scholarly journals Application of the ADO method on disadvantage-factor calculation for heterogeneous slab cells considering linear anisotropic scattering effects

2017 ◽  
Vol 13 (4) ◽  
Author(s):  
João Francisco Prolo Filho ◽  
Marco Paulsen Rodrigues
2019 ◽  
Vol 18 (1) ◽  
pp. 92
Author(s):  
D. L. Ribeiro ◽  
M. P. Rodrigues ◽  
J. F. Prolo Filho

In this work, the Analytical Discrete Ordinate method (ADO method) is used to solve deep-penetration transport problems in one-dimensional Cartesian geometry, subject to isotropic and linear anisotropic scattering effects. The regime is considered permanent, the media are homogeneous, and the fluxes are caused by sources located on the boundaries of the domain. In addition, the energy fluctuations will be considered as not significant, characterizing the phenomena as monoenergetic problems. In order to validate the code, method and provide benchmark results, some test problems will be treated and results will be discussed. In particular, the ADO method generated fairly accurate results when compared to other methods based on SN approaches, at a relatively low computational cost.


2019 ◽  
Vol 15 (4) ◽  
Author(s):  
Dalvana Lopes Ribeiro ◽  
João Francisco Prolo Filho

In this work, a discrete ordinates solution for a neutron transport problem in one-dimensional Cartesian geometry is presented. In order to evaluate the efficiency of the half-range quadrature scheme, the Analytical Discrete Ordinates method (ADO) is used to solve two classes of problems in finite and homogeneous media (with isotropic and linear anisotropic scattering), for steady-state regime, without inner source and prescribed boundary conditions. Numerical results for the scalar fluxes were obtained and comparisons with other works in the literature were made. The versatility of the use of quadratures has always been seen as an advantage of the ADO method which, besides providing accurate results at a low computational cost, has a simpler approach, allowing the use of free software distribution for the simulations. In the results analysis, it was verified that the use of the half-range quadrature was able to accelerate the convergence, mainly in linearly anisotropic problems.


Author(s):  
K. J. Daun ◽  
K. A. Thomson ◽  
F. Liu

Laser-induced incandescence (LII) measurements carried out on aerosols having a large particle volume fraction must be corrected for extinction between the energized aerosol particles and the detector, called signal trapping. While standard correction techniques have been developed for signal trapping by absorption, signal trapping due to scattering requires further investigation, particularly the case of highly anisotropic scattering. This paper examines this effect in an aerosol containing highly-aggregated soot particles by simulating LII signals using a backwards Monte Carlo analysis; the signals are then used to recover a pyrometric beam temperature and soot volume fraction. The results show that in-scattered radiation is a substantial component of the LII signal under high soot loading conditions, which can strongly influence the properties derived from these measurements. Correction techniques based on Bourguer’s law are shown to be effective in mitigating the effect of scatter on the LII signals.


Author(s):  
Kenneth H. Downing ◽  
Hu Meisheng ◽  
Hans-Rudolf Went ◽  
Michael A. O'Keefe

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.


Author(s):  
B. B. Chang ◽  
D. F. Parsons

The significance of dynamical scattering effects remains the major question in the structural analysis by electron diffraction of protein crystals preserved in the hydrated state. In the few cases (single layers of purple membrane and 400-600 Å thick catalase crystals examined at 100 kV acceleration voltage) where electron-diffraction patterns were used quantitatively, dynamical scattering effects were considered unimportant on the basis of a comparison with x-ray intensities. The kinematical treatment is usually justified by the thinness of the crystal. A theoretical investigation by Ho et al. using Cowley-Moodie multislice formulation of dynamical scattering theory and cytochrome b5as the test object2 suggests that kinematical analysis of electron diffraction data with 100-keV electrons would not likely be valid for specimen thickness of 300 Å or more. We have chosen to work with electron diffraction patterns obtained from actual wet protein crystals (rat hemoglobin crystals of thickness range 1000 to 2500 Å) at 200 and 1000 kV and to analyze these for dynamical effects.


1986 ◽  
Vol 47 (C8) ◽  
pp. C8-589-C8-592
Author(s):  
N. BINSTED ◽  
S. L. COOK ◽  
J. EVANS ◽  
R. J. PRICE ◽  
G. N. GREAVES

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