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

    , Article Neural Computing and Applications ; 2014 ; ISSN: 09410643 Shabani, M. O ; Rahimipour, M. R ; Tofigh, A. A ; Davami, P ; Sharif University of Technology
    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... 

    Design and operation of a simple beam shaping system

    , Article Journal of Applied Sciences ; Volume 9, Issue 18 , 2009 , Pages 3350-3356 ; 18125654 (ISSN) Haghighatzadeh, A ; Golnabi, H ; Shakouri, M ; Sharif University of Technology
    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... 

    Production of biodiesel from waste frying oil using whole cell biocatalysts: Optimization of effective factors

    , Article Waste and Biomass Valorization ; Vol. 5, issue. 6 , 2014 , pp. 947-954 ; ISSN: 18772641 Ghaderinezhad, F ; Kariminia, H. R ; Yaghmaei, S ; Sharif University of Technology
    Using whole cell as a catalyst of enzymatic transesterification is a method to produce biodiesel with fewer drawbacks and at a lower cost. In the present study, biodiesel was produced by the reaction of waste frying oil with methanol in the presence of Rhizopus oryzae PTCC 5174 in both immobilized and free forms. Effect of four influencing factors including temperature, methanol to oil molar ratio, amount of biomass, and shaking speed was investigated. Response surface methodology was used to find the optimum conditions of the transesterification reaction. Each factor was set at three levels and the yield of the biodiesel was considered as the response. A quadratic equation was well-fitted... 

    Solvent-free synthesis of 3-benzylpyrano[3,2-c]pyran/chromene-2,5-diones via tandem reaction of 4-hydroxy-6-methyl-pyran-2-one and 4-hydroxycoumarin with Baylis-Hillman adduct acetates

    , Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 735-741 ; 1026-3098 ; 2345-3605 Matloubi Moghaddam, F ; Koushki Foroushani, B ; Lotfi Kalahroodi, E ; Sharif University of Technology
    4-hydroxycoumarin 2a and 4-hydroxy-6-methyl-pyran-2-one 2b were applied in a one-pot reaction with Baylis-Hillman adduct acetates 1 to form novel 3-benzylpyrano [3, 2-c] pyran-2, 5-diones 3 in high yields (70-85%). The synthesized framework is available in many biologically active moieties. The reaction was carried out under different conditions to achieve optimum conditions. The results indicated that Et3N, as a base under solvent-free conditions, was optimum. The reaction procedure and purification method are mild and straightforward  

    Optimization of a vanillin assay for determination of anthocyanins using D-optimal design

    , Article Analytical Methods ; Volume 4, Issue 3 , Feb , 2012 , Pages 824-829 ; 17599660 (ISSN) Khoshayand, M. R ; Roohi, T ; Moghaddam, G ; Khoshayand, F ; Shahbazikhah, P ; Oveisi, M. R ; Hajimahmoodi, M ; Sharif University of Technology
    The vanillin assay is a spectrophotometric method for anthocyanin determination that is simple, quick and inexpensive. The method is preferred because of its high sensitivity, specificity and simplicity; however, the results of this test are influenced by several factors. Hence, a D-optimal experimental design approach was investigated to simultaneously, without loss of information, optimize five factors that influence the vanillin assay: acid normality, vanillin concentration, temperature, time and acid type. Further optimization with a D-optimal design and response surface analysis (RSM) showed that a second-order polynomial model fit the experimental data appropriately. The optimum... 

    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) Jafari, R ; Golnabi, H ; Sharif University of Technology
    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... 

    Copper recovery from reverberatory furnace flue dust

    , Article International Journal of Mineral Processing ; Volume 157 , 2016 , Pages 205-209 ; 03017516 (ISSN) Mohagheghi, M ; Askari, M ; Sharif University of Technology
    Elsevier, B. V  2016
    In this study, leaching of reverberatory furnace dust at Sarcheshmeh was investigated in H2SO4-O3 medium. Response surface methodology based on central composite face-centered design (RSM-CCF) was applied to optimize the operating parameters. The optimal conditions to achieve the principle objectives of maximizing copper dissolution and minimizing iron dissolution from dust were identified to be a temperature of 30 °C, a leaching time of 3 h, an initial pH of 0.5, a pulp density of 20%, and an ozone flow rate of 1 g/h. Under the optimum conditions, the copper and iron concentrations in the leaching solution were found to be 27.11 and 0.90 g/L, respectively. The results showed that selective... 

    Deep eutectic solvents: Cutting-edge applications in cross-coupling reactions

    , Article Green Chemistry ; Volume 22, Issue 12 , 2020 , Pages 3668-3692 Hooshmand, S. E ; Afshari, R ; Ramón, D. J ; Varma, R. S ; Sharif University of Technology
    Royal Society of Chemistry  2020
    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... 

    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) Hosseininaveh, H ; Mohammadi, O ; Faghiri, S ; Shafii, M. B ; Sharif University of Technology
    Elsevier Ltd  2021
    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... 

    An optimized thermal cracking approach for onsite upgrading of bitumen

    , Article Fuel ; Volume 307 , 2022 ; 00162361 (ISSN) Salehzadeh, M ; Kaminski, T ; Husein, M. M ; Sharif University of Technology
    Elsevier Ltd  2022
    Onsite partial upgrading is a promising strategy for facilitating pipeline transportation of bitumen without the use of diluent. In the present work, a one-step treatment using an autoclave is optimized toward upgrading Alberta bitumen of 9.6 API gravity and 925,000 cP viscosity. The thermal cracking process was kept simple in order to maintain an economic and environmental advantage. Optimum conditions entailed 75 min of reaction time at 420 °C, without quenching the reactor. These conditions corresponded to highest centrifuged oil product yield of 73.3 ± 1.1 wt%, viscosity of 34 ± 2 cP and API gravity of 18.9 ± 0.5. H-NMR, CHNS and FTIR measurements revealed thermally cracked asphaltenes... 

    Construction and Optimum Condition Selection for Microbial Fuel Cell for Organic Matter Removal and Electricity Generation

    , Ph.D. Dissertation Sharif University of Technology Hosseinpour, Mohammad Reza (Author) ; Vossoughi, Manoochehr (Supervisor) ; Alemzadeh, Iran (Supervisor)
    A Microbial fuel cell is a Bioreactor in which chemical bands are broken and their energy convert to electricity by bio-catalysts such as microorganisms and enzymes.In this project, construction, substrate investigation and optimization of operational parameters were done. Microbial fuel cell as a waste water treatment method was considered in this project. As a result, different substrate were used in anode chamber of constructed microbial fuel cell. The most important ones were waste water containing ethylene glycol and crude oil.Consequently, lack of information about cathode operational parameters was led to optimum condition selection for pH, buffer concentration and ionic strength as... 

    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) Imanieh, I ; Yousefi, E ; Dolati, A ; Mohammadi, M. R ; Sharif University of Technology
    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... 

    An investigation on the optimum conditions of synthesizing a magnetite based ferrofluid as MRI contrast agent using Taguchi method

    , Article Materials Science- Poland ; Volume 31, Issue 2 , 2013 , Pages 253-258 ; 01371339 (ISSN) Ahmadi, R ; Hosseini, H. R. M ; Sharif University of Technology
    In this study, some stabilized magnetite based ferrofluids were synthesized using Dextran as a stabilizing agent. In order to achieve optimum experimental conditions for synthesizing ferrofluids as MRI contrast agents, the Taguchi method was used. This approach was employed to design and minimize the number of required experiments. By using the Taguchi orthogonal (L16) array, four parameters including solution temperature and alkalinity, reaction temperature and stirring rate were selected at four predetermined levels for 16 experiments. Synthesizing processes established based on this set of experimental conditions were carried out and the obtained ferrofluids were characterized using PCS,... 

    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) Hormozi Nezhad, M. R ; Bagheri, H ; Bohloul, A ; Taheri, N ; Robatjazi, H ; Sharif University of Technology
    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... 

    Numerical investigation of droplets breakup in a microfluidic T-junction

    , Article Applied Mechanics and Materials ; Volume 110-116 , 2012 , Pages 3269-3277 ; 16609336 (ISSN) ; 9783037852620 (ISBN) Bedram, A ; Moosavi, A ; Int. Assoc. Comput. Sci. Inf. Technol. (IACSIT) ; Sharif University of Technology
    A Volume of Fluid (VOF) method is used to stdy the breakup of droplets in T-junction geometries. Symmetric T-junctions, which are used to produce equal size droplets and have many applications in pharmacy and chemical industries, are considered. Two important factors namely "breakup time" and "breakup length" that can improve the performance of these systems have been introduced. In addition a novel system which consists of an asymmetric T-junction is proposed to produce unequal size droplets. The effects of the channel width ratio and the capillary number on the size and length of the generated droplets and also the time of the generation have been studied and discussed. For simulation the... 

    Production of glucoamylase by aspergillus niger under solid state fermentation

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 25, Issue 1 , 2012 , Pages 1-7 ; 1728-144X (ISSN) Nahid, P ; Vossoughi, M ; Roostaazad, R ; Ahmadi, M ; Zarrabi, A ; Hosseini, S. M ; Sharif University of Technology
    In this study, Glucoamylase production by Aspergillus niger was investigated under solid state fermentation using low cost by-products of agricultural processes as substrate. Highest enzyme production was observed when a combination of wheat bran (WB) and corn flour (CF) was used as compared to WB+ rice bran, WB+ rice flour and WB alone. Several compositions of corn flours were experimented. The best combination of WB in addition of 10% corn flour resulted maximum enzyme activities. Study of the fermentations in flasks revealed 373.3 IU/gds and 41.4 g/l for the enzyme activity and protein concentration respectively under conditions of 30± 1°C, pH 4.7 and time 96 h. Optimum conditions... 

    Cold briquetting of sponge iron (CBSI): Parameters and effectiveness

    , Article Ironmaking and Steelmaking ; Volume 38, Issue 6 , May , 2011 , Pages 442-446 ; 03019233 (ISSN) Tavakoli, M. R ; Askari, M ; Farahani, M ; Shahahmadi, A ; Sharif University of Technology
    The oxidation of sponge iron products and its destructive effects on iron content as well as other properties have been considered by ferrous technologists for a long time. In this investigation, a unique new low temperature method of preventing and/or retarding the oxidation of direct reduced iron is introduced. Experimental results from laboratory and pilot plant tests show the success of the method which has been named cold briquetting of sponge iron. The optimum condition for briquetting is achieved at 80 kN (Lcm)-1, 6% binder, 10% sponge iron fines and 4% anthracite. While hot briquetted iron has become a successful method for the new generation of iron reduction plants, cold... 

    Improvement of palm oil and sunflower oil blends by enzymatic interestrification

    , Article International Journal of Food Science and Technology ; Volume 46, Issue 5 , 2011 , Pages 1093-1099 ; 09505423 (ISSN) Yazdi, Z. K ; Alemzadeh, I ; Sharif University of Technology
    Palm oil (PO) and sunflower oil (SFO) blends with varying proportions were subjected to enzymatic interesterification (EIE) using a 1,3-specific immobilised lipase. The interesterified blends were evaluated for their slip melting point (SMP), solid fat content (SFC) at 10-40°C, p-anisidine value, peroxide value, free fatty acids (FFA), induction period of oxidation at 110°C (IP110) and composition of fatty acids by gas chromatography. Under EIE treatment, the blends of PO and SFO in different proportions (20:80, 40:60, 50:50, 60:40 and 80:20) had saturated and unsaturated fatty acid content in the range of 37.6-52.0% and 48.0-62.4%, respectively. The blends showed a considerable reduction in... 

    Colorimetric detection of glutathione based on transverse overgrowth of high aspect ratio gold nanorods investigated by MCR-ALS

    , Article RSC Advances ; Volume 5, Issue 101 , 2015 , Pages 82906-82915 ; 20462069 (ISSN) Fahimi Kashani, N ; Shadabipour, P ; Hormozi-Nezhad, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2015
    In this paper, we present a simple platform for colorimetric detection of glutathione using gold nanorods (AR ∼ 6.5 ± 0.2) as a plasmonic sensor. The functional mechanism of the sensor is based on shifts of longitudinal plasmon resonance during selective transverse overgrowth induced by preferential binding of glutathione at the nanorod tips. Under the optimum conditions, a calibration curve showed two linear regimes at the range of 50 nM to 20 μM of glutathione with a detection limit as low as 40 nM. The nanosensor maintains relatively high selectivity for determination of glutathione in the presence of several other amino acids. However, cysteine at similar concentration levels strongly... 

    Characterization of nanocrystalline CuCo2O4 spinel prepared by sol–gel technique applicable to the SOFC interconnect coating

    , Article Applied Physics A: Materials Science and Processing ; Volume 119, Issue 2 , May , 2015 , Pages 727-734 ; 09478396 (ISSN) Paknahad, P ; Askari, M ; Ghorbanzadeh, M ; Sharif University of Technology
    Springer Verlag  2015
    CuCo2O4 spinel nanopowders were synthesized by sol–gel method. The optimal values of pH and molar ratio of citric acid to metal ions (RC), and the influence of the calcination temperature and time were investigated. As-prepared materials were characterized by XRD, TGA, DSC, FE-SEM and electrical and coefficient of thermal expansion (CTE) measurements. It was found that pH = 4.5 and RC = 1 are the optimum conditions to produce pure CuCo2O4 nanopowders. The electrical conductivity was increased remarkably from 15.2 to 27.5 S cm−1 with an increase in temperature from 500 to 800 °C. Over the temperature range of 25–800 °C, the CTE of...