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    Experimental study and surface complexation modeling of non-monotonic wettability behavior due to change in brine salinity/composition: Insight into anhydrite impurity in carbonates

    , Article Journal of Molecular Liquids ; Volume 365 , 2022 ; 01677322 (ISSN) Madadi Mogharrab, J ; Ayatollahi, S ; Pishvaie, M. R ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    Wettability alteration as the main mechanism of improved oil recovery in carbonates during low salinity/engineered water flooding (LS/EWF) is a complex phenomenon due to high heterogeneity of rock. During LS/EWF, wettability changes when electrochemical interactions at carbonate-brine interface happen. Anhydrite impurity in carbonates is one of the most important parameters affecting the electrochemical interactions at the rock-brine interface and the wettability alteration process. Therefore, the success of LS/EWF in carbonate reservoirs lies in perceiving the role of impurities such as anhydrite, from a geochemical and dissolution point of view. Modified flotation tests (MFT) were... 

    Smart Water Optimal Injection Policy in Fractured Carbonate Reservoirs, Using Laboratory Data

    , Ph.D. Dissertation Sharif University of Technology Madadi Mogharrab, Javad (Author) ; Ayatollahi, Shahaboddin (Supervisor) ; Pishvaie, Mahmood Reza (Supervisor)
    Abstract
    Wettability alteration is the main mechanism for enhancing oil recovery in carbonate reservoirs during low salinity or engineered water flooding (LS/EWF), though it is a complex process due to the high heterogeneity of rock. During LS/EWF, wettability alteration occurs as a result of electrochemical interactions at the interface between carbonate rock and brine. One of the most critical factors affecting these interactions, and the wettability alteration process, is the presence of anhydrite impurities in the carbonate rock. Therefore, the success of LS/EWF in carbonate reservoirs lies on understanding the role of impurities like anhydrite from both geochemical and dissolution perspectives.... 

    Iranian Professional Football League’s Scheduling

    , M.Sc. Thesis Sharif University of Technology Madadi, Mahdi (Author) ; Kianfar, Ferydoon (Supervisor)
    Abstract
    Finding a proper and fair schedule for sport competitions has been an important issue, especially these days which professional sports has became a large scale business and profitability of sport competitions depends on the quality of the schedule.
    Hence in the last three decades sport scheduling has been considered by computer science and operation research scientists.
    Professional soccer league consists of many teams which compete in one round or double round robin tournament every year. In round robin tournaments each team has two matches, one at their own place and the other one at the competitors place. The main issues of the sport scheduling are the round and the host of... 

    Investigation of Plasmonic Excitation in Carbonic Nanostructures Within Near-IR

    , M.Sc. Thesis Sharif University of Technology Madadi, Mahkam (Author) ; Jamshidi, Zahra (Supervisor)
    Abstract
    To date, the plasmonic properties of many metallic and semi-conducting materials have been investigated and used in various industries. One of the plasmonic material categories that have always been considered is polycyclic aromatic hydrocarbon or PAH, whose plasmonic resonance energy depends on the charge state of the molecule. In this regard, it is easy to change the plasmonic resonance energy via changing the induced charge, which is a unique feature of the mentioned materials. In addition, plasmonic structures with excitations in the infrared region are able to enhance the vibration intensity of absorbed molecules by increasing the electric field around themselves. Therefore, they have... 

    Vector space generated by the multiplicative commutators of a division ring

    , Article Journal of Algebra and its Applications ; Volume 12, Issue 8 , December , 2013 ; 02194988 (ISSN) Aghabali, M ; Akbari, S ; Ariannejad, M ; Madadi, A ; Sharif University of Technology
    2013
    Abstract
    Let D be a division ring with center F. An element of the form xyx -1y-1 ∈ D is called a multiplicative commutator. Let T(D) be the vector space over F generated by all multiplicative commutators in D. In this paper it is shown that if D is algebraic over F and Char(D) = 0, then D = T(D). We conjecture that it is true in general. Among other results it is shown that in characteristic zero if T(D) is algebraic over F, then D is algebraic over F  

    Performance predicting modeling of axial-flow compressor at design and off-design conditions

    , Article Proceedings of the ASME Turbo Expo, 9 June 2008 through 13 June 2008, Berlin ; Volume 6, Issue PART A , 2008 , Pages 317-324 ; 9780791843161 (ISBN) Madadi, A ; Hajilouy Benisi, A ; International Gas Turbine Institute ; Sharif University of Technology
    2008
    Abstract
    Axial flow compressor is one of the most important parts of gas turbine units. Therefore, its design and performance prediction are very important. One-dimensional modeling is a simple, fast and accurate method for performance prediction of any type of compressors with different geometries. In this approach, inlet flow conditions and compressor geometry are known and by considering various compressor losses, velocity triangles at rotor, and stator inlets and outlets are determined, and then compressor performance characteristics are predicted. Numerous models have been developed theoretically and experimentally for estimating various types of compressor losses. In present work, performance... 

    Optical analog of Matthiessen's rule in a one-dimensional model for diffusive light transport in foams

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 82, Issue 4 , 2010 ; 15393755 (ISSN) Miri, M ; Kheradsoud, S ; Madadi, E ; Mokhtari, Z ; Hassani, H ; Sharif University of Technology
    2010
    Abstract
    We study photon diffusion in a one-dimensional model foam composed of thin films and Plateau borders. Each thin film or Plateau border is characterized by its own intensity transmittance. We relate | Foam, the transport-mean-free path of photons diffusing in the foam, to the foam microstructure. Denoting by l Film (l PB) the transport-mean-free path of photons in a medium composed only of thin films (Plateau borders), we find 1/ l Foam = φF / l Film + φP / l PB. Here φF and φP =1- φF are the fraction of films and Plateau borders, respectively  

    Analysis of mechanical and thermal properties of carbon and silicon nanomaterials using a coarse-grained molecular dynamics method

    , Article International Journal of Mechanical Sciences ; Volume 187 , December , 2020 Mohammadi, K ; Ali Madadi, A ; Bajalan, Z ; Nejat Pishkenari, H ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The main concern in Molecular Dynamics (MD) simulations is the computational cost, and coarse-graining methods accelerate simulations by reducing the degrees of freedom in the system. Yet, the utilization of these methods should be carefully followed. In this paper, we presented an energy-based coarse-graining method for Tersoff and Stillinger-Weber potential functions. The presented coarse-graining method is based on the domain mapping and modification of potential function. The focus of this paper is on Carbon and Silicon materials; however, this method can be applied to model other materials for which Tersoff and Stillinger-Weber potentials are defined. This method has been validated by... 

    Coarse Grained-Atomistic Concurrent Multi-Scale Modeling for Numerical Simulation of Mechanical Behavior of Heterogeneous Materials in Nano-cale

    , M.Sc. Thesis Sharif University of Technology Ali Madadi Ahmadabadi, Ashkan (Author) ; Khoei, Amir Reza (Supervisor)
    Abstract
    In this thesis, a method has been exploited to couple the atomistic domain with the coarse-grained domain. Since molecular dynamics has a high computational cost when a large number of atoms exist, coarse-grained molecular dynamics was used in which a number of atoms are assumed as a bigger bid and interatomic potential is modified for bids so that the material’s mechanical properties remain constant. This method not only reduces the computational cost of calculating forces in molecular dynamics simulation but also, the time step used in Coarse-Grained Methods can be more than atomistic simulations as the frequency of occurring phenomena in CG scale is less than atomistic scale.The advantage... 

    A fuzzy random minimum cost network flow programming problem [electronic resource]

    , Article Journal of Industrial and Systems Engineering (JISE)-Iranian Institute of Industrial Engineering ; Article 3, Volume 6, Issue 1, Spring 2012, Page 34-47 Nematian, J. (Javad) ; Eshghi, Kourosh ; Sharif University of Technology
    Abstract
    In this paper, a fuzzy random minimum cost flow problem is presented. In this problem, cost parameters and decision variables are fuzzy random variables and fuzzy numbers respectively. The object of the problem is to find optimal flows of a capacitated network. Then, two algorithms are developed to solve the problem based on Er-expected value of fuzzy random variables and chance-constrained programming. Furthermore, the results of two algorithms will be compared. An illustrative example is also provided to clarify the concept  

    Special classes of mathematical programming models with fuzzy random variables [electronic resource]

    , Article Journal of Intelligent and Fuzzy Systems, Published In: IOS Press ; Volume 19, Number 2, 2008 Eshghi, K. (Kourosh) ; Nematian, Javad ; Sharif University of Technology
    Abstract
    In this paper, we will discuss two special classes of mathematical programming models with fuzzy random variables. In the first model, a linear programming problem with fuzzy decision variables and fuzzy random coefficients is introduced. Then an algorithm is developed to solve the model based on fuzzy optimization method and fuzzy ranking method. In the second model, a fuzzy random quadratic spanning tree problem is presented. Then the proposed problem is formulated and solved by using the scalar expected value of fuzzy random variables. Furthermore, illustrative numerical examples are also given to clarify the methods discussed in this paper  

    A special class of fuzzy integer programming model with all different constraints [electronic resource]

    , Article Scientia Iranica ; Vol. 16, No. 1, pp. 1-10, 2009 Eshghi, K. (Kourosh) ; Nematian, Javad ; Sharif University Of Technology
    Abstract
    In this paper, a fuzzy approach is applied to special classes of integer programming problems with all diierent constraints. In the rst model, a fuzzy integer programming model is developed to represent the all-diierent constraints in mathematical programming. In order to solve the proposed model, a new branching scheme for the Branch and Bound algorithm is also presented. In the second model, a special class of large-scale multi-objective fuzzy integer programming problems with all-diierent constraints is introduced. A solution method for the proposed model is also developed by using the decomposition technique, weighting method and Branch and Bound algorithm. An illustrative numerical... 

    Fuzzy random minimum cost network problem [electronic resource]

    , Article Journal of Industrial and Systems Engineering ; Vol. 6, No. 1, pp 34-47, 2012 Nematian, J. (Javad) ; Eshghi, Kourosh ; Sharif University of Technology
    Abstract
    In this paper, a fuzzy random minimum cost flow problem is presented. In this problem, cost parameters and decision variables are fuzzy random variables and fuzzy numbers respectively. The object of the problem is to find optimal flows of a capacitated network. Then, two algorithms are developed to solve the problem based on Er-expected value of fuzzy random variables and chance-constrained programming. Furthermore, the results of two algorithms will be compared. An illustrative example is also provided to clarify the concept  

    Tube length-assisted optimized aerosol trapping

    , Article Optics Communications ; Vol. 329, issue , 2014 , pp. 196-199 ; ISSN: 00304018 Taheri, S. M. R ; Sadeghi, M ; Madadi, E ; S. Reihani, S. N ; Sharif University of Technology
    2014
    Abstract
    Trapping a single aerosol using optical tweezers could be of great importance for environmental sciences. Though a single nanoparticle as small as 10 nm is successfully trapped in aqueous media using optical tweezers, due to spherical aberration only large clusters of nanoparticles were stably trapped in air. In this paper we provide our theoretical and experimental results on optimized trapping of aerosols as small as 400 nm in radius by the introduction of an extra spherical aberration source in order to minimize the total spherical aberration of the system. Our method allows for trapping of high refractive index particles such as polystyrene beads in air. It also provides considerably... 

    Production of Uranium Dioxide Nano Powder With Hydrothermal Method in Supercritical Water Reactor

    , M.Sc. Thesis Sharif University of Technology Golzary, Abooali (Author) ; Outokesh, Mohammad (Supervisor) ; Ahmadi, Javad (Supervisor) ; Karimi Sabet, Javad (Co-Advisor)
    Abstract
    Hydrothermal supercritical method is one of the most suitable methods for metal oxide nano powder, ceramics and mineral catalyst synthesis. Metal oxides nanopowder in its pure or mixed form has wide potential application as chemical industrial catalyst, hot Superconductors, magnetic material, gas sensors and car catalyst convertors. One of the most important metal oxides aspects of application is uranium oxide as nuclear reactor fuel is used. In addition, UO2 is selective catalyst for converting methane to methanol process and Decomposition of organic Chlorine material. In Supercritical hydrothermal method done in high pressure reactor with critical to fluid, is new method for the... 

    Experimental Study of Pendulum Grinding of Superalloys

    , M.Sc. Thesis Sharif University of Technology Yazdani, Majid (Author) ; Akbari, Javad (Supervisor)
    Abstract
    Superalloys are widely used in aerospace and power industries due to the good performance at high temperatures for examples gas turbines, steam turbines and aircraft components. In addition to the turbines cobalt-base superalloys are used in medical implants such as knee and hip joints. The main strengths of the superalloys are heat-resistant, retaining their high mechanical and chemical properties at high temperatures, high melting temperatures, high corrosion resistance, resistance to thermal fatigue, thermal shock, creep, and erosion. Because of difficult to machine properties of superalloys, grinding is one of the effective methods for machining superalloys. The surface integrity of the... 

    Ultrasonic Assisted Deep Drilling of Super-Alloy and Comparison With Electro Discharge Drilling Method

    , M.Sc. Thesis Sharif University of Technology Baghlani, Valid (Author) ; Akbari, Javad (Supervisor)
    Abstract
    Drilling super alloys with a good hole quality and acceptable surface finish is a constant challenge in modern industries dealing with such materials. Ultrasonic assisted drilling is a modern and nonconventional method of drilling which has attracted many researchers attention recently. In this study deep drilling on Inconel 738 LC is done using ultrasonic assisted drilling technique and the results are compared with those of Electro Discharge Machininng or EDM method. The results show that Ultrasonic Assisted Drilling or UAD is an appropriate alternative for EDM of Inconel. The whole process time is decrease dimensional accuracy is improved and surface roughness is decreased significantly.... 

    Security Evaluation of Public Key Based Key Management in MANET

    , M.Sc. Thesis Sharif University of Technology Jamshidi, Farzad (Author) ; Mohajeri, Javad (Supervisor)
    Abstract
    Due to popularity of mobile wireless devices, security of mobile ad hoc networks (MANETs) being more important than before. Traditional key management schemes based on symmetric key cryptography are became ineffective because of dynamic and infrastructureless nature of these networks.Recent studies are mainly based on traditional public key cryptography schemes and ID-based cryptography schemes. On the other hand, Contributory schemes seem suitable for MANETs because of their inherent self-organize property. Key update and Key revocation are the fundamental issues of key management schemes in mobile ad hoc networks. Certificateless public key cryptography, in addition to solve those issues,... 

    Economic Cooperation Organization: Ex-post Impact and Potentials on Intra-group Trade in Non-Oil Industries Using Gravity Model

    , M.Sc. Thesis Sharif University of Technology Mesgari, Iman (Author) ; Abedini, Javad (Supervisor)
    Abstract
    International trade arrangements have been considerably developed in recent decadees. Especially, one can note the role of these factors in economic development and improvement of life standards in member countries. In the meantime, Economic Cooperation Organization (ECO) was established in 1985, by Iran, Pakistan and Turkey and then extended by seven other countries: Afghanistan, Azerbaijan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan. Improving economic development and intra-group trade of member countries is one of the main objectives for the group. The purpose of this research is to estimate the ex-post effects of ECO on the intra-group trade of member countries.... 

    Determinants of Free Trade Agreements Based on Limited Dependent Variable Models: ECO countries and their major trading partners

    , M.Sc. Thesis Sharif University of Technology Gholami, Mahdi (Author) ; Abedini, Javad (Supervisor)
    Abstract
    Establishing an efficient free trade agreement (FTA) requires some conditions in both trading partners. The median voter approach insists on the direction of general interests (identified by the utility of a median voter) to explain how two countries may agree to sign an FTA. At the other side, lobbying approach emphasizes on the role of interest groups (groups with a large influence on the public decisions) in forming FTAs. Taking into account the theoretically based and empirically robust foundation of the median voter approach, we rely on it to investigate the major determinants of free trade agreements in the case of ECO countries besides all their main trade partners. The database...