Inversions of statistical parameters of an acoustic signal in range-dependent environments with applications in ocean acoustic tomography

The paper presents an application of a method for the characterization of underwater acoustic signals based on the statistics of their wavelet transform sub-band coefficients in range-dependent environments. As it was illustrated in previous works, this statistical characterization scheme is a very efficient tool for obtaining observables to be exploited in problems of ocean acoustic tomography and geoacoustic inversion, when range-independent environments are considered. Now the scheme is applied in range-dependent environments for the estimation of range-dependent features in shallow water. A simple denoising strategy, also presented in the paper, is shown to enhance the quality of the inversion results, as it helps to keep the signal characterization to the energy significant part of it. The results presented for typical test cases are encouraging and indicative of the potential of the method for the treatment of inverse problems in acoustical oceanography

Digital Signal Processing Group

Contains an introduction and reports on nineteen research projects.U.S. Navy - Office of Naval Research (Contract N00014-77-C-0266)U.S. Navy - Office of Naval Research (Contract N00014-81-K-0742)National Science Foundation (Grant ECS80-07102)Bell Laboratories FellowshipAmoco Foundation FellowshipU.S. Navy - Office of Naval Research (Contract N00014-77-C-0196)Schlumberger-Doll Research Center FellowshipToshiba Company FellowshipVinton Hayes FellowshipHertz Foundation Fellowshi

A survey on inverse problems for applied sciences

The aim of this paper is to introduce inversion-based engineering applications and to investigate some of the important ones from mathematical point of view. To do this we employ acoustic, electromagnetic, and elastic waves for presenting different types of inverse problems. More specifically, we first study location, shape, and boundary parameter reconstruction algorithms for the inaccessible targets in acoustics. The inverse problems for the time-dependent differential equations of isotropic and anisotropic elasticity are reviewed in the following section of the paper. These problems were the objects of the study by many authors in the last several decades. The physical interpretations for almost all of these problems are given, and the geophysical applications for some of them are described. In our last section, an introduction with many links into the literature is given for modern algorithms which combine techniques from classical inverse problems with stochastic tools into ensemble methods both for data assimilation as well as for forecasting

Digital Signal Processing Research Program

Contains table of contents for Section 2, an introduction and reports on seventeen research projects.U.S. Navy - Office of Naval Research Grant N00014-91-J-1628Vertical Arrays for the Heard Island Experiment Award No. SC 48548Charles S. Draper Laboratories, Inc. Contract DL-H-418472Defense Advanced Research Projects Agency/U.S. Navy - Office of Naval Research Grant N00014-89-J-1489Rockwell Corporation Doctoral FellowshipMIT - Woods Hole Oceanographic Institution Joint ProgramDefense Advanced Research Projects Agency/U.S. Navy - Office of Naval Research Grant N00014-90-J-1109Lockheed Sanders, Inc./U.S. Navy - Office of Naval Research Contract N00014-91-C-0125U.S. Air Force - Office of Scientific Research Grant AFOSR-91-0034AT&T Laboratories Doctoral ProgramU.S. Navy - Office of Naval Research Grant N00014-91-J-1628General Electric Foundation Graduate Fellowship in Electrical EngineeringNational Science Foundation Grant MIP 87-14969National Science Foundation Graduate FellowshipCanada Natural Sciences and Engineering Research CouncilLockheed Sanders, Inc

Applications on Ultrasonic Wave

This book presents applications on the ultrasonic wave for material characterization and nondestructive evaluations. It could be of interest to the researchers and students who are studying on the fields of ultrasonic waves

Flow velocity mapping in a circular experimental wave/current basin with small scale underwater acoustic tomography method

Several researches normally use the rectangle tank for ocean device testing in laboratory trails. Rectangle experimental tanks, however, can only generate normalized flow in one or some fixed directions with limited testing area. Meanwhile, the appearance of the flow will be in large extent affected by boundary. This thesis study flow details in a 25m diameter circular testing facility Flowave TT, which can generate combined wave and current in any relative direction. The spatial of flow current velocity obtained by fixed point direct measurement is insufficient if the quantity of test points is not enough. Acoustic tomography is used here for flow internal structure visualizing in the experimental basin by transmitting sound wave with acoustic transducer. Using acoustic tomography method, one could get real-time mapping of parameter variation by installing detect devices outside or at the boundary of interested region without interrupting original field. Two sets of underwater acoustic tomography system that developed in cooperation with Hiroshima University were used for sound wave emitting and acoustic signal receiving. Travel time of acoustic signal in the interested region is analysed to reconstruct flow velocity by solving inverse problems. Multi-path arrivals that propagated by different ray paths are identified by ray tracing. Flow details in the circular basin is studied in a horizontal plane and along a vertical slice using acoustic method. Besides acoustic tomography experiments in the Flowave, a field work was conducted in the Bali Strait, Indonesia. This trail explores the remote sensing of tide progress in the Bali strait with coastal acoustic tomography systems. This study is for the first time to conduct multi-station acoustic tomography experiment for flow velocity reconstructing with only two stations. This study demonstrates that small scale flow profiles in the experimental tank can be reconstructed with acoustic tomography method. The real time monitoring of small-scale flow details can be accomplished with multi-station network, which is one of the further research topics for small scale underwater acoustic tomography research