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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.
31

Um sistema de roteirização via internet para o campus da USP de Ribeirão Preto / A system of internet routing service for addresing at campus of University of São Paulo in Ribeirão Preto

Costa, Airton Manoel Romero 26 March 2004 (has links)
Neste trabalho uma metodologia é proposta para disponibilizar, via internet, um serviço de roteirização de endereços para o campus da USP de Ribeirão Preto, com a determinação do menor caminho entre duas localidades. Esta metodologia pode ser aplicada não apenas ao campus da USP de Ribeirão Preto, mas ela poderá ser estendida às cidades e/ou regiões que possuam um mapa digital correspondente. Um sistema, denominado SIGRIB, foi desenvolvido para implementar a metodologia proposta. Utiliza o software ARCVIEW como suporte na manipulação de dados geográficos e cadastrais. Para facilitar a interação do usuário com o sistema SIGRIB, uma interface foi desenvolvida para que se possa fornecer duas localidades para as quais se deseja obter o menor caminho. O resultado desta consulta é uma figura ou conjunto de figuras contendo o menor caminho correspondente destacado. O sistema SIGRIB está disponível na internet (http://143.107.231.188/sigrib/pagina.asp) e vários testes são apresentados neste trabalho que demonstram o seu bom desempenho. / In this work a methodology is proposal to turn available, through internet, a routing service for addressing at campus of University of São Paulo, in Ribeirão Preto, including the determination of shortest way between two localities. This methodology can be applied not only to this campus but it can be extended to various cities and/or regions that have a corresponding digital map. A system, called SIGRIB, has been developed for implementing the proposed methodology. It utilizes ARCVIEW software as support for manipulation of geographical and cadastral data. To turn easy the interaction of user with SIGRIB system, a interface has been also implemented for that can provide two localities for which it desires to obtain the shortest path. The result of this search is a figure or set of figures containing the corresponding shortest path highlighted. The system SIGRIB is available in the internet (http://143.107.231.188/sigrib/pagina.asp) and several tests are presented in this work that demonstrate its good performance.
32

Análise da compatibilidade do gabarito de caminhões com a geometria das interseções urbanas numa cidade de médio porte / Analysis of template compatibility of trucks with the urban intersections geometry in a medium-sized city

Costa, Ely Emerson Santos da 14 May 1997 (has links)
Este trabalho tem a finalidade de analisar a compatibilidade do gabarito dos caminhões brasileiros com a geometria das interseções urbanas de uma cidade de médio porte. Foi utilizado um Sistema de Informações Geográficas para a elaboração de rotas de menor caminho, dentro da área de estudo. Foram realizados levantamentos de campo para a reconstituição da geometria das interseções. Em seguida, através de um programa de simulação cada conversão necessária foi analisada para saber se havia a possibilidade de realização da manobra, dentro das rotas de menor caminho. / This work has the objective of analyzing the template compatibility, of Brazilian trucks with the urban intersections geometry in a medium-sized city. It was used a Geographic Information System to elaborate the shortest path within the study area. Field data were carried out for reconstitution of the intersections geometry. Next, each necessary conversion was analyzed, through a simulation program in order to know if the trucks were able to negotiate the curves in the shortest path routes.
33

Análise da compatibilidade do gabarito de caminhões com a geometria das interseções urbanas numa cidade de médio porte / Analysis of template compatibility of trucks with the urban intersections geometry in a medium-sized city

Ely Emerson Santos da Costa 14 May 1997 (has links)
Este trabalho tem a finalidade de analisar a compatibilidade do gabarito dos caminhões brasileiros com a geometria das interseções urbanas de uma cidade de médio porte. Foi utilizado um Sistema de Informações Geográficas para a elaboração de rotas de menor caminho, dentro da área de estudo. Foram realizados levantamentos de campo para a reconstituição da geometria das interseções. Em seguida, através de um programa de simulação cada conversão necessária foi analisada para saber se havia a possibilidade de realização da manobra, dentro das rotas de menor caminho. / This work has the objective of analyzing the template compatibility, of Brazilian trucks with the urban intersections geometry in a medium-sized city. It was used a Geographic Information System to elaborate the shortest path within the study area. Field data were carried out for reconstitution of the intersections geometry. Next, each necessary conversion was analyzed, through a simulation program in order to know if the trucks were able to negotiate the curves in the shortest path routes.
34

Um sistema de roteirização via internet para o campus da USP de Ribeirão Preto / A system of internet routing service for addresing at campus of University of São Paulo in Ribeirão Preto

Airton Manoel Romero Costa 26 March 2004 (has links)
Neste trabalho uma metodologia é proposta para disponibilizar, via internet, um serviço de roteirização de endereços para o campus da USP de Ribeirão Preto, com a determinação do menor caminho entre duas localidades. Esta metodologia pode ser aplicada não apenas ao campus da USP de Ribeirão Preto, mas ela poderá ser estendida às cidades e/ou regiões que possuam um mapa digital correspondente. Um sistema, denominado SIGRIB, foi desenvolvido para implementar a metodologia proposta. Utiliza o software ARCVIEW como suporte na manipulação de dados geográficos e cadastrais. Para facilitar a interação do usuário com o sistema SIGRIB, uma interface foi desenvolvida para que se possa fornecer duas localidades para as quais se deseja obter o menor caminho. O resultado desta consulta é uma figura ou conjunto de figuras contendo o menor caminho correspondente destacado. O sistema SIGRIB está disponível na internet (http://143.107.231.188/sigrib/pagina.asp) e vários testes são apresentados neste trabalho que demonstram o seu bom desempenho. / In this work a methodology is proposal to turn available, through internet, a routing service for addressing at campus of University of São Paulo, in Ribeirão Preto, including the determination of shortest way between two localities. This methodology can be applied not only to this campus but it can be extended to various cities and/or regions that have a corresponding digital map. A system, called SIGRIB, has been developed for implementing the proposed methodology. It utilizes ARCVIEW software as support for manipulation of geographical and cadastral data. To turn easy the interaction of user with SIGRIB system, a interface has been also implemented for that can provide two localities for which it desires to obtain the shortest path. The result of this search is a figure or set of figures containing the corresponding shortest path highlighted. The system SIGRIB is available in the internet (http://143.107.231.188/sigrib/pagina.asp) and several tests are presented in this work that demonstrate its good performance.
35

An Evaluation of Shortest Path Algorithms on Real Metropolitan Area Networks

Johansson, David January 2008 (has links)
<p>This thesis examines some of the best known algorithms for solving the shortest point-to-point path problem, and evaluates their performance on real metropolitan area networks. The focus has mainly been on Dijkstra‟s algorithm and different variations of it, and the algorithms have been implemented in C# for the practical tests. The size of the networks used in this study varied between 358 and 2464 nodes, and both running time and representative operation counts were measured.</p><p>The results show that many different factors besides the network size affect the running time of an algorithm, such as arc-to-node ratio, path length and network structure. The queue implementation of Dijkstra‟s algorithm showed the worst performance and suffered heavily when the problem size increased. Two techniques for increasing the performance were examined: optimizing the management of labelled nodes and reducing the search space. A bidirectional Dijkstra‟s algorithm using a binary heap to store temporarily labelled nodes combines both of these techniques, and it was the algorithm that performed best of all the tested algorithms in the practical tests.</p><p>This project was initiated by Netadmin Systems i Sverige AB who needed a new path finding module for their network management system NETadmin. While this study is primarily of interest for researchers dealing with path finding problems in computer networks, it may also be useful in evaluations of path finding algorithms for road networks since the two networks share some common characteristics.</p>
36

Estimating freight costs over a multi-modal network: an auto industry supply chain example

Moore, Amy Marie 10 April 2013 (has links)
The objective of this research is to implement multi-modal cost calculations on a freight transportation network, in order to estimate the cost of freight shipments from parts suppliers to original equipment manufacturers (OEMs), and from OEMs to final consumers involved in the automobile manufacturing industry supply chain. The research will describe gaps in the current freight cost estimation literature, determine the strengths and weaknesses of current practices, and offer possible improvement strategies. The necessary components for this research include: a multi-modal (highway-rail-water-air) network database, the geocoded locations and activity levels of auto industry parts suppliers and OEMs; freight movement cost functions; information on the modes and vehicle/vessel types used for the shipment of certain commodity types; and distance- based travel costs per-mile for these modes. A product of this line of research will be a method that other industries, in other locations, might also use to determine overall freight transportation costs throughout an entire supply chain. The present research effort provides an example using data gathered on the automobile manufacturing industry centered in Georgia and Alabama. The network-based freight costs derived in this research should also be useful in other applications, including the estimation of origin-to-destination flows, as well as in the estimation of transportation costs used in regional and statewide freight planning models.
37

A Scalable Partial-Order Data Structure for Distributed-System Observation

Ward, Paul January 2001 (has links)
Distributed-system observation is foundational to understanding and controlling distributed computations. Existing tools for distributed-system observation are constrained in the size of computation that they can observe by three fundamental problems. They lack scalable information collection, scalable data-structures for storing and querying the information collected, and scalable information-abstraction schemes. This dissertation addresses the second of these problems. Two core problems were identified in providing a scalable data structure. First, in spite of the existence of several distributed-system-observation tools, the requirements of such a structure were not well-defined. Rather, current tools appear to be built on the basis of events as the core data structure. Events were assigned logical timestamps, typically Fidge/Mattern, as needed to capture causality. Algorithms then took advantage of additional properties of these timestamps that are not explicit in the formal semantics. This dissertation defines the data-structure interface precisely, and goes some way toward reworking algorithms in terms of that interface. The second problem is providing an efficient, scalable implementation for the defined data structure. The key issue in solving this is to provide a scalable precedence-test operation. Current tools use the Fidge/Mattern timestamp for this. While this provides a constant-time test, it requires space per event equal to the number of processes. As the number of processes increases, the space consumption becomes sufficient to affect the precedence-test time because of caching effects. It also becomes problematic when the timestamps need to be copied between processes or written to a file. Worse, existing theory suggested that the space-consumption requirement of Fidge/Mattern timestamps was optimal. In this dissertation we present two alternate timestamp algorithms that require substantially less space than does the Fidge/Mattern algorithm.
38

Optimal Path Searching through Specified Routes using different Algorithms

Farooq, Farhan January 2009 (has links)
To connect different electrical, network and data devices with the minimum cost and shortest path, is a complex job. In huge buildings, where the devices are placed at different locations on different floors and only some specific routes are available to pass the cables and buses, the shortest path search becomes more complex. The aim of this thesis project is, to develop an application which indentifies the best path to connect all objects or devices by following the specific routes.To address the above issue we adopted three algorithms Greedy Algorithm, Simulated Annealing and Exhaustive search and analyzed their results. The given problem is similar to Travelling Salesman Problem. Exhaustive search is a best algorithm to solve this problem as it checks each and every possibility and give the accurate result but it is an impractical solution because of huge time consumption. If no. of objects increased from 12 it takes hours to search the shortest path. Simulated annealing is emerged with some promising results with lower time cost. As of probabilistic nature, Simulated annealing could be non optimal but it gives a near optimal solution in a reasonable duration. Greedy algorithm is not a good choice for this problem. So, simulated annealing is proved best algorithm for this problem. The project has been implemented in C-language which takes input and store output in an Excel Workbook
39

A Scalable Partial-Order Data Structure for Distributed-System Observation

Ward, Paul January 2001 (has links)
Distributed-system observation is foundational to understanding and controlling distributed computations. Existing tools for distributed-system observation are constrained in the size of computation that they can observe by three fundamental problems. They lack scalable information collection, scalable data-structures for storing and querying the information collected, and scalable information-abstraction schemes. This dissertation addresses the second of these problems. Two core problems were identified in providing a scalable data structure. First, in spite of the existence of several distributed-system-observation tools, the requirements of such a structure were not well-defined. Rather, current tools appear to be built on the basis of events as the core data structure. Events were assigned logical timestamps, typically Fidge/Mattern, as needed to capture causality. Algorithms then took advantage of additional properties of these timestamps that are not explicit in the formal semantics. This dissertation defines the data-structure interface precisely, and goes some way toward reworking algorithms in terms of that interface. The second problem is providing an efficient, scalable implementation for the defined data structure. The key issue in solving this is to provide a scalable precedence-test operation. Current tools use the Fidge/Mattern timestamp for this. While this provides a constant-time test, it requires space per event equal to the number of processes. As the number of processes increases, the space consumption becomes sufficient to affect the precedence-test time because of caching effects. It also becomes problematic when the timestamps need to be copied between processes or written to a file. Worse, existing theory suggested that the space-consumption requirement of Fidge/Mattern timestamps was optimal. In this dissertation we present two alternate timestamp algorithms that require substantially less space than does the Fidge/Mattern algorithm.
40

Shortest Path Queries in Very Large Spatial Databases

Zhang, Ning January 2001 (has links)
Finding the shortest paths in a graph has been studied for a long time, and there are many main memory based algorithms dealing with this problem. Among these, Dijkstra's shortest path algorithm is one of the most commonly used efficient algorithms to the non-negative graphs. Even more efficient algorithms have been developed recently for graphs with particular properties such as the weights of edges fall into a range of integer. All of the mentioned algorithms require the graph totally reside in the main memory. Howevery, for very large graphs, such as the digital maps managed by Geographic Information Systems (GIS), the requirement cannot be satisfied in most cases, so the algorithms mentioned above are not appropriate. My objective in this thesis is to design and evaluate the performance of external memory (disk-based) shortest path algorithms and data structures to solve the shortest path problem in very large digital maps. In particular the following questions are studied:What have other researchers done on the shortest path queries in very large digital maps?What could be improved on the previous works? How efficient are our new shortest paths algorithms on the digital maps, and what factors affect the efficiency? What can be done based on the algorithm? In this thesis, we give a disk-based Dijkstra's-like algorithm to answer shortest path queries based on pre-processing information. Experiments based on our Java implementation are given to show what factors affect the running time of our algorithms.

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