Excitons Diffusion Length, Tree Dimensionless Numbers and Mean Temperature Dependence of Semiconductor Performance Including Excitons
Modou Faye,
Ousmane Ngom,
Saliou Ndiaye,
Cheikh Mbow,
Bassirou Ba
Issue:
Volume 9, Issue 2, March 2020
Pages:
25-33
Received:
27 March 2020
Accepted:
20 April 2020
Published:
18 May 2020
Abstract: The author, taking into account the non-uniformity of dissociation, the recombination of excitons in the depletion region, as well as the variability of the coefficients as a function of temperature, used dimensional analysis. Thus, by grouping together the physical parameters, dependent and independent variables, he generates dimensionless numbers. Among the latter, we have the ratio between the diffusion time and the lifetime of the charge carriers (Fourier number); the ratio between the imposed heat flux and that thermal conduction (heating factor) and the ratio between the mobility of the excitons and that of the electrons. The motivation of the author is on the one hand to show the influence of these dimensionless numbers on the diffusion lengths of the charge carriers and on the other hand their influence and that of the diffusion lengths on the total photocurrent density of the carriers. Therefore, he studied the effects of the mean temperature and those of the mobility ratio on the total density of the photocurrent. In order to carry out such work, the author opted for the finite volume method combined with an iterative line-by-line relaxation method of the Gauss-Seidel type as a method of solving his physical problem.
Abstract: The author, taking into account the non-uniformity of dissociation, the recombination of excitons in the depletion region, as well as the variability of the coefficients as a function of temperature, used dimensional analysis. Thus, by grouping together the physical parameters, dependent and independent variables, he generates dimensionless numbers...
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A Low Temperature Manufactured Portland Cement Clinker from Pulverized Waste of Fly Ash
Hassan Hassanien Mohamed Darweesh
Issue:
Volume 9, Issue 2, March 2020
Pages:
34-39
Received:
21 April 2020
Accepted:
18 May 2020
Published:
28 June 2020
Abstract: The possibility to produce both environmentally and friendly cement exclusively or solely from industrial byproducts such as pulverized fly ash (PFa) was investigated. A low clinkering temperature was attained or acquired to produce cement. It is capable to gain high early and late strength on hydration. The optimum quantities of PFa and clinkering temperature were detected. The results indicated that the higher the clinkering temperature, the higher hydration reactivity of the cement. The optimum PFa content and clinkering temperature for synthesizing cement were found to be 35 wt. % and 1350°C, respectively. The production of cement with PFa at a low clinkering temperature can save energy and natural resources consumption, landfills disposal cost and also can reduce CO2↑ emission. The formed major phases in presence of PFa are more or less the same as those of the blank as experimentally achieved and approved by the compressive strength. As the PFa content increased, the free lime contents decreased, and also the firing or clinkering temperature decreased. The optimum PFa content must not exceed than 35 wt. %, and any further increase of Pfa resulted in adverse effects on all characteristics of the produced clinker.
Abstract: The possibility to produce both environmentally and friendly cement exclusively or solely from industrial byproducts such as pulverized fly ash (PFa) was investigated. A low clinkering temperature was attained or acquired to produce cement. It is capable to gain high early and late strength on hydration. The optimum quantities of PFa and clinkering...
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