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    Laboratory performance of stone mastic asphalt mixtures

    , Article Amirkabir (Journal of Science and Technology) ; Volume 13, Issue 49 , December , 2002 , Pages 24-35 ; ISSN: 10150951 Tabatabaee, N ; Alasti, M ; Sharif University of Technology
    Abstract
    Researchers and practicing engineers have come to this realization that different mixtures should be used for different climate and traffic conditions. Rutting is one of the main performance related types of distress in areas where the asphalt pavement is subjected to heavy axle loads and high temperature. In this research various types of SMA mixtures were tested to evaluate their effectiveness for inhibiting rutting. The variables in the laboratory tests were aggregate gradation  

    Laboratory performance of stone mastic asphalt mixtures

    , Article Amirkabir (Journal of Science and Technology) ; Volume 13, Issue 49 , 2002 , Pages 24-35 ; 10150951 (ISSN) Tabatabaee, N ; Alasti, M ; Sharif University of Technology
    2002
    Abstract
    Researchers and practicing engineers have come to this realization that different mixtures should be used for different climate and traffic conditions. Rutting is one of the main performance related types of distress in areas where the asphalt pavement is subjected to heavy axle loads and high temperature. In this research various types of SMA mixtures were tested to evaluate their effectiveness for inhibiting rutting. The variables in the laboratory tests were aggregate gradation, nominal maximum aggregate size, asphalt binder content, and the type of binder thickener. Two types of asphalt binder thickener, namely mineral fiber and crumb rubber were used. The results of this investigation... 

    Robust shape control of two SMA actuators attached to a flexible beam based on DK iteration

    , Article International Conference on Control, Automation and Systems ; 2012 , Pages 316-321 ; 15987833 (ISSN) ; 9781467322478 (ISBN) Alambeigi, F ; Zamani, A ; Vossoughi, G ; Zakerzadeh, M. R ; Sharif University of Technology
    2012
    Abstract
    There has been great demand for shape memory alloy (SMA) wires as actuators for shape control of flexible structures. The experimental setup of this study consists of a flexible beam actuated by two active SMA actuators. The input applied to the SMA actuator in this setup is electrical current while the output is the strain or position. To control strain of the actuator, the SMA wire is heated resistively in order to reach the desired temperature calculated by inverse of the phenomenological model. In heating the SMA wire resistively, the controllable quantity is the heat input to the wire via an applied current. In controller design, changes of physical properties of SMA wires and the... 

    An analytical study on the bending of prismatic SMA beams

    , Article Smart Materials and Structures ; Volume 24, Issue 12 , 2015 ; 09641726 (ISSN) Ostadrahimi, A ; Arghavani, J ; Poorasadion, S ; Sharif University of Technology
    Institute of Physics Publishing  2015
    Abstract
    In this study, an analytical solution is presented for pure bending of shape memory alloy (SMA) beams with symmetric cross section as well as symmetric behavior in tension and compression. To this end, a three-dimensional constitutive equation is reduced to one-dimensional form and employed to study the bending response of SMA beams at high (pseudo-elasticity) and low (shape memory effect) temperatures. An analytical expression for bending stress as well as polynomial approximation for shear stress and deflection are obtained. Derived equations for bending are employed to analyze an SMA beam with rectangular cross section and results are compared with those of the finite element method. The... 

    Development of a new mechanism to change velocity in a helical swimmer robot at low Reynolds number

    , Article Scientia Iranica ; Volume 25, Issue 5B , 2018 , Pages 2616-2627 ; 10263098 (ISSN) Sayyaadi, H ; Bahmanyar, Sh ; Sharif University of Technology
    Sharif University of Technology  2018
    Abstract
    This paper presents a new mechanism with unique and prominent features for a helical swimmer robot. "Double Helices Propulsion Mechanism" consists of two parallel helices with a single axis rotating in the same direction. The outer helix acts as the main propulsion component, and the inner helix, which is made of a Shape Memory Alloy (SMA), controls the forward velocity during swimming. This mechanism, by varying the geometrical parameters of its helical tail, can change the forward velocity of the helical swimmer robot that is required by its predefined missions. In order to study the effects of geometric parameters on the forward velocity in the single helical swimmer, a hydrodynamic model... 

    Analytical modeling of a Minimally Invasive Surgery grasper actuated by shape memory alloy wires

    , Article International Conference on Robotics and Mechatronics, ICRoM 2013 ; Feb , 2013 , Pages 147-151 ; 9781467358118 (ISBN) Shahriari, M ; Zabihollah, A ; Sharif University of Technology
    2013
    Abstract
    Minimally Invasive Surgery (MIS) is getting common these days. MIS robots using special tools can perform surgery precisely as humans. This is only possible with dexterous end-effectors and a well-controlled system. Local, lightweight and powerful actuators positioned at end-effectors provide the ability to decrease the degrees of freedom and simplify the design. This paper discusses a grasper design actuated by Shape Memory Alloy (SMA) wires that can be used in MIS robotics. The properties of a commercially available shape memory alloy are explored and analytical formulations for the actuation procedure are developed. The grasper actuated by SMA wires is studied and the procedure of... 

    Compact broadband printed monopole antenna

    , Article Applied Computational Electromagnetics Society Journal ; Volume 28, Issue 4 , 2013 , Pages 321-326 ; 10544887 (ISSN) Jafargholi, A ; Jafargholi, A ; Sharif University of Technology
    2013
    Abstract
    A compact printed monopole antenna for broadband application is presented. The proposed antenna, having a total physical size of 21 × 6.5 mm consists of a patch fed by a coaxial line and an SMA connector as partial finite ground plane. The modified patch plane with a slot in its feed point helps to increase the impedance bandwidth of the proposed antenna. The optimal design may offer an ultra-wide impedance bandwidth from 2.56 GHz to 20 GHz. A prototype is fabricated and tested. The agreement between the simulated and measured results is quite good  

    A comparative analysis of some one-dimensional shape memory alloy constitutive models based on experimental tests

    , Article Scientia Iranica ; Volume 19, Issue 2 , Volume 19, Issue 2 , 2012 , Pages 249-257 ; 10263098 (ISSN) Sayyaadi, H ; Zakerzadeh, M. R ; Salehi, H ; Sharif University of Technology
    2012
    Abstract
    Recently, Shape Memory Alloys (SMAs) have been receiving more attention and further study, due to their ability to develop extremely large, recoverable strains and great forces. In this paper, three major models of SMA behavior, used in the literature, for studying the static performance of SMA components attributed to Tanaka, Liang and Rogers, and Brinson, have been analyzed and compared. The major differences and similarities between these models have also been emphasized and presented in this paper, based on the experimental data of the shape memory and superelastic behavior of an SMA wire. It is shown that these models all agree well in their prediction of the superelastic behavior of... 

    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... 

    A novel preisach based neural network approach to hysteresis non-linearity modeling

    , Article Proceedings of the 2010 International Conference on Artificial Intelligence, ICAI 2010, 12 July 2010 through 15 July 2010, Las Vegas, NV ; Volume 1 , 2010 , Pages 299-305 ; 9781601321480 (ISBN) Firouzi, M ; Ghomi Rostami, M ; Bagheri Shouraki, S ; Iloukhani, M ; Sharif University of Technology
    2010
    Abstract
    In some systems with hysteresis behavior like Shape Memory Alloy (SMA) actuators and Piezo actuators, we essentially need an accurate modeling of hysteresis either for controller design or performance evaluation. One of the most interesting Hysteresis non-linearity identification methods is Preisach model in which hysteresis is modeled by linear combination of elemental operators. Despite good ability of Preisach modeling to extract main features of system with hysteresis behavior, cause of tough numerical nature of Preisach, it is not convenient to use in real-time control applications. In this paper we present a novel method based on Artificial Neural Network. For evaluation of proposed... 

    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... 

    Mechanism of reaction of molten NiTi with EBM graphite crucible

    , Article Materials Science and Technology ; Volume 25, Issue 6 , 2009 , Pages 699-706 ; 02670836 (ISSN) Sadrnezhaad, Kh ; Ahmadi, E ; Malekzadeh, M ; Sharif University of Technology
    2009
    Abstract
    Ultra clean NiTi shape memory alloy was produced by electron beam melting of Ni rich vacuum inductionally melted butts together with pure Ti chunks in both condensed and electrographite crucibles. A hollow cathode discharge gun was used for heating up to 1623, 1653 and 1693 K and holding the charge materials under vacuum for 300, 600, 900 and 1200 s. Effects of temperature, time and compactness of the crucible on formation/disappearance of the hard compounds like Ni3Ti, Ti4Ni2O, Ti4Ni 2C, Ti3Ni2OC and TiC were determined by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. A combination of the experimental results with the kinetic rate equations indicated... 

    Ingredient losses during melting binary Ni-Ti shape memory alloys

    , Article Journal of Materials Science and Technology ; Volume 21, Issue 4 , 2005 , Pages 484-488 ; 10050302 (ISSN) Sadrnezhaad, S. K ; Badakhshan Raz, S ; Sharif University of Technology
    2005
    Abstract
    Losses of the alloying elements during vacuum induction melting of the binary NiTi alloys were evaluated by visual observation and chemical analysis of the NiTi melted specimens and the scalp formed on the internal surface of the crucible. The results indicated that the major sources of the losses were (a) evaporation of the metals, (b) formation of the NiTi scalp and (c) the sprinkling drops splashed out of the melt due to the exothermic reactions occurring between Ni and Ti to form the NiTi parent phase. Quantitative evaluations were made for the metallic losses by holding the molten alloy for 0.5, 3, 5, 10 and 15 min at around 100°C above the melting point inside the crucible. Chemical... 

    Hysteresis identification of shape memory alloy actuators using a novel artificial neural network based Presiach model

    , Article ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2010, 28 September 2010 through 1 October 2010 ; Volume 1 , 2010 , Pages 653-660 ; 9780791844151 (ISBN) Zakerzadeh, M. R ; Firouzi, M ; Sayyaadi, H ; Bagheri Shouraki, S ; Sharif University of Technology
    Abstract
    In systems with hysteresis behavior like Shape Memory Alloy (SMA) actuators and Piezo actuators, an accurate modeling of hysteresis behavior either for performance evaluation and identification or controller design is essentially needed. One of the most interesting hysteresis none-linearity identification methods is Preisach model which the hysteresis is modeled by linear combination of hysteresis operators. In spite of good ability of the Preisach model to extract the main features of system with hysteresis behavior, due to its numerical nature, it is not convenient to use in real time control applications. In this paper a novel artificial neural network (ANN) approach based on the Preisach... 

    Colorimetric assay for exon 7 SMN1/SMN2 single nucleotide polymorphism using gold nanoprobes

    , Article BioImpacts ; Volume 3, Issue 4 , 2013 , Pages 185-194 ; 22285652 (ISSN) Ahmadpour Yazdi, H ; Hormozi Nezhad, M. R ; Abadi, A ; Sanati, M. H ; Kazemi, B ; Sharif University of Technology
    2013
    Abstract
    Introduction: Proximal spinal muscular atrophy (SMA) is one of the most significant neurodegenerative diseases amongst the autosomal-recessive genetic disorders which is caused by the absence of protein survival of motor neuron (SMN). A critical nucleotide difference in SMN2 compared to SMN1 gene leads to an inefficient protein. Hence, homozygous lack of SMN1 provides a progressive disease. Due to the high prevalence, up to now, several molecular diagnostic methods have been used which most of them are lengthy, expensive, and laborious. Methods: In the present study, we exploited a gold nanoprobe-based method for semi-quantitative SMN1 gene dosage analysis compared to SMN2. The assay was... 

    Pore control in SMA NiTi scaffolds via space holder usage

    , Article Materials Science and Engineering C ; Volume 32, Issue 5 , 2012 , Pages 1266-1270 ; 09284931 (ISSN) Ghasemi, A ; Hosseini, S. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    2012
    Abstract
    Porous NiTi shape memory alloy (SMA) was fabricated by sintering of compressed constituent elements pre-mixed with NaCl or urea spacer holders. Effect of spacer to metal volume-ratio (r S) on shape, size, distribution and openness of the voids was probed by optical metallography, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) was used to determine the SMA transformation temperatures. Controllable void geometry helping osteoblast proliferation and bone cell growth was gained by addition of the spacers. At r S = 0.7, percentage of the open pores reached 52% while at r S = 1.43, interconnected pores with 200 to 500 μm diameter were... 

    Property change during nanosecond pulse laser annealing of amorphous NiTi thin film

    , Article Bulletin of Materials Science ; Volume 35, Issue 3 , 2012 , Pages 357-364 ; 02504707 (ISSN) Sadrnezhaad, S. K ; Yasavol, N ; Ganjali, M ; Sanjabi, S ; Sharif University of Technology
    2012
    Abstract
    Nanosecond lasers of different intensities were pulsed into sputter-deposited amorphous thin films of near equiatomic Ni/Ti composition to produce partially crystallized highly sensitive R-phase spots surrounded by amorphous regions. Scanning electron microscopy having secondary and back-scattered electrons, field emission scanning electron microscopy, optical microscopy and X-ray diffraction patterns were used to characterize the laser treated spots. Effect of nanosecond pulse lasering on microstructure, morphology, thermal diffusion and inclusion formation was investigated. Increasing beam intensity and laser pulse-number promoted amorphous to R-phase transition. Lowering duration of the... 

    Hysteresis nonlinearity identification by using RBF neural network approach

    , Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010 ; 2010 , Pages 692-697 ; 9781424467600 (ISBN) Firouzi, M ; Bagheri Shouraki, S ; Zakerzadeh, M. R ; Sharif University of Technology
    Abstract
    In systems with hysteresis behavior like magnetic cores, Piezo actuators, Shape Memory Alloy(SMA), we essentially need an accurate modeling of hysteresis either for design or performance evaluation; also in some control applications accurate system identification is needed. One of the famous methods of Hysteresis modeling is Preisach model. In this numerical method hysteresis is modeled by linear combination of smaller hysteresis loops as an elemental operator and local memory. In this paper we discuss those Radial Base artificial neural networks (RBF) which provides natural settings in accordance with the Preisach model. It is shown that the proposed approach can represent hysteresis... 

    Numerical study of an innovative SMA based beam-column connection in reducing the seismic response of steel MRF structures

    , Article Scientia Iranica ; Volume 23, Issue 5 , 2016 , Pages 2033-2043 ; 10263098 (ISSN) Rofooei, F. R ; Yadegari Farzaneh, A ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    During recent years, Shape Memory Alloys (SMAs) have been effectively used to control the seismic response of structural systems. Recovering the residual strains upon unloading (super-elasticity) or by heating (shape memory effect) is the main characteristic of SMA materials. This paper explores the efficiency of a proposed application of steel & SMA bolts in improving the seismic behavior of connections in steel Moment Resisting Frame (MRF) structures. A new semi-rigid, end-plate, beam-column connection is introduced, which is based on parallel application of steel and austenite-phase SMA bolts. A number of 3-D steel MRF structural models with different numbers of stories and mass...