Keywords: Residence time distribution (RTD), moments of RTD, experimental estimation of RTD, RTD of ideal and nonideal flow models, axially dispersed plug flow model, tanks in series model, multiparameter model, dispersion coefficient, microfluid, macrofluid, earliness and lateness of mixing, conversion in nonideal flows.

This second part of the overview of reverse osmosis investigates the ability of membrane transport models, presented in Part 1, to describe and/or predict membrane performance under different operating conditions. The problem of using the transport models to describe mixed solute systems is also discussed. The emphasis is to provide a simple, practical, and yet comprehensive summary of the most...

the n-(2-benzoyl-phenyl) oxalyl derivatives are important models for studying of three-centered intramolecular hydrogen bonding in organic molecules. the quantum theoretical calculations for two crystal structures of n-(2-benzoyl-phenyl) oxalyl (compounds i and ii) were performed by density functional theory (b3lyp method and 6-311+g* basis set). from the optimized structures, geometric paramet...

Chemical tracers can be used to assess the simulated circulation in ocean models. Tracers that have been used in this context include tritium, chlorofluorocarbons, natural and bomb-produced radiocarbon, and to a lesser extent, oxygen, silicate, phosphate, isotopes of organic and inorganic carbon compounds, and certain noble gases (e.g., helium and argon). This paper reviews the use of chemical ...

We present the results of observational studies of a number of molecular clouds associated with ultracompact HII regions in regions of massive star formation. We derive molecular abundances and show that gas-phase-only chemical models of these regions are incapable of reproducing the observations. It appears that a rich chemistry occurs in the ice matrices frozen onto dust grains at high densit...

The solution of chemical kinetics is one of the most computationally intensive tasks in atmospheric chemical transport simulations. Due to the stiff nature of the system, implicit time stepping algorithms which repeatedly solve linear systems of equations are necessary. This paper reviews the issues and challenges associated with the construction of efficient chemical solvers, discusses several...

Implementation and evaluation of an array of chemical solvers in a global chemical transport model P. Eller, K. Singh, A. Sandu, K. Bowman, D. K. Henze, and M. Lee Department of Computer Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA NASA Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA Earth Institute, Columbia University, 2880 B...

We present a general mathematical framework for constructing deterministic models of simple chemical reactions. In such a model, an underlying dynamical system drives a process in which a particle undergoes a reaction (changes color) when it enters a certain subset (the catalytic site) of the phase space and (possibly) some other conditions are satisfied. The framework we suggest allows us to d...

A brief review of mathematical models in chemical physics is given. More attention is devoted to the theory of chain reactions. This theory was created by N.N. Semenoff. Chain theory is theoretical foundation of modern models. Being extremely significant in the field of chemistry, chain processes are investigated by experimental methods as well as by mathematical models. The results of calculat...

Stellar evolution computations provide the foundation of several methods applied to study the evolutionary properties of stars and stellar populations, both Galactic and extragalactic. The accuracy of the results obtained with these techniques is linked to the accuracy of the stellar models, and in this context the correct treatment of the transport of chemical elements is crucial. Unfortunatel...