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    An approach for the estimation of dynamic imbibition capillary pressure curves

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 9 , Dec , 2010 , p. 1007-1017 ; ISSN: 15567036 Shojaadini Ardakany, M ; Shadizadeh, S.R ; Masihi, M ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
    Abstract
    Capillary pressure is one of the most important parameters for reservoir engineering studies. Although different experimental methods are devised to measure capillary pressure, these methods do not represent the physics of fluid flow, which happens at reservoir conditions. Thus, it is attempted to extract the capillary pressure from spontaneous imbibition data, the common mechanism of oil production in water wet porous media. In this work, a new approach is developed to obtain the imbibition capillary pressure curve by using spontaneous water imbibition data in oil-water-rock systems. Comparison of calculated imbibition capillary pressure curves by the new approach with experimental values... 

    Simultaneous triple joint movement fuzzy control in FES-assisted rowing exercise

    , Article 2012 19th Iranian Conference of Biomedical Engineering, ICBME 2012, 20 December 2012 through 21 December 2012 ; December , 2012 , Pages 66-70 ; 9781467331302 (ISBN) Zarei, M ; Jahed, M ; Mehravar, M ; Sharif University of Technology
    2012
    Abstract
    Fuzzy Control of rowing exercise using Functional Electrical Stimulation (FES) concerns ankle, knee and hip joints. Muscular Modeling for each joint may contain two groups of muscles, namely extension and flexion. In the proposed method, joint controllers provide electrical stimulation pulses to the appropriate muscle group based on the trajectory error and according to a prescribed pattern designed for rowing exercise. Results indicate that the simulated Fuzzy control of desired angles closely match the experimental values for prescribed joints. Moreover, the robustness of the controller in presence of external disturbance is examined and the results show that the tracking of each joint... 

    Densities, viscosities, and surface tensions of aqueous mixtures of sulfolane + triethanolamine and sulfolane + diisopropanolamine

    , Article Journal of Chemical and Engineering Data ; Volume 56, Issue 12 , 2011 , Pages 4317-4324 ; 00219568 (ISSN) Kelayeh, S. A ; Jalili, A. H ; Ghotbi, C ; Hosseini Jenab, M ; Taghikhani, V ; Sharif University of Technology
    Abstract
    Densities and viscosities of aqueous solutions containing sulfolane and ternary aqueous solutions of sulfolane and triethanolamine and ternary aqueous solutions containing sulfolane and disopropanolamine and also equilibrium surface tensions of the above ternary aqueous solutions were measured at temperatures ranging from (303.15 to 343.15) K and atmospheric pressure. The overall concentration of sulfolane, triethanolamine, and diisopropanolamine in solutions varied in the range of 0 to 16.5, 0 to 43, and 0 to 40 mass percent, respectively. Using the density, viscosity, and surface tension of pure water as the solvent, the corresponding experimental values obtained for the investigated... 

    Prediction of standard enthalpy of combustion of pure compounds using a very accurate group-contribution-based method

    , Article Energy and Fuels ; Volume 25, Issue 6 , April , 2011 , Pages 2651-2654 ; 08870624 (ISSN) Gharagheizi, F ; Mirkhani, S. A ; Tofangchi Mahyari, A. R ; Sharif University of Technology
    2011
    Abstract
    The artificial neural network-group contribution (ANN-GC) method is applied to estimate the standard enthalpy of combustion of pure chemical compounds. A total of 4590 pure compounds from various chemical families are investigated to propose a comprehensive and predictive model. The obtained results show the squared correlation coefficient (R 2) of 0.999 99, root mean square error of 12.57 kJ/mol, and average absolute deviation lower than 0.16% for the estimated properties from existing experimental values  

    Kinetic modeling of thermal hydrocracking of a paraffinic feedstock

    , Article Energy and Fuels ; Volume 30, Issue 4 , 2016 , Pages 3374-3384 ; 08870624 (ISSN) Hajian, H ; Khorasheh, F ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    A kinetic model based on a mechanistic approach was developed for thermal hydrocracking of a paraffinic feedstock. The hydrocarbon feed was described as a mixture of representative molecules based on structural group analysis (SGA) where information from elemental analysis, H1, and C13-NMR of the feed were used to obtain the average concentration of various structural groups from which representative molecules were constructed. The behavior of the feedstock under reaction conditions was described in terms of the reaction of the individual molecules. The reaction of each of the representative molecules and the corresponding product distribution was based on free radical mechanisms. The... 

    Experimental and numerical study of the effect of pulsating flow on the turbocharger turbine performance parameters

    , Article SAE Technical Papers ; Volume 2 , April , 2013 Tabatabaei, H ; Boroomand, M ; Taeibi Rahni, M ; Sharif University of Technology
    2013
    Abstract
    The pulsating flow in the exhaust gas of a SI engine causes an unsteady flow at the inlet to the turbocharger turbine. In a four cylinder four stroke engine, the pulse frequency varies between 20 and 200 Hz. Three dimensional pulsating flows in a vane-less turbocharger turbine of a 1.7 liters SI engine are simulated numerically and validated experimentally. Simulations are done for 720 degree engine cycle at three engine speeds. The results are shown the inlet pulsating flow has significant effects on several turbine parameters especially the inlet total pressure, the reduced mass flow rate and the efficiency. The results show a very good agreement between the three-dimensional unsteady... 

    Halide (Cl-, Br-, I-) influence on the electronic properties of macrocyclic nickel(II) complexes: Ab-initio DFT study

    , Article Journal of the Korean Chemical Society ; Volume 57, Issue 3 , 2013 , Pages 311-315 ; 10172548 (ISSN) Zarei, S. A ; Akhtari, K ; Hassanzadeh, K ; Piltan, M ; Saaidpour, S ; Abedi, M ; Sharif University of Technology
    2013
    Abstract
    The geometry structures of hexa-coordinated [NiLX]X complexes (X = Cl -, Br-, I-) {L = 8,9,18,19-tetrahydro-7H,17H- dibenzo[f,o] [1,5,9,13]dioxadiaza cyclohexadecine-8,18-diol} are optimized by density functional theory (DFT) using B3LYP/LANL2DZ. The calculated geometric parameters are in good agreement with the corresponding experimental values. Calculation results about these complexes show that dipole moment decreases, and the energy levels of HOMOs descend from iodo-complex to chloro-complex. The energy levels of HOMOs descend gently from iodo-complex to chloro-complex, while the energy levels of LUMOs in the present complexes are almost similar; therefore the energy gapes between HOMOs... 

    Development of a novel Peng–Robinson plus association equation of state for industrially important associating compounds

    , Article Neural Computing and Applications ; Nov , 2015 , Pages 1-9 ; 09410643 (ISSN) Eslami, L ; Khadem Hamedani, B ; Sharif University of Technology
    Springer-Verlag London Ltd  2015
    Abstract
    Cubic plus association (CPA) equations of state (EoSs) have found great interest in describing thermodynamic properties of associating fluids. In CPA EoSs, the association contribution proposed by Wertheim is added to cubic EoSs such as Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR). In different developments of CPA EoSs, adjusting the pure component properties such as critical temperature and critical pressure in addition to the association parameters is proposed in some works in the literature. In this work, the PR EoS has been extended to water, phenol, and a number of alcohols (methanol up to dodecanol) by addition of the Wertheim association contribution. In contrast to other CPA... 

    Application of response surface methodology and central composite rotatable design for modeling and optimization of sulfuric and nitric leaching of spent catalyst

    , Article Russian Journal of Non-Ferrous Metals ; Volume 56, Issue 2 , 2015 , Pages 155-164 ; 10678212 (ISSN) Niaki, R ; Abazarpoor, A ; Halali, M ; Maarefvand, M ; Ebrahimi, G ; Sharif University of Technology
    Abstract
    The optimization of leaching parameters for the Ni recovery of the used catalyst was developed using response surface methodology. The relationship between the Ni recoveries, and four main leaching parameters, temperature, acid concentration, leaching time and particle size were presented as empirical model equations. The predicted values of nickel recoveries were found to be in a reasonable agreement with the experimental values, with R2 as correlation factor being 0.9669 and 0.9869 for sulfuric and nitric acids, respectively. The model equations were then optimized using the quadratic programming method to maximize nickel recovery. The optimum conditions were found to be 103.4°C... 

    Modelling correlation between hot working parameters and flow stress of IN625 alloy using neural network

    , Article Materials Science and Technology ; Volume 26, Issue 5 , Jul , 2010 , Pages 621-625 ; 02670836 (ISSN) Montakhab, M ; Behjati, P ; Sharif University of Technology
    2010
    Abstract
    In this work, an optimum multilayer perceptron neural network is developed to model the correlation between hot working parameters (temperature, strain rate and strain) and flow stress of IN625 alloy. Three variations of standard back propagation algorithm (Broyden, Fletcher, Goldfarb and Shanno quasi-Newton, Levenberg-Marquardt and Bayesian) are applied to train the model. The results show that, in this case, the best performance, minimum error and shortest converging time are achieved by the Levenberg-Marquardt training algorithm. Comparing the predicted values and the experimental values reveals that a well trained network is capable of accurately calculating the flow stress of the alloy... 

    Investigation of conductivity effects on capacitance measurements of water liquids using a cylindrical capacitive sensor

    , Article Journal of Applied Sciences ; Volume 10, Issue 4 , 2010 , Pages 261-268 ; 18125654 (ISSN) Behzadi, G ; Golnabi, H ; Sharif University of Technology
    Abstract
    In this study by using a Cylindrical Capacitive Sensor (CCS), the Electrical Conductivity (EC), effects on the capacitance measurements of the water liquids was investigated. Theoretical values of the capacitance measurements of water liquids with the cylindrical length in the range 0.5-5 cm are calculated. Our obtained results indicate that measured capacitance value by CCS depends on the liquid capacitance and reactance capacitance. Liquid capacitance value of the distilled water for permittivity of 80 is about 33.5 pF and reactance capacitance value is about 0.290 μF, when the cylindrical length value is about 1.6 cm. The reactance capacitance for the mineral, tap and dilute salt water... 

    A novel correlation approach for viscosity prediction of water based nanofluids of Al2O3, TiO2, SiO2 and CuO

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 58 , 2016 , Pages 19-27 ; 18761070 (ISSN) KalantariMeybodi, M ; Daryasafar, A ; MoradiKoochi, M ; Moghadasi, J ; BabaeiMeybodi, R ; KhorramGhahfarokhi, A ; Sharif University of Technology
    Taiwan Institute of Chemical Engineers  2016
    Abstract
    Nanofluids viscosity is one of the most important thermophysical properties in nanofluids usage especially in chemical and petroleum engineering applications. So it is highly desirable to predict the viscosity of nanofluids accurately. Experimental measurements are impossible in most situations and present models are not comprehensive and efficient especially for high temperature, high volume concentration and high viscosity values. In this study, a new correlation has been developed based on the comprehensive database of water based Al2O3, TiO2, SiO2 and CuO nanofluids viscosity data found in literature. The proposed correlation uses temperature, nanoparticle size, nanoparticle volumetric... 

    Modelling of conventional and severe shot peening influence on properties of high carbon steel via artificial neural network

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 31, Issue 2 , 2018 , Pages 382-393 ; 1728144X (ISSN) Maleki, E ; Farrahi, G. H ; Sharif University of Technology
    Materials and Energy Research Center  2018
    Abstract
    Shot peening (SP), as one of the severe plastic deformation (SPD) methods is employed for surface modification of the engineering components by improving the metallurgical and mechanical properties. Furthermore, artificial neural network (ANN) has been widely used in different science and engineering problems for predicting and optimizing in the last decade. In the present study, effects of conventional shot peening (CSP) and severe shot peening (SSP) on properties of AISI 1060 high carbon steel were modelled and compared via ANN. In order to networks training, the back propagation (BP) error algorithm is developed and data of experimental tests results are employed. Experimental data... 

    Developing a mathematical model for reforming of glycerol towards a comparative evaluation of the liquid vs. gas phase medium

    , Article International Journal of Hydrogen Energy ; Volume 44, Issue 49 , 2019 , Pages 26764-26772 ; 03603199 (ISSN) Nayernia, Z ; Kazemeini, M ; Larimi, A ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Glycerol might be converted into hydrogen through a catalytic reforming process. In order to design an effective route, the choice of reaction conditions and in particular its medium considered yet a crucial issue still needing further investigations. In this research, a mathematical model of reforming processes in vapor (i.e., steam reforming (SR) and liquid phase (i.e.; aqueous phase reforming (APR)) were developed. This was performed in terms of understudying effects of parameters including the reactor diameter, catalyst morphology (i.e., particle size) and mass flow rate on the glycerol conversion. Then, a superior reaction medium in terms of these variables was determined. For data... 

    Development of a novel Peng–Robinson plus association equation of state for industrially important associating compounds

    , Article Neural Computing and Applications ; Volume 31, Issue 7 , 2019 , Pages 2107-2115 ; 09410643 (ISSN) Eslami, L ; Khadem Hamedani, B ; Sharif University of Technology
    Springer London  2019
    Abstract
    Cubic plus association (CPA) equations of state (EoSs) have found great interest in describing thermodynamic properties of associating fluids. In CPA EoSs, the association contribution proposed by Wertheim is added to cubic EoSs such as Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR). In different developments of CPA EoSs, adjusting the pure component properties such as critical temperature and critical pressure in addition to the association parameters is proposed in some works in the literature. In this work, the PR EoS has been extended to water, phenol, and a number of alcohols (methanol up to dodecanol) by addition of the Wertheim association contribution. In contrast to other CPA... 

    Sensitivity analysis of the transmission factor and resolution of a multiblade neutron velocity selector to the various parameters

    , Article Radiation Physics and Chemistry ; Volume 177 , December , 2020 Moeini, H ; Hosseini, S. A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The neutron velocity selector is a device used to produce a monochromatic neutron beam with continuous flux. The purpose of the present study is to investigate the sensitivity of the transmission factor and resolution of a multiblade neutron velocity selector to the various parameters using the McStas software. To this end, two instruments were created using the Arm, Progress_bar, Source_simple, DivMonitor, L_monitor, Guide_channeled and V_selector components of the McStas software. The used V_selector component to simulate the multiblade neutron velocity selector was created by considering three assumptions: 1. The absorption of colliding neutrons to selector blades, 2. No interaction of... 

    Prediction of CO2 loading capacity of chemical absorbents using a multi-layer perceptron neural network

    , Article Fluid Phase Equilibria ; Volume 354 , September , 2013 , Pages 6-11 ; 03783812 (ISSN) Bastani, D ; Hamzehie, M. E ; Davardoost, F ; Mazinani, S ; Poorbashiri, A ; Sharif University of Technology
    2013
    Abstract
    A feed forward multi-layer perceptron neural network was developed to predict carbon dioxide loading capacity of chemical absorbents over wide ranges of temperature, pressure, and concentration based on the molecular weight of solution. To verify the suggested artificial neural network (ANN), regression analysis was conducted on the estimated and experimental values of CO2 solubility in various aqueous solutions. Furthermore, a comparison was performed between results of the proposed neural network and experimental data that were not previously used for network training, as well as a set of data for binary solutions. Comparison between the proposed multi-layer perceptron (MLP) network and... 

    Study of the solubility of CO2, H2S and their mixture in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate: Experimental and modelling

    , Article Journal of Chemical Thermodynamics ; Volume 65 , 2013 , Pages 220-232 ; 00219614 (ISSN) Safavi, M ; Ghotbi, C ; Taghikhani, V ; Jalili, A. H ; Mehdizadeh, A ; Sharif University of Technology
    2013
    Abstract
    New experimental results are presented for the solubility of carbon dioxide, hydrogen sulfide in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) at temperatures range from (303.15 to 353.15) K and pressures up to about 2 MPa. The solubility of the mixture of CO2/H2S in [C8mim][PF6] under various feed compositions were also measured at temperatures of (303.15, 323.15 and 343.15) K and the pressure up to 1 MPa. The solubility of carbon dioxide and hydrogen sulfide increased with increasing pressure and decreased with increasing temperature and the solubility of H2S is about three times that of CO2 in the particular ionic liquid studied. The measured data were... 

    Layer selection effect on solid state 13C and 15N chemical shifts calculation using ONIOM approach

    , Article Solid State Nuclear Magnetic Resonance ; Volume 51-52 , 2013 , Pages 31-36 ; 09262040 (ISSN) Shaghaghi, H ; Ebrahimi, H. P ; Bahrami Panah, N ; Tafazzoli, M ; Sharif University of Technology
    2013
    Abstract
    Solid state 13C and 15N chemical shifts of uracil and imidazole have been calculated using a 2-layer ONIOM approach at 32 levels of theory. The effect of electron correlation between two layers has been investigated by choosing two different kinds of layer selection. Factorial design has been applied as a multivariate technique to analyze the effect of wave function and layer selection on solid state 13C and 15N chemical shifts calculations. PBEPBE/6-311+G(d,p) was recommended as an optimally selected level of theory for high layer in both models. It is illustrated that considering the electron correlation of two layers of ONIOM models is important factor to calculate solid state 15N... 

    First principles study of oxygen adsorption on nickel-doped graphite

    , Article Molecular Physics ; Volume 110, Issue 13 , Feb , 2012 , Pages 1437-1445 ; 00268976 (ISSN) Nahali, M ; Gobal, F ; Sharif University of Technology
    2012
    Abstract
    Density functional theory is used in a spin-polarized plane wave pseudopotential implementation to investigate molecular oxygen adsorption and dissociation on graphite and nickel-doped graphite surfaces. Molecular oxygen physisorbs on graphite surface retaining its magnetic property. The calculated adsorption energy is consistent with the experimental value of 0.1eV. It is found that substituting a carbon atom of the graphite surface by a single doping nickel atom (2.8% content) makes the surface active for oxygen chemisorption. It is found that the molecular oxygen never adsorbs on doping nickel atom while it adsorbs and dissociates spontaneously into atomic oxygens on the carbon atoms...