In this thesis, a PEMFC stack, which can be self-humidification of passive portable hydrogen fuel cell, will be developed. The stack is developed for portable applications, so the structure of the stack is simplified as possible as we can. As the cathode directly exposed under the atmosphere, so in a long time, the membrane easily lead to excessive evaporation of water, so that performance degradation. The traditional humidifier is more complex applications are not suitable for portable, so this thesis stack developed by the use of cotton capillarity, the water from the tanks transferred to the membrane, and then by cotton and a good touch to the membrane humidifier effect, this structure without an increase in large equipment, in line with the principles of portability. The PEMFC stack is made with carbon fiber bunches for current collectors and two 8-cell banded-type MEAs, the stack can develop a high voltage by serially connecting outside of the reaction chamber. 16-cell in series when the current density is greater than 110mA/cm2, use humidification to avoid long time operation, due to water cause a voltage drop. Humidification is not only to help transfer of hydrogen ions, and the role of a cooling stack, the cells temperature is too high will not cause transpiration rate of speed. Current density greater than 250mA/cm2, although humidity can still be effective, but insufficient humidification single cotton, one hour after, the voltage drop of about 20% longer cell performance, such as humidity will be no more have a more significant decline phenomenon, more cotton or additional external humidification humidifier can maintain a long-time stable operation. Therefore, the performance of the cells in order to avoid a recession, should pay attention to in a long time when working conditions and operating range.

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This thesis centers on the development and analysis of numerical multiscale methods for multiscale problems arising in steady heat conduction, heat transfer and wave propagation in heterogeneous media. In a multiscale problem several scales interact with each other to form a system which has variations over a wide range of scales. A direct numerical simulation of such problems requires resolving the small scales over a computational domain, typically much larger than the microscopic scales. This demands a tremendous computational cost. We develop and analyse multiscale methods based on the heterogeneous multiscale methods (HMM) framework, which captures the macroscopic variations in the solution at a cost much lower than traditional numerical recipes. HMM assumes that there is a macro and a micro model which describes the problem. The micro model is accurate but computationally expensive to solve. The macro model is inexpensive but incomplete as it lacks certain parameter values. These are upscaled by solving the micro model locally in small parts of the domain. The accuracy of the method is then linked to how accurately this upscaling procedure captures the right macroscopic effects. In this thesis we analyse the upscaling error of existing multiscale methods and also propose a micro model which significantly reduces the upscaling error invarious settings. In papers I and IV we give an analysis of a finite difference HMM (FD-HMM) for approximating the effective solutions of multiscale wave equations over long time scales. In particular, we consider time scales T^ε = O(ε−k ), k =1, 2, where ε represents the size of the microstructures in the medium. In this setting, waves exhibit non-trivial behaviour which do not appear over short time scales. We use new analytical tools to prove that the FD-HMM accurately captures the long time effects. We first, in Paper I, consider T^ε =O(ε−2 ) and analyze the accuracy of FD-HMM in a one-dimensional periodicsetting. The core analytical ideas are quasi-polynomial solutions of periodic problems and local time averages of solutions of periodic wave equations.The analysis naturally reveals the role of consistency in HMM for high order approximation of effective quantities over long time scales. Next, in paperIV, we consider T^ε = O(ε−1 ) and use the tools in a multi-dimensional settingto analyze the accuracy of the FD-HMM in locally-periodic media where fast and slow variations are allowed at the same time. Moreover, in papers II and III we propose new multiscale methods which substantially improve the upscaling error in multiscale elliptic, parabolic and hyperbolic partial differential equations. In paper II we first propose a FD-HMM for solving elliptic homogenization problems. The strategy is to use the wave equation as the micro model even if the macro problem is of elliptic type. Next in paper III, we use this idea in a finite element HMM setting and generalize the approach to parabolic and hyperbolic problems. In a spatially fully discrete a priori error analysis we prove that the upscaling error can be made arbitrarily small for periodic media, even if we do not know the exact period of the oscillations in the media. / <p>QC 20150216</p> / Multiscale methods for wave propagation

Yes / In this article we briefly review the Boxed Molecular Dynamics (BXD) method, which allows analysis of thermodynamics and kinetics in complicated molecular systems. BXD is a multiscale technique, in which thermodynamics and long-time dynamics are recovered from a set of short-time simulations. In this article, we review previous applications of BXD to peptide cyclization, diamond etching, solution-phase organic reaction dynamics, and desorption of ions from self-assembled monolayers (SAMs). We also report preliminary results of simulations of diamond etching mechanisms and protein unfolding in AFM experiments. The latter demonstrate a correlation between the protein’s structural motifs and its potential of mean force (PMF). Simulations of these processes by standard molecular dynamics (MD) is typically not possible, since the experimental timescales are very long. However, BXD yields well-converged and physically meaningful results. Compared to other methods of accelerated MD, our BXD approach is very simple; it is easy to implement, and it provides an integrated approach for simultaneously obtaining both thermodynamics and kinetics. It also provides a strategy for obtaining statistically meaningful dynamical results in regions of configuration space that standard MD approaches would visit only very rarely. / DRG is grateful for funding from a Royal Society Research Fellowship. JB and DVS acknowledge the support of EPSRC (Grant No EP/E009824/1). E.M.-N. and S.A.V. are grateful to the “Centro de Supercomputación de Galicia (CESGA)” for the use of its computational resources, as well as to “Ministerio de Economía y Competitividad” (Grant No. CTQ2009-12588) for financial support. DS and E.M.-N. acknowledge the Leverhulme Trust for funding the E.M.-N. visit to Leeds by the grant “Accelerated classical and quantum molecular dynamics and its applications” (Grant No. VP1-2012-013).

The thesis is aimed at climatological, agroclimatological and phenological conditions at Tušimice observatory during 45 years of observations (1968-2012) on basis of meteorological and phenological data by using statistical methods, method of cumulative series and geographical information system. Basic climatic elements (air temperature, precipitation total, snow cover, cloudiness, wind, humidity, sunshine duration, fog and thunderstorm), agroclimatic characteristics according to the WMO recommendation, selected phenological phases (mainly beginning of flowering 10 %) of herb and wooden species were processed in the study. The literature overview was made on climatic and phenological conditions at Tušimice station, in the Czech Republic and other countries. Apart from statistical analysis, the elements were also evaluated in the interaction with the changing air circulation in Central Europe. In addition, results were compared to Quitt's classification based on long-term averages of meteorological data (1961-1990 versus 1981-2010). The drought occurrence was evaluated in 45 years of observations period. The thesis is divided into three main parts - Climatic conditions of Tušimice observatory (part 5.1), Agroclimatic conditions of Tušimice observatory (part 5.2) and Phenological conditions of...

La propagation des états cohérents est un sujet actif de la recherche de ces dernières décennies. Un état cohérent est la modélisation quantique d'une particule classique. La trajectoire d'une particule chargée dans un champ magnétique fort, i.e. qui ne s'annule pas, est donnée par le mouvement centre guide : il s'agit d'oscillations rapides autour d'un centre virtuel dont la dynamique plus lente suit les lignes de champ magnétique. Le sujet de ma thèse est d'étudier le pendant magnétique de ce résultat. Il est connu que pour des temps courts, c'est à dire bornés en le paramètre semi-classique h, la dynamique d'un état cohérent est donnée par la dynamique classique de la particule associée. Le problème est alors l'étude de la dynamique en temps longs de tels états. Pour des états cohérents de basses énergies, en utilisant des résultats de forme normale et de régularité elliptique magnétique, on prouve le résultat suivant de propagation magnétique en temps longs. Un état cohérent sous un champs magnétique se propage pour des temps de l'ordre de l'inverse de h en une somme d'états cohérents évoluant sur une même trajectoire, mais à des vitesses différentes. / The propagation of coherent states was extensively studied over past decades. A coherent state is the quantum version of a classical particle. The trajectory of a charged particle under strong magnetic field, that is a non-vanishing field, is given by the center guide motion : it is high speeds oscillations around a virtual center that moves slowly along the field lines of the magnetic field. The aim of this thesis is the study of the quantum translation of this. It is well-known that for short times, i.e. bounded times with respect to the semiclassical parameter h, the dynamics of such a state is given by the classical trajectory of the associated particle. The thing is to study the dynamics of coherent states for long times, that are times going to infinite as h goes to 0. For low energy coherent states, using normal form and magnetic elliptical regularity results, we prove the following long time magnetic propagation result. A coherent state under strong magnetic field is propagated as a sum of coherent states following the same dynamics, but with different speeds.

This thesis analyzes the relationship between upper extremity musculoskeletal disorders and longtime computer usage. Firstly / maastricht upper extremity questionnaire is applied to Financial Control and Information Technology Departments of Turk Telekom. Results are analyzed by using spss 16.0 tool by conduction of ordinal logistic regression analysis to determine the significance between work environment and postural information and upper extremity musculoskeletal complaints. Then / development of a new tool, namely PACU (postural analysis of computer users), takes place aiming to determine the factors of disorders, by mainly focusing on work-related neck and upper limb disorders, for long time computer users of Financial Control and Information Technology Departments of Turk Telekom. Results of the PACU are analyzed by using the methods of correlation, chi square goodness of fit test, factor analysis, and ordinal logistic regression.

This diploma thesis addresses the issue of the analysis of labor market developments in the period 2005-2015, especially the development of indicators of employment and unemployment. In the first, theoretical part, is the method used literature review, in this part of the basic concepts and theoretical background on the labor market as employment, unemployment, economic activity, economic crisis. Attention is also paid to indicators which are used in the practical part. The second part is practical, includes data analysis and indicators of employment and unemployment on the labor market in the Czech Republic, for which purposes the analysis of selected data from the Labour Force Survey. The third and final part of the thesis is focused on a comprehensive analysis period 2005-2015. In the final analysis it shows that despite the fact that the Czech labor market observed in the negative sense of economic crisis, its impact had long-term consequences, but resulted in the period of 2009-2011, and in subsequent years has been some labor market indicators show positive values again.

My diploma theses deals with the problem of the speaker recognition. The basic theory of this problem is described in the text as well as model and implementation of the system for speaker recognition. The scope of the system is to recognize up to three speakers. The theory is based on calculation parameters for speaker recognition and processing of voice. Program is made in Matlab as a independent application and it has got Czech and English interface.

The differences between refolding mechanisms of sperm whale apomyoglobin subsequent to three different unfolding conditions have been examined by atomistic level computer simulations. The three unfolding conditions used in this work are high-temperature, low temperature and low pH. The folding of this protein has been extensively studied experimentally, providing a large data base of folding parameters which can be probed using simulations. The crystal structure of sperm whale myoglobin was taken from Protein Data Bank, followed by the removal of the heme unit and a subsequent energy minimization was performed in order to generate the native apomyoblogin form. Thus, the native conformation of apomyoglobin utilized is the same in all the three different refolding simulations done in the present work. The differences are the way the initial unfolded conformations were obtained. The refolding trajectories were obtained at room temperature using the Stochastic Difference Equation in Length algorithm. The results reveal differences between the three refolding routes. In contrast to previous molecular simulations that modeled low pH denaturation, an extended intermediate with large helical content was not observed in the refolding simulations from the high-temperature unfolded state. Otherwise, a structural collapse occurs without formation of helices or native contacts. Once the protein structure is more compact (radius of gyration less than 18 angstroms) secondary and tertiary structures appear. The low pH simulations show some agreement with the low pH experimental data and previous molecular dynamics simulations, like formation of a conformation having radius of gyration around 20 angstroms and large helical content. And the refolding simulations after the low temperature unfolding present differences in the properties of apomyoglobin folding route, comparing to the other two previous conditions. The collapse of the protein during folding occurs later in the simulation when compared with high-temperature denaturing state, but earlier when compared to low pH simulations. These differences strongly suggest that a protein can follow different folding routes, depending on the nature and the structure of the unfolded state.