Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 94-98).

Thesis (M.S. in Physics)--Naval Postgraduate School, June 2010. / Thesis Advisor(s): Karunasiri, Gamani ; Grbovic, Dragoslav. "June 2010." Description based on title screen as viewed on July 15, 2010. Author(s) subject terms: Bi-material Pixel, Terahertz Imaging, Deformation, Multi-layer stack, Terahertz Absorption, COMSOL finite element modeling, Fresnel's Equations, Dielectric Bragg reflector, FTIR Spectroscopy, maximizing the THz absorption. Includes bibliographical references (p. 51-52). Also available in print.

First published in the Bulletin of the American Mathematical Society in Vol.69, 1963, published by the American Mathematical Society

First published in the Bulletin of the American Mathematical Society in Vol.70, 1964, published by the American Mathematical Society

Chapter II of this thesis describes the operation of a Fourier Transform Ion Cyclotron Resonance Spectrometer. Included is a detailed discussion of software which was developed to run the spectrometer and analyze the data. An automatic data acquisition system for kinetic experiments is also described. Chapter III contains a short discussion of discrete versus continuous methods of data acquisition and problems with the FT-ICR method which utilizes discrete sampling. Two techniques are discussed which have been found to solve problems associated with a digital system, acquisition by "mixing" and zero-filling. Also, mass calibrations done on the FT-ICR spectrometer are presented. The reactions of some negative ions with esters in the gas phase have been studied by FT-ICR and are discussed in Chapter IV. The reactions of ¹⁸0 labelled methoxide with methyl trifluoroacetate, methyl benzoate, dimethyl carbonate, diethyl carbonate and dipropyl carbonate have been studied. It was found that there is incorporation of ¹⁸0 in product ions of the form RCOO⁻ showing that methoxide attacks esters in the gas phase partially at carbonyl carbon. Product distributions are found to be consistent with two competing mechanisms, B[sub AC]2 and S[sub N]2. Thus it was found that CH₃•0⁻ reacts with C₆H₅COOCH₃- 92% by a B[sub AC]2 type mechanism and 8% by an S[sub N]2 type mechanism. The amount of ¹⁸0 incorporation in product ions was seen to decrease with the presence of β hydrogens, due to the presence of an elimination channel. The reaction of ethoxide with the above named esters was studied and the products are also interpreted in terms of three competing mechanisms, B[sub AC]2, S[sub N]2 and elimination. / Science, Faculty of / Chemistry, Department of / Graduate

Yes / This paper investigates the performance of wavelet OFDM signals over a wireless communications link. The scheme is shown to be generally similar to Fourier based OFDM, but with some additional features, and improved characteristics. The sensitivity of both schemes to the nonlinear amplification in the transmitter is compared by monitoring the time domain output data and the adjacent channel power ratio (ACPR) performance.

No description available.

Over the past few decades, the demand for digital information has increased drastically. This enormous demand poses serious difficulties on the storage and transmission bandwidth of the current technologies. One possible solution to overcome this approach is to compress the amount of information by discarding all the redundancies. In multimedia technology, various lossy compression techniques are used to compress the raw image data to facilitate storage and to fit the transmission bandwidth. In this thesis, we propose a new approach using algebraic integers to reduce the complexity of the Daubechies-4 (D4) and Daubechies-6 (D6) Lifting based Discrete Wavelet Transforms. The resulting architecture is completely integer based, which is free from the round-off error that is caused in floating point calculations. The filter coefficients of the two transforms of Daubechies family are individually converted to integers by multiplying it with value of 2x, where, x is a random value selected at a point where the quantity of losses is negligible. The wavelet coefficients are then quantized using the proposed iterative individual-subband coding algorithm. The proposed coding algorithm is adopted from the well-known Embedded Zerotree Wavelet (EZW) coding. The results obtained from simulation shows that the proposed coding algorithm proves to be much faster than its predecessor, and at the same time, produces good Peak Signal to Noise Ratio (PSNR) at very low bit rates. Finally, the two proposed transform architectures are implemented on Virtex-E Field Programmable Gate Array (FPGA) to test the hardware cost (in terms of multipliers, adders and registers) and throughput rate. From the synthesis results, we see that the proposed algorithm has low hardware cost and a high throughput rate.

There are many different methods available for the solution of the heat equation and the choice of which to use is dependent upon the nature of the problem and the specific regions of the domain where the temperature is required. In the case of melting or freezing problems it is usual for the position of the boundary, at which change of physical state (phase change) occurs, to be of greater interest than the temperature at particular points. Again there are several solution methods enabling the tracking of the moving interface between the physical states of the material. For this work we begin with the isotherm migration method, which first appeared in the 1970s but is less frequently cited now. We first solve problems in one dimension with no phase change using the isotherm migration method, which is in itself new work, since all references we have found allude to it as a tool for the solution of phase change problems. We test the method using a variety of examples to explore the difficulties and challenges it produces, and we find it to be robust and tolerant of errors. We then combine it with the Laplace transform method, a well-established technique for solving ordinary and partial differential equations, in which the number of independent variables is reduced by one. The solution is then transformed back into the time domain using a suitable numerical process. The Laplace transform isotherm migration method is a new process, not mentioned previously to our knowledge, and it produces results which are comparable with the isotherm migration method. The new process is applied to one-dimensional phase change problems,where we find that due to the mathematics at the phase change boundary, we are required to make a modification to the usual manner of operating the Laplace transform. This is novel as far as we are aware. Our method is applied to a variety of problems and produces satisfactory results. We then move on to a two-dimensional setting where we find the situation to be much more complex and challenging, as it requires interpolation and curve-fitting processes. Finally we examine the possiblity of speeding up the calculation time using the Laplace transform isotherm migration method by setting problems in a parallel environment and using an MPI platform. This has not been previously attempted and we are able to show a measure of success in our objective.

The main advantage of wavelet transform relative to its Fourier analysis counterpart is its suitability to deal with transient signals. Furthermore, wavelet packet transform has very good frequency analytic ability with the result that it is developing in very fast speed and widespread researched and used in industry and academia. We study the characteristics of fiber optic sensors by applying wavelet transform. Hence, in this paper, the traditional Fourier analysis is taken as a basis, and the wavelet packet analysis is taken as a comparison. The major objects include: (1) calibration of hydrophones; (2) vibration measurement. In calibration of hydrophones, the experimental results show a 2.72 dB re V/£gPa inaccuracies and a 5.3 dB re V/£gPa standard deviation by Fourier analysis, but 0.5 dB inaccuracies and 1.6 dB re V/£gPa standard deviation by wavelet packet analysis. It shows that the wavelet packet analysis has better analytic ability than that of traditional Fourier analysis. In vibration measurement, we utilize FBG interferometers to measure stable vibration. The experimental results denote that wavelet packet analysis has excellent frequency analytic ability as Fourier analysis. Besides, in obtaining transient characteristic signals induced by falling stones, the results appear that wavelet packet analysis has better resolution and identification capability relative to Fourier analysis.