A novel trajectory and attitude control and navigation analysis tool for powered ascent is developed. The tool is capable of rapid trade-space analysis and is designed to ultimately reduce turnaround time for launch vehicle design, mission planning, and redesign work. It is streamlined to quickly determine trajectory and attitude control dispersions, propellant dispersions, orbit insertion dispersions, and navigation errors and their sensitivities to sensor errors, actuator execution uncertainties, and random disturbances. The tool is developed by applying both Monte Carlo and linear covariance analysis techniques to a closed-loop, launch vehicle guidance, navigation, and control (GN&C) system. The nonlinear dynamics and flight GN&C software models of a closed-loop, six-degree-of-freedom (6-DOF), Monte Carlo simulation are formulated and developed. The nominal reference trajectory (NRT) for the proposed lunar ascent trajectory is defined and generated. The Monte Carlo truth models and GN&C algorithms are linearized about the NRT, the linear covariance equations are formulated, and the linear covariance simulation is developed. The performance of the launch vehicle GN&C system is evaluated using both Monte Carlo and linear covariance techniques and their trajectory and attitude control dispersion, propellant dispersion, orbit insertion dispersion, and navigation error results are validated and compared. Statistical results from linear covariance analysis are generally within 10% of Monte Carlo results, and in most cases the differences are less than 5%. This is an excellent result given the many complex nonlinearities that are embedded in the ascent GN&C problem. Moreover, the real value of this tool lies in its speed, where the linear covariance simulation is 1036.62 times faster than the Monte Carlo simulation. Although the application and results presented are for a lunar, single-stage-to-orbit (SSTO), ascent vehicle, the tools, techniques, and mathematical formulations that are discussed are applicable to ascent on Earth or other planets as well as other rocket-powered systems such as sounding rockets and ballistic missiles.

Thesis (Elec.E. and S.M. in Electrical Engineering)--Joint Program in Applied Ocean Physics and Engineering (Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; and the Woods Hole Oceanographic Institution), 2003. / "February 2003." / Includes bibliographical references (leaves 139-141). / by Andrea L. Kraay. / Elec.E.and S.M.in Electrical Engineering

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While variation analysis methods for compliant assemblies are not new, little has been done to include the effects of multi-step, fixtured assembly processes. This thesis introduces a new method to statistically analyze compliant part assembly processes using fixtures. This method, consistent with the FASTA method developed at BYU, yields both a mean and a variant solution. The method, called Piecewise-Linear Elastic Analysis, or PLEA, is developed for predicting the residual stress, deformation and springback variation in compliant assemblies. A comprehensive, step-by-step analysis map is provided. PLEA is validated on a simple, laboratory assembly and a more complex, production assembly. Significant modeling findings are reported as well as the comparison of the analytical to physical results.

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<p>Hypercholesterolemia is the presence of high levels of cholesterol in the blood, and it is one of the major factors for the development of long-term complications in T1D patients.</p> <p>In the thesis, we studied 1303 Caucasians with type 1 diabetes in the Diabetes Control and Complications Trial (DCCT). With the experience of diabetes study, many factors are associated with diabetes complications, they are age, gender, cohort, treatment, diabetes duration, body mass index (BMI), exercise, insulin dose, etc. We mainly focus on which factors are associated with total cholesterol (CHL) analysis in the thesis.</p> <p>Many measures were collected monthly, quarterly or yearly for average 6.5 years from 1983 to 1993. We used annually lipid measures of DCCT because of their values are sufficient and complete, and they belong to longitudinal data.</p> <p>Different methods are discussed in the study, and linear mixed effect models are the appropriate approach to the study. The details of model selection with CHL model analysis are shown, which includes fixed effect selection, random effects selection, and residual correlation structure selection. Then the SNPs were added on three models individually in GWAS. We found locus (rs7412) is not only genome-wide associated with CHL, but also genome-wide associated with LDL.</p> <p>We will assess whether these SNPs are diabetes-specific in the future, and we will add dietary data in the three models to identify locus are associated with the interaction of diet and SNPs.</p> / Master of Science (MSc)

<p><h1>This study discusses energy and water balance in an 80-year-old deciduous Carolinian forest in the Great Lakes region in southern Ontario, Canada. The eddy covariance technique and associated meteorological and soil variables were used to make a year-round measurements of energy and water vapour fluxes from January-December,2012. This site is part of the Turkey Point Flux Station and global Fluxnet. The linear relationship between daily turbulent (sensible heat (H), latent heat (LE)) and radiative fluxes (net radiation (Rn),soil heat (G) and canopy heat storage ( S)) has a the slope of 0.75 (intercept of -15.8 Wm^-2, and a correlation coefficient, r² of 0.93) indicating a 25% deficiency in energy balance closure. The mean value of canopy albedo was 0.16 during the growing season. Maximum daily evapotranspiration (E) rate was 3.8 mm day^-1 in June, when growing is at its peak in the region. Total annual E was 400 mm, which accounted for 42% of the total annual precipitation of 950 mm. The water storage in upper soil column (1.0 m depth) was approximately 100 mm, indicating that about 450 mm of water was lost from the forest as runoff. Apart from radiation, vapour pressure deficit (D) was the dominant control on E. Maximum value of bulk surface conductance (Gs) was about 18.5 mm s^-1. Gs linearly decreased in response to increase in D. The minimum Gs values were recorded when D was maximum, i.e. 3 to 3.5 kPa. Gs also showed high sensitivity to the volumetric soil water content (ϴ), during dry periods, for example the drought event in 2012. In the growing season, the typical value of Priestley-Taylor α ranged between 0.8 to 1.2 with a maximum of 1.8, indicating a wet deciduous forest. However, the LE/Rn relationship showed a linear increase with increasing D with a low (0.26) slope, indicating a conservative response of forest E to atmospheric demand. This study provides insight into energy partitioning, the water balance and their controls in this Carolinian deciduous forest. A better understanding of evapotranspiration processes and their controls in these forests would help to better quantify water availability at local and regional scales and to evaluate the impacts of future climate change on water resources in the region.</h1></p> / Master of Science (MSc)

<p>Continuous measurements of carbon fluxes and meteorological variables were made at a newly initiated flux tower site at an oak-dominant temperate deciduous forest in Southern Ontario, Canada from January to December 2012. Results indicate this forest was a moderate carbon sink in 2012. Annual values of net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (R) were 263 ± 30, 1192 and 922 g C m^-2, respectively. An unusual warm period in March caused a strong increase in R. Erratic peaks of daily air temperature in April also increased R. A drought in July and early August reduced NEP rates when soil moisture values reached the lowest point of the year in late July and early August (minimum 0.023 m³ m^-3). This decrease in NEP was mostly caused by a decrease in GEP, rather than increased R. Water use efficiency at this deciduous forest was 2.86 g C kg^-1 H₂O, indicating conservative water use by the forest. Downwelling photosynthetic active radiation (PAR) was a dominant environmental control on photosynthesis, followed by air temperature and vapour pressure deficit, except in extreme dry periods when soil water stress affected carbon uptake. Extremely cloudy days in the growing season resulted in net carbon release due to low photosynthetic uptake values. Results indicate that large climatic fluctuations in this region may cause high instability in photosynthetic carbon uptake and release from soil carbon pools. This study helps to evaluate and quantify the responses of deciduous forests in the Great Lakes region to future climate change and extreme weather events.</p> / Master of Science (MSc)