Time-frequency representations (TFR) are a widely used tool to analyze signals of guided waves such as Lamb waves. As a consequence of the uncertainty principle, however, the resolution in time and frequency is limited for all existing TFR methods. Due to the multi-modal and dispersive character of Lamb waves, displacement or energy related quantities can only be allocated to individual modes when they are separated in the time-frequency plane. The chirplet transform has been introduced as a generalization of both the wavelet and Short-time Fourier transform. It offers additional degrees of freedom to adjust time-frequency atoms which can be exploited in a model-based approach to match the group delay of individual modes. The objective of the current thesis is to apply the algorithm proposed by Kuttig to a series of candidate nondestructive evaluation problems. The accuracy and robustness of the CT based procedure is examined for each of these example problems and is benchmarked against analytical solutions (if available) and to the conventional STFT.

Purpose: To compare and analyze the differences in visual outcomes between Visx iDesign Advanced WaveScan Studio (TM) System, Alcon Wavelight Allegro Topolyzer and Nidek EC-5000 using Final Fit (TM) Custom Ablation Treatment Software from the submitted summary of safety and effectiveness of the US Food and Drug Administration (FDA) data. Methods: In this retrospective comparative study, 334 eyes from Visx iDesign, 212 eyes from Alcon Contour, and 135 eyes from Nidek CATz platforms were analyzed for primary and secondary visual outcomes. These outcomes were compared via side-by-side graphical and tabular representation of the FDA data. Statistical significance was calculated when appropriate to assess differences. A P-value <0.05 was considered statistically significant. Results: The mean postoperative uncorrected distance visual acuity (UDVA) at 12 months was 20/19.25 +/- 8.76, 20/16.59 +/- 5.94, and 20/19.17 +/- 4.46 for Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. In at least 90% of treated eyes at 3 months and 12 months, all three lasers showed either no change or a gain of corrected distance visual acuity (CDVA). Mesopic contrast sensitivity at 6 months showed a clinically significant increase of 41.3%, 25.1%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. Photopic contrast sensitivity at 6 months showed a clinically significant increase of 19.2%, 31.9%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. Conclusion: FDA data for the three platforms shows all three were excellent with respect to efficacy, safety, accuracy, and stability. However, there are some differences between the platforms with certain outcome measurements. Overall, patients using all three lasers showed significant improvements in primary and secondary visual outcomes after LASIK surgery.

Report (M.S.)--Virginia Polytechnic Institute and State University. M.S. 1991. / Vita. Abstract. Includes bibliographical references (leaves 84-88). Also available via the Internet.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographical references.

Thesis (M.S.)--University of Louisville, 1995. / School of Dentistry, Department of Biological and Biophysical Sciences. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Louisville, 1995. / School of Dentistry, Department of Biological and Biophysical Sciences. Includes bibliographical references.

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Thesis (Ph.D.)--Boston University. / An analysis is given which treats experimental heat-transfer data obtained during flights of three V-2 rockets and two Aerobee rockets. This work was conducted largely at Boston University under Air Force Contracts W28-099-ac-395 and AF 33(615)-382. The instrumentation and rocket-flight phases extended from 1947 to 1952, while the analysis was carried out in the period from 1953 to 1955. A total of nine V-2 rockets were instrumented to some extent for the purposes of this experiment. The missiles for which data have been analyzed were chosen on the basis of best performance on the part of both instrumentation and rocket. Experimental equipment of special design was produced and installed by the Boston University group in the rockets which were launched in the White Sands area in New Mexico. Extensive field trips were required in this connection, both for the experiment on heat0transer and others in which the same group participated at the same time. The general program was one of research in physics of the upper atmosphere. Since the conclusion of the supporting contracts in October of 1954, additional consideration of the experimental results has continued on a private basis. The data obtained during the course of the present experiment were in the form of temperature variations as experienced by heat meters which were placed at selected locations over the body and fin of the rockets. The heat meters were small circular diaphragms of stainless steel which were placed flush with the rocket skin. Each diaphragm had on its central inner surface a pair of resistance thermometers made of nickel wire, with a diameter of 0.002". The thermometers were switched in sequence into a resistance bridge. One thermometer had always a higher resistance than the other, an arrangement which served two purposes. Firstly, the two values of voltage for a given temperature permited unambiguous determination of the direction in which the resistance bridge was unbalanced. Secondly, these two values of voltage were handled independently by our own instrumentation, and by the recording or telemetry devices. When two such different values of voltage were finally translated back into their equivalent temperatures, close agreement of the temperature values lent considerable support to their accuracy. When the two thermometers reported temperatures which were significantly different from each other, restraint was indicated in trusting their accuracy. Fortunately, close agreement of temperatures reported by the dual thermometers was the more usual experience. [TRUNCATED]