This paper describes the acoustic properties of a range of epoxy resins prepared by photocuring that are suitable for application in piezoelectric ultrasonic transducer matching layers. Materials, based on blends of diglycidyl ether of Bisphenol A and 1,4-cyclohexanedimethanol diglycidyl ether, are described. Furthermore, in order to vary the elastic character of the base resin, samples contain...

This paper presents the microfabrication of an acoustic impedance gradient matching layer on a spherically-shaped piezoelectric ultrasonic transducer. The acoustic matching layer can be designed to achieve higher acoustic energy transmission and operating bandwidth. Also included in this paper are a theoretical analysis of the device design and a micromachining technique to produce the novel tr...

Several AVO cross plot methods were compared using well data from 5 exploration drilled in deep water block in Krishna-Godavari basin. This study shows that AVO Impedance vs. Acoustic Impedance cross plot provides the best separation between gas bearing sands, water bearing sands and shale/clay. AVO Impedance (AVOI) attribute derived by normalizing the Acoustic Impedance (AI) and Elastic Impeda...

impedance (AI) and a parameter related to shear-wave velocity from seismic data, our ability to discriminate between different lithologies and fluid phases will increase. Prestack inversion on individual CDP gathers and inverting directly for VP, VS, and density have been tested in several ways, but the estimated parameters are often poorly determined. A more robust approach is to apply poststa...

Previous analytical and empirical studies of the human auditory system have shown that the cues used for localization are modified by the inclusion of nonrigid scattering surfaces (clothing, hair etc). This paper presents an investigation into the acoustic impedance properties of human hair. The legitimacy of a locally reactive surface assumption is investigated, and an appropriate boundary con...

Porous metallic material and its compound sound absorbing structures are very popular for the practical applications in harsh environment such as high temperature, humidity, and high sound pressure levels. There are all kinds of mathematic models available to predict the sound absorption properties of porous metal in literatures elsewhere. In this work, Cellular Automata is applied to model the...

Helmholtz resonators are commonly used for tuning of acoustic systems such as industrial processes, vehicle exhaust, engine intake manifold systems and more. Past efforts resulted in limited tuning capability and significant mechanical complexity. The work presented here considers a system that modifies the acoustic response of a system continuously, online, allowing optimum performance over a ...

In order to progress in the area of aeroacoustics, experimental measurements are necessary. Not only they required for engineering applications acoustics and noise engineering, but also necessary developing models acoustic phenomenon around us. One measurement particular importance is impedance. Acoustic Impedance measure opposition acoustical flow due pressure. It indicates how much sound pres...

What are shock waves? Extracorporeal shock waves are pressure waves generated outside the body that can be focused at a specific site within the body. Shock waves are characterized by high positive pressures, up to 100 MPa (over 100 times atmospheric pressure), and negative pressures of 5-10 MPa. They have a rapid rise time of 30-120 nanoseconds (10-9) and a short, 5 microsecond (10-6) pulse du...