Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Includes bibliographical references. / M.S.

Vita. / Digitized by Kansas Correctional Industries

Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. / Microfiche copy available in Archives and Science. / Vita. / Includes bibliographical references. / Sc.D.

Thermal radiation is ubiquitous to all matter at finite temperature and controlling the radiative nature of that matter has been a key enabling factor in the development of several recent technologies, such as thermal diodes, thermal antennae, thermophotovoltaics, heat-assisted magnetic recording, and contactless cooling in microelectromechanical systems. At the micro/nano-scale, thermal radiation does not reliably behave in the way Planck's blackbody law predicts, due to near-field effects such as the diffraction, interference, and tunneling of light. In fact, the so-called blackbody limit can routinely be broken by several orders of magnitude when objects of dimensions or separation distances much smaller than the peak thermal wavelength (approximately 10 \si{\micro\meter} at room temperature) exchange thermal radiation. A deeper theory is required to understand near-field thermal radiation: Maxwell's equations. Maxwell's equations allow for a direct connection between the thermally induced current fluctuations and radiative transfer. In this dissertation, I investigate radiative transfer among spherical bodies aligned in a linear chain. The chain may be composed of any number of spheres, and the spheres themselves may be composed of any linear isotropic material, may be of any size and separation distance, and may each have any number of spherically symmetric layers. Using a dyadic Green's function formalism, I derive numerically exact formulas for heat transfer between pairs of spheres in the chain and between any sphere in the chain and its environment. My work clearly demonstrates that adding coatings to spherical objects can drastically impact the spectrum of radiative transfer, enhancing or diminishing it in various cases. This degree of tailoring makes coated spheres a flexible, yet unexplored, platform for future experiments in near-field radiative heat transfer. My work also demonstrates that, in an experiment measuring the distance dependent heat transfer between two spheres, heat transfer from the spheres to their environment can also have a strong distance dependence, which must be considered carefully when designing an experiment and analyzing its results. This demonstrates a cautious but optimistic outlook for the near-field radiative heat transfer community moving beyond traditional plane-plane and sphere-plane experimental configurations.

Ren Liyuan = 小寬高比熱對流中高精度Nusselt數和局部溫度測量 / 任立元. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 64-66). / Text in English; abstracts in English and Chinese. / Ren Liyuan = Xiao kuan gao bi re dui liu zhong gao jing du Nusselt shu he ju bu wen du ce liang / Ren Liyuan. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.ix / Chapters / Chapter I. --- Turbulent Rayleigh-Benard Convection --- p.1 / Chapter 1.1 --- Introduction of Rayleigh-Benard Convection --- p.1 / Chapter 1.2 --- The Convection Equations --- p.2 / Chapter 1.3 --- The parameters --- p.3 / Chapter 1.4 --- Background --- p.5 / Chapter 1.5 --- Synopsis of this thesis --- p.8 / Chapter II. --- Experimental Setup and Methods --- p.9 / Chapter 2.1 --- The Apparatus --- p.9 / Chapter 2.2 --- Thermistor Calibration --- p.12 / Chapter III. --- Local temperature measurements --- p.19 / Chapter 3.1 --- Introduction and motivation --- p.19 / Chapter 3.2 --- Local temperature measurements --- p.20 / Chapter 3.3 --- Temperature time series and histograms --- p.20 / Chapter 3.4 --- Mean temperature profile --- p.24 / Chapter 3.5 --- Summery --- p.35 / Chapter 3.6 --- Appendix A: Data lists for this chapter --- p.36 / Chapter IV --- Heat transport measurement --- p.39 / Chapter 4.1 --- Introduction and Motivation --- p.39 / Chapter 4.2 --- Heat transfer measurements --- p.40 / Chapter 4.3 --- Experimental uncertainties associated with high-precision measurements of Nu --- p.41 / Chapter 4.3.1 --- Cell height measurement --- p.41 / Chapter 4.3.2 --- Temperature measurement --- p.41 / Chapter 4.3.3 --- Thermal source --- p.41 / Chapter 4.3.4 --- Thermal leakage --- p.42 / Chapter 4.3.5 --- Sidewalleffect --- p.44 / Chapter 4.3.6 --- Long time measurement --- p.44 / Chapter 4.4 --- Results and discussion --- p.45 / Chapter 4.4.1 --- Experimental data --- p.45 / Chapter 4.4.2 --- Finite conductivity effect --- p.47 / Chapter 4.4.3 --- Nu dependence on Г --- p.49 / Chapter 4.4.4 --- Nu dependence on Ra --- p.50 / Chapter 4.5 --- Summary --- p.53 / Chapter 4.6 --- Appendix B: Data lists for this chapter --- p.54 / Chapter V. --- Conclusions --- p.62 / References --- p.64

This thesis focuses on the electrical and thermal transport properties of two distinct systems: lead halide perovskites and layered materials. While unrelated, each system relies on diffusion phenomena in several ways. The first part of this work therefore explores particulate, charge carrier and thermal diffusion to establish a framework on which the rest of this thesis lays. In this first section, an introduction to the many measurement techniques are also included. The interested reader and future members of the lab will hopefully find this as a useful primer and can also find relevant and practical information involving the manipulation of some of these instruments in the Appendix as well. The second part of this thesis focuses entirely on lead halide perovskites. Despite its complex nature, or perhaps because of it, lead halide perovskites have recently enjoyed increasing attention from the scientific community at large for photovoltaic, thermoelectric and optoelectronic applications. Although photovoltaic efficiencies over 20 % have been reported and continue to rise, very little is still understood about the mechanism of transport within the system as a whole. Debates on improving performances have focused primarily on the A-type cation in the APbX3 perovskite structure, often pointing to the organic cation as the magical ingredient that lends lead halide perovskites their superpowers. We explore this notion by studying the diffusion lengths of charge carriers and mean free paths of phonons in a series of lead halide perovskites, focusing both on the A-type cation and the halide anion composition. Using several optical and optoelectronic techniques, we show that that the composition of the A-type cation has only a secondary effect on thermal and charge carrier transport, and note that the halide is a stronger influencing factor for both means of transport. We deconstruct the transport distances into individual contributions from speed and lifetime, and note differences not only across the series of perovskites but also between charge carrier types, ultimately allowing us to suggest areas of improvement for future photovoltaic and thermoelectric device designs. Finally, we begin the exploration of the interplay between structure and transport through a detailed study of the crystal structure via SCXRD as well as the transport phenomena, both as a function of temperature. The third and final part of this thesis shifts gears and looks at the work that we’ve done with layered materials and intercalation. The intercalation of layered materials is a time-honored tradition in chemistry and has proven to be an effective and reversible doping method for many solid-state materials. This sections begins with a discussion of more traditional materials and the development of techniques within our lab that can now be used to intercalate mesoscopic samples electrochemically. We then expand this study to include van der Waals heterostructures, showing for the first time ever, the intercalation of a heterointerface of this nature. We then conclude with preliminary work that has been done to extend the traditional notions of layered materials and their intercalation to superatomic structures. Both of these systems represent a path to new class of exciting and yet-to-be-studied materials.

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Banca: Álvaro de Souza Dutra / Banca: Messias Borges da Silva / Banca: Estaner Claro Romão / Banca: Carlos Alberto Moreira dos Santos / Bancs: Durval Rodrigues Junior / Resumo: Disserta-se nessa tese sobre o uso de analogias como recurso didático na disciplina de transmissão de calor. A aplicação de analogias no ensino é revisada na literatura, de modo que se estabeleça um referencial teórico que justifique este uso. Assim, propõe-se que a analogia possa ser interpretada como um mediador simbólico de Vigotski. Usos de analogias adaptadas ou desenvolvidas em sala de aula pelo autor da presente tese são apresentados. As impressões do autor acerca da receptividade dos alunos ao recurso são discutidas, bem como alguns casos de interação com os alunos são apresentados / Abstract: The use of analogies as a didactic resource in the discipline of heat transfer is discussed in this thesis. The application of analogies in teaching is reviewed in the literature, so that a theoretical framework that justifies the use of analogies can be established. Thus, it is proposed that the analogy can be interpreted as a Vigotski's symbolic mediation. Uses of analogies either adapted or developed in the classroom by the author of this thesis are presented. The impressions of the author about the students' receptivity to the resource are discussed, as well as some cases of interaction with the students are presented

The continental shelf on the western side of the Antarctic Peninsula is a region of substantial climate and ecosystem change. The Long Term Ecological Research project at Palmer Station has been sampling and studying the shelf ecosystem and physical environment since 1990. This dissertation seeks to improve our understanding of the subtidal and intraseasonal (hereafter defined together as 3-100 days) circulation on the neighboring continental shelf and is particularly motivated by the aims of the project to understand (1) how lateral transports of scalar parameters such as heat affect the vertical stratification and (2) how coastal canyon heads are linked to the larger-scale shelf circulation and why they are such ecologically productive environments. In this dissertation we study: (1) the origin and mixing of mesoscale eddies as agents of heat transport and stirring; (2) the spatial coherence of shelf-scale barotropic velocity fluctuations, their origin through flow-topography interaction with Marguerite Trough Canyon, and their associated heat transports; and (3) the wind-driven dynamics of the long-shore flow manifested through coastal trapped waves and their ability to both induce upwelling at a coastal canyon head and to modulate isopycnal depth at the continental shelf-break. This work takes an observational approach, utilizing the rare and expansive data set afforded by the long-term sampling program including shipboard CTD and ADCP profiles, moored current meter time series, and CTD profiles from an autonomous underwater vehicle.

Bibliography: leaves 114-119.