Intelligent Transportation Systems (ITS) are gaining momentum among researchers. ITS encompasses several technologies, including wireless communications, sensor networks, data and voice communication, real-time driving assistant systems, etc. These states of the art technologies are expected to pave the way for a plethora of vehicular network applications. In fact, recently we have witnessed a growing interest in Vehicular Networks from both the research community and industry. Several potential applications of Vehicular Networks are envisioned such as road safety and security, traffic monitoring and driving comfort, just to mention a few. It is critical that the existence of convenience or driving comfort services do not negatively affect the performance of safety services. In essence, the dissemination of safety services or the discovery of convenience applications requires the communication among service providers and service requesters through constrained bandwidth resources. Therefore, service discovery techniques for vehicular networks must efficiently use the available common resources. In this thesis, we focus on the design of bandwidth-efficient and scalable service discovery protocols for Vehicular Networks. Three types of service discovery architectures are introduced: infrastructure-less, infrastructure-based, and hybrid architectures. Our proposed algorithms are network layer based where service discovery messages are integrated into the routing messages for a lightweight discovery. Moreover, our protocols use the channel diversity for efficient service discovery. We describe our algorithms and discuss their implementation. Finally, we present the main results of the extensive set of simulation experiments that have been used in order to evaluate their performance.

The combination of infrastructure-to-vehicle and vehicle-to-vehicle communications, namely the multi-hop Vehicular Communications Network (VCN) , appears as a promising solution for the ubiquitous access to IP services in vehicular environments. In this thesis, we address the challenges of multi-hop VCN, and investigate the seamless provision of IP services over such network. Three different schemes are proposed and analyzed. First, we study the limitations of current standards for the provision of IP services, such as 802.11p/WAVE, and propose a framework that enables multi-hop communications and a robust IP mobility mechanism over WAVE. An accurate analytical model is developed to evaluate the throughput performance, and to determine the feasibility of the deployment of IP-based services in 802.11p/WAVE networks. Next, the IP mobility support is extended to asymmetric multi-hop VCN. The proposed IP mobility and routing mechanisms react to the asymmetric links, and also employ geographic location and road traffic information to enable predictive handovers. Moreover, since multi-hop communications suffer from security threats, it ensures that all mobility signalling is authenticated among the participant vehicles. Last, we extend our study to a heterogeneous multi-hop VCN, and propose a hybrid scheme that allows for the on-going IP sessions to be transferred along the heterogeneous communications system. The proposed global IP mobility scheme focuses on urban vehicular scenarios, and enables seamless communications for in-vehicle networks, commuters, and pedestrians. The overall performance of IP applications over multi-hop VCN are improved substantially by the proposed schemes. This is demonstrated by means of analytical evaluations, as well as extensive simulations that are carried out in realistic highway and urban vehicular scenarios. More importantly, we believe that our dissertation provides useful analytical tools, for evaluating the throughput and delay performance of IP applications in multi-hop vehicular environments. In addition, we provide a set of practical and efficient solutions for the seamless support of IP tra c along the heterogeneous and multi-hop vehicular network, which will help on achieving ubiquitous drive-thru Internet, and infotainment traffic access in both urban and highway scenarios.

By equipping vehicles with the on-board wireless facility, the newly emerged vehicular networking targets to provision the broadband serves to vehicles. As such, a variety of novel and exciting applications can be provided to vehicular users to enhance their road safety and travel comfort, and finally raise a complete change to their on-road life. As the content distribution and media/video streaming, such as Youtube, Netflix, nowadays have become the most popular Internet applications, to enable the efficient content distribution and audio/video streaming services is thus of the paramount importance to the success of the vehicular networking. This, however, is fraught with fundamental challenges due to the distinguished natures of vehicular networking. On one hand, the vehicular communication is challenged by the spotty and volatile wireless connections caused by the high mobility of vehicles. This makes the download performance of connections very unstable and dramatically change over time, which directly threats to the on-top media applications. On the other hand, a vehicular network typically involves an extremely large-scale node population (e.g., hundreds or thousandths of vehicles in a region) with intense spatial and temporal variations across the network geometry at different times. This dictates any designs to be scalable and fully distributed which should not only be resilient to the network dynamics, but also provide the guaranteed quality-of-service (QoS) to users. The purpose of this dissertation is to address the challenges of the vehicular networking imposed by its intrinsic dynamic and large-scale natures, and build the efficient, scalable and, more importantly, practical systems to enable the cost-effective and QoS guaranteed content distribution and media streaming services to vehicular users. Note that to effective- ly deliver the content from the remote Internet to in-motion vehicles, it typically involves three parts as: 1.) an infrastructure grid of gateways which behave as the data depots or injection points of Internet contents and services to vehicles, 2.) protocol at gateways which schedules the bandwidth resource at gateways and coordinates the parallel transmissions to different vehicles, and 3.) the end-system control mechanism at receivers which adapts the receiver’s content download/playback strategy based on the available network throughput to provide users with the desired service experience. With above three parts in mind, the entire research work in this dissertation casts a systematic view to address each part in one topic with: 1.) design of large-scale cost-effective content distribution infrastructure, 2.) MAC (media access control) performance evaluation and channel time scheduling, and 3.) receiver adaptation and adaptive playout in dynamic download environment. In specific, in the first topic, we propose a practical solution to form a large-scale and cost-effective content distribution infrastructure in the city. We argue that a large-scale infrastructure with the dedicated resources, including storage, computing and communication capacity, is necessary for the vehicular network to become an alternative of 3G/4G cellular network as the dominating approach of ubiquitous content distribution and data services to vehicles. On addressing this issue, we propose a fully distributed scheme to form a large-scale infrastructure by the contributions of individual entities in the city, such as grocery stores, movie theaters, etc. That is to say, the installation and maintenance costs are shared by many individuals. In this topic, we explain the design rationale on how to motivate individuals to contribute, and specify the detailed design of the system, which is embodied with distributed protocols and performance evaluation. The second topic investigates on the MAC throughput performance of the vehicle-to- infrastructure (V2I) communications when vehicles drive through RSUs, namely drive-thru Internet. Note that with a large-scale population of fast-motion nodes contending the chan- nel for transmissions, the MAC performance determines the achievable nodal throughput and is crucial to the on-top applications. In this topic, using a simple yet accurate Marko- vian model, we first show the impacts of mobility (characterized by node velocity and moving directions) on the nodal and system throughput performance, respectively. Based on this analysis, we then propose three enhancement schemes to timely adjust the MAC parameters in tune with the vehicle mobility to achieve the maximal the system throughput. The last topic investigates on the end-system design to deliver the user desired media streaming services in the vehicular environment. In specific, the vehicular communications are notoriously known for the intermittent connectivity and dramatically varying throughput. Video streaming on top of vehicular networks therefore inevitably suffers from the severe network dynamics, resulting in the frequent jerkiness or even freezing video playback. To address this issue, an analytical model is first developed to unveil the impacts of network dynamics on the resultant video performance to users in terms of video start-up delay and smoothness of playback. Based on the analysis, the adaptive playout buffer mechanism is developed to adapt the video playback strategy at receivers towards the user-defined video quality. The proposals developed in the three topics are validated with the extensive and high fidelity simulations. We believe that our analysis developed in the dissertation can provide insightful lights on understanding the fundamental performance of the vehicular content distribution networks from the aspects of session-level download performance in urban vehicular networks (topic 1), MAC throughput performance (topic 2), and user perceived media quality (topic 3). The protocols developed in the three topics, respectively, offer practical and efficient solutions to build and optimize the vehicular content distribution networks.

This dissertation contains two essays on the analysis of market imperfections. In the first essay, I empirically test whether in a three-level hierarchy with asymmetries of information, more competition among intermediaries leads to more deception against the principal. In this setting, intermediaries supervise agents by delegation of the principal, and compete among themselves to provide supervision services to the agents. They cannot be perfectly monitored, therefore allowing them to manipulate supervision results in favor of the agents, and potentially leading to less than optimal outcomes for the principal. Using inspection-level data from the vehicular inspection program in Atlanta, I test for the existence of inspection deception (false positives), and whether this incidence is a function of the number of local competitors by station. I estimate the incidence of the most common form of false positives (clean piping) to be 9% of the passing inspections during the sample period. Moreover, the incidence of clean piping -- passing results of a different vehicle fraudulently applied to a failing vehicle -- per station increases by 0.7% with one more competitor within a 0.5 mile radius. These results are consistent with the presence of more competitors exacerbating the perverse incentives introduced by competition under this setting. In the second essay, we test whether electricity consumption by industrial and commercial customers responds to real-time prices after these firms sign-up for prices linked to the electricity wholesale market price. In principle, time-varying prices (TVP) can mitigate market power in wholesale markets and promote the integration of intermittent generation sources such as wind and solar power. However, little is known about the prevalence of TVP, especially in deregulated retail markets where customers can choose whether to adopt TVP, and how these firms change their consumption after signing up for this type of tariff. We study firm-level data on commercial and industrial customers in Texas, and estimate the magnitude of demand responsiveness using demand equations that consider the restrictions imposed by the microeconomic theory. We find a meaningful level of take-up of TVP ? in some sectors more than one-quarter of customers signed up for TVP. Nevertheless, the estimated price responsiveness of consumption is still small. Estimations by size and by type of industry show that own price elasticities are in most cases below 0.01 in absolute value. In the only cases that own price elasticities reach 0.02 in absolute value, the magnitude of demand response compared to the aggregate demand is negligible.

Thesis (M. S. in Computer Science)--Vanderbilt University, May 2009. / Title from title screen. Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Keith W. Goossen, Dept. of Electrical & Computer Engineering. Includes bibliographical references.

Thesis (M.S.)--Michigan State University. Dept. of Electrical and Computer Engineering, 2008. / Title from PDF t.p. (viewed on Aug. 6, 2009) Includes bibliographical references (p. 136-138). Also issued in print.

Os hidrocarbonetos policíclicos aromáticos (HPA) são amplamente estudados na área de meio ambiente, em diversas matrizes ambientais como ar, água, solo e sedimento, devido a sua toxicidade, potencial mutagênico e carcinogênico. Por conta disto, as agências ambientais de países desenvolvidos listaram dezesseis HPA como sendo poluentes prioritários. As legislações a nível mundial não estipulam limites para estes compostos para ar ambiente, somente para emissões de fontes fixas e móveis e ambientes ocupacionais, mas existem diversos estudos, mais especificamente para os 16 prioritários HPA e muito pouco para os homólogos alquilados. Os HPA alquilados são mais abundantes, persistentes e frequentemente mais tóxicos que os não alquilados e a toxicidade aumenta com o número de substituições alquil sobre os núcleos aromáticos. As legislações ambientais em todo o mundo não realizam o controle em nenhuma matriz ambiental para os HPA alquilados. Neste trabalho foi desenvolvido um método para análise dos HPA e seus homólogos alquilados, utilizando cromatografia de fase gasosa acoplado a um detector de espectrometria de massa e com um sistema de injeção para grande volume, associado à vaporização com temperatura programada, que permitiu um nível de detecção na faixa de 0,70 até 103,6 ng mL-1, sendo possível analisar as amostras de material particulado oriundas de emissões veiculares. As amostras foram coletadas de acordo com a Norma ABNT NBR14489, em um dinamômetro de bancada para motor do ciclo diesel (Ciclo de 13 pontos). Os resultados encontrados foram na faixa de 0,5 ng mL-1 até 96,9 ng mL-1 Os resultados indicaram que motores a diesel/ biodiesel têm uma contribuição muito grande na formação destes HPA e homólogos alquilados

Orientador: Gustavo Luiz Chagas Manhães de Abreu / Resumo: Fluidos magnetoreológicos (MR) são fluidos capazes de alterar suas propriedadesreológicas quando um campo magnético é aplicado sobre ele. Uma das aplicações maisimportantes do fluido MR é em amortecedores de vibrações, utilizados principalmente naconstrução civil, veículos automotivos e outros sistemas mecânicos sujeitos a excitaçõesque provocam vibrações indesejáveis. Na indústria automobilística, atualmente atecnologia dos amortecedores que utilizam fluido MR vem se destacando como umasolução que pode trazer benefícios de conforto e segurança aos usuários de veículos emgeral. Este trabalho discute a modelagem não-linear de um veículo que considera adinâmica vertical, lateral e longitudinal, simulado em diferentes condições de conduçãoque buscam avaliar o conforto, a aderência à estrada, a dirigibilidade, a rolagem e adeflexão da suspensão. Pretende, também, contribuir com a área de controle de vibraçõesem suspensões veiculares que utilizam amortecedores MR, avaliando o desempenho doscontroladores ótimo (LQR), nebuloso e FEB (Frequency-Estimation-Based ) projetadosem 1/4 de veículo e aplicados ao modelo não-linear do veículo. O trabalho terminacomentando as potencialidades da metodologia apresentada, discutindo as facilidadese dificuldades encontradas na sua implementação e aponta propostas para a suacontinuidade. / Doutor

As emissões de poluentes atmosféricos decorrentes de veículos automotores representam um grave problema ambiental. O modo de operação do veículo influencia diretamente a quantidade de poluentes emitidos. Quando um veículo inicia sua operação com motor frio, efeito denominado de partida a frio, a quantidade de poluentes emitidos torna-se consideravelmente maior em comparação às condições estabilizadas de temperatura do motor. O efeito da partida a frio é bastante representativo em viagens de curta duração, como é o caso dos deslocamentos urbanos. Este estudo propõe um método para a determinação e distribuição espacial do adicional de emissões de poluentes em partida a frio. Este método foi aplicado em Porto Alegre, utilizando informações de tráfego e da frota local coletados na pesquisa de entrevistas domiciliares, realizada no ano de 2003. Os fatores de emissão utilizados embasaram-se em um estudo realizado com veículos brasileiros. Os resultados da aplicação do método indicaram que a maior parte das partidas a frio ocorre na região central de Porto Alegre e suas adjacências, sendo maior no período matinal. Observou-se também que os maiores responsáveis pelo adicional por partida a frio são os veículos equipados com conversores catalíticos e injeção eletrônica de combustível. Entretanto, os veículos mais antigos, sem conversor catalítico e equipados com carburador, são os maiores responsáveis pela emissão total, adicional por partida a frio e emissão estabilizada de CO e HC nos períodos analisados. Através do método proposto neste estudo foi possível identificar áreas críticas que necessitam de ações de controle de emissões em partida a frio. Os resultados deste estudo podem subsidiar o planejamento e gerenciamento das condições ambientais provocadas pelas emissões veiculares em áreas urbanas. / Atmospheric pollution from vehicle emissions is a serious environmental problem. The vehicle operation mode influences directly in the amount of emitted pollutants. When a vehicle begins its operation with the cold engine, called as cold start effect, the amount of emitted pollutant becomes considerably higher than when in stabilized conditions of engine’s temperature. Cold start effect are very representative in short travels, such as urban trips. This study proposes a method to estimate the amount and spacial distribution of the additional cold start pollutant emissions. This method was applied to Porto Alegre, Brazil, using traffic and local fleet data from a household travel survey of 2003. Emissions factors were based on a study of Brazilian fleet. The results from the method application showed that cold start emissions in Porto Alegre are higher in the morning peak and most of the cold start emissions are concentrated in the town center and its adjacencies. The results also showed that the catalyst fuel injection vehicles are the main responsible for the additional cold start emissions. However, old vehicles, without catalyst and equipped with carburetor, are the main responsible for the total, cold start and running emissions, CO and HC emissions in both analyses periods. Through the proposed method, it was possible to identify critical areas that need control actions of cold start emissions. The results from this study can assist planning and management of the environmental conditions deriving from vehicular emissions in urban areas.