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

1995 ◽  
Vol 117 (2) ◽  
pp. 346-354 ◽  
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.

Comparison of Experiment With Monte Carlo Simulations on a Reflective Gap Using a Detailed Surface Properties Model

1996 ◽  
Vol 118 (2) ◽  
pp. 388-393 ◽  
Author(s):  
J. Zaworski ◽  
J. R. Welty ◽  
B. J. Palmer ◽  
M. K. Drost
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Grazing Angle ◽  
Incident Radiation ◽  
Monte Carlo Code ◽  
Bidirectional Reflectance Distribution Function ◽  
Bidirectional Reflectance ◽  
Detailed Surface ◽  
Bidirectional Reflectance Distribution

The spatial distribution of light through a rectangular gap bounded by highly reflective, diffuse surfaces was measured and compared with the results of Monte Carlo simulations. Incorporating radiant properties for real surfaces into a Monte Carlo code was seen to be a significant problem; a number of techniques for accomplishing this are discussed. Independent results are reported for measured values of the bidirectional reflectance distribution function over incident polar angles from 0 to 90 deg for a semidiffuse surface treatment (Krylon™ flat white spray paint). The inclusion of this information into a Monte Carlo simulation yielded various levels of agreement with experimental results. The poorest agreement occurred when the incident radiation was at a grazing angle with respect to the surface and the reflectance was nearly specular.

Comparison of Monte Carlo and Fuzzy Math Simulation Methods for Quantitative Microbial Risk Assessment

2003 ◽  
Vol 66 (10) ◽  
pp. 1900-1910 ◽  
Author(s):  
VALERIE J. DAVIDSON ◽  
JOANNE RYKS
Keyword(s):  
Risk Assessment ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Interval Arithmetic ◽  
Food Systems ◽  
Probability Distributions ◽  
Economic Cost ◽  
Fuzzy Mathematics ◽  
Quantitative Microbial Risk Assessment ◽  
Mean Values

The objective of food safety risk assessment is to quantify levels of risk for consumers as well as to design improved processing, distribution, and preparation systems that reduce exposure to acceptable limits. Monte Carlo simulation tools have been used to deal with the inherent variability in food systems, but these tools require substantial data for estimates of probability distributions. The objective of this study was to evaluate the use of fuzzy values to represent uncertainty. Fuzzy mathematics and Monte Carlo simulations were compared to analyze the propagation of uncertainty through a number of sequential calculations in two different applications: estimation of biological impacts and economic cost in a general framework and survival of Campylobacter jejuni in a sequence of five poultry processing operations. Estimates of the proportion of a population requiring hospitalization were comparable, but using fuzzy values and interval arithmetic resulted in more conservative estimates of mortality and cost, in terms of the intervals of possible values and mean values, compared to Monte Carlo calculations. In the second application, the two approaches predicted the same reduction in mean concentration (−4 log CFU/ml of rinse), but the limits of the final concentration distribution were wider for the fuzzy estimate (−3.3 to 5.6 log CFU/ml of rinse) compared to the probability estimate (−2.2 to 4.3 log CFU/ml of rinse). Interval arithmetic with fuzzy values considered all possible combinations in calculations and maximum membership grade for each possible result. Consequently, fuzzy results fully included distributions estimated by Monte Carlo simulations but extended to broader limits. When limited data defines probability distributions for all inputs, fuzzy mathematics is a more conservative approach for risk assessment than Monte Carlo simulations.

scholarly journals A Monte-Carlo Simulation of the Behaviour of Electron Swarms in Hydrogen Using an Anisotropic Scattering Model

1978 ◽  
Vol 31 (4) ◽  
pp. 299 ◽  
Author(s):  
HA Blevin ◽  
J Fletcher ◽  
SR Hunter
Keyword(s):  
Experimental Data ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Electron Transport ◽  
Anisotropic Scattering ◽  
Isotropic Scattering ◽  
Transport Parameters ◽  
Simulation Code ◽  
Scattering Model ◽  
Good Agreement

Hunter (1977) found that a Monte-Carlo simulation of electron swarms in hydrogen, based on an isotropic scattering model, produced discrepancies between the predicted and measured electron transport parameters. The present paper shows that, with an anisotropic scattering model, good agreement is obtained between the predicted and experimental data. The simulation code is used here to calculate various parameters which are not directly measurable.

scholarly journals Validation of a Monte Carlo Modelling Based Dosimetry of Extraoral Photobiomodulation

Diagnostics ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2207
Author(s):  
Anna N. Yaroslavsky ◽  
Amy F. Juliano ◽  
Ather Adnan ◽  
Wayne J. Selting ◽  
Tyler W. Iorizzo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Light Emitting Diode ◽  
Morphological Data ◽  
Transmitted Power ◽  
Light Dosimetry ◽  
Mean Values ◽  
Mri Scans ◽  
The Difference

An in vivo validation study was performed to confirm the accuracy of extraoral photobiomodulation therapy (PBMT) dosimetry determined by modelling. The Monte Carlo technique was utilized to calculate the fluence rate and absorbed power of light delivered through multi-layered tissue. Optical properties used during Monte Carlo simulations were taken from the literature. Morphological data of four study volunteers were acquired using magnetic resonance imaging (MRI) scans. Light emitting diode (LED) coupled to a power meter were utilized to measure transmitted power through each volunteer’s cheek, in vivo. The transmitted power determined by Monte Carlo modelling was compared to the in vivo measurements to determine the accuracy of the simulations. Experimental and simulation results were in good agreement for all four subjects. The difference between the mean values of the measured transmission was within 12% from the respective transmission obtained using Monte Carlo simulations. The results of the study indicate that Monte Carlo modelling is a robust and reliable method for light dosimetry.

Size determination of spherical voids from the extrema of the Mie scattering intensities

1976 ◽  
Vol 54 (4) ◽  
pp. 349-352
Author(s):  
A. J. Patitsas ◽  
F. Robillard ◽  
B. H. Kaye
Keyword(s):  
Refractive Index ◽  
Forward Direction ◽  
Incident Radiation ◽  
Mie Scattering ◽  
Size Determination ◽  
Size Parameter ◽  
Spherical Void ◽  
Variable Λ ◽  
Spherical Voids

Simple relations have been obtained, by numerical methods, between the diameter D of a spherical void (bubble) in a conducting medium of a given refractive index and the angular positions of the extrema of the Mie scattering intensities from the voids. The extrema are counted from the forward direction. These relations allow the determination of the positions of the extrema for a given diameter, or the reverse, without computational aids. The real part of the refractive index was varied from 1.25 to 15.00 and the imaginary part from 0.0 to 22.50. The size parameter α = πD/λ was varied in all cases from 4.00 to 24.00. The variable λ represents the wavelength of the incident radiation. These findings could thus be related to the scattering of microwaves by bubbles in water. Similar relations have also been obtained regarding the scattering of scalar waves by spherical voids. This corresponds to scattering of Schrödinger waves from complex spherical barrier potentials.

scholarly journals Optimal Capacity Sizing for the Integration of a Battery and Photovoltaic Microgrid to Supply Auxiliary Services in Substations under a Contingency

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6037
Author(s):  
Alejandra Tabares ◽  
Norberto Martinez ◽  
Lucas Ginez ◽  
José F. Resende ◽  
Nierbeth Brito ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Careful Analysis ◽  
Exhaustive Search ◽  
Solar Irradiation ◽  
Photovoltaic Generation ◽  
Hybrid Microgrid ◽  
Optimal Capacity ◽  
Capacity Sizing ◽  
Auxiliary Services

Auxiliary services are vital for the operation of a substation. If a contingency affects the distribution feeder that provides energy for the auxiliary services, it could lead to the unavailability of the substation’s service. Therefore, backup systems such as diesel generators are used. Another alternative is the adoption of a microgrid with batteries and photovoltaic generation to supply substation auxiliary services during a contingency. Nevertheless, high battery costs and the intermittence of photovoltaic generation requires a careful analysis so the microgrid capacity is defined in a compromise between the investment and the unavailability reduction of auxiliary services. This paper proposes a method for the capacity sizing of a microgrid with batteries, photovoltaic generation, and bidirectional inverters to supply auxiliary services in substations under a contingency. A set of alternatives is assessed through exhaustive search and Monte Carlo simulations to cater for uncertainties of contingencies and variation of solar irradiation. An unavailability index is proposed to measure the contribution of the integrated hybrid microgrid to reduce the time that the substation is not in operation. Simulations carried out showed that the proposed method identifies the microgrid capacity with the lowest investment that satisfies a goal for the unavailability of the substation service.

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