title: A fractional Fourier transform analysis of a bubble excited by an ultrasonic chirp.
abstract: The fractional Fourier transform is proposed here as a model based, signal processing technique for determining the size of a bubble in a fluid. The bubble is insonified with an ultrasonic chirp and the radiated pressure field is recorded. This experimental bubble response is then compared with a series of theoretical model responses to identify the most accurate match between experiment and theory which allows the correct bubble size to be identified. The fractional Fourier transform is used to produce a more detailed description of each response, and two-dimensional cross correlation is then employed to identify the similarities between the experimental response and each theoretical response. In this paper the experimental bubble response is simulated by adding various levels of noise to the theoretical model output. The method is compared to the standard technique of using time-domain cross correlation. The proposed method is shown to be far more robust at correctly sizing the bubble and can cope with much lower signal to noise ratios.
authors.affiliation: Department of Mathematics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, United Kingdom. euan.barlow@strath.ac.uk
authors.forename: Euan
authors.initials: E
authors.lastname: Barlow
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Mulholland
mesh_terms: D003198:Computer Simulation; D003287:Contrast Media; D005583:Fourier Analysis; D005740:Gases; D016014:Linear Models; D045423:Microbubbles; D009716:Numerical Analysis, Computer-Assisted; D010316:Particle Size; D011312:Pressure; D013010:Sonication; D013500:Surface Tension; D013997:Time Factors; D014465:Ultrasonics; D014783:Viscosity
chemical_list: D003287:Contrast Media; D005740:Gases