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    Investigation of Electro-Optical Properties of Heterostructures based on 2-D Layered Materials by Quantum Simulation

    , M.Sc. Thesis Sharif University of Technology Saadat Somaeh Sofla, Zahra (Author) ; Simchi, Abdolreza (Supervisor) ; Shayeganfar, Farzaneh (Supervisor)
    Abstract
    Density Functional Theory is one of the most robust Ab-intio methods for describing the structural and electronic properties of a wide range of materials. The ability to predict the material properties changes due to targeted material manipulation at the atomic scale has reduced the cost of many empirical experiments. It has improved the knowledge and understanding of the investigation and producing new materials and devices. Tow dimensional heterostructures are highly regarded due to their unique optoelectronic properties, potential application in nanoelectronic devices, energy storage devices, solid-state devices, and photovoltaic devices. In this study, the two-dimensional materials... 

    Levels of complexity in turbulent time series for weakly and high Reynolds number

    , Article Physica A: Statistical Mechanics and its Applications ; Volume 391, Issue 11 , 2012 , Pages 3151-3158 ; 03784371 (ISSN) Shayeganfar, F ; Sharif University of Technology
    2012
    Abstract
    We use the detrended fluctuation analysis (DFA), the detrended cross correlation analysis (DCCA) and the magnitude and sign decomposition analysis to study the fluctuations in the turbulent time series and to probe long-term nonlinear levels of complexity in weakly and high turbulent flow. The DFA analysis indicate that there is a time scaling region in the fluctuation function, segregating regimes with different scaling exponents. We discuss that this time scaling region is related to inertial range in turbulent flows. The DCCA exponent implies the presence of power-law cross correlations. In addition, we conclude its multifractality for high Reynold's number in inertial range. Further, we... 

    Methane molecule over the defected and rippled graphene sheet

    , Article Solid State Communications ; Volume 152, Issue 15 , August , 2012 , Pages 1493-1496 ; 00381098 (ISSN) Shayeganfar, F ; Neek Amal, M ; Sharif University of Technology
    Elsevier  2012
    Abstract
    Adsorption of a methane molecule (CH 4) onto a defected and rippled graphene sheet is studied using ab initio and molecular mechanics calculations. The optimal adsorption position and orientation of this molecule on the graphene surface (motivated by the recent realization of graphene sensors to detect individual gas molecules) is determined and the adsorption energies are calculated. In light of the density of states, we used the SIESTA code. It is found that (i) classical force field yields adsorption energy comparable with experimental result and ab initio calculation; (ii) the periodic nature of the van der Waals potential energy stored between methane and perfect sheet is altered due to... 

    Discrimination of Sol and Gel states in an aging clay suspension

    , Article Chemical Physics ; Volume 423 , September , 2013 , Pages 167-172 ; 03010104 (ISSN) Shayeganfar, F ; Movahed, M. S ; Jafari, G. R ; Sharif University of Technology
    2013
    Abstract
    The dynamical scattered light intensity and multiplicative cascade model was employed to characterize the anisotropic charged colloidal particles suspension during the so-called Sol-Gel transition. Generally we looked for finding a criterion to distinguish the properties of Sol and Gel states systematically. The probability density function (PDF) of the light scattering intensity shows an obvious change with proceeding of the sample aging process (during of gelation state). Our results confirmed that in the so-called Sol state, the value of non-Gaussian parameter, kW, as a function of time is larger than that of for weak-Gel or in coexistence Sol-Gel state. The number of cascades in the... 

    Molecular dynamics simulation of formation and growth of CdS nanoparticles

    , Article Molecular Simulation ; Vol. 40, issue. 5 , Jul , 2014 , p. 361-369 ; ISSN: 08927022 Shayeganfar, F ; Eskandari, Z ; Rahimi Tabar, M. R ; Sahimi, M ; Sharif University of Technology
    2014
    Abstract
    Monodispersed semiconducting nanoparticles are usually synthesised in a liquid medium using injection of an appropriate solution. A key factor in attaining a narrow particle size distribution (PSD) is the temporal separation of the nucleation and growth stages, where the former takes place during the injection. Faster injection produces a larger number of nuclei and a narrower PSD. The injection speed is expected to affect the diffusion of the ions in the solution and to create uniformly high supersaturation for a short period of time. In this paper, we study the growth of CdS nanoparticles during the injection by molecular dynamics simulation. A solution of Cd ions is injected into the... 

    The level crossing and inverse statistic analysis of German stock market index (DAX) and daily oil price time series

    , Article Physica A: Statistical Mechanics and its Applications ; Volume 391, Issue 1-2 , 2012 , Pages 209-216 ; 03784371 (ISSN) Shayeganfar, F ; Hölling, M ; Peinke, J ; Rahimi Tabar, M. Reza ; Sharif University of Technology
    2012
    Abstract
    The level crossing and inverse statistics analysis of DAX and oil price time series are given. We determine the average frequency of positive-slope crossings, να+, where Tα=1να+ is the average waiting time for observing the level α again. We estimate the probability P(K,α), which provides us the probability of observing K times of the level α with positive slope, in time scale Tα. For analyzed time series, we found that maximum K is about ≈6. We show that by using the level crossing analysis one can estimate how the DAX and oil time series will develop. We carry out the same analysis for the increments of DAX and oil price log-returns (which is known as inverse statistics), and provide the... 

    Effects of functionalization and side defects on single-photon emission in boron nitride quantum dots

    , Article Physical Review B ; Volume 96, Issue 16 , 2017 ; 24699950 (ISSN) Shayeganfar, F ; Rahimi Tabar, M. R ; Simchi, A ; Beheshtian, J ; Sharif University of Technology
    2017
    Abstract
    Boron nitride quantum dots (BNQDs) functionalized with chemical ligands exhibit intriguing optoelectronic properties due to the quantum confinement effect. This paper presents peculiar insights on the effect of side defects on the electronic structure and optical properties of BNQDs functionalized with different chemical bonds including hydrogen (H), nitrogen (N), hydroxyl (OH), amine (NH2), and thiol groups (inspired by experimental reports of functionalized BN nanosheets and nanotubes) Weng, Chem. Soc. Rev. 45, 3989 (2016)0306-001210.1039/C5CS00869G. Hybrid density functional simulations and Green's function calculations indicate an intriguing coexistence of two different Peierls-like... 

    Evaluation of the optimal performance of passenger vehicle by integrated energy-environment-economic modeling

    , Article International Journal of Environmental Science and Technology ; Volume 4, Issue 2 , 2007 , Pages 189-196 ; 17351472 (ISSN) Farzaneh, H ; Saboohi, Y ; Sharif University of Technology
    CEERS  2007
    Abstract
    Analysis of multi dimensional interactions of flow of energy in passenger vehicle is a complex task that necessitates development and utilization of analytical tools. Development of analytical tools with high complexity is usually based on conclusions of many concepts and theories from different scientific disciplines. In this approach, Passenger vehicle is supposed to be organized in the form of a firm and appears in the market that oriented towards establishing an effective energy supply system which may be identified as delivering the product (person kilometer or tone kilometer) with minimum operation costs. To this end, an optimization model named power software founded on theory of firm... 

    Model for analysis of energy flow from tank-to-wheel in a passenger vehicle

    , Article 2005 IEEE Vehicle Power and Propulsion Conference, VPPC, Chicago, IL, 7 September 2005 through 9 September 2005 ; Volume 2005 , 2005 , Pages 150-153 ; 0780392809 (ISBN); 9780780392809 (ISBN) Farzaneh, H ; Saboohi, Y ; Sharif University of Technology
    2005
    Abstract
    Analysis of multi dimensional interactions of flow of energy in passenger vehicle is a complex task that necessitates development and utilization of analytical tools. Development of analytical tools with high complexity is usually based on conclusions of many concepts and theories from different scientific disciplines. In this approach, Passenger vehicle is supposed to be organized in the form of a firm and appears in the market that oriented towards establishing an effective energy supply system which may be identified as delivering the product (person per mileage removable) with minimum operation costs. To this end, an optimization model named POWER software founded on theory of firm of... 

    Software of passenger vehicle optimal work and energy recovery (POWER)

    , Article 12th International Conference on Urban Transport and the Environment in the 21st Century, URBAN TRANSPORT 2006, UT06, Prague, 12 July 2006 through 14 July 2006 ; Volume 89 , 2006 , Pages 691-699 ; 17433509 (ISSN); 1845641795 (ISBN); 9781845641795 (ISBN) Farzaneh, H ; Saboohi, Y ; Sharif University of Technology
    2006
    Abstract
    In our investigation, the model of optimal energy flow in a passenger vehicle has been founded on the theory of firm microeconomics. Based on this theory, the car owner tries to minimize the total cost of the system (including the cost of time of the traveller) subject to the satisfaction of the required transport services and technological, economical, environmental and institutional constraints. The aforementioned model has been developed using a technique of mathematical programming. The model depicts the behaviour of a nonlinear system and it includes many nonlinear functions in the objective function and in the constraints. Solving the large nonlinear set of constraints and identifying... 

    Radiowave Propagation Modeling Along a Street for Use in Microcells in Third Generation Wireless Communications

    , M.Sc. Thesis Sharif University of Technology Sadeghi, Hamed (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    In this thesis, a simplified method was introduced to model the wave scattering by the metallic objects in a microcell, in order to determine the coverage pattern. First, the equivalent images method was introduced, which models the building walls effect. This method is fast, memory saving and accurate enough to estimate the scattered fields. Two-ray incidence model accuracy was investigated and confirmed in modeling the scattering from the metallic objects. This method also enhances saving in time and memory. The accuracy of single scattering assumption was investigated and confirmed in a scenario of multiple metallic scatterers. Based on this assumption, we can superimpose the scattered... 

    Design and Simulation of Smart Patch Antenna Array in 2.4 GHz band

    , M.Sc. Thesis Sharif University of Technology Hosseini, Mahdi (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    Over the past few years , demand for wireless communication services have grown at a formidable rate. As such we need to find new ways to support more and more wireless users in a confined space. this means that the capacity of networks should be significantly increased to overcome formidable rate of subscribers growth. That is why the smart antennas have become very popular in communication systems. Smart antennas are a kind of adaptive antenna arrays with smart signal processing algorithms used to find direction of arrival(DOA) of the signal, and use it to calculate suitable weights to direct the antenna beam on the desired user and nulling interferences. In this thesis, DOA estimation... 

    Evaluation of Phase Comparison DOA Estimation Methods in Multipath Environments for Millimeter Waves

    , M.Sc. Thesis Sharif University of Technology Karimi, Parisa (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    The main objective of this project is to discuss a DOA estimation system performance in a multipath environment. For this goal, first the basics of the DOA Estimation systems are discussed. Evaluation of different types of algorithms and choosing an appropriate one is an important step in this regard. Moreover the comparison of different array structures is necessary to choose the appropriate one. The major part of the project has been dedicated to discussion of multipath phenomenon as a major source of error in DOA estimation and studying the multipath mitigation algorithms to eliminate the aforementioned error. A model based on the concept of Bistatic Radar Cross Section is proposed to... 

    Evaluation and Improvement of DOA Estimation Methods in Dipole Antenna Arrays with Different Geometries

    , M.Sc. Thesis Sharif University of Technology Sasannia, Zahra (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    In this thesis, some of the well-known DOA algorithms namely Bartlett, Capon, Linear prediction, Maximum Entropy, Pisarenko harmonic decomposition, Minimum norm and MUSIC are analyzed and compared with each other in the identical situations using a uniform linear array. Then based on these comparisons, the appropriate algorithm is selected. In the next step since the linear arrays can't estimate both angles of arrival (Azimuth and Elevation) simultaneously, two dimensional (2D) geometries are introduced and are also compared to each other. Then one of them (circular array) is selected for dipole antenna arrays. The performance of the selected array is evaluated using isotropic elements for... 

    Analysis and Simulation of Mars Rover Curiosity in the X and UHF Bands

    , M.Sc. Thesis Sharif University of Technology Torabi, Masoud (Author) ; Forouhar, Farzaneh (Supervisor)
    Abstract
    Mars rover Curiosity is a mobile scientific laboratory which it’s mission is to assess the biological potential of the landing site and characterize the geology of the landing region. This rover communicate to a Mars orbiter named MRO satellite in the UHF band which relies the signals to the Earth stations. Also this rover communicate to the Earth stations directly in the X band. In this thesis, we determine the technical characteristics of stations and simulate Earth-Mars radio links. So we calculate :
    1. determine the technical characteristics of Earth stations
    2. determine the technical characteristics of satellite and Curiosity
    3. Earth-Mars orbital position in the... 

    , M.Sc. Thesis Sharif University of Technology Razieh, Azad (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    In recent years due to the advances in semiconductor technology and the ability to implement small-scale manufacturing, communication at 60 GHz band receive more attention than ever has been. The use of this frequency band is not only about 7-9 GHz unlicensed broadband access provided, but getting smaller devices make it possible to use multiple antennas at the transmitter and receiver, and thus taking advantage of multiple input – multiple output systems. Antennas used in these systems should have features such as small size , low weight, high gain and bandwidth and also they should keep their high efficiency and gainat high frequency range (about a few GHz ). To achieve these features... 

    Switched Parasitic Antennas for the use in Wireless Communications

    , M.Sc. Thesis Sharif University of Technology Ahmady, Hesam (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    Switched Parasitic Antennas, as a kind of Smart Antennas, have several applications in Telecommunications and Radar systems. In the realm of wireless applications, these antennas provide the system with higher capacity owning to the fact that they are able to direct the main beam toward the desirable user. Moreover, they can be used to degrade the adverse effects of Multi-path. Multi-path reduction not only benefits mobile communication but applies to many applications of radar systems. These antennas, in addition, can be utilized in Direction Finding. In the case of other types of Smart Antennas, the above mentioned benefits can be achieved with high costs due to the fact that there are a... 

    Wideband Microwave Radio Direction Finding Based on Phase Interferometry Method for Two and Three Dimensional Arrays with Minimum Number of Antennas

    , Ph.D. Dissertation Sharif University of Technology Mollai, Sajjad (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    The interferometer method, as one of the most accurate schemes for wideband direction finding (DF), is used. The interferometer method has various algorithms which can be implemented depending on the required specifications. The advantages and disadvantages of these algorithms have been evaluated and the appropriate algorithm for a general practical case in view of the ambiguity resolution is proposed. The receivers’ channel phase tracking error is of significant concern in practice, in interferometric DF systems. The induced error due to channels phase tracking error is estimated. Furthermore the use of physically realizable antennas, achievement of high accuracy, minimum number of antennas... 

    Design and Simulation of mmWave Antenna Arrays with Novel 3D Geometries for 5G Wireless Applications

    , M.Sc. Thesis Sharif University of Technology Ahmadi, Nima (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    In the new generations of mobile communication systems, smart antennas are used to achieve higher capacities. Since these systems have the ability to form a radiation pattern where the desired signal is received with minimum distortion and inteferers are received with a significant attenuation therefore their application makes it possible to have a large signal to inteference ratio. In addition by setting the main beam direction towards the desired signal, it is conceivable to realize the the communication with a lower power. The optimal methods for angle-of-arrival estimation and beamforming in one and two dimensional structures has been studied in the literature, but the three dimensional... 

    Analysis and Design of a Multiple-Input Multiple-output (MIMO) Transmitter in the 60 GHz Band with a Beam Steering Capability Using All-digital Phase-locked Loop Chip

    , Ph.D. Dissertation Sharif University of Technology Salarpour, Mahdi (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    Multiple-Input Multiple-Output (MIMO) communications at millimeter-wave (mm-wave) frequencies (e.g., in the 60 GHz band) is a modern technology recently considered for various applications, such as emerging 5G services for multi-user MIMO (MU-MIMO) and high-resolution frequency-modulated continuous wave (FMCW) MIMO radars to support multi-gigabit throughputs in short-range environments via spatial multiplexing-diversity. Nevertheless, the impairments of communication channels in this frequency band, including significant propagation loss and severe blockage effect, are quite challenging to allow an efficient communication link. Hence, beamforming/beam steering can play a crucial role in 60...