نتایج جستجو برای: acoustic impedance volume
تعداد نتایج: 430710 فیلتر نتایج به سال:
Introduction: Reducing noise pollution has become an essential issue due to the increase in public concern and also social demands for a better lifestyle. Using sound absorption materials is a preferred method to reduce the noise pollution. Undesirable properties of pure polyurethane such as poor absorption of mechanical energy in narrow frequency ranges can be improved by providing polymeric n...
In a previous study, it was hypothesized that ultrasound-induced lung damage was related to the transfer of ultrasonic energy into the lungs (W. D. O'Brien et al. 2002, "Ultrasound-induced lung hemorrhage: Role of acoustic boundary conditions at the pleural surface," J. Acoust. Soc. Am. 111, 1102-1109). From this study a technique was developed to: 1) estimate the impedance (Mrayl) of fresh, ex...
The densities and ultrasound velocities in azithromycin solutions ethanol, 1-propanol 1-butanol at various concentrations three different temperatures (T = 300.15, 305.15, 310.15 K) have been measured. Based on the data obtained, derived acoustical parameters viz, acoustic impedance (Z), adiabatic compressibility (β), intermolecular free length (Lf), volume (Vf), Rao’s constant (R), Wada’s (W),...
Impedance maps (ZMs) have been proposed as a tool for modeling acoustic properties of tissue microstructure. Three-dimensional (3D) ZMs are constructed from a series of adjacent histological tissue slides that have been stained to emphasize acoustic impedance structures. The power spectrum of a 3DZM can be related to the ultrasound backscatter coefficient, which can be further reduced to a form...
We present a concept of "active material" with variable acoustic properties, being constituted of an electroacoustic transducer which acoustic impedance can be changed by an active mean. Among the different ways to obtain variable acoustic properties on an electroacoustic transducer's voicing face is the shunting of the transducer's electrical input. With such shunt devices, the acoustic impeda...
In 1946, Metz described what was probably the first practical impedance bridge for measurement of the acoustic reflex. Over the next four decades, diagnostic use of the acoustic reflex progressed in parallel with instrumentation refinements. Today, acoustic reflex threshold and decay testing are a routine component of the diagnostic audiology test battery. Recent advances in the measurement of ...
In this paper, a theoretical study is conducted in order to establish the feasibility of a liquid metal acoustic resonator ͑liquid gallium or liquid aluminum͒ for high-amplitude acoustic oscillations. The fundamental resonant frequency typically lies between 5 and 40 kHz. The oscillations are induced by an alternating Lorentz force density applied directly to the liquid metal volume. Depending on...
Impedance phlebography, a noninvasive approach to the diagnosis of venous thrombosis, depends on decreasing calf electrical impedance in normal subjects during inspiration. In order to assess the relationship between impedance changes and inspiratory volume, normal subjects were studied at various depths of inspiration. The mean inspiration volume required for a result indicating no evidence of...
Scanning Acoustic Microscopy (SAM) can deliver information on mechanical properties. For the investigation of bone microstructure we found the acoustic impedance as the most suitable parameter.A spatial resolution of approximately 1 um at 1 GHz allows morphological studies at the level of cellular structures. For quantitative analysis at high frequencies a smooth and plane surface is essential....
The Virtual Flute is a web service that provides many thousands of machine-predicted alternative fingerings. Alternative fingerings can offer variations in intonation and timbre, and can be easier to play in different musical contexts. Many play multiphonics. An advanced fingering guide is invaluable when exotic effects and demanding passages are required of the player. The Virtual Flute uses a...
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