Ultrasound waves have been used for imaging purposes for many years. However, a liquid interface has always been necessary between the transducer and the object being imaged due to a high mechanical resistance at the air-transducer interface. Recent advances in transducers have made it possible to omit the liquid interface, allowing imaging to be done through air interfaces. Because this is a relatively new field, research into ultrasound propagation in air is very limited. A comprehensive model of how an ultrasound wave propagates through air would expedite the study of air-coupled ultrasound for imaging. This thesis presents a mathematical model of two-dimensional linear acoustic wave propagation in air. The model takes as input the frequency and amplitude of an acoustic signal and outputs the pressure field over varying longitudinal and lateral distances from the source. The benefits of a mathematical model over a finite element model are first discussed, then the mathematical model for acoustic propagation in air is developed using both computer simulations and physical experiments in an anechoic chamber. Results are presented and compared to experimental data to confirm the validity of the mathematical model.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-01032008-114426 |
| Date | 07 January 2008 |
| Creators | Vetreno, JoAnna Ruth |
| Contributors | Dr. Hamid Krim, Dr. Michael B. Steer, Dr. Kevin Gard |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-01032008-114426/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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