A theory of the depolarization of light scattered by a dense medium

1957 ◽  
Vol 53 ◽  
pp. 884 ◽  
Author(s):  
A. D. Buckingham ◽  
M. J. Stephen
Keyword(s):  
Dense Medium ◽  
Depolarization Of Light

scholarly journals Modeling metallurgical responses of coal Tri-Flo separators by a novel BNN: a “Conscious-Lab” development

2021 ◽  
Author(s):  
Mehdi Alidokht ◽  
Samaneh Yazdani ◽  
Esmaeil Hadavandi ◽  
Saeed Chehreh Chelgani
Keyword(s):  
Laboratory Experiments ◽  
Scaling Up ◽  
Dense Medium ◽  
Support Vector ◽  
Coal Processing ◽  
Separation Device ◽  
Modeling Methods ◽  
Machine Learning Methods ◽  
Coal Washery ◽  
First Time

AbstractTri-flo cyclone, as a dense-medium separation device, is one of the most typical environmentally friendly industrial techniques in the coal washery plants. Surprisingly, no detailed investigation has been conducted to explore the effectiveness of tri-flo cyclone operating parameters on their representative metallurgical responses (yield and recovery). To fill this gap, this work for the first time in the coal processing sector is going to introduce a type of advanced intelligent method (boosted-neural network “BNN”) which is able to linearly and nonlinearly assess multivariable correlations among all variables, rank them based on their effectiveness and model their produced responses. These assessments and modeling were considered a new concept called “Conscious Laboratory (CL)”. CL can markedly decrease the number of laboratory experiments, reduce cost, save time, remove scaling up risks, expand maintaining processes, and significantly improve our knowledge about the modeled system. In this study, a robust monitoring database from the Tabas coal plant was prepared to cover various conditions for building a CL for coal tri-flo separators. Well-known machine learning methods, random forest, and support vector regression were developed to validate BNN outcomes. The comparisons indicated the accuracy and strength of BNN over the examined traditional modeling methods. In a sentence, generating a novel BNN within the CL concept can apply in various energy and coal processing areas, fill gaps in our knowledge about possible interactions, and open a new window for plants' fully automotive process.

Enrichment of a Nigerian chromite ore for metallurgical application by dense medium flotation and magnetic separation

2019 ◽  
Vol 116 (3) ◽  
pp. 324 ◽  
Author(s):  
Kuranga Ibrahim Ayinla ◽  
Alafara Abdullahi Baba ◽  
Bankim Chandra Tripathy ◽  
Malay Kumar Ghosh ◽  
Rajan Kumar Dwari ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Separation ◽  
Organic Liquid ◽  
Size Fraction ◽  
Dense Medium ◽  
Chromium Alloy ◽  
Magnetic Separator ◽  
Electro Deposition ◽  
Chromite Ore ◽  
Wet Chemical

This study, focused on the beneficiation of a Nigerian complex chromite ore sourced from Tunga-Kaduka, Anka Local Government of Zamfara State, Nigeria, assaying 45.85% Cr2O4 and 54.15% mineral impurities, was enriched concurrently through sink floatation and magnetic separation techniques. The chromite ore initially analyzed to contain silicate impurities was found not suitable for metallurgical purposes. Thus, enrichment was examined through gravity separation studies using organic liquid with different specific gravities at 2.8, 3.3, and 4.0. The separation of chromite ore with lowest particle size fraction was done using Mozley mineral separator followed by the magnetic separation of the sink product by magnetic separator. The results obtained revealed about 77% of the total material containing 300 μm particle size, 52% ˂ 212 μm and 17% below 75 μm. Subsequent analysis of the beneficiated ore was carried out by wet chemical analysis and atomic absorption spectrophotometer. The results showed that Cr2O4 content increased to 78.34% from initial 45.83% with maximum Cr:Fe ratio of 3.2:1, representing 84.27% of chromium metal present in the ore. The enrichment of Cr2O4 obtained in this study could be found metallurgically applicable in the electro-deposition and ferro-chromium alloy production practices.

scholarly journals Causality and stability conditions of a conformal charged fluid

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Farid Taghinavaz
Keyword(s):  
Chemical Potential ◽  
Second Law Of Thermodynamics ◽  
Dense Medium ◽  
Wave Number ◽  
Second Law ◽  
Stability Conditions ◽  
Charged Fluid ◽  
Large Wave ◽  
The Stability ◽  
Large Wave Number

Abstract In this paper, I study the conditions imposed on a normal charged fluid so that the causality and stability criteria hold for this fluid. I adopt the newly developed General Frame (GF) notion in the relativistic hydrodynamics framework which states that hydrodynamic frames have to be fixed after applying the stability and causality conditions. To do this, I take a charged conformal matter in the flat and 3 + 1 dimension to analyze better these conditions. The causality condition is applied by looking to the asymptotic velocity of sound hydro modes at the large wave number limit and stability conditions are imposed by looking to the imaginary parts of hydro modes as well as the Routh-Hurwitz criteria. By fixing some of the transports, the suitable spaces for other ones are derived. I observe that in a dense medium having a finite U(1) charge with chemical potential μ0, negative values for transports appear and the second law of thermodynamics has not ruled out the existence of such values. Sign of scalar transports are not limited by any constraints and just a combination of vector transports is limited by the second law of thermodynamic. Also numerically it is proved that the most favorable region for transports $$ {\tilde{\upgamma}}_{1,2}, $$ γ ˜ 1 , 2 , coefficients of the dissipative terms of the current, is of negative values.

Hydrodynamic characteristics of the dense medium gas–solid fluidized bed for coal beneficiation and cleaning

2015 ◽  
Vol 34 (2) ◽  
pp. 173-183 ◽  
Author(s):  
Jingfeng He ◽  
Yuemin Zhao ◽  
Yaqun He ◽  
Zhenfu Luo ◽  
Hong Li ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Dense Medium ◽  
Hydrodynamic Characteristics ◽  
Coal Beneficiation

Applications of Computational Fluid Dynamics (CFD) Tools for Gravity Concentrators in Coal Preparation

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
Y. K. Xia
Keyword(s):  
Multiphase Flows ◽  
Coupling Effect ◽  
Numerical Models ◽  
Dense Medium ◽  
Hindered Settling ◽  
Heavy Medium ◽  
Computational Fluid Dynamics Cfd ◽  
Dimensional Simulation ◽  
Dense Medium Cyclone ◽  
Lagrange Approach

Extensive progress has been made in using CFD tool in the simulation of multiphase flows in some gravity concentrators. Several case studies for calculation of multiphase flows by different numerical models in spiral, dense medium cyclone, water only cyclones, hindered-settling bed separator, heavy medium vessel and jig are reviewed. The Euler-Lagrange approach in calculation of the particle movement and particle-liquid coupling effect are also discussed. The limitation of Euler-Euler models in the treatment of the particles with a size distribution, and disadvantages of discrete element method (DEM) in description of the jigging processes will be presented. The successful two-dimensional simulation of the hindered-settling bed separator, heavy medium vessel and jig by Euler-Lagrange approach is also addressed.

scholarly journals The potential for dense medium separation of mineral fines using a laboratory Falcon Concentrator

2017 ◽  
Vol 105 ◽  
pp. 7-9 ◽  
Author(s):  
C. Marion ◽  
H. Williams ◽  
R. Langlois ◽  
O. Kökkılıç ◽  
F. Coelho ◽  
...  
Keyword(s):  
Dense Medium

scholarly journals Light shift of the Ramsey resonance of coherent population trapping in optically dense medium

2018 ◽  
Vol 190 ◽  
pp. 04003 ◽  
Author(s):  
Konstantin Barantsev ◽  
Gavriil Voloshin ◽  
Andrey Litvinov ◽  
Evgeniy Popov
Keyword(s):  
Laser Pulses ◽  
Coherent Population Trapping ◽  
Dense Medium ◽  
Light Shift ◽  
Atomic Ensembles ◽  
Trapping Effect ◽  
Population Trapping ◽  
Ramsey Resonance

In this work we calculate the Ramsey resonances of coherent population trapping effect in cold atomic ensembles. The main goal is to investigate the light shift of the resonance on the different parameters in optically dense medium, because such medium can to distort and absorb the interrogating laser pulses.

scholarly journals Tunnelling dominates the reactions of hydrogen atoms with unsaturated alcohols and aldehydes in the dense medium

2018 ◽  
Vol 617 ◽  
pp. A25 ◽  
Author(s):  
V. Zaverkin ◽  
T. Lamberts ◽  
M. N. Markmeyer ◽  
J. Kästner
Keyword(s):  
Functional Groups ◽  
Rate Constants ◽  
Aldehyde Group ◽  
Dense Medium ◽  
Hydrogen Atoms ◽  
Hydrogen Addition ◽  
Reaction Rate Constants ◽  
Quantum Chemical Methods ◽  
Experimental Findings ◽  
Recombination Reactions

Hydrogen addition and abstraction reactions play an important role as surface reactions in the buildup of complex organic molecules in the dense interstellar medium. Addition reactions allow unsaturated bonds to be fully hydrogenated, while abstraction reactions recreate radicals that may undergo radical–radical recombination reactions. Previous experimental work has indicated that double and triple C–C bonds are easily hydrogenated, but aldehyde –C=O bonds are not. Here, we investigate a total of 29 reactions of the hydrogen atom with propynal, propargyl alcohol, propenal, allyl alcohol, and propanal by means of quantum chemical methods to quantify the reaction rate constants involved. First of all, our results are in good agreement with and can explain the observed experimental findings. The hydrogen addition to the aldehyde group, either on the C or O side, is indeed slow for all molecules considered. Abstraction of the H atom from the aldehyde group, on the other hand, is among the faster reactions. Furthermore, hydrogen addition to C–C double bonds is generally faster than to triple bonds. In both cases, addition on the terminal carbon atom that is not connected to other functional groups is easiest. Finally, we wish to stress that it is not possible to predict rate constants based solely on the type of reaction: the specific functional groups attached to a backbone play a crucial role and can lead to a spread of several orders of magnitude in the rate constant.

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