| Final Technical Report for ONR Contract N00014-88-K-0172 15 November 1987-14 November 1991 (California University, San Diego, La Jolla. Department of Physics) |
02 SEP 93 |
4 pages |
| Authors:
Roger Dashen; CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF PHYSICS
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 | In 1987 and 1988, Dan Wurmser (now at NRL) and I developed a new method for scattering from rough surfaces. There were several new results. The first was a new exact formula for the scattering amplitude which manifestly exhibits reciprocity. However, like all exact formulas it is useful only in conjunction with numerical work. On the other hand, this new formulation of the scattering problem lead to an approximate expression ... |
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| AFAR (Azores Fixed Acoustic Range) Measurements of Intensity and Intensity Moments |
SEP 86 |
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| Authors:
Stanley M. Flatte; Stephen A. Reynolds; Roger Dashen; Barry Buehler; Pat Maciejewski; CALIFORNIA UNIV SANTA CRUZ DEPT OF PHYSICS
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 | In an acoustic-oceanographic experiment (AFAR) performed near the Azores in 1975, frequencies from 400 to 4670 Hz were transmitted over a 35-km wholly refracted patch. In addition, a separate data set was gathered over a 3- km path in 1973. Measurements of the intensity coherence function of time and frequency, intensity moments, and the probability distribution of intensity are presented and compared with predictions of fluctuations due to internal waves. ... |
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| Path-Integral Treatment of Intensity Behavior for Rays in a Sound Channel |
SEP 86 |
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| Authors:
Stanley M. Flatte; Stephen A. Reynolds; Roger Dashen; CALIFORNIA UNIV SANTA CRUZ DEPT OF PHYSICS
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| The intensity coherence function (ICF) of the acoustic wave function from a point source is derived by the path-integral technique for transmission through internal waves in the presence of a sound channel. Separations in time are emphasized, although separations in transverse horizontal position, vertical position, and acoustic frequency are discussed. Approximate intensity coherence times, lengths, and bandwidths due to internal-wave fluctuations are derived. Analytic approximations suitable for computer coding are ... |
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| AFAR (Azores Fixed Acoustic Range) Measurements of Acoustic Mutual Coherence Functions of Time and Frequency |
MAY 85 |
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| Authors:
Stanley M. Flatte; Stephen A. Reynolds; Roger Dashen; Barry Buehler; Pat Maciejewski; LA JOLLA INST CA CENTER FOR THE STUDY OF NONLINEAR DYNAMICS
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| A joint acoustic-oceanographic experiment was performed near the Azores in 1975. Frequencies from 400-4670 Hz were transmitted over a 35 km wholly refracted path. In addition, a separate data set was gathered over a 3 km path in 1973. Measurements of the mutual coherence function of time and frequency, and measurements of the acoustic phase structure function are presented and compared with predictions of fluctuations due to internal waves. (Reprints) ... |
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| Path-Integral Treatment of Acoustic Mutual Coherence Functions for Rays in a Sound Channel |
MAY 85 |
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| Authors:
Roger Dashen; Stanley M. Flatte; Stephen A. Reynolds; LA JOLLA INST CA CENTER FOR THE STUDY OF NONLINEAR DYNAMICS
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| The mutual coherence function (MCF) of the acoustic wavefunction from a point source is derived by the path-integral technique for transmission in the presence of a sound channel. Separations in time, transverse horizontal position, vertical position, and acoustic frequency are treated. Approximate coherence times, lengths, and bandwidths due to internal-wave fluctuations are derived. The MCF of frequency is explicitly evaluated for fluctuations due to internal waves. The shape of an ... |
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| Intensity Moments by Path Integral Techniques for Wave Propagation Through Random Media, with Application to Sound in the Ocean |
JUL 83 |
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| Authors:
Stanley M. Flatte; David R. Bernstein; Roger Dashen; CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF PHYSICS
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| Using the formalism of path integrals, the intensity moments of waves propagated through anisotropic inhomogeneous random media in the presence of a deterministic wave speed variation can be formed. In the saturated scattering regime, intensity fluctuations are expected to be Rayleigh distributed to first order. A correction to Rayleigh statistics is calculated that results in a form for the intensity moments: = n factorial to the nth power (1 + ... |
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| Path Integrals for Waves in Random Media. |
MAY 1977 |
103 pages |
| Authors:
Roger Dashen; STANFORD RESEARCH INST MENLO PARK CALIF
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| The problem of wave propagation in a random medium is formulated in terms of Feynman's path integral. It turns out to be a powerful calculational tool. The emphasis is on propagation conditions where the rms (multiple) scattering angle is small but the log-intensity fluctuations are of order unity - the so-called saturated regime. It is shown that the intensity distribution is then approximately Rayleigh with calculable corrections. In an isotropic ... |
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| Report of the 1971 JASON Laser Summer Study. Volume II. Supporting Appendices A-M, |
AUG 1971 |
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| Authors:
John F. Asmus; Kenneth M. Case; Roger Dashen; Ali Javan; Paul Kelley; INSTITUTE FOR DEFENSE ANALYSES ARLINGTON VA JASON DIV
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| The volume contains a summary of the current state of the art in laser devices and associated technology, plus discussions of the current and potential uses of lasers in the following areas: medicine and biological research, communications, holography and information processing, chemical processing, atmospheric monitoring and air pollution detection, geophysics, industry, basic research in the physical sciences, and ignition of controlled thermonuclear reactions. The current status of laser safety standards ... |
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| Report of the 1971 JASON Laser Summer Study. Volume I. Recommendations and Conclusions, |
AUG 1971 |
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| Authors:
Kenneth Watson; Kenneth Case; Roger Dashen; Normal Kroll; Malvin Ruderman; INSTITUTE FOR DEFENSE ANALYSES ARLINGTON VA JASON DIV
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| All potential uses of lasers, civil and military, are reviewed: medicine and biological research, chemical processing, initiation of controlled thermonuclear reactions, communications, pollutant detection and monitoring, geoscience applications, holographic applications, manufacturing and related processes, and basic research. Recommendations are made concerning Federal encouragement, funding, and coordination of further effort in these area and in laser technology and device development. (Author) |
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| GENERATION AND AIRBORNE DETECTION OF INTERNAL WAVES FROM AN OBJECT MOVING THROUGH A STRATIFIED OCEAN. VOLUME II. SUPPORTING ANALYSES, |
APR 1969 |
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| Authors:
Walter H. Munk; Curtis G. Callan Jr.; Roger Dashen; James B. Hartle; Joseph B. Keller; INSTITUTE FOR DEFENSE ANALYSES ARLINGTON VA JASON DIV
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| This study deals with fundamentals in the performance of airborne sensors for detecting the wake from the passage of a submarine through stratified water. No attempt has been made to imbed the theoretical results in an operational setting. (Author) |
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