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    Significance of effective number of cycles in endurance time analysis

    , Article Asian Journal of Civil Engineering ; Volume 13, Issue 5 , 2012 , Pages 647-657 ; 15630854 (ISSN) Mashayekhi, M ; Estekanchi, H. E ; Sharif University of Technology
    AJCE  2012
    Endurance Time (ET) method is a dynamic analysis procedure using intensifying accelerograms which can be used to assess the structural performance at different excitation levels. In generation process of current ET accelerograms, the compatibility between acceleration spectrum produced by the ET accelerograms and acceleration spectrum associated with the real ground motions is applied, whereas the duration consistency is not directly considered. It is generally accepted that the strong-motion duration can strongly influence the response of structures which have stiffness or strength degrading characteristics. In this study, the number of cycles that a structure should resist due to a ground... 

    Triangular labyrinth side weirs with one and two cycles

    , Article Proceedings of the Institution of Civil Engineers: Water Management ; Volume 166, Issue 1 , 2013 , Pages 27-42 ; 17417589 (ISSN) Borghei, S. M ; Nekooie, M. A ; Sadeghian, H ; Ghazizadeh, M. R. J ; Sharif University of Technology
    Labyrinth side weirs provide a potentially effective way to shorten the length of a channel opening with the desired water height, but the discharge coefficient needs to be found experimentally. Experiments were carried out for triangular labyrinth side weirs with one and two cycles in order to obtain the discharge coefficient. The test variables included channel opening, head angle, number of cycles, weir height, upstream water depth and discharge in a subcritical situation. The resultsshow that the discharge coefficient ratio for a triangular labyrinth to a conventional side weir could rise to more than 2 with the same flow and geometric conditions. Relationships for the De Marchi... 

    Applying circular coloring to open shop scheduling

    , Article Scientia Iranica ; Volume 15, Issue 5 , 2008 , Pages 652-660 ; 10263098 (ISSN) Modarres, M ; Ghandehari, M ; Sharif University of Technology
    Sharif University of Technology  2008
    In this paper, a new approach to formulate a class of scheduling problems is introduced, which can be applied to many other discrete problems with complicated structures. The concept of graph circular coloring is applied to develop a model for the special case of an open shop scheduling problem. In this problem, there are some independent jobs to be processed in a shop with dedicated renewable resources. Each job consists of several tasks with no precedence restriction. Each task is processed without preemption. The processing time of the tasks is given. Processing each task requires using some multiple specified types of resource, while no more than one task can use each resource,... 

    Optimal Ag2S nanoparticle incorporated TiO2 nanotube array for visible water splitting

    , Article RSC Advances ; Volume 4, Issue 15 , 2014 , Pages 7838-7844 ; ISSN: 20462069 Gholami, M ; Qorbani, M ; Moradlou, O ; Naseri, N ; Moshfegh, A. Z ; Sharif University of Technology
    Free-standing TiO2 nanotube array (TNA) films were fabricated via two-step anodization of a titanium sheet. The X-ray diffraction pattern indicated amorphous TNAs were transformed into anatase after annealing the films at 500 °C in air. The surface of TNA was modified by a sequential-chemical bath deposition (S-CBD) method to fabricate Ag2S nanoparticles and forming TNA/Ag2S-n nanostructure, by varying the number of cycles (n). Based on SEM observations, the produced films consisted of vertically ordered tubular structure arrays, each with 125 nm in diameter and 4.1 μm in length containing silver sulphide nanoparticles of ∼12 nm diameter. X-Ray photoelectron spectroscopy (XPS) confirmed the... 

    Effects of membrane compliance on pore water pressure generation in gravelly sands under cyclic loading

    , Article Geotechnical Testing Journal ; Volume 33, Issue 5 , 2010 ; 01496115 (ISSN) Haeri, S. M ; Shakeri, M. R ; Sharif University of Technology
    The paper deals with an experimental study of the undrained cyclic behavior of a natural coarse sand and gravel deposit located in Tehran, a megacity situated on the continental side of the Alborz Mountain in Iran. Membrane compliance that plays a significant role in inhibiting redistribution of pore pressure and liquefaction in undrained cyclic triaxial tests performed on coarse granular soils is studied in this paper. Currently there is no or little satisfactory method for accounting for this phenomenon for gravelly soils, and thus the non-compliant cyclic loading resistanceof granular soils and the evaluation of the behavior of such material in natural and in situ state are not easily... 

    A low-latency low-power QR-decomposition ASIC implementation in 0.13 μm CMOS

    , Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 60, Issue 2 , 2013 , Pages 327-340 ; 15498328 (ISSN) Shabany, M ; Patel, D ; Gulak, P. G ; Sharif University of Technology
    This paper presents a hybrid QR decomposition (QRD) design that reduces the number of computations and increases their execution parallelism by using a unique combination of Multi-dimensional Givens rotations, Householder transformations and conventional 2-D Givens rotations. A semi-pipelined semi-iterative architecture is presented for the QRD core, that uses innovative design ideas to develop 2-D, Householder 3-D and 4-D/2-D configurable CORDIC processors, such that they can perform the maximum possible number of vectoring and rotation operations within the given number of cycles, while minimizing gate count and maximizing the resource utilization. Test results for the 0.3 mm 2 QRD chip,... 

    Experimental study on dynamic properties of sand with emphasis on the degree of saturation

    , Article Soil Dynamics and Earthquake Engineering ; Volume 32, Issue 1 , 2012 , Pages 26-41 ; 02677261 (ISSN) Jafarzadeh, F ; Sadeghi, H ; Sharif University of Technology
    Cyclic drained and undrained tests were performed in a modified simple shear device in order to specifically investigate the effect of saturation ratio on shear modulus and damping parameters of sand. In addition to the degree of saturation, the effects of number of cycles, vertical consolidation stress, shear strain amplitude and relative density on dynamic properties of sand were investigated. Dynamic stiffness and damping characteristic were found to be substantially independent of saturation ratio in the range of 25-75%. However, by approaching the full saturation state, the values of modulus fall sharply and damping of loose samples increases dramatically from corresponding values of... 

    IMAC: An Interference-aware duty-cycle MAC protocol for wireless sensor networks employing multipath routing

    , Article Proceedings - 2011 IFIP 9th International Conference on Embedded and Ubiquitous Computing, EUC 2011 ; 2011 , Pages 288-293 ; 9780769545523 (ISBN) Eskandari, L ; Yousefi, H ; Movaghar, A ; Khansari, M ; Sharif University of Technology
    The main source of energy consumption in the current MAC protocols for wireless sensor networks is idle listening. To mitigate this problem, duty cycling is used. However, it increases data delivery latency. In this paper, we propose an Interference-aware duty-cycle MAC (IMAC) protocol for wireless sensor networks that uses cross-layer information to reserve multiple paths for each source and send data packets along them efficiently. IMAC also handles the existing interference between these paths such that data packets can be delivered in the minimum required number of cycles. Simulation results in ns-2 show that the proposed algorithm has an average reduction of 49% in data delivery latency... 

    Response of a novel beam-to-column connection to monotonic and cyclic flexural loading

    , Article Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, 9 June 2008 through 13 June 2008, Berlin ; Volume 2 , 2008 , Pages 599-608 ; 9780791848197 (ISBN) Khonsari, S. V ; England, G. L ; Shahsavar Gargari, M ; Parvinnia, M. H ; Sharif University of Technology
    A new beam-to-column joint with high rotational as well as shear deformation capacity was devised. This high rotational 'capacity' is required to fulfill the great 'demand' for rotation arising during earthquakes, severe waves and current loads, etc. Due to its ability to contain damage during an overload, it leaves the connected elements intact. This, together with its replaceability can reduce the cost of post-event repair substantially. Its bending as well as shear performance under "monotonie" loading had already been assessed experimentally (OMAE'02-28864, OMAE'03-37292, OMAE'04-51494 & OMAE'05-6736l) and proved well superior to that of conventional joints. In order to study its... 

    Texture evolution of AA3003 aluminum alloy sheet produced by accumulative roll bonding

    , Article Materials Science and Engineering A ; Volume 492, Issue 1-2 , 2008 , Pages 110-117 ; 09215093 (ISSN) Pirgazi, H ; Akbarzadeh, A ; Petrov, R ; Sidor, J ; Kestens, L ; Sharif University of Technology
    The accumulative roll bonding process was carried out on an AA3003 aluminum alloy sheet up to eight cycles. The electron backscattering diffraction (EBSD) method was employed to investigate the microtextural development in the ARB processed sheets. The results indicate that with increasing the number of cycles, the overall texture intensity increases even up to the eighth rolling pass and a strong texture develops. The main textural components are the copper and Dillamore components of which the intensities increase with increasing number of cycles. Measurement of microhardness and lamellar spacing of grains in the processed sheets revealed that the presence of second phase particles in this... 

    Effects of conventional and severe shot peening on residual stress and fatigue strength of steel aisi 1060 and residual stress relaxation due to fatigue loading: experimental and numerical simulation

    , Article Metals and Materials International ; Volume 27, Issue 8 , 2021 , Pages 2575-2591 ; 15989623 (ISSN) Maleki, E ; Farrahi, G. H ; Reza Kashyzadeh, K ; Unal, O ; Gugaliano, M ; Bagherifard, S ; Sharif University of Technology
    Korean Institute of Metals and Materials  2021
    Abstract: This study investigates and compares the effects of different shot peening treatments including conventional and severe shot peening on microstructure, mechanical properties, fatigue behavior, and residual stress relaxation of AISI 1060 steel. Shot peening treatments were applied with two Almen intensities of 17 and 21 A and a wide ranges of coverage (100%–1500%). Various microstructural observations were carried out to analyze the evolution of microstructure. Microhardness, residual stress and surface roughness measurements and also axial fatigue test were performed. Moreover, the extent of the residual stress relaxation during cyclic loading was investigated by means of XRD... 

    Glassy carbon electrode modified with a bilayer of multi-walled carbon nanotube and polypyrrole doped with new coccine: Application to the sensitive electrochemical determination of Sumatriptan

    , Article Electrochimica Acta ; Volume 56, Issue 27 , November , 2011 , Pages 10032-10038 ; 00134686 (ISSN) Shahrokhian, S ; Kamalzadeh, Z ; Saberi, R. S ; Sharif University of Technology
    A promising electrochemical sensor was developed based on a layer by layer process by electro-polymerization of pyrrole in the presence of new coccine (NC) as dopant anion on the surface of the multi-walled carbon nanotubes (MWCNTs) pre-coated glassy carbon electrode (GCE). The modified electrode was used as a new and sensitive electrochemical sensor for voltammetric determination of sumatriptan (SUM). The electrochemical behavior of SUM was investigated on the surface of the modified electrode using linear sweep voltammetry (LSV). The results showed a remarkable increase (∼12 times) in the anodic peak current of SUM in comparison to the bare GCE. The effect of experimental variables such... 

    Evaluation of dynamic properties of a calcite cemented gravely sand

    , Article Geotechnical Earthquake Engineering and Soil Dynamics IV Congress 2008 - Geotechnical Earthquake Engineering and Soil Dynamics, Sacramento, CA, 18 May 2008 through 22 May 2008 ; Issue 181 , 2008 ; 08950563 (ISSN); 9780784409756 (ISBN) Haeri, S. M ; Shakeri, M. R ; Shahcheraghi, S. A ; Sharif University of Technology
    Understanding of the effect of cementation on dynamic behaviour of cemented soil in an earthquake prone area could be crucial for earthquake resistance design. The major section of the city of Tehran has been developed on cemented coarse-grained alluvium. In order to understand the dynamic behaviour of this soil, a series of undrained cyclic triaxial tests were performed on uncemented and artificially calcite-cemented samples. In this paper, two dynamic parameters including dynamic shear modulus and damping ratio based on different definitions are investigated. In this regard the effects of cement content, confining pressure and cyclic deviatoric stress were studied as well. In general by... 

    Electrochemical determination of l-dopa in the presence of ascorbic acid on the surface of the glassy carbon electrode modified by a bilayer of multi-walled carbon nanotube and poly-pyrrole doped with tiron

    , Article Journal of Electroanalytical Chemistry ; Volume 636, Issue 1-2 , 2009 , Pages 40-46 ; 15726657 (ISSN) Shahrokhian, S ; Asadian, E ; Sharif University of Technology
    Elsevier  2009
    There are high attractions in the development of conducting polymer (CP) coatings to improve the electrochemical properties and biocompatibility of electrodes in the area of biosensors. A new type of the modified electrodes is prepared in a layer-by-layer process by using multi-walled carbon nanotube (MWCNT) and poly-pyrrole. In this procedure, the glassy carbon electrode is casted by a drop suspension of MWCNT, which leads to form a thin film of nanotube on its surface. In the second step, electrochemical polymerization of pyrrole in the presence of tiron (used as doping anion) is performed on the surface of the MWCNT pre-coated electrode. The modification procedure led to fabrication of a...