• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 70
  • 17
  • 16
  • 13
  • 5
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 176
  • 56
  • 40
  • 37
  • 34
  • 33
  • 29
  • 21
  • 16
  • 15
  • 14
  • 14
  • 14
  • 13
  • 11
  • 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.
161

Uncontrolled intersection coordination of the autonomous vehicle based on multi-agent reinforcement learning.

McSey, Isaac Arnold January 2023 (has links)
This study explores the application of multi-agent reinforcement learning (MARL) to enhance the decision-making, safety, and passenger comfort of Autonomous Vehicles (AVs)at uncontrolled intersections. The research aims to assess the potential of MARL in modeling multiple agents interacting within a shared environment, reflecting real-world situations where AVs interact with multiple actors. The findings suggest that AVs trained using aMARL approach with global experiences can better navigate intersection scenarios than AVs trained on local (individual) experiences. This capability is a critical precursor to achieving Level 5 autonomy, where vehicles are expected to manage all aspects of the driving task under all conditions. The research contributes to the ongoing discourse on enhancing autonomous vehicle technology through multi-agent reinforcement learning and informs the development of sophisticated training methodologies for autonomous driving.
162

Visualisation d'une carte écologique complexe : contribution de la cartographie assistée par ordinateur ; traitement et communication graphique des données d'un projet d'aménagement routier

Saia, Marc-André 11 April 2018 (has links)
Québec Université Laval, Bibliothèque 2016
163

Proposta de um método transdisciplinar de pesquisa e sua aplicação na tabacologia, na construção do Teste Projetivo e Transdisciplinar de Tabagismo (TPTT) e na pré-testagem formal deste instrumento / Proposal of a transdisciplinary method of research and its application in tabacology, in the construction of the projective and transdisciplinary test of tabagism (PTTT) and in the formal pre-testing of this instrument

Keppe, Marc André da Rocha 16 April 2014 (has links)
Este trabalho propõe um método transdisciplinar de pesquisa para servir como modelo para estudos, investigações e pesquisas transdisciplinares, utilizando um critério denominado: estatístico-matemático-filosófico. Este método transdisciplinar, denominado método das intersecções foi aplicado: na reconstrução de alguns conceitos tabacológicos; na revisão de pressupostos da tabacologia; em descobertas que trazem novas hipóteses sobre a origem do tabaco e de sua utilização; na investigação sobre a utilização saudável e sobre o uso patológico do tabaco; nos diagnósticos, prognósticos e tratamentos bioecopsicosocioespirituais do tabagismo; na construção do Teste Projetivo e Transdisciplinar de Tabagismo (TPTT) e na prétestagem formal deste instrumento. Algumas conclusões destes estudos podem ser sintetizadas das seguintes formas: 1ª) Algumas descobertas científicas apontam para a origem do tabaco, e de sua utilização, a partir de, pelo menos, 3.200 anos atrás, na civilização egípcia; 2ª) Além da utilização patológica, denominada tabagismo, existem formas saudáveis de consumo do tabaco; 3ª) Os diagnósticos, prognósticos e formas de tratamento do tabagismo podem ser realizados de acordo com o modelo bioecopsicosocioespiritual, que considera as perspectivas: biológica, ecológica, psicológica, sociológica e espiritualista, ampliando a observação e a atuação diante deste problema. 4ª) A pré-testagem formal do Teste Projetivo e Transdisciplinar de Tabagismo (TPTT) demonstrou a possibilidade deste instrumento se constituir em ferramenta útil para se descobrir o índice geral de tabagismo, bem como para se encontrar as perspectivas preponderantes para tal compulsão ou consumo exagerado, e também as motivações que levam à tal utilização do tabaco / This dissertation suggest a transdisciplinary method of research in order to serve as a model in transdisciplinary studies, investigations and researches, utilizing a criterion called: statistics-mathematics-philosophical. This transdisciplinary method called intersections method was applied: in the reconstruction of some concepts of tabacology; in the revision of some assumptions in tabacology; in discoveries that brings new hypothesis about the origin of tobacco and its uses; in the investigation about the healthy and pathologic use of tobacco; in the bioecopsychosocialspiritual diagnostics, forecasts and treatments of tabagism; in the construction of the Projective and Transdisciplinary Test of Tabagism (PTTT) and in the formal pre-testing of this instrument. Some conclusions of these researches can be summarized as follows: 1ª)Some scientific discoveries indicates an origin of tobacco and its uses from 3.200 years ago, at least, in egyptian civilization. 2ª) Besides of the pathologic use called tabagism there are healthy ways of consumption of tobacco. 3ª) The diagnostics, forecasts and treatments of tabagism can be done following the bioecopsychosocialspiritual model that consider the perspectives: biological, ecological, psychological, sociological e spiritualistic, extending the observation and acting over this problem. 4ª) The formal pre-testing of the Projective and Transdisciplinary Test of Tabagism (PTTT) show the possibility of this instrument became a useful tool to find out the general index of tabagism and to achieve the prevalent perspective of this compulsion or overdose and the motivations in order to use tobacco in this way
164

Equations fonctionnelles pour une fonction sur<br />un espace singulier

Torrelli, Tristan 06 November 1998 (has links) (PDF)
Afin d'étendre à un cadre singulier des résultats de la théorie du polynôme de Bernstein-Sato, nous étudions ici les polynômes de Bernstein d'une fonction analytique f associée aux sections du module de cohomologie locale algébrique R à support une intersection complète locale X définie par un morphisme analytique g. En effet, il résulte de la construction algébrique des cycles évanescents que les racines de ces polynômes sont étroitement liées aux valeurs propres de la monodromie locale de f sur X.<br /><br />Après avoir donné des résultats sur les polynômes de Bernstein associés aux sections d'un D-Module holonome, nous faisons l'étude du cas g lisse à l'origine, puis f lisse et X hypersurface. Nous étudions ensuite l'existence de polynômes de Bernstein génériques et relatifs des sections de R associées à une déformation analytique, reliant ces questions à la géométrie d'espaces conormaux.<br /><br />Reprenant des idées de B. Malgrange, nous donnons ensuite une construction adaptée à l'étude des polynômes de Bernstein des sections de R lorsque les morphismes g et (f,g) définissent des intersections complètes à singularité isolée à l'origine. Cette construction impose notamment la quasi-homogénéité de g et nécessite des calculs d'annulateurs. Nous nous consacrons enfin aux calculs de polynômes de Bernstein basés sur ces résultats. Nous donnons d'abord un algorithme de calcul lorsque en plus des hypothèses adéquates, nous supposons que la partie initiale de f définit une singularité isolée sur X. Quand de plus f est quasi-homogène, nous obtenons des formules explicites. Nous terminons notre étude par des exemples de calculs lorsque X est un cône quadratique non dégénéré.
165

Fuzzy logic for improved dilemma zone identification : a simulator study

Moore, Derek (Derek Adam) 15 June 2012 (has links)
The Type-II dilemma zone refers to the segment of roadway approaching an intersection where drivers have difficulty deciding to stop or proceed through at the onset of the circular yellow (CY) indication. Signalized intersection safety can be improved when the dilemma zone is correctly identified and steps are taken to reduce the likelihood that vehicles are caught in it. This research employs driving simulation as a means to collect driver response data at the onset of the CY indication to better understand and describe the dilemma zone. The data obtained was compared against that from previous experiments documented in the literature and the evidence suggests that driving simulator data is valid for describing driver behavior under the given conditions. Fuzzy logic was proposed as a tool to model driver behavior in the dilemma zone, and three such models were developed to describe driver behavior as it relates to the speed and position of the vehicle. These models were shown to be consistent with previous research on this subject and were able to predict driver behavior with up to 90% accuracy. / Graduation date: 2013
166

Risk Estimation at Road Intersections for Connected Vehicle Safety Applications

Lef��vre, St��phanie 22 October 2012 (has links) (PDF)
Les intersections sont les zones les plus dangereuses du r��seau routier. Les ��tudes d'accidentologie montrent que la plupart des accidents aux intersections sont caus��s par des erreurs des conducteurs, et qu'une majorit�� d'accidents pourraient ��tre ��vit��s gr��ce �� l'utilisation de syst��mes d'aide �� la conduite. Dans ce cadre, les communications inter-v��hiculaire sont une technologie particuli��rement prometteuse. Le partage d'informations entre les v��hicules via des liens sans fil permet �� chaque v��hicule de percevoir son environnement au-del�� des limites de champ de vision de ses capteurs embarqu��s. Il en r��sulte une repr��sentation de l'environnement plus ��tendue dans l'espace et dans le temps, ce qui am��liore la compr��hension de situation et permet d'anticiper le danger. Cette th��se aborde le probl��me de l'estimation du risque sous un angle nouveau : elle propose une structure de raisonnement pour analyser les sc��nes routi��res et le risque de collision �� un niveau s��mantique, contrairement aux approches classiques qui raisonnent au niveau des trajectoires. Le risque est calcul�� en estimant les intentions des conducteurs et en d��tectant les conflits, sans avoir �� pr��dire les trajectoires futures des v��hicules. Plus pr��cis��ment, la d��tection des situations dangereuses est bas��e sur la comparaison entre ce que les conducteurs ont l'intention de faire et ce que les conducteurs devraient faire d'apr��s les r��gles de la circulation. Ce raisonnement est r��alis�� de mani��re probabiliste afin de prendre en compte les incertitudes sur les mesures capteur et les ambig��it��s sur l'interpr��tation de la sc��ne. En th��orie ce raisonnement peut ��tre appliqu�� �� tout type de sc��ne routi��re ; dans cette th��se nous pr��sentons son application aux intersections. Le mod��le propos�� prend en compte l'influence que la man��uvre d'un v��hicule exerce sur la man��uvre des autres v��hicules. Il incorpore aussi des informations sur l'influence de la g��om��trie et topologie de l'intersection sur le comportement d'un v��hicule. L'approche propos��e a ��t�� valid��e par des tests en environnement r��el avec des v��hicules communicants, ainsi qu'en simulation. Les r��sultats montrent que l'algorithme est capable de d��tecter les situations dangereuses et qu'il est compatible avec des applications s��curitaires temps-r��el.
167

Proposta de um método transdisciplinar de pesquisa e sua aplicação na tabacologia, na construção do Teste Projetivo e Transdisciplinar de Tabagismo (TPTT) e na pré-testagem formal deste instrumento / Proposal of a transdisciplinary method of research and its application in tabacology, in the construction of the projective and transdisciplinary test of tabagism (PTTT) and in the formal pre-testing of this instrument

Marc André da Rocha Keppe 16 April 2014 (has links)
Este trabalho propõe um método transdisciplinar de pesquisa para servir como modelo para estudos, investigações e pesquisas transdisciplinares, utilizando um critério denominado: estatístico-matemático-filosófico. Este método transdisciplinar, denominado método das intersecções foi aplicado: na reconstrução de alguns conceitos tabacológicos; na revisão de pressupostos da tabacologia; em descobertas que trazem novas hipóteses sobre a origem do tabaco e de sua utilização; na investigação sobre a utilização saudável e sobre o uso patológico do tabaco; nos diagnósticos, prognósticos e tratamentos bioecopsicosocioespirituais do tabagismo; na construção do Teste Projetivo e Transdisciplinar de Tabagismo (TPTT) e na prétestagem formal deste instrumento. Algumas conclusões destes estudos podem ser sintetizadas das seguintes formas: 1ª) Algumas descobertas científicas apontam para a origem do tabaco, e de sua utilização, a partir de, pelo menos, 3.200 anos atrás, na civilização egípcia; 2ª) Além da utilização patológica, denominada tabagismo, existem formas saudáveis de consumo do tabaco; 3ª) Os diagnósticos, prognósticos e formas de tratamento do tabagismo podem ser realizados de acordo com o modelo bioecopsicosocioespiritual, que considera as perspectivas: biológica, ecológica, psicológica, sociológica e espiritualista, ampliando a observação e a atuação diante deste problema. 4ª) A pré-testagem formal do Teste Projetivo e Transdisciplinar de Tabagismo (TPTT) demonstrou a possibilidade deste instrumento se constituir em ferramenta útil para se descobrir o índice geral de tabagismo, bem como para se encontrar as perspectivas preponderantes para tal compulsão ou consumo exagerado, e também as motivações que levam à tal utilização do tabaco / This dissertation suggest a transdisciplinary method of research in order to serve as a model in transdisciplinary studies, investigations and researches, utilizing a criterion called: statistics-mathematics-philosophical. This transdisciplinary method called intersections method was applied: in the reconstruction of some concepts of tabacology; in the revision of some assumptions in tabacology; in discoveries that brings new hypothesis about the origin of tobacco and its uses; in the investigation about the healthy and pathologic use of tobacco; in the bioecopsychosocialspiritual diagnostics, forecasts and treatments of tabagism; in the construction of the Projective and Transdisciplinary Test of Tabagism (PTTT) and in the formal pre-testing of this instrument. Some conclusions of these researches can be summarized as follows: 1ª)Some scientific discoveries indicates an origin of tobacco and its uses from 3.200 years ago, at least, in egyptian civilization. 2ª) Besides of the pathologic use called tabagism there are healthy ways of consumption of tobacco. 3ª) The diagnostics, forecasts and treatments of tabagism can be done following the bioecopsychosocialspiritual model that consider the perspectives: biological, ecological, psychological, sociological e spiritualistic, extending the observation and acting over this problem. 4ª) The formal pre-testing of the Projective and Transdisciplinary Test of Tabagism (PTTT) show the possibility of this instrument became a useful tool to find out the general index of tabagism and to achieve the prevalent perspective of this compulsion or overdose and the motivations in order to use tobacco in this way
168

Análisis experimental de intersecciones amplias tipo cruz en base a la metodología de flujo continuo. Caso avenida República de Venezuela con la avenida Aurelio García y García / Experimental analysis of large cross intersections based on the continuous flow methodology. Case of the Republic avenue of Venezuela with the avenue Aurelio García y García

Chuco Pozo, Betsi Suliana, Perez Ramos, Carlos Edgar 14 October 2020 (has links)
Las ciudades altamente congestionadas requieren de una óptima gestión de la movilidad urbana. Muchas de estas ciudades se caracterizan porque su infraestructura vial no va acorde con su demanda vehicular, como es el caso de la ciudad de Lima. Por consiguiente, se debe priorizar el desarrollo de la infraestructura vial, ya que existen por ejemplo intersecciones amplias que presentan gran cantidad de puntos de conflicto. En efecto, reducen la capacidad operacional y el nivel de servicio de la intersección. Esta investigación tiene como objetivo reducir los puntos de conflicto y el tiempo de cruce en intersecciones amplias tipo cruz, en base a la Metodología de Flujo Continuo (CFI, por sus siglas en inglés) con delineadores elevados (bolardos compuestos) y detectores (sensores) a fin de mejorar la capacidad y seguridad operacional de la intersección. El objeto de estudio de la presente investigación se encuentra en una zona comercial ubicada entre la Avenida República de Venezuela con la Avenida Aurelio García y García, Lima. Los movimientos vehiculares de giro a la izquierda son los que afectan el rendimiento de las intersecciones señalizadas. Por tanto, se recolectaron 3219 vehículos en total, de los cuales 561 vehículos giraron a la izquierda demostrando así la alta densidad de este tipo de maniobras. La efectividad del diseño propuesto se valida empleando una microsimulación en el software Vissim. Los resultados obtenidos muestran los puntos de conflictos tipo cruz se redujeron a 8 puntos con el modelo propuesto frente al estado actual, el cual posee 58 puntos de conflictos tipo cruz. Por otro lado, el tiempo promedio de cruce de los vehículos disminuyó en 4.20 y 9.79 segundos en la fase 1, debido al rediseño de la geometría de la intersección. En efecto, la capacidad operacional aumentó en 33.85%, ya que el aforo vehicular con el nuevo ciclo semafórico de 150 segundos es de 431vehículos con respecto a los 322 vehículos que se tenía con el modelo anterior. Finalmente, los riesgos de colisiones posteriores y laterales se reducen mediante el uso de delineadores elevados en un 83%. / Highly congested cities require optimal management of urban mobility. Many of these cities are characterized because their road infrastructure does not match their vehicular demand, as is the case in the city of Lima. Therefore, the development of road infrastructure should be prioritized, since there are, for example, wide intersections that present a large number of conflict points. In effect, they reduce the operational capacity and service level of the intersection. This research aims to reduce conflict points and crossing time at wide cross-type intersections, based on the Continuous Flow Methodology (CFI) with elevated eyeliners (composite bollards) and detectors (sensors) in order to improve the capacity and safety of the intersection. The object of study of the present investigation is in a commercial area located between avenue Republica de Venezuela with avenue Aurelio Garcia y Garcia, Lima. The left-turn vehicular movements are those that affect the performance of the signposted intersections. Therefore, 3219 vehicles were collected in total, of which 561 vehicles turned left demonstrating the high density of this type of maneuver. The effectiveness of the proposed design is validated using microsimulation in the Vissim software. The results obtained show the points of cross-type conflicts were reduced to 8 points with the proposed model compared to the current state, which has 58 points of cross-type conflicts. On the other hand, the average crossing time of the vehicles decreased by 4.20 and 9.79 seconds in phase 1, due to the redesign of the intersection geometry. In fact, the operational capacity increased by 33.85%, since the vehicle capacity with the new traffic light cycle of 150 seconds is 431 vehicles with respect to the 322 vehicles that had the previous model. Finally, the risks of posterior and lateral collisions are reduced by the use of elevated eyeliners by 83%. / Tesis
169

Systém pro asistenci při nepřehledných dopravních situacích / Traffic assistant system for complicated situations

Podola, David January 2019 (has links)
T-intersections are one of the most common places where collisions happen. An intelligent traffic mirror is one the possible solutions to reduce the accident rate. The mirror detects the situation around the intersection, process the data and provides the driver with an information, whether the situation is safe and the driver can enter the junction safely. The aim of the thesis is a feasibility study of reliable detection of non-stationary objects based on cameras. The core of the intended product – the detection algorithm – detected the object on short distance from the camera reliably but as the distance was growing, the detection quality degraded. One of the possible solutions to achieve better detection results on longer distances may be achieved by using a camera with greater zoom. Based on the example improvement proposal, the feasibility of the solution based on optical methods was finally confirmed.
170

Geometrical design and forming analysis of three-dimensional woven node structures

Hübner, Matthias, Fazeli, Monireh, Gereke, Thomas, Cherif, Chokri 05 November 2019 (has links)
Structural frames have been established in many technical applications and typically consist of interconnected profiles. The profiles are commonly joined with node elements. For lightweight structures, the use of composite node elements is expedient. Due to the anisotropic mechanical properties of the fibers, high demands are placed on the orientation of the fibers in the textile reinforcement structure. A continuous fiber course around the circumference and at the junctions is necessary for an excellent force transmission. A special binding and forming process was developed based on the weaving technology. It allows the production of near-net-shaped node elements with branches in any spatial direction, which meet the requirements of load-adjusted fiber orientation. The principles by which these three-dimensional (3D) node elements are converted into a suitable geometry for weaving as a net shape multilayer fabric are reported. The intersections of the branches are described mathematically and flattened to a plane. This is the basis for the weave pattern development. Forming simulations on the macro- and meso-scales complement the analyses. A macro-scale model based on the finite element method (FEM) is used to verify the general formability and the accuracy of the flattenings. Since yarns are pulled through the textile structure in the novel forming process, the required tensile forces and the pulling lengths of the individual yarns are analyzed with a meso-scale FEM model. The flattening for two different node structures is realized successfully, and the simulation proves formability. Furthermore, the necessary forming forces are determined. Finally, the developed method for flattening the 3D geometry is suitable for the design of a variety of spatial node structures and the simulation supports the design of automated forming processes.

Page generated in 0.1849 seconds