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    A new formulation for equivalent hydrodynamic modeling of the Jack-up legs

    , Article Proceedings of the 21st International Conference on Offshore Mechanics and Arctic Engineering (OMAE), Oslo, 23 June 2002 through 28 June 2002 ; Volume 1 , 2002 , Pages 605-611 Daghigh, M ; ASME ; Sharif University of Technology
    2002
    Abstract
    Regulations of offshore structures suggest the application of Morison type equation for the estimation of forces induced by wave and current on the slender bodies of Jacket and Jack-up structures. However, common values of hydrodynamic coefficients are rarely defined in two different regulations. Estimation of global responses of Jack-up structure, the simplified geometrical model is used, therefore we will try to modify the DNV formulations in order to estimate the hydrodynamic forces on equivalent pile. Finally, the forces on the real structure and the equivalent pile model are compared and it has been shown that the approximation of the inertia forces has more accuracy comparing to the... 

    Connectivity analysis of one-dimensional ad hoc networks with arbitrary spatial distribution for variable and fixed number of nodes

    , Article IEEE Transactions on Mobile Computing ; Volume 11, Issue 10 , 2012 , Pages 1425-1435 ; 15361233 (ISSN) Sharif Nassab, A ; Ashtiani, F ; Sharif University of Technology
    2012
    Abstract
    In this paper, we propose an analytical approach to compute the probability of connectivity for one-dimensional ad hoc networks. The proposed analysis gives the exact probability of connectivity for an arbitrary distribution of nodes, provided that nodes are independently and identically distributed. We conduct separate analyses for two cases; in the first case, the number of nodes varies by time under a stationary distribution and in the second case, there is a fixed (known) number of nodes in the network. Using the approaches presented in this work, we are able to derive closed-form formulas for the probability of connectivity for some spatial distributions, while for more complicated... 

    A new mechanism for wall climbing operation based on 4-bar linkage

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Sharif Shourijeh, M ; Sayyaadi, H ; Sharif University of Technology
    2006
    Abstract
    Wall walking robots are designed for different purposes, rescue operations, wall inspections and jobs such as painting and cleaning and fire fighting for tall buildings. These are some cases that these types of robots are extensively used. This paper describes a design of a new serial mechanism for wall climbing job. In deed we are seeking to define a minimum degree of freedom mechanism to be applied in a robot moving vertically on a surface. This mechanism has 5 links, but at any point it works with its 4 links, actually in each cycle of motion the linkage will be interchanged. Copyright © 2006 by ASME  

    Peak to mean envelope power ratio of oversampled OFDM signals: An analytical approach

    , Article International Conference on Communications (ICC2001), Helsinki, 11 June 2000 through 14 June 2000 ; Volume 5 , 2001 , Pages 1476-1480 ; 05361486 (ISSN) Sharif, M ; Khalaj, B. H ; Sharif University of Technology
    2001
    Abstract
    Orthogonal frequency division multiplexing (OFDM) has a large peak to mean envelope power ratio (PMEPR), which can result in significant signal distortion in presence of nonlinear amplifiers. In this paper, we will show that peak of the continuous envelope of OFDM signal can be bounded by maximum of corresponding oversampled sequence. This fact is then used as the corner stone of our study in two parts. In the first part, statistical analysis is used to find probability upper bound for complementary cumulative distribution function of PMEPR. It is also proven that for large number of subcarriers, only one redundant bit is necessary to limit PMEPR within %10 of its maximum value. In the... 

    A micromechanical model for coupled interaction of thermomechanical and corrosion fatigue in microelectronics thin-film metallizations

    , Article Fifth International Conference on Computer Methods and Experimental Measurements for Surface Treatment Effects, Surface Treatment V, Seville, 20 June 2001 through 22 June 2001 ; Volume 6 , 2001 , Pages 429-438 ; 1853128643 (ISBN) Shodja, H. M ; Wessex Institute of Technology ; Sharif University of Technology
    2001
    Abstract
    Having studied the intergranular crack nucleation in bicrystalline materials under fatigue [1], the concepts are extended to innovative treatise of crack initiation in thin-film metallizations under coupled interaction of thermomechanical fatigue (IMF) and corrosion. The pile-up of dislocations under thermal cycling and diffusion of corrosive agents have interacting effects in accelerating crack nucleation. It is shown that the corresponding evolutionary partial differential equation (PDE), which governs diffusion of the corrosive agent, contains two terms that involve the first and second spatial derivatives of hydrostatic pressure. Through dependence of the hydrostatic pressure on normal... 

    An appraisal of forest sustainability in the Asian and Pacific Region

    , Article Third International Conference on Ecosystems and Sustainable Development ECOSUD 2001, Alicante, 6 June 2001 through 8 June 2001 ; Volume 10 , 2001 , Pages 615-621 ; 13698273 (ISSN) Vaziri, M ; Rassafi, A. A ; Wessex Institute of Technology; University of Alicante ; Sharif University of Technology
    2001
    Abstract
    The assessment of forest sustainability in the Asian and Pacific Region was carried out. It was stated that 61 countries are members of the largest United Nations regional commission, the Economic Commission for Asia and Pacific (ESCAP). The study showed that for about one third of these countries, the national forest and woodland coverage has steadily diminished and for more than 50 percent of the remaining countries the coverage has not improved significantly. The results confirmed the significance of the region 's forest sustainability problem and its forthcoming challenges for the 21st century  

    Dynamic analysis of human ear during sound transmission

    , Article 3rd international Conference on Manufacturing Science and Engineering, ICMSE 2012, Xiamen, 27 March 2012 through 29 March 2012 ; Volume 472-475 , 2012 , Pages 1215-1219 ; 10226680 (ISSN); 9783037853702 (ISBN) Ghafari, A. S ; Zahiri, S ; Fujian University of Technology; Xiamen University; Fuzhou University; Huaqiao University; University of Wollongong ; Sharif University of Technology
    2012
    Abstract
    The aim of the present research is to simulate dynamic behavior of the human auditoria peripherals during sound transmission using the equivalent six-degrees-of-freedom lumped parameter mathematical model. Transmissibility analysis was employed to get a better insight into the sound transmission from tympanic membrane to malleus, incus, stapes, and cochlea. Furthermore, transmissibility from each member to corresponding adjacent member was carried out to functional analysis of the human ear. Simulation study illustrated that the results are in agreement with the experimental results published in the literature, and the proposed model provides more information in the dynamic analysis of... 

    Second-order calibration for simultaneous determination of pharmaceuticals in water samples by solid-phase extraction and fast high-performance liquid chromatography with diode array detector

    , Article Chemometrics and Intelligent Laboratory Systems ; Vol. 137, issue , 2014 , pp. 146-154 ; ISSN: 01697439 Akvan, N ; Parastar, H ; Sharif University of Technology
    2014
    Abstract
    A fast high-performance liquid chromatography-diode array detection (HPLC-DAD) approach combined to solid phase extraction (SPE) as a pre-concentration step is developed for simultaneous determination of five selected pharmaceuticals (carbamazepine, naproxen, diclofenac, gemfibrozil and mefenamic acid) in water samples. The effective factors on the efficiency of SPE procedure are optimized using faced-centered central composite design (FCCD). In addition, multi-response optimization by using Derringer's desirability function is used to find the optimum experimental conditions for extraction of analytes from well and river waters. Due to the complexity of water matrices and the presence of... 

    Fine-grained architecture in dark silicon era for SRAM-based reconfigurable devices

    , Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Vol. 61, Issue. 10 , 2014 , Pages 798-802 ; ISSN: 15497747 Yazdanshenas, S ; Asadi, H ; Sharif University of Technology
    2014
    Abstract
    In this brief, we present a fine-grained dark silicon architecture to facilitate further integration of transistors in static random access memory-based reconfigurable devices. In the proposed architecture, we present a technique to power off inactive configuration cells in nonutilized or underutilized logic blocks. We also propose a routing circuitry capable of turning off the configuration cells of connection blocks (CBs) and switch boxes (SBs) in the routing fabric. Experimental results carried out on the Microelectronics Center of North Carolina benchmark show that power consumption in configuration cells of lookup tables, CBs, and SBs can, on average, be reduced by 27%, 75%, and 4%,... 

    Infeasibility proof and information state in network information theory

    , Article IEEE Transactions on Information Theory ; Vol. 60, Issue. 10 , 2014 , Pages 5992-6004 ; ISSN: 00189448 Gohari, A ; Anantharam, V ; Sharif University of Technology
    2014
    Abstract
    In this paper, we revisit the structure of infeasibility results in network information theory, based on a notion of information state. We also discuss ideas for generalizing a known outer bound for lossless transmission of independent sources over a network to one of lossy transmission of dependent sources over the same network. To concretely demonstrate this, we apply our ideas and prove new results for lossy transmission of dependent sources by generalizing: 1) the cut-set bound; 2) the best known outer bound on the capacity region of a general broadcast channel; and 3) the outer bound part of the result of Maric, Yates, and Kramer on strong interference channels with a common message  

    Microstructure, mechanical properties, corrosion behavior and cytotoxicity of Mg-Zn-Al-Ca alloys as biodegradable materials

    , Article Journal of Alloys and Compounds ; Vol. 607 , 2014 , Pages 1-10 ; ISSN: 09258388 Homayun, B ; Afshar, A ; Sharif University of Technology
    2014
    Abstract
    Recently, considerable attentions have been paid to alloy Mg-4Zn-0.2Ca for biomedical applications due to its suitable biocompatibility and acceptable mechanical properties. In this work, the effects of the addition of different amounts of Al on microstructure, mechanical properties, degradation behavior, and biocompatibility of this alloy were investigated. The corrosion behaviors of the alloys were investigated through polarization tests, chronoamperometry analysis, immersion tests, and EIS experiments. The mechanical properties were analyzed by using tensile tests and compression tests. The results showed that the addition of Al up to 3 wt.% considerably modifies the degradation behaviors... 

    The use of graphene in the self-organized differentiation of human neural stem cells into neurons under pulsed laser stimulation

    , Article Journal of Materials Chemistry B ; Vol. 2, Issue. 34 , 2014 , Pages 5602-5611 ; ISSN: 20507518 Akhavan, O ; Ghaderi, E ; Sharif University of Technology
    2014
    Abstract
    An effective and self-organized differentiation of human neural stem cells (hNSCs) into neurons was developed by the pulsed laser stimulation of the cells on graphene films (prepared by drop-casting a GO suspension onto quartz substrates). The effects of graphene oxide (GO) and hydrazine-reduced graphene oxide (rGO) sheets on the proliferation of hNSCs were examined. The higher proliferation of the cells on the GO was assigned to its better hydrophilicity. On the other hand, the rGO sheets, which have significantly better electrical conductivity than GO, exhibited more differentiation of the cells into neurons. The pulsed laser stimulation not only resulted in an accelerated differentiation... 

    Connectedness of users-items networks and recommender systems

    , Article Applied Mathematics and Computation ; Vol. 243 , 2014 , Pages 578-584 ; ISSN: 00963003 Gharibshah, J ; Jalili, M ; Sharif University of Technology
    2014
    Abstract
    Recommender systems have become an important issue in network science. Collaborative filtering and its variants are the most widely used approaches for building recommender systems, which have received great attention in both academia and industry. In this paper, we studied the relationship between recommender systems and connectivity of users-items bipartite network. This results in a novel recommendation algorithm. In our method recommended items are selected based on the eigenvector corresponding to the algebraic connectivity of the graph - the second smallest eigenvalue of the Laplacian matrix. Since recommending an item to a user equals to adding a new link to the users-items bipartite... 

    Effect of metal doping, boron substitution and functional groups on hydrogen adsorption of MOF-5: A DFT-D study

    , Article Computational and Theoretical Chemistry ; Vol. 1044, issue , 2014 , Pages 36-43 ; ISSN: 2210271X Lotfi, R ; Saboohi, Y ; Sharif University of Technology
    2014
    Abstract
    In the present work, adsorption of hydrogen molecules over a metal organic framework (MOF-5) has been investigated by using first principles density functional theory (DFT). Different strategies have been applied for improving hydrogen storage, i.e. metal doping, boron substitution and functionalization. The metal atoms used for enhancing hydrogen adsorption include Li, Ca and Sc. It is found that the binding energy between these metal atoms and MOF is not enough to prevent clustering. Therefore a number of carbon atoms are substituted by boron atoms and it is indicated that boron substitution enhances the binding energies, significantly. Also the results reveal that boron substituted MOF... 

    N-way partial least squares with variable importance in projection combined to GC × GC-TOFMS as a reliable tool for toxicity identification of fresh and weathered crude oils

    , Article Analytical and Bioanalytical Chemistry ; Volume 407, Issue 1 , 2014 , pp 285-295 ; ISSN: 16182650 Mostafapour, S ; Parastar, H ; Sharif University of Technology
    2014
    Abstract
    In this study, N-way partial least squares (NPLS) is proposed to correlate comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC × GC-TOFMS) data of different aromatic oil fractions (fresh and weathered) to their toxicity values. Before NPLS modeling, since drift and wander of baseline interfere with information of sought analytes in GC × GC-TOFMS data, a novel method called two-dimensional asymmetric least squares is thus developed for comprehensive correction of the baseline contributions in both chromatographic dimensions. The algorithm is termed comprehensive because it functions to correct the entire chromatogram in both dimensions and it preserves the... 

    Low voltage ride-through capability improvement of DFIG-based wind turbines under unbalanced voltage dips

    , Article International Journal of Electrical Power and Energy Systems ; Vol. 60,Issue , 2014 , pp. 82-95 ; ISSN: 01420615 Rahimi, M ; Parniani, M ; Sharif University of Technology
    2014
    Abstract
    This paper proposes a competent and effective scheme to enhance the ride-through capability of DFIG-based wind turbines under unbalanced voltage dip conditions. The proposed method is realized through joint use of the rotor-side converter control and a three-phase stator damping resistor (SDR) placed in series with the stator windings. By means of an asymmetrical SDR idea, during the unbalanced voltage dip the SDR resistors are activated only in phase(s) experiencing low voltage. Then, the rotor current is controlled such that no unbalance voltage appears on the stator voltage. The proposed ride-through approach limits the peak values of the rotor inrush current, electromagnetic torque and... 

    Game theoretic based charging strategy for plug-in hybrid electric vehicles

    , Article IEEE Transactions on Smart Grid ; Vol. 5,Issue. 5 , 2014 , pp. 2368-2375 ; ISSN: 19493053 Bahrami, S ; Parniani, M ; Sharif University of Technology
    2014
    Abstract
    In the future smart grids, Plug-in Hybrid Electric Vehicles (PHEVs) are seen as an important means of transportation to reduce greenhouse gas emissions. One of the main issues regarding to this sort of vehicles is managing their charging time to prevent high peak loads over time. Deploying advanced metering and automatic chargers can be a practical way not only for the vehicle owners to manage their energy consumption, but also for the utilities to manage the electricity load during the day by shifting the charging loads to the off-peak periods. Additionally, an efficient charging schedule can reduce the users' electricity bill cost. In this paper we propose a new practical demand response... 

    High-performance/low-temperature-processed dye solar cell counter electrodes based on chromium substrates with cube-like morphology

    , Article Journal of Power Sources ; Vol. 260 , 2014 , Pages 299-306 ; ISSN: 03787753 Behrouznejad, F ; Taghavinia, N ; Sharif University of Technology
    2014
    Abstract
    There is still an open question of how to prepare high-performance counter electrodes for dye solar cells (DSCs) at room temperature; a requirement for flexible DSCs. Here, we introduce Pt deposited cube-like chromium coating as a low-temperature highly-efficient counter electrode for DSCs. Cr is a chemically stable metal and can be easily electroplated on conductive substrates with high roughness (here ∼160 nm) and cube-like appearance. A cyclic electrochemical deposition method with optimized temperature and number of cycles is used to grow Pt nanoparticles on this surface and charge transfer resistance as low as 0.54 Ω cm2 and 0.27 Ω cm2 were obtained at 40 °C and 55 °C solution... 

    Extending a hybrid finite-volume-element method to solve laminar diffusive flame

    , Article Numerical Heat Transfer, Part B: Fundamentals ; Vol. 66, issue. 2 , August , 2014 , pp. 181-210 ; ISSN: 10407790 Darbandi, M ; Ghafourizadeh, M ; Sharif University of Technology
    2014
    Abstract
    We extend a hybrid finite-volume-element (FVE) method to treat the laminar reacting flow in cylindrical coordinates considering the collocation of all chosen primitive variables. To approximate the advection fluxes at the cell faces, we use the upwind-biased physical influence scheme PIS and derive a few new extended expressions applicable in the cylindrical frame. These expressions are derived for both the Navier-Stokes and reactive flow governing equations, of which the latter expressions are considered novel in the finite-volume formulation. To validate our derived expressions, the current results are compared with the experimental data and other available numerical solutions. The results... 

    Experimental investigation of asphaltene-induced core damage during miscible CO2 injection

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 13 , 2014 , pp. 1395-1405 ; ISSN: 15567036 Bolouri, H ; Ghoodjani, E ; Sharif University of Technology
    2014
    Abstract
    In this article, dynamic core flood experiments in miscible CO2 condition were carried out to investigate core damage due to asphaltene deposition. Carbonate and sandstone cores were used to study of effect of core characteristic on permeability and porosity reduction. The experimental results show asphaltene deposition preferentially in sandstone core type takes place in the first half of the core while in the carbonate one it occurs in the second half. In spite of asphaltene content measurement results (IP-143) that show higher asphaltene deposition in sandstone cores, permeability impairment compared to the carbonate one is severe. Also, permeability-porosity reduction models are affected...