bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiscale model of cavitation bubble formation and breakdown
Authors: Nault Isaac , Mitran Sorin M. , Sankin Georgy , Zhong Pei
Published: October 2014

Cavitation damage is responsible for initial pitting of kidney stone surfaces, damage that is thought to play an important role in shock wave lithotripsy. We introduce a multiscale model of the formation of cavitation bubbles in water, and subsequent breakdown. At a macroscopic, continuum scale cavitation is modeled by the 3D Euler equations with a Tait equation of state. Adaptive mesh refinement is used to provide increased resolution at the liquid/vapor boundary. Cells with both liquid and vapor phases are flagged by the continuum solver for mesoscale, kinetic modeling by a lattice Boltzmann description capable of capturing non-equilibrium behavior (e.g., phase change, energetic jet impingement). Isolated and interacting two-bubble configurations are studied. Computational simulation results are compared with high-speed experimental imaging of individual bubble dynamics and bubble–bubble interaction. The model is used to build a statistical description of multiple-bubble interaction, with input from cavitation cloud imaging. [Work supported by NIH through 5R37DK052985-18.]
Evaluating kidney stone size in children using the posterior acoustic shadow
Authors: Lee Franklin C. , Harper Jonathan D. , Lendvay Thomas S. , Liu Ziyue , Dunmire Barbrina , Dighe Manjiri , Bailey Michael R. , Sorensen Mathew D.
Published: October 2014

Ultrasound, not x-ray, is preferred for imaging kidney stones in children; however, stone size determination is less accurate with ultrasound. In vitro we found stone sizing was improved by measuring the width of the acoustic shadow behind the stone. We sought to determine the prevalence and accuracy of the acoustic shadow in pediatric patients. A retrospective analysis was performed of all initial stone events at a children’s hospital over the last 10 years. Included subjects had a computed tomography (CT) scan and renal ultrasound within 3 months of each other. The width of the stone and acoustic shadow were measured on ultrasound and compared to the stone size as determined by CT. Thirty-seven patients with 49 kidney stones were included. An acoustic shadow was seen in 85% of stones evaluated. Stone width resulted in an average overestimation of 1.2 ± 2.2 mm while shadow width resulted in an underestimation of 0.5 ± 1.7 mm (p < 0.001). A posterior acoustic shadow was seen in the majority of stones and was a more accurate measure of stone size. This would provide valuable information for stone management. [Work supported by NIH DK43881 and DK092197, and NSBRI through NASA NCC 9-58.]
Development and testing of an image-guided prototype system for the comminution of kidney stones using burst wave lithotripsy
Authors: Cunitz Bryan , Maxwell Adam , Kreider Wayne , Sapozhnikov Oleg , Lee Franklin , Harper Jonathan , Sorenson Matthew , Bailey Michael
Published: October 2014

Burst wave lithotripsy is a novel technology that uses focused, sinusoidal bursts of ultrasound to fragment kidney stones. Prior research laid the groundwork to design an extracorporeal, image-guided probe for in-vivo testing and potentially human clinical testing. Toward this end, a 12-element 330 kHz array transducer was designed and built. The probe frequency, geometry, and shape were designed to break stones up to 1 cm in diameter into fragments <2mm. A custom amplifier capable of generating output bursts up to 3 kV was built to drive the array. To facilitate image guidance, the transducer array was designed with a central hole to accommodate co-axial attachment of an HDI P4-2 probe. Custom B-mode and Doppler imaging sequences were developed and synchronized on a Verasonics ultrasound engine to enable real-time stone targeting and cavitation detection, Preliminary data suggest that natural stones will exhibit Doppler “twinkling” artifact in the BWL focus and that the Doppler power increases as the stone begins to fragment. This feedback allows accurate stone targeting while both types of imaging sequences can also detect cavitation in bulk tissue that may lead to injury. [Work supported by NIH grants DK043881, EB007643, EB016118, T32 DK007779, and NSBRI through NASA NCC 9-58.]
Removal of residual bubble nuclei to enhance histotripsy kidney stone erosion at high rate
Authors: Duryea Alexander P. , Roberts William W. , Cain Charles A. , Hall Timothy L.
Published: October 2014

Previous work has shown that histotripsy can effectively erode model kidney stones to tiny, sub-millimeter debris via a cavitational bubble cloud localized on the stone surface. Similar to shock wave lithotripsy, histotripsy stone treatment displays a rate-dependent efficacy, with pulses applied at low repetition frequency producing more efficient erosion compared to those applied at high repetition frequency. This is attributed to microscopic residual cavitation bubble nuclei that can persist for hundreds of milliseconds following bubble cloud collapse. To mitigate this effect, we have developed low amplitude (MI<1) acoustic pulses to actively remove residual nuclei from the field. These bubble removal pulses utilize the Bjerknes forces to stimulate the aggregation and subsequent coalescence of remnant nuclei, consolidating the population from a very large number to a countably small number of remnant bubbles within several milliseconds. Incorporation of this bubble removal scheme in histotripsy model stone treatments performed at high rate (100 pulses/second) produced drastic improvement in treatment efficiency, with an average erosion rate increase of 12-fold in comparison to treatment without bubble removal. High speed imaging indicates that the influence of remnant nuclei on the location of bubble cloud collapse is the dominant contributor to this disparity in treatment efficacy.
Response shaping and scale transition in dynamic systems with arrays of attachments
Authors: Vignola Joseph F. , Glean Aldo A. , Sterling John , Judge John A.
Published: October 2014

Arrays of elastic attachments can be design to act as energy sinks in dynamic systems. This presentation describes design strategies for drawing off mechanical energy to achieve specific objectives such as mode suppression and response tailoring in both extended and discrete systems. The design parameters are established using numerical simulations for both propagating and standing compressional waves in a one-dimensional system. The attachments were chosen to be cantilevers so that higher modes would have limited interaction with the higher modes of the primary structure. The two cases considered here are concentrated groups of cantilevers and spatial distributions of similar cantilevers. Relationships between the number and placement of the attachments and their masses and frequency distributions are of particular interest, along with the energy density distribution between the primary structure and the attachments. The simulations are also used to show how fabrication error degrades performance and how energy scale transition can be managed to maintain linear behavior.
Accelerated general method for computing noise effects in arrays
Authors: Reed Heather , Cipolla Jeffrey , Bailakanavar Mahesh , Murray Patrick
Published: October 2014

Noise in an acoustic array can be defined as any unwanted signal, and understanding how noise interacts with a structural system is paramount for optimal design. For example, in an underwater vehicle we may want to understand how structural vibrations radiate through a surrounding fluid; or an engineer may want to evaluate the level of sound inside a car resulting from the turbulent boundary layer (TBL) induced by a moving vehicle. This talk will discuss a means of modeling noise at a point of interest (e.g., at a sensor location) stemming from a known source by utilizing a power transfer function between the source and the point of interest, a generalization of the work presented in [1]. The power transfer function can be readily computed from the acoustic response to an incident wave field, requiring virtually no additional computation. The acoustic solution may be determined via analytic frequency domain approaches or through a finite element analysis, enabling the noise solution to be a fast post processing exercise. This method is demonstrated by modeling the effects of a TBL pressure and noise induced by structural vibrations on a sensor array embedded in an elastic, multi-layer solid. Additionally, uncertainties in the noise model can be easily quantified through Monte Carlo techniques due to the fast evaluation of the noise spectrum. Ko, S.H. and Schloemer, H.H. “Flow noise reduction techniques for a planar array of hydrophones,” J. Acoust. Soc. Am. 92, 3409 (1992).
Testing facility concepts for the material characterization of porous media consisting of relatively limp foam and stiff fluid
Authors: Woodworth Michael , Cipolla Jeffrey
Published: October 2014

Fluid filled foams are important components of acoustical systems. Most are made up of a stiff skeleton medium relative to the fluid considered, usually air. Biot’s theory of poroelasticity is appropriate for characterizing and modeling these foams. The use of relatively stiff fluid (such as water) and limp foam media pose a greater challenge. Recently modifications to Biot's theory have generated the mechanical relationships required to model these systems. Necessary static material properties for the model can be obtain through in vacuo measurement. Frequency dependent properties are more difficult to obtain. Traditional impedance tube methods suffer from fluid structure interaction when the bulk modulus of the fluid media approaches that of the waveguide. The current investigation derives the theory for, and investigates the feasibility of, several rigid impedance tube alternatives for characterizing limp foams in stiff fluid media. Alternatives considered include a sufficiently rigid impedance tube, a pressure relief impedance tube and, the most promising, a piston excited oscillating chamber of small aspect ratio. The chamber concept can recover the descriptive properties of a porous medium described by Biot’s theory or by complex-impedance equivalent-fluid models. The advantages of this facility are small facility size, low cost, and small sample size.
Adomian decomposition identifies an approximate analytical solution for a set of coupled strings
Authors: Segala David
Published: October 2014

The use of Adomian decomposition method (ADM) has been successfully applied in various applications across the applied mechanics and mathematics community. Originally, Adomian developed this method to derive analytical approximate solutions to nonlinear functional equations. It was shown that the solution to the given nonlinear functional equation can be approximated by an infinite series solution of the linear and nonlinear terms, provided the nonlinear terms are represented by a sum of series of Adomian polynomials. Here, ADM is used to derive an approximate analytical solution to a set of partial differential equations (PDEs) describing the motion of two coupled strings that lie orthogonal to each other. The PDEs are derived using Euler-Lagrange equations of motion. The ends of the strings are pinned and the strings are coupled with a nonlinear spring. A finite element model of the system is developed to provide a comparative baseline. Both the finite element model and analytical solution were driven by an initial displacement condition. The results from both the FEA and analytical solution were compared at six different equally spaced time points over the course of a 1.2 second simulation.
A longitudinal shear wave and transverse compressional wave in solids
Authors: Zorgani ali , Catheline Stefan , Benech Nicolas
Published: October 2014

What general definition can one give to elastic P- and S-wave, especially when they are transversely and longitudinally polarized respectively? This question is the main motivation of the analysis of the Green’s function reported in this letter. By separating the Green’s function in a divergence free and a rotational free terms, not only a longitudinal S-wave but also a transversal P-wave are described. These waves are shown to be parts of the solution of the wave equation known as coupling terms. Similarly to surface water wave, they are divergence and rotational free. Their special motion is carefully described and illustrated.
The Graduate Program in Acoustics at The Pennsylvania State University
Authors: Sparrow Victor , Russell Daniel A.
Published: October 2014

In 2015, the Graduate Program in Acoustics at Penn State will be celebrating 50 years as the only program in the United States offering the Ph.D. in Acoustics as well as M.S. and M.Eng. degrees in Acoustics. An interdisciplinary program with faculty from a variety of academic disciplines, the Acoustics Program is administratively aligned with the College of Engineering and closely affiliated with the Applied Research Laboratory. The research areas include: ocean acoustics, structural acoustics, signal processing, aeroacoustics, thermoacoustics, architectural acoustics, transducers, computational acoustics, nonlinear acoustics, marine bioacoustics, noise and vibration control, and psychoacoustics. The course offerings include fundamentals of acoustics and vibration, electroacoustic transducers, signal processing, acoustics in fluid media, sound-structure interaction, digital signal processing, experimental techniques, acoustic measurements and data analysis, ocean acoustics, architectural acoustics, noise control engineering, nonlinear acoustics, ultrasonic NDE, outdoor sound propagation, computational acoustics, flow induced noise, spatial sound and 3D audio, marine bioacoustics, and the acoustics of musical instruments. Penn State Acoustics graduates serve widely throughout military and government labs, academic institutions, consulting firms, and industry. This poster will summarize faculty, research areas, facilities, student demographics, successful graduates, and recent enrollment and employment trends.
Graduate studies in acoustics and noise control in the School of Mechanical Engineering at Purdue University
Authors: Davies Patricia , Bolton J. Stuart , Li Kai Ming
Published: October 2014

The acoustics community at Purdue University will be described with special emphasis on the graduate program in Mechanical Engineering (ME). Purdue is home to around 30 faculty who study various aspects of acoustics and related disciplines, and so, there are many classes to choose from as graduate students structure their plans of study to complement their research activities and to broaden their understanding of the various aspects of acoustics. In Mechanical Engineering, the primary emphasis is on understanding noise generation, noise propagation, and the impact of noise on people, as well as development of noise control strategies, experimental techniques, and noise and noise impact prediction tools. The ME acoustics research is conducted at the Ray W. Herrick Laboratories, which houses several large acoustics chambers that are designed to facilitate testing of a wide array mechanical systems, reflecting the Laboratories’ long history of industry-relevant research. Complementing the acoustics research, Purdue has vibrations, dynamics, and electromechanical systems research programs and is home to a collaborative group of engineering and psychology professors who study human perception and its integration into engineering design. There are also very strong ties between ME acoustics faculty and faculty in Biomedical Engineering and Speech Language and Hearing Sciences.
Acoustics program at the University of Rhode Island
Authors: Potty Gopu R. , Miller James H. , Wallin Brenton , White Charles E. , Giard Jennifer
Published: October 2014

The undergraduate and graduate program in Ocean Engineering at the University of Rhode Island is one of the oldest such programs in the United States. This program offers Bachelors, Masters (thesis and non-thesis options), and Ph.D. degrees in Ocean Engineering. The Ocean Engineering program has a strong acoustic component both at the undergraduate and graduate level. At the graduate level, students can specialize in several areas including geoacoustic inversion, propagation modeling, marine mammal acoustics, ocean acoustic instrumentation, transducers, etc. Current acoustics related research activities of various groups will be presented. Information regarding the requirements of entry into the program will be provided. Many graduates from the program hold faculty positions at a number of universities in the United States and abroad. In addition, graduates from the ocean acoustics program at URI are key staff at many companies and organizations. The opportunities and challenges facing the program will be summarized.
Graduate training opportunities in the hearing sciences at the University of Louisville
Authors: Zahorik Pavel , Preminger Jill E. , Stilp Christian E.
Published: October 2014

The University of Louisville currently offers two branches of training opportunities for students interested in pursuing graduate training in the hearing sciences: A Ph.D. degree in experimental psychology with concentration in hearing science, and a clinical doctorate in audiology (Au.D.). The Ph.D. degree program offers mentored research training in areas such as psychoacoustics, speech perception, spatial hearing, and multisensory perception, and guarantees students four years of funding (tuition plus stipend). The Au.D. program is a 4-year program designed to provide students with the academic and clinical background necessary to enter audiologic practice. Both programs are affiliated with the Heuser Hearing Institute, which, along with the University of Louisville, provides laboratory facilities and clinical populations for both research and training. An accelerated Au.D./Ph.D. training program that integrates key components of both programs for training of students interested in clinically based research is under development. Additional information is available at http://louisville.edu/medicine/degrees/audiology and http://louisville.edu/psychology/graduate/vision-hearing.
Acoustics-related research in the Department of Speech and Hearing Sciences at Indiana University
Authors: Bent Tessa , Lulich Steven , Withnell Robert , Shofner William
Published: October 2014

In the Department of Speech and Hearing Sciences at Indiana University, there are many highly active laboratories that conduct research on a wide range of areas in acoustics. Four of these laboratories are described below. The Biophysics Lab (PI: Robert Withnell) focuses on the mechanics of hearing. Acoustically based signal processing and data acquisition provide experimental data for model-based analysis of peripheral sound processing. The Comparative Perception Lab (PI: William Shofner) focuses on how the physical features of complex sounds are related to their perceptual attributes, particularly pitch and speech. Understanding behavior and perception in animals, particularly in chinchillas, is an essential component of the research. The Speech Production Laboratory (PI: Steven Lulich) conducts research on imaging of the tongue and oral cavity, speech breathing, and acoustic modeling of the whole vocal/respiratory tract. Laboratory equipment includes 3D/4D ultrasound, digitized palate impressions, whole-body and inductive plethysmography, electroglottography, oral and nasal pressure and flow recordings, and accelerometers. The Speech Perception Lab (PI: Tessa Bent) focuses on the perceptual consequences of phonetic variability in speech, particularly foreign-accented speech. The main topics under investigation are perceptual adaptation, individual differences in word recognition, and developmental speech perception.
Graduate studies in acoustics at the University of Notre Dame
Authors: Jasinski Christopher , Corke Thomas C.
Published: October 2014

The University of Notre Dame department of Aerospace and Mechanical Engineering is conducting cutting edge research in aeroacoustics, structural vibration, and wind turbine noise. Expanding facilities are housed at two buildings of the Hessert Laboratory for Aerospace Engineering and include two 25 kW wind turbines, a Mach 0.6 wind tunnel, and an anechoic wind tunnel. Several faculty members conduct research related to acoustics and multiple graduate level courses are offered in general acoustics and aeroacoustics. This poster presentation will give an overview of the current research activities, laboratory facilities, and graduate students and faculty involved at Notre Dame’s Hessert Laboratory for Aerospace Engineering.
Graduate studies in acoustics at Northwestern University
Authors: Bradlow Ann
Published: October 2014

Northwestern University has a vibrant and highly interdisciplinary community of acousticians. Of the 13 ASA technical areas, three have strong representation at Northwestern: Speech Communication, Psychological and Physiological Acoustics, and Musical Acoustics. Sound-related work is conducted across a wide range of departments including Linguistics (in the Weinberg College of Arts and Sciences), Communication Sciences & Disorders, and Radio/Television/Film (both in the School of Communication), Electrical Engineering & Computer Science (in the McCormick School of Engineering), Music Theory & Cognition (in the Bienen School of Music), and Otolaryngology (in the Feinberg School of Medicine). In addition, The Knowles Hearing Center involves researchers and labs across the university dedicated to the prevention, diagnosis and treatment of hearing disorders. Specific acoustics research topics across the university range from speech perception and production across the lifespan and across languages, dialect and socio-indexical properties of speech, sound design, machine perception of music and audio, musical communication, the impact of long-term musical experience on auditory encoding and representation, auditory perceptual learning, and the cellular, molecular, and genetic bases of hearing function. We invite you to visit our poster to learn more about the “sonic boom” at Northwestern University!
Detailed analysis of free reed initial transients
Authors: Wolff Daniel M. , Henessee Spencer , Cottingham James P.
Published: October 2014

The motion of the reed tongue in early stages of the attack transient has been studied in some detail for reeds from a reed organ. Oscillation waveforms were obtained using a laser vibrometer system, variable impedance transducer proximity sensors, and high speed video with tracking software. Typically, the motion of the reed tongue begins with an initial displacement of the equilibrium position, often accompanied by a few cycles of irregular oscillation. This is followed by a short transitional period in which the amplitude of oscillation gradually increases and the frequency stabilizes at the steady state oscillation frequency. In the next stage, the amplitude of oscillation continues to increase to the steady state value. The spectra derived from the waveforms in each stage have been analyzed, showing that the second transverse mode and the first torsional mode are both observed in the transient, with the amplitude of the torsional mode apparently especially significant in the earlier stages of oscillation. Comparison of reed tongues of different design have been made to explore the role of the torsional mode the initial excitation. Finite element simulations have been used to aid in the verification and interpretation of some of the results. [Work supported by US National Science Foundation REU Grant PHY-1004860.]
Comparison of traditional and matched grips: Rhythmic sequences played in jazz drumming
Authors: Scott E. K. Ellington , Cottingham James P.
Published: October 2014

Traditional and matched grips have been compared using a series of measurements involving rhythmic sequences played by experienced jazz drummers using each of the two grips. Rhythmic sequences played on the snare drum were analyzed using high speed video as well as other measurement techniques including laser vibrometry and spectral analysis of the sound waveforms. The high speed video images, used with tracking software, allow observation of several aspects of stick-drum head interaction. These include two-dimensional trajectories of the drum stick tip, a detailed picture of the stick-drum head interaction, and velocities of both the stick and the drum head during the contact phase of the stroke. Differences between the two grips in timing during the rhythmic sequences were investigated, and differences in sound spectrum were also analyzed. Some factors that may be player dependent have been explored, such as the effect of tightness of the grip, but an effort has been made to concentrate on factors that are independent of the player. [Work supported by US National Science Foundation REU Grant PHY-1004860.]
A harmonic analysis of oboe reeds
Authors: Gjebic Julia , Gipson Karen , Vavrikova Marlen
Published: October 2014

Because oboists make their own reeds to satisfy personal and physiological preferences, no two reed-makers construct their reeds in the same manner, just as no two oboe players have the same sound. The basic structure of an oboe reed consists of two curved blades of the grass Arundo donax bound to a conical metal tube (a staple) such that the edges of the blades meet and vibrate against one another when stimulated by a change in the surrounding pressure. While this basic structure is constant across reed-makers, the physical measurements of the various portions of the reed (tip, spine, and heart) resulting from the final stage of reed-making (scraping) can vary significantly between individual oboists. In this study, we investigated how the physical structure of individual reeds relates to the acoustic spectrum. We performed statistical analyses to discern which areas of the finished reed influence the harmonic series most strongly. This information is of great interest to oboists as it allows them quantitative insight into how their individual scrape affects their overall tone quality and timbre.
Modeling and numerical simulation of a harpsichord
Authors: Piperkova Rossitza , Reiter Sebastian , Rupp Martin , Wittum Gabriel
Published: October 2014

This research studies what influences various properties of a soundboard may have upon the acoustic feedback to gain a better understanding about the relevance of different properties regarding the sound characteristics. It may also help to improve the quality of simulations. We did a modal analysis of a real soundboard of a harpsichord using a Laser-Doppler-Vibrometer and also simulated several models of the very same soundboard in three space dimensions using the simulation software UG4. The used models of the sound board differed from each other by changing or skipping several properties and components. Then, we compared the simulated vibration patterns with the patterns measured on the real sound board to gain a better understanding about their influences on the vibrations. In particular, we used models with and without soundboard bars and bridge, but also were using different thicknesses for the soundboard itself.
Constructing alto saxophone multiphonic space
Authors: Moore Keith A.
Published: October 2014

Multiphonics are sonorities with two or more independent tones arising from instruments, or portions of instruments, associated with the production of single pitches. Since the 1960s multiphonics have been probed in two ways. Acousticians have explored the role of nonlinearity in multiphonic sound production (Benade 1976; Backus 1978; Keefe & Laden 1991) and musicians have created instrumental catalogs of multiphonic sounds (Bartolozzi 1967; Rehfeldt 1977; Kientzy 1982; Levine 2002). These lines of inquiry have at times been combined (Veale & Mankopf 1994). However, a meta-level analysis has not yet emerged from this work that answers basic questions such as how many kinds of multiphonics are found on one particular instrument and which physical conditions underlie such variety. The present paper suggests a database driven approach to the problem, producing a “quantitative resonant frequency curve” that shows every audible appearance of each frequency in a large—if not permutationally exhaustive—set of alto saxophone multiphonics. Compelling data emerges, including sonority prototypes, prototype transposition levels, and register specific distortions. Notably, true difference tones—audible difference tones unsustainable apart from a sounding multiphonic—are found to be register specific, not sonority specific; suggesting that physical locations (rather than harmonic contexts) underpin these sounds.
Massachusetts Wind Turbine Acoustics Research Project—Goals and preliminary results
Authors: Kaliski Kenneth , Lozupone David , McPhee Peter , O'Neal Robert , Zimmerman John , Wilson Kieth , Rowan-West Carol
Published: October 2014

The Commonwealth of Massachusetts (USA) has 43 operating wind turbine projects of 100 kW or more. At several of these projects, noise complaints have been made to state authorities. The Massachusetts Clean Energy Center, which provides funding for early stage analysis and development of wind power projects, and the Massachusetts Department of Environmental Protection, which regulates noise, launched the project to increase understanding of (1) wind turbine acoustic impacts, taking into account variables such as wind turbine size, technology, wind speed, topography and distance, and (2) the generation, propagation, and measurement of sound around wind turbine projects, to inform policy-makers on how pre- and post-construction wind turbine noise studies should be conducted. This study involved the collection of detailed sound and meteorological data at five locations. The resulting database and interim reports contain information on infrasound and audible frequencies, including amplitude modulation, tonality, and level. Analyses will include how the effects of wind shear and other variables may affect these parameters. Preliminary findings reflect the effects of meteorological conditions on wind turbine sound generation and propagation.
Wind turbine annoyance—A clue from acoustic room modes
Authors: Palmer William K.
Published: October 2014

When one admits that they do not know all the answers and sets out to listen to the stories of people annoyed by wind turbines, the clues can seem confusing. Why would some people report that they could get a better night’s sleep in an outdoor tent, rather than their bedroom? Others reported that they could sleep better in the basement recreation room of their home, than in bedrooms. That made little sense either. A third mysterious clue came from acoustic measurements at homes nearby wind turbines. Analysis of the sound signature revealed low frequency spikes, but at amplitudes well below those expected to cause annoyance. The clues merged while studying the acoustic room modes in a home, to reveal a remarkable hypothesis as to the cause of annoyance from wind turbines. In rooms where annoyance was felt, the frequencies flagged by room mode calculations and the low frequency spikes observed from wind turbine measurements coincided. This paper will discuss the research and the results, which revealed a finding that provides a clue to the annoyance, and potentially even a manner of providing limited relief.
Measurement and synthesis of wind turbine infrasound
Authors: Walker Bruce E. , Celano Joseph W.
Published: October 2014

As part of an ongoing investigation into the putative subjective effects of sub-20 Hz acoustical emissions from large industrial wind turbines, measurement techniques for faithful capture of emissions waveforms have been developed and reported. To evaluate perception thresholds, Fourier synthesis and high fidelity low-frequency playback equipment has been used to duplicate in a residential-like listening environment the amplitudes and wave slopes of the actual emissions, with pulsation rate in the range of 0.5–1.0 per second. Further, the amplitudes and slopes of the synthesized waves can be parametrically varied and the harmonic phases “scrambled” to assess the relative effects on auditory and other subjective responses. Measurement and synthesis system details and initial subjective response results will be shown.
Propagation of wind turbine noise through the turbulent atmosphere
Authors: Peng Yuan , Zhou Nina , Chen Jun , Li Kai Ming
Published: October 2014

It is well known that turbulence can cause fluctuations in the resulting sound fields. In the issue of wind turbine noise, such effect is non-negligible since either the inflow turbulence from nearby turbine wakes or the atmospheric turbulence generated by rotating turbine blades can increase the sound output of individual turbines. In this study, a combined approach of the Finite Element Method (FEM) and Parabolic Equation (PE) method is employed to predict the sound levels from a wind turbine. In the prediction procedure, the near field acoustic data is obtained by means of a computational fluid dynamic program which serves as a good starting field of sound propagation. It is then possible to advance wind turbine noise in range by using the FEM/PE marching algorithm. By incorporating the simulated turbulence profiles near wind turbine, more accurate predictions of sound field in realistic atmospheric conditions are obtained.
Understanding effects of man-made sound on fishes and turtles: Gaps and guidelines
Authors: Popper Arthur N. , Hawkins Anthony D.
Published: October 2014

Mitigating measures may be needed to protect animals and humans that are exposed to sound from man-made sources. In this context, the levels of man-made sound that will disrupt behavior or physically harm the receiver should drive the degree of mitigation that is needed. If a particular sound does not affect an animal adversely, then there is no need for mitigation! The problem then is to know the sound levels that can affect the receiving animal. For most marine animals, there are relatively few data to develop guidelines that can help formulate the levels at which mitigation is needed. In this talk, we will review recent guidelines for fishes and turtles. Since so much remains to be determined in order to make guidelines more useful, it is important that priorities be set for future research. The most critical data, with broadest implications for marine life, should be obtained first. This paper will also consider the most critical gaps and present recommendations for future research.
The relationship between underwater sounds generated by pile driving and fish physiological responses
Authors: Halvorsen Michele B.
Published: October 2014

Assessment of fish physiology after exposure to impulsive sound has been limited by quantifying physiological injuries, which range from mortal to recoverable. A complex panel of injuries was reduced to a single metric by a model called the Fish Index of Trauma. Over several years, six species of fishes from different morphological groupings, (e.g., physoclistous, physostomous, and lack of a swim bladder) were studied. The onset of physiological tissue effect was determined across a range of cumulative sound exposure levels with varying number of pile strikes. Follow up studies included investigation of healing from incurred injuries. The level of injury that animals expressed was influenced by their morphological grouping. Finally, investigation of the inner ear sensory hair cells showed that damage occurred at higher sound exposure levels than when the onset of tissue injury would occur.
A model to predict tissue damage in fishes from vibratory and impact pile driving
Authors: Hastings Mardi C.
Published: October 2014

Predicting effects of underwater pile driving on marine life requires coupling of pile source models with biological receiver models. Fishes in particular are very vulnerable to tissue damage and hearing loss from pile driving activities, especially since they are often restricted to specific habitat sites and migratory routes. Cumulative sound exposure level is the metric used by government agencies for sound exposure criteria to protect marine animals. In recent laboratory studies, physical injury and hearing loss in fish from simulated impact pile driving signals have even been correlated with this metric. Mechanisms for injury and hearing loss in fishes, however, depend on relative acoustic particle motion within the body of the animal, which can be disproportionately large in the vicinity of a pile. Modeling results will be presented showing correlation of auditory tissue damage in three species of fish with relative particle motion that can be generated 10–20 m from driving a 24-in diameter steel pile with an impact hammer. Comparative results with vibratory piling based on measured waveforms indicate that particle motion mechanisms may provide an explanation why the very large cumulative sound exposure levels associated with vibratory pile driving do not produce tissue damage.
Pile driving pressure and particle velocity at the seabed: Quantifying effects on crustaceans and groundfish
Authors: Miller James H. , Potty Gopu R. , Kim Hui-Kwan
Published: October 2014

In the United States, offshore wind farms are being planned and construction could begin in the near future along the East Coast of the US. Some of the sites being considered are known to be habitat for crustaceans such as the American lobster, Homarus americanus, which has a range from New Jersey to Labrador along the coast of North America. Groundfish such as summer flounder, Paralichthys dentatus, and winter flounder, Pseudopleuronectes americanus, also are common along the East Coast of the US. Besides sharing the seafloor in locations where wind farms are planned, all three of these species are valuable commercially. We model the effects on crustaceans, groundfish, and other animals near the seafloor due to pile driving. Three different waves are investigated including the compressional wave, shear wave and interface wave. A Finite Element (FE) technique is employed in and around the pile while a Parabolic Equation (PE) code is used to predict propagation at long ranges from the pile. Pressure, particle displacement, and particle velocity are presented as a function of range at the seafloor for a shallow water environment near Rhode Island. We will discuss the potential effects on animals near the seafloor.
Finite difference computational modeling of marine impact pile driving
Authors: MacGillivray Alexander O.
Published: October 2014

Computational models based on the finite difference (FD) method can be successfully used to predict underwater pressure waves generated by marine impact pile driving. FD-based models typically discretize the equations of motion for a cylindrical shell to model the vibrations of a submerged pile in the time-domain. However, because the dynamics of a driven pile are complex, realistic models must also incorporate physics of the driving hammer and surrounding acousto-elastic media into the FD formulation. This paper discusses several of the different physical phenomena involved, and shows some approaches to simulating them using the FD method. Topics include dynamics of the hammer and its coupling to the pile head, transmission of axial pile vibrations into the soil, energy dissipation at the pile wall due to friction, acousto-elastic coupling to the surrounding media, and near-field versus far-field propagation modeling. Furthermore, this paper considers the physical parameters required for predictive modeling of pile driving noise in conjunction with some practical considerations about how to determine these parameters for real-world scenarios.
On the challenges of validating a profound pile driving noise model
Authors: Ruhnau Marcel , Lippert Tristan , Heitmann Kristof , Lippert Stephan , von Estorff Otto
Published: October 2014

When predicting underwater sound levels for offshore pile driving by using numerical simulation models, appropriate model validation becomes of major importance. In fact, different parallel transmission paths for sound emission into the water column, i.e., pile-to-water, pile-to-soil, and soil-to-water, make a validation at each of the involved interfaces necessary. As the offshore environment comes with difficult and often unpredictable conditions, measurement campaigns are very time consuming and cost intensive. Model developers have to keep in mind that even thorough planning cannot overcome practical restrictions as well as technical limits and thus require for a reasonable model balancing. The current work presents the validation approach chosen for a comprehensive pile driving noise model—consisting of a near field finite element model as well as a far field propagation model—that is used for the prediction of noise levels at offshore wind farms.
Underwater noise and transmission loss from vibratory pile driving
Authors: Dahl Peter H. , Farrell Dara M.
Published: October 2014

High levels of underwater sound can be produced in vibratory pile driving that can carry regulatory implications. In this presentation, observations of underwater noise from vibratory pile driving made with a vertical line array placed at range 17 m from the source (water depth 7.5 m) are discussed, along with simultaneous measurements made at ranges of order 100 m. It is shown that the dominant spectral features are related to the frequency of the vibratory pile driving hammer (typically 15–35 Hz), producing spectral lines at intervals of this frequency. Homomorphic analysis removes these lines to reveal the underlying variance spectrum. The mean square pressure versus depth is subsequently studied in octave bands in view of the aforementioned spectral line property, with depth variation well modeled by an incoherent sum of sources distributed over the water column. Adiabatic mode theory is used to model the range dependent local bathymetry, including the effect of elastic seabed, and comparisons are made with simultaneous measurements of the mean-square acoustic pressure at ranges 200 and 400 m. This approach makes clear headway into the problem of predicting transmission loss versus range for this method of pile driving.
Using arrays of air-filled resonators to attenuate low frequency underwater sound
Authors: Lee Kevin M. , McNeese Andrew R. , Wilson Preston S. , Wochner Mark S.
Published: October 2014

This paper investigates the acoustic behavior of underwater air-filled resonators that could potentially be used in an underwater noise abatement system. The resonators are similar to Helmholtz resonators without a neck, consisting of underwater inverted air-filled cavities with combinations of rigid and elastic wall members, and they are intended to be fastened to a framework to form a stationary array surrounding a noise source, such as a marine pile driving operation, a natural resource production platform, or an air gun array, or to protect a receiving area from outside noise. Previous work has demonstrated the potential of surrounding low frequency sound sources with arrays of large stationary encapsulated bubbles that can be designed to attenuate sound levels over any desired frequency band and with levels of reduction up to 50 dB [Lee and Wilson, Proceedings of Meeting on Acoustics 19, 075048 (2013)]. Open water measurements of underwater sound attenuation using resonators were obtained during a set of lake experiments, where a low-frequency electromechanical sound source was surrounded by different arrays of resonators. The results indicate that air-filled resonators are a potential alternative to using encapsulated bubbles for low frequency underwater noise mitigation. [Work supported by AdBm Technologies.]
Axial impact driven buckling dynamics of slender beams
Authors: Gladden Josh R. , Handzy Nestor , Belmonte Andrew , Villermaux E.
Published: October 2014

We present experiments on the dynamic buckling of slender rods axially impacted by a projectile. By combining the results of Saint-Venant and elastic beam theory, we derive a preferred wavelength for the buckling instability, and experimentally verify the resulting scaling law for a range of materials using high speed video analysis. The scaling law for the preferred excitation mode depends on the ratio of the longitudinal speed of sound in the beam to the impact speed of the projectile. We will briefly present the imprint of this deterministic mechanism on the fragmentation statistics for brittle beams.
Vibration reduction in air handling systems
Authors: Campanella Angelo J.
Published: October 2014

Air handling units (AHU) mounted on elevated floors in old and new buildings can create floor vibrations that transmit through the building structure to perturb nearby occupants and sensitive equipment such as electron microscopes. Vibration sources include rotating fan imbalance and air turbulence. Isolation springs and the deflecting floor then create a two degree of freedom system. The analysis discussed here was originally published in “Sound and Vibration,” October 1987, pp. 26–30. Analysis parameters will be discussed along with inertia block affects and spring design strategy for floors of finite mass.
Determining fan generated dynamic forces for use in predicting and controlling vibration and structure-borne noise from air handling equipment
Authors: Phillips James E.
Published: October 2014

Vibration measurements were conducted to determine the dynamic forces imparted by an operating fan to the floor of an existing rooftop mechanical room. The calculated forces where then used as inputs to a Finite Element Analysis (FEA) computer model to predict the vibration and structure-borne noise in a future building with a similar fan. This paper summarizes the vibration measurements, analysis of the measured data, the subsequent FEA analysis of the future building and the recommendations developed to control fan generated noise and vibration in the future building.
Analysis of the forced response and radiation of a single-dimpled beam with different boundary conditions
Authors: Myers Kyle R. , Naghshineh Koorosh
Published: October 2014

Beading and dimpling via the stamping process has been used for decades to stiffen structures (e.g., beams, plates, and shells) against static loads and buckling. Recently, this structural modification technique has been used as a means to shift a structure's natural frequencies and to reduce its radiated sound power. Most studies to date have modeled dimpled beams and dimpled/beaded plates using the finite element method. In this research, an analytical model is developed for a beam with any number of dimples using Hamilton's Principle. First, the natural frequencies and mode shapes are predicted for a dimpled beam in free transverse vibration. A comparison with those obtained using the finite element method shows excellent agreement. Second, the forced response of a dimpled beam is calculated for a given input force. Mode shapes properly scaled from the forced response are used in order to calculate the beam strain energy, thus demonstrating the effect of dimpling on beam natural frequencies. Finally, some preliminary results are presented on the changes in the radiation properties of dimpled beams.
Creep behavior of composite interlayer and its influence on impact sound of floating floor
Authors: Cho Tongjun , Oh Byung Kwan , Kim Yousok , Park Hyo Seon
Published: October 2014

Creep-induced changes in dynamic stiffness of resilient interlayer used for floating floor is an important parameter of vibration isolator in long-term use. Compressive creep behavior of a composite layer made from closed-cell foam and fibrous material is investigated using a Findley equation-based method recommended by International Organization for Standardization (ISO). Quasi-static mechanical analysis is used to evaluate the dynamic stiffness influenced by the creep-deformation of the composite layer. It is shown in the present work that the long-term creep strain of the interlayer under nominal load of the floor and furniture is within the zone where dynamic stiffness increases. The changes in low frequency impact sound by the long-term creep deformation are estimated through real scale laboratory experiments and numerical vibro-acoustic analysis.