An ultrasound tomography system with polyvinyl alcohol (PVA) moldings for coupling: in vivo results for 3-D pulse-echo imaging of the female breast.

Full-angle spatial compounding (FASC) is a concept for pulse-echo imaging using an ultrasound tomography (UST) system. With FASC, resolution is increased and speckles are suppressed by averaging pulse-echo data from 360°. In vivo investigations have already shown a great potential for 2-D FASC in the female breast as well as for finger-joint imaging.

Quantitative reconstruction of a disturbed ultrasound pressure field in a conventional hydrophone measurement.

Among various techniques enabling absolute measurements of ultrasound pressure, light refractive tomography (LRT) is so far the only one which is noninvasive, omnidirectional, and provides time-resolved results in pascals. By exploiting all these advantages, LRT shows suitability for investigations of ultrasound pressure fields, even in the case of adjacent medium boundaries which may cause considerable sound reflections. To demonstrate the potential research possibilities offered by this technique, we apply LRT to investigating the disturbance to a pressure field caused by a hydrophone.

Ultrasonic imaging of complex specimens by processing multiple incident angles in full-angle synthetic aperture focusing technique.

In the evaluation of large-scale metallic specimens, X-ray CT suffers from limited penetration, which results in artifacts in the reconstructed image. Data fusion of information obtained by different modalities allows correction of those artifacts. In this contribution, an approach is presented to provide complementary data of the inner pattern of the specimen by ultrasonic testing in immersion mode.

Magnetostrictive microelectromechanical loudspeaker.

A microelectromechnical-loudspeaker based on the magnetostrictive effect is presented. The membrane consists of a comb structure of monomorph bending cantilevers with an area of about 16 mm(2). Prototypes generate a sound pressure level (SPL) of up to 102 dB at 450 Hz with a total harmonic distortion of 2% inside a 2 cm(3) measurement volume.

A reliability study of light refractive tomography utilized for noninvasive measurement of ultrasound pressure fields.

Light refractive tomography is an optical measurement technique that is able to provide absolute sound pressure values in specified volumes. Because of the simplicity of the measurement principle as well as the compactness of the measurement setup, light refractive tomography offers higher measurement performance and fewer error sources than light diffraction tomography. In this contribution, a numerically simulated ultrasound pressure field is exploited to determine the experimental parameters and to analyze the error sources as well as their influences on final results.

A method for characterizing stapes prostheses by their mechanical transfer function.

In this contribution, we present and evaluate a method for characterizing stapes prostheses by their mechanical transfer function. The measurements were carried out after a stapedotomy surgery was performed in three human temporal bones conserved in 4% formaldehyde. The inner ear was drained of fluid.

Optical 3-D metric measurements of local vocal fold deformation characteristics in an in vitro setup.

Understanding vocal fold dynamics presents an essential part in treating voice disorders as it is the prerequisite to appropriate medical therapy. Various physical and numerical models exist for simulation purposes, all relying on simplified material parameters. To improve current approaches, data of realistic tissue behavior, i.

FEM-Based determination of real and complex elastic, dielectric, and piezoelectric moduli in piezoceramic materials.

We propose an enhanced iterative scheme for the precise reconstruction of piezoelectric material parameters from electric impedance and mechanical displacement measurements. It is based on finite-element simulations of the full three-dimensional piezoelectric equations, combined with an inexact Newton or nonlinear Landweber iterative inversion scheme. We apply our method to two piezoelectric materials and test its performance.

Beam profile measurements using light refractive tomography.

A method for reconstructing the sound pressure profile from interferometer measurements using computed tomography is presented. In accordance with the term light diffraction tomography, in short we want to call the method light refractive tomography, because it is based on the sound pressure-induced refractive index change along the laser beam. We compare three tomographic reconstruction methods applicable to axisymmetric beam profiles, namely, the filtered back-projection, the Hankel Fourier method, and the onion peeling method, the latter based on Nestor and Olsens algorithm.

A coupled finite-element, boundary-integral method for simulating ultrasonic flowmeters.

Today's most popular technology of ultrasonic flow measurement is based on the transit-time principle. In this paper, a numerical simulation technique applicable to the analysis of transit-time flowmeters is presented. A flowmeter represents a large simulation problem that also requires computation of acoustic fields in moving media.

Finite-element simulation of wave propagation in periodic piezoelectric SAW structures.

Many surface acoustic wave (SAW) devices consist of quasiperiodic structures that are designed by successive repetition of a base cell. The precise numerical simulation of such devices, including all physical effects, is currently beyond the capacity of high-end computation. Therefore, we have to restrict the numerical analysis to the periodic substructure.