MHD Natural Convection with Convective Surface Boundary Condition over a Flat Plate

We apply the one parameter continuous group method to investigate similarity solutions of magnetohydrodynamic (MHD) heat and mass transfer flow of a steady viscous incompressible fluid over a flat plate. By using the one parameter group method, similarity transformations and corresponding similarity representations are presented. A convective boundary condition is applied instead of the usual boundary conditions of constant surface temperature or constant heat flux. In addition it is assumed that viscosity, thermal conductivity, and concentration diffusivity vary linearly. Our study indicates that a similarity solution is possible if the convective heat transfer related to the hot fluid on the lower surface of the plate is directly proportional to (x-)-1/2 where x- is the distance from the leading edge of the solid surface. Numerical solutions of the ordinary differential equations are obtained by the Keller Box method for different values of the controlling parameters associated with the problem

Polyvinylidene Fluoride-Graphene Oxide Membranes for Dye Removal under Visible Light Irradiation

[EN] In this study, polyvinylidene fluoride (PVDF)-graphene oxide (GO) membranes were obtained by employing triethyl phosphate (TEP) as a solvent. GO nanosheets were prepared and characterized in terms of scanning and transmission electron microscopy (SEM and TEM, respectively), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), chemical analysis and inductively coupled plasma mass spectroscopy (ICP). Two different phase inversion techniques, Non-Solvent Induced Phase Separation (NIPS) and Vapour-Induced Phase Separation (VIPS)/NIPS, were applied to study the effect of fabrication procedure on the membrane structure and properties. Membranes were characterized by SEM, AFM, pore size, porosity, contact angle and mechanical tests, and finally tested for photocatalytic methylene blue (MB+) degradation under visible light irradiation. The effect of different pH values of dye aqueous solutions on the photocatalytic efficiency was investigated. Finally, the influence of NaCl salt on the MB+ photodegradation process was also evaluated.The authors acknowledge the financial support from Iran Science Ministry. The authors also sincerely thank the Institute on Membrane Technology, National Research Council of Italy (ITM-CNR) for kindly collaborate.Alyarnezhad, S.; Marino, T.; Parsa, JB.; Galiano, F.; Ursino, C.; García Gómez, H.; Puche, M.... (2020). Polyvinylidene Fluoride-Graphene Oxide Membranes for Dye Removal under Visible Light Irradiation. E-Polymers. 12(7):1-19. https://doi.org/10.3390/polym12071509S119127Figoli, A., Ursino, C., Galiano, F., Di Nicolò, E., Campanelli, P., Carnevale, M. C., & Criscuoli, A. (2017). Innovative hydrophobic coating of perfluoropolyether (PFPE) on commercial hydrophilic membranes for DCMD application. Journal of Membrane Science, 522, 192-201. doi:10.1016/j.memsci.2016.08.066Dao, V.-D., Vu, N. H., & Choi, H.-S. (2020). All day Limnobium laevigatum inspired nanogenerator self-driven via water evaporation. Journal of Power Sources, 448, 227388. doi:10.1016/j.jpowsour.2019.227388Dao, V.-D., Vu, N. H., & Yun, S. (2020). Recent advances and challenges for solar-driven water evaporation system toward applications. Nano Energy, 68, 104324. doi:10.1016/j.nanoen.2019.104324Dao, V.-D., & Choi, H.-S. (2018). Carbon-Based Sunlight Absorbers in Solar-Driven Steam Generation Devices. Global Challenges, 2(2), 1700094. doi:10.1002/gch2.201700094Pastrana-Martínez, L. M., Morales-Torres, S., Figueiredo, J. L., Faria, J. L., & Silva, A. M. T. (2015). Graphene oxide based ultrafiltration membranes for photocatalytic degradation of organic pollutants in salty water. Water Research, 77, 179-190. doi:10.1016/j.watres.2015.03.014Zhang, X., Wang, D. K., & Diniz da Costa, J. C. (2014). Recent progresses on fabrication of photocatalytic membranes for water treatment. Catalysis Today, 230, 47-54. doi:10.1016/j.cattod.2013.11.019Athanasekou, C. P., Moustakas, N. G., Morales-Torres, S., Pastrana-Martínez, L. M., Figueiredo, J. L., Faria, J. L., … Falaras, P. (2015). Ceramic photocatalytic membranes for water filtration under UV and visible light. Applied Catalysis B: Environmental, 178, 12-19. doi:10.1016/j.apcatb.2014.11.021Athanasekou, C. P., Romanos, G. E., Katsaros, F. K., Kordatos, K., Likodimos, V., & Falaras, P. (2012). Very efficient composite titania membranes in hybrid ultrafiltration/photocatalysis water treatment processes. Journal of Membrane Science, 392-393, 192-203. doi:10.1016/j.memsci.2011.12.028Romanos, G. E., Athanasekou, C. P., Katsaros, F. K., Kanellopoulos, N. K., Dionysiou, D. D., Likodimos, V., & Falaras, P. (2012). Double-side active TiO2-modified nanofiltration membranes in continuous flow photocatalytic reactors for effective water purification. 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Documenting and predicting topic changes in Computers in Biology and Medicine: A bibliometric keyword analysis from 1990 to 2017

The Computers in Biology and Medicine (CBM) journal promotes the use of com-puting machinery in the fields of bioscience and medicine. Since the first volume in 1970, the importance of computers in these fields has grown dramatically, this is evident in the diversification of topics and an increase in the publication rate. In this study, we quantify both change and diversification of topics covered in CBM. This is done by analysing the author supplied keywords, since they were electronically captured in 1990. The analysis starts by selecting 40 keywords, related to Medical (M) (7), Data (D)(10), Feature (F) (17) and Artificial Intelligence (AI) (6) methods. Automated keyword clustering shows the statistical connection between the selected keywords. We found that the three most popular topics in CBM are: Support Vector Machine (SVM), Elec-troencephalography (EEG) and IMAGE PROCESSING. In a separate analysis step, we bagged the selected keywords into sequential one year time slices and calculated the normalized appearance. The results were visualised with graphs that indicate the CBM topic changes. These graphs show that there was a transition from Artificial Neural Network (ANN) to SVM. In 2006 SVM replaced ANN as the most important AI algo-rithm. Our investigation helps the editorial board to manage and embrace topic change. Furthermore, our analysis is interesting for the general reader, as the results can help them to adjust their research directions

A new numerical method for investigation of thermophoresis and Brownian motion effects on MHD nanofluid flow and heat transfer between parallel plates partially filled with a porous medium

Numerical investigation the problem of nanofluid heat and mass transfer in a channel partially filled with a porous medium in the presence of uniform magnetic field is carried out by a new computational iterative approach known as the spectral local linearization method (SLLM). The similarity solution is used to reduce the governing system of partial differential equations to a set of nonlinear ordinary differential equations which are then solved by SLLM and validity of our solutions is verified by the numerical results (fourth-order Runge-Kutta scheme with the shooting method). In modeling the flow in the channel, the effects of flow inertia, Brinkman friction, nanoparticles concentration and thickness of the porous region are taken into account. The results are obtained for velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number. Also, effects of active parameters such as viscosity parameter, Hartmann number, Darcy number, Prandtl number, Schmidt number, Eckert number, Brownian motion parameter, thermophoresis parameter and the thickness of porous region on the hydrodynamics, heat and mass transfer behaviors are investigated. Keywords: Brownian, Nanofluid, Porous medium, Spectral local linearization method, Thermophoresi

Nanofluid flow and heat transfer in a Brinkman Porous Channel with variable porosity

The problem of forced convection in a channel lled with a nano fluid-saturated porous medium is investigated, numerically. A nite difference Computational Fluid Dynamics (CFD) model with structured uniform grid system is employed to solve the momentum and energy equations. In modeling flow in the channel, the effects of flow inertia, variable porosity and Brinkman friction are taken into account. Studies are carried out for different nanoparticles with different volume fractions in the range 0%-4% and different nanoparticle diameters. Comparison made between our numerical and semi analytical Differential Transform Method (DTM) results with those in previous published research is found to be appropriate. Results show that increasing either nanoparticles volume fraction or pressure gradient parameter improves heat transfer. Further, for large quantities of nanoparticle concentration and pressure gradient, the channeling phenomenon is intensied.Keywords: Brinkman friction, nano fluid, numerical solution, porous channel, semi analytical metho

Treatment of Synthetic Wastewater Containing AB14 Pigment by Electrooxidation in both Pilot and Bench Scale Reactors

The electrochemical oxidation process was used for the degradation of Acid Brown 14 in both bench and pilot scale reactors. The bench scale one with a working volume of 0.5 L was equipped with platinum plate used as the anode and stainless steel (SS-304) plates as the cathode. The pilot scale reactor had a volume of 9 L and was equipped with SS-304 plates used as both the anode and the cathode. Experiments were run using these reactors to investigate the two parameters of energy consumption and anode efficiency. The bench scale reactor was capable of removing 92% and 36% of the dye and COD, respectively, after 18 min of operation. The pilot scale reactor, however, was capable of removing 87% and 59% of the dye and the COD content, respectively, after 60 min of operation. The kinetic study of both the bench and pilot reactors for dye and COD removals showed that both processes followed a zero order kinetic

Numerical analysis of forced convection heat transfer from two tandem circular cylinders embedded in a porous medium

Study the heat and mass transfer in packed bed heat exchangers particularly in nuclear application is subject of many new researches. In this paper numerical analysis of forced convection heat transfer from two tandem circular cylinders embedded in a packed bed, which is made of spherical aluminum particles, is investigated in laminar flow. The porous medium increases the overall heat absorbed from two cylinders and cooling effect but increases the pressure drop, significantly. Also, the effect of increase the horizontal distance between two tandem circular cylinders on flow pattern and heat transfer is investigated. For the empty channel, the total wall heat flux in very small distances have a minimum due to generation of closed vortex region and for longer distances, by increases the distance between two tandem cylinder, the total wall heat flux increases. It is shown that for two circular cylinders embedded in the packed bed, the total wall heat fluxes from two cylinders and the fluid outlet temperature increase to a maximum quantity and then decrease with negative gradient. Also, the quantities of the empty channel are too smaller than the amounts of porous medium