Biblioteca Digital

A computação reconfigurável está se fortalecendo cada vez mais devido ao grande avanço dos dispositivos reprogramáveis e ferramentas de projeto de hardware utilizadas atualmente. Isso possibilita que o desenvolvimento de hardware torne-se bem menos trabalhoso e complicado, facilitando assim a vida do desenvolvedor. A tecnologia utilizada atualmente em projetos de computação reconfigurável é denominada FPGA (Field Programmable Gate Array), que une algumas características tanto de software (flexibilidade), como de hardware (desempenho). Isso fornece um ambiente bastante propício para desenvolvimento de aplicações que precisam de um bom desempenho, sem que estas devam possuir uma configuração definitiva. O objetivo deste trabalho foi implementar um barramento eficiente para possibilitar a comunicação entre diferentes CORES de um robô reconfigurável, que podem estar dispersos em diferentes dispositivos FPGAs. Tal barramento seguirá o padrão AMBA (Advanced Microcontroller Bus Architecture), pertencente à ARM. Todo o desenvolvimento do core completo do AMBA foi realizado utilizando-se a linguagem VHDL (Very High Speed Integrated Circuit Hardware Description Language) e ferramentas EDAs (Electronic Design Automation) apropriadas. É importante notar que...

Esta dissertação investiga a influência de diversos fatores intervenientes nas emissões veiculares em corredores de ônibus de alta capacidade, conhecidos como BRT Bus Rapid Transit. Esses sistemas têm sido adotados em cidades de todo o mundo devido a possibilidade de atender demandas elevadas a custos relativamente baixos quando comparados com alternativas sobre trilhos, com nível de serviço adequado e possibilitando a redução de emissões. Três categorias de variáveis foram consideradas: (i) variáveis que são função do projeto do corredor de ônibus (infraestrutura, especificações tecnológicas e operacionais); (ii) variáveis que são afetadas pela implantação do corredor (impactos na velocidade média dos outros veículos, utilização de rotas alternativas e transferência modal); (iii) variáveis que dependem de políticas públicas (como mudanças do tipo de combustível ou programas de inspeção veicular). As emissões foram estimadas através de dois procedimentos. Preferencialmente utilizou-se o modelo IVE International Vehicle Emissions, que se baseia no ciclo de condução dos veículos (perfil de variação da velocidade segundo a segundo). Em alguns casos, as estimativas utilizaram resultados de medidas de emissões realizadas pelo IPT Instituto de Pesquisas Tecnológicas...

Esta dissertação trata dos abrigos para usuários em pontos de parada de ônibus na cidade de São Paulo, que são popularmente conhecidos como abrigo de ônibus. Toma como exemplo a produção mais recente no município: os abrigos SP450 e Barbosa & Corbucci (B&C), implantados na gestão da prefeita Marta Suplicy - 2001-2004. Apresenta os abrigos enfocando seus aspectos de concepção, produção e implantação, e os analisa através de suas características de mobiliário urbano e as relações com o sistema de transporte público urbano. Ao observar sua inserção dentro do funcionamento do sistema de transporte e da situação política, evidenciam-se os desvios entre a concepção das propostas e a realidade de sua implantação. Conforme verificado na pesquisa realizada, o desenvolvimento de uma peça de mobiliário abrange uma ampla escala - desde o planejamento urbano até detalhamento de projeto - com interface em diversas áreas do conhecimento: design e produção, instalação e manutenção de peças e serviços, legislação, exploração econômica, gestão de espaço público, gestão de infra-estrutura urbana, entre outras. Longe de esgotar o tema, a pesquisa documenta a atual condição de permanência na cidade...

Este trabalho é um modelo para controle de operação de frota de ônibus público urbano de baixa demanda, que objetiva o monitoramento (e intervenção, quando necessário), de forma que os ônibus monitorados cumpram a programação predeterminada pela grade-horária, evitando assim situações indesejáveis como atrasos ou congestionamentos nas estações de embarque e desembarque. A gestão do controle da movimentação dos ônibus se baseia em intervenções a serem realizadas na frota, considerando-se o sistema Bus Rapid Transit, que possui como grande diferencial as faixas segregadas para circulação dos ônibus. O objetivo é propor intervenções na frota (ações enviadas diretamente ao motorista como, por exemplo, diminuir a velocidade), e analisar os resultados, de forma a contribuir para diminuir dois grandes problemas em transporte público urbano: (1) o não cumprimento dos horários e (2) congestionamentos nas estações. Esses dois problemas geram reações em cadeia que acabam também afetando a regularidade de outros ônibus que compartilhar a mesma via e estações. Instituições públicas ou privadas de ônibus urbano podem obter benefícios utilizando um bom sistema de monitoramento e controle de frota, como por exemplo: mais segurança e previsibilidade nos horários...

Esta dissertação teve como objetivo principal investigar a influência, no comportamento de escolha de linha de passageiros de ônibus, de painéis eletrônicos em pontos de parada com informação em tempo real sobre previsões para passagem dos veículos. Para a coleta de dados, um experimento de escolha declarada com desenho eficiente foi aplicado a uma amostra de 1179 entrevistados residentes na Região Metropolitana de São Paulo (RMSP) e pertencentes à comunidade da Universidade de São Paulo. Em cada situação de escolha foram apresentadas duas linhas diferentes de ônibus que chegariam ao mesmo destino, mas não passavam pelo mesmo ponto, de modo que a escolha a ser feita era entre uma ou outra combinação de linha e ponto. Adicionalmente, apenas um dos pontos tinha painel eletrônico. As alternativas também se diferenciavam pelos seguintes atributos: intervalo de tempo programado para a passagem de veículos consecutivos da mesma linha; possível atraso em relação ao intervalo programado; tempo de viagem dentro do veículo até o destino; ocupação do veículo quando chega ao ponto; e valor da tarifa. Na amostra predominaram jovens com até 25 anos (64% da amostra), homens (60%), usuários frequentes de ônibus (80%)...

The purpose of this work is to study voltage control and energy balance of a split DC bus topology within a power electronics equipment connected to the AC mains, such as UPS systems, wind power generators, active filters and FACTS devices. A typical configuration in such equipment has two mains connected converters sharing a common DC bus, one series connected and the other parallel connected. The DC bus is usually composed by a battery or a capacitor bank. In the proposed topology, the DC bus is divided in two sides, interconnected with a buck-boost converter, which controls power flow and DC voltage on both sides. © 2009 IEEE.

The collective intercity transportation by bus is currently a mean of locomotion much sought after by people. Security in accidents is a very important factor that must be taken into account in design of bus body structure, being the evaluation of passenger safety of this type of vehicle is an important subject that should be checked, because in many accidents occur disconnection between seats and fastening members causing serious passengers injury, often fatal. This work aims at evaluation the behavior of frame fixing of seats of intercity bus bodies, submitted to the frontal impact situation in a rigid wall of 100% offset, through evaluation by finite element method (FEM). This study uses a numerical model corresponding to the body structure and chassis, developed through flexible beam elements, combining with shell elements for the structure of the seats and its fastening members, with the objective of not missing the essential aspects of the problem, allowing the solution with a reduced computational time. The numerical model of bus body and seat was impacted against a rigid wall at a speed of 8.89 m/s, being its validation according to the deceleration curve established by Regulation 80. Then it was gotten the Von Mises stress in fastening members of the seat structure in bus body. It is also presented a proposal to improve the fastening of the seat structure...

Public transportation users are constantly in search of regular service, fair cost, high safety, and physical and psychological comfort. Creating a system for bus route evaluation (BRE) can be considered to be among the basic requirements for public transportation management in cities. The need for a logical and scientific tool to support the decisions made by the policy makers of public transportation for the purpose of a higher quality of the services, specifically in a developing metropolitan such as Shiraz, Iran, proves the importance of such a system. In this study, firs, six routes among the 71 bus routes of metropolitan Shiraz were chosen. Subsequently, 16 criteria based on the theoretical literature and the data collected in a survey conducted by the Shiraz Public Bus Organization (SPBO) were produced. Then by using a two-stage multiple-criteria decision making (MCDM) model containing hierarchical Fuzzy Analytical Hierarchal Process (Fuzzy AHP) and TOPSIS methods the data was analyzed and the existing situation of the selected bus routes was evaluated. This study and the presented evaluation framework for the analysis of the current situation along with the comparison of the bus routes can help the managers and policy makers of bus transportation on their way to improving the services...

Este trabalho tem como objetivo avaliar a confiabilidade do transporte coletivo urbano por ônibus tendo como base o corredor estrutural de ônibus da Avenida João Naves de Ávila, uma das principais vias da cidade de Uberlândia, MG. Para tanto, foram utilizados os programas computacionais Simulation and Assignment of Traffic in Urban Road Networks – SATURN e Dynamic Route Assignment Combining User Learning and Microsimulation – DRACULA. Os programas, ambos desenvolvidos pela Universidade de Leeds, na Inglaterra, foram usados na execução das simulações necessárias para concluir quanto ao efeito que a implantação do corredor de ônibus acarretou sobre a linha de ônibus que percorre a avenida. É apresentada uma análise sobre a confiabilidade do transporte coletivo urbano na avenida, onde foi implantada uma faixa exclusiva para ônibus e treze estações de embarque e desembarque, por meio de indicadores como tempo de viagem, regularidade e pontualidade, entre outros. Além do cenário básico, foram propostos cenários variados a fim de verificar como os indicadores de confiabilidade seriam afetados. Por fim, esse trabalho traz a comparação entre os tempos de viagem antes e após a implantação do corredor e visa concluir sobre os benefícios reais da implantação de um corredor de ônibus em cidades médias. ______________________________________________________________________________ ABSTRACT; The aim of this work is to evaluate the reliability of the urban public transport using as a study case the bus structural corridor in the João Naves de Ávila Avenue...

peer-reviewed; Most cities have special lanes dedicated to buses, however these lanes are rarely used at full capacity. At the same time governments around the world are encouraging people to buy electric vehicles. This paper proposes the creation of electric vehicle enhanced dedicated bus lanes (E-DBL), by allowing electric vehicles access to bus lanes, in order to improve the use of road capacity. By opening bus lanes to electric vehicles, traffic congestion could be eased, the range of electric vehicles could be extended, and the travel times for electric vehicle owners could be reduced significantly. The paper shows how by introducing EDBLs, the bus journey times are not significantly affected given the current uptake of electric vehicles in most developed countries. This paper presents extensive simulations based on traffic situation in the city of Dublin with regard to the effect of opening up bus lanes to electric vehicles. The results show that even with very high percentages of electric vehicles the bus journey times are not noticeably affected. Opening up bus lanes to electric vehicles can even be beneficial for other road users by reducing congestion on regular lanes, which would further reduce carbon emissions.

El trabajo de grado, que se presenta en este documento, corresponde a la tercera implementación en hardware de PCSIM, proyecto de larga trayectoria que empezó a desarrollarse en 1999, teniendo como fin el aprendizaje y comprensión de la arquitectura de un procesador. Este proyecto se llevó a cabo sobre la segunda versión en hardware correspondiente a BINARIC (trabajo de grado), realizando un estudio a fondo del proyecto para así realizar algunas modificaciones en los temas de interrupciones y de bus espía, permitiendo así la simplificación de la estructura original para que el estudiante tenga un mayor entendimiento de la asignatura. Para el desarrollo del proyecto se empleó la metodología de diseño digital que se ha venido desarrollando en las asignaturas de Técnicas Digitales; el diseño de un sistema digital empieza por la descripción del sistema, un diagrama de bloques, descripción en AHPL (A Hardware Programming Language), descripción en VHDL (VHSIC Hardware description Language), simulación en el software de ALTER QUARTUS II versión 9.1 y finalmente, implementación sobre la FPGA (Field Programmable Gate array).; The Degree workshop developed continues a huge project called PCSIM; PCSIM is an emulator of a processor which enables the student to understand the basic principles of processor architecture. It started in 1999...

The authors make the case for the return of regulation in the organization of urban bus services in developing countries. During the past three decades urban public transport policy has gone through several phases. The 1980s and 1990s were characterized by liberalization of the sector from public ownership and monopoly provision. The experience of several countries, in particular Chile, indicates that a full liberalization of the sector may not be the welfare-maximizing option. The authors discuss the market failures that justify this claim and present the regulatory options available in this emerging new role of government. Throughout the paper they illustrate ideas with examples from Chile, Colombia, and a few other countries.

In recent years helpful guides have appeared in both English and Spanish to assist planners and officials to construct accessible buildings and pedestrian infrastructure which are usable by seniors, persons with disabilities, and all others who especially benefit from universal design. Less has been written about access to public transport systems. Very little guidance is available concerning specific issues which confront those planning Bus Rapid Transit (BRT) systems, mass transit systems which incorporate a spectrum of design and operational features on integrated trunk and feeder routes and which were initiated in Latin America and are now spreading throughout the region and beyond. The guidelines focus on the BRT environment and assume that interested parties can take advantage of existing guidelines to clarify general issues of access to public space, buildings, and pedestrian infrastructure. The guidelines generally follow the travel path of a passenger using a full-featured Bus Rapid Transit system. The accessible travel chain begins with sidewalks and pedestrian crossings and continues into a typical mid-island station served by buses with left-side doors (in countries where traffic drives on the right side). Buses pull up to an enclosed station with a ramped platform the height of the bus floor. The guidelines then focus on station features...

Bus stops are key links in the journeys of transit patrons with disabilities. Inaccessible bus stops prevent people with disabilities from using fixed-route bus services, thus limiting their mobility. The Americans with Disabilities Act (ADA) of 1990 prescribes the minimum requirements for bus stop accessibility by riders with disabilities. Due to limited budgets, transit agencies can only select a limited number of bus stop locations for ADA improvements annually. These locations should preferably be selected such that they maximize the overall benefits to patrons with disabilities. In addition, transit agencies may also choose to implement the universal design paradigm, which involves higher design standards than current ADA requirements and can provide amenities that are useful for all riders, like shelters and lighting. Many factors can affect the decision to improve a bus stop, including rider-based aspects like the number of riders with disabilities, total ridership, customer complaints, accidents, deployment costs, as well as locational aspects like the location of employment centers, schools, shopping areas, and so on. These interlacing factors make it difficult to identify optimum improvement locations without the aid of an optimization model. This dissertation proposes two integer programming models to help identify a priority list of bus stops for accessibility improvements. The first is a binary integer programming model designed to identify bus stops that need improvements to meet the minimum ADA requirements. The second involves a multi-objective nonlinear mixed integer programming model that attempts to achieve an optimal compromise among the two accessibility design standards. Geographic Information System (GIS) techniques were used extensively to both prepare the model input and examine the model output. An analytic hierarchy process (AHP) was applied to combine all of the factors affecting the benefits to patrons with disabilities. An extensive sensitivity analysis was performed to assess the reasonableness of the model outputs in response to changes in model constraints. Based on a case study using data from Broward County Transit (BCT) in Florida...

Bogota, the capital city of Colombia, is located near the geographic center of Colombia, 2,640 meters (8,661 ft) sea level. It is the largest and most populous city in the nation, with an estimated 8.2 million inhabitants in the metropolitan area in 2007 and a population density of 3,912 inhabitants per square kilometer. Its economy generates 25 percent of Colombia's total gross domestic product (GDP). The city's roads were highly congested with the significant growth in private car ownership and use. While private cars occupied 64 percent of the road space, they only represented 19 percent of the population, and the daily average commute time was 1 hour and 10 minutes each way. Other issues included high incidences of accidents and extremely high air pollution rates during peak travel hours. In 1999, after the new National Government rejected potential plans for a subway system, the Mayor of Bogota presented his plan for a Bus Rapid Transit (BRT) system, built upon the successful experience of Curitiba in Brazil. The transition to an effective BRT system would help realize the Mayor's four main goals by: (i) improving public transport system with respect to efficiency...

Buses are the most common form of urban transit but, in the developing world, are often seen as inefficient and polluting. It is well known that buses that are properly tuned and adjusted tend to be cleaner, safer and consume less fuel than poorly maintained buses. Fuel cost is a relatively large fraction of total cost especially when labor and bus costs are low, as in many developing countries. Hence, reducing fuel use through targeted maintenance of fuel inefficient buses can reduce significant expenditures especially in developing countries, freeing up resources for other improved city services. In addition, if city buses do not receive periodic maintenance that is adequate in quality and quantity, their emissions, both local and global, will suffer. In an effort to catalyze solutions for urban transport, the World Bank Group focused on development of a global Knowledge Product in the form of a 'Guidance Note' (GN) on bus maintenance procedures. The GN is directed towards city transit managers and their technical staff in developing countries to enhance the energy efficiency of city transit. The objective of this work effort is to prepare a Guidance Note (GN) on maintenance best practices that is a practical and useful tool to guide the implementation of a program that will enhance the fuel efficiency of buses. To address this objective...

In most large cities in developing countries, buses continue to be the public transport option of choice, carrying a large share of urban travelers. However, transit bus companies in these countries are often cash-strapped. In many cases, the operating cost per bus kilometer exceeds revenues and bus fares are often kept low irrespective of the cost of providing service. Many cities are dominated by old and fuel-intensive buses with high operating costs. Transit systems are also often plagued by overcrowded and undependable service, congested roadways and chaotic operating environments. Across the board, city officials in developing countries are under strong pressure to improve the efficiency and enhance the attractiveness of bus transportation. Fuel makes up a relatively large fraction of total bus operating costs, especially when labor costs are low, as in many developing countries. Fuel costs can be reduced by improving the driving style of bus drivers and through sound maintenance practices. A safe and economical driving style can reduce variable costs...

O estudo de diferentes "bus" de comunicação paralela utilizados em arquiteturas multi-microprocesssodores ("bus" das estruturas SM 90, MULTIBUS e VME), assim que suas técnicas de arbitragem respectivas, nos permitiram de conduzir nosso trabalho sobre o estudo de compatibilidade do circuito integrado arbitro de bus ABC 90 da estrutura SM 90 (cujas funções são as mais potentes) com os outros tipos de "bus" (MULTIBUS e VME). A primeira etapa de nosso estudo se traduz pela proposição de utilização do circuito ABC 90 com órgão de alocação de "bus" em diferentes configurações arquiteturais multi-microprocessadores através da introdução de componentes discretos. A segunda etapa consiste na proposição de um circuito integrado arbitro de "bus" multi-protocolos partindo das especificações do circuito ABC 90 e dos resultados obtidos pela primeira proposição. A validação das duas proposições sugeridas par este trabalho foi obtida através de simulações.; The existence of so many parallel communication multi-microprocessor buses (buses of the SM 90, MULTIBUS & VME structures) and their different arbiter techniques led us to study the compatibility of the integrated bus arbiter ABC 90 of the SM 90 (which presents the widest range of functions) with other types of buses MULTIBUS and VME). The first part of the study involved the feasibility of using the ABC 90 circuit as bus arbiter in different architectural configurations; this has been realized by the addition of discrete components. The second step consisted in the design of an integrated multi - protocol communication arbiter...

Artículo de publicación ISI; The interplay between congestion and crowding externalities in the design of urban bus systems is identified and analysed. A multimodal social welfare maximisation model with spatially disaggregated demand is developed, in which users choose between travelling by bus, car or walking in a transport corridor. Optimisation variables are bus fare, congestion toll, bus frequency, bus size, fare collection system, bus boarding policy and the number of seats inside buses. We find that optimal bus frequency results from a trade-off between the level of congestion inside buses, i.e., passengers’ crowding, and the level of congestion outside buses, i.e., the effect of frequency on slowing down both buses and cars in mixed-traffic roads. A numerical application shows that optimal frequency is quite sensitive to the assumptions on crowding costs, impact of buses on traffic congestion, and overall congestion level. If crowding matters to users, buses should have as many seats as possible, up to a minimum area that must be left free of seats. If for any other reason planners decide to have buses with fewer seats than optimal (e.g., to increase bus capacity), frequency should be increased to compensate for the discomfort imposed on public transport users. Finally...

Artículo de publicación ISI; This paper re-considers the problem of choosing the number of bus stops along urban routes, first by estimating the probability of stopping in low demand markets, and second by analysing the interplay between bus stop size, bus running speed, spacing and congestion in high demand markets. A comprehensive review of the theory and practice on the location and spacing of bus stops is presented. Using empirical data from Sydney, Australia, we show that the widely used Poisson model overestimates the probability of stopping in an on-call bus stopping regime, and consequently underestimates the optimal number of bus stops that should be designed. For fixed-stop services, we show that bus running speed, frequency and dwell time are crucial to determining the relationship between bus stop spacing and demand, with bus stop congestion in the form of queuing delays playing a key role. In particular, we find that bus stop spacing should be decreased if demand increases at a constant bus running speed; however, if both bus running speed and the speed of the passenger boarding process increase, then the distance between bus stops should be kept long even at high demand levels, a result that is consistent with the implementation of Bus Rapid Transit (BRT) systems that feature high bus running speeds and long distances between stops relative to conventional bus services.; This research has been supported by Busways Group...