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Influence of novel surface modifying macromolecules and coagulation media on the gas permeation properties of different polymeric gas separation membranes
, Article Journal of Applied Polymer Science ; Volume 124, Issue 3 , 2012 , Pages 2300-2310 ; 00218995 (ISSN) ; Rana, D ; Matsuura, T ; Soltanieh, M ; Tabe, S ; Sharif University of Technology
2012
Abstract
Integrally skinned asymmetric membranes for the separation of O 2 and N 2 were fabricated by the phase inversion technique from polysulfone, polyetherimide, and polyimide. Two types of surface modifying macromolecules (SMMs) including hydrophilic SMM (LSMM) and charged SMM (cSMM) were synthesized and blended with the casting solution to modify the membrane surface. The cast film was then immersed in the first coagulant alcohol (methanol, ethanol, or isopropanol) for a predetermined period, before being immersed in the second coagulant (water). The SMMs used in these experiments were laboratory synthesized by the two-step process of polyurethane prepolymer synthesis and end capping, before...
On the instability of spinning cylindrical shells partially filled with liquid
, Article International Journal of Structural Stability and Dynamics ; Volume 12, Issue 3 , 2012 ; 02194554 (ISSN) ; Permoon, M. R ; Haddadpour, H ; Sharif University of Technology
Abstract
The dynamics and stability of rotating circular cylindrical shells partially filled with ideal liquid is analyzed. The structural dynamics of the shell is modeled by using the first-order shear deformable shell theory and the flow inside the cylinder is simulated by a quasi 2D model based on the NavierStokes equations for ideal liquid. The fluid and structural models are combined using the nonpenetration condition of the flow on the wetted surface of the cylinder and the fluid pressure on the flexible shell. The obtained fluidstructure model is employed for the determination of the stable regions of the spinning frequency of the cylinder. A series of case studies are performed on the...
Experimental investigation of matrix wettability effects on water imbibition in fractured artificial porous media
, Article Journal of Petroleum Science and Engineering ; Volume 86-87 , 2012 , Pages 165-171 ; 09204105 (ISSN) ; Ayatollahi, S ; Rostami, B ; Sharif University of Technology
Abstract
Spontaneous water imbibition into the matrix blocks is known as the main mechanism for increased oil recovery from naturally fractured oil reservoirs. The rate of oil recovery and its ultimate value is mostly affected by wettability of the rocks and their pore structure. Oil viscosity also greatly influences the rate of oil recovery. A novel experimental model was utilized to study the imbibition mechanism under different wettability conditions. Matrix blocks made from different grain types and size distributions of glass beads were saturated with two different types of synthetic oil, to mimic the oil-saturated matrixes. The wetting characteristic of the models used in this study were...
Preparation and characterisation of diopside-based glass-ceramic foams
, Article Ceramics International ; Volume 38, Issue 3 , 2012 , Pages 2005-2010 ; 02728842 (ISSN) ; Nemati, A ; Eftekhari Yekta, B ; Alizadeh, P ; Sharif University of Technology
2012
Abstract
Foaming and crystallisation behaviours of compacted glass powders based on a diopside glass-ceramic composition were investigated using the sintering route. The foaming agent was 2 wt.% SiC particles. The effect of PbO on the foaming ability of glasses was investigated. The results showed that the addition of PbO not only improved the foaming ability, by improving the wettability of the glass-SiC particles but also increased the crystallisation temperature and widened the temperature interval between the dilatometric softening point and the onset of crystallisation. The glass-SiC wetting angle was decreased from 85°for the lead-free glass, to 55°for the glass that contains 15 wt.% PbO
Effect of cobalt replacement by nickel on functionally graded cemented carbonitrides
, Article International Journal of Refractory Metals and Hard Materials ; Volume 30, Issue 1 , January , 2012 , Pages 42-47 ; 02634368 (ISSN) ; Abachi, P ; Pourazarang, K ; Sharif University of Technology
2012
Abstract
Functionally graded cemented carbonitrides (FGCCs) are applied in cutting tools industry. Indexable inserts made from mentioned alloys have superior cutting performance and tool life thanks the formation of a surface modified layer with enhanced properties as well as crater wear resistance. Cemented carbonitrides are made of hard carbide/nitride/carbonitride particles that have been embedded in a metallic binder. Excellent wetting ability of tungsten carbide with cobalt has made this metal the first choice as binder. However, cobalt has high cost and environmental pollution impacts. Substitution of cobalt with other metals has always been figured out. Some other metals that have been used as...
Analytical solutions for the static instability of Micro/Nano mirrors under the combined effect of capillary force and Casimir force
, Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, Denver, CO, 11 November 2011 through 17 November 2011 ; Volume 11 , November , 2011 , Pages 463-469 ; 9780791854976 (ISBN) ; Darvishian, A ; Ahmadian, M. T ; Sharif University of Technology
2011
Abstract
This paper deals with the problem of static instability of Micro/Nano mirrors under the combined effect of capillary force and Casimir force. At the First the governing equations of the statical behavior of Micro/Nano mirrors under the combined effect of capillary force and casimir force is obtained. The dependency of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that existence of casimir force can considerably reduce the stability limits of nano/micromirror. It is also found that rotation angle of the mirror due to capillary force highly depends on the casimir force applied to the...
Hydro-mechanical modeling of two-phase fluid flow in deforming, partially saturated porous media with propagating cohesive cracks using the extended finite element method
, Article Computational Plasticity XI - Fundamentals and Applications, COMPLAS XI, 7 September 2011 through 9 September 2011 ; September , 2011 , Pages 1516-1527 ; 9788489925731 (ISBN) ; Khoei, A. R ; Sharif University of Technology
Abstract
In the present paper, a fully coupled numerical model is developed for the hydromechanical analysis of deforming, progressively fracturing porous media interacting with the flow of two immiscible, compressible wetting and non-wetting pore fluids. The governing equations involving the coupled two-phase fluid flow and deformation processes in partially saturated porous media containing cohesive cracks are derived within the framework of the generalized Biot theory. The displacement of the solid phase, the pressure of the wetting phase and the capillary pressure are taken as the primary unknowns of the three-phase formulation. A softening cohesive law is employed to describe the nonlinear...
Molecular dynamics simulation of nano channel as nanopumps
, Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011, Edmonton, AB ; Volume 2 , 2011 , Pages 223-227 ; 9780791844649 (ISBN) ; Abbasi, H. R ; Khaledi Alidusti, R ; Sabouri, M ; Schneider, G. E ; Sharif University of Technology
Abstract
We use three-dimensional molecular dynamics simulation to investigate the driven flow between two parallel plates separated by argon atoms. Our simulations show that fluids in such channels can be continuously driven. Difference in surface wettability can cause a difference in fluid density along the nano channel. To control the nanochannel temperature walls, we use the thermal wall idea, which models the walls using atoms connected to their original positions by enforcing linear spring forces. In this study, we propose a nanochannel system in which, half of the channel has a low surface wettability, while the other half has a higher surface wettability and that the middle part of channel...
Modeling of catalyst deactivation in catalytic wet air oxidation of phenol in fixed bed three-phase reactor
, Article World Academy of Science, Engineering and Technology ; Volume 73 , 2011 , Pages 604-609 ; 2010376X (ISSN) ; Kazemeini, M ; Khorasheh, F ; Fattahi, M ; Sharif University of Technology
Abstract
Modeling and simulation of fixed bed three-phase catalytic reactors are considered for wet air catalytic oxidation of phenol to perform a comparative numerical analysis between tricklebed and packed-bubble column reactors. The modeling involves material balances both for the catalyst particle as well as for different fluid phases. Catalyst deactivation is also considered in a transient reactor model to investigate the effects of various parameters including reactor temperature on catalyst deactivation. The simulation results indicated that packed-bubble columns were slightly superior in performance than trickle beds. It was also found that reaction temperature was the most effective...
A coupled model between torsion and bending in nano/micromirrors under the combined effect of Van der Waals force and capillary force
, Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 11 November 2011 through 17 November 2011, Denver, CO ; Volume 11 , 2011 , Pages 523-529 ; 9780791854976 (ISBN) ; Darvishian, A ; Ahmadian, M. T ; ASME ; Sharif University of Technology
Abstract
The coupling effect between torsion and bending in nano/micromirrors under the combined effect of capillary force and van der Waals (vdW) force is presented in this paper. At the first, the dimensionless equations governing the statical behavior of the nano/micromirror are obtained using the minimum total potential energy principle. Then the equations governing the pull-in state of the mirror are obtained using the implicit function theorem. The related results show that neglecting bending effect can lead to considerable overestimation in predicting the pull-in limits of the nano/micromirror under combined vdW and capillary forces. It is observed that vdW force reduces the pull-in angle and...
Closed form solutions for the problem of statical behavior of nano/micromirrors under the effect of capillary force and van der Waals force
, Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 11 November 2011 through 17 November 2011, Denver, CO ; Volume 11 , 2011 , Pages 213-219 ; 9780791854976 (ISBN) ; Moeenfard, H ; Zohoor, H ; Ahmadian, M. T ; ASME ; Sharif University of Technology
2011
Abstract
The current paper deals with the problem of static instability of Micro/Nano mirrors under the combined effect of capillary force and van der Waals force. First the governing equations of the statical behavior of Micro/Nano mirrors under the combined effect of capillary force and casimir force is obtained using the newtons first law of motion. The dependence of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that existence of vdW torque can considerably reduce the stability limits of the nano/micromirror. It is also found that rotation angle of the mirror due to capillary force...
Supercritical gasification of biomass: Thermodynamics analysis with Gibbs free energy minimization
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 34, Issue 2 , Dec , 2011 , Pages 163-176 ; 15567036 (ISSN) ; Pazuki, G. R ; Vossoughi, M ; Saboohi, Y ; Hashemi, N ; Sharif University of Technology
2011
Abstract
Gasification of biomass in supercritical water is a successful technology for hydrogen production especially by using wet biomass. The whole process, from feeding to purification of hydrogen, consists of a lot of equipment, such as pumps, heat exchangers, heaters, reactors, etc. Because the main reactions take place in the gasification reactor, the gasifier is the most important equipment of the process. In this article, a thermodynamic model, including chemical equilibrium in the reactor that is based on Gibbs free energy minimization, is developed to estimate equilibrium composition for gasification of biomass in supercritical water for hydrogen production. For this analysis, we use three...
Novel silver nano-wedges for killing microorganisms
, Article Materials Research Bulletin ; Volume 46, Issue 11 , 2011 , Pages 1860-1865 ; 00255408 (ISSN) ; Soleyman, R ; Sharif University of Technology
Abstract
In the current study, for the first time, photochemical facile green synthesis of salep capped silver nano-wedges was reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing agent caused mild reduction of silver ions to the silver nano-wedges. Salep as an effective capping/shaping polysaccharide bioresource material was used in the reaction medium and caused creation of flower-like self-assembled structures of the silver nano-wedges. The formation of silver nano-wedges and their flower-like self-assembled structures was confirmed by SEM technique. Further investigations were carried out using UV-vis, FTIR, GPC and XRD data. The prepared silver nano-wedges...
Modeling of Pull-In Instability of Nano/Micromirrors Under the Combined Effect of Capillary and Casimir Forces
, Article International Journal of Optomechatronics ; Volume 5, Issue 4 , Dec , 2011 , Pages 378-392 ; 15599612 (ISSN) ; Darvishian, A ; Ahmaidan, M. T ; Sharif University of Technology
2011
Abstract
In the current article the effect of the Casimir force on the static behavior and pull-in characteristics of nano/micromirrors under capillary force is investigated. At the first, the dimensionless equation governing the static behavior of nano/micromirrors is obtained. The dependency of the critical tilting angle on the physical and geometrical parameters of the nano/micromirror and its supporting torsional beams is investigated. It is found that the Casimir effect can considerably reduce the pull-in instability limits of the nano/micromirror. It is also found that rotation angle of the mirror under capillary force highly depends on the Casimir force applied to the mirror. Finally the...
Silver nanoparticles with gelatin nanoshells: Photochemical facile green synthesis and their antimicrobial activity
, Article Journal of Nanoparticle Research ; Volume 13, Issue 10 , October , 2011 , Pages 4647-4658 ; 13880764 (ISSN) ; Soleyman, R ; Sharif University of Technology
2011
Abstract
In the current study, a facile green synthesis of silver-gelatin core-shell nanostructures (spherical, spherical/cubic hybrid, and cubic, DLS diameter: 4.1-6.9 nm) is reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing agent cause mild reduction of silver ions into the silver nanoparticles (Ag-NPs). Gelatin protein, as an effective capping/shaping agent, was used in the reaction to self-assemble silver nanostructures. The formation of silver nanostructures and their self-assembly pattern was confirmed by SEM, AFM, and TEM techniques. Further investigations were carried out using zeta-potential, UV-Vis, FTIR, GPC, and TGA/DTG/DTA data. The prepared Ag-NPs...
Energy consumption criteria and labeling program of wet cooling towers in Iran
, Article Energy and Buildings ; Volume 43, Issue 10 , October , 2011 , Pages 2712-2717 ; 03787788 (ISSN) ; Sajadi, B ; Sayyadi, P ; Sharif University of Technology
2011
Abstract
Increasing concerns about the lack of energy resources, global warming and environmental pollution have pushed the relevant organizations to develop energy saving strategies such as energy labeling programs. In this research, a new energy labeling program is developed and evaluated for the wet cooling towers in Iran. The cooling tower parameters, including its cooling capacity and the fan power consumption, are measured using an experimental setup. The experimental data are standardized to compensate the effect of the ambient wet bulb temperature on the cooling tower performance which cannot be controlled during the experiments. The results show that the cooling tower capacity and the fan...
The effect of microstructure on the photocatalytic properties of TiO2
, Article Advanced Materials Research, 26 October 2009 through 29 October 2009 ; Volume 264-265 , 2011 , Pages 1340-1345 ; 10226680 (ISSN) ; 9783037850534 (ISBN) ; Kianpour Rad, M ; Sadrnezhaad, S. K ; Vaezi, M. R ; Sharif University of Technology
2011
Abstract
Titanium dioxide is a cheap, chemically stable and non-toxic material. However its photocatalytic properties are unstable and it is a modest semiconductor and a mediocre insulator. For several applications it would be interesting to make it either more insulating or more conducting. The goal of this work was to modify the photocatalytic properties of nano-crystalline TiO2 powders by wet chemical routes and hydrothermal methods to understand the mechanism leading to these modifications The principal factors that influence the photocatalytic properties are on the one hand the concentration and nature of the chemical and physical conditions in TiO2, and on the other hand the morphology of the...
Quantifying the role of pore geometry and medium heterogeneity on heavy oil recovery during solvent/Co-solvent flooding inwater-wet systems
, Article Journal of Porous Media ; Volume 14, Issue 4 , 2011 , Pages 363-373 ; 1091028X (ISSN) ; Kharrat, R ; Ghazanfari, M. H ; Vossoughi, S ; Sharif University of Technology
Abstract
Porous medium characteristics (e.g., pore geometry and medium heterogeneity) as well as the chemical nature of the co-solvents crucially affect the oil displacement efficiency during solvent flooding processes. In this work, initially saturated models with heavy crude oil were used to perform a series of solvent injection experiments. Several onequarter five-spot micromodels with pre-designed pore geometry were constructed and used. In addition, rock-look-alike flow patterns generated from thin sections of sandstone and dolomite reservoir rocks were etched onto glass plates to form micromodels mimicking the pore geometry and heterogeneity of these rocks. Four different groups of chemicals...
Numerical study of factors influencing relative permeabilities of two immiscible fluids flowing through porous media using lattice Boltzmann method
, Article Journal of Petroleum Science and Engineering ; Volume 77, Issue 1 , 2011 , Pages 135-145 ; 09204105 (ISSN) ; Pak, A ; Sharif University of Technology
Abstract
Relative permeability curves have practical implications in petroleum reservoir simulations. Study of the effects of reservoir wettability, pore shape geometry, and viscosity ratio of flowing fluids on the relative permeabilities is of great importance in reservoir modeling. In this paper, lattice Boltzmann method (LBM) is employed for analyzing the two-fluid flow in rigid porous media. The developed LBM code proved to be a robust numerical tool for analyzing the factors that influence the relative permeabilities of two immiscible fluids flowing through porous media. The numerically derived relative permeability curves demonstrate that in neutrally wet reservoirs, the effect of viscosity...
Pore-Scale Monitoring of Wettability Alteration by Silica Nanoparticles During Polymer Flooding to Heavy Oil in a Five-Spot Glass Micromodel
, Article Transport in Porous Media ; Volume 87, Issue 3 , 2011 , Pages 653-664 ; 01693913 (ISSN) ; Mohebbi, A ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
Abstract
It is well known that the oil recovery is affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of medium surfaces has remained a topic of debate in the literature. Furthermore, there is a little information of the way dispersed silica nanoparticles affect the oil recovery efficiency during polymer flooding, especially, when heavy oil is used. In this study, a series of injection experiments were performed in a five-spot glass micromodel after saturation with the heavy oil. Polyacrylamide solution and dispersed silica nanoparticles in polyacrylamide (DSNP) solution were used as injected fluids. The oil recovery as well as fluid distribution in...