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Basée sur un vaste corpus d’œuvres en quartzite, axé sur la statuaire mais prenant aussi en compte d’autres types de monuments, l’étude vise à examiner l’utilisation de cette pierre dure par les anciens Égyptiens au Nouvel Empire, sous les XVIIIe et XIXe dynasties. Correspondant à du grès silicifié, le quartzite a été extrait du Gebel el-Ahmar au nord et des carrières d’Assouan au sud. Après avoir évoqué les caractéristiques géologiques du quartzite et sa désignation dans les anciens textes égyptiens, l’étude traite du travail dans les carrières du point de vue de son organisation et de ses aspects techniques (méthodes d’extraction, outils employés, ébauches in situ), avant d’envisager la question du transport et de la finition dans les ateliers de sculpteurs. La seconde partie, introduite par un chapitre sur l’usage du quartzite avant le Nouvel Empire, est consacrée à l’examen des œuvres du corpus replacées dans leur contexte : il permet de mettre en évidence l’essor de ce matériau au cours de la XVIIIe dynastie, avec une utilisation majeure sous les règnes d’Amenhotep III et d’Akhénaton, fortement marqués par les conceptions solaires, et un nouveau regain sous Séthi Ier, notamment à Héliopolis, et sous Ramsès II qui a cherché à imiter son prédécesseur Amenhotep III. La symbolique solaire du quartzite, due à sa couleur rouge et à l’origine mythique du Gebel el-Ahmar, explique en grande partie son emploi dans les monuments royaux et divins et en fait une pierre de prestige, presque exclusivement réservée à l’élite. Les résultats d’analyses scientifiques menées sur des objets en quartzite du musée du Louvre sont annexés au travail. / Based on a large corpus of works made of quartzite, centred on statuary but also taking into account other types of monuments, the present study is a review of this hard stone use by the ancient Egyptians during New Kingdom, mainly 18th and 19th dynasties. Quartzite or silicified sandstone was extracted from Gebel el-Ahmar quarries in the North and from Aswan quarries in the South. Having mentioned the geologic characteristics of quartzite and its name in the ancient Egyptian texts, the study deals with the work in the quarries (organization and technical aspects like extraction technologies, tools, rough or unfinished pieces found in situ) and the transport of the stone from the quarry to the workshop. The second part of the research, introduced by a chapter on quartzite use before New Kingdom, is dedicated to the monuments of the catalogue put in their context : their examination reveals the significant development of this material during the 18th dynasty, with a peak under the reigns of Amenhotep III and Akhenaton, heavily influenced by solar beliefs, and a revival under Seti Ist (especially in Heliopolis) and Ramesses II, who wanted to emulate his predecessor Amenhotep III. The use of quartzite in royal and divine monuments might be explained by its solar symbolism, due to the red colour of the stone and the mythical origin of the Gebel el-Ahmar : it is the reason why this high-value stone is almost exclusively reserved for the Egyptian elite. An appendix containing the results from scientific analysis conducted on some quartzite objects kept in the Louvre Museum completes the study.

The demand for high power density keeps driving the development of electromagnetic integration technologies in the field of power electronics. Based on planar homogeneous integrated structures, the mechanism of the electromagnetic integration of passives has been investigated with distributed-parameter models. High order modeling of integrated passives has been developed to investigate the electromagnetic performance. The design algorithm combining electromagnetic design and loss models has been developed to optimize and evaluate the spiral winding structure. High power density of 480 W/in3 has been obtained on the prototype. Due to the structural limitation, the currently applied planar spiral winding structure does not sufficiently utilize the space, and the structure is mechanically vulnerable. The improvement on structures is necessary for further application of integrated passives. The goal of this research is to investigate and evaluate alternative structures for high-power-density integrated passives. The research covers electromagnetic modeling, constructional study, design algorithm, loss modeling, thermal management and implementation technology The symmetric single layer structure and the stacked structure are proposed to overcome the disadvantages of the currently applied planar spiral winding structure. Because of the potential of high power density and low power loss, the stacked structure is selected for further research. The structural characteristics and the processing technologies are addressed. By taking an integrated LLCT module as the study case, the general design algorithm is developed to find out a set of feasible designs. The obtained design maps are used to evaluate the constraints from spatial, materials and processing technologies for the stacked structure. Based on the assumption of one-dimensional magnetic filed on the cross-section and linear current distribution along the longitudinal direction of the stacked structure, the electromagnetic field distribution is analyzed and the loss modeling is made. The experimental method is proposed to measure the loss and to verify the calculation. The power loss in the module leads to thermal issues, which limit the processed power of power electronics modules and thus limit the power density. To further improve the power handling ability of the module, the thermal management is made based on loss estimation. The heat extraction technology is developed to improve the heat removal ability and further improve the power density of integrated passives. The experimental results verify the power density improvement from the proposed stacked structure and the applied heat extraction technology. The power density of 1147 W/in3 (70 W/cm3) is achieved in the implemented LLCT module with the efficiency of 97.8% at output power of 1008W. / Ph. D.

O presente trabalho teve por objetivo apresentar e discutir um caso de identificação e remediação emergencial de compostos orgânicos voláteis, oclusos em camada arenosa do Terciário da Formação São Paulo, em decorrência do vazamento de tanques de combustíveis de um posto de serviços. A técnica de remediação adotada para o caso consistiu na extração in situ dos vapores do solo e no tratamento dos mesmos por adsorção em filtros de carvão ativado (SVE - soil vapor extraction). Os processos de seleção, projeto, implantação, operação e descomissionamento da tecnologia SVE seguiram as metodologias indicadas pela literatura, adaptadas às condições locais. O acompanhamento da eficiência da remediação foi baseado na quantificação inicial dos hidrocarbonetos totais de petróleo leves presentes no subsolo, através das técnicas de cromatografia gasosa e espectrometria de massa, e na medição em campo das concentrações de voláteis e dos respectivos teores de explosividade. O resultado da campanha laboratorial apresentou fortes indícios de que a contaminação local fosse proveniente do combustível gasolina e indicou a ocorrência do composto benzeno em concentrações superiores aos limites adotados como referência. As leituras realizadas em campo mostraram rápido declínio das concentrações de voláteis e dos teores de explosividade com a operação da tecnologia SVE, indicando baixa ocorrência de fatores limitantes do transporte de massa no local. Corroborou com tal hipótese, o fato das metas de remediação terem sido atingidas com poucas trocas de ar, parâmetro retro-analisado a partir de dados de ensaios geológico-geotécnicos. Assim, concluiu-se que, para áreas com características semelhantes à estudada, a tecnologia SVE pode ser eficiente como medida de remediação de voláteis e redução dos riscos de explosividade. / This work aims to present and to discuss a case study of identification and emergency remediation of volatile organic compounds, occluded in a sand layer of the São Paulo Tertiary Formation, as a result of the leakage of fuel tanks of a service station. The adopted remediation technique was in situ soil vapor extraction (SVE) and offgas treatment for adsorption in activated carbon filters. Selection, design, commissioning, operation and shutdown processes of SVE technology followed literature methodologies, which were adapted to local conditions. Remediation efficiency monitoring was based on the initial quantification of light total petroleum hydrocarbons in the subsoil, through gas chromatography and mass spectrometry techniques, and on measurement of the volatile concentrations and respective explosive contents in the field. The result of the laboratorial campaign presented strong indications that the local contamination proceeded from combustible gasoline and it indicated the occurrence of benzene in concentrations higher than the adopted reference. Field measurements showed fast decline of the volatile concentrations and explosive contents with the SVE technology operation, fact that indicated low occurrence of mass transfer limitations in the place. The fact that remediation goals were achieved with few air exchanges, parameter back-analyzed from geologicgeotechnical tests, contributed to reinforce such hypothesis. Thus, SVE technique can be considered efficient for volatile remediation and explosive risks reduction, for areas with characteristics similar to the studied one.

O presente trabalho teve por objetivo apresentar e discutir um caso de identificação e remediação emergencial de compostos orgânicos voláteis, oclusos em camada arenosa do Terciário da Formação São Paulo, em decorrência do vazamento de tanques de combustíveis de um posto de serviços. A técnica de remediação adotada para o caso consistiu na extração in situ dos vapores do solo e no tratamento dos mesmos por adsorção em filtros de carvão ativado (SVE - soil vapor extraction). Os processos de seleção, projeto, implantação, operação e descomissionamento da tecnologia SVE seguiram as metodologias indicadas pela literatura, adaptadas às condições locais. O acompanhamento da eficiência da remediação foi baseado na quantificação inicial dos hidrocarbonetos totais de petróleo leves presentes no subsolo, através das técnicas de cromatografia gasosa e espectrometria de massa, e na medição em campo das concentrações de voláteis e dos respectivos teores de explosividade. O resultado da campanha laboratorial apresentou fortes indícios de que a contaminação local fosse proveniente do combustível gasolina e indicou a ocorrência do composto benzeno em concentrações superiores aos limites adotados como referência. As leituras realizadas em campo mostraram rápido declínio das concentrações de voláteis e dos teores de explosividade com a operação da tecnologia SVE, indicando baixa ocorrência de fatores limitantes do transporte de massa no local. Corroborou com tal hipótese, o fato das metas de remediação terem sido atingidas com poucas trocas de ar, parâmetro retro-analisado a partir de dados de ensaios geológico-geotécnicos. Assim, concluiu-se que, para áreas com características semelhantes à estudada, a tecnologia SVE pode ser eficiente como medida de remediação de voláteis e redução dos riscos de explosividade. / This work aims to present and to discuss a case study of identification and emergency remediation of volatile organic compounds, occluded in a sand layer of the São Paulo Tertiary Formation, as a result of the leakage of fuel tanks of a service station. The adopted remediation technique was in situ soil vapor extraction (SVE) and offgas treatment for adsorption in activated carbon filters. Selection, design, commissioning, operation and shutdown processes of SVE technology followed literature methodologies, which were adapted to local conditions. Remediation efficiency monitoring was based on the initial quantification of light total petroleum hydrocarbons in the subsoil, through gas chromatography and mass spectrometry techniques, and on measurement of the volatile concentrations and respective explosive contents in the field. The result of the laboratorial campaign presented strong indications that the local contamination proceeded from combustible gasoline and it indicated the occurrence of benzene in concentrations higher than the adopted reference. Field measurements showed fast decline of the volatile concentrations and explosive contents with the SVE technology operation, fact that indicated low occurrence of mass transfer limitations in the place. The fact that remediation goals were achieved with few air exchanges, parameter back-analyzed from geologicgeotechnical tests, contributed to reinforce such hypothesis. Thus, SVE technique can be considered efficient for volatile remediation and explosive risks reduction, for areas with characteristics similar to the studied one.

The Nigeria economy is wholly dependent on revenue from oil. However, bitumen has been discovered in the country since 1903 and has remained untapped over the years. The need for the country to complement oil exploration with the huge bitumen deposit cannot be overemphasized. This will help to improve the country's gross domestic product (GDP) and revenue available to government. Bitumen is classifled as heavy crude with API (American petroleum Institute) number ranging between 50 and 110 and occurs in Nigeria, Canada, Saudi Arabia, Venezuela etc from which petroleum products could be derived. This dissertation looked at the Canadian experience by comparing the oil and tar sand deposit found in Canada with particular reference to Athabasca (Grosmont, Wabiskaw McMurray and Nsiku) with that in Nigeria with a view of transferring process technology from Canada to Nigeria. The Nigeria and Athabasca tar sands occur in the same type of environment. These are the deltaic, fluvial marine deposit in an incised valley with similar reservoir, chemical and physical properties. However, the Nigeria tar sand is more asphaltenic and also contains more resin and as such will yield more product volume during hydro cracking albeit more acidic. The differences in the components (viscosity, resin and asphaltenes contents, sulphur and heavy metal contents) of the tar sands is within the limit of technology adaptation. Any of the technologies used in Athabasca, Canada is adaptable to Nigeria according to the findings of this research. The techno-economics of some of the process technologies are. x-rayed using the PTAC (petroleum technology alliance Canada) technology recovery model in order to obtain their unit cost for Nigeria bitumen. The unit cost of processed bitumen adopting steam assisted gravity drainage (SAGD), in situ combustion (ISC) and cyclic steam stimulation (CSS) process technology is 40.59, 25.00 and 44.14 Canadian dollars respectively. The unit cost in Canada using the same process technology is 57.27, 25.00 and 61.33 Canadian dollars respectively. The unit cost in Nigeria is substantively lesser than in Canada. A trade off is thereafter done using life cycle costing so as to select the best process technology for the Nigeria oil/tar sands. The net present value/internal rate of return is found to be B$3,062/36.35% for steam assisted gravity drainage, B$I,570124.51 % for cyclic steam stimulation and B$3,503/39.64% for in situ combustion. Though in situ combustion returned the highest net present value and internal rate of return, it proved not to be the best option for Nigeria due to environmental concern and response time to production. The best viable option for the Nigeria tar sand was then deemed to be steam assisted gravity drainage. An integrated oil strategy coupled with cogeneration using MSAR was also seen to considerably amplify the benefits accruable from bitumen exploration; therefore, an investment in bitumen exploration in Nigeria is a wise economic decision. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2010.

The Nigeria economy is wholly dependent on revenue from oil. However, bitumen has been discovered in the country since 1903 and has remained untapped over the years. The need for the country to complement oil exploration with the huge bitumen deposit cannot be overemphasized. This will help to improve the country's gross domestic product (GDP) and revenue available to government. Bitumen is classifled as heavy crude with API (American petroleum Institute) number ranging between 50 and 110 and occurs in Nigeria, Canada, Saudi Arabia, Venezuela etc from which petroleum products could be derived. This dissertation looked at the Canadian experience by comparing the oil and tar sand deposit found in Canada with particular reference to Athabasca (Grosmont, Wabiskaw McMurray and Nsiku) with that in Nigeria with a view of transferring process technology from Canada to Nigeria. The Nigeria and Athabasca tar sands occur in the same type of environment. These are the deltaic, fluvial marine deposit in an incised valley with similar reservoir, chemical and physical properties. However, the Nigeria tar sand is more asphaltenic and also contains more resin and as such will yield more product volume during hydro cracking albeit more acidic. The differences in the components (viscosity, resin and asphaltenes contents, sulphur and heavy metal contents) of the tar sands is within the limit of technology adaptation. Any of the technologies used in Athabasca, Canada is adaptable to Nigeria according to the findings of this research. The techno-economics of some of the process technologies are. x-rayed using the PTAC (petroleum technology alliance Canada) technology recovery model in order to obtain their unit cost for Nigeria bitumen. The unit cost of processed bitumen adopting steam assisted gravity drainage (SAGD), in situ combustion (ISC) and cyclic steam stimulation (CSS) process technology is 40.59, 25.00 and 44.14 Canadian dollars respectively. The unit cost in Canada using the same process technology is 57.27, 25.00 and 61.33 Canadian dollars respectively. The unit cost in Nigeria is substantively lesser than in Canada. A trade off is thereafter done using life cycle costing so as to select the best process technology for the Nigeria oil/tar sands. The net present value/internal rate of return is found to be B$3,062/36.35% for steam assisted gravity drainage, B$I,570124.51 % for cyclic steam stimulation and B$3,503/39.64% for in situ combustion. Though in situ combustion returned the highest net present value and internal rate of return, it proved not to be the best option for Nigeria due to environmental concern and response time to production. The best viable option for the Nigeria tar sand was then deemed to be steam assisted gravity drainage. An integrated oil strategy coupled with cogeneration using MSAR was also seen to considerably amplify the benefits accruable from bitumen exploration; therefore, an investment in bitumen exploration in Nigeria is a wise economic decision. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2010.