bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient behavior in quasi-atomic layer etching of silicon dioxide and silicon nitride in fluorocarbon plasmas
Authors: Huard Chad M. , Sriraman Saravanapriyan , Paterson Alex , Kushner Mark J.
Published: October 2018

The mechanism for atomic layer etching (ALE) typically consists of two sequential self-limited half-reactions—passivation and ion bombardment—which provide unique control over the process. Some of the possible benefits of this control include increased selectivity, reduced plasma induced damage, improved uniformity and aspect ratio independence. To achieve the greatest benefit from ALE, both half-reactions should be fully self-limited. In the experimental demonstration of ALE of SiO2 using fluorocarbon plasmas, the passivation phase typically consists of deposition of fluoropolymer on the SiO2 surface. This passivation step is not a self-limited reaction as the final polymer thickness depends on the passivation time. In this paper, results are presented from a computational investigation of the ALE of SiO2 and Si3N4 focusing on the implications of this nonself-limited passivation phase. The polymer overlayer was found to be critically important to the ALE performance, providing the main mechanism for selectivity between SiO2 and Si3N4. The polymer overlayer acts as a fuel for etching SiO2, which couples the etch depth per ALE cycle to the passivation time. Due to the inherently pulsed nature of the ALE mechanism, the polymer overlayer requires a finite number of cycles to reach a pulsed periodic steady-state thickness. Since the thickness of the polymer overlayer largely determines selectivity between SiO2 and Si3N4, the initial formation of an overlayer results in a transient period at the beginning of etching where high selectivity may not be achieved. For the etching of thin films, or applications which require very high selectivity, this transient etching period may be a limiting factor. Results are also presented using ALE to etch high aspect ratio self-aligned contacts which could not be cleared using continuous plasma etching with similar ion energies and flux ratios.
Relativistic description of the photoelectric effect
Authors: Güémez Julio , Fiolhais Manuel
Published: October 2018

Einstein's famous explanation of the photoelectric effect is addressed using the Minkowski four-vector formalism. This formalism deals with energy and linear momentum simultaneously and it is Lorentz covariant. The energy and momentum equations for both electron emission and electron braking are obtained in the lab frame S. It is then shown that the energy and momentum equations for electron emission and electron braking in a second inertial frame S′ are linear combinations of the corresponding equations in the original frame S, according to the principle of relativity. Although the photoelectric effect is basically a non-relativistic phenomenon, the approach presented here may provide new insights for both instructors and students.
Estimation and experiment for sound absorption coefficient of three clearance types using a bundle of nested tubes
Authors: Sakamoto Shuichi , Tanikawa Hirohiko , Maruyama Yuki , Yamaguchi Kohei , Ii Kohei
Published: October 2018

Closely packed nested structure circular tubes form three types of clearances: circular clearances, concentric clearances, and longitudinal clearances. The cross-sectional shape of rice straw, including the above-mentioned three types of clearances, is similar to that of the samples of the present study. Herein, the propagation constant and characteristic impedance of the circular, concentric, and longitudinal clearances surrounded by three cylindrical surfaces are treated as a transfer matrix. Then, by connecting these transfer matrices in parallel, a transfer matrix integrating these clearances is determined, and the sound absorption coefficient is calculated. Test samples that have three types of clearances are also created, and measure their sound absorption coefficients. The contributions of the concentric and circular clearances are significant because of the dimensions of the used tubes. The results of the calculations that took eccentricity into account revealed no significant impact on the sound absorption coefficient in wide-frequency range. The results of the calculations that took flexure into account revealed that the theoretical value was close to the measured value in the low-frequency range.
Direct simulation of acoustic scattering problems involving fluid-structure interaction using an efficient immersed boundary-lattice Boltzmann method
Authors: Cai Yunan , Lu Jianhua , Li Sheng
Published: October 2018

An efficient immersed boundary-lattice Boltzmann method (IB-LBM) is applied to carry out the direct simulation of acoustic scattering problems involving fluid-structure interaction. In the simulation, the lattice Boltzmann method is adopted for the fluid domain, the immersed boundary method is used to handle the fluid-structure interaction and the instantaneous fluid pressure perturbation is computed to obtain the acoustic field. Compared with the conventional IB-LBMs, a force correction technique is introduced in this method to enforce the non-slip boundary conditions at the immersed boundaries and the acoustic scattering field thus can be obtained more accurately. The study of the numerical result comparison with the conventional IB-LBMs or analytical solutions is conducted on four acoustic problems, such as acoustic radiation from a pulsing cylinder, acoustic scattering from a static cylinder with pulse, or harmonic Gaussian sources and a moving two-dimensional sedimentating particle. The better efficiency of the present method is validated.
Mechanical and acoustic performance prediction model for elastomers in different environmental conditions
Authors: Huang Yunke , Hou Hong , Oterkus Selda , Wei Zhengyu , Zhang Shuai
Published: October 2018

This study focuses on the constitutive model, including temperature and pressure effects, to investigate the dynamic, mechanical, and acoustic properties of elastomers in the frequency domain under different underwater conditions. The developed constitutive relation is based on the Havriliak-Negami (H-N) model by implementing experimental Young's modulus data and using the Williams-Landel-Ferry (WLF) shift function for relaxation time calculation. The H-N model accurately captures the dynamic mechanical modulus for a wide range of frequencies for constant temperature and pressure based on measured dynamic mechanical thermal analysis data. Since the WLF shift function is related with the relaxation time for different temperatures and pressures, the proposed model represents a simple and accurate prediction of the dynamic modulus for varying external conditions. The relationship between Young's modulus and the acoustic properties of the rubber structure can be established by investigating the hydro-wave propagation process. The predictions from the proposed model are verified by comparing with mechanical and acoustic experimental data at different temperatures and pressures. Additionally, the parametric study is conducted to investigate the effect of H-N parameters on mechanical and acoustic properties of elastomer materials. The proposed model can be used to predict the mechanical and acoustic properties in different environmental conditions accurately.
Using Schlieren imaging to estimate the geometry of a shock wave radiated by a trumpet bell
Authors: Rendón Pablo L. , Velasco-Segura Roberto , Echeverría Carlos , Porta David , Pérez-López Antonio , Vázquez-Turner R. Teo , Stern Catalina
Published: October 2018

The Schlieren method has been used before to visualize weak shock waves radiated from the open ends of brass instruments, but no attempt has previously been undertaken, however, to measure the geometry of the radiated wavefronts using the Schlieren images. In this paper Schlieren visualization is used to estimate the geometry of the two-dimensional shock wavefronts radiated from the bell of a trumpet at different frequencies. It is observed that the geometry of the shocks does change with frequency, in the expected manner. The propagation speeds of these shocks are also calculated, and they too exhibit the anticipated behavior.
Reconsidering the nature of voice
Authors: Kreiman Jody E.
Published: October 2018

Voices play essential roles in human experience, and carry many kinds of meaning. At present, the study of voice is consistently tied to the speech chain model, so that voice production, acoustics, and perception are treated as separate, independently studied stages. Such studies provide no insight into how meaning in voice is constructed, and create a situation where voice comprises something different to everyone who studies it. This paper presents empirical and theoretical arguments leading to the conclusion that voice must be viewed as a single integral process, and not as a concatenation of separate stages. We argue that voice production, acoustics, aeroacoustics, biomechanics, perception, and all the rest, are conceptually inseparable, and that none can be understood without knowing how its relationship to the others contributes to its structure and function. We submit that development of such a comprehensive theory of voice should be the primary goal of voice research, whatever the discipline. Such a theory would form a basis on which to build realistic explanations of how voice functions socially and communicatively, how it has evolved, and how it conveys meanings of all sorts, leading to a deeper understanding of what it means to be human and to communicate.
Bayesian inference of tissue properties from glottal area waveforms using a 2D finite element model
Authors: Hadwin Paul J. , Peterson Sean D.
Published: October 2018

Bayesian inference has recently been demonstrated to be effective in estimating stationary and non-stationary reduced-order vocal fold model parameters, along with the associated levels of uncertainty, from simulated glottal area waveform measures (Hadwin et al., 2016, 2017). In these studies, the fitting model was a three mass body-cover model with two degrees of freedom in the cover layer. While demonstrative, restricting the fitting model to two degrees of freedom assumes a priori that this is sufficient to capture salient vocal fold dynamics, thus limiting future clinical applicability. To overcome this, we employ Bayesian inference to directly estimate tissue properties of a two-dimensional (2D) finite element vocal fold model from glottal area waveforms generated by both numerical simulations and recorded videos of synthetic vocal fold oscillations. We demonstrate that the 2D finite element model is not only capable of producing meaningful estimates with reasonable uncertainties, but is also capable of distinguishing between different experimental tissue properties, which is an essential step towards the development of patient specific models.
Advancement of flow velocity measurements in excised canine larynx model
Authors: Oren Liran , Farbos de Luzan Charles , Maddox Alexandra , Gutmark Ephraim , Khosla Sid M.
Published: October 2018

In the classic source-filter model of speech production, flow modulation is the source of sound. Modulation of the flow refers to the fact that the volume flow, Q, is changing as the glottis opens and closes. Furthermore, studies have shown that the maximum flow declination rate (MFDR), which occurs during the latter part of the closing phase, is highly correlated with acoustic intensity (loudness) and acoustic energy in the higher harmonics. Therefore, measurements of the glottal airflow can provide important insights into voice mechanisms, dysfunction and efficiency. In recent years, particle image velocimetry (PIV) have become the method of choice for measuring Q because the technique can quantify, non-intrusively, the spatial and temporal information of the flow. The discussion includes progress of PIV measurements, from 2D to tomographic measurements, in the excised canine larynx model. Key findings related to intraglottal flow and glottal geometry, and their extension to modeling of voice mechanisms, are described.
Adaptive beamforming for uniformly-spaced linear hydrophone array using temporal convolutional neural networks
Authors: Wang Dezhi , Zhang Lilun , Bao Changchun , Xu Kele , Zhu Boqing , Lu Zengquan
Published: October 2018

In oceanic remote sensing, large discrete linear hydrophone arrays are usually utilized to enhance the signal-to-noise ratio (SNR) by means of beamforming that attenuates noise coming from the directions outside the target direction. Although the widely adopted delay-and-sum (DS) and filter-and-sum (FS) beamforming techniques can improve the performance of linear hydrophone arrays in some scenarios, both DS and FS methods have limited adaptability to the changing oceanic environments especially with spatially correlated noise. Moreover, these beamforming techniques aims to optimize the SNR, which is not completely consistent with some objectives such as target recognition. In this work, a neural network adaptive beamforming framework for an uniformly-spaced linear hydrophone array is proposed to make use of the large-scale array signals and address the above issues. In particular, an architecture consists of temporal convolutional neural networks is designed to predict the beamforming filter coefficients in time domain by taking the raw multi-channel waveforms of sound pressure as the input. The filter prediction networks are also jointly trained with a convolutional neural network (CNN) based classification model with the purpose of increasing the target recognition accuracy. The proposed approach is validated by experiments carried out in the south coastal waters of China.
Detection and classification of whales calls using band-limited energy detection and transfer learning
Authors: Cline Danelle E. , Ryan John P.
Published: October 2018

The Monterey Bay Aquarium Research Institute has been recording since July 2015 almost continuously at the Monterey Accelerated Research System (MARS) cabled observatory in Monterey Bay, California, USA. This long-term recording contains thousands of whale calls to help further our understanding of interannual, seasonal, and diel patterns. Here we report on our highly accurate detection and classification method developed to classify blue whale A, B, and D calls and Fin whale 20 Hz pulses. The foundation of the method is a computationally efficient and tuned decimation filter to convert the broadband hydrophone 128 kHz signal to 2 kHz which preserves the low-frequency signal and avoids any high-frequency aliasing. Detection is done using a band-limited-energy-detection filter to find potential calls in the decimated data. Spectrograms are then generated for potential calls and enhanced with local image normalization followed by smoothing by convolving in either time or frequency. Classification is done using the Google Inception v3 model with a transfer learning method. Overall, false positive rates are very low despite variability in whale call shape and background noise.
A Bayesian approach to a passive range estimation method of underwater sound source in shallow water waveguide
Authors: Li Xiaoman , Piao Shenchun
Published: October 2018

In this paper, a matched mode processing method is used to estimate the range of underwater sound source in shallow water, in which the replica field is calculated with the P and Q normal mode model. In this normal mode model, the replica field is described with the bottom phase shift coefficient, the sea depth and the average sound speed profile. The influence caused by the uncertainty of environment parameters, on the accuracy of range estimation is discussed with Bayesian approximation. Bayesian approximation is a good way to estimate the unknown parameters based on probability of data. The Gaussian distribution model and Markov Chain Monte Carlo method are used in this paper for calculating the posterior probability density. The effect of the uncertainty or error of environment parameters to the ranging result is obtained. The practicality of the ranging method is raised significantly. The procedure and the discussed results are given.
One project begets many: The role of one seminal project in the development of many design solutions (Part 2)
Authors: Miller Gregory A. , Pfeiffer Scott D.
Published: October 2018

In the second part of this multi-part paper, the solution for the cap of the organ chamber at Verizon Hall will be presented. The original cap was a lightweight material, allowing significant low frequency energy—critical to the success of any pipe organ—to escape the acoustic volume of the room. The solutions implemented to improve the sound of the organ were limited by structural capacities, and were ultimately developed as lightweight but very stiff honeycomb core panels. The strategy of lightweight-yet-stiff materials has been implemented in numerous other projects to achieve low frequency reflectivity. Examples will be presented illustrating development of this strategy over the past decade.
Noise and vibration measurements of a machine-room-less elevator system
Authors: Williamson Andrew
Published: October 2018

A trend in the design of new condominium buildings is the use of “machine-room less” (MRL) elevator systems. The primary difference between MRL elevator systems and more traditional elevator systems is that, rather than locating the hoist machinery in a rooftop penthouse, the hoist machinery is installed in the elevator shaft. In this location (which is typically closer to residential units), there is greater potential for the operation of the machinery to result in complaints from residents of excessive noise and vibration levels. This paper presents a case study of noise and vibration measurements that were conducted in a condominium building with a MRL elevator system. Measurements were conducted both within the affected residential unit as well as in the elevator shaft. In conducting the measurements, particular attention was paid to determining the effectiveness of the vibration isolation that was provided for the elevator hoist machinery within the elevator shaft.
Jittered echo delay resolution in bats and dolphins
Authors: Finneran James J. , Jones Ryan A. , Mulsow Jason , Houser Dorian S. , Moore Patrick
Published: October 2018

Fine-scale echo delay resolution has been investigated using a “jittered” echo paradigm, where animals discriminate between electronic echoes with fixed delay (i.e., simulating fixed range) and echoes with delays that alternate (jitter) on successive echoes. The data consist of the animals’ discrimination performance (e.g., error rate) as a function of the amount of jitter in the echo delay (the time interval over which the echoes jitter). Results of jitter delay experiments in big brown bats (Eptesicus fuscus) are extraordinary (and controversial) because they suggest that bats can extract information from within the envelope of the crosscorrelation function between an emitted signal and its received echo and therefore may be capable of operating as a coherent receiver. Recently, the jitter delay paradigm has been adapted for use with bottlenose dolphins (Tursiops truncatus) at jitter delays down to 1 μs. Jitter delay acuity results for dolphins show qualitative similarities to those from bats: error function peak widths are below the envelope of the biosonar pulse autocorrelation function and dolphins can perceive a jitter in echo polarity with no change in echo delay. However, further testing with sub-microsecond jitter values are required to determine if dolphins possess “hyperacuity” as reported for bats.
Reconstruction of acoustic scenes in biosonar
Authors: Ming Chen , Roan Michael J. , Müller Rolf , Simmons James A.
Published: October 2018

Biosonar mechanisms are highlighted by comparing acoustically reconstructed scenes derived from generalized methods with the performance of echolocating animals. Bioinspired computations replacing standard methods then offer a path towards understanding the animal’s solutions. Seemingly simple outdoor spaces present flying bats with complex scenes when vegetation and the ground are factored in, and even sound-treated research spaces such as flight rooms evolve into complex scenes as transmitted sounds propagate through the space. Underwater scenes, particularly for shallow water, are much more complicated because longer propagation distances create multipath reverberation that often overlaps with echoes. Interpulse intervals of biosonar emissions must be short to support rapid updating of tracking and perception, but reverberation means that pulse-echo ambiguity occurs. Two reconstructive methods are useful—the HARPEX method for visualizing the progression of echoes and reverberation following a sound, and a HARPEX-like method reconfigured as a forward-looking sonar. Acoustic datasets visualize airborne and underwater sonar scenes by reconstructing sound images for successive time frames following a transmitted sound using a tetrahedral soundfield microphone or a forward-looking sonar head. The complex acoustics of vegetation are examined with a simulation model built to understand the bats’ perception of vegetation. (Work supported by ONR.)
Biosonar capabilities of large-brained dolphins and small-brained bats: Size does matter
Authors: Van Alstyne Kaitlin R. , Branstetter Brian K. , Ridgway Sam H. , Finneran James J. , Xitco Mark J.
Published: October 2018

The large encephalized brain of the bottlenose dolphin, with a small corpus callosum, functions to maintain continuous, 24-hour biosonar signal processing. Bats are not faced with the dolphin’s challenge of maintaining constant vigilance, as bats are able to retreat to roosts for safety from predators. Although both bats and dolphins echolocate, dolphins face greater challenges in the aquatic environment. Dolphins must locate prey of a similar density to that of the environment, which itself has a high speed of sound transmission. Bats can readily distinguish between prey from the surrounding air because of a strong impedance mismatch, and the speed of sound is much slower. Perhaps stemming from these challenges, dolphins have developed a highly sophisticated echolocation system in which they are able to emit signals and receive echoes, decide, and respond accordingly at a remarkably rapid speed. Dolphin brains may also be specially equipped for early auditory development in utero. The dolphin body has a close impedance match to water, exposing the fetus to environmental sounds. Furthermore, auditory fibers develop myelin early during gestation. Thus, although dolphins and bats both echolocate, the dolphin’s experience during life in the ocean promoted the development of a large and specialized brain.
Dolphins’ echolocation based on reverberations through skull?
Authors: Boschi Lapo , Reinwald Michael , Grimal Quentin , Marchal Jacques , Catheline Stefan
Published: October 2018

The sensitivity of odontocetes to changes in sound source azimuth and, in particular, elevation (minimum audible angles) has been reported to be superior to those of humans and bats. It has been suggested that binaural/spectral cues might be insufficient to account for this skill. We investigate bone-conducted sound in a short-beaked common dolphin’s mandible and attempt to determine whether and to what extent it could contribute to the task of localizing a sound source. Experiments are conducted in a water tank by deploying, on the horizontal and median planes of the skull, sound sources that emit synthetic clicks between 45 and 55 kHz. Elastic waves propagating through the mandible are measured at the pan bones and used to localize source positions via binaural cues, as well as a correlation-based full-waveform algorithm. We find that by making use of the full waveforms, and, most importantly, of their reverberated coda, the accuracy of source localization in the vertical plane can be enhanced. While further experimental work is needed to substantiate this speculation, our results suggest that the auditory system of dolphins might be able to localize sound sources by analyzing the coda of biosonar echoes.
Ultra high definition 3D tracking of biosonar of Amazon River dolphins and others mammals into the wild
Authors: Blakefield Gerald , Trone Marie , Barchasz Valentin , Gies Valentin , Bonnett Dave , Glotin Herve
Published: October 2018

We designed and built a high capacity digital analog converter : JASON Qualilife DAQ [1] which is capable of sampling at 1 MHz on 5 channels simultaneously to assess cetacean biosonar and the source position and orientation relative to the array using time delay of arrivals of the biosonar acoustical signals. We used JASON with underwater portable arrays housing between 3 and 7 hydrophones (for more than 4 hydrophones we connected two cards sharing one common hydrophone). This has been used to monitor Physeter m. biosonar in near field, and Inia. g. in the Peruvian Amazon from 2014 to 2018. Results demonstrate the efficiency of this advanced low cost scientific instrumentation : it allows with only 4 hydrophones to track in 3D the precise movements of the I. g. dolphin, and to determine key behavioral features, like the velocity of its rostrum rotation, while following its highly defined biosonar emissions. This is the first, at our knowledge, that wild amazon dolphin biosonar is described inside its ecosystem. Perspectives on automatic low power trigger [2] for counting of the dolphins and extraction of individual acoustic invariant are given, as well as research avenues on biosonar of other species. [1] Gies et al, JASON Qualilife Daq, in DCLDE2018, smiot.univ-tln.fr,sabiod.org/bib [2] Fourniol et al., Low-Power Frequency Trigger for Environmental Internet of Things, in IEEE/ASME Mechatronic & Embedded Systems http://sabiod.org/bib, 2018 Samples and supp. material: http://sabiod.org/JASON.
Orcasound app: An open-source solution for streaming live ocean sound to citizen scientists and cloud-based algorithms
Authors: Veirs Scott , Veirs Val , Cretu Paul , Hicks Steve , Mzali Skander
Published: October 2018

A growing number of hydrophones stream ocean sound data in near-real-time to automated detectors. Many of these streams are also provided to the public, but none yet appeal for citizen scientists to provide real-time detection or classification services. Within the Orcasound hydrophone network—orcasound.net (WA, USA)—live human listeners have always been in friendly competition with real-time automated detectors. To facilitate the participation of citizen scientists in studies of signals from southern resident killer whales and other soniferous organisms of the Salish Sea, in 2017–2018, we developed a low-cost combination of hardware and open-source software to stream audio data from our hydrophones to the headphones of our listeners. The data are archived at and stream from AWS/S3 in real-time (<60 seconds latency) to a browser-based player that is platform- and device-independent. This sets the stage for human detection of signals—mainly the calls, whistles, or clicks of fish-eating orcas—but also novel signals for which we do not yet have classifiers. We will demonstrate the Orcasound app and explain how it interacts synergistically with automated detectors and classifiers, as well as crowdsourced citizen science projects.
Update on clinical trials results of kidney stone repositioning and preclinical results of stone breaking with one ultrasound system
Authors: Bailey Michael R. , Wang Yak-Nam , Kreider Wayne , Cunitz Bryan W. , Dai Jessica , Harper Jonathan , Chang Helena , Sorensen Matthew D. , Liu Ziyue , Levy Oren , Dunmire Barbrina , Maxwell Adam D.
Published: October 2018

Our goal is an office-based, handheld ultrasound system to target, detach, break, and/or expel stones and stone fragments from the urinary space to facilitate natural clearance. Repositioning of stones in humans (maximum 2.5 MPa, and 3-second bursts) and breaking of stones in a porcine model (maximum 50 cycles, 20 Hz repetition, 30 minutes, and 7 MPa peak negative pressure) have been demonstrated using the same 350-kHz probe. Repositioning in humans was conducted during surgery with a ureteroscope in the kidney to film stone movement. Independent video review confirmed stone movements (≥ 3 mm) in 14 of 15 kidneys (93%). No serious or unanticipated adverse events were reported. Experiments of burst wave lithotripsy (BWL) effectiveness on breaking human stones implanted in the porcine bladder and kidney demonstrated fragmentation of 4 of 4 stones on post mortem dissection. All clinical pathology, hematology, and urinalysis for a 1-week survival study with the BWL exposures in 10 specific pathogen free pigs were within normal limits. These results demonstrate that repositioning of stones with ultrasonic propulsion and breaking of stones with BWL are safe and effective. [Work supported by NIH P01 DK043881, K01 DK104854, and R44 DK109779.]
Acoustic radiation force acting on a spherical scatterer in water: Measurements and simulation
Authors: Karzova Maria M. , Nikolaeva Anastasiya V. , Tsysar Sergey , Khokhlova Vera , Sapozhnikov Oleg
Published: October 2018

Acoustic radiation force (ARF) is successfully used in a recently proposed ultrasonic technology for kidney stone propulsion. The planning of the treatment requires calibration of ARF for stones of different dimensions and locations. However, such calibration remains a problem. Here, a method of measuring ARF acting on a mm-sized spherical object positioned on the axis of a focused ultrasound beam is proposed and tested. Acoustic field was generated by a single-element 1.072 MHz transducer of 100 mm aperture and 70 mm focal length positioned at the bottom of the water tank. Measurements were performed for nylon and glass spherical scatterers with diameters from 2 to 4 mm located at different distances from the source along the vertical beam axis. For each scatterer, the source power was gradually decreased until the scatterer started to fall down from the trap. At this threshold power of the source, the value of ARF was determined as a difference between the gravity and buoyancy forces acting on the scatterer. At other source power outputs, the value of ARF was linearly scaled. ARF was also calculated from pressure distributions reconstructed from acoustic hologram of the source and physical parameters of the scatterers. Experimental and theoretical results were found in a good agreement. It was shown that the most effective pushing was observed at distances where the beam was slightly wider than the scatterer. [Work supported by the stipend of the President of Russia (SP-2621.2016.4), RFBR №18-32-00659, and NIH P01 DK43881.]
Generation of guided waves during burst wave lithotripsy as a mechanism of stone fracture
Authors: Maxwell Adam D. , MacConaghy Brian , Bailey Michael R. , Sapozhnikov Oleg
Published: October 2018

Burst wave lithotripsy (BWL) is an experimental method to noninvasively fragment urinary stones by short pulses of focused ultrasound. We are investigating physical mechanisms of stone fracture during BWL to better optimize this procedure. In this study, we used photoelasticity imaging as a method to visualize elastic wave dynamics in model stones. Epoxy and glass stone models were made into cylindrical, rectangular, or irregular geometries and exposed in a degassed water bath to focused ultrasound bursts at different frequencies. A high-speed camera was used to record images of the stone during exposure through a circular polariscope backlit by a monochromic flash source. Results showed development of periodic stresses in the stone body with a pattern dependent on frequency. These were identified as guided wave modes in cylinders and plates, which formed standing waves upon reflection from the distal surfaces of the stone model, causing periodic stress positions. Measured phase velocities compared favorably to specific numerically calculated modes dependent on frequency and material. Artificial stones exposed to BWL produced cracks at positions anticipated by this mechanism. These results support guided wave production and reflection as a mechanism of stone fracture in BWL. [Work supported by K01 DK104854 and P01 DK043881.]
Experimental observations and numerical modeling of lipid-shell microbubbles with stone targeting moieties for minimally-invasive treatment of urinary stones
Authors: Pishchalnikov Yuri A. , Behnke-Parks William , Maeda Kazuki , Colonius Tim , Mellema Matt , Hopcroft Matt , Luong Alice , Wiener Scott , Stoller Marshall , Kenny Thomas , Laser Daniel
Published: October 2018

Products incorporating stone-targeting microbubbles have recently entered human clinical trials as a new minimally-invasive approach to treat urinary stones. Lipid-shell, gas-core microbubbles can be introduced into the urinary tract through a catheter. Calcium-binding moieties incorporated into the lipid shell can facilitate binding to stones. The microbubbles can be excited by an extracorporeal source of low-intensity ultrasound. Alternatively, the microbubbles can be excited by an intraluminal source, such as a fiber-optic laser. With either excitation technique, stone-targeting microbubbles can significantly increase rates of erosion, pitting, and fragmentation of stones, as has recently been reported for in-vitro experiments with synthetic stones [Wiener et al., J. Urology, v.199, no.4S, e322 (2018)]. We report here on new experiments using high-speed photography to characterize microbubbles expansion of cracks within a stone and resultant breaking-off of stone fragments. Numerical modeling shows that the direction of microjets produced by collapsing stone-bound microbubbles depends strongly on bubble shape and stand-off distance. For a wide range of stand-off distances and bubble shapes, microbubble collapse is associated with pressure increases of some two orders of magnitude compared to the excitation source pressures. This in-vitro study provides key insights into the use of stone-targeting microbubbles in treatment of urinary stones.
Finite element modelling of scattering of an acoustic wave by particles in a fluid: Shear and thermal effects
Authors: Pinfield Valerie J. , Forrester Derek M. , Huang Jinrui
Published: October 2018

We investigate, using finite element modelling, the effects of viscous and thermal dissipation in the region around a particle in a liquid subjected to an acoustic field. The linearized thermo-acoustic equations for propagation in a viscous liquid are used in the model. In the Rayleigh scattering regime, with Mega-Hertz frequencies and nano- or micron-sized particles, the shear and thermal decay lengths are of order micrometres and are therefore challenging to resolve accurately using finite element models. We report investigations of the effect of particle size and frequency on the magnitude of the thermal and shear wave fields and their decay length and compare with analytical predictions. We present a determination of the viscous and thermal power dissipation around a single particle, and for small clusters of particles. Here we identify the effect of interaction of the shear and thermal fields with neighbouring particles through mode reconversion, leading to a reduction in dissipation losses when interparticle separation is of the order of the thermal or shear decay length.
Quantitative assessment of angiogenic microvasculature using Ultrasound multiple scattering with microbubble contrast agents
Authors: Mohanty Kaustav , Papadopoulou Virginie , Newsome Isabel , Dayton Paul A. , Muller Marie M.
Published: October 2018

In tumors, angiogenesis (formation of new blood vessels) is established as a biomarker of malignancy. A random, isotropic, high-density vessel network is linked to tumor invasiveness. Ultrasound quantification of angiogenic micro-architecture could help increase the specificity of ultrasound for cancer diagnosis. We exploit multiple scattering by microbubbles populating angiogenic networks to characterize an effective medium diffusivity via the diffusion constant (D). The inter-element response matrix is acquired using an L11-4v linear array transducer operating at 7.8 MHz. D is computed from the time evolution of the incoherent contribution to the backscattered intensity in the near field. D is measured in fibrosarcoma tumors subcutaneously implanted in rats (n = 16), and in control, healthy tissue (n = 18). D is measured for two different orientations (Coronal and Transverse) and the anisotropy of the microvasculature is evaluated via the ratio of the D values obtained in the two different orientations. D was found significantly different between control (1.38 ± 0.51 mm2/μs) and tumor (0.65 ± 0.27 mm2/μs) (p<0.01) and anisotropy of the angiogenic network was observed in control cases (1.62 ± 0.911). For further validation, these results were corroborated with vascular density measurements from acoustic angiography data, confirming increased vessel density in tumors compared to controls.
Interaction of guided waves with defects in a multilayered cylinder by an asymptotic approach
Authors: Krishna Aditya , Ducasse Eric , Deschamps Marc
Published: October 2018

This work deals with the problem of the propagation of an elastodynamic field radiated by a source in a cylindrical layered medium which interacts with and is diffracted by a defect. At low frequencies, where the defect size is much smaller than the wavelength, this interaction can be approximated by a point source, located at the defect position. This secondary source is expressed by the Green function and its derivative. The Green function, which describes the response of an undamaged cylinder, is calculated using the canonical form of the wave equation initially expressed as a function of the spatial and temporal variables. Performing the Laplace in time and Fourier transforms along the cylinder axis, this equation is written as an ordinary differential equation with respect to the radial position. The solution for the transversely isotropic case is obtained by adopting the partial wave formulation, expressed as a combination of the modified Bessel's functions of the first and second kind. Having assembled the layers, numerical inverse transforms are performed to obtain the real wave fields. This technique allows for reduced computational costs and faster calculation times and could be used for the non destructive testing of embedded pipes and tubes.
Harmonic generation and frequency mixing at nonlinear imperfect interfaces
Authors: Biwa Shiro
Published: October 2018

Imperfect interfaces can be found in a variety of natural and artificial systems. Some examples of such interfaces that are objects of ultrasonic evaluation and diagnostics include contacting mechanical components as well as closed defects in structural components. A remarkable feature of these interfaces is that they exhibit highly nonlinear responses to ultrasonic waves. Harmonic generation (generation of, e.g., double frequency signals at the incidence of a wave with a certain frequency) and frequency mixing (generation of sum/difference frequency signals at the incidence of waves of two different frequencies) are typical phenomena at these interfaces. In this presentation, a theoretical analysis of these phenomena is presented based on modeling the interface as a nonlinear spring-type interface between two similar linearly elastic media. Unlike the corresponding nonlinear acoustic effects due to material nonlinearity, the interfacial nonlinear effects considered here do not require the spatial accumulation of nonlinearly generated harmonic or sum/difference frequency components. The propagation directions and amplitudes of these nonlinearly generated components are derived for plane mono- or dichromatic incident waves. Some relevant experimental results for a contacting interface of metallic blocks subjected to different applied pressures are also presented.
Experimental behaviour of an acoustic wave in a medium comprising self-similar (fractal) objects
Authors: Mandelbrot Elsy , Sapoval Bernard , Gibiat Vincent
Published: October 2018

After the pioneering work of one of the authors (Sapoval et al. J. Acoust. Soc. Am. 104, 1997), the study of acoustic propagation over fractal boundaries came up against the difficulty of experimenting with self-similar objects immersed in two- and three-dimensional space. The idea of one of us to use the capabilities offered by three-dimensional printing has made it possible to overcome this difficulty and produce numerous objects, as small or large as desired, in large numbers. We will present the experimental results obtained for acoustic propagation, reflection coefficient, attenuation and trapping in the case of an half fractal octahedron, isolated as well as in the case of a flat paving consisting of an important number of these objects.
Further testing on the efficacy of inertia base weight training stations for CrossFit weight drops
Authors: Waters Angela , Smith Scott W.
Published: October 2018

In an attempt to mitigate the adverse impact and vibration effects of CrossFit weight drops in a wood frame house in South Carolina, a concrete inertia base system was designed, constructed, and installed in 2013. The homeowners have been pleased with the system’s performance, reporting major reductions in the felt vibration throughout the house. In 2017 initial testing was conducted that showed significant reduction in vibration in an adjacent corridor. This presentation reports on the results of subsequent and more detailed testing at remote locations in the house. New equipment became available which allowed the vibration levels on the inertia base and at the remote locations to be recorded simultaneously.
Long-term monitoring of fitness activity in a commercial gym
Authors: Rawlings Samantha , Dong David W. , LoVerde John
Published: October 2018

Noise and vibration from activity in fitness facilities is a common source of complaints in residential, commercial, and mixed use buildings. Most studies have focused on developing and measuring mitigation of the vibration from the activity. However, there is limited information on the characteristics of fitness activity and its effect on acceptability. It is assumed that the complaints will increase with the frequency of occurrence of the events, but there is little information on the temporal distribution of typical fitness activity. There is therefore a need for long term measurements of a large number of fitness facilities, comparable to noise data that have been collected around sources such as roadways and airports. Here, we begin to address this need and report results of long-term vibration monitoring of a commercial fitness facility.
Investigation of vibration reduction methods from fitness activity
Authors: Dong David W. , LoVerde John , Silva Richard , Rawlings Samantha
Published: October 2018

Noise and vibration from activity in fitness facilities, in particular drops of heavy weights, is a common source of disturbance and complaint in residential, commercial, and mixed-use building types. There is no standardized method for evaluating the reduction in noise or vibration provided by these products and systems. The authors previously reported (Internoise 2015, Noise-Con 2016, ASA Boston 2017) a preliminary test method to evaluate athletic tile flooring with heavy weight drops, based on the reduction in floor vibration (ΔLV) achieved due to the insertion of the products. Preliminary results indicated that the ΔLV measurement adequately described the impact reduction due to athletic tile, over a certain frequency range, reasonably independent of structure. This paper continues the research with measurements with additional materials and sources, and preliminary analytical investigations of the effects of mitigation methods.
Further prediction of heavy weight drops on resilient sports floors in existing buildings
Authors: Golden Matthew V. , Gartenburg Paul
Published: October 2018

Currently, the assessment of noise and vibration due to heavy weight drops in an existing building can be cumbersome and time consuming, have low repeatability, and does not allow for evaluation of additional solutions not present at the time of testing. This paper will present further development of a method to solve those problems and is broken up into three parts. The first part is the laboratory assessment of the force pulse that a given weight will exert onto a resilient floor. The second part is a method to quickly obtain the in-situ transfer function between the force injected into the building and the resulting vibration elsewhere in the building. The third part combines the previous two items to predict the acceleration in a building due to any arbitrary combination of impact source and resilient floor. The results obtained will be compared to on-site weight drop measurements in order to qualify the predictive model. Extensions of the model into other structures, types of outputs (vibration vs sound pressure levels), and octave band vs narrow band results will be discussed.
Short-term annoyance due to construction work noise in a laboratory context
Authors: Lee Jae Kwan , Chang Seo I. , Jang Jae Woong , Lee Soo Il
Published: October 2018

Among the various noises that cause environmental disputes, the noise of the construction site is particularly problematic. Psycho-acoustic experiment was used to develop an "annoyance model" due to construction site noise. In the experiment, four noises recorded at the construction site were used. There are two continuous noises and two impact noises. Some people were recruited for experiment and the classification was performed primarily. The subjects were classified into various criteria such as gender, age, sensitivity, disease, and the results were compared. The noise converted to 35–80dB (A) was randomly played. During the experiment, the annoyance was judged by the 11 point scale for every noise. The physical analysis of the sound used in the experiment was performed for the development of the annoyance model besides the auditory experiment. Annoyance model was developed by multiple regression analysis using Leq, Lmax, sound quality indices (loudness, sharpness, roughness, and tonality), and questionnaire score. Also, it was confirmed whether there was any difference in the annoyance model for each subject group.
Characterization, analysis, and noise control measures of a mechanical room
Authors: Jha Deepak Deokant , Lee Joonhee , Zaheeruddin Mohammed
Published: October 2018

The acoustic environment of a mechanical room in buildings has received little attention because the space is occasionally occupied by building maintenance staff. However, the room typically includes the loudest noise sources in buildings. It is necessary to investigate noise exposure in the mechanical room for the staff. The aim of this study is, thus, to assess noise levels in the room by examining acoustic characteristics of the noise sources and mapping noise levels produced by the sources. This study also aims to provide optimal solutions to decrease the noise levels being produced. The framework consists of (1) identifying the major locations at which noise is being produced; (2) measurement of noise levels; and (3) performing noise level analysis of each activity. These findings will provide useful information to establish effective noise management plans for mechanical rooms in buildings.