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    Numerical investigation of distance effect between two searasers for hydrodynamic performance

    , Article Alexandria Engineering Journal ; Volume 55, Issue 3 , 2016 , Pages 2257-2268 ; 11100168 (ISSN) Babajani, A. A ; Jafari, M ; Hafezi Sefat, P ; Sharif University of Technology
    Elsevier B.V  2016
    Abstract
    Nowadays, researchers are interested in investigation of the ocean wave energy conversion (OWEC) because this device can convert wave energy into electricity economically. The aim of this study was to evaluate a novel ocean wave energy converter named Searaser which may be capable of being used in the Caspian Sea. One of the ways for improving the efficiency of Searasers is to use numerous Searasers simultaneously. Increasing the number of Searasers not only increases the electricity production but also can help producing more stable electricity. In this article the function of two Searasers three different distances (10, 15 and 20 m) was evaluated numerically by solving momentum and... 

    Laboratory investigations on impulsive waves caused by underwater landslide

    , Article Coastal Engineering ; Volume 55, Issue 12 , December , 2008 , Pages 989-1004 ; 03783839 (ISSN) Ataie Ashtiani, B ; Najafi Jilani, A ; Sharif University of Technology
    2008
    Abstract
    Laboratory investigations have been performed on the submarine landslide generated waves by performing 120 laboratory tests. Both rigid and deforming-slide masses are considered. The effects of bed slope angle, initial submergence, slide geometry, shape and deformation on impulse wave characteristics have been inspected. Impulse wave amplitude, period, energy and nonlinearity are studied in this work. The effects of bed slope angle on energy conversion from slide into wave are also investigated. Laboratory-based prediction equations are presented for impulse wave amplitude and period in near and far-field and are successfully verified using the available data in previous laboratory and... 

    Impulsive waves caused by subaerial landslides

    , Article Environmental Fluid Mechanics ; Volume 8, Issue 3 , 2008 , Pages 263-280 ; 15677419 (ISSN) Ataie Ashtiani, B ; Nik Khah, A ; Sharif University of Technology
    2008
    Abstract
    This paper presents the experimental results of impulsive waves caused by subaerial landslides. A wide range of effective parameters are considered and studied by performing 120 laboratory tests. Considered slide masses are both rigid and deformable. The effects of bed slope angle, water depth, slide impact velocity, geometry, shape and deformation on impulse wave characteristics have been inspected. The impulse wave features such as amplitude, period and also energy conversation are studied. The effects of slide Froude number and deformation on energy conversation from slide into wave are also investigated. Based on laboratory measured data an empirical equation for impulse wave amplitude... 

    PELAMIS’s Hydro Dynamical Analyses and Mechanism Design of Wave Energy Converter Device (Semi-PELAMIS)

    , M.Sc. Thesis Sharif University of Technology Saeidi Hamid Abad, Mohammad (Author) ; AbbasPour, Majid (Supervisor)
    Abstract
    Pelamis is a semi-submersible device that can extract wave energy and converters that to electrical power. It has 5 cylindrical structure that connects through the joints. This device takes the shape of wave and the wave forces tubes to had angular relative motion together. The Main task of this device is to convert the angular movements of tubes to the Linear movement of pistons. External mechanism called the energy capture device are responsible for absorbing wave energy through angular movements, and then the internal mechanism, called the Power Take-Off, are responsible for converting this energy into the electrical power for use in the electricity grid. This device was designed and... 

    Design and Constructing a Flap Wave Energy Converter Model

    , M.Sc. Thesis Sharif University of Technology Kouhi Anbaran, Soroush (Author) ; Abbaspour, Majid (Supervisor)
    Abstract
    In the recent decades, because of the reduction of the fossil sources and increasing the environmental pollution, also worldwide population growth and the necessity of energy have made humanbeing to use the Renewable Energy. Wave energy is an opulent source of energy in many parts of the world, especially in Iran.
    In this thesis, in the first chapter, different kinds of renewable energy are introduced, and the importance of them is discussed. In the second chapter, the mechanisms of extracting energy by the wave energy converters are investigated, and their types are discussed. Then, in the next chapter, wave equations, wave spctrums and simulation of a flap wave energy converter in... 

    Optimization of Wave Energy Convertors by Genetic Algorithm

    , M.Sc. Thesis Sharif University of Technology Farshforoush Imani, Amir (Author) ; Abbaspour Tehrani Fard, Majid (Supervisor)
    Abstract
    Given the great potential of energy resources, the utilization of wave energy for electricity production can make a significant contribution to the renewable energy portfolio of coastal nations. There are, however, many challenges that must be overcome in order for wave energy to be commercially viable. One of the key objectives of the wave energy industry today is to produce commercially viable wave farms by placing multiple wave energy converters (WECs) together in an array. The full problem of calculating the power absorbtion of an array of WECs requires not only the complete knowledge of the hydrodynamics of each individual body, but also the scattering and radiation effects between all... 

    Numerical Study of the Floating Oscillating Surge Wave Energy Converter Using the Boundary Element Method

    , M.Sc. Thesis Sharif University of Technology Taghipour, Haniyeh (Author) ; Raie, Mohammad (Supervisor)
    Abstract
    Energy production from fossil fuels such as oil and gas is one of the non-renewable energies, which causes many environmental problems such as global warming and environmental pollution. The existence of these problems has led to agreements such as the Glasgow Environmental Agreement, which obligates governments to apply methods to reduce the production of greenhouse gases, which include reducing the consumption of fossil fuels and increasing the use of renewable energy. Sea wave energy is one of the renewable energies that can be used to generate electricity. In the seas of Iran, including the Caspian Sea, Persian Gulf and Oman, there are sources of wave energy that can be used and are... 

    Details study on the kinematic characteristics of manta ray section in flapping motion and exploring its application in wave glider propulsion system

    , Article Sustainable Energy Technologies and Assessments ; Volume 53 , 2022 ; 22131388 (ISSN) Abbaspour, M ; Safari, H ; Darbandi, M ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    It has always been a human challenge to inspire natural configurations and phenomena and benefit from their merits in improving the performances of man-made proposed aero/hydro vehicles. For example, the manta rays are known for their great swimming performances. To design and fabricate an underwater robot based on the manta ray geometry and its kinematic characteristics, it is important to initially study its hydrodynamic behavior and possibly arrive at some key design parameters, which can remarkably help to figure out an optimum geometry with high swimming performances. The main objective of this study is to focus on the merits of gliding motion inspired by the manta ray fish considering... 

    A low cost Hydrokinetic Wells turbine system for oceanic surface waves energy harvesting

    , Article Renewable Energy ; Volume 156 , 2020 , Pages 610-623 Valizadeh, R ; Abbaspour, M ; Taeibi Rahni, M ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    This paper provides a feasibility study on a low cost system called Hydrokinetic Wells turbine for surface wave energy conversion without using plenum chambers. The elimination of the plenum chamber and its complicated valve systems can reduce the expenses of wave energy conversion up to 23%.The feasibility process were done for high and low frequency conditions. For the low frequency waves, we offer the 300 rpm angular velocity as an optimum selection for further studies. For the high frequency condition a reliable analytical approach based on validated methods was developed. The analytical results indicate that a wells turbine with 60 cm diameter could produce up to 1600 Watts power in... 

    Design and Simulation of a Hydraulic Wave Energy Converter By Use of a Fuzzy Logic Controller

    , M.Sc. Thesis Sharif University of Technology Razavi, Payam (Author) ; Zabihollah, Abolghasem (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
    Abstract
    Problems of global warming have motivated energy communities to design and develop green power generators. Energy of the ocean waves is one of the most fascinating clean energies which have not been completely explored yet. The present work intends to design and develop a novel efficient system to generate electricity using the power of ocean waves. The proposed device can operate in most ocean situations. The device floats with the buoyancy of the buoy over the ocean surface. Regarding the ocean inputs the device is sinking or floating at the ocean to control and optimize input force. In the proposed system kinetic energy of the ocean wave is converted into force. This force moves the... 

    Design and Construction of Ocean Wave Energy Converter

    , M.Sc. Thesis Sharif University of Technology Sarlak Chivaee, Hamid (Author) ; Seif, Mohammad Saeid (Supervisor) ; Abbaspour, Mohammad (Supervisor)
    Abstract
    An important characteristic of sea waves is their high energy density, which is the highest among renewable energy sources. Many different types of wave-energy converters of various categories have been proposed yet. In this thesis the performance of a novel wave energy converter (WEC) is studied. The system, extracts the wave energy from heaving motion of a cylinder buoy in head seas. This heaving cylindrical floating buoy is tested with sinusoidal incident waves in a wave channel in marine engineering laboratory, Sharif University of Technology (SUT). The study begins with a thorough review on types of renewable energy and their application in Iran. Then an introduction to ocean wave,... 

    Iran atlas of offshore renewable energies

    , Article Renewable Energy ; Volume 36, Issue 1 , January , 2011 , Pages 388-398 ; 09601481 (ISSN) Abbaspour, M ; Rahimi, R ; Sharif University of Technology
    2011
    Abstract
    The aim of the present study is to provide an Atlas of IRAN Offshore Renewable Energy Resources (hereafter called 'the Atlas') to map out wave and tidal resources at a national scale, extending over the area of the Persian Gulf and Sea of Oman. Such an Atlas can provide necessary tools to identify the areas with greatest resource potential and within reach of present technology development. To estimate available tidal energy resources at the site, a two-dimensional tidally driven hydrodynamic numerical model of Persian Gulf was developed using the hydrodynamic model in the MIKE 21 Flow Model (MIKE 21HD), with validation using tidal elevation measurements and tidal stream diamonds from... 

    Site Selection and Design of an Optimal OWC System for the Coastal and Offshore Areas of the Persian Gulf and the Sea of Oman

    , M.Sc. Thesis Sharif University of Technology Savaedi, Mohamad (Author) ; Abbaspour Tehrani Fard, Madjid (Supervisor)
    Abstract
    Today, to reduce the effects of greenhouse gases on the earth, as well as reduce dependence on fossil fuels and other non-renewable sources, the international community is moving towards greater use of renewable energy. The oscillating water column device as a wave energy converter system has the ability to use and absorb energy within the waves through a chamber consisting an air and a water column. This system has the ability to move the turbine installed on the valve by expanding and compressing the air passing through the valve. Oscillating water column systems have different categories, and this high diversity makes the choice of this wave energy converter closely related to the... 

    The Effects of PTO Characteristics on Performance of a Floating Point Absorber Wave Energy Converter

    , M.Sc. Thesis Sharif University of Technology Ramazani, Arman (Author) ; Behzad, Mahdi (Supervisor) ; Abazari, Abuzar (Supervisor)
    Abstract
    In recent years, the challenges of using fossil energy causes governments and researchers to focus on renewable energies. In this regard, one of the strategies for generating power is using wave energy converters. The aim of present study is modeling frequency and time domain analysis of the wave energy converter. the study focuses on the effect of Power-Take-Off system on the output power and efficiency under the Macoran sea waves. First, the concept of wave converters is explained and the commercialized ones are introduced. Then the related previous works are reviewed and the wave theories are briefly presented. In the following, a specified one-degree-of-freedom converter is modeled in... 

    Influence of asymmetry on the band structure of photonic crystals

    , Article Proceedings of SPIE - The International Society for Optical Engineering, 26 January 2010 through 28 January 2010 ; Volume 7609 , January , 2010 ; 0277786X (ISSN) ; 9780819480057 (ISBN) Moosavi Mehr, S. H ; Khorasani, S ; Sharif University of Technology
    2010
    Abstract
    Computer calculation of photonic band structure for unit cells of various symmetry in the two-dimensional square lattice suggests that the bandgap calculated by traversing the ΓXM triangle in k-space is only reliable when the unit cell is C4v symmetric. For structures of lower symmetry, examining a two-dimensional subset of the first Brillouin zone will give smaller bandgaps  

    On the effects of landslide deformability and initial submergence on landslide-generated waves

    , Article Landslides ; Volume 16, Issue 1 , 2019 , Pages 37-53 ; 1612510X (ISSN) Yavari Ramshe, S ; Ataie Ashtiani, B ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    This paper represents a numerical study on the effects of landslide initial submergence and its geotechnical and rheological properties on the characteristics of landslide-generated waves (LGWs) and landslide deformation. A number of 117 numerical experiments are performed using a two-layer Coulomb Mixture Flow (2LCMFlow) model on a real-sized numerical flume as a simplified cross section of the Maku dam reservoir, located in the Northwest of Iran. Three different initial locations are considered for landslide representing a subaerial (SAL), a semi-submerged (SSL), and a submarine (SML) landslide. Based on the numerical results, the majority of SMLs and in some cases SSLs generate tsunami... 

    Band-structure calculation of SH-waves in 1D hypersonic nano-sized phononic crystals with deformable interfaces

    , Article Mechanics of Materials ; Volume 171 , 2022 ; 01676636 (ISSN) Jam, M.T ; Shodja, H. M ; Sanati, M ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    Nanoscopic interface deformations between the layers in a superlattice have a great impact on its phononic band-structure. This work aims to study the SH-wave band-structure in one-dimensional (1D) multilayer hypersonic nano-sized phononic crystals with consideration of local deformations at the interfaces of the layers. At this scale, the traditional theory of elasticity is unable to capture the realistic forbidden and permitted frequencies. Thus, in light of surface/interface elastodynamics theory for nanostructures with deformable interfaces, a mixed variational method which accounts for the notion of interface elasticity, deformability, and inertia is introduced in the present work. For... 

    Stability analysis of parametric resonance in spar-buoy based on Floquet theory

    , Article Ocean Engineering ; Volume 266 , 2022 ; 00298018 (ISSN) Aziminia, M. M ; Abazari, A ; Behzad, M ; Hayatdavoodi, M ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Parametric resonance is a phenomenon caused by time-varying changes in the parameters of a system which may result in undesirable motion responses and instability. Floating bodies like ships and spar-buoys are prone to Mathieu instability mainly due to the instantaneous change of the metacentric height. With the fast-growing developments in Ocean Renewable Energy systems, spar-buoys are commonly used for wave energy convertors and floating wind turbines. Undesirable, unstable motions as a result of the parametric resonance can be problematic as it may cause inefficiency in operations and structural risk integrity. In this research, a new approach has been developed to investigate these... 

    Parallelized numerical modeling of the interaction of a solid object with immiscible incompressible two-phase fluid flow

    , Article Engineering Computations (Swansea, Wales) ; Volume 34, Issue 3 , 2017 , Pages 709-724 ; 02644401 (ISSN) Ghasemi, A ; Nikbakhti, R ; Ghasemi, A ; Hedayati, F ; Malvandi, A ; Sharif University of Technology
    Abstract
    Purpose - A numerical method is developed to capture the interaction of solid object with two-phase flow with high density ratios. The current computational tool would be the first step of accurate modeling of wave energy converters in which the immense energy of the ocean can be extracted at low cost. Design/methodology/approach - The full two-dimensional Navier-Stokes equations are discretized on a regular structured grid, and the two-step projection method along with multi-processing (OpenMP) is used to efficiently solve the flow equations. The level set and the immersed boundary methods are used to capture the free surface of a fluid and a solid object, respectively. The full... 

    An energy-efficient controller for wirelessly-powered communication networks

    , Article IEEE Transactions on Communications ; Volume 68, Issue 8 , August , 2020 , Pages 4986-5002 Movahednasab, M ; Makki, B ; Omidvar, N ; Pakravan, M. R ; Svensson, T ; Zorzi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    In a wirelessly-powered communication network (WPCN), an energy access point (E-AP) supplies the energy needs of the network nodes through radio frequency wave transmission, and the nodes store their received energy in their batteries for possible data transmission. In this paper, we propose an online control policy for energy transfer from the E-AP to the wireless nodes and for data transfer among the nodes. With our proposed control policy, all data queues of the nodes are stable, while the average energy consumption of the network is shown to be within a bounded gap of the minimum energy required for stabilizing the network. Our proposed policy is designed using a quadratic Lyapunov...