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    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... 

    Physical optics integrals evaluation using closed-form expressions and triangular boundary-rectangular mesh algorithm

    , Article IET Microwaves, Antennas and Propagation ; Volume 9, Issue 15 , 2015 , Pages 1803-1808 ; 17518725 (ISSN) Mokhtari Koushyar, F ; Shishegar, A. A ; Sharif University of Technology
    In this study, the authors propose a novel Filon-type integration method that uses error-controllable and frequency-independent closed-form expression to evaluate highly oscillatory physical optics (PO) surface integrals on smooth conducting surfaces. In this method, the phase and amplitude functions of PO integrals for a general parametric surface and incident wave are approximated by second order polynomials, first. Although there are some complicated closed-form expressions for these integrals in the literature, the authors present simple and computationally efficient closed-form expressions for them. For this end, the parametric domain of each resulted integral is meshed by triangular... 

    Use of response surface methodology for evaluation of effective parameters in codeposition of Cu-Sn alloys using non-cyanide electroplating solution

    , Article Transactions of the Institute of Metal Finishing ; Volume 90, Issue 1 , January , 2012 , Pages 38-43 ; 00202967 (ISSN) Asnavandi, M ; Ghorbani, M ; Sharif University of Technology
    A pyrophosphate based solution, as an acidic electrolyte, was developed for bronze electroplating. By using a statistical experimental design, response surface method, the effects of five factors [copper concentration (Cu), tin concentration (Sn), pyrophosphate concentration (P), current density j and pH] on the composition of the electroplated alloy as well as the process efficiency were evaluated. Statistical analysis indicated that all the parameters were significant and a second order polynomial model was successfully fitted to the data for both the alloy composition and the process efficiency. Based on the results obtained, a solution of Cu(II)8.04 g L -1, Sn(II)=26.36 g L -1, P=113.22... 

    On the strain inhomogeneity in drawn copper wires

    , Article International Journal of Material Forming ; Volume 3, Issue 1 , 2010 , Pages 59-64 ; 19606206 (ISSN) Hasani, G. H ; Mahmudi, R ; Karimi Taheri, A ; Sharif University of Technology
    Three different wire drawing schedules were attempted to examine the effects of reduction of area, die-angle and friction coefficient on the strain inhomogeneity of drawn copper wires. The microhardness distribution was studied over the transverse and longitudinal cross-sections. Inhomogeneity factor (I. F.) curves; I. F. = f(r), I. F. = g(2α) and I. F. = h(μ) were determined from the measurements. The results indicate that less strain inhomogeneity is achieved in drawing wires through dies with low angle, low friction coefficient and high reduction of area. Despite the variation in reduction of area and die-angle, the strain was distributed evenly at the center of the drawn wires. Contrary... 

    Surface modification of polysulfone ultrafiltration membranes by free radical graft polymerization of acrylic acid using response surface methodology

    , Article Journal of Polymer Research ; Volume 26, Issue 9 , 2019 ; 10229760 (ISSN) Ganj, M ; Asadollahi, M ; Mousavi, S. A ; Bastani, D ; Aghaeifard, F ; Sharif University of Technology
    Springer Netherlands  2019
    In this research, polysulfone (PSf) ultrafiltration (UF) membranes were prepared by a phase inversion method. Surface modification of the PSf membranes was carried out via grafting of acrylic acid as a hydrophilic monomer by free radical graft polymerization initiated by redox reaction. A central composite design (CCD) of response surface methodology (RSM) was applied to design the experiments. The process variables were acrylic acid concentration (CAA), redox system contact time (T1), and acrylic acid polymerization time (T2), while the contact angle (CA), pure water flux (PWF), and flux recovery ratio (FRR) were considered as the responses. Analysis of variance (ANOVA) demonstrated that... 

    Sensitivity analysis of a heat exchanger tube fitted with cross-cut twisted tape with alternate axis

    , Article Journal of Heat Transfer ; Volume 141, Issue 4 , 2019 ; 00221481 (ISSN) Nakhchi, M. E ; Esfahani, J. A ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2019
    Numerical simulations are used to analyze the thermal performance of turbulent flow inside heat exchanger tube fitted with cross-cut twisted tape with alternate axis (CCTA). The design parameters include the Reynolds number (5000 < Re < 15; 000), cross-cut width ratio (0:7 < b=D < 0:9), cross-cut length ratio (2 < s=D < 2:5), and twist ratio (2 < y=D < 4). The objective functions are the Nusselt number ratio (Nu=Nus), the friction factor ratio (f =fs), and the thermal performance (g). Response surface method (RSM) is used to construct second-order polynomial correlations as functions of design parameters. The regression analysis shows that heat transfer ratio decreased with increasing both... 

    Simulation of wellbore drilling energy saving of nanofluids using an experimental taylor–couette flow system

    , Article Journal of Petroleum Exploration and Production ; Volume 11, Issue 7 , 2021 , Pages 2963-2979 ; 21900558 (ISSN) Rashidi, M ; Sedaghat, A ; Misbah, B ; Sabati, M ; Vaidyan, K ; Mostafaeipour, A ; Hosseini Dehshiri, S. S ; Almutairi, K ; Issakhov, A ; Oloomi, S. A. A ; Malayer, M. A ; Arockia Dhanraj, J ; Sharif University of Technology
    Springer Science and Business Media B.V  2021
    Power consumption of wellbore drilling in oil and gas exploitations count for 40% of total costs, hence power saving of WBM (water-based mud) by adding different concentrations of Al2O3, TiO2 and SiO2 nanoparticles is investigated here. A high-speed Taylor–Couette system (TCS) was devised to operate at speeds 0–1600 RPM to simulate power consumption of wellbore drilling using nanofluids in laminar to turbulent flow conditions. The TCS control unit uses several sensors to record current, voltage and rotational speed and Arduino microprocessors to process outputs including rheological properties and power consumption. Total power consumption of the TCS was correlated with a second-order... 

    Enhancement of bioleaching of a spent Ni/Mo hydroprocessing catalyst by Penicillium simplicissimum

    , Article Separation and Purification Technology ; Volume 80, Issue 3 , August , 2011 , Pages 566-576 ; 13835866 (ISSN) Amiri, F ; Mousavi, S. M ; Yaghmaei, S ; Sharif University of Technology
    Statistically based experimental designs were applied to screen and optimize the bioleaching of spent hydrocracking catalyst by Penicillium simplicissimum. Eleven factors were examined for their significance on bioleaching using a Plackett-Burman factorial design. Four significant variables (pulp density, sucrose, NaNO3, and yeast extract concentrations) were selected for the optimization studies. The combined effect of these variables on metal bioleaching was studied using a central composite design (CCD). Second-order polynomials were established to identify the relationship between the recovery percent of the metals and the four significant variables. The optimal values of the variables... 

    Statistical analysis for enzymatic decolorization of acid orange 7 by Coprinus cinereus peroxidase

    , Article International Biodeterioration and Biodegradation ; Volume 64, Issue 3 , 2010 , Pages 245-252 ; 09648305 (ISSN) Yousefi, V ; Kariminia, H. R ; Sharif University of Technology
    Enzymatic decolorization of the monoazo dye, acid orange 7 (AO7) by the fungal peroxidase from Coprinus cinereus NBRC 30628 is a complex system, which is greatly affected by temperature, pH, enzyme activity and the concentrations of H2O2 and dye concentration. The study of these factors and investigating the combined interactions between them by applying one-factor-at-a-time (OFAT) method and two other statistical methods including 2-factorial method and response surface methodology (RSM) were aimed in this work. Through OFAT analysis the optimized conditions were a temperature of 25 °C, pH 9.0 with H2O2 concentration of about 3.9 mM and AO7 concentration of 40 mg/l. A complete... 

    Evaluation of trichloroethylene degradation by starch supported Fe/Ni nanoparticles via response surface methodology

    , Article Water Science and Technology ; Volume 73, Issue 4 , 2016 , Pages 935-946 ; 02731223 (ISSN) Nikroo, R ; Alemzadeh, I ; Vossoughi, M ; Haddadian, K ; Sharif University of Technology
    IWA Publishing 
    In this study, degradation of trichloroethylene (TCE), a chlorinated hydrocarbon, using starch supported Fe/Ni nanoparticles was investigated. The scanning electron microscope images showed applying water soluble starch as a stabilizer for the Fe/Ni nanoparticles tended to reduce agglomeration and discrete particle. Also the mean particle diameter reduced from about 70 nm (unsupported Fe/Ni nanoparticle) to about 30 nm. Effects of three key independent operating parameters including initial TCE concentration (10.0-300.0 mg L-1), initial pH (4.00-10.00) and Fe0 dosage (0.10-2.00) g L-1 on TCE dechlorination efficiency in 1 hour were analysed by employing response surface methodology (RSM)....