the findings of these experiments. The model was subsequently tested with a final experiment; good qualitative and quantitative agreement was found.

ACKNOWLEDGMENT

Dissertation directed by C. G. Rice, Institute of Sound and Vibration Research, University of Southampton, England.

Technical reports [43.10. Qs]

The following technical reports may be obtained from the Na- tional Technical Information Service, Springfield, VA 22151 under the order numbers listed.

Extensions of the Parabolic Equation Model for High-Angle Bot- tom-Interacting Paths--L. B. Dozier and C. W. Spofford, Science Applications Inc., McLean, VA, December 1977, 27 pp. Here the specific problem of interest is the propagation of high angles over large distances where the energy is refracted in the ocean- bottom sediments (rather than reflected from a hard interface). The principal difficulty with PE in such geometries is that a steep angle effectively propagates with the period of a shallower angle since the horizontal component of its phase velocity is less than it should be. Hence the ray period, or cycle distance, is too large. For water-borne paths this problem was largely removed by CMOD. The relaxation of the CMOD convergence-zone constraint permits certain liberties to be taken with the sound-speed proœfie in the bottom which could not be considered in the water column. Order No. AD-A052890.

A Note on the Inverse Source Problem--N. Bleistein and J. K.

Cohen, Denver Univ. Colo. Dept. of Mathematics, December 1977, 9 pp. In an earlier paper, the authors derived a Fredholm integral equation of the first kind for the solution of the inverse source problem for acoustic waves. The eigenvalues of this equation were shown to converge rapidly to zero and also to include zero. Thus, the solution was shown to be nonunique and even the particular part of the solution of that equation was ill conditioned. In this note it is shown how to obtain the nontrivial information of that

integral equation in a well-conditioned manner. [Order No. AD- A052909.]

A New Model for the Flat Conductor Electromagnetic Saw Trans- ducer--J. C. Sethares and T. L. Szabo, Rome Air Development Center Hanscorn AFB Mass. Deputy for Electronic Technology, September 1977, 9 pp. Previous models for Rayleigh- and Lamb- wave electromagnetic transducers have been based on the assump- tion that the current distribution in each transducer conductor is

uniform. The authors present solutions for the dynamic magnetic fields surrounding an array of flat conductors above a ground plane in which the current distribution is allowed to vary. The resulting solutions are used to calculate space-harmonic curves and to derive a new transducer model including electrical inductance, eddy current resistance, acoustic impedance, and transducer effi- ciency. [Order No. AD-A053212.]

Proceedings of the Workshop off Acoustic Attenuation Materials

Systems--National Materials Advisory Board (Nas-Nae), Washing- ton, DC 1978, 152 pp. The choice and use of materials for acous- tical attenuation is an important technical problem as well as of great interest for improving comfort and working efficiency. Al- though the major effort in this field is at ambient conditions and in the audio frequency range, there are important applications that involve widely varying pressures, temperatures and frequencies along with other requirements peculiar to the particular use. Among current problems in the control of acoustic energy are those asso- ciated with such diverse applications as ultrasonic devices, space vehicles, and deep-diving oceanographic vehicles. Each of these, of course, may also have other quite different requirements of the acoustical materials in such properties as density, pressure re- sponses, and flammability. [Order No. AD-A053337.]

Using Aerodynamic Configuration Charts and Calculators or Slide Rules--H. W. Carlson, National Aeronaua'cs and Space Administra- tion, Langley Research Center, Langley Station, VA, March 1978, 50 pp. Sonic boom overpressures and signature duration may be predicted for the entire affected ground area for a wide variety of supersonic airplane configurations and •pacecraft operating at alti- tudes up to 76 km in level flight or in moderate climbing or de- scending flight paths. The outlined procedure relies to a great ex- tent on the use of charts to provide generation and propagation factors for use in relatively simple expressions for signature calcu- lation. Computational requirements can be met by hand-held sci- entific calculators, or even by slide rules. A variety of correlations of predicted and measured sonic-boom data for airplanes and spacecraft serve to demonstrate the applicability of the simplified method. [Order No. N78-20078.]

547 J. Acoust. Soc. Am. 65(2), Feb. 1979; 0001-4966/79/020547-01500.80; ̧ 1979 Acoust. Soc. Am.; Notes and Briefs 547

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