gas hydrate formation in production and transmission pipelines and consequent plugging of these lines have been a major flow-assurance concern of the oil and gas industry for the last 75 years. gas hydrate formation rate is one of the most important topics related to the kinetics of the process of gas hydrate crystallization. the main purpose of this study is investigating phenomenon of gas hyd...

reaction constants and heat release during thermophilic aerobic digestion of typical secondary and mixed sludges were determined. maximum reaction constant, determined by measuring the amounts of biodegradable volatile suspended solids (bvss) removed, occurred in the temperature range of 55-60 ºc. measurement of heat releases were carried out, at the same range, by the aid of a temperature prog...

We study a surface growth model related to the Kardar-Parisi-Zhang equation for nonequilibrium kinetic roughening, but where the thermal noise is replaced by a static columnar disorder eta(x) . This model is one of the many representations of the problem of particle diffusion in trapping or amplifying disordered media. We find that probability localization in the latter translates into facet fo...

About the "normal growth" approximation in the dynamical theory of phase transitions L. Truskinovsky Nonequilibrium phase transitions can often be modeled by a surface of dis-continuity propagating into a metastable region. The physical hypothesis of "normal growth" presumes a linear relation between the velocity of the phase boundary and the degree of metastability. The phenomenological coeffi...

Kinetic models for bioethanol production from waste sorghum leaves by Saccharomyces cerevisiae BY4743 are presented. Fermentation processes were carried out at varied initial glucose concentrations (12.5–30.0 g/L). Experimental data on cell growth and substrate utilisation fit the Monod kinetic model with a coefficient of determination (R2) of 0.95. A maximum specific growth rate (μmax) and Mon...

Reaction behaviors and kinetics of catalytic oxidation of toluene with different feed flows over Pt/Zr(x)-HMS catalysts with Si/Zr ratio equal to 5, 10, 20 and 35 were investigated over a wide temperature range (200 – 500 oC). Results show that Pt/Zr(x)-HMS performs more easily toluene oxidation. The kinetic data were fitted by the Power-law and Mars–van Krevelen kinetic models. The fitting res...

An in situ respirometric technique was applied to a sequential biofilm batch reactor treating a synthetic wastewater containing acetate. In this reactor, inoculated with mixed liquor from a wastewater plant, unglazed ceramic tiles were used as support media while maintaining complete mixing regime. A total of 8 kinetic and stoichiometric parameters were determined by in situ pulse respirometry;...

regarding the important role of health in economic growth and development, the purpose of the present paper is to investigate the impact of life expectancy, as the most important indicator of health, on economic growth in iran during 1965-2009. the estimated smooth transition regression (str) model supports a nonlinear threshold behavior in the relationship between life expectancy and economic ...

one may find out the application‎ ‎of mathematics in the areas of ecology‎, ‎biology‎, ‎environmental‎ ‎sciences etc‎. ‎mathematics is particulary used in the problem of‎ ‎predator-prey known as lotka-volterra predator-prey equations.‎ ‎indeed‎, ‎differential equations is employed very much in many areas‎ ‎of other sciences‎. ‎however‎, ‎most of natural problems involve some‎ ‎unknown functions...

In the most cases of the practical fermentation processes with filamentous microorganisms, direct monitoring of the cell morphology and biomass distribution in the culture medium is not easy possible. Penicillium brevicompactum is one of the morphologically complex filamentous fungi with different structural forms. In this research, nutrient uptake and cell growth kinetics was investigated comp...