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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.
21

HEAVY-DUTY TRUCK PLATOONING ON HILLY TERRAIN: METHODS FOR ASSESSMENT AND IMPROVEMENT

Miles J Droege (11128536) 22 July 2021 (has links)
Class 8 heavy-duty truck platooning has demonstrated significant fuel economy benefits on routes with road grade less than±2% in literature, but there is little to no platooning research on routes with road grade greater than±2% - which make up a significant portion of U.S. highways. Therefore, the effort described in this thesis is aimed at assessing currently available two-truck platoon control strategies as well as developing new strategies to improve platoon performance on hilly terrain. Specifically, the strategies tested in this work include four types of lead truck speed control strategies and two types of platoon transmission shifting strategies. These strategies are tested using two experimentally validated heavy-duty, two-truck platoon simulation approaches where each approach has its own advantages and disadvantages. The trends observed from these two simulation approaches indicate that the lead truck speed control and transmission shifting strategies have a significant effect on the platoon fuel economy and gap control performance when the platoon operates on a hilly terrain route.
22

A Geometric Design of Traffic-Light Roads Crossing Using the Continuous Flow Intersections Methodology to Reduce Points of Primary Conflicts Caused by Left Turns

Chuco, Betsi, Pérez, Carlos, Silvera, Manuel, Campos, Fernando 01 January 2021 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The continuous flow intersections (CFI) increase the operational capacity of road systems with congestion problems, by using shared lanes located at the access points before the intersection. However, the CFI presents road safety risks that increase the likelihood of vehicle collision. This article proposes a geometric design composed of raised delineators at a traffic-light intersection, whose objective is to eliminate the points of primary conflicts caused by the left turns of the vehicles. To do this, a study was conducted to identify the different maneuvers present in a wide cross-type intersection in a commercial area located in the city of Lima. A total of 3219 vehicles was collected, of which 561 vehicles turned left demonstrating the high density of this type of maneuver. The effectiveness of the proposed design is validated using a microsimulation in the Vissim program. The results show that it was reduced from 58 to 8 points of conflict, increasing operational capacity by 34.97%. Finally, the risks caused by CFI decreased by 83%. / Revisión por pares
23

Melhoria do desempenho do tráfego em rotatórias com o emprego de semáfaros próximos na via principal / Traffic performance improvement at roundabouts with traffic lights near the main street

Diego Fernandes Neris 24 February 2014 (has links)
Neste trabalho é avaliado o desempenho operacional de uma nova configuração idealizada para a operação de rotatórias de três pernas (prioridade para os veículos da via principal com semáforos próximos). Nesta avaliação é comparado o novo sistema de operação com outros dois usualmente empregados: (1) prioridade para os veículos que estão circulando na ilha central (rotatória convencional) e (2) prioridade para os veículos da via principal sem o emprego de semáforo, bem como, com base nos resultados das comparações realizadas, são estabelecidas as condições dos fluxos de tráfego em que é indicada uma ou outra configuração. Os valores obtidos nas simulações mostram, de forma inequívoca, o desempenho operacional superior da rotatória com prioridade para a via principal com semáforos próximos, adequadamente programados, no caso de fluxos altos. O emprego de semáforos próximos reduz significativamente o atraso na aproximação crítica e, em consequência, o tamanho da fila, como consequência do aumento expressivo da capacidade de tráfego da rotatória. Os resultados da simulação corroboram o que se pode observar nos sistemas implantados na cidade de Araraquara, onde a colocação de semáforos próximos de rotatórias de três pernas melhorou de forma significativa o desempenho operacional dos dispositivos, reduzindo o atraso crítico e o tamanho da fila crítica e aumentando a capacidade. O acompanhamento da acidentalidade nas rotatórias onde foram colocados semáforos próximos na cidade de Araraquara mostra uma redução dos acidentes graves de aproximadamente 90%. Uma explicação para essa redução pode ser devido ao aumento da paciência dos motoristas em esperar uma brecha maior para entrar na rotatória, pois sabem que, esporadicamente, há uma interrupção do fluxo na via principal. / In this study the operational performance is measured of a new idealized configuration for the operation in three-legged traffic circles (priority way for the vehicles from the main street with traffic lights nearby). This measured is compared the new operational system with two others usually systems: (1) priority for the circulating traffic (conventional roundabout) and (2) priority for vehicles from the main street without traffic lights. Also, based on the results from the comparisons, seek to establish what traffic flow conditions are better for a given configuration. The values obtained from the simulations demonstrate, clearly, the superior operational performance of the traffic circle with main road priority combined with properly programmed traffic lights nearby, in the case of high flows. The use of traffic lights reduces significantly the delay from the critical approach, and consequently, the queue length, as a consequence resulting on significant traffic capacity increase at the intersection. Simulation results validate what can be seen in Araraquara, where the installation of traffic lights near from the three-legged traffic circle improved significantly the operating performance of the devices, reducing the critical delay and critical queue size and increasing the effective capacity. Monitoring the accident rate in traffic circles where traffic lights nearby were placed in Araraquara shows a reduction of approximately 90% in serious accidents. An explanation of this reduction may be due to the increased of patience of drivers in wait for a larger gap to enter on the roundabout, because they know there will be an interruption on the main street, sporadically.
24

Melhoria do desempenho do tráfego em rotatórias com o emprego de semáfaros próximos na via principal / Traffic performance improvement at roundabouts with traffic lights near the main street

Neris, Diego Fernandes 24 February 2014 (has links)
Neste trabalho é avaliado o desempenho operacional de uma nova configuração idealizada para a operação de rotatórias de três pernas (prioridade para os veículos da via principal com semáforos próximos). Nesta avaliação é comparado o novo sistema de operação com outros dois usualmente empregados: (1) prioridade para os veículos que estão circulando na ilha central (rotatória convencional) e (2) prioridade para os veículos da via principal sem o emprego de semáforo, bem como, com base nos resultados das comparações realizadas, são estabelecidas as condições dos fluxos de tráfego em que é indicada uma ou outra configuração. Os valores obtidos nas simulações mostram, de forma inequívoca, o desempenho operacional superior da rotatória com prioridade para a via principal com semáforos próximos, adequadamente programados, no caso de fluxos altos. O emprego de semáforos próximos reduz significativamente o atraso na aproximação crítica e, em consequência, o tamanho da fila, como consequência do aumento expressivo da capacidade de tráfego da rotatória. Os resultados da simulação corroboram o que se pode observar nos sistemas implantados na cidade de Araraquara, onde a colocação de semáforos próximos de rotatórias de três pernas melhorou de forma significativa o desempenho operacional dos dispositivos, reduzindo o atraso crítico e o tamanho da fila crítica e aumentando a capacidade. O acompanhamento da acidentalidade nas rotatórias onde foram colocados semáforos próximos na cidade de Araraquara mostra uma redução dos acidentes graves de aproximadamente 90%. Uma explicação para essa redução pode ser devido ao aumento da paciência dos motoristas em esperar uma brecha maior para entrar na rotatória, pois sabem que, esporadicamente, há uma interrupção do fluxo na via principal. / In this study the operational performance is measured of a new idealized configuration for the operation in three-legged traffic circles (priority way for the vehicles from the main street with traffic lights nearby). This measured is compared the new operational system with two others usually systems: (1) priority for the circulating traffic (conventional roundabout) and (2) priority for vehicles from the main street without traffic lights. Also, based on the results from the comparisons, seek to establish what traffic flow conditions are better for a given configuration. The values obtained from the simulations demonstrate, clearly, the superior operational performance of the traffic circle with main road priority combined with properly programmed traffic lights nearby, in the case of high flows. The use of traffic lights reduces significantly the delay from the critical approach, and consequently, the queue length, as a consequence resulting on significant traffic capacity increase at the intersection. Simulation results validate what can be seen in Araraquara, where the installation of traffic lights near from the three-legged traffic circle improved significantly the operating performance of the devices, reducing the critical delay and critical queue size and increasing the effective capacity. Monitoring the accident rate in traffic circles where traffic lights nearby were placed in Araraquara shows a reduction of approximately 90% in serious accidents. An explanation of this reduction may be due to the increased of patience of drivers in wait for a larger gap to enter on the roundabout, because they know there will be an interruption on the main street, sporadically.
25

How to Present Statistical Comparisons between Swedish Hospitals and Counties

Xia, Binyan January 2011 (has links)
Background The Swedish Association of local authorities and regions in collaboration with the national board of health and welfare produces the yearly “Swedish Health Care Report” in order to provide evaluations of the hospitals and counties in Sweden for both the politicians and the general public. Method We describe several standard methods which have been used to present the performance of each hospital or county: Forest plot (FL), League Table (LT), League Plot (LP) and Funnel Plot (FP). Using simulation technique to produce the League Plot of rank is also presented in order to illustrate the unreliable of the ranking principle. Results The league plot with confidence interval is easily understood by people, but it should provide the total number of operations (sample size) as well. The resulting multiple-indicators system gives a clear overview of the whole system, but the cut-off points used in the traffic light method is not the best choice. Several possible improved methodologies are: A league plot traffic light method and a standard funnel plot traffic light method is recommended when aiming at finding the outliers; A p=0.67 funnel plot traffic light method is suggested when wishing to divide the units into approximately equally large groups; A one-side traffic light method seems to be a wonderful choice when focusing on the bad performance units.
26

Sensor de presença para semáforo inteligente de baixo custo

Sergio Ferreira de Oliveira 13 December 2012 (has links)
Este trabalho destina-se a especificar, analisar e ensaiar um sensor de presença para um semáforo inteligente de baixo custo. O sensor tem por finalidade a redução dos custos de implantação e manutenção nos sistemas de controles dos semáforos inteligentes, quando comparado a outros sensores, tais como, por imagem, ultrassom, laser, infravermelho, pneumático ou indutivo. O princípio de funcionamento tem por base a detecção de veículos na região de aproximação das vias de uma interseção por meio de um sensor que gera um sinal elétrico para o sistema de controle de tráfego. Utilizando sensores de micro-ondas de efeito Doppler e um circuito detecção o sistema torna-se de fácil implantação nos cruzamentos das vias públicas, por possuir tamanho reduzido, facilidade de programação e baixo consumo de energia, atendendo, portanto a necessidade de sistemas sustentáveis. Por motivo de segurança, ao ser iniciado ou reiniciado devido a falta de energia elétrica, o sistema funciona de forma temporizada por dois ciclos completos, tempo suficiente para que seja possível a detecção de veículos pelos sensores. / This work aims to specify, analyze and test a presence sensor for an intelligent traffic light at low cost. The sensor is intended to reduce the costs of deployment and maintenance of control systems in intelligent traffic lights, when compared to other sensors such as imaging, ultrasound, laser, infrared, pneumatic or inductive. The operating principle is based on the detection of approaching vehicles in the region of an intersection roads by means of a sensor which generates an electrical signal to the control system traffic. Using sensors microwave Doppler Effect and a loop detection system becomes easy to deploy in the crossings of public roads, for having reduced size, ease of programming and low power consumption, light, therefore the need for sustainable systems. For security reasons, to be started or restarted due to power outages, the system works timed by two complete cycles, enough time to be able to detect vehicles by sensors.
27

Centralizované vyhodnocování zátěže dopravního systému / Centralised Traffic System Load Evaluation

Zukal, Marek January 2010 (has links)
There are statistical data gathered as a part of the operation of the intersections controlled by the traffic light signalling devices. This data concerns characteristics of traffic flows and parameters of the aplied controlling strategy and can be valuable source of information that can be used to improve the controlling strategy or creation of a mathematical model describing the behaviour of the traffic flows. These models are closely studied and used for prediction of the immediate development of the traffic flows based on their current states. This paper is trying to design means to create such models and to work with them.
28

Prädiktion von Signallaufzeiten verkehrsadaptiver Lichtsignalanlagen zur Unterstützung von C-ITS Anwendungen

Krumnow, Mario 08 December 2023 (has links)
In dieser Arbeit wird ein Verfahren zur Prognose von Schaltzeiten verkehrsadaptiver Lichtsignalanlagen vorgestellt. Der vorgestellte Algorithmus ist dabei sowohl hersteller- als auch schnittstellenunabhängig und somit universell einsetzbar. Der Algorithmus besteht aus einer Langzeit- und einer Kurzfristprognose und setzt das Verfahren zur Berechnung von Entscheidungsbäumen effizient um. Die Verifikation der vorgestellten Schaltzeitprognose wird an über 200 Lichtsignalanlagen in Dresden durchgeführt. Es wird gezeigt das eine gute Prognose von Signalabläufen für das automatisierte Fahren grundsätzlich möglich ist, wobei die Variabilität des Steuerverfahrens und der betrachtete Prognosehorizont maßgeblich die erzielbare Prognosequalität beeinflussen.:1 Einleitung 1.1 Motivation 1.2 Stand der Technik 1.3 Zielsetzung 1.4 Aufbau der Arbeit 2 Grundlagen 2.1 Aufbau von Lichtsignalanlagen 2.2 Steuerungsarten von Lichtsignalanlagen 2.3 Betrieb von Lichtsignalanlagen 2.4 Fahrerassistenzsysteme an signalisierten Knotenpunkten 2.5 Fazit 3 Analyse verkehrsadaptiver Lichtsignalanlagen 3.1 Möglichkeiten der Erhebung von Prozessdaten 3.2 Methodik der Datenauswertung 3.3 Statistische Kenngrößen 3.4 Anforderung an die Prädiktion 3.5 Annäherungsstrategie an signalisierten Knotenpunkten 3.6 Fazit 4 Neue Verfahren zur Prädiktion von Signalzeiten 4.1 Systemanforderungen 4.2 Arten der Wissensverarbeitung 4.3 Anwendung von Entscheidungsbäumen 4.4 Algorithmus der Kurzfristprognose 4.5 Algorithmus der Langzeitprognose 4.6 Fazit 5 Umsetzung und Anwendung der Verfahren 5.1 Vorstellung der Referenzstrecken 5.2 Datenübertragung und Informationsaustausch 5.3 Programmtechnische Umsetzung 5.4 Darstellung der Prognose im Fahrzeug 5.5 Fazit 6 Auswertung, Evaluation und Bewertung 6.1 Methodik 6.2 Prozessdaten und Datenübertragung 6.3 Prognose im gesamten Untersuchungsgebiet 6.4 Prognose auf den Pilotstrecken 6.5 Auswertung von Messfahrten 6.6 Verbesserungsmöglichkeiten der Prognose 7 Zusammenfassung und Ausblick
29

INTERSECTION STATE VISUALIZATION FOR REALTIME SIMULATIONS

Roth, Justin L. 10 1900 (has links)
<p>Driving simulators have existed since the beginning of the $20<sup>th</sup> century. From its roots, it has been a technology used primarily to train drivers, test and prototype new technology, and improve the safety of automobile users. As technology has progressed, so has the quality of the driving simulation, and along side it, the complexity of experiments performed. The McMaster motion simulation system combines the latest software with state of the art psychology techniques, to analyze the driving experience in new and unique ways. To accommodate the wide range of plausible experiments, a robust software system was developed that allows for custom driving scenarios. The software system is comprised of several sub-components including content generation, scenario management, visualization and artificial intelligence. This thesis details the development of a traffic light system and its incorporation into the existing simulation system. A variety of challenges were encountered including real-time constraints, adapting flight software to driving simulation, inter-system communication, and interoperability of multiple APIs. A secondary objective was to document, this thesis records the methodology used to overcome these challenges in an attempt to facilitate future work in this field.</p> / Master of Applied Science (MASc)
30

Evaluation of Road Equipment with Emphasis on Condition Assessment

Lundkvist, Sven-Olof January 2008 (has links)
This doctoral thesis deals primarily with condition assessment of road equipment. The road equipment concept is defined by five main groups, road lighting, fences and barriers, vertical signs, horizontal signs and traffic signals, respectively. Of these groups, road markings, street lighting and barriers of three-lane roads have been studied more in detail. A state-of-the-art, comprising information obtained by comprehensive literature studies on condition assessment of road equipment is presented. Comparably few fundamental studies were found, which, to some degree, can be explained by the lack of suitable physical measurement methods. However, in the case of road marking retroreflectivity, mobile instruments have been developed, and research published in this area is relatively comprehensive. Furthermore, although not based on mobile measurements, several studies on assessments on performance of road sign sheeting have been published. The experimental part of the thesis is divided into four studies, of which two are dealing with mobile measurement of wet road markings and street lighting, respectively. One of the studies concerns condition assessment of road marking performance accomplished in the Nordic countries. Finally, one study comprises risk analysis related to crashes into the barriers on three-lane roads. At road equipment condition assessment, mobile measurement methods are preferable compared to stationary methods. However, many relevant parameters are tricky to measure at speed. One example in this connection is characterization of performance of wet road markings, which has to be based on one or more parameters obtained by measurements on dry surfaces. Results presented in this thesis indicate that retroreflectivity and skid resistance of wet road markings can be predicted based on retroreflectivity and macro-texture of dry road marking. For traffic safety, street lighting is important. The performance of this type of road equipment is in most cases described in terms of luminance of the illuminated road surface. However, luminance measurements are tricky and time-consuming and not useful for condition assessment. On the contrary, measurement of illuminance is easy to carry out and can be performed at speed. One part of the thesis describes how road surface luminance in street lighting can be estimated based on illuminance and reflection properties of the road surface. With the purpose of comparing road marking performance in the Nordic countries, condition assessment using mobile measurement equipment was accomplished in 2002 and 2003. In each of the five Nordic countries, a number of roads were chosen for measuring retroreflectivity. The study showed that the retroreflectivity of edge, centre and lane lines was poor in some countries, but, at least regarding edge lines, this shortcoming could be compensated by use of wide, continuous lines. In other words, the visibility of longitudinal road markings was approximately equal in the different countries. The purpose of the risk analysis performed on three-lane road barriers was to estimate the influence of the time-period between initial crash and repair on the risk of a secondary accident. The result showed that, especially in winter-time, time-reduction means reduced risk of secondary accidents. / QC 20100824

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