<div>A new class of bladeless turbines was developed which allows for power extraction from harsh environments with minimal maintenance cost. This is achieved through a wavy hub surface that promotes shocks and expansion fans and hence generates torque besides trust if used as bottoming or topping cycle. </div><div>A numerical procedure to design, mesh, and model this new expansion device through steady and unsteady Reynolds Averaged Navier Stokes simulations is outlined. Then, the full three-dimensional flow field is replicated using a two-dimensional geometry to enable a simpler test section with full optical access at the Purdue Experimental Turbine Aerothermal Lab. Pressure, heat flux, and skin friction are computed via several measurement techniques to provide an accurate estimation of the uncertainties on the power, efficiency, and heat flux of the bladeless turbine. High-frequency pressure sensors (160 kHz) along with a high-frequency heat flux sensor (atomic layer thermopile) are used to characterize the unsteady phenomena on the hub and the shroud. Unsteadiness in the flow field is assessed through 10 kHz shadowgraph, density gradients are quantitatively assessed via 3 kHz Background Oriented Schlieren, and unsteady velocity components and flow angles are characterized with 1 kHz Femtosecond Laser Electronic Excitation Tagging. A reduced order model is constructed with Spectral Proper Orthogonal Decomposition to retrieve the dominant frequencies in the flow field, which could be associated with a multitude of shock-boundary layer, shock-shock, and shock-shear layer interactions.</div><div>A parametric study and multi-objective optimization to maximize power extraction while minimizing pressure loss and heat flux are performed. The operational envelope and scaling of the bladeless turbine are described for several reduced mass flows, reduced speeds, and swirl angles. Based on all the gathered simulations, a guideline for the design of bladeless turbines is provided.</div><div><br></div><div>Finally, the operation of the bladeless turbine is analyzed considering the unsteady propagation of a rotating oblique shock throughout the passage. Non-dimensional parameters to generically describe rotating shocks are discussed, and their influence on the operation of the turbine is assessed. Correction terms for the power and pressure loss during the unsteady operation of the bladeless turbine are developed with results of this section.</div><div><br></div>

The decreasing availability of fossil fuels and their negative environmental impacts requires urgent need of developing renewable energy. The main objective of this research was to develop low-dimensional nanomaterials for harvesting solar and mechanical energy with high conversion efficiency. In particular, photoelectrochemical water splitting and photovoltaic cell applications driven by sunlight were investigated in this project. A highly efficient triboelectric nanogenerator was investigated for harvesting mechanical energy. The device was further integrated with an organic solar cell for harvesting both mechanical energy and solar energy. My research work started with the synthesis of nanostructured materials. Electrospinning, as well as electrospray, was developed to synthesise nanofibres and hollow hemispheres. The influences of processing parameters to the morphologies and structures of the nanomaterials were systematically investigated. An electrophoretic deposition method was also developed to form good-quality nanostructured metal oxide thin films, which were applied in photoelectrochemical water splitting. The metal oxide hollow hemisphere thin films were also applied in dye-sensitised solar cells. A transparent and flexible triboelectric nanogenerator was developed in order to harvest mechanical energy. The contact electrodes were created using metal nanowire percolation networks embedded in a polymer matrix. The correlation between the energy conversion performances and optical property of the triboelectric electrodes were comprehensively studied as a function of the areal fraction of the metal nanowires. A flexible hybrid cell, integrating the solar cell with the triboelectric device, was designed by constructing an organic solar cell under a single-electrode triboelectric nanogenerator. The hybrid cell could convert both solar and mechanical energies into electricity independently and simultaneously. Such devices are potentially able to supply electricity day and night. Nanomaterials offer novel approaches for enhancing the efficiency of harvesting solar and mechanical energy in a hybrid device.

A number of alternative economic and economic geography theories have been developed to account for the divergence of national political economy and industrial dynamics. These include the varieties of capitalism, developmental state, neo-Schumpeterian innovation, and Gerschenkronian catching-up theories. In this thesis I shall argue that in these theories a core and often shared concept of "institutional advantage" plays a central role in explaining different economic performances across nations. This concept is elaborated as a means of examining the causal relationships between institutional advantages and four necessary functions (market creation, capital mobilisation, process innovation and cost reduction) in the development of the photovoltaic (PV) industry of Germany, China, and South Korea. The development of these industries is examined in detail on the basis of empirical evidence in the form of archival and interview based data. Two main conclusions are reached. Firstly, domestic market creation is not a generally necessary condition for the development of a local PV industry at a national level. China's PV industry grew fast without a sufficient domestic market unlike in Germany. However, domestic market creation is important, because the domestic PV industry, national support policy and the domestic market are interrelated. Secondly, capital mobilisation is a core function in establishing the PV industry. In the 2000s, Korea failed to establish its local PV industry despite an institutional advantage in creating domestic markets, mainly due to the fact that it had an institutional disadvantage in mobilising capital. However, Germany and China succeeded in mobilising capital in their PV sectors, governments playing a decisive role in facilitating the raising of funds in both cases. This research contributes to a better understanding of the nature of industrial dynamics in the context of institutional configurations of a national political economy, broadening the usage of "institutional advantage" by applying this concept to comparative analysis on the national PV trajectories. Moreover, from the perspective of the social system, four necessary functions for the PV industry have been proposed and investigated.

Design and implementation of TCR (Thyristor Controlled Reactor) for industrial SVC (Static VAr Compensator) systems require special design. Both power stage and control system design and implementation are thoroughly investigated in this thesis. Engineering aspects of TCR design are emphasized and supported with case studies. As the first case study / a novel, unified and relocatable SVC for open cast lignite mining in Turkey is designed, implemented and commissioned. The second case study is the first 12 pulse TCR design and implementation for ladle furnace compensation in the world. The SVC simulation results are verified by data acquired in the field. Real time data are also simulated in EMTDC/PSCAD program to verify the control system responses of the commissioned systems.

This thesis deals with the problem of hydrogen explosions in nuclear power plants, and evaluates if the reactor hall is to be seen as a safety barrier for such events. Today, the reactor hall is not seen as a safety barrier that is able to withstand an internal explosion. In the analysis Abaqus was used for the FEM calculations, where a main scenario of a wall subjected to a hydrogen explosion was used. In conclusion, the results showed that a reactor hall with the assumed dimensions cannot be seen as a safety barrier, since the deformation after a hydrogen explosion near the LEL was too great. However, it is also concluded that with increased wall and rebar dimensions it is possible to construct a wall of this kind that fulfills the requirements of a safety barrier.

Creating a diverse and flexible energy system to ensure security of supply is at the heart of UK energy policy. However, despite the apparent interest in the idea of securing supply in this way and the term ‘diversity' becoming more frequently used in this context in government White Papers, policy discourse and the academic literature relatively little attention has been given to exploring what diversity means, how it can be measured, what contribution it can make to different policy objectives and the specific implications for the UK electricity system. Furthermore CCS technologies which are becoming increasingly important to decarbonisation of the power sector in order to meet legally binding greenhouse gas targets set out in the Climate Change Act which raises the question, what are the potential impacts of these technologies on the diversity of the future UK electricity system? To answer this question a mixed methodology of quantitative energy-economic modelling (using MARKAL), scenario analysis and diversity analysis is combined with qualitative semi-structured stakeholder interviews. Data analysis is carried out in two parts. The first assesses the diversity (with a specific focus on the effect of different input assumptions on CCS technologies) of the scenarios generated using Stirling's Diversity Heuristic and creates a set of ‘diversity profiles' which map changes in diversity across each scenario. The second part uses stakeholder perspectives to inform the quantification of diversity across the same set of scenarios providing evidence of the impact of different stakeholder perspectives on the overall diversity of the electricity system.

ABSTRACT SENSORLESS DIRECT FIELD ORIENTED CONTROL OF INDUCTION MACHINE BY FLUX AND SPEED ESTIMATORS USING MODEL REFERENCE ADAPTIVE SYSTEM This work focuses on an observer design which will estimate flux-linkage and speed for induction motors in its entire speed control range. The theoretical base of the algorithm is explained in detail and its both open-loop, and closed-loop performance is tested with experiments, measuring only stator current and voltage. Theoretically, the field-oriented control for the induction motor drive can be mainly categorized into two types / indirect and direct field oriented. The field to be oriented may be rotor, stator, or airgap flux-linkage. In the indirect field-oriented control, the slip estimation based on the measured or estimated rotor speed is required in order to compute the synchronous speed. There is no need for the flux estimation in such a system. For the direct field oriented case the synchronous speed is computed with the aid of a flux estimator. In DFO, the synchronous speed is iv computed from the ratio of dq-axes fluxes. With the combination of a flux estimator and an open-loop speed estimator one can observe stator-rotor fluxes, rotor-flux angle and rotor speed. In this study, the direct (rotor) flux oriented control system with flux and-open-loop speed estimators is described and tested in real-time with the Evaluation Module named TMS320LF21407 and the Embedded Target software named Vissim from Visual Solutions Company.

Theme Master’s thesis was studying of wind energy power supply. Comparison of character of wind power supply in Czech Republic to power supply abroad. Thesis begins with short introduction of historical wind applications. It continues by theory of wind engines, the wind engines construction and its facilities. Next part describes wind energy characteristics and physics. It describes wind speed influence to power supply of wind turbine, a physical limits of wind engines efficiency. Later, meteorological forecast possibilities are mentioned. Following chapter classifies wind power plants by geographical locations and characterizes them. It presents and explains individual cases of wind energy business growth in Czech Republic and other countries. There are also mentioned many suitable locations for wind parks in Czech Republic. There are described data analysis methods in chapter number 5. Analysis results of day period graph and year period graphs are shown. Unsophisticated forecast model is sketched out and created in following chapter. Here the regressive analysis methods are described, such as Autoregressive moving average model (ARMA), which can bring satisfactory results. Another example is Markov switching autoregressive model (MSAR). Next step from statistic forecast models is to sophisticated large forecasting systems. Those systems require meteorological forecast data and historical wind power data. Data are analyzed by statistical models. They have been developed recently and they are ordinary used nowadays.

Technological improvements on wind energy systems with governmental supports have increased the penetration level of wind power into the grid in recent years. The high level of penetration forces the wind turbines stay connected to the grid during the disturbances in order to enhance system stability. Moreover, power system operators must revise their grid codes in parallel with these developments. This work is devoted to the modeling of variable speed wind turbines and the investigation of fault ride trough capability of the wind turbines for grid integration studies. In the thesis, detailed models of different variable speed wind turbines will be presented. Requirements of grid codes for wind power integration will also be discussed regarding active power control, reactive power control and fault ride through (FRT) capability. Investigation of the wind turbine FRT capability is the main focus of this thesis. Methods to overcome this problem for different types of wind turbines will be also explained in detail. Models of grid-connected wind turbines with doubly-fed induction generator and permanent magnet synchronous generator are implemented in the dedicated power system analysis tool PSCAD/EMTDC. With these models and computer simulations, FRT capabilities ofvariable speed wind turbines have been studied and benchmarked and the influences on the grid during the faults are discussed.

In this thesis, control schemes for the self-excited induction generator are developed with Matlab/Simulink. Self-excited induction generator is considered as a constant voltage-constant frequency supply for an isolated load. A wind turbine is assumed to be the variable-speed drive of the induction generator. Control schemes aim to ensure a constant voltage-constant frequency operation of the induction generator in case of the variations in the wind speed and/or the load. From the general model of the self-excited induction generator, the characteristics of the system and the dynamic responses of the system in case of any disturbance are examined. Next, the control strategies are developed both for the squirrel-cage rotor induction generator and for the wound-rotor induction generator. Two control loops are necessary for constant voltage-constant frequency operation of a variable speed induction generator, one for the voltage regulation and the other for the frequency regulation. After developing the control loops, constant voltage-constant frequency operation of the self-excited induction generator is simulated with a cage type saturation adaptive induction generator, a fixed capacitor with thyristor controlled reactor (TCR) used for frequency regulation and switched external resistors connected to the stator terminals used for voltage regulation.