A large proportion of movement in urban area is constrained to a road network such as pedestrian, bicycle and vehicle. That movement information is commonly collected by Global Positioning System (GPS) sensor, which has generated large collections of trajectories. A contiguous sequential pattern (CSP) in these trajectories represents a certain number of objects traversing a sequence of spatially contiguous edges in the network, which is an intuitive way to study regularities in network-constrained movement. CSPs are closely related to route choices and traffic flows and can be useful in travel demand modeling and transportation planning. However, the efficient and scalable extraction of CSPs and effective visualization of the heavily overlapping CSPs are remaining challenges. To address these challenges, the thesis develops two algorithms and a visual analytics system. Firstly, a fast map matching (FMM) algorithm is designed for matching a noisy trajectory to a sequence of edges traversed by the object with a high performance. Secondly, an algorithm called bidirectional pruning based closed contiguous sequential pattern mining (BP-CCSM) is developed to extract sequential patterns with closeness and contiguity constraint from the map matched trajectories. Finally, a visual analytics system called sequential pattern explorer for trajectories (SPET) is designed for interactive mining and visualization of CSPs in a large collection of trajectories. Extensive experiments are performed on a real-world taxi trip GPS dataset to evaluate the algorithms and visual analytics system. The results demonstrate that FMM achieves a superior performance by replacing repeated routing queries with hash table lookups. BP-CCSM considerably outperforms three state-of-the-art algorithms in terms of running time and memory consumption. SPET enables the user to efficiently and conveniently explore spatial and temporal variations of CSPs in network-constrained movement. / <p>QC 20171122</p>

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If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.

If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.

<div>Optimization of atmospheric flight control has long been performed on the ground, prior to mission flight due to large computational requirements used to solve non-linear programming problems. Onboard trajectory optimization enables the creation of new reference trajectories and updates to guidance coefficients in real time. This thesis summarizes the methods involved in solving optimal control problems in real time using convexification and Sequential Convex Programming (SCP). The following investigation provided insight in assessing the use of state of the art SCP optimization architectures and convexification of the hypersonic equations of motion[ 1 ]–[ 3 ] with different control schemes for the purposes of enabling on-board trajectory optimization capabilities.</div><div>An architecture was constructed to solve convexified optimal control problems using direct population of sparse matrices in triplet form and an embedded conic solver to enable rapid turn around of optimized trajectories. The results of this show that convexified optimal control problems can be solved quickly and efficiently which holds promise in autonomous trajectory design to better overcome unexpected environments and mission parameter changes. It was observed that angle of attack control problems can be successfully convexified and solved using SCP methods. However, the use of multiple coupled controls is not guaranteed to be successful with this method when they act in the same plane as one another. The results of this thesis demonstrate that state of the art SCP methods have the capacity to enable onboard trajectory optimization with both angle of attack control and bank angle control schemes.</div><div><br></div>

There is a need for a fuel-optimal required time of arrival (RTA) mode for aircraft flight management systems capable of enabling controlled time of arrival functionality in the presence of wind speed forecast uncertainty. A computationally tractable two-stage stochastic algorithm utilizing a data-driven, location-specific forecast uncertainty model to generate forecast uncertainty scenarios is proposed as a solution. Three years of Aircraft Communications Addressing and Reporting Systems (ACARS) wind speed reports are used in conjunction with corresponding wind speed forecasts from the Rapid Update Cycle (RUC) forecast product to construct an inhomogeneous Markov model quantifying forecast uncertainty characteristics along specific route through the national airspace system. The forecast uncertainty modeling methodology addresses previously unanswered questions regarding the regional uncertainty characteristics of the RUC model, and realizations of the model demonstrate a clear tendency of the RUC product to be positively biased along routes following the normal contours of the jet stream. A two-stage stochastic algorithm is then developed to calculate the fuel optimal stage one cruise speed given a required time of arrival at a destination waypoint and wind forecast uncertainty scenarios generated using the inhomogeneous Markov model. The algorithm utilizes a quadratic approximation of aircraft fuel flow rate as a function of cruising Mach number to quickly search for the fuel-minimum stage one cruise speed while keeping computational footprint small and ensuring RTA adherence. Compared to standard approaches to the problem utilizing large scale linear programming approximations, the algorithm performs significantly better from a computational complexity standpoint, providing solutions in fractional power time while maintaining computational tractability in on-board systems.

Les nouveaux enjeux environnementaux motivent la recherche par les acteurs de l'industrie aéronautique de méthodes de calcul de trajectoires optimales. Les contributions de cette thèse se déclinent selon trois axes. Dans un premier temps, plusieurs techniques d'optimisation de trajectoire avion sont comparées sur un cas simple traité dans la bibliographie universitaire. Puis, un modèle réduit pour prendre en compte le niveau des nuisances sonores dans un algorithme d'optimisation de trajectoire est proposé.Enfin, un problème d'optimisation de trajectoire de montée d'un avion civil est résolu par une approche directe. Les spécificités du problème consistent en la présence de plusieurs phases au sein de la trajectoire, la formulation de contraintes égalités à vérifier par des composantes du vecteur d'état sur des intervalles de temps et enfin la difficulté d'intégration numérique du modèle de bruit. / Forthcoming environmental challenges stimulate the development of trajectory optimization methods by aeronautical actors. This contribution consists in three parts. First, several trajectory optimization techniques are compared. The comparison is based on a simple academic problem. After that, a model is proposed for considering noise nuisance level in the framework of trajectory optimization. Finally, the optimization problem of an ascent phase of a civil aircraft is solved using a direct approach. The specific issues of the problem are tackled with a general formulation. They consist in the presence of several phases along the trajectory, running state equality constraints and tough numerical integration of the noise model.

Neste trabalho apresentamos uma versão do Teorema de Poincaré-Bendixson para campos vetoriais contínuos na garrafa de Klein. Como conseqüência, mostramos que a garrafa de Klein não possui campo vetorial contínuo com trajetória injetiva recorrente / We present a version of the Poincaré-Bendixson Theorem on the Klein bottle for continuous vector fields. As a consequence, we obtain the fact that the Klein bottle does not admit continuous vector fields having a recurrent injective trajectory

Spatio-temporal data is a commonly used source of information. Using machine learning to analyse this kind of data can lead to many interesting and useful insights. In this thesis project, a novel public transportation spatio-temporal dataset is explored and analysed. The dataset contains 282 GB of positional events, spanning two weeks of time, from all public transportation vehicles in Östergötland county, Sweden.  From the data exploration, three high-level problems are formulated: bus stop detection, GPS variance estimation, and arrival time prediction, also called trajectory forecasting. The bus stop detection problem is briefly discussed and solutions are proposed. Gaussian process regression is an effective method for solving regression problems. The GPS variance estimation problem is solved via the use of a mixture of Gaussian processes. A mixture of Gaussian processes is also used to predict the arrival time for public transportation buses. The arrival time prediction is from one bus stop to the next, not for the whole trajectory.  The result from the arrival time prediction is a distribution of arrival times, which can easily be applied to determine the earliest and latest expected arrival to the next bus stop, alongside the most probable arrival time. The naïve arrival time prediction model implemented has a root mean square error of 5 to 19 seconds. In general, the absolute error of the prediction model decreases over time in each respective segment. The results from the GPS variance estimation problem is a model which can compare the variance for different environments along the route on a given trajectory.

Entre 2004 e 2014, a Educação Superior brasileira passou pelo maior processo de expansão já empreendido em sua curta história. Embora a maior parte das matrículas tenha se mantido na rede privada, foi no setor público que ocorreu a ampliação mais significativa do número de instituições, cursos, matrículas e funções docentes, especialmente na rede federal. Tal processo possibilitou o ingresso não somente de maior número de discentes oriundos de famílias pobres e sem tradição de longevidade escolar, mas também de docentes que trilharam trajetórias formativas e profissionais marcadas por condicionantes sociais próprios desse tipo de origem, os quais relacionam as escolas que puderam frequentar com as escolhas possíveis quanto à formação acadêmica e a inserção no mundo do trabalho. Com referencial teóricometodológico bourdieusiano e o objetivo de desvelar os condicionantes sociais de trajetórias de docentes de origem popular que ingressaram numa universidade federal durante a expansão, foram coletados dados em fontes documentais diversas e também por meio de questionário, observação de locais de trabalho e entrevista semiestruturada, de natureza autobiográfica. Do total de 1.427 docentes que compunham o quadro efetivo da Universidade Federal de São Paulo (Unifesp) em julho de 2014, o questionário foi respondido por 339 agentes de diversas origens sociais e, entre eles, foram entrevistados 31 docentes de origem popular, distribuídos em cinco campi e diversas áreas de conhecimento. Para situar sóciohistoricamente o espaço de confluência das trajetórias, a análise parte de um histórico da instituição, desde sua criação, por e para uma parcela da elite paulistana, como Escola Paulista de Medicina (EPM), até as transformações que a tornaram uma universidade multicampi, por força da expansão que visava democratizar seu público. Em seguida, dois capítulos se dedicam a expor os aspectos considerados mais relevantes nas trajetórias. A análise revela 9 condicionantes sociais mais proeminentes: i- influência do nível de escolaridade familiar nas formas de adesão ao jogo da escolarização; ii- acesso a diferentes oportunidades de formação escolar; iii- relação entre as restrições materiais sofridas durante a formação básica e a precariedade das estratégias de acúmulo de capital cultural; iv- implicação da formação inicial na escolha da formação universitária; v- necessidade de recursos materiais para assegurar a vida universitária; vi- convivência acadêmica como impulsora da formação e carreira; vii- obtenção de bolsa de estágio em nível de Pós-Doutorado; viii- expansão das universidades federais; ix- configurações específicas das áreas de conhecimento como balizador dos modos de trabalho. Conclui-se que os condicionantes sociais diretamente relacionados à origem de classe não justificam integralmente os percursos, as escolhas e os investimentos na carreira; porém, delineiam o horizonte de possibilidades e operam sobre a estruturação dos esquemas de percepção, avaliação, pensamento e ação de cada agente, cumprindo função decisiva na definição do destino e do desenvolvimento profissional. Portanto, tais condicionantes não podem ser ignorados quando se discute a expansão ou democratização do acesso à Educação Superior, sobretudo no que diz respeito à importância da assistência estudantil como política de permanência para que os estudantes pobres conquistem a longevidade escolar. / Between 2004 and 2014, Higher Education in Brazil experienced the largest expansion in its short history. Although most registrations took place in private institutions, the public sector faced the most significant enlargement in the number of institutions, courses, registrations and teaching functions, especially in the federal system. Such process enabled not only access to the university by a greater number of students from poor families and with no tradition of schooling longevity, but also professors who have had formative and professional trajectories marked by social constraints, typical of such origin, which relate to the schools they were able to attend with their possible choices regarding academic education and transition to the labor market. Supported by Bourdieu´s theoretical/methodological framework and with the purpose of unveiling the social constraints of the trajectories of professors from grass-roots background who were admitted to a federal university at the time of the expansion, data collection came from several documental sources and also from a questionnaire, the observation of the workplaces and an autobiographical semi-structured interview. Out of 1,427 professors who were the effective faculty of the Federal University of São Paulo (Unifesp) in July, 2014, the questionnaire got responses from 339 agents from several social origins and, out of them, 31 professors from grass-roots background were interviewed, spread in five campuses and from different areas of knowledge. In order to locate socio-historically the space of confluence of the trajectories, the analysis starts with a history of institution, since it was established, by and for a portion of São Paulo´s elite, as the São Paulo Medical School (EPM), up to the changes that turned it into a multi-campus university, as a result of the expansion aimed at democratizing its public. Next, two chapters are dedicated to exposing the most remarkable aspects in the trajectories. The analysis reveals nine (9) outstanding social constraints: i- influence of the family schooling level in the forms of adherence to the schooling game; ii- access to different opportunities of education; iii- relation between the material limitations occurring during basic education and the precarious strategies of building up cultural capital; iv- implication of the basic education in the choice of higher education to be pursued; v- need of material resources to achieve a university degree; vi- academic conviviality as an impeller to education and career; vii- getting a scholarship as a PostDoctoral intern; viii- expansion of the federal universities; ix- specific configurations of the areas of knowledge as a guide of the ways of work. Conclusion was that the social constraints directly associated with the class origin do not thoroughly justify the routes taken, the choices and investments made in the career; however, they outline the horizon of possibilities and play a role onto the structuring of the schemes of perception, evaluation, thinking and action of each agent, fulfilling a decisive function in defining the professional destiny and development. Therefore, such constraints cannot be ignored when one discusses the expansion or democratization of the access to Higher Education, mainly concerning the importance of student assistance as a policy to retain poor students and make them achieve schooling longevity.