Search for: optimum-conditions
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    Optimisation of Ru-promoted Ir-catalysed methanol carbonylation utilising response surface methodology

    , Article Applied Catalysis A: General ; Volume 394, Issue 1-2 , February , 2011 , Pages 166-175 ; 0926860X (ISSN) Hosseinpour, V ; Kazemeini, M ; Mohammadrezaee, A ; Sharif University of Technology
    In this study, central composite design (CCD) at five levels (-1.63, -1, 0, +1, +1.63) combined with response surface methodology (RSM) have been applied to optimise methanol carbonylation using a ruthenium-promoted iridium catalyst in a homogenous phase. The effect of seven process variables, including temperature, pressure, iridium, ruthenium, methyl iodide, methyl acetate and water concentrations, as well as their binary interactions, were modelled. The determined R 2 values greater than 0.9 for the rate and methane formation data confirmed that the quadratic equation properly fitted the obtained experimental data. The optimum conditions for maximum rate and minimum methane formation were... 

    Modification and optimization of benzene alkylation process for production of ethylbenzene

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 50, Issue 1 , 2011 , Pages 31-36 ; 02552701 (ISSN) Ebrahimi, A. N ; Sharak, A. Z ; Mousavi, S. A ; Aghazadeh, F ; Soltani, A ; Sharif University of Technology
    In this paper, an industrial ethylbenzene production unit has been simulated and the results are compared against five-day experimental data. According to prevailing unit condition, i.e. recycled ratio of benzene, benzene selectivity, and energy consumption, the unit is not working under its optimum conditions for minimum cost of ethylbenzene production. In the current design, high amount of benzene recycle (6:1) causes to have an additional cost due to fractionation of ethylbenzene from benzene. A new approach is proposed to modify the benzene alkylation process and reduce the unit's energy consumption. In the newly designed scheme, two double-bed alkylation reactors converted into four... 

    Enhancement of fungal delignification of rice straw by Trichoderma viride sp. to improve its saccharification

    , Article Biochemical Engineering Journal ; Volume 101 , September , 2015 , Pages 77-84 ; 1369703X (ISSN) Ghorbani, F ; Karimi, M ; Biria, D ; Kariminia, H. R ; Jeihanipour, A ; Sharif University of Technology
    Elsevier  2015
    Fungal delignification can be considered as a feasible process to pre-treat lignocellulosic biomass in biofuel production, if its performance is improved in terms of efficiency thorough a few modifications. In this study, Trichoderma viride was utilized to investigate the effect of wet-milling, addition of surfactant (Tween 80) and optimization of operating factors such as temperature, biomass to liquid medium ratio and glucose concentration on biodelignification of rice straw. Next, the enzymatic hydrolysis of pretreated biomass was studied at various pretreatment times. Results revealed that the wet milling and addition of surfactant increases the lignin removal about 15% and 11%,... 

    Refined microstructure of compo cast nanocomposites: the performance of combined neuro-computing, fuzzy logic and particle swarm techniques

    , Article Neural Computing and Applications ; Volume 26, Issue 4 , May , 2015 , Pages 899-909 ; 09410643 (ISSN) Ostad Shabani, M ; Rahimipour, M. R ; Tofigh, A. A ; Davami, P ; Sharif University of Technology
    Springer-Verlag London Ltd  2015
    Aluminum metal matrix composites (MMCs) reinforced with nanoceramics are ideal materials for the manufacture of lightweight automotive and other commercial parts. Adaptive neuro-fuzzy inference system combined with particle swarm optimization method is implemented in this research study in order to optimize the parameters in processing of aluminum MMCs. In order to solve the problems associated with poor wettability, agglomeration and gravity segregation of nanoparticles in the melt, a mixture of alumina and aluminum particles was used as the reinforcement instead of raw nanoalumina. Microstructural characterization shows dendritic microstructure for the sand cast and non-dendritic... 

    Investigation and optimization of SDS and key parameters effect on the nickel electroless coatings properties by Taguchi method

    , Article Journal of Coatings Technology Research ; Volume 7, Issue 5 , 2010 , Pages 547-555 ; 15470091 (ISSN) Farzaneh, A ; Ehteshamzadeh, M ; Ghorbani, M ; Vazifeh Mehrabani, J ; Sharif University of Technology
    In this research, the influence of anionic surfactant sodium dodecyl sulfate (SDS), pH, substrate finishing, and annealing temperature on the surface morphology and hardness of the electroless nickel phosphorus (ENi-P) coatings were studied. Taguchi's experimental design method was used. Parameters selected in three levels and L9 from orthogonal robust array design were employed. Surface roughnesses of the deposits were measured using a stylus instrument. Scanning electron microscope and x-ray diffraction analysis were implemented to study surface morphologies and phase composition, respectively. Microhardness of the ENi-P deposits was measured using a microhardness tester at three trials... 

    Optimization of parameters for synthesis of mfi nanoparticles by taguchi robust design

    , Article Chemical Engineering and Technology ; Volume 33, Issue 6 , 2010 , Pages 902-910 ; 09307516 (ISSN) Torkman, R ; Soltanieh, M ; Kazemian, H ; Sharif University of Technology
    MFI-type zeolite was successfully synthesized by hydrothermal crystallization of clear synthesis mixtures. A statistical experimental design method (the Taguchi method with an L8 orthogonal array) was implemented to optimize the experimental conditions for the preparation of MFI nanocrystals with respect to particle size and distribution as the desirable properties. In the Taguchi experimental design, crystallization temperature, water content, template/silica molar ratio, aluminum content, as well as the presence of alkaline cations were chosen as significant parameters affecting the properties. It was shown that water and aluminum content of the synthesis solution were the most important... 

    Newly developed technique to eliminate hot cracking with electromagnetic vibration for joining of 2024 aluminum alloy

    , Article Metallography, Microstructure, and Analysis ; Volume 5, Issue 1 , 2016 , Pages 7-15 ; 21929262 (ISSN) Nikzad, S ; Ashuri, H ; Kokabi, A. H ; Shafizadeh, M ; Ferasat, K ; Sharif University of Technology
    Springer New York LLC 
    In this study, the effect of electromagnetic vibration on joining of aluminum alloy 2024 was investigated. Simultaneously applying a static magnetic field and alternating electrical current passing through a conductor produced electromagnetic vibration. Joining was accomplished using constant electric current (60 A) and the magnetic flux of 75, 110, and 145 mT in the presence of argon gas. After joining, samples were cooled first by argon gas as a shielding gas and then by water. The microstructure and mechanical properties of the welded samples were studied for different electromagnetic vibrations. The optimum microstructure and mechanical properties were obtained when applied... 

    Surface and mechanical properties of modified porous titanium scaffold

    , Article Surface and Coatings Technology ; Volume 315 , 2017 , Pages 61-66 ; 02578972 (ISSN) Khodaei, M ; Valanezhad, A ; Watanabe, I ; Yousefi, R ; Sharif University of Technology
    The bioinertness makes surface treatments essential to improve the bioactivity of porous titanium scaffold, and surface treatment might affect their mechanical properties. So finding an optimum condition lying between bioactivity and mechanical properties seems to be curial. In this research, the effect of the time of the thermal oxidation at 600 °C on apatite formation and mechanical properties of the porous titanium scaffold was studied. The results of thin film X-ray diffraction and Raman spectroscopy indicated that the surface of heat treated samples up to 480 min was mainly covered by rutile. Also, wettability measurement and in vitro apatite formation ability assessment indicated that... 

    Performance improvement of a supersonic external compression inlet by heat source addition

    , Article World Academy of Science, Engineering and Technology ; Volume 40 , 2009 , Pages 267-274 ; 2010376X (ISSN) Soltani, M. R ; Farahani, M ; Sepahi Younsi, J ; Sharif University of Technology
    Heat source addition to the axisymmetric supersonic inlet may improve the performance parameters, which will increase the inlet efficiency. In this investigation the heat has been added to the flow field at some distance ahead of an axisymmetric inlet by adding an imaginary thermal source upstream of cowl lip. The effect of heat addition on the drag coefficient, mass flow rate and the overall efficiency of the inlet have been investigated. The results show that heat addition causes flow separation, hence to prevent this phenomena, roughness has been added on the spike surface. However, heat addition reduces the drag coefficient and the inlet mass flow rate considerably. Furthermore, the... 

    Irradiation synthesis of biopolymer-based superabsorbent hydrogel: optimization using the taguchi method and investigation of its swelling behavior

    , Article Advances in Polymer Technology ; Volume 28, Issue 2 , 2009 , Pages 131-140 ; 07306679 (ISSN) Rezanejade Bardajee, G ; Pourjavadi, A ; Soleyman, R ; Sharif University of Technology
    In this report, the synthesis of a novel superabsorbent hydrogel via γ-irradiation graft copolymerization of acrylamide onto sodium alginate and kappa-carrageenan hybrid backbones in a homogeneous solution is described. The Taguchi method was used as a powerful experimental design tool for synthesis optimization. A series of superabsorbent hydrogels was synthesized by proposed conditions of Qualitek-4 software. Considering the results of nine trials according to analysis of variance, optimum conditions were proposed. The swelling behavior of optimum superabsorbent hydrogels was studied in various solutions, with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in... 

    Synthesis and swelling behavior of a new superabsorbent hydrogel network based on polyacrylamide grafted onto salep

    , Article Journal of Applied Polymer Science ; Volume 112, Issue 5 , 2009 , Pages 2625-2633 ; 00218995 (ISSN) Pourjavadi, A ; Rezanejade Bardajee, G ; Soleyman, R ; Sharif University of Technology
    Synthesis and swelling behavior of a new superabsorbent hydrogel based on natural salep grafted with Polyacrylamide is described. The new superabsorbent hydrogel biopolymer was synthesized via radical crosslink-ing and graft copolymerization of acrylamide monomer onto salep backbones. Regarding to the water absorption of hydrogel, the best synthesis condition is reported. FTIR spectroscopy and thermogravimetric analysis were used to confirm the structure of the final product and a mechanism for superabsorbent hydrogel formation was also suggested. After preparing the desired hydrogels based on optimum condition, several factors affecting the swelling behavior of hydrogel including pH of... 

    Investigation of optimum condition in oxygen gas-assisted laser cutting

    , Article Optics and Laser Technology ; Volume 41, Issue 4 , 2009 , Pages 454-460 ; 00303992 (ISSN) Golnabi, H ; Bahar, M ; Sharif University of Technology
    Laser cutting characteristics including power level and cutting gas pressure are investigated in order to obtain an optimum kerf width. The kerf width is investigated for a laser power range of 50-170 W and a gas pressure of 1-6 bar for steel and mild steel materials. Variation of sample thickness, material type, gas pressure and laser power on the average cut width and slot quality are investigated. Optimum conditions for the steel and mild steel materials with a thickness range of 1-2 mm are obtained. The optimum condition for the steel cutting results in a minimum average kerf width of 0.2 mm at a laser power of 67 W, cutting rate of 7.1 mm/s and an oxygen pressure of 4 bar. A similar... 

    Synthesis of composite coating containing tio2 and ha nanoparticles on titanium substrate by ac plasma electrolytic oxidation

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 50, Issue 7 , 2019 , Pages 3310-3319 ; 10735623 (ISSN) Soleymani Naeini, M ; Ghorbani, M ; Chambari, E ; Sharif University of Technology
    Springer Boston  2019
    In this study, biocompatible ceramic layers containing TiO2 and hydroxyapatite (HA) nanoparticles (TiO2/HA) were deposited on pure commercial titanium (Grade 2) by using plasma electrolytic oxidation and AC power supply. The coating process was carried out in five different solutions for various times at a current density of 500 mA cm−2. To achieve the optimum conditions for thickness and microstructure, the coating process was conducted in solutions with a 3 g L−1 concentration of HA nanoparticles. FESEM, XRD, and FTIR results showed that HA nanoparticles were successfully incorporated into the pores of the layer. Furthermore, the corrosion behavior of the coating layers in the simulated... 

    The oxidative desulfurization process performed upon a model fuel utilizing modified molybdenum based nanocatalysts: Experimental and density functional theory investigations under optimally prepared and operated conditions

    , Article Applied Surface Science ; Volume 527 , 2020 Hasannia, S ; Kazemeini, M ; Rashidi, A ; Seif, A ; Sharif University of Technology
    Elsevier B.V  2020
    CoMo/reduced graphene oxide (rGO) catalyst was synthesized for the oxidative desulfurization process (ODS) of dibenzothiophene (DBT) in n-decane. Parameters including total metal (Co and Mo) loading, Co/Mo and CA (citric Acid)/Mo molar ratios were investigated toward achieving optimum conditions. The catalysts were characterized by the XRD, ICP, FTIR, Raman Spectroscopy, BET-BJH, NH3-TPD, XPS, and TEM methods. The product sulfur content was measured by the ICP-OES while the product was evaluated using FTIR and 1H NMR analyses. All experimental stages were designed using Design-Expert software. High BET area, acidity, uniform particle size, and Co-promoter played key roles in this... 

    Phosphomolybdic acid/graphene oxide as novel green catalyst using for biodiesel production from waste cooking oil via electrolysis method: optimization using with response surface methodology (RSM)

    , Article Fuel ; Volume 287 , March , 2021 Helmi, M ; Tahvildari, K ; Hemmati, A ; Aberoomand azar, P ; Safekordi, A ; Sharif University of Technology
    Elsevier Ltd  2020
    In this study, biodiesel (FAME) was prepared using a novel heterogeneous catalyst of phosphomolybdic acid (H3PMo12O40, HPMo)/support graphene oxide (GO). The characterization of the catalyst was evaluated by SEM, EDX, Map analysis, TEM, FT-IR, and Raman analyses. The production of biodiesel from waste cooking oil (WCO) was carried out by the electrolysis method. The process of the trans-esterification reaction was optimized by applying the response surface methodology (RSM) based on the central composite design (CCD) approach. The effects of four independent variables of methanol to oil molar ratio (6–12 mol:mol), catalyst weight (0.5–1.5 wt%), time (8–24 h), and voltage (30–70 V) were... 

    Synthesis and characterization of bagasse poly(methyl methacrylate) graft copolymer

    , Article Macromolecular Symposia ; Volume 274, Issue 1 , 2008 , Pages 49-54 ; 10221360 (ISSN) Sarvi, I ; Pourjavadi, A ; Noei Aghaei, M. A ; Sharif University of Technology
    Graft copolymerization of methyl methacrylate (MMA) was carried out on bagasse fibers in an aqueous medium using eerie ammonium nitrate (CAN) as initiator under a neutral atmosphere. In order to obtain the optimum condition for graft copolymerization, the effects of initiator concentration, temperature, time of reaction, and monomer concentration were studied. The maximum grafting percent was found to be 122%. The bagasse grafted poly(methyl methacrylate) was characterized by FTIR and its thermal behavior was characterized by TGA. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA  

    New ellipsoid cavity model for high-intensity laser-plasma interaction

    , Article Plasma Devices and Operations ; Volume 16, Issue 2 , 2008 , Pages 105-114 ; 10519998 (ISSN) Zobdeh, P ; Sadighi Bonabi, R ; Afarideh, H ; Sharif University of Technology
    In this work we present an ellipsoid cavity regime for the production of a bunch of quasi-monoenergetic electrons. The electron output beam is more effective than the periodic plasma wave method or the plasma-channel-guided method. A hyperbola, parabola or ellipsoid path is described for the electron trajectory motion in this model. A dense bunch of relativistic electrons with a quasi-monoenergetic spectrum is self-generated here. The obtained results show a smaller width for the electron energy spectrum in comparison with the previous results. We found that there are optimum conditions to form the ellipsoid cavity. Laser beam properties (such as the spot size, power and pulse duration) and... 

    Numerical analysis of two-phase flow in heterogeneous porous media during pre-flush stage of matrix acidizing: Optimization by response surface methodology

    , Article Physics of Fluids ; Volume 33, Issue 5 , 2021 ; 10706631 (ISSN) Sabooniha, E ; Rokhforouz, M. R ; Kazemi, A ; Ayatollahi, S ; Sharif University of Technology
    American Institute of Physics Inc  2021
    Oil trapping behavior during the pre-flush stage is critically important to evaluate the effectiveness of matrix acidizing for the oil well stimulation. In this study, the visco-capillary behavior of the two-phase flow in the pore-scale is analyzed to investigate the influence of wetting properties for a natural rock sample. A two-dimensional model, based on Cahn-Hilliard phase-field and Navier-Stokes equations, was established and solved using the finite element method. A stability phase diagram for log capillary number (Ca)-log viscosity ratio (M) was constructed and then compared with the reported experimental works. The maximum and minimum ranges of capillary number and viscosity ratio... 

    Flash photo stimulation of human neural stem cells on graphene/TiO 2 heterojunction for differentiation into neurons

    , Article Nanoscale ; Volume 5, Issue 21 , 2013 , Pages 10316-10326 ; 20403364 (ISSN) Akhavan, O ; Ghaderi, E ; Sharif University of Technology
    For the application of human neural stem cells (hNSCs) in neural regeneration and brain repair, it is necessary to stimulate hNSC differentiation towards neurons rather than glia. Due to the unique properties of graphene in stem cell differentiation, here we introduce reduced graphene oxide (rGO)/TiO2 heterojunction film as a biocompatible flash photo stimulator for effective differentiation of hNSCs into neurons. Using the stimulation, the number of cell nuclei on rGO/TiO2 increased by a factor of ∼1.5, while on GO/TiO2 and TiO2 it increased only ∼48 and 24%, respectively. Moreover, under optimum conditions of flash photo stimulation (10 mW cm-2 flash intensity and 15.0 mM ascorbic acid in... 

    Thermodynamic analysis of application of organic Rankine cycle for heat recovery from an integrated DIR-MCFC with pre-reformer

    , Article Energy Conversion and Management ; Volume 67 , 2013 , Pages 197-207 ; 01968904 (ISSN) Vatani, A ; Khazaeli, A ; Roshandel, R ; Panjeshahi, M. H ; Sharif University of Technology
    This work deals with waste heat recovery from a proposed direct internal reforming molten carbonate fuel cell (DIR-MCFC), including an integrated pre-reformer. In this regard, some advantages are attainable over exhaust gas recycling. For instance, due to low temperature in the pre-reformer, carbon deposition and coke formation resulting from higher hydrocarbons can be eliminated. In this study, the cathode outlet provides the heat requirement for the pre-reforming process. After partial heat recovery from the cathode outlet, the stream still has a considerable energy and exergy (352.55 °C and 83.687 kW respectively). This study investigates waste heat recovery from the proposed DIR-MCFC,...