Physics Commons^™

Ab-Initio And Empirical Simulations Of Aluminum And Copper Metal, William Wolfs

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, I perform detailed calculations on the bulk and electronic properties of aluminum and copper metal. Originally, I was motivated by experimental work on the solidsolid phase changes in pure aluminum. These phase changes were well predicted by density functional theory(DFT) but difficult or impossible to predict using embedded atom method potentials(EAM). EAM potentials are in wide use to describe many properties of bulk materials, and it seemed worrying that something so basic as a phase change could not be predicted. I began running high precision calculations with DFT and compared the results to EAM potentials which had …

Numerical Studies Of Regularized Navier-Stokes Equations And An Application Of A Run-To-Run Control Model For Membrane Filtration At A Large Urban Water Treatment Facility, Jeffrey Belding

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation consists of two parts. The first part consists of research on accurate and efficient turbulent fluid flow modeling via a family of regularizations of the Navier-Stokes equation which are known as Time Relaxation models. In the second part, we look into the modeling application for the filtration/backwash process at the River Mountains Water Treatment Facility in Henderson, NV.

In the first two chapters, we introduce the Time Relaxation models and their associated differential filter equations. In addition, we develop the regularization method which employs the Nth van Cittert deconvolution operator, which gives rise to the family of models. …

Hyperpolarizability Dispersion Measured For Carbon Disulfide Vapor, Rodrigo N. Fernandez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The second hyperpolarizability (γ) of carbon disulfide (CS2) was measured by gas phase electric-field-induced second harmonic generation (ESHG), for laser wavelengths in the range of 765-1064 nm. The observed hyperpolarizability is decomposed into electronic (γ^e) and vibrational (γ^v) contributions, and the dispersion curve for γ^eis extrapolated to the static limit, with the result γ^e_0 = 12558 ± 93 atomic units. The results of this experiment agree with other recent nonlinear optical measurements and theoretical calculations.

Plasma Aerodynamics: Experimental Quantification Of The Lift Force Generated On An Airfoil Using Plasma Actuation To Estimate Power Requirements In Small Uav Applications, Getachew Ashenafi

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research addressed the amount of electric power required to induce specific changes in lift force using a NACA 2127 airfoil with a chord length of ~28 mm, connected to a micro load cell, in a wind tunnel of 103 square centimeter cross-section. A DBD plasma actuator supplied by a ZVS driven high voltage pulsed DC circuit, operating at a frequency of 17.4 kHz, was utilized for voltages of up to 5000 V. Two configurations of electrode gapping were compared to determine the efficient use of power. The configuration with a gap of ~1 mm between the upstream and downstream …

Accretion And Debris Disc Dynamics Around Single And Higher-Order Star Systems, Jeremy L. Smallwood

UNLV Theses, Dissertations, Professional Papers, and Capstones

My research deals with highly topical areas of astrophysics, such as planet habitability, stellar evolution, the origin of fast radio bursts, the evolution of debris discs, and the dynamics of accretion discs in binary and higher-order star systems. Accretion discs around binary star systems are ubiquitous in the galaxy and planet formation is thought to occur within these discs. Circumbinary discs are commonly observed to be misaligned with respect to the binary orbital plane. A misaligned circumbinary disc eventually evolve to a stable orientation, either coplanar or polar with the binary orbital plane. The process of disc alignment has important …

A Process For Adm-300 Radiation Detector Modernization For Military Applications, Caesar R. Pereira

UNLV Theses, Dissertations, Professional Papers, and Capstones

An investigation to re-evaluate the current use in military applications of the ADM-300 Multi-Functional Survey Instrument and its requirements are provided. This paper outlines a method to upgrade the ADM-300 due to its eventual obsolescence using newly developed requirements that meet the original justification for use in the USAF in 1992. The capabilities and features of various detectors are analyzed and compared to the ADM-300. Response curves are generated using Monte Carlo simulations. The detectors are prioritized based on their performance to create metrics. A metanalysis of the metrics is conducted to limit bias within the process and justify their …