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Thousand Oaks, CA, United States

Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 99.93K | Year: 2006

We propose to develop high-fidelity numerical simulation tools to be used in the analysis and assessment of bone conduction of sound in the human head and the desigh of noise protection devices. The proposed approach utilizes boundary and volumetric integral equation methods, and will constitute an extension of our currently developed approach from acoustics to coupled elasticity-theory and acoustics formulation.

Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 99.96K | Year: 2005

We intend to develop an efficient solution scheme applicable to numerical modeling of objects in large complex environments, which would provide an adequate accuracy at a cost significantly lower than rigorous solution methods based on state-of-the-art matrix compression methods (multilevel Fast Multipole Method (FMM) or Adaptive Integral Method (AIM)). During Phase I, we shall develop a self-contained software prototype, which will demonstrate the feasibility of the proposed approach. The algorithms and the software we propose to develop will make a significant advancement in the numerical simulation software for prediction of radar signatures and radiation patterns of object embedded in large, complex scenes. The proposed approach will overcome limitations of the conventional MoM as well as of the compressed (FMM-based, AIM-based) algorithms. The algorithms we propose will consist of the following elements: (i) a fast algorithm for the coupling between the substystem S_1 and the environment S_2 achieving its performance through the utilization of an asymptotic evaluation of the FMM-like translation operators and the full or partial parameterization of the environement in terms of basis functions defined on large supports (the proposed coupling scheme is general and can be implemented in the context of different multiple scattering expansions which were proposed in the past), (ii) implementaion of the fast coupling scheme in the context of a particular realization of rapidly convergent multiple scattering scheme based on a suitable arrangement/grouping of short-range and long-range interaction contributions.

Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 99.99K | Year: 2005

The objective of this proposal is to make a significant advancement in the development of software for the prediction of radiation patterns of antennas mounted on large platforms. The proposed approach will combine fast rigorous and asymptotic solution methods with a suitably constructed direct and iterative solvers. The proposed scheme will significantly reduce the computational cost of the solution of a broad spectrum of antenna design problems without compromising its accuracy.

Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 742.63K | Year: 2008

We propose to develop high fidelity software tools which would allow identification and understanding of the relevant bioacoustic and psychacoustic mechanisms responsible for the transition of acoustic energy through non-airborne pathways to the cochlea and significantly reduce the cost of design of noise suppression devices. The principal numerical tool we propose to use is the fast integral equation solver for elasto-acoustic media, development of which we initiated during Phase I of this project. The following features make the choice of our solver uniquely suited to the proposed numerical simulations: - the non-lossy compression technique, which allows to reduce, without compromising accuracy of the solution, the memory and computer time requirements from O(N^3) to O(Nlog N), where N is the number of unknowns (we note that in the envisioned numerical simulations of the acoustic wave propagating through the human head, the expected number of unknowns can be of the order of one to ten millions; thus the compression technique we propose to use would reduce the memory and computational complexity by a gigantic factor of 10^{12} - 10^{14}, and hence make the realistic numerical simulations tractable), - numerical accuracy over a sufficient dynamic range to describe the alternative sound propagation paths (empirically, it is known that the intensity of the bone-conducted sound is about 30 - 40 dB lower than that of the air-conduction mechanism, - ability to simulate regions/surfaces of different material properties, - applicability of the compression technique to the entire interval of acoustic frequencies in which the problem size ranges from sub-wavelength (fraction of a wavelength) to moderate (several wavelengths), - parallel, scalable implementation of the algorithm which reduces the wall clock time of the simulations.

Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 744.77K | Year: 2010

We propose to develop a new autofocus method applicable to large-scene surveillance with circular SAR. Our work constitutes a continuation, full implementation, and extensions of the new autofocus algorithm we developed and successfully tested during Phase I. The proposed method is applicable to large apertures and corrects effects of fine-scale (sub-wavelength) deviations in the platform motion along arbitrary curved trajectories. The proposed method will be accelerated with suitable fast imaging techniques. It will be also extended to multi-pass circular SAR measurements and augmented with autofocus methods for moving targets. BENEFIT: The proposed method will significantly enhance the capabilities of DoD SAR imaging technology. It will be applicable in a number of commercial and national security surveillance programs, e.g., in border monitoring.

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