A well-made flute is always a compromise and the job of flute makers is to achieve a musically and aesthetically satisfying compromise; a task that involves much trial and-error. The practical aim of this thesis is to develop a mathematical model of the flute and a computer program that assists in the flute design process. Many musical qualities of a woodwind instrument may be calculated from the acoustic impedance spectrum of the instrument. A technique for fast and accurate measurement of this quantity is developed. The technique is based on the multiple-microphone technique, and uses resonance-free impedance loads to calibrate the system and spectral shaping to improve the precision at impedance extrema. The impedance spectra of the flute and clarinet are measured over a wide range of fingerings, yielding a comprehensive and accurate database. The impedance properties of single finger holes are measured using a related technique, and fitformulae are derived for the length corrections of closed finger holes for a typical range of hole sizes and lengths. The bore surface of wooden instruments can change over time with playing and this can affect the acoustic impedance, and therefore the playing quality. Such changes in acoustic impedance are explored using wooden test pipes. To account for the effect of a typical player on flute tuning, an empirical correction is determined from the measured tuning of both modern and classical flutes as played by several professional and semi-professional players. By combining the measured impedance database with the player effects and various results in the literature a mathematical model of the input impedance of flutes is developed and implemented in command-line programs written in the software language C. A user-friendly graphical interface is created using the flute impedance model for the purposes of flute acoustical design and analysis. The program calculates the tuning and other acoustical properties for any given geometry. The program is applied to a modern flute and a classical flute. The capabilities and limitations of the software are thereby illustrated and possible contributions of the program to contemporary flute design are explored.

This thesis represents the work that has been done by the author during his Master of Engineering Science candidature in the area of vibration control of flexible structures at the School of Mechanical Engineering, The University of Adelaide, between March 2003 and June 2004. The aim of this research is to further extend the application of the Spatial Control Approach for two-dimensional flexible structures for attenuating global structural vibration with the possible implication of reduction in noise radiation. The research was concentrated on a simply supported thin flexible plate, using piezoelectric ceramic materials as actuators and sensors. In this work, active controllers were designed for the purpose of controlling only the first five vibration modes (0-500Hz) of the plate. A spatial controller was designed to minimize the total energy of the spatially distributed signal, which is reflected by the spatial H2 norm of the transfer function from the disturbance signal to the vibration output at every point over the plate. This approach ensures the vibration contributed by all the in bandwidth (0-500 Hz) vibration modes is minimized, and hence is capable of minimizing vibration throughout the entire plate. Within the control framework, two cases were considered here; the case when the prior knowledge of the incoming disturbance in terms of reference signal is vailable and the case when it is not available. For the case when the reference signal is available, spatial feedforward controller was designed; whereas for the case when the reference signal is not available, spatial feedback controller was designed to attenuate the global disturbance. The effectiveness of spatial controllers was then compared with that of the standard point-wise controllers numerically and experimentally. The experimental results were found to reflect the numerical results, and the results demonstrated that spatial controllers are able to reduce the energy transfer from the disturbance to the structural output across the plate in a more uniform way than the point-wise controllers. The research work has demonstrated that spatial controller managed to minimize the global plate vibrations and noise radiation that were due to the first five modes. / Thesis (M.Eng.Sc.)--School of Mechanical Engineering, 2005.

Thermoacoustic engines convert thermal energy into acoustic energy with few or no moving parts, thus they require little maintenance, are highly reliable, and are inexpensive to produce. These traits make them attractive for applications in remote or portable power generation, where a linear alternator converts the acoustic power into electric power. Their primary application, however, is in driving thermoacoustic refrigerators, which use acoustic power to provide cooling at potentially cryogenic temperatures, also without moving parts. This dissertation examines the feasibility of a new type of thermoacoustic engine, where mean flow and an internal pulse combustion process replace the hot heat exchanger in a traditional closed cycle thermoacoustic engine, thereby eliminating the heat exchangers cost, inefficiency, and thermal expansion stresses. The theory developed in this work reveals that a large temperature difference must exist between the hot face of the regenerator and the hot combustion products flowing into it, and that much of the convective thermal energy input from the combustion process is converted into conductive and thermoacoustic losses in the regenerator. The development of the Thermoacoustic Pulse Combustion Engine, as described in this study, is designed to recover most of this lost thermal energy by routing the inlet pipes through the regenerator to preheat the combustion reactants. Further, the developed theory shows that the pulse combustion process has the potential to add up to 7% to the engines acoustic power output for an acoustic pressure ratio of 10%, with linearly increasing contributions for increasing acoustic pressure ratios. Computational modeling and optimization of the Thermoacoustic Pulse Combustion Engine yield thermal efficiencies of about 20% for atmospheric mean operating pressures, though higher mean engine pressures increase this efficiency considerably by increasing the acoustic power density relative to the thermal losses. However, permissible mean engine pressures are limited by the need to avoid fouling the regenerator with condensation of water vapor out of the cold combustion products. Despite lower acoustic power densities, the Thermoacoustic Pulse Combustion Engine is shown to be well suited to portable refrigeration and power generation applications, due to its reasonable efficiency and inherent simplicity and compactness.

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Comprehensive studies are required to understand the design of the performance halls in Turkish Early Republican Period. Acoustics, a significant parameter in performance hall design, has been chosen to contribute the studies. Three pioneers of the period, Resim Heykel Museum, K&uuml / &ccedil / &uuml / k Theatre and Opera Halls, are chosen as cases. The acoustical qualities of performance halls of Turkish Early Republican period in Ankara is studied in parallel to the acoustical design of performance halls in Europe which may reveal similarities in case halls. Detailed 3-D models of the halls for acoustical simulations based on the original design data have been prepared and results are to be compared with acoustically recognized halls in the world.

Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Rogers, P. H.; Committee Member: Ferri, A. A.; Committee Member: Ruzzene, M.; Committee Member: Smith, M. K.; Committee Member: Trivett, D.; Committee Member: Zinn, B. T. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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