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    Analytical solution for axisymmetric buckling of joined conical shells under axial compression

    , Article Structural Engineering and Mechanics ; Volume 54, Issue 4 , 2015 , Pages 649-664 ; 12254568 (ISSN) Kouchakzadeh, M. A ; Shakouri, M ; Sharif University of Technology
    Techno Press  2015
    In this study, the authors present an analytical approach to find the axisymmetric buckling load of two joined isotropic conical shells under axial compression. The problem of two joined conical shells may be considered as the generalized form of joined cylindrical and conical shells with constant or stepped thicknesses. Thickness of each cone is constant; however it may be different from the thickness of the other cone. The boundary conditions are assumed to be simply supported with rigid rings. The governing equations for the conical shells are obtained and solved with an analytical approach. A simple closed-form expression is obtained for the buckling load of two joined truncated conical... 

    Design and application of a new tapered superelement for analysis of revolving geometries

    , Article Finite Elements in Analysis and Design ; Volume 47, Issue 11 , November , 2011 , Pages 1242-1252 ; 0168874X (ISSN) Ahmadian, M. T ; Movahhedy, M. R ; Rezaei, M. M ; Sharif University of Technology
    Structures of tapered geometry are customarily used in a variety of applications. The analysis of such structures is usually made through finite element method using traditional beam, shell or brick elements. In this paper, a new tapered superelement is presented that lends itself to modeling revolving geometries under lateral, axial and torsional loads. The presented tapered superelement has 16 nodes. The performance of this element under static and dynamic loading and in rotating condition is examined. It is shown that this element yields accurate results with higher computational efficiency compared to conventional elements. Furthermore, it is verified that a single tapered superelement... 

    High-throughput 0.13-μm CMOS lattice reduction core supporting 880 Mb/s detection

    , Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 21, Issue 5 , July , 2013 , Pages 848-861 ; 10638210 (ISSN) Shabany, M ; Youssef, A ; Gulak, G ; Sharif University of Technology
    This paper presents the first silicon-proven implementation of a lattice reduction (LR) algorithm, which achieves maximum likelihood diversity. The implementation is based on a novel hardware-optimized due to the Lenstra, Lenstra, and Lovász (LLL) algorithm, which significantly reduces its complexity by replacing all the computationally intensive LLL operations (multiplication, division, and square root) with low-complexity additions and comparisons. The proposed VLSI design utilizes a pipelined architecture that produces an LR-reduced matrix set every 40 cycles, which is a 60% reduction compared to current state-of-the-art LR field-programmable gate array implementations. The 0.13-μm CMOS... 

    Design and fuzzy control of a moving magnetic levitation device for 3D manipulation of small objects

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 5 , 2010 , Pages 255-261 ; 9780791849194 (ISBN) Molavian Jazi, M ; Vossoughi, G ; Tajaddodianfar, F ; Sharif University of Technology
    Magnetic levitation is an appropriate solution for noncontact 3D manipulation. Workspace of the previously proposed maglev systems are confined to a relatively small cube, and this severely limits application of this technology. In addition, most of the previously given mechanisms require design and application of a subsystem for unifying their magnetic field. In this paper, a moving magnet is implemented which results in horizontally extendable work space; moreover, the field unifying section is not needed since one electromagnet only is used. Further, details of the mechanism and finite element based design procedure of the magnet are presented. Dynamic equations of the system derived by... 

    Investigating fluid invasion control by Colloidal Gas Aphron (CGA) based fluids in micromodel systems

    , Article Journal of Natural Gas Science and Engineering ; Volume 66 , 2019 , Pages 1-10 ; 18755100 (ISSN) Pasdar, M ; Kamari, E ; Kazemzadeh, E ; Ghazanfari, M. H ; Soleymani, M ; Sharif University of Technology
    Elsevier B.V  2019
    Recently, Colloidal Gas Aphron (CGA) based fluids have been introduced to further develop depleted hydrocarbon reservoirs. This fluid system has been employed in an attempt to control drilling fluid invasion and, thus, reducing formation damage occurred during drilling operations. Understanding the mechanisms of fluid invasion control is of great importance for successful design and application of CGA-based fluids in drilling operations. Although fluid flow of conventional foams has been studied extensively in the available literature, little attention has been paid to CGA fluids flow, especially in heterogeneous fractured porous media. Here, an experimental study was conducted to achieve... 

    Design and application of (Fe3O4)-GOTfOH based AgNPs doped starch/PEG-poly (acrylic acid) nanocomposite as the magnetic nanocatalyst and the wound dress

    , Article Journal of Molecular Structure ; Volume 1214 , 2020 Forouzandehdel, S ; Meskini, M ; Rami, M. R ; Sharif University of Technology
    Elsevier B.V  2020
    As a novel, recyclable nanocatalyst, (Fe3O4)-GOTfOH based Ag nanoparticles doped Starch/PEG-poly (acrylic acid) nanocomposite (Fe3O4@GOTfOH/Ag/St-PEG-AcA) was applied for one-pot synthesis of 2,4,6-triarylpyridine derivatives under water solvent conditions. The prepared nanocomposite was also evaluated in terms of biocompatibility for wound healing. Fe3O4@GOTfOH/Ag/St-PEG-AcA could be easily removed from the mixture of the reaction by an external magnet and recycled without a considerable decrease of activity even after 10 runs. The new nanocatalyst offered better efficiencies than other commercially available sulfonic acid catalysts. In terms of the bioactivity of nanocatalyst, good... 

    Application of a new cylindrical element formulation in finite element structural analysis of FGM hollow cylinders

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 14 , 2009 , Pages 21-25 ; 9780791848753 (ISBN) Ahmadian, M. T ; Taghvaeipour, A ; Bonakdar, M ; Sharif University of Technology
    Functionally graded materials are advanced composite materials consisting two or more material ingredients that are engineered to have a continuous spatial variation of properties. There are a few analytical methods available to solve the governing equations of FGM made structures, confined to some specific and limited shapes, loadings and boundary conditions. Hence the numerical methods such as FEM are used to treat these materials. In previous studies the finite element method was used to solve thin walled FG structures like shells and plates by modification of the conventional shell and plate elements. Solving the thick walled FG structures confronts some difficulties. One of the methods... 

    Cell "vision": Complementary factor of protein corona in nanotoxicology

    , Article Nanoscale ; Volume 4, Issue 17 , 2012 , Pages 5461-5468 ; 20403364 (ISSN) Mahmoudi, M ; Saeedi-Eslami, S. N ; Shokrgozar, M. A ; Azadmanesh, K ; Hassanlou, M ; Kalhor, H. R ; Burtea, C ; Rothen Rutishauser, B ; Laurent, S ; Sheibani, S ; Vali, H ; Sharif University of Technology
    RSC  2012
    Engineered nanoparticles are increasingly being considered for use as biosensors, imaging agents and drug delivery vehicles. Their versatility in design and applications make them an attractive proposition for new biological and biomedical approaches. Despite the remarkable speed of development in nanoscience, relatively little is known about the interaction of nanoscale objects with living systems. In a biological fluid, proteins associate with nanoparticles, and the amount and the presentation of the proteins on their surface could lead to a different in vivo response than an uncoated particle. Here, in addition to protein adsorption, we are going to introduce concept of cell "vision",...