• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 213
  • 107
  • 51
  • 21
  • 13
  • 8
  • 4
  • 4
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 479
  • 178
  • 107
  • 107
  • 95
  • 85
  • 82
  • 76
  • 70
  • 55
  • 52
  • 51
  • 49
  • 48
  • 48
  • 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.
41

Methodology for determining optimized traffic light cycles based on simulation

Rivera, G., Rivera, G., Velasquez, L., Bravo, A., Minano, P. 28 February 2020 (has links)
In large urbanized cities, a major problem that affects the economy and health of all citizens is vehicular congestion. This is because the traffic light cycles are not adequate. In the present study, we seek to optimize traffic light cycles based on simulation, in order to improve vehicle flow. For this, the PTV Vissim 9.0 software was used as a simulator and the Synchro 10.0 software to determine the initial optimal traffic light cycle. Through several runs and having as variables the length of queues, delay times and the average speed, the optimal traffic light cycle could be found for the study area. The results obtained reflect a 14% reduction in delay times and 10% in queue lengths. On the other hand, the average vehicle speed increased by 10.56%. All this represents an improvement in the service level of the study intersections.
42

Video Streaming and Multimedia Broadcasting Over Vehicular Ad Hoc Networks

Naeimipoor, Farahnaz January 2013 (has links)
Video dissemination capabilities are crucial for the deployment of many services over VANETs. These services range from enhancing safety via the dissemination of video from the scene of an accident, to advertisement of local services or businesses. This work considers the infrastructure-less scenario of VANETs and dissemination of video content over this network environment, which is extremely challenging mainly due to its dynamic topology and stringent requirements for video streaming. This study discusses issues and challenges that need to be tackled for disseminating high-quality video over VANETs. Furthermore it surveys and analyzes the suitability of different existing solutions aimed towards effective and efficient techniques for video dissemination in vehicular networks. As a result, a set of the most promising techniques are selected, described in detail and evaluated based on standard terms in quality of service. This thesis also discusses efficiency and suitability of these techniques for video dissemination and compares their performance over the same network condition. In addition, a detailed study on the effect of network coding on video dissemination protocols has been conducted to guide how to employ this technique properly for video streaming over VANETs. From this study, a summary of the observations was obtained and used to design a new hybrid solution by deploying robust and efficient techniques in number of existing protocols in an optimal manner. The proposed hybrid video dissemination protocol outperforms other protocols in term of delivery ratio and complies with other quality-of-service requirements for video broadcasting over vehicular environments.
43

Ventajas del Arrendamiento Operativo frente al Arrendamiento Financiero en el Perú en el 2017

Falen Sanchez, Farid Eugenio, Melchor Ángeles, Galdino Eleodoro, Minaya Obregón, Henry Edson, Barrenechea García Zapatero, Ángel Martin 30 November 2017 (has links)
La iniciativa de realizar el presente estudio de viabilidad de la implementación de una empresa que realice arrendamiento operativo nace del hallazgo de millones de personas que no pueden calificar a un crédito vehicular convencional, por distintos motivos, como no cumplir con alguno de los requisitos formales, por no encontrarse en el sistema financiero o por tener calificación negativa en él. A raíz de ello, realizamos una investigación sobre cuáles son las ventajas del arrendamiento operativo frente al financiero y se encontró que existe la necesidad de cubrir a esta demanda. Concluimos que, al implementarse el arrendamiento operativo, se cubre esta demanda, apoyando a las personas que no tienen otra opción que alquilar un auto o comprar uno de segunda mano, para lo cual se irán empleando métodos adecuados, para minimizar los riesgos y de darse, poder manejarlos de forma eficiente, para evitar que la empresa se perjudique de alguna manera. Cabe indicar que los resultados obtenidos del análisis operativo y financiero tenemos un VAN S/ 2,520,161.35, TIR 34.18%, WACC 7.73%, Payback de 3 Años 3 Meses, se concluye que el proyecto es viable. / Trabajo de investigación
44

Techniques for using 3D Terrain Surface Measurements for Vehicular Simulations

Detweiler, Zachary Ray 17 June 2009 (has links)
Throughout a ground vehicle development program, it is necessary to possess the loads the vehicle will experience. Unfortunately, actual loads are only available at the conclusion of the program, when the vehicle has been built and design changes are costly. The design engineer is challenged with using predicted loads early in the design process, when changes are relatively easy and inexpensive to make. It is advantageous, therefore, to accurately predict these loads early in the program, thus improving the vehicle design and, ultimately, saving time and money. The prediction of these loads depends on the fidelity of the vehicle models and their excitation. The focus of this thesis is the development of techniques for using 3D terrain surface measurements for vehicular simulations. Contributions are made to vehicle model parameter identification, terrain filtering, and application-dependent interpolation methods for 3D terrain surfaces. Modeling and simulation are used to improve and shorten a vehicle's development cycle, thus, saving time and money. An important aspect in developing a vehicle model is to identify the parameters. Some parameters are easily measured with readily available tools; however, other parameters require dismantling the vehicle or using expensive test equipment. Initial estimates of these difficult or costly to obtain parameters are made based on similar vehicle models or standard practices. In this work, a parameter identification method is presented to obtain a better estimate of these inaccessible parameters using measured terrain excitations. By knowing the excitations to the physical vehicle, the simulated response can be compared to measured response, and then the vehicle model's parameters can be optimized such that the error between the responses is minimized. Through this process, better estimates of the vehicle's parameter are obtained, which demonstrates that measured terrain can improve vehicle development by increasing the accuracy of parameter estimates. The principal excitation to any ground vehicle is the terrain, and by obtaining more accurate representations of the terrain, vehicular simulation techniques are advanced. Many simple vehicle models use a point contact tire model, which performs poorly when short wavelength irregularities are present because the model neglects the tire's mechanical filtering properties. Therefore, a filter is used to emulate a tire's mechanical filtering mechanism and create an effective terrain profile. In this work, terrain filters are evaluated to quantify their effect on the sprung mass response of the dynamic simulation of a seven degree of freedom vehicle model. In any vehicular simulation, there is a balance between analytical expense and simulation realism. This balance often limits simulations to 2D terrain profile excitations, but as computing power increases the computational expense decreases. Thus, 3D terrain excitations for vehicular simulation are a tool for advancing simulation realism that is becoming less computationally expensive. Three dimensional terrain surfaces are measured with a non-uniform spacing in the horizontal plane; therefore, application-dependent gridding methods are developed in this work to interpolate 3D terrain surface to uniform grid spacing. The uniform grid spacing allows 3D terrain surfaces to be used more efficiently in any vehicular simulation when compared to non-uniform spacing. / Master of Science
45

Propuesta de crecimiento de la participación de mercado de neumáticos para vehículos SUV de Empresa Fabricante de Llantas / Proposal for the market share growth of tires for SUV vehicles of a tire manufacturer company

Galarza Rosazza, Efraín Carlos 26 December 2018 (has links)
Este trabajo de investigación trata de la evaluación del entorno externo e interno de la empresa, su análisis y la propuesta de estrategias específicas para aumentar el crecimiento de la participación de mercado en el segmento de llantas de consumo para vehículos SUV, para una planta fabricante de llantas en el Perú, a la que llamaremos “Fabricante de Llantas S.A”. El estudio se inicia con el análisis del entorno externo donde opera esta empresa, el análisis de su estructura interna, para luego en base a estos análisis realizar una evaluación estratégica de la misma, identificando sus fortalezas, amenazas, debilidades y oportunidades con el fin de determinar las mejores estrategias a adoptar para mantener en el tiempo una ventaja competitiva sobre sus competidores, que la lleve a incrementar su participación de mercado. En esta evaluación se realizaron los análisis FODA, PEYEA, BCG, IE y GE, así como también se utilizaron otros criterios que afectan al sector, con el fin de proponer las estrategias necesarias para su implementación, donde se incluyen los lineamientos estratégicos y los objetivos a ser alcanzados, que lleven a la organización a incrementar su participación en el segmento de mercado de llantas de consumo para vehículos SUV. Finalmente se proponen algunas recomendaciones que le pueden permitir alcanzar estos objetivos y seguir manteniéndose competitivos en el mercado de llantas en el Perú y Latinoamérica. / This research work consists of the evaluation of the external and internal environment of the company, its analysis and the proposal of specific strategies to increase the growth of the market share in the segment of consumer tires for SUV vehicles, for a manufacturing plant of tires in Peru, which it will be called "Tires Manufacturer S.A.”. The study begins with the analysis of the external environment where this company operates, the analysis of its internal structure, and then on the basis of these analyzes perform a strategic evaluation of it, identifying its strengths, threats, weaknesses and opportunities with the aim of determining the best strategies to adopt in order to maintain throughout the years a competitive advantage over its competitors, which will lead it to increase its market share. In this evaluation the SWOT, PEYEA, BCG, IE and GE analyzes were carried out, as well as other criteria that affect the sector, so as to propose the necessary strategies for its implementation, which include the strategic guidelines and objectives to be achieved, which will lead the organization to increase its participation in the market segment of consumer tires for SUV vehicles. Finally, some recommendations are proposed that will allow you to achieve these objectives and continue to remain competitive in the tire market in Peru and Latin America. / Tesis
46

Determinación de ciclos semafóricos optimizados con Synchro 10.0 aplicados y evaluados en intersecciones de gran congestión vehicular con el software PTV Vissim 9.0 / Determination of traffic signal cycles optimized with Synchro 10.0 applied and evaluated at intersections of high traffic congestion with the PTV Vissim 9.0 software

Rivera Saavedra, Gabriel, Velásquez Ochochoque, Luis Alberto 24 July 2019 (has links)
Este artículo presenta la evaluación del tráfico vehicular en dos intersecciones semaforizadas ubicadas en la ciudad de Lima; una de las principales ciudades del mundo con gran congestión vehicular; mediante un modelo microscópico desarrollado con el software Vissim 9.0. La finalidad de esta investigación es proponer la implementación de un sistema de semaforización inteligente para mejorar los niveles de servicio y disminuir la congestión vehicular. El proceso de construcción del modelo consiste en cuatro etapas. Primero, es el trabajo previo, en la cual se realizó la recolección de datos de campo. Luego, se construyó el modelo mediante el software Vissim 9.0. Después, se realizó la calibración y validación del modelo en ambas intersecciones en base a parámetros psicofísicos para certificar que los resultados del modelo se asemejen a las condiciones reales de las intersecciones. Por último, se incorporaron los nuevos flujos futuros en el modelo cada 15 minutos los cuales se simularon y evaluaron con los NS obtenidos, que incorporan la propuesta de mejora. Esencialmente los niveles de servicio de las intersecciones mejoran, determinando cada 15 minutos durante la hora pico nuevos ciclos semaforizados optimizados con el programa Synchro 10.0 aplicados a Vissim 9.0, pasando de un NS E a D, esto se deduce a partir de la disminución de longitudes de colas en todos los accesos y la reducción de las demoras de viaje, las cuales fueron 14% en la Av. Javier Prado – Ca. Las Flores y 24% en la Av. Javier Prado – Ca. Las Palmeras. / This paper presents the evaluation of vehicular traffic on two signalized intersections located in the city of Lima; one of the world's major cities with high traffic congestion; by microscopic model developed with Vissim 9.0 software. The purpose of this research is to propose the implementation of an intelligent traffic signals to improve service levels and reduce traffic congestion. The process of building the model consists of four stages. First, it is the previous work, in which the field data collection was performed. The model was then constructed by Vissim 9.0 software. After, calibration and validation of the model was performed on both intersections based on psychophysical parameters to certify that the model results resemble the actual conditions of intersections. Finally, new future flows were incorporated into the model every 15 minutes which were simulated and evaluated with the NS obtained, incorporating the proposed improvement. Essentially service levels intersections improve, determining every 15 minutes during rush hour new signalized cycles optimized with Synchro 10.0 program applied to Vissim 9.0, from an NS E to D, It follows from decreasing lengths queues at all entrances and reducing travel delays, which were 14% at Av. Javier Prado -. Ca. Las Flores and 24% on Av. Javier Prado -. Ca. Las Palmeras. / Trabajo de investigación
47

Determinación de ciclos semafóricos optimizados con Synchro 10.0 aplicados y evaluados en intersecciones de gran congestión vehicular con el software PTV Vissim 9.0. / Determination of traffic signal cycles optimized with Synchro 10.0 applied and evaluated at intersections of high traffic congestion with the PTV Vissim 9.0 software.

Rivera Saavedra, Gabriel, Velásquez Ochochoque, Luis Alberto 24 July 2019 (has links)
Este artículo presenta la evaluación del tráfico vehicular en dos intersecciones semaforizadas ubicadas en la ciudad de Lima; una de las principales ciudades del mundo con gran congestión vehicular; mediante un modelo microscópico desarrollado con el software Vissim 9.0. La finalidad de esta investigación es proponer la implementación de un sistema de semaforización inteligente para mejorar los niveles de servicio y disminuir la congestión vehicular. El proceso de construcción del modelo consiste en cuatro etapas. Primero, es el trabajo previo, en la cual se realizó la recolección de datos de campo. Luego, se construyó el modelo mediante el software Vissim 9.0. Después, se realizó la calibración y validación del modelo en ambas intersecciones en base a parámetros psicofísicos para certificar que los resultados del modelo se asemejen a las condiciones reales de las intersecciones. Por último, se incorporaron los nuevos flujos futuros en el modelo cada 15 minutos los cuales se simularon y evaluaron con los NS obtenidos, que incorporan la propuesta de mejora. Esencialmente los niveles de servicio de las intersecciones mejoran, determinando cada 15 minutos durante la hora pico nuevos ciclos semaforizados optimizados con el programa Synchro 10.0 aplicados a Vissim 9.0, pasando de un NS E a D, esto se deduce a partir de la disminución de longitudes de colas en todos los accesos y la reducción de las demoras de viaje, las cuales fueron 14% en la Av. Javier Prado – Ca. Las Flores y 24% en la Av. Javier Prado – Ca. Las Palmeras. / This paper presents the evaluation of vehicular traffic on two signalized intersections located in the city of Lima; one of the world's major cities with high traffic congestion; by microscopic model developed with Vissim 9.0 software. The purpose of this research is to propose the implementation of an intelligent traffic signals to improve service levels and reduce traffic congestion. The process of building the model consists of four stages. First, it is the previous work, in which the field data collection was performed. The model was then constructed by Vissim 9.0 software. After, calibration and validation of the model was performed on both intersections based on psychophysical parameters to certify that the model results resemble the actual conditions of intersections. Finally, new future flows were incorporated into the model every 15 minutes which were simulated and evaluated with the NS obtained, incorporating the proposed improvement. Essentially service levels intersections improve, determining every 15 minutes during rush hour new signalized cycles optimized with Synchro 10.0 program applied to Vissim 9.0, from an NS E to D, It follows from decreasing lengths queues at all entrances and reducing travel delays, which were 14% at Av. Javier Prado -. Ca. Las Flores and 24% on Av. Javier Prado -. Ca. Las Palmeras. / Tesis
48

Determinación de ciclos semafóricos optimizados con Synchro 10.0 aplicados y evaluados en intersecciones de gran congestión vehicular con el software PTV Vissim 9.0. / Determination of traffic signal cycles optimized with Synchro 10.0 applied and evaluated at intersections of high traffic congestion with the PTV Vissim 9.0 software

Rivera Saavedra, Gabriel, Velásquez Ochochoque, Luis Alberto 24 July 2019 (has links)
Este artículo presenta la evaluación del tráfico vehicular en dos intersecciones semaforizadas ubicadas en la ciudad de Lima; una de las principales ciudades del mundo con gran congestión vehicular; mediante un modelo microscópico desarrollado con el software Vissim 9.0. La finalidad de esta investigación es proponer la implementación de un sistema de semaforización inteligente para mejorar los niveles de servicio y disminuir la congestión vehicular. El proceso de construcción del modelo consiste en cuatro etapas. Primero, es el trabajo previo, en la cual se realizó la recolección de datos de campo. Luego, se construyó el modelo mediante el software Vissim 9.0. Después, se realizó la calibración y validación del modelo en ambas intersecciones en base a parámetros psicofísicos para certificar que los resultados del modelo se asemejen a las condiciones reales de las intersecciones. Por último, se incorporaron los nuevos flujos futuros en el modelo cada 15 minutos los cuales se simularon y evaluaron con los NS obtenidos, que incorporan la propuesta de mejora. Esencialmente los niveles de servicio de las intersecciones mejoran, determinando cada 15 minutos durante la hora pico nuevos ciclos semaforizados optimizados con el programa Synchro 10.0 aplicados a Vissim 9.0, pasando de un NS E a D, esto se deduce a partir de la disminución de longitudes de colas en todos los accesos y la reducción de las demoras de viaje, las cuales fueron 14% en la Av. Javier Prado – Ca. Las Flores y 24% en la Av. Javier Prado – Ca. Las Palmeras. / This paper presents the evaluation of vehicular traffic on two signalized intersections located in the city of Lima; one of the world's major cities with high traffic congestion; by microscopic model developed with Vissim 9.0 software. The purpose of this research is to propose the implementation of an intelligent traffic signals to improve service levels and reduce traffic congestion. The process of building the model consists of four stages. First, it is the previous work, in which the field data collection was performed. The model was then constructed by Vissim 9.0 software. After, calibration and validation of the model was performed on both intersections based on psychophysical parameters to certify that the model results resemble the actual conditions of intersections. Finally, new future flows were incorporated into the model every 15 minutes which were simulated and evaluated with the NS obtained, incorporating the proposed improvement. Essentially service levels intersections improve, determining every 15 minutes during rush hour new signalized cycles optimized with Synchro 10.0 program applied to Vissim 9.0, from an NS E to D, It follows from decreasing lengths queues at all entrances and reducing travel delays, which were 14% at Av. Javier Prado -. Ca. Las Flores and 24% on Av. Javier Prado -. Ca. Las Palmeras. / Trabajo de investigación
49

Reliable Broadcast of Safety Messages in Vehicular Ad hoc Networks

Hassanzadeh, Farzad 24 February 2009 (has links)
Broadcast communications is critically important in vehicular networks. Many safety applications need safety warning messages to be broadcast to all vehicles present in an area. In this thesis, we propose a novel repetition-based broadcast protocol based on ``optical orthogonal codes.'' Optical orthogonal codes are used because of their ability to reduce the possibility of collision. We present a detailed mathematical analysis for obtaining the probability of success and the average delay. Furthermore, we propose to use coding to increase network throughput, and ``adaptive elimination'' of potentially colliding transmissions to further increase reliability. We show, by analysis and simulations, that the proposed protocol outperforms existing repetition-based ones and provides reliable broadcast communications and can reliably deliver safety messages under load conditions deemed to be common in vehicular environments. We also show that the proposed protocol is able to provide different levels of quality of service.
50

Reliable Broadcast of Safety Messages in Vehicular Ad hoc Networks

Hassanzadeh, Farzad 24 February 2009 (has links)
Broadcast communications is critically important in vehicular networks. Many safety applications need safety warning messages to be broadcast to all vehicles present in an area. In this thesis, we propose a novel repetition-based broadcast protocol based on ``optical orthogonal codes.'' Optical orthogonal codes are used because of their ability to reduce the possibility of collision. We present a detailed mathematical analysis for obtaining the probability of success and the average delay. Furthermore, we propose to use coding to increase network throughput, and ``adaptive elimination'' of potentially colliding transmissions to further increase reliability. We show, by analysis and simulations, that the proposed protocol outperforms existing repetition-based ones and provides reliable broadcast communications and can reliably deliver safety messages under load conditions deemed to be common in vehicular environments. We also show that the proposed protocol is able to provide different levels of quality of service.

Page generated in 0.0528 seconds