Response of acoustic imaging systems using convergent leaky waves to cylindrical flaws

Date

1989-9

Author

Günalp, Nilgün
Atalar, Abdullah

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

198
views

0
downloads

A theoretical study of imaging systems utilizing focused leaky surface acoustic waves (SAWs), and their response to certain kind of defects is presented. In particular, circular cylindrical inhomogeneities with axes perpendicular to the surface are considered. The scattering of the SAW from this cylinder is formulated with some approximations. The surface wave incident on the inhomogeneity is initially found as an angular spectrum of plane waves. However, to apply the boundary conditions at the cylindrical surface, the incident field has to be transformed into a superposition of cylindrical waves. Similarly, the scattered field, which is found in the form of outgoing cylindrical SAWs, is converted back to a plane wave spectrum. A formula is obtained for the transducer output voltage in terms of the position and the radius of the cylinder, and it is suitable for computer evaluation. By considering various locations for the cylinder, the sensitivity of the system around the focal point is studied. By comparing the output voltages for cylinders of different radii, the sensitivity of the system to the size of the inhomogeneity is examined. The numerical results are in agreement with the experimental observations.

Subject Keywords

Acoustics, Acoustic imaging, Surface acoustic waves, Sawing machines, Acoustic scattering, Voltage, Focusing, Acoustic waves, Boundary conditions, Surface waves, Transducers

URI

https://hdl.handle.net/11511/52154

Journal

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control

DOI

https://doi.org/10.1109/58.31794

Collections

Department of Electrical and Electronics Engineering, Article

Suggestions

OpenMETU
Core

Near-field scanning in the time domain on a spherical surface - A formulation using the free-space Green's function Koc, S; Aydın Çivi, Hatice Özlem; Buyukdura, OM (2001-10-01) Two formulations for determining the characteristics of an unknown source of acoustic waves using the measurement of its field at its near zone are presented. The measurement in both cases is to be performed on a spherical scan surface which encapsulates the source. The first is for an ideal probe which measures the field at its location. The knowledge of the field is sufficient; its normal derivative is not required. In the second formulation a realistic probe is considered. This time it is required only t...
Design and implementation of an annular acoustic levitation system Kandemir, Mehmet Hakan; Çalışkan, Mehmet; Department of Mechanical Engineering (2014) In standing wave acoustic levitation technique, a standing wave is obtained between a source and a reflector. Particles can be attracted towards pressure nodes in standing waves owing to the spring action. Hence, particles can be suspended in air. This operation can be performed on continuous structures as well as in several numbers of axes. In this study an annular acoustic levitation set-up is designed and built. The set-up consists of two langevin type piezoelectric transducers, two waveguides, an annula...
Underwater channel modeling for sonar applications Epçaçan, Erdal; Çiloğlu, Tolga; Department of Electrical and Electronics Engineering (2011) Underwater acoustic channel models have been studied in the context of communication and sonar applications. Acoustic propagation channel in an underwater environment exhibits multipath, time-variability and Doppler e ects. In this thesis, multipath fading channel models, underwater physical properties and sound propagation characteristics are studied. An underwater channel model for sonar applications is proposed. In the proposed model, the physical characteristics of underwater environment are considered ...
Thin Film PZT Acoustic Sensor for Fully Implantable Cochlear Implants İlik, Bedirhan; Koyuncuoğlu, Aziz; Uluşan, Hasan; Chamanıan, Salar; Işık Akçakaya, Dilek; Şardan Sukas, Özlem; Külah, Haluk (2017-09-06) This paper presents design and fabrication of a MEMS-based thin film piezoelectric transducer to be placed on an eardrum for fully-implantable cochlear implant (FICI) applications. Resonating at a specific frequency within the hearing band, the transducer senses eardrum vibration and generates the required voltage output for the stimulating circuitry. Moreover, high sensitivity of the sensor, 391.9 mV/Pa @900 Hz, decreases the required power for neural stimulation. The transducer provides highest voltage ou...
Comparison of PWM and PFM induction drives ID in,egarding audible noise and vibration for household applications Ertan, Hulusi Bülent (2004-11-01) This paper is aimed at comparing the performance of pulse frequency modulation (PFM) and pulsewidth modulation (PWM) techniques regarding audible noise generated from inverter-driven induction motors. For the purpose of illustrating the performance of the two modulation techniques, a drive developed for washing machine applications is considered. First, the measured and simulated harmonic content of this inverter is compared with the measured harmonic spectrum of a three-phase input-output commercial variab...

Citation Formats

N. Günalp and A. Atalar, “Response of acoustic imaging systems using convergent leaky waves to cylindrical flaws,” IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, pp. 507–516, 1989, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/52154.