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    Minimization of Wet End disturbances during web breaks using online LAV estimation

    , Article Control Engineering Practice ; Volume 18, Issue 4 , 2010 , Pages 433-447 ; 09670661 (ISSN) Nobakhti, A ; Wang, H ; Sharif University of Technology
    Abstract
    During a Wet End break, the loss of paper feed through the paper machine causes loss of sensory information and the remaining parts of the process are operated in open-loop. This causes the stock composition in the Headbox to deviate substantially from the nominal specifications, causing paper quality (after start up) and paper machine runability issues. In this work, the Base Sheet Ash measurement of the scanner is estimated using a least absolute value (LAV) model which can then be used for control of the chalk valve during the breaks to keep the Headbox Ash within specified limits. The model is computed using a very fast optimization algorithm which is able to compute the LAV solution... 

    Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    , Article Journal of Nanoparticle Research ; Volume 18, Issue 9 , 2016 ; 13880764 (ISSN) Behzadi, A ; Mohammadi, A ; Sharif University of Technology
    Springer Netherlands 
    Abstract
    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at... 

    Roll bonding of AA5052 and polypropylene sheets: bonding mechanisms, microstructure and mechanical properties

    , Article Journal of Adhesion ; 2016 , Pages 1-25 ; 00218464 (ISSN) Rezaei Anvar, B ; Akbarzadeh, A ; Sharif University of Technology
    Taylor and Francis Inc  2016
    Abstract
    Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was... 

    Toward a hydrocarbon-based chemical for wettability alteration of reservoir rocks to gas wetting condition: implications to gas condensate reservoirs

    , Article Journal of Molecular Liquids ; Volume 248 , 2017 , Pages 100-111 ; 01677322 (ISSN) Erfani Gahrooei, H. R ; Ghazanfari, M. H ; Sharif University of Technology
    Abstract
    Recently, wettability alteration has been much attended by researchers for studying well productivity improvement in gas condensate reservoirs. Previous studies in this area only utilized water/alcohol based chemicals for this purpose. While, hydrocarbon nature of the blocked condensate in retrograde gas reservoirs, may motivate application of hydrocarbon based chemical agents. In this study, a new hydrocarbon based wettability modifier is introduced to alter wettability of carbonate and sandstone rocks to preferentially gas wetting condition. Static and dynamic contact angle measurements, spontaneous imbibition and core flooding tests were conducted to investigate the effect of proposed... 

    Application of a water based nanofluid for wettability alteration of sandstone reservoir rocks to preferentially gas wetting condition

    , Article Journal of Molecular Liquids ; Volume 232 , 2017 , Pages 351-360 ; 01677322 (ISSN) Erfani Gahrooei, H. R ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    Condensate and water banking around gas condensate wells result in vital well deliverability issues. Wettability alteration of near wellbore region to gas wetting condition is known to be the most novel and the only permanent method, to improve condensate well productivity. In this work, a water based nanofluid is used to change the wettability of sandstone reservoir rocks from strongly liquid wetting to intermediate gas wetting condition. Static contact angle measurements demonstrated significant increase of liquid phase contact angle as a result of chemical treatment with SurfaPore M nanofluid. The characteristics of SurfaPore M adsorption on sandstone rock are quantified through kinetic... 

    Co-doping a metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn) on Mn/ZSM-5 catalyst and its effect on the catalytic reduction of nitrogen oxides with ammonia

    , Article Research on Chemical Intermediates ; Volume 43, Issue 4 , 2017 , Pages 2143-2157 ; 09226168 (ISSN) Saeidi, M ; Hamidzadeh, M ; Sharif University of Technology
    Springer Netherlands  2017
    Abstract
    Selective catalytic reduction (SCR) of NOx by NH3 over a series of Mn–M/Z catalysts (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, and Z = the ZSM-5 Zeolite) synthesized by wet impregnation method was investigated. Mn–Fe/Z, Mn–Co/Z, and Mn–Cu/Z catalysts exhibited approximately 100 % NOx conversion over a wide temperature range (200–360 °C) in a defined atmospheric condition, which was noticeably greater than that of Mn–Cr/Z (340–360 °C). Furthermore, the effect of addition of second metal oxide species to the initial Mn/Z catalyst on the structure of catalysts was studied by several characterization techniques. BET measurements revealed high surface area and pore volume of the Mn–Cu/Z catalyst. In... 

    Effect of soil structure and disturbance on hydromechanical behavior of collapsible loessial soils

    , Article International Journal of Geomechanics ; Volume 17, Issue 1 , 2017 , Pages 1-15 ; 15323641 (ISSN) Mohsen Haeri, S ; Khosravi, A ; Akbari Garakani, A ; Ghazizadeh, S ; Sharif University of Technology
    American Society of Civil Engineers (ASCE)  2017
    Abstract
    To characterize the role of specimen disturbance and structure in the hydromechanical behavior of collapsible soils, two sets of wetting-induced collapse and suction-controlled triaxial tests were conducted on intact and reconstituted specimens of a loessial soil taken from a loess deposit in Gorgan, a city in the northeastern Golestan province of Iran. The testing approach used an advanced triaxial testing device that was specifically modified to control pressures applied to a soil specimen and to monitor and measure the amount of changes in volume and water content of the soil specimens during testing using highly sensitive digital sensors with an accuracy of 60.01 cm3. Results of the... 

    A facile approach for reducing the working voltage of Au/TiO2/Au nanostructured memristors by enhancing the local electric field

    , Article Nanotechnology ; Volume 29, Issue 1 , 2018 ; 09574484 (ISSN) Arab Bafrani, H ; Ebrahimi, M ; Bagheri Shouraki, S ; Moshfegh, A. Z ; Sharif University of Technology
    Institute of Physics Publishing  2018
    Abstract
    Memristor devices have attracted tremendous interest due to different applications ranging from nonvolatile data storage to neuromorphic computing units. Exploring the role of surface roughness of the bottom electrode (BE)/active layer interface provides useful guidelines for the optimization of the memristor switching performance. This study focuses on the effect of surface roughness of the BE electrode on the switching characteristics of Au/TiO2/Au three-layer memristor devices. An optimized wet-etching treatment condition was found to modify the surface roughness of the Au BE where the measurement results indicate that the roughness of the Au BE is affected by both duration time and... 

    Stick-slip behavior of sessile drop on the surfaces with irregular roughnesses

    , Article Chemical Engineering Research and Design ; Volume 160 , 2020 , Pages 216-223 Azadi Tabar, M ; Shayesteh, M ; Shafiei, Y ; Ghazanfari, M. H ; Sharif University of Technology
    Institution of Chemical Engineers  2020
    Abstract
    In this work, sessile drop and low-bond axisymmetric drop shape analysis methods were coupled to provide some new aspects on stick-slip behavior as well as stick time of a drop on calcite surfaces. Slightly hydrophobic calcite surfaces typified with three irregular roughnesses were used to create irregular surfaces to mimic defects for the water-calcite-air systems. Polishing papers of 200, 600, and 1200 grit and a polishing machine were used to prepare surfaces. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transform infrared, and atomic force microscopy techniques were employed to evaluate the chemical and physical properties of surfaces. A model was developed to predict... 

    Experimental investigation on the dominating fluid-fluid and rock-fluid interactions during low salinity water flooding in water-wet and oil-wet calcites

    , Article Journal of Petroleum Science and Engineering ; Volume 204 , 2021 ; 09204105 (ISSN) Farhadi, H ; Fatemi, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    Low salinity water flooding (LSWF) has the potential to enhance the oil recovery by affecting the fluid-fluid and rock-fluid interactions. Therefore, a systematic investigation on the effect of initial wetting state (water-wet or oil-wet) of pure calcite is conducted to study the importance of these interactions on the effectiveness of LSWF. In the case of initially water-wet cores, more oil recovery efficiency is observed for more saline water cases. To shed light on the possible involved mechanisms, dynamic IFT, dynamic contact angle (CA), oil/brine and rock/brine surfaces zeta potentials, and effluent pH are measured. It is shown that the short-term effect of IFT reduction and long-term... 

    A vacuum-re lled tensiometer for deep monitoring of in-situ pore water pressure

    , Article Scientia Iranica ; Volume 27, Issue 2 , 2021 , Pages 596-606 ; 10263098 (ISSN) Sadeghi, H ; Chiu, A. C. F ; Ng, C. W. W ; Jafarzadeh, F ; Sharif University of Technology
    Sharif University of Technology  2021
    Abstract
    Real-time measurement of soil water pressure has been recognized as an essential part of investigating water ow in unsaturated soils. Tensiometry, amongst di erent measuring techniques, is a common method for direct evaluation of water pressure. However, the lower limit of measurable water pressure by a conventional tensiometer becomes even more limited by increasing its length in the vertical installation. This paper describes the development of a Vacuum-Re lled Tensiometer (VRT) for monitoring soil water pressure independent of installation depth. This is achieved by xing the distance between pressure sensor and ceramic cup together with incorporating an ancillary vacuum-re lling assembly... 

    On the adsorption behavior of a fluorochemical onto carbonate rock with the application of wettability alteration to a gas wetting condition

    , Article Journal of Molecular Liquids ; Volume 326 , 2021 ; 01677322 (ISSN) Shayesteh, M ; Azadi Tabar, M ; Shafiei, Y ; Fakhroueian, Z ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    In this study, some new aspects of adsorption of a fluorochemical onto carbonate rocks as a wettability alteration agent to a gas wetting condition with the potential application for reduction of condensate blockage in gas condensate reservoirs are presented. To achieve this, kinetics, equilibrium, and thermodynamic of the adsorption process besides contact angle, imbibition, and characterization tests are investigated. Results of adsorption experiments revealed that kinetics behavior of the utilized fluorochemical–calcite system obeyed the pseudo-second order kinetics model. There was no change in adsorption after about 20 h. Also, the intraparticle diffusion mechanism was not the only rate... 

    Super gas wet and gas wet rock surface: state-of- the art evaluation through contact angle analysis

    , Article Petroleum ; 2021 ; 24056561 (ISSN) Azadi Tabar, M ; Dehghan Monfared, A ; Shayegh, F ; Barzegar, F ; Ghazanfari, M. H ; Sharif University of Technology
    KeAi Communications Co  2021
    Abstract
    Recently, super gas wet and gas wet surfaces have been extensively attended in petroleum industry, as supported by the increasing number of publications in the last decade related to wettability alteration in gas condensate reservoirs. In many cases, contact angle measurement has been employed to assess the wettability alteration. Even though contact angle measurement seems to be a straightforward approach, there exist many misuses of this technique and consequently misinterpretation of the corresponding results. In this regard, a critical inspection of the most recent updated concepts and the intervening parameters in the contact angle based wettability evaluation of liquid-solid-gas... 

    Tuning the wetting properties of SiO2-based nanofluids to create durable surfaces with special wettability for self-cleaning, anti-fouling, and oil-water separation

    , Article Industrial and Engineering Chemistry Research ; Volume 61, Issue 23 , 2022 , Pages 8005-8019 ; 08885885 (ISSN) Esmaeilzadeh, P ; Ghazanfari, M. H ; Molaei Dehkordi, A ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    Surfaces with special wettability have aroused lots of attention due to their broad applications in many fields. In this work, we systematically report selective and various fabrications of nanofluids based on readily available materials such as SiO2 nanoparticles and polydimethylsiloxane to create superhydrophobic, superoleophobic, superhydrophilic/superoleophobic, and underwater superoleophobic coatings. The efficiency of prepared coatings is investigated on mineral rock plates as porous substrates via the straightforward and cost-effective solution-immersion technique. The static water contact angle of 170°, effortless bouncing of water droplets, and self-cleaning property with a near... 

    Chemical Vapor Processing of 2D MoS2 Nanolayers for Next Generation Inoptoelectronic Devices: Characterization and Properties

    , M.Sc. Thesis Sharif University of Technology Sovizi, Saeed (Author) ; Simchi, Abdolreza (Supervisor)
    Abstract
    Quite a few methods have been reported to synthesize monolayer MoS2, which has recently attracted scientist attentions. Fully controlled conditions, however, have not been achieved in these methods. In this research, two-dimensional MoS2 nanofilms have been synthesized by Chemical Vaper Deposition (CVD). Layer thickness of synthesized layer and effects of various parameters of used method have been investigated. Although every scientist synthesizes 2D MoS2 at 650°C in the CVD method by using seeds, in this research, it has been proved that MoS2 nanofilms can be produced at 575°C without using any seeds, which leads to lower consumption of time and price and increases the quality of... 

    Impact of Hydraulic Hysteresis on Hydro-mechanical Behaviour of Infilled Fractured Rocks in Unsaturated Condition

    , M.Sc. Thesis Sharif University of Technology Mousavi, Masoud (Author) ; Khosravi, Ali (Supervisor)
    Abstract
    Recent studies have shown that comprehensive characterization of the behavior of infilled rock fractures under saturated and unsaturated conditions requires knowledge of morphological details of fracture surface, as well as state of stress of infill materials and their initial innate conditions (e.g., void ratio, water content, degree of saturation and dry density). This study presents the details and typical results from a new testing approach to study the hydro-mechanical behavior of the infilled rock fractures under different stress states and saturation conditions. The new testing approach incorporates the axis translation technique for suction control, a flow pump for the measurement of... 

    Experimental and Modeling Investigation of Wettability Alteration to Gas Wetting Condition in Gas Condensate Reservoirs

    , M.Sc. Thesis Sharif University of Technology Erfani Gahrooei, Hamid Reza (Author) ; Ghazanfari, Mohammad Hossein (Supervisor)
    Abstract
    During production from gas condensate reservoirs, reservoir pressure decreses to lower than dew point pressure of the reservoir fluid. Consequently, condensates will form in near wellbore regions, which significantly decrease well productivity. One of the remediations that is recently proposed for solving this problem is wettability alteration of near wellbore region to gas wetting condition. In comparison to other methods, it provides a better permanency, which is its key advantage. The main purpose of this thesis is, quantitative, qualitative and modeling study of wettability alteration of rock to gas wetting condition and verification of modeling rsults for a reservoir rock sample. Also,... 

    Three-Dimensional Polyamide Nanofibrous Scaffolds for Needle Trap Microextraction of Chlorobenzenes from Water Samples and Comparing them with Two-Dimensional Nanofibres

    , M.Sc. Thesis Sharif University of Technology Manshaei, Faranak (Author) ; Bagheri, Habib (Supervisor)
    Abstract
    In the past decades, electrospinning has been widely used for the production of micro/nanofibers. In spite of the simplicity and effectivity of the conventional electrospinning for fabricating nanofibers, compact structure and small pores of the nanofibers hinder the efficient penetration of analytes during the extraction process. In order to overcome this issue, an applicable strategy called wet electrospinnig has been employed to enlarge the pore size of the electrospun scaffolds. By applying this technique, a collector was placed at the bottom of a solvent bath and highly porous foam from polyamide nanofibers was produced immediately after freeze-drying (3D electrospinning).... 

    Experimental and Numerical Investigation of Reactive Absorption in the presence of Nanofluid and Magnetic field

    , M.Sc. Thesis Sharif University of Technology Kheirkhah Ravandi, Zahra (Author) ; Molaei Dehkordi, Asghar (Supervisor)
    Abstract
    The importance of gases and liquids absorption in the liquid falling film is mostly due to the wide applications of liquid falling film reactors in the chemical industries. In such a reactor the mass and heat transfer occur simultaneously, but in most cases, the importance of mass transfer is predominant. Therefore, the study of heat transfer in this kind of reactor is neglected. In order to improve the efficiency of absorption, different methods have been employed by researchers. Owing to the rapid growth of nanotechnology, nanofluids have widely been used for increasing the absorption of solution, recently. Magnetic fluids due to their unique combination, among different kinds of... 

    Investigation of Water Consumption Reduction and Exergoeconomic Analysis of Hybrid Cooling Towers

    , M.Sc. Thesis Sharif University of Technology Azizi Kordkandi, Mohammad (Author) ; Saidi, Mohammad Hassan (Supervisor) ; Asghari, Mohsen (Supervisor)
    Abstract
    Nowadays, cooling towers are widely used in power plants, refineries, petrochemicals and ventilation industries, but the water consumption of these towers is high and because of water crisis in Middle East and Iran, it is necessary to devise in order to reduce the water consumption of these towers. In this study separated hybrid cooling tower are used to investigate the water consumption at power plants. The rigorous Poppe method are used in order to estimate the exact amount of water loss due to evaporation in wet cooling towers. First, the effect of ambient condition, wet cooling tower cells and dry cooling tower size on the performance of hybrid cooling tower are investigated, then the...