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    Design and Analysis of Inexact Nonmonotone Sequential Quadratic Programming Algorithms for Large-Scale Nonlinear Optimization

    , Ph.D. Dissertation Sharif University of Technology Ahmadzadeh Salot, Hani (Author) ; Mahdavi Amiri, Nezameddin (Supervisor)
    Abstract
    Two algorithms for solving constrained nonlinear programming problems (NLPs) are proposed. The first algorithm is an inexact nonmonotone filter sequential quadratic programming iNFSQP method. In each iteration of the algorithm, the search direction is computed using an inexact solution of a strictly convex quadratic program (QP). The search direction is a descent direction for the objective function (in feasible iterations) or a descent direction for the constraints violation function (in infeasible iterations). In this algorithm, the penalty parameter is updated in such a way that the search direction is a descent direction for the penalty function, which is a combination of the objective... 

    Electrochemical behavior of S-doped nanostructured TiO2 layer synthesized with PEO process for photocatalytic applications

    , Article Advanced Materials Research ; Volume 829 , 2014 , Pages 487-491 ; ISSN: 10226680 ; ISBN: 9783037859070 Ahmadzadeh, M ; Ghorbani, M ; Sharif University of Technology
    2014
    Abstract
    Sulfur doped and pure micro-nanoporous TiO2 film were synthesized with PEO method to produce a film with a high surface area for photocatalysis applications. The effect of applied voltage and electrolyte concentration on the microstructure and photocatalytic properties of the prepared layer were investigated via SEM, XRD, EIS and DRS studies. Electrochemical Impedance Spectroscopy (EIS) was carried out in order to determine the corrosion and electrochemical properties of the produced layer. It was found that although the barrier layer resistance decreases with the voltage, the layers porosity and consequently the surface area increases. Finally the XRD and DRS spectrums were correlated with... 

    Electrochemical and Photocatalytic Behaviour of V&S Doped Titania Produced with Plasma Electrolytic Oxidation

    , M.Sc. Thesis Sharif University of Technology Ahmadzadeh, Mohammad (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    Plasma Electrolytic Oxidation is a new and promising method for synthesis of oxide layers and coatings on light metals such as titanium and aluminum. This method is a fast, easy and economicalway to produce TiO2 layers on Ti substrate. Photocatalytic properties of TiO2 can be improved with doping of other elements such as metals and non-metals by expanding its band gap which is in UV area of light spectrum in to visible area.Photocatalytic properties of TiO2 is also dependent on surface area and grain size, oxide layers which has been produced with PEO process has a high surface area due to its porosity. Voltage, electrolyte and additives concentration are among parameters which can affect... 

    A competitive inexact nonmonotone filter SQP method: convergence analysis and numerical results

    , Article Optimization Methods and Software ; 2021 ; 10556788 (ISSN) Ahmadzadeh, H ; Mahdavi Amiri, N ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    Abstract
    We propose an inexact nonmonotone successive quadratic programming (SQP) algorithm for solving nonlinear programming problems with equality constraints and bounded variables. Regarding the value of the current feasibility violation and the minimum value of its linear approximation over a trust region, several scenarios are envisaged. In one scenario, a possible infeasible stationary point is detected. In other scenarios, the search direction is computed using an inexact (truncated) solution of a feasible strictly convex quadratic program (QP). The search direction is shown to be a descent direction for the objective function or the feasibility violation in the feasible or infeasible... 

    A new inexact nonmonotone filter sequential quadratic programming algorithm

    , Article 5th International Conference on Numerical Analysis and Optimization: Theory, Methods, Applications and Technology Transfer, NAOV 2020, 6 January 2020 through 9 January 2020 ; Volume 354 , 2021 , Pages 1-24 ; 21941009 (ISSN) ; 9783030720391 (ISBN) Ahmadzadeh, H ; Mahdavi Amiri, N ; Sharif University of Technology
    Springer  2021
    Abstract
    An inexact nonmonotone filter sequential quadratic programming algorithm is presented for solving general constrained nonlinear programming problems. At every iteration, a steering direction is computed as a minimizer of a linear model of the constraint violation over a trust region. A possible infeasible stationary point can be detected using the steering direction. If the current iterate is not an infeasible stationary point, a strongly convex feasible quadratic programming subproblem is defined to compute a search direction as an inexact solution satisfying some loose and achievable conditions. We prove that the search direction is a descent direction for the constraint violation or the... 

    A competitive inexact nonmonotone filter SQP method: convergence analysis and numerical results

    , Article Optimization Methods and Software ; 2021 ; 10556788 (ISSN) Ahmadzadeh, H ; Mahdavi Amiri, N ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    Abstract
    We propose an inexact nonmonotone successive quadratic programming (SQP) algorithm for solving nonlinear programming problems with equality constraints and bounded variables. Regarding the value of the current feasibility violation and the minimum value of its linear approximation over a trust region, several scenarios are envisaged. In one scenario, a possible infeasible stationary point is detected. In other scenarios, the search direction is computed using an inexact (truncated) solution of a feasible strictly convex quadratic program (QP). The search direction is shown to be a descent direction for the objective function or the feasibility violation in the feasible or infeasible... 

    A new inexact nonmonotone filter sequential quadratic programming algorithm

    , Article 5th International Conference on Numerical Analysis and Optimization: Theory, Methods, Applications and Technology Transfer, NAOV 2020, 6 January 2020 through 9 January 2020 ; Volume 354 , 2021 , Pages 1-24 ; 21941009 (ISSN); 9783030720391 (ISBN) Ahmadzadeh, H ; Mahdavi Amiri, N ; Sharif University of Technology
    Springer  2021
    Abstract
    An inexact nonmonotone filter sequential quadratic programming algorithm is presented for solving general constrained nonlinear programming problems. At every iteration, a steering direction is computed as a minimizer of a linear model of the constraint violation over a trust region. A possible infeasible stationary point can be detected using the steering direction. If the current iterate is not an infeasible stationary point, a strongly convex feasible quadratic programming subproblem is defined to compute a search direction as an inexact solution satisfying some loose and achievable conditions. We prove that the search direction is a descent direction for the constraint violation or the... 

    A competitive inexact nonmonotone filter SQP method: convergence analysis and numerical results

    , Article Optimization Methods and Software ; Volume 37, Issue 4 , 2022 , Pages 1310-1343 ; 10556788 (ISSN) Ahmadzadeh, H ; Mahdavi Amiri, N ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    We propose an inexact nonmonotone successive quadratic programming (SQP) algorithm for solving nonlinear programming problems with equality constraints and bounded variables. Regarding the value of the current feasibility violation and the minimum value of its linear approximation over a trust region, several scenarios are envisaged. In one scenario, a possible infeasible stationary point is detected. In other scenarios, the search direction is computed using an inexact (truncated) solution of a feasible strictly convex quadratic program (QP). The search direction is shown to be a descent direction for the objective function or the feasibility violation in the feasible or infeasible... 

    Fast and scalable quantum computing simulation on multi-core and many-core platforms

    , Article Quantum Information Processing ; Volume 22, Issue 5 , 2023 ; 15700755 (ISSN) Ahmadzadeh, A ; Sarbazi Azad, H ; Sharif University of Technology
    Springer  2023
    Abstract
    Quantum computing is an emerging and promising computational paradigm that provides substantial speedup for a variety of tasks such as integer factorization, database search, and machine learning. One of the quantum computation features is the possibility of developing quantum algorithms, which could be faster than algorithms developed for classic computers. However, we are still unable to fully realize a physical quantum computer and depend on traditional computers to simulate their behavior and test quantum algorithms. This is a source of complexity since one of the challenges to simulate quantum algorithms is the exponential memory requirement. In this work, we propose a method to... 

    Numerical Study of Heat Transfer Enhancement in Porous Medium by Applying Magnetic Field on Nano Fluid

    , M.Sc. Thesis Sharif University of Technology Morshedi, Golnoosh (Author) ; Sadrhosseini, Hani (Supervisor)
    Abstract
    A 2D simulation has been carried out to study the effect of magnetic field on heat transfer and pressure drop of nanofluid flowing through a pipe filled with porous medium. The nanofluid flow is modeled as a single-phase flow, and Darcy–Brinkman–Forchheimer equation is employed to model fluid flow in porous media. A constant uniform heat flux was imposed on the walls of the cylinder, and the values of Darcy number, Hartmann number, and volume fraction of the nanoparticles were selected as 0.1, 200, and 0.2, respectively. Effects of parameters such as Reynolds number, the material of the porous medium (conductivity and porosity), and material of nanofluids have been investigated in the... 

    Hybrid Design of Recommender Systems

    , M.Sc. Thesis Sharif University of Technology Ahmadzadeh Asl, Ali (Author) ; Izadi, Mohammad (Supervisor)
    Abstract
    Nowadays recommender systems are one of the most important parts of big websites. These systems help users to find their intended items among enormous amounts of data. Traditionally, recommender systems are designed and implemented using different methods such as content based, collaborative and demographic filtering. Each of these methods had some problems that lead to emergence of a new kind of recommender systems called hybrid recommender systems. This kind of recommender systems try to combine the other methods and make them better. In this thesis, we have selected some previous recommender systems and then, we have made a new system by combining and reforming them. The resulted... 

    Experimental Study of Effect of Capillary Pressure on Archie Parameters for one of Iranian Petroleum Rock

    , M.Sc. Thesis Sharif University of Technology Hasani Ahmadzadeh, Peyman (Author) ; Masihi, Mohsen (Supervisor)
    Abstract
    The most fundamental concept in considering electrical properties of reservoir rocks are formation Resistivity factor and Resistivity index which are defined by Archie and are useful in interpretation of well logging, evaluation of porosity and saturation. A theory on the relationship between formation resistivity factor and porosity, also resistivity index and saturation are presented by use of parameters Cementation factor and Saturation exponent. The Archie equation is valid only when the rock is strongly water-wet and clay free, which is not the case in carbonate rocks. Therefore the Archie equation cannot be generalized over the entire carbonate reservoirs. On the other hand influence... 

    Design and Manufacturing of Atmospheric Water Generation in Hot and Humid Area

    , M.Sc. Thesis Sharif University of Technology Rastegari, Amin (Author) ; Sadr Hosseini, Hani (Supervisor)
    Abstract
    This experimental study evaluates the implementation of atmospheric water generator (AWG) apparatus for rural households to supply the needed water. Humid (atmospheric) air is sucked into the condenser and passed through an air filter by a fan; since the temperature of the condenser is lower than the ambient air temperature (dew point temperature), the moist in the atmospheric air is condensed and freshwater is collected which is stored in a tank and after 7 stages of purification will be ready to drink.Data of this project is obtained from Kish Island’s weather station to find the average temperature and humidity. Kish Island is chosen for this project because of its high humidity and... 

    Surface/interface effects on elastic behavior of a screw dislocation in an eccentric core-shell nanowire

    , Article International Journal of Solids and Structures ; Volume 49, Issue 13 , 2012 , Pages 1665-1675 ; 00207683 (ISSN) Ahmadzadeh Bakhshayesh, H ; Gutkin, M.Y ; Shodja, H. M ; Sharif University of Technology
    2012
    Abstract
    The elastic behavior of a screw dislocation which is positioned inside the shell domain of an eccentric core-shell nanowire is addressed with taking into account the surface/interface stress effect. The complex potential function method in combination with the conformal mapping function is applied to solve the governing non-classical equations. The dislocation stress field and the image force acting on the dislocation are studied in detail and compared with those obtained within the classical theory of elasticity. It is shown that near the free outer surface and the inner core-shell interface, the non-classical solution for the stress field considerably differs from the classical one, while... 

    Comprehensive reactive receiver modeling for diffusive molecular communication systems: reversible binding, molecule degradation, and finite number of receptors

    , Article IEEE Transactions on Nanobioscience ; Volume PP, Issue 99 , 2016 ; 15361241 (ISSN) Ahmadzadeh, A ; Arjmandi, H ; Burkovski, A ; Schober, R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    This paper studies the problem of receiver modeling in molecular communication systems. We consider the diffusive molecular communication channel between a transmitter nanomachine and a receiver nano-machine in a fluid environment. The information molecules released by the transmitter nano-machine into the environment can degrade in the channel via a first-order degradation reaction and those that reach the receiver nanomachine can participate in a reversible bimolecular reaction with receiver receptor proteins. Thereby, we distinguish between two scenarios. In the first scenario, we assume that the entire surface of the receiver is covered by receptor molecules. We derive a closed-form... 

    Studying the Interaction Between Dislocation Sandin Homogeneities in Nano-Scale, by Incorporating Surface Effect

    , M.Sc. Thesis Sharif University of Technology Ahmadzadeh Bakhshayesh, Hossein (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    Abstract
    By considering the effect of surface/interface stress, classical problems of the interaction between dislocations and inhomogeneities are addressed. Especifically two distinct problems are solved, the first one is consisted of an edge dislocation located near an elliptical nano-inhomogeneity and the second one hasa screw dislocation laid in the core-shell nanowire. The stress field as well as the image force on the dislocation are calculated and discussed in detail. Results show that by decreasing the dimension of the problem to nano-scale, the differences between classical elasticity and surface approachincrease rapidly. By considering the effect of the surface/interface stress, new... 

    High performance GPU implementation of k-NN based on Mahalanobis distance

    , Article CSSE 2015 - 20th International Symposium on Computer Science and Software Engineering, 18 August 2015 ; 2015 ; 9781467391818 (ISBN) Gavahi, M ; Mirzæi, R ; Nazarbeygi, A ; Ahmadzadeh, A ; Gorgin, S ; Sharif University of Technology
    2015
    Abstract
    The k-nearest neighbor (k-NN) is a widely used classification technique and has significant applications in various domains. The most challenging issues in the k-nearest neighbor algorithm are high dimensional data, the reasonable accuracy of results and suitable computation time. Nowadays, using parallel processing and deploying many-core platforms like GPUs is considered as one of the popular approaches to improving these issues. In this paper, we present a novel and accurate parallel implementation of k-NN based on Mahalanobis distance metric in GPU platform. We design and implement k-NN for GPU architecture and utilize mathematic and algorithmic techniques to eliminate repetitive... 

    In extended quasi-switched Z-source inverter

    , Article 10th International Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2019, 12 February 2019 through 14 February 2019 ; Pages 189-194 , 2019 ; 9781538692547 (ISBN) Sabahi, M ; Babaei, E ; Ahmadzadeh, T ; Kolahian, P ; Tarzamni, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    In this paper, a new extended quasi-switched Z-source inverter, using a switched-inductor cell, is proposed. The most important advantage of the proposed inverter is achieving the maximum voltage gain in the lower duty cycle with less circuit components than similar previous inverters, which causes the modulation index value increase. Furthermore, it leads to less power losses and less voltage and current ripples. The employed control method in this inverter is the pulse width modulation (PWM) simple boost control method. In this paper, theoretical analysis and comparison results of the proposed inverter with other similar ones are prepared. In addition, the experimental results reconfirm... 

    A Coarse -Grained Model for Molecular Dynamics Simulation of Crystalline Nano- Structures

    , M.Sc. Thesis Sharif University of Technology Ahmadzadeh, Baharan (Author) ; Khoei, Amir Reza (Supervisor) ; Jahanshahi, Mohsen ($item.subfieldsMap.e)
    Abstract
    In this work, we investigate the application of coarse graining (CG) methods to molecular dynamics (MD) simulations. These methods provide access to length and time scales previously inaccessible to traditional materials, simulation techniques. However, care must be taken when applying any coarse graining strategy to ensure that we preserve the material properties of the system we are interested in. The most prominent of these techniques is the so called multi scale coarse graining (MS-CG) method. In this study we will focus on the modeling of crystalline Nano structures using coarse graining as one of the approaches in multi scale analysis the force matching method is mainly followed to... 

    Simulation of Flow Drag Reduction through Air Injection from the Porous Wall

    , M.Sc. Thesis Sharif University of Technology Boyerahmadi, Amirhossein (Author) ; Moosavi, Ali (Supervisor) ; Sadrhosseini, Hani (Supervisor)
    Abstract
    The effect of using backpressure of air injection in a microchannel on internal flow pressure drop were investigated in this study. Multiphase flows are commonly encountered in gas and oil industries. Flow fields in production operations are often complex and include multiphase flows of gas and liquid. Previously, because of their complex nature, these flow patterns have been mostly investigated only experimentally and empirical correlations based on the experimental data. From another point of view, it is almost impossible to experimentally realize all the flow conditions for each of the flow patterns. Nowadays computer facilities provide the tool to construct and use large-scale...