As concerns about climate change increase, many people are calling for reductions in the use of fossil fuels and encouraging a shift to more sustainable and less polluting transportation modes. Cities and urban areas are more concerned because their population currently comprises over half of the world's population. Sustainable transportation modes such as cycling, walking, and use of public transit and electric vehicles can benefit the environment in many ways, including a reduction in toxic greenhouse gas (GHG) emissions and noise levels. In order to enhance the trend of using sustainable modes of transportation, tools, measures, and planning techniques similar to those used for vehicular transportation need to be developed. In this dissertation, we consider four problems in the context of different sustainable modes of transportation, namely, cycling, rail, public transit, and ridesharing. We develop different models to predict bike travel times for use in bike share systems (BSSs) using random forest (RF), least square boosting (LSBoost), and artificial neural network (ANN) techniques. We also use cycling Global Positioning System (GPS) data collected from 10 people (3 females and 7 males) to study cyclists' acceleration/deceleration behavior. Moreover, we develop a continuous rail transit simulator (RailSIM) intended for multi-modal energy-efficient routing applications. Finally, we propose a dynamic trip planning system that integrates ridesharing and public transit. The work done in this dissertation can help encouraging more people to move to more sustainable modes of transportation. / Doctor of Philosophy / As concerns about climate change increase, many people are calling for reductions in the use of fossil fuels and encouraging a shift to more sustainable and less polluting transportation modes. Cities and urban areas are more concerned because their population currently comprises over half of the world's population. Sustainable transportation modes such as cycling, walking, and use of public transit and electric vehicles can benefit the environment in many ways, including a reduction of toxic greenhouse gas (GHG) emissions and noise levels. In order to enhance the trend of using sustainable modes of transportation, tools, measures, and planning techniques similar to those used for vehicular transportation need to be developed. In this dissertation, we consider four problems in the context of different sustainable modes of transportation, namely, cycling, rail, public transit, and ridesharing. We develop different models to predict bike travel times in bike share systems (BSSs) using machine learning techniques. We also use cycling Global Positioning System (GPS) data collected from 10 people (3 females and 7 males) to study cyclists' acceleration/deceleration behavior. Moreover, we develop a continuous rail transit simulator (RailSIM) intended for multi-modal energy-efficient routing applications. Finally, we propose a dynamic trip planning system that integrates ridesharing and public transit. The work done in this dissertation can help encouraging more people to move to more sustainable modes of transportation.

Presently, the United States has yet to achieve the 1991 Intermodal Surface Transportation Efficiency Act's (ISTEA) goal of creating a seamless intermodal transportation system. In addition to the dearth of connections, the nation's poor transportation information systems limit intercity intermodal transportation. Travelers lack awareness of available transportation options and face too many separate portals for trip planning that both consume time and present inadequate information. This paper posits that the creation of an efficient and extensive web-based door-to-door intermodal trip planner can solve these problems. The proposed system will present travelers with a single portal to meet all their trip planning needs. Upon selecting specific trips, travelers can then decide to be directed to operators to make a purchase. The system will include operators from the major modal groups including intercity buses, intercity rail, commuter rail, transit, and airlines. It will also include taxis due to the disjointed nature of the US public transportation system and the need to connect users who are far from stations. The requirements to create this trip planner are explored, including the support systems, potential legal issues, and suitable entities for administration and management. A survey of 39 transportation system users revealed the existence of redundant and inadequate trip planners and that the lack of sufficient information on public transportation options is driving travelers to private vehicles for shorter distances even for those who prefer public means of transportation. Analysis of the costs and benefits of implementing the proposed system is drawn from interviews with key personnel within the transportation industry, and a review of nationwide trip planners in European countries. Finally, a roadmap is presented on how best to implement the system with inputs from both the public and private sector. Recommendations include the establishment of an industry-wide data standard, a national interagency database, and a cooperative structure that entices major players within each mode to participate in the system. Also suggested are incentives from the DOT and interested private sector members to encourage more operators to participate in the system. / Master of Science

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O desenvolvimento e utilização de novos materiais, mais leves e com propriedades mecânicas superiores aos atuais, se mostram extremamente importantes devido à redução de peso e consequentemente redução na emissão de gases poluentes que poderiam gerar. As ligas de Fe-Mn-C com elevados teores de Mn (20-30%) representam um desenvolvimento muito recente de aços austeníticos, que, através dos seus mecanismos diferenciados de deformação reúnem elevada resistência mecânica com grande ductilidade. Essa nova classe de materiais estruturais possibilita uma efetiva redução de custos na produção através do reduzido tempo de processamento (sem a necessidade de tratamentos térmicos especiais e de processamentos termomecânicos controlados). A soldagem é, atualmente, o mais importante processo de união de metais usado no setor industrial. Dentro da variada gama de processos de soldagem existentes, a soldagem por fricção e mistura mecânica (SFMM, em inglês: Friction Stir Welding - FSW) se destaca por ser um processo de união no estado sólido que apresenta uma série de vantagens sobre as tecnologias convencionais de soldagem por fusão. Do ponto de vista metalúrgico, uma das suas principais vantagens se manifesta justamente na junção de materiais dissimilares, visto que o grau de mistura de composições e as transformações de fases entre materiais incompatíveis podem ser minimizados. Outra vantagem é que há um refino de grão no cordão de solda comparado com a microestrutura fundida que se forma nos processos convencionais. Este trabalho teve como objetivo produzir em escala laboratorial os aços de alta liga ao manganês com efeito TRIP, avaliar o impacto da velocidade de rotação da ferramenta na soldagem por fricção e mistura mecânica e avaliar a microestrutura e propriedades mecânicas das juntas soldadas. A microestrutura das juntas soldadas caracterizou-se pela presença apenas da zona de mistura e do metal base, além da formação de \'anéis de cebola\' na zona de mistura, esta não mostrou sinais de transformação martensítica induzida por deformação e sofreu recristalização dinâmica para todas as velocidades de rotação investigadas com a formação de grãos refinados e com morfologia equiaxial. Os corpos de tração fraturaram todos nos metais de base, mostrando que as propriedades mecânicas da zona de mistura foram superiores à do metal base e que a variação de aporte térmico alcançada com a velocidade de rotação da ferramenta não comprometeu a qualidade das juntas soldadas. / The development and application of new light materials with superior mechanical properties is extremely important to weight reduction in vehicles and consequently reduction of greenhouse gases emission. The Fe-Mn-C steels with high Mn (20-30%) are a recent development of austenitic steels, which, due to their different mechanisms of deformation, possesses high strength and high ductility as well. In addition, this new type of structural steel allows an effective reduction of manufacturing costs due to its reduced processing time (it does not require special heat treatments and controlled thermo mechanical processing). Welding has been one of the most important processes for joining metals. Among the available welding processes, friction stir welding (FSW) is notable for being a solid state process with great advantages over the conventional welding methods. In the mettalurgical point of view, welding dissimilar materials is a significant advantage of FSW over the other process. The main reason is the reduction of mixture of material and phase transformations between the incompatible materials in the weld. Moreover, grain refinement is another advantage from the process. The present study aimed to produce laboratorial scale high Mn steels with TRIP effect, investigate the impact of tool speed ont the microstructure and mechanical properties of friction stir welded joints. The microstructure of the welded joints exhibited only the stirred zone (SZ) and the base material (BM), besides the presence of ´onion rings´ within the stirred zone. The SZ exhibited no signs of martensite suggesting that dynamic recrystallization have occurred for all the speed tested. Moreover, the grains in the SZ had equiaxial morphology and were significantly refined. The fracture of the tensile specimens occurred in the base material, bringing to light that the welding process was beneficial to the mechanical properties. Furthermore, the variation of heat input achieved with the speed did not compromise the quality of welded joints.

O desenvolvimento e utilização de novos materiais, mais leves e com propriedades mecânicas superiores aos atuais, se mostram extremamente importantes devido à redução de peso e consequentemente redução na emissão de gases poluentes que poderiam gerar. As ligas de Fe-Mn-C com elevados teores de Mn (20-30%) representam um desenvolvimento muito recente de aços austeníticos, que, através dos seus mecanismos diferenciados de deformação reúnem elevada resistência mecânica com grande ductilidade. Essa nova classe de materiais estruturais possibilita uma efetiva redução de custos na produção através do reduzido tempo de processamento (sem a necessidade de tratamentos térmicos especiais e de processamentos termomecânicos controlados). A soldagem é, atualmente, o mais importante processo de união de metais usado no setor industrial. Dentro da variada gama de processos de soldagem existentes, a soldagem por fricção e mistura mecânica (SFMM, em inglês: Friction Stir Welding - FSW) se destaca por ser um processo de união no estado sólido que apresenta uma série de vantagens sobre as tecnologias convencionais de soldagem por fusão. Do ponto de vista metalúrgico, uma das suas principais vantagens se manifesta justamente na junção de materiais dissimilares, visto que o grau de mistura de composições e as transformações de fases entre materiais incompatíveis podem ser minimizados. Outra vantagem é que há um refino de grão no cordão de solda comparado com a microestrutura fundida que se forma nos processos convencionais. Este trabalho teve como objetivo produzir em escala laboratorial os aços de alta liga ao manganês com efeito TRIP, avaliar o impacto da velocidade de rotação da ferramenta na soldagem por fricção e mistura mecânica e avaliar a microestrutura e propriedades mecânicas das juntas soldadas. A microestrutura das juntas soldadas caracterizou-se pela presença apenas da zona de mistura e do metal base, além da formação de \'anéis de cebola\' na zona de mistura, esta não mostrou sinais de transformação martensítica induzida por deformação e sofreu recristalização dinâmica para todas as velocidades de rotação investigadas com a formação de grãos refinados e com morfologia equiaxial. Os corpos de tração fraturaram todos nos metais de base, mostrando que as propriedades mecânicas da zona de mistura foram superiores à do metal base e que a variação de aporte térmico alcançada com a velocidade de rotação da ferramenta não comprometeu a qualidade das juntas soldadas. / The development and application of new light materials with superior mechanical properties is extremely important to weight reduction in vehicles and consequently reduction of greenhouse gases emission. The Fe-Mn-C steels with high Mn (20-30%) are a recent development of austenitic steels, which, due to their different mechanisms of deformation, possesses high strength and high ductility as well. In addition, this new type of structural steel allows an effective reduction of manufacturing costs due to its reduced processing time (it does not require special heat treatments and controlled thermo mechanical processing). Welding has been one of the most important processes for joining metals. Among the available welding processes, friction stir welding (FSW) is notable for being a solid state process with great advantages over the conventional welding methods. In the mettalurgical point of view, welding dissimilar materials is a significant advantage of FSW over the other process. The main reason is the reduction of mixture of material and phase transformations between the incompatible materials in the weld. Moreover, grain refinement is another advantage from the process. The present study aimed to produce laboratorial scale high Mn steels with TRIP effect, investigate the impact of tool speed ont the microstructure and mechanical properties of friction stir welded joints. The microstructure of the welded joints exhibited only the stirred zone (SZ) and the base material (BM), besides the presence of ´onion rings´ within the stirred zone. The SZ exhibited no signs of martensite suggesting that dynamic recrystallization have occurred for all the speed tested. Moreover, the grains in the SZ had equiaxial morphology and were significantly refined. The fracture of the tensile specimens occurred in the base material, bringing to light that the welding process was beneficial to the mechanical properties. Furthermore, the variation of heat input achieved with the speed did not compromise the quality of welded joints.

Traditionelle 3D-Anwendungsentwicklung für VR/AR verläuft in heterogenen Entwicklerteams unstrukturiert, ad hoc und ist fehlerbehaftet. Der präsentierte Roundtrip3D Entwicklungsprozess ermöglicht die iterativ inkrementelle 3D-Anwendungsentwicklung, wechselseitig auf Softwaremodell- und Implementierungsebene. Modelle fördern das gemeinsame Verständnis unter Projektbeteiligten und sichern durch generierte Schnittstellen gleichzeitiges Programmieren und 3D-Modellieren zu. Das Roundtrip3D Werkzeug ermittelt Inkonsistenzen zwischen vervollständigten 3D-Inhalten und Quelltexten auch für verschiedene Plattformen und visualisiert sie auf abstrakter Modellebene. Die gesamte Implementierung wird nicht simultan, sondern nach codegetriebener Entwicklung kontrolliert mit Softwaremodellen abgeglichen. Inkremente aus aktualisierten Softwaremodellen fließen in dann wieder zueinander konsistente Quelltexte und 3D-Inhalte ein. Der Roundtrip3D Entwicklungsprozess vereint dauerhaft Vorteile codegetriebener mit modellgetriebener 3D-Anwendungsentwicklung und fördert strukturiertes Vorgehen im agilen Umfeld.

Lors d’un recuit inter-critique d’un acier dit « Medium Manganèse », dont la teneur en Mn est située entre 4 et 12 %, avec une microstructure initiale complètement martensitique, la formation de l’austénite obéit à un mécanisme spécifique qui porte le nom d'ART - « Austenite Reverted Transformation » (transformation inverse de l’austénite). L’objectif de ce travail de thèse était d’étudier et de modéliser les évolutions microstructurales en lien avec les propriétés mécaniques lors d’un recuit ART. Il a été déterminé que la microstructure finale se compose de phases de nature (ferrite, austénite résiduelle et martensite de trempe) et morphologie (en forme d’aiguille et polygonale) différentes. Une attention particulière a été accordée aux cinétiques de dissolution des carbures et de formation de l’austénite. Une vision complète de ces processus a été construite. En outre, le mécanisme de stabilisation de l’austénite résiduelle à la température ambiante a été étudié et discuté. Enfin, des essais de traction ont été réalisés afin d’évaluer le comportement mécanique de l’acier après différents recuits ART et établir le lien avec la microstructure. Une analyse plus détaillée du comportement de chaque constituant de la microstructure a été effectuée. A l'issue de cette thèse, un modèle complet est disponible pour calculer les courbes de contrainte vraie - déformation vraie d’un acier Medium Mn / During the intercritical annealing of fully martensitic Medium Mn steel, containing from 4 to 12 wt.% Mn, the formation of austenite happens through the so-called “Austenite Reverted Transformation” (ART) mechanism. In this PhD work, the evolution of both microstructure and tensile properties was studied as a function of holding time in the intercritical domain. The microstructure evolution was studied using a double experimental and modeling approach. The final microstructure contained phases of different natures (ferrite (annealed martensite), retained austenite and fresh martensite) and of different morphologies (lath-like and polygonal). A particular attention was paid to the kinetics of austenite formation in connection with cementite dissolution and to the morphology of the phases. A mechanism was proposed to describe the formation of such microstructure. The critical factors controlling thermal austenite stability, including both chemical and size effects, were determined and discussed, based on the analysis of the retained austenite time-evolution. At last, tensile properties of the steel were measured as a function of holding time and the relation between microstructure and mechanical behavior was analyzed. Advanced analysis of the individual behavior of the three major constituents was performed. As a final output of this work, a complete model for predicting the true-stress versus true-strain curves of medium Mn steels was proposed

Securing of electrical devices is important not only to protect against destruction under the effects of electric current, but also for protection of people or animals against electric shock. With increasing of living standards goes hand in hand increasing of the electricity consumption. Therefore In the grid of low voltage, there are increasing short-circuit currents. With improving technology is posed considerable demand on the performance, security and switching capacity of circuit breakers. This thesis is oriented on development of thermal and electromagnetic switch of circuit breaker on which is put a big demand in development of new types of circuit breakers. The thesis is interesting because of comprehensive use of circuits’ breakers since it can be used in AC and DC networks with frequency of 50 Hz and 400 Hz.

Using circuit breakers as devices for protecting the circuit, equipment, property, and not least the people is an important part of the generation, transmission and distribution of electricity. This puts high demands on the design of complex devices such as circuit breakers. To ensure proper function is one of many parts and that is the trip unit. Trip unit is used to evaluate the current flowing through the breaker and respond to undesirable overcurrent. For these reasons, this work deals with electromagnetic analysis - specifically thermal magnetic trip unit. The focus will be on improving the actual situation and finding more suitable design solutions.