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Communication with and transmission of energy to remote devices, such as deeply-implanted physiological recorders, using ultrasound presents several technical problems. In particular, device detection and piezoelectric sensor targeting remains difficult. Both tasks require differentiating the device from the surrounding fully passive tissues. Like radiofrequency identification devices, ultrasonic...
Time-reversal with multiple signal classification (TR-MUSIC) is an imaging method for locating point-like targets beyond the classic resolution limit. In the presence of noise, however, the super-resolution capability of TR-MUSIC is diminished. Recently a new method, phase-coherent MUSIC (PC-MUSIC), was developed. This algorithm modifies TR-MUSIC to make use of phase information from multiple frequencies...
A systematic framework for incubation of damage- state quantification in composites is almost absent in the current practice. Identification and quantification of the material state at its early stage has become significantly important in the field of structural health monitoring. Interaction between the intrinsic material state and ultrasonic wave signals, e.g., nonlinear ultrasonic, higher harmonic...
This paper presents a passive (X, Y) giant tap screen panel (GTP). Based on the time difference of arrival principle (TDOA), the device localizes low-energy impacts of around 1 mJ generated by fingernail taps. Selective detection of A0 Lamb waves generated in the upper frequency spectrum, around 100 kHz, makes it possible to detect light to strong impacts with equal resolution or precision, close...
In the original publication of the paper [1], the funding source was inadvertently omitted from the footnote on page 1016. The footnote should have read "Manuscript received November 20, 2012; accepted February 14, 2013. This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under project grant 110E216. A. Atalar acknowledges the support of the Turkish...
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...
Acoustic Bessel beams are known to produce an axial radiation force on a sphere centered on the beam axis (on-axial configuration) that exhibits both repulsor and tractor behaviors. The repulsor and the tractor forces are oriented along the beam's direction of propagation and opposite to it, respectively. The behavior of the acoustic radiation force generated by Bessel beams when the sphere lies outside...
The characterization of the spatial and frequency response of acoustic detectors is important for enabling accurate optoacoustic imaging. In this work, we developed a hybrid method for the characterization of the spatially dependent response of ultrasound detectors. The method is based on the experimental determination of the receive-mode electrical impulse response (EIR) of the sensor, which is subsequently...
A theoretical model for the multi-push??pull configuration of magnetoelectric (ME) laminated composites comprising magnetostrictive and piezoelectric layers with interdigitated electrodes encapsulated in polyimide film is presented. Analytical solutions for the ME voltage coefficient θE, ME charge coefficient θQ, noise charge density and equivalent magnetic noise were derived. Parametric studies are...
Measurement of the shear elastic constant of soft and highly damping tissue of high Poisson ratio is quite a challenging task. It is proposed to evaluate shear wave velocity and damping of tissue by measuring the shear skimming bulk waves using one interdigitated interdigital transducer on a piezoelectric layer, such as polyvinylidene fluoride, applied to the surface of the small tissue sample.
In beamforming, a critical design issue is the choice of the window or apodization function. Because the transverse beam pattern at focal depth is related to the Fourier transform of the apodization function, designers must evaluate the properties of the function and its transform, jointly, to optimize the system. This paper illustrates systematic approaches to designing useful functions.
This paper reports the fabrication and evaluation of a high-frequency ultrasonic transducer based on a new lead-free piezoelectric material for intravascular imaging application. Lead-free 0.5Ba(Zr0.2Ti0.8)O3??0.5(Ba0.7Ca0.3)TiO4(BZT-50BCT) ceramic with a high dielectric constant (~2800) was employed to develop a high-frequency (~30 MHz) needletype ultrasonic transducer. With superior piezoelectric...
An algorithm for an efficient parallel implementation of Snell's law of refraction, applicable to planar interfaces, is found by algebraic manipulation. The algorithm is tailored for general-purpose graphics processing unit (GP-GPU)-type processors. Numerical singularity in the solution is addressed. Performance is compared against other implementations. Application areas include real-time total focusing...
It has been hypothesized that estimates of mean scatterer spacing are useful indicators for pathological changes to the liver. A commonly employed estimator of the mean scatterer spacing is the location of the maximum of the collapsed average of coherence of the ultrasound radio-frequency signal. To date, in ultrasound, estimators for this quantity have been calculated with a single taper. Using frequency-domain...
Power ultrasonic applications such as cutting, welding, and sonochemistry often use Langevin transducers to generate power ultrasound. Traditionally, it has been proposed that the piezoceramic stack of a Langevin transducer should be located in the nodal plane of the longitudinal mode of vibration, ensuring that the piezoceramic elements are positioned under a uniform stress during transducer operation,...
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