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  • Acoustics
  • 1980-1984  (33)
  • 1975-1979  (13)
  • 1925-1929
Collection
Years
Year
  • 1
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    In:  Geophysics, Luxembourg, Conseil de l'Europe, vol. 44, no. 2, pp. 1485-1501, pp. 1892
    Publication Date: 1979
    Keywords: Inversion ; Acoustics
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  • 2
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    In:  Geophysics, San Francisco, Pergamon, vol. 44, no. 3, pp. 1485-1501, pp. 1246
    Publication Date: 1979
    Keywords: Pseudo Impedance Log ; Acoustics
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  • 3
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    In:  Geophysics, London, Institution of Mining and Metallurgy, vol. 46, no. B8, pp. 1559, pp. 1869, (ISBN: 0-12-018847-3)
    Publication Date: 1982
    Keywords: Seismics (controlled source seismology) ; Reflection seismics ; Acoustics
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  • 4
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    In:  Geophysics, Heidelberg, 3-4, vol. 46, no. 2, pp. 1244-1246, pp. 1516, (ISBN: 0-12-018847-3)
    Publication Date: 1981
    Keywords: Layers ; Seismics (controlled source seismology) ; Reflection seismics ; Physical properties of rocks ; Acoustics
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  • 5
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    In:  Physikalische Zeitschrift, Jena, Gustav Fischer, vol. 27, no. 3, pp. 84-86, pp. L24306, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1926
    Keywords: Meteorology ; Acoustics
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  • 6
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    In:  Zeitschrift für Geophysik, Jena, Gustav Fischer, vol. 2, no. 3, pp. 260-266, pp. L24306, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1926
    Keywords: Waves ; Acoustics
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  • 7
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    In:  Die Naturwissenschaften, Jena, Gustav Fischer, vol. 14, no. 3, pp. 338-342, pp. L24306, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1926
    Keywords: Waves ; Meteorology ; Acoustics
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  • 8
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    In:  Int J. Rock Mech. Min. Sci. & Geomech. Abstr., Basel, Inst. f. Geophys., Ruhr-Univ. Bochum, vol. 15, no. 4, pp. 53-58, pp. 1517, (ISSN: 1340-4202)
    Publication Date: 1978
    Keywords: Velocity ; Laboratory measurements ; Instruments ; Acoustics
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  • 9
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    In:  Geophys. J. R. astr. Soc., Basel, Inst. f. Geophys., Ruhr-Univ. Bochum, vol. 70, no. 1, pp. 229-243, pp. 8038, (ISSN: 1340-4202)
    Publication Date: 1982
    Keywords: Impedance ; Gelfand-Levitan ; Inversion ; Acoustics ; GJRaS
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  • 10
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    In:  Wave Motion, Basel, Inst. f. Geophys., Ruhr-Univ. Bochum, vol. 4, no. 1, pp. 99-110, pp. 8038, (ISSN: 1340-4202)
    Publication Date: 1982
    Keywords: Inversion ; Impedance ; Acoustics
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  • 11
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    In:  J. Acoust. Soc. Am., Dordrecht, Netherlands, Dr. W. Junk, vol. 73, no. 2, pp. 61-65, pp. L13307, (ISSN: 1340-4202)
    Publication Date: 1983
    Keywords: Seismic stratigraphy ; Acoustics
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  • 12
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    In:  J. Acoust. Soc. Am., Luxembourg, Conseil de l'Europe, vol. 73, no. 1, pp. 1179-1186, pp. 1006, (ISSN: 1340-4202)
    Publication Date: 1983
    Keywords: Inversion ; Impedance ; Acoustics
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  • 13
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    In:  Geophysics, Kunming, China, AGU, vol. 49, no. 14, pp. 1259-1266, pp. L14317, (ISSN: 1340-4202)
    Publication Date: 1984
    Keywords: Reflection seismics ; Seismics (controlled source seismology) ; Inversion ; Acoustics
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  • 14
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    Elsevier
    In:  Amsterdam, Elsevier, vol. 14 B, pp. 225, (ISBN 3-7643-7011-4)
    Publication Date: 1984
    Keywords: Applied geophysics ; seismic Migration ; Seismics (controlled source seismology) ; Acoustics
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  • 15
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    Elsevier
    In:  Amsterdam, 253 pp., Elsevier, vol. 10, no. 1, pp. 1-40, (ISBN: 3-540-23712-7)
    Publication Date: 1983
    Keywords: Textbook of geophysics ; Acoustics ; Seismics (controlled source seismology) ; Waves ; Wave propagation
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  • 16
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    DPG-Verlag
    In:  Bull., Polar Proj. OP-O3A4, Fortschritte d. Akustik, DAGA 78, Bad Honnef, DPG-Verlag, vol. 81A, no. 16, pp. 597-600, (ISBN: 3-540-23712-7)
    Publication Date: 1978
    Keywords: Acoustics ; physics
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  • 17
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    DPG-Verlag
    In:  Bull., Polar Proj. OP-O3A4, Fortschritte d. Akustik, DAGA 84, Bad Honnef, DPG-Verlag, vol. 81A, no. 16, pp. 663-666, (ISBN: 3-540-23712-7)
    Publication Date: 1984
    Keywords: Acoustics ; physics
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  • 18
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    In:  Geophysics, Paris, Pergamon, vol. 48, no. 1, pp. 1351-1358, pp. 1246
    Publication Date: 1983
    Keywords: Pseudo Impedance Log ; Acoustics ; Seismics (controlled source seismology)
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  • 19
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    In:  J. Acoust. Soc. Am., Luxembourg, U.S. Geological Survey, vol. 67, no. 22, pp. 833-841, pp. B05309, (ISBN 0-471-26610-8)
    Publication Date: 1980
    Keywords: Detectors ; NOISE ; Acoustics
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  • 20
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    In:  J. Acoust. Soc. Am., Bonn, South Afr. Inst. Mining Metall., vol. 68, no. 1, pp. 1454-1458, pp. 1056, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1980
    Keywords: Seismic stratigraphy ; Randomly layered ; Acoustics
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  • 21
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    In:  Proceedings IEEE, Stuttgart, Icelandic Meteorological Office, Ministry for the Environment,, vol. 71, no. 8, pp. 330-337, pp. L05602, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1983
    Keywords: Inversion ; Acoustics
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  • 22
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    In:  Bull. Seism. Soc. Am., London, Institution of Mining and Metallurgy, vol. 67, no. B8, pp. 1529-1540, pp. 1869, (ISBN: 0-12-018847-3)
    Publication Date: 1977
    Keywords: Synthetic seismograms ; Absorption ; Acoustics ; BSSA
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  • 23
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    In:  Geophysics, Heidelberg, 3-4, vol. 44, no. 4, pp. 1077-1087, pp. 1516, (ISBN: 0-12-018847-3)
    Publication Date: 1979
    Keywords: Seismics (controlled source seismology) ; Inversion ; Waves ; Acoustics
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  • 24
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    In:  Zeitschrift für Geophysik, Jena, Gustav Fischer, vol. 2, no. 3, pp. 101-106, pp. L24306, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1926
    Keywords: Meteorology ; Acoustics
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  • 25
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    Geophysical Press
    In:  London, Geophysical Press, vol. 12, pp. 225, (ISBN 3-7643-7011-4)
    Publication Date: 1984
    Keywords: Handbook of geophysics ; Seismics (controlled source seismology) ; Reflection seismics ; Applied geophysics ; Acoustics
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  • 26
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    Inst. Electrical & Electronics Engineers
    In:  Proceedings of the Ultrasonic Symposium (IEEE catalogue 76 CH 1344-1/78/000), Rome, Inst. Electrical & Electronics Engineers, vol. 10, no. 84-256, pp. 225-228
    Publication Date: 1978
    Keywords: Seismics (controlled source seismology) ; Mining geophysics ; Acoustics
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  • 27
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    In:  Geophysics, Kyoto, AGU, vol. 48, no. 2, pp. 1318-1337, pp. L24302, (ISSN: 1340-4202)
    Publication Date: 1983
    Keywords: Inversion ; Impedance ; Acoustics
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  • 28
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    DPG-Verlag
    In:  Bull., Polar Proj. OP-O3A4, Fortschritte d. Akustik, DAGA 81, Bad Honnef, DPG-Verlag, vol. 81A, no. 16, pp. 709-712, (ISBN: 3-540-23712-7)
    Publication Date: 1981
    Keywords: Acoustics ; physics
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  • 29
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    In:  Geophysics, Kyoto, AGU, vol. 49, no. 2, pp. 1653-1663, pp. L24302, (ISSN: 1340-4202)
    Publication Date: 1984
    Keywords: Inversion ; Impedance ; Velocity ; Acoustics
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  • 30
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    Geophysical Press
    In:  New York, Geophysical Press, vol. 7, pp. 225, (ISBN 3-7643-7011-4)
    Publication Date: 1984
    Keywords: seismic Migration ; Spatial resolution ; Acoustics
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  • 31
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    Applied Science Publishers
    In:  Bull., Open-File Rept., Developments in Geophysical Exploration Methods, London, Applied Science Publishers, vol. 3, no. 1, pp. 151-193, (ISBN 0080419208)
    Publication Date: 1982
    Keywords: Borehole geophys. ; Borehole Compensated Sonic log ; Acoustics
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  • 32
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    In:  Preprint, Beijing, Halliburton Logging Services, vol. C 560, 183 pp., no. PL-TR-91-2212(II), pp. 938-939, (ISBN 3-933346-037)
    Publication Date: 1979
    Keywords: Seismology ; Seismics (controlled source seismology) ; Scattering ; Coda (waves, ~ of seismograms) ; Wave propagation ; Acoustics
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  • 33
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    Lehrstuhl f. allg. E-Technik u. Elektroakustik, Ruhr-Univ. Bochum
    In:  Diplomarbeit, St. Louis, Lehrstuhl f. allg. E-Technik u. Elektroakustik, Ruhr-Univ. Bochum, vol. C 560, 183 pp., no. GL-TR-89-0143, pp. 13-24, (ISBN 3-933346-037)
    Publication Date: 1979
    Keywords: Acoustics ; physics
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  • 34
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    Inst. f. Meteorol. und Geophys. der Univ. Frankfurt/Main
    In:  Dissertation, Berichte, Kiel, Inst. f. Meteorol. und Geophys. der Univ. Frankfurt/Main, vol. C 560, 183 pp., no. 33, pp. 40-48, (ISBN 3-933346-037)
    Publication Date: 1977
    Keywords: Laboratory measurements ; Physical properties of rocks ; Absorption ; Quality factor ; Acoustics
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  • 35
    Publication Date: 1982-10-08
    Description: Sounds recorded in Dallas at the time of the assassination of John F. Kennedy were analyzed by two research groups, whose reports formed the basis for the opinion that two gunmen fired at President Kennedy. These reports and the acoustic evidence have been studied by the Committee on Ballistic Acoustics, and further acoustic analyses, including sound spectrograms, have been performed. The committee finds that the acoustic data do not support a conclusion that a second gunman was involved in the assassination.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 1982 Oct 8;218(4568):127-33.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6750789" target="_blank"〉PubMed〈/a〉
    Keywords: Acoustics ; *Famous Persons ; *Forensic Medicine ; History, 20th Century ; Humans ; Male ; Texas ; *Wounds, Gunshot
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 36
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-08-17
    Description: The mustache bat emits a three-harmonic echolocation pulse. At the external ear, large interaural intensity differences are generated only when a sound originates within a limited area of two-dimensional space, and this area is different for each pulse harmonic. As a consequence, the external ear generates pronounced binaural spectral cues containing two-dimensional spatial information. This information is encoded in the inferior colliculus by neurons tuned to one of the harmonics and sensitive to interaural intensity differences.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fuzessery, Z M -- Pollak, G D -- NS 13276/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1984 Aug 17;225(4663):725-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6463649" target="_blank"〉PubMed〈/a〉
    Keywords: Acoustics ; Animals ; Auditory Perception/*physiology ; Chiroptera/*physiology ; Ear, External/physiology ; Echolocation/*physiology ; Inferior Colliculi/physiology ; Neurons/physiology ; Orientation/*physiology ; Sound Localization/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 37
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    In:  CASI
    Publication Date: 2018-06-09
    Description: Many manufacturers of loudspeakers are now using a magnetic liquid cooling agent known as ferrofluid. Commercialized by Ferrofluids Corporation, ferrofluid is a liquid material in which sub-microscopic particles of iron oxide are permanently suspended. Injected into the voice coil segment of speaker system, magnetic liquid serves as superior heat transfer medium for cooling the voice coil, thus substantially increasing the system's ability to handle higher power levels and decreasing chance of speaker failure. Ferrofluid offers several additional advantages which add up to improved speaker performance, lower manufacturing costs and fewer rejects.
    Keywords: Acoustics
    Type: Spinoff 1980; 122
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  • 38
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    In:  CASI
    Publication Date: 2018-06-09
    Description: A demonstration conducted last winter at the Tip Top Poultry Plant intended to show poultry plant managers from all over the U.S. potential solutions to the problem of plant noise. Plastic covers used over sound absorbing materials need to meet cleanability requirements, high- pressure water cleaning and other harsh maintenance procedures peculiar to the poultry processing industry. For the demonstration, Fiber Flex, Inc. manufactured and donated 750 noise panels; Owens-Corning Fiberglas Corporation donated the fiberglas cores; and the cover material was purchased from Howe and Bainbridge. The Engineering Experiment Station (EES) conducted before and after noise surveys and is evaluating the effect of noise reduction on turnover and productivity in the demonstration plant. EES plans to conduct a noise abatement workshop and update a handbook to help poultry processors with noise problems. EES study and demonstration may be applicable to other food processing plants where similar sanitary constraints exist.
    Keywords: Acoustics
    Type: Spinoff 1982; 94-95
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  • 39
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    In:  CASI
    Publication Date: 2018-06-09
    Description: MicroUltrasonics PLR-1000 is a refined microprocessor-controlled version (usable on bolts, plates, liquids and gases) of the P2L2 developed by Langley Research Center. New technique is for nondestructive measurement of residual stress in various types of structures, for example, nuclear pressure vessels, pipes in nuclear reactors, offshore platforms, bridges, railroad tracks and wheels, aircraft wings, and engines. The instrument produces sound tone pulses that travel through a test specimen. PLR-1000 precisely measures speeds as stress increases speed of sound, tone changes, making precise measurements possible.
    Keywords: Acoustics
    Type: Spinoff 1983; 95
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  • 40
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    In:  CASI
    Publication Date: 2018-06-09
    Description: PIND, developed by Dunegan/Endevco is an acronym for Particle Impact Noise Detection, a means of finding tiny, loose conductive particles introduced during fabrication of integrated circuits, which sometimes cause system failures. One type of automated system used for PIND testing has undergone a study by Goddard Space Flight Center to determine its effectiveness. Analysis of the test data indicated that an average PIND detection capability of about 45 percent can be expected.
    Keywords: Acoustics
    Type: Spinoff 1981; 63
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  • 41
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    In:  CASI
    Publication Date: 2019-06-28
    Description: An improved test section for a supersonic or hypersonic wind tunnel is disclosed wherein the model tested is shielded from the noise normally radiated by the turbulent tunnel wall boundary layer. A vacuum plenum surrounds spaced rod elements making up the test chamber to extract some of the boundary layer as formed along the rod elements during a test to thereby delay the tendency of the rod boundary layers to become turbulent. Novel rod construction involves bending each rod slightly prior to machining the bent area to provide a flat segment on each rod for connection with the flat entrance fairing. Rods and fairing are secured to provide a test chamber incline on the order of 1 deg outward from the noise shield centerline to produce up to 65% reduction of the root mean square (rms) pressure over previously employed wind tunnel test sections at equivalent Reynolds numbers.
    Keywords: Acoustics
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  • 42
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    In:  CASI
    Publication Date: 2019-08-17
    Description: SMART, Sound Modification and Regulated Temperature compound, is a liquid plastic mixture with exceptional energy and sound absorbing qualities. It is derived from a very elastic plastic which was an effective noise abatement material in the Apollo Guidance System. Discovered by a NASA employee, it is marketed by Environmental Health Systems, Inc. (EHS). The product has been successfully employed by a diaper company with noisy dryers and a sugar company with noisy blowers. The company also manufactures an audiometric test booth and acoustical office partitions.
    Keywords: Acoustics
    Type: Spinoff 1983; 124-125
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  • 43
    Publication Date: 2019-07-12
    Description: A mass archival optical recording and reproduction system includes a recording light source such as a laser beam focussed and directed upon an acousto-optic linear modulator array (or page composer) that receives parallel blocks of data converted from a serial stream of digital data to be stored. The page composer imparts to the laser beam modulation representative of a plurality of parallel channels of data and through focussing optics downstream of the page composer parallel arrays of optical spots are recorded upon a suitable recording medium such as a photographic film floppy disc. The recording medium may be substantially frictionlessly and stably positioned for recording at a record/read station by an air-bearing platen arrangement which is preferably thermodynamically non-throttling so that the recording film may be positioned in the path of the information-carrying light beam in a static or dynamic mode. During readout, the page composer is bypassed and a readout light beam is focussed directly upon the recording medium containing an array of previously recorded digital spots, a sync bit, data positioning bits, and a tracking band. The readout beam which has been directed through the recording medium is then imaged upon a photodetector array, the output of which may be coupled to suitable electronic processing circuitry, such as a digital multiplexer, whereby the parallel spot array is converted back into the original serial data stream.
    Keywords: Acoustics
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  • 44
    Publication Date: 2019-08-17
    Description: Helicopter impulsive noise tests were conducted in the Langley V/STOL tunnel with an articulated rotor system. The tests demonstrated that impulsive noise could be simulated for low-speed forward flight with low descent rates and also in the high-speed level flight. For the low forward speed condition, the noise level was highly sensitive to small changes in descent rate. For the high-speed condition, the noise level was increased with an increase in rotor thrust.
    Keywords: Acoustics
    Type: NASA-TM-X-3528 , NAS 1.15:X-3528 , L-11229
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  • 45
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    In:  CASI
    Publication Date: 2019-08-16
    Description: Environmental Health Systems puts forth an increasing effort in the U.S. to develop ways of controlling noise, particularly in industrial environments due to Federal and State laws, labor union insistence and new findings relative to noise pollution impact on human health. NASA's Apollo guidance control system aided in the development of a noise protection product, SMART. The basis of all SMART products is SMART compound a liquid plastic mixture with exceptional energy/sound absorbing qualities. The basic compound was later refined for noise protection use.
    Keywords: Acoustics
    Type: Spinoff 1980; 88
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  • 46
    Publication Date: 2019-07-10
    Description: As part of a research program directed at the acoustics of advanced subsonic propulsion systems undertaken at NASA Langley, Duke University was funded to develop a boundary condition model for bulk-reacting nacelle liners. The overall objective of the Langley program was to understand and predict noise from advanced subsonic transport engines and to develop related noise control technology. The overall technical areas included: fan and propeller source noise, acoustics of ducts and duct liners, interior noise, subjective acoustics, and systems noise prediction. The Duke effort was directed toward duct liner acoustics for the development of analytical methods to characterize liner behavior in both frequency domain and time domain. A review of duct acoustics and liner technology can be found in Reference [1]. At that time, NASA Langley was investigating the propulsion concept of an advanced ducted fan, with a large diameter housed inside a relatively short duct. Fan diameters in excess of ten feet were proposed. The lengths of both the inlet and exhaust portions of the duct were to be short, probably less than half the fan diameter. The nacelle itself would be relatively thin-walled for reasons of aerodynamic efficiency. The blade-passage frequency was expected to be less than I kHz, and very likely in the 200 to 300 Hz range. Because of the design constraints of a short duct, a thin nacelle, and long acoustic wavelengths, the application of effective liner technology would be especially challenging. One of the needs of the NASA Langley program was the capability to accurately and efficiently predict the behavior of the acoustic liner. The traditional point impedance method was not an adequate model for proposed liner designs. The method was too restrictive to represent bulk reacting liners and to allow for the characterization of many possible innovative liner concepts. In the research effort at Duke, an alternative method, initially developed to handle bulk reacting layers as described in Reference [2], was extended to apply to a broad range of liner types. This method included the effect of local gradients along the liner surface, and was particularly appropriate for situations with flow over the liner and grazing incidence acoustic fields. In order to utilize time domain computational methods to solve for the propfan acoustic field, corresponding liner boundary conditions were developed for time domain solutions rather than frequency domain solutions.
    Keywords: Acoustics
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  • 47
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    In:  CASI
    Publication Date: 2019-08-15
    Description: Through COSMIC, United Information Services, Inc., (UIS) in Raleigh, NC, purchased a software package consisting of two computer programs--NOIZ and RAYTR. These programs, enhanced by UIS for its particular applications, are used to provide computer analysis of noise level predictions for clients. Predictions are then used in design of new buildings or in remodeling existing plants.
    Keywords: Acoustics
    Type: Spinoff 1984; 102
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  • 48
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 14 (1976), S. 653-659 
    ISSN: 1741-0444
    Keywords: Acoustics ; Pneumograph ; Tidal volume ; Thoracic impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Un son de 200 Hz élaboré par un générateur d'ondes sinusoïdales a été utilisé pour surveiller la respiration. On a fait passer le son de la bouche au poumon, et le son émis a été détecté à travers la cage thoracique par un microphone de phonocardiogramme installé sur la paroi de la poitrine. La tension de sortie du microphone, représentée par sa valeur moyenne absolue, a varié en fonction de la respiration du sujet. Par rapport au volume aspiratoire ou expiratoire des gaz obtenus par une méthode classique, on a démontré que la variation de la sortie était proportionnelle à la modification du volume des gaz pulmonaires. Notre pneumographe acoustique nous a permis de mesurer non seulement les changements dans le volume des gaz pulmonaires, mais aussi la variation du niveau expiratoire terminal. On a examiné aussi les mécanismes des variations de la sortie et la linéarité du dispositif.
    Abstract: Zusammenfassung Ein Ton von 200 Hz von einem Sinuswellen-Generator wurde zur überwachung der Atmung verwendet. Der Ton wurde vom Mund in die Lunge geleitet, und das übertragene Geräusch wurde durch den Brustkorb über ein Phonokardiogramm-Mikrofon abgehört, das auf die Brustkorbwand gelegt wurde. Die Ausgangsspannung des Mikrofons, die durch ihren absoluten Mittelwert dargestellt wurde, änderte sich mit der Atmung des Patienten. Verglichen mit dem Gasvolumen bei der Einatmung oder Ausatmung, das durch ein konventionelles Verfahren erhalten wurde, zeigte es sich, daß die Änderung in der Ausgangsspannung proportional zur Änderung des Lungengasvolumens war. Mit unserem akustischen Pneumographen war es möglich, nicht nur die Änderung im Lungengasvolumen zu messen, sondern auch die Äanderung in der Stärke der Endausatmung. Der Mechanismus der Äanderungen in der Ausgangsspannung und die Linearität dieses Geräts wurden ebenfalls überprüft.
    Notes: Abstract A 200 Hz tone from a sinewave generator was utilised to monitor respiration. The sound was led into the lung from the mouth and the transmitted sound was detected through the thoracic cage by a phonocardiogram microphone fixed on the chest wall. The microphone output voltage, represented by its absolute mean value, varied with the respiration of the subject. Compared with the inspiratory or expiratory gas volume obtained by a conventional method, it was shown that the variation in the output was proportional to the change in pulmonary gas volume. With our acoustic pneumograph, it was possible to measure not only the change in pulmonary gas volume but also the variation in the end-expiratory level. The mechanisms of the changes in the output and the linearity of this device were also examined.
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  • 49
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 16 (1978), S. 437-442 
    ISSN: 1741-0444
    Keywords: Acoustics ; Diagnostic ; Instrumentation ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Les maladies arthritiques restent la cause la plus courante de troubles non mortels mais paralysants. Elles sont responsables de nombreuses heures de travail perdu. Le besoin de développer des outils pour détecter et maîtriser la maladie dès le début, est devenu plus urgent, à cause de la priorité accordée à certaines formes d'arthrite des personnes du troisième âge et du taux de longévité accru, en général, dans notre société. Toutefois, il n'existe pas actuellement d'outils cliniques non invasibles, qui puissent fournir une évaluation objective de la condition du cartilage articulaire pendant le développement de la maladie. Malheureusement, celui-ci est transparent à la radio, et la radiographie ne donne que des renseignementspost facto. Récemment, fut développée une technique electro-acoustique non invasible, qui donne une mesure objective de la condition du cartilage endommagé, grâce à la mesure de la puissance acoustique émise au niveau du genou. La fiabilité de cette méthode fut vérifiée in vivo sur des animaux, en modelant la maladie. Cette technique est d'un intérêt immédiat pour les médecins cliniciens, qui ont un besoin urgent d'un ‘outil’ plus objectif pour déterminer l'efficacité de certains médicaments ou des programmes de traitement de la maladie.
    Abstract: Zusammenfassung Die Arthritiserkrankungen sind noch immer die häufigsten Ursachen nichttötlich wirkender, krüppelnder Leiden. Ihnen sind viele verlorene Arbeitsstunden zuzuschreiben. Aufgrund des Vorherrschens einiger Formen von Arthritis bei den älteren Altersgruppen und der zunehmenden Langlebigkeit unserer Gesellschaft, wird die Notwendigkeit, Werkzeuge zur Früherkennung und Beobachtung zu entwickeln, immer dringlicher. Jedoch gibt es zur Zeit keine nichtangreifenden, klinischen Werkzeuge, die eine objektive Bewertung des Gelenkknorpelzustands während des Krankheitprozesses ermöglichen. Leider ist der Gelenkknorpel strahlendurchlässig und ergibt beim Röntgen nur eine post facto Information. Vor kurzem wurde eine nichtangreifende, elektroakustische Technik entwickelt, die ein objektives Maß an Beschädigung des Knorpels durch die durch das Knie gemessene und abgegebene akustische Kraft ergibt. Die Zuverlässigkeit dieses Vorgangs wurde durch einen in vivo Modellversuch mit dieser Krankheit an Tieren belegt. Diese Technik weckt sofort das Interesse aller Internisten, die dringend ein objektiveres Werkzeug benötigen, um die Wirkung bestimmter Medikamente und/oder Behandlungsprogramme während des Krankheitsverlaufs feststellen zu können.
    Notes: Abstract The arthritides continue to be the most common cause of non-fatal, crippling disorders. They account for many hours of lost work time. Because of the preference for some forms of arthritis for the older age groups and the increasing longevity of our society, the need to develop tools for early detection and monitoring are becoming more urgent. However, at present there are no noninvasive, clinical tools available that would provide an objective evaluation of the condition of the articular cartilage during the progress of the disease. Unfortunately, articular cartilage is radiolucent and X-ray gives onlypost facto information. Recently, a noninvasive electroacoustical technique was developed which gives an objective measure of the degree of cartilage damage through the measurement of knee emitted acoustic power. The reliability of the procedure was verified throughin vivo modelling of the disease using animals. This technique is of immediate interest to clinicians who urgently need a more objective ‘tool’ in the determination of the efficacy of certain drugs and/or treatment programmes during the course of the disease.
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  • 50
    ISSN: 0271-2091
    Keywords: Finite Elements ; Infinite Elements ; Acoustics ; Wave Propagation ; Radiation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Finite element models are presented for the calculation of near and far field acoustical radiation. These models are applied to the specific problem of fan noise radiation from axisymmetric turbofan inlets. In all cases conventional acoustic finite elements are used within an inner region close to the inlet. The far field is represented by infinite elements or wave envelope elements. Theory and results are presented for the case with zero mean flow. Comparisons of computed data with analytic solutions and measured values establish the utility of both the infinite element and wave envelope element schemes in determining the near field values of acoustical pressure. The wave envelope scheme is shown to be effective also in the far field. Both schemes use meshes an order of magnitude more sparse that would be required in conventional numerical discretizations, and may consequently be applied at modest computational cost.
    Additional Material: 16 Ill.
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