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    Manipulation of the electric field of electrospinning system to produce polyacrylonitrile nanofiber yarn

    , Article Journal of the Textile Institute ; Volume 98, Issue 3 , 2007 , Pages 237-241 ; 00405000 (ISSN) Dabirian, F ; Hosseini, Y ; Hosseini Ravandi , S. A ; Sharif University of Technology
    2007
    Abstract
    Electrospinning is a process that produces nanofiber through the action of an external electric field imposed on a polymer solution or melt. This paper introduces a new system capable of producing continuous uniaxially aligned PAN nanofiber yarn by manipulating the electric field. The manipulation was carried out by employing a negative charged bar in the electric field of conventional electrospinning system, leading to the formation of an electrostatic multipolar field. As a result, the main stream was redirected towards a rotating take up unit, collecting the twisted yarn consisting of uniaxially aligned nanofibers. The yarns were then treated in boiling water under tension and their... 

    Simulation approach to investigate the effect of the jet structure and air pressure on the performance of siro-jet spinning

    , Article Fibres and Textiles in Eastern Europe ; Volume 92, Issue 3 , 2012 , Pages 46-50 ; 12303666 (ISSN) Hasani, H ; Hasani, M ; Sharif University of Technology
    2012
    Abstract
    In this paper, the effects of different parameters on the hairiness of siro-jet spun yarns, such as the nozzle pressure, the distance between the front roller nip and inlet of the nozzle, and jet structure were investigated. Using the Taguchi method, it was concluded that the factor air pressure has the strongest effect and the factor distance between the front roller nip and inlet of the nozzle does not have a significant effect on the performance of the siro-jet spinning system in reducing yarn hairiness. A computational fluid dynamics model was developed to simulate the airflow pattern inside the jets. The effect of air pressure and the jet structure was simulated using Fluent 6.3... 

    Designing a MapReduce performance model in distributed heterogeneous platforms based on benchmarking approach

    , Article Journal of Supercomputing ; Volume 76, Issue 9 , 2020 , Pages 7177-7203 Gandomi, A ; Movaghar, A ; Reshadi, M ; Khademzadeh, A ; Sharif University of Technology
    Springer  2020
    Abstract
    MapReduce framework is an effective method for big data parallel processing. Enhancing the performance of MapReduce clusters, along with reducing their job execution time, is a fundamental challenge to this approach. In fact, one is faced with two challenges here: how to maximize the execution overlap between jobs and how to create an optimum job scheduling. Accordingly, one of the most critical challenges to achieving these goals is developing a precise model to estimate the job execution time due to the large number and high volume of the submitted jobs, limited consumable resources, and the need for proper Hadoop configuration. This paper presents a model based on MapReduce phases for... 

    Enhancing Seebeck coefficient and electrical conductivity of polyaniline/carbon nanotube–coated thermoelectric fabric

    , Article Journal of Industrial Textiles ; Volume 51, Issue 2_suppl , 2022 , Pages 3297S-3308S ; 15280837 (ISSN) Amirabad, R ; Ramazani Saadatabadi, A ; Pourjahanbakhsh, M ; Siadati, M. H ; Sharif University of Technology
    SAGE Publications Ltd  2022
    Abstract
    In this work, flexible thermoelectric fabrics, polyester/yarn fabrics coated with polyaniline/carbon nanotube (PANI/CNT) nanocomposite, were fabricated by sequential processing: (I) polyaniline/carbon nanotube nanocomposites preparation by a one-step in-situ polymerization and (II) dip coating of a mixture solution of CNT-doped PANI on a polyester/yarn fabric. Nanocomposites were synthesized with various CNT content (0.5, 2.5, 5, and 10 wt%) and characterized using different methods. The Seebeck coefficient and electrical conductivity measurements were used to determine their thermoelectric properties. The results revealed significant improvement in both electrical conductivity and the... 

    Anomaly in current distribution of multiwall carbon nanotube bundles at high frequencies

    , Article 14th IEEE International Conference on Nanotechnology, IEEE-NANO 2014 ; 2014 , pp. 702-705 ; ISBN: 9781479956227 Farahani, E. K ; Sarvari, R ; Sharif University of Technology
    Abstract
    In this paper, for the first time, current distribution inside multiwall carbon nanotube (MWCNT) bundles is studied in the high frequency range in which resistance becomes saturated. It is shown that current distribution of MWCNT bundles in this range is not strictly decreasing vs. distance from surface as in Cu wires  

    A front-end tool for automated abstraction and modular verification of actor-based models

    , Article Proceedings - Fourth International Conference on Application of Concurrency to System Design, ACSD 2004, Hamilton, Ont., 16 June 2004 through 18 June 2004 ; 2004 , Pages 145-148 ; 0769520774 (ISBN); 9780769520773 (ISBN) Sirjani, M ; Shali, A ; Jaghoori, M. M ; Iravanchi, H ; Movaghar, A ; Sharif University of Technology
    2004
    Abstract
    Actor-based modeling is known to be an appropriate approach for representing concurrent and distributed systems. Rebeca is an actor-based language with a formal foundation, based on an operational interpretation of the actor model. We develop a front-end tool for translating a subset of Rebeca to SMV in order to model check Rebeca models. Automated modular verification and abstraction techniques are supported by the tool  

    Thermo acoustic study of carbon nanotubes in near and far field: Theory, simulation, and experiment

    , Article Journal of Applied Physics ; Volume 117, Issue 9 , 2015 ; 00218979 (ISSN) Asadzadeh, S. S ; Moosavi, A ; Huynh, C ; Saleki, O ; Sharif University of Technology
    American Institute of Physics Inc  2015
    Abstract
    Carbon nanotube webs exhibit interesting properties when used as thermo-acoustic projectors. This work studies thermo-acoustic effect of these sound sources both in near and far field regions. Based on two alternative forms of the energy equation, we have developed a straightforward formula for calculation of pressure field, which is consistent with experimental data in far field. Also we have solved full 3-D governing equations using numerical methods. Our three-dimensional simulation and experimental data show pressure waves are highly affected by dimensions of sound sources in near field due to interference effects. However, generation of sound waves in far field is independent of... 

    Pervaporation of toluene and iso-octane through poly(vinyl alcohol)/graphene oxide nanoplate mixed matrix membranes: Comparison of crosslinked and noncrosslinked membranes

    , Article Journal of Applied Polymer Science ; Volume 135, Issue 7 , 2018 ; 00218995 (ISSN) Khazaei, A ; Mohebbi, V ; Behbahani, R. M ; Ramazani S. A., A ; Sharif University of Technology
    John Wiley and Sons Inc  2018
    Abstract
    Removal of aromatic compounds from fuel is an essential requirement in new environmental policies. In the present study, poly(vinyl alcohol)/graphene oxide (GO) mixed matrix membranes were prepared and applied to the separation of toluene from iso-octane by pervaporation, considering the similarity and interaction between graphene and aromatics. The effects of crosslinking and GO content on separation efficiency have been investigated in detail. Owing to the high affinity of GO with toluene through s and π bonds, the selectivity of the membranes was increased by incorporating a low amount of GO. The results also indicated that noncrosslinked membranes have higher selectivity and permeation... 

    Enhancing seebeck coefficient and electrical conductivity of polyaniline/carbon nanotube–coated thermoelectric fabric

    , Article Journal of Industrial Textiles ; 2021 ; 15280837 (ISSN) Amirabad, R ; Ramazani Saadatabadi, A ; Pourjahanbakhsh, M ; Siadati, M. H ; Sharif University of Technology
    SAGE Publications Ltd  2021
    Abstract
    In this work, flexible thermoelectric fabrics, polyester/yarn fabrics coated with polyaniline/carbon nanotube (PANI/CNT) nanocomposite, were fabricated by sequential processing: (I) polyaniline/carbon nanotube nanocomposites preparation by a one-step in-situ polymerization and (II) dip coating of a mixture solution of CNT-doped PANI on a polyester/yarn fabric. Nanocomposites were synthesized with various CNT content (0.5, 2.5, 5, and 10 wt%) and characterized using different methods. The Seebeck coefficient and electrical conductivity measurements were used to determine their thermoelectric properties. The results revealed significant improvement in both electrical conductivity and the... 

    Hydro-purification of crude terephthalic acid using palladium catalyst supported on multi-wall carbon nanotubes

    , Article Journal of Industrial and Engineering Chemistry ; 2015 ; ISSN: 1226086X Tourani, S ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
    Abstract
    Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.% of palladium on activated carbon)... 

    Cytotoxicity of protein corona-graphene oxide nanoribbons on human epithelial cells

    , Article Applied Surface Science ; Volume 320 , 30 November , 2014 , Pages 596-601 ; ISSN: 01694332 Mbeh, D. A ; Akhavan, O ; Javanbakht, T ; Mahmoudi, M ; Yahia, L ; Sharif University of Technology
    Abstract
    Graphene oxide nanoribbons (GONRs) were synthesized using an oxidative unzipping of multi-walled carbon nanotubes. The interactions of the GONRs with various concentrations of fetal bovine serum or human plasma serum indicated that the GONRs were functionalized substantially by the albumin originated from the two different protein sources. Then, concentration-dependent cytotoxicity of the protein-functionalized GONRs on human epithelial cells was studied. Although the GONRs with concentrations ≤50 μg/mL did not exhibit significant cytotoxicity on the cells (with the cell viability >85%), the concentration of 100 μg/mL exhibited significant cytotoxicity including prevention of cell... 

    A seamless-pitched graphene nanoribbon field effect transistor

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 74 , November , 2015 , Pages 414-420 ; 13869477 (ISSN) Haji Nasiri, S ; Moravvej Farshi, M. K ; Faez, R ; Sharif University of Technology
    Elsevier  2015
    Abstract
    This paper proposes a graphene nanoribbon field effect transistor (GNRFET) consisting of pitched semiconducting GNRs as the channels that are connected to the metallic graphene source/drain in a seamless fashion. We obtained the diagrams for frequency bandwidths, step time responses, and Nyquist stability for the seamless pitched GNRFET (SP-GNRFET) with a channel having 100 pitched GNRs at 10 nm pitch in the common source configuration with various dimensions of the GNRs. The aforementioned diagrams were also obtained for the pitched carbon nanotube field effect transistor (CNTFET) with a channel having 100 pitched CNTs at 10 nm pitch in the common source configuration with various... 

    An experimental study on the effect of ultrasonication on thermal conductivity of ferrofluid loaded with carbon nanotubes

    , Article Thermochimica Acta ; Volume 617 , October , 2015 , Pages 102-110 ; 00406031 (ISSN) Shahsavar, A ; Salimpour, M. R ; Saghafian, M ; Shafii, M. B ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Nanofluids containing Fe3O4 and carbon nanotubes nanoparticles emulsified and dispersed using gum arabic (GA) and tetramethylammonium hydroxide (TMAH) were made and characterized for potential use as heat transfer fluids. Due to the interaction between the TMAH and GA molecules, the magnetic nanoparticles and CNTs were physically adsorbed. This paper reports an experimental work on the effect of ultrasonication on thermal conductivity of this aqueous suspension. The characterization and surface morphology of the dried samples were studied by using XRD and TEM measurements. Experiments were conducted in the magnetic nanoparticles mass concentration range 0.494-2.428%,... 

    Free vibrations and stability of high-speed rotating carbon nanotubes partially resting on Winkler foundations

    , Article Composite Structures ; Volume 126 , 2015 , Pages 52-61 ; 02638223 (ISSN) Torkaman Asadi, M. A ; Rahmanian, M ; Firouz-Abadi, R. D ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    In the present study, free vibrations and stability of rotating single walled carbon nanotubes (SWCNT) is investigated by nonlocal theory of elasticity; while the CNT is partially resting on an elastic foundation. The governing equations of motion are presented by using Love's shell assumptions. An exact series expansion method of solution is employed and very accurate results are obtained. Some parameter studies including the effects of rotating speed, foundation stiffness, slenderness ratio and nonlocal parameter on the natural frequency and stability margins of the current model are studied. The studies show that rotation rates and foundation elasticity can contribute significantly in the... 

    Application of electrostatically actuated carbon nanotubes in nanofluidic and bio-nanofluidic sensors and actuators

    , Article Measurement: Journal of the International Measurement Confederation ; Volume 73 , September , 2015 , Pages 127-136 ; 02632241 (ISSN) Seyyed Fakhrabadi, M. M ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    Elsevier  2015
    Abstract
    The paper investigates the effects of fluid flow on the static and dynamic behaviors of electrostatically actuated carbon nanotubes using nonlocal elasticity theory. The influences of various parameters of fluid flow including fluid viscosity, velocity, mass and temperature on the mechanical behaviors of the carbon nanotubes under static and step DC voltages are studied using this theory. The results computed from the nonlocal elasticity theory are compared with those estimated using the classical elasticity theorem and the outcomes demonstrate the applicability of the electrostatically actuated carbon nanotubes as nano sensors and nano actuators in nanofluidic systems. The nanosystem can be... 

    Morphological investigations of nanostructured V2O5 over graphene used for the ODHP reaction: From synthesis to physiochemical evaluations

    , Article Catalysis Science and Technology ; Volume 5, Issue 2 , Sep , 2015 , Pages 910-924 ; 20444753 (ISSN) Fattahi, M ; Kazemeini, M ; Khorasheh, F ; Rashidi, A. M ; Sharif University of Technology
    Royal Society of Chemistry  2015
    Abstract
    Oxidative dehydrogenation of propane (ODHP) in a fixed-bed reactor over synthesized vanadia nanocatalysts was investigated physicochemically. Several vanadium pentoxide (V2O5) nanostructures including rod-, belt-, tube-, needle- and flower-like forms were successfully synthesized via reflux and hydrothermal processes utilizing different templates such as monoamines, diamines, aromatic and alcoholic amines. The morphologies of the obtained products were found to be sensitive to the types of templates used. Nanorods obtained were 1.4 μm in length and about 97 nm in width while the VO2(B) nanotubes were of about 76 nm average diameter and up to 1.2 μm long. The diameters of the V2O5 nanotubes... 

    Study of Biomolecules Imaging Using Molecular Dynamics Simulations

    , Article Nano ; Volume 10, Issue 7 , October , 2015 ; 17932920 (ISSN) Kheirodin, M ; Nejat Pishkenari, H ; Moosavi, A ; Meghdari, A ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    The process of imaging a biomolecule by atomic force microscope (AFM) is modeled using molecular dynamics (MD) simulations. Since the large normal force exerted by the tip on the biosample in contact and tapping modes may damage the sample structure and produce irreversible deformation, the noncontact mode of AFM (NC-AFM) is employed as the operating mode. The biosample is scanned using a carbon nanotube (CNT) as the AFM probe. CNTs because of their small diameter, high aspect ratio and high mechanical resistance attract many attentions for imaging purposes. The tip-sample interaction is simulated by the MD method. The protein, which has been considered as the biomolecule, is ubiquitin and a... 

    Reinforcing mechanisms of carbon nanotubes and high structure carbon black in natural rubber/styrene-butadiene rubber blend prepared by mechanical mixing-effect of bound rubber

    , Article Polymer International ; Volume 64, Issue 11 , July , 2015 , Pages 1627-1638 ; 09598103 (ISSN) Ahmadi, M ; Shojaei, A ; Sharif University of Technology
    John Wiley and Sons Ltd  2015
    Abstract
    The reinforcing effect of high structure carbon black (HSCB) and multi-walled carbon nanotubes (MWCNTs) on natural rubber/styrene-butadiene rubber blend processed using mechanical mixing was comparatively investigated. In-depth analysis by dynamic mechanical analysis, the Eggers-Schummer model and Medalia's relationship showed that HSCB aggregates provided large internal pores leading to significant immobilized macromolecules in filled rubber. Additionally, a tubular immobilized rubber layer with a thickness of 8nm was estimated for the rubber/MWCNT system based on dynamic mechanical analysis data. The mechanical performance of the HSCB filled blend was higher than that of the MWCNT filled... 

    Thermal buckling analysis of bridged single walled carbon nanotubes using molecular structural mechanics

    , Article Journal of Applied Physics ; Volume 117, Issue 11 , 2015 ; 00218979 (ISSN) Firouz Abadi, R. D ; Badri Kouhi, E ; Sharif University of Technology
    American Institute of Physics Inc  2015
    Abstract
    This paper is concerned with the stability analysis of bridged single walled carbon nanotubes (SWCNT) under temperature changes. A molecular structural mechanics model is utilized to investigate the free vibration frequencies and thermal buckling of SWCNT. In comparison with most of the previous studies, a temperature-variable thermal-expansion-coefficient is used that is negative under a certain temperature. Also thermal variation of Young's modulus of the CNTs is considered. Several studies are performed to investigate the critical temperature change due to heating and cooling of SWCNTs with different chiralities and slenderness ratios and the stability boundaries are determined  

    Hydro-purification of crude terephthalic acid using palladium catalyst supported on multi-wall carbon nanotubes

    , Article Journal of Industrial and Engineering Chemistry ; Volume 28 , August , 2015 , Pages 202-210 ; 1226086X (ISSN) Tourani, S ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2015
    Abstract
    Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.%...