{"title":"Diffraction phenomena with co-axial plane piston transducers","authors":"A. Goldstein, D. R. Gandhi, W. O’Brien","doi":"10.1109/ULTSYM.1994.401930","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401930","url":null,"abstract":"Using an exact theory of Beissner an experimental methodology is developed to accurately measure the effective radii of unfocused, circular plane piston transducers. The transient and steady-state diffraction concepts described by Lord are also used to propose an extension of the definition of the AIUM/NEMA pulse intensity integral to properly analyze cw and tone burst data","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121006570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Algorithms for eigenvalue problems in piezoelectric finite element analyses","authors":"Y. Yong, Y. Cho","doi":"10.1109/ULTSYM.1994.401716","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401716","url":null,"abstract":"Two algorithms for eigenvalue problems in piezoelectric finite element analyses are introduced. The first algorithm involves the use a Lanczos eigensolver, while the second algorithm uses a Rayleigh quotient iteration scheme. In both solution methods, schemes are implemented to reduce storage requirements and solution time. Also, both solution methods seek to preserve the sparsity structure of the stiffness matrix to realize major savings in memory. In the Lanczos solution method, the structural pattern of the consistent mass matrix is exploited to gain savings in both memory and solution time. In the Rayleigh quotient iteration method, an algorithm for generating good initial eigenpairs is employed to improve significantly its overall convergence rate, and convergence stability in the regions of closely spaced eigenvalues and repeated eigenvalues. The initial eigenvectors are obtained by interpolation from a coarse mesh. In order for this iterative method to be effective, an eigenvector of interest in the fine mesh must resemble an eigenvector in the coarse mesh. Hence, the method is effective for finding the set of eigenpairs in the low frequency range, and not in the high frequency range where the eigenvectors of the coarse mesh does not resemble well their counterparts in the fine mesh. Results of example problems are presented to show the savings in solution time and storage requirements of the proposed algorithms when compared with the conventional algorithm which uses static condensation to remove the electric potential degrees of freedom from the piezoelectric eigenvalue problem. The disadvantage of this conventional scheme is that the static condensation destroys the sparsity structure of the stiffness matrix, which leads to major increases in memory and solution time","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"220 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115577960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Stimulated material vibration by inhomogeneous plane waves and its application for bounded ultrasonic beams","authors":"K. Van Den Abeele, R. Briers, O. Leroy","doi":"10.1109/ULTSYM.1994.401692","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401692","url":null,"abstract":"Instead of an ordinary approach by means of homogeneous waves, more general complex harmonic waves may be used to examine medium vibration properties. It occurs that not homogeneous wave but rather only particular inhomogeneous plane waves can stimulate eigenvibrations of a given structure. The reflection and transmission of such inhomogeneous waves is investigated for plane parallel interfaces as well as their scattering at periodically corrugated boundaries between liquid and solids. Using an original description of a bounded ultrasonic beam as a finite superposition of inhomogeneous waves, this theory can be applied to examine the deformation of gaussian profiles and to explicitly relate this deformation to the stimulation of mode vibrations","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122190361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Bozkurt, G. Yaralioglu, A. Atalar, H. Koymen, K. Kramer
{"title":"Characterization and imaging with Lamb wave lens at gigahertz frequencies","authors":"A. Bozkurt, G. Yaralioglu, A. Atalar, H. Koymen, K. Kramer","doi":"10.1109/ULTSYM.1994.401857","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401857","url":null,"abstract":"Lamb wave lenses with conical refracting surfaces are fabricated for use at 400 MHz and 1 GHz. The conical surfaces are ground and polished with mechanical means and they are sufficiently smooth for the frequencies of interest. The wide bandwidth of transducers allow frequency tuning necessary for Lamb wave lenses, The fabricated lenses show the expected V(Z) performance. At high frequencies the attenuation in the coupling medium can be very high, but due to the smaller wavelength the resolution is better and defocus distance can be reduced. Inherently higher leaky wave sensitivity of Lamb wave lens enables a good V(Z) characterization ability at higher frequencies as compared to the conventional spherical lens. Subsurface imaging with these Lamb wave lenses gives satisfactory results for layered structures. Chosen object has leaky wave modes within the angular coverage of the lens. The images exhibit a resolution close to the diffraction limit. Experimental V(Z) curves obtained with these lenses along with images are presented","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"C-23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126475484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Design of 1-3 piezocomposite hydrostatic transducers using finite element analysis","authors":"J. Bennett, G. Hayward","doi":"10.1109/ULTSYM.1994.401775","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401775","url":null,"abstract":"1-3 piezocomposites were originally created because of their perceived good performance under hydrostatic operating conditions. For design evaluation, several researchers have devised constrained-dimensional models that are valid over a restricted operating range. This work describes a finite element method originally developed for thickness mode operation and extended to hydrostatic behaviour. The theory was compared against experimental data and with a constrained-dimensional model, producing encouraging results. A materials comparison for both the ceramic and polymer phase was performed using the finite element model, from which the desired properties of each phase were determined. The best hydrostatic performance for a 1-3 piezocomposite was obtained by using a low volume fraction composite of PZT-5H with potential enhancement by incorporation of stiffening plates. The polymer phase should be compliant and possess the lowest possible Poisson's ratio","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115455966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ground motion above a soft basin submitted to seismic waves","authors":"A. Wirgin","doi":"10.1109/ULTSYM.1994.401734","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401734","url":null,"abstract":"The resonant nature of ground motion above a semi-circular basin is demonstrated theoretically from the rigorous formulation and solution of the problem. The resonances are shown to be connected with the excitation of the normal modes of the bedrock-basin system. The analytical form of these modes is derived and exact as well as approximate procedures are given for computing the characteristic frequencies","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123055138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Acoustic image improvement by confidence levels","authors":"V. Murino, A. Trucco","doi":"10.1109/ULTSYM.1994.401844","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401844","url":null,"abstract":"This paper proposes a method for improving the quality of 2D and 3D underwater acoustic images, operating directly on the information extracted from each beam signal computed by a beamforming process. Some problems may arise when an acoustic image is built directly:on the basis of the envelope of the beam signals (as it is generally done) and this affects the quality of the results. The image quality can improve by using a general criterion operating as an interface between the beam signals and the image pixels. For each beam signal, this measure, called confidence level, assesses the reliability of the actual echoes in function of the similarity with expected echoes. Results obtained, in both real underwater 2D and simulated 3D images, are reported","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117220307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A multi-channel TeO2 acousto-optic modulator: design and characteristics","authors":"O. Bazzi, M. Gazalet, J. Kastelik, C. Bruneel","doi":"10.1109/ULTSYM.1994.401681","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401681","url":null,"abstract":"Multichannel acousto-optic interaction principle is presented. It is based on dividing the interaction bandwidth into separate channels. Limitations are due to intermodulation and crosstalk effects between neighbouring channels. Theoretical analysis of a two-channel modulator is developed. The results derived are compared with experimental ones obtained with a 95-MHz-bandwidth TeO2 processor and are presented in the paper","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121069723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Application of signal processing and neural net techniques to ultrasonic characterization of multilayered media","authors":"J. Rouvaen, K. Harrouche, M. Ourak, B. El Khaldi","doi":"10.1109/ULTSYM.1994.401690","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401690","url":null,"abstract":"The characterization of multilayered media using ultrasonic waves is classically performed using time of flight reflectometry in the pulsed regime or spectroscopy in the quasi-continuous wave regime. Our aim is to study the performances improvements given by numeric signal processing and neural nets methods. Starting from simple models for layered media, the reflection coefficient for high frequency pulsed ultrasonic waves is computed. The application of homomorphic processing techniques is studied theoretically, taking the transducer frequency response and the overall measurement system signal to noise ratio into account. Neural nets are then considered and it is shown that they provide a valid response in situations where other methods fail","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127099234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"2 dimensional modelling of lateral modes in 1-3 piezocomposites","authors":"D. Certon, F. Patat, O. Casula, L.P. Tran Hu Hue","doi":"10.1109/ULTSYM.1994.401778","DOIUrl":"https://doi.org/10.1109/ULTSYM.1994.401778","url":null,"abstract":"On account of their periodic structure 1-3 piezocomposites have spurious modes which are due to the acoustic waves undergoing Bragg-scattering in the elastic lattice. In the case of piezocomposite plates, lateral resonances are generated by multiple reflections of Lamb waves between structure discontinuities. However, for 2-2 composites several authors have simplified the theoretical approach by analysing the problem in terms of transverse waves travelling in a 1-D periodic medium of infinite thickness. They have shown that this hypothesis provides theoretical predictions with good accuracy. In this paper, by using the same assumption, a simple model for predicting the first and second lateral behavior in 1-3 piezocomposite is developed. Experimental results of lateral frequencies and displacement field at the composite surface measured with an interferometric laser technique are given and compared to theoretical predictions","PeriodicalId":394363,"journal":{"name":"1994 Proceedings of IEEE Ultrasonics Symposium","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124979410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}