Physics Commons^™

On The Propagation Of Atmospheric Gravity Waves In A Non-Uniform Wind Field: Introducing A Modified Acoustic-Gravity Wave Equation, Ahmad Talaei

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Atmospheric gravity waves play fundamental roles in a broad-range of dynamical processes extending throughout the Earth’s neutral atmosphere and ionosphere. In this paper, we present a modified form for the acoustic-gravity wave equation and its dispersion relationships for a compressible and non-stationary atmosphere in hydrostatic balance. Importantly, the solutions have been achieved without the use of the well-known Boussinesq approximation which have been used extensively in previous studies.

We utilize the complete set of governing equations for a compressible atmosphere with non-uniform airflows to determine an equation for vertical velocity of possible atmospheric waves. This intricate wave equation is simplified …

Thermal Property Measurement Of Thin Fibers By Complementary Methods, Troy Robert Munro

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Thin fibers are prevalent in many engineering materials. Measuring how well heat transfers in such small fibers can be difficult to determine, and previous methods have led to erroneous results. This dissertation details three proposed methods to improve the measurement of the thermal conductivity, thermal diffusivity, and volumetric heat capacity of thin fibers. Of particular interest is natural and synthetic spider silks because previously published values of the natural silk thermal conductivity was similar to copper, an excellent thermal conductor.

The three methods developed are the improved transient electrothermal technique (which was redeveloped to include radiation and convection heat losses …

Rayleigh-Scatter Lidar Measurements Of The Mesosphere And Thermosphere And Their Connections To Sudden Stratospheric Warmings, Leda Sox

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Earth’s middle atmosphere is comprised of the stratosphere, mesosphere and thermosphere, from approximately 10 to 110 km, or approximately 6 to 68 miles. An understanding of the dynamics and climatological conditions in this region is of vital importance to the aerospace industry and military, which both launch aircraft and spacecraft into this region, as well as researchers who study climate change and the interactions between the atmosphere and the Earth, oceans, and space.

Measurements of atmospheric properties (density, temperature, and pressure) in this region are relatively difficult to gather as the middle atmosphere’s altitudes are both too high for …

Investigating The Effect Of Carbon Nanotube Functionalization In A Polydimethylsiloxane Composite Through Use Of A Stepped Bar Apparatus, Matthew I. Ralphs

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Thermal interface materials (TIMs) are used in transporting heat away from a circuit or electronic module. Composite materials are a popular research area for TIMs because they allow the desired properties to be joined in a composite to take advantage of the best properties from all the constituents involved. The composite selected for this study uses carbon nanotubes (CNT) as the filler and an elastomeric polymer for the matrix, specifically a multiwalled carbon nanotube (MWCNT) / polydimethylsiloxane (PDMS) composite. This study looks at chemical modification (functionalization) of the CNTin an effort to produce a better bond between the CNT and …

Cryostat System For Spacecraft Materials Testing, Justin Dekany

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An existing space environment simulation test chamber used in the study of electron emission, sample charging and discharge, electrostatic discharge and arcing, electron transport, and luminescence of spacecraft materials now has extended temperature control capabilities. By incorporating a two-stage, closed-cycle helium cryostat, it is now possible to simulate the temperature typical spacecraft will experience when in orbit, ranging from < 40 K to > 450 K. The system was designed to maintain compatibility with an existing ultrahigh vacuum chamber that can simulate diverse space environments. This vacuum chamber can simulate space environment conditions by producing the same pressure, amount of electrons, electromagnetic radiation and temperature …