Physical Sciences and Mathematics Commons^™

Validating And Highlighting The Advantages Of The Optimal Estimation Method For Rayleigh Lidar Middle Atmospheric Temperature Retrievals, Ali Jalali

Electronic Thesis and Dissertation Repository

An improved understanding of temperature variations in Earth’s middle atmosphere is important for the improvement of our understanding of climate and weather on the surface. The optimal estimation method (OEM) is an inversion modeling approach, which uses regularized nonlinear regression to retrieve, in this case, the temperature of Earth’s middle atmosphere using Rayleigh-scatter lidar measurements. The OEM regularization term is the a priori knowledge of the atmospheric temperature profile. In this thesis I use lidar temperatures in the altitude range 30–110km to construct a temperature climatology using over 500 nights of measurements obtained by the Purple Crow Lidar in London, …

Investigation Of Chaos In Biological Systems, Navaneeth Mohan

Electronic Thesis and Dissertation Repository

Chaos is the seemingly irregular behavior arising from a deterministic system. Chaos is observed in many real-world systems. Edward Lorenz’s seminal discovery of chaotic behavior in a weather model has prompted researchers to develop tools that distinguish chaos from non-chaotic behavior. In the first chapter of this thesis, I survey the tools for detecting chaos namely, Poincaré maps, Lyapunov exponents, surrogate data analysis, recurrence plots and correlation integral plots. In chapter two, I investigate blood pressure fluctuations for chaotic signatures. Though my analysis reveals interesting evidence in support of chaos, the utility such an analysis lies in a different direction …

Properties And Computation Of The Inverse Of The Gamma Function, Folitse Komla Amenyou

Electronic Thesis and Dissertation Repository

We explore the approximation formulas for the inverse function of Γ. The inverse function of Γ is a multivalued function and must be computed branch by branch. We compare three approximations for the principal branch Γ̌ 0 . Plots and numerical values show that the choice of the approximation depends on the domain of the arguments, specially for small arguments. We also investigate some iterative schemes and find that the Inverse Quadratic Interpolation scheme is better than Newton’s scheme for improving the initial approximation. We introduce the contours technique for extending a real-valued function into the complex plane using two …

Numerical Studies Of Electrohydrodynamic Flow Induced By Corona And Dielectric Barrier Discharges, Chaoao Shi

Electronic Thesis and Dissertation Repository

Electrohyrodynamic (EHD) flow produced by gas discharges allows the control of airflow through electrostatic forces. Various promising applications of EHD can be considered, but this requires a deeper understanding of the physical mechanisms involved.

This thesis investigates the EHD flow generated by three forms of gas discharge. First, a multiple pin-plate EHD dryer associated with the positive corona discharge is studied using a stationary model. Second, the dynamics of a dielectric barrier discharge (DBD) plasma actuator is simulated with a time-dependent solver. Third, different configurations of the extended DBD are explored to enhance the EHD flow.

The results of the …