Monte Carlo simulations of the growth and decay of quasi-ballistic photon fractions with depth in an isotropic scattering medium

Nonisothermal Nongray Absorbing-Emitting-Scattering Suspension of Fe3O4 Particles Under Concentrated Solar Irradiation

Journal of Heat Transfer ◽

10.1115/1.2822528 ◽

1995 ◽

Vol 117 (2) ◽

pp. 346-354 ◽

Cited By ~ 23

Author(s):

D. Mischler ◽

A. Steinfeld

Keyword(s):

Monte Carlo ◽

Incident Radiation ◽

Mie Scattering ◽

Solar Irradiation ◽

Isotropic Scattering ◽

Cumulative Probability ◽

Scattering Medium ◽

Mean Values ◽

Magnetite Fe3o4 ◽

Temperature Solution

Radiation transfer within a cloud of magnetite (Fe3O4) particles contained in an infinite slab is considered. The particulate cloud is modeled as a pseudo-continuous, nongray, nonisothermal, absorbing, emitting, and anisotropically scattering medium. The energy source is concentrated solar irradiation, which is assumed to be diffusely and uniformly distributed over a circular opening and has a 5780 K blackbody spectrum. Mie-scattering theory is applied to calculate the spectrally and directionally dependent optical properties of the particles. The Monte Carlo ray-tracing method is used to calculate the attenuation characteristics of the cloud and the temperature distribution under radiative equilibrium. The Monte Carlo simulation is optimized by incorporating the appropriate cumulative probability density functions via Bezier surfaces. The effect of spectral and directional dependency is investigated by comparing the results with those obtained for a gray and isotropic-scattering medium under diffuse or perpendicular incident radiation. It is found that a cloud of Mie-scattering Fe3O4 particles under perpendicular incident radiation requires approximately twice as much optical thickness to obtain the same attenuation (of radiation at all wavelengths and directions) as a cloud of isotropic-scattering particles under diffuse incident radiation. It is demonstrated that the gray approximation using Planck mean values can lead to considerable error in the temperature solution because the spectral absorption coefficient is higher in the region of longer wavelengths where the peak emission by Fe3O4 particles occurs.

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Femtosecond pulse propagation in biotissue-like scattering medium: theoretical analysis versus Monte Carlo simulations

10.1117/12.740604 ◽

2007 ◽

Author(s):

Ekaterina A. Sergeeva ◽

Mikhail Yu. Kirillin ◽

Alexander V. Priezzhev

Keyword(s):

Monte Carlo ◽

Theoretical Analysis ◽

Monte Carlo Simulations ◽

Femtosecond Pulse ◽

Pulse Propagation ◽

Scattering Medium

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Low-voltage EDS of magnesium ferrite Dendrites in a FEG-SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164854 ◽

1996 ◽

Vol 54 ◽

pp. 478-479

Author(s):

Matthew T. Johnson ◽

Ian M. Anderson ◽

Jim Bentley ◽

C. Barry Carter

Keyword(s):

Monte Carlo ◽

Quantitative Analysis ◽

Monte Carlo Simulations ◽

Cross Section ◽

Spatial Resolution ◽

Low Voltage ◽

Magnesium Ferrite ◽

X Ray ◽

Interaction Volume ◽

Ferrite Spinel

Energy-dispersive X-ray spectrometry (EDS) performed at low (≤ 5 kV) accelerating voltages in the SEM has the potential for providing quantitative microanalytical information with a spatial resolution of ∼100 nm. In the present work, EDS analyses were performed on magnesium ferrite spinel [(MgxFe1−x)Fe2O4] dendrites embedded in a MgO matrix, as shown in Fig. 1. spatial resolution of X-ray microanalysis at conventional accelerating voltages is insufficient for the quantitative analysis of these dendrites, which have widths of the order of a few hundred nanometers, without deconvolution of contributions from the MgO matrix. However, Monte Carlo simulations indicate that the interaction volume for MgFe2O4 is ∼150 nm at 3 kV accelerating voltage and therefore sufficient to analyze the dendrites without matrix contributions.Single-crystal {001}-oriented MgO was reacted with hematite (Fe2O3) powder for 6 h at 1450°C in air and furnace cooled. The specimen was then cleaved to expose a clean cross-section suitable for microanalysis.

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