| Fundamentals of Distributed, Networked Military Forces and the Engineering of Distributed Systems |
09 MAY 2002 |
23 pages |
| Authors:
Jeffrey R. Cares; Raymond J. Christian; Robert C. Manke; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
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 | Defense community innovators have proposed concepts for using cutting-edge technologies to solve long-standing military challenges, including destruction of time-critical targets, theater-wide surveillance, power projection, and access to littorals. These concepts assume great benefits from networking that will enable military advantage via the use of distributed systems. However, the advantages of networking, as well as the implications of engineering distributed systems, have not been fully articulated. This report describes how distributed, ... |
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| Revisions to an Empirical Surface Loss Model Using a Correction for pH- Dependent Attenuation |
29 SEP 94 |
22 pages |
| Authors:
Raymond J. Christian; David G. Williams; David G. Browning; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
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| This document contains the presentation entitled 'Revisions to an Empirical Surface Loss Model Using a Correction for pH-Dependent Attenuation,' presented at the 127th meeting of the Acoustical Society of America, 7 June 1994, Cambridge, Massachusetts. Absorption, Bubbles, Surface Duct, Attenuation, Rough Surface Scattering, Surface Loss |
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| NUWC Shallow Water Curtain Effect with Biot Bottom Loss: System Impact |
25 OCT 93 |
14 pages |
| Authors:
David G. Browning; Raymond J. Christian; Peter D. Herstein; Joseph M. Monti; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV NEW LONDON CT NEW LONDON DETACHMENT
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| The Curtain Effect was originally conceived to compare the relative rates of loss of spreading and attenuation in deep water in order to estimate possible attainable acoustic detection ranges. It was later modified to compare spreading, attenuation, and bottom loss in shallow water for the same purpose (NUWC-NL Technical Document 4009, 2 March 1992). We now compare the Shallow Water Curtain under strongly downward refracting conditions for various source/ receiver ... |
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| The Influence of a Bubbly Layer on Near-Surface Acoustic Propagation and Surface Loss Modeling |
11 DEC 92 |
23 pages |
| Authors:
Raymond J. Christian; NAVAL UNDERSEA WARFARE CENTER NEW LONDON CT NEW LONDON DETACHMENT
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| The impact of refraction, attenuation, and scattering due to a near- surface bubbly layer on acoustic propagation modeling can be significant in sensitive surface duct and shallow water environments. Hall (J. Acoustic. Soc. Am. 86(3), September 1989) presents a semi-empirical acoustic model to determine the propagation effects of the bubbly layer on one-way horizontal transmission in a surface duct. Expressions for the depth-dependent complex sound speed and attenuation are used ... |
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| The Curtain Effect in a Multiple Convergence Zone Environment: Part 1. Implications for Ambient Noise |
24 JAN 91 |
16 pages |
| Authors:
David G. Browning; Raymond J. Christian; NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT NEW LONDON LAB
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| Over multiple convergence zone propagation ranges the relative spreading loss per zone, although initially high, decreases with range. The other major component of propagation loss, attenuation, remains unchanged and eventually becomes greater than the rate of spreading loss. The range at which this crossover occurs is highly frequency dependent. At low frequencies the curtain effect occurs at long ranges; this allows sources or scatterers in the second convergence zone or ... |
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| Low Frequency Ambient Noise Near Bermuda: Filling in the Notch |
27 MAY 87 |
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| Authors:
William A. Von Winkle; David G. Browning; Raymond J. Christian; A. D. Cobb; NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT NEW LONDON LAB
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 | Ambient noise models which assume no significant wind-generated noise mechanism in the 5- to 100-Hz frequency range predict a notch in noise levels, between shipping and microseismic noise, at approximately 10 Hz. Data are presented for the frequency range 3-200 Hz that show that this notch fills in at increasing wind speeds and is entirely eliminated above 35 knots for a North Atlantic Ocean location near Bermuda. These results are ... |
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| Limitations of Sound Propagation in the Ocean: The Curtain Effect |
05 MAR 87 |
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| Authors:
David G. Browning; John J. Hanrahan; Raymond J. Christian; Robert H. Mellen; NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT NEW LONDON LAB
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| Although initially very high, the rate of spreading loss decreased rapidly with range, while the rate of attenuation remains constant for a given frequency. At increasing ranges the two loss curves cross, with attenuation becoming the dominant mechanism. This results in a 'curtain effect' due to rapidly increasing propagation loss. Examples are given of convergence zones obtainable as a function of frequency for various oceans and of the transition between ... |
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