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    Evaluate the Effectiveness of Knowledge Components in The Sectoral Innovation System: Study Leading and Late Comer Countries in Renewable Energy

    , M.Sc. Thesis Sharif University of Technology Mardukh Rouhani, Farzaneh (Author) ; Miremadi, Iman (Supervisor)
    Abstract
    Climate change and its Environmental issues become fundamental challenges in recent years, and countries have to try find various solutions about it, such as developing renewable energy technologies. Multiple studies have been conducted on the importance of innovation in technology development and technological changes in different countries. Many studies have addressed the concept of the innovation system and evaluated the role of various institutions and actors. The innovation system as one of the concepts branched from the innovation system focuses on the importance of interactions between actors, the role, and nature of knowledge in a particular industry or sector. Hence, investigating... 

    Rapid growth of hydroxyapatite nanoparticles using ultrasonic irradiation

    , Article Ultrasonics Sonochemistry ; Volume 17, Issue 5 , Jun , 2010 , Pages 853-856 ; 13504177 (ISSN) Rouhani, P ; Taghavinia, N ; Rouhani, S ; Sharif University of Technology
    2010
    Abstract
    A rapid, environmental friendly and low-cost method to prepare hydroxyapatite nanoparticles is proposed. In this method, hydroxyapatite is produced in a sonicated pseudo-body solution. The sonication time was found effective in the formation of the crystalline phase of nanoparticles. In our experimental condition, 15 min sonication resulted in the most pure hydroxyapatite phase. Also it was shown that growth temperature is a crucial factor and hydroxyapatite crystallizes only at 37 °C. The particles formed by sonication were generally smaller and more spherical than those obtained without sonication. Sonication increased the hydroxyapatite crystal growth rate up to 5.5 times compared to... 

    The Universality Classes of the KPZ Equation

    , M.Sc. Thesis Sharif University of Technology Balouchi, Ashkan (Author) ; Rouhani, Shahin (Supervisor)
    Abstract
    Kardar-Parisi-Zhang (KPZ) equation was first proposed as a model to explain surface growth. This equation is very similar to Edwards-Wilkinson (EW) equation that is used to study scaling phenomena in non-equilibrium systems and phase transition. Although EW’s universality classes have been known well, it still remains a problem for KPZ. In the present thesis, in addition to a general review on surface growth models and a study on properties of rough surfaces, we study the physics of the KPZ model and the other related physical models. Also, using numerical results (like SLE method), renormalization group results and simulation, we study the dynamic and roughness exponents (α, z), and the... 

    AdS3/CFT2 In The Presence of N=1 Supergravity

    , M.Sc. Thesis Sharif University of Technology Fattahi, Mohammad (Author) ; Rouhani, Shahin (Supervisor)
    Abstract
    Brown and Henneaux showed that asymptotic symmetries of asymptotically form a conformal group in two dimensions [1]. Also they could derive classical central charge of theory. Fourteen years later, Maldacena, conjectured that this Holographic correspondence could be true for a specific theory a simplified chromodynamics in the boundary of ), this holographic theory attracted physicist communitee's attention. Many physicists tried to make this conjecture more precise. It is worth to say that, no example of holographic correspondence has been completely proven, till now, Because of the difficulty of the calculation. However these days we consider Madacena conjectrure in any arbitrary... 

    Analysis of Off-Critical Percolation Clusters by Schramm-Loewner Evolution

    , M.Sc. Thesis Sharif University of Technology Jamali, Tayyeb (Author) ; Rouhani, Shahin (Supervisor)
    Abstract
    Recently, a new tool in the study of two-dimensional continuous phase transition was provided by Schramm-Loewner evolution. The main part of SLE is a conformal map which relates growth process of a two-dimensional simple curve to one-dimensional motion on the real axis (so-called Loewner driving function). Time evolution of this map and Loewner driving function is connected via the Loewner differential equation. It turns out that for a certain class of stochastic and conformally invariant curves in two dimensions, the driving function shows Brownian motion in one dimension. Strength point of SLE comes from this fact that all the geometrical properties of such curves is described through a... 

    The Watershed Model and Schramm-loewner Evolution

    , Ph.D. Dissertation Sharif University of Technology Daryaei, Ebrahim (Author) ; Rouhani, Shahin (Supervisor)
    Abstract
    Schramm Loewner evolution (SLE) is a one-parameter family of random simple curves in the complex plane introduced by Schramm in 1999 which is believed to describe the scaling limit of a variety of domain interfaces at criticality. This thesis is concerned with statistical properties of watersheds dividing drainage basins. The fractal dimension of this model is 1.22 which is consistent with the known fractal dimension for several important models such as Invasion percolation and minimum spanning trees (MST). We present numerical evidences that in the scaling limit this model are SLE curves with =1.73, being the only known physical example of an
    SLE with <2. This lies outside the... 

    Variance of the Topological Charge as an Order Parameter for the KT Model

    , M.Sc. Thesis Sharif University of Technology Norouzi, Hossein (Author) ; Rouhani, Shahin (Supervisor)
    Abstract
    XY Model due to topological defects (or vortex) has topological phase transition. According Kosterlitz-Thouless (KT) theory, phase transition is from low-temperature bounded vortices to high-temperature free vortices. XY model is appropriate choice for description of superfluidity in 2d thin films of . KT theory predicts universal jump in mass density of 2d superfluid in phase transition point. It is confirmed experimentally by Bishop and Reppy. All critical behavior of XY model is described with 2d coulomb gas, vortices are topological charges of the gas. KT predict variance of topological charge should obey of the “surface law vs perimeter law”, similar to behavior of Wilson loop in ... 

    Generalization of Greenwood- Williamson Model by Extreme value Statistics

    , Ph.D. Dissertation Sharif University of Technology Malekan, Azadeh (Author) ; Rouhani, Shahin (Supervisor)
    Abstract
    We propose a model for friction between two rough surfaces based on extreme value statistics (EVS). Different models for single-asperity contact, including adhesive and elasto-plastic contacts, were combined with EVS. The Hertzian model for contacts and Gumbel distribution for summit heights show the closest conformity with Amonton’s law. The range over which Gumbel distribution mimics Amonton’s law is wider than that of the Greenwood–Williamson (GW) model. In comparison with other EVS distribution, Gumbel distribution seems the proper choice for summit‘ s height. Interestingly, here again, elasto-plastic contact and Gumbel distribution for summits achieve the best conformity with Amontons... 

    Detecting and evaluating detrimental factors of clay's longevity, selecting, and optimizing an appropriate adsorbent for operating time elevation in the separation process of trace olefins from aromatics

    , Article Industrial and Engineering Chemistry Research ; Volume 59, Issue 7 , 2020 , Pages 2796-2804 Rouhani, H ; Farhadi, F ; Sharif University of Technology
    American Chemical Society  2020
    Abstract
    Industrial-scale production of aromatic materials is confronted by the problem of removal of impurities such as olefins. Their removal is an essential requirement in marketability. Catalytic adsorbent clay is the most common material used for the removal of olefins from aromatic streams. The current study is focused on increasing the lifetime of a commercial type of clay by identifying the effective parameters in reducing the adsorbent lifetime. An analysis of 3 years of data from a petrochemical complex showed that water, morpholine, and N-formyl morpholine (NFM) contents in the feed stream are the factors reducing the clay lifetime. Various experiments have been performed to determine the... 

    Estimating the Interaction Between Sites of a System by Convolutional Neural Networks and Applying Renormalization Group Methods on the Network’s Density Matrix

    , M.Sc. Thesis Sharif University of Technology Pourmohammad, Hamid (Author) ; Rouhani, Shahin (Supervisor)
    Abstract
    In the last two decades, Convolutional Neural Networks (CNN) have shown significant capabilities in artificial intelligence. These networks are able to provide comprehensive conclusions about the overall behavior a system by analyzing the relationship between the components of that system; Clearly, these networks have been successful in performing categorization tasks. However, there are no coherent theories as to why they work, and how to optimize them. On the other hand, according to recent research on the relationship between deep networks (in computer science) and Renormalization Group (in physics), convolutional networks seem to use a method similar to the Density Matrix Renormalization... 

    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... 

    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... 

    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 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... 

    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... 

    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... 

    Array Geometry Based Beamforming in Smart Antennas Intended for Capacity Improvment in Wireless Systems

    , Ph.D. Dissertation Sharif University of Technology Poormohammad, Sarah (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    Novel two dimensional and three dimensional antenna array geometries for smart antenna application are introduced. MMSE beamforming algorithm, using these arrays, in presence of signal, noise and interferences is implemented. Beamforming approach is used for every type of array assuming uniform and log-normal distributions for the interference amplitudes. Equal volume cylindrical or prism type arrays with circular, hexagonal, triangular, square and star cross sections with equal number of elements are considered for comparison. Novel geometries consisting of rotated cross sections are studied as well. In each case the relative SIR’s are compared in these geometries, showing that the... 

    Reliable and Uninterrupted Telecommunication link between Earth and Mars

    , M.Sc. Thesis Sharif University of Technology Ahmadi, Jamil (Author) ; Farzaneh, Frohar (Supervisor)
    Abstract
    For a manned space mission to Mars, one of the essential requirements is to have a two-way, uninterrupted communication link.Three Mars Synchronous Satellites (MSS), are proposed to ensure the telecommunication link in all locations on Mars (except its poles) at any time. At any given moment, at least two of the three satellites (MSS) is connected to the Deep Space Communication Complex (DSCC) (NASA Earth Station). But the use of MSS satellites is not adequate during the periods of solar conjunction and solar opposition. Due to the fact that the sun blocks or weakens the receiver signal, a solar orbiting satellite (SOS) is proposed to maintain the communication link at this condition....