Physical Acoustics Research Articles

17th annual Anglo-French Physical Acoustics Conference (AFPAC)

Proceedings of the Anglo-French Physical Acoustics Conference (AFPAC)PrefaceThe 17th annual Anglo-French Physical Acoustics Conference (AFPAC) was held at the Selsdon Park Hotel is Surrey UK from 17th to 19th of January 2018. Over the years AFPAC has established a unique character where a most diverse range of topics covering the many application of acoustics and ultrasonics are discussed in a friendly environment with almost a residential workshop feel. The scientific standards are always high and PhD students make up a large proportion of the presentations. This 17th annual meeting was no exception. There were 42 presentations including 4 from invited speakers. These invited speakers included Andrea Colombi from Imperial College who talked about seismic waves and metamaterials. James Windmill of Strathclyde University presented work on how the study of insects is being used to develop new sensors. Emmanuel Moulin from Université de Valenciennes talked about coda waves in Structural Health monitoring (SHM) and Régis Marchiano from Université Pierre et Marie Curie in Paris presented work from a project on inverse problems using data collected by large arrays of microphones. Other subjects covered included acoustofluidics, acoustic tweezers and particle manipulation, biomedical ultrasound applications such as histotripsy, lithotripsy and HIFU, NDE and SHM for plate-like structures, corrosion and polycrystalline materials. There were also presentations on acoustically driven bubbles. A truly eclectic mix for those who are fascinated by all things acoustic!These proceedings contain a collections of papers submitted by the participants at the 2018 AFPAC. Submission of manuscripts has always been done on a voluntary basis and we have continued to maintain a high standard of reviewing for those who choose to have their work published here.Nader SaffariAlain Lhemery

Acoustic Emission Characteristics During Rock Fragmentation Processes Induced by Disc Cutter under Different Water Content Conditions

Based on a properly modified testing platform and Physical Acoustics Corporation (PAC) Micro-II acoustic emission (AE) system, a series of sequential indentation tests on granite samples with five different water contents was conducted to investigate the effect of the water content on the rock fragmentation process induced by a tunnel boring machine (TBM) disc cutter. During these tests, the effects of the water content on the characteristics of the peak penetration force, AE events, consumed energy, rock chip volume, and specific energy were analyzed. The results showed that the AE events were associated with the whole second indentation process of the granite. Under conditions with the same water content, the peak penetration forces and the consumed energy were smaller than those in the first indentation force. Additionally, subsequent chips were formed more frequently than the first indentation chips. The specific energy was lower, which meant that the rock breaking efficiency was higher. With the increase in the water content, the acoustic emission events reduced. The peak penetration force and consumed energy decreased with the increase in the water content. The volume of the chips increased significantly as the water content increased. The specific energy was promoted by the increase of the water content and then by the increase in the rock-breaking efficiency of the TBM disc cutter.

2E5-2 Laser Ultrasound Technique for Material Characterization of Thermal Sprayed Coatings(Physical Acoustics, Acousto-Optics II, Ocean Acoustics)

2E5-2 Laser Ultrasound Technique for Material Characterization of Thermal Sprayed Coatings(Physical Acoustics, Acousto-Optics II, Ocean Acoustics)

ИТОГИ XVI ШКОЛЫ-СЕМИНАРА ИМЕНИ АКАДЕМИКА Л.М. БРЕХОВСКИХ «АКУСТИКА ОКЕАНА»

This short communication presents the report on the XVI School-seminar named after academician L.M. Brekhovskikh. The conference combined with the XXXI session of the Russian Acoustic Society was held at Shirshov Institute of Oceanology, RAS in May 29 - June 1, 2018. The objectives of the conference were as follows: overview the ongoing research by Russian scientists in the field of ocean acoustics, present new results and exchange of opinions among members of the ocean acoustics community, discuss new priorities and future projects. The conference was attended by more than 150 participants from Shirshov Institute of Oceanology (Moscow), Ilyichev Pacific Oceanological Institute (Vladivostok), Prokhorov Institute of General Physics (Moscow), Institute of Applied Physics (Nizhniy Novgorod) and Andreev Acoustics Institute (Moscow), as well as from Sevastopol State University and Lomonosov Moscow State University. 87 reports were published in the volume Ocean Acoustics, Proceedings of the XVI L.M. Brekhovskikh Conference, Edited by V.V. Goncharov, T.I. Tsyplakova. Moscow: GEOS, 2018, 436 p. ISBN 978 5-89118-768-9.

Kuramoto and Sommerfeld: Toward comprehension of symphony orchestras in concert halls

Given comprehension of physical acoustics in concert halls, an accurate replacement to the inadequate concatenation of reverberation theory, geometric acoustics, and Beranek’s “perceptual categories” that long has held the field in architectural acoustics, it remains to explain how the symphony orchestra couples to the space. Individual instruments do not couple to the space directly, but first to others in their respective sections: first violins to first violins, second violins to second violins, violas to violas, cellos to cellos, basses to basses, and so on through the winds, and others. Each section is synchronized in phase by a Kuramoto mean-field. Then the coherently radiating sections couple to each other asynchronously and create a unique propagating field according to the Sommerfield radiation condition. Kuramoto mean-field coupling is key, for absent that a section’s individual instruments would tend to randomize in phase and sum to zero power. The Sommerfeld radiation condition does not guarantee such a uniform field, only a unique one, the power and information of which are conveyed to the audience as constrained by the usual Gabor-Huygens principle: proximity effects and resonant scattering are essential.

16th Anglo-French Physical Acoustics Conference (AFPAC)

16th Anglo-French Physical Acoustics Conference (AFPAC 2017)FOREWORD/PREFACEThe 16th Anglo-French Physical Acoustics Conference (AFPAC) was held on 23-25 January 2017 at the Laboratoire de Mécanique et d’Acoustique (LMA), Marseille, France. The event was organised by Dr Cécile Baron and Dr Philippe Lasaygues (LMA), who ensured a successful unfolding of both the conference sessions at the laboratory, and the social events in the city centre. The involvement of other staff from the LMA guaranteed that everything went very well and smoothly. A total of 50 papers were presented at the conference, which featured over 60 delegates. We would like to extend our thanks to Cécile, Philippe and the LMA staff for the pleasant times we had.The first day of AFPAC kicked off with an invited presentation by Dr Claudia Fritz (Institut Jean Le Rond d’Alembert, Paris, France) who provided a fascinating insight into the qualities of Stradivarius versus modern-built violins, with surprising results. A diverse range of physical acoustics topics were broached on this day, ranging from the experimental ultrasonic characterisation of cultural heritage reproductions, acoustic emissions as a tribochemical sensing technique, acoustic characterisation of microbubble clouds and defect characterisation using ultrasonic arrays. The first of two Conference Dinners was held at Le Malthazar, in the Vieux-Port area of Marseille. The second day featured an invited presentation by Prof Geoff Nash (University of Exeter, UK) on surface acoustic wave-graphene interactions. Other works presented on this day included liquid foams, soap films and acoustic dissipation processes, nonlinear elastic metamaterials, transcostal high-intensity focused ultrasound for the treatment of liver tumours, torsional guided wave EMAT for SHM, the acoustic signature of skin samples for cosmetic applications and a range of numerical methods for NDE. An invited talk was given by Dr Frédéric Padilla (Labtau, INSERM, Lyon, France), who discussed the applications of ultrasound for bone tissue engineering and regenerative medicine. The second Conference Dinner was held at Les Arcenaulx, also in the Vieux-Port area, and offered a selection of locally sourced foods and organic wines. During the Conference Dinner, the 2016 Bob Chivers prize (a prize awarded by IOP / Physical Acoustics Group to students engaged in a PhD in a UK university) was awarded to Dr Anton Van Pamel (Imperial College London, UK) for his paper entitled “Finite element modelling of elastic wave scattering within a polycrystalline material in two and three dimensions”.On the final day of the conference, Prof Jeff Bamber (Institute of Cancer Research, London, UK) gave an invited talk reviewing elastography as an imaging modality for characterising the biomedical properties of tissue, in research and in clinical medicine. The conference concluded with a tour of the state-of-the-art facilities at the Laboratoire de Mécanique et d’Acoustique.Dr Pierre Gélat (UCL, United Kingdom), IOP / Physical Acoustics Group, Chair,Dr Alain Lhémery (CEA, France), SFA / GAPSUS,Pr Nader Saffari (UCL, United Kingdom), IOP / Physical Acoustics Group.

Different bedding loaded coal mechanics properties and acoustic emission

Using TAW-2000KN electro-hydraulic servo rock press machines and the American Physical Acoustics Company’s SH-II acoustic emission systems, experimental studies began to address the mechanical properties in different beddings of loaded coal and the related acoustic emission characteristics, established based on the acoustic emission damage model, and verify the model. The results show that the mechanical properties of different coal sample beddings are distinctive, with maximum uniaxial compressive strength and elastic modulus of vertical stratification of coal samples and the minimum Poisson’s ratio. Thus, the minimum uniaxial compressive strength and elastic modulus of oblique bedding coal samples along with the maximum Poisson’s ratio in the processes of loading result in different bedding coal samples having different stress–strain curves, especially when different bedding coal samples experience the stages of fissure compression, elastic deformation, plastic deformation and instability and destruction. In addition, the displacement proportions of each stage of the loading process have relatively obvious differences: the loading times of vertical, parallel and oblique bedding coal are 495, 382 and 331 s, respectively, and their acoustic emission mutation points of peak stress are approximately 60, 41 and 33%, respectively. Thus, we can use the mutation point as precursor information to estimate the damage intensity in different bedding seams. The theoretical and experimental stress–strain curves obtained by the coal damage model are basically identical, verifying the reliability of the model and reflecting the feasibility of acoustic emission technology in the study of coal damage. The results can effectively forecast coal and gas outburst hazard in coal mines, especially highly gassy and outburst mines. It can also make comprehensive predictions for flooding accidents, roof fall accidents and other disasters, and provide valuable evacuation time for underground coal mine workers. The results are of great scientific significance in safeguarding the safety of coal mines.

Introduction to the Technical Committee on Physical Acoustics

The Technical Committee on Physical Acoustics (TCPA) of the Acoustical Society of America (ASA) is home to scientists and engineers with an interest in the underlying physics of acoustical phenomena and/or use acoustic waves to study the physical properties of matter. It is one of the broader communities within the Acoustical Society, as the research areas and methods cover the entire frequency range from infrasound to ultrasound, while studying the interaction of these sound waves in all three states of matter: liquids, solids, and gasses. TCPA currently has about 575 members with a primary interest in physical acoustics with 75–125 typically attending open TCPA meetings.

An introduction to the acoustical oceanography technical committee

Acoustics is a critical modality for interpreting the ocean environment, as evidenced by the complex acoustic physiology and sophisticated auditory processing capability of marine organisms, for example. The acoustical oceanography (AO) technical committee (TC) seeks to foster a broad range of work in pure and applied acoustics aimed at gaining new and fundamental understanding of physical, biological, geophysical, and chemical processes in the ocean and at its boundaries. With this focus, the AO TC is necessarily strongly interdisciplinary, having close ties to other TC’s such as animal bioacoustics, physical acoustics, signal processing, and underwater acoustics. This talk will describe many of the break-through discoveries that have been made in our field and point to inspiring present and future work.Acoustics is a critical modality for interpreting the ocean environment, as evidenced by the complex acoustic physiology and sophisticated auditory processing capability of marine organisms, for example. The acoustical oceanography (AO) technical committee (TC) seeks to foster a broad range of work in pure and applied acoustics aimed at gaining new and fundamental understanding of physical, biological, geophysical, and chemical processes in the ocean and at its boundaries. With this focus, the AO TC is necessarily strongly interdisciplinary, having close ties to other TC’s such as animal bioacoustics, physical acoustics, signal processing, and underwater acoustics. This talk will describe many of the break-through discoveries that have been made in our field and point to inspiring present and future work.

The Technical Committee on Musical Acoustics: Diverse membership with a common interest

The Technical Committee on Musical Acoustics is concerned with the application of science and technology to the field of music. Topics of current interest include the physics of musical sound production, music perception and cognition, and analysis and synthesis of musical sounds. TCMU is an interdisciplinary committee with ties to architectural, psychological and physiological, signal processing, speech, physical, and structural acoustics. Members of the committee represent a variety of backgrounds and interests, yet are united by a common interest in understanding all aspects of the science of music.

Numerical Modeling and Optimization of Acoustic Fields and Designs for High-Intensity Focused Ultrasound Transducers

Recent advances in the fields of physical acoustics, imaging and imaging techniques, piezoelectric materials, and ultrasound transducer designs have led to the emergence of new methods and equipment for ultrasound diagnostics, therapy, and aesthetic medicine, and to the development of traditional and emerging new applications. Ultrasound transducers for medical diagnostic equipment, particularly high-intensity focused ultrasound transducers (HIFU), are one promising use of piezoceramic and composite materials. This work is devoted to the development of mathematical models, numerical modeling, and optimizing acoustic fields and transducers of this type made of porous ferroelectric piezoceramics.

Broadband Calibration of Acoustic Emission and Ultrasonic Sensors from Generalized Ray Theory and Finite Element Models

This paper describes a calibration method for acoustic emission and ultrasonic sensors that is effective from 1 kHz to 1 MHz. The method combines generalized ray theory and finite element analysis to model wave propagation at higher and lower frequencies, respectively. A ball impact is used as a calibration source, a thick aluminum plate is used as the test block, and hot glue is used as the couplant. We demonstrate this method on five commercial piezoelectric sensors: Physical Acoustics (PAC) R15a, PAC WSa, Panametrics V101, Panametrics V103, and Valpey-Fisher Pinducer. Our calibration results show that reflections and other wave phases can be more clearly identified with the less-resonant Panametrics sensors. The PAC sensors have the greatest sensitivity and are able to detect surface normal displacements at least down to 1 pm amplitude in the 100s of kHz frequency band. Aperture effect is minimized by the small size of the Pinducer. Our method focuses on the amplitude response of the sensors (phase is ignored) and extends the calibration to a frequency band that is lower than typical analyses. Low frequency information is useful for determining the seismic moment of a seismic source (analogous to the magnitude of an earthquake) and can increase the amount of information acquired in a single recording.

Summary of "Biomedical Acoustics and Physical Acoustics: Shock Waves and Ultrasound for Calculus Fragmentation".

This paper summarizes the special session, "Shock Waves and Ultrasound for Calculus Fragmentation," that took place during the 176th Meeting of the Acoustical Society of America and 2018 Acoustics Week in Canada. The sessions were cosponsored by the Biomedical Acoustics and Physical Acoustics Technical Committees and consisted of ten talks by industry and academic researchers from institutions in the United States, France, and the Russian Federation. The sessions described basic and applied acoustic research to manage urinary stones.

Strain monitoring system for steel and concrete structures

The present work is part of a collaborative H2020 European funded research project called SENSKIN, that aims to improve Structural Health Monitoring (SHM) for transport infrastructure through the development of an innovative monitoring and management system for bridges based on a novel, inexpensive, skin-like sensor. The integrated SENSKIN technology will be implemented in the case of steel and concrete bridges, and tested, field-evaluated and benchmarked on actual bridge environment against a conventional health monitoring solution developed by Mistras Group Hellas. The main objective of the present work is to implement the autonomous, fully functional strain monitoring system based on commercially available off-the-shelf components, that will be used to accomplish direct comparison between the performance of the innovative SENSKIN sensors and the conventional strain sensors commonly used for structural monitoring of bridges. For this purpose, the mini Structural Monitoring System (mini SMS) of Physical Acoustics Corporation, a comprehensive data acquisition unit designed specifically for long-term unattended operation in outdoor environments, was selected. For the completion of the conventional system, appropriate foil-type strain sensors were selected, driven by special conditioners manufactured by Mistras Group. A comprehensive description of the strain monitoring system and its peripheral components is provided in this paper. For the evaluation of the integrated system’s performance and the effect of various parameters on the long-term behavior of sensors, several test steel pieces instrumented with different strain sensors configurations were prepared and tested in both laboratory and field ambient conditions. Furthermore, loading tests were performed aiming to validate the response of the system in monitoring the strains developed in steel beam elements subject to bending regimes. Representative results obtained from the above experimental tests have been included in this paper as well.

From underwater thunder to cavitation from pulsed ultrasound: One graduate student’s perspective of the years leading up to the formation of NCPA

The Physical Acoustics Research Group at the University of Mississippi (PARGUM) fostered a vibrant, multidisciplinary research environment in the early 1980s that incubated the concept of the National Center for Physical Acoustics (NCPA). It also provided graduate students, new to physical acoustics, an enticing glimpse into the breadth of the field and an exposure to a range of important contemporary problems. The research programs included terrestrial lightning detection and location, the underwater sound generated by lightning striking the ocean surface, long range sound propagation, propagation through porous materials, sound amplification by selective molecular excitation, acoustic levitation of bubbles and droplets, studies of acoustic cavitation thresholds and sonoluminescence, numerical simulation of bubble dynamics, and others. Beyond the scientific activities, PARGUM introduced a number of new acousticians to the ASA, many of whom have contributed to the leadership of the Society. The purpose of this presentation is to review some of the research results produced by the members of group from the time period as well as their contributions to the ASA.

Reflections on the origins of the National Center for Physical Acoustics

The National Center for Physical Acoustics arose from a group of faculty within the Physics Department at the University of Mississippi that had a strong interest in the general area of physical acoustics. With Hank Bass’s leadership, and support of the University of Mississippi’s central administration, this group constantly sought to expand their interest and their expertise in this area. Financial support from ONR permitted the expansion of their research space and the establishment of the Institute for Technology Development in the State of Mississippi led to eventual support from Congress. In October of 1986, by an act of the Congress of the United States of America, the National Center for Physical Acoustics was established. This presentation will provide some of the history concerning this event.

The unexpected but fulfilling impact of the Hunt Postdoctoral Research Fellowship in my academia career

Soon after I graduated with my Ph.D. degree in Physics from Washington State University in 2012 under the supervision of Dr. Philip L. Marston, I applied to the 2013–2014 Hunt Postdoctoral Research Fellowship. I was honored to receive the fellowship that funded my proposed postdoctoral research on acoustic propagation through internal waves under the joint supervision of Dr. Harry L. Swinney at the University of Texas at Austin and Dr. James F. Lynch at Woods Hole Oceanographic Institution. I am very grateful to the Hunt Fellowship for providing me with the opportunity to shift from analytical work on physical acoustics and fluid dynamics in my Ph.D. study to numerical and laboratory work on underwater acoustics in postdoctoral research. This has broadened the range of tools that I have to address acoustic problems in my academia career. I am fortunate to have had mentors who guided me on an unexpected but fulfilling career path that led me to becoming a faculty member in Physics at the University of Miss...

Physical Acoustics and Oxford: My experience as a researcher, a fellow, and beyond

In May 2015, I arrived in London after completing my Ph.D. work under the direction of Prof. Christy Holland at the University of Cincinnati and moved shortly thereafter with a goal to help establish one of the principal physical acoustics laboratories in the UK at Oxford. At the outset, it was my hope and expectation that the F. V. Hunt Fellowship would help to define a unique trajectory for my career. During the fellowship and along with the support of my mentor, Prof. Ronald Roy, I have been able to develop a network of collaborators and conduct research which will help to define the next phase of my career and work in acoustics. A highlight of my term as a Hunt Fellow was the opportunity to travel to China, during which I visited four research laboratories relating to my work in therapeutic ultrasound and delivered two invited seminars. I am grateful to the Hunt family estate and the Acoustical Society of America for offering this fellowship, which has not only provided me with the opportunity to conduct research, but also the flexibility to develop as an independent scientist and to work with international collaborators.In May 2015, I arrived in London after completing my Ph.D. work under the direction of Prof. Christy Holland at the University of Cincinnati and moved shortly thereafter with a goal to help establish one of the principal physical acoustics laboratories in the UK at Oxford. At the outset, it was my hope and expectation that the F. V. Hunt Fellowship would help to define a unique trajectory for my career. During the fellowship and along with the support of my mentor, Prof. Ronald Roy, I have been able to develop a network of collaborators and conduct research which will help to define the next phase of my career and work in acoustics. A highlight of my term as a Hunt Fellow was the opportunity to travel to China, during which I visited four research laboratories relating to my work in therapeutic ultrasound and delivered two invited seminars. I am grateful to the Hunt family estate and the Acoustical Society of America for offering this fellowship, which has not only provided me with the opportunity to cond...

Nucleation of a career in biomedical ultrasound

I was introduced to the Acoustical Society of America by Allan Pierce, who supervised my doctoral dissertation “Physical Theory of Narrow-Band Sounds Associated with Intracranial Aneurysms” in Penn State's Graduate Program in Acoustics. Professor Pierce also introduced me to Robert Waag, whose Diagnostic Ultrasound Research Laboratory I joined as a postdoctoral research associate at the University of Rochester. I received the 17th F. V. Hunt Postdoctoral Fellowship in 1994/1995 to investigate “Ultrasonic scattering: new techniques for measurement, analysis, and imaging.” As a Hunt Fellow in Professor Waag’s laboratory, I was immersed in the broad, interdisciplinary field of biomedical ultrasound, including tissue characterization from scattering measurements, breast imaging by diffraction tomography, and numerical modeling of propagation through realistic tissue models. My subsequent career has focused on biomedical applications of ultrasound, including positions at Penn State working with David Swanson, at Ethicon Endo-Surgery where Inder Makin recruited me to collaborate on a therapeutic ultrasound platform, and at University of Cincinnati where Christy Holland recruited me to join the Department of Biomedical Engineering. Through collaborations with these and many other acousticians, I have learned the value of applying physical acoustics principles to biomedical problems.

Distinguishing between varying amounts of diffusion subjectively and objectively

This paper summarizes findings from a study of both subjective perception and objective quantification of varying amounts of diffusion. Numerous impulse response measurements were collected from a physical acoustics testing facility that featured reversible absorptive/diffusive/reflective wall panels. The collected room impulse response measurements were utilized in subjective perception trials as well as an objective metric analysis. Subjective testing used auralizations from the measured impulse responses in audio comparison trials to determine how well diffusive room conditions could be discerned. It was found that more than 50% coverage of diffusive surface area was required for the average subject to discriminate between diffusive and absorptive wall conditions. Subjects were even less capable of discerning between diffusive and reflective wall conditions. The objective metric analysis identified the Number of Peaks methodology as the most effective metric for assessing diffusive room conditions from...