Harvey C. Woodsum

Method and apparatus for determining and forming delayed waveforms for forming transmitting or receiving beams for an acoustic system array of transmitting or receiving elements for imaging in non-homogenous/non-uniform mediums

An acoustic imaging system for forming acoustic beams approximating an optimum acoustic beam for the directional transmission or reception of acoustic energy. Maximum and minimum dependent beamform factors are determined from initial beamform factors and an initial parent population of chromosomes is generated, each chromosome including a gene corresponding to a dependent beamform factor and representing an initial candidate beam and subsequent parent populations are generated by cloning of the surviving populations. A child population is generated by exchanging statistically selected pairs of genes of the parent population and generating a mutated population. A surviving population is selected from the mutated population of the mutated population with a fitness criteria. When a chromosome of the surviving population meets the solution criteria, the genes of the surviving population having the best match to the fitness criteria are selected to forming a beam.

Bistatic/monostatic sonar fence

A sonar system has at least two separated bottom-mounted acoustic modules, each module including a projector for generating horizontal sound beam, a vertical line receive array for monostatic and bistatic detection, and a high frequency, upward-directed transducer for providing a steerable vertical beam to ensure full water column coverage by the use of surface reflections to minimize shadowing caused by high relief bottom topography.

Steerable thermoacoustic array

This invention is a steerable thermoacoustic array system for directing information between an object that is above the surface of the water and a sound detector that is beneath the surface of the water. The foregoing system comprises a laser or particle accelerator that is located above the waters surface. The laser or particle beam produces a light beam or particle beam which contains information that is moved along a small layer of water at the air/water interface at a speed equal to the speed of sound in water divided by the steering angle of the laser so that the light beam or particle beam is absorbed by the water causing the water to expand and produce a series of acousitic Braves that constructively interfere with each other and travel towards the sound detector.

Fourier‐operator methods for parametric array analysis: Theory versus Experiment

Fourier operator methods pertaining to nonlinear scattering of sound by sound, previously developed by the present authors [J. Acoust. Soc. Am. 95(5), part 2 (2PA14)], have been refined into computer codes, to allow prediction of parametric array performance over a wide range of circumstances, to include parametric array far field and near field, with linear medium attenuation as well as saturation effects fully accounted for. Experimental data sets have been obtained in the course of parametric source calibrations, which allow precise comparison with the new model, showing favorable comparisons in all cases.

Enhancement of a general solution to Lighthill-Westervelt nonlinear acoustic equation to the cases of inhomogeneous and random media

A general solution to the Lighthill-Westervelt equation of nonlinear acoustics, previously developed and successfully applied to model the scattering of sound by sound and to the parametric array, has been generalized further for use in the cases of inhomogeneous and random media. The form of the solution makes use of an exact inverse differential operator in combination with a sequence of perturbation terms that comprise the multiple orders of nonlinear acoustic scattering to arbitrary order. Integration techniques have been developed which allow accurate, approximate, analytical solutions under particular circumstances. These solutions are shown to reduce to other previously known solutions in the appropriate limits.

Optimized hermetic transform beam-forming of acoustic arrays via cascaded spatial filter arrangements derived using a chimerical evolutionary genetic algorithm

Hermetic transforms are complex matrices, having particular mathematical properties, that have recently been introduced to the field of acoustic array signal processing. Cascade sequences of Hermetic transform matrices have been shown to have direct utility in accomplishing spatial filtering and beam-forming of data from oversampled arrays. The present work details the adaptation of techniques previously shown to be successful in the processing of radio-wave phased-array antenna systems [Woodsum et al., 16th International Conference on Cognitive and Neural Systems (2012)] to the processing of sampled digital data from acoustic arrays. As in our earlier work, the use of a Chimerical, Evolutionary, Genetic Algorithm, having a “feature seeking” fitness function, is retained, for deriving optimal multiplicative arrangements of non-commuting elemental transform matrices. Each elemental matrix represents a spatial “pole” or “zero,” and cascaded arrangements of these are utilized to create a desired spatial patt...

Hermetic array processing for underwater echo‐ranging systems.

Hermetic array processing provides enhanced beam width resolution, as well as correspondingly greater gain against ambient noise and reverberation, without the requirement of data‐adaptive processing. The technique derives from the discrete hermetic (spectral) transform, and has been applied to an underwater echo‐ranging system deployed in an underwater security system. Theoretical and empirical results are also described, and the impact on sonar system performance is presented. A description of practical implementation issues and a comparison to traditional adaptive beamforming are shown.

Results of hermetic transform signal processing to enhance the resolution and array gain of underwater acoustic arrays.

Results of applying the discrete hermetic transform (DHT) to the beamforming of underwater acoustic arrays are presented in terms of measured reductions in beam mainlobe width as well as the associated improvement in directivity index/array gain for practical cases of interest. Application of the DHT to array beamforming is shown to produce substantially enhanced resolution relative to the conventional beamforming diffraction limit as well as significant enhancement in array gain against ambient noise, without the use of data adaptive or nonlinear processing. As a result, enhanced sonar signal detection and/or the ability to use substantially smaller than normal arrays can be accomplished through the judicious use of DHT based beamforming algorithms. Results are favorably compared to theoretical predictions of algorithm performance.

Acoustic performance predictions via a general theory for the scattering of sound by sound with experimental data from an operational parametric sonar system.

In results previously described [J. Acoust. Soc. Am. 95, 2PA14 (1994)], a general theory for the scattering of sound by sound has been developed as an exact solution to the Lighthill–Westervelt equation of nonlinear acoustics. Most recently, a computer model based on this theory has been developed in order to support design analysis and performance prediction for parametric array echo‐ranging systems and has been applied to a currently deployed operational parametric sonar. The present theory and model have the potential to support a wide range of analyses, including development of beam patterns, source levels, transient waveform effects, as well as the analysis of scattering of sound by sound from intersecting beams as well as the prediction of performance of parametric sources having multiple simultaneous transmit beams. Both the theoretical basis for the model and agreement with experimental data are presented.

Theoretical analyis of Schwinger's conjecture on sonoluminescence in relation to the boosting of sonluminescent transduction efficiency.

In a previous paper [Spring ASA, Salt Lake (2007)], we have considered the potential viability of Schwinger’s conjecture that sonoluminescent light radiation, which results from acoustically developed cavitation, derives from zero‐point energy of the vacuum. In our prior paper, we considered the nonlinear interaction of zero‐point electromagnetic modes in a cavitating bubble, through the Euler–Heisenberg theory for the scattering of light by light. Good agreement was found between theory and experiment with regard to both the efficiency and spectrum of the sonoluminescent radiation generated using a single acoustic frequency. We now consider a comparison of this theory with other experiments [Phys. Rev. Lett. 81, 1961–1964 (1998)] which have demonstrated that cavitation bubbles created with acoustic waves having both first and second harmonics present, and having particular amplitude and phase arrangements, can result in sonoluminescent transduction efficiency increases of up to 300%. At this point in tim...