نتایج جستجو برای: attenuation coefficient

تعداد نتایج: 216100  

2010
Dan P. Popescu Costel Flueraru Youxin Mao Shoude Chang Michael G. Sowa

The sensitivity of optical coherence tomography images to sample morphology is tested by two methods. The first method estimates the attenuation of the OCT signal from various regions of the probed tissue. The second method uses a box-counting algorithm to calculate the fractal dimensions in the regions of interest identified in the images. Although both the attenuation coefficient as well as t...

Introduction: This study introduces a novel polyvinyl chloride (PVC)/tungsten composites with characterization of their shielding properties by employing different techniques. Methods: The PVC/tungsten composites were produced by employing various weight fractions of tungsten micro-particles including 0, 20, and 40 % wt via melt blending method. In the next st...

2010
R. Abbasi S. W. Barwick M. L. Benabderrahmane P. A. Evenson A. R. Fazely T. K. Gaisser H. Kolanoski D. J. Koskinen

Using the South Pole Acoustic Test Setup (SPATS) and a retrievable transmitter deployed in holes drilled for the IceCube experiment, we have measured the attenuation of acoustic signals by South Pole ice at depths between 190 m and 500 m. Three data sets, using different acoustic sources, have been analyzed and give consistent results. The method with the smallest systematic uncertainties yield...

2014
Barun Raychaudhuri

Abstract—A methodology is proposed for estimating the optical attenuation and proportional depth variation of shallow inland water. The process is demonstrated with EO-1 Hyperion hyperspectral and IRS-P6 LISS-3 multispectral images of Kolkata city nearby area centered around 22o33′ N 88o26′ E. The attenuation coefficient of water was found to change with fine resolution of wavebands and in pres...

Journal: :The International Journal of Advanced Manufacturing Technology 2008

2003
LIN X I N YAO JAMES A. ZAGZEBSKI

-Uncertainties in measured attenuation and hackscatter coefficients due to statistical fluctuations in echo signal data from a randomly scattering medium are estimated. The uncertainties are computed for the special case in which a reference phantom is employed to account for transducer and instrumentation factors when measuring attenuation and backscatter coefficients. The resultant uncertaint...

Journal: :Optics express 2010
Changjun Min Georgios Veronis

We theoretically investigate the effect of fabrication-related disorders on subwavelength metal-dielectric-metal plasmonic waveguides. We use a Monte Carlo method to calculate the roughness-induced excess attenuation coefficient with respect to a smooth waveguide. For small roughness height, the excess optical power loss due to disorder is small compared to the material loss in a smooth wavegui...

Journal: :Bio-medical materials and engineering 2014
Xingsong Li Yinhui Deng Jinhua Yu Yuanyuan Wang Vijay Shamdasani

Backscatter and attenuation parameters are not easily measured in clinical applications due to tissue inhomogeneity in the region of interest (ROI). A least squares method(LSM) that fits the echo signal power spectra from a ROI to a 3-parameter tissue model was used to get attenuation coefficient imaging in fatty liver. Since fat's attenuation value is higher than normal liver parenchyma, a rea...

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