Theoretical and Numerical Investigation of Liquid-Gas Interface Location of Capillary Driven Flow During the Time Throughout Circular Microchannels

The main aim of this study is to find the best, most rapid, and the most accurate numerical method to find the liquid-gas interface of capillary driven flow during the time in circular Microchannels by using COMSOL Multiphysics software. Capillary driven flow by eliminating micropumps or any physical pressure gradient generators can make the microfluidic devices cheaper and more usable. Hence, by using this two-phase flow, the final costs of lots of microfluidic devices and lab-on-a-chip can significantly be decreased and help them to be commercialized. The first step to employing the capillary flow in these devices is the simulation of this flow inside the microchannels. One of the most common and valid software for this work is COMSOL Multiphysics; this fact reveals the importance of this study. In this research study, simulation results obtained by using two possible numerical methods in this software, for capillary flows of water and ethanol in two different circular microchannels, verified and compared with four other methods, which verified experimentally before. Finally, the most accurate and time-saving numerical method of this software will be specified. This appropriate technique can contribute to simulate microfluidic and lab-on-a-chip devices, which are made of different mechanical and electrical parts, in COMSOL Multiphysics software by choosing the best method.Comment: 7 pages, 13 figures, 7 tables, 2017 5th International Conference on Robotics and Mechatronics (ICROM

The Onset of Chaos in Pulsating Variable Stars

Random changes in pulsation period occur in cool pulsating Mira variables, Type A, B, and C semiregular variables, RV Tauri variables, and in most classical Cepheids. The physical processes responsible for such fluctuations are uncertain, but presumably originate in temporal modifications of the envelope convection in such stars. Such fluctuations are seemingly random over a few pulsation cycles of the stars, but are dominated by the regularity of the primary pulsation over the long term. The magnitude of stochasticity in pulsating stars appears to be linked directly to their dimensions, although not in simple fashion. It is relatively larger in M supergiants, for example, than in short-period Cepheids, but is common enough that it can be detected in visual observations for many types of pulsating stars. Although chaos was discovered in such stars 80 years ago, detection of its general presence in the group has only been possible in recent studies.Comment: To appear in the proceedings of the Odessa Variable Stars 2010 Conference (see http://uavso.org.ua/?page=vs2010&lang=en), edited by I. Andronov and V. Kovtyuk

Producing fish sauce from Caspian kilka

Fish sauce is a fermented product which is used in south Asian countries. In the present study, Caspian Kilka was used to produce the sauce, using either cooked or raw fish subjected to four different treatments: 1) traditional method, where fish and salt were used; 2) an enzymatic method, where fish, salt and proteolytic enzymes, including Protamex and Flavourzyme (Novo Nordisc Co., Bagsvaerd, Denmark), were used; 3) a microbial method, where fish, salt, and Bacillus and Pediococcus species were used; and 4) a combination of the enzyme and microbial methods. Fermentation of the ingredients was carried out in 400cc bottles for a period of 6 months with microbiological and chemical tests at intervals of one week and then one month. The results of molds, yeast, and aflatoxin detection tests were negative. The total bacterial count ranged between log 2.1 and 6.18. Chemical tests included TVN and pH. pH of the final products ranged from 6.5 to 7.0. The speed of fermentation as determined by examining the bottles every two or three days was as follows: Traditional< Microbial<Enzymatic = Enzymatic+Microbial Method. However different treatments could be used to speed up the fermentation, but the traditional method is considered to be better as the quality is concerned