bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient use of particle filters for multi-source data fusion in decentralized sensor networks.
Authors: Haney Philip J. , Edelson Geoffrey S.
Published: October 2009

A highly-scalable Bayesian approach to the problem of performing multi-source data fusion and target tracking in decentralized sensor networks is presented. Previous applications of decentralized data fusion have generally been restricted to uni-modal/uni-source sensor networks using Gaussian based approaches, such as the Kalman or information filter. However, with recent interest to employ complex, multi-modal/multi-source sensors which potentially exhibit observation and/or process non-linearities along with non-Gaussian distributions, the need to develop a more generalized and scalable method of decentralized data fusion using particle filters is required. The probabilistic approach featured in this work provides the ability to seamlessly integrate and efficiently fuse multi-source sensor data in the absence of any linearity and/or normality constraints. The architecture is fully decentralized and provides a methodology that scales extremely well to any growth in the number of targets or region of coverage. This multi-source data fusion architecture is capable of providing high-precision tracking performance in complex, non-linear/non-Gaussian operating environments. In addition, the architecture provides an unprecedented scaling capability for decentralized sensor networks as compared to similar architectures which communicate information using particle data, Gaussian mixture models, or Parzen density estimators.
Comparison of particle filter and histogram filter performance for passive sonar localization.
Authors: Jemmott Colin W. , Culver R. Lee , Langelaan Jack W.
Published: October 2009

A number of extensions of the famous Kalman filter exist for recursive Bayesian estimation of state vectors with nonlinear update equations and non-Gaussian prior probability density functions. Two of the most powerful are the particle filter, which uses a direct Monte Carlo approach, and the histogram filter, which uses a grid-based approach. Both filters are numerical implementations of recursive Bayesian estimation. The histogram filter uses a grid based approach that is analogous to midpoint rectangular integration, while the particle filter uses a Monte Carlo approach. Their performance is compared for a passive, model-based localization problem in which the target is broadcasting a low-frequency tonal signal while moving through a shallow water waveguide. The state vector being estimated includes range, depth, and source level. Target dynamic models allow for slow changes in velocity, depth, or source level. The example uses RAM realizations with additive noise as a synthetic received signal. In situations where computational power is restricted, the particle filter consistently outperforms the histogram filter in localizing the target. However, with sufficient computational power the performance is equivalent. [This work was sponsored by ONR Undersea Signal Processing.]
Hybrid grid-particle Bayesian tracking with intelligent likelihood sampling.
Authors: Aughenbaugh Jason M. , La Cour Brian R.
Published: October 2009

Characteristic of anti-submarine warfare is the goal of detecting and localizing a single target in a noisy environment in which subtle clues in the signals are essential for differentiating clutter and the target of interest. Bayesian inference is a general framework for performing target tracking in these applications, but both particle filter and grid-based models of the distributions have limitations. Particle filters involve fast motion updates but slow measurement updates. Grid-based models allow for faster measurement updates at the cost of slower motion updates. A particle filter provides adaptive modeling of the prior and posterior distributions, but both methods can fail to provide detailed sampling of the likelihood function in crucial regions, and these small details are often the key to mitigating clutter in active systems. In this paper, a hybrid grid-particle model with intelligent likelihood sampling is introduced. The density is approximated by a fixed grid, and the motion update is implemented using a particle-based sampling of the grid. The integral of the likelihood over each grid cell is calculated in an intelligent manner that adapts to the received measurements and the known sensor model properties. [This work was supported by the Office of Naval Research Contract No. N00014-06-G-0218-01.]
A particle filtering approach for multipath arrival time estimation from acoustic time series.
Authors: Jain Rashi , Michalopoulou Zoi-Heleni
Published: October 2009

Accurately estimating arrival times from acoustic time series in the ocean leads to a wealth of information on the geometry of the sound propagation environment and environmental parameters such as sound speed in sediments. In this work, a sequential Monte Carlo method is developed that treats the spatial variation of signal paths as moving targets, dynamically modeling their temporal location at spatially separated receiving phones. The spatial rather than the temporal sequential variability of the problem permits the application of smoothing techniques to the arrival time estimates, significantly reducing uncertainty. The results are compared to maximum likelihood estimates for the same test cases; the comparison demonstrates an advantage in using the proposed approach, which can be employed for reduction in uncertainty in arrival time estimation and, consequently, in geometric and geoacoustic inversion. It is further demonstrated how this method accurately extracts path amplitudes, which can then be employed for attenuation inversion. This method, suitable for environments with an unknown number of arriving paths, is also tested successfully on Haro Strait Primer Experiment and Shallow Water 06 data. [Work supported by ONR.]
A level set method for high-frequency ocean acoustic propagation.
Authors: Martinelli Sheri , Fredricks Andrew
Published: October 2009

The level set method due to Osher and Sethian [J. Comput. Phys. 79, 12–49 (1988)] provides a way to obtain fixed grid solutions to the high-frequency wave equation. Instead of tracing several rays from the source, the level set method embeds the entire wavefront implicitly in the phase space and propagates it according to the velocity field determined by the local ray direction, thus avoiding the complications involved in the spatial reconstruction of the wavefronts from diverging and scattered rays. A level set method has been developed and implemented as a fixed-grid alternative to ray tracing to solve the high-frequency equation for the acoustic phase. Furthermore, an efficient ray-based method that takes advantage of the full knowledge of the wavefronts afforded by the level set solution to the Eikonal equation has been developed to solve for the geometric spreading term in the expansion. Preliminary results are presented with comparisons to ray tracing and full wave equation solutions. [Work supported by ONR.]
Incorporating array processing to improve resolution of ambient noise data cross-correlation along a horizontal array.
Authors: Fried Stephanie E. , Kuperman William A.
Published: October 2009

Numerous authors have shown that the cross-correlation of ambient noise recordings at two points can produce an approximation of the Green’s function between those points. The resolution of the cross-correlation is fundamentally limited by the characteristics of the noise field and the changing environment. In order to make this technique the most effective, we wish to limit the time needed to extract the desired environmental information. To that end, array processing techniques can be adapted to work with the noise cross-correlation function taken along a horizontal array to decrease the time needed to resolve multiple individual returns. For a given noise field, beam forming between horizontal arrays is effective in reducing the time needed to identify both the direct and single-bounce surface reflection paths.
Acoustic communication from a moving source: Data results and model simulations.
Authors: Song Aijun , Badiey Mohsen , Hsieh Julia , Rouseff Daniel , Song H.-C. , Hodgkiss William
Published: October 2009

Acoustic communication can provide a flexible way to exchange information among moving platforms in the ocean. However, source-receiver motion poses additional difficulties to high-rate coherent communication. During the KAM08 experiment conducted in the summer of 2008, high-frequency (greater than 10-kHz) communication sequences were transmitted by a towed source and observed by multiple hydrophone arrays in the shallow water region west of Kauai, HI. Using time reversal combining followed by a single channel decision feedback equalizer aided by Doppler and channel tracking, reliable communication was achieved for different source-receiver geometries for the moving source. Further, the ray-based ocean acoustic time series simulation model sonar simulation toolset with a rough sea surface and moving source configuration was used to simulate the acoustic channel and received communication data. Simulated signals and demodulated results were compared with experimental data in order to examine the factors that significantly impede communication effectiveness for moving platforms. [Work supported by ONR 321OA.]
Passive acoustic classification of vessels in the Hudson River.
Authors: Zucker Michael L. , Sedunov Alexander , Zhdanov Vladimir , Sutin Alexander
Published: October 2009

Stevens Institute of Technology is conducting research aimed at the development of a low-cost passive acoustic system for detection and classification of underwater and surface threats. The experimental system is comprised of a hydrophone array and a stand alone acoustic buoy. Video and photographs of the passing ships were also captured simultaneously during the acoustic measurements. For classification purposes special attention was paid to extraction of the specific parameters of vessel acoustic signatures in high-frequency band (10–60 kHz) using detection of envelope modulation on noise algorithm. The spectrum of the noise envelope contains shaft and blade frequencies and their harmonics. Parameters extracted include the frequency of the fundamental peak of the ship noise emission, the amplitude modulation of the fundamental tone, the number of peaks found in the spectrum, the slope of the spectral peaks, as well as the calculation of the total harmonic distortion. Parameters extracted from various records are then plotted together and their statistical analysis was applied for surface ship classification. [This work was supported by the U.S. Department of Homeland Security under Grant No. 2008-ST-061-ML0002].
Toward acoustic tomography in a shallow estuary.
Authors: Sutin Alexander , Blumberg Alan , Fillinger Laurent , Sedunov Nikolay , Sedunov Alexander
Published: October 2009

There is presently much interest in understanding the hydrophysical parameters in a shallow estuary. The importance of predicting the currents in Hudson River was demonstrated during rescue and recovery of the USAirways aircraft crashed in the river on January 15, 2009. Usually hydrophysical parameters are measured by fixed location sensors that cannot provide high spatial resolution. Acoustic tomography, on the other hand, can map the hydrophysical parameters. Recently, Stevens Institute of Technology using their fully equipped underwater facility including two surface vessels has conducted the first feasibility test on acoustic tomography. The test was conducted in the Hudson River, a shallow estuary that is connected to New York Harbor. The test used an estimate of the differential time of flight of an acoustical signal in opposite directions between two nodes. One node was at a fixed location, while the other was on a research vessel drifting on the other side of the river. An application of a frequency sweep signal (30–90 kHz) and a cross-correlation technique allowed measurements of the difference in time of flight of the acoustic signals propagated in opposite directions that is proportional to the current in the river. The average current speed was estimated and correlated well with current measurements available from the Stevens Observing and Prediction System. [This work was supported by ONR Project #N00014-05-1-0632: Na.]
Fundamental acoustics education and applications.
Authors: Sanders James V.
Published: October 2009

Teaching acoustics at the graduate level to professional naval officers, who, after graduation, will go back to driving ships, submarines, and airplanes, as well as other professional naval disciplines, offers a unique challenge. The Naval Postgraduate School has been the home for over 50 years of the textbook, Fundamentals of Acoustics, originally written by Lawrence Kinsler and Austin Frey and revised in later editions by Alan Coppens and James Sanders. Updating a textbook that is suitable for undergraduate and graduate students in a multitude of disciplines at civilian institutions and also suitable for use by naval officers interested in underwater acoustics continues to be most challenging. Solutions to these and other teaching responsibilities in these environments, including long distance learning, are discussed.
Biomedical photoacoustics: From sensing to imaging to therapy.
Authors: Emelianov Stanislav
Published: October 2009

Photoacoustics is a wonder as the lightning and thunder once were. Indeed, the absorbed short laser light pulses can generate sound. Utilizing this photoacoustic effect, researchers are now combining photonics with ultrasound technologies, nanoscience, and molecular biology to develop new approaches in molecular imaging and therapy. In photoacoustic imaging, the tissue is irradiated with non-ionizing laser pulses. The deep-penetrating photons are preferentially absorbed within the tissue and, through thermoelastic expansion, the photoacoustic transients are generated. Using acoustic sensors, these photoacoustic waves are then detected at the tissue surface to assess the strength and distribution of optically induced internal sound sources. Photoacoustic imaging can be seamlessly fused with ultrasound imaging, taking full advantage of the many synergistic features of these systems. Furthermore, using bioconjugated nanoparticles with high optical absorption, events at the molecular and cellular levels can be visualized. In this presentation, the basic physics will be described to introduce biomedical photoacoustics. We will then discuss experimental aspects of photoacoustic sensing and imaging including ultrasound/photoacoustic hardware, signal and image processing algorithms, etc. Techniques to synthesize molecular contrast agents will be overviewed. Finally, we will demonstrate and discuss biomedical and clinical applications of the combined ultrasound and photoacoustic imaging ranging from diagnostics to therapeutics.
Hot topics in noise.
Authors: Timmerman Nancy S.
Published: October 2009

Noise as a topic is, perhaps, the most politically charged of all areas of acoustics. This paper will review some of the items of current interest. Recent work in this field includes community noise and vibration from transportation (air and highway) and from sustainable energy projects, in particular, wind turbines; use of an audibility criterion within the National Parks; and use of the “soundscape” to get away from the negative connotations of the word “noise.” Codes and standards continuing to be developed include recent criteria for “green building” (LEED) certification for hospitals and schools. Cost credit can be taken for reduction in energy use resulting from noise control. Electronic miniaturization has moved recreational “boom box” noise to in-ear monitors, at the possible detriment of the users. These topics will be addressed as time permits.
Spatial correlation in a diffuse field generated by random point masses.
Authors: Choi Wonjae , Woodhouse Jim , Langley Robin
Published: October 2009

This paper considers spatial correlation in a random subsystem. In statistical energy analysis, a subsystem is modeled as a diffuse field, which can be generated by irregular boundaries or scatterers. This paper considers the case where waves are scattered by irregularities inside the subsystem and the boundaries remain deterministic. The uncertainties are parametrized by number and size of random point masses, and the effect on the spatial correlation function between two points in the random subsystem is investigated in the mid-high-frequency range. The scattering effect of one point mass is introduced with point impedance theory, and then the average effect along a wave path is derived so that the statistical loss factor is obtained. In addition, the correlation function is expressed explicitly in terms of a Green function with the aid of the Lagrange–Rayleigh–Ritz method. In the correlation the first few boundary reflections should be included as a minimum in order to cover the whole area of the system, which leads to local variation within the system. The estimation shows good agreement with Monte Carlo simulation of a random plate.
The Nyquist spatial sampling requirement in nearfield acoustical holography.
Authors: Dziklinski Richard , Wu Sean
Published: October 2009

Numerical simulations of Fourier acoustics and Helmholtz equation least squares (HELS) based NAH to visualize incoherent point sources separated by 6.25 mm are presented. The acoustic pressure measurements are taken over a 50 × 50 mm2 plane at different stand-off distances under various signal to noise ratios (SNRs). The considered source frequencies are well above 9 kHz. For Fourier acoustics based NAH, an 11 × 11 microphone array with 5 mm microphone spacing is used to collect the input data. Results show that Fourier acoustics based NAH encounters great challenges in locating these sources as the frequency and stand-off distance increase and SNR decreases unless regularization is used. On the other hand, a 5 × 5 microphone array with 12.5-mm microphone spacing is used for HELS under the same conditions without regularization. Clearly, the Nyquist spatial sampling requirement is violated in this case. Nevertheless, if the goal is to identify the locations of discrete airborne sources rather than reconstructing precise sources amplitudes, HELS can still yield satisfactory results. Results show that HELS is capable of locating the discrete airborne sources with a high spatial resolution (<± 2.5 mm) when stand-off distance is 10 mm and SNR is 10 dB.
Continuous-scan vibrometry technique for broadband vibration measurements with high spatial detail.
Authors: Allen Matthew S.
Published: October 2009

Recent works by the author and others have shown that one can estimate the mode shapes of a structure with remarkable spatial detail in a short time by sweeping a laser vibrometer continuously over the surface of the structure in a periodic fashion. The highly detailed spatial shapes that this method identifies may aid in locating damage or in understanding mismatch between an analytical model and the experimental hardware. Previous works have developed continuous-scan vibrometry methods for transient response measurements and pure sinusoidal excitation. This work treats measurements from structures excited with a measured, broadband forcing function. The approach amounts to a non-parametric estimator for the state transition matrix (analogous to the transfer function) of the time-periodic system. The method is evaluated using simulated measurements from a time-periodic system and using continuous-scan vibrometer measurements from an air conditioner condenser fan.
On modeling the intra-model, infinite seawater acoustic propagation path of undersea vehicles in statistical energy analysis.
Authors: Koch Robert M.
Published: October 2009

Statistical energy analysis (SEA) modeling has been utilized for decades toward the prediction of both self- and radiated noise behaviors of undersea vehicles such as submarines, torpedoes, and unmanned underwater vehicles. Since these vehicles operate in a semi-infinite or infinite seawater environment, it is difficult in SEA to account for any “intra-model” acoustic propagation through this infinite seawater path. For example, an important source of undersea vehicle self-noise arises due to acoustic propagation through the seawater environment from the vehicle’s aft propulsion system to the vehicle’s nose where the array is oftentimes located. To date, there has been no standard method published in the literature for how to accurately handle this important acoustic propagation path in SEA. The present paper investigates and compares several approaches that have been employed for properly accounting for aft-to-forward acoustic propagation through this infinite seawater environment path both for fully-wetted and supercavitating, high-speed undersea vehicle SEA models. A new hybrid method employing both finite acoustic volume and semi-infinite SEA acoustic elements has recently shown promise and is presented for discussion.
Viscoelastic properties of phonosurgical biomaterials at phonatory frequencies.
Authors: Kimura Miwako , Mau Ted , Chan Roger W.
Published: October 2009

The purpose of this study was to compare the functional biomechanical properties of injectable biomaterials commonly used for vocal fold augmentation. Viscoelastic shear properties of cross-linked hyaluronic acid (HA) gel (Juvederm), micronized Alloderm (Cymetra), and atelocollagen (3% bovine non-cross-linked collagen) were determined at phonatory frequencies and compared to those of the human vocal fold cover (n=13). The elastic and viscous shear moduli (G′ and G″) of all samples were quantified with a linear, controlled-strain simple-shear rheometer as functions of frequency, up to the phonatory range (1–250 Hz). Statistical analysis was performed with one-way analysis of variance and Tukey’s tests. Results showed that the injectable materials tested were generally stiffer and more viscous than the vocal fold cover. Significant differences in the viscoelastic functions were observed between micronized Alloderm and the vocal fold cover at some phonatory frequencies. Cross-linked HA and atelocollagen were found to be the closest rheological match to the vocal fold cover. These findings have implications for the functional biomechanical performance of these biomaterials for facilitating vocal fold vibration. [Work supported by NIH.]
Frequency response of synthetic vocal fold models with linear and nonlinear material properties.
Authors: Shaw Stephanie , Smith Simeon , Thomson Scott L.
Published: October 2009

Previous studies have shown the importance of cricothyroid muscle activation in altering fundamental frequency of the human voice. Other studies have explored the nonlinear stress-strain properties of human vocal fold tissue and shown that this also influences vibration frequency. Synthetic models have been and are currently being used to characterize behavior of the human vocal folds. To date, the models have used materials with essentially linear stress-strain properties. The purpose of this research study was to investigate the frequency response of synthetic models fabricated with linear and nonlinear materials as a function of anterior-posterior stretching (as in cricothyroid muscle activation). Methods are described for fabrication of both materially-linear and nonlinear vocal fold models. The mechanism for applying anterior-posterior stretching is described. Onset pressure and fundamental frequency data are given for linear and nonlinear models at 1-mm stretch (about 6% strain) intervals up to 10 mm (about 60% strain). Tensile test results show stress-strain properties for both models, and data are compared with similar tests performed using excised human vocal folds. [Work supported by NIH.]
Characterization of acoustic behavior when prandial material is present in the larynx.
Authors: Murugappan Shanmugam , Boyce Suzanne , Khosla Sid , Kelchner Lisa , Gutmark Ephraim
Published: October 2009

A perceptible change in phonation characteristics after a swallow has long been considered evidence that food and/or drink material has entered the laryngeal vestibule and is on the surface of the vocal folds as they vibrate. In this paper, we investigate the acoustic characteristics of phonation when liquid material is present on the vocal folds, using in vitro excised porcine larynges as a model. Two liquids of different Varibar viscosity (nectar and honey) were studied at constant volume. The presence of material on the folds during phonation was generally found to suppress the higher-frequency harmonics and generate intermittent additional frequencies in the low and high ends of the acoustic spectrum, with differences proportional to viscosity. Perturbation measures showed a higher percentage of jitter and shimmer when liquid material was present on the folds during phonation but they were unable to differentiate statistically between the two fluid conditions. The finite correlation dimension and positive Lyapunov exponent measures indicated that the presence of material on the vocal folds excited a chaotic system. Further, these measures were able to differentiate the two fluid conditions.
Silver Medal in Acoustical Oceanography
Authors: Spindel Robert C.
Published: October 2009

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Silver Medal in Noise
Authors: Stinson Michael R.
Published: October 2009

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Characterizing variation in natural acoustical environments and assessing the consequences of this variation for animal perception and communication.
Authors: Fristrup Kurt M.
Published: October 2009

Ambient sound levels present fundamental constraints for auditory perception. An extensive archive of sound level data, 1-s Leq values in 1/3 octave bands, has been collected by the National Park Service to assess conditions across a wide variety of park units and environmental settings. Exceedance values for these data offer one approach to assessing variation, but this ignores the temporal sequence of the measurements. In what sense are sound level patterns “stationary”? This presentation will evaluate several measures of temporal variation in sound levels and evaluate the results in relation to the diel schedule and behavioral tempo of animal activities.
Bats control the auditory scene by adapting intensity and directionality of echolocation calls.
Authors: Surlykke Annemarie , Jakobsen Lasse , Brinkloev Signe , Moss Cynthia
Published: October 2009

Echolocating bats emit short high-frequency calls and use returning echoes to determine direction, distance, and features of objects in the environment. Thus, echolocation is an active orientation system allowing bats to operate with little or no light. In open areas in the wild, bats emit very high intensity search calls of high directionality to increase the range of the sonar. In cluttered habitats (or the laboratory) not only the prey but also vegetation and other obstacles will reflect a fusion of many echoes for each emitted echolocation call. In cluttered habitats, the intensity is lower and the beam is wider to shorten and broaden the angle of view, while the beam axis is still focused very accurately on the target. Thus, by adjusting intensity, directionality, and beam aim of their calls, bats can actively filter and control the “sound-picture” of their surroundings that they perceive through echolocation.
Multiple scattering effects on communication and imaging through random media.
Authors: Ishimaru Akira , Jaruwatanadilok Sermsak , Kuga Yasuo
Published: October 2009

Communication through turbulence and particulate matters such as rain are seriously affected by multiple scattering. We present a study on multiple-input-multiple-output system in random medium and its channel capacity making use of the stochastic Green’s functions and the mutual coherence function (MCF). The channel matrix and the eigenvalues are given explicitly in terms of the medium characteristics, and the channel capacity is given in terms of signal-to-noise ratios, eigenvalues, and the antenna gain characteristics. MCF is given in terms of the power spectrum for turbulence and the optical depth, phase function, and albedo for particulate matters. Next, we consider imaging through random medium such as biological media. We present several space-time array signal processing imaging techniques which include time-reverse imaging, time-reverse multiple signal classification, Capon minimum variance, modified beam former, and SAR. We discuss the advantages and the disadvantages of these techniques with numerical examples. The effects of array sizes, Fresnel size, bandwidth, the distance, and the medium characteristics on the transverse and longitudinal resolutions are clarified. This study is aimed at combining the propagation and scattering and the array signal processing for communication and imaging in a random complex environment such as turbulence and biological media.
The effective wavenumber equation for an elastic medium containing cylindrical scatterers.
Authors: Norris Andrew , Conoir Jean-Marc
Published: October 2009

We will discuss effective wavenumber equations for waves in an elastic solid containing randomly distributed inclusions in a half-space. The multiple scattering approach used is similar to the one proposed by Fikioris and Waterman for acoustic waves, and will be reviewed in that context. The characteristic equation, the solution of which yields the effective wavenumbers of coherent elastic waves, is obtained in an explicit form without the use of any renormalization methods. Two approximations are considered. First, formulas are derived for the effective wavenumbers in a dilute random distribution of identical scatterers. These equations generalize the formula obtained by Linton and Martin for acoustic waves. Second, the high-frequency approximation is compared with the Waterman and Truell approach for elastic waves. The Fikioris and Waterman approach, in contrast with Waterman and Truell’s method, shows that P and SV waves are coupled even at relatively low concentration of scatterers. Reflection coefficients of P and SV waves incident on the interface of the half-space containing randomly distributed inclusions are also discussed. These expressions depend on frequency, concentration of scatterers, and the two effective wave numbers of the coherent waves propagating in the elastic multiple scattering medium.
Experimental study of the resonant motion of biological cells.
Authors: Choi Youngsoo , Ohm Won-Suk , Kim Yong Tae
Published: October 2009

The two lowest natural modes of vibration of a spherical cell suspended in a host fluid have been known to be quadrupole and octupole oscillations [Zinin et al., Phys. Rev. E 72, 061907 (2005)], although no experimental confirmations have been reported to date. In this paper, an attempt to ultrasonically excite and measure the quadrupole oscillation of a spherical cell is described. Cells suspended in an ultrasonic standing wave field are put into resonance by a series of shock pulses, and the resulting acoustic emission is measured by a needle hydrophone. Both the characteristic frequency and the overall radiation pattern of the observed acoustic emission serve as evidence of the quadrupole cell motion.
Analysis of human fibroadenoma using three-dimensional impedance maps.
Authors: Dapore Alexander , Wirtzfeld Lauren A. , King Michael R. , Sarwate Sandhya , Harter Josephine , Oelze Michael L. , Hall Timothy J. , Do Minh N. , O'Brien William D.
Published: October 2009

Three-dimensional impedance maps (3DZMs) are virtual volumes of acoustic impedance values constructed from histology to represent tissue microstructure acoustically. From the 3DZM, estimations can be made for ultrasonic backscatter and scatterer properties, such as effective scatterer diameter (ESD). Additionally, the 3DZM can be exploited to visualize and identify possible scattering sites, which may aid in the development of more effective scattering models to better represent the ultrasonic interaction with underlying tissue microstructure. In this study, 3DZMs were created from several human fibroadenoma samples. ESD estimates were obtained using the fluid-filled sphere form factor model. These estimates were made using two regions of interest (ROIs) sizes: cubes of side lengths of 300 and 150 μm. This estimation technique allowed a better understanding of the spatial distribution and variability of the estimates throughout the volume. For a collection of ten 3DZMs, the ESD was estimated to be 94±47 μm with the large ROI and 52±19 μm when using the small ROI. The 3DZMs were then investigated visually to identify possible scattering sources. This visualization and comparison resulted in the identification of possible ultrasonic scattering sources within human fibroadenomas. [Work supported by NIH Grant CA111289.]
Comparison between independent and multiple scattering models to predict velocity dispersion in trabecular bone.
Authors: Haiat Guillaume , Naili Salah
Published: October 2009

Transverse transmission devices are used clinically to assess fracture risk. However, the physical interaction between trabecular bone and ultrasound remains unclear. Unlike most soft tissues, negative values of velocity dispersion have been measured in trabecular bone. The origin of negative dispersion is still a matter of debate. The aim of this paper is to propose a model predicting the frequency dependence of phase velocity as well as its physical determinants. A two-dimensional homogenization model accounting for the coupling of independent scattering effects with viscoelastic absorption is employed to calculate the dependence of phase velocity on frequency, bone volume fraction (BV/TV), and trabecular thickness (TbTh). A simple biphasic description of TB in which the trabeculae are assumed to be identical and parallel cylinders are considered. The first step of the method is to compute the attenuation coefficient in the entire frequency range using a suitable decomposition via Bessel functions. Then, the Kramers–Kronig relationships are used to derive the frequency dependence of phase velocity. The results obtained assuming, independent scattering are compared with a model accounting for multiple scattering [Haiat et al., J. Acoust. Soc. Am. (2008)], which is shown to be in better agreement with experimental results obtained in the literature.
Experimental and theoretical investigations of ultrasound contrast agent dynamics between parallel plates and within rectangular channels.
Authors: Hay Todd A. , Garbin Valeria , Versluis Michel , Ilinskii Yurii A. , Hamilton Mark F.
Published: October 2009

The behavior of ultrasound contrast agent (UCA) microbubbles in confining environments is relevant for applications including ultrasound imaging and targeted microbubbles. In this presentation, measurements from experiments investigating the radial dynamics of UCA microbubbles positioned between parallel plates and within rectangular microchannels will be compared with model simulations. The radial motion of several UCA bubbles was recorded with high-speed imaging at 15 million frames per second over a range of insonation frequencies at various offset distances from the plates or channel walls. The behavior of each individual bubble was observed in both parallel plate and microchannel environments, thereby isolating effects due purely to the confinement. Several plastics and polymers with well-defined material properties were used to construct the plates and channels, making the dataset suitable for model validation. Measurements show that the oscillation amplitude and natural frequency of the bubbles depend on their position with respect to the walls as well as the material properties and geometry of the confining surfaces. Comparisons with various models for parallel plate and microchannel geometries will be presented. [Work supported by NIH DK070618.]
Iron-gallium (Galfenol) transduction alloys: Magnetic and mechanical properties.
Authors: Restorff James B. , Wun-Fogle Marilyn , Clark Arthur E. , Lograsso Thomas A. , Petculescu Gabriela
Published: October 2009

Galfenol, Fe100−xGax (∼5<x<∼20), is a unique magnetostrictive alloy that combines high saturation magnetostrictions with robust mechanical properties. [Clark et al., “Magnetostrictive properties of body-centered cubic Fe-Ga and Fe-Ga-Al alloys,” IEEE Trans. Magn. 36, 3238 (2000)]. These materials can be welded and machined. Additionally, alloys treated with a stress annealing process retain the maximum value of magnetostriction up to tensile loads of approximately 38 MPa. [Wun-Fogle et al., “Stress annealing of Fe-Ga transduction alloys for operation under tension and compression,” J. Appl. Phys. 97, 10M301 (2005)]. Room temperature Fe81Ga19 single crystal properties are Ms≅1.7 T, (3/2)λ100≅400×10−6, c′≅20 GPa, and tensile strength >500 MPa. In this presentation, temperature, field and stress dependent magnetic and elastic properties such as permeability, piezomagnetic d constants, Young’s modulus and coupling factors will be presented for several Fe–Ga alloys.
Large-magnetostriction ternary alloys obtained from Galfenol through partial substitution of Ga.
Authors: Mandru A. O. , Petculescu G. , Hathaway K. B. , Lograsso T. A. , Clark A. E. , Wun-Fogle M. , Restorff J. B.
Published: October 2009

In this paper the magnetoelastic characteristics of ternary Fe–Ga–X (X=Ge, Sn) alloys are compared with those of Galfenol (Fe–Ga) within the same range of solute concentration. New magnetostriction and elastic modulus data for Fe–Ga–Ge at six different compositions are presented. The most notable case is that of Fe86.9Ga9.9Ge8.7. Although the tetragonal magnetostriction, λ100, of Fe–Ge is lower overall than that of Fe–Ga, the magnetostriction of the aforementioned ternary alloy equals the value of Galfenol at the same solute concentration, Fe86.9Ga13.1. The theory proposed for explaining the measured λ100 values in the ternary alloys takes into account the total number of electrons each solute contributes to the alloy. The valence of Fe is taken to be “1” from first-principles calculations. Previously published results on Fe–Ga–Sn [Summers et al., “Magnetostriction of binary and ternary Fe-Ga alloys,” J. Mater. Sci 42, 9582–9594 (2007)] concur with this theory (Sn and Ge belong to the same periodic table group). The Sn ternary alloys are of economic importance for large-scale applications given that significant magnetostriction can be achieved while using less expensive solutes. It is also notable that, when compared with Galfenol at a Ga concentration of x=6.2 at. %, the ternary alloy Fe88.1Ga6.2Ge5.7 has a magnetostriction that is larger by a factor of 2.
Galfenol low frequency slotted cylinder transducer.
Authors: Meyer Richard , Summers Eric , Slaughter Julie , Allen Charles , Thompson Stephen C.
Published: October 2009

The ability of Galfenol to be readily formed into various geometries can be exploited by device designers in their efforts to create innovative sources and sensors. In this research forged Galfenol alloy is utilized as the active source actuating a slotted cylinder transducer (SCT). Analytical modeling was utilized to determine the geometry necessary to achieve the notional performance specifications: 210-dB source level, 750-Hz resonance frequency, and 200-Hz bandwidth. The final form factor was a Galfenol SCT with overall dimensions of 7.75-in. diameter × 12-in. length with a graphite composite shell material and Galfenol drivers comprising a rib-like structure within the shell. The advantages this device has over existing SCTs are reduced cost, ease in manufacture and assembly, and improved reliability. Magnetic and mechanical models were combined in order to conduct three dimensional FEA analysis. The magnetic circuit was modeled in COMSOL MULTIPHYSICS and the acoustic model was built in ATILA. This presentation will include the predicted SCT performance based on the modeling effort as well as details on material manufacturing. Future work will include design optimization to further improve output and bandwidth.
A galfenol force-based energy harvester.
Authors: Slaughter Julie , Kosterman Jim , Arbetter Barry , Summers Eric
Published: October 2009

A force-based energy harvester utilizing the magnetostrictive material, Galfenol, has been developed. Energy harvesters currently available primarily utilize a mass-spring concept where optimal energy harvesting efficiency occurs around a distinct resonance frequency. Deviation from the tuned frequency significantly degrades energy harvesting performance. Galfenol was engineered into a bolt-like configuration with a Galfenol rod welded to threaded stainless steel end pieces and pickup coils wound around the Galfenol. Dynamic forces are applied axially to the Galfenol resulting in a change in flux inducing voltage in the pick-up coils. Because dynamic force is the mechanism generating power, the energy harvester works across a broad range of frequencies. Two different electronic packages were developed; a voltage doubler and quadrupler, which provided efficient energy conversion based on the frequency range of interest. The configuration of the Galfenol bolt resulted in an energy harvester capable of harvesting energy over a broad frequency range. The development and the testing of this unique energy harvester will be discussed. Specific points of discussion will be the optimum device configuration, both hardware and associated electronics that provided the largest output power. In addition, the voltage and output power results will be presented as a function of frequency and force.
Variable compliance split-cylinder transducer using Galfenol for frequency control.
Authors: Thompson Stephen C. , Slaughter Julie , Summers Eric , Allen Charles , Meyer Richard J.
Published: October 2009

The size of conventional split ring transducers is much smaller than a wavelength at operating frequency leading to a high Q resonance and limited operating bandwidth. This work investigated modifying the split ring structure to allow its resonant frequency to be adjusted under active control so that it is always operated at or near its resonance. Because the transducer is operated at resonance, the phase of its input impedance is approximately constant, simplifying the design of the transmit power amplifier and reducing the size and weight of the system. A high Q system is desirable for an actively tuned system resulting in very high efficiency and allowing the use of less expensive shell materials. The two variable compliance designs studied involve the use of Galfenol stiffener bars located at the nodal point/hinge point of the shell. By activating all or a portion of these bars, the compliance (stiffness) of the shell can be varied with a corresponding shift in resonance frequency. Two methods of compliance control are being investigated, one that switches the stiffness “on” and “off,” and one that allows continuous control using the “delta-E” effect in Galfenol.
Singing in the brain: Professional singers, occasional singers, and out-of-tune singers.
Authors: Schlaug Gottfried
Published: October 2009

Speaking and singing are the two most complex communication systems of the human being, and perhaps in all of nature, both of which call on extensive cortical and subcortical resources in the brain. Singing is a combination of language and music that taps brain centers involved in both forms of communication and may rely more on right than left fronto-temporal brain structures. I will present results of research studies that examined the neural correlates of singing in professional singers, in occasional singers, and in individuals that sing out of tune. These “tone-deaf” singers lack some of the connections between auditory and motor brain regions that play a critical role in the feedback and feedforward control of vocal communications. These same brain structures are enhanced in professional singers and the duration of training as a singer correlates with gray and white matter enhancements seen in their brains. Ongoing studies are examining the development of these brain regions in children with and without musical training.
Noise control evolution in Mexico.
Authors: Beristain Sergio
Published: October 2009

Noise legislation in Mexico started in the mid-1970s, when most of the standards and recommendations available nowadays were issued, ranging from noise classification, sound level meter characteristics, to noise pollution and labor noise limits. Several of those standards were modified, with very little updating in the mid-1990s, but most of them were just transposed to the national standards format, without any major technical change, because the original issuing office was a federal depending ministry, but not the official standards office. More recently one of those standards was improved in only 3 dB, and a noise monitoring system for Mexico City is under preparation. From the non legislation point of view, some posters have been published in newspapers and billboards, and radio and TV noise control programs have been broadcasted.
Mexico City urban noise control network.
Authors: Menchaca Garcia Felipe Rolando , Sanchez Fernandez Luis Pastor , Suarez Guerra Sergio
Published: October 2009

This paper presents an IP network model for monitoring urban noise emitted from mobile and fixed sources. The model is applying to build a monitoring network in the historic center of Mexico City. Design of network system includes measuring station design, network design, central of monitoring design, measuring politics and functionality, event detection modules, central database of historic information, report module design, and administration system. Mexico City Urban Noise Control Network is going to be an important tool to enforce application of local noise regulations, detection of infractions for excessive noise, detection of security events like gun shots, and monitoring of noise pollution levels. Measuring stations are developed to detect average standard levels and individual events, to generate warnings and alarms, and to detect some specific events. Network is developed over a wireless Network.
Noise source identification in transportation systems in Brazil using beamforming technique.
Authors: Gerges Samir , Fonseca William , Bento Coelho Jose , M. Neves Miguel
Published: October 2009

Beamforming with acoustic phased arrays has become a popular technique for locating and quantifying noise sources in complex system such as environmental noise, aircraft noise, internal and external automobile noise, beside other applications. The signal processing performs traditional delay-and-sum beamforming and accounting for the different propagation paths from the source and to the different microphones. The sources may pass the acoustic camera with high speeds, allowing the beam to focus and follow the bypassing source past the microphone array. The signal processing can zoom into any part of the studied objector of any frequency band. Ultimately, image quality depends on the number of microphones and their configuration. When the microphones cover a big surface, the resolution gets higher; however, the image may contain noise at high frequencies. Reducing microphone distances from the source removes the specks but at the same time worsens the resolution. So the best way to guarantee high-quality images is to use as many microphones as possible. This paper presents the results of tests with 32-channel from National Instrument phased array system developed by the UFSC-Brazil. Measurement results are shown for motorcycle, car motor, and external automobile noise during pass-by test.