Electrical Conductivity and Chemical Diffusion Coefficient of Strontium-Doped Lanthanum Manganites

1996 ◽  
Vol 123 (2) ◽  
pp. 382-390 ◽  
Author(s):  
Isamu Yasuda ◽  
Masakazu Hishinuma
Keyword(s):  
Electrical Conductivity ◽  
Diffusion Coefficient ◽  
Chemical Diffusion ◽  
Chemical Diffusion Coefficient ◽  
Lanthanum Manganites ◽  
Doped Lanthanum Manganites

scholarly journals Boundary layer analysis for a 2-D Keller-Segel model

2020 ◽  
Vol 18 (1) ◽  
pp. 1895-1914
Author(s):  
Linlin Meng ◽  
Wen-Qing Xu ◽  
Shu Wang
Keyword(s):  
Boundary Layer ◽  
Diffusion Coefficient ◽  
Approximate Solution ◽  
Chemical Diffusion ◽  
Singular Perturbation Theory ◽  
Energy Estimates ◽  
Chemical Diffusion Coefficient ◽  
Boundary Layer Problem ◽  
Classical Energy ◽  
Layer Analysis

Abstract We study the boundary layer problem of a Keller-Segel model in a domain of two space dimensions with vanishing chemical diffusion coefficient. By using the method of matched asymptotic expansions of singular perturbation theory, we construct an accurate approximate solution which incorporates the effects of boundary layers and then use the classical energy estimates to prove the structural stability of the approximate solution as the chemical diffusion coefficient tends to zero.

Diffusion und Korrelation in goldreichen Gold—Zinn-Mischkristallen / Diffusion and Correlation in Gold-Rich Gold—Tin Solid Solutions

1972 ◽  
Vol 27 (7) ◽  
pp. 1109-1118 ◽  
Author(s):  
Chr. Herzig ◽  
Th. Heumann
Keyword(s):  
Diffusion Coefficient ◽  
Impurity Content ◽  
Chemical Diffusion ◽  
Correlation Factor ◽  
Coarse Grained ◽  
Pure Gold ◽  
Large Temperature ◽  
Chemical Diffusion Coefficient ◽  
Self Diffusion ◽  
Different Temperatures

Abstract The diffusion of Sn-113 and Au-195 in pure gold and dilute tin -gold alloys has been measured at different temperatures and tin concentrations in coarse-grained specimens. In addition the dependence on concentration of the chemical diffusion coefficient and the diffusion of tin in gold at very low impurity concentrations has been determined using the electron microprobe. It was found, that the self-diffusion coefficient of tin as well as that of gold increased strongly with in-creasing impurity content. The thermodynamic factor is equal to one up to ca. 0.5 at.-% tin. For the correlation factor of the diffusion of tin in gold, calculated by the relation of Lidiard, an essentially temperature independent value is obtained. A comparison of the experimental results with the model of Le Claire concerning the impurity diffusion in metals shows, that this model seems to require a too-large temperature dependence of the correlation factor

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