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    Aeroelastic Analysis of Sandwich wing With Fractional Viscoelastic Core

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Hossein (Author) ; Haddadpour, Hassan (Supervisor)
    Abstract
    In this research, the effect of application of viscoelastic material with fractional derivatives pattern in aeroelastic stability analysis for a sandwich wing, has been examined. In order to study the wing’s aeroelastic behavior and the effect of inner layer on aeroelastic instability boundaries (fluttering), the wing is modeled as a cantilever sandwich beam with a fractional viscoelastic core. The Wagner approximation is used for applying the unstable aeroelastic loads. To obtain the characteristics and behaviors of the structure some assumptions including non-classical effects, are considered. These non-classical effects are the inner layer shear stress, the axial movements, the wing’s... 

    Optimal Monetary Policy with Attention to Housing Price in the Economy of Iran: DSGEApproach

    , M.Sc. Thesis Sharif University of Technology Bagherpour, Alireza (Author) ; Dargahi, Hassan (Supervisor) ; Ebrahimi, Illnaz (Supervisor)
    Abstract
    Purpose of this study is the assignment of the optimal monetary policy rule with attention to housing price with base of setting and to estimating a Dynamic Stochastic General Equilibrium modeling (DSGE). This study has two steps. In the first step we set a model with base of Households, firms, government, and monetary sector behavior and with attention to important variables like outcome, consumption, and investment, the model will be caliber and by simulation it will be evaluated. In the second step we determine optimal monetary rule and the model simulate again with this monetary rule. The comparison between two simulation for verity of shocks shows us that the optimal monetary policy... 

    Dynamic Simulation of Running Human Normal and with Below-Knee Prosthesis

    , M.Sc. Thesis Sharif University of Technology Ebrahimi Mamaghani, Ali (Author) ; Firoozbakhsh, Keykhosro (Supervisor) ; Zohoor, Hassan (Supervisor)
    Abstract
    Researches in the field of human gait have a lot of applications in medicine, ergonomics, sport science and technology. Lower limb prostheses design is one of the fields in which human gait is important. One of the best methods of gait analysis is to use analytical models. In this project, first, the normal human was simulated using a two-dimensional biped model with 7 segments, i.e., a HAT segment representing head, arms and trunk, and 6 segments representing thighs, shanks and feet of the two legs. In this model the foot-ground contact was is estimated using Taylor series after running experiment and it’s analysis which is expendable to people with different ages and different weight and... 

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Narjes Khatoon (Author) ; Samadfam, Mohammad (Supervisor) ; Mallah, Mohammad Hassan (Supervisor) ; Safdari, Jaber (Supervisor)
    Abstract
    In many uranium mines such as gachin-bandarabbas, use sulfuric acid for leaching operation on ore. This leach liquor, containing uranium, is extracted by organic solvent, such as D2EHPA (dapex process ).althogh this process have being used for many years, there is a vacancy for detailed thermodynamical studying on uranium extraction of uranium from leach liquor. To have a thermodynamical model, we need information on equilibrium concentration of all component that may have effect on uranium extraction in addition we need concentration of solvent , pH, phase ratio and activity coefficient.such a model must have the ability to predict the equilibrium concentration in alloperation condition.... 

    A ZVS-resonant bifilar drive circuit for SRM with a reduction in stress voltage of switches

    , Article International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2011 and Electromotion 2011 Joint Conference, Istanbul ; 2013 , Pages 125-128 ; 9781467350037 (ISBN) Ebrahimi, S ; Najmi, V ; Ebrahimi, S ; Oraee, H ; Sharif University of Technology
    2013
    Abstract
    Switched Reluctance Motors (SRMs) are widely used in high-speed and low voltage applications because of their attractive features such as robustness and simplicity. No winding on the rotor of this type of motors allows reaching high speed which is desired for many applications. Drive circuits of SRMs also play an important role in their performance and operation. In this paper, a new bifilar drive circuit for this type of motors has been proposed. This novel configuration has been tested and investigated by PSIM software. Results show that the new bifilar drive circuit highly reduces the voltage stresses on semiconductor switches, and also considerably reduces the switching losses which are... 

    Structural Design of a Launch Vehicle with Reusable First Stage

    , M.Sc. Thesis Sharif University of Technology Hassan Jamaklu (Author) ; Haddadpour, Hassan (Supervisor)
    Abstract
    Aerodynamics loads and aeroheating during reentry, are one of the challenging issues in designing One of the main challenges in the design and application of reusable spacecrafts is the aerodynamic and thermal loads acting on their structures during reentry into the atmosphere. For this reason, all the concepts/prototypes presented in the 20th century were either not fully reusable, or were partially canceled, or did not have economic justification. In this report, the aerodynamic loads on the first stage of a launch vehicle during the launch and return phases have been investigated. Due to the fact that the main part of the first stage of the vehicle includes fuel and oxidizer tanks, the... 

    Energy management of smart home considering residences' satisfaction and PHEV

    , Article 2018 International Conference on Smart Energy Systems and Technologies, SEST 2018, 10 September 2018 through 12 September 2018 ; 2018 ; 9781538653265 (ISBN) Ebrahimi, M ; Shokri Gazafroudi, A ; Corchado, J. M ; Ebrahimi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Regarding the increasing number of electrical devices in the smart homes that leads to increase in total electricity consumption and cost, it is essential to use energy management methods to reduce the electricity cost. However, this can cause resident's dissatisfaction. Hence, it is important to define a method in which cost and dissatisfaction be optimized simultaneously. Among different services, an electric vehicle is the one that can be used as an energy storage system, so it can reduce the daily cost despite of increasing the total energy consumption. In this paper, we study the effect of the EV on the cost and dissatisfaction in our proposed method. © 2018 IEEE  

    Measured impact of different back-off points and cooling methods on pulse-to-pulse stability and sidelobe level of a high-power solid-state amplifier

    , Article IET Radar, Sonar and Navigation ; Volume 14, Issue 2 , 2020 , Pages 335-340 Ebrahimi, A ; Khodarahmi, E ; Ebrahimi, E ; Ahmadi, B ; Jalali, M ; Sharif University of Technology
    Institution of Engineering and Technology  2020
    Abstract
    Using solid-state power amplifiers for next generation of weather radars becomes feasible by pulse compression techniques. In this study a 1.5 kW solid-state power amplifier (transmitter) for C-band weather radars is designed and fabricated by GaN high electron mobility transistor (HEMT) technology. An experimental setup based on heterodyne receiver with 16-bit digitiser is developed to investigate the behavior of the power amplifier under different cooling methods and back-off points. Several measurements with shaped LFM pulse show an approximately identical pulse to pulse (P2P) stability for 3 dB compression, P1dB and 2 dB back-off points while the best sidelobe level (SLL) is achieved for... 

    Probabilistic safety assessment of a UF 6 production process

    , Article Advances in Safety, Reliability and Risk Management - Proceedings of the European Safety and Reliability Conference, ESREL 2011 ; 2012 , Pages 1384-1389 ; 9780415683791 (ISBN) Ebrahimi, B ; Sharif University of Technology
    2012
    Abstract
    Application of Probabilistic Safety Assessment (PSA) to a Uranium hexafluoride (UF 6) production process is presented in this paper. The process is constituted from three main units: UF 4 conversion to UF 6, condensation of produced UF 6 gas and tail gas treatment. Radioactive gas is present in all parts of the process and occurrence of high pressure or high temperature in the process equipments may lead to radioactive release to workplace and environment. The work is mainly based on PSA experience in nuclear power plants. Accordingly for the process, eight group of Initiating Events (IE) that lead to UF 6 gas release have been identified using HAZOP study. For each IE, based on related... 

    On the temperature control in self-controlling hyperthermia therapy

    , Article Journal of Magnetism and Magnetic Materials ; Volume 416 , 2016 , Pages 134-140 ; 03048853 (ISSN) Ebrahimi, M ; Sharif University of Technology
    Elsevier  2016
    Abstract
    In self-controlling hyperthermia therapy, once the desired temperature is reached, the heat generation ceases and overheating is prevented. In order to design a system that generates sufficient heat without thermal ablation of surrounding healthy tissue, a good understanding of temperature distribution and its change with time is imperative. This study is conducted to extend our understanding about the heat generation and transfer, temperature distribution and temperature rise pattern in the tumor and surrounding tissue during self-controlling magnetic hyperthermia. A model consisting of two concentric spheres that represents the tumor and its surrounding tissue is considered and temperature... 

    Atmospheric icing effects of S816 airfoil on a 600 kW wind turbine's performance

    , Article Scientia Iranica ; Volume 25, Issue 5B , 2018 , Pages 2693-2705 ; 10263098 (ISSN) Ebrahimi, A ; Sharif University of Technology
    Sharif University of Technology  2018
    Abstract
    This study investigates the aerodynamic loads and energy losses of a typical 600 kW wind turbine with S816 airfoil blade under two different icing conditions. Three sections at different radial positions were considered to estimate the icing effect along the blade. Ice accretion simulations in wet and dry regimes were carried out using the NASA LEWICE 3.2 computer program. The airflow simulations were performed with CFD method and SST k -ω turbulence model. The results of these simulations, including streamlines, surface pressure, skin friction, lift, and drag coefficients, were inspected for both clean and iced airfoils. In the case of wet iced airfoil, a separation bubble was created in... 

    Investigation on the Effects of the Polyacrylamide Copolymers and Their Blends with Sulfonated Lignin on the Soil Stabilization

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Shohre (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor) ; Ebrahimi, Hossein (Co-Supervisor)
    Abstract
    In recent years, dust pollution has become a worldwide issue due to the creation of serious environmental problems and the effects it has on human health. In this research, an environmentally friendly soil stabilizer has been synthesized, and its performance has been investigated. Acrylamide monomers were grafted onto sodium lignosulfonate chains, utilizing solution polymerization. The soil of the Ahvaz deserts was used in the analyses. Using EDX and DLS analyses, the components of this soil and the particle size distribution of the used soil were obtained. Characterization of the functional groups and the structure of the graft copolymer were done by FTIR and H-NMR analysis, respectively,... 

    Optimal Trajectory Correction for Hazardous Near-Earth Asteroids

    , M.Sc. Thesis Sharif University of Technology Farsi, Salman (Author) ; Zohoor, Hassan (Supervisor) ; Sayyadi, Hassan (Supervisor)
    Abstract
    The collision of moderately large asteroids and comets also referred to as Near-Earth Objects (NEO's) with earth would have catastrophic consequences. Such events have occurred in the past and may occur again in the future. However, for the first time in known history, humanity may have the technology required to counter this threat. Methods studied for mitigation of this hazard are based on deflecting asteroid's trajectory and are normally divided into two basic categories: high energy impulsive methods, and long-duration low-thrust methods. Two parts of mission to be optimized are the trajectory of spacecraft to reach the target and the deflection strategy which could be analyzed by the... 

    A revised version of ACO for cutting stock problem [electronic resource]

    , Article International Journal of Industrial Engineering ; Vol 15, No 4 (2008), Pages 341-348 Eshghi, K. (Kourosh) ; Javanshir, Hassan ; Sharif University of Technology
    Abstract
    The one-dimensional cutting stock problem has many applications in industries and during the past few years has been one of the centers of attention among the researchers in the field of applied operations research. In this paper, a revised version of Ant Colony Optimization (ACO) technique is presented to solve this problem. This paper is a sequel to the previous ACO algorithm presented by the authors. In this algorithm, according to some probabilistic rules, artificial ants will select cutting patterns and generate a feasible solution. Computational results show the high efficiency and accuracy of the proposed algorithm for solving one- dimensional cutting stock problem  

    Control of Car-Like Multi Robots for Following and Hunting of Moving Target

    , M.Sc. Thesis Sharif University of Technology Kouhi Gilvan, Hamed (Author) ; Sayyaadi, Hassan (Supervisor) ; Salarieh, Hassan (Co-Advisor)
    Abstract
    The main purpose of the present thesis is to establish a decentralized controller for some car–like multi robots to follow and hunt moving targets. Robots are very similar to actual cars considering geometric dimensions, mass and moment of inertia and so on; and outputs of the controller are steering-wheel and driving-wheel torques appropriately. Dynamics of the moving target is so that it escapes from the robots. Robots are equipped with antenna for getting wireless sensory signals, including range and bearing sensors. Kalman filter is used for estimation the target relative position and speed and robots state variables. The controller is designed for doing the above mentioned group... 

    Dunford-Taylor integral and the isotropic tensor valued functions having the commutative property with their tensor argument

    , Article Advanced Materials Research, 16 September 2011 through 18 September 2011 ; Volume 433-440 , September , 2012 , Pages 3308-3314 ; 10226680 (ISSN) ; 9783037853191 (ISBN) Ebrahimi, M ; Asghari, M ; Sharif University of Technology
    2012
    Abstract
    Isotropic tensor valued functions of tensor arguments play an important role in the formulation of the equations governing the behavior of solid materials in the field of continuum mechanics. When the tensor argument is non-symmetric, the complexity and the difficulty in dealing with the tensor functions are high. In this work, the issue of expressing an isotropic tensor valued tensor function of a non-symmetric tensor argument is attention by utilizing the Dunford-Taylor integral. An important subclass of the isotropic tensor functions is considered with the commutative property  

    Formaldehyde biodegradation using an immobilized bed aerobic bioreactor with pumice stone as a support

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1372-1376 ; 10263098 (ISSN) Ebrahimi, S ; Borghei, M ; Sharif University of Technology
    2011
    Abstract
    The objective of this study is the investigation of formaldehyde degradation in a bioreactor with pumice stone as a support. The reactor was tested at different synthetic wastewater concentrations with total COD of 500, 1000 and 1500 mgL, respectively, at 24 h hydraulic retention time. The effect of feed composition was tested by changing the COD TCOD FA ratio in order to analyze the impact of formaldehyde concentration. The average formaldehyde and COD removal efficiencies obtained in the reactor were 97.1% and 88%, respectively. The maximum COD and formaldehyde removal efficiencies occurred at the COD TCOD F of 41 at COD T=1000mgL. The effect of toxic shock on reactor performance was... 

    Port-Hamiltonian control of a brachiating robot via generalized canonical transformations

    , Article 2016 American Control Conference, ACC 2016, 6 July 2016 through 8 July 2016 ; Volume 2016-July , 2016 , Pages 3026-3031 ; 07431619 (ISSN); 9781467386821 (ISBN) Ebrahimi, K ; Namvar, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    This paper is devoted to the design of a port Hamiltonian controller for different scenarios of brachiation movement by a two-link bio-inspired robot called brachiating robot. A unified technique for trajectory tracking control problem of nonholonomic (drift-less) port Hamiltonian systems was introduced in the past, which exploits a generalized canonical transformation to form an error system in order to convert the trajectory tracking problem into a stabilization one. Although the method is novel and promising, only fully actuated systems are considered and success of the approach relies on the possibility of solving a set of partial differential equations (PDEs). Considering the fact that... 

    Numerical investigation of the forward and backward travelling waves through an undulating propulsor: performance and wake pattern

    , Article Ships and Offshore Structures ; Volume 11, Issue 5 , 2016 , Pages 517-539 ; 17445302 (ISSN) Ebrahimi, M ; Abbaspour, M ; Sharif University of Technology
    Taylor and Francis Ltd  2016
    Abstract
    Recently, the mechanisms of natural undulatory locomotion of aquatic animal swimming have become one of the most significant issues for the researchers, swimmers and engineers. This study aims to elucidate and compare the propulsive vortical signature and performance of backward (negative undulation) and forward (positive undulation) travelling waves through a typical fishlike propulsor by a systematic numerical study. The numerical approach uses a pressure-based finite volume method solver to solve Navier–Stokes equations in an arbitrary Lagrangian–Eulerian framework domain containing a two-dimensional NACA 0012 foil moving with prescribed kinematics. Some of the important findings are: (1)... 

    A comparative numerical study on the performances and vortical patterns of two bioinspired oscillatory mechanisms: Undulating and pure heaving

    , Article Applied Bionics and Biomechanics ; Volume 2015 , 2015 ; 11762322 (ISSN) Ebrahimi, M ; Abbaspour, M ; Sharif University of Technology
    IOS Press  2015
    Abstract
    The hydrodynamics and energetics of bioinspired oscillating mechanisms have received significant attentions by engineers and biologists to develop the underwater and air vehicles. Undulating and pure heaving (or plunging) motions are two significant mechanisms which are utilized in nature to provide propulsive, maneuvering, and stabilization forces.This study aims to elucidate and compare the propulsive vortical signature and performance of these two important natural mechanisms through a systematic numerical study. Navier-Stokes equations are solved, by a pressure-based finite volume method solver, in an arbitrary Lagrangian- Eulerian (ALE) framework domain containing a 2D NACA0012 foil...