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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.
11

Contribuições ao estudo de implantação de pedágio urbano em São Paulo. / Contributions towards the study of congestion charging systems in São Paulo.

Dias, Felipe Ferreira 01 April 2015 (has links)
A Região Metropolitana de São Paulo (RMSP) sofre de sérios problemas de congestionamento, assim como muitas outras cidades de grande porte. Uma possível solução, proposta por pesquisadores de transportes, economia e ciências ambientais, é a implantação de um sistema de congestion charging, chamada no Brasil de pedágio urbano. Um dos objetivos do presente trabalho foi estabelecer os conceitos relacionados a este assunto e ilustrar as principais questões relacionadas à sua implantação. Espera-se que este trabalho possa auxiliar o desenvolvimento de estudos de avaliação da viabilidade e de impactos de sistemas propostos de congestion charging. Para atingir este objetivo, toca-se em diversos assuntos, como a definição de congestionamento e as formas de medi-lo, a base conceitual e teórica dos sistemas de congestion charging e seus diversos esquemas de diferenciação. São expostas também as medidas de mitigação de congestionamento que já foram implantadas na RMSP, quais foram os estudos já desenvolvidos considerando este tipo de política para a RMSP, e casos em que sistemas de congestion charging já foi implantado. Neste trabalho, desenvolveu-se também um modelo de escolha discreta a partir dos dados da Pesquisa Origem e Destino 2007 do METRÔ, onde pessoas deveriam escolher entre \"Transporte Coletivo\" e \"Transporte Público\". Este modelo foi utilizado para avaliar o potencial de impacto na divisão modal e de arrecadação de um congestion charge aplicado ao centro expandido de São Paulo. Adverte-se, porém, que os resultados obtidos são meramente ilustrativos. Mostra-se, também, que é possível avaliar a capacidade ociosa do sistema de transporte coletivo a partir dos dados disponíveis de bilhetagem e de GPS dos ônibus. Este processo é exemplificado através do cálculo de capacidade de uma única viagem de um único ônibus, dada a dificuldade de automatização deste processo para abranger toda a frota. / The São Paulo Metropolitan Region (SPMR) suffers from severe traffic congestion, as do many other large-scale urban areas around the world. A possible solution to this issue, which has been suggested by transportation, economics and environmental researchers, is the implementation of a congestion charging system. One of the objectives of this project is to establish clear concepts and shed light on the main issues regarding these systems by means of a comprehensive literary review. It is expected that this project may help the development of in-depth studies carried in order to evaluate the viability and impacts of congestion charging proposals. In order to achieve this goal, many subjects are addressed, such as the definition of congestion, how its measured, the theoretical backgrounds that support congestion charging schemes, their different degrees of differentiation, which policies were enacted in order to reduce traffic congestion in São Paulo, what considerations and studies have already been developed for Brazil and São Paulo regarding these systems and where have these systems been successfully installed. Later chapters deal with another goal of this project: estimating how a congestion charging system would affect SPMR. This was achieved through a multinomial logit model, where decision-makers choose between \"Public Transportation\" and \"Private Automobile\". The results presented at this phase are merely indicative of certain tendencies and should not be considered final. This project also attempts to show that given the available Automated Fare Collection (AFC) data and Automated Vehicle Location (AVL) data, it is possible to estimate the current public transportation system\'s unused capacity. The author shows this by calculating the capacity of one bus trip using these data, but also explains the difficulties of expanding this analysis to the whole of SPMR\'s public transportation system.
12

Contribuições ao estudo de implantação de pedágio urbano em São Paulo. / Contributions towards the study of congestion charging systems in São Paulo.

Felipe Ferreira Dias 01 April 2015 (has links)
A Região Metropolitana de São Paulo (RMSP) sofre de sérios problemas de congestionamento, assim como muitas outras cidades de grande porte. Uma possível solução, proposta por pesquisadores de transportes, economia e ciências ambientais, é a implantação de um sistema de congestion charging, chamada no Brasil de pedágio urbano. Um dos objetivos do presente trabalho foi estabelecer os conceitos relacionados a este assunto e ilustrar as principais questões relacionadas à sua implantação. Espera-se que este trabalho possa auxiliar o desenvolvimento de estudos de avaliação da viabilidade e de impactos de sistemas propostos de congestion charging. Para atingir este objetivo, toca-se em diversos assuntos, como a definição de congestionamento e as formas de medi-lo, a base conceitual e teórica dos sistemas de congestion charging e seus diversos esquemas de diferenciação. São expostas também as medidas de mitigação de congestionamento que já foram implantadas na RMSP, quais foram os estudos já desenvolvidos considerando este tipo de política para a RMSP, e casos em que sistemas de congestion charging já foi implantado. Neste trabalho, desenvolveu-se também um modelo de escolha discreta a partir dos dados da Pesquisa Origem e Destino 2007 do METRÔ, onde pessoas deveriam escolher entre \"Transporte Coletivo\" e \"Transporte Público\". Este modelo foi utilizado para avaliar o potencial de impacto na divisão modal e de arrecadação de um congestion charge aplicado ao centro expandido de São Paulo. Adverte-se, porém, que os resultados obtidos são meramente ilustrativos. Mostra-se, também, que é possível avaliar a capacidade ociosa do sistema de transporte coletivo a partir dos dados disponíveis de bilhetagem e de GPS dos ônibus. Este processo é exemplificado através do cálculo de capacidade de uma única viagem de um único ônibus, dada a dificuldade de automatização deste processo para abranger toda a frota. / The São Paulo Metropolitan Region (SPMR) suffers from severe traffic congestion, as do many other large-scale urban areas around the world. A possible solution to this issue, which has been suggested by transportation, economics and environmental researchers, is the implementation of a congestion charging system. One of the objectives of this project is to establish clear concepts and shed light on the main issues regarding these systems by means of a comprehensive literary review. It is expected that this project may help the development of in-depth studies carried in order to evaluate the viability and impacts of congestion charging proposals. In order to achieve this goal, many subjects are addressed, such as the definition of congestion, how its measured, the theoretical backgrounds that support congestion charging schemes, their different degrees of differentiation, which policies were enacted in order to reduce traffic congestion in São Paulo, what considerations and studies have already been developed for Brazil and São Paulo regarding these systems and where have these systems been successfully installed. Later chapters deal with another goal of this project: estimating how a congestion charging system would affect SPMR. This was achieved through a multinomial logit model, where decision-makers choose between \"Public Transportation\" and \"Private Automobile\". The results presented at this phase are merely indicative of certain tendencies and should not be considered final. This project also attempts to show that given the available Automated Fare Collection (AFC) data and Automated Vehicle Location (AVL) data, it is possible to estimate the current public transportation system\'s unused capacity. The author shows this by calculating the capacity of one bus trip using these data, but also explains the difficulties of expanding this analysis to the whole of SPMR\'s public transportation system.
13

Comparison between MATSim & EMME: Developing a Dynamic, Activity-based Microsimulation Transit Assignment Model for Toronto

Kucirek, Peter 20 November 2012 (has links)
Public transit is becoming an increasing important field of study to combat global issues such as traffic congestion and climate change. Accurate simulation of public transit is therefore likewise vital, as it is an important tool for understanding potential impacts of public transit policies. The research presented in this thesis describes the implementation of a multimodal, dynamic, agent-based supply-side simulation model of public transit implemented in the open-source platform MATSim for the city of Toronto. Transit schedule data was converted from Google Transit Feed Specification (GTFS) and map-matched to a region-wide road network to obtain a congestion-based multimodal assignment for transit. Volume-based results from the assignment showed under-prediction of subway volumes and slight over-prediction of bus volumes, but were generally comparable with static EMME/3 assignment for the same data. Travel time analysis indicated that further calibration of network specification is needed.
14

Comparison between MATSim & EMME: Developing a Dynamic, Activity-based Microsimulation Transit Assignment Model for Toronto

Kucirek, Peter 20 November 2012 (has links)
Public transit is becoming an increasing important field of study to combat global issues such as traffic congestion and climate change. Accurate simulation of public transit is therefore likewise vital, as it is an important tool for understanding potential impacts of public transit policies. The research presented in this thesis describes the implementation of a multimodal, dynamic, agent-based supply-side simulation model of public transit implemented in the open-source platform MATSim for the city of Toronto. Transit schedule data was converted from Google Transit Feed Specification (GTFS) and map-matched to a region-wide road network to obtain a congestion-based multimodal assignment for transit. Volume-based results from the assignment showed under-prediction of subway volumes and slight over-prediction of bus volumes, but were generally comparable with static EMME/3 assignment for the same data. Travel time analysis indicated that further calibration of network specification is needed.
15

Arrival Time Predictions for Buses using Recurrent Neural Networks / Ankomsttidsprediktioner för bussar med rekurrenta neurala nätverk

Fors Johansson, Christoffer January 2019 (has links)
In this thesis, two different types of bus passengers are identified. These two types, namely current passengers and passengers-to-be have different needs in terms of arrival time predictions. A set of machine learning models based on recurrent neural networks and long short-term memory units were developed to meet these needs. Furthermore, bus data from the public transport in Östergötland county, Sweden, were collected and used for training new machine learning models. These new models are compared with the current prediction system that is used today to provide passengers with arrival time information. The models proposed in this thesis uses a sequence of time steps as input and the observed arrival time as output. Each input time step contains information about the current state such as the time of arrival, the departure time from thevery first stop and the current position in Cartesian coordinates. The targeted value for each input is the arrival time at the next time step. To predict the rest of the trip, the prediction for the next step is simply used as input in the next time step. The result shows that the proposed models can improve the mean absolute error per stop between 7.2% to 40.9% compared to the system used today on all eight routes tested. Furthermore, the choice of loss function introduces models thatcan meet the identified passengers need by trading average prediction accuracy for a certainty that predictions do not overestimate or underestimate the target time in approximately 95% of the cases.
16

Beyond Food Deserts: Assessing the Impact of Public Transit Availability Change on Spatial Access to Food

Katz, Brandon P. 03 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Food access is a dimension of food security that many struggle with even in high- income countries, which is a contributing factor to chronic diet-related disease. Inequalities in economic access to food has been addressed in public policy for several decades, but spatial access to food has only been seriously studied and addressed by policy for the past twenty-five years. After the food desert metaphor emerged, it was promptly accepted as a standard measure of food access for governments and a basis for policies created to address inequalities. Conceptual criticisms and methodological limitations of the metaphor have led the study of spatial access to food towards newer methods that measure food access more realistically and assist in the development and assessment of intervention strategies to inform policy decisions. This thesis describes the history of the food desert metaphor from its emergence until its adoption in US public policy, the conceptual criticisms and methodological limitations that surround it, and offers an analysis that measures the impact of change in the availability of public transportation on spatial access to food for various population subgroups that are more at risk of food insecurity in Marion County, Indiana. Results demonstrate that policies and plans designed without consideration for food access have an impact on it nevertheless, and that policymakers and planners can leverage such strategies to better coordinate efforts across government to reduce inequalities in spatial access to food and food insecurity overall.
17

Analyse der ÖPNV-Versorgung mittels offener Fahrplandaten – Potenziale, Herausforderungen und Lösungsansätze

Sikder, Sujit Kumar, Ehrig, Nico, Herold, Hendrik, Meinel, Gotthard 27 December 2021 (has links)
Auf der Basis öffentlich und frei verfügbarer Fahrplandaten stellt dieser Beitrag ein Konzept für einen kleinräumigen Indikator (1 km²-Raster) zur ÖPNV-Versorgung vor. Grundlage dieser Studie sind Fahrplandaten des öffentlichen Personenverkehrs im digitalen Austauschformat General Transit Feed Service (GTFS). Mithilfe dieser Daten können ÖPNV-Haltestellen verortet und die Bedienfrequenzen der angebotenen Verkehrsmittelarten ermittelt werden. Die Untersuchung erfolgt am Beispiel des Mitteldeutschen Verkehrsverbundes (MDV), welcher die Großstädte Leipzig und Halle, Mittel- und Kleinstädte sowie ländliche Gebiete umfasst. Für die Datenanalyse wird die räumliche Verteilung mittels GINI und Moran‘s I nach Siedlungsstrukturtypen untersucht.
18

Real-time transit passenger information: a case study in standards development

Reed, Landon T. 13 January 2014 (has links)
As the transportation sector fully integrates information technology, transit agencies face decisions that expose them to new technologies, relationships and risks. Accompanying a rise in transit-related web and mobile applications, a set of competing real-time transit data standards from both public and private organizations have emerged. The purpose of this research is to understand the standard-setting processes for these data standards and the forces that move the transit industry towards the widespread adoption of a data standard. This project will analyze through case studies and interviews with members of standard-setting organizations the development of three real-time transit data standards: (1) the development of the General Transit Feed Specification Realtime (GTFS-realtime), (2) the Service Interface for Real Time Information (SIRI), and (3) Transit Communications Interface Profiles (TCIP). The expected outcome of this research is an assessment of federal policy on standards development as well as an analysis of current and future trends in this sector—both technical and institutional. The results will inform federal transit policy and future action in standards-setting and intelligent transportation systems (ITS) requirements, identifying the potential catalysts that will increase the effectiveness of federal- and agency-level programs.
19

Go with the flow : A study exploring public transit performance using a flow network model

Boman, Axel, Nilsson, Erik January 2020 (has links)
As opposed to public transit agencies' well-developed data generation capabilities, their utilization of their data is often overlooked. This study will tap into the potential of using the GTFS data format from an agency stakeholder perspective to assess transit performance. This format holds data for scheduled transit services, including real-time updates and network organization. The broad adaptation of GTFS by transit agencies (1240 transit networks in 672 locations worldwide) has made it a de-facto standard, making products built on top of it inherently scalable and could potentially be deployed in networks all over the world. The purpose of this thesis is two-fold; firstly, to explore how specific vulnerability features of nodes in a public transit network can be assessed using graph mining algorithms. Secondly, to develop a pipeline for aggregating GTFS data and fit it into a flow network model. The results include a data-driven framework for vulnerability characterization, a method for fitting GTFS data in a flow network model, and lastly, a definition for reduced flow capacity in a public transit context. Additionally, the results are presented in the setting of Uppsala's network (UL) and visualized with a web-based tool.
20

Evaluating the Approximate Location Feature in Android : An analysis of the built in Location Privacy Protection of Android 12 / Analys av ungefärlig platsdelning i Android : En analys av de inbyggda integritetsskydden vid platsdelning i Android 12

Loxdal, Joakim January 2023 (has links)
Smartphone users share their locations with location based services (navigation apps, dating apps, fitness trackers, etc.). These services can be useful, but introduce privacy concerns. Strategies have been suggested in academic literature to counter these location privacy issues while still maintaining some utility of the location based services. In practice, Google introduced a new location privacy protection mechanism in Android 12. Users are now able to share only their approximate location with any app that request their location. In this thesis, the Approximate Location feature in Android 12 is evaluated and tested in different scenarios (on device and simulated) to decide its potential benefits and drawbacks for a users location privacy. The source code analysis show that the Approximate Location feature uses a grid mapping (’snap-togrid’) technique to make locations less precise and adds a random offset to make it more difficult to reveal when a user crosses a grid border. Over longer time periods, an attacker can exploit the random offset to reveal a more precise location than intended. The random offset will change gradually, meaning a precise location can result in several approximate locations. By averaging the approximate locations that a stationary precise location generates over time, one could potentially create a new more precise location than the approximate ones. Simulations and some real world experiments on an Android 12 device show that this attack could be feasible, but that since the random offset only updates every hour the attack would be very time consuming. The simulations showed that when approximate locations were shared for one precise location 10,000 times (hours in practice), the mean approximate location was on average 478 meters away from the precise location, compared to 986 meters on average if the approximate location was only shared once. Analysis made on recorded and simulated locations show that even though the approximate locations use a grid with 2 km granularity, many public transport routes can be inferred. The success of unambiguously inferring a public transport trip using a users approximate locations depends on the length of the trip (the longer the easier) and on how many other public transport trips share the route or sub route of the trip (the more trips that share the route, the harder it is to infer the correct one). By combining historical approximate location data and public transport data, results indicate that 80.52% of the bus routes in the Region of Skåne in Sweden could be inferred if a user travels the full route. / Smartphoneanvändare delar sin platsdata med mobilapplikationer, s.k. ’location based services’ (LBS). Exempel på sådana applikationer är navigationsappar, dejtingappar och träningsappar. Dessa applikationer kan vara värdefulla för användaren, men leder även till ökade integritetsproblem. Teoretiska och praktiska metoder har föreslagits för att begränsa dessa problem utan att applikationernas funktionalitet drabbas i för hög grad. I praktiken så introducerades ett antal nya integritetsskyddande funktioner i Android 12 för att ge användaren mer kontroll över sin platsintegritet (location privacy). Nu kan användare välja att dela enbart sina ungefärliga platser till appar som efterfrågar deras platsdata. Denna funktion kallas ”Approximate Location” (ungefärlig plats). I denna masteruppsats undersöks denna funktion ur ett integritetsperspektiv, och testas i olika scenarion (både verkliga och simulerade). Detta görs för att avgöra funktionens fördelar och begränsningar när det kommer till användares platsintegritet. Källkodsanalysen visar att den den ungefärliga platsen genereras genom en ’snap-to-grid’ eller ’grid masking’-teknik som gör platsen som delas mindre exakt. Kortfattat kan det beskrivas som att världen delas upp i ett rutnät med horisontella och vertikala linjer där användarens plats avrundas till den närmaste brytpunkt mellan två linjer. Dessutom flyttas platsen slumpmässigt mellan varje delning vilket gör det svårare för en angripare att avgöra när användaren rör sig mellan olika rutor i rutnätet. Simulationer och experiment på Android-enheter visar att ju längre en smartphone delar sin ungefärliga plats, desto mer avslöjas om den exakta. När ungefärliga platser som korresponderade mot en stillastående exakt plats delades 10 000 gånger och avrundades så var den avrundade platsen i genomsnitt 478 meter ifrån den exakta platsen. Detta kan jämföras med 986 meter i genomsnitt om den ungefärliga platsen bara delades en gång. Analys som utfördes med simulerad platsdata visar att även om positionerna genereras på ett rutnät med 2 kilometers avstånd mellan linjerna så kan resor med kollektivtrafik exponeras, trots att enbart ungefärliga platser delas. Hur enkelt det är att exponera rutten beror på hur lång resan är (ju längre desto enklare), och hur många andra rutter som liknar resan (ju fler, desto svårare). Baserat på simulerade ungefärliga platser längs kollektivtrafikrutter kombinerat med kollektivtrafikdata, indikerar resultaten att 80.53% av alla bussrutter i region Skåne kan exponeras om en person delar sin ungefärliga plats längs hela rutten.

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