The multispectral gas radiation modeling: A new theoretical framework based on a multidimensional approach to k-distribution methods

2014 ◽  
Vol 147 ◽  
pp. 178-195 ◽  
Author(s):  
Frédéric André ◽  
Longfeng Hou ◽  
Maxime Roger ◽  
Rodolphe Vaillon
Keyword(s):  
Theoretical Framework ◽  
Multidimensional Approach ◽  
Gas Radiation ◽  
Radiation Modeling

Application of the Multi-Spectral Correlated-k Distribution Model to Multi-Dimensional Rectangular Enclosure Gas Radiation Calculations

2021 ◽  
Vol 16 (3) ◽  
pp. 479-493
Author(s):  
Longfeng Hou
Keyword(s):  
Industrial Applications ◽  
Distribution Model ◽  
Scaling Functions ◽  
Test Cases ◽  
Multidimensional Approach ◽  
Spectral Absorption ◽  
Gas Radiation ◽  
Gaseous Media ◽  
Radiation Modeling ◽  
Approximate Treatment

The Multi-Spectral Correlated-k distribution model (MSCk) is an amelioration of the widely used Ck model. In the MSCk model, the breakdown of correlation assumption used in the original Ck model for non-uniform media is overcome by introducing the clustering of scaling functions. The principle of MSCk model is to group together wavenumbers with respect to the spectral scaling functions—defined as the ratio between spectral absorption coefficients in distinct states—so that the correlation assumption can be considered as exact over the corresponding intervals of wavenumbers. Until now, validations of the MSCk model in 0D and 1D test cases have already been performed in the previous work (Andre, F., Hou, L., Roger, M. and Vaillon, R., 2014. The multispectral gas radiation modeling: A new theoretical framework based on a multidimensional approach to k-distribution methods. Journal of Quantitative Spectroscopy and Radiative Transfer, 147, pp.178–195; Andre, F., Hou, L. and Solovjov, V.P., 2016. An Exact Formulation of k-Distribution Methods in Non-Uniform Gaseous Media and its Approximate Treatment Within the Multi-Spectral Framework. Journal of Physics: Conference Series, 676(1)). However, its application to multi-dimensional configurations (much closer to industrial applications) has not been conducted. Accordingly, in the present paper, we focus our attention on the application of the MSCk model to Multi-dimensional calculations.

scholarly journals CFD ANALYSIS OF PULVERIZED COAL COMBUSTION IN A BLAST FURNACE TUYERE: COMPARISON BETWEEN WSGG AND GG MODELS FOR RADIATION MODELING

2016 ◽  
Vol 15 (2) ◽  
pp. 60
Author(s):  
C. V. Da Silva ◽  
G. Weber ◽  
F. R. Centeno ◽  
F. H. R. França
Keyword(s):  
Blast Furnace ◽  
Radiation Heat Transfer ◽  
Pulverized Coal ◽  
Operating Conditions ◽  
Base Case ◽  
Combustion Gases ◽  
Gas Radiation ◽  
Spectral Models ◽  
Industrial Operations ◽  
Radiation Modeling

Combustion processes are being employed for many years, and remains a major source of energy for industrial operations through the conversion of chemical energy in thermal energy, besides being usually accompanied by formation of pollutants. This work presents a numerical investigation using the software Ansys CFX to model the process of combustion of pulverized coal injected into a blast furnace for production of pig iron making a comparison between WSGG and GG spectral models for gas radiation aim to verify the influence on the radiation heat transfer and the temperature field. Since global coal reserves are being constantly reduced, new techniques using coal are being studied. Among some effective techniques, there is the injection of pulverized coal through a tuyere installed at the bottom of the blast furnace. Thus, among the objectives of this work is to obtain information about the pulverized coal burning process injected. Firstly, it will be employed a North American coal as a base case in order to better understand the involved phenomena. Simulations were made using the actual operating conditions of a blast furnace, which uses atmospheric air enriched with oxygen for burning the coal. The same boundary conditions and operation of other investigations were considered in order to validate the model developed for this work, and so that it can be applied in similar situations, either in assessments or in projects of coal injection systems and combustion in blast furnaces. The results include temperature and velocity fields, oxygen concentration, and the formation of CO and CO2 and they are in agreement with data from literature. Comparing the results of this study with the results obtained in the work (Gu et al., 2010) It observed a qualitative similarity between them and also quantitative. Furthermore, it was found that, in this case, modeling the absorption spectrum of the combustion gases resulting in changes in flame form, but did not significantly alter the magnitude of temperatures, since the walls of the equipment are considered adiabatic.

Radiation Modeling in Oxy-Fuel Combustion Scenarios

2009 ◽  
Author(s):  
Gautham Krishnamoorthy ◽  
Muhammad Sami ◽  
Stefano Orsino ◽  
Anura Perera ◽  
Mehrdad Shahnam ◽  
...  
Keyword(s):  
Fluid Dynamic ◽  
Wide Band ◽  
Full Scale ◽  
Radiative Properties ◽  
Band Model ◽  
Particle Radiation ◽  
Gas Radiation ◽  
Gaseous Media ◽  
Wide Band Model ◽  
Radiation Modeling

Three gray models for the radiative properties of gases were examined for their usage in oxy-combustion simulations of a full scale boiler with flue gas recycle. Fully coupled computational fluid dynamic (CFD) simulations of a full scale boiler were carried out employing the weighted-sum-of-gray-gases model (WSGGM) at air burn, dry-recycle and wet-recycle conditions. The resulting thermal and composition fields were then frozen and the radiative properties of the gaseous media recomputed employing the Exponential Wide Band Model (EWBM) and correlations for total emissivities of gas mixtures. It is shown that when high CO2/H2O ratios were encountered within the boiler such as in dry-recycle scenarios, employing emissivity correlations developed for purely CO2 media within the models can result in incorrect gas properties. The errors associated with this can be significant when there are large pockets within the furnace where the gas radiation dominates the particle radiation.

Gray/nongray gas radiation modeling in steam cracker CFD calculations

AIChE Journal ◽  
2007 ◽  
Vol 53 (7) ◽  
pp. 1658-1669 ◽  
Author(s):  
G. D. Stefanidis ◽  
B. Merci ◽  
G. J. Heynderickx ◽  
G. B. Marin
Keyword(s):  
Gas Radiation ◽  
Steam Cracker ◽  
Radiation Modeling

Mind wandering as data augmentation: How mental travel supports abstraction

2020 ◽  
Vol 43 ◽  
Author(s):  
Myrthe Faber
Keyword(s):  
Machine Learning ◽  
Data Augmentation ◽  
Mental Content ◽  
Mind Wandering ◽  
Theoretical Framework ◽  
Important Addition

Abstract Gilead et al. state that abstraction supports mental travel, and that mental travel critically relies on abstraction. I propose an important addition to this theoretical framework, namely that mental travel might also support abstraction. Specifically, I argue that spontaneous mental travel (mind wandering), much like data augmentation in machine learning, provides variability in mental content and context necessary for abstraction.

Barriers to Physical Activity in Adolescents

2015 ◽  
Vol 23 (2) ◽  
pp. 47-59 ◽  
Author(s):  
Nadine Langguth ◽  
Tanja Könen ◽  
Simone Matulis ◽  
Regina Steil ◽  
Caterina Gawrilow ◽  
...  
Keyword(s):  
Physical Activity ◽  
Leisure Activities ◽  
Outcome Expectations ◽  
Multidimensional Approach ◽  
Factor Analyses ◽  
Physical And Mental Health ◽  
Tailored Interventions ◽  
Long Term Consequences ◽  
Age Range

During adolescence, physical activity (PA) decreases with potentially serious, long-term consequences for physical and mental health. Although barriers have been identified as an important PA correlate in adults, research on adolescents’ PA barriers is lacking. Thus reliable, valid scales to measure adolescents’ PA barriers are needed. We present two studies describing a broad range of PA barriers relevant to adolescents with a multidimensional approach. In Study 1, 124 adolescents (age range = 12 – 24 years) reported their most important PA barriers. Two independent coders categorized those barriers. The most frequent PA barriers were incorporated in a multidimensional questionnaire. In Study 2, 598 adolescents (age range = 13 – 21 years) completed this questionnaire and reported their current PA, intention, self-efficacy, and negative outcome expectations. Seven PA barrier dimensions (leisure activities, lack of motivation, screen-based sedentary behavior, depressed mood, physical health, school workload, and preconditions) were confirmed in factor analyses. A multidimensional approach to measuring PA barriers in adolescents is reliable and valid. The current studies provide the basis for developing individually tailored interventions to increase PA in adolescents.

Adaptive and Maladaptive Neural Plasticity Due to Facial Nerve Palsy

2016 ◽  
Vol 224 (2) ◽  
pp. 102-111 ◽  
Author(s):  
Carsten M. Klingner ◽  
Stefan Brodoehl ◽  
Gerd F. Volk ◽  
Orlando Guntinas-Lichius ◽  
Otto W. Witte
Keyword(s):  
Facial Nerve ◽  
Neural Plasticity ◽  
Cortical Plasticity ◽  
Brain Plasticity ◽  
Motor Nerve ◽  
Predictive Coding ◽  
Theoretical Framework ◽  
Cortical Reorganization ◽  
Nerve Lesion ◽  
Peripheral Facial Palsy

Abstract. This paper reviews adaptive and maladaptive mechanisms of cortical plasticity in patients suffering from peripheral facial palsy. As the peripheral facial nerve is a pure motor nerve, a facial nerve lesion is causing an exclusive deefferentation without deafferentation. We focus on the question of how the investigation of pure deefferentation adds to our current understanding of brain plasticity which derives from studies on learning and studies on brain lesions. The importance of efference and afference as drivers for cortical plasticity is discussed in addition to the crossmodal influence of different competitive sensory inputs. We make the attempt to integrate the experimental findings of the effects of pure deefferentation within the theoretical framework of cortical responses and predictive coding. We show that the available experimental data can be explained within this theoretical framework which also clarifies the necessity for maladaptive plasticity. Finally, we propose rehabilitation approaches for directing cortical reorganization in the appropriate direction and highlight some challenging questions that are yet unexplored in the field.

A Multidimensional Approach to Psychology

1999 ◽  
Vol 44 (3) ◽  
pp. 237-238
Author(s):  
Donald E. Polkinghorne
Keyword(s):  
Multidimensional Approach
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