Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2004. / Kok-Meng Lee, Committee Chair ; Andrei G. Fedorov, Committee Member ; William E. Singhose, Committee Member ; David G. Taylor, Committee Member ; Zhi Zhou, Committee Member. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, June 1990. / Thesis Advisor(s): Kraus, Allan D. Second Reader: Brown, Sue. "June 1990." Description based on signature page. DTIC Identifier(s): Radiators (heating and cooling), radiative transfer, heat transfer (radiation). Author(s) subject terms: Radiative heat transfer, longitudinal fins, free space and non-free space. Includes bibliographical references (p. 147-148). Also available online.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 105-114).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2007. / Includes bibliographical references (p. 53-55).

Observations of exoplanet transit spectra are essential to understanding the physics and chemistry of distant worlds. The effects of opacity sources and many physical processes combine to set the shape of a transit spectrum. Two such key processes-refraction and cloud and/or haze forward-scattering-have seen substantial recent study. However, models of these processes are typically complex, which prevents their incorporation into observational analyses and standard transit spectrum tools. In this work, we develop analytic expressions that allow for the efficient parameterization of forward-scattering and refraction effects in transit spectra. We derive an effective slant optical depth that includes a correction for forward-scattered light, and present an analytic form of this correction. We validate our correction against a full-physics transit spectrum model that includes scattering, and we explore the extent to which the omission of forward-scattering effects may bias models. Also, we verify a common analytic expression for the location of a refractive boundary, which we express in terms of the maximum pressure probed in a transit spectrum. This expression is designed to be easily incorporated into existing tools, and we discuss how the detection of a refractive boundary could help indicate the background atmospheric composition by constraining the bulk refractivity of the atmosphere. Finally, we show that opacity from Rayleigh scattering and collision-induced absorption will outweigh the effects of refraction for Jupiter-like atmospheres whose equilibrium temperatures are above 400-500 K.

The gas kinetic temperature (T-K) of various interstellar environments is often inferred from observations that can deduce level populations of atoms, ions, or molecules using spectral line observations; H I 21 cm is perhaps the most widely used, and has a long history. Usually the H I 21 cm line is assumed to be in thermal equilibrium. and the populations are given by the Boltzmann distribution. A variety of processes, many involving Ly alpha, can affect the 21 cm line. Here we show how this is treated in the spectral simulation code Cloudy, and present numerical simulations of environments where this temperature indicator is used, with a detailed treatment of the physical processes that determine level populations within H-0. We discuss situations where this temperature indicator traces TK, cases where it fails, as well as the effects of Lya pumping on the 21 cm spin temperature. We also show that the Lya excitation temperature rarely traces the gas kinetic temperature.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21573号 / 理博第4480号 / 新制||理||1643(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 前田 啓一, 准教授 上田 佳宏, 教授 嶺重 慎 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Research on the propagation of acoustic waves in ocean bottom sediment is of interest for active sonar applications such as target detection and remote sensing. Currently, all seabed scattering models available in the literature are based on the full solution of the wave equation, which sometimes leads to mathematically intractable problems. In the electromagnetics community, an alternative formulation that overcomes some of this complexity is radiative transfer theory, which has established itself as an important technique for remote sensing. In this work, radiative transfer (RT) theory is proposed for the first time as a tool for the study of seabed acoustic scattering. The focus of this work is the development of a complete model for the interaction of acoustic energy with water-saturated sediments. The general geometry considered in this study consists of multiple elastic layers containing random distributions of inhomogeneities. The accuracy of the proposed model is assessed by rigorous experimental work, with data collected from random media in which acoustic properties such as the concentration and size of scatterers, background material, and the presence of elastic boundaries are controlled parameters. First, the ultrasound RT model is implemented for layers of finite thickness. The range of applicability of the proposed model is then illustrated using scaled experiments conducted at the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab). Next, the model is applied to field data collected in a region with gassy sediments and compared to the formulation originally used to explain these data. Finally, insight into the emerging area of study of the time-dependent RT formulation is presented, and its role in the representation of finite broadband pulses is discussed.