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    Fabrication of self-organised highly ordered titanium oxide nanotube arrays by anodic oxidation and characterisation

    , Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 297-309 ; 17469392 (ISSN) Mohammadpour, R ; Ahadian, M. M ; Iraji Zad, A ; Taghavinia, N ; Dolati, A. G ; Sharif University of Technology
    Self-organised and vertically oriented titanium oxide nanotube array (TNTA) has been synthesised by potentiostat anodisation of Ti foil in fluoride-based electrolyte. By varying the anodisation voltage from 8 V to 24 V it was possible to gradually change the topologies of nanotubes. The size of TNTAs was measured using SEM images and also determined based on a non-destructive optical method. In addition, photoelectrochemical properties of nanotubular TiO2/Ti electrodes were examined by anodic photocurrent response, potentiodynamic polarisation measurements and electrochemical impedance spectroscopy. A general equivalent circuit model was proposed for photoelectrochemical system consists of... 

    A fast method for prior probability selection based on maximum entropy principle and Gibbs sampler

    , Article 2007 9th International Symposium on Signal Processing and its Applications, ISSPA 2007, Sharjah, 12 February 2007 through 15 February 2007 ; 2007 ; 1424407796 (ISBN); 9781424407798 (ISBN) Dianat, R ; Kasaei, S ; Khabbazian, M ; Sharif University of Technology
    One of the problems in Bayesian inference is the prior selection. We can categorize different methods for selecting prior into two main groups: informative and non-informative. Here, we have considered an informative method called filters random filed and minimax entropy (FRAME). Despite of its theoretical interest, that method introduces a huge amount of computational burden, which makes it very unsuitable for real-time applications. The main critical point of the method is its parameter estimation part, which plays a major role in its very low speed. In this paper, we have introduced a fast method for parameter estimation to fasten the FRAME approach. Although the kernel of our approach is... 

    Computer simulation of fluid motion in a porous bed using a volume of fluid method: Application in heap leaching

    , Article Minerals Engineering ; Volume 19, Issue 10 , 2006 , Pages 1077-1083 ; 08926875 (ISSN) Mousavi, S. M ; Jafari, A ; Yaghmaei, S ; Vossoughi, M ; Sarkomaa, P ; Sharif University of Technology
    Heap leaching is a process extensively used by the mining industry to recover metals from low-grade ores and large quantities of submarginal material resources. Understanding flow through a packed particle bed is important to enhance the performance of heap leaching with respect to design and operating considerations. Complex fluid behavior in porous media, such as film flow, fragmentation, coalescence of droplets, and rivulet flow with or without meandering, has been widely observed in laboratory experiments. In this study, to provide detailed information of momentum and mass transfer phenomena in a granular bed direct numerical simulations (DNS) were performed. In this case the liquid-gas... 

    Determination of austenite grain coarsening temperature of a Nb-microalloyed steel sheet

    , Article Advanced Materials Research, 21 January 2011 through 23 January 2011 ; Volume 213 , January , 2011 , Pages 600-603 ; 10226680 (ISSN) ; 9783037850619 (ISBN) Khaki, D. M ; Otaaghvar, V. A ; Khaki, M. M ; Sharif University of Technology
    Thermomechnical processing and controlled rolling of microalloyed steel sheets are affected by several factors according to the final properties of product. To create the high mechanical properties, a uniform and fine-grain structure is necessary in hot rolled final products. To produce such microstructures, every stage of the thermomechanical processing of the steel rolling has to be carefully controlled. Hence, first step is grain coarsening control that it usually occurs during reheating for slab. For this purpose, seven different reheating temperatures between 1000 to 1300 °C with 50 °C increments were chosen in this investigation for soaking treatment. By soaking the specimens in... 

    Multistep reduction of oxygen on polycrystalline silver in alkaline solution

    , Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 31, Issue 5 , 2010 , Pages 541-546 ; 02539837 (ISSN) Jafarian, M ; Gobal, F ; Mahjani, M. G ; Hosseini Aliabadi, M ; Sharif University of Technology
    Oxygen reduction on a polycrystalline silver electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The reaction occurred by a two-electron pathway. The steps in the mechanism were observed in the cyclic voltammograms recorded with different scan rates. The intermediates formed in the steps were detected by electrochemical impedance spectroscopy  

    Statistical tolerance analysis of flexible assemblies with contact effects

    , Article SAE 2016 World Congress and Exhibition, 12 April 2016 through 14 April 2016 ; Volume 2016-April, Issue April , 2016 Khodaygan, S ; Ghasemali, A ; Afrasiab, H ; Sharif University of Technology
    SAE International 
    One of the most important characteristics of industrial products, especially mechanical set-ups, is considering the tolerances of production and assembly of these set-ups, which directly influences the products' operations. In sheet metal structures, due to the high flexibility of the sheets, the errors appeared while assembly will be as highly influential as the errors due to the production tolerance of the sheets. As a result, having a comprehensive model which could analyze the assembly process of these structures and also clarifies the relation between the tolerance of the parts and the ultimate changes of the set-up will be of considerable importance. During the assembly process, the... 

    Thermal analysis of laser hardening for different moving patterns

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 22, Issue 2 , 2009 , Pages 169-180 ; 17281431 (ISSN) Farrahi, G. H ; Sistaninia, M ; Sharif University of Technology
    Materials and Energy Research Center  2009
    Transient thermal field in laser surface hardening treatment of medium carbon steel was analyzed by employing both three-dimensional analytical model and finite element model. In finite element model the laser beam was considered as a moving plane heat flux to establish the temperature rise distribution in the work-piece, while in analytical model laser beam was considered as an internal heat source. The numerical results were compared with the analytical results. In laser heat treatment of steel some methods are used to produce a wider and nearly uniform average irradiance profile. It may be achieved by rotating the beam optically, thereby producing an overlapping spiral track, or by... 

    Optimum design of middle stage tool geometry and addendum surfaces in sheet metal stamping processes using a new isogeometric-based framework

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; 2021 ; 09544054 (ISSN) Shamloofard, M ; Isazadeh, A. R ; Bostan Shirin, M ; Assempour, A ; Sharif University of Technology
    SAGE Publications Ltd  2021
    An efficient isogeometric-based framework is presented to integrate optimum design and formability analysis of sheet metal forming processes. To assess the quality of the formed parts, several objective functions such as fracture, wrinkling, thickness variation, and stretching are studied. In this framework, geometric parameters of addendum surfaces and middle tools are considered as design variables, the objective functions are calculated using the recently developed one-step and multi-step inverse isogeometric methods, and the optimum design variables are obtained using the genetic global optimization algorithm. The major advantage of employing the inverse methods is to analyze the... 

    Immobilization of dioxomolybdenum(VI) complex bearing salicylidene 2-picoloyl hydrazone on chloropropyl functionalized SBA-15: A highly active, selective and reusable catalyst in olefin epoxidation

    , Article Applied Catalysis A: General ; Vol. 475 , April , 2014 , pp. 55-62 ; ISSN: 0926860X Bagherzadeh, M ; Zare, M ; Salemnoush, T ; Ozkar, S ; Akbayrak, S ; Sharif University of Technology
    A novel organic-inorganic hybrid heterogeneous catalyst system was obtained from the reaction of the molybdenum(VI) complex of salicylidene 2-picoloyl hydrazone with mesoporous silica containing 3-chloropropyl groups prepared by a direct synthetic approach involving hydrolysis and co-condensation of tetraethylorthosilicate (TEOS) and 3-chloropropyltrimethoxysilane in the presence of the triblock copolymer P123 as template under acidic conditions. Characterization of the functionalized materials by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), N2 adsorption/desorption, FT-IR and UV-Vis spectroscopy, and thermogravimetric... 

    Operation of tapered steel slit dampers in steel structures using the endurance time method

    , Article Civil-Comp Proceedings ; 2013 , Volume 102 ; 17593433 (ISSN) ; 9781905088577 (ISBN) Mirjalili, A ; Estekanchi, H.E ; Fakhri, M ; Sharif University of Technology
    Civil-Comp Press  2013
    Based on special properties of metal dampers such as high energy dissipation, stable hysteric cycles, simple application, low cost, insensitivity to changes of temperature and the ability to substitute after the occurrence of earthquakes, they are being used for structural control. One of these metal dampers which has been of special interest is the tapered steel slit damper (TSS). When shear forces are applied, this damper yields and enters the plastic zone. The TSS damper is made of pieces of standard wide flanges where slits have been extracted from their web. These dampers are connected to the top of the chevron braces and under the middle of the beams. In the endurance time (ET) method... 

    Interaction of cations with 2′-deoxythymidine nucleoside and analysis of the nature and strength of cation bonds

    , Article Journal of Physical Organic Chemistry ; Volume 25, Issue 2 , JAN , 2012 , Pages 153-161 ; 08943230 (ISSN) Shakourian Fard, M ; Fattahi, A ; Jamshidi, Z ; Sharif University of Technology
    Binding of Mg 2+, Ca 2+, Zn 2+, and Cu + metal ions with 2′-deoxythymidine (dT) nucleoside was studied using a density functional theory method and a 6-311++G(d,p) basis set. This work demonstrated that the interaction of dT with these cations is tri-coordinated · (O2, O4′, O5′). Among the four types of cations, Zn 2+ cation exhibited the most tendency to interact with the dT. Cations via their interaction with dT can affect the N-glycosidic bond length, the values of pseudorotation of the sugar ring, the orientation of the base unit with respect to the sugar ring, and the acidity of the O5′H, O3′H, and N3H groups in the dT nucleoside. Natural bond orbital analysis was performed to calculate... 

    An experimental design approach to determine effects of the operating parameters on the rate of Ru promoted Ir carbonylation of methanol

    , Article World Academy of Science, Engineering and Technology ; Volume 73 , March , 2011 , Pages 598-603 ; 2010376X (ISSN) Hosseinpour, V ; Kazemini, M ; Mohammadrezaee, A ; Sharif University of Technology
    carbonylation of methanol in homogenous phase is one of the major routesfor production of acetic acid. Amongst group VIII metal catalysts used in this process iridium has displayed the best capabilities. To investigate effect of operating parameters like: temperature, pressure, methyl iodide, methyl acetate, iridium, ruthenium, and water concentrations on the reaction rate, experimental design for this system based upon central composite design (CCD) was utilized. Statistical rate equation developed by this method contained individual, interactions and curvature effects of parameters on the reaction rate. The model with p-value less than 0.0001 and R 2 values greater than 0.9; confirmeda... 

    On the binding of Mg 2+, Ca 2+, Zn 2+ and Cu + metal cations to 2 ′ -deoxyguanosine: Changes on sugar puckering and strength of the N-glycosidic bond

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1343-1352 ; 10263098 (ISSN) Ahmadi, M. S ; Fattahi, A ; Sharif University of Technology
    The binding of Mg 2+, Ca 2+, Zn 2+ and Cu + metal cations to 2′-deoxyguanosine has been analyzed, using the hybrid B3LYP, Density Functional Theory (DFT) method and 6311++G(d,p) orbital basis sets. Coordination geometries, absolute metal ion affinities, and free energies for the most stable complexes formed by Mg 2+, Ca 2+, Zn 2+ and Cu + with the nucleoside, 2′-deoxyguanosine, have been determined. Furthermore, the influences of metal cationization on the strength of the N-glycosidic bond, torsion angles and angle of Pseudorotation (P) have been studied. With respect to the results, it has been found that metal binding significantly changes the values of the phase angle of Pseudorotation... 

    The effect of heat treatment on physical properties of nanograined (WO 3)1-x-(Fe2O3)x thin films

    , Article Vacuum ; Volume 85, Issue 8 , February , 2011 , Pages 810-819 ; 0042207X (ISSN) Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    Thin films of (WO3)1-x-(Fe2O 3)x composition were deposited by thermal evaporation on glass substrates and then all samples were annealed at 200-500 °C in air. Optical properties such as transmittance, reflectance, optical bangap energy, and the optical constants of the "as deposited" and the annealed films were studied using ultraviolet-visible spectrophotometry. It was shown that the annealing process changes the film optical properties which were related to Fe2O3 concentration. Moreover, using X-ray photoelectron spectroscopy, we have indicated that WO3 is stoichiometric, while iron oxide was in both FeO and Fe2O3 compositions so that the FeO composition converted to Fe2O3 after the... 

    Effect of finishing temperature on mechanical properties of a Nb-microalloyed steel sheet

    , Article Advanced Materials Research, 17 September 2010 through 19 September 2010 ; Volume 129-131 , 2010 , Pages 1022-1028 ; 10226680 (ISSN) ; 9780878492435 (ISBN) Mirahmadi Khaki, D ; Akbarzadeh, A ; Abedi, A ; Sharif University of Technology
    Thermo mechanical processing and controlled rolling of microalloyed steel sheets are affected by several factors. In this investigation, finishing temperature of rolling which is considered as the most effective parameters on the final mechanical properties of hot rolled products has been studied. For this purpose, three different finishing temperatures of 950, 900 and 850 °C below the non-recrystallization temperature and one temperature of 800 °C in the intercritical range were chosen. It is observed that decreasing the finishing temperature causes increase of strength and decrease of total elongation. This is accompanied by more grain refinement of microstructure and the morphology was... 

    The effects of annealing phenomena on the energy absorption of roll-bonded Al-steel sheets during wedge tearing

    , Article Materials Science and Engineering A ; Volume 527, Issue 27-28 , 2010 , Pages 7329-7333 ; 09215093 (ISSN) Beygi, R ; Kazeminezhad, M ; Sharif University of Technology
    The purpose of this paper is to investigate the effects of annealing phenomena on the energy absorption of Al-steel bilayer sheets, bonded by cold rolling, through wedge tearing. Tearing by wedge is a dissipating energy system that includes three components: cutting, friction and plastic deformation due to bending. In order to find the bonding and annealing effects on energy absorption, the non-bonded bilayer sheets are prepared in the same condition of bonded ones. The results show that energy absorption of bonded sheets is larger than that of non-bonded ones. This is due to different plastic bending moment of bonded and non-bonded bilayer sheets. Whenever the bond is improved by heat... 

    Seismic assessment of steel frames with the endurance time method

    , Article Journal of Constructional Steel Research ; Volume 66, Issue 6 , 2010 , Pages 780-792 ; 0143974X (ISSN) Riahi, H. T ; Estekanchi, H. E ; Sharif University of Technology
    In the endurance time (ET) method, structures are subjected to a specially designed intensifying ground acceleration function and their performance is judged based on their response at various excitation levels. A range of equivalent intensities can be covered in a single numerical or experimental simulation, thus significantly reducing the computational demand as compared to full nonlinear response-history analyses. The applied excitation intensity at various times has been correlated with those of the scaled ground motions. Response spectra of seven ground motions on stiff soil were used to produce intensifying acceleration functions that at each time window produce a response spectrum... 

    Electrochemically Assisted Photocatalytic Oxidation of Methanol on TiO2 Nanotube Arrays

    , Article Journal of Materials Science and Technology ; Volume 26, Issue 6 , June , 2010 , Pages 535-541 ; 10050302 (ISSN) Mohammadpour, R ; Irajizad, A ; Taghavinia, N ; Rahman, M ; Ahadian, M. M ; Sharif University of Technology
    The influence of an externally applied bias on photocatalytic performance of crystallized TiO2/Ti nanotubular electrode formed by anodization in fluoride-based electrolyte were investigated and compared to the behavior of multiporous TiO2 electrode. The photoelectrocatalytic oxidation behavior of methanol over the nanotubular electrode has been studied by measuring photocurrent response, potentiodynamic polarization spectroscopy and using electrochemical impedance spectroscopy (EIS). It was found that the photoelectrocatalytic oxidation and the charge transfer rate constant of reaction on TiO2/Ti nanotubular electrode can significantly be increased by applying electrochemical bias. Moreover,... 

    Investigation on the effects of hot forging parameters on the austenite grain size of vanadium microalloyed forging steel (30MSV6)

    , Article Journal of Alloys and Compounds ; Volume 490, Issue 1-2 , February , 2010 , Pages 572-575 ; 09258388 (ISSN) Babakhani, A ; Ziaei, S. M. R ; Kiani Rashid, A. R ; Sharif University of Technology
    It is known that the thermomechanical processing is one of the most important techniques for improving quality and mechanical properties of microalloyed steels. In this paper, the main parameters of hot forging (preheat temperature, strain and post-forging cooling rate) on the primary austenite grain size of vanadium microalloyed steel (30MSV6) were studied. From this investigation, it was found that increasing preheat temperature from 1150 °C to 1300 °C will result in a decrease in grain size number. Furthermore, it has shown that as the strain increases, the austenite grain size number increases, as is evident for the two cooling rates of 2.5 °C/s and 1.5 °C/s for primary austenite.... 

    Surrogate-based pareto optimization of annealing parameters for severely deformed steel

    , Article Materials and Design ; Volume 92 , 2016 , Pages 1062-1069 ; 02641275 (ISSN) Ghiabakloo, H ; Lee, K ; Kazeminezhad, M ; Kang, B. S ; Sharif University of Technology
    Elsevier Ltd  2016
    Severe plastic deformation (SPD) is a metalworking technique that is used for the enhancement of the strength and hardness of metallic materials. As SPD causes ductility deterioration, materials typically necessitate annealing for ductility increase; however, annealing may conversely affect strength and hardness. Thus, to optimally balance strength, hardness, and ductility, this study determined annealing conditions with a severely deformed low carbon steel sheet by adjusting annealing time and temperature. For the facilitation of the annealing process optimization, measurements of strength, hardness, and ductility under various annealing conditions were represented by regression Kriging....