bluuebunny/crossref_metadata_2025 huggingface dataset:
Playback experiments for Thryothorus ludovicianus in urban backyard experiments
Authors: Knobles David P. , Badiey Mohsen
Published: May 2015

Acoustic playback experiments were performed from June 2014 to April 2015 for Thryothorus ludovicianus (Carolina Wren) in a backyard environment in Austin, Texas. Acoustic recordings were made for pre-playback, playback, and post-playback periods for multiple song types. The songs were obtained from recordings made in the backyard and surrounding neighborhood. Recordings of both the playback and acoustic responses of the bird subjects are made in coincidence with visual observations of the bird’s behavior. Bird behavior is quantified in terms of the statistics of closest distance of approach, latency to approach, latency to sing, number of post-playback songs, number of flybys, percent of male-female duets, temporal correlation of individual song phrases, and number of singing competitions with neighboring subjects. Statistics of the properties of the measured spectrograms and spatial correlation properties for experiments are presented, and attempts are made to interpret the observed behavior and acoustical responses of the birds in the form of communication and territorial defense with the bird’s ability to estimate distance using the degradation (transmission loss and reverberation) of the playback calls. It was also observed that Thryothorus ludovicianus will respond to playback calls of Cardinalis cardinalis (Northern Cardinal) and this interaction between bird species is examined.
Temperature measurement using backscattered ultrasonic power for non-invasive thermometry during HIFU ablatio
Authors: Chenot Jeremy , Melodelima David
Published: May 2015

The temperature dependence of ultrasonic tissue parameters has been reported extensively. In this work, the relationship between changes in ultrasound backscattered power and temperature during HIFU treatments was studied. An analytical model was developed based on attenuation, backscattered coefficient, velocity, and thermal expansion to predict temperature changes. In vitro and in vivo tests were conducted in liver to confirm simulations. HIFU treatments were performed using a focused transducer working at 3 MHz. The radius of curvature and the diameter were both 70 mm. An ultrasound imaging probe working at 7.5 MHz was placed in the center of the HIFU transducer. Long exposure time (120 s) was used to observe smooth temperature increase from 37 to 80 °C. Simulations predicted that backscattered power increased nearly logarithmically with temperature over the range from 37 °C to 80 °C. The model predicted a linear increase 15 dB. A linear increase 12 dB was measured in ultrasound backscattered power during experiments. The tissue temperature increase estimated using backscattered energy correlated well (r = 0.79) with temperature measurements performed using thermocouples. This linear relationship between changes in the backscattered energy and actual temperature was observed up to 80 °C. Successful temperature estimation has allowed creating 2D temperature maps during HIFU treatments
Phase I-II study of intra-operative high intensity focused ultrasound in 25 patients with colorectal liver metastase
Authors: Melodelima David , Dupre Aurelien , Perol David , Chen Yao , Vincenot Jeremy , Chapelon Jean-Yves , Rivoire Michel
Published: May 2015

The objective of this clinical study was to validate the effectiveness, accuracy, tolerance, and safety of a HIFU treatment developed for the treatment of liver metastases in a prospective, phase I-II trial. The transducer has a toroidal shape (diameter: 70 mm, radius of curvature: 70 mm) and was divided into 32 ring-shaped emitters operating at 3 MHz. HIFU was delivered immediately before scheduled hepatectomy. Ablations were performed on healthy tissue within the areas scheduled for resection. First, 30 ablations were carried out in 15 patients. These ablations were all generated within 40 seconds and on average measured 27.5 × 21.0 mm2. The phase I study (n = 6) showed that use of the HIFU device was feasible and safe and did not damage neighboring tissue. The phase IIa study (n = 9) showed that the area of ablation could be precisely targeted on a previously implanted metallic mark. Ablations were achieved with a precision of 1–2 mm. The phase IIb study (n = 10) demonstrated ablation of metastases with safety margins, again prior to planned resection. Using electronic focusing the volume of ablation was adjusted to the size of the tumor from 7 cm3 (40 s of treatment) to 50 cm3 (6 min of treatment).
A simple animal model for cerebral vasculature rupture due to exposure to intense pressure waves
Authors: Nabili Marjan , Acharya Priyanka , Kim Yeon Ho , Myers Matthew R.
Published: May 2015

Understanding the threshold of microvasculature rupture in the central nervous system is critical to evaluating the safety of transcranial therapeutic ultrasound procedures, and treatment planning for blast traumatic brain injury. The goal of this study is to determine the threshold for microvasculature rupture in a simple animal model, as a function of the characteristics of the incident pressure-pulse train. An earthworm model was chosen, as a first step in a sequence of increasingly complex models, and because of its readily accessible large vessel. Following anesthetization, the earthworms were sonicated with 3.3 MHz pulse trains from a high-intensity focused ultrasound (HIFU) transducer. A variety of pulse durations, repetition rates, and amplitudes were considered. The pulse duty cycle was kept low (0.0001 to 0.001) to minimize thermal effects. In cases where rupture occurred within 10 min of exposure, the rupture time was recorded. A noticeable threshold for microvascular damage was observed at a peak negative pressure of about 20 MPa. Beyond this pressure, rupture times decreased rapidly with increasing acoustic pressure. The threshold for damage is likely due to the onset of cavitation, though the mechanisms affecting the rupture time require further study.
An analysis of multi-year acoustic and energy performance data for bathroom and utility residential ventilation fans
Authors: Choi Wongyu , Gomez Antonio , Pate Michael B. , Sweeney James F.
Published: May 2015

Loudness levels have been established as a new requirement in residential ventilation standards and codes including ASHRAE and IECC. Despite the extensive application of various standards and codes, the control of loudness has not been a common target in past whole-house ventilation standards and codes. In order to evaluate the appropriate loudness of ventilation fans, especially in terms of leading standards and codes, a statistical analysis is necessary. Therefore, this paper provides statistical data for bathroom and utility ventilation fans over a nine year period from 2005 to 2013. Specifically, this paper presents an evaluation of changes in fan loudness over the 9 year test period and the relevance of loudness to leading standards including HVI and ASHRAE. The loudness levels of brushless DC-motor fans are also evaluated in comparison to the loudness of AC-motor fans. For AC and DC motor fans, relationships between loudness and efficacy was determined and then explained with regression models. Based on observations, this paper introduces a new “loudness-to-energy ratio” coefficient, L/E, which is a measure of the acoustic and energy performance of a fan. Relationships between acoustic and energy performances are established by using L/E coefficients with supporting statistics for bathroom and utility fans.
Evaluation and validation of the Federal Highway Administration: Traffic noise model in a sanitized environment
Authors: Rahman Monty A.
Published: May 2015

The development of powerful physics based simulation models that are dependent on stochastic parameters does not always guarantee reliability. The Federal Highway Traffic Noise Model (TNM) is such a complex model that relies on Reference Energy Mean Emission Level (RMEL) from highway vehicle-type average speed and volume to predict noise propagation in far-field environment. Although the TNM accounts for static parameters such as ground type, it does not account for changing noise source or noise propagation medium. Currently, when validating TNM, the neglected dynamic parameters in the model are usually accounted for by calibrating the model to agree with measured data. However, a model is not necessarily validated when its predicted output is compared to measured data and updated to produce desired values. This paper will review current validation procedures and assess TNM’s reliability to predict noise propagation from a highway line source within a sanitized environment. Sanitized environment is an open field within which noise propagation is independent of dynamic variables. By validating TNM within a sanitized environment TNM’s residual prediction error due only to variation in the traffic parameters (vehicle type, speed, and flow rate) could be identified and the reliability of REML used in TNM could be confirmed.
An improved two-microphone transfer function method for measuring oblique absorption coefficient in the free field using numerical modeling
Authors: Hall Hubert S. , Vignola Joseph F. , Judge John A. , Turo Diego , Ryan Teresa J.
Published: May 2015

The use of the two-microphone free field transfer function technique has remained unchanged since its development. In practice, finite sample sizes limit measurement fidelity due to edge effects. The sound field contribution from edge diffraction has generally restricted the technique from use at low frequencies (<300 Hz) and required test panels greater than several square meters in area. This effort intends to characterize the diffraction contribution to the sound field for relatively small panels. Using numerical modeling, samples of like acoustic properties were excited by a point source at normal incidence to quantify the diffraction term. Following validation via comparison with impedance tube data, the diffraction term was incorporated in an updated derivation of the complex reflection coefficient equation and validated experimentally for a known reference material at both normal and oblique incidence. The goal of this work is to validate measurements of oblique absorption coefficient in an anechoic chamber for panels smaller than one square meter at frequencies down to 100 Hz.
Reverberation mapping using instantaneous intensity estimates from a tetrahedron microphone array
Authors: Burns Thomas
Published: May 2015

For hearing aids, the directivity index is a benchmark defined under two acoustical conditions that a hearing-aid user won’t encounter, namely, the ratio of sound power signal arriving from the on-axis target in an anechoic condition to the isotropic spherical noise. It would be useful to benchmark the speech signal to noise that is encountered in a typical environment. The purpose of this study is to map the instantaneous acoustic intensity in a room using a head and torso voice simulator as the source and a regular tetrahedron microphone array in the field. Four impulse responses from a small tetrahedron were measured in a reverberant conference room of gypsum walls, carpet, and absorptive ceiling tile. Welch’s method was used to compute one-third octave estimates of the auto- and cross-spectra from the impulse responses, and these spectra were used to estimate the steady-state, 3D instantaneous acoustic intensity vector via the time-averaged active intensity and the maximum amplitude of the reactive intensity. A histogram of the instantaneous intensity vector revealed an angular estimate for the arriving sound power that was, in general, cylindrically rather than spherically “diffuse.”
Acoustic characterization of micro-perforate porous plates
Authors: Brown Martha C. , Jones Michael G. , Howerton Brian M.
Published: May 2015

The research objective of this paper is to develop an acoustic impedance model for micro-perforate plates. Passive acoustic liners consisting of perforate plates-over-honeycomb structures are a key contributor in the reduction of fan noise propagated through the inlet and aft-fan duct of aircraft engine nacelles. These perforated plates are physically characterized by plate thickness, t, orifice diameter, d, and porosity, σ, and the resultant liners are typically classified as conventional for t/d ≈ 1 or micro-perforate for t/d ≫1. Micro-perforate plates are becoming more popular because of their acoustic linearity, i.e., insensitivity to sound level. The goal of the current research is to develop models to better understand the acoustic behavior of liners constructed with micro-perforate facesheets. The first step is to model the flow resistivity of micro-perforate plates, computed as the ratio of the static pressure drop across the plate to the mean flow through the orifices. This result is then used to model the acoustic impedance, which is defined as the ratio of the acoustic pressure to the normal component of acoustic particle velocity at the liner surface. These tests are conducted in the NASA Langley Raylometer and Normal Incidence Tube with samples spanning a range of 4% ≤ σ ≤ 20% and 5.0 ≤ t/d ≤ 7.14.
Comparing time varying directivity of musical instruments across different musical motifs
Authors: Davidson Madeline A. , Hanna Kristin , Wang Lily M.
Published: May 2015

The directionality of a musical instrument can vary in time quite significantly as the instrument is used to play a musical piece, but this behavior has not been well-quantified or compared across instruments and musical motifs in previous research. Prior work conducted at the University of Nebraska has proposed quantifying this behavior by seeing how directional characteristics vary in time using overlapping one-second windows. The analyses were conducted on twenty-second long sections from 13-channel anechoic recordings of three solo instruments (flute, violin, and trombone). Maximum directivity index plots across time and space were produced to quantify and examine the time-varying directional characteristics. In this presentation, these previous results are compared against more recent results obtained from five-channel anechoic recordings of all instrument parts of both a Mozart and a Brahms symphony. The effects of reducing the time window of analysis from one second down to half-second and quarter-second time windows are also examined. Special attention is paid to how the proposed quantifiers for time-varying directivity are impacted by aspects such as tempo and dynamics in these musical compositions.
Effects of pitch, intensity, and timbre on frequency masking
Authors: Chon Song Hui , Huron David
Published: May 2015

It has been widely known that the four main factors of music—pitch, timbre, duration, and loudness—are not independent. One comes to wonder how these four factors will affect frequency masking, which has traditionally been explained with the cochlear responses to pure tones or narrowband noises. As a first step toward understanding these interactions, the mutual masking effects of two concurrent non-unison tones were investigated. A MATLAB simulation was implemented based on the psychoacoustic model in Bosi & Goldberg (2003). As the degree of masking would obviously depend on factors such as pitch, timbre, and intensity, we considered 81 pitches (B0 to G7) in three timbre categories (pure tone, uniform, and average timbre). For each timbre category, 15 levels of amplitudes were considered to examine the effect of intensity. A preliminary analysis shows that the chance of the higher pitched tone masking the lower pitched tone might change depending on the pitch, timbre, and loudness. The findings will be discussed with the implications on the interpretation of high voice superiority on the preference of melodies on the highest part in music.
Demonstration of nonlinear mode coupling in woodwind-like air columns: Recollections from the laboratory of A. H. Benade
Authors: Thompson Stephen C. , Hoekje Peter L.
Published: May 2015

Self sustained oscillations in woodwinds are generated by the player's blowing pressure, through the interaction of the standing wave in the air column, the dynamic motion of the reed and the air flow through the reed. In properly designed instruments, the oscillation begins at a threshold blowing pressure near the frequency of an air column resonance. With increased blowing pressure, the amplitude grows and the flow nonlinearity generates harmonics of the playing frequency. The nonlinearity couples the steady state components of the tone. The coupling dictates behaviors that cannot be explained by a linear model. When A. H. Benade came to understand this in the early 1960s, he developed a “tacet horn” whose unplayable behavior could only be explained by the nonlinear theory [Benade and Gans, Ann. N.Y. Acad. Sci. 155, 247–263 (1968)]. Throughout his life, Benade used other pathological air columns for research and pedagogy. This paper will demonstrate two of Benade’s concepts with air columns that are simple to build. One is a clarinet-like tube that can play softly near threshold, but cannot be played louder. The other is a conical tube that plays only at high amplitude.
Theoretical model and experimental validation of a gas-combustion infrasound source
Authors: Smith Chad M. , Gabrielson Thomas B.
Published: May 2015

The design of controlled infrasound sources is challenging due to the large volumes of air that must be moved with a source of practical size. One possible approach is to produce a periodic volume expansion/contraction by periodic heating of the air mass using a combustible-gas burner. For equal storage pressure, the available energy density from combustion of a gas is substantially higher than the available energy density from expansion of a compressed gas. While no source that is much smaller than a wavelength will be anything but inefficient, this large energy density may partially offset this basic acoustical inefficiency making gas-combustion infrasound source technology practical for use in the field. The goal of this work is to generate usable levels of sound in the 0.1 to 20 Hz frequency band for infrasound-measurement-system calibrations and propagation-path characterization. This paper presents a theoretical model and experimental demonstration of this infrasound generation method. Both theory and demonstration suggest that usable infrasound levels can be generated with a relatively compact source.
Status of digital infrasound sensors developed by the NCPA
Authors: Talmadge Carrick L.
Published: May 2015

In collaboration with Hyperion Technology Group, Inc., the National Center for Physical Acoustics (NCPA) has developed a digital infrasound sensor that can be configured for broadband outdoor measurements (flat within 3-dB from 0.03–150 Hz) and a nominal maximum transducible pressure of 200-Pa peak-to-peak, ultra-broadband measurements for calibration systems (flat within 3-dB from 0.0003-Hz to 150 Hz) and very high level sounds (up to 110 kPa peak-to-peak). This sensor has a GPS-locked digitizer that store over four months of continuously sampled data digitized at 1000 samples per second. The measurement performance of this system, including noise floor, reproducibility of measurements between sensors, linearity, mechanical robustness, etc., will be summarized.
Numerical evaluation of absorbing boundary layers for the transient Khokhlov–Zabolotskaya–Kuznetsov Equation
Authors: Zhao Xiaofeng , McGough Robert J.
Published: May 2015

FOCUS, the “Fast Object-Oriented C + + Ultrasound Simulator” (http://www.egr.msu.edu/~fultras-web), simulates nonlinear ultrasound propagation in the time-domain by numerically evaluating the transient Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation. KZK simulations in FOCUS previously required a computational grid with a large radial distance relative to the aperture radius to reduce the effect of reflections from the boundary. To decrease the size of the grid required for these calculations, an absorbing boundary layer derived from the power law wave equation provides an alternative to the stretched coordinate system in a perfectly matched layer. Simulations of the linear pressure fields generated by a spherically focused transducer with an aperture radius of 1.5 cm and a radius of curvature of 6 cm are evaluated for a short pulse with a center frequency of 1 MHz and a peak surface pressure of 0.5 MPa. Numerical results for linear KZK simulations with and without the absorbing boundary layer are compared to an on-axis analytical solution. Results of nonlinear KZK simulations with and without the PML are also evaluated, and all of these show that the absorbing layer effectively attenuates the wavefronts that reach the boundary of the computational grid. [This work was supported in part by NIH Grant R01 EB012079.]
An improved interpolation approach for rapid simulations of pulse-echo ultrasound imaging
Authors: Thomas Leslie P. , McGough Robert
Published: May 2015

New B-mode image simulation routines in FOCUS (http://www.egr.msu.edu/~fultras-web) apply linear interpolation to a finely sampled pressure signal that is calculated once per scatterer and then reused for different time delay and amplitude values in subsequent A-lines. This approach achieves more accurate results in less time than simulations that calculate the pressure waveforms on a coarser grid followed by cubic spline interpolation. To demonstrate this result, simulations are performed using 24 element sub-apertures in a linear array consisting of 192 rectangular elements that are 5mm high and 0.5133 mm wide with 0.1 mm center-to-center spacing. The center frequency of the excitation is 3 MHz for simulations of a computer phantom with 100,000 scatterers. Results for each approach are compared to a simulated reference signal calculated with the impulse response for a sampling frequency of 1 GHz. To achieve an RMS error of 6%, FOCUS requires linearly interpolated signals sampled at 16 MHz, where the stored signal was sampled at 64 MHz. The total computation time for the linear interpolation approach was 36 min, whereas the cubic spline interpolations required a frequency of 20 MHz and took 49 minto run to achieve a similar RMS error. [This work was supported in part by NIH Grant R01 EB012079.]
The effect of Parkinson disease on voice onset time: Temporal differences in voicing contrast
Authors: Whitfield Jason A. , Goberman Alexander M.
Published: May 2015

Parkinson disease (PD) affects the basal ganglia, which is involved with the selection, sequencing, and implementation of movement. Investigations suggest an extension of deficits to the speech motor and linguistic systems. Previous studies examining voice onset time (VOT) suggest that VOTs are neither systematically delayed nor systematically advanced in PD as compared to controls. The VOTs for voiced and voiceless stops are expected to differ for both individuals with PD and controls. However, inefficiencies in the sequencing and implementation of the voicing gesture may result in a smaller difference between VOT values of voiced and voiceless cognates. The current study examined VOT in individuals with PD and controls. Participants produced a corpus of stimuli to evaluate VOT using the carrier phrase “CVp again.” The four corner vowels and all stop consonants were used. Speech was recorded and VOT values were manually measured for every utterance. Overall VOTs were significantly shorter for voiceless stops across all speakers. However, the average difference between the voice and voiceless cognates produced by the PD group was significantly smaller than the control group. These data suggest that the PD group exhibited less temporal distinction between voiced and voiceless stops.
Effect of intelligibility and speech rate on perceived listener effort
Authors: Nagle Kathleen
Published: May 2015

Perceived listener effort (PLE) has been defined as the perceived “amount of mental exertion required to attend to, and understand, an auditory system” (McGarrigle et al., 2014). PLE may be affected by multiple characteristics of the speech signal, including sentence length and intelligibility. Previous qualitative data indicates that listeners are also sensitive to speaking rate. This experiment measured the effect of speech rate on PLE for speech produced with a range of intelligibility. Eleven listeners with normal hearing (HINT), working memory (WAIS-IV), and receptive vocabulary (PPVT) transcribed and rated their PLE for the 144 low-context sentences produced with a monotone electrolarynx (EL) set at 75 Hz. Speech rate (syllables per second) was measured from onset of the first word to offset of the last word. Multiple regression analysis indicated that intelligibility and speech rate accounted for a significant amount of variance in PLE scores, R2= 0.70, F(2,142) = 168.803, p < 0.001, R2adj = 0.70. Intelligibility had a unique negative effect on PLE ratings (b = −6.45, SE = 0.35), t(142) = −18.37, p < 0.001, sr2 = 0.70; however, rate was not uniquely predictive (p > 0.05). Future research should examine the association between radiated noise and PLE for EL speech.
Using the stability of vocal onsets to evaluate vocal effort in response to changing acoustical conditions
Authors: Berardi Mark L. , Hunter Eric J. , Leishman Timothy W.
Published: May 2015

Several acoustical measures have been used in the past to evaluate vocal effort. They are useful in evaluating occupational risk for teachers or other occupational voice users. Analysis of vocal onsets has been used to show vocal effort in spasmodic dysphonia. Acoustical measures are also used in clinical speech-language pathology as an inexpensive and noninvasive ways of evaluating pathology severity and tracking therapy progress. In this presentation, a single acoustic parameter based on relative fundamental frequencies of glottal pulses following voiceless consonants (the onset coefficient) is used to evaluate vocal effort in response to changes in background noise and reverberation time within speaking environments. Analysis shows that males and females have similar vocal effort levels in the most typical acoustical conditions. However, females respond to louder background noise and longer reverberation times with more vocal effort than males.
Gap detection and speech recognition in noise in younger versus older listeners
Authors: DeMetropolis Susan M. , Schoepflin Janet R. , Raphael Lawrence J.
Published: May 2015

The ability to encode information in temporal envelopes of acoustic stimuli is an important skill of the auditory system. It has been demonstrated that a listener's temporal-processing capability is predictive of performance on speech recognition, especially in noisy and complex environments (George, Festen, & Houtgast, 2006; George et al., 2007; Shen, 2014; Snell, Mapes, Hickman, & Frisina, 2002). The goal of this study was to determine whether temporal acuity using gap detection thresholds from the Gap-in Noise (GIN) test (Musiek, 2003) has any relation to the perception of speech in noise from the Revised Speech Perception in Noise (R-SPIN; Bilger, 1984). All younger listeners were between 21 and 30 years (n = 7/mean = 24.7) and older listeners (n = 4/mean = 67.25) were between 65 and 71 years old with audiometric thresholds equal or better than 15 dB HL between 250 and 8000 Hz in both ears, monolingual English, and intact cognitive skills. Results revealed that temporal acuity of older listeners was reduced compared to the younger listeners. Despite temporal processing differences between the two age groups on the GIN test, they performed similarly on the R-SPIN. Results suggest that impaired abilities to process envelope and fine structure cues of acoustic signals does not influence speech perception in background noise.
An approximation method for dispersive wave propagation
Authors: Ben-Benjamin Jonathan , Cohen Leon , Loughlin Patrick
Published: May 2015

A phase space approximation method that extends a previous single-mode approximation [Loughlin, Cohen, J. Acoust. Soc. Am. 118, 1268 (2005)] for linear dispersive wave propagation is developed. We show that each mode is governed by a Schrodinger-type equation, where the corresponding Hamiltonian operator is non-Hermitian if the dispersion relation is complex, for which case there is absorption. The propagated wave is obtained by evolving each mode according to its respective Schrodinger equation. We show how to obtain the initial modes from the initial conditions on the wave. We then formulate the propagation problem in phase space and obtain the exact equation of motion for the phase space function. We also obtain an approximate solution for the phase space evolution of the wave, which involves a simple substitution into the initial phase space function. Examples are given for a parallel plate wave guide and the beam equation. [Work supported by ONR, code 321US.]
Environmentally corrected matched filter
Authors: Camin H. John
Published: May 2015

Matched filtering is commonly used to process broadband active acoustic echoes providing higher levels of range resolution and reverberation noise suppression than can be realized through narrowband processing. Since theoretical processing gains are proportional to the signal bandwidth, it is typically desirable to utilize the widest band signals possible. However, as signal bandwidth increases, so do environmental effects that increase decorrelation between the received echo and the transmitted waveform. This loss of coherence often results in processing gains and range resolution much lower than theoretically predicted. Weiner filtering, commonly used in image processing to improve distorted and noisy photos, was investigated as an approach to correct for these environmental effects. This improved signal processing, environmentally corrected matched filter (ECMF), first uses a Wiener filter to estimate the environmental transfer function and then again to correct the received signal. This process can be viewed as a “smarter” inverse or whitening filter that optimally adjusts according to the signal to noise ratio across the spectrum. Sonar simulation toolset (SST) synthetic data and measured in-air data will be presented to illustrate the improved processing.
Time delay estimation of acoustic tones with unpredictable frequency variations under low signal to noise ratio conditions
Authors: Franklin Stephen J. , Finn Anthony , Meade Joshua
Published: May 2015

This paper describes a novel approach for autonomously detecting and tracking aircraft in the vicinity of a unmanned aerial vehicle (UAV). The time difference of arrival (TDOA) of acoustic tones emanating from the distant aircraft are correlated between spatially distributed microphone pairs located on the UAV. The geometry of multiple microphone pairs then allows the elevation and azimuth of the approaching aircraft to be estimated, despite the high levels of onboard narrow- and broadband noise emanating from the engine firing sequence, propeller, airflow over the microphones, and mechanical vibration. Current signal processing techniques estimate time delay when the signal level of the approaching aircraft is above the background signature of the sensing aircraft, despite subtle frequency variations in the narrowband components of the approaching aircraft’s signature. The technique described in this paper is designed to track these unpredictable frequency variations and thus extends the detection range of the approach by enabling estimation of TDOA when the signal level is 20 dB below the noise floor. Potential detection ranges in excess of 1 km are demonstrated when the signal processing is combined with careful suppression of the many noise sources onboard the UAV.
A follow up low frequency propagation experiment in Currituck Sound
Authors: Costley Richard D. , McNeese Andrew R. , Ballard Megan S. , Lee Kevin M. , Hathaway Kent K. , Smth Eric , Wilson Preston S. , Muir Thomas G.
Published: May 2015

An initial low frequency propagation experiment was conducted in September 2013 in which a Combustive Sound Source (CSS) generated transient acoustic signals in water depths of approximately 2.5 m [Costley et al. J. Acoust. Soc. Am. 136, 2178 (2014)]. High amplitude signals were generated mid-water column and recorded with bottom mounted hydrophones at distances up to 200 m. A time harmonic, two-dimensional axisymmetric finite element model under-predicted the magnitudes of the recorded pressure signals. A follow up experiment was conducted in October 2014. In addition to using the CSS and the bottom mounted hydrophones, a 4-element vertical line array was deployed. Measurements were made at source-receiver separations from approximately 10 m to 1000 m in 100 m increments. Additionally, acoustic properties of the sediment were obtained through in-situ measurements [McNeese et al. J. Acoust. Soc. Am. 136, 2252 (2014)]. The results of the experiment, along with results of the finite element model using updated sediment properties, will be presented. [Work supported by the U.S. Army Engineer Research and Development Center. Permission to publish was granted by Director, Geotechnical & Structures Laboratory.]
Multi-fluid cavity underwater acoustic transducer
Authors: Sang Yongjie , Lan Yu
Published: May 2015

A multi- fluid cavity underwater acoustic transducer is developed. The main structures of the transducer include inner Helmholtz resonator, Janus longitudinal vibration transducer and two outer Helmholtz resonators. The vibration of Janus transducer at low frequencies is enlarged by the inner Helmholtz resonator, and the vibration of Janus transducer at high frequencies is enlarged by the two outer Helmholtz resonators, so this kind of transducer can transmit broadband acoustic signal in water. Operation bandwidth of the multi-fluid cavity underwater acoustic transducer is usually more than two octaves. The broadband operating mechanism of the transducer is studied. The effect of some of the major structural parameters on the operation bandwidth and Helmholtz resonance frequency is studied by finite element software ANSYS. The structure size of virtual prototype is obtained. A prototype is produced based on finite element design results, the electro-acoustic performance are tested in anechoic tank. The results agree well with the simulation results. Operation bandwidth of the prototype is 500 Hz–2500 Hz, the maximum source level greater than 200 dB.
Internal- and External-Rotation Peak Torque in Little League Baseball Players With Subacromial Impingement Syndrome: Improved by Closed Kinetic Chain Shoulder Training
Authors: Lee Dong-Rour , Kim Laurentius Jongsoon
Published: May 2015

Context:

Many studies have explored closed kinetic chain (CKC) shoulder exercises (SEs) with a sling because they are safer and more effective than open-chain exercises, especially in early stages of treatment. However, the application of CKC SE in youth baseball players has rarely been attempted, although teenage baseball players also experience shoulder pain.

Objective:

To investigate the effects of CKC SE on the peak torque of shoulder internal rotation (IR) and external rotation (ER) in youth baseball players.

Design:

Single-group pretest, posttest.

Setting:

Biomechanics laboratory.

Participants:

23 Little League Baseball players with subacromial impingement syndrome.

Interventions:

The CKC SE with a sling was CKC shoulder-flexion exercise, extension exercise, IR exercise, and ER exercise. This exercise regimen was conducted 2 or 3 times/wk for 8 wk.

Main Outcome Measures:

The peak torque of shoulder IR and ER was measured using an isokinetic dynamometer. Concentric shoulder rotation was performed, with 5 repetitions at an angular velocity of 60°/s and 15 at 180°/s.

Results:

The IR and ER peak torque significantly increased at each angular velocity after the exercise program. In particular, the increase in IR and ER peak torque values was statistically significant at an angular velocity of 180°/s.

Conclusions:

CKC SE was effective in increasing shoulder IR and ER strength, demonstrating its potential benefits in the prevention and treatment of shoulder injury. In addition, increased IR peak torque appears to improve throwing velocity in baseball players.
Whole-Genome Sequencing of 10 Pseudomonas syringae Strains Representing Different Host Range Spectra
Authors: Bartoli Claudia , Carrere Sébastien , Lamichhane Jay Ram , Varvaro Leonardo , Morris Cindy E.
Published: May 2015

Pseudomonas syringae
is a ubiquitous bacterium that readily persists in environmental habitats as a saprophyte and also is responsible for numerous diseases of crops. Here, we report the whole-genome sequences of 10 strains isolated from both woody and herbaceous plants that will contribute to the elucidation of the determinants of their host ranges.
Genome Sequence of the Acidophilic Ferrous Iron-Oxidizing Isolate
Acidithrix ferrooxidans
Strain Py-F3, the Proposed Type Strain of the Novel Actinobacterial Genus
Acidithrix
Authors: Eisen Sebastian , Poehlein Anja , Johnson D. Barrie , Daniel Rolf , Schlömann Michael , Mühling Martin
Published: May 2015

Extremely acidophilic iron-oxidizing Gram-positive bacteria comprise species within the phyla
Firmicutes
and
Actinobacteria
. Here, we report the 4.02-Mb draft genome of
Acidithrix ferrooxidans
Py-F3, which was isolated from a stream draining an abandoned copper mine and proposed as the type species of a new genus of
Actinobacteria
.
Genome Sequence of the Acidophilic Iron Oxidizer Ferrimicrobium acidiphilum Strain T23
T
Authors: Eisen Sebastian , Poehlein Anja , Johnson D. Barrie , Daniel Rolf , Schlömann Michael , Mühling Martin
Published: May 2015

Extremely acidophilic iron-oxidizing bacteria have largely been characterized for the phyla
Proteobacteria
and
Nitrospira
. Here, we report the draft genome of an iron-oxidizing and -reducing heterotrophic mesophile of the
Actinobacteria
,
Ferrimicrobium acidiphilum
, which was isolated from an abandoned pyrite mine. The genome sequence comprises 3.08 Mb.
Complete Genome Sequence of Rhodovulum sulfidophilum DSM 2351, an Extracellular Nucleic Acid-Producing Bacterium
Authors: Nagao Nobuyoshi , Hirose Yuu , Misawa Naomi , Ohtsubo Yoshiyuki , Umekage So , Kikuchi Yo
Published: May 2015

Rhodovulum sulfidophilum
DSM 2351 is the nonsulfur photosynthetic bacterium that efficiently releases nucleic acids into the extracellular milieu, which leads to flocculation. In this study, we determined the complete genome sequence of
R. sulfidophilum
DSM 2351, which will provide new insights into the mechanism of its unique nucleic acid release.
Economics of alcohol-involved traffic crashes in the USA: an input-output analysis
Authors: Zaloshnja Eduard , Miller Ted R , Lawrence Bruce A
Published: May 2015

Background

Preventing traffic crashes reduces crash costs paid by employers and employees. The related savings filter through the economy, impacting its performance. This study is the first to measure the impact of traffic crash reduction on a national economy. It focuses on impaired driving crashes.

Methods

We analysed the impact of the almost 50% alcohol-involved driving crash rate reduction from 1984–1986 to 2010 and the impact if such crashes in 2010 had not occurred. The analysis entered published estimates of costs that employers, consumers and governments paid because of US impaired-driving crashes as production costs and demand changes in Rutgers University's input–output model of the US economy. For example, reducing medical costs paid by employers lowers the cost of labour inputs to production while reducing vehicle repairs raises demand for other goods. Running the model at current and alternative crash rates revealed the impacts of crash reductions on economic output, gross domestic product (GDP), national income and employment.

Results

Alcohol-involved crash reductions since 1984–1986 increased economic output in 2010 by an estimated $20 billion, raised GDP by $10 billion, increased US income by $6.5 billion, and created 215 000 jobs. GDP gains from alcohol-involved crash reduction contributed 5% of the $200 million compounded average annual growth in US GDP from 1985 to 2013. Eliminating remaining alcohol-involved crashes would result in similar economic gains.

Conclusions

Alcohol-involved crashes drag down the US economy. On average, each of the 25.5 billion miles Americans drove impaired in 2010 reduced economic output by $0.80. Those losses are preventable.
Squeezing xenon into phenylether bis-urea nanochannels
Authors: Bowers Clifford R. , Dvoyashkin Muslim , Salpage Sahan R. , Akel Christopher , Bhase Hrishi , Geer Michael F. , Shimizu Linda S.
Published: May 2015

One-dimensional nanochannels, hundreds of microns in persistence length but with elliptical cross-sectional dimensions of only ∼3.7 Å × 4.8 Å, are formed by the columnar assembly of phenylether bis-urea macrocycles. Hyperpolarized Xe-129 NMR is utilized to investigate the Xe atom packing and Xe diffusion inside the needle shaped crystals. The elliptical channel structure produces a Xe-129 powder pattern characteristic of an asymmetric chemical shift tensor extending to well over 300 ppm with respect to the gas phase, reflecting the highly anisotropic electronic environment and extreme confinement of the atom. Consistent with the simple geometrical criterion, hyperpolarized tracer exchange NMR data reveals single-file diffusion in the bis-urea nanochannels.
Using Network Traffic to Infer Hardware State
Authors: Watkins Lanier , Robinson William H. , Beyah Raheem
Published: May 2015

In this article, we illustrate that the boundary of a general-purpose node can be extended into the network by extracting information from network traffic generated by that general-purpose node to infer the state of its hardware components. This information is represented in a
delay signature
latent within the network traffic. In contrast, the traditional approach to determine the internal state of a node’s resources meant that a software application with internal processes had to be resident on the node. The aforementioned delay signature is the keystone that provides a correlation between network traffic and the internal state of the source node. We characterize this delay signature by (1) identifying the different types of assembly language instructions that source this delay and (2) describing how architectural techniques, such as instruction pipelining and caching, give rise to this delay signature. In theory, highly utilized nodes (due to multiple threads) will contain excessive context switching and contention for shared resources. One important shared resource is main memory, and excessive use of this resource by applications and internal processes eventually leads to a decrease in cache efficiency that eventually stalls the instruction pipeline. Our results support this theory; specifically, we have observed that excessive context switching in active applications increases the effective memory access time and wastes precious CPU cycles, thus adding additional delay to the execution of load, store, and other instructions. Because the operating system (OS) kernel accesses memory to send network packets, the delay signature is induced into network traffic in situations where user-level utilization is high. We demonstrate this theory in two case studies: (1) resource discovery in cluster grids and (2) network-based detection of bitcoin mining on compromised nodes.
Simplifying Data Disclosure Configurations in a Cloud Computing Environment
Authors: Hirschprung Ron , Toch Eran , Maimon Oded
Published: May 2015

Cloud computing offers a compelling vision of computation, enabling an unprecedented level of data distribution and sharing. Beyond improving the computing infrastructure, cloud computing enables a higher level of interoperability between information systems, simplifying tasks such as sharing documents between coworkers or enabling collaboration between an organization and its suppliers. While these abilities may result in significant benefits to users and organizations, they also present privacy challenges due to unwanted exposure of sensitive information. As information-sharing processes in cloud computing are complex and domain specific, configuring these processes can be an overwhelming and burdensome task for users. This article investigates the feasibility of configuring sharing processes through a small and representative set of canonical configuration options. For this purpose, we present a generic method, named SCON-UP (Simplified CON-figuration of User Preferences). SCON-UP simplifies configuration interfaces by using a clustering algorithm that analyzes a massive set of sharing preferences and condenses them into a small number of discrete disclosure levels. Thus, the user is provided with a usable configuration model while guaranteeing adequate privacy control. We describe the algorithm and empirically evaluate our model using data collected in two user studies (n = 121 and n = 352). Our results show that when provided with three canonical configuration options, on average, 82% of the population can be covered by at least one option. We exemplify the feasibility of discretizing sharing levels and discuss the tradeoff between coverage and simplicity in discrete configuration options.
User-Specific Feature-Based Similarity Models for Top-
n
Recommendation of New Items
Authors: Elbadrawy Asmaa , Karypis George
Published: May 2015

Recommending new items for suitable users is an important yet challenging problem due to the lack of preference history for the new items. Noncollaborative user modeling techniques that rely on the item features can be used to recommend new items. However, they only use the past preferences of each user to provide recommendations for that user. They do not utilize information from the past preferences of other users, which can potentially be ignoring useful information. More recent factor models transfer knowledge across users using their preference information in order to provide more accurate recommendations. These methods learn a low-rank approximation for the preference matrix, which can lead to loss of information. Moreover, they might not be able to learn useful patterns given very sparse datasets. In this work, we present UFSM, a method for top-n recommendation of new items given binary user preferences. UFSM learns User-specific Feature-based item-Similarity Models, and its strength lies in combining two points: (1) exploiting preference information across all users to learn multiple global item similarity functions and (2) learning user-specific weights that determine the contribution of each global similarity function in generating recommendations for each user. UFSM can be considered as a sparse high-dimensional factor model where the previous preferences of each user are incorporated within his or her latent representation. This way, UFSM combines the merits of item similarity models that capture local relations among items and factor models that learn global preference patterns. A comprehensive set of experiments was conduced to compare UFSM against state-of-the-art collaborative factor models and noncollaborative user modeling techniques. Results show that UFSM outperforms other techniques in terms of recommendation quality. UFSM manages to yield better recommendations even with very sparse datasets. Results also show that UFSM can efficiently handle high-dimensional as well as low-dimensional item feature spaces.