| SAR Remote Sensing Algorithms for Automated Extraction of Sea Ice Ridges and Leads |
AUG 97 |
56 pages |
| Authors:
John F. Vesecky; MICHIGAN UNIV ANN ARBOR DEPT OF ATMOSPHERIC AND OCEANIC SCIENCE
|
 | Sea ice is of fundamental importance in weather, climate and other geophysical processes. It is also an important factor for naval operations in the polar regions, in particular regarding transport of personnel and material in regions where sea ice is likely to be found and assessment and prediction of acoustic environments in polar regions. Ridges (and keels) in sea ice are important because they provide a rougher surface and thus ... |
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| Defense Base Realignment and Closure Budget Data for the Realignment of Naval Surface Warfare Center Annapolis, Maryland, To Naval Surface Warfare Center Philadelphia, Pennsylvania |
01 JUL 1997 |
27 pages |
| Authors:
Paul J. Granetto; Wayne K. Million; Nicholas E. Como; Tonya M. Dean; INSPECTOR GENERAL DEPT OF DEFENSE ARLINGTON VA
|
| The overall audit objective was to determine the accuracy of Defense base realignment and closure military construction budget data. This report provides the results of the audit of two projects, valued at $11.2 million, for the closure of Naval Surface Warfare Center Annapolis, Maryland, and realignment of the acoustics and electrical power systems facilities to Naval Surface Warfare Center Philadelphia, Pennsylvania. |
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| Behavioral Responses and Temporary Shift in Masked Hearing Threshold of Bottlenose Dolphins, Tursiops truncatus, to 1-second Tones of 141 to 201 dB re 1 Micron Pa |
JUL 1997 |
37 pages |
| Authors:
Sam H. Ridgway; Donald A. Carter; Robert R. Smith; Tricia Kamolnick; Carolyn E. Schlundt; NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
|
| The Navy is concerned that acoustic energy emissions from various products may interfere with marine mammals. Proposed federal regulations under the Marine Mammal Protection Act discuss temporary threshold shift (TTS) as a means of evaluating impacts of those emissions. Existing Navy methods published in the Journal of the Acoustical Society of America were applied to investigate TTS in the hearing sensitivity of bottlenose dolphins (Tursiops truncatus). Changes in the dolphins' ... |
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| Method for Doubling the Resolving Power of a Sonar Array and a Sonar Array for Implementing the Same. |
24 JUN 1997 |
|
| Authors:
William J. Zehner; DEPARTMENT OF THE NAVY WASHINGTON DC
|
 | A sonar array which has a resolving power which is double that of conventional sonar arrays includes an array of hydrophones each having an acoustic center, a first projector positioned proximate a first endmost one of the hydrophones for launching a first sound signal during a first transmission time period, a second projector positioned proximate a second endmost one of the hydrophones for launching a second sound signal during a ... |
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| Innovative Acoustic Techniques for Studying New Materials and New Developments in Solid State Physics |
06 JUN 1997 |
16 pages |
| Authors:
Julian D. Maynard; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF PHYSICS
|
| The goals of this project involve the use of innovative acoustic techniques to study new materials and new developments in solid state physics. Major accomplishments include (a) the publication of two book chapters and three papers, including one in the prestigious Journal Appl. Phys. Lett. on the measurement of the elastic constants of titanium diboride using resonant ultrasound spectroscopy (RUS); (b) the successful completion of the Ph.D. degree for Philip ... |
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| Elastic Properties of Novel Materials Using PVDF Film and Resonance Ultrasound Spectroscopy |
06 JUN 1997 |
120 pages |
| Authors:
Philip S. Spoor; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF PHYSICS
|
| Elastic properties are of fundamental interest in condensed matter physics, material science, geoscience, and many branches of engineering. This paper describes the use of a relatively new technique, known as 'Resonant Ultrasound Spectroscopy' (RUS), with which the elastic properties of a small sample may be found in a single measurement, by analyzing a sufficient number of the sample's normal modes of free vibration. The present work describes the use of ... |
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| Acoustic Casimir Effect |
JUN 97 |
45 pages |
| Authors:
Christopher David Homes; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| In 1948, Hendrick Brugt Gerhard Casimir predicted that two closely spaced uncharged conducting plates in vacuum would be mutually attracted. This attractive force is an indirect manifestation of the quantum electromagnetic zero point field (ZPF). When the indirect manifestations of the ZPF are interpreted as due to radiation pressure, acoustic noise can provide an excellent analog to investigate the Casimir effect as well as other effects due to the ZPF. ... |
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| Sonic Nozzles for Mass Flow Measurement and Reference Nozzles for Thrust Verification (Les Tuyeres Soniques Pour le Controle du Debit Massiquie et les Tuyeres de Reference Pour la Verification de la Poussee) |
JUN 97 |
|
| Authors:
ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRAN CE)
|
| Accurate measurement of massflow and thrust is essential to the success of windtunnel tests supporting engine-airframe aerodynamic integration studies. Among other benefits, optimising engine integration results into reductions of the cruise drag of an aircraft by at least several percent. Hence, mastering this technique at an early stage of a project allows, within a given set of specification (e.g. the range), to save on the mass of the aircraft and ... |
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| Micromachined Ultrasonic Transducers |
JUN 97 |
7 pages |
| Authors:
B. T. Khuri-Yakub; STANFORD UNIV CA EDWARD L GINZTON LAB OF PHYSICS
|
| Microfabricated ultrasonic transducers have been generated which operate in both liquids and gases. Air coupled through transmission of aluminum was observed for the first time using a pair of 2.3 MHz transducers. The dynamic range of the transducers was 110 dB, and the received signal had an SNR of 30 DB. Air coupled through transmission of steel and glass has also been observed. A theoretical model for the transducers has ... |
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| The Effects of Noise on Health |
JUN 97 |
54 pages |
| Authors:
Charles S. Harris; ARMSTRONG LAB WRIGHT-PATTERSON AFB OH NOISE EFFECTS BRANCH
|
| There is an attempt to convey the complexity of and the difficulties in forming a perspective on noise research. This is followed, in turn, by a discussion of the some of the early research sponsored by the Environmental Protection Agency (EPA) that has had such a large role in developing many of the methods and procedures for noise assessment and evaluation. Many of the methods and recommendations are still used ... |
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| Nonequilibrium Carrier Dynamics, Transport, and Noise in Low Dimensional Semiconductor Structures |
30 MAY 1997 |
15 pages |
| Authors:
Vladimir Mitin; WAYNE STATE UNIV DETROIT MI
|
| Acoustic phonons in quantum wells and quantum wires and various mechanisms of their interaction with electrons have been investigated. The obtained radiation patterns and spectrums for emitted acoustic phonons show that the thermal energy is radiated preferably in the direction of spatial quantization. The interaction of the electrons with confined acoustic phonons in free-standing quantum wells leads to the electron relaxation times having steps on their dependence on electron energy. ... |
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| 3-Dimensional Audio Ergonomic Improvement Project for the NORAD CMOC |
MAY 1997 |
32 pages |
| Authors:
Debra North; William R. D'Angelo; ARMSTRONG LAB WRIGHT-PATTERSON AFB OH CREW SYSTEMS DIRECTORATE
|
| This technical report describes the concept, design, development, and on-site evaluation of a 3-dimensional (3-D) audio interface system for potential operational use by North American Aerospace Defense (NORAD). An initial prototype phase was used to evaluate the 3-D audio interface system in an operational exercise setting giving NORAD operators the capability to conduct hands-free communication over multiple communication lines. This 3-D audio interface system enabled hands-free communications by providing a ... |
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| Acquired Resistance to Impulse Noise |
MAY 97 |
18 pages |
| Authors:
Donald Henderson; STATE UNIV OF NEW YORK AT BUFFALO AMHERST
|
| Previous experiments have shown that the mammalians auditory system can be made more resistant to the traumatic effects of noise exposure by having the subject exposed to a lower level, prophylactic noise. This set of experiments was designed to see if the acquired resistance phenomenon could be adapted to protect soldiers. The specific experiments used chinchillas and focused on several questions: does the acquired resistance to noise (ARN) protect them ... |
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| Porous Metal/Organic Polymeric Composites. |
28 APR 1997 |
40 pages |
| Authors:
M. A. Imam; Satya B. Sastri; Tedyy M. Keller; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Metal foams are impregnated with resins. The metal foam/polymer composite formed upon curing has excellent acoustic dampening and structural properties. Foams of various metals, such as aluminum, titanium, nickel, copper, iron, zinc, lead, silver, gold, platinum, tantalum, and alloys based on these metals, may be used. The polymer component may be any polymeric resin, for example, epoxy, natural rubber, acrylic, or phenolic. |
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| Joint Tactical Electrical Vehicle, Active Ride Height and Damping Control, Final Report for FY '95: CALSTART System Development Project for Advanced Hybrid Reconnaissance Vehicles |
08 APR 97 |
294 pages |
| Authors:
CALSTART BURBANK CA
|
| The active suspension system developed for this project is based on an active damper for controlling the medium and high speed dynamics involved with vehicle body and wheel motions, and an active ride height system for controlling the low speed body motions. This type of system makes improvements over a passive system by allowing the optimal damping required for differing terrain and vehicle control requirements to be automatically set by ... |
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| 1997 NRL Review |
APR 1997 |
244 pages |
| Authors:
NAVAL RESEARCH LAB WASHINGTON DC
|
| The Navy Unit Commendation was awarded by The Honorable John H. Dalton, Secretary of the Navy, jointly to the military and civilian personnel of NRL and its parent organization, the Office of Naval Research. The award was presented for "unparalleled research and development that significantly contributed to the technological capabilities of current and future Naval forces" during the period January 1992 through July 1996. This award, an unusual distinction for ... |
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| Semiannual Report - October 1, 1996 Through March 31, 1997 |
31 MAR 1997 |
61 pages |
| Authors:
INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period October 1, 1996 through March 31 1997. |
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| Sixth Conference on Nonlinear Vibrations, Stability, and Dynamics of Structures |
11 MAR 97 |
209 pages |
| Authors:
Ali H. Nayfah; Dean T. Mook; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIEN CE AND MECHANICS
|
| The study of nonlinear vibrations, stability, and dynamics of structures underlies all applications in modern dynamical systems. Indeed, improving our understanding of the responses of nonlinear systems would contribute to the advancement of control systems, machine dynamics, acoustics, and noise control. It would also contribute to improving our national productivity and competitiveness by opening the design space. |
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| Fluctuating Dilatation Rate as an Acoustic Source |
97 |
11 pages |
| Authors:
J. R. Ristorcelli; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| Ribner's (1962) dilatational acoustic theory is revisited. A rigorous connection between the fluctuating dilatation rate and the acoustic source field is established; this vindicates Ribner's heuristic contention while indicating additional acoustic source terms in his dilatational acoustic theory. It is also shown that Ribner's acoustic source term is quadrupole. Interesting consequences of the dilatational point of view are indicated. It is found that in the region of vortical fluid motion ... |
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| Design and Development of a Constant Beamwidth Transducer for Sub-Bottom Acoustic Profiling |
1997 |
7 pages |
| Authors:
K. C. Benjamin; A. K. Walden; A. L. Van Buren; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| The design, fabrication, and acoustic calibration for a new Constant Beamwidth Transducer (CBT) is presented. Although designed for a sub-bottom profiling application, the transducer may be used whenever a spatially constant sound beam is desired over a relatively wide frequency range. The CBT design is based on the theoretical work presented earlier by Van Buren et al. [1] and relies on an axis-symmetric velocity distribution acting over a spherically curved ... |
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| Applied Physics Laboratory, College of Ocean and Fishery Sciences, University of Washington. 1997 Biennial Report |
97 |
54 pages |
| Authors:
UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
|
| Formed in 1943 in response to a Navy request for assistance in development a reliable torpedo influence exploder, the Applied Physics Laboratory (APL) of the University of Washington has evolved into a well-known and respected source of research and development in marine-related science and engineering. The partnership with the Navy that began over 50 years ago continues today with a program based in fundamental research and grounded by expertise developed ... |
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| Development of a Broadband Underwater Sound Projector |
1997 |
8 pages |
| Authors:
Thomas R. Howarth; Robert Y. Ting; NAVAL RESEARCH LAB WASHINGTON DC ACOUSTICS DIV
|
| Abstract - An underwater sound projector has been recently developed for operation over a decade long frequency range. The output of the projector has been designed for 10 kHz to 100 kHz operation on an autonomous underwater vehicle (AUV). The transducer is resonant at 100 kHz but has been designed to deliver high sound pressure levels without impedance or phase instabilities. The transducer features the first successful stacking of 1-3 ... |
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| Casimir Acoustics |
DEC 96 |
40 pages |
| Authors:
Robert T. Susbilla; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| When the indirect manifestations of the electromagnetic ZPF are interpreted as due to radiation pressure, acoustic noise can render an excellent analog to probe previous as well as recently proposed behavior. An acoustic chamber for isotropic and homogeneous acoustic noise of controllable spectral shape has been built. The noise can be driven up to levels of 130 dB (re 20 microPa) in a band of frequencies up to 50 kHz ... |
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| Strategy for Application of Non-Destructive Testing to Maintenance of Nuclear Power Plants, |
DEC 1996 |
|
| Authors:
J. Samman
|
| Paper describes Electricite de France's strategies for nondestructive inspection of their nuclear power plants. Topics include: curative maintenance, preventive maintenance, safety, technique, and economy. (NTIAC). |
|
| Ultrasonic Examination Modelling at the CEA, |
DEC 1996 |
|
| Authors:
P. Calmon; A. Lhemery; I. Lecoeur-Taibi; R. Raillon
|
| The French Atomic Energy Commission (CEA) has developed a system called CIVA for multiple-technique NDE data acquisition and processing. Modelling tools for ultrasonic nondestructive testing have been developed and implemented within this system allowing direct comparison between measured and predicted results. These models are not only devoted to laboratory uses but also must be usable by ultrasonic operators without special training in simulation techniques. Therefore, emphasis has been on finding ... |
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| Condition Monitoring and NDT of Water Mains of the City of Bordeaux, |
DEC 1996 |
|
| Authors:
X.E. Gros; R.D. Wakefield
|
| Bordeaux has a network of water pipes totalling 2,400 km, 13 water treatment stations and an average of 160,000 cubed meters of drinking water distributed every day. Total quality management of the water mains is a task requiring the latest of technologies. This paper presents an overview of technologies developed by the water company Lyonnaise des Eaux for condition monitoring and nondestructive testing of the water mains of the city ... |
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| Advanced Maintenance Advisory Surveillance System (AMASS) for Equipment Operating in Hostile Environments, |
DEC 1996 |
|
| Authors:
M. Martins
|
| The overall objective of the AMASS project is to develop an on-line surveillance system which monitors the condition of boiler tubing in service and reduces the number of forced outages due to degradation by erosion, corrosion, and overheating. The system will integrate the outputs of on-line and off-line techniques, together with tube life algorithms to give real-time estimates of tube life probability. This paper presents the planned project objectives and ... |
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| Fundamental Studies of Radial Wave Thermoacoustic Engines |
10 NOV 96 |
20 pages |
| Authors:
W. P. Arnott; NEVADA UNIV SYSTEM RENO ATMOSPHERIC SCIENCES CENTER
|
| Our goal was to evaluate the influence of resonator geometry on thermoacoustic engine performance. Resonator geometry affects thermoacoustic heat transport and acoustic power generation, energy dissipation, and stack volume. Thermoacoustic engines placed in the first radial mode of a cylindrical resonator were studied in detail, and were compared with the more-developed plane wave resonator counterparts. A radial wave prime mover was constructed from use of our numerical model. Experimental results ... |
|
| ICASE: Semiannual Report. April 1, 1996 through September 30, 1996 |
NOV 96 |
90 pages |
| Authors:
INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| The Institute for Computer Applications in Science and Engineering (ICASE) is operated at the Langley Research Center (LaRC) of NASA by the Universities Space Research Association (USRA) under a contract with the Center. USRA is a nonprofit consortium of major U. S. colleges and universities. The Institute conducts unclassified basic research in applied mathematics, numerical analysis and algorithm development, fluid mechanics, and computer science in order to extend and improve ... |
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| RAH-66 Comanche Health Hazard and Performance Issues for the Helmet Integrated Display and Sighting System |
NOV 96 |
48 pages |
| Authors:
Clarence E. Rash; Ben T. Mozo; B. J. McEntire; Joseph R. Licina; ARMY AEROMEDICAL RESEARCH LAB FORT RUCKER AL
|
| The helmet integrated and display sighting system (HIDSS) is a combination of a protective helmet, helmet mounted display (HMD), and helmet mounted sighting system. It is planned for use in the Army's next generation reconnaissance/attack helicopter, the RAH-66 Comanche. In 1986 and 1988, USAARL developed and published guidelines for addressing potential health hazard issues with the HIDSS. The most recent version of these guidelines was USAARL LR 88-4- 21-1O, 'Revision ... |
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| Prototype Acoustic Monitoring Pad |
OCT 96 |
20 pages |
| Authors:
Michael V. Scanlon; ARMY RESEARCH LAB ADELPHI MD
|
| The Army Research Laboratory has developed an acoustic sensor that couples extremely well with the human body to detect and monitor heartbeat and lung sounds. A hand-held version of the sensing pad was configured that can be attached to a field medic's hand or glove for combat casualty care. The configuration allows auscultation through headphones by placement of the medic's hand on the torso or limb. Data collected with a ... |
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| Controlling Mechanisms of Pulsating Incineration Processes |
30 SEP 96 |
90 pages |
| Authors:
B. T. Zinn; J. I. Jagoda; L. M. Matta; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| The purpose of this research program is to study the fundamental processes that control the performance of acoustically excited incineration systems. The information learned will be used in the development of a compact, high efficiency waste incinerator for shipboard use. Tests performed during the course of this program have demonstrated that mixing and heat transport processes, both crucial to the incineration process, can be enhanced by imposing acoustic oscillations. Because ... |
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| Non-Invasive, Photochromic-Tracer Studies of Particulate Suspensions and Granular Media |
01 SEP 96 |
7 pages |
| Authors:
J. D. Goddard; CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF APPLIED MECHANICS AND ENGINEERING SCIENCES
|
| This is a summary of research performed under the subject AFOSR grant on the micromechanics, continuum mechanics and transport properties of granular media and geomaterials. It has involved the development of new theoretical models of microstructure, numerical simulation of granular assemblages, and experimental observation on model systems. The overall goal of the work is to provide a sound microstructural basis for understanding continuum behavior and elucidating structurally and geologically important ... |
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| Graduate Student Research Sound Source Determination |
31 AUG 96 |
6 pages |
| Authors:
William A. Yost; LOYOLA UNIV OF CHICAGO IL PARMLY HEARING INST
|
| The objective of this report is to better understand the role of binaural processing in complex multi-sound source acoustic environments. Dr Grange worked on the topic of binaural pitch, sometimes called Huggins pitch. |
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| New Physical Models and Methods for Source Localization |
AUG 96 |
11 pages |
| Authors:
Arye Nehorai; YALE UNIV NEW HAVEN CT
|
| The research focuses on the development of sensor processing methods for source localization and parameter estimation. The main contributions are: the introduction of electromagnetic and acoustic vector-sensor processing; development of radar polarimetric methods, including remote sensing applications, and optimum choices of transmitting signals and polarizations; methods for sensor calibration using active sources; localizing sources using a small number of mobile sensors that can replace methods with a large number of ... |
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| Environmental Effects of Dredging, Technical Notes |
AUG 96 |
8 pages |
| Authors:
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB
|
| Biomagnification of Contaminants in Aquatic Food Webs as a Result of Open-Water Disposal of Dredged Material ; Fate of Dredged Material During Open- Water Disposal; Engineering Considerations for Capping Subaqueous Dredged Material Deposits-Background and Preliminary Planning; Engineering Considerations for Capping Subaqueous Dredged Material Deposits-Design Concepts and Placement Techniques; Monitoring Dredged Material Consolidation and Settlement at Aquatic Disposal Sites; Computerized Database for Interpretation of the Relationship Between Contaminant Tissue Residues and ... |
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| Problems in Nonlinear Acoustics: Surface Acoustic Waves, Nondestructive Testing, and Acoustic Streaming |
01 JUL 96 |
10 pages |
| Authors:
Mark F. Hamilton; TEXAS UNIV AT AUSTIN DEPT OF MECHANICAL ENGINEERING
|
| Three projects in nonlinear acoustics are described: (1) Surface Acoustic Waves (derivation of theoretical models for Stoneley and Scholte waves in isotropic solids, surface waves in crystals, and surface waves in piezoelectric materials); (2) Nondestructive Testing (theory and experiment for ultrasonic measurement of third order elastic moduli via immersion techniques); (3) Acoustic Streaming (numerical modeling of acoustic streaming, at high Reynolds numbers, produced by focused sound beams containing shocks). ... |
|
| ARO and AFOSR Contractors Meeting in Chemical Propulsion, Held in Virginia Beach, Virginia on 3-6 June 1996 |
20 JUN 96 |
299 pages |
| Authors:
David M. Mann; Mitat A. Birkan; Julian M. Tishkoff; AIR FORCE OFFICE OF SCIENTIFIC RESEARCH BOLLING AFB DC
|
| Partial contents: Supercritical droplet behavior; Fundamentals of acoustic instabilities in liquid-propellant rockets; Modeling liquid jet atomization proceses; Liquid-propellant droplets dynamics and combustions in supercritical forced convective environments; Contributions of shear coaxial injectors to liquid rocket motor combustion instabilities; High pressure combustion studies under combustion driven oscillatory flow conditions; Droplet collision on liquid propellant combustion; Combustion and plumes; Development of a collisional radiative emission model for strongly nonequilibrium flows; Energy transfer ... |
|
| An Analysis of Spacecraft Dynamic Testing at the Vehicle Level |
JUN 96 |
136 pages |
| Authors:
Alan D. Scott; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The US space industry has accumulated a vast amount of expertise in the testing of spacecraft to ensure these vehicles can endure the harsh environments associated with launch and on-orbit operations. Even with this corporate experience, there remains a wide variation in the techniques utilized to test spacecraft during the development and manufacturing process, particularly with regard to spacecraft level dynamics testing. This study investigates the effectiveness of sinusoidal vibration, ... |
|
| Summary of Technical Support for Seawolf Shock Test: Potential Impact on Marine-Mammal Hearing |
15 MAY 96 |
86 pages |
| Authors:
Jean A. Goertner; Delbert L. Lehto; NAVAL SURFACE WARFARE CENTER INDIAN HEAD DIV MD
|
| This report documents a study performed in support of the SSN 21 (Seawolf) shock-test program. The purpose was twofold: (1) to develop a more efficient method for calculating potential acoustic damage to marine-mammal herring from underwater explosions, and (2) to perform calculations specifically for use in preparing the Seawolf environmental impact statement. The most meaningful criterion for determining acoustic safe ranges would be one based on measurements of temporary threshold ... |
|
| Efficient Algorithms for Speech Recognition |
15 MAY 96 |
|
| Authors:
Mosur K. Ravishankar; CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF COMPUTER SCIENCE
|
| Advances in speech technology and computing power have created a surge of interest in the practical application of speech recognition. However, the most accurate speech recognition systems in the research world are still far too slow and expensive to be used in practical, large vocabulary continuous speech applications. Their main goal has been recognition accuracy, with emphasis on acoustic and language modelling. But practical speech recognition also requires the computation ... |
|
| Phonon Interactions in Novel Semiconductor Nanostructures |
MAY 96 |
109 pages |
| Authors:
Michael A. Stroscio; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF ELECTRICAL AND COMPUTER ENGINEERI NG
|
| During this research effort, numerous interactions of confined phonons in nanostructures have been modelled theoretically; these include: piezoelectric scattering in cylindrical quantum wires; generalized piezoelectric scattering rate for elections in a two-dimensional election gas; Gamma-X transitions driven by interface phonons; interface optical modes in cylindrical quantum wires; microscopic model for election-optical-phonon interactions in quantum wells; optical phonons in quantum dots; electron-acoustic-phonon scattering in both rectangular and cylindrical quantum wires; and ... |
|
| PCBoom3 Sonic Boom Prediction Model - Version 1.0c |
MAY 1996 |
39 pages |
| Authors:
Kenneth J. Plotkin; WYLE RESEARCH LAB ARLINGTON VA
|
| PCBoom3 is a PC-based program that computes single-event sonic boom footprints from any supersonic vehicle exercising any maneuver in a real atmosphere, including winds. The user specifies the aircraft, the maneuver, and the atmosphere. The primary output is the sonic boom footprint in terms of contours of equal overpressure (or other amplitude metric) on the ground, relative to the aircraft's position. PCBoom3 also generates sonic boom signatures, the pressure-time history ... |
|
| New Computational Methods for the Prediction and Analysis of Helicopter Noise |
May 1996 |
17 pages |
| Authors:
Roger C Strawn; Leonid Oliker; Rupak Biswas; RESEARCH INST FOR ADVANCED COMPUTER SCIENCE MOFFETT FIELD CA
|
| This paper describes several new methods to predict and analyze rotorcraft noise. These methods are 1) a combined computational fluid dynamics and Kirchholt scheme for far-field noise predictions, 2) parallel computer implementation of the Kirchhoff integrations 3) audio and visual rendering of the computed acoustic predictions over large far-field regions, and 4) acoustic tracebacks to the Kirchhoff surface to pinpoint the sources of the rotor noise. The paper describes each ... |
|
| Depth and Geoacoustic Parameter Measurement in Littoral Regions Using the UQN-4A Sonar Sounding Set |
08 APR 96 |
29 pages |
| Authors:
Raymond W. Fidler; Robert D. Broome; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS FREQUENCY ACOUSTICS SECTION
|
| The data in this report demonstrates that SIMAS (Sonar In situ Mode Assessment System) can obtain current in situ bathymetric and geoacoustic information from the AN/UQN-4A Sonar Sounding Set (depth sounder) in littoral regions where vessels equipped with SIMAS systems will operate. Acoustic time series and digital depth output data were collected from the depth sounder for recording and transmission to the SIMAS system on-board the USS Curtis Wilbur (DDG-54). ... |
|
| Development of Nondestructive Evaluation Methods for Structural Ceramics, |
APR 1996 |
|
| Authors:
W.A. Ellingson; R.D. Koehl; H.P. Engel; J.A. Wilson; J.B. Stuckey; ARGONNE NATIONAL LAB IL ENERGY AND ENVIRONMENTAL SYSTEMS DIV
|
| Nondestructive evaluation (NDE) methods using three-dimensional microfocus X-ray computed tomographic imaging (3DXCT) were employed to map axial and radial density variations in hot-gas filters and heat exchanger tubes. 3D XCT analysis was conducted on (a) two 38-mm-OD, 6.5-mm wall, SiC/SiC heat exchanger tubes infiltrated by CVI; (b) eight 10 cm diam. oxide/oxide heat exchanger tubes; and (c) one 26-cm-long Nextel fiber/SiC matrix hot-gas filter. The results show that radial and ... |
|
| Acoustic Element Tester for an Array of Hydrophones. |
22 MAR 1996 |
18 pages |
| Authors:
Foster L. Striffler; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| An apparatus for testing an individual hydrophone element in an axially extending hydrophone array includes a pressure wave generator, an insonifier for directing the generated pressure waves toward a selected one of the elements of the array and a monitor for measuring the output of the array responsive to the generated arrays. The pressure wave generator is isolated so it does not produce pressure waves externally thereto. The insonifier includes ... |
|
| Sonar Baffles. Presentation at the Wayne Reader Memorial Session of the 129th Meeting of the Acoustical Society of America, 31 May 1995, Washington, DC |
16 FEB 96 |
16 pages |
| Authors:
Ronald P. Radlinski; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV NEW LONDON CT NEW LONDON DETACHMENT
|
| Acoustic decoupling baffles are often used to minimize noise contamination at hydrophone and transducer arrays. To maintain sensitivity near the nominally pressure release surface of the baffle, hydrophones can be placed at an odd multiple of a quarter wavelength from the baffle or near a heavy signal conditioning plate inserted between the hydrophones and the baffle. In either case, coherent interference between the incident wave and the wave reflected from ... |
|
| Response of the Lungs to Low Frequency Underwater Sound |
31 JAN 96 |
29 pages |
| Authors:
Peter H. Rogers; Gary W. Caille; Thomas N. Lewis; GEORGIA INST OF TECH ATLANTA SCHOOL OF MECHANICAL ENGINEERING
|
| Because of their high compliance, the lungs are probably more vulnerable to damage by high intensity, low frequency underwater sound than any other part of the human anatomy. The objective of this research was to study the effects of low frequency (50-1200 Hz) underwater sound on the lungs to assist in estimating safe exposure conditions for swimmers and divers. To accurately assess the risk, it is necessary to have a ... |
|
| Proceedings of the International Symposium on the Effects of Noise on Hearing: Scientific Basis of Noise-Induced Hearing Loss (5th) Held in Goetborg, Sweden on 12-14 May 1994. |
JAN 1996 |
486 pages |
| Authors:
Roger P. Hamernik; STATE UNIV OF NEW YORK COLL AT PLATTSBURGH
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| Biological Basis of Noise-Induced Hearing Loss, Sensory Cell Regeneration and Functional Recovery, The Effects of Acoustic Trauma, Other Cochlear Injury, and Death on Basilar-Membrane Responses to Sound, Excitotoxicity and Plasticity of IHC-Auditory Nerve Contributes to Both Temporary and Permanent Threshold shift, Noise-Induced Expression of Heat Shock Proteins in the Cochlea, Changes in Gene Expression Following Temporary Noise- Induced Threshold Shift, Genetic Susceptibility to Noise-Induced Hearing Loss in Mice, Effects of ... |
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