TDMA-Based MAC (CVTMAC) in Green Vehicular Networks

The growing need to reduce the carbon footprint and the operation expenditure (OPEX) in communication networks necessitates the deployment of wind powered base stations (BSs) and roadside units (RSUs) for vehicular communication networks in windy countries with limited solar irradiation. This system finds ready application in sparse areas like countryside and motorways that lack the supply from the national grid for economic reasons. The stringent performance requirement of vehicular communication systems owed to their critical services poses challenges to their greening efforts. In this paper, we design a robust time-division multiple access (TDMA) based MAC for an infrastructure based green vehicular network in a motorway scenario and investigate the network performance against the stringent quality of service (QoS) thresholds. We call the proposed Centralised Vehicular TDMA based MAC as CVTMAC for short. To obtain a realistic performance evaluation, we model and simulate the proposed MAC protocol with the real channel characteristics of the motorway environment fully incorporated. The off grid RSU is powered solely by an economical and easy to deploy small standalone wind energy conversion systems (SSWECS). Wind energy-based rate adaptation is deployed in the RSU to enhance the efficient utilization of available energy (considering the intermittent nature of wind energy). In this study the real vehicular traffic profiles and wind data for a specified motorway region have been utilised. Both analytic and simulation results reveal that with the introduction of small battery capacity (27 Ah), the green vehicular network is able to support QoS for data, audio and video-related applications at each hour of the day in a motorway vehicular environment

Energy Efficient Nano Servers Provisioning for Information Piece Delivery in a Vehicular Environment

In this paper, we propose energy efficient Information Piece Delivery (IPD) through Nano Servers (NSs) in a vehicular network. Information pieces may contain any data that needs to be communicated to a vehicle. The available power (renewable or non-renewable) for a NS is variable. As a result, the service rate of a NS varies linearly with the available energy within a given range. Our proposed system therefore exhibits energy aware rate adaptation (RA), which uses variable transmission energy. We have also developed another transmission energy saving method for comparison, where sleep cycles (SC) are employed. Both methods are compared against an acceptable download time. To reduce the operational energy, we first optimise the locations of the NSs by developing a mixed integer linear programming (MILP) model, which takes into account the hourly variation of the traffic. The model is validated through a Genetic Algorithm (GA1). Furthermore, to reduce the gross delay over the entire vehicular network, the available renewable energy (wind farm) is optimally allocated to each NS according to piece demand. This, in turn, also reduces the network carbon footprint. A Genetic Algorithm (GA2) is also developed to validate the MILP results associated with this system. Through transmission energy savings, RA and SC further reduce the NSs energy consumption by 19% and 18% respectively, however at the expense of higher download time. MILP model 4 (with RA) and model 5 (with SC) reduced the delay by 81% and 83% respectively, while minimising the carbon footprint by 96% and 98% respectively, compared to the initial MILP model

An Open-Source Microscopic Traffic Simulator

We present the interactive Java-based open-source traffic simulator available at www.traffic-simulation.de. In contrast to most closed-source commercial simulators, the focus is on investigating fundamental issues of traffic dynamics rather than simulating specific road networks. This includes testing theories for the spatiotemporal evolution of traffic jams, comparing and testing different microscopic traffic models, modeling the effects of driving styles and traffic rules on the efficiency and stability of traffic flow, and investigating novel ITS technologies such as adaptive cruise control, inter-vehicle and vehicle-infrastructure communication

Federated Robust Embedded Systems: Concepts and Challenges

The development within the area of embedded systems (ESs) is moving rapidly, not least due to falling costs of computation and communication equipment. It is believed that increased communication opportunities will lead to the future ESs no longer being parts of isolated products, but rather parts of larger communities or federations of ESs, within which information is exchanged for the benefit of all participants. This vision is asserted by a number of interrelated research topics, such as the internet of things, cyber-physical systems, systems of systems, and multi-agent systems. In this work, the focus is primarily on ESs, with their specific real-time and safety requirements. While the vision of interconnected ESs is quite promising, it also brings great challenges to the development of future systems in an efficient, safe, and reliable way. In this work, a pre-study has been carried out in order to gain a better understanding about common concepts and challenges that naturally arise in federations of ESs. The work was organized around a series of workshops, with contributions from both academic participants and industrial partners with a strong experience in ES development. During the workshops, a portfolio of possible ES federation scenarios was collected, and a number of application examples were discussed more thoroughly on different abstraction levels, starting from screening the nature of interactions on the federation level and proceeding down to the implementation details within each ES. These discussions led to a better understanding of what can be expected in the future federated ESs. In this report, the discussed applications are summarized, together with their characteristics, challenges, and necessary solution elements, providing a ground for the future research within the area of communicating ESs

Three essays on the environment and health in cities

In my dissertation, I examine the impacts of the local urban environment on health in the developed and developing world. By 2008, more than half the global population resided in urban areas, yet many questions regarding the health impact of urban environmental factors remain unanswered. I use large, unique micro data sets on fetal health in New York City, where 8 million people reside, to observe the impacts of air pollution and extreme weather events on birth outcomes. Previous work has shown that fetal health can affect long-run outcomes, like educational attainment or income, so it is necessary to understand how exposure to various environmental factors might affect fetal health. In contrast to the U.S. where air quality regulations have been implemented since the 1960's, I also observe air pollution in Nairobi, the capital of Kenya and home to 3.1 million residents. Currently, there are no air quality regulations enforced in Kenya, nor any long-term consistent pollution monitoring, though by 2020, more than half of Kenya's population is expected to reside in urban areas. Additionally, few studies have examine urban air pollution in sub-Saharan Africa. So in another chapter, I measure occupational exposure levels of fine particulate matter (PM2.5) for individuals who work by roadways and inside informal settlements. These chapters incorporate elements from economics, public health, and atmospheric science to better understand these issues and the potential policies needed to reconcile problems of urban development and sustainability. In my first chapter, "Transit buses and fetal health: Evaluating the impacts of bus pollution policies in New York City," I provide the first estimates of the impacts of diesel vehicles on fetal health using quasi-experimental analysis. The U.S. Environmental Protection Agency (EPA) re- duced emission standards for transit buses by 98% between 1988 and 2010. I exploit the variation induced by these policy changes over time to evaluate the impacts of transit bus pollution policies on fetal health in New York City (NYC). I use bus vintage as a proxy for street-level bus emis- sions and construct a novel panel data set for the NYC Transit bus fleet that allows me to assign maternal exposure to bus pollution at the census block level. Results show a 10% reduction in emission standards for particulate matter and nitrogen oxides during pregnancy increased infant Apgar 5 scores by 0.003 points and birth weight by 6.2 grams. While the impacts on fetal health are modest, the sensitivity of later-life outcomes to prenatal conditions suggests improved emission standards between 1990 and 2009 increased total earnings for the 2009 birth cohort by at least $51 million. In my second chapter, "Occupational exposure to PM2.5 from roadways and inside informal settlements in sub-Saharan Africa: A pilot study in Nairobi, Kenya," I observe the impacts of exposure to PM2.5 for at-risk populations. Few studies examine urban air pollution in sub-Saharan Africa (SSA), yet urbanization rates there are among the highest in the world. In this study, we measure 8-hr average occupational exposure levels of fine particulate matter (PM2.5), black carbon, UV-PM, and trace elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Se, Br, and Pb) for individuals who work along roadways in Nairobi, specifically bus drivers, garage workers, and street vendors. As a comparison group we also measured exposure levels for women who reside and work inside informal settlements in Nairobi and who may also be exposed to high levels of urban air pollution. First, we find strong correlations among sources of roadside dust and vehicle exhaust across all groups. Second, we find bus drivers in Nairobi experienced 2 to 5 times the PM2.5 levels as bus or truck drivers in U.S. or European cities. Additionally, exposure levels for garage workers, street vendors, and women in Mathare were not statistically different from each other, suggesting residents in informal settlements in SSA also experience high exposure levels. These results suggest major health benefits from regulations targeting diesel exhaust emissions and roadside dust for the large portion of Nairobi residents who walk and work along roadways. We also find that improved cook stove programs could reduce PM2.5 exposure levels for informal settlement residents, particularly women. This is the first study to measure occupational exposure to urban air pollution in SSA and results from this suggest that roadway emissions are a serious concern. In my third chapter, "The relationship between temperature and fetal health in cities," I observe the impact of extreme weather events on fetal health in New York City. Climate change is projected to increase the duration, intensity and frequency of heat waves, but few studies have examined this relationship, which is of particular concern in cities where the urban heat island effect could exacerbate impacts. In this study, I combine average daily temperature from 1985-2010 with detailed birth certificate data in New York City and flexibly estimate the impact of an increase in maternal exposure to moderate and extreme temperatures. I find exposure to a day where temperature is greater than 85 degrees F is associated with a 0.37 to 1.14 g reduction in birth weight. However, I find no effect on gestational age. The effect on birth weight is modest, but using projections on how climate change might affect future heat waves, I find birth weight could reduce by 8.5 to 26.2 grams in the future, or about six times the current impact

Climate change and disaster impact reduction

Based on papers presented at the 'UK - South Asia Young Scientists and Practitioners Seminar on Climate Change and Disaster Impact Reduction' held at Kathmandu, Nepal on 5-6 June, 2008

U.S. Billion-ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry

The Report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of “potential” biomass within the contiguous United States based on numerous assumptions about current and future inventory and production capacity, availability, and technology. In the 2005 BTS, a strategic analysis was undertaken to determine if U.S. agriculture and forest resources have the capability to potentially produce at least one billion dry tons of biomass annually, in a sustainable manner—enough to displace approximately 30% of the country’s present petroleum consumption. To ensure reasonable confidence in the study results, an effort was made to use relatively conservative assumptions. However, for both agriculture and forestry, the resource potential was not restricted by price. That is, all identified biomass was potentially available, even though some potential feedstock would more than likely be too expensive to actually be economically available. In addition to updating the 2005 study, this report attempts to address a number of its shortcoming

Solar Energy: A Necessary Investment in a Developing Economy

Electrical Energy is the pivot of all developmental efforts in both the developed and the developing nations. Due to the fact that sources or conventional means of energy generation arc finite and fast depleting, most industrialized countries have started research on solar energy as a renewable sources or energy.This paper presents the present state of conventional energy generation in a developing economy like Nigeria. The efforts made in solar energy research .and utilization arc highlighted. A case is made for a systematic and coordinated financial investment in solar energy research and adaptation to complement the generation from conventional sources

Three essays on the environment and health in cities

In my dissertation, I examine the impacts of the local urban environment on health in the developed and developing world. By 2008, more than half the global population resided in urban areas, yet many questions regarding the health impact of urban environmental factors remain unanswered. I use large, unique micro data sets on fetal health in New York City, where 8 million people reside, to observe the impacts of air pollution and extreme weather events on birth outcomes. Previous work has shown that fetal health can affect long-run outcomes, like educational attainment or income, so it is necessary to understand how exposure to various environmental factors might affect fetal health. In contrast to the U.S. where air quality regulations have been implemented since the 1960's, I also observe air pollution in Nairobi, the capital of Kenya and home to 3.1 million residents. Currently, there are no air quality regulations enforced in Kenya, nor any long-term consistent pollution monitoring, though by 2020, more than half of Kenya's population is expected to reside in urban areas. Additionally, few studies have examine urban air pollution in sub-Saharan Africa. So in another chapter, I measure occupational exposure levels of fine particulate matter (PM2.5) for individuals who work by roadways and inside informal settlements. These chapters incorporate elements from economics, public health, and atmospheric science to better understand these issues and the potential policies needed to reconcile problems of urban development and sustainability. In my first chapter, "Transit buses and fetal health: Evaluating the impacts of bus pollution policies in New York City," I provide the first estimates of the impacts of diesel vehicles on fetal health using quasi-experimental analysis. The U.S. Environmental Protection Agency (EPA) re- duced emission standards for transit buses by 98% between 1988 and 2010. I exploit the variation induced by these policy changes over time to evaluate the impacts of transit bus pollution policies on fetal health in New York City (NYC). I use bus vintage as a proxy for street-level bus emis- sions and construct a novel panel data set for the NYC Transit bus fleet that allows me to assign maternal exposure to bus pollution at the census block level. Results show a 10% reduction in emission standards for particulate matter and nitrogen oxides during pregnancy increased infant Apgar 5 scores by 0.003 points and birth weight by 6.2 grams. While the impacts on fetal health are modest, the sensitivity of later-life outcomes to prenatal conditions suggests improved emission standards between 1990 and 2009 increased total earnings for the 2009 birth cohort by at least $51 million. In my second chapter, "Occupational exposure to PM2.5 from roadways and inside informal settlements in sub-Saharan Africa: A pilot study in Nairobi, Kenya," I observe the impacts of exposure to PM2.5 for at-risk populations. Few studies examine urban air pollution in sub-Saharan Africa (SSA), yet urbanization rates there are among the highest in the world. In this study, we measure 8-hr average occupational exposure levels of fine particulate matter (PM2.5), black carbon, UV-PM, and trace elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Se, Br, and Pb) for individuals who work along roadways in Nairobi, specifically bus drivers, garage workers, and street vendors. As a comparison group we also measured exposure levels for women who reside and work inside informal settlements in Nairobi and who may also be exposed to high levels of urban air pollution. First, we find strong correlations among sources of roadside dust and vehicle exhaust across all groups. Second, we find bus drivers in Nairobi experienced 2 to 5 times the PM2.5 levels as bus or truck drivers in U.S. or European cities. Additionally, exposure levels for garage workers, street vendors, and women in Mathare were not statistically different from each other, suggesting residents in informal settlements in SSA also experience high exposure levels. These results suggest major health benefits from regulations targeting diesel exhaust emissions and roadside dust for the large portion of Nairobi residents who walk and work along roadways. We also find that improved cook stove programs could reduce PM2.5 exposure levels for informal settlement residents, particularly women. This is the first study to measure occupational exposure to urban air pollution in SSA and results from this suggest that roadway emissions are a serious concern. In my third chapter, "The relationship between temperature and fetal health in cities," I observe the impact of extreme weather events on fetal health in New York City. Climate change is projected to increase the duration, intensity and frequency of heat waves, but few studies have examined this relationship, which is of particular concern in cities where the urban heat island effect could exacerbate impacts. In this study, I combine average daily temperature from 1985-2010 with detailed birth certificate data in New York City and flexibly estimate the impact of an increase in maternal exposure to moderate and extreme temperatures. I find exposure to a day where temperature is greater than 85 degrees F is associated with a 0.37 to 1.14 g reduction in birth weight. However, I find no effect on gestational age. The effect on birth weight is modest, but using projections on how climate change might affect future heat waves, I find birth weight could reduce by 8.5 to 26.2 grams in the future, or about six times the current impact