نتایج جستجو برای: mass attenuation coefficient

تعداد نتایج: 679612  

2016
Mianmian Dong

To solve noises affecting the performance of laser communication system problems, this paper studies mathematical model in atmospheric attenuation condition, sets up atmospheric attenuation coefficient of the primary factor aerosol (haze) according to the absorbing and scattering characteristics of the atmosphere, gives output SNR(Signal to Noise Ratio) models under atmosphere attenuation based...

Journal: :The Journal of the Acoustical Society of America 1988
K J Parker T A Tuthill R B Baggs

The excess ultrasonic attenuation caused by adding glycogen and inorganic phosphate to liver homogenates has been studied to determine the underlying differences between attenuation coefficients of normal and diffusely diseased livers. Results show that glycogen has a higher than average specific absorption coefficient compared to other large molecular weight biomolecules. Since the glycogen co...

2013
K. Goebbels

Ultrasonic backscattering measurements by means of spatial averaging technique were carried out in steel to determine the ultrasonic attenuation coefficient. The attenuation coefficients were evaluated from the exponential decay of the backscattering signal. The results were compared with those obtained by evaluating the amplitude decay of the main pulse. Good agreement is observed provided the...

Journal: :Applied optics 1999
K Mitra J H Churnside

We estimate the optical signal for an oceanographic lidar from the one-dimensional transient (time-dependent) radiative transfer equation using the discrete ordinates method. An oceanographic lidar directs a pulsed blue or green laser into the ocean and measures the time-dependent backscattered light. A large number of parameters affect the performance of such a system. Here the optical signal ...

Journal: :Ultrasonics 2011
Eenas Omari Heichang Lee Tomy Varghese

Quantitative ultrasound features such as the attenuation slope, sound speed and scatterer size, have been utilized to evaluate pathological variations in soft tissues such as the liver and breast. However, the impact of variations in the sound speed and backscatter due to underlying fat content or fibrotic changes, on the attenuation slope has not been addressed. Both numerical and acoustically...

2009
Björn J. Heismann Michael Balda

In this paper we describe and evaluate an image-based spectral CT method. Its central formula expresses measured CT data as a spectral integration of the spectral attenuation coefficient multiplied by a Local Weighting Function (LWF). The LWF represents the local energy weighting in the image domain, taking into account the system and reconstruction properties and the object self attenuation. A...

Journal: :Indian journal of experimental biology 2003
Susamma Chacko D Kumar Megha Singh

A procedure for non-invasive imaging of the optical attenuation coefficient variation of in vivo thick organs/tissues is developed. The laser back-scattered surface profiles at various locations of human forearm, by multi-probe reflectometer, are measured. These profiles are matched by iterative procedure, with that as obtained by Monte Carlo simulation and the corresponding values of attenuati...

Journal: :International Journal of Biomedical Imaging 2008
Paul Dan Popescu Michael G. Sowa

A direct method for the measurement of the optical attenuation coefficient and the scattering anisotropy parameter based on applying the extended Huygens-Fresnel principle to optical coherence tomography images of blood is demonstrated. The images are acquired with a low-power probing beam at the wavelength of 1300 nm. Values of 12.15 mm(-1) and 0.95 are found for the total attenuation coeffici...

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