in exploration seismology, estimation of elastic parameters of rocks using seismic amplitudes is considered as inverse problems. nowadays, model-based and more generally optimization-based algorithms are of the most common methods of seismic inversion. these algorithms which are known as deterministic methods, are suffering from two main problems; first, vertical resolution of outputs is very l...

An impedance matched surface is able, in principle, to totally absorb the incident sound and yield no reflection, and this is desired in many acoustic applications. Here we demonstrate a design of impedance matched sound absorbing surface with a simple construction. By coupling different resonators and generating a hybrid resonance mode, we designed and fabricated a metasurface that is impedanc...

Some active impedance control experiments in an anechoic chamber are reported. Further active methods are developed for the design of locally controlled absorption liners in air, whose basic principles were described by Olson and May and subsequently investigated practically by Guicking and his colleagues at the beginning of the 80’s. Two methods are described and tested. In the first, processi...

OBJECTIVES We introduce a new acoustic lens material for photoacoustic tomography (PAT) to improve lateral resolution while possessing excellent acoustic acoustic impedance matching with tissue to minimize lens induced image artifacts. BACKGROUND A large surface area detector due to its high sensitivity is preferable to detect weak signals in photoacoustic mammography. The lateral resolution ...

We present five kinds of labyrinthine or space-coiling acoustic metamaterials with tapered channels and apertures. These designs exhibit negative index behavior with modest dispersion, and also have substantially improved impedance matching compared to previously investigated labyrinthine cells. Experimentally measured effective material parameters are in good agreement with numerically compute...

This work describes a new approach to impedance matching for ultrasonic transducers. A single matching layer with high acoustic impedance of 16 MRayls is demonstrated to show a bandwidth of around 70%, compared with conventional single matching layer designs of around 50%. Although as a consequence of this improvement in bandwidth, there is a loss in sensitivity, this is found to be similar to ...

In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers use an ultrasound beam produced by a lead zirconate titanate (PZT) transducer oper...

Variations in the acoustic impedance throughout cells and tissue can be used to gain insight into cellular microstructures and the physiologic state of the cell. Ultrasound imaging can be used to create a map of the acoustic impedance, on which fluctuations can be used to help identify the dominant ultrasound scattering source in cells, providing information for ultrasound tissue characterizati...