Downloaded from orbit.dtu.dk on: Oct 05, 2021 Transducer models in the ultrasound simulation program FIELD II and their accuracy Jensen, Jørgen Arendt; Bæk, David Published in: Acoustical Society of America. Journal Link to article, DOI: 10.1121/1.3384240 Publication date: 2010 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Jensen, J. A., & Bæk, D. (2010). Transducer models in the ultrasound simulation program FIELD II and their accuracy. Acoustical Society of America. Journal, 127(3), 1828-1828. https://doi.org/10.1121/1.3384240 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. TUESDAY MORNING, 20 APRIL 2010 GRAND BALLROOM V, 9:15 A.M. TO 12:00 NOON Session 2aAO Acoustical Oceanography and Underwater Acoustics: Environmental Effects on Acoustic Propagation Roger M. Oba, Cochair Naval Research Lab., Code 7120, Washington, DC 20375 Ying-Tsong Lin, Cochair Woods Hole Oceanographic Inst., 210 Bigelow Bldg., Woods Hole, MA 02543 Contributed Papers 9:15 9:45 2aAO1. Acoustic ducting and refraction by sea bottom relief in shallow 2aAO3. Three dimensional parabolic equation modeling of an internal water. James F. Lynch, Alexey A. Shmelev, Ying-Tsong Lin, and Arthur E. wave event during Shallow Water 2006. Georges A. Dossot, James H. Newhall ͑Dept. of Appl. Ocean Phys. and Eng., Woods Hole Oceanograph. Miller, Gopu R. Potty ͑Dept. of Ocean Eng., Univ. of Rhode Island, Nar- Inst., 98 Water St., Woods Hole, MA 02543, [email protected]͒ ragansett Bay Campus, Narragansett, RI 02882͒, James F. Lynch, Ying- Tsong Lin ͑Woods Hole Oceanograph. Inst., Woods Hole, MA 02543͒, Observations show that shallow water bottom relief often has a band- Mohsen Badiey ͑Univ. of Delaware, Newark, DE 19716͒, and Kevin, B. limited directional spectrum produced by various oceanographic and geo- Smith ͑Naval Postgrad. School, Monterey, CA 93943͒ logical processes. This directional bottom feature is shown to have a notice- able effect on three-dimensional low-frequency acoustic propagation. An During the Shallow Water 2006 ͑SW06͒ experiment, a J-15 acoustic analytical study with an idealized model of straight sea bottom ripples has source deployed from the Research Vessel Sharp transmitted broadband shown that acoustic energy can be partially ducted between neighboring ͑100–500 Hz͒ chirp signals 15 km away from a vertical line array. The array ripples, and this ducting will affect acoustic propagation in shallow water. In was intentionally positioned near the shelf-break front and in an area where our work, we also study ducting and refracting due to idealized curved sea internal waves are known to occur. During the same time an internal wave, bottom ripples. Previous research has shown that non-linear internal waves “Event 44,” passed through the sound field such that the internal wave front can also create acoustical ducts. Comparative analysis of these two different was near parallel to the acoustic transmission path. Measured data show ducts is performed using our idealized model. The combined effects of in- substantial intensity fluctuations that vary over time and space due to com- ternal waves and bathymetry are studied for various relative directions of plex multimode and multipath ͑both two and three dimensional͒ interference internal wave front and bottom ripples. A numerical simulation of three- patterns. Of specific interest are fluctuations of measured intensity preceding dimensional sound propagation across realistic bathymetry and internal the internal wave’s arrival. Additionally, depth variability of the measured wave fluctuations is performed. In conclusion, both water column fluctua- acoustic intensities can be attributed to a warm water intrusion coinciding tions and bathymetry variability need to be taken into account when study- with the internal wave event. This presentation shows recent modeling re- ing three-dimensional acoustic propagation in shallow water. sults using the experimental geometry, acoustic signal parameters, and a simulated oceanographic environment based on environmental moorings and ship-born sensors. A new version of the three-dimensional Monterey–Miami parabolic equation code, which incorporates a user- defined sound speed field, is used. ͓Work sponsored by the Office of Naval 9:30 Research.͔ 2aAO2. Three-dimensional sound propagation over submarine canyons. 10:00 Ying-Tsong Lin, Timothy F. Duda ͑Dept. Appl. Ocean Phys. & Eng., Woods 2aAO4. Horizontal focusing/defocusing due to shallow-water internal Hole Oceanograph. Inst., Woods Hole, MA 02543, [email protected]͒, Jon M. waves. ͑ Collis ͑Colorado School of Mines, Golden, CO 80401͒, James F. Lynch, and Jing Luo, Mohsen Badiey Univ. of Delaware, Robinson Hall 112B, ͒ Arthur E. Newhall ͑Woods Hole Oceanograph. Inst., Woods Hole, MA 261 S. College Ave., Newark, DE 19716, [email protected] , and Ying- ͑ ͒ 02543͒ Tsong Lin Woods Hole Oceanograph. Inst., Woods Hole, MA 02543 ͑ ͒ Submarine canyons are common features of continental shelf and slope During the New Jersey Shallow Water 2006 SW06 experiment, an regions, e.g., Hudson Canyon in the Mid-Atlantic Bight. In this paper, the acoustic source was towed by the Research Vessel Sharp and followed the impact of submarine canyons on low-frequency sound propagation is stud- front of an internal wave packet. The source was transmitting broadband ͑ ͒ ied using a three dimensional ͑3-D͒ parabolic approximation numerical pro- acoustic signals 50–450 Hz in different angles with respect to the internal gram, which is implemented in a Cartesian coordinate system and utilizes wave front. The receptions of transmitted signal on a vertical hydrophone the split-step Fourier technique and a 3-D variant of the Thomson and Chap- line array are analyzed to study the horizontal focusing/defocusing that oc- man wide-angle approximation. This program will be first benchmarked curred when the internal wave front and acoustic track aligned closely. with a classic wedge problem, and then used to study an idealized canyon Based on ship-board radar images and temperature data collected on the en- environment to understand distinct 3-D sound propagation effects. The ide- vironmental moorings at various locations along the acoustic track, a de- ͑ ͒ alized environment has a Gaussian shaped canyon incising a slope. Horizon- tailed three-dimensional 3D environment is reconstructed for a 3-D para- tal focusing of sound in the canyon and energy flow into the canyon from an bolic approximation model to study the unique propagation scenario. off-axis sound source are observed. A realistic model using the Hudson Can- Construction of index of normal mode refraction for these data provides a yon bathymetry shows even more complex sound propagation situations. clear picture of acoustic energy focusing for this event. Data and model ͓ ͔ Propagation conditions over different seabed types are also compared, and comparison are in good agreement. Work supported by ONR321 OA the 3-D field sensitivity to bottom properties is investigated. ͓Work sup- ported by the Office of Naval Research.͔ 10:15—10:30 Break 1786 J. Acoust. Soc. Am., Vol. 127, No. 3, Pt. 2, March 2010 159th ASA Meeting/NOISE-CON 2010 1786 Downloaded 29 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 10:30 Sea surface roughness is one of several factors that significantly influ- 2aAO5. Spatial and temporal sound fluctuations in shallow water in ences high-frequency ͑1–50-kHz͒ acoustic wave propagation in shallow presence of internal soliton in transition areas. Boris Katsnelson and water. The evolving sea surface introduces several variability effects includ- Andrey Malikhin ͑Voronezh Univ., 1 Universitetskaya sq, Voronezh 394006, ing Doppler shift. Data analyses from high-frequency acoustic experiments Russia͒ show high-correlation between time, angle, and intensity fluctuations of re- ceived signals and varying sea surface conditions. In order to assess detailed Behavior of the sound field is considered in a 1–2-h time interval in acoustic signal interactions with the sea surface, a realistic wave model is presence of train of internal soliton ͑IS͒ crossing an acoustic track. During developed and combined with an acoustic ray-based model. Model validity this period moving ISs pass through several stages: approaching an acoustic is evaluated by comparing the results with data from multiple experiments. track, consequent covering source ͑receiver͒ only, both source and receiver, ͓Work supported by ONR 321OA.͔ receiver ͑source͒ only, and receding from an acoustic track. Correspondingly there are different regimes of interaction of the sound field with IS: horizon- 11:30 tal reflection, capture of signals in horizontal waveguide, adiabatic varia- 2aAO9. Acoustic observations of subsurface instability. Justin M. tions, and transition areas between these regimes. So, rather complex spatial Eickmeier, Mohsen Badiey ͑College of Earth, Ocean and Environment, and temporal structure of the sound field takes place, including frequency Univ. of Delaware, Newark, DE 19716, [email protected]͒, and Tokuo and modal dependence of its parameters. Theoretical analysis of variations Yamamoto ͑Rosenstiel School of Marine and Atmospheric Sci., Univ. of Mi- in the sound field on the basis of techniques of vertical modes and horizontal ami, Miami, FL 33149͒ rays ͑PE in horizontal plane͒ is carried out, and estimation of feasibility of an experimental setup is presented.