and polymer in the membrane and to describe the influence of gradient of surface tension of water in the membrane. We solve the model in 1D approximation. Consequently, we calculate the influence processes in the membrane have on efficiency of the fuel cell. 1 see for example Larminie, J. and A. Dicks. Fuel Cell Systems Explained. 2nd edition. John Wiley & Sons Ltd., 2003. ISBN 0-470-84857-X. 2 Weber, A. Z. and J. Newman. Transport in Polymer-Electrolyte Membranes I, II, III. J. Electrochem. Soc., 150 (7), A1008-A1015, 2003; 151 (2), A1311-A1325, 2004.; 151 (2), A1326-A1339,...
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Thermodynamics of ideal cycles of IC engines in Matlab
Pavlíček, David ; Mauder, Tomáš (referee) ; Štětina, Josef (advisor)
Key aspect of this thesis is toolbox, which contains functions for calculate ideal combustion engine cycles. Thesis is divided into four parts. In the first part is briefly described history. The first chapter contains description of real combustion engine types. In the second part, which is covered by the second chapter, is located thermodynamic view. Third part is whole about MATLAB. From historical introduction through description of individual functions to example how toolbox can be used. In the last part is comparison of real combustion engine cycle with ideal one, which has been created by toolbox.
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