Pure rotational spectra of simple metal carbon clusters that relevant to transition metal synthesis and catalysis have been obtained using Fourier transform microwave (FTMW) techniques combined with millimeter-wave direct-absorption methods. Rotational spectra of metal acetylides (CuCCH, ZnCCH, Li/Na/KCCH, MgCCH, AlCCH, CrCCH), diatomic metal monocarbide (CrC) and T-shape metal dicarbides (YC₂ and ScC₂) were recorded in the 4–650 GHz frequency regime. Measurements of weaker isotoplogues including ⁶⁶ZnCCH, ⁶⁸ZnCCH, Zn¹³C¹³CH, ZnCCD, Li/Na/KCCD, CrCCD, Y¹³C¹²C, Y¹³C¹³C, Sc¹³C¹³C, were also studied to aid in structural determinations. This work is the first study of ZnCCH and ScC₂ by any type of spectroscopic technique. Hyperfine splittings in MgCCH and Li/Na/KCCH have also been resolved and the weak isotoplogues of YC₂ have been measured for the first time. Potential interstellar molecules ScO and FeCN were studied using the FTMW techniques in the 4–62 GHz frequency regime. Spectra of the zinc insertion product ClZnCH₃ were additionally recorded in the 10–30 GHz (FTMW) and 260–296 GHz (direct absorption) frequency ranges, along with weaker isotopologues Cl⁶⁶ZnCH₃ and Cl⁶⁸ZnCH₃. This works is the first measurement of zinc insertion products using the FTMW-DALAS techniques. The data were analyzed implementing an effective Hamiltonian, allowing for accurate spectroscopic parameters to be established. From rotational constants, the molecular geometries were accurately determined. Electronic properties were also assessed, including the degree of covalent vs ionic character in a chemical bond, and the molecular orbital composition. The fundamental physical and chemical properties of these benchmark species were obtained in order to gain insight into their role in larger molecular systems, test theoretical calculations, and, in certain cases, provide accurate rest frequencies for astronomical searches.

Transient heat transfer phenomena in the rotational molding of plastic parts are modeled in this study. Natural convection and radiation from the furnace and flue gases to the mold housing are analyzed. Other models include transient heat transfer through the mold, single-phase conduction through the particulate plastic material prior to phase change, melting of the plastic and heating of the liquid pool. Subsequent staged cooling of the mold and solidification of the plastic using a combination of free and forced convection and radiation, are also modeled. The mold wall, melt, and solidified plastic regions are divided into a number of finite segments to track the temperature variation with time during the molding process. The corresponding variations in masses and thicknesses of the melt and solidified plastic regions are estimated. This information is used to estimate the energy consumption rates for various phases of the process. The model is applied to a specific molding process in a commercial rotational molding plant. Parametric studies of the effect of heating and cooling durations on the plastic temperatures and the energy consumption rates are conducted. These analyses provide insights about opportunities for optimization of the heating and cooling schedules to reduce overall energy consumption and improve throughput. The overall energy and gas consumption for the rotational molding process, taking into consideration the thermal mass of the auxiliary housing (steel) required to hold the molds, is estimated on a per-batch basis. In addition, a preliminary design for an alternative system for heating and cooling the molds using a high temperature heat transfer fluid (HTF) flowing through jackets integral to the molds is proposed.

The present work examines line measurements of pressure, temperature, and density in high speed, non-isobaric flows emanating from an underexpanded jet nozzle. Line images of rotational and vibrational Raman spectra are collected for a 8-mm linear laser probe, and are combined onto the same EMCCD detector. Combining the two techniques allows for a single-shot measurement of major species, pressure, and temperature in a turbulent non-isobaric environment that is chemically reacting. Temperature measurements along the laser test section are extracted from the rotational Raman spectrum, whereas major species densities are measured by examining the intensities of their respective vibrational Raman lines. Pressure can be calculated using an equation of state, in every location along the linear laser probe. The technique feasibility is examined by performing measurements of pressure, temperature and density in a non-reacting underexpanded air jet where the chemical composition is constant and known. Future work will extend the technique to chemically reacting supersonic flows with unknown chemical composition.

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Many physical systems can be represented by a regular arrangement of molecules in a lattice structure. Knowing how neighboring molecules in the lattice interact with one another can give great insight into a material's macroscopic behavior. A very popular and effective means of investigating these microscopic interactions is the Ising Model. This model, suggested first by Wilhelm Lenz in 1920 and later expanded by Ernst Ising in 1925, is based on the assumptions that each molecule in a lattice structure can be represented by its spin value (+l or -1) and that only nearest neighbors contribute to the total interaction energy. The Ising Model, which was initially used in the study of ferromagnetic systems, can now be used to study a variety of physical systems. Some of these include antiferromagnetic crystals, binary alloys, DNA, and lattice gasses. / Department of Physics and Astronomy

No description available.

Thesis (Ph.D.)--Tufts University, 2004. / Adviser: Boris Hasselblatt. Submitted to the Dept. of Mathematics. Includes bibliographical references (leaves 61-62). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (doctoral)--Stockholm University, 1983. / Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Harry L. Swinney. Vita. Includes bibliographical references.