An enormous and urgent energy demand is predicted due to the growing global population, increase in power intensive industries, higher living standards, electrification of remote areas, and globalisation (transportation). Moreover, the global consciousness about the harmful effects of traditional methods of power generation on the environment. That, in turn, has created a need to strategically plan and develop renewable and sustainable energy generation systems. This study presents a wind resource assessment of seven locations proximate to the largest industrial hub in the Middle East, Jubail Industrial City, Kingdom of Saudi Arabia, and a Geographic Information System, GIS based model considering a multi-criteria wind farm site suitability approach for the entire Kingdom of Saudi Arabia and elsewhere. The hourly mean wind speed data at 10, 50 and 90 m above the ground level (AGL) over a period of five years was used for a meteorological station at the Industrial Area (Central) of Jubail. At the remaining six sites, the meteorological data were recorded at 10 m AGL only. Five years of wind data were used for five sites and three years of data were available for the remaining one site. At the Industrial Area (East), the mean wind speeds were found to be 3.34, 4.79 and 5.35 m/s at 10, 50 and 90 m AGL, respectively. At 50 and 90 m AGL, the availability of wind speed above 3.5 m/s was more than 75%. The local wind shear exponent, calculated using measured wind speed values at three heights, was found to be 0.217. The mean wind power density values at measurement heights were 50.92, 116.03 and 168.46 W/m2, respectively. After the assessment and comparison of wind characteristics of all seven sites, the highest annual mean wind speed of 4.52 m/s was observed at Industrial Area (East) and the lowest of 2.52 m/s at the Pearl Beach with standard deviations of 2.52 and 1.1 m/s, respectively. In general, at all sites, the highest monthly mean wind speed was observed in February/June and the lowest in September/October. The period of higher wind availability coincides with a high power demand period in the region attributable to the air conditioning load. The wind rose plots show that the prevailing wind direction for all sites was from the north-west. Weibull parameters for all sites were estimated using maximum likelihood, least-squares regression method (LSRM), and WAsP algorithm. In general, at all sites, the Weibull parameter, c, was the highest in the months of February/June and the lowest in the month of October. The most probable and maximum energy carrying wind speed was determined by all three methods. The highest value of most probable wind speed was found to be in the range of 3.2 m/s to 3.6 m/s at Industrial Area (East) and the highest value of maximum energy carrying wind speed was found to be in the range 8.6 m/s to 9.0 m/s at Industrial Area 2 (South) by three estimation methods. The correlation coefficient (R2), root mean square error (RMSE), mean bias error (MBE), and mean bias absolute error (MAE) showed that all three methods represent wind data at all sites accurately. However, the maximum likelihood method is slightly better than LSRM, followed by WAsP algorithm. The wind power output at all seven sites, from five commercially available wind turbines of rated power ranging from 1.8 to 3.3 MW, showed that Industrial Area (East) is most promising for wind farm development. At all sites, based on percentage plant capacity factor, PCF, the 1.8 MW wind turbine was found to be the most efficient. At Industrial Area (East), this wind turbine was found to have a maximum PCF of 41.8%, producing 6,589 MWh/year energy output. The second best wind turbine was 3 MW at all locations except the Al-Bahar Desalination Plant and Pearl Beach. At both of these locations, 3.3 MW was the next best option. The energy output from the 3 MW wind turbine at Industrial Area (East) was found to be 11,136 MWh/year with a PCF of 41.3%. The maximum duration of rated power output from all selected wind turbines was observed to be between 8 to 16.6% at Industrial Area 2 (South). The minimum duration of rated power output, less than 0.3% for all wind turbines, was observed at Pearl Beach. The maximum duration of zero power output of between 35 to 60% was also observed at Pearl Beach. / Thesis (PhD)--University of Pretoria, 2017. / Mechanical and Aeronautical Engineering / PhD / Unrestricted

Made available in DSpace on 2014-08-20T14:25:48Z (GMT). No. of bitstreams: 1 dissertacao_ana_carolina_pereira.pdf: 8965039 bytes, checksum: 94bb2b07c5b8788f73621ddfa4a752de (MD5) Previous issue date: 2008-12-18 / In this work a study of the winds in Rio Grande do Sul, during the period 2000-2007 is presented to identify where and when the wind were stronger in the State. The wind data obtained at 10m height, at three time observation (00, 12 and 18UTC) of 15 meteorological stations, well distributed in the State are utilized. The identification of the stations where the winds were stronger and with less spectrum of variation was made using a Weibull distribution to the monthly average values of velocity, calculated on the total period of data from each station (between 4 and 8 years) and for time. The similarity of velocities behavior between the stations with 8 years of data was obtained by applying the method K-means, non-hierarchical clustering technique, setting up 4 groups for homogeneous regions of pentad average velocities in the state, by hour of observation. Sensibility tests with two Planetary Boundary Layer (PBL) parameterizations (Blackadar and MRF) of MM5 model were realized by using two nested grids with 35 sigma levels in vertical, centered in Rio Grande do Sul and with initial and contour data from NCEP (1º resolution in latitude and longitude). The validation of simulated versus observed velocities at 10m height was realized with the calculation of bias error, the mean square root of error and standard deviation of errors. The cities of São Luiz Gonzaga and Santa Vitória do Palmar stood out from the others because they had more often high values of k and c parameters. The homogeneous group, characterized by having the highest values of pentadal avegared velocities was constitued predominantly by the stations of Santa Vitória do Palmar (in the extreme south of the state) and Passo Fundo (located in the northern region). The highest velocities were observed in the month of November, in Santa Vitória do Palmar. The selected case study was the extratropical cyclone that struck the southern Rio Grande do Sul in the period from 9 to November 13, 2002. The errors between observed and simulated velocities in both experiments were relatively large. The comparison between results and observed data in some stations showed that Blackadar PBL parameterization was better than MRF parameterization. / Neste trabalho é mostrado o estudo sobre os ventos no Rio Grande do Sul, durante o período 2000-2007, para identificar onde e quando os ventos foram mais intensos no Estado. Foram utilizados dados de velocidades obtidos a 10m de altura, nos três horários de observação (00, 12 e 18UTC) de 15 estações meteorológicas, bem distribuídas no Estado. A identificação das estações onde os ventos foram mais fortes e com menor espectro de variação foi feita aplicando a distribuição Weibull aos valores médios mensais de velocidades, calculadas sobre o período total de dados de cada estação (entre 4 e 8 anos) e por horário. A similaridade de comportamento das velocidades entre as estações com 8 anos de dados, foi obtida pela aplicação do método K-means, definindo-se 4 grupos para regiões homogêneas de velocidades médias pentadais no Estado, por horário de observação.Testes de sensibilidade com duas parametrizações (Blackadar e MRF) de Camada Limite Planetária (CLP) do modelo MM5 foram realizados usando duas grades aninhadas com 35 níveis sigma na vertical, centradas no Rio Grande do Sul e com dados iniciais e de contorno do NCEP (resolução de 1º em latitude e longitude). A validação das velocidades simuladas versus observadas, a 10m de altura, foi realizada com o cálculo do erro de viés, da raiz do erro quadrático médio e do desvio padrão dos erros. As cidades de São Luiz Gonzaga e de Santa Vitória do Palmar se destacaram das demais por apresentarem mais frequentemente, os valores mais elevados dos parâmetros k e c, respectivamente. O grupo homogêneo, caracterizado por apresentar os maiores valores de velocidades médias pentadais foi constituído predominantemente pelas estações de Santa Vitória do Palmar (no extremo sul do Estado) e Passo Fundo (localizado na região norte). As velocidades mais elevadas foram observadas no mês de novembro, em Santa Vitória do Palmar. O caso de estudo selecionado foi o ciclone extratropical que atingiu o sul do Rio Grande do Sul no período de 9 a 13 de novembro de 2002. Os erros encontrados entre as velocidades observadas e simuladas nos dois experimentos foram relativamente grandes. A comparação entre os resultados e os dados observados em algumas estações mostrou que a parametrização de camada limite planetária Blackadar foi melhor que a parametrização MRF.

Der Small-Punch-Test (SPT) ist eine vielversprechende minimalinvasive mechanische Prüfmethode, wenn nur sehr wenig Material für Proben zur Verfügung steht. Die vorliegende Arbeit hat das Ziel, aus Small-Punch-Kleinstproben wahre Materialparameter der elastisch-plastischen Verformung und des spröden Versagens zu bestimmen. Die Kraft-Verschiebungs-Kurve des Versuchs stellt die nichtlineare Materialantwort der inhomogen beanspruchten Probe dar. Das inverse Problem der Identifikation konstitutiver Materialparameter wird numerisch mit Hilfe von Finite-Elemente-Simulationen in Verbindung mit einem Response-Surface-Modell und nichtlinearer Optimierungsverfahren gelöst, indem die Abweichung zwischen gemessener und simulierter Kurve minimiert wird. Mit Hilfe einer eigens entwickelten Kühlapparatur wurden Versuche mit ferritischen Stählen von Raumtemperatur bis hinunter zu -191°C durchgeführt und die temperaturabhängigen Fließkurven identifiziert. Bei tiefen Temperaturen wurden die Weibull-Parameter der zufällig streuenden Sprödbruchfestigkeit bestimmt und die Bruchzähigkeitsverteilung durch Simulation einer CT-Probe vorhergesagt. Für eine Aluminiumoxidkeramik wurden ebenfalls die Weibull-Parameter bestimmt sowie mit Indenterrissen versehene Proben zur Abschätzung der Bruchzähigkeit verwendet. / The small punch test (SPT) is a promising minimally invasive material testing method, especially in cases where only small amounts of material are available. This thesis is aimed at identifying true material parameters of elastic-plastic deformation and brittle fracture. The load-displacement curve of the test represents the non-linear material response of the nonuniformly stressed specimen. The identification of material parameters of constitutive laws is an inverse problem, which is solved numerically. Finite element simulations together with a response surface model and nonlinear optimization techniques are applied to minimize the error between measured and simulated curves. A specially developed cooling apparatus was used to perform tests with ferritic steels from room temperature down to -191°C. The temperature dependent yield stresses and hardening curves were identified. At low temperatures the Weibull parameters of randomly distributed cleavage fracture strength were estimated. The fracture toughness distribution was then predicted by the help of a finite element simulation of a CT specimen. Furthermore the Weibull parameters of an alumina ceramic were determined and its fracture toughness was predicted using specimens prepared with indentation cracks.

Der Small-Punch-Test (SPT) ist eine vielversprechende minimalinvasive mechanische Prüfmethode, wenn nur sehr wenig Material für Proben zur Verfügung steht. Die vorliegende Arbeit hat das Ziel, aus Small-Punch-Kleinstproben wahre Materialparameter der elastisch-plastischen Verformung und des spröden Versagens zu bestimmen. Die Kraft-Verschiebungs-Kurve des Versuchs stellt die nichtlineare Materialantwort der inhomogen beanspruchten Probe dar. Das inverse Problem der Identifikation konstitutiver Materialparameter wird numerisch mit Hilfe von Finite-Elemente-Simulationen in Verbindung mit einem Response-Surface-Modell und nichtlinearer Optimierungsverfahren gelöst, indem die Abweichung zwischen gemessener und simulierter Kurve minimiert wird. Mit Hilfe einer eigens entwickelten Kühlapparatur wurden Versuche mit ferritischen Stählen von Raumtemperatur bis hinunter zu -191°C durchgeführt und die temperaturabhängigen Fließkurven identifiziert. Bei tiefen Temperaturen wurden die Weibull-Parameter der zufällig streuenden Sprödbruchfestigkeit bestimmt und die Bruchzähigkeitsverteilung durch Simulation einer CT-Probe vorhergesagt. Für eine Aluminiumoxidkeramik wurden ebenfalls die Weibull-Parameter bestimmt sowie mit Indenterrissen versehene Proben zur Abschätzung der Bruchzähigkeit verwendet. / The small punch test (SPT) is a promising minimally invasive material testing method, especially in cases where only small amounts of material are available. This thesis is aimed at identifying true material parameters of elastic-plastic deformation and brittle fracture. The load-displacement curve of the test represents the non-linear material response of the nonuniformly stressed specimen. The identification of material parameters of constitutive laws is an inverse problem, which is solved numerically. Finite element simulations together with a response surface model and nonlinear optimization techniques are applied to minimize the error between measured and simulated curves. A specially developed cooling apparatus was used to perform tests with ferritic steels from room temperature down to -191°C. The temperature dependent yield stresses and hardening curves were identified. At low temperatures the Weibull parameters of randomly distributed cleavage fracture strength were estimated. The fracture toughness distribution was then predicted by the help of a finite element simulation of a CT specimen. Furthermore the Weibull parameters of an alumina ceramic were determined and its fracture toughness was predicted using specimens prepared with indentation cracks.