نتایج جستجو برای: linear attenuation coefficient

تعداد نتایج: 671039  

Journal: :Applied optics 2006
Stephen G Warren Richard E Brandt Thomas C Grenfell

Snow is a scattering-dominated medium whose scattering is independent of wavelength at 350-600 nm. The attenuation of solar radiation in snow can be used to infer the spectral absorption coefficient of pure ice, by reference to a known value at 600 nm. The method is applied to clean Antarctic snow; the absorption minimum is at 390 nm, and the inferred absorption coefficient is lower than even t...

Journal: :Biomedical optics express 2015
Melissa M Eberle Mike S Hsu Carissa L Rodriguez Jenny I Szu Michael C Oliveira Devin K Binder B Hyle Park

Optical coherence tomography (OCT) is a high resolution, minimally invasive imaging technique, which can produce depth-resolved cross-sectional images. In this study, OCT was used to detect changes in the optical properties of cortical tissue in vivo in mice during the induction of global (pentylenetetrazol) and focal (4-aminopyridine) seizures. Through the use of a confidence interval statisti...

2013
Seon Young Yoo Yookyung Kim Hyun Hae Cho Mi Joo Choi Sung Shine Shim Jeong Kyong Lee Seung Yon Baek

OBJECTIVE To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. MATERIALS AND METHODS A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced ...

Journal: :Optics express 2004
Dirk Faber Freek van der Meer Maurice Aalders Ton van Leeuwen

From calibrated, weakly scattering tissue phantoms (2-6 mm-1), we extract the attenuation coefficient with an accuracy of 0.8 mm-1 from OCT data in the clinically relevant 'fixed focus' geometry. The data are analyzed using a single scattering model and a recently developed description of the confocal point spread function (PSF). We verify the validity of the single scattering model by a quanti...

Journal: :SIAM J. Control and Optimization 2006
Ji-Woong Lee Geir E. Dullerud

An exact condition for uniform stabilization and disturbance attenuation for switched linear systems is given in the discrete-time domain via the union of an increasing family of linear matrix inequality conditions. Associated with each Markovian jump linear system is a switched linear system, so we obtain a necessary and sufficient condition for almost sure uniform stabilization and disturbanc...

2014
R. R. GUPTA

Rayleigh waves in a half-space exhibiting microplar transversely isotropic generalized thermoelastic properties based on the Lord-Shulman (L-S), Green and Lindsay (G-L) and Coupled thermoelasticty (C-T) theories are discussed. The phase velocity and attenuation coefficient in the previous three different theories have been obtained. A comparison is carried out of the phase velocity, attenuation...

Journal: :International journal of engineering technology and management sciences 2023

The linear attenuation coefficient (LAC) and mass (MAC) are most important while studying of radiation, radio-isotopes in dosimentry irradiation materials. In the present work to calculate values different salts samples by using Gamma-ray spectrometry with Photo-Multiplier Tube (PMT) Multi-Channel Analyzer (MCA). 0.123, 0.511, 0.662, 1.17, 1.28 1.33MeV gamma energy rays used for experiment inte...

2017

Energy dissipation during wave propagation in fragmented geomaterials can be caused by independent movement of fragments leading to energy loss on their impact. By considering a pair of impacting fragments at times much greater than the period of their oscillations we show that at large time scale, the dynamics of the pair can be described by a linear viscous model with damping coefficient expr...

2007
Paul W. Jewell

A linear, three-component (nitrate, phytoplankton, and zooplankton) biogeochemical model coupled to a one-dimensional turbulence closure fluid dynamic model successfully reproduces most of the thermal and biogeochemical features of three marine settings (Bermuda Station "S" in the oligotrophic portion of the North Atlantic subtropical gyre, Ocean Weather Station "India" in the North Atlantic su...

Journal: :Ultrasonics 2007
Leigh-Ann Orr Anthony J Mulholland Richard L O'Leary Agnes Parr Richard A Pethrick Gordon Hayward

The large number of degrees of freedom in the design of piezoelectric transducers requires a theoretical model that is computationally efficient so that a large number of iterations can be performed in the design optimisation. The materials used are often lossy, and indeed loss can be used to enhance the operational characteristics of these designs. Motivated by these needs, this paper extends ...

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