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    Experimental Study of Effect of Nano-graphen Oxide on Methane Hydrate Formation Rate and Storage Capacity

    , M.Sc. Thesis Sharif University of Technology Montazeri, Vahab (Author) ; Baghalha, Morteza (Supervisor) ; Ramazani, Ahmad (Supervisor) ; Zarenezhad, Bahman (Co-Advisor)
    Abstract
    According to the importance of conversion and transmission of energy, and introduction of hydrate formation process as an alternative method, in this study, the nano-graphene oxide is used to increase the rate if methane gas hydrates formation. The experiments were performed at different concentrations of 30 to 70 ppm and the results were compared with pure water. The effect of temperature and pressure on hydrate formation at temperatures of 1 and 2˚C and pressures of 48 and 53 bar were studied. And it was found that nano-graphene oxide can be used to accelerate the methane hydrates formation. The effect of ultrasonic on methane hydrate formation has been studied that it was found that the... 

    Investigation on Effects of Nanoparticles Presence on Hydrate Formation Characterization During Drilling

    , M.Sc. Thesis Sharif University of Technology Jalilolghadr Ardabili, Raouf (Author) ; Mohammadi, Ali Asghar (Supervisor) ; Zarenezhad, Bahman (Co-Advisor) ; Ramazani, Ahmad (Co-Advisor)
    Abstract
    In past two decades, the direction of oil and gas exploration has moved towards deep water drilling. The pressure and temperature in these zones are ideal for gas hydrate formation that can cause serious and sometimes uncontrollable issues during drilling operations. Gas hydrate formation while drilling can cause problems such as occurrence of kick and blowout, plug chock and kill line, and change in rheology of drilling mud. On the other hand, nowadays, nanotechnology has created an evolution in engineering sciences and because of the wide range of this science, drilling industry is affected like other industries. In the meantime, because of high yield, high stability and various methods of... 

    Nanofluid-assisted gas to hydrate (GTH) energy conversion for promoting CO 2 recovery and sequestration processes in the petroleum industry

    , Article Petroleum Science and Technology ; Volume 34, Issue 1 , 2016 , Pages 37-43 ; 10916466 (ISSN) Zarenezhad, B ; Montazeri, V ; Sharif University of Technology
    Taylor and Francis Inc  2016
    Abstract
    In this work the enhancement of gas to hydrate conversion employing the nanographene oxide (NGO)-based nanofluid regarding CO2 capture and sequestration recovery is investigated. A new series of experiments are carried out at different pressures, temperatures, agitation intensities and NGO promoter concentrations by using a newly developed fully automated GTH (gas to hydrate) energy converter. According to the presented results at the 3 MPa and 275.15 K and in the presence of 30 ppm NGO, it is possible to reach a CO2 gas to hydrate conversion of 95% at a low impeller speed in less than 2.5 h, which is quite interesting from an energy consumption standpoint. The presented approach can have... 

    Observation of cosmic rays by Alborz -1 array

    , Article Iranian Journal of Physics Research ; Volume 17, Issue 3 , 2017 , Pages 473-484 ; 16826957 (ISSN) Bahman Abadi, M ; Sharif University of Technology
    Isfahan University of Technology  2017
    Abstract
    The first phase of the Alborz Observatory Array (Alborz-1) consists of 20 plastic scintillation detectors each one with surface area of 0.25 m2 spread over an area of 40×40 m2 realized to the study of Extensive Air Showers around the knee at the Sharif University of Technology campus. The first stage of the project including construction and operation of a prototype system has now been completed and the electronics that will be used in the array instrument has been tested under field conditions. In order to achieve a realistic estimate of the array performance, a large number of simulated CORSIKA showers have been used. In the present work, theoretical results obtained in the study of... 

    Performance evaluation of a new nanocomposite polymer gel for water shutoff in petroleum reservoirs

    , Article Journal of Dispersion Science and Technology ; 2018 ; 01932691 (ISSN) Asadizadeh, S ; Ayatollahi, S ; ZareNezhad, B ; Sharif University of Technology
    Taylor and Francis Inc  2018
    Abstract
    A new polymer gel nanocomposite is fabricated for excess water production control (water shut off) in petroleum reservoirs and its rheological behavior is evaluated in the presence of sea water and formation water at the temperature of 100 °C. It is shown that at a high salinity without using SiO2 nanoparticles, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water are 12.5 Pa and 9.8 Pa respectively. However by incorporation of SiO2 nanoparticles in the polymer gel matrix, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water can be improved to 13.56 Pa and 11.57 Pa respectively, which is quite interesting... 

    Performance evaluation of a new nanocomposite polymer gel for water shutoff in petroleum reservoirs

    , Article Journal of Dispersion Science and Technology ; Volume 40, Issue 10 , 2019 , Pages 1479-1487 ; 01932691 (ISSN) Asadizadeh, S ; Ayatollahi, S ; ZareNezhad, B ; Sharif University of Technology
    Taylor and Francis Inc  2019
    Abstract
    A new polymer gel nanocomposite is fabricated for excess water production control (water shut off) in petroleum reservoirs and its rheological behavior is evaluated in the presence of sea water and formation water at the temperature of 100 °C. It is shown that at a high salinity without using SiO2 nanoparticles, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water are 12.5 Pa and 9.8 Pa respectively. However by incorporation of SiO2 nanoparticles in the polymer gel matrix, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water can be improved to 13.56 Pa and 11.57 Pa respectively, which is quite interesting... 

    Fabrication of a highly efficient new nanocomposite polymer gel for controlling the excess water production in petroleum reservoirs and increasing the performance of enhanced oil recovery processes

    , Article Chinese Journal of Chemical Engineering ; Volume 32 , 2021 , Pages 385-392 ; 10049541 (ISSN) Asadizadeh, S ; Ayatollahi, S ; ZareNezhad, B ; Sharif University of Technology
    Materials China  2021
    Abstract
    A new nanocomposite polymer gel is synthesized for reduction of excess water production in petroleum reservoirs at real operating conditions. This new nanocomposite gel contains SiO2 nanoparticles, partially hydrolyzed polyacrylamide (HPAM) and chromium triacetate. High pressure and high temperature tests using porous carbonate core are carried out to evaluate the effects of nanoparticles on the synthesized polymer gel performance. It is shown that the residual resistance factor ratio of water to oil using the synthesized polymer gel nanocomposite in this work is much higher than that of the ordinary polymer gels. The presented results confirm the high performance of the synthesized... 

    Robot control using an inexpensive P300 based BCI

    , Article 26th National and 4th International Iranian Conference on Biomedical Engineering, ICBME 2019, 27 November 2019 through 28 November 2019 ; 2019 , Pages 204-207 ; 9781728156637 (ISBN) Bahman, S ; Shamsollahi, M. B ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Brain Computer Interfaces (BCI) are an important concept of biomedical engineering because of their ability to improve life conditions for people with different disabilities. Lots of studies have worked on important characteristics of BCI systems, such as speed and accuracy, whereas price is an important aspect too. Thus, a low cost BCI system with high accuracy clearly can help more people. Our purpose in this study is to design a P300 based BCI system using a low-priced EEG headset which has an acceptable accuracy. Our final design got a mean real-time accuracy of 93.3% which is comparable to systems with much more expensive hardware. © 2019 IEEE  

    Improvement of Perovskite Coating to Increase Operation Efficiency of Photovoltaic Cells

    , Ph.D. Dissertation Sharif University of Technology Zarenezhad, Hamaneh (Author) ; Askari, Masoud (Supervisor) ; Halali, Mohammad (Supervisor)
    Abstract
    In this work, polyvinylidene difluoride (PVDF) as a ferroelectric polymer, polyaniline (PANI) and polypyrrole (PPy) as conductive polymer additives are used to fabricate high performance mesoporous CH3NH3PbI3-xClx mixed-halide perovskite solar cells in a sequential deposition method. Using polymer additives in perovskite precursor solution leads to modification of perovskite layer morphology by changing nucleation and growth of perovskite grains. Besides, conductive polymer additives in perovskite layer help to more charge carrier transfer. Power conversion efficiency has been enhanced from 10.40 % to 16.51% and to 13.21 % in ambient atmosphere in the presence of 1.0 wt. % of PVDF and PPy... 

    Performance Evaluation of Membrane Bioreactors in Treating Municipal Wastewater

    , M.Sc. Thesis Sharif University of Technology Hatami Bahman Beyglou, Elnaz (Author) ; Torkian, Ayoub (Supervisor)
    Abstract
    Membrane bioreactors can replace the activated sludge process and the final clarification step in municipal wastewater treatment. The combination of bioreactor and crossflow microfiltration allows for a high chemical oxygen demand (COD) reduction of synthetic wastewater. In this study, experimental data from a laboratory scale membrane bioreactor are presented. In order to investigate the influence of various operating parameters such as hydraulic retention time (HRT), biomass concentration and organic loading rate on organic pollutant removal, the pilot scale submerged membrane bioreactor (SMBR) with a Polyvinylidene Fluoride (PVDF) hollow fiber membrane module was conducted using synthetic... 

    Efficient carrier utilization induced by conductive polypyrrole additives in organic-inorganic halide perovskite solar cells

    , Article Solar Energy ; Volume 207 , 2020 , Pages 1300-1307 Zarenezhad, H ; Balkan, T ; Solati, N ; Halali, M ; Askari, M ; Kaya, S ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The morphology of the perovskite layer, the effective extraction of the charge carriers, and their transport are the main factors determining the power conversion efficiency (PCE) of the perovskite solar cells (PSCs). In this work, we demonstrated that the geometric and electronic structures of the PSCs could be modified by using a conductive polymer additive in the lead (Pb) halide layer prepared by a two-step deposition method. Polypyrrole (PPy) as a conductive polymer is used in the perovskite layers which could increase the PCE of CH3NH3PbI3-xClx mixed-halide PSCs. By adding an optimized amount of PPy, PCE has been raised from 10.4 to 13.2%. PPy acts as a conductive channel facilitating... 

    Enhanced electron transport induced by a ferroelectric field in efficient halide perovskite solar cells

    , Article Solar Energy Materials and Solar Cells ; Volume 206 , 2020 Zarenezhad, H ; Askari, M ; Halali, M ; Solati, N ; Balkan, T ; Kaya, S ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    Perovskite solar cells have been appearing as a superior photovoltaic device owing to their high photovoltaic performance and low cost of fabrication. The formation of a compact and uniform perovskite layer with large crystal size is a significant factor to get the best device performance. In this work, polyvinylidene difluoride (PVDF) was used as a ferroelectric polymer additive to fabricate high-performance mesoporous CH3NH3PbI3-xClx mixed-halide perovskite solar cells in a sequential deposition method. Power conversion efficiency has been enhanced from 10.4 to 16.51% in an ambient atmosphere in the presence of an optimized amount of PVDF assuring continuous and smooth layers with large... 

    Frozen leg operation of a three-phase dual active bridge DC/DC converter at light loads

    , Article Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC ; Volume 2018-March , 18 April , 2018 , Pages 3385-3391 ; 9781538611807 (ISBN) Haghbin, S ; Blaabjerg, F ; Yazdani, F ; Bahman, A. S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    A three-phase dual active bridge (DAB) converter is designed and constructed as the DC/DC stage of a 50 kW fast charger station. Recently introduced 300A SiC power modules and drivers are utilized in the converter to obtain a high efficiency. Each module has two interconnected switches with anti-parallel diodes resembling a converter leg. It is observed that the driver halts the module operation as a result of protective actions such as over-current, gate under-voltage, or gate overvoltage. In such case the module operates as a leg with two diodes until an external hardware signal resets the driver. The aim of this paper is to provide analysis, simulation and experiments for a three-phase... 

    Numerical Study of Various Parameters Affecting Ventilation and Fire- Induced Smoke Movement in Curved Road Tunnels

    , M.Sc. Thesis Sharif University of Technology Bahman Shamsabadi, Mohammad Mahdi (Author) ; Farhanieh, Bijan (Supervisor)
    Abstract
    When a fire breaks out in a tunnel, due to the enclosure of the interior of the road tunnels, hot and poison smoke quickly spreads in the tunnel. This phenomenon, in addition to destroy the tunnel structure, causes a lot of financial and human losses. In recent years, research into fire control has become more important with the occurrence of numerous accidents in road tunnels and fatalities. Longitudinal ventilation is still the main method for controlling smoke distribution in tunnels due to lower construction costs and acceptable efficiency. Numerous studies have been conducted to investigate the effect of different and effective parameters on fire control and smoke emissions in direct... 

    Experimental Aeroacoustic Investigation of Transient Impinging Jet Using Shock Tube

    , Ph.D. Dissertation Sharif University of Technology Bahman Jahromi, Iman (Author) ; Ebrahimi, Mohammad (Supervisor) ; Ghorbanian, Kaveh (Supervisor)
    Abstract
    Supersonic impinging jets, similar to the jet flows exhausted from a nozzle, generate high unsteady pressure and acoustic loads on the rocket payload or the VTOL aircraft structure with possible mission failure during the launch/starting phase. In the past, experimental studies were concentrated on characterizing the steady impingement flow and not the initial transient process. It was shown that one of the main characteristics of supersonic impinging jets is the dominance of the feedback loop mechanism. The present investigation is an attempt to examine the flow characteristics of a high temperature supersonic impinging jet through a convergent-divergent nozzle during the transient starting... 

    Multiobjective optimal reactive power dispatch and voltage control: A new opposition-based self-adaptive modified gravitational search algorithm

    , Article IEEE Systems Journal ; Volume 7, Issue 4 , 2013 , Pages 742-753 ; 19328184 (ISSN) Niknam, T ; Narimani, M. R ; Azizipanah Abarghooee, R ; Bahman Firouzi, B ; Sharif University of Technology
    2013
    Abstract
    This paper presents a novel opposition-based self-adaptive modified gravitational search algorithm (OSAMGSA) for optimal reactive power dispatch and voltage control in power-system operation. The problem is formulated as a mixed integer, nonlinear optimization problem, which has both continuous and discrete control variables. In order to achieve the optimal value of loss, voltage deviation, and voltage stability index, it is necessary to find the optimal value of control variables such as the tap positions of tap changing transformers, generator voltages, and compensation capacitor. Therefore, this complicated problem needs to be solved by an accurate optimization algorithm. This paper... 

    Long Lifetime Multipath Routing in Unreliable Wireless Multimedia Sensor Networks

    , M.Sc. Thesis Sharif University of Technology Nikseresht, Ilnaz (Author) ; Movaghar Rahimabadi, Ali (Supervisor) ; Mehri, Bahman (Co-Advisor)
    Abstract
    Most of the current routing protocols in the WMSNs only consider the inter-path interference and not necessarily intra-path interference factor which is considered as one of the main causes of energy consumption in these networks. Among those protocols that consider this factor, none of them has ever come up with an algorithm capable of performing the routing without the need to use either the special hardware in the nodes (referred to as the GPS or directional antennas) or with the unrealistic assumption that the interference range is equal to the transmission range. The previously mentioned factors are critical in the sense that the former assumption results in more expensive sensor nodes... 

    Influence of Tail on the Wing Pressure Distribution of a Model at Different Conditions

    , M.Sc. Thesis Sharif University of Technology Bahman Jahromi, Iman (Author) ; Soltani, Mohammad Reza (Supervisor) ; Ghorbanian, Kaveh (Supervisor)
    Abstract
    Control surfaces are used in combat aircrafts to control the pitching moment and to help the aircraft perform high angle of attack manoeuvres. For delta wing configuration, the flow characteristics around the horizontal tail depend on the wing and tail flow field and their interactions. The flow over delta wing is mainly characterised by strong vortices. These vortices move downstream and affect the tail flow field making the problem more complicated. The goal of this research is to study the effect of tail up wash on the horizontal wing-body- tail configurations in subsonic flow. For this purpose a series of wind tunnel tests were conducted on a model containing a moveable horizontal tail... 

    Phase behavior and rheology of emulsions in an alkaline/cosolvent/crude oil/brine system

    , Article Petroleum Science and Technology ; Volume 34, Issue 3 , 2016 , Pages 207-215 ; 10916466 (ISSN) Bahman Abadi, H ; Hemmati, M ; Shariat Panahi, H ; Masihi, M ; Karam Beigi, M. S ; Sharif University of Technology
    Taylor and Francis Inc  2016
    Abstract
    Phase behavior of active crude oil/alkaline was systematically studied in the presence of cosolvents. For this purpose, several factors have been considered: alkaline concentration, oil concentration, and type of brine. The best composition was used to generate emulsion for rheology and displacement tests. Furthermore, precipitation of alkaline was eliminated by its synergy with EDTA. Next, rheology of emulsion was analyzed by which a Power law model was developed that indicates non-Newtonian behavior of emulsion. Moreover, the viscosity of emulsion was reduced by the addition of cosolvent as well as by the increase of alkaline concentration. Finally, the best formulation (containing... 

    One Dimensional Extended Hubbard Model with Long Range Interactions

    , M.Sc. Thesis Sharif University of Technology Talebi, Amir Hossein (Author) ; Davoudi, Bahman (Supervisor) ; Rahimi Tabar, Mohammad Reza (Supervisor)
    Abstract
    In this thesis, we have studied the ground state properties of one-dimensional many body electron systems using the extended Hubbard model. Following the important work of Tremblay and Davoudi, we have used the TPSC approach to derive explicit expressions for spin and charge response functions. The response functions are expressed in terms of the free response function χ_0 and local field factors U_cc and U_ss. The local field factors can be written in terms of the pair correlation functions. Also fluctuation-dissipation theorem allows us to write pair correlation functions in terms of the structure factors. In the first part of thesis, we study the ground state properties of the system by...