Time-to-digital converters (TDC) are widely used in light-detection-and-ranging (LIDAR) systems to measure the time-of-flight. Conventional TDCs are sensitivity to process, voltage, and temperature (PVT) variations. Recent work utilizing the stochastic delay-line TDC architecture has demonstrated excellent robustness against PVT variations. But important issues affecting the linearity of a stochastic delay-line TDC has yet to be recognized and addressed.This thesis rigorously analyzes the problem of linearity of a stochastic delay-line TDC and formulates an intuitive theory to predict the linearity performance. Apolarvisualization of the phase distribution of a delay line is proposed to aid the analysis. Based on the results of this study, this thesis proposes a stochastic delay-line TDC employing a delay-locked loop (DLL) to guarantee linearity over PVT variations and to reduce the number of redundant bits. The proposed TDC is implemented in a 0.18 µm CMOS process to validate the linearity theory and the proposed solution. The 8-bit TDC samples at 60 MHz and demonstrates a linear-number-of-bit of 6.36 with only 2-bit redundancy. Consuming 25 mW from a 1.8 V supply, the TDC yields a figure-of-merit of 5.04 pJ/conversion-step. With the DLL turned off, the integral nonlinearity (INL) degrades by about a factor of two, verifying the effectiveness of the proposed solution. The TDC is measured at different temperatures and supply voltages to demonstrate robustness against PVT variations. The measurement results show excellent agreement with the behavioral simulations.

Photovoltaic thermal (PVT) collectors are widely used to harness a large fraction of the solar spectrum to generate electricity and heat from a single collector. The circulation of the working medium will pass through the collector which cools down the PV cell temperature and also increases the water temperature, which will increase the electrical and thermal performance at the same time. PVT is an emerging technology and is demonstrated for domestic and industrial applications. There has also been a major gap for the techno-economic analysis of PVT system in different climatic conditions and further developing reliable financial models that can be applied in different regions. This thesis paper presents a techno-economic evaluation of a liquid-based PVT collector system developed by Abora Solar, Spain across a wide range of climatic conditions and contexts. The various performance indicators are visualized by digital mapping approach for 86 different locations all over the world. The databank obtained from the analysis is further used to establish a general correlation between collector performance and meteorological parameters such as Global horizontal irradiation and ambient temperature. The collector energetic performance is simulated using a validated and proprietary simulation tool developed by Abora Solar company. The complete energy system consists of a PVT collector, a water storage tank, and the associated DHW demand simulator. The collector energetic performance has reflected following the analysed Global horizontal irradiation and ambient temperature trend. The highest and lowest energy utilization ratio of the collector has been recorded in Reykjavik, Iceland (63%) and Medina, Saudi Arabia (54%) respectively. The highest and lowest exergetic efficiency of the collector has been recorded in Reykjavik, Iceland (23%) and Medina, Saudi Arabia (17%) respectively. The exergetic efficiency collector has shown better performance with the less ambient temperature and less quality of work in high ambient temperatures. Furthermore, the energy utilization ratio and exergetic efficiencies of collector production are analysed. The economic analysis is carried out in realistic approach using two different financial scenarios: mode (1) The total system cost is capital investment in the first year; mode (2) Only 25 % of total system cost is a capital investment and remaining 75 % investment is considered with financing period with certain interest rate. The economic performance of the collector has been decided mainly based on the Net Present Value per unit collector area, whereas it expressed high dependency on thermal energy savings. The average NPV per unit collector area of 86 geographical cities for first financial model 1 and financial model 2 are 1886€ and 2221€ respectively. Besides, the Payback Period has also been estimated for the first financing model in all selected locations. The first financial model (1) has shown better results in locations with a high interest rate and highly recommended for the locations with interest rate. The significant work of understanding of PVT components behaviour at the system level, the collector energetic and economic performance at different climatic conditions across the world have been highlighted which reflects the concrete developments to this research subject area and helps market decision-makers for market penetration.

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The rise in population causes serious issues in larger cities since the electrical grid is becoming overloaded. Simultaneously, the demand on more sustainable energy production and the use of renewable energy sources increase. Renewable energy based off-grid electrical systems are a possible solution to decrease the magnitude of these issues. The purpose of this thesis is to compare solar cells, solar thermal collectors and PVT (Photovoltaic thermal hybrid solar collectors) and design the most suitable combination of solar panels for a selfsufficient multi-family house in Jönköping, Sweden. The solar panels were compared from a cost and energy production perspective, then a suitable renewable energy system with all three types of panels was constructed and optimized using Opti-CE, which is a MATLABbased software. During the course of this thesis, an interview was made with Hans-Olof Nilsson who is a co-founder of Nilsson Energy and owner of a self-sufficient off-grid house. The results show that PVT-panels have higher energy production per area and 22% higher LCC (life cycle cost) than regular solar cells in combination with solar thermal collectors. Optimization results indicate that the house cannot be self-sufficient by installing solar panels on the given roof area only, rather the area of installed solar collectors should be increased to a minimum of 1497𝑚2 . With the given roof area of 900𝑚2 the house can only be self-sufficient a maximum of 75% of the time. The results also indicate that the introduction of compact systems with the simultaneous decrease of cost will make renewable off-grid energy systems more attractive in the future.

[pt] O crescente uso de modelos integrados de produção (MIP) na indústria de petróleo como solução para representar o potencial de uma jazida se justifica pelos atuais cenários encontrados para o desenvolvimento de novos projetos, caracterizado por baixos preços de venda do petróleo e conceitos de produção de alta complexidade. Esta abordagem, em que diferentes partes de um sistema de produção são integradas, permite ao usuário um entendimento detalhado das interações entre reservatório, poços e rede de escoamento, e facilita a detecção de gargalos e consequentemente a otimização do plano de explotação. Neste contexto, é fundamental obter uma modelagem satisfatória do fluido em todo o sistema de produção. O modelo deve honrar tanto o escoamento no meio poroso, isotérmico, quanto o escoamento nos poços e dutos, que precisa ser caracterizado em várias temperaturas. Além disso, o modelo deve ter tempo de simulação adequado. Uma maneira criteriosa de modelar as propriedades de um fluido é através do ajuste de uma equação de estado (EOS). Uma EOS detalhada com 24 componentes determinada por cromatografia gasosa e EOS simplificadas com 14, 9, 7, 6, 5 e 4 pseudocomponentes foram geradas para avaliar este problema. As EOS foram usadas para representar as propriedades PVT em um MIP e ao final foram comparadas as respostas das EOS simplificadas e detalhadas, a fim de estabelecer resultados adequados com um tempo computacional adequado. Os resultados obtidos mostram que o uso de EOS excessivamente simplificadas, apesar da melhoria no tempo computacional, podem gerar resultados insatisfatórios em modelos integrados de produção. / [en] The growing use of integrated production models (IPM) in the oil industry as a solution to represent the potential of a field is justified by the current scenarios found for the development of new projects, characterized by low oil prices and high complexity production concepts. This approach, where different parts of a production system are integrated, allows the user to have a detailed understanding of the interactions between reservoir, wells and gathering system, and facilitates the detection of bottlenecks and consequently the optimization of the exploitation plan. In this context, it is essential to obtain a satisfactory fluid model in the entire production system. The model must honor both the flow in the porous media, isothermal, and the flow in the wells and pipelines, which must be characterized at various temperatures. In addition, the model must have adequate simulation time. A rigorous way to model the properties of a fluid is by adjusting an equation of state (EOS). A detailed EOS with 24 components determined by gas chromatography and simplified EOS with 14, 9, 7, 6, 5 and 4 pseudocomponents were generated to evaluate this problem. The EOS were used to represent the PVT properties in a IPM and the responses of the simplified and detailed EOS were compared, in order to establish an adequate results with an adequate computational time. The results obtained show that the use of excessively simplified EOS, despite the improvement in computational time, can generate unsatisfactory results in integrated production models.

In Photovoltaic/Thermal (PVT) technology, both PV and solar thermal technology are integrated in the same module for simultaneous electricity and heat production. Research has shown that there are multiple benefits from integrating PVT collectors with a ground source heat pump (GSHP) system, since it allows for seasonal storage of thermal energy over the year. Furthermore, it leads to reduced operating temperatures for the PVT collectors which can increase efficiency and lifetime. The aim of this study is to present the electric and thermal performance of a PVT collector developed by Solhybrid i Småland AB, for different environmental and fluid inlet conditions that can occur when PVT collectors are connected to a GSHP system. Furthermore, the performance of this PVT design is evaluated with ASHRAE (Standard 93-2003), to allow for comparison with other PVT collector designs, with values on the overall heat loss coefficient (UL) and heat removal factor (FR). The modelling tool used for the study is the software COMSOL Multiphysics, which uses the finite element method to solve the partial differential equations in heat transfer and fluid flow problems. Based on the performance curves, the thermal and electrical efficiency of the collector is approximately 48.0-53.4% and 19.0-19.2% respectively at a reduced temperature of zero and irradiance levels of 800-1000 W/m2 for the mass flow rate of 0.026 kg/sm2 which was determined as most suitable to increase thermal performance. Furthermore, these results resulted in a heat removal factor (FR) and overall heat loss coefficient (UL) of 0.56-0.62 and 53.4-53.5 W/m2 K respectively. The results on the performance of the PVT collector in different weather conditions shows that the inlet water temperature can significantly affect operating time and the amount of thermal energy that can be extracted during the year, especially if the collector operates in a colder climate like Sweden. To assess the accuracy of the created model, future work includes experimental testing of the studied PVT collector. / En panel med kombinerad teknik av både solceller och termisk solfångare (PVT) kan producera både elektricitet och värme samtidigt. Forskning har visat att det kan finnas flera fördelar med att integrera PVT-paneler med ett bergvärmesystem, eftersom det mjliggör lagring av termisk energi över året. Dessutom leder ett sådant system till lägre drifttemperaturer som kan öka PVT-panelens effektivitet och livslängd. Syftet med studien är att presentera den elektriska och termiska prestandan av en PVT-panel utvecklat av Solhybrid i Småland AB för olika driftförhållanden som kan uppstå på grund av olika väderförhållanden och inlopps-temperaturer när panelerna är kopplade till ett bergvärmesystem. Vidare utvärderas prestandan för denna panel med ASHRAEmetoden (standard 93-2003), för att möjliggöra jämförelse med andra PVT-paneler. Modelleringsverktyget som använts i studien är mjukvaran COMSOL Multiphysics, som använder finita elementmetoden för att lösa partiella differentialekvationer i värmeöverförings-och flödesproblem. Baserat på prestandakurvorna som presenteras i resultatet, är den termiska och elektriska verkningsgraden approximativt 48.0-53.4% respektive 19.0-19.2% för en reducerad temperatur med värdet noll, en solstrålning mellan 800-1000 W/m2, för en massflödeshastighet på 0.026 kg/sm2 som beslutades som den mest lämpliga för att öka den termiska prestandan. Resultaten resulterade i en värmeavledningsfaktor (FR) och total värmeförlustkoefficient (UL) på 0.56-0.62 respektive 53.4-53.5 W/m2 K. Resultaten på PVT-panelens prestanda under olika väderförhållanden visar att vattnets inloppstemperatur kan påverka drifttiden och mängden termisk energi som kan extraheras under året avsevärt, speciellt i nordiskt klimat. För att bedöma korrektheten i resultaten och den skapade modellen rekommenderas experimentell testning av den studerade PVT-panelen.

Cette thèse étudie les avantages et les potentiels offerts par le style de conception asynchrone (sans horloge) pour implémenter les traitements numériques de réception des signaux radio impulsionnelle à ultra large bande (UWB), dans le contexte applicatif des réseaux de capteurs. D'une part, des oscillateurs numériques asynchrones ont été étudiés pour réaliser l'implémentation de la base de temps nécessaire aux traitements de réception des signaux radio impulsionnelle, et d'autre part, des algorithmes et des architectures asynchrones de réception de ces signaux radio ont été proposés et validés. Ces différents travaux ont permis de démontrer la pertinence de l'approche asynchrone pour l'implémentation de ce type de traitements, notamment sur le critère de faible consommation. Elles ouvrent ainsi la voie au concept de réseau de capteurs entièrement asynchrones.

Obesity is America’s fastest growing health threat. Although a primary health risk factor, obesity increases the probability of secondary health consequences such as stroke, diabetes mellitus and heart disease. Siberian hamsters offer a convenient model to study obesity, as they exhibit a photoperiod-driven reversal of obesity during the fall-winter months (i.e., short-days-SD). SD responses in the Siberian hamster, amongst others, include decreased adiposity and gonadal regression. The duration of the dark period is faithfully transmitted into a neuroendocrine melatonin (MEL) signal; that codes seasonal information. The brain communicates with body fat (white adipose tissue- WAT) via the sympathetic nervous system (SNS). The central MEL binding sites, however, necessary for the body fat/lipid mobilization responses during SDs are not precisely known, although melatonin receptor (MEL 1aR) mRNA has been co-localized with sympathetic outflow neurons of WAT in several forebrain areas. This dissertation aims to identify and to characterize the contribution of central sites that are important in seasonal responses in Siberian hamsters. Thus, I asked: Which specific brain sites are both sufficient and necessary to stimulate SD-like decreases in body, WAT and testes mass? Furthermore, I tested if SD-induced decreases in body fat mass are accompanied by increased energy expenditure, specifically brown adipose tissue (BAT) thermogenesis. It is hoped that the identification of brain sites and mechanisms involved in the effortless reversal of obesity in these animals can be applied to treatment opportunities of human obesity.