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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Developing a GIS-based traffic control planning tool

Karl, Andrew W. 24 August 2010 (has links)
The purpose of this study is to assist TxDOT engineers in the field of traffic control planning. This is to be done via the creation of a Geographic Information System (GIS) based tool. By bringing together information about TxDOT’s on-system roadways’ geographical locations, traffic demands, and capacities, one aggregate database has been established. Using the tools of GIS, Microsoft Excel, Microsoft Access, and VBA programming, a static clickable interface has been constructed. It enables users to access properties for any selected roadway link they desire. Expansion of the product to ArcIMS is ongoing to allow easy access for end users via the internet. / text
172

Psychodiagnostika v personální psychologii - výběrové řízení na pozici řídícího letového provozu. (Analýza úspěšnosti uchazeče ve výcviku na základě výsledků vybraných testů). / Psychodiagnostics in personnel psychology - Selection process for a position of Air traffic controller. (Analysis of success of candidate in training based on results of selected tests).

Šustíková, Klára January 2011 (has links)
The first purpose of this study was to map the field of psychodiagnostic methods in the selection process for the position of Air traffic controller in selected countries in Central Europe. The second one was to see how differs the results of FEAST and psychological testing among different groups of candidates in relation to their success in training. This is a quantitative research. The method used in collecting data was the analysis of results of selected tests for individual candidates. The research was realized at 93 candidates who successfully completed the selection procedure for the position of the Air traffic controller at ŘLP Čr from 2005 - 2009. The data were analyzed using SPSS statistical program. In the vast majority of performance or personality tests did any statistically significant difference was not found between the group of successful and unsuccessful candidates in training. A statistically significant difference was detected in the scale "Noticed matches" in the FEAST test battery, where unsuccessful candidates scored above. Another one was discovered in the test CAQ in factor Q1: Radicalism, where successful candidates achieved lower scores than the unsuccessful. We believe that candidates who manage the selection procedure are so good that it is not possible their further...
173

Avaliação de risco em operações de pouso de aeronaves em pistas paralelas utilizando procedimentos e técnicas CSPA. / Risk assessment in aircraft landing operations in parallel runways using CSPA procedures and techniques.

Matsuyama, Rafael Tsuji 13 June 2011 (has links)
Historicamente, os sistemas de tráfego aéreo incorporaram níveis de automação nas atividades de controle do espaço aéreo com o intuito de atender à crescente demanda por serviços aéreos e de melhorar os níveis de segurança nos procedimentos de voo. Com o crescimento expressivo previsto para os próximos anos, devido ao aumento nos números de voos e de usuários, as opções tradicionais de expansão da malha aérea e / ou construção de novos aeroportos se tornaram onerosas economicamente, tornando necessária a adoção de alternativas, tais como as técnicas / procedimentos para pousos em pistas paralelas, como forma de aproveitar parte da atual infraestrutura aeroportuária existente, sem a necessidade de enormes aportes financeiros. Para avaliar a viabilidade de projetos de pousos simultâneos em pistas paralelas, um dos fatores importantes a serem analisados é o da avaliação do risco de colisão entre aeronaves associado durante esses procedimentos. Nesse cenário, este trabalho de pesquisa propõe uma extensão no modelo de avaliação de segurança de Ogata para procedimentos de pouso em pistas paralelas, considerando que o modelo original tem o objetivo de medir o nível de risco associado somente para operações de pouso convencionais em pistas paralelas. A extensão deste modelo ocorre no sentido de também permitir a simulação em outros cenários distintos de pouso, o que torna possível tanto a realização de comparativos entre técnicas / procedimentos utilizadas em operações de pouso em pistas paralelas, quanto a avaliação do nível de risco associado. Este modelo estendido de segurança utiliza o método de Monte Carlo, da mesma forma que o original, em que um número elevado de simulações de cenários possíveis de pousos em pistas paralelas é avaliado. Com os resultados obtidos, é analisado o impacto da variação da distância entre as pistas na segurança de pousos em pistas paralelas. / Historically, air traffic control systems have incorporated some levels of automation to manage procedures of airspace control in order to meet the growing demand for air transportation services and to improve levels of safety in flight procedures. With significant growth expected in the coming years due to an increase in numbers of flights and passengers, the traditional options of expanding the air traffic network and / or construction of new airports have become economically burdensome, requiring the adoption of alternatives such as techniques / procedures for landings on parallel runways as a way of taking advantage of part of the current airport infrastructure, without requiring enormous financial contributions. To assess the feasibility of projects of landing in parallel runways, one of the important factors to be analyzed is the evaluation of the risk of collision between aircraft, associated to these procedures. In this scenario, this research proposes to extend the Ogata safety assessment model in procedures for landing on parallel runways, whereas the original model aims to measure the level of risk associated only with conventional landing operations in parallel runways. The extension of this model occurs in order to allow the simulation of different landing scenarios, which makes possible both the conduct of comparative techniques / procedures used in landing operations on parallel runways, such as the risk level assessment. This model uses the Monte Carlo simulation, the same as the original model, in which a large number of simulations of possible scenarios for landings on parallel runways are evaluated. With these results, it studies the impact of the change of distance between lanes on the safety of aircraft landing on parallel runways.
174

Modelo de rede neural bioinspirada para o controle do trânsito urbano. / Biologically-inspired neural network model for urban traffic control.

Castro, Guilherme Barros 01 February 2017 (has links)
Congestionamentos no trânsito urbano são uma preocupação principal em grandes cidades pelo mundo, devido a seus impactos negativos multifacetados na saúde humana, no meio ambiente e na economia. A urbanização crescente, e seu consequente aumento no volume do trânsito, causam ainda mais congestionamentos por causa do ritmo lento - e, em alguns casos, inexistente - das melhoras na infraestrutura urbana. Uma solução com bom custo-benefício para reduzir o tempo médio de viagem dos veículos e prevenir os congestionamentos é o controle do trânsito urbano. No entanto, a maior parte das abordagens de controle do trânsito urbano adota um ciclo de controle fixo, o qual limita o desempenho de controle devido à consequente inabilidade de agir quando necessário. Ao contrário dessas abordagens, esse trabalho propõe uma rede neural bioinspirada que monitora o estado do sistema de forma contínua e é capaz de agir em qualquer momento. A rede neural bioinspirada proposta adota plasticidade intrínseca e inibição lateral para gerar uma competição natural entre os neurônios, a qual determina quais semáforos devem ser ativados em cada momento. Além disso, interneurônios inibitórios são adotados para coordenar intersecções vizinhas e melhorar os fluxos de veículos. Devido à grande quantidade de possíveis combinações dos parâmetros, um método para determinar o comportamento do modelo de acordo com as características intrínsecas da rede neural bioinspirada também é proposto. A convergência e a estabilidade do modelo proposto são avaliadas por seus pontos-fixos e autovalores, respectivamente. Ademais, o tempo de processamento e a complexidade computacional da rede neural bioinspirada também são avaliados. Por fim, o desempenho do modelo para diferentes demandas de veículos e situações do trânsito é avaliado com um simulador de mobilidade urbana e comparado a um método de controle adaptativo. / Traffic congestions are a major concern for big cities around the world due to its multifaceted negative impacts on human health, the environment and the economy. Growing urbanization, and the consequent increase in traffic volume, causes even more traffic congestions due to the slow-paced - and, in some cases, non-existing - improvements in the urban traffic infrastructure. A cost-effective solution to reduce vehicle travel times and prevent traffic congestions is traffic signal control. However, most approaches to traffic signal control adopt a fixed control cycle, which limits control performance due to the consequent inability to act when necessary. Contrary to these approaches, this work proposes a biologically-inspired neural network that monitors the system state continuously and can act upon it at any moment. The biologically-inspired neural network proposed adopts intrinsic plasticity and lateral inhibition to generate natural competition among neurons, determining which semaphores should be active at each moment. Furthermore, inhibitory interneurons are also adopted to coordinate neighboring intersections and to improve vehicle flows. Due to the large number of parameter combinations, a method to determine the model behavior according to the intrinsic characteristics of the biologically-inspired neural network is also proposed. Model convergence and stability are evaluated by its fixed-points and eigenvalues, respectively. Moreover, the computation time and computational complexity of the biologically-inspired neural network are also evaluated. Finally, the model performance for different vehicle demands and traffic situations is evaluated with a simulator of urban mobility and compared to an adaptive control method.
175

Clutter Measurement and Reduction for Enhanced Information Visualization

Lloyd, Natasha 12 January 2006 (has links)
The effectiveness of information visualization largely depends on the ease and accuracy with which users can access the information. Visual clutter in a display can detract from a user's ability to properly read the information. An ideal visualization needs to maximize the visibility of patterns and structure and minimize the clutter present. Thus far, there has been surprisingly little work done in finding quantitative ways to measure clutter in information visualizations. The goal of this project was to create clutter measurement and reduction techniques that minimize the presence of visual clutter and maximize a user's ability to accurately read the data. These methods were tested and evaluated on a number of visualizations depicting domestic air traffic data.
176

Modelo de rede neural bioinspirada para o controle do trânsito urbano. / Biologically-inspired neural network model for urban traffic control.

Guilherme Barros Castro 01 February 2017 (has links)
Congestionamentos no trânsito urbano são uma preocupação principal em grandes cidades pelo mundo, devido a seus impactos negativos multifacetados na saúde humana, no meio ambiente e na economia. A urbanização crescente, e seu consequente aumento no volume do trânsito, causam ainda mais congestionamentos por causa do ritmo lento - e, em alguns casos, inexistente - das melhoras na infraestrutura urbana. Uma solução com bom custo-benefício para reduzir o tempo médio de viagem dos veículos e prevenir os congestionamentos é o controle do trânsito urbano. No entanto, a maior parte das abordagens de controle do trânsito urbano adota um ciclo de controle fixo, o qual limita o desempenho de controle devido à consequente inabilidade de agir quando necessário. Ao contrário dessas abordagens, esse trabalho propõe uma rede neural bioinspirada que monitora o estado do sistema de forma contínua e é capaz de agir em qualquer momento. A rede neural bioinspirada proposta adota plasticidade intrínseca e inibição lateral para gerar uma competição natural entre os neurônios, a qual determina quais semáforos devem ser ativados em cada momento. Além disso, interneurônios inibitórios são adotados para coordenar intersecções vizinhas e melhorar os fluxos de veículos. Devido à grande quantidade de possíveis combinações dos parâmetros, um método para determinar o comportamento do modelo de acordo com as características intrínsecas da rede neural bioinspirada também é proposto. A convergência e a estabilidade do modelo proposto são avaliadas por seus pontos-fixos e autovalores, respectivamente. Ademais, o tempo de processamento e a complexidade computacional da rede neural bioinspirada também são avaliados. Por fim, o desempenho do modelo para diferentes demandas de veículos e situações do trânsito é avaliado com um simulador de mobilidade urbana e comparado a um método de controle adaptativo. / Traffic congestions are a major concern for big cities around the world due to its multifaceted negative impacts on human health, the environment and the economy. Growing urbanization, and the consequent increase in traffic volume, causes even more traffic congestions due to the slow-paced - and, in some cases, non-existing - improvements in the urban traffic infrastructure. A cost-effective solution to reduce vehicle travel times and prevent traffic congestions is traffic signal control. However, most approaches to traffic signal control adopt a fixed control cycle, which limits control performance due to the consequent inability to act when necessary. Contrary to these approaches, this work proposes a biologically-inspired neural network that monitors the system state continuously and can act upon it at any moment. The biologically-inspired neural network proposed adopts intrinsic plasticity and lateral inhibition to generate natural competition among neurons, determining which semaphores should be active at each moment. Furthermore, inhibitory interneurons are also adopted to coordinate neighboring intersections and to improve vehicle flows. Due to the large number of parameter combinations, a method to determine the model behavior according to the intrinsic characteristics of the biologically-inspired neural network is also proposed. Model convergence and stability are evaluated by its fixed-points and eigenvalues, respectively. Moreover, the computation time and computational complexity of the biologically-inspired neural network are also evaluated. Finally, the model performance for different vehicle demands and traffic situations is evaluated with a simulator of urban mobility and compared to an adaptive control method.
177

Avaliação de risco em operações de pouso de aeronaves em pistas paralelas utilizando procedimentos e técnicas CSPA. / Risk assessment in aircraft landing operations in parallel runways using CSPA procedures and techniques.

Rafael Tsuji Matsuyama 13 June 2011 (has links)
Historicamente, os sistemas de tráfego aéreo incorporaram níveis de automação nas atividades de controle do espaço aéreo com o intuito de atender à crescente demanda por serviços aéreos e de melhorar os níveis de segurança nos procedimentos de voo. Com o crescimento expressivo previsto para os próximos anos, devido ao aumento nos números de voos e de usuários, as opções tradicionais de expansão da malha aérea e / ou construção de novos aeroportos se tornaram onerosas economicamente, tornando necessária a adoção de alternativas, tais como as técnicas / procedimentos para pousos em pistas paralelas, como forma de aproveitar parte da atual infraestrutura aeroportuária existente, sem a necessidade de enormes aportes financeiros. Para avaliar a viabilidade de projetos de pousos simultâneos em pistas paralelas, um dos fatores importantes a serem analisados é o da avaliação do risco de colisão entre aeronaves associado durante esses procedimentos. Nesse cenário, este trabalho de pesquisa propõe uma extensão no modelo de avaliação de segurança de Ogata para procedimentos de pouso em pistas paralelas, considerando que o modelo original tem o objetivo de medir o nível de risco associado somente para operações de pouso convencionais em pistas paralelas. A extensão deste modelo ocorre no sentido de também permitir a simulação em outros cenários distintos de pouso, o que torna possível tanto a realização de comparativos entre técnicas / procedimentos utilizadas em operações de pouso em pistas paralelas, quanto a avaliação do nível de risco associado. Este modelo estendido de segurança utiliza o método de Monte Carlo, da mesma forma que o original, em que um número elevado de simulações de cenários possíveis de pousos em pistas paralelas é avaliado. Com os resultados obtidos, é analisado o impacto da variação da distância entre as pistas na segurança de pousos em pistas paralelas. / Historically, air traffic control systems have incorporated some levels of automation to manage procedures of airspace control in order to meet the growing demand for air transportation services and to improve levels of safety in flight procedures. With significant growth expected in the coming years due to an increase in numbers of flights and passengers, the traditional options of expanding the air traffic network and / or construction of new airports have become economically burdensome, requiring the adoption of alternatives such as techniques / procedures for landings on parallel runways as a way of taking advantage of part of the current airport infrastructure, without requiring enormous financial contributions. To assess the feasibility of projects of landing in parallel runways, one of the important factors to be analyzed is the evaluation of the risk of collision between aircraft, associated to these procedures. In this scenario, this research proposes to extend the Ogata safety assessment model in procedures for landing on parallel runways, whereas the original model aims to measure the level of risk associated only with conventional landing operations in parallel runways. The extension of this model occurs in order to allow the simulation of different landing scenarios, which makes possible both the conduct of comparative techniques / procedures used in landing operations on parallel runways, such as the risk level assessment. This model uses the Monte Carlo simulation, the same as the original model, in which a large number of simulations of possible scenarios for landings on parallel runways are evaluated. With these results, it studies the impact of the change of distance between lanes on the safety of aircraft landing on parallel runways.
178

Evaluation of rumble strips at rural stop-controlled intersections in Texas

Thompson, Tyrell D. 01 November 2005 (has links)
Major safety concerns are present at rural high speed intersections. When long uninterrupted tangents are located near rural intersections, the drivers can become inattentive to upcoming decision points. Traffic control devices could aid in mitigating these occurrences by warning drivers of upcoming decision points. One such device is transverse rumble strips, which act to provide motorists with an audible and tactile warning that their vehicle is approaching a decision point of critical importance to safety. The objective of this research was to determine if the presence of transverse rumble strips were an effective warning device for drivers approaching rural stop-controlled intersections. To evaluate the effectiveness of transverse rumble strips, vehicle speeds were measured at three locations along the approach to an intersection both before and after the installation of rumble strips. Vehicle speeds were measured at nine rural stop-controlled intersection sites in Texas. Overall, the installation of rumble strips generally produced small, but statistically significant (p ? 0.05), reductions in traffic speeds. There were some negative driver behavioral impacts (i.e., speed increases) that occurred after the installation of rumble strips. There were a few instances where speed change reductions of greater than 1 mph occurred, however, the overall trend was that speed change reductions were equal to or less than 1 mph. Although the rumble strips did not produce meaningful reductions in traffic speeds, they should still be considered based upon previous accident reductions and minimal installation costs.
179

Evaluation of rumble strips at rural stop-controlled intersections in Texas

Thompson, Tyrell D. 01 November 2005 (has links)
Major safety concerns are present at rural high speed intersections. When long uninterrupted tangents are located near rural intersections, the drivers can become inattentive to upcoming decision points. Traffic control devices could aid in mitigating these occurrences by warning drivers of upcoming decision points. One such device is transverse rumble strips, which act to provide motorists with an audible and tactile warning that their vehicle is approaching a decision point of critical importance to safety. The objective of this research was to determine if the presence of transverse rumble strips were an effective warning device for drivers approaching rural stop-controlled intersections. To evaluate the effectiveness of transverse rumble strips, vehicle speeds were measured at three locations along the approach to an intersection both before and after the installation of rumble strips. Vehicle speeds were measured at nine rural stop-controlled intersection sites in Texas. Overall, the installation of rumble strips generally produced small, but statistically significant (p ? 0.05), reductions in traffic speeds. There were some negative driver behavioral impacts (i.e., speed increases) that occurred after the installation of rumble strips. There were a few instances where speed change reductions of greater than 1 mph occurred, however, the overall trend was that speed change reductions were equal to or less than 1 mph. Although the rumble strips did not produce meaningful reductions in traffic speeds, they should still be considered based upon previous accident reductions and minimal installation costs.
180

Stochastic programming approaches to air traffic flow management under the uncertainty of weather

Chang, Yu-Heng 26 October 2010 (has links)
As air traffic congestion grows, air traffic flow management (ATFM) is becoming a great concern. ATFM deals with air traffic and the efficient utilization of the airport and airspace. Air traffic efficiency is heavily influenced by unanticipated factors, or uncertainties, which can come from several sources such as mechanical breakdown; however, weather is the main unavoidable cause of uncertainty. Because weather is unpredictable, it poses a critical challenge for ATFM in current airport and airspace operations. Convective weather results in congestion at airports as well as in airspace sectors. During times of congestion, the decision as how and when to send aircraft toward an airspace sector in the presence of weather is difficult. To approach this problem, we first propose a two-stage stochastic integer program by emphasizing a given single sector. By considering ground delay, cancellation, and cruise speed for each flight on the ground in the first stage, as well as air holding and diversion recourse actions for each flight in the air in the second stage, our model determines how aircraft are sent toward a sector under the uncertainty of weather. However, due to the large number of weather scenarios, the model is intractable in practice. To overcome the intractability, we suggest a rolling horizon method to solve the problem to near optimal. Lagrangian relaxation and subgradient method are used to justify the rolling horizon method. Since the rolling horizon method can be solved in real time, we can apply it to actual aircraft schedules to reduce the costs incurred on the ground as well as in airspace. We then extend our two-stage model to a multistage stochastic program, which increases the number of possible weather realizations and results a more efficient schedule in terms of costs. The rolling horizon method as well as Lagrangian relaxation and subgradient method are applied to this multistage model. An overall comparison among the previously described methodologies are presented.

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