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    Development of Low-order Model/controllers for Oil Reservoir Smart Wells

    , M.Sc. Thesis Sharif University of Technology Hemmati, Sahar (Author) ; Pishvaie, Mahmoud Reza (Supervisor)
    Abstract
    Upstream oil industry operators have turned to optimal production methods for further recoveries, such as smart wells. Control algorithms for smart wells must be equipped with online measurements, in other words, reflected in the feedback philosophy. On the other hand, after discretization, an oil reservoir's dynamic and control-driven model becomes a realization or a large-scale and sparse state space. One way to deal with this problem and provide an appropriate model for the design of smart well controllers is to use appropriate reservoir dimensional reduction methods. Therefore, to design low-order controllers, a study must first be performed at the level of the reservoir model and its... 

    Modeling and Characterizing Transient Behavior of Distillation Columns with Travelling Wave Theory

    , M.Sc. Thesis Sharif University of Technology Hemmati Alam, Narjes (Author) ; Pishvaie, Mahmoud Reza (Supervisor)
    Abstract
    Simulation and controlling nonlinear process is one of the challenging problems in academic and industrial research. Saving data for keeping history of process or arising number of calculation for optimization in control design, is forcing to decrease number of equation or order of system. One of the methods to decrease the order of distillation process is using the travelling wave theory. This solution shows god accuracy for simulation the behavior of distillation column. On the other hand finite difference method as a solver for distillation equation takes some time to converge to steady state condition and the numbers of calculation in this method are high. Finite difference method is... 

    Chemical Engineering- Transport Phenomena and Separation Processes

    , M.Sc. Thesis Sharif University of Technology Reyhani, Amin (Author) ; Safekordi, Ali Akbar (Supervisor) ; Hemmati, Mahmoud (Supervisor)
    Abstract
    In this study, experimental results of Ahvaz produced water treatment obtained in ultrafiltration process using a polymeric membrane formed from Polyacrylonitrile (PAN) with 0.2 µm poreshave been reported. In this process the effects of different factors including transmembrane pressure (TMP), cross flow velocity (CFV) and feed temperature on permeate flux, membrane fouling resistance and TOC rejection was investigated. The results show that optimum conditionswere found in the range of TMP: 1.5-3 bar, CFV: 1-1.5 m/s and operating temperature 40°C.Results show that under optimum conditions the final permeate flux for produced water of Asmari outlet of Skimmer unit was 30 L/m2.h, and the... 

    prediction of Polymeric Membrane Morphology Based on Phase Diagrams for MBR Applications

    , M.Sc. Thesis Sharif University of Technology Mohsenpour, Sajjad (Author) ; Sayf Kordi, Ali Akbar (Supervisor) ; Hemmati, Mahmoud (Supervisor) ; Rekabdar, Fatemeh (Co-Advisor)
    Abstract
    In this research, we have tried to predict the morphology of the membranes that were prepared by phase inversion method. In this research Polyvinylinedifluoride (PVDF) and dimethylacetamide (DMAc) was used as the polymer and solvent. The affect of titanium oxide (TiO2 ) and polyvinylpyrolidene (PVP) which are respectively an inorganic and an organic additive, on the morphology of the membranes was investigated. Ternary and Quadratic phase diagrams were drawn based on the Flory Huggins theory. The interaction between components was determined and the effect of interactions and molar volumes of polymer, solvent, non-solvent and additives on the binodal line was investigated. To predict... 

    Ground Water Denitrification by Packed Bed Bioreactor With KMT Packing

    , M.Sc. Thesis Sharif University of Technology Hemmati, Azadeh (Author) ; Borghei, Mehdi (Supervisor)
    Abstract
    In this study biological denitrification method by moving bed biofilm reactor is investigated. The main advantage of MBBR reactor is due to their capacity for high removal rates and low operational problems such as clogging. Two MBBRs in series with 3 liter volume each, were designed in experimental set up and used in this research. Nitrification reactor worked under aerobic conditions and denitrification reactor operated under anaerobic conditions. Methanol was used as carbon source in the reactors throughout the study. Fifty percent of each reactor volume was occupied with KMT1 packing. To finding the optimum nitrate loading rate, the concentration of ammonium and nitrate were changed from... 

    Control of resistance spot welding using model predictive control

    , Article 9th International Conference on Electrical and Electronics Engineering, 26 November 2015 through 28 November 2015 ; 2015 , Pages 864-868 ; 9786050107371 (ISBN) Hemmati, M ; Haeri, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    Nowadays, the need for industrial processes with sufficient accuracy, efficiency, and flexibility to compete world markets is inevitable. On the other hand, the advent of control techniques and increased computation power of CPUs allow implementation of complex controllers using optimization techniques to provide higher efficiency and economic productivity. Model predictive control refers to a wide range of optimization-based control methods applying explicit models to predict its prospective use. These methods of control compute control signal by minimizing the cost function so that the process output becomes very close to the optimal path. In this paper, we use a new model predictive... 

    Self-reconfiguration in highly available pervasive computing systems

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 23 June 2008 through 25 June 2008, Oslo ; Volume 5060 LNCS , 2008 , Pages 289-301 ; 03029743 (ISSN) ; 3540692940 (ISBN); 9783540692942 (ISBN) Hemmati, H ; Jalili, R ; Sharif University of Technology
    2008
    Abstract
    High availability of software systems is an essential requirement for pervasive computing environments. In such systems self-adaptation, using dynamic reconfiguration is also a key feature. However, dynamic reconfiguration potentially decreases the system availability by making parts of the system temporary frozen, especially during incomplete or faulty execution of the reconfiguration process. In this paper, we propose Assured Dynamic Reconfiguration Framework (ADRF), consisting of run-time analysis phases, assuring the desired correctness and completeness of dynamic reconfiguration process. We also specify factors that affect availability of reconfigurable software in pervasive computing... 

    Processing algorithm for a strapdown gyrocompass

    , Article Scientia Iranica ; Volume 19, Issue 3 , 2012 , Pages 774-781 ; 10263098 (ISSN) Hemmati, M ; Massoumnia, M. A ; Sharif University of Technology
    2012
    Abstract
    The problem of gyrocompassing using inertial sensors, i.e., gyros and accelerometers, is addressed. North finding, with an order of accuracy of one arc-min, is not only required for the initial alignment of inertial navigation systems, but also has a critical role to play in the guidance and navigation of ships that navigate for long periods of time. In this work, after extracting the error model of an inertial navigation system and augmenting it with the error model of inertial sensors, a processing algorithm based on the Kalman filter is designed and simulated to process the navigation system velocity error, and to estimate and correct tilt and heading errors along with gyro drifts and... 

    Identification of Damage Type and Location in Reinforced Concrete Piers of Slab– Beam Bridges Using Numerical Methods

    , M.Sc. Thesis Sharif University of Technology Hemmati, Omid (Author) ; Ahmadizadeh, Mahdi (Supervisor)
    Abstract
    Bridges are among the crucial elements of transportation networks, and play an important role in facilitating emergency relief efforts following earthquakes. For this reason, it is emparative to monitor their damages to ensure about their performace in earthquakes. The structure of a bridge is divided into two parts, namely the superstructure and substructure. Due to the relatively high rigidity and strength of superstructures, most of structural damage is usually concentrated in substructures, which may ultimately affect the overall stability of the bridge. Therefore, assessing the level of damage in the substructure is of utmost concern. This research attempts to evaluate the damage in the... 

    Manipulation of Electronic Structure in Boron Nitride Nanosheets to Improve Catalytic and Photocatalytic Properties

    , M.Sc. Thesis Sharif University of Technology Hemmati, Amir (Author) ; Simchi, Abdolreza (Supervisor)
    Abstract
    The variety of 2D materials and their wide range of properties, as well as numerous methods to manipulate them, have made this class of materials among prominent candidates for the future of the energy industry. Among the means available to tailor nanomaterials performance for such applications, introducing dopants and the creation of heteroatom-doped structures are of great interest. In this study, mixtures of urea, boric acid, and graphene oxide, as cheap and available precursors, were used to synthesize C-doped h-BN nanosheets. After the implementation of TGA/DSC to select a suitable calcination temperature of 950 C°, the samples were successfully synthesized with relatively precise... 

    Evaluation of ascorbic acid-loaded calcium phosphate bone cements: Physical properties and in vitro release behavior

    , Article Ceramics International ; Vol. 40, issue. 3 , April , 2014 , pp. 3961-3968 ; ISSN: 02728842 Hemmati, K ; Hesaraki, S ; Nemati, A ; Sharif University of Technology
    2014
    Abstract
    In this study, different concentrations of ascorbic acid (50, 100 and 200 μg/mL) were added to the liquid phase of a calcium phosphate cement (CPC). The cements were immersed in simulated body fluid (SBF) for different intervals and physical, physicochemical and mechanical properties of them were evaluated. The release of added ascorbic acid from CPCs into the SBF solution was also studied. From the results, both setting time and injectability of CPC decreased by adding ascorbic acid, however the compressive strength was sharply increased before soaking in SBF solution. But, the compressive strength values of all cements (with or without ascorbic acid) soaked in SBF solution for more than 7... 

    System modeling and optimization for islanded micro-grid using multi-cross learning-based chaotic differential evolution algorithm

    , Article International Journal of Electrical Power and Energy Systems ; Vol. 56 , 2014 , pp. 349-360 ; ISSN: 01420615 Hemmati, M ; Amjady, N ; Ehsan, M ; Sharif University of Technology
    2014
    Abstract
    This paper presents a comprehensive operation model for micro-grids (MG) operating in the islanded mode. Various energy sources of a MG including diesel engine generator, micro-turbine, wind turbine and photovoltaic cell as well as battery storage and AC/DC rectifier/inverter are modeled in the proposed framework. Fuel costs, emission costs, and operation and maintenance (O&M) costs of these sources as well as their operating limits and characteristics are considered in the model. Furthermore, a new multi-cross learning-based chaotic differential evolution (MLCDE) algorithm is presented to solve the optimization problem of MG operation. The numerical results obtained from the proposed... 

    On the convergence of heterogeneous reinforcement learning private agents to nash equilibrium in a macroeconomic policy game

    , Article Australian Journal of Basic and Applied Sciences ; Volume 5, Issue 7 , 2011 , Pages 491-499 ; 19918178 (ISSN) Hemmati, M ; Nili, M ; Sadati, N ; Sharif University of Technology
    2011
    Abstract
    A repeated inflation-unemployment game within the linear-quadratic frame-work of Barro and Gordon is studied assuming that the government would like to cheat optimally and the finite heterogeneous population of private agents attempts to learn the government's targets using a reinforcement learning algorithm. Private agents are heterogeneous in their initial expectations of inflation rate but are assumed to utilize an identical anticipatory reinforcement learning process, namely Q-learning. In our heterogeneous setting, the only way for the private agents to achieve a zero value for their loss function, is for all of them to correctly anticipate the Nash equilibrium. It is of particular... 

    Application of Worm-Like Micelles for Heavy Oil Recovery: Experimental and Modeling

    , M.Sc. Thesis Sharif University of Technology Hemmati, Nasim (Author) ; Ghaznafari, Mohammad Hossein (Supervisor)
    Abstract
    Surfactants are widely used in enhancing oil recovery. But application of worm-like micelles which seem to be a perfect candidate for enhancing heavy oil recovery have been less studied despite their significant ability in reducing interfacial tension and their high viscosity. This research consists of three parts. In the first part, the kinetic and equilibrium adsorption of surfactant on reservoir rock is experimentally investigated, and its appropriate kinetic and equilibrium adsorption model is specified. According to the adsorption models, the pseudo second order kintic coefficient of adsorption is proved to have a linear relationship with concentration, so its value at different... 

    Reinforcement learning of heterogeneous private agents in a macroeconomic policy game

    , Article Lecture Notes in Economics and Mathematical Systems ; Volume 645 , 2010 , Pages 215-226 ; 00758442 (ISSN) ; 9783642139468 (ISBN) Hemmati, M ; Nili, M ; Sadati, N ; Sharif University of Technology
    2010
    Abstract
    A repeated inflation-unemployment game within the linear-quadratic framework of Barro and Gordon is studied assuming that the government would like to cheat optimally and the finite heterogeneous population of private agents attempts to learn the government's targets using a reinforcement learning algorithm. Private agents are heterogeneous in their initial expectations of inflation rate but are assumed to utilize an identical anticipatory reinforcement learning process, namely Q-learning. In our heterogeneous setting, the only way for the private agents to achieve a zero value for their loss function, is for all of them to correctly anticipate the Nash equilibrium. It is of particular... 

    Towards a bounded-rationality model of multi-agent social learning in games

    , Article 2010 10th International Conference on Intelligent Systems Design and Applications, ISDA'10, Cairo, 29 November 2010 through 1 December 2010 ; 2010 , Pages 142-148 ; 9781424481354 (ISBN) Hemmati, M ; Sadati, N ; Nili, M ; Sharif University of Technology
    2010
    Abstract
    This paper deals with the problem of multi-agent learning of a population of players, engaged in a repeated normal-form game. Assuming boundedly-rational agents, we propose a model of social learning based on trial and error, called "social reinforcement learning". This extension of well-known Q-learning algorithm, allows players within a population to communicate and share their experiences with each other. To illustrate the effectiveness of the proposed learning algorithm, a number of simulations on the benchmark game of "Battle of Sexes" has been carried out. Results show that supplementing communication to the classical form of Q-learning, significantly improves convergence speed towards... 

    Design & Manufacture of IGF/DGF Plant in Semi Industrial Scale for Wastewater Separation

    , M.Sc. Thesis Sharif University of Technology Hemmati, Amir Hossein (Author) ; Ghotbi, Siroos (Supervisor)
    Abstract
    The increasing demand for energy forced to production of oil as one of the main sources of energy. Along with the increase in oil production, the proportion of water produced with oil is increasing relative to the oil produced. On the other hand, environmental restrictions for the discharge of industrial effluents into the environment are becoming more and more stringent every day. Before discharging the effluent into the environment, petroleum must be removed. The complexity of these issues demonstrates the need to develop new technologies and improve the efficiency of existing technologies. Gas flotation are among the technologies adopted in the field that have been used throughout the... 

    Vibration suppression of offshore wind turbine foundations using tuned liquid column dampers and tuned mass dampers

    , Article Ocean Engineering ; Volume 172 , 2019 , Pages 286-295 ; 00298018 (ISSN) Hemmati, A ; Oterkus, E ; Khorasanchi, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Highly dynamic nature of the applied loads on flexible and lightly damped offshore wind turbine (OWT) foundations affects the lifetime and serviceability of the system. In this study, the excessive vibration responses of OWTs are minimized using tuned mass dampers (TMD) and tuned liquid column dampers (TLCD). Due to high efficiency of TLCDs and TMDs for certain loading conditions, a combined TLCD-TMD is also utilized to improve the overall performance in a wide range of loading conditions. First, a parametric study was performed that highlights the sensitivity of these structural control devices. The effect of two devices on fixed offshore wind turbine foundations for the benchmark 5 MW NREL... 

    A framework to support run-time assured dynamic reconfiguration for pervasive computing environments

    , Article 2006 1st International Symposium on Wireless Pervasive Computing, Phuket, 16 January 2006 through 18 January 2006 ; Volume 2006 , 2006 , Pages 1-6 ; 0780394100 (ISBN); 9780780394100 (ISBN) Hemmati, H ; Niamanesh, M ; Jalili, R ; Sharif University of Technology
    2006
    Abstract
    With the increasing use of pervasive computing environments (PCEs), developing dynamic reconfigurable software in such environments becomes an important issue. The ability to change software components in running systems has advantages such as building adaptive, long-life, and self-reconfigurable software as well as increasing invisibility in PCEs. As dynamic reconfiguration is performed in error-prone wireless mobile systems frequently, it can threaten system safety. Therefore, a mechanism to support assured dynamic reconfiguration at run-time for PCEs is required. In this paper, we propose an Assured Dynamic Reconfiguration Framework (ADRF) with emphasis on assurance analysis. The... 

    Phosphomolybdic acid/chitosan as acid solid catalyst using for biodiesel production from pomegranate seed oil via microwave heating system: RSM optimization and kinetic study

    , Article Renewable Energy ; Volume 189 , 2022 , Pages 881-898 ; 09601481 (ISSN) Helmi, F ; Helmi, M ; Hemmati, A ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    In this research, a green solid catalyst of phosphomolybdic acid (HPA) prated on Chitosan was synthesized to produce biodiesel. The prepared catalyst was characterized using Fourier Transform Infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray (EDX), X-ray diffraction (XRD), and XRF analyses. The catalyst was applied in microwave-assisted trans-esterification of Pomegranate oil, and the biodiesel production process was optimized by response surface methodology based on central composite design (RSM-CCD). The effect of influential reaction parameters, including time (33–142 min), catalyst weight (0.15–5.6 wt%), and methanol to oil molar...