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Simulation of three different double-fiber probes for reflection sensing
, Article Journal of Applied Sciences ; Volume 10, Issue 1 , 2010 , Pages 20-28 ; 18125654 (ISSN) ; Golnabi, H ; Sharif University of Technology
Abstract
In this study simulation results for three double-fiber optical designs for the reflection measurements are reported. Modeling is perused for three cases namely Equal Fibers (EF), transmitter fiber shorter (TS) and receiver fiber shorter (RS) designs. By proper modeling and written programs the operations of such symmetric double-fiber probes are simulated and the role of different crucial parameters such as fiber-to-fiber distance (t), fiber core radius (r) and fiber Numerical Aperture (NA) are investigated. In the second study simulation results for the transmitter fiber shorter and receiver fiber shorter designs are investigated for different fiber length differences (w). Finally...
Electrophoretic deposition of Ni/SiO2 nanocomposite coating: Fabrication process and tribological and corrosion properties
, Article Journal of Nano Research ; Volume 26 , 6 January , 2014 , Pages 45-51 ; ISSN: 16625250 ; Ghorbani, M ; Sharif University of Technology
Abstract
To the best of our knowledge, this work presents the first successful effort to fabricate and study nanostructured Ni-based composite coatings using the electrophoretic deposition method with nanostructured SiO2 particles. In this work, Ni/SiO2 nanoparticle composite coatings were prepared by electrophoretic deposition (EPD) [1] and their hardness, wear and corrosion resistances [2] were examined. After studying the morphology of the coatings and finding the optimum conditions for uniform coating, in order to improve the mechanical properties as well as resistance to corrosion, sintering was performed. The Ni/SiO2 nanocomposite coatings show excellent hardness (∼376 HV), reduced Young's...
Experiments design for hardness optimization of the Ni-Cr alloy electrodeposited by pulse plating
, Article Acta Metallurgica Sinica (English Letters) ; Volume 26, Issue 5 , 2013 , Pages 558-564 ; 10067191 (ISSN) ; Yousefi, E ; Dolati, A ; Mohammadi, M. R ; Sharif University of Technology
2013
Abstract
The hardness of the Ni-Cr alloy which is electrodeposited in chloride solution, is optimized by design of experiment method (central composite design). Various parameters were evaluated in order to find significant factors in this process. Frequency, duty cycle, current density and temperature were selected as effective factors. Analyses of variance (ANOVA) were performed on the results of the designed experiments. The best model which can predict the hardness of the Ni-Cr alloy electrodeposits was found whereas the frequency and quadratic behaviour of the current density were the most significant model terms. Serious interaction of the current density with frequency and duty cycle also were...
A study of the water-gas shift reaction in Ru-promoted Ir-catalysed methanol carbonylation utilising experimental design methodology
, Article Chemical Engineering Science ; Volume 66, Issue 20 , October , 2011 , Pages 4798-4806 ; 00092509 (ISSN) ; Kazemeini, M ; Mohammadrezaee, A ; Sharif University of Technology
2011
Abstract
The water-gas shift reaction occurs competitively to the main reaction of the Ir-catalysed methanol carbonylation process. To study the effect of seven factors including temperature, pressure, iridium, ruthenium, methyl iodide, methyl acetate and water concentrations on the formation of hydrogen and carbon dioxide as a result of the water-gas shift reaction and other side reactions in the carbonylation of methanol to acetic acid, the experimental design method combined with response surface methodology (RSM) was utilised. Central composite design at five levels (with α=1.63) was used to design experiments. A quadratic model that included the main and interaction effects of variables for H 2...
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) ; Kazemeini, M ; Mohammadrezaee, A ; Sharif University of Technology
2011
Abstract
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...
A comprehensive study on the complete charging-discharging cycle of a phase change material using intermediate boiling fluid to control energy flow
, Article Journal of Energy Storage ; Volume 35 , 2021 ; 2352152X (ISSN) ; Mohammadi, O ; Faghiri, S ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
The low melting and solidification rates of phase change materials (PCM), which traces back to their low thermal conductivity coefficient, has led the application of these materials to face limitations. This paper aims to explore the effectiveness of a novel method called intermediate boiling fluid (IBF) in speeding up the energy storage and transfer processes in PCMs during a complete charging-discharging cycle. Throughout this novel technique, paraffin and acetone are utilized as PCM and IBF, respectively. In the solidification process, there is no direct contact between the cold source and the molten paraffin, while acetone, as an intermediate fluid, is being boiled via absorbing...
Highly sensitive turn-on fluorescent detection of captopril based on energy transfer between fluorescein isothiocyanate and gold nanoparticles
, Article Journal of Luminescence ; Volume 134 , 2013 , Pages 874-879 ; 00222313 (ISSN) ; Bagheri, H ; Bohloul, A ; Taheri, N ; Robatjazi, H ; Sharif University of Technology
2013
Abstract
A novel approach for highly sensitive detection of captopril was developed based on the fluorescence resonance energy transfer (FRET) between gold nanoparticles (Au NPs) and fluorescein isothiocyanate (FITC), in which FITC acts as the donor and Au NPs as the acceptor. The fluorescence intensity of fluorescein isothiocyanate (FITC) was strictly quenched as a result of noncovalently adsorbed on Au NPs. Upon the addition of captopril, the fluorescence intensity of FITC turn-on due to the competition between captopril and FITC towards the surface of Au NPs. Under the optimum conditions, the fluorescence intensity of the released FITC displays a linear relationship in the range of 20 μg L-1 to...
Simultaneous colorimetric determination of dopamine and ascorbic acid based on the surface plasmon resonance band of colloidal silver nanoparticles using artificial neural networks
, Article Analytical Methods ; Volume 2, Issue 9 , 2010 , Pages 1263-1269 ; 17599660 (ISSN) ; Tashkhourian, J ; Khodaveisi, J ; Khoshi, M. R ; Sharif University of Technology
2010
Abstract
A new method for simultaneous determination of dopamine (DA) and ascorbic acid (ASC) is proposed. The method is based on the reaction of dopamine and ascorbic acid with the oxidizing agent (silver nitrate) in the presence of PVP (as a stabilizer) and the formation of silver nanoparticles in a slightly basic medium. Spectrophotometry is used to monitor the changes of the surface plasmon resonance (SPR) band at a maximum wavelength of silver nanoparticles (440 nm) vs. time. Three-layered feed-forward artificial neural networks (ANN) trained by back propagation learning algorithm is used to model the relationship between absorbance and concentration to quantify analyte in mixtures under optimum...
Deep eutectic solvents: Cutting-edge applications in cross-coupling reactions
, Article Green Chemistry ; Volume 22, Issue 12 , 2020 , Pages 3668-3692 ; Afshari, R ; Ramón, D. J ; Varma, R. S ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
Deep eutectic solvents (DESs), surmised as "the organic reaction medium of the century", have reverberated a new symphony throughout the present green millennium. A brief historical account of the DES systems and their physicochemical properties as task-specific and designer solvents for cross-coupling reactions are appraised including the hole theory that explains the underlying mechanistic pathway for this emerging neoteric medium. The insights into cross-coupling reactions and their applications are included, highlighting the significant achievements pertaining to the dual role of DESs as a solvent and catalyst. In addition, popular "name-reactions"for the carbon-carbon and...
Determining and optimizing power loss reduction in distribution feeders due to Distributed generation
, Article 2006 IEEE PES Power Systems Conference and Exposition, PSCE 2006, Atlanta, GA, 29 October 2006 through 1 November 2006 ; 2006 , Pages 1914-1918 ; 142440178X (ISBN); 9781424401789 (ISBN) ; Parniani, M ; Sharif University of Technology
2006
Abstract
One of the beneficial impacts of Distributed generation (DG) units on electrical network is power loss reduction in the distribution feeder on which DG is located. In this paper the effect of DG on power losses of a distribution feeder with a combination of uniformly distributed and lumped loads is investigated, and a mathematical model of power loss reduction as a function of DG and the feeder parameters is extracted. Then, based on the derived formula, optimum conditions of utilizing and locating the DG units are obtained. © 2006 IEEE
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 ; Tahvildari, K ; Hemmati, A ; Aberoomand azar, P ; Safekordi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
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...
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 , 2021 ; 00162361 (ISSN) ; Tahvildari, K ; Hemmati, A ; Aberoomand azar, P ; Safekordi, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
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...
Experimental and simulation investigation on separation of binary hydrocarbon mixture by thermogravitational column
, Article Journal of Molecular Liquids ; Volume 268 , 2018 , Pages 791-806 ; 01677322 (ISSN) ; Karimi Sabet, J ; Motahari, K ; Mahruz Monfared, S ; Amini, Y ; Moosavian, M. A ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this article, experimental and numerical investigations are performed to study a thermogravitational column (TGC) for the separation of toluene/n-heptane mixture. This research has tried to determine the main significant parameters and their effects on the performance of the process. In experimental examinations, the influence of the main parameters such as feed flow rate, cut and temperature gradient on the performance of the TGC efficiency is studied. In addition, computational fluid dynamics is used to simulate the separation process in this review. The response surface methodology (RSM) was also applied to minimize the number of runs and investigate the optimum operating conditions....
Effective promotion of g–C3N4 photocatalytic performance via surface oxygen vacancy and coupling with bismuth-based semiconductors towards antibiotics degradation
, Article Chemosphere ; Volume 287 , 2022 ; 00456535 (ISSN) ; Moradi, M ; Aghaebrahimi Samani, S ; Kakavandi, B ; Rahman Setayesh, S ; Noorisepehr, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this research, the potential of bismuth chromate (BCO), a new bismuth-based semiconductor belongs to the family of Bi2XO6 (X = Mo, W, or Cr), was introduced by a novel 1D/2D structure consist of BCO nanobelts and N2-freezed ultra-wrinkled graphitic carbon nitride (N–CN) nanosheets. To enhance intimate contact between BCO and N–CN (BCO/N–CN composite), surface oxygen vacancy (VO) was created as an efficient electron transfer highway using a simple alkaline-treatment-assisted method. Various characterization techniques, including XRD, FT-IR, EPR, FE-SEM, TEM, BET, DRS, PL, EIS, and photocurrent transient analyses were conducted to elucidate the physicochemical aspects of catalysts. The...
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 ; Kazemeini, M ; Rashidi, A ; Seif, A ; Sharif University of Technology
Elsevier B.V
2020
Abstract
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...
Design and operation of a simple beam shaping system
, Article Journal of Applied Sciences ; Volume 9, Issue 18 , 2009 , Pages 3350-3356 ; 18125654 (ISSN) ; Golnabi, H ; Shakouri, M ; Sharif University of Technology
2009
Abstract
Design and performance of a beam shaping device based on a simple flexible plastic fiber-bundle stripe and a prism duct is described in this study. Such a system offers practical means to modify and change the output beam shape and also provides quantitative information concerning the transmitted power. It is possible to measure transmitted power signal by using a precise photodetector and also analyze beam images taken by a digital camera. The photograph picture of the illuminating LED beam just at its output point shows a circular shape with a radius of about 4 mm and the fiber-bundle output beam is rectangular shape with a dimension of 22.5×2 mm. A regular duct is tested in this study and...
Using three different optical fiber designs to study humidity effect on the air refractive index
, Article Optics and Lasers in Engineering ; Volume 50, Issue 11 , November , 2012 , Pages 1495-1500 ; 01438166 (ISSN) ; Sharif University of Technology
2012
Abstract
Design and operation of three different optical designs based on the light intensity modulation for investigation of the humidity effects on the air index of refraction are described. The measurement variable is the transmitted power, which depends on the refractive index of the medium in the path of a fiber-to-fiber optical design. Three different probes (probe #1, #2, and #3) are tested in which probe #1 and probe #2 can also check the presence of water or any other transparent liquid in the gap between the two axial fibers. Performances of the new systems are tested as a refractive index monitoring mean and experimental results are given. The variations of the modulated powers as...
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) ; Bahar, M ; Sharif University of Technology
2009
Abstract
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...
Optimum operating conditions for direct oxidation of h 2s in a fluidized bed reactor
, Article World Academy of Science, Engineering and Technology ; Volume 79 , 2011 , Pages 237-241 ; 2010376X (ISSN) ; Kazemeini, M ; Fattahi, M ; Amjadian, A ; Sharif University of Technology
2011
Abstract
In this research a mathematical model for direct oxidization of hydrogen sulfide into elemental sulfur in a fluidized bed reactor with external circulation was developed. As the catalyst is deactivated in the fluidized bed, it might be placed in a reduction tank in order to remove sulfur through heating above its dew point. The reactor model demonstrated via MATLAB software. It was shown that variations of H 2S conversion as well as; products formed were reasonable in comparison with corresponding results of a fixed bed reactor. Through analyzing results of this model, it became possible to propose the main optimized operating conditions for the process considered. These conditions included;...
Optimum operating conditions for direct oxidation of H2S in a fluidized bed reactor
, Article World Academy of Science, Engineering and Technology ; Volume 77 , 2011 , Pages 411-415 ; 2010376X (ISSN) ; Kazemeini, M ; Fattahi, M ; Amjadia, A ; Sharif University of Technology
Abstract
In this research a mathematical model for direct oxidization of hydrogen sulfide into elemental sulfur in a fluidized bed reactor with external circulation was developed. As the catalyst is deactivated in the fluidized bed, it might be placed in a reduction tank in order to remove sulfur through heating above its dew point. The reactor model demonstrated via MATLAB software. It was shown that variations of H 2S conversion as well as; products formed were reasonable in comparison with corresponding results of a fixed bed reactor. Through analyzing results of this model, it became possible to propose the main optimized operating conditions for the process considered. These conditions included;...