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    Design, analysis, and experimental evaluation of a novel three-fingered endoscopic large-organ grasper

    , Article Journal of Medical Devices, Transactions of the ASME ; Volume 7, Issue 2 , 2013 ; 19326181 (ISSN) Mirbagheri, A ; Farahmand, F ; Sharif University of Technology
    The currently available laparoscopic instruments are unable to manipulate and grasp the large intra-abdominal organs, such as spleen and kidney, with sufficient stability and safety. This paper describes a novel three-fingered endoscopic instrument, based on parallelogram mechanism, which can fully constrain the large organs and provide an effective grasping function. We first evaluated the efficacy of the design using a 3D model and finite element analysis. Then, a fully functional prototype was fabricated for experimental evaluations, including force propagation and pull force limitation characteristics. Finally, the instrument's capability for effective grasping was investigated on animal... 

    Estimation of modulus of elasticity for closed-cell aluminum foam

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 3, Issue PARTS A, B, AND C , 2012 , Pages 1285-1289 ; 9780791845196 (ISBN) Ahmadian, M. T ; Gobal, A ; Alkhani, R ; Sharif University of Technology
    Monodisperse closed cell aluminum foam was analyzed numerically to determine the relationship between its elastic modulus, porosity and pore diameter. It was found a nonlinear relationship exists between porosity, pore diameter and modulus of elasticity. In this regard, an empirical equation is developed and implemented for the prediction of modulus of elasticity versus porosity and pore diameter. Comparing experimental and analytical approaches by other researchers with those obtained in this research shows agreement exists within 1 to 3 percent  

    An age index for vascular system based on photoplethysmogram pulse contour analysis

    , Article IFMBE Proceedings ; Volume 21 IFMBE, Issue 1 , 2008 , Pages 125-128 ; 16800737 (ISSN); 9783540691389 (ISBN) Chellappan, K ; Mohd Ali, M. A ; Zahedi, E ; Sharif University of Technology
    Springer Verlag  2008
    An approach based pulse on contour analysis is proposed for the development of an aging index for the vascular system. The approach is non-invasive, using photoplethysmography (PPG), which is in wide clinical use. A probe is applied to the subject's finger-tip to provide a measure of the pulse waveform. The measured waveforms are filtered, digitized and post-processed. Individual pulses are extracted and the best pulse was selected by using the best pulse selection algorithm. Pulse contour analysis is then performed with specially formulated PPG fitness equation. Results of measurements taken from 72 subjects are reported. The age range of the subjects was from 19 to 68 years, all of them... 

    Development of empirical equations for prediction of modulus of elasticity for monodisperse metallic foams

    , Article Scientia Iranica ; Vol. 21, issue. 6 , 2014 ; ISSN: 10263098 Ahmadian, M. T ; Alkhani, R ; Gobal, A ; Sharif University of Technology
    Metallic foams are a class of lightweight materials that show high potentials for different industrial applications such as automotive and aerospace engineering. However, many factors have prevented metallic foams from being fully utilized in industrial applications. One main factor is that the influences of the porous structure on the mechanical properties of metallic foams are not well known yet. In this paper, a finite element model was used to analyze monodisperse closed cell aluminum foam in order to determine the relationship between its elastic modulus, porosity and pore diameter. A nonlinear relationship was found between the foams porosity, pore diameter and modulus of elasticity.... 

    Highly sensitive turn-on fluorescent detection of captopril based on energy transfer between fluorescein isothiocyanate and gold nanoparticles

    , Article Journal of Luminescence ; Volume 134 , 2013 , Pages 874-879 ; 00222313 (ISSN) Hormozi Nezhad, M. R ; Bagheri, H ; Bohloul, A ; Taheri, N ; Robatjazi, H ; Sharif University of Technology
    A novel approach for highly sensitive detection of captopril was developed based on the fluorescence resonance energy transfer (FRET) between gold nanoparticles (Au NPs) and fluorescein isothiocyanate (FITC), in which FITC acts as the donor and Au NPs as the acceptor. The fluorescence intensity of fluorescein isothiocyanate (FITC) was strictly quenched as a result of noncovalently adsorbed on Au NPs. Upon the addition of captopril, the fluorescence intensity of FITC turn-on due to the competition between captopril and FITC towards the surface of Au NPs. Under the optimum conditions, the fluorescence intensity of the released FITC displays a linear relationship in the range of 20 μg L-1 to... 

    The evaluation of transmutation of hazardous nuclear waste of 90Sr, into valuable nuclear medicine of 89Sr by ultraintense lasers

    , Article Laser and Particle Beams ; Volume 28, Issue 2 , 2010 , Pages 269-276 ; 02630346 (ISSN) Sadighi, S. K ; Sadighi Bonabi, R ; Sharif University of Technology
    The analytical evaluation of the capability of Bremsstrahlung highly directional energetic γ-beam to induce photo transmutation of 90Sr (γ,n) 89Sr is presented. Photo transmutation of hazardous nuclear waste of 90Sr, one of the two main sources of heat and radioactivity in spent fuel into valuable nuclear medicine radioisotope of 89Sr is explained. Based on the calculations, a fairly decent fraction of gamma rays in this range are used in transmuting of 90Sr into 89Sr where according to the available experimental data it is shown that by irradiating a 1-cm thick 90Sr sample with lasers of intensity of 1021 W/cm2 and repletion rate of 100Hz for an hour, the reaction activity would be 1.45... 

    Unidirectional transport of water through an asymmetrically charged rotating carbon nanotube

    , Article Journal of Physical Chemistry C ; Volume 121, Issue 42 , 2017 , Pages 23649-23658 ; 19327447 (ISSN) Khodabakhshi, M ; Moosavi, A ; Sharif University of Technology
    Achieving a high speed, unidirectional water flow through carbon nanotubes (CNTs) is a key factor in designing novel nanofluidic devices. In this study, utilizing molecular dynamics (MD) simulations, we propose a novel nanoscale water pump for directed water transportation using charged rotating CNTs. Two basic conditions for stable water flow, including thermodynamic nonequilibrium and spatial asymmetry, are provided by introducing partial charges on carbon atoms of the channel with asymmetric patterns and its rotation, respectively. We demonstrate that the performance of the water pump is proportional to the gradient of a linear charge distribution and angular velocity of the rotation. Our... 

    Development of a paper-based plasmonic test strip for visual detection of methiocarb insecticide

    , Article IEEE Sensors Journal ; Volume 17, Issue 18 , 2017 , Pages 6044-6049 ; 1530437X (ISSN) Mohammadi, A ; Ghasemi, F ; Hormozi Nezhad, M. R ; Sharif University of Technology
    This paper describes a simple and low-cost test strip for on-site monitoring of methiocarb insecticide. Hydrophilic filter paper soaked in agarose solution was bounded by hydrophobic solid wax and then was coated with unmodified gold nanoparticles (AuNPs). AuNPs aggregation caused by methiocarb served as colorimetric response. We demonstrated detection capability of methiocarb both in solution- and substrate-based sensor. A good linear relationship was obtained between the colorimetric response and the concentration of methiocarb ranging from 20 to 80 ng mL -1 with a limit of detection of 5 ng mL -1. Excellent selectivity toward methiocarb was observed among various pesticides and cationic... 

    Metallurgical and mechanical properties of underwater friction stir welds of Al7075 aluminum alloy

    , Article Journal of Materials Processing Technology ; Volume 262 , 2018 , Pages 239-256 ; 09240136 (ISSN) Rouzbehani, R ; Kokabi, A. H ; Sabet, H ; Paidar, M ; Ojo, O. O ; Sharif University of Technology
    Elsevier Ltd  2018
    Travel speeds between 25–300 mm/min and tool rotational speeds of 800 and 1250 rpm were employed for this study. The microstructure, mechanical properties and fracture surfaces of the joints were studied. Underwater environment and an increase in travel speed significantly increase the precipitates’ volume fraction, reduce the average grain and precipitate sizes of the weld nugget zones. A critical travel speed of 150 mm/min is attained in underwater welds beyond which the average grain sizes remain relatively the same. Average grain and precipitate sizes have linear relationships with the tool rotational and travel speed ratio. Optimum weld strengths of 396 and 360 MPa were obtained in the... 

    Functional brain networks in parkinson's disease

    , Article 24th Iranian Conference on Biomedical Engineering and 2017 2nd International Iranian Conference on Biomedical Engineering, ICBME 2017, 30 November 2017 through 1 December 2017 ; 2018 ; 9781538636091 (ISBN) Akbari, S ; Fatemizadeh, E ; Reza Deevband, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Parkinson's disease (PD) is the second most common and progressive neurological disorder. Parkinson's signs are caused by dysfunction in PD patient's brain network. Newly, resting state functional magnetic resonance imaging has been utilized to assess the altered functional connectivity in PD patients. In this study, we investigated the properties of the brain network topology in 19 PD patients compared to 17 normal healthy group by means of graph theory. In addition, we used four different graph formation methods to explore linear and nonlinear relationships between fMRI signals. Each correlation measure created a weighted graph for each subject. Different graph characteristics have been... 

    A temperature-calibrated continuum model for vibrational analysis of the fullerene family using molecular dynamics simulations

    , Article Applied Mathematical Modelling ; Volume 80 , April , 2020 , Pages 115-125 Nejat Pishkenari, H ; Golzari, A ; Sharif University of Technology
    Elsevier Inc  2020
    In the present study, a model was proposed to determine the elastic properties of the family of fullerenes at different temperatures (between 300 and 2000 K) using a combination of molecular dynamics simulation and continuum shell theory. The fullerenes molecules examined here are eight spherical fullerenes, including C60, C80, C180, C240, C260, C320, C500, and C720. First, the breathing mode frequency and the radius of gyration of the molecules were obtained at different temperatures by molecular dynamics simulations using AIREBO potential. Then, these data were used in a continuum model to obtain the elastic coefficients of these closed clusters of carbon in terms of temperature changes.... 

    Thermo-mechanical analysis of cold extrusion process using stream function and finite element methods

    , Article Multidiscipline Modeling in Materials and Structures ; Volume 9, Issue 1 , 2013 , Pages 128-139 ; 15736105 (ISSN) Hosseinabadi, H. G ; Serajzadeh, S ; Sharif University of Technology
    Purpose - The purpose of this paper is to propose a mathematical model to estimate required energy and temperature distribution during cold extrusion process. Design/methodology/approach - An admissible velocity field is generated based on stream function technique. Then, the required energy and the temperature distributions in the metal and the extrusion die are determined by a coupled upper bound-finite element analysis. Findings - To examine the proposed model, cold extrusion of AA6061-10%SiCp is considered and the predicted extrusion force-displacement diagrams in different reductions are compared with the experimental ones and reasonable agreement is observed. Furthermore, it... 

    Experimental study of some important factors on nonwetting phase recovery by cocurrent spontaneous imbibition

    , Article Journal of Natural Gas Science and Engineering ; 2015 ; 18755100 (ISSN) Hamidpour, E ; Mirzaei Paiaman, A ; Masihi, M ; Harimi, B ; Sharif University of Technology
    Elsevier  2015
    Spontaneous imbibition, defined as the displacement of nonwetting phase by wetting phase in porous media by action of capillary forces, is important in many applications within earth sciences and in particular in naturally fractured oil and gas reservoirs. Hence, it is critical to investigate the various aspects of this process to correctly model the fractured reservoir behavior. In this study, twenty four experiments were conducted to study the effect of rock properties, lithology of porous medium, brine viscosity and boundary conditions on displacement rate and final recovery by cocurrent spontaneous imbibition (COCSI) in brine-oil systems. The results can be extended to brine-gas systems,... 

    Fracture behavior dependence on load-bearing capacity of filler in nano- and microcomposites of polypropylene containing calcium carbonate

    , Article Materials and Design ; Volume 31, Issue 2 , 2010 , Pages 802-807 ; 02641275 (ISSN) Afshar, A ; Massoumi, I ; Khosh, R. L ; Bagheri, R ; Sharif University of Technology
    The fracture toughness and deformation mechanism of PP/CaCO3 (15 wt.%) composites were studied and related to load-bearing capacity of the particles. To alter the load-bearing capacity of the particles, different particle sizes (0.07-7 μm) with or without stearic acid coating were incorporated. The fracture toughness of the composites was determined using J-Integral method and the deformation mechanism was studied by transmission optical microscopy of the crack tip damage zone. It was observed that the load-bearing capacity of the particles decreased by reduction of particle size and application of coating. A linear relationship between normalized fracture toughness and inverse of... 

    On the strain inhomogeneity in drawn copper wires

    , Article International Journal of Material Forming ; Volume 3, Issue 1 , 2010 , Pages 59-64 ; 19606206 (ISSN) Hasani, G. H ; Mahmudi, R ; Karimi Taheri, A ; Sharif University of Technology
    Three different wire drawing schedules were attempted to examine the effects of reduction of area, die-angle and friction coefficient on the strain inhomogeneity of drawn copper wires. The microhardness distribution was studied over the transverse and longitudinal cross-sections. Inhomogeneity factor (I. F.) curves; I. F. = f(r), I. F. = g(2α) and I. F. = h(μ) were determined from the measurements. The results indicate that less strain inhomogeneity is achieved in drawing wires through dies with low angle, low friction coefficient and high reduction of area. Despite the variation in reduction of area and die-angle, the strain was distributed evenly at the center of the drawn wires. Contrary... 

    Investigation of CFS shear walls with one and two-sided steel sheeting

    , Article Journal of Constructional Steel Research ; Volume 122 , 2016 , Pages 292-307 ; 0143974X (ISSN) Attari, N. K. A ; Alizadeh, S ; Hadidi, S ; Sharif University of Technology
    Elsevier Ltd  2016
    In this study six Cold-Formed Steel shear wall (CFS) with one and two side steel sheeting are tested under reversed cyclic loading. Besides, thirteen numerical models are simulated, using nonlinear finite element method, and analyzed under monotonic pushover loading. The studied parameters are the comparison of one and two side steel sheeting, the nominal thickness of steel sheet and boundary elements, and height to width aspect ratios of the wall. The performance of tested specimens is investigated in terms of lateral load-story drift response, failure modes and ultimate strength of shear walls. Based on AISI S213 the available strength of two-sided steel-sheathed walls is cumulative but... 

    Prognostics of rolling element bearings with the combination of Paris law and reliability method

    , Article 2017 Prognostics and System Health Management Conference, PHM-Harbin 2017 - Proceedings, 9 July 2017 through 12 July 2017 ; 2017 ; 9781538603703 (ISBN) Behzad, M ; Addin Arghan, H ; Rohani Bastami, A ; Sharif University of Technology
    In this research, a combination of the physical model based on Paris law and probability method is proposed for remaining useful life prediction of rolling element bearings. Level crossing is used as a feature that represents a linear relationship with defect size. Considering this linear relationship and using Paris law, a new model has been developed for bearings that follow degradation pattern with two stages. In this pattern, a bearing starts working in the healthy condition. Then it starts slow degradation stage and finally it goes to fast degradation stage until it reaches to the failure threshold. Considering a normal distribution for transition point from the slow degradation to the... 

    Ionic liquid based on 6-amino-6-deoxy hexopyranose cation and BF4 ¯, PF6 ¯, and ClO4 ¯ as anions: a DFT study on the structural and electronic properties

    , Article Journal of Physical Organic Chemistry ; Volume 31, Issue 5 , 2018 ; 08943230 (ISSN) Kheirjou, S ; Fattahi, A ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    In this study, the structural and electronic properties of a carbohydrate-based (6-amino-6-deoxy hexopyranose [ADHP]) ionic liquid were explored. The interactions among 3 anions (BF4 ¯, PF6 ¯, and ClO4 ¯) and ADHP as cation were investigated at B3LYP/6-311++G(d,p) level. Based on the calculated interaction energy, it was found that PF6 ¯ anion has the highest interaction energy with ADHP. It was found that the hydrogen bonds play an important role in the interaction of ion pairs. The nature of hydrogen bonds in the optimized ion pars was analyzed by using natural bond orbital analysis and the quantum theory of atoms in molecules. The linear relationship between electron density at the bond... 

    Chemiluminometric fingerprints for identification of plasmonic nanoparticles

    , Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 209 , 2019 , Pages 85-94 ; 13861425 (ISSN) Shahrajabian, M ; Hormozi Nezhad, M. R ; Sharif University of Technology
    Elsevier B.V  2019
    Development of a convenient and inexpensive method for identification and detection of nanoparticles (NPs) is of great interest. In this work, we have developed a novel and simple chemiluminescence based sensor array, with its sensing mechanism mimicking that of olfactory and gustatory systems for discriminating a set of NPs. The proposed method is based on the enhancement effect of NPs on luminol–oxidant CL intensity by their catalytic effect. Three kinds of oxidant including H2O2, AgNO3, and K3Fe(CN)6 were used as sensor elements and NPs exhibited diverse enhancing responses to different oxidant-luminol CL systems producing unique response patterns that were identified through heat map and... 

    fMRI functional connectivity analysis via kernel graph in Alzheimer’s disease

    , Article Signal, Image and Video Processing ; 2020 Ahmadi, H ; Fatemizadeh, E ; Motie-Nasrabadi, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2020
    Functional magnetic resonance imaging (fMRI) is an imaging tool that is used to analyze the brain’s functions. Brain functional connectivity analysis based on fMRI signals often calculated correlations among time series in different areas of the brain. For FC analysis most prior research works generate the brain graphs based on linear correlations, however, the nonlinear behavior of the brain can lower the accuracy of such graphs. Usually, the Pearson correlation coefficient is used which has limitations in revealing nonlinear relationships. One of the proper methods for nonlinear analysis is the Kernel trick. This method maps the data into a high dimensional space and calculates the linear...