Recent studies have shown that the presence of sand ripples on the seabed improves sonar detection of buried mines at sub-critical angles. Sidescan sonar data of ripples off on the west Florida shelf were collected as part of ONR's Ripples Departmental Research Initiative (DRI) September 26-29th and November 7-9th, 2004. Hurricane Ivan, the strongest storm of the 2004 hurricane season, passed over the experiment site a week before the first data collection. This study focuses on the ripples created by Ivan. Average relict ripple wavelengths left after the storm were found to increase with water depth (50 cm, 62 cm, and 83 cm in 20, 30, and 50 meter water depths) despite the fact that orbital diameter decreases with water depth. Ripple prediction requires information about surface gravity waves and sediment grain size. The most reliable offshore wave field available was created with Wavewatch III by Naval Postgraduate School scientists. These waves were inputted into Delft3D WAVE, incorporating the nearshore wave model SWAN to predict waves at the locations where ripples were measured. Orbital motions at the seabed and grain size were inputted into a time-dependent ripple model with varying dissipation parameters to estimate sand ripples created by Hurricane Ivan. Ripple wavelength was found to be more strongly dependent on grain size than wave dissipation. / Contract number: N62271-97-G-0026. / US Navy (USN) author.

No description available.

Bibliography: p. 283-311. / xxii, 311 p. : ill. (some col.), photos (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Mechanical Engineering, 2004

<p>In this work we have studied energy flow in acoustic billiards, focusing on irregular billiards with and without current effects. The open systems were modeled with an imaginary potential as a source and drain. We have used the finite difference method to model the billiards. General features of the systems are reported and effects of the measuring probe on the wave function are discussed.</p>

No description available.

In this work we have studied energy flow in acoustic billiards, focusing on irregular billiards with and without current effects. The open systems were modeled with an imaginary potential as a source and drain. We have used the finite difference method to model the billiards. General features of the systems are reported and effects of the measuring probe on the wave function are discussed.

With the popularity of golfing, the marketing of golf clubs has been promoted in recent years. The purpose of this study is to investigate the sound effects of golf impact on different shapes and thicknesses of striking face of the golf club using the finite element method. The researcher found that the vibration model and the resonance frequency of golf club heads. In addition, the researcher used vibration modal analysis to generalize the golf head modes with the distribution of the sound pressure. He also used acoustic transient analysis to check the sound pressure level. Finally, the correlations among the sound pressure, sound pressure level and sound frequency of the golf club head impacts were administered. After all, the study findings provides golf head designers and producers with a reference for designing, revising and producing comfortable and qualified impact sounds of golf club heads.

Among communication filters, SAW Filters have been largely used in RF and IF filters of mobile phone because of their small size, high reliability, and the capability to be mass produced. But with increasing of working frequency and miniaturization of SAW package, SAW filters are more sensitive to interference introduced by the package and SAW Pattern. Discrepancy in performance between design and measurement can be large if the packaging effects are not considered. In this thesis, we use the full wave analysis approach that combining full wave simulator HFSS (High Frequency Structure Simulator) with circuit software to simulate the package effects and the electromagnetic effects of SAW pattern. Our approach has been applied to several cases and measurements are also carried out to verify our results. Good agreements are obtained. We also use this method to discuss the electromagnetic effects inside package, such as the change of the bond wire length. With an accurate prediction, we can save factory design time and production cost.

Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): Charles W. Therrien, Murali Tummala. Includes bibliographical references (p. 83-84). Also available online.

Thesis (M.S. in A.E.)--School of Aerospace Engineering, Georgia Institute of Technology, 2004. Directed by Tim Lieuwen. / Includes bibliographical references (leaves 39-41).