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    Design and optimization of a heat driven thermoacoustic refrigerator

    , Article Applied Thermal Engineering ; Volume 62, Issue 2 , 25 January 2014 , Pages 653–661 Ghorbanian, K ; Karimi, M ; Sharif University of Technology
    Abstract
    The present paper deals with the design and optimization of a heat driven thermoacoustic refrigerator. A simplified model is developed which enables to pinpoint and examine the most important physical characteristics of a compact traveling wave thermoacoustic refrigerator driven by a traveling wave thermoacoustic engine. The model can explain the so-called traveling standing wave effect in thermoacoustics very well. The position, length and hydraulic radius of the refrigerator are optimized for the maximum total COP. The prime mover efficiency, refrigerator COP and dimensionless dissipation and their impacts on total COP are investigated and discussed. The results indicate that a COP of... 

    Investigation of Effective Parameters on Performance of Microfluidic Microbial Fuel Cell–Microbial Electrolysis Cell Coupled System

    , M.Sc. Thesis Sharif University of Technology Fadakar, Aref (Author) ; Bastani, Dariush (Supervisor) ; Yaghmaei, Soheila (Supervisor) ; Mardanpour, Mohammad Mahdi (Co-Supervisor)
    Abstract
    This study presents the experimental investigation of the microfluidic microbial fuel cell – microbial electrolysis cell coupled system as a bioenergy generator to produce biohydrogen without any external power supply. The effect of microbial fuel cells number (to provide the required potential for microbial electrolysis cell), the type of substrate and its concentration were assessed. The maximum produced hydrogen of 25, 33 and 50 ppm were obtained in flow rate of 200 μl h-1 and glucose concentration of 200 mg l-1 in 1, 2 and 3 stack MFCs, respectively. For urea solution, by combination of 1, 2 and 3 stack MFCs in the flow rate of 200 μl h-1 and the concentration of 800 mg l-1, the maximum... 

    Design and optimization of a heat driven thermoacoustic refrigerator

    , Article Applied Thermal Engineering ; Volume 61, Issue 2 , 2013 , Pages 653-661 ; 13594311 (ISSN) Ghorbanian, K ; Karimi, M ; Sharif University of Technology
    2013
    Abstract
    The present paper deals with the design and optimization of a heat driven thermoacoustic refrigerator. A simplified model is developed which enables to pinpoint and examine the most important physical characteristics of a compact traveling wave thermoacoustic refrigerator driven by a traveling wave thermoacoustic engine. The model can explain the so-called traveling standing wave effect in thermoacoustics very well. The position, length and hydraulic radius of the refrigerator are optimized for the maximum total COP. The prime mover efficiency, refrigerator COP and dimensionless dissipation and their impacts on total COP are investigated and discussed. The results indicate that a COP of... 

    The Fabrication of the Coupled Microfluidic Microbial Electrochemical Cells for Oxalate Biodegradation

    , M.Sc. Thesis Sharif University of Technology Yahyanezhad Gele, Maedeh (Author) ; Yaghmaei, Soheila (Supervisor) ; Mardanpour, Mohammad Mahdi (Co-Supervisor)
    Abstract
    This study invewstigates the performance of a coupled microfluidic microbial fuel cell-microbial electrolysis cell producing biohydrogen in presence of shewanella oneidensis MR-1 from excreted oxalate of human metabolic processes. The effect of different parameters such as cell geometry including spiral and straight microchannels, precipitation of nano-particles on anode surface, substrate flowrate and the number of microfluidic microbial fuel cell supporting required power for microbial electrolysis cell were assessed. By anode modification, the maximum current density of 428 W m-3 was obtained which is less than 6-fold of the maximum power density in the cell fabricated by zinc foil. The... 

    Design and Construction of the Coupled Thermoacoustic Refrigerator

    , M.Sc. Thesis Sharif University of Technology Fazli, Mahyar (Author) ; Soltani, Mohammad Reza (Supervisor) ; Karimi, Mohsen (Co-Advisor)
    Abstract
    One of the significant as well as fascinating utilization of thermoacoustic is combining heat pump and thermoacoustic refrigerator. By means of supplied heat from hear source, the heat pump generates acoustic power which will be absorbed by refrigerator and forwarded to the heat source afterwards. In other words, thermoacoustic systems, from the side of which heat is absorbed, produces chill in the opposite side. Due to the novelty as well as heavy and precise research requirements, these systems has been neither designed nor manufactured in our country yet. In this research a laboratory prototype from aforementioned systems has been constructed, thereby paving the way for enjoying and... 

    Theoretical Investigation of Coupled Microbial Electrochemical Cells in Micro-Sized Systems and Assessment of Biohydrogen Generation

    , M.Sc. Thesis Sharif University of Technology Arab Yarmohammadi, Fatemeh (Author) ; Yaghmaei, Soheila (Supervisor) ; Mardanpour, Mohammad Mahdi (Co-Supervisor)
    Abstract
    Due to the importance of hydrogen production for its applications in therapy, this research reports the fabrication of a coupled microfluidic microbial electrochemical cell, including microfluidic microbial fuel cells (MFCs) and a microfluidic microbial electrolysis cell (MEC) series in order to perform it as a selfpowered bioenergy generator to produce biohydrogen with no need for an external power source. The designed went goes through a validation process that relied on experimental results of a coupled system in glucose degradation. By determining the governing equations of the system and simulating its behavior in various conditions, the effect of operational factors on the system... 

    Solution of coupled system of nonlinear differential equations using homotopy analysis method

    , Article Nonlinear Dynamics ; Volume 56, Issue 1-2 , 2009 , Pages 159-167 ; 0924090X (ISSN) Ganjiani, M ; Ganjiani, H ; Sharif University of Technology
    2009
    Abstract
    In this article, the homotopy analysis method has been applied to solve a coupled nonlinear diffusion-reaction equations. The validity of this method has been successful by applying it for these nonlinear equations. The results obtained by this method have a good agreement with one obtained by other methods. This work illustrates the validity of the homotopy analysis method for the nonlinear differential equations. The basic ideas of this approach can be widely employed to solve other strongly nonlinear problems. © 2008 Springer Science+Business Media B.V  

    Electrical equivalent circuit of multi-mode flexible beams with piezoelectric elements

    , Article Journal of Intelligent Material Systems and Structures ; Volume 19, Issue 5 , 2008 , Pages 621-627 ; 1045389X (ISSN) Saghafi, M ; Meghdari, A ; Sharif University of Technology
    2008
    Abstract
    Surface mounted piezoelectric sensors and actuators on elastic structures are often connected to electrical networks. The coupled equations of motion of the elastic structure with piezoelectric elements are already well known. However, due to complex behavior of some electrical elements in the electrical network, it is not an easy task to obtain the integrated equations of the whole system. A good remedy for this problem is to take advantage of an equivalent electrical circuit (EEC) representation of the mechanical part, leading the entire system to be represented as an electrical circuit. In this study, the authors propose a new method for constructing the EEC. This method is based upon the... 

    Experimental Investigation of the Microbial Fuel Cell–Microbial Electrolysis Cell Coupled System for Dairy Wastewater Treatment and Hydrogen Production

    , M.Sc. Thesis Sharif University of Technology Rezaei Ansari, Mustapha (Author) ; Yaghmaei, Soheyla (Supervisor) ; Roosta Azad, Reza (Supervisor)
    Abstract
    Microbial electrolysis cell- microbial fuel cell (MFC-MEC) coupled system is one of the novel method, for in-situ utilization from the wastewater and generating electricity and hydrogen simultaneously. In this system, required energy for microbial electrolysis cell supply by electric energy generated in microbial fuel cell. Implementation of this system is complicated, because of its unsteady state nature. In this study, it is demonstrated that the hydrogen production in such an MEC-MFC coupled sustem can be manipulated through adjusting the power input on the MEC. The power input of the MEC is regulated by adding MFCs connected into the circuit in series. When one MFC add to the coupled... 

    Vibration analysis of a composite Timoshenko beam with actuating layers under motion of a uniformlly traveling partially disributed mass

    , Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 9 PART C , 2008 , Pages 1933-1942 ; 0791843033 (ISBN); 9780791843031 (ISBN) Ahmadian, M. T ; Pirbodaghi, T ; Paak, M ; Hassanpour, S ; Sharif University of Technology
    2008
    Abstract
    In this paper, a thorough investigation of response of a composite Timoshenko simply-supported beam with actuating layers, under the motion of a partially distributed mass is studied and a control system based on the feedback of beam's deflection velocity is applied to alleviate and suppress the vibration of the beam in either case when the mass is still traveling on the beam or departed the beam. The actuating layers are made up of Terfenol-D smart material which are sensitive to magnetic field (magnetostrictive materials) and this trait makes them very suitable to be used for vibration control. They introduce damping to the system through which the energy of system dissipates. The response... 

    Nonlinear analysis of a flexible beam actuated by a couple of active SMA wire actuators

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 25, Issue 3 , 2012 , Pages 249-264 ; 17281431 (ISSN) Sayyaadi, H ; Zakerzadeh, M. R ; Sharif University of Technology
    2012
    Abstract
    There are two different ways of using SMA wires as actuators for shape control of flexible structures; which can be either embedded within the composite laminate or externally attached to the structure. Since the actuator can be placed at different offset distances from the beam, external actuators produce more bending moment and, consequently, considerable shape changes with the same magnitude of the actuation force comparing to the embedded type. Such a configuration also provides fast convection which is very important in shape control applications that require a high-frequency response of SMA actuators. Although combination and modeling of externally-attached SMA actuator wires and... 

    Analysis of a flexible beam actuated by two active SMA wires

    , Article ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2010, 28 September 2010 through 1 October 2010 ; Volume 1 , October , 2010 , Pages 661-672 ; 9780791844151 (ISBN) Zakerzadeh, M. R ; Sayyaadi, H ; Aerospace Division ; Sharif University of Technology
    2010
    Abstract
    There are two ways of using SMAs as actuators for shape control of flexible structures; they can be either embedded within composite laminates or externally attached to the structures. Since the actuator can be placed at different offset distances from the beam, external actuators produce more bending moment and, consequently, more shape change. Such a configuration also allows introduction of fast convection cooling, very important in shape control applications that require a high-frequency response of SMA actuators. Although combination and modeling of externally-attached SMA actuator wires and strips have been widely considered by some researchers, these studies have some weaknesses that... 

    Modeling of a nonlinear Euler-Bernoulli flexible beam actuated by two active shape memory alloy actuators

    , Article Journal of Intelligent Material Systems and Structures ; Volume 22, Issue 11 , 2011 , Pages 1249-1268 ; 1045389X (ISSN) Zakerzadeh, M. R ; Salehi, H ; Sayyaadi, H ; Sharif University of Technology
    2011
    Abstract
    There are two different ways of using shape memory alloy (SMA) wire as an actuator for shape control of flexible structures: it can be either embedded within the composite laminate or externally attached to the structure. As the actuator can be placed at different offset distances from the beam, external actuators produce more bending moment and, consequently, considerabnle shape changes with the same magnitude of actuation force compared with the embedded type. Such a configuration also provides faster heat transfer rate owing to convection, which is very important in shape control applications that require a highfrequency response of SMA actuators. Although combination and physics-based...