NDLI: Time-reversal focusing in a range-dependent ocean

Content Provider	IEEE Xplore Digital Library
Author	de Rosny, J. Derode, A. Tourin, A. Roux, P. Fink, M.
Copyright Year	2005
Description	Author affiliation: Lab. Ondes et Acoustique, Paris Univ., France (de Rosny, J.; Derode, A.; Tourin, A.; Roux, P.; Fink, M.)
Abstract	Shallow water time-reversal focusing has been successfully applied in ultrasonic laboratory experiments as well as in the ocean. For simplicity the ocean is usually considered as a range-independent waveguide. As a consequence, an omnidirectional vertical time-reversal array should refocus the wave not only at the source but also on a ring surrounding the array. In a real environment, the ocean bottom may be sloping. In this work, the influence of a slight inclination of the ocean bottom is studied. We show that the symmetry breaking yields an additional focusing in azimuth. We present ultrasonic experiments, which are well supported by a theoretical model based on modal decomposition and a stationary phase approach. The shape of the focal region in depth, range and azimuth is determined. The experiments are carried out in a water tank, at a central frequency of 3 MHz. The height of the waveguide ranges between 10 mm and 13.5 mm, its length is 500 mm. The inclination of the bottom is controlled by a step motor. A piezoelectric array is used to perform the TR operation. A needle hydrophone is used to check the accuracy of focusing. In the theoretical approach, the nature of the bottom can be taken into account, which is shown to significantly change the results. This is confirmed by numerical simulations performed in a realistic ocean environment.
Starting Page	449
Ending Page	453
File Size	686678
Page Count	5
File Format	PDF
ISBN	0780391039
DOI	10.1109/OCEANSE.2005.1511757
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2005-06-20
Publisher Place	France
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Oceans Azimuth Sensor arrays Laboratories Numerical simulation Predictive models Tellurium Shape Frequency Needles
Content Type	Text
Resource Type	Article

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

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