Radiative transfer in a Solar CPC Photoreactor using the First-Order Scattering Method

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Patricio J. Valades-Pelayo ◽  
Manuel A. Ramirez-Cabrera
Keyword(s):  
Monte Carlo ◽  
Graphene Oxide ◽  
Radiation Transfer ◽  
Scattering Method ◽  
First Order ◽  
Statistical Fluctuations ◽  
Parabolic Collector ◽  
Photocatalytic Applications ◽  
Very High ◽  
Statistical Noise

Abstract This manuscript analyzes the suitability of a recently proposed numerical method, the First-Order Scattering Method (FOS), to describe radiation transfer in a Solar Compound Parabolic Collector Photoreactor (CPCP). The study considers five different irradiance conditions ranging from fully diffuse to fully direct solar radiation, with 90 and 45° angled rays. Three photocatalysts at different loadings were considered: Evonik P25, Graphene Oxide, and Goethite, selected due to (1) their relevance in photocatalytic applications and (2) the availability of optical transport properties in the open literature. The study shows that the method is efficient and free of statistical noise, while its accuracy is not affected by the boundary condition’s complexity. The method’s accuracy is very high for photocatalysts with low to moderate albedos, such as Goethite and Graphene Oxide, displaying Normalized Absoluted Mean Error below 3%, i.e., comparable to the Monte Carlo (MC) Method’s statistical fluctuations.

Monte Carlo Algorithms for Moments of Transition Arrays

1988 ◽  
Vol 102 ◽  
pp. 79-81
Author(s):  
A. Goldberg ◽  
S.D. Bloom
Keyword(s):  
Monte Carlo ◽  
State Vector ◽  
Basis Vector ◽  
Collective State ◽  
Dispersion Characteristics ◽  
Dipole Strength ◽  
The Third ◽  
Monte Carlo Algorithms ◽  
Third Moment ◽  
Very High

AbstractClosed expressions for the first, second, and (in some cases) the third moment of atomic transition arrays now exist. Recently a method has been developed for getting to very high moments (up to the 12th and beyond) in cases where a “collective” state-vector (i.e. a state-vector containing the entire electric dipole strength) can be created from each eigenstate in the parent configuration. Both of these approaches give exact results. Herein we describe astatistical(or Monte Carlo) approach which requires onlyonerepresentative state-vector |RV> for the entire parent manifold to get estimates of transition moments of high order. The representation is achieved through the random amplitudes associated with each basis vector making up |RV>. This also gives rise to the dispersion characterizing the method, which has been applied to a system (in the M shell) with≈250,000 lines where we have calculated up to the 5th moment. It turns out that the dispersion in the moments decreases with the size of the manifold, making its application to very big systems statistically advantageous. A discussion of the method and these dispersion characteristics will be presented.

Nappes d'huile: prediction de leurs deplacements comme agent efficace d'un plan de mesure d'urgence

1979 ◽  
Vol 14 (1) ◽  
pp. 89-109
Author(s):  
B. Coupal ◽  
M. de Broissia
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Finite Elements ◽  
Mass Balance ◽  
Stochastic Method ◽  
Stochastic Methods ◽  
Deterministic Approach ◽  
First Order ◽  
The Third ◽  
Comme Agent

Abstract The movement of oil slicks on open waters has been predicted, using both deterministic and stochastic methods. The first method, named slick rose, consists in locating an area specifying the position of the slick during the first hours after the spill. The second method combines a deterministic approach for the simulation of current parameters to a stochastic method simulating the wind parameters. A Markov chain of the first order followed by a Monte Carlo approach enables the simulation of both phenomena. The third method presented in this paper describes a mass balance on the spilt oil, solved by the method of finite elements. The three methods are complementary to each other and constitute an important point for a contingency plan.

scholarly journals Observational manifestations of ‘cosmological dinosaurs’ at redshifts z ∼ 20

2021 ◽  
Vol 503 (2) ◽  
pp. 3081-3088
Author(s):  
V K Dubrovich ◽  
Yu N Eroshenko ◽  
S I Grachev
Keyword(s):  
Black Hole ◽  
Atomic Hydrogen ◽  
Radiation Transfer ◽  
Ring Width ◽  
High Mass ◽  
Primordial Black Hole ◽  
Array Type ◽  
Local Sources ◽  
Order Of Magnitude ◽  
Very High

ABSTRACT We consider a primordial black hole of very high mass, $10^9\!-\!10^{10}\, \mathrm{M}_\odot$, surrounded by the dark matter and bayonic halo at redshifts z ∼ 20 without any local sources of energy release. Such heavy and concentrated objects in the early Universe were previously called ‘cosmological dinosaurs’. Spectral distribution and spatial variation of the brightness in the 21-cm line of atomic hydrogen are calculated with the theory of radiation transfer. It is shown that a narrow and deep absorption arises in the form of the spherical shell around the primordial black hole at the certain radius. The parameters of this shell depend almost exclusively on the mass of the black hole. The angular diameter 18 arcsec of the absorption ring at z ∼ 20 is well within the current technical possibilities of the Square Kilometre Array type telescopes. But the observation of the ring width itself requires an order of magnitude better resolution.

scholarly journals Dynamical model for social distancing in the U.S. during the COVID-19 epidemic

2020 ◽  
Vol 8 (1) ◽  
pp. 141-149
Author(s):  
Shirish M. Chitanvis
Keyword(s):  
New York ◽  
Monte Carlo ◽  
Temporal Evolution ◽  
Social Experiment ◽  
Social Distancing ◽  
Back Testing ◽  
Moderate Growth ◽  
Log Normal ◽  
Very High ◽  
The U.S

AbstractBackground Social distancing has led to a “flattening of the curve” in many states across the U.S. This is part of a novel, massive, global social experiment which has served to mitigate the COVID-19 pandemic in the absence of a vaccine or effective anti-viral drugs. Hence it is important to be able to forecast hospitalizations reasonably accurately.Methods We propose on phenomenological grounds a random walk/generalized diffusion equation which incorporates the effect of social distancing to describe the temporal evolution of the probability of having a given number of hospitalizations. The probability density function is log-normal in the number of hospitalizations, which is useful in describing pandemics where the number of hospitalizations is very high.Findings We used this insight and data to make forecasts for states using Monte Carlo methods. Back testing validates our approach, which yields good results about a week into the future. States are beginning to reopen at the time of submission of this paper and our forecasts indicate possible precursors of increased hospitalizations. However, the trends we forecast for hospitalizations as well as infections thus far show moderate growth.Additionally we studied the reproducibility Ro in New York (Italian strain) and California (Wuhan strain). We find that even if there is a difference in the transmission of the two strains, social distancing has been able to control the progression of COVID 19.

An Equilibrium Prediction Method for Control and Fault Detection of Energy Systems

2021 ◽  
Author(s):  
Austin Rogers ◽  
Fangzhou Guo ◽  
Bryan Rasmussen
Keyword(s):  
Monte Carlo ◽  
Fault Detection ◽  
Monte Carlo Simulations ◽  
Case Studies ◽  
Air Conditioning ◽  
Prediction Method ◽  
Worker Safety ◽  
Static System ◽  
Control Logic ◽  
First Order

Abstract Many fault detection, optimization, and control logic methods rely on sensor feedback that assumes the system is operating at steady state conditions, despite persistent transient disturbances. While filtering and signal processing techniques can eliminate some transient effects, this paper proposes an equilibrium prediction method for first order dynamic systems using an exponential regression. This method is particularly valuable for many commercial and industrial energy system, whose dynamics are dominated by first order thermo-fluid effects. To illustrate the basic advantages of the proposed approach, Monte Carlo simulations are used. This is followed by three distinct experimental case studies to demonstrate the practical efficacy of the proposed method. First, the ability to predict the carbon dioxide level in classrooms allows for energy efficient control of the ventilation system and ensures occupant comfort. Second, predicting the optimal time to end the cool-down of an industrial sintering furnace allows for maximum part throughput and worker safety. Finally, fault detection and diagnosis methods for air conditioning systems typically use static system models; however, the transient response of many air conditioning signals may be approximated as first order, and therefore, the prediction model enables the use of static fault detection methods with transient data. In this paper, the equilibrium prediction method's performance will be quantified using both Monte Carlo simulations and case studies.

High magnetic field NMR investigation of the spin density wave phase of TMTSF2PF6

2002 ◽  
Vol 12 (9) ◽  
pp. 389-389
Author(s):  
W. G. Clark ◽  
F. Zamborsky ◽  
B. Alavi ◽  
P. Vonlanthen ◽  
W. Moulton ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Proton Relaxation ◽  
High Magnetic Fields ◽  
Organic Conductor ◽  
First Order ◽  
The Magnetic Field ◽  
Very High

We report proton NMR measurements of the effect of very high magnetic fields up to 44.7 T (1.9 GHz) on the spin density wave (SDW) transition of the organic conductor TMTSF2PF6. Up to 1.8 GHz, no effect of critical slowing close to the transition is seen on the proton relaxation rate (1/T1), which is determined by the SDW fluctuations associated with the phase transition at the NMR frequency. Thus, the correlation time for such fluctuations is less than $1O^{-10}$s. A possible explanation for the absence of longer correlation times is that the transition is weakly first order, so that the full critical divergence is never achieved. The measurements also show a dependence of the transition temperature on the orientation of the magnetic field and a quadratic dependence on its magnitude that agrees with earlier transport measurements at lower fields. The UCLA part of this work was supported by NSF Grant DMR-0072524.

Sunlight assisted degradation of dye molecules and reduction of toxic Cr(vi) in aqueous medium using magnetically recoverable Fe3O4/reduced graphene oxide nanocomposite

RSC Advances ◽  
2016 ◽  
Vol 6 (13) ◽  
pp. 11049-11063 ◽  
Author(s):  
Purna K. Boruah ◽  
Priyakshree Borthakur ◽  
Gitashree Darabdhara ◽  
Chaitanya K. Kamaja ◽  
Indrapal Karbhal ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Aqueous Medium ◽  
Reduced Graphene Oxide ◽  
Dye Molecules ◽  
Reduced Graphene ◽  
Magnetically Recoverable Catalysts ◽  
Recoverable Catalysts ◽  
Photocatalytic Applications

In view of the significant impact of magnetically recoverable catalysts in photocatalytic applications, Fe3O4/rGO nanocomposite photocatalyst was synthesized and utilized as an efficient photocatalyst for the degradation of dye molecules and reduction of the toxic Cr(vi).

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