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Jafarzadeh E, Amini MH, Sinclair AN. Spectral Shift Originating from Non-linear Ultrasonic Wave Propagation and Its Effect on Imaging Resolution. Ultrasound Med Biol 2021; 47:1893-1903. [PMID: 33896680 DOI: 10.1016/j.ultrasmedbio.2021.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 03/13/2021] [Accepted: 03/15/2021] [Indexed: 06/12/2023]
Abstract
An amplitude-dependent downshift in the fundamental wave spectrum of a propagating ultrasonic pulse caused by non-linear wave propagation is described. The effects of non-linearity and the associated downshift on spatial resolution are also studied. The amounts of downshift and spatial resolution are extracted from the numerically simulated beam profile based on the KZK equation. Results for a 25-MHz transducer reveal that non-linear effects can lead to 58% additional downshift in the centre frequency of a pulse compared with a linear case with downshift caused only by attenuation. This additional downshift causes about 50% degradation in axial resolution. However, as the beam becomes narrower from the non-linear effects, the overall effect of non-linearity still leads to improved lateral resolution (≤26%). Therefore, as non-linearity increases with wave pressure, it is concluded that the increase in source pressure improves lateral resolution and degrades axial resolution.
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Affiliation(s)
- Ehsan Jafarzadeh
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.
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Lebon GSB, Salloum-Abou-Jaoude G, Eskin D, Tzanakis I, Pericleous K, Jarry P. Numerical modelling of acoustic streaming during the ultrasonic melt treatment of direct-chill (DC) casting. Ultrason Sonochem 2019; 54:171-182. [PMID: 30755390 DOI: 10.1016/j.ultsonch.2019.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 05/12/2023]
Abstract
Acoustic streaming and its attendant effects in the sump of a direct-chill (DC) casting process are successfully predicted under ultrasonic treatment for the first time. The proposed numerical model couples acoustic cavitation, fluid flow, heat and species transfer, and solidification to predict the flow pattern, acoustic pressure, and temperature fields in the sump. The model is numerically stable with time steps of the order of 0.01 s and therefore computationally attractive for optimization studies necessitating simulation times of the order of a minute. The sump profile is altered by acoustic streaming, with the slurry region depressed along the centreline of the billet by a strong central jet. The temperature gradient in the transition zone is increased, potentially interfering with grain refinement. The cooling rate in the sump is also altered, thereby modifying the dendrite arm spacing of the as-cast billet. The relative position of the sonotrode affects the sump profile, with the sump depth decreased by around 5 mm when the sonotrode is moved above the graphite ring level by 100 mm. The acoustic streaming jet penetrates into the slurry zone and, as a result, the growth direction of dendritic grains in the off-centre position is altered.
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Affiliation(s)
- G S Bruno Lebon
- Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, Uxbridge UB8 3PH, United Kingdom; Computational Science and Engineering Group (CSEG), Department of Mathematical Sciences, University of Greenwich, London SE10 9LS, United Kingdom.
| | - Georges Salloum-Abou-Jaoude
- Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, Uxbridge UB8 3PH, United Kingdom; Constellium, Parc Economique Centr'alp, CS10027, Voreppe 38341 cedex, France
| | - Dmitry Eskin
- Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, Uxbridge UB8 3PH, United Kingdom; Tomsk State University, Tomsk 634050, Russia
| | - Iakovos Tzanakis
- Faculty of Technology, Design and Environment, Oxford Brookes University, Oxford OX33 1HX, United Kingdom; Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom
| | - Koulis Pericleous
- Computational Science and Engineering Group (CSEG), Department of Mathematical Sciences, University of Greenwich, London SE10 9LS, United Kingdom
| | - Philippe Jarry
- Constellium, Parc Economique Centr'alp, CS10027, Voreppe 38341 cedex, France
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Jafarzadeh E, Sinclair AN. Non-linear Wave Propagation and Safety Standards for Diagnostic Ultrasound Devices. Ultrasound Med Biol 2019; 45:11-20. [PMID: 30292462 DOI: 10.1016/j.ultrasmedbio.2018.08.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 08/23/2018] [Accepted: 08/28/2018] [Indexed: 06/08/2023]
Abstract
Safety standards for clinical diagnostic ultrasonic devices were developed for use in relatively low-frequency systems (1-10 MHz), under the assumption that non-linear effects would be negligible. This article reviews ways in which neglecting non-linear wave propagation affects the measurements and calculations required to comply with safety standards and U.S. Food and Drug Administration guidance that recognizes these standards. An attempt is made to evaluate whether ignoring non-linear effects could result in significant error in the exposure quantities defined in these standards at either low or high frequencies, based on published literature. This article maintains that although non-linear effects have been considered in some parts of safety standards related to hydrophone requirements, the coverage is inadequate, especially for modern equipment with high working frequencies. A new approach is required to assess the magnitude of thermal heating for recently developed high-frequency systems to incorporate non-linear effects. In contrast, the current approach for evaluating the risk of cavitation can be used after appropriate modifications.
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Affiliation(s)
- Ehsan Jafarzadeh
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.
| | - Anthony N Sinclair
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
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Bowers MT, Friedlaender AS, Janik VM, Nowacek DP, Quick NJ, Southall BL, Read AJ. Selective reactions to different killer whale call categories in two delphinid species. J Exp Biol 2018; 221:jeb162479. [PMID: 29895580 PMCID: PMC6515772 DOI: 10.1242/jeb.162479] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 04/09/2018] [Indexed: 11/20/2022]
Abstract
The risk of predation is often invoked as an important factor influencing the evolution of social organization in cetaceans, but little direct information is available about how these aquatic mammals respond to predators or other perceived threats. We used controlled playback experiments to examine the behavioral responses of short-finned pilot whales (Globicephala macrorhynchus) off Cape Hatteras, NC, USA, and Risso's dolphins (Grampus griseus) off the coast of Southern California, USA, to the calls of a potential predator, mammal-eating killer whales. We transmitted calls of mammal-eating killer whales, conspecifics and baleen whales to 10 pilot whales and four Risso's dolphins equipped with multi-sensor archival acoustic recording tags (DTAGs). Only playbacks of killer whale calls resulted in significant changes in tagged animal heading. The strong responses observed in both species occurred only following exposure to a subset of killer whale calls, all of which contained multiple non-linear properties. This finding suggests that these structural features of killer whale calls convey information about predatory risk to pilot whales and Risso's dolphins. The observed responses differed between the two species; pilot whales approached the sound source while Risso's dolphins fled following playbacks. These divergent responses likely reflect differences in anti-predator response mediated by the social structure of the two species.
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Affiliation(s)
- Matthew T Bowers
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA
- Southall Environmental Associates, Inc., 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USA
| | - Ari S Friedlaender
- Southall Environmental Associates, Inc., 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USA
- Institute for Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA 95060, USA
| | - Vincent M Janik
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, Fife KY16 8LB, UK
| | - Douglas P Nowacek
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA
- Electrical and Computer Engineering, Pratt School of Engineering, Duke University, Durham, NC 27708, USA
| | - Nicola J Quick
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA
| | - Brandon L Southall
- Southall Environmental Associates, Inc., 9099 Soquel Drive, Suite 8, Aptos, CA 95003, USA
| | - Andrew J Read
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA
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Grisey A, Heidmann M, Letort V, Lafitte P, Yon S. Influence of Skin and Subcutaneous Tissue on High-Intensity Focused Ultrasound Beam: Experimental Quantification and Numerical Modeling. Ultrasound Med Biol 2016; 42:2457-2465. [PMID: 27471120 DOI: 10.1016/j.ultrasmedbio.2016.06.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 05/02/2016] [Accepted: 06/06/2016] [Indexed: 06/06/2023]
Abstract
High-intensity focused ultrasound (HIFU) enables the non-invasive thermal ablation of tumors. However, numerical simulations of the treatment remain complex and difficult to validate in clinically relevant situations. In this context, needle hydrophone measurements of the acoustic field downstream of seven rabbit tissue layers comprising skin, subcutaneous fat and muscle were performed in different geometrical configurations. Increasing curvature and thickness of the sample were found to decrease the focusing of the beam: typically, a curvature of 0.05 mm(-1) decreased the maximum pressure by 45% and doubled the focal area. A numerical model based on k-Wave Toolbox was found to be in very good agreement with the reported measurements. It was used to extrapolate the effect of the superficial tissues on peak positive and peak negative pressure at focus, which affects both cavitation and target heating. The shape of the interface was found to have a strong influence on the values, and it is therefore an important parameter to monitor or to control in the clinical practice. This also highlights the importance of modeling realistic configurations when designing treatment procedures.
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Affiliation(s)
- Anthony Grisey
- Mathematics in Interaction with Computer Science Laboratory, CentraleSupélec, Châtenay-Malabry, France; Theraclion, Malakoff, France.
| | - Marc Heidmann
- Theraclion, Malakoff, France; Département de Physique, École Normale Supérieure de Lyon, Université de Lyon, Lyon, France
| | - Veronique Letort
- Mathematics in Interaction with Computer Science Laboratory, CentraleSupélec, Châtenay-Malabry, France
| | - Pauline Lafitte
- Mathematics in Interaction with Computer Science Laboratory, CentraleSupélec, Châtenay-Malabry, France
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Renaud G, Bosch JG, Van Der Steen AFW, De Jong N. Low-amplitude non-linear volume vibrations of single microbubbles measured with an "acoustical camera". Ultrasound Med Biol 2014; 40:1282-1295. [PMID: 24613552 DOI: 10.1016/j.ultrasmedbio.2013.12.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 06/03/2023]
Abstract
Contrast-enhanced ultrasound imaging is based on the detection of non-linear vibrational responses of a contrast agent after its intravenous administration. Improving contrast-enhanced images requires an accurate understanding of the vibrational response to ultrasound of the lipid-coated gas microbubbles that constitute most ultrasound contrast agents. Variations in the volume of microbubbles provide the most efficient radiation of ultrasound and, therefore, are the most important bubble vibrations for medical diagnostic ultrasound imaging. We developed an "acoustical camera" that measures the dynamic volume change of individual microbubbles when excited by a pressure wave. In the work described here, the technique was applied to the characterization of low-amplitude non-linear behaviors of BR14 microbubbles (Bracco Research, Geneva, Switzerland). The amplitude dependence of the resonance frequency and the damping, the prevalence of efficient subharmonic and ultraharmonic vibrations and the amplitude dependence of the response at the fundamental frequency and at the second harmonic frequency were investigated. Because of the large number of measurements, we provide a statistical characterization of the low-amplitude non-linear properties of the contrast agent.
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Affiliation(s)
- Guillaume Renaud
- Biomedical Engineering, ThoraxCenter, Erasmus Medical Center, Rotterdam, The Netherlands.
| | - Johan G Bosch
- Biomedical Engineering, ThoraxCenter, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Antonius F W Van Der Steen
- Biomedical Engineering, ThoraxCenter, Erasmus Medical Center, Rotterdam, The Netherlands; Acoustical Wavefield Imaging Research Group, Delft University of Technology, Delft, The Netherlands
| | - Nico De Jong
- Biomedical Engineering, ThoraxCenter, Erasmus Medical Center, Rotterdam, The Netherlands; Acoustical Wavefield Imaging Research Group, Delft University of Technology, Delft, The Netherlands
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Knoop C, Fritsching U. Dynamic forces on agglomerated particles caused by high-intensity ultrasound. Ultrasonics 2014; 54:763-769. [PMID: 24152872 DOI: 10.1016/j.ultras.2013.09.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/09/2013] [Accepted: 09/24/2013] [Indexed: 06/02/2023]
Abstract
In this paper the acoustic forces on particles and agglomerates caused by high-intensity ultrasound in gaseous atmosphere are derived by means of computational fluid dynamics (CFD). Sound induced forces cause an oscillating stress scenario where the primary particles of an agglomerate are alternatingly pressed together and torn apart with the frequency of the applied wave. A comparison of the calculated acoustic forces with respect to the inter particle adhesion forces from Van-der-Waals and liquid bridge interactions reveals that the separation forces may reach the same order of magnitude for 80 μm sized SiO2-particles. Hence, with finite probability acoustically agitated gases may de-agglomerate/disperse solid agglomerate structures. This effect is confirmed by dispersion experiments in an acoustic particle levitation setup.
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Affiliation(s)
- Claas Knoop
- Department of Particles and Process Engineering, University of Bremen, Foundation Institute of Materials Science, Badgasteiner Str. 3, D-28359 Bremen, Germany.
| | - Udo Fritsching
- Department of Particles and Process Engineering, University of Bremen, Foundation Institute of Materials Science, Badgasteiner Str. 3, D-28359 Bremen, Germany
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