| Human Bioresponse to Low-Frequency Underwater Sound |
02-Feb-2009 |
240 pages |
| Authors:
Mark F Hamilton; Sarah L Gourlie; Paul A Waters; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
 | A technical summary of work completed under contract N00014-06-1-0299, entitled Human Bioresponse to Low-Frequency Underwater Sound, is given. Preliminary research such as the development of two micromechanical models of lung tissue and the calculation of elastic constants based upon such models is described. Progress made in the development of a lumped-element model of the human body and its internal organs is discussed. Master's theses completed under this contract are attached. ... |
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| The GPS Toolkit: Open Source Clock Tools |
01-Dec-2008 |
21 pages |
| Authors:
Timothy J Craddock; Richard J Broderick; Colin P Petersen; Alex Hu; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The GPS Toolkit (GPSTk) is an open source software project sponsored by the Space and Geophysics Laboratory of Applied Research Laboratories, The University of Texas at Austin. The GPSTk provides processing and analysis tools for GPS data. Clock Tools, a recent addition to the GPSTk, allows for basic clock stability analyses. These Clock Tools are interoperable with other GPSTk programs, allowing clock analyses to be easily run alongside other GPS ... |
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| Advanced Mathematical Modeling of Sonar-Induced Bubble Growth and Coalescence in Humans and Marine Mammals |
01-Sep-2008 |
30 pages |
| Authors:
Yurii A Ilinskii; Preston S Wilson; Mark F Hamilton; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| For high gas supersaturation levels in liquids, on the order of 300% as predicted in capillaries of marine mammals following a series of dives, standard mathematical models of both static and rectified diffusion are found to underestimate the rate of bubble growth by 10%-20%. The discrepancy is demonstrated by comparing predictions based on existing mathematical models with direct numerical solutions of the differential equations for gas diffusion in the liquid ... |
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| Experimental Investigation of the Interaction of Electrothermal Plasmas with Solid Propellants |
14 SEP 2007 |
35 pages |
| Authors:
Philip L. Varghese; Noel T. Clemens; Michael D. Ryan; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| We report measurements of the interaction between plasma radiation and solid propellant. We made heat flux measurements of the electrothermal plasma jet impinging on a sensor mimicking a disk of propellant. We made planar laser-induced fluorescence images of NO, a JA2 decomposition product at the propellant surface. High speed video imaging of the propellant surface and scattering of ejected particles was used to study how the propellant surface evolves during ... |
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| Development and Testing of a Multiple Frequency Continuous Wave Radar for Target Detection and Classification |
MAR 2007 |
99 pages |
| Authors:
Robert L. Rogers; Michael G. Anderson; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This report presents the development of a multiple frequency continuous wave radar for target detection and classification. The radar design incorporates specifications germane to both basic research and personnel detection applications. An extensive database of radar signatures is collected, processed, and analyzed. The radar signataure database contains data from human, vehicle and animal subjects. The subjects undergo significant variation in velocity, range, approach angle, and posture to represent potential operational ... |
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| Review of the Current Status of Four-Dimensional Ionospheric Imaging |
JUN 2006 |
19 pages |
| Authors:
G. S. Bust; C. N. Mitchell; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Recent developments in tomographic imaging allow the use of GPS satellite data to image the Earth's ionosphere. Ground-based GPS receivers monitor the Earth's ionosphere continuously and a comprehensive database of ionospheric measurements suitable for tomographic processing now exists. The tomographic inversion of these GPS data in a three-dimensional time-dependent inversion algorithm can reveal the spatial and temporal distribution of ionospheric electron density. This new technique is unique for studying ionospheric ... |
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| Incorporating Digisonde Traces into the Ionospheric Data Assimilation Three Dimensional (IDA3D) Algorithm |
11 MAY 2006 |
8 pages |
| Authors:
Trevor W. Garner; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This study incorporated virtual height traces measured by ionosondes directly into an objective analysis (OA) algorithm. The OA algorithms ingest available data sets to construct coherent maps that represent the larger scale behavior of the ionosphere. A forward model which calculates the virtual height profile form a given electron density distribution was developed and incorporated into the Ionospheric Data Assimilation Three Dimensional (IDA3D) OA algorithm. In addition, IDA3D was modified ... |
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| Additional Mine Classification Capabilities for the INSS |
10 SEP 2003 |
64 pages |
| Authors:
Min F. Chang; Charles M. Loeffler; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| As a diver scans shallow water or very shallow water (SW/VSW) area with an INSS high frequency sonar, many objects may be detected or imaged in the scene. The objective of this project is to develop algorithms that capture the broadband echo responses from these objects detected by the INSS and extract special echo features to assist in target discrimination from the background. The algorithms are based upon geometric acoustics, ... |
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| Diver Charting and Graphical Display |
05 MAY 2003 |
11 pages |
| Authors:
Kenneth L. Krueger; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The Diver Charting and Graphical Display (DCGD) software application was developed as a mission planning and data analysis tool for divers using an Integrated Navigation Sonar Sensor (INSS). It is a Microsoft Windows based graphical user interface application that can be installed and executed on computers using a Microsoft Windows based operating systems. The need and usefulness of this tool becomes apparent when one understands what is required to plan, ... |
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| A Progress Report on the Estimation of Geoacoustic Parameters from Measured Time Series Taken During the East China Sea Component of ASIAEX |
OCT 2002 |
20 pages |
| Authors:
D. P. Knobles; T. W. Yudichak; P. G. Cable; Y. Dorfman; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Viewgraphs from a progress report on the estimation of geoacoustic parameters from measured time series taken during the East China Sea component of ASIAEX. |
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| Clandestine ELOS/OTH RF Communications for Unmanned Underwater Vehicles |
30 SEP 2002 |
7 pages |
| Authors:
Robert L. Rogers; Dillon P. Buhl; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This is a proposal to assess and develop critical technology for clandestine radio frequency communication systems for underwater autonomous vehicles (UAVs). Under a previous ONR grant, the Applied Research Laboratories at the University of Texas at Austin developed and tested a preliminary design for a wire antenna. Assessments were made of data rates, propagation effects, and overall system impacts for a wide variety of communication methods. The long term goal ... |
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| Broadband, Range-Dependent Normal Mode Model Development |
09 JUL 2002 |
18 pages |
| Authors:
Evan K. Westwood; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Practical approaches to modeling broadband acoustic propagation in range-dependent environments using normal mode theory were developed. A method for eliminating the branch line integral from the normal mode solution was developed, analyzed, and documented in a JASA article. The accuracy and characteristics of various adiabatic- and coupled-mode approaches for range- dependent benchmark problems were investigated. A method for extracting the acoustic modes of propagation and inverting for the acoustic parameters ... |
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| Very High Resolution Imaging Diver Held Sonar |
26 JUN 2002 |
7 pages |
| Authors:
Keith Lent; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| New fixed focal length transducers were developed for the INSS (integrated Navigation and Sensor System) diver held sonar which allows a VSW diver to obtain a very high resolution sonar image (with approximately 1 in. by 1 in. resolution at a range of 15 ft) and to obtain a lower resolution image of buried targets. With these new focused transducers (which will replace the existing INSS transducer) the diver should ... |
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| Non-Lethal Swimmer Neutralization Study |
MAY 2002 |
79 pages |
| Authors:
Karl W. Rehn; Penny K. Riggs; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The Applied Research Laboratories, The University of Texas at Austin (ARL: UT) was tasked to study the means and equipment for non-lethal methods to deter swimmers and scuba divers from restricted areas. This work included identification and evaluation of existing technologies, as well as review of research in security, acoustics, biology, and other fields. Various technologies have been developed as non-lethal weapons for law enforcement, but most of them are ... |
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| Estimation of Receiver Operating Characteristic Curves for Multiping Mine Detection Using Empirical Target Data |
14 MAR 2002 |
40 pages |
| Authors:
Petre I. Rusu; S. P. Pitt; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This report develops the formalism for computing receiver operating characteristic (ROC) curves for an active sonar detector, consisting of linear receiver processing followed by a linear envelope detector. The formalism is applicable to both single-ping and multiple-ping detection. The methodology for computing the ROC curves directly incorporates measurements of target strength as a function of aspect angle to estimate the requisite signal-plus-noise probability density function (pdf) under the assumption of ... |
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| ONR Basic Research Program: Summary and Bibliographies |
15 JAN 2002 |
|
| Authors:
Gary R. Wilson; Elaine C. Frazer; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
 | The Office of Naval Research (ONR) sponsored the Basic Research Program, a discretionary grant program for the purpose of giving university laboratory directors freedom to develop and apply their resources to basic research problems of naval relevance, which might not be known or appreciated by others in the community. Program guidelines included (1) involvement of students and faculty and (2) initiation of research in areas that could transition into either ... |
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| ADS MNT and FET: Array Element Localization Analysis and Results |
13 MAR 2000 |
102 pages |
| Authors:
Peter E. McCarty; Marton I. Garay; Mary R. Parse; Russell E. Henrichs; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Accurate array element localization (AEL) is an important component of optimizing the detection performance of bottom-mounted acoustic arrays. Use of the nominal element positions can lead to significant degradations in beamforming performance when the array has been subject to real-world deployment methods. Methods of accurately estimating array element positions using both overt and covert methods have been developed by the Advanced Deployable System (ADS) program, and were used during the ... |
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| Subband Energy Detection in Passive Array Processing |
2000 |
6 pages |
| Authors:
Michael Bono; Ben Shapo; Pete McCarty; Roy Bethel; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Broadband processing is an important part of the Navy's current and future SONAR systems. This paper provides an introduction to a new class of passive broadband processing algorithms, Subband Energy Detection (SED), which includes both Subband Peak Energy Detection (SPED) and Subband Extrema Energy Detection (SEED). It will be shown that SED has several performance advantages over Conventional Energy Detection (CED), also known as Linear Rectify (LR). SED exploits the ... |
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| Plasma Sound Source Basic Research |
01 JUL 1999 |
113 pages |
| Authors:
Robert L. Rogers; James C. Espinosa; David L. Fisher; Austin M. Gleeson; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This report investigates the phenomena of breakdown and initial arc formation of a plasma sound source. The prebreakdown phase is examined experimentally. A proton-hopping model is proposed that is qualitatively consistent with the data. A literature review of the behavior of water near electrodes shows water having a regular, solid-like structure, permitting use of proton-hopping models to calculate specifics of ion transport in the electrode ... |
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| ONR Basic Research Program: Summary and Bibliographies |
08 JAN 1999 |
47 pages |
| Authors:
Gary R. Wilson; Elaine C. Frazer; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The Office of Naval Research (ONR) sponsored the Basic Research Program, a discretionary grant program for the purpose of giving university laboratory directors freedom to develop and apply their resources to basic research problems of naval relevance, which might not be known or appreciated by others in the community. Program guidelines included (1) involvement of students and faculty and (2) initiation of research in areas that could transition into either ... |
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| Acoustic Localization and Decay of the Incoherent Impulse Response |
02 NOV 1998 |
6 pages |
| Authors:
Eric Smith; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Applied Research Laboratories, The University of Texas at Austin (ARL:UT) was tasked to study the effects of strong random scattering in acoustic media with macroscopically non-uniform scattering strengths. A statistical, field- theoretic method, previously applied in condensed matter physics and seismology, was introduced to study these effects analytically. Non-uniform random scattering was found to produce phenomena closely related to acoustic localization, which results from uniform ... |
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| Analysis of Sea Surface Patterns |
31 AUG 1998 |
7 pages |
| Authors:
Andrew C. Vastano; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This Navy Grant supports research focused on sea surface flow regimes and their analyses. The objective is establishment of an ongoing archive that is gathered from remotely sensed imagery and drifter trajectories, and applied in studies of circulation on the Texas Louisiana Shelf (TLS). The geographic location has been chosen because of the wealth of archival, coincident in situ Eulerian current meter, Lagrangian drifter, and hydrographic observations, as well as ... |
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| Test and Development of High Data Rate Millimeter Wave Data Links Over Low Elevation Paths for Physical Security Systems |
02 JUL 1998 |
237 pages |
| Authors:
Robert L. Rogers; Matthew A. Koerner; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This report documents testing of a millimeter wave data link for its applicability to physical security systems. Propagation measurements were made at 27.3 GHz and 60 GHz. The feasibility of using these data links for high speed (1.5 Mbps tested) data transmission over low elevation transmission paths was established. Tests were conducted at Eglin Air Force Base (AFB), Davis Monthan AFB, and Minot AFB. The longest path over land tested ... |
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| Multiple Scatter Theory of Ocean Sediments II |
16 JAN 98 |
48 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| It is postulated that a laminar sand bed may be modeled as an ensemble of randomly layered poroelastic material. The thickness of each layer was related to the associated grain size and porosity by a conservation of mass relationship. The effect of lateral variations in grain size were simulated by performing a coherent ensemble average of results from several realizations of the randomly stratified medium. Poroelastic medium parameters were chosen ... |
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| ONR Basic Research Program: Summary and Bibliographies |
09 JAN 1998 |
25 pages |
| Authors:
Thomas G. Muir; Elaine C. Frazar; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The Office of Naval Research (ONR) sponsored the Basic Research Program, a discretionary grant program for the purpose of giving university laboratory directors freedom to develop and apply their resources to basic research problems of naval relevance, which might not be known or appreciated by others in the community. Program guidelines included: (1) involvement of students and faculty, and (2) initiation of research in areas that could transition into either ... |
|
| High Frequency Buried Target Imaging |
06 OCT 97 |
27 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Acoustical imaging can potentially provide a buried object classification capability. The image quality is expected to be a function of sediment type, burial depth, and grazing angle. Image degradation is caused by propagation and scattering processes that can be modeled and experimentally measured. Three physical mechanisms were investigated: ghosting, warping, and fogging. Fogging, caused by backscattering from the sediment, is expected to be the limiting factor. A laboratory experiment was ... |
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| Continuation of Signal Detection Using Polyspectra; 1 June 1991 - 31 March 1997 |
01 OCT 97 |
5 pages |
| Authors:
Melvin J. Hinich; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Two methods have been developed for detecting and classifying transient signals in a noise background. One uses the third order portmanteau test I presented in "Testing for Dependence in the Input to a Linear Time Series Model," Journal of Nonparametric Statistics (1996). The test statistic is a sum of squared bicorrelations where the number of lags used is a function of the sample size. A FORTRAN program that has been ... |
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| Sediment Penetration of Underwater Mammalian Sonar Signals |
10 SEP 97 |
10 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The adopted approach for characterization of buried target detection by underwater mammalian sonars, as represented by the sonar of tursiops truncatus has three components: (1) direct measurement and analysis of acoustic signals incident on buried targets; (2) construction of acoustic penetration and target scattering model; and (3) deduction of detection and classification methods through reproduction of target insonification processes. It has been two years since the start of the project, ... |
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| Environmental Data from UUV Systems and Purple Star |
17 JUN 97 |
25 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This is a progress report for the first year of work on bottom classification using tactical sensors. Data from a TVSS experiment in 1994, at deep and shallow sites, were provided by CSS and distributed by NRL/SSC. The data were processed and analyzed to provide calibration in a self-consistent manner and then to compute the magnitude of the normal incidence bottom reflection coefficient, which was then used to estimate bottom ... |
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| Feasibility of Bottom Classification with the Toroidal Volume Search Sonar (TVSS) |
17 JUN 1997 |
23 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This is a progress report for the first year of work on bottom classification using tactical sensors. Data from a TVSS experiment in 1994, at deep and shallow sites, were provided by CSS and distributed by NRL/SSC. The data were processed and analyzed to provide calibration in a self-consistent manner and then to compute the magnitude of the normal incidence bottom reflection coefficient, which was then used to estimate bottom ... |
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| Development and Tests of a Low Cost Passive Millimeter Wave Sensor |
15 APR 97 |
99 pages |
| Authors:
Robert L. Rogers; David L. Fisher; Heinrich D. Foltz; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This report describes an effort to develop and test a passive millimeter wave (PMMW) sensor for application as a physical security sensor. It also describes the successful implementation of a total power radiometer at 27. 7-GHz center frequency as the sensor. The sensor that was demonstrated was completely fabricated from printed circuit board components. The architecture of the down converter was coplanar waveguide. This means that no via-holes were required ... |
|
| ONR Basic Research Program: Summary and Bibliographies |
02 APR 97 |
30 pages |
| Authors:
Thomas G. Muir; Elaine C. Frazer; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The Office of Naval Research (ONR) sponsored the Basic Research Program, a discretionary grant program for the purpose of giving university laboratory directors freedom to develop and apply their resources to basic research problems of naval relevance, which might not be known or appreciated by others in the community. Program guidelines included (1) involvement of students and faculty and (2) initiation of research in areas that could transition into either ... |
|
| Control of Acoustic Cavitation with Application to Lithotripsy |
03 MAR 97 |
221 pages |
| Authors:
Michael R. Bailey; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Control of acoustic cavitation (sound-induced bubble activity) is the subject of this dissertation. Application is to clinical lithotripsy where cavitation contributes to kidney stone comminution and tissue damage. An electrical spark at the near focus of an underwater ellipsoidal reflector was the acoustical source, as in the Dornier HM3 lithotripter. Experiments were done with rigid reflectors, pressure-release reflectors, and pairs of reflectors sharing a common focus and a controlled delay ... |
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| Plasma Sound Source Basic Research |
12 DEC 96 |
11 pages |
| Authors:
Robert L. Rogers; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| This research focuses on the problem of understanding the mechanisms by which the underwater spark is generated and the delivery of electrical energy to the arc load and ultimately the acoustic signal. Recent progress in numerical simulations of arc-generated bubbles in water show good agreement with experimental observations. The arc formation and dielectric breakdown of the water at moderate field strengths have been modeled with a fractal object. Good agreement ... |
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| Sediment Penetration of Underwater Mammalian Sonar Signals |
13 JUN 96 |
11 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The objective is characterization of buried target detection by underwater mammalian sonars. To this end, a collaboration has been formed between Applied Research Laboratories, The University of Texas at Austin (AflL:UT) and Naval Command, Control and Ocean Surveillance Center (NRaD), San Diego. ARL:UT brings expertise in the modeling of sediment acoustics, and signal processing. NRaD possesses extensive experience in the training of mammals to locate buried objects, as well as ... |
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| Bottom Grain Gas and Roughness Technique (BOGGART) Version 3.0: Bottom Backscatter Model User's Guide |
04 JUN 96 |
46 pages |
| Authors:
Frank A. Boyle; Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| A user's guide has been developed for BOGGART, a model for acoustic backscatter from marine sediments, developed at Applied Research Laboratories, The University of Texas at Austin (ARL:UT), with support from the Naval Research Laboratory at Stennis Space Center (NRL/SSC). The model, named for bottom grain gas and roughness technique, computes the total backscattering strength as an incoherent sum of contributions from three components. They are (1) scattering from sediment ... |
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| Nonlinear Acoustics Research |
21 MAR 96 |
44 pages |
| Authors:
David T. Blackstock; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Research on nonlinear acoustics was carried out during the period 1 August 1984-31 December 1995. Most of the work was done as masters and doctoral research projects in one of the following general areas: nonlinear ocean acoustics; propagation; reflection, refraction, interaction, and scattering; medical ultrasonics; and miscellaneous. The research led to five master's degrees and five doctorates (including one in progress at the end of the grant) among seven students. ... |
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| Multiple Scatter Theory of Ocean Sediments II |
FEB 96 |
5 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The long term goals are to develop a new model of acoustic bottom backscatter from sandy sediments, based on a multiple scattering theory approach, and hence, properly explain observed phenomena, including Lambert's rule and frequency dependence of backscattering strength, particularly at shallow grazing angles, for which current theories are at a loss. |
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| Evaluation of the Dominant Mode Rejection Beamformer |
11 JAN 96 |
109 pages |
| Authors:
Tina R. Messerschmitt; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Increasing the number of hydrophones in an array should increase beamformer performance. However, when the number of hydrophones is large, integration times must be long enough to give accurate cross spectral matrix (CSM) estimates, but short enough so that the dynamic behavior of the noise described by the CSM is captured. The dominant mode rejection (DMR) beamformer calculates adaptive weights based on a reduced rank CSM estimate, where the CSM ... |
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| Backscatter Analysis from a Smooth Sand Surface: Diffusion Approximation |
26 OCT 95 |
46 pages |
| Authors:
Nicholas P. Chotiros; Adrienne M. Mautner; Julia Laughlin; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The development of a model of backscatter from a smooth underwater sediment surface is described. The model includes two components: the propagation of acoustic energy through the water/sediment interface which is governed by wave theory, and randomization of acoustic energy within the interior of the sediment which is approximated by the diffusion equation. With respect to the wave theory, Biot's poroelastic wave propagation theory is used. The model gives predictions ... |
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| Sediment Classification and Bathymetry Data Acquired from the AN/UQN-4 Depth Sounder in Support of MTEDS |
25 OCT 95 |
55 pages |
| Authors:
Robert A. Altenburg; Karl W. Rehnn; Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| A realtime system for the measurement of the bottom reflection coefficient using the AN/UQN-4 depth sounder was developed. Data provided by the system is transferred to the MTEDS database system where it is made available to the Acoustic Sediment Classification System (ASCS). In addition to the bottom reflection coefficient, the system also provides time and ship's position from a built-in GPS receiver, and depth data for the MTEDS database. Three ... |
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| Bottom Grain Gas and Roughness Technique (BOGGART) Version 1.0: Bottom Backscatter Model User's Guide |
02 OCT 95 |
42 pages |
| Authors:
Frank A. Boyle; Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| A use's guide for ARL:UT's marine sediment acoustic backscatter model has been developed. The model, named BOGGART (Bottom Grain Gas and Roughness Technique), is a three-component model which computes the total backscattering strength as an incoherent sum of contributions from three components. They are (1) scattering from sediment grains, (2) scattering from trapped gas bubbles within the sediment, and (3) scattering from interface roughness. The grain scattering is modeled empirically ... |
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| Scattering of a Transient Plane Compression Wave by a Spherical Inclusion in a Biot Medium |
OCT 95 |
45 pages |
| Authors:
Dennis J. Yelton; Morris Stern; Hans G. Schantz; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The scattering of an arbitrary transient plane wave by a spherical inclusion in a Biot medium is modeled, by applying the single frequency steady state solution of Zimmerman and Stern to the discrete Fourier components of the transient signal, and assuming linear superposition. The solution of Zimmerman and Stem is an analytical series solution. Its accuracy is mainly determined by computation errors and the convergence of the series. The incident ... |
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| New Multiple Scatter Model of the Ocean Sediment |
15 SEP 95 |
66 pages |
| Authors:
Dennis J. Yelton; Morris Stern; Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The reflection and scattering properties of an in homogeneous poroelastic medium were studied via numerical simulation. The inhomogeneous medium was modeled as an ensemble average of randomly layered poroelastic material. Each layer represented a granular material of a particular grain size. The thickness of each layer was related to the associated grain size and porosity by a conservation of mass relationship. Lateral variations in grain size were approximated by performing ... |
|
| Bottom Scattering Strength Measurement and Analysis |
14 SEP 95 |
3 pages |
| Authors:
Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Collection of high frequency reverberation data from shallow water sediment, particularly coral and mud sediments for measurement on spatial backscatter statistics, using sensors mounted on a tripod on the bottom and on a ROV, in support of high frequency sonar imaging applications and sediment classification. |
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| Bistatic Scattering and Depth Dependent Gas Fractions in the Acoustic Modeling of Gassy Sediment |
07 SEP 95 |
37 pages |
| Authors:
Frank A. Boyle; Nicholas P. Chotiros; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| A model for acoustic scattering from the seabed was previously developed by Boyle and Chotiros (ARL-TR-93-15, 'Bottom Backscatter from Trapped Bubbles' and ARL-TR-94-21, 'Bottom Backscatter from Trapped Bubbles II'). The model treats acoustic scattering as a sum of three independent processes, including scattering from the sediment interface, volume scattering from sediment grains, and volume scattering from trapped gas bubbles that might exist between grains. Recently the gas bubble component of ... |
|
| Surface Backscattering |
29 AUG 95 |
117 pages |
| Authors:
Hollis Boehme; Walter M. Amos; Rick S. Bailey; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Surface and near surface acoustic backscatter measurements at 108, 72, 36, and 18 kHz made off the coast of Fort Lauderdale, Florida, have been analyzed and the results are presented in this report. The measurements were made with bottom mounted equipment looking upward at the ocean surface; wind speeds encountered varied from about 2.5 to about 16 m/s. Vertical incidence acoustic measurements were used to evaluate near surface volume backscatter ... |
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| Nonlinear Acoustics: Self-Refraction in the Field of a Paraboloidal Reflector and Two-Ellipsoid System to Enhance Cavitation Collapse |
15 AUG 95 |
36 pages |
| Authors:
David T. Blackstock; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Research on nonlinear acoustics has been performed during the 12- month period ending 30 September 1995. Progress is reported on the following projects: (1) Self-refraction in the field of a paraboloidal reflector (experimental), and (2) Two-ellipsoid system to enhance cavitation collapse (experimental). Public communication of the research includes one thesis, one oral paper, two journal articles submitted, and two technical reports. |
|
| Nonlinear Acoustics: Production of an Isolated Negative Pulse in Water, Self-Refraction in the Field of a Paraboloidal Reflector, and Preliminary Study of the Acoustitron |
08 AUG 95 |
36 pages |
| Authors:
David T. Blackstock; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| Research on nonlinear acoustics has been performed during the 12- month period ending 30 September 1994. Progress is reported on the following projects: (1) Production of an isolated negative pulse in water (experimental); (2) Self-refraction in the field of a paraboloidal reflector (experimental); (3) Preliminary study of the acoustitron (theoretical). Public communication of the research includes one thesis, two oral papers, two journal articles published, three journal articles submitted, and ... |
|
| Physics of Buried Mine Detection and Classification |
12 MAY 95 |
15 pages |
| Authors:
Nicholas P. Chotiros; Thomas G. Muir; D. E. Smith; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| The physics of buried mine detection in offshore sediments and in the surf zone was investigated. Optical techniques are useless because they cannot penetrate sediments while magnetic techniques are of low value because of low resolution, short range, and the introduction of non-magnetic mines. For buried mine detection in the off-shore sediment acoustic penetration at shallow grazing angles was explored. An experiment was conducted jointly with SACLANTCEN to measure sound ... |
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