The HVDC, High Voltage Direct Current, is important when it comes to upgrading the energy system to a renewable, sustainable and efficient system. This master thesis is investigating what is happening during the most decisive fault cases when the HVDC station is operating with inherent overload. An inherent overload operating area is defined and simulations are performed in PSCAD/EMTDC to study the transient behavior of the fault currents and overvoltages.

The proposed work evaluates the technical viability of a photovoltaic pumping system and presents the main characteristics of the system application. The pumping system uses a lead acid battery and a photovoltaic panel. The battery supplies energy to an alternating current motor, namely Shaded Pole, which feeds the centrifugal surface pump. The energy from the battery is changed to AC voltage by a DC-AC inverter, 12/220 V. The voltage level applied on this battery is monitored by a load controller (solar power regulator). The whole proposed system is made in Brazil, which facilitates the purchase, alteration and building of the system. The amount of water pumped is related to the solar radiation, the solar exposition period, the manometric height and the pumping power. By evaluating the proposed system is possible to find the volume of pumped water and how this amount will be applied at small rural municipalities, as human and animal water consumption, irrigation, among others. / O presente trabalho tem por finalidade determinar o comportamento e a viabilidade técnica e energética de um sistema de bombeamento fotovoltaico utilizando uma bateria do tipo chumbo-ácido, estacionária ou usada em veículos automotores, alimentada por um painel fotovoltaico. A bateria fornecerá energia elétrica para um motor elétrico CA, tipo Shaded Pole, que por sua vez acionará uma bomba centrífuga de superfície. A transformação da CC da bateria em CA, para alimentar o motor da bomba, se dará através de um Inversor CC-CA, 12/220 V. A tensão elétrica aplicada na bateria, pelo painel, será monitorada por um Controlador de Carga Solar. O conjunto motobomba será de fabricação brasileira, de modo a facilitar a aquisição, reposição e montagem do sistema proposto. A quantidade de água diária a ser bombeada pelo sistema dependerá da radiação solar do local, das horas em que o painel alimentará a bateria, da altura manométrica e da potência da motobomba. A partir da avaliação deste sistema de bombeamento em questão, com a motobomba alimentada pela luz solar que incide no painel fotovoltaico e pela bateria, será possível determinar o volume de água bombeado e como este será utilizada em pequenas propriedades rurais ou assentamentos, visando atender as diversas necessidades destas localidades, como irrigação de produtos hortigranjeiros, consumo humano, animal (bebedouro), entre outros.

The presented thesis deals with a numerical simulation of axially cooled glassmaking parison. Several types of cooling channels have been investigated according to its usage in glassmaking process. Software Star CCM+ was used to describe properties throughout the channels and also the parison itself. The main focus of this thesis lies in comparing of temperature fields, cooling effects and cooling intensity among the chosen channel designs. The boundary condi-tions were kept the same accordingly to glassmaking conditions for every design. Some out-puts were transferred to non-dimensional diagrams in order to recalculation pursuant to other boundary conditions. Properties of diffuser channel designs were compared to an experiment. Transient temperature field of the parison were calculated with Ansys APDL in order to de-termine the accumulation and stationary zone of the parison and to verify the boundary conditions for cooling channels.

This diploma thesis deals with the design and optimization of the device for measurement of field emission from gallium nitride (GaN) nanocrystals surface. The first part of the thesis is the topic review, which contains the introduction to the problematics of field emissio focused on GaN. Then there were designed, constructed and optimized two versions of the device for the measurement of field emission. Through the optimization phase, the first successful test has been performed with zinc oxide (ZnO) nanowires. Simultaneously GaN nanocrystals were fabricated on the silicon substrate Si(111) with 2 nm of silicon dioxide SiO2 and also on the copper foil covered by graphene by molecular beam epitaxy (MBE). In the last chapter, there are presented the results of the measurement for emission of GaN nanocrystals. Finally, this study is comparing results with the current research in the area of field emission, which displays the improved characteristics for field emission of GaN nanocrystals on the copper foil covered by graphene.

Diploma thesis deals with a research of the flow in front of three different automotive vents. The velocity field and intensity of the turbulence was measured in detail, using thermoanemometry. After that the same data was measured with PIV method and validation was performed. The difference between achieved data was investigated. The design among the vents was also investigated, because it’s fundamentally affects the air flow. The purpose of this thesis is to obtain data about the velocity field using two methods and their subsequent use to validate numerical simulations, which will be performed in the future. The diploma thesis also contains the calculation of measurement uncertainty.

Jednoduché dvojrozměrné anténní zářiče, které slouží jako stavební bloky anténních polí, jsou analyticky analyzovány v časové oblasti. Jako hlavní nástroj pro analýzu je použita Cagniard-DeHoopova metoda. Je ukázáno, že zvolený přístup umožňuje získat přesné vzorce v časové oblasti v uzavřeném tvaru, které jasně demonstrují vliv vstupních parametrů a objasňují fyzikální podstatu pulsního elektromagnetického vyzařování. Dané numerické výsledky ilustrují důležité aspekty pulsního elektromagnetického záření v rozličných konfiguracích problémů. Získané výsledky jsou užitečné pro efektivní návrh anténních polí, které jsou buzeny pulsními signály.

The aim of this thesis is to explain terms like light field, plenoptic camera or digital lens. Also the goal is to explain the principle of rendering the resulting images with the option to select the plane of focus, depth of field, changes in perspective and partial change in the angle of the point of view. The main outputs of this thesis are scripts for rendering images from Lytro camera and the interactive application, which clearly demonstrates the principles of plenoptic sensing.

The thesis is focused on comparison of several ways of the calculation of thermal and moisture fields in wood containing bound water during drying and their comparison with commonly used standards for wood drying processes. Each of the four models presents different way of the unsteady-state calculation of the coupled thermal and moisture field in wood. The first model describes linear simulation, other three models present nonlinear simulation using material coefficients dependent on temperature and moisture content, differing in the method of the thermodiffusion (Soret effect) coefficient settings. The aim of the thesis is to establish the influence of Soret effect on the wood drying process and to describe the difference between commonly used presumption of this process and its presumption given by the unsteady-state computation of the coupled thermal and moisture fields in wood.

Transmissibility is the most common metric used for isolator characterization. However, engineers are becoming increasingly concerned about energy transmission through an isolator at high frequencies and how the compliance of the machine and foundation factor into the performance. In this study, the transfer matrix approach for isolator characterization is first reviewed. Two methods are detailed for determining the transfer matrix of an isolator using finite element simulation. This is accomplished by determining either the mobility or impedance matrix for the isolator and then converting to a transfer matrix. One of the more useful metrics to characterize the high frequency performance of an isolator is insertion loss. Insertion loss is defined as the difference in transmitted vibration in decibels between the unisolated and isolated cases. Insertion loss takes into account the compliance on the source and receiver sides. Accordingly, it has some advantages over transmissibility which is a function of the damping and mounted resonant frequency. A static analysis is to preload the isolator so that stress stiffening is accounted for. This is followed by modal and forced response analyses to identify the transfer matrix of the isolator. In this paper, the insertion loss of spring isolators is examined as a function of several geometric parameters including the spring diameter, wire diameter, number of active coils, and height. Results demonstrate how modifications to these parameters affect the insertion loss and the first surge frequency.

The IceCube Neutrino Telescope is designed to detect high energy neutrinos with a large array of photomultiplier tubes placed deep within the Antarctic ice. The way that light propagates through the ice needs to be modelled accurately to enable the paths of charged particles to be reconstructed from the distribution of their Cerenkov radiation. Light travelling through even the purest of ice will undergo scattering and absorption processes, however the ice in which IceCube is embedded has optical properties that vary significantly with depth which need to be accurately modelled. Currently, simulation of the muon background using the current ice model is unable to fully replicate experimental data. In this thesis we investigate a potential method of improving on the current generation of ice models. We introduce thin, highly absorbing layers into the current description of the detection medium and investigate the effect on the simulation of muon tracks in IceCube. We find that better agreement between simulation and data can be seen in the occupancy of optical modules, through the introduction of such absorptive layers into the existing ice layers.