Diffuse transmission theory

Heat diffusivity transmission coefficient in the transition-state theory... 

ABSTRACT With the increase of mine exploitation depth and appliance widely of large-scale full-mechanized equipment, coal block gas emission has been one of the most gas effusion source. Base on unsteady diffusion theory and mass transmission fundamental, the mathematical and physical model of gas diffusion through coal particles with third type boundary condition was founded and its analytical solution was obtained by separate variableness method. The characteristics of gas through coal particles was analyzed according as mass transmission theory of porous material. The results show that the Biot s criterion of mass transmission can reflect the resistance characteristic of gas diffusion and the Fourier s criterion of mass transmission can represent the dynamic feature of diffusion field varying with time. 

Simmons (1975) compared various theories of diffuse reflectance. He introduced a modified remission function, which explains deviations from linearity when F(p) is plotted versus k. He also concluded that the Kubelka-Munk function is proportional to the absorption coefficient k as obtained from transmission measurements for "weakly absorbing samples." Unfortunately, most literature is vague in that "weak" or "strong" absorption is not specified. One value given for "weak" is F(p) < 1 (Kellermann, 1979). 

Except for the fullerenes, carbon nanotubes, nanohoms, and schwarzites, porous carbons are usually disordered materials, and cannot at present be completely characterized experimentally. Methods such as X-ray and neutron scattering and high-resolution transmission electron microscopy (HRTEM) give partial structural information, but are not yet able to provide a complete description of the atomic structure. Nevertheless, atomistic models of carbons are needed in order to interpret experimental characterization data (adsorption isotherms, heats of adsorption, etc.). They are also a necessary ingredient of any theory or molecular simulation for the prediction of the behavior of adsorbed phases within carbons - including diffusion, adsorption, heat effects, phase transitions, and chemical reactivity. 

In terms of absolute rate theory, provided the transmission coefficient at the activation barrier is unity, the diffusivity D0 is given by the expression... 

Values of the crystal field splitting parameters A or QDq are listed in Table 8. These give a good idea of relative strengths of ion-water interactions they are available from solution transmission spectra and from diffuse reflectance spectra for solids containing [M(OH2) J" complex cations. The greater interaction with than with and with second-row M " than with first-row as well as the dependence on d electron configuration and spin all accord satisfactorily with crystal field theory. 

This formula follows directly from isothermal diffusion theory (Schottky, 1938) in which the parameter denotes the transmission coefficient for majority carriers across the barrier interface (j9 = 1 implies a transparent barrier). 

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