As semiconductor technology scales down, process variations become increasingly difficult to control. To cope with this, more and more conservative delay and clock frequency estimations are used during design, which result in overly large and leaky circuits. Also, the system runs at a speed slower than that possible because a fixed clock determined by the worst-case analysis of the circuit is used. On top of process variations, voltage and temperature variations also push the designer towards even more conservative delay estimations. On the other hand, asynchronous design style has potential advantages over synchronous design including resilience to process variations, lower power consumption and higher performance. Unfortunately, these advantages are usually hindered by the significant design effort required to implement useful asynchronous circuits and also by the overhead of asynchronous control logic. Borrowing from asynchronous techniques, a new methodology is proposed to design synchronous circuits that have some of the advantages of asynchronous circuits. Asynchronous logic is used to generate the clock of a synchronous system. The resulting system automatically tunes itself to deliver the best-possible performance under the prevailing process-voltage-temperature (PVT) conditions. This methodology may be used to reduce the leakage power significantly in deep nanometer technologies. It also helps in handling process variations. The results from a 32-bit processor implemented in 90nm technology shows 10X leakage reduction compared to the traditional synchronous design. The proposed technique is expanded to adjust the speed of a pipeline according to the current operations flowing in the pipeline as well as the current PVT conditions. The results from a 32-bit processor in 90nm technology demonstrate a 2X speed improvement compared to the conventional synchronous design. The proposed techniques only use synchronous design tools and are compatible with design flows that are currently in use.

As semiconductor technology scales down, process variations become increasingly difficult to control. To cope with this, more and more conservative delay and clock frequency estimations are used during design, which result in overly large and leaky circuits. Also, the system runs at a speed slower than that possible because a fixed clock determined by the worst-case analysis of the circuit is used. On top of process variations, voltage and temperature variations also push the designer towards even more conservative delay estimations. On the other hand, asynchronous design style has potential advantages over synchronous design including resilience to process variations, lower power consumption and higher performance. Unfortunately, these advantages are usually hindered by the significant design effort required to implement useful asynchronous circuits and also by the overhead of asynchronous control logic. Borrowing from asynchronous techniques, a new methodology is proposed to design synchronous circuits that have some of the advantages of asynchronous circuits. Asynchronous logic is used to generate the clock of a synchronous system. The resulting system automatically tunes itself to deliver the best-possible performance under the prevailing process-voltage-temperature (PVT) conditions. This methodology may be used to reduce the leakage power significantly in deep nanometer technologies. It also helps in handling process variations. The results from a 32-bit processor implemented in 90nm technology shows 10X leakage reduction compared to the traditional synchronous design. The proposed technique is expanded to adjust the speed of a pipeline according to the current operations flowing in the pipeline as well as the current PVT conditions. The results from a 32-bit processor in 90nm technology demonstrate a 2X speed improvement compared to the conventional synchronous design. The proposed techniques only use synchronous design tools and are compatible with design flows that are currently in use.

Made available in DSpace on 2016-08-29T15:32:49Z (GMT). No. of bitstreams: 1 tese_2710_GARBEN BRAVIM GOMES.pdf: 1482770 bytes, checksum: 9243d54bf2284a8fe68f63c5ba00d41c (MD5) Previous issue date: 2008-10-08 / Uma estimação precisa do comportamento do reservatório é necessária para a avaliação das reservas de hidrocarbonetos, previsão de desempenho futuro desenvolvimento das instalações de produção e planejamento de métodos eficazes de recuperação de óleo. No entanto, a medição de todas as propriedades do petróleo durante a operação de um poço exploratório é inviável por causa do tempo demandado para a completa caracterização. O problema é contornado com a medição de algumas propriedades, a partir das quais se estimam outras. Com esta finalidade diversos modelos foram desenvolvidos nos últimos anos para relacionar, de forma eficiente, as propriedades do fluido do reservatório como, por exemplo, fator volume de formação, razão de solubilidade, pressão de saturação, temperatura, grau API, densidade etc. Estes modelos são conhecidos na literatura e indústria como correlações PVT, dentre as quais as mais conhecidas são de Standing, Glaso e Vazquez-Beggs. Diversas modificações dessas correlações têm sido introduzidas nos últimos anos por De Ghetto, Al Marroun, Petrosky, dentre outros. Neste trabalho apresentamos, com aplicação de um ferramental estatístico adequado, uma análise destas das correlações PVT que estimam a pressão de saturação propostas por Standing, Glaso e Vazquez-Beggs. Os dados experimentais utilizados são os apresentados por De Ghetto et al. (1995). Palavras chaves: Correlações, Propriedades PVT, Reservatórios de Petróleo.

Embedded systems which are targeted towards portable applications are required to have low power consumption because such portable devices are typically powered by batteries. During the memory accesses of such battery operated portable systems, including laptops, cell phones and other devices, a significant amount of power or energy is consumed which significantly affects the battery life. Therefore, efficient and leakage power saving cache designs are needed for longer operation of battery powered applications. Design engineers have limited control over many design parameters of the circuit and hence face many chal-lenges due to inherent process technology variations, particularly on static random access memory (SRAM) circuit design. As CMOS process technologies scale down deeper into the nanometer regime, the push for high performance and reliable systems becomes even more challenging. As a result, developing low-power designs while maintaining better performance of the circuit becomes a very difficult task. Furthermore, a major need for accurate analysis and optimization of various forms of total power dissipation and performance in nanoscale CMOS technologies, particularly in SRAMs, is another critical issue to be considered. This dissertation proposes power-leakage and static noise margin (SNM) analysis and methodologies to achieve optimized static random access memories (SRAMs). Alternate topologies of SRAMs, mainly a 7-transistor SRAM, are taken as a case study throughout this dissertation. The optimized cache designs are process-voltage-temperature (PVT) tolerant and consider individual cells as well as memory arrays.

The study sets out to review various literatures concerning photovoltaic/thermal (PVT) modules for the extraction of electricity and heat, it also reviews different PVT collectors as well as their performance. The study provides an understanding of a system that fully supports ecological society by promoting the use of solar modules from a different scope in future global resolutions. Furthermore, it looks into renewable energy in Sweden, solar energy and PVT systems, operational principles of hybrid PVT collectors, PVT applications, PVT market and legal face of PVT in Sweden among others. Among other social benefits, PVT system contributes enormously to energy savings and energy consumption which in turn lowers CO2 emissions. The review shows that PVT modules can provide homes and industries with 100% renewable electricity and heat that is affordable. This paper adopts systematic literature review, as it allows thorough cross-examination of various publications regarding the subject.

Made available in DSpace on 2016-12-23T14:08:11Z (GMT). No. of bitstreams: 1 Arquivo 1 - Capa 1.pdf: 14839 bytes, checksum: 4aceff6f3a05166a03ac50b15cef72d4 (MD5) Previous issue date: 2008-10-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Uma estimação precisa do comportamento do reservatório é necessária para a avaliação das reservas de hidrocarbonetos, previsão de desempenho futuro desenvolvimento das instalações de produção e planejamento de métodos eficazes de recuperação de óleo. No entanto, a medição de todas as propriedades do petróleo durante a operação de um poço exploratório é inviável por causa do tempo demandado para a completa caracterização. O problema é contornado com a medição de algumas propriedades, a partir das quais se estimam outras. Com esta finalidade diversos modelos foram desenvolvidos nos últimos anos para relacionar, de forma eficiente, as propriedades do fluido do reservatório como, por exemplo, fator volume de formação, razão de solubilidade, pressão de saturação, temperatura, grau API, densidade etc. Estes modelos são conhecidos na literatura e indústria como correlações PVT, dentre as quais as mais conhecidas são de Standing, Glaso e Vazquez-Beggs. Diversas modificações dessas correlações têm sido introduzidas nos últimos anos por De Ghetto, Al Marroun, Petrosky, dentre outros. Neste trabalho apresentamos, com aplicação de um ferramental estatístico adequado, uma análise destas das correlações PVT que estimam a pressão de saturação propostas por Standing, Glaso e Vazquez-Beggs. Os dados experimentais utilizados são os apresentados por De Ghetto et al. (1995). / A precise estimation of a reservoir behavior is very important for the correct evaluation of hydrocarbons amount, prediction of the performance, development of production facilities and planning of efficient recuperation methods. But direct evaluation of all petroleum properties is not viable during operation of an exploratory well bore. This problem is solved by estimating some properties from others whose evaluation in laboratory is easier. Several correlations were proposed and commented in the literature for correlating oil formation volume factor, solubility ratio, bubble point pressure, reservoir temperature, oil gravity, gas gravity, and so on. These models have been nominated PVT correlations, although sometimes the include some non PVT properties as oil and gas viscosity. The most famous correlations is that proposed by Standing, Glaso and Vazquez-Beggs, which have been modified by other researchers as, for example, De Gheto, Al Marroun and Petrosky. In this work, we present statistical analysis of some correlations (for bubble point pressure estimation) for Standing, Glaso and Vazquez-Beggs correlations. The experimental data are that presented by De Gheto in 1995.

Le carbure de silicium (SiC) est l'un des matériaux les plus prometteurs pour les dispositifs électroniques de puissance. Même si la modélisation a prouvé sa capacité à assister le développement du procédé de croissance des cristaux de SiC, de nombreux aspects ne sont toujours pas décrits de façon satisfaisante. Cette thèse a pour but d'utiliser les outils de modélisation pour étudier les phénomènes fondamentaux ayant lieu dans la croissance massive du SiC, que ce soit en phase vapeur (PVT) ou en phase liquide (TSSG). Pour la méthode PVT, une attention particulière est portée sur la physico-chimie de l'interface solide-vapeur. Pour simuler la cristallisation stœchiométrique du SiC à partir d'une phase gazeuse non-congruente, phénomène mal décrit par le modèle d'Hertz-Knudsen, nous avons considéré le SiC comme une solution solide en utilisant la modélisation couplée du transfert de masse et de la thermodynamique. Cette approche donne une évaluation de la composition du cristal de SiC qui peut être liée à des paramètres contrôlables. De telles corrélations peuvent servir de base pour contrôler la densité de défauts ponctuels, la stabilité des polytypes et la concentration de dopage. Dans le cas du procédé TSSG, les effets de la vitesse de rotation du cristal et de la fréquence du champ magnétique sont étudiés. La convection électromagnétique est la principale contribution régissant les mouvements de fluide à basse fréquence alors que la convection naturelle et l'effet Marangoni deviennent dominants à haute fréquence. Dans les conditions expérimentales utilisant les basses fréquences, la vitesse de croissance du cristal pourrait encore être accrue en augmentant la vitesse de rotation. Une modélisation analytique, couplée aux calculs de dynamique des fluides a permis de décrire les interactions entre le flux de liquide et la direction de propagation des marches de croissance à la surface du cristal. Un paramètre de phase a été introduit comme critère d'apparition de macromarches, à l'origine d'instabilités morphologiques. / Silicon Carbide (SiC) is one of the most desirable materials for power electronic devices. The development of the growth process, to achieve larger size and higher quality is on the way. Even if modeling has proved its ability to assist the optimization of the growth processes, there are still some strong issues which are not considered in a satisfactory way. This thesis aims to use the modeling tools to tackle those challenging fundamental and technological issues on both industrially used PVT and emerging TSSG processes. In the PVT process, special attention is paid to the physical chemistry at the solid-vapor interfaces. Especially, we investigated the way to model the stoichiometric crystallization of SiC from a non-congruent vapor as the Hertz-Knudsen model was shown to be not adapted. We thus considered SiC as a solid solution using coupled mass transport modeling and thermodynamics. This approach gives an assessment to the chemistry of the SiC crystal which can be linked to the controllable parameters. Such correlations may serve as a basis to control the points defect density, stable polytypes, and doping concentration. Concerning the TSSG process, the effects of crystal rotation speed and operating frequency are studied. The electromagnetic convection is the main contribution governing the growth process using low frequency while the combined buoyancy and Marangoni convections become dominant at high frequency. In the experimental conditions using low frequency, the crystal growth rate could still be enhanced by increasing the rotation speed. The phase parameter is also introduced using the combined fluid dynamics and analytical modeling. This provides a comprehensive visualization of the interactions between fluid flow and step flow and a guideline to improve the surface morphology of the crystal.

Le projet HYPMOBB vise à évaluer un procédé de mise en œuvre de matière végétale par thermo-compression. Dans le cadre de ce projet, les travaux présentés ont pour objectif d’étudier le comportement des polysaccharides sous haute contrainte mécanique (0-300 MPa) et thermique (25-200°C). Trois variétés de biopolymères ont été choisies : la cellulose, l’amidon natif de pomme de terre et ce même amidon après gélatinisation. Elles représentent trois modèles différents d’organisation: hautement cristalline sans fusion, semi-cristalline avec fusion et complétement amorphe. La démarche employée consiste dans un premier temps à analyser les données Pression-Volume-Température (PVT) obtenues à l’aide d’un dilatomètre. Les diagrammes PVT fournissent des indications précieuses sur les effets combinés de la température et de la pression. A ces deux paramètres a été ajouté l’impact de la teneur en eau sur les comportements lors de la compression. Des méthodes ont été mises au point afin d’extraire des mesures PVT, les différentes transformations thermiques (fusion, transition vitreuse) des trois polymères modèles. Pour chaque situation, l’objectif était de déterminer une tendance nette en fonction de l’humidité et de la pression puis de prédire par extrapolation les valeurs à pression nulle. Les résultats obtenus ont été comparés aux analyses classiques DSC et la bonne concordance des mesures a permis de valider les méthodes mises au point. Dans un second temps, les diagrammes PVT ont été modélisés à l’aide de l’équation de Tait. Pour les polymères cristallins, l’ajustement des courbes expérimentales à l’aide de ce modèle n’a pas été concluant. Néanmoins, la bonne modélisation du comportement PVT de l’amidon amorphe et la cohérence des paramètres déterminés a permis de valider le modèle de Tait. Pour finir, dans le but d’étudier l’effet du traitement thermique et mécanique sur la morphologie et les propriétés des compacts mis en forme, des études AMD et DRX ont été réalisées. Bien que les échantillons aient été conditionnés dans des conditions identiques, les études ont montré que la matière gardait en mémoire les conditions de leur traitement. De plus, en accord avec les analyses PVT, les matières les plus organisées, ont présenté lors de la mise en forme à chaud, la formation de liaisons/fusions inter-particulaires qui permettent d’assurer leur cohésion. / The HYPMOBB project aims to evaluate a vegetable material molding process by hot high pressure compression. In the context of this project, the objective of this work is to study the behaviour of carbohydrates under thermal and pressure constraints. Three biopolymer varieties have be chosen: cellulose, native potato starch and gelatinized starch which represented three different models of organisation: highly crystalline without fusion, semi-crystalline with fusion and totally amorphous. The approach used consists first into analysing the Pressure-Volume-Temperature data obtained by a dilatometer. PVT diagrams provide good indications of combined effects of temperature and pressure. In addition of these two parameters, the moisture content impact on the behaviour of these carbohydrates during thermal and mechanical treatment has been studied. Methods have been established in order to retrieve different thermal events (fusion, glass transition) of the three polymers from PVT measurements. For each situation, the objective was to determine a clear trend according to moisture content and pressure and then to predict by extrapolation these transition temperatures at atmospheric pressure. The obtained results have been compared to classical DSC analysis and the close concordance of the measurements allowed the validation of the established methods Secondly, diagrams have been modelled with Tait equation. For crystalline polymers, the experimental curves adjustment with this model hasn’t been concluant. However the good modelling of amorphous starch behaviour and the good concordance of the determined parameters has permitted to validate the Tait model. Finally, in order to study the effect of the compression treatment on compacts properties and morphologies, DMA and XRD analyses have been carried out. Even if the samples have been conditioned in the same conditions, the studies have shown that the materials keep the memory of the treatment conditions. Moreover, in accordance with the PVT analysis, the most organised raw materials have presented after compression molding the formation of interparticles necks/fusions allowing their cohesion.

Minskat behov av köpt energi i svenska småhus kan komma att bli en viktig del i EU:s mål att effektivisera energianvändning och minska utsläppen av växthusgaser. Solhybridpaneler (eng. Photovoltaic thermal collector, förkort. PVT) kombinerat med bergvärmepump kan bidra till målen genom att minska värmepumpens elbehov, producera el för egenanvändning och leverera överskottsproduktion till elnätet. I svenska småhus finns det mer än 440 000 installerade berg-, jord- och sjövärmepumpar. I dagsläget är det vanligaste att en ny värmepump ersätter en äldre värmepump. Vid byte av bergvärmepump finns risk att det befintliga borrhålet är underdimensionerat i förhållande till den nya värmepumpen.  PVT består av en konventionell solcellspanel (PV) för elproduktion kompletterad med en termisk kollektor som hämtar termisk energi från PV-modulen och omgivande luft. Genom att överföra termisk energi från PVT till värmepumpens värmekälla minskar värmepumpens elbehov samtidigt som PV-modulens elproduktion ökar. Arbetet görs tillsammans med företaget Samster som bland annat är konstruktör och återförsäljare av PVT. Samster efterfrågar ett beräkningsverktyg för att underlätta projektering av PVT-assisterade bergvärmepumpar avsedda för villor. Verktyget ska bedöma prestanda,miljönytta och elkostnader utifrån platsspecifika förutsättningar och PVT-anläggningens dimensionering. Slutprodukt från arbetet består av en simuleringsmodell för dimensionering av PVT-assisterad bergvärme konstruerad i mjukvaran Simulink. Med simuleringsmodellen utförs analyser avyttre förutsättningar och systemkomponenter. Simuleringar under varierande förutsättningar utförs för att visa PVT-anläggningens påverkan på elanvändning och bergvärmepumpens effektivitet.  Genomförda analyser visar att geografiskt läge och temperaturförloppet i borrhålet har störst inverkan på PVT-assisterad bergvärme och att PVT är mest effektiva när de kopplas till en värmepump som hämtar energi från ett underdimensionerat borrhål. För en villa i Göteborgmed befinligt borrhål på 100 m och årligt värmebehov på 25 000 kWh kan komplettering med9,9 m2 PVT öka SPFVP från 2,65 till 2,82. Att komplettera bergvärmepump med 9,9 m2 PVTbidrar till att reducera villans elkostnad med 14 % och koldioxidutsläpp från elanvändning reduceras med 14 %. Kylning av PVT bidrar till att öka elproduktionen med 4 - 5 % på årsbasis. Riktvärde för lämplig dimension av PVT för att termiskt assistera bergvärmepump är 0,4 – 0,5 m2/MWh totalt uppvärmningsbehov. / Reducing the need for purchased energy in Swedish detached houses may become an important part of the EU's goal of streamlining energy use and reducing greenhouse gas emissions. Photovoltaic thermal collector (PVT collector) combined with a borehole ground source heat pump can contribute to reaching the climate goals by reducing the heat pump's electricity demand, producing electricity for private use and generating a surplus production going into the electricity grid. In Swedish detached houses, there are more than 440,000 installed ground and lake water source heat pumps. At present, a new heat pump usually replaces an older heat pump. When replacing a borehole ground source heat pump, there is a risk that the existing borehole is undersized in relation to the new heat pump. PVT collectors consists of a conventional solar cell panel (PV) for electricity production supplemented with a thermal collector that collects thermal energy from the PV module and the surrounding air. By transferring thermal energy from PVT collector to the heat pump's heat source, the heat pump's electricity demand decreases while the PV module's electricity production increases. This thesis is a collaboration with Samster, a company that, among other things, designs PVTcollectors. Samster is requesting a calculation tool to facilitate the planning of PVT-assisted ground source heat pumps installations, intended for detached houses. The tool needs to assess performance, environmental benefits and electricity costs based on site-specific conditions and the dimensioning of the PVT collector installation. Finished product from the work consists of a simulation model for dimensioning PVTassisted geothermal heat systems constructed in the Simulink software. With the simulation model, analyses of external conditions and system components are performed. Simulations under varying conditions are performed to show the impact on electricity use and efficiency of the heat pump when PVT collectors are installed. Performed analysis show that geographical location and the temperature variations in the borehole have the greatest impact on the system performance and that PVT collectors are most effective when connected to a heat pump that draws energy from an undersized borehole. For a Swedish detached house located in Gothenburg with a 100-meter boreholeand an annual heat demand of 25,000 kWh, supplementation with 9.9 m2 PVT collectors can increase the heat pump´s SPFVP (seasonal performance factor) from 2.65 to 2.85. The electricity cost for the household is reduced by 14 % and carbon dioxide emissions from electricity use are reduced by 14 %.  Cooling of the PVT collectors PV cells contributes to increasing electricity production by 4 -5 % on an annual basis. Guide value for suitable dimensions for PVT collectors that assist a borehole ground source heat pump is 0,4 - 0,5 m2/MWh of total heating demand.

Finding cleaner and sustainable energy resources is one of the most important concerns for the development of humanity. Solar energy is taking an essential role in this matter as the production cost of solar collectors is decreasing and more solar installations are being set up every year throughout the world. One way of reducing the cost of solar panels is by using concentrators that are cheaper than the costly photovoltaic cells and can increase their output. Solarus AB designed a Photovoltaic Thermal (PVT) hybrid collector that uses this principle and which is a variation of the Maximum Reflector Collector (MaReCo) design and is a Compound Parabolic Collector (CPC). This thesis has two main objectives. The first one is to design variations of the actual Solarus’ design and some alternative MaReCo designs and pure parabola designs. These designs include new solar cell cuts which are based on 4 busbar solar cells. In this way a future in-depth analysis may be carried out by comparing different receiver designs and collector boxes. The second goal is to investigate the current electrical and thermal performance of the collectors from Solarus AB which are installed in the Hus 45 of HiG. The appropriate data of the installation has been obtained using simulations and specific software, and it has been analysed with Microsoft Excel®. Concerning the new designs of the receivers and boxes, everything has been prepared for the future construction of the prototypes. All the measurements and their adjustments have been taken into account to define the size of the components and the process of building has been set up. Moreover, some future work has been planned in order to move forward the project. Regarding the analysis of the HiG installation, both electrical and thermal performance have resulted to be significantly lower compared with their estimated simulation, being their real output around 60 % of the estimated one. In the thermal part, the losses in the pipeline result to be more than a third part of the produced heat. In the electrical part, the production varies a lot between different collectors due to some of them do not work properly, consequence of poor condition of the solar panels (broken cells, dirt, shading, etc.).