An Sn Application of Homotopy Continuation in Neutral Particle Transport

The objective of this dissertation is to investigate the usefulness of homotopy continuation applied in the context of neutral particle transport where traditional methods of acceleration degrade. This occurs in higher dimensional heterogeneous problems [51]. We focus on utilizing homotopy continuation as a means of providing a better initial guess for difficult problems. We investigate various homotopy formulations for two primary diffcult problems: a thick-diffusive fixed internal source, and a k-eigenvalue problem with high dominance ratio. We also investigate the usefulness of homotopy continuation for computationally intensive problems with 30-energy groups. We find that homotopy continuation exhibits usefulness in specific problem formulations. In the thick-diffusive problem it shows benefit when there is a strong internal source in thin materials. In the k-eigenvalue problem, homotopy continuation provides an improvement in convergence speed for fixed point iteration methods in high dominance ratio problems. We also show that one of our imbeddings successfully stabilizes the nonlinear formulation of the k-eigenvalue problem with a high dominance ratio

Guidance, flight mechanics and trajectory optimization. Volume 6 - The N-body problem and special perturbation techniques

Analytical formulations and numerical integration methods for many body problem and special perturbative technique

Advanced flight control system study

The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed

The health effects of automobile fuel economy through improvements in air quality

In this dissertation, I evaluate the health effects of the automobile (or vehicle) fuel economy. Automobile fuel economy is regulated by the Corporate Average Fuel Economy (CAFE) standards put into effect in 1975 in the United States primarily to reduce the oil consumption and dependency on oil import in response to the Oil Embargo in the 1970s. The health benefit was not thoroughly analyzed in policy analyses of CAFE standards. I hypothesize that better automobile fuel economy results in less mobile source air pollutants such as fine Particulate Matters (PM2.5), Carbon Monoxide (CO), and Nitrogen Dioxide (NO2), and hence improves air quality, which in turn reduces air pollutant related diseases such as asthma. Thus, CAFE standards have health benefits because CAFE standards increase the on-road vehicle fleet fuel economy. I seek empirical evidence of the health effects of automobile fuel economy through the improvement of air quality. Using vehicle registration and fuel consumption data, air pollutant data, health survey data, and other relevant data in the United States, I apply statistical mediation analysis techniques to assess the variation of asthma with respect to the changes of automobile fuel economy over time through the air pollutants mechanism. The empirical analysis results, under certain assumptions and with some limitation due to the data, support my key hypotheses: 1) there is a clear negative correlation between the automobile fuel economy and mobile source air pollutants over time; 2) there is a negative correlation between the fuel economy and asthma prevalence through the air pollutants mechanism; 3) empirical evidence supports that the air pollutants are the mediators through which automobile fuel economy affects health. This dissertation provides the empirical evidence of the health effects of automobile fuel economy improvement through improvements in air quality. It contributes to the literature and knowledge to the research community in two aspects: first, by identifying the health benefits of automobile fuel economy and an additional support to tighten the automobile fuel economy standards; second, by applying statistical mediation methods in econometric analysis