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This thesis explores opportunities in the mathematical modelling of metal rolling processes, specifically asymmetrical sheet rolling. With the application of control systems in mind, desired mathematical models must make adequate predictions with short computational times. This renders generic numerical approaches inappropriate. Previous analytical models of symmetrical sheet rolling have relied on ad hoc assumptions about the form of the solution. The work within this thesis begins by generalising symmetric asymptotic rolling models: models that make systematic assumptions about the rolling configuration. Using assumptions that apply to cold rolling, these models are generalised to include asymmetries in roll size, roll speed and roll-workpiece friction conditions. The systematic procedure of asymptotic analysis makes this approach flexible to incorporating alternative friction and material models. A further generalisation of a clad-sheet workpiece is presented to illustrate this. Whilst this model was formulated and solved successfully, deterioration of the results for any workpiece inhomogeneity demonstrates the limitations of some of the assumptions used in these two models. Attention is then turned to curvature prediction. A review of workpiece curvature studies shows that contradictions exist in the literature; and complex non-linear relationships are seen to exist between asymmetries, roll geometry and induced curvature. The collated data from the studies reviewed were insufficient to determine these relationships empirically; and neither analytical models, including those developed thus far, nor linear regressions are able to predict these data. Another asymmetric rolling model is developed with alternative asymptotic assumptions, which shows non-linear behaviour over ranges of asymmetries and geometric parameters. While quantitative curvature predictions are not achieved, metrics of mechanisms hypothesised to drive curvature indicate these non-linear curvature trends may be captured with further refinement. Finally, coupling a curved beam model with a curvature predicting rolling model is proposed to model the ring rolling process. Both of these parts are implemented but convergence between them is not yet achieved. By analogy this could be extended with shell theory and a three-dimensional rolling model to model the wheeling process.

The rapid growth in Field Programmable Gate Array (FPGA) architecture design space has led to an explosion in architectural choices that exceed well over 1,000,000 configurations. This makes searching for pareto-optimal solutions using a CAD-based incremental design process near impossible for hardware architects and application engineers. Designers need fast and accurate analytical models in order to evaluate the impact of their design choices on performance. Despite the proliferation of FPGA models, todays state-of the art modeling tools suffer from two drawbacks. First, they rely on circuit characteristics extracted from various stages of the FPGA CAD flow making them CAD dependent. Second, they lack ability to take routing architecture parameters into account. These two factors pose as a barrier for converging to the desired implementation rapidly. In this research, we address these two challenges and propose the first static power and post-routing wirelength models in academia. Our models are unique as they are CAD-independent, and they take both logic and routing architecture parameters into account. Using the static power model we are able to estimate the active and idle leakage power dissipation in homogeneous FPGAs with average correlation factor of 95% and mean percentage error of 17% over experimental results based on MCNC benchmarks. Using our wirelength model, we are able to obtain a low mean percentage error of 4.2% and an average correlation factor of 84% using MCNC and VTR benchmarks. We also show that utilizing wirelength model for architecture optimization process reduces the design space exploration time by 53% compared to the CAD-based process. We finally propose an algorithmic approach to estimate the logic density (i.e., number of LUTs) of multiplexer-based circuits, and address the problem of discrete effects in FPGA analytical models. We show that a model that generates logic density of a fundamental circuit element, such as a multiplexer, can be used to estimate performance metrics, such as critical path delay and power.

The rapid growth in Field Programmable Gate Array (FPGA) architecture design space has led to an explosion in architectural choices that exceed well over 1,000,000 configurations. This makes searching for pareto-optimal solutions using a CAD-based incremental design process near impossible for hardware architects and application engineers. Designers need fast and accurate analytical models in order to evaluate the impact of their design choices on performance. Despite the proliferation of FPGA models, todays state-of the art modeling tools suffer from two drawbacks. First, they rely on circuit characteristics extracted from various stages of the FPGA CAD flow making them CAD dependent. Second, they lack ability to take routing architecture parameters into account. These two factors pose as a barrier for converging to the desired implementation rapidly. In this research, we address these two challenges and propose the first static power and post-routing wirelength models in academia. Our models are unique as they are CAD-independent, and they take both logic and routing architecture parameters into account. Using the static power model we are able to estimate the active and idle leakage power dissipation in homogeneous FPGAs with average correlation factor of 95% and mean percentage error of 17% over experimental results based on MCNC benchmarks. Using our wirelength model, we are able to obtain a low mean percentage error of 4.2% and an average correlation factor of 84% using MCNC and VTR benchmarks. We also show that utilizing wirelength model for architecture optimization process reduces the design space exploration time by 53% compared to the CAD-based process. We finally propose an algorithmic approach to estimate the logic density (i.e., number of LUTs) of multiplexer-based circuits, and address the problem of discrete effects in FPGA analytical models. We show that a model that generates logic density of a fundamental circuit element, such as a multiplexer, can be used to estimate performance metrics, such as critical path delay and power.

No description available.

Tubos flexíveis e cabos umbilicais têm sido bastante utilizados pela indústria petrolífera em aplicações offshore nos últimos anos. Os primeiros consistem num tipo de tubulação usada para o transporte de vários tipos de fluidos, geralmente trabalhando a alta pressão. Já os cabos umbilicais são usados para permitir o controle e a comunicação entre equipamentos submersos e de superfície. Quanto à concepção estrutural, os dois tipos de produto são muito semelhantes, apresentando diversas camadas metálicas combinadas com camadas plásticas concêntricas de modo a formar uma estrutura com grande rigidez axial e torcional, porém baixa rigidez flexional. O escopo deste trabalho é o estudo de modelos analíticos para a previsão do comportamento estrutural de tubos flexíveis e cabos umbilicais. Inicialmente são propostos modelos para a análise local destas estruturas, sob a ação de carregamentos de tração, torção, pressão interna, externa e flexão, agindo isoladamente ou combinados. São propostos modelos analíticos consistentes para cada camada, resultando num sistema de equações algébricas que, ao ser resolvido, fornece os valores de tensões e deformações nas diversas camadas, bem como os valores de rigidez equivalente axial, flexional e torcional do tubo/cabo. São feitas várias comparações entre os resultados obtidos analiticamente e resultados experimentais obtidos na literatura para diversos tubos e cabos. A importância dos modelos desenvolvidos fica evidente numa análise do comportamento global para a previsão de instabilidade de linhas sob carregamento combinado de torção e compressão dinâmica. Através de uma análise consistente, mostra-se que a clássica equação de Greenhill também pode ser utilizada para a determinação das cargas críticas de flambagem em barras curvas de grande comprimento, sendo o comprimento de flambagem da barra estimado a partir da relação de dispersão de onda flexional numa viga reta. Vários exemplos de determinação da carga crítica de flambagem são abordados, envolvendo tanto risers rígidos quanto flexíveis. Uma atenção especial ao estabelecimento e discussão de hipóteses é dada em todos os modelos propostos. / Flexible pipes and umbilical cables have been largely used by the oil industry in offshore applications in these last years. The former are a kind of pipeline structure used for conducting several fluids, often working at high pressure, while the latter are cables used to provide control and communication links between seafloor and surface equipments. Regarding their structural design, both flexible pipes and umbilicals are quite similar, presenting a number of steel armour layers combined with polymeric layers disposed in such a way to form a structure which is stiff under torsion and traction, but compliant under bending. The aim of this work is the study of analytical models to predict the structural behaviour of flexible pipes and umbilicals. At first, local analysis of such structures is undertaken, considering combined loadings of traction, torsion, internal and external pressures and bending. Consistent analytical models, proposed for each layer, are then combined to result in a system of algebraic equations that is solved for the stresses and deformations in the layers. Equivalent axial, torsional and flexural stiffness values for the pipe/umbilical are also obtained. Several comparisons between analytical results and experimental results obtained in the literature are also made, involving both flexible pipes and umbilicals. The importance of the developed models is highlighted in an analysis of the global structural behaviour made to predict the instability condition of flexible lines under the action of dynamic compression and twisting moment. Through a consistent analysis, it is shown that the classical Greenhill formula can also be used to determine critical buckling loads for long curved rods. In this case, an estimate for the buckling lenght is given by the flexural wave dispersion relation of a straight beam. Several examples, involving both SCRs and flexible pipes, illustrate the method of critical buckling load determination. Emphasis is also given in the establishment and discussion of hypotheses for all proposed models.

This thesis dealt with the techniques that could be used for the pre-assessment of contaminated sites. The goals of the thesis were based on a simple fact that every contaminated site possesses certain potential to degrade natural resources, specifically groundwater and land resources. The thesis focused on using mathematical and statistical techniques to predict the maximum length of contaminated plumes or Lmax, which it considered as a key parameter that could be used for the site assessment. As the first thesis work, data from KORA sites were compiled and analysed. From the analyses, it was found that the Lmax for BTEX plumes are in average under 150 m long. Further, for this work, Analytical Models that can be used to estimate Lmax were reviewed and, examples comparing model and fifield Lmax were presented. The second work for the thesis focused on a development and analysis of a new 3D-analytical model for a fifinite planar and fully penetrating source. An implicit expression for predicting Lmax was obtained. The analysis of the developed model suggested that the longest Lmax will result if the source takes an approximately square shape. The last part of the thesis improved the 3D-analytical model obtained in the second work by presenting an expression for a fifinite planar source that only partially penetrates the aquifer. For this work, a very simple numerical technique was developed that not only simplififies numerical analysis of the scenarios considered in this thesis but it also bears potentials to be used for very complex subsurface reaction transport scenarios. This thesis has been successful in narrowing research-gaps on problems related to contaminated sites management. / Diese Doktorarbeit befasste sich mit Methoden, welche für eine Vorabbewertung von kontaminierten Standorten genutzt werden können. Die Ziele der Arbeit basierten auf dem einfachen Fakt, dass jeder kontaminierte Standort ein bestimmtes Potential besitzt, natürliche Ressourcen, speziell Grundwasser- und Bodenressourcen, in ihrer Qualität negativ zu beeinträchtigen. Die Arbeit war auf die Nutzung mathematischer und statistischer Techniken zur Abschätzung der maximalen Schadstofffahnenlänge, auch Lmax, fokussiert, welche als entscheidender Parameter für die Standortbewertung genutzt werden kann. Der erste Teil der Doktorarbeit beinhaltete die Zusammenstellung und Analyse von Daten einer Vielzahl von KORA-Standorten. Anhand dieser Untersuchungen konnte festgestellt werden, dass Lmax von BTEX-Fahnen im Mittel unterhalb von 150 m liegt. Des Weiteren wurden für diese Arbeit analytische Modelle, welche für die Abschätzung von Lmax genutzt werden können, kritisch bewertet und vergleichende Beispiele zwischen mit Modellierung bestimmter und im Feld ermittelter Lmax präsentiert. Der zweite Teil der Doktorarbeit zielte auf die Entwicklung und Analyse eines neuen dreidimensionalen, analytischen Models für eine finite, planare und über die komplette Mächtigkeit vorherrschende Quelle ab. Es konnte ein impliziter mathematischer Ausdruck zur Vorhersage von Lmax gewonnen werden. Die Analyse des Models wies darauf hin, dass maximale Lmax erreicht werden, wenn die Quelle eine annähernd quadratische Form aufweist. Der letzte Teil der Doktorarbeit diente der Weiterentwicklung des dreidimensionalen, analytischen Modells aus dem zweiten Teil durch die Entwicklung eines Ausdrucks für eine finite, planare Quelle, welche jedoch nur teilweise die Mächtigkeit des Grundwasserleiters kontaminiert. Für diese Arbeit wurde ein sehr einfacher numerischer Ansatz entwickelt, welcher die numerische Analyse der in dieser Arbeit berücksichtigten Szenarien nicht einfach nur erleichtert, sondern auch das Potential beinhaltet diesen auf komplexe, reaktive Transportszenarien im Untergrund anzuwenden. Abschließend kann gesagt werden, dass diese Arbeit erfolgreich zur Verringerung von Forschungslücken in der Problematik des Managements kontaminierter Standorte beigetragen hat.

Mobile ad hoc networks create communication links without the aid of any infrastructure, forwarding packets among mobile nodes. The MANET research community has identified several fundamental challenges, among which the most prominent is discovering an optimal route between two nodes. Existing work has proposed a plethora of routing protocols. Since each protocol implements its own philosophy and algorithm to target a specific purpose, routing protocols in MANETs show very different characteristics. Selecting a particular protocol for an application or deployment environment involves evaluating many complex inter-dependent tradeoffs and can be an overwhelming task for an application designer. However, this decision can have a significant impact on the success of a system in terms of performance, cost, and responsiveness. Emerging distributed applications deployed in MANETs inherently experience highly dynamic situations, which necessitate real-time routing protocol selection in response to varying scenarios. Most of the relevant research in this area relies on simulation studies or empirical analysis to select a routing protocol, requiring an infeasible amount of time and resources for the approaches to be used in real-time decision making. In my dissertation work, I designed the Chameleon framework to facilitate real-time routing protocol decisions based on given application and environmental characteristics. My approach develops analytical models for important network layer performance measures capturing various inter-dependent factors that affect routing protocol behavior. I provide an analytical framework that expresses protocol performance metrics in terms of environment-, protocol-, and application-dependent parameters. This effort has resulted in detailed models for two important metrics: end-to-end delay and throughput. I specify detailed models for the parameters embedded in the models with respect to the ability of network deployers, protocol designers, and application developers to reasonably provide the information. Finally, in a systematic manner, I outline the Chameleon software framework to integrate the analytical models with parameters specified by these three groups of stakeholders. / text

Losses for wake effects in offshore wind farms represent about 10% to 20% of the park annual energy production. Several analytical wake models have been developed and implemented to predict the power deficit of a wake-affected wind turbine. Validating and parameterizing the wake models available in the industry is essential to better predict the wake losses and thus maximize the energy yield of future offshore developments. In this study, a wake model validation is undertaken for the three models available in the commercial software WindSim. Data from Horns Rev wind farm is used to that purpose. Next, the models that show the best agreement with the observations are parameterized to better describe the power losses of a future offshore wind farm at Bockstigen. To finish with, an optimization sensitivity study is carried out and a final optimal layout is determined according to the seabed depth.

O presente memorial está dividido em duas partes, a primeira trata da situação do compositor de frente à sua própria peça. Partindo do modelo tripartite da semiologia de Jean Jaques Nattiez, é proposto um deslocamento do observador com o intuito de oferecer uma ferramenta analítica a ser utilizada pelo compositor na análise de seu próprio trabalho. Após a formulação teórica, esta primeira parte é encerrada por uma breve análise de uma das peças do portfólio apresentada como uma primeira aproximação ao funcionamento do modelo analítico e como exemplo das questões que estão se debatendo tais como material, objeto musical entre outros. Esta análise é seguida por uma critica composicional que por sua vez dá lugar a alguns comentários de outra das peças do portfólio. A segunda parte trata do problema composicional especifico que fora trabalhado durante o mestrado; a saber, o relacionamento entre tempo e forma. Num primeiro momento se estabelece um debate teórico para logo dar lugar à análise de outra peça do portfólio que exemplificará o funcionamento de um dispositivo formal proposto como possível solução ao binômio tempo/forma. / This text is divided into two parts, the first dealing with the situation of the composer in front of his own work. Based on the tripartite model of semiology proposed by Jean Jaques Nattiez, a shift of the observer is proposed in order to provide an analytical tool to be used by the composer in the analysis of their own work. After the theoretical formulation, the first part concludes with a brief analysis of a piece of the portfolio presented as a first approach to the operation of the analytical model and an example of the issues with which at deals, such as material and musical objects. This analysis is followed by a compositional critique, which in turn gives rise to some comments on an other piece of the portfolio. The second part deals with the specific compositional problem that has been worked during the Masters investigation: namely, the relationship between time and form. At first a theoretical debate is established that in turn give rise to the analysis of another piece of the portfolio that exemplifies the performance of a device formally proposed as a possible solution to the binomial time/form.