<p> This dissertation describes three related studies regarding the imbalance difference theory in modeling the conversion between differential mode and common mode/antenna mode signals. The topics covered are: rigorous derivation of imbalance difference theory for modeling radiated emission problems, modeling the conversion between differential mode and common mode propagation in transmission lines, and modeling the loading impedance on differential mode signals due to radiated emissions. </p><p> The imbalance difference theory describes a method for calculating the coupling between differential mode signals and common mode signals due to changes in electrical balance on a transmission line. It provides both physical insight and a simple technique for modeling the conversions between the two modes. </p><p> The first chapter presents a rigorous derivation of imbalance difference theory for modeling radiated emission problems. Although the theory has been successfully used to model a wide variety of important EMC problems over the past, it has not been rigorously derived. The derivation carefully defines the important quantities and demonstrates that imbalance difference calculations are exact provided that the differential-mode propagation is TEM and the current division factor, h, represents the actual ratio of currents on the two transmission line conductors excited by a common-mode source. This chapter also discusses the acquisition of the current division factor from 2D calculations of the cross-section of the transmission line. </p><p> The second chapter provides a rigorous development of the imbalance difference theory for three-conductor transmission lines where both the differential mode and common mode exhibit TEM propagation. It also derives expressions for the mode conversion impedances, which account for the energy converted from one mode to the other. They are essential for modeling the conversion between the two modes when they are strongly coupled. </p><p> The third chapter introduces conversion impedance to the existing imbalance difference theory model for modeling radiated emission problems, so that when the coupling between differential mode and antenna mode are strong, the imbalance difference theory can more accurately estimate the antenna mode current. </p><p> All three papers are about confirming, enriching and expanding the imbalance difference theory. The first chapter focuses on the rigorous derivation of theory for its most common application, radiated emission problems. The second chapter expands the theory to multi-conductor transmission line structure when the two modes are strongly coupled. The last chapter introduces conversion impedance to the theory in modeling radiated emission problems and improves the accuracy of the model at resonant frequencies. </p>

This work is concerned with the development of a new quantitative kinetic model for the analysis of hydrocarbon fuel droplet heating and evaporation, suitable for practical engineering applications. The work mainly focuses on the following two areas. Firstly, a new molecular dynamics (MD) algorithm for the simulation of complex hydrocarbon molecules, with emphasis on the evaporation/condensation process of liquid n-dodecane (C12H26), which is used as an approximation for Diesel fuel, has been developed. The analysis of n-dodecane molecules has been reduced to the analysis of simplified molecules, consisting of pseudoatoms, each representing the methyl (CH3) or methylene (CH2) groups. This analysis allows us to understand the underlying physics of the evaporation/condensation process of n-dodecane molecules and to estimate the values of its evaporation/condensation coefficients for a wide range of temperatures related to Diesel engines. Nobody, to the best of our knowledge, has considered MD simulation of molecules at this level of complexity. Secondly, a new numerical algorithm for the solution of the Boltzmann equation, taking into account inelastic collisions between complex molecules, has been developed. In this algorithm, additional dimensions referring to inelastic collisions have been taken into account alongside three dimensions describing the translational motion of molecules as a whole. The conservation of the total energy before and after collisions has been considered. A discrete number of combinations of the values of energy corresponding to translational and internal motions of molecules after collisions have been allowed and the probabilities of the realisation of these combinations have been assumed to be equal. This kinetic model, with the values of the evaporation coefficient estimated based on MD simulations, has been applied to the modelling of the heating and evaporation processes of n-dodecane droplets in Diesel engine-like conditions. In the previously developed kinetic models, applied to this modelling, all collisions were assumed to be elastic and the evaporation coefficient was assumed equal to 1. It is shown that the effects of inelastic collisions lead to stronger increase in the predicted droplet evaporation time relative to the hydrodynamic model, compared with the similar increase predicted by the kinetic model considering only elastic collisions. The effects of a non-unity evaporation coefficient are shown to be weak at gas temperatures around or less than 1,000 K but noticeable for gas temperatures 1,500 K. The application of the rigorous kinetic model, taking into account the effects of inelastic collisions and a non-unity evaporation coefficient, and the model considering the temperature gradient inside droplets is recommended when accurate predictions of the values of droplet surface temperature and evaporation time in Diesel engine-like conditions are essential.

Nowadays, the European automotive market is dominated by Diesel engines. Despite their high efficiency, these produce significant levels of pollutants. Among the various pollutants released, nitrogen oxides and soot are the main issues. Their formation is linked to the combustion process and attempts to reduce one often lead to an increase of the other. Laser diagnostics are among the best tools for experimental, non-intrusive studies inside combustion chambers for a better understanding of the complex combustion processes. Depending on the optical diagnostic, numerous combustion characteristics and processes can be investigated. The work presented here intends initially to develop a quantitative laser technique for characterising soot and, secondly, to further the knowledge on soot formation in Diesel engines by the application of this technique in an optical combustion chamber. Some of the main characteristics describing soot formation are the soot volume fraction, number density and particle sizes. Soot volume fraction is the major one as it is representative of the volume of soot produced. Planar characterisation of soot volume fraction, number density and particle size were achieved for the first time by simultaneous recording laser-induced incandescence (LII), laser scattering and two-colour time-resolved (2C-TiRe) LII signals. Qualitative planar distributions of particle diameter and soot volume fraction were derived from the image ratio of scattering and incandescence signals. 2C- TiRe LII technique allowed the simultaneous recording of the temporal LII signal for two different wavelengths in order to obtain quantitative values of the laser-heated particles temperature, soot volume fraction and particle size for a local or global part of the flame. These were used to recalibrate relative size and soot volume distributions. An initial development of the technique was performed on a laminar diffusion flame (Santoro burner) to validate its viability and performance. Equivalent temperature, soot volume fraction and particle diameter were determined throughout the flame. The results were found to be in good agreement with the ones published in the literature. The diagnostic was subsequently applied to an optical Diesel rapid compression machine, and further refinements were undertaken to cope with the higher soot concentration and lower LII signal. Tests were conducted for in-cylinder pressures ranging from 4 to 10 MPa, and injection pressures up to 160 MPa. A fixed injection timing and injected fuel quantity were used. Effects of in-cylinder pressure, fuel injection pressure and cetane number on soot formation and characteristics were observed. High injection pressure, cetane number and in-cylinder pressure caused a reduction of soot particle size and volume fraction but an increase of the soot particle density.

Vetronics in modern day military vehicles have evolved to include network enabled capability (NEC) allowing the use of electronics architectures to integrate different sub-systems. Integrated vehicle electronics (vetronics) offer improved performance, efficiency and new capabilities at the sub-system, system and system-of-systems level. However, this integration is associated with magnified risk and compromise from cyber-attacks. Potential cyber-attacks could be from an external source where a node is accessed by a malicious intruder using NEC, or internal to the vehicle such as a passive attack waiting to be triggered by an event. The aim of this work is to provide an understanding of applying survivable systems principles of preventive and reactive mechanisms, and proposes a vetronics survivability framework for the vehicle’s integrated vetronics in order to mitigate internal and external threats.

abstract: For autonomous vehicles, intelligent autonomous intersection management will be required for safe and efficient operation. In order to achieve safe operation despite uncertainties in vehicle trajectory, intersection management techniques must consider a safety buffer around the vehicles. For truly safe operation, an extra buffer space should be added to account for the network and computational delay caused by communication with the Intersection Manager (IM). However, modeling the worst-case computation and network delay as additional buffer around the vehicle degrades the throughput of the intersection. To avoid this problem, AIM, a popular state-of-the-art IM, adopts a query-based approach in which the vehicle requests to enter at a certain arrival time dictated by its current velocity and distance to the intersection, and the IM replies yes/no. Although this solution does not degrade the position uncertainty, it ultimately results in poor intersection throughput. We present Crossroads, a time-sensitive programming method to program the interface of a vehicle and the IM. Without requiring additional buffer to account for the effect of network and computational delay, Crossroads enables efficient intersection management. Test results on a 1/10 scale model of intersection using TRAXXAS RC cars demonstrates that our Crossroads approach obviates the need for large buffers to accommodate for the network and computation delay, and can reduce the average wait time for the vehicles at a single-lane intersection by 24%. To compare Crossroads with previous approaches, we perform extensive Matlab simulations, and find that Crossroads achieves on average 1.62X higher throughput than a simple VT-IM with extra safety buffer, and 1.36X better than AIM. / Dissertation/Thesis / Masters Thesis Engineering 2017

O presente trabalho destina-se a resumir o processo de desenvolvimento de automóveis, mostrando os vários itens que influenciam na velocidade deste desenvolvimento, e propor uma base de raciocínio para se diminuir o tempo total para o projeto. / The present volume is destined to summarize the development process of automobiles, showing the many items responsible for speed up this development, and make a proposal for a thinking basis to shorten development time.

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Electric vehicles are the main technology currently being pursued to reduce dependence on fossil fuels in the transportation sector. These vehicles provide both reduced greenhouse gas emissions and decreased operating costs when compared to conventional internal combustion vehicles, while providing the flexibility to use both renewable and fossil energy. However, these vehicles have seen limited consumer adoption due to their large purchase prices and limited driving range. Both purchase price and driving range are related to the large onboard battery systems required for electric vehicle travel. One solution to decrease dependence on large battery systems has focused on charging vehicles in-motion using wireless power transfer. In-motion charging of electric vehicles would allow for longer range travel with smaller onboard battery systems which would lead to cheaper vehicles and, in turn, greater consumer acceptance. Wireless power transfer is commonly used for small electronics (i.e. cell phones), but has seen limited use on large scale projects. Therefore, limited work has been done to understand the feasibility of in-motion charging of electric vehicles using wireless power transfer. The goal of this thesis is to better understand the economic feasibility, environmental benefit, and infrastructure requirements of a wirelessly charged electric vehicle fleet for transportation in the United States.

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