bluuebunny/crossref_metadata_2025 huggingface dataset:
Lateral Equilibrium Position Analysis Program With Applications to Electric Submersible Pumps
Authors: Norrbin Clay S. , Childs Dara W.
Published: November 2017

The long length of subsea electric submersible pumps (ESPs) requires a large amount of annular seals. Loading caused by gravity and housing curvature changes the static equilibrium position (SEP) of the rotor in these seals. This analysis predicts the SEP due to gravity and/or well curvature loading. The analysis also displays the rotordynamics around the SEP. A static and rotordynamic analysis is presented for a previously studied ESP model. This study differs by first finding the SEP and then performing a rotordynamic analysis about the SEP. Predictions are shown in a horizontal and a vertical orientation. In these two configurations, viscosities and clearances are varied through four cases: 1X 1cP, 3X 1cP, 1X 30cP, and 3X 30cP. In a horizontal, straight-housing position, the model includes gravity and buoyancy on the shaft. At 1cP-1X and 1cP-3X, the horizontal statics, show a moderate eccentricity ratio for the shaft with respect to the housing. With 30cP-1X, the predicted static eccentricity ratio is low at 0.08. With 30cP-3X, the predicted eccentricity ratio increases to 0.33. Predictions for a vertical case of the same model are also presented. The curvature of the housing is varied in the Y–Z plane until rub or close-to-wall rub is expected. The curvature needed for a rub with a 1X 1cP fluid is 7.5 deg of curvature. Curvature has little impact on stability. With both 1X 30cP and 3X 30cP, the maximum curvature for a static rub is over 25 deg of curvature. Both 1X 30cP and 3X 30cP remain unstable with increasing curvature.
Room-temperature plasma enhanced atomic layer deposition of aluminum silicate and its application in dye-sensitized solar cells
Authors: Imai Takahiro , Mori Yoshiharu , Kanomata Kensaku , Miura Masanori , Ahmmad Bashir , Kubota Shigeru , Hirose Fumihiko
Published: November 2017

The authors present a plasma enhanced room-temperature atomic layer deposition (ALD) technique for depositing aluminum silicate on TiO2 photoanodes for dye-sensitized solar cells. In the ALD process, adsorption of the precursor is completed in a two-step process involving sequential application of a subsaturation quantity of tris(dimethylamino)silane (TDMAS) and an Al precursor trimethylaluminum to the target surface. The Al-to-Si atomic ratio is controlled by the initial coverage of TDMAS on the sample surface. Aluminum-silicate coatings with a balanced composition of Al and Si are applied to the TiO2 nanoparticle photoanodes in N719-based dye-sensitized solar cells. A one-cycle ALD coating improves the short circuit current density, suggesting the enhancement of N719 dye adsorption or charge separation at the interface of the dye and TiO2 photoanode. Electro-impedance analysis suggests that the improved power generation does not correlate with the charge recombination of electrons in TiO2 and I3− ions in the redox electrolyte. The mechanism behind the improvement in the coated photoanode samples is discussed in this paper.
Atlas of the distribution of amphibians and reptiles in the Diawling National Park, Mauritania
Authors: Sow Andack Saad , Gonçalves Duarte Vasconcelos , Sousa Fábio Vieira , Martínez-Freiría Fernando , Santarém Frederico , Velo-Antón Guillermo , Dieng Hamidou , Campos João Carlos , Diagne Saer Khayar , Boratyński Zbyszek , Brito José Carlos
Published: November 2017

This study provides the first atlas of the distribution of amphibians and reptiles in the Diawling National Park (DNP), Mauritania. Unpublished fieldwork observations collected between 2010 and 2017 were combined with published records and museum data in a geographical information system to produce maps with the distribution of individual species and species richness. The taxonomic list includes 32 species, six amphibians and 26 reptiles, grouped in 17 families. Ten species are new records for the area. Species form distinct groups according to their distribution patterns and preliminary habitat selection trends: 1) species distributed in inland dunes, some extending their range to coastal dunes; 2) species distributed in inland dunes and floodplains; and 3) species associated with habitats that are permanently or seasonally flooded or that inhabit riparian forests. Three areas accumulating most of the species found are located in sand habitats of DNP and peripheral zones. Specific counts of Crocodylus suchus suggest strong seasonal fluctuations in population size inside DNP, which are likely a consequence of the human-mediated dynamics of water availability in the area
Sequential dependencies in pitch judgments
Authors: Arzounian Dorothée , de Kerangal Mathilde , de Cheveigné Alain
Published: November 2017

Studies that measure pitch discrimination relate a subject's response on each trial to the stimuli presented on that trial, but there is evidence that behavior depends also on earlier stimulation. Here, listeners heard a sequence of tones and reported after each tone whether it was higher or lower in pitch than the previous tone. Frequencies were determined by an adaptive staircase targeting 75% correct, with interleaved tracks to ensure independence between consecutive frequency changes. Responses for this specific task were predicted by a model that took into account the frequency interval on the current trial, as well as the interval and response on the previous trial. This model was superior to simpler models. The dependence on the previous interval was positive (assimilative) for all subjects, consistent with persistence of the sensory trace. The dependence on the previous response was either positive or negative, depending on the subject, consistent with a subject-specific suboptimal response strategy. It is argued that a full stimulus + response model is necessary to account for effects of stimulus history and obtain an accurate estimate of sensory noise.
Application of carbon nanotube thermophones in consumer electronics
Authors: Vaglica Stephania M. , Barnard Andrew
Published: November 2017

A thermoacoustic transducer is a device that converts electrical energy into heat energy which then generates sound energy. Carbon nanotubes (CNT) are a thermoacoustic transducer that have the ability to transform this energy. Carbon nanotubes are hexagonal lattice tubes of carbon that have diameters one ten thousandth of the thickness of human hair. These graphite allotropes of carbon have a range of different applications and properties, particularly thermoacoustic conductivity. Because of their unique thermoacoustic properties, a lightweight loudspeaker can be designed by creating an aligned film of carbon nanotubes. CNTs form nanoscale tubes that are positioned in a “forest” like configuration. Unlike a typical loudspeaker, there is no magnetic coil that generates sound. Instead, sound is generated by the nanotubes fast cooling and heating property. This cooling and heating effect will expand and contract the air around the speaker which will result in the propagation of a sound wave. This new typeof speaker creates a brand new market for speciality consumer electronics.
Northern vowel features within the deep south: The new orleans yat dialect
Authors: Carmichael Katie
Published: November 2017

Linguists have noted the distinctively Northern sound of the White, working class New Orleans English dialect locally referred to as Yat, though the features of this dialect have not been well documented phonetically. Vowel features attested include a split short-a system, BOUGHT raising, and Canadian raising of /ɑʊ/—common to Northeastern dialects but rare within the American South. In this study, I analyze the realization of these sounds within a corpus of interviews, reading passages, and word lists completed with 57 local Yat speakers, situating Yat within broader American English trends. Results indicate that in comparison to descriptions of these features in Northeastern dialects, the Yat split short-a system features slightly different phonetic triggers, BOUGHT is less raised and diphthongal, and Canadian raising appears to occur across the diphthong and not just in the nucleus. Thus, while these features do resemble those found in Northeastern dialects, there are some local distinctions. Moreover, BOUGHT raising and the split short-a system are in decline amongst younger speakers, while Canadian raising is a relatively recent innovation within the New Orleans area. Thus, Yat will likely remain a peculiar dialect within the South, despite its changing qualities.
An acoustic and phonological description of /z/-devoicing in Southern American English
Authors: Walker Abby , Southall Amy , Hargrave Rachel
Published: November 2017

In this paper, we investigate whether z-devoicing is a feature of Southern American English. 37 students from around Virginia, half of whom identified as Southern, half of whom did not, were recorded completing a picture naming task and a reading task designed to elicit /z/-final tokens. They also answered questions about their orientation and attitudes toward their hometown, Appalachia, and the South in general. Participants’ final /z/ tokens were automatically categorized as being [z] or [s] using the FAVE Aligner (Rosenfelder et al. 2011) and then acoustically analyzed in terms of duration, spectral energy measures, and voicing. The results of the categorical analysis and voicing analysis suggest that people who identify as Southern /z/-devoice at higher rates than those who do not, but only in pre-pausal environments. In fact, there appears to be significantly more voicing in Southern speech in pre-voiced environments. Additionally, within the Southern identifying participants, those who express more positive attitudes towards the South /z/-devoice more than those who do not. The results suggest that pre-pausal /z/-devoicing can be considered a socially meaningful feature of Southern American English.
Computational imaging with a frequency-diverse metasurface aperture
Authors: Smith David
Published: November 2017

We demonstrate image formation with radio frequency (RF) waves using a frequency-diverse metasurface antenna. The metasurface antenna consists of a planar cavity—formed from a double-layer, copper-clad printed circuit board—fed from one side by an RF source, and with a series of irises patterned into the opposite side. At any particular frequency, the cavity mode excited by the feed in turn excites the irises, each of which radiates as a magnetic dipole element. The cavity walls (fabricated using vias patterned into the circuit board) are irregular, so that the excited cavity modes exhibit considerable variation as a function of frequency. Thus, the radiated fields from the cavity-backed metasurface tend to have a series of randomly directed lobes, the number and directions of which vary significantly as a function of frequency. These radiation patterns can be used to form measurements of a scene, with the scene then estimated using computational imaging techniques. We have applied the metasurface aperture in a prototype imaging system capable of acquiring high resolution images of human-scale targets. The metasurface aperture design and reconstruction methods are general, and can be easily adapted for acoustic imaging.
Metamaterial-based passive phased arrays: Resolution, losses, and characterization
Authors: Zhang Likun , Mobley Joel , Jiang Xue , Li Yong
Published: November 2017

Metamaterial and metasurface-based passive phased arrays provide novel means for the manipulation of acoustic fields. As passive elements, metasurfaces can provide local phase delays which enable the steering of sound fields and facilitate extraordinary wave phenomena. Some aspects that affect the performance of these passive elements include the spatial resolution/aliasing effect, the component resonances that shape the transmission spectra, and the thermoviscous losses that limit the transmission efficiency [X. Jiang, L. Yong, and L. Zhang, J. Acoust. Soc. Am. 141(4), EL363–368, April 2017]. Efficient acoustic field characterization is essential for investigating these issues with the ultimate aim of optimizing the geometrical parameters of the structure. This talk will address some details of the physics of metamaterial-based passive arrays and the broadband approach for assessing their transmission properties, with the aim of improving the design cycle and exploring novel uses.
Deconvolution methods to obtain the impulse response of acoustic metamaterial samples of finite extent
Authors: Spratt Kyle S. , Cushing Colby W. , Lee Kevin M. , Wilson Preston S. , Haberman Michael R. , Su Xiaoshi , Norris Andrew
Published: November 2017

One complication of characterizing the response of acoustic metamaterials is that models often assume the medium is of infinite extent. On the other hand, material property measurement can only be done with samples of finite size. The result is that acoustic field measurements include the effects of edge diffraction and scattering from fixtures. This work presents deconvolution methods to extract the frequency-dependent reflection and transmission behavior of acoustic metamaterial samples. Measurements using broadband chirp signals are obtained and subsequently post-processed using deconvolution techniques to obtain high-time-resolution impulse responses. Additionally, the chirp signals can be modified to compensate for the frequency response of the transducers being used. Examples will be shown for the transmission behavior through a two-dimensional pentamode gradient index lens and the reflection response of a flat square plate. [Work supported by ONR.]
Assessment of the proportion of anthropogenic underwater noise levels in passive acoustic monitoring
Authors: Mustonen Mirko , Klauson Aleksander , Tommingas Mihkel , Berdnikova Julia
Published: November 2017

The marine environment faces a pressure from the increasing shipping intensity in the form of rising levels of continuous anthropogenic underwater noise. Current underwater noise monitoring guidelines advise to measure the long-term trends in the overall noise levels in the frequency bands where ship noise is most prevalent. However, the natural noise is omnipresent and prolongs the time period required for the detection of statistically significant trends in the overall noise. The monitoring efficiency can be improved by finding the proportions of the anthropogenic and the natural noise levels and by measuring the changes in the proportions over time. These proportions can be found by differentiating between the two types of ambient noise in the recordings according to both proximity of the ships and the variability of the environmental conditions. This is achieved by using the AIS ship traffic data along with the ship noise detection algorithms. The AIS data enable to determine the position of ships around a noise monitoring location and calibrate the ship noise detection algorithms. The results and the methods are presented for the passive acoustic monitoring in the Baltic Sea and applicability of the described methods are discussed.
The marine soundscape off the Isle of Mull in Scotland's Inner Hebrides
Authors: Roland Adele , Wage Kathleen E. , Parsons E. C. M.
Published: November 2017

The waters around the Isle of Mull, Scotland are home to minke whales, basking sharks, common and bottlenose dolphins, harbor porpoises, and many fish and marine invertebrates. This talk describes the soundscape of this region, measured as part of a study on minke whale (Balaenoptera acutorostrata) acoustic habitat use, conducted June–September 2016. The study area consists of shallow (<100 m depth) shelf waters between and around the Islands of Mull, Coll, and Muck. Measurements were made with a Soundtrap 300 from multiple points over the study area (~560 km2) at a sampling rate of 288k Hz. Recordings were taken at a depth of ~30 m from a whale watching vessel when it was stopped (usually observing marine wildlife). The study includes 131 recordings with durations of 5–40 min. Spectral density varies with location and time over the study. Temporal and regional variation and the identity of various sounds are analyzed. Most of the acoustic energy in the region is concentrated below 50 kHz. The soundscape is dominated by wave noise, snapping shrimp, and distant dredging. Local areas or times may be dominated by transient biological sounds, e.g., the calls of common dolphins. Regular but infrequent ferry passage temporarily alters the base soundscape.
The acoustic energy conversion efficiency of a single raindrop
Authors: Shang Dajing , Li Qi , Liu Shu , Deng Fangzhou
Published: November 2017

The measurement of rainfall in the ocean is more difficult than in land, but the noise signals produced by rainfall can be used for measuring the rainfall in the ocean. In this paper, a single raindrop measurement system was set up to measure the noise of the raindrop, the bubble sound is classified by the radius of the raindrop which was measured by the splash method. The mechanism of the initial impact and the bubble sound are analyzed, and the kinetic energy threshold and acoustic energy conversion efficiency of the single raindrops is also investigated. The results show that the bubble sound is the main compared with initial impact sound, the initial impact sound will become larger with the radius of raindrop, the bubble acoustic energy of large and great raindrop is much larger than that of small one, but the tiny and medium raindrop have no bubble acoustic energy. The kinetic energy threshold is not a constant, but proportional to the raindrop size. The acoustic energy conversion efficiency is about 1.04×10-3% for small raindrops, but 10-5% for heavy rain and great raindrops.
Ship source strength estimation in shallow water
Authors: Klauson Aleksander , Mustonen Mirko
Published: November 2017

Continuous underwater noise from the commercial ship traffic is an important pressure on the marine environment. The environmental assessment of this pressure often includes both measurements and modeling. In order to model ship noise based on AIS traffic data, it is essential to provide a better Source Level (SL) input values for the individual ships. The SL can be estimated using underwater noise recordings along with the identified position of the ships. A good estimate of the SL in the deep water can be obtained by application of the spherical spread model. In the shallow water such an approach is inapplicable because of multiple interactions of the sound waves with the sea surface and the bottom and therefore sound propagation modeling should be applied. If the modeling is performed for some particular frequency bands, estimation of the transmission loss needs even more calculation effort. Simplified approach for more efficient calculation of the losses is proposed. The calculated results are compared with the measurements in different geographical positions and sea conditions. The topic of the ship source directionality is addressed. Repeatability of the results is checked for the different passages of the same ship during the year.
In-water impact pile driving sound source spectra comparison and the quest for a “Generic Spectrum”
Authors: Guan Shane , Austin Melanie , Vignola Joseph F.
Published: November 2017

Noise generated from in-water impact pile driving for marine and coastal construction can impact marine mammals. Physiological effects to marine mammals include hearing impairments such as temporary and/or permanent threshold shifts. Because marine mammals’ auditory response to sound levels is frequency-dependent, environmental impact analysis from noise exposure needs to consider noise spectrum in addition to broadband received level. In this study, spectral characteristics of measured noise levels from impact driving of 30-inch steel piles at four locations in Alaska and Washington were compared. Results show for all impact pile driving, most acoustic energies were between 100 and 1,000 Hz. Spectral levels below 100 Hz varied among the locations. Above 1,000 Hz, spectral levels decayed at a rate of 15 dB/decade for the three Alaska sites, but at 30 dB/decade in Washington. Despite these general characteristics, however, there does not seem to be a “generic spectrum” for the 30-inch steel pile impact driving. The variations among the spectral characteristics are likely due to differences in substrate, hammer energy, and bathymetry in different locations.
Active acoustics in multi-purpose venues: A ten year retrospective
Authors: Ellison Steve , Parker Melody
Published: November 2017

Multi-purpose venues better serve diverse programs by tailoring their acoustics for each use condition. Active acoustic systems use electronics to provide wide-ranging acoustic adjustability with the press of a button. Over the past decade, the Constellation acoustic system by Meyer Sound has been deployed in over one hundred venues, supporting the performing arts, worship, education, and corporate sectors. This paper presents a survey of such venues and discusses lessons learned.
Multi-purpose performance spaces as vehicles to enhance the acoustical communities of cities and towns
Authors: Siebein Gary W. , Roa Marylin , Miller Jennifer R. , Vetterick Matthew
Published: November 2017

Soundscape theory can offer insights into methods that can transform the design of multi-purpose performance venues so that they can come closer to fulfilling their potential as a vibrant facility at the artistic and cultural core of a community every day of the year all day long. This is a design theory guided by technical innovation and philosophical insight that can bring together diverse groups of users and performers; experimental building, acoustical and theatrical systems; and sophisticated, integrative design methods. Case studies of several architectural design studio projects that ask questions about the nature of performance in the city will be used to describe an approach to integrated architectural and acoustical design based in soundscape theory that brings forth new approaches to using sound to shape space rather than designing spaces and inserting acoustical envelopes within the spaces based on transformative mapping of interior and exterior space created by sound and the ways that it is enhanced when it interacts with buildings.
Multi-purpose halls… Wave of a new future or dead-end?
Authors: Scarbrough Paul H. , Blair Christopher
Published: November 2017

Multi-purpose halls, that is, performance spaces that can adapt their acoustical and technical features to serve many different performance types are a uniquely North American invention. Europe, where the modern-day symphony orchestra, opera company, ballet company, and drama troupe all originated, favors halls that are purpose-built to serve each art form. In the United States and Canada, even in cities that could afford to field multiple ensembles or companies, building dedicated facilities for each art form was often a bridge too far. This gave rise to the multi-purpose hall and with it the old saw that multi-purpose meant no-purpose. The success of new venues in Charleston, San Antonio, León, México, and elsewhere demonstrates that multi-purpose halls are cost-effective solutions and that they need not be the compromises they once were. The authors will explore the development of multi-purpose halls starting with Louis Sullivan’s Auditorium Theater in Chicago, arguably the forerunner of the contemporary multi-purpose hall, through to the current day. The authors will also explore how the evolving creative impulses of artists and directors is challenging designers to go even further, and incorporate degrees of flexibility into these spaces that would have been unimaginable just two decades ago.
Sixteen years later—Skirball Center for the performing arts at NYU completes the installation of Electronic Architecture
Authors: Barbar Steve
Published: November 2017

The Skirball Center for the Arts at New York University was designed to be a multi-purpose venue with Electronic Architecture providing variable acoustics. Although the infrastructure (wiring, loudspeakers) was integrated during construction in 2000, the system was not completed and remained idle since that time. In 2016, New York University decided to complete the system installation. We will discuss the nature of the venue and its programming, the reasons that the system remained dormant for so long, and the changes that sparked interest in completing the system.
Narrowband auditory brainstem responses to “self-heard” and external clicks in the bottlenose dolphin
Authors: Houser Dorian S. , Mulsow Jason , Finneran James J. , Schlundt Carolyn E.
Published: November 2017

Knowledge of the emitted click or chirp in echolocating dolphins and bats is believed to be critical to using echo delays to reveal target range and shape. In dolphins, the neural representation of the “self-heard” click should not equate to that of a click measured in the far-field due to sound propagation path differences and temporal dispersion within the cochlea. To investigate these differences, auditory brainstem responses (ABRs) to self-heard clicks masked with noise bursts having various high-pass cutoff frequencies were measured in two dolphins. A passive listening experiment was also conducted in which similarly masked external, spectrally “pink” clicks were used as stimuli. In both experiments, narrowband ABRs were derived using a high-pass subtractive noise technique. Latencies of the ABR to the external click demonstrated frequency-dependent latency shifts. Latencies of the ABR to the self-heard click were delayed relative to those of the passive listening experiment and similar across frequencies from ~28 to 113 kHz, suggesting that neural responses to the self-heard click are synchronous within the bandwidth of echolocation. Longer ABR latencies are potentially due to spectral differences between external and self-heard clicks, click-induced forward masking, and possibly, neural inhibition associated with click production.
Non-auditory, electrophysiological potentials preceding biosonar click production in bottlenose dolphins
Authors: Finneran James J. , Mulsow Jason , Jones Ryan , Houser Dorian S. , Accomando Alyssa W. , Ridgway Sam H.
Published: November 2017

The auditory brainstem response (ABR) to a dolphin’s own emitted biosonar click may be measured by averaging epochs of the instantaneous electroencephalogram (EEG) that are time-locked to the emitted click. In this study, waves in the averaged EEG preceding the biosonar click-evoked ABR were measured using surface electrodes placed on the head in six configurations while dolphins performed an echolocation task. Simultaneously, clicks were measured using contact hydrophones on the melon and a hydrophone in the farfield. The results revealed an electrophysiological potential (the pre-auditory wave, PAW) preceding the production of each biosonar click. The largest PAW amplitudes occurred with the non-inverting electrode just posterior of the blowhole and right of the midline — the apparent side of biosonar click generation. Although the source of the PAW is unknown, the temporal and spatial properties rule out an auditory origin. The PAW may be a myogenic potential associated with click production; however, it is not known if muscles within the dolphin nasal system can be actuated at the rates reported for dolphin click production, or if sufficiently coordinated and fast motor endplates of nasal muscles exist to produce a PAW detectable with surface electrodes. [Work supported by ONR.]
Microbiota and macrobiota alterations impact acoustic predictions of geotechnical sediment properties
Authors: Reed Allen H.
Published: November 2017

Computed tomography supplies a three-dimensional vision of sedimentary geometries that are fabricated by microscopic and macroscopic biota. The biota alter sediment structure and properties in such a way that the altered sediment structure impacts acoustic determinations of idealized seafloor properties, which are based upon grain size and associated, yet textbook, geoacoustic properties. The presence of these alterations affects propagation by scattering acoustic energy at density discontinuities and non-planar surfaces (aka ”seafloor roughness”) both of which have a likely impacts: dampening of signal strength and increases in reverberation. The result is that the information sought about the seafloor is obscured; sediment properties, composition, strength, and potential for deformation and mobility are ambiguous and poorly constrained from available acoustic information in areas where biological activity significantly alters the sediment structure. Here, the three-dimensional geometry of the microbiotic and macrobiotic impacts on sediments are presented in images that display unique features, which are often discounted in sediment acoustic models, but which should be considered as important and highly relevant sources of uncertainty with respect to acoustic determinations of the seafloor geotechnical and geophysical properties.
Comparison between infauna abundance and seabed geoacoustic properties
Authors: Lee Kevin M. , Ballard Megan S. , McNeese Andrew R. , Ballentine Will M. , Dorgan Kelly M. , Venegas Gabriel R. , Wilson Preston S.
Published: November 2017

To investigate the effects of infauna on seabed geoacoustic properties, a field experiment was conducted during May 2017 in Petit Bois Pass, near the mouth of Mobile Bay, Alabama. In situ measurements of seabed geoacoustic properties were collected using hydrophones to generate and receive compressional waves from 5 kHz to 100 kHz and bimorph transducers to measure shear waves from 300 Hz to 1.5 kHz. The measurement system was deployed multiple times at three distinct sites within the pass, and acoustic measurements were conducted at depths ranging from 5 cm to 20 cm into the sediment. For each deployment of the acoustic system, diver cores were collected. A subset of the cores were sieved on site to collect infauna, and the remaining cores were taken back to the laboratory where they were sectioned and analyzed for porosity and grain size distribution. Comparison between compressional and shear wave speed and attenuation, the sediment geotechnical properties, and the distribution and abundance of infauna will be presented. [Work supported by ONR and ARL:UT IR&D.]
Low-frequency acoustic behavior of photosynthetically active seagrasses
Authors: Johnson Jay R. , Hermand Jean-Pierre , Wilson Preston S.
Published: November 2017

Acoustic remote sensing techniques are an important tool for mapping seagrass coverage. Three different photosynthesis-related processes can occur in seagrasses that affect the acoustic behavior. First, the air channels within the leaf pressurize with produced gas. Next, bubbles form on the leaf blades. Finally, some of these bubbles break off and enter the water column. A one-dimensional acoustic resonator technique was adapted to monitor the photosynthetic activity of two Mediterranean seagrasses, Posidonia oceanicaand Cymodocea nodosa. Measurements of the low-frequency (1–8 kHz) effective sound speed of a mixture of seagrass leaf blades and artificial seawater were taken at regular intervals during periods of no direct light and exposure to photosynthetically active radiation. The acoustic response is compared to independent dissolved oxygen measurements and visual observation of bubble formation.
Time domain analysis of ultrasonic backscatter signals from cancellous bone
Authors: Ankersen Jordan P. , Sharp Phoebe C. , McPherson Joseph A. , Viano Ann , Hoffmeister Brent
Published: November 2017

Ultrasonic backscatter techniques are being developed to detect changes in bone caused by osteoporosis. Most techniques analyze backscatter signals in the frequency domain by measuring quantities related to the power spectrum. Investigate the utility of two backscatter parameters determined from a time domain analysis of backscatter signals: the normalized backscatter amplitude ratio (nBAR) and the backscatter amplitude decay constant (BADC). A 3.5 MHz transducer was used to acquire backscatter signals from 54 specimens of bone prepared from 14 human femurs. nBAR was determined from the log of the ratio of the root mean square amplitude of two different portions of a backscatter signal. BADC was determined by measuring the exponential decay in the amplitude of a backscatter signal. nBAR and BADC both demonstrated highly significant (p < 0.001) linear correlations with bone density. However, the correlation coefficients were slightly stronger for nBAR (0.79 ≤ R ≤ 0.89) than for BADC (0.67 ≤ R ≤ 0.73). Parameters based on a time domain analysis of backscatter signals from bone may be sensitive to changes in bone caused by osteoporosis. Of the two parameters tested, nBAR demonstrated the strongest correlations with bone density. [Funding: NIH/NIAMS R15AR066900.]
Correlation of ultrasonic backscatter difference parameters with bone density in clinical ultrasound images
Authors: Diaz Abel , Viano Ann , McPherson Joseph A. , Garra Brian S. , Hoffmeister Brent
Published: November 2017

The ultrasonic backscatter difference technique analyzes the power difference (in dB) between two gated regions of a backscatter signal and is being used to detect changes in bone caused by osteoporosis. The current study investigates correlations with bone density for these parameters determined from clinical ultrasound data. Ultrasonic backscatter images and signals were acquired from the hip and two vertebral bodies of human subjects using a 2.5 MHz phased-array transducer. Three backscatter parameters- normalized mean, slope, and intercept of the backscatter difference- were determined from the power difference between two gated regions of the signal. All three parameters were analyzed for 25 different gate choices. X-ray bone mineral density data for each subject were acquired for the three anatomical regions. Significant linear correlations (p<0.05) were found for all three ultrasonic parameters for at least one choice of gate parameters. R values ranged from to 0.38 to 0.63. For the first time, backscatter difference parameters measured in vivo have been shown to correlate with bone density. The correlation may depend on the gated regions of the backscatter signal chosen for analysis. [Funding: NIH/NIAMS R15AR066900.]
Recovery of the complete data set from ultrasound sequences with arbitrary transmit delays
Authors: Bottenus Nick
Published: November 2017

Ultrasound beamforming relies on particular models of propagation to convert samples of the backscattered field through time into spatial samples of an image. The most common model used is straight-line propagation of a focused wave, assuming a narrow steered and focused beam that propagates radially along a selected direction. This model describes the main propagating pulse but fails to capture the true spatial extent of the wave. The reconstructed image suffers from defocusing, reduced signal-to-noise ratio (SNR), and contrast loss. A method is proposed to model transmission as the superposition of individual transmit elements on the transducer array and to efficiently recover the “complete data set,” individual element transmit and receive responses, from an arbitrary scan sequence. Standard diverging wave focusing is applied to the complete data set to produce an image independent of the applied transmit focusing. For a sequence with a fixed transmit focus, the result is a high-SNR, two-way focused image. The proposed method also improves upon other synthetic transmit aperture methods such as plane wave imaging in that it captures the full diffracting wave field rather than relying on approximate field models, maximizing SNR at depth. Phantom and in vivo images are used to demonstrate improvement.
Validation of a wide-angle parabolic model for shallow-focus ultrasound transducers
Authors: Soneson Joshua , Liu Yunbo
Published: November 2017

Recently, a novel numerical method was developed for a wide-angle parabolic equation which accommodates steep gradients and discontinuities in the pressure distribution of the source boundary condition (Soneson, IEEE Trans Ultrason., Ferroelectr., Freq. Control 64, pp. 679–687, 2017). The method allows rapid computation of acoustic fields with improved diffraction modeling capability over the standard parabolic approximation of the Helmholtz equation with no additional computational overhead, and is free from oscillatory artifacts which previously precluded the use of wide-angle models with discontinuous sources. In this work the wide-angle model, using the expression of a converging spherical wave (with a sharp cutoff at the edge of the active area) as the source boundary condition, is validated against measurements obtained using a 200 μm membrane hydrophone. The ultrasound field was produced by a single-element transducer with f-number 0.7 at 1.5 MHz, which was selected to test the wide angle model’s account of diffraction physics well outside the regime of the standard parabolic model. Close agreement between the measured and computed fields is shown along the central axis and in the focal plane. This analysis represents a critical component of the rigorous validation of the model, which will come with a forthcoming uncertainty analysis.
Mapping the electrical activity of the heart in vivo using ultrafast acoustoelectric imaging
Authors: Berthon Beatrice , Mateo Philippe , Ialy-Radio Nathalie , Tanter Mickael , Pernot Mathieu , Provost Jean
Published: November 2017

The heart is driven by an electrical activation that propagates in cells and triggers their concerted contraction. When this electrical activation pattern is altered, it can lead to debilitating diseases such as arrhythmia or heart failure. Yet, directly imaging the electrical activity of the heart remains difficult to achieve. We have recently introduced Ultrafast Acoustoelectric Imaging (UAI) that combines ultrasound plane wave emissions and the acoustoelectric effect, i.e., the modulation of electrical impedance by ultrasound waves, to map electrical current densities in real-time with 1-mm and 5-ms spatial and temporal resolutions, respectively. Herein, we present its application to direct mapping of the cardiac activation in isolated live rat hearts and in pig hearts in vivo. UAI was performed in isolated rat hearts (n = 4) and in open-chest pigs (n = 1) using a 5-MHz linear array ultrasound probe fitted to a 256 channel- Vantage ultrasound system (Verasonics, Inc., WA). Two electrodes positioned on the heart and fed to the Vantage system were used to detect electrical impedance variations caused by ultrasound plane waves, which were then backprojected to reconstruct images of electrical current densities. UAI images depicted the propagation of the electrical activation of the cardiac tissue as validated by the electrocardiogram. These first in-vivo results suggest that UAI may allow the emergence of new biomarkers for the diagnosis and pre-clinical study of cardiac activation diseases such as arrhythmias.
The Coffee-Can radar at the naval academy
Authors: Coxson Gregory E. , Keyes Erich
Published: November 2017

The Coffee-Can radar was designed by Professor Gregory Charvat as a simple low-cost radar system for small teams of students to build and test during an intersession course at MIT. The name derives from the use of coffee cans as transmit and receive antennas. Since the success of Charvat’s course, the coffee-can radar has been used at a number of schools for hands-on experiences with radar. It is one of the small radar systems used in courses in Principles of Radar at the United States Naval Academy, where laboratory and project-based learning are necessary components of the educational experience. This paper will describe how the radar operates, and will explain the role this radar plays in the Naval Academy’s Principles of Radar and EW course. Attendees will receive a demonstration of the radar’s three modes: ranging, range-rate estimation, and synthetic aperture imaging; and will have the opportunity to operate the radar. Additional small radar systems used in the Principles of Radar course will be available as well.
Subjective assessment of wind turbine noise—The stereo approach
Authors: Cooper Steven E. , Chan Chris
Published: November 2017

The conduct of stereo measurements for both playback in high-quality headphones and in a hemi-anechoic room has been undertaken for a number of wind farms and other low-frequency noise sources as an expansion on the material previously presented at the Boston ASA meeting. The results of the additional monitoring, evaluation of modulation index, and subjective analysis of this procedure is discussed and identifies the benefits of monitoring noise complaints and assessments of wind farm noise in stereo.
Wind turbines—A Cape Bridgewater residents' experience
Authors: Ware Melissa , Cooper Steven E.
Published: November 2017

In 2008, 29 2 MW wind turbines were built on neighboring properties, 850 m from our solid limestone home. Having a bilateral senso-neuro hearing loss may result in a different experience. The experiences of living near a wind farm, the consequences, and involvement in the Cape Bridgewater Study are discussed.
Noise prediction of axial fan duct using a lattice Boltzmann approach
Authors: Hayashi Kentaro
Published: November 2017

Large axial fans in fire power plants are noise source of the plants, they are required to reduce the noise level. Fan noise propagates in a fan duct, and since it is emitted to the exterior, silencers are used as countermeasure in general. It is important for noise reduction to predict noise generation and noise propagation in fan ducts. The Lattice-Boltzmann Method (LBM) based approach was applied for the unsteady simulation of axial fan and its duct to predict fan noise generation and sound propagation simultaneously. The LBM has minute numerical viscosity, and is suitable for the analysis of the sound propagation and the flow field. In this research, aeroacoustic analysis by using applicable analysis model in the design phase has been conducted and validated compared to experimental results. The results shows good agreement with experiment within 3dB at overall value and predicted spectra are also compared with experimental results.
A technical overview of the LIGO detectors
Authors: Mullavey Adam
Published: November 2017

The LIGO detectors are a technological marvel, the culmination of ~50 years of research and development, that have opened up a new window on the universe by making the first detections of gravitational waves. The LIGO detectors can measure strain caused by gravitational wave perturbations down to 10-23 (at their most sensitive frequency band). In this talk, I will give an overview of the techniques that have allowed us to reach such incredible precision, and where possible relate said techniques to the field of acoustics.
Gravitational-wave detectors: Upgrades and new facilities
Authors: Dooley Katherine
Published: November 2017

The LIGO observatories have detected gravitational waves, but even so there's much that can be done to further improve their sensitivity. I will describe plans to upgrade the existing Advanced LIGO detectors as well as design studies for new detectors in brand new facilities.
Computational modeling of human isolated auditory word recognition using DIANA
Authors: Nenadic Filip , ten Bosch Louis , Tucker Benjamin V.
Published: November 2017

In recent years, computational modeling has proved to be an essential tool for investigating cognitive processes underlying speech perception (see, e.g., Scharenborg & Boves, 2010). Here we address the question of how an end-to-end computational model that uses the acoustic signal as input simulates behavioral responses of actual participants. We used the Massive Auditory Lexical Decision (MALD) database recordings comprising of 26,800 isolated words produced by a single male native speaker of English. MALD response data came from 232 native speakers of English, with each participant responding to a subset of recorded words in an auditory lexical decision experiment (Tucker et al., submitted). We applied DIANA, a recently developed end-to-end computational model of word perception (Ten Bosch et al., 2013; Ten Bosch et al., 2015) to model the MALD response latency data. DIANA is a model that takes in the acoustic signal as input, activates internal word representations without assuming prelexical categorical decision, and outputs estimated response latencies and lexicality judgements. We report the results of the participant-to-model comparison, and discuss the simulated between-word competition as a function of time in the DIANA model.
Individual differences in perceptual adaptation to phonetic categories: Categorization gradiency and cognitive abilities
Authors: Kim Donghyun , Clayards Meghan , Kong Eun Jong
Published: November 2017

We examine whether listeners flexibly adapt to unfamiliar speech patterns such as those encountered in foreign-accented English vowels. In these cases, the relative informativity of acoustic dimensions (spectral quality vs. duration) can be changed such that the most informative dimension (spectral quality) is no longer informative, but the role of the secondary cue (duration) is enhanced. We further test whether listeners’ adaptive strategies are related to individual differences in utilizations of secondary cues (measured by categorization gradiency) and cognitive abilities. Native English listeners (N = 36) listened to continuum of vowels /ɛ/ and /æ/ (as in head and had) varying spectral and duration values to complete a perceptual adaptation task, a visual analogue scaling (VAS) task, and were given cognitive ability tasks examining executive function capacities. Results showed that listeners mostly used spectral quality to signal vowel category at baseline, but rapidly adapted by up-weighting reliance on duration when spectral quality was no longer informative. The VAS task showed substantial individual differences in categorization gradiency with more gradient listeners using a secondary cue more, but gradiency was not linked to degree of adaptation. Finally, results of cognitive ability tasks revealed that individual differences in inhibitory control, but not the other cognitive abilities, correlated with the amount of perceptual adaptation.
Effect of musical experience on learning to understand vocoded speech
Authors: Laursen Kieran E. , Williams Iain C. , Marquardt Tahnee , Prostko Sara L. , Gottfried Terry L.
Published: November 2017

This study explores whether musicians have an advantage over non-musicians in processing and comprehending 8-channel vocoded speech, spectrally degraded speech that imitates cochlear implant output (see Loebach, Bent, & Pisoni, 2008). Musicians and non-musicians completed a pre-test in which they were asked to transcribe a number of vocoded sentences and words. Afterwards, they completed training on either vocoded or natural stimuli. After training, participants completed post-tests during which they transcribed vocoded speech, including items from the original test and from new speakers and 4-channel vocoded stimuli. In preliminary studies, musicians showed no advantage over non-musicians, and contrary to expectations, participants in natural-speech training condition improved more from pre- to post-test vocoded word recognition than participants in the vocoded training condition. Current studies are examining the relation of rhythmic and melodic perception (Musical Ear Test, Wallentin et al., 2010) to performance on the vocoded speech learning; the vocoded and natural speech training tasks are also compared to a control training task (testing sine-wave tone detection). Results of these tests will be used to evaluate the extent to which musical ability and training may be related to perception of degraded speech.