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A note on the synergistic effect of surfactants and nanoparticles on rising bubble hydrodynamics
, Article Chemical Engineering and Processing - Process Intensification ; Volume 155 , 2020 ; Bastani, D ; Lotfi, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Various mixtures of surfactants and nanosilica particles were investigated to assess their influence on rising bubble hydrodynamics. For this purpose, local velocities of rising bubbles were measured experimentally. Also, the effects of concentration of three types of surface-modified silica nanoparticles on density, viscosity, and surface tension of surfactant solutions were determined. Experimental results revealed that the simultaneous presence of nanoparticles and surfactant molecules led to the decrease of local velocities of rising bubbles. The presence of nanoparticles in surfactant solutions leads to a more reduction of bubble local velocity. This could be caused by the formation of...
Influence of surface-modified nanoparticles on the hydrodynamics of rising bubbles
, Article Chemical Engineering and Technology ; Volume 44, Issue 3 , 2021 , Pages 513-520 ; 09307516 (ISSN) ; Bastani, D ; Lotfi, M ; Miller, R ; Sharif University of Technology
Wiley-VCH Verlag
2021
Abstract
Local velocities of bubbles rising in four different nanosilica solutions were investigated experimentally. Also, the density, viscosity, and surface tension of fumed nanosilica and modified nanosilica solutions were measured. Heat treatment and chemical functionalization were used to modify the properties of silica nanoparticles. It was found that the addition of nanosilica affected the hydrodynamics of the rising bubble by increasing the drag friction at the interface. However, environmentally responsive nanosilica particles behaved like surfactant molecules, due to the interfacial activity of hydrophilic and hydrophobic chains. Silica nanoparticles coated with both hydrophilic and...
Non-Equilibrium Interfacial Behavior of Dynamic Interfaces in Presence of Surfactants and Nanoparticles; Experimental and Computational Fluid Dynamic Investigations
, Ph.D. Dissertation Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Lotfi, Marzieh (Supervisor)
Abstract
The present study has been performed for better understanding about the dynamic behavior of fluid interfaces in presence of surfactants, nanoparticles and their interactions in gas-liquid dispersion systems. One of the main purposes of this work is to investigate the influence of surface modified nanoparticles on the dynamic behavior of gas-liquid interfaces. For this purpose, the rising bubble experiment was used as one of the most conventional procedures. Local velocities of bubbles rising in nanoparticle solutions were determined experimentally. Influences of silica nanoparticles which were modified via three approaches were investigated in these experiments. Heat treatment was applied to...
An improved macro-model for simulation of single electron transistor (SET) using HSPICE
, Article TIC-STH'09: 2009 IEEE Toronto International Conference - Science and Technology for Humanity, 26 September 2009 through 27 September 2009, Toronto, ON ; 2009 , Pages 1000-1004 ; 9781424438785 (ISBN) ; Dousti, M ; Pouyan, M ; Faez, R ; Sharif University of Technology
2009
Abstract
To get a more accurate model for simulation of single electron transistors (SETs), we have proposed a new macromodel that includes the ability of electron tunneling time calculation. In our proposed model, we have modified the previous models and applied some basic corrections to their formulas. In addition, we have added a switched capacitor circuit, as a quantizer, to calculate the electron tunneling time. We used HSPICE for high-speed simulation and observed that the simulation results obtained from our model matched more closely with that of SIMON 2.0. We also could evaluate the time of electron tunneling through the barrier by using the quantizer. Clearly, our macro-model gives more...
The effects of bubble detachment shape on rising bubble hydrodynamics
, Article Scientia Iranica ; Volume 26, Issue 3 C , 2019 , Pages 1546-1554 ; 10263098 (ISSN) ; Bastani, D ; Lotfi, M ; Ghamangiz Khararoodi, M ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
Local velocities and aspect ratios of rising bubbles were measured to investigate the effects of bubble detachment shape on rising bubble hydrodynamics. Two types of capillary were employed to generate bubbles of identical volume: one glassy nozzle aligned vertically and the other stainless steel needle aligned horizontally. Horizontally injected bubbles have a spherical initial shape, and their values of aspect ratio slightly fluctuate around unity. However, vertically injected bubbles have a surface-stretched initial shape, and their values of aspect ratios decrease sharply from 1.1 to 0.65. There is a notable correspondence between the variation of local velocities and aspect ratios that...
A New SPICE macro-model for the simulation of single electron circuits
, Article Journal of the Korean Physical Society ; Volume 56, Issue 4 , 2010 , Pages 1202-1207 ; 03744884 (ISSN) ; Dousti, M ; Pouyan, M ; Faez, R ; Sharif University of Technology
2010
Abstract
To get a more accurate model for the simulation of single electron transistors (SETs), we propose a new macro-model that includes an electron tunneling time calculation. In our proposed model, we have modified the previous models and have applied some basic corrections to the formulas. In addition, we have added a switched capacitor circuit, as a quantizer, to calculate the electron tunneling time. We used HSPICE for a high-speed simulation and observed that the simulation results obtained from our model match more closely with that of SIMON 2.0. We also could evaluate the time of electron tunneling through the barrier by using the quantizer. Clearly, our macro-model gives more accurate...
A novel fuzzy genetic annealing classification approach
, Article EMS 2009 - UKSim 3rd European Modelling Symposium on Computer Modelling and Simulation, 25 November 2009 through 27 November 2009, Athens ; 2009 , Pages 87-91 ; 9780769538860 (ISBN) ; Mohamadi, H ; Saniee Abadeh, M ; Foroughifar, A ; Sharif University of Technology
2009
Abstract
In this paper, a novel classification approach is presented. This approach uses fuzzy if-then rules for classification task and employs a hybrid optimization method to improve the accuracy and comprehensibility of obtained outcome. The mentioned optimization method has been formulated by simulated annealing and genetic algorithm. In fact, the genetic operators have been used as perturb functions at the core of simulated annealing heuristic. Results of proposed approach have been compared with several well-known methods such as Naïve Bayes, Support Vector Machine, Decision Tree, k-NN, and GBML, and show that our method performs the classification task as well as other famous algorithms. ©...
Misuse detection via a novel hybrid system
, Article EMS 2009 - UKSim 3rd European Modelling Symposium on Computer Modelling and Simulation, 25 November 2009 through 27 November 2009, Athens ; 2009 , Pages 11-16 ; 9780769538860 (ISBN) ; Abadeh, M. S ; Momenzadeh, A ; Pouyan, M. B ; Sharif University of Technology
2009
Abstract
Intrusion detection systems (IDS) are tools located inside computer networks that analyze the network traffics. In this paper, a novel fuzzy-evolutionary system is presented to effectively detect the intrusion in computer networks. This system utilizes a hybridization of simulated annealing heuristic and tabu search algorithm to improve the accuracy of fuzzy if-then rules as intrusion detectors. Each of these algorithms has its advantageous and disadvantageous. Using the hybrid model of both algorithms, the proposed system employs the good features of them to improve the accuracy of obtained rules. Evaluation of the proposed system is done on the KDDCup99 Dataset which has information about...
The Effect of Type, Size and Morphology of Nanoparticles on the Hydrodynamics of Rising Bubble Motion
, M.Sc. Thesis Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Feizi, Pouyan (Co-Supervisor)
Abstract
The motion of gas bubbles in the bulk of a fluid can be one of the most widely used industrial phenomena. Various factors such as the size and shape of the bubbles, the physical properties of the liquid phase such as density and viscosity, method of gas injection, the presence of impurities, etc. affect this phenomenon. Some of the most important industrial processes that include the motion of bubbles in the liquid phase bulk are gas adsorption, distillation and froth flotation. According to the results of previous studies, the hydrodynamics of bubble motion in the bulk of a liquid fluid depends on the presence of impurities such as surfactants, proteins and colloidal particles. In many...