Gas absorption in a countercurrent packed tower : (1) Absorption with simultaneous chemical reaction (2) absorption into varying viscous solutions

The surface renewal rate from Danckwerts' theory and the effective interfacial area between gas and liquid per unit packing volume in a packed absorption tower were evaluated for the absorption of carbon dioxide into carbonate/bicarbonate buffer solution accompanied by a pseudo-first order chemical reaction. The rate of chemical reaction in the liquid phase was controlled by varying the buffer ratios. A small absorption tower was constructed, which had a packing section, 30 cm high with 10.2 cm inside diameter. Two kinds of packing, ½-inch Rasehig ring for one part of the experiment and ½-inch Ben saddle for the other part of the experiment, were used in the investigation. Sodium carbonate/bicarbonate buffer solutions, with buffer ratios varying from 0.4 to 3.0, were used. Glycerine-water solutions were also used to investigate the effect of density and viscosity on the physical absorption of carbon dioxide; the content of glycerine varied from 0 to 40 % wt. Pure carbon dioxide was used to eliminate the gas side resistance in the mass transfer operation. The results of this investigation suggested the following conclusions: The surface renewal rate, s, and the effective interfacial area per unit packing volume, a, for each packing can be expressed as functions of Reynolds Number of the liquid flow. The comparison of values from this study with those of Danckwerts showed discrepancies; these discrepancies could be due to different flow patterns, packing densities, and the apparently more uniform distribution of liquid over the packing. The mass transfer coefficient for physical absorption into glycerine solution was expressed as a function of Reynolds number and Schmidt number. The mass transfer coefficient calculated from Danckwerts' model equation, kL*a = [Ds divided by a*] for absorption of carbon dioxide into water seemed to be larger than those measured in this experiment

Common fixed point theorems and applications

The purpose of this paper is to discuss the existence of common fixed points for mappings in general quasi-metric spaces. As applications, some common fixed point theorems for mappings in probabilistic quasi-metric spaces are given. The results presented in this paper generalize some recent results

MGOS: A library for molecular geometry and its operating system

The geometry of atomic arrangement underpins the structural understanding of molecules in many fields. However, no general framework of mathematical/computational theory for the geometry of atomic arrangement exists. Here we present "Molecular Geometry (MG)'' as a theoretical framework accompanied by "MG Operating System (MGOS)'' which consists of callable functions implementing the MG theory. MG allows researchers to model complicated molecular structure problems in terms of elementary yet standard notions of volume, area, etc. and MGOS frees them from the hard and tedious task of developing/implementing geometric algorithms so that they can focus more on their primary research issues. MG facilitates simpler modeling of molecular structure problems; MGOS functions can be conveniently embedded in application programs for the efficient and accurate solution of geometric queries involving atomic arrangements. The use of MGOS in problems involving spherical entities is akin to the use of math libraries in general purpose programming languages in science and engineering. (C) 2019 The Author(s). Published by Elsevier B.V

Seasonal Prevalence of Mosquitoes, Including Vectors of Brugian Filariasis, in Southern Islands of the Republic of Korea

A survey of mosquitoes, including the vector status of Brugia malayi filariasis and their relative larval density, was conducted from 2002 to 2005 at several southern remote islands of Jeollanam-do (province), Gyeongsangnam-do, and Jeju-do, Korea, where filariasis was previously endemic. Overall, a total of 9 species belonging to 7 genera were collected. Ochlerotatus togoi (formerly known as Aedes togoi), Anopheles (Hyrcanus) group, and Culex pipiens were the predominant species captured at all areas. Oc. togoi larvae were most frequently collected at salinity levels <0.5% during June and July, with densities decreasing sharply during the rainy season in August. The most likely explanation for the eradication of filariasis in these areas is suggested to be an aggressive treatment program executed during the 1970s and the 1990s. However, high prevalence of the vector mosquitoes may constitute a potential risk for reemerging of brugian filariasis in these areas

Renormalization group theory for percolation in time-varying networks

Motivated by multi-hop communication in unreliable wireless networks, we present a percolation theory for time-varying networks. We develop a renormalization group theory for a prototypical network on a regular grid, where individual links switch stochastically between active and inactive states. The question whether a given source node can communicate with a destination node along paths of active links is equivalent to a percolation problem. Our theory maps the temporal existence of multi-hop paths on an effective two-state Markov process. We show analytically how this Markov process converges towards a memory-less Bernoulli process as the hop distance between source and destination node increases. Our work extends classical percolation theory to the dynamic case and elucidates temporal correlations of message losses. Quantification of temporal correlations has implications for the design of wireless communication and control protocols, e.g. in cyber-physical systems such as self-organized swarms of drones or smart traffic networks.Comment: 8 pages, 3 figure