This thesis has been motivated by the idea of harvesting the energy from ambient vibrations via nonlinear dynamics of the parametric pendulum. It aims to cover those aspects of the pendulum dynamics, which are relevant for energy extraction purposes and have not been addressed in previous studies. A simple system like parametric pendulum can experience variety of responses. One of them is rotary motion, which is characterised by significantly higher kinetic energy than oscillations and thus has a potential of delivering more energy, when subjected to the parametric excitation. Initially, a preliminary study on the dynamics of parametric pendulum has been conducted. This involved comparison of oscillatory and rotary responses with a view to application in energy harvesting, numerical continuation of rotary solutions and developing a control method for initiating and maintaining the desired response. As a next step, different forcing configurations have been considered, including pendulum excited along a tilted axis and a combined excitation, where pendulum additionally performs rocking action. The influence of the forcing arrangement on the lower limit of stability of rotary motion has been examined. The vibrations which can be observed in the environment are rarely perfectly harmonic. To provide more realistic results, the response of the pendulum under noisy excitation has been studied. Different types of noise have been considered and their influence on the pendulum rotation examined. One of the major energy sources, which could be utilised are the oscillating ocean surfaces. Therefore, a stochastic model of the sea wave has been constructed and the response of the pendulum system studied under parametric excitation by a wave profile. Finally, taking into account the imbalanced forces which rotating pendulum exerts on the supporting base, the model has been extended to a system of two pendulums. Synchronization in such a system was studied. The influence of the synchronization mode on the rotation of the pendulums and on the stability of supporting structure was considered. All of the numerical results presented in this thesis have been verified experimentally to ensure good correspondence.

Progress in our understanding of the chemical composition of the interstellar medium leans both on laboratory analyses of high resolution rotational spectra from molecules that may be present in these regions, and on radio astronomical observations of molecular tracers to constrain astrochemical models. Due to the thermodynamic conditions in outer space, some molecules likely to be found in interstellar regions in relevant abundances are open shell radicals. In a series of laboratory studies, the pure rotational spectra of the transition metal containing radicals sulfur species ScS, YS, VS and ZnSH were obtained for the first time. In addition to accurate and precise rest frequencies for these species, bonding characteristics were determined from fine and hyperfine molecular parameters. It was found that these sulfides have a higher degree of covalent bonding than their mostly ionic oxide counterparts. Isomers and isotope ratios are excellent diagnostic tools for a variety of astrochemical models. From radio observations of isotopes of nitrile species, the galactic gradient of ¹⁴N/¹⁵N was accurately established. A further study of this ratio in carbon rich asymptotic giant branch stars provided observational evidence for an unknown process in J type carbon stars, and highlighted the need to update stellar nucleosynthesis models. Proper radiative transfer modeling of the emission spectra of interstellar molecules can yield a wealth of information about the abundance and distribution of these species within the observed sources. To model the asymmetric emission of SO and SO₂ in oxygen-rich supergiants, an in-house code was developed, and successfully applied to gain insight into circumstellar sulfur chemistry of VY Canis Majoris. It was concluded that current astrochemistry kinetic models, based on spherical symmetry assumptions, need to be revisited.

High-resolution pulsed beam Fourier Transform Microwave Spectroscopy (PBFTMS) technique has been used to investigate the rotational spectra, molecular structures and electronic charge distribution of organometallic and organic molecules. The thesis reports high-resolution rotational spectral findings for nine different asymmetric-top molecules in the singlet electronic ground state including: Cyclopentadienyltungstentricarbonylhydride, Bis-(cyclopentadienyl)tungstendihydride, Tetracarbonylethyleneosmium, two substituted Ferrocenes and an organic keto-enol tautomeric system, Z-2-Hydroxypyridine and 2-Pyridone. Moreover, gas-phase rotational constants and distortion constants have also been reported for an excited vibrational state of Cyclopentadienylnickelnitrosyl complex using a high-resolution Fourier Transform Spectrometer (FTS) system at Kitt Peak Arizona, (KPNO). Preliminary microwave results for a fluxional molecule, Cyclopentadienyliridiumdicarbonyl are also presented in this work. Extensive Density Functional Theory (DFT) calculations have been performed in conjunction with the experiments to provide additional insight toward further understanding the equilibrium structures, structural isomers and electric field distributions of these molecules. These calculations were not only helpful in predicting the preliminary structure and rotational constants of the molecules of interest, but also advantageous in analyzing the observed spectra.

Millimeter wave studies of molecules in circumstellar envelopes and a planetary nebula have been conducted. Using the Submillimeter Telescope (SMT) of the Arizona Radio Observatory (ARO) on Mt. Graham, a comparative spectral survey from 215-285 GHz was carried out of the carbon-rich asymptotic giant branch star IRC +10216 and the oxygen-rich supergiant VY Canis Majoris. A total of 858 emission lines were observed in both objects, arising from 40 different molecules. In VY Canis Majoris, AlO, AlOH, and PO were detected for the first time in interstellar space. In IRC +10216, PH3 was detected for the first time beyond the solar system, and C3O, and CH2NH were found for the first time in a circumstellar envelope. Additionally, in the evolved planetary nebula, the Helix, H2CO, C2H, and cyclic-C3H2 were observed using the SMT and the Kitt Peak 12 m telescopes. The presence of these three molecules in the Helix suggests that relatively complex chemistry occurs in planetary nebulae, despite the harsh ultraviolet field. Overall, the research on molecules in circumstellar and planetary nebulae furthers our understanding of the nature of the material that is fed back into the interstellar medium from evolved stars. Besides telescope work, laboratory research was also conducted - the rotational spectrum of ZnCl was measured and its bond length and rotational constants were determined. Lastly, in partial fulfillment of a graduate certificate in entrepreneurial chemistry, the commercial applications of terahertz spectroscopy were explored through literature research.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Dissertation (Ph. D.)--University of Akron, Dept. of Electrical and Computer Engineering, 2008. / "December, 2008." Title from electronic dissertation title page (viewed 12/29/2008) Advisor, Nathan Ida; Committee members, Robert J. Veillette, George C. Giakos, Jiang John Zhe, Gerald W. Young; Department Chair, Jose Alexis De Abreu-Garcia; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Mémoire (M.Sc.A.)--Université du Québec à Chicoutimi, 1991. / Document électronique également accessible en format PDF. CaQCU

Thesis (Ph.D.)--McMaster University, 2001 / Includes bibliographical references. Also available via World Wide Web.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 105-111).

Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Aug. 27, 2007). Includes bibliographical references.