No description available.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: John H. Davis. Vita. Includes bibliographical references. Also available from UMI.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 50-51).

Carrots cooked by microwaves were judged less tender in both the core and external flesh area than those cooked by conventional boiling. Broccoli cooked by microwaves was less tender in the external layer but softer in the central flesh than that cooked conventionally. Cooking methods made essentially no difference in the concentration of water-insoluble pectic substances. The predominant factor responsible for the textural differences in vegetables cooked by microwaves seemed to be dehydration as evidenced by 1) a twofold water loss during cooking as compared to conventional method, 2) a significantly more shrunken contour of the vegetable piece, and 3) increased collapse of cells and extensive radial fissures in the paren-chymatous tissues. / Graduation date: 1974

The microwave spectra of CH₃I were measured on a C-band Stark cell microwave spectrometer. The lines were analyzed assuming that the quadrupole coupling eQq should be replaced by eQ(aJ(J + 1) + bK² + cK⁴/(J(J + 1)) + d) due to the presence of quadrupole centrifugal distortion. Explicit expressions were derived for a, b, and c in terms of molecular parameters. The values of a, b, and c were calculated for CH₃I and CD₃I and agree reasonably well with the experimental values. An algorithm was devised for the determination of the effect of hyperfine coupling on rotational energy levels in a molecule containing up to four nuclei of arbitrary spin. The uncoupled representation was used, and matrix elements were derived for spin-spin, spin-rotation, quadrupole, and Stark interactions. The case of three equivalent nuclei with spin of 1 was discussed. The microwave spectrum of phosphine-d₂ was measured and analyzed using two structural and three centrifugal distortion constants. Using molecular properties of phosphine, the centrifugal distortion tensor of phosphine-d₂ was calculated and the centrifugal distortion constants were determined. Only one of the three centrifugal distortion constants agreed well with the experimental value, suggesting that more data at higher frequencies is needed. The possibility of an electric hexadecapole interaction in CH₃I was discussed. A relationship between the magnitudes of the electric hexadecapole coupling constant and the d-orbital character of iodine in the C-I bond was derived. A gaussmeter specifically built for the determination of magnetic field in an Electron Paramagnetic Resonance experiment was described. A schematic diagram as well as a discussion of hardware was included.

Gas phase structures and other molecular parameters have been investigated for several molecules and dimers using pulsed beam Fourier Transform Microwave Spectroscopy. An automated control system has been designed and implemented for the microwave spectrometer that has allowed a systematic observation of the microwave spectrum for many molecules. The theoretical models that are available to the gas phase structural chemist, density functional theory and ab-initio methods, are described with detailed comparisons to experimental results. Experimental data was generated for systems involving hydrogen bonded dimers, organic molecules, inorganic molecules and organometallic molecules. Rotational constants and quadrupole coupling constants were determined using the microwave spectra. This data and isotopic investigations have been used to determine key structural parameters and molecular properties.

No description available.

Over the last century the electromagnetic (EM) spectrum has become ever more accessible with advances in technology. As a result, EM filters (or Frequency Selective Surfaces (FSSs)) have been developed for many applications. Such filters have been used on satellites and radomes. In this thesis, novel single layer and dual layer FSS have been studied and characterised, experimentally and using Finite Element Method (FEM) modelling, showing very good agreement between the data and models. The interesting transmission properties of these structurally complicated FSS are explained and the physics of the resonant modes that mediate transmission is explored. Enhanced transmission through an array of sub-wavelength apertures close to the diffraction limit has been a popular area of physics for many years. In addition enhanced reflection from metal patch arrays has been of great interest. This thesis studies original extensions of conventional FSS. The work is split into two main sections: single layer FSS and dual layer FSS. In the first experimental chapter (chapter 5) two new single layered FSS comprising complementary elements tessellated into composite arrays are explored (a connected array and a disconnected array). The behaviour of these arrays is compared with that of arrays of the constituent elements that either exhibit enhanced transmission or enhanced reflection phenomena. The behaviour of the connected composite array can be inferred from the behaviour of arrays of the constituent elements. Interestingly for the disconnected composite array, the behaviour can not be inferred from the constituent elements as without one or the other of the elements in situ, the modes supported on the composite array are not supported for the arrays of constituent elements. The second and third experimental chapters (Chapters 6 and 7) explore the transmission through dual layer arrays composed of either capped holes or capped annuli. Despite the holes being capped with a metal disc, the array exhibits a remarkably high transmission, mediated by the annular cavity formed between the caps and apertured metal sheet. In Chapter 7 concentrically nested annular patches above annular slots are used to achieve multiple transmission pass bands. For many applications it is often desirable to miniaturise resonant elements. Developing this concept further, chapter 8 explores the resonant frequency of a structured capped aperture. The internal structure of metal inclusions, give control over the resonant frequency of the cavity, reducing it's resonant frequency significantly and miniaturising the size of the cavity compared to the incident wavelength.