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Autonomous electric vehicles are set to replace most conventional vehicles in the near future. Extensive research is being done to improve efficiency at the individual and fleet level. There is much potential benefit in optimizing the deployment and rebalancing of Autonomous Electric Taxi Fleets (AETF) in cities with dynamic demand and limited charging infrastructure. We propose a Fleet Management System with an Online Optimization Model to assign idle taxis to either a region or a charging station considering the current demand and charging station availability. Our system uses real-time information such as demand in regions, taxi locations and state of charge (SoC), and charging station availability to make optimal decisions in satisfying the dynamic demand considering the range-based constraints of electric taxis. We integrate our Fleet Management System with MATSim, an agent-based transport simulator, to simulate taxis serving real on-demand requests extracted from the San Francisco taxi mobility dataset. We found our system to be effective in rebalancing and ensuring efficient taxi operation by assigning them to charging stations when depleted. We evaluate this system using different performance metrics such as passenger waiting time, fleet efficiency (taxi empty driving time) and charging station utilization by varying initial SoC of taxis, frequency of optimization and charging station capacity and power.

Autonomous electric vehicles are set to replace most conventional vehicles in the near future. Extensive research is being done to improve efficiency at the individual and fleet level. There is much potential benefit in optimizing the deployment and rebalancing of Autonomous Electric Taxi Fleets (AETF) in cities with dynamic demand and limited charging infrastructure. We propose a Fleet Management System with an Online Optimization Model to assign idle taxis to either a region or a charging station considering the current demand and charging station availability. Our system uses real-time information such as demand in regions, taxi locations and state of charge (SoC), and charging station availability to make optimal decisions in satisfying the dynamic demand considering the range-based constraints of electric taxis. We integrate our Fleet Management System with MATSim, an agent-based transport simulator, to simulate taxis serving real on-demand requests extracted from the San Francisco taxi mobility dataset. We found our system to be effective in rebalancing and ensuring efficient taxi operation by assigning them to charging stations when depleted. We evaluate this system using different performance metrics such as passenger waiting time, fleet efficiency (taxi empty driving time) and charging station utilization by varying initial SoC of taxis, frequency of optimization and charging station capacity and power.

Bike Sharing is a sustainable mode of urban mobility, not only for regular commuters but also for casual users and tourists. Free-floating bike sharing (FFBS) is an innovative bike sharing model, which saves on start-up cost, prevents bike theft, and offers significant opportunities for smart management by tracking bikes in real-time with built-in GPS. Efficient management of a FFBS requires: 1) analyzing its mobility patterns and spatio-temporal imbalance of supply and demand of bikes, 2) developing strategies to mitigate such imbalances, and 3) understanding the causes of a bike getting damaged and developing strategies to minimize them. All of these operational management problems are successfully addressed in this dissertation, using tools from Operations Research, Statistical and Machine Learning and using Share-A-Bull Bike FFBS and Divvy station-based bike sharing system as case studies.

In this thesis, the parallel performance of the finite element-spherical harmonics (FE-PN) method implemented in the general-purpose radiation transport code EVENT is studied both analytically and empirically. EVENT solves the coupled set of space-angle discretized FE-PN equations using a parallel block-Jacobi domain decomposition method. As part of the analytical study, the thesis presents complexity results for EVENT when solving for a 3D criticality benchmark radiation transport problem in parallel. The empirical analysis is concerned with the impact of the main algorithmic factors affecting performance. Firstly, EVENT supports two solution strategies, namely MOD (Moments Over Domains) and DOM (Domains Over Moments), to solve the transport equation in parallel. The two strategies differ in the way they solve the multi-level space-angle coupled systems of equations. The thesis presents empirical evidence of which of the two solution strategies is more efficient. Secondly, different preconditioners are used in the Preconditioned Conjugate Gradient (PCG) inside EVENT. Performance of EVENT is compared when using three preconditioners, namely diagonal, SSOR(Symmetric Successive Over-Relaxation) and ILU. The other two factors, angular and spatial resolutions of the problem affect both the performance and precision of EVENT. The thesis presents comparative results on EVENTs performance as these two resolutions are increased. From the empirical performance study of EVENT, a bottleneck is identified that limits the improvement in performance as number of processors used by EVENT is increased. In some experiments, it is observed that uneven assignment of computational load among processors causes a significant portion of the total time being spent in synchronization among processors. The thesis presents two indicators that identify when such inefficiency occur; and in such a case, a load rebalancing strategy is applied that computes a new partition of the problem so that each partition corresponds to equal amount of computational load.

Most studies view transaction costs and constraints separate in the mean-variance framework. As such, I evaluate the benefits of holding and turnover constraints in the presence of transaction costs on Swedish Asset Returns. In theory, the benefits should be limited when transaction costs are included in the portfolio rebalancing problem. By using the model developed by Mitchell and Braun (2003), my results indicate that there are benefits of holding constraints in the mean-variance optimization. The main issue with the long-only portfolio is its lack of diversification. The strategy allocates the majority of the investment in 15 out of 100 assets. By imposing holding constraints, the portfolio becomes more diversified while reducing turnover volume and increasing Sharpe ratio. I find that the homogenous 1/N holding constraint increases monthly Sharpe ratio performance by 50 percent over the entire sample. However, the results are not consistent over all samples and not statistically significant. Further, turnover constraints only marginally increase performance, which more likely originates from the increase in diversification.

Landscape is dynamic. All the elements in the landscape are in a continual process of change. There is growth, expansion, weathering, disintegration, decay and renewal. Change is the very substance of things and it is through these changes that we register the passage of time. This thesis explores the concept of material duration and its application to landscape design. Duration is a complex measure of time. This thesis adapts a definition of duration developed in the field of finance to explore time in the design of an urban cemetery. The design embodies the concept of a cemetery with a "constant duration". This lasting quality of constant duration is a persistence that retains at its core the essence of the landscape while embracing the unavoidable and indispensable material changes. To design with constant duration is to analyze and chart a design as a journey through time. / Master of Landscape Architecture

Sistemas de Bicicletas Compartilhadas (SBCs) têm sido implantados e aprimorados nos últimos anos nas principais cidades do mundo. Neste tipo de sistema, usuários podem retirar e devolver bicicletas em qualquer estação da rede, desde que haja bicicleta e vaga disponível, respectivamente. Porém, devido às características de ocupação do solo em grandes centros urbanos, existe uma tendência natural de desbalanceamento nos fluxos dos usuários, fazendo com que em determinados horários certas estações fiquem lotadas de bicicletas enquanto outras estações estão vazias. Para mitigar este problema, gestores de SBCs utilizam veículos de carga para rebalancear o sistema (reposicionar as bicicletas entre as estações). Entretanto, usualmente, esse processo na prática não é realizado com auxílio de ferramentas quantitativas que tornem o processo racional ou maximizem sua eficácia. Nesse sentido, no presente trabalho é proposto um modelo híbrido de simulação com otimização, aplicado ao rebalanceamento de um SBC brasileiro e com potencial para utilização em sistemas reais com o objetivo de melhorar seus níveis de serviço. Além disso, apresenta-se uma análise de dados e a caracterização de uso deste SBC, um histórico de evolução de SBCs ao redor do mundo e sua bibliografia pertinente, a fim de registrá-los na literatura e de se obter maior compreensão deste tipo de sistema. / Bike Sharing Systems (BSSs) have been implemented and enhanced in several major cities around the world, during the past few years. In such systems, users can take off a bike and return it at any network\'s station, provided that there is a bike and a dock available, respectively. However, these systems face an operational problem, caused by the fact that users\' flows are not balanced, bringing on that, at some point in time, some stations will be completely full while others will be empty. To tackle this issue, cargo vehicles are used by BSS\'s operators to rebalance the system (relocate bicycles through the stations). However, in most cases this process is not supported by quantitative tools that make the process rational or maximize its effectiveness. In this sense, this work proposes a hybrid model of simulation with optimization, applied to the rebalance of a Brazilian BSS and with potential for use in real systems with the aim of improving their service levels. In addition, is presented a data analysis and a usage study of this specific BSS, a BSSs evolutionary study and its relevant literature with the purpose of registering them in the literature and achieving a superior understanding of the problem.

Depuis la prise de possession de la Nouvelle-Calédonie par la France en 1853, les tensions entre les autochtones et les allochtones ont toujours existé car cet archipel met en présence deux mondes qui se côtoient tout en s’ignorant. À une bipolarisation ethnique naturellement imparfaite entre les populations mélanésiennes et les colonisateurs, s’ajoute également une bipolarisation sociologique, politique, économique et sociale.Dès 1970, la majeure partie de la population mélanésienne de Nouvelle-Calédonie lutte pour une reconnaissance et une revalorisation de son identité culturelle et de son patrimoine, et c’est avec « Melanesia 2000 » en 1975 que le ciment culturel prend corps et avec le foncier que le fondement de la personnalité mélanésienne est affirmé. Les tensions allant crescendo aboutissent au drame d’Ouvéa. Partis d’une situation conflictuelle, les rapports deviennent consensuels avec les Accords de Matignon. La bipolarisation conflictuelle fait place à une bipolarisation contractuelle.La création de trois provinces constitue la première étape de ce long processus d’émancipation. L’Accord de Nouméa et sa loi organique de 1999 poussent la sophistication institutionnelle jusqu’à mettre en place un gouvernement local composé à la proportionnelle des membres du Congrès. Le rééquilibrage concerne les domaines politique, économique et social. En fin d’accord, les calédoniens devront se prononcer sur le transfert des pouvoirs régaliens à la Nouvelle-Calédonie. Comme toutes les élections sont clivées par rapport au concept d’indépendance, les électeurs se basent d’abord sur le positionnement des candidats par rapport à ce concept. L’Accord de Nouméa, de lecture plurielle, obvie les mésententes. Il permet le partage du pouvoir mais laisse en suspend la question essentielle du devenir ultérieur de la Nouvelle-Calédonie. La raison l’a emporté sur la violence, mais les convictions des uns et des autres restent apparemment intactes / Since taking possession of New Caledonia by France in 1853, tensions between natives and immigrants have always existed since the archipelago brings together two worlds that coexist while ignoring each other. At a naturally imperfect polarization between ethnic Melanesian and colonizers, also adds a polarization sociological, political, economic and social.By 1970, most of the Melanesian population of New Caledonia struggle for recognition and appreciation of cultural identity and heritage, and it is with "Melanesia 2000" in 1975 that cement cultural body and takes the property that the basis of personality is Melanesian said. Tensions ranging from tragedy to lead crescendo Uvea. Parties to a conflict situation, the reports become consensual with the Matignon Accords. The bipolar conflict gives way to a polarization of contract. The creation of three provinces is the first step in this long process of emancipation. The Noumea Accord and its organic law of 1999 to push the sophistication institutional set up a local government comprising proportional congressmen. Rebalancing for the political, economic and social development. At the end of agreement, the Caledonian will decide on the transfer of sovereign powers to New Caledonia. Like all elections are cleaved from the concept of independence, voters rely first on the positioning of candidates compared to that concept. The Noumea Accord, reading plural obviates the disagreements. It allows the sharing of power but leaves the key issue of suspending further becoming of New Caledonia. The reason has prevailed over violence, but the convictions of each others apparently remain intact