scholarly journals Optimized Cool Coatings as a Strategy to Improve Urban Equivalent Albedo at Various Latitudes

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1335
Author(s):  
Mattia Manni ◽  
Andrea Nicolini
Keyword(s):  
Monte Carlo ◽  
Optical Properties ◽  
Numerical Model ◽  
Ray Tracing ◽  
Research Study ◽  
Numerical Models ◽  
Winter Season ◽  
Angle Of Incidence ◽  
Mitigation Potential ◽  
Selective Behavior

This research study aimed to investigate the influences of angular-selective retro-reflective (AS-RR) and retro-reflective (RR) materials on the urban equivalent albedo (αeq). Full ray tracing solar analyses were conducted through the Monte Carlo-based numerical model validated in a previous work. Different geometry scenarios with different patterns of urban density were modelled. AS-RR and RR materials were alternately applied to the street and to the most irradiated façade. AS-RR materials were proposed to enhance the αeq of the urban environment particularly during summer. Solar analyses were reiterated for three latitudes (i.e., Oslo, Milan, Cairo). RR pavements and façades were capable of increasing the αeq throughout the year. However, implementing an angular-selective behavior allowed for a reduction of the mitigation potential of RR materials during the winter season. In their best application, RR and AS-RR materials enabled higher αeq in summer (122%) with negligible effects during the winter (7%). Finally, the study highlighted the need for exploiting numerical models capable of conducting full ray tracing solar analyses when investigating materials whose optical properties depend on the angle of incidence of the sunrays (such as RR materials).

The Method Of Quasi-specular Elements To Reduce Stochastic Noise During Illuminance Simulation

2020 ◽  
pp. 39-47
Author(s):  
Sergei V. Ershov ◽  
Dmitry D. Zhdanov ◽  
Alexei G. Voloboy
Keyword(s):  
Monte Carlo ◽  
Distribution Function ◽  
Optical Properties ◽  
Ray Tracing ◽  
Stochastic Noise ◽  
Scattering Function ◽  
Propagation Of Light ◽  
Diffuse Surface ◽  
Natural Criterion ◽  
Specular Objects

When simulating the propagation of light, luminance/ radiance brought by a ray is calculated from the optical properties of the scene objects it interacts with. According to their optical properties, objects can be roughly divided into diffuse and specular. In Monte Carlo ray tracing luminance/radiance is calculated only for diffuse surfaces. When a ray hits a specular a surface, it is reflected (or refracted) until it reaches a diffuse surface, and only then the luminance/radiance is calculated. In the proposed approach, diffuse elements are further divided into genuine diffuse and quasi-specular elements. The most natural criterion for the latter is that it scatters light in a narrow cone about the specular direction. An element of the scene can also be a superposition of both types when its scattering function is a sum of the genuine diffuse and quasi-specular parts. This article shows how different components of illuminance/irradiance interact with quasi-specular objects and describe how this works in the bi-directional stochastic ray tracing. The proposed approach significantly reduces stochastic noise for multiple scenes. This method is also applicable for simulation of volume scattering, treating the phase function of the medium as quasi-specular. In this case, the choice of quasi-specular objects is not based on the nature of the bidirectional scattering distribution function (BSDF): the medium is treated as completely quasi-specular while the surfaces, even if their BSDFs are narrower, remain genuine diffuse. The article shows the advantage of this approach.

scholarly journals An Open-Source Monte Carlo Ray-Tracing Simulation Tool for Luminescent Solar Concentrators with Validation Studies Employing Scattering Phosphor Films

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 455
Author(s):  
Duncan E. Smith ◽  
Michael D. Hughes ◽  
Bhakti Patel ◽  
Diana-Andra Borca-Tasciuc
Keyword(s):  
Monte Carlo ◽  
Ray Tracing ◽  
Validation Studies ◽  
Three Dimensional ◽  
Angle Of Incidence ◽  
Simulation Tool ◽  
Solar Concentrators ◽  
Building Integrated Photovoltaics ◽  
Luminescent Solar Concentrators ◽  
Ray Tracing Simulation

Luminescent solar concentrators enhance the power output of solar cells through wave-guided luminescent emission and have great potential as building-integrated photovoltaics. Luminescent solar concentrators with a variety of geometries and absorbing–emitting materials have been reported in the literature. As the breadth of available experimental configurations continues to grow, there is an increasing need for versatile Monte Carlo ray-tracing simulation tools to analyze the performance of these devices for specific applications. This paper presents the framework for a Monte Carlo ray-tracing simulation tool that can be used to analyze a host of three-dimensional geometries. It incorporates custom radiative transport models to consider the effects of scattering from luminescent media, while simultaneously modeling absorption and luminescent emission. The model is validated using experimental results for three-dimensional planar and wedge-shaped luminescent solar concentrators employing scattering phosphor films. Performance was studied as a function of length, wavelength, and the angle of incidence of incoming light. The data for the validation studies and the code (written using the Python programming language) associated with the described model are publically available.

A Free and Open Source Monte Carlo Ray Tracing Program for Concentrating Solar Energy Research

2010 ◽  
Author(s):  
Jo¨rg Petrasch
Keyword(s):  
Monte Carlo ◽  
Solar Energy ◽  
Open Source ◽  
Ray Tracing ◽  
Modular Design ◽  
Numerical Models ◽  
Solar Furnace ◽  
High Flux ◽  
Energy Research ◽  
Solar Simulator

A free and open source Monte Carlo ray-tracing program for concentrating solar energy research and development is presented. The program uses non energy partitioning Monte Carlo methods to model radiative exchange between arbitrarily arranged surfaces. Surface models include concentrating geometries, such as spherical, parabolic, and elliptical concentrators as well as compound parabolic concentrators. The program’s modular design allows implementation of additional surface and source models. The program has been thoroughly tested and experimentally validated. It has been used to model several concentrating devices including PSI’s high flux solar furnace and ETH’s high flux solar simulator. Furthermore, it has been used to design PSI’s high flux solar simulator and UFL’s high flux solar simulator. The code is particularly suited to provide radiative boundary conditions for numerical models of high temperature solar receivers and solar thermochemical reactors.

Probabilistic multiscale modeling of fracture in heterogeneous materials and structures

2020 ◽  
Vol 86 (7) ◽  
pp. 45-54
Author(s):  
A. M. Lepikhin ◽  
N. A. Makhutov ◽  
Yu. I. Shokin
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Fracture Mechanics ◽  
Multiscale Modeling ◽  
Virtual Work ◽  
Numerical Models ◽  
Heterogeneous Materials ◽  
Heterogeneous Structure ◽  
Generalized Coordinates ◽  
Heterogeneous Structures

The probabilistic aspects of multiscale modeling of the fracture of heterogeneous structures are considered. An approach combining homogenization methods with phenomenological and numerical models of fracture mechanics is proposed to solve the problems of assessing the probabilities of destruction of structurally heterogeneous materials. A model of a generalized heterogeneous structure consisting of heterogeneous materials and regions of different scales containing cracks and crack-like defects is formulated. Linking of scales is carried out using kinematic conditions and multiscale principle of virtual forces. The probability of destruction is formulated as the conditional probability of successive nested fracture events of different scales. Cracks and crack-like defects are considered the main sources of fracture. The distribution of defects is represented in the form of Poisson ensembles. Critical stresses at the tops of cracks are described by the Weibull model. Analytical expressions for the fracture probabilities of multiscale heterogeneous structures with multilevel limit states are obtained. An approach based on a modified Monte Carlo method of statistical modeling is proposed to assess the fracture probabilities taking into account the real morphology of heterogeneous structures. A feature of the proposed method is the use of a three-level fracture scheme with numerical solution of the problems at the micro, meso and macro scales. The main variables are generalized forces of the crack propagation and crack growth resistance. Crack sizes are considered generalized coordinates. To reduce the dimensionality, the problem of fracture mechanics is reformulated into the problem of stability of a heterogeneous structure under load with variations of generalized coordinates and analysis of the virtual work of generalized forces. Expressions for estimating the fracture probabilities using a modified Monte Carlo method for multiscale heterogeneous structures are obtained. The prospects of using the developed approaches to assess the fracture probabilities and address the problems of risk analysis of heterogeneous structures are shown.

scholarly journals Preliminary Results on the Dynamics of a Pile-Moored Fish Cage with Elastic Net in Currents and Waves

2020 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Gianluca Zitti ◽  
Nico Novelli ◽  
Maurizio Brocchini
Keyword(s):  
Numerical Model ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Offshore Structures ◽  
Fish Farm ◽  
Maximum Displacement ◽  
Drag Forces ◽  
Real Size ◽  
Lift And Drag ◽  
Mesh Grid

Over the last decades, the aquaculture sector increased significantly and constantly, moving fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The deformations of the system subjected to currents and waves are studied.

scholarly journals Development of Detailed FE Numerical Models for Assessing the Replacement of Metal with Composite Materials Applied to an Executive Aircraft Wing

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 178
Author(s):  
Valerio Acanfora ◽  
Roberto Petillo ◽  
Salvatore Incognito ◽  
Gerardo Mario Mirra ◽  
Aniello Riccio
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Numerical Model ◽  
Numerical Models ◽  
Structural Performance ◽  
Aircraft Wing ◽  
Resin Infusion ◽  
Effectiveness Analysis ◽  
Liquid Resin Infusion ◽  
Process Constraints

This work provides a feasibility and effectiveness analysis, through numerical investigation, of metal replacement of primary components with composite material for an executive aircraft wing. In particular, benefits and disadvantages of replacing metal, usually adopted to manufacture this structural component, with composite material are explored. To accomplish this task, a detailed FEM numerical model of the composite aircraft wing was deployed by taking into account process constraints related to Liquid Resin Infusion, which was selected as the preferred manufacturing technique to fabricate the wing. We obtained a geometric and material layup definition for the CFRP components of the wing, which demonstrated that the replacement of the metal elements with composite materials did not affect the structural performance and can guarantee a substantial advantage for the structure in terms of weight reduction when compared to the equivalent metallic configuration, even for existing executive wing configurations.

Analysis of a Hybrid PV/T Concept Based on Wavelength Selective Films

2013 ◽  
Author(s):  
Tejas U. Ulavi ◽  
Jane H. Davidson ◽  
Tim Hebrink
Keyword(s):  
Thin Film ◽  
Monte Carlo ◽  
Total Energy ◽  
Ray Tracing ◽  
Solar Spectrum ◽  
Photovoltaic Module ◽  
Optical Performance ◽  
Technical Performance ◽  
Compound Parabolic Concentrator ◽  
Pv Modules

The technical performance of a non-tracking hybrid PV/T concept that uses a wavelength selective film is modeled. The wavelength selective film is coupled with a compound parabolic concentrator to reflect and concentrate the infrared portion of the solar spectrum onto a tubular absorber while transmitting the visible portion of the spectrum to an underlying thin-film photovoltaic module. The optical performance of the CPC/selective film is obtained through Monte Carlo Ray-Tracing. The CPC geometry is optimized for maximum total energy generation for a roof-top application. Applied to a rooftop in Phoenix, Arizona USA, the hybrid PV/T provides 20% more energy compared to a system of the same area with independent solar thermal and PV modules, but the increase is achieved at the expense of a decrease in the electrical efficiency from 8.8% to 5.8%.

Uncertainties evaluations in the ray-tracing algorithm based on Monte Carlo method

2014 ◽  
Author(s):  
Guojin Feng ◽  
Ping Li ◽  
Yingwei He ◽  
Yu Wang ◽  
Houping Wu
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Ray Tracing ◽  
Tracing Algorithm
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