نتایج جستجو برای: attenuation coefficient

تعداد نتایج: 216100  

2004
M D de Jonge C T Chantler

Recent measurements of mass attenuation coefficients have identified the determination of the thickness of the absorbing specimen as the major limitation to the accuracy of the measurement. We present a technique for determining the mass attenuation coefficient with high accuracy. The technique uses the integral of the density along a column extending through the thickness of the absorber, whic...

Journal: :The Journal of the Acoustical Society of America 2004
Naoyuki Akashi Jun-ichi Kushibiki Floyd Dunn

The bioultrasonic spectroscopy system was employed for measurements of velocity and attenuation coefficient of glucose solutions in the VHF/UHF range. The relation between the slope of the square of velocity and the relaxation parameters, and the relation between the frequency exponent on attenuation coefficient and the relaxation parameters are investigated. In order to carry out numerical cal...

Journal: :Ultrasonic imaging 2012
Kibo Nam Ivan M Rosado-Mendez Lauren A Wirtzfeld Goutam Ghoshal Alexander D Pawlicki Ernest L Madsen Roberto J Lavarello Michael L Oelze James A Zagzebski William D O'Brien Timothy J Hall

Backscatter and attenuation coefficient estimates are needed in many quantitative ultrasound strategies. In clinical applications, these parameters may not be easily obtained because of variations in scattering by tissues overlying a region of interest (ROI). The goal of this study is to assess the accuracy of backscatter and attenuation estimates for regions distal to nonuniform layers of tiss...

Journal: :The Journal of the Acoustical Society of America 1986
F Dunn

The dependence of the speed of sound and the attenuation coefficient upon exposure frequency, in the range of 1-5 MHz, and upon level of inflation, in the range of mass density 0.35-0.7 g/cm3, are reported. The speed of sound decreases linearly and the attenuation coefficient increases exponentially, for all levels of inflation studied.

2014
Robert L. Stewart Cindy K. Harnett

A light attenuation sensor system (LASS) for measurements in waters is described in this paper. The LASS records irradiance at multiple levels in the water column to provide a measure of the diffuse light attenuation coefficient which is strongly affected by suspended sediment. Dimensional analysis and geometric optical theory are used to relate the irradiance attenuation to sediment properties...

Journal: :Applied optics 2002
Vladimir I Haltrin

A one-parameter two-term Henyey-Greenstein (TTHG) phase function of light scattering in seawater is proposed. The original three-parameter TTHG phase function was reduced to the one-parameter TTHG phase function by use of experimentally derived regression dependencies between integral parameters of the marine phase functions. An approach to calculate a diffuse attenuation coefficient in the dep...

2012
Serge Grabtchak William M. Whelan

We present a new method for extracting the effective attenuation coefficient and the diffusion coefficient from relative spectrally resolved cw radiance measurements using the diffusion approximation. The method is validated on both simulated and experimental radiance data sets using Intralipid-1% as a test platform. The effective attenuation coefficient is determined from a simple algebraic ex...

Journal: :Applied optics 2002
Xiaobing Zheng Tommy Dickey Grace Chang

In situ time-series measurements of spectral diffuse downwelling irradiance from the Bermuda Testbed Mooring are presented. Averaged diffuse attenuation coefficients of downwelling irradiance, Kd,and their elastic and inelastic components are investigated at seven wavelengths. At shorter wavelengths (<510 nm), Kd is weakly dependent on the solar zenith angle owing to the prevailing scattering e...

C. Olaru, G.V. Ormenisan, M. Zadehrafi, S.A. Ciobanu,

Background: Lead glass has a wide variety of applications in radiation protection. This study aims to investigate some characteristics of lead glass such as the γ-ray energy-dependent mass and linear attenuation coefficients, the half-value layer thickness, and the absorbed dose distribution for specific energy. Materials and Methods: The attenuation parameters of different lead glass types aga...

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