bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-frequency sound propagation in short ranges: A case where leaky modes can be observed
Authors: Abadi Shima
Published: November 2019

In an ocean waveguide, sound propagation can be modeled by the normal-modes theory. In a lossless ocean floor, the acoustic field is a finite sum of the normal modes that are trapped in the water column. These modes have real acoustic wave numbers and their equivalent rays are at angles less than the critical grazing angle. When attenuation is present in the ocean floor, the number of normal modes increases. Those additional modes, called “leaky modes,” have complex acoustic wave numbers, and their equivalent rays are steeper than the critical grazing angle. Since leaky modes attenuate in short ranges, they are not typically observable in measurements. In this presentation, I show that leaky modes can be observed on the data collected during marine seismic reflection surveys. Marine seismic reflection surveys are used to image the structure of the seafloor. They generate low-frequency signals from airguns and record the reflections off the seafloor up to a few kilometers from the source. I use simulations and experiments to characterize the short-range propagation of airgun pulses in shallow and deep water. The experimental data utilized in this study are from the COAST experiment conducted in the Northeast Pacific continental shelf.
Observations of low frequency, long range propagation in the Philippine Sea and comparisons with mode transport theory
Authors: Chandrayadula Tarun K. , Colosi John A. , Worcester Peter F. , Dzieciuch Matthew , Mercer James , Andrew Rex
Published: November 2019

The year-long Philippine Sea (2010–2011) experiment was an extensive deep water propagation experiment in which there were six different sources transmitting to a water column spanning vertical line array. The six sources were placed across a 250 km × 250 km area, and transmitted at frequencies in the 200–300-Hz, and 140–205-Hz bandwidth. The PhilSea frequencies are higher than previous deep water experiments in the North Pacific for which modal analyses were performed. Further, the acoustic paths sample a two-dimensional area that is rich in internal tides, waves, and eddies. The PhilSea observations are thus a new opportunity to observe acoustic modal variability at higher frequencies than before and in an oceanographically dynamic region. This talk focuses on mode observations around the mid-water depths. The mode observations are used to present narrowband statistics such as transmission loss, and broadband statistics such as peak pulse intensity, travel time wander, time spreads, and scintillation indices. The observations are then compared with a new hybrid broadband transport theory. The model-data comparisons show excellent agreement for modes 1–10, and minor deviations for the rest. The discrepancies in the comparisons are related to limitations of the hybrid model, and other oceanographic fluctuations.
Out-of-band phase conjugation for auto-focusing and communications in the shallow ocean
Authors: Cheong YeonJoon , Popa Bogdan Ioan
Published: November 2019

Time-reversal methods in which received sound is inverted in the time domain and retransmitted back towards the source allows effective temporal and spatial auto-focusing in complex and dynamically changing environments such as the ocean. However, time-reversal typically involves significant time lapses between the receipt of a signal and its time-reversed retransmission. Given the continuously changing nature of the ocean significantly affecting higher frequencies, demonstrations of time-reversal systems were limited to low frequencies below 5 kHz. The closely related phase conjugation methods remove the time gap between signal receipt and its retransmission but are difficult to implement because of additional hardware needed to decouple the receiver and transmitter operating on the same frequency band. Moreover, phase conjugation preserves only the spatial focusing of time-reversal and loses the temporal focusing ability. In this presentation we will introduce the concept of out-of-band phase conjugation in which the phase conjugated sound is on a higher harmonic of the received sound thus effectively decoupling the transmitter and receiver. At the same time, out-of-band phase conjugation improves the resolution of the auto-focused phase conjugated sound. We will also discuss methods to mitigate the effects of imperfect temporal focusing.
Applications, mechanisms and real-time monitoring of enhanced drug transport by sustained inertial cavitation
Authors: Smith Cameron , Mannaris Christophoros , Katti Prateek , Paverd Catherine , Coviello Christian , Carlisle Robert , Coussios Constantin
Published: November 2019

Sustained inertial cavitation seeded by microbubbles, sub-micron cavitation nuclei or even without any cavitation nucleation agent has been shown to enable increased delivery and penetration of drugs and vaccines across the skin, into solid tumours and across the blood-brain barrier. The safety and efficacy of these applications are typically monitored using single-element passive cavitation detectors, or more recently using multi-element arrays that enable real-time passive acoustic mapping of cavitation activity. We will provide an overview of the different types of cavitation nucleation agents which are available to use, the type and persistence of acoustic emissions that they are typically associated with, and, where possible, a direct comparison between the performance of different nucleation strategies to achieve the desired drug delivery bioeffect in the target of interest. We will then turn our attention to the presently available strategies for real-time monitoring of safety and efficacy, with specific reference to the benefits offered by the ability to achieve spatiotemporal monitoring of cavitation activity to correlate it with bioeffects in subsets of the overall region of interest.
Influence of compressive stresses on the ultrasonic response of the bone-implant interface
Authors: Hériveaux Yoann , Nguyen Vu-Hieu , Geiger Didier , Haiat Guillaume
Published: November 2019

The stress distribution around endosseous implants is an important determinant of the surgical success but it remains difficult to be measured. So far, no method developed to determine the implant stability is sensitive to the loading conditions of the bone-implant interface (BII). The objective of this study is to investigate whether a quantitative ultrasound (QUS) technique may be used to retrieve information on compressive stresses applied to the BII. A dedicated acousto-mechanical device was conceived to compress 18 trabecular bovine bone samples onto coin-shaped implants and to measure the ultrasonic response of the BII during compression. The biomechanical behavior of the trabecular bone samples was modeled as Neo-Hookean. The reflection coefficient of the BII was shown to decrease as a function of the compressive stress during the elastic compression of the trabecular bone samples and during the collapse of the trabecular network, with an average slope of -4.82 GPa-1. Results may be explained by an increase of the bone-implant contact ratio and a change of bone structure occurring during compression. The sensitivity of the QUS response of the BII to compressive stresses opens new paths in the development of patient specific decision support systems allowing surgeons to assess implant stability.
Ultrasonic guided wave propagation in a dental implant
Authors: Hériveaux Yoann , Audoin Bertrand , Biateau Chrstine , Nguyen Vu-Hieu , Haiat Guillaume
Published: November 2019

Ultrasound techniques can be used to characterize and stimulate dental implant osseointegration. The acoustical energy transmitted to the bone-implant interface is an important parameter that must be controlled for both applications, since it should be sufficiently low to avoid damaging the surrounding tissues, but sufficiently high for stimulation purposes to enhance bone growth. However, the interaction between an ultrasonic wave and a dental implant remains unclear. The objective of this study combining experimental, analytical and numerical approaches is to investigate the propagation of an ultrasonic wave in a dental implant by assessing the amplitude of the displacements along the implant axis. An ultrasonic transducer was excited in transient regime at 10 MHz. Laser interferometric techniques were employed to measure the amplitude of the displacements, which varied between 5 and 12 nm according to the position. The results show the propagation of a guided wave mode along the implant axis with a velocity of first arriving signal equal to 2110 m s−1 and frequency components lower than 1 MHz, which was confirmed by the analytical and numerical results. This work paves the way to improve techniques for the characterization and stimulation of the bone-implant interface.
A heat balance model to explain delayed thermoacoustic sound production in seawater using metal electrodes
Authors: McBeth Michael S.
Published: November 2019

Experiments conducted with solid metal wire electrodes in seawater generated second harmonic sound waves thought to be thermoacoustic in origin. Using sine wave bursts of five cycles of 10 kHz voltage across the electrodes, the thermoacoustic sound production was repeatedly observed to be delayed by about 240 μs from the initial applied voltage. At the time of these experiments around 2014, we were unable to account for this surprising delay in sound production. Recently, we built a heat balance model for the driven water volume that shows heat accumulating, during the applied voltage, faster than it can escape by heat conduction to the surrounding water. This results in a build up of heat in the driven water volume that increases the local temperature and density until a threshold level for sound production is reached. After the last cycle of the voltage burst, sound waves continue to be produced until enough heat has conducted away from the driven water volume for the temperature and density to fall below the sound production threshold. Although the model uses several simplifying assumptions, the results match the experimental observations reasonably well.
Liquid metal-based resistive membranes for flow acoustics detection
Authors: Wissman James P. , Sampath Kaushik , Ikei Alec , Özütemiz Kadri B. , Carmel Majidi , Rohde Charles
Published: November 2019

Fluid flow over bodies results in vortex and turbulence-induced vibrations that reflect the boundary layer conditions and lead to drag and noise production. Many platforms would benefit from real-time monitoring of these acoustic signatures, providing feedback for control or increased efficiency. Of particular interest are compliant pressure sensors that can be wrapped around any surface. We present a silicone membrane integrated with a liquid phase gallium-indium coil. As the device deforms under pressure fluctuations, the resistance across the liquid metal can be monitored for real-time detection of flow features. The fabrication process is presented, including a masked spray deposition of gallium-indium coupled with layering of elastomer. The 18 mm-diameter sample demonstrates a point load sensitivity of 0.045 W/mm. To evaluate the performance of the device, it is tested in air with an acoustic tube, and its output is compared to impedance analysis at frequencies up to 10 kHz. Furthermore, the membrane vibrations are tracked with scanning laser Doppler vibrometer. These results are then compared to analytic models and COMSOL simulations. The sensor presented here is well suited to bulk fabrication in functional “skins” of active elements. [Work sponsored by the Office of Naval Research.]
Mode studies on note sections of a Gubal
Authors: Hansen Uwe J. , Gibson Joshua , Morden Dylan
Published: November 2019

Over the years, Felix Rohner and Sabina Schärer, of Panart in Bern, Switzerland have implemented a number of significant modification to the standard Caribbean Steel Pan. These include using custom rolled sheet metal in place of commercially available used 55 Gallon drums, sinking the pan in a press rather than hand hammer sinking, dispensing with chiseled note section boundaries in favor of natural narrow change in curvature, adding central domes which give rise to more order in high overtone mode patterns, and building a lap held, hand played Hang. The latest addition to the Panart family is the Gubal, an inverted Hang with an added large dome on the bottom and the playing area, including the tone hole, at the top. Electronic Speckle Interferometric mode representations for Gubal note sections will be shown to illustrate spectral content of the Gubal.
Summary of acoustic design for H3 launch complex
Authors: Sarae Wataru , Terashima Keita , Tsutsumi Seiji , Takegoshi Masao , Kobayashi Hiroaki , Mori Ayano
Published: November 2019

H3-scaled Acoustic Reduction Experiments (HARE) with a scale of 2.5 % was conducted for the prediction and reduction of lift-off acoustics for the H3 launch vehicle currently under development in Japan. The effect of vehicle elevation and shape of a movable launch platform was studied in the first testing campaign. Then, acoustic reduction based on acoustic shielding and water injection system was also studied in the second testing campaign. In this presentation, results of those testing campaign will be summarized. Then, in addition to the numerical study, acoustic design of the launch complex conducted in the H3 development will be presented.
Experimental study of over-expanded jets with centered thermal non-uniformity
Authors: Daniel Kyle A. , Mayo David , Lowe Kevin T. , Ng Wing
Published: November 2019

Recently, there has been increased concern in reducing supersonic jet noise, due in part to stricter community noise standards, renewed interest in supersonic transport over land, and the hearing damaged sustained by Navy personnel operating on the decks of aircraft carriers. In support of this, we propose an examination of the flow and acoustic fields of a supersonic jet with nozzle boundary conditions tailored to produce thermal non-uniformity. Specifically, we aim to study a heated jet with a centered thermal non-uniformity operating at over-expanded conditions. It will be shown through the course of this study that thermal non-uniformity reduces the overall sound pressure level (OASPL) by a maximum of 2.5 dB near the peak noise direction. We hypothesize the reduction in the radiated sound field is related to perturbations which persist beyond the near nozzle region and disrupt the organized structure of acoustically efficient turbulence over large axial distances. This hypothesis is supported by experimental evidence showing a reduced peak Reynolds shear stress, a decoherence in the hydrodynamic field, and a decorrelation of Mach wave structures. These effects are captured using PIV and high-speed schlieren imaging of the density near-field.
Experimental realization of aqueous double negative metamaterials in near-megahertz range
Authors: Wang Jiaying , Allein Florian , Boechler Nicholas , Friend James , Vazquez-Mena Oscar
Published: November 2019

Ultrasound is strongly attenuated and aberrated by the skull, principally due to the complex structure and acoustic impedance mismatch of skull which generates strong scattering. Analytical models and finite element methods have shown that negative index metamaterials matching skull properties can enable the transmission of US which enhances bidirectional transmission of ultrasonic signal for imaging. However, it is difficult to realize double-negative metamaterials in near-megahertz range experimentally because of the limitation of fabrication and characterization methods. Here we show the experimental realization of waterborne double negative acoustic metamaterials by coupling micrometer-size membrane-based negative density metamaterials with Helmholtz resonator-based negative modulus materials. Numerical simulation and experimental verification consistently exhibit the double negative behavior between 230 kHz and 410 kHz. We demonstrated the feasibility of creating ultrasonic-range metamaterials for non-invasive ultrasound imaging and neuron stimulation.
Dynamical energy analysis—An efficient mesh based simulation tool for mid-to-high frequency structure-borne sound calculations
Authors: Tanner Gregor
Published: November 2019

Modelling the vibro-acoustic response of mechanical built-up structures is a challenging task—especially in the mid to high frequency regime—even with the computing powers available today. Standard modelling tools such as Finite Element Methods (FEM) are not scalable to high frequencies due to the prohibitive increase in model size. Typical high frequency methods such as the Statistical Energy Analysis (SEA) on the other hand, often lack details of the structure and require care in the setting up the model. In this talk, I will review the Dynamical Energy Analysis (DEA)—a method bridging the gap between the low and very high frequency range. DEA describes the energy flow in a complex structure keeping the directional information of energy propagation. It can be set up directly on meshed structures thus providing detailed spatial information about the vibrational energy of a built-up structure of high complexity. The response of coupling coefficients between sub-components are obtained through local wave models integrated into the global DEA treatment. The computational cost of DEA is frequency independent making it possible to get results from the mid-to-high frequency regime. The method can be extended to include sound radiation calculations in a post-processing step. The new method has been validated both using FEM computations and experiments in collaboration with Yanmar Co., Ltd., a Japanese tractor manufacturer. Further applications in the car, aerospace and ship building industry will be presented.
Further exploration of model truncation to extend the applicability of the finite element method to higher frequencies
Authors: Bonomo Anthony L.
Published: November 2019

In a previous presentation, the use of model truncation to extend the applicability of the finite element method to higher frequencies was explored. This talk furthers that exploration and focuses on the development of an easy-to-implement alternative to the perfectly matched layer for the truncation of semi-infinite problems with coupled structural and acoustic domains. Numerical results showing the efficacy of the proposed method are discussed and a method to bound the error that results from treating a large finite structural as semi-infinite is considered. It is hoped that the proposed method helps facilitate extension of the finite element method to mid-frequency applications. [Work supported by ONR.]
The neutralization of Xiapu Min tones in disyllabic tone sandhi forms
Authors: Chai Yuan
Published: November 2019

Tone sandhi can result in both incomplete and complete tone neutralization. Chien and Jongman (2018) proposed that unproductive (i.e., lexicalized) tone sandhi (as in Taiwan Min) tends to have complete neutralization; productive tone sandhi usually shows incomplete neutralization (as in Mandarin; Zhang and Lai, 2010). The current study tests whether tone sandhi is phonetically neutralized in Xiapu Min, an Eastern Min variety from Fujian, China (Wen, 2015). Xiapu Min has seven tones, five of which are smooth tones (44, 11, 42, 35, 23) and two of which are checked tones (5, 2). Tone sandhi occurs in disyllabic words and results in neutralization (e.g., Tone 42, 35, and 5 are neutralized to Tone 55 when word-initial.) We test the completeness of this neutralization by investigating potential differences in F0, duration, and phonation, which is measured acoustically using H1*–H2* and HNR, and articulatorily using electroglottographic open quotient. We also determine the productivity of Xiapu Min by testing whether tone sandhi emerges in nonce words. The results will illustrate whether the tonal neutralization is complete in Xiapu Min real words and will bring further data to bear on the relation between sandhi productivity and the completeness of neutralization.
Analysis of breathiness as an acoustic correlate of nasality in Hindi
Authors: Gogoi Pamir , Pandey Ayushi , Wayland Ratree
Published: November 2019

This project investigates the perceived breathiness of nasal segments than non-nasal sonorants like [l] in Hindi. Shared acoustic correlates between nasality and breathiness (like wider F1 bandwidth, appearance of additional poles and zeros in the acoustic spectrum) lead to perceptual consequences that both allow erroneous perception of breathiness as nasality (Ohala and Busà, 1995) or enhanced perception of nasality (Arai, 2006). Breathiness has been observed to co-occur with nasality in French (Styler, 2017) and some Yi languages (Garellek et al., 2016). Effects of breathiness on perception of nasality have also been reported in Hindi (Ohala and Ohala, 1993)—vowels that were produced with a relatively open glottis were perceived to be more nasal than their non-breathy counterparts. Based on these findings, we hypothesized that Hindi speakers use breathiness for enhanced perception of nasality. This was tested using the following acoustic parameters of breathiness: Difference between 1st and 2nd harmonic (H1-H2), Cepstral Peak Prominence (CPP), Spectral tilt and Harmonic to Noise Ratio (HNR). The results demonstrated that the nasals were significantly breathier than the non-nasal sonorants, suggesting that breathiness might be used as a cue to enhance the perception of nasality in Hindi.
Eco-active sonar concept with examples
Authors: Ferguson Brian G. , Culver R. Lee , Ferguson Eric L.
Published: November 2019

Eco-active sonar is a term coined to describe high-frequency (>20 kHz) wideband (>20 kHz) active sonars that emit environmentally friendly transmissions without impacting the marine ecosystem. The remarkable biological sonar of dolphins is one example of eco-active sonar. The waveforms of the acoustic pulses projected by Indo-Pacific bottlenose dolphins (Tursiops aduncus) are reviewed and the observed fine structure of the bistatic scattering impulse responses of the sea floor, sea surface and scatterers in the water volume are presented. Another example is pulse compression sonar (commonly referred to in defense parlance as low probability of intercept sonar or covert active sonar) which transmit low source level, wideband coded signals of long duration in contrast to high source level, narrowband short-duration pulses of conventional naval sonars. Matched filtering of the sonar returns reveals the presence of echoes from undersea objects and monostatic reverberation contributions from the sea floor and sea surface. High-frequency, high-resolution sonar meets the need for enhanced situational awareness in the undersea littoral as well as precision navigation and high-resolution mapping of the sea floor. The advent of injection-molded piezocomposite wideband sonar transducers with quality factors approaching unity enable the practical realization of eco-active sonar.
Robust direction finding in the fluctuating oceans by complex L1-norm principal component analysis
Authors: Sklivanitis George , Real Gaultier , Pados Dimitris
Published: November 2019

We consider the problem of robust direction-of-arrival (DoA) estimation in dynamic ocean environments. Robust direction finding of underwater acoustic signals transmitted from known locations may enable accurate underwater localization and enhance link communication rate by instructing a receiver to listen for transmissions from a specific direction. We propose to estimate the DoA of underwater acoustic signals via subspace methods, executed at a very large receiver array, that involve performing what is known as principal-component analysis (PCA) for finding the L2-norm principal vector subspace of the recorded signal snapshots. However, in practice coherence loss, which typically arises from dynamic wavefront fluctuations due to internal waves, scattering from the sea surface and/or bottom and other unknown environmental parameters, may result in recorded signal snapshots that are corrupted by faulty measurements, leading to an inaccurate estimation of the DoA and source position. We propose to model the loss of coherence as multiplicative random noise applied to the measured acoustic signal. In such cases, L2-norm PCA methods suffer from significant performance degradation. Motivated by the resistance of novel L1-nrom-derived subspaces against the impact of irregular, highly deviating points in reduced-dimensionality data approximations, we propose to employ L1-norm (absolute error) maximum projection PCA of the antenna array measurements and evaluate the performance of a novel, outlier-resistant DoA estimation algorithm.
Analytical models for predicting required response of mandrel-type fiber optic acoustic sensors for ocean and seismic applications
Authors: DeMetz Fred C.
Published: November 2019

Fiber optic acoustic sensor systems have been developed by industry, university, and government research teams which meet enhanced requirements for arrays with high sensor counts, high dynamic range, wide bandwidths, and will operate reliably for a decade or more in high-pressure-high-temperature pipeline, ocean, and seismic environments. Optical sensors do not require vulnerable electrical telemetry in the “wet” end of the system, and can reliably transmit high sensor count string outputs which are 10's of km from the light source and acoustic data processors. This paper introduces a modified version of the SONAR equation which allows a straight forward estimation of the required fiber optic acoustic sensor array response to capture the desired acoustic signal detail necessary to interpret the target or seismic event. This enables system design engineers to define and optimize sensor response requirements early on, and help minimize prototype and production system performance and budget risks.
Architectural soundscapes
Authors: Siebein Gary W. , Paek Hyun , Roa Marylin , Siebein Keely , Miller Jennifer R. , Vetterick Matthew , Siebein Gary
Published: November 2019

This paper describes seven elements of soundscape theory that can be applied to the design of architectural spaces including worship spaces, music education spaces, justice facilities, museums, performing arts centers, libraries, restaurants and schools. The paper is focused on the transformative steps that must be taken to translate soundscape data and analysis into the physical form of a building where sound is conceived of as a generator of form and is not necessarily a result of the form. Case studies of recent research and architectural studio classes involved with the design of performing arts facilities will be presented to illustrate how sound can become a part of the conceptual structure of buildings in addition to one of the functions to be accommodated in buildings. The concept of a sonic niche in location, time, level, pitch and form becoming a tangible architectural intervention in a building is explored as one way to translate soundscape theory into architectural space.
The impact of the acoustic environments on the emotional experience of worship spaces
Authors: Algargoosh Alaa , Soleimani Babak
Published: November 2019

The acoustic properties of a space influence how it is being perceived. However, less is known about the ways in which the acoustic environment elicit different emotional responses. The purpose of this paper is to investigate this question through the study of worship spaces. The Focus on such buildings in this study is due to the essential role of the acoustics in shaping the spiritual experience. Adopting a mixed-method approach, the researchers created virtual experiences of these buildings using 360-deg sound and visual recordings. The recordings were displayed for the subjects through a virtual reality headset. During the experiment, physiological signals of the participants and semantic descriptions of their experience were collected and analyzed to understand the emotional impact of the acoustic environment. The outcome of this study will allow exploring the relationship between acoustic characteristics of worship spaces and the human emotional experience. Therefore, it will provide a further understanding of the impact of the architectural design that determines the acoustic environment, which then contributes to improving the restorative qualities of such spaces and enhancing the spiritual experience.
Deep learning of biosonar landmarks for navigation in forest environments
Authors: Zhang Liujun , Bhardwaj Ananya , Goldsworthy Michael , Müller Rolf
Published: November 2019

Many bat species live in densely vegetated habitats which pose challenges to their biosonar systems. Among these challenges, the problem of identifying prey in clutter has received the most attention. Here, the far less well-studied problem of landmark identification in forest environments has been investigated. To this end, a large data set of about 220 000 foliage echoes has been collected along different tracks located in forested area. The echoes were recorded using a biomimetic sonarhead with flexible noseleaf and pinnae modeled on the periphery of horseshoe bats. Low-dimensional representations of these foliage echoes were created with the encoder portion of a variational autoencoder deep neural network architecture. The feature vectors obtained in this manner were subjected to clustering to determine whether the echo recordings exhibited continuous variability or fell into discernible clusters. The data silhouettes indicate the presence of a small number of distinguishable clusters in the echo data. Furthermore, mapping the assigned cluster labels to the geographical coordinates of the respective echo recordings revealed that different tracks were characterized by a different “fingerprints” of echo classes. Hence, these fingerprints could be a hypothetical basis for biosonar-based navigation in forest environments.
Learning the relationship between biosonar pulse trains and peripheral dynamics in hipposiderid bats
Authors: Liu Yanming , Zhang Shuxin , Müller Rolf
Published: November 2019

The biosonar system of hipposiderid bats is characterized by a peripheral dynamics consisting of variable noseleaf and pinna motions as well as temporal variability in the emitted pulse trains. It may be hypothesized that a well-integrated biosonar emission system should coordinate noseleaf and pinna motions with the biosonar pulse trains if this leads to synergistic effects. To investigate whether a relationship between these two sources of variability in the emission system of hipposiderid bats exists, a data set with high-speed stereo video recordings of noseleaf and pinna motions that were synchronized with ultrasonic recordings of the biosonar pulses has been analyzed. Different similarity metrics that were developed for analyzing neural spike sequences have been tested for comparing the individual biosonar pulse trains. Based on these metrics, pulse trains were clustered and the results were compared to the different categories of noseleaf and pinna motions that were found in the video recordings. The results obtained so far for 80 recorded sequences show that noseleaf/pinna motions and pulse trains can be organized into joint clusters, i.e., certain categories of peripheral motions cluster with specific types of biosonar pulse trains. These links could indicate a synergistic relationship between noseleaf/pinna motions and pulse timings.
Machine learning for automated detection of migrating adult eels from ARIS sonar images
Authors: Zang Xiaoqin , Yin Tianzhixi , Hou Zhangshuan , Mueller Robert , Jacobson Paul T. , Deng Daniel Zhiqun
Published: November 2019

A machine-learning-based method is developed to detect American eels from ARIS sonar data through several analyses: (1) utilize wavelet transform to filter noises and enhance sonar images; (2) extract individual targets from the training image data with a screening and threshold approach; (3) identify multiple candidate objects from training and testing images using the selective search method; (4) train and apply convolutional neural network models to classify objects into four categories – background, eels, moving sticks, and other objects (e.g., bubble clouds). With laboratory control experiments, favorable conditions for applying the designed detection and classification method are identified. The applicability to the field data, collected at the Iroquois Water Control Dam on the St. Lawrence River, is also evaluated. The machine-learning-based method yields classification accuracy commensurate with human-supervised classification, providing an automated and efficient way to monitor fish migration and passage through hydropower facilities.
Underwater noise generated by vehicle traffic in an underwater tunnel
Authors: Reeder D. Benjamin , Joseph John E. , Rago Tarry
Published: November 2019

Underwater noise measurements were made adjacent to the Monitor-Merrimac Memorial Bridge-Tunnel in the James River, VA during a field experiment in April of 2019. Anticipated sources of underwater noise included wind, waves and associated bubbles, flow noise, boat/ship traffic, industrial shipyard noise and traffic noise radiating from the underwater tunnel. During the field observations, winds, waves/surface conditions, underwater currents, water column structure and tunnel traffic were monitored by anemometers, high-frequency surface radar, ADCPs, echosounders and traffic sensors. The observed noise field exhibited high frequency and tidal-scale variability due to passing surface vessels and tidally driven currents in the estuary; most interestingly, the noise field exhibited variability on a diurnal time scale, closely correlated to the temporal distribution of vehicular traffic in the underwater tunnel. The tunnel traffic underwater noise amplitude varied by 1–5 dB at 10s to 100s of Hertz and exhibited a non-linear relationship to frequency.
Site-specific characterization of transmission efficiency of broadband transcranial focused ultrasound
Authors: Smith Collin , O'Driscoll Christopher , Ebbini Emad S.
Published: November 2019

The efficacy of transcranial focused ultrasound (tFUS) is largely limited by the acoustic properties of the skull. The spatial and spectral variability of acoustic transmission coefficients were measured in three Sprague-Dawley rat skulls. Target areas such as the ventral posterolateral nuclei (VPL) and hippocampus were included in the analysis. The skull samples were interrogated using two systems: a standard, matched transducer setup for transmission measurements with a narrow beam width and a focused array transducer with planar hydrophone transmission measurements. Both systems were designed to operate in the 2 to 4.5 MHz frequency range. Results have shown that the variability in transmission efficiency for different target locations within the same skull varied by 6 dB. Furthermore, measured transmission efficiencies varied by 7 dB on average as a function of frequency in the 2 to 4.5 MHz range in a nonmonotonic manner. Finally, transmission efficiency for the same target window varied by 25% across different skull samples. These results suggest the need for site-specific optimization of the spectral content of tFUS beams taken the skull transmission characteristics into consideration. The results also serve as a basis for validating reflection mode measurements for characterizing transmission efficiency of tFUS beams.
Microelectrode arrays (MEA) for measuring spatio-temporal neural activity generated by low-energy focused ultrasound (LEFUS) in ex vivo brain slices
Authors: Suarez Castellanos Ivan M. , N'Djin Apoutou , Vion-Bailly Jérémy , Dossi Elena , Carpentier Alexandre , Huberfeld Gilles , Chapelon Jean-Yves
Published: November 2019

The objective of this project was to study the electrical activities elicited by Low-Energy Focused Ultrasound (LEFUS) neurostimulation in ex vivo mouse hippocampal brain slices using a MicroElectrode Array (MEA) system. A mixed LEFUS/MEA platform was developed for spatial-temporal recording of neural responses induced by LEFUS exposures in ex-vivo hippocampal brain slices from a mouse model. Hippocampal slices were maintained functional in the 60 electrode MEA chip by perfusion with artificial cerebrospinal fluid. The LEFUS system consisted of a 1.78-MHz focused transducer (diameter: 15 mm, radius of curvature: 15 mm). LEFUS pulses (1.1 MPa, 284–568 cycles) were applied on slices at pulse repetition frequencies in the range of 0.2–1 Hz. Recorded signals resulting from LEFUS stimulation were characterized by negative deflections corresponding to LEFUS artifacts, followed by positive deflections corresponding to electrophysiological responses several milliseconds afterwards. This setup thus allows for the recording and differentiation of fiber volleys (latency ≈ 1–5 ms) and post-synaptic potentials (amplitude ≈ 100–800 μV) as a result of LEFUS stimulation. Such responses were observed in several electrodes across the MEA matrix while exhibiting a progressive drop in amplitude after every applied pulse (Long-term depression). [This project was supported by the French National Research Agency (ANR-16-TERC-0017) the LabEx DevWeCan, and the Focused Ultrasound Foundation (Centers of Excellence).]
Modeling lipid-encapsulated microbubbles using transient network theory
Authors: Alnajar Bashir M. , Sridhar Shankar L. , Borden Mark , Vernerey Franck , Calvisi Michael L.
Published: November 2019

Encapsulated microbubbles (EMBs) are widely used to enhance contrast in ultrasound sonography and are finding increasing use in biomedical therapies such as drug/gene delivery and tissue ablation. EMBs consist of a gas core surrounded by a stabilizing shell made of various materials, including polymers, lipids, and proteins. Lipid-coated EMBs present a unique challenge for modeling due to their relatively large oscillations and nonlinear, viscoelastic properties. We propose a novel model for a lipid-coated, spherical EMB that utilizes a statistically based continuum theory based on transient networks to simulate the encapsulating material. The use of transient network theory permits the viscoelastic properties of the encapsulation—such as stress, elastic energy and entropy—to be calculated locally based on the configuration of lipid molecules. The model requires a minimum number of parameters that include the lipid concentration, and the rates of attachment and detachment of lipids to and from the network. The model closely reproduces the experimentally measured radial response of an ultrasonically driven, lipid-coated microbubble. The model also reproduces experimentally observed nonlinear behavior, such as compression and expansion-dominated oscillations. Furthermore, the model can be readily extended to large nonspherical EMB deformations, which are important in many biomedical applications.
Optical coherence elastography for evaluating Rayleigh wave propagation in soft matter-micellar fluids
Authors: Liu Hsiao-Chuan , Kijanka Piotr , Urban Matthew W.
Published: November 2019

Wormlike micellar (WM) fluids exhibit a self-assembly property and viscoelastic behavior which make them a promising material for representing biological fluids, ultrasoft tissue phantoms and drug delivery carriers. Although WM biochemistry has been investigated, the mechanical properties have been rarely discussed because of the complexity of soft matter systems. Here, we demonstrate that optical coherence elastography (OCE) is capable of measuring Rayleigh wave of micellar fluids. Three solutions with concentrations of 100, 200, 300 and 400 mM, were considered in the study. Ultrasound excitation to produce Rayleigh waves was accomplished using 7.5 MHz burst excitation signals of length 4.0 ms repeated at a rate of 19 Hz. The optical coherence tomography (OCT) acquisition was set to 50 lateral positions and 4000 A-scans for each lateral position at a 76 kHz scan rate for total acquisition time of 52.6 ms. Ultrasound-based shear wave elastography, implemented on a Verasonics system, was used to obtain group and phase velocity of the shear wave in all micellar fluids as reference. Our research results demonstrated that Rayleigh wave in micellar fluids can be evaluated by OCE and mechanical properties like Young’s modulus can be assessed. A wide of concentration ranges of WM fluids would provide a more realistic model to mimic biological fluids and tissues.
Quantitative assessment of surface wave in kidney using optical coherence elastography
Authors: Liu Hsiao-Chuan , Kijanka Piotr , Urban Matthew W.
Published: November 2019

Patients with chronic kidney disease (CKD) and renal transplant rejection are at high risk to develop advanced pathology including glomerular sclerosis and renal interstitial fibrosis. The elasticity of kidney tissues is associated with the disease progression and can be evaluated with ultrasound elastography. Understanding how tissue pathology changes the renal mechanical properties is crucial. Optical coherence elastography (OCE) might be a promising tool for evaluating renal tissues due to higher resolution. A phantom with 8% gelatin and 2% cellulose (50 mm) was fabricated to validate the ability of OCE to bulk materials and the results were confirmed by comparing the dataset obtained with an ultrasound-based Verasonics system as the ground truth. Excitation signals, composed with 4 cycles of a 400 Hz harmonic wave repeated at a rate of 38 Hz, were directly applied to the surface area with two directions and cortical regions of ex vivo porcine kidneys that had been cut open. Preliminary results showed that the velocity of surface wave on the cortical regions was near 1 m/s and corresponded with the result of shear waves from Verasonics system (1.2 m/s). Our study demonstrated that OCE has an ability to assess the mechanical properties of bulk materials and is a promising tool to evaluate mechanical properties of renal tissue with high resolution and sensitivity.
Microbubbles on kidney stones contribute to the twinkling artifact in humans
Authors: Simon Julianna C. , Zinck Scott A. , Rokni Eric , Thiel Jeffrey , Dunmire Barbrina , Cunitz Bryan W. , Holm James R. , Bailey Michael R.
Published: November 2019

The color Doppler ultrasound twinkling artifact, a rapid color change that highlights kidney stones, was recently attributed to surface crevice microbubbles on ex vivo stones because twinkling was affected by changes in hydrostatic pressure. However, it was unclear whether crevice bubbles existed on in situ human kidney stones, and, if so, how smooth-surfaced stones could harbor the crevice bubbles that give rise to twinkling. Here, 8 human subjects with known kidney stones were exposed to 4 atmospheres absolute (ATA) while breathing air inside a hyperbaric chamber; twinkling was monitored and quantified with a research ultrasound system. At 3 and 4 ATA, twinkling was significantly reduced by an average of 35% and 39%, respectively (p = 0.04). Then, ex vivo kidney stones that twinkled were exposed to micro-computed tomography (μCT) and hypobaric pressures while submerged in water. Regions of low x-ray attenuation within the stone (i.e., microcracks) at 1 ATA expanded when the pressure was reduced to 0.1 ATA. These results support the theory that microbubbles are present on kidney stones in the human body and that microbubbles may be internal as well as external to the kidney stone. [Work supported by NSBRI through NASA NCC 9-58 and NIH DK043881.]
High-speed microphotography of stone breakage with Holmium:YAG lasers
Authors: Pishchalnikov Yuri A. , Behnke-Parks William , Laser Daniel , Stoller Marshall
Published: November 2019

To better understand physical mechanisms of stone comminution in Holmium:YAG laser lithotripsy, high-speed microphotography was used to study the breakage of dry stones in air and hydrated stones in water. Surgically retrieved urinary calculi and hydroxyapatite pellets were pulsed with a Holmium:YAG laser at 0.2–1 J and recorded at ∼250 000 fps using a high-speed camera (Shimadzu HPV-X2) mounted to a Nikon microscope. In air, direct light–stone interactions were seen to produce photothermal melting, vaporization, and micro-explosions. The most apparent damage to stones was due to the micro-explosions, which erupt the stone surface producing craters and pits. The micro-explosions, however, were observed to progressively diminish with number of laser shots, typically stalling after several shots. Increasing the laser energy or moving the fiber tip to a new position was seen to restore the occurrence of micro-explosions before stalling a second time. In water, the laser produced cavitation bubbles, the collapse of which continued to fragment, pit, and erode the stone after each laser pulse. This study suggests that cavitation bubbles contribute strongly to stone comminution. Cavitation bubbles may have a particularly important role in sustaining micro-explosions after initial laser shots.
Modeling 3-dimensional sound propagation using the parabolic equation
Authors: Heaney Kevin D. , Campbell Richard L.
Published: November 2019

For low frequency sound (below 50 Hz), all ocean propagation is effectively shallow water, as the impact of the seafloor topography impacts the direction and level of acoustic propagation. In this paper, we present a parabolic equation (PE) model, based upon the Range-dependent Acoustic Model (RAM), developed by Michael Collins, which was extended to handle parts of this 3-dimensional acoustic propagation problem. The model, which applies the Pade propagation operator in cross range, after each range step, is well suited to global scale problems where the effects of diffraction and refraction dominate. A quantitative comparison of observations of undersea explosions detonated off the coast of Japan measured from Chile will be presented. In addition to the presentation of this model and it’s application to several observed 3-D propagation effects, a collection of hybrid models used historically to address the out-of-plane propagation will be presented.
Use of the parabolic equation method for local infrasound propagation predictions
Authors: Swearingen Michelle E. , Alter Ross E.
Published: November 2019

Local infrasound (<150 km) propagation is strongly influenced by range- and time-dependent meteorological conditions. The Parabolic Equation computational method provides an efficient and flexible tool for predicting infrasound propagation in this regime. Over these longer distances, the influence of spatial and temporal variations in the meteorological conditions can be significant. Meteorological conditions extracted from simulations using the Weather Research and Forecasting (WRF) model are incorporated by updating the effective sound speed profile as a function of propagation range. By examining horizontal grid increments between 1 and 15 km and temporal resolutions between 4 and 60 seconds, we begin to quantify the potential variability in predictions at ranges of up to 150 km, for frequencies between 1 and 20 Hz. This procedure will inform a broader discussion of the application of the PE method to infrasound prediction. [Work funded by the Assistant Secretary of the Army (Acquisition, Logistics, and Technology) [ASA(ALT)] under 62784/T40. Distribution Statement A: Approved for public release; Distribution is unlimited.]