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    General consideration for button-BPM

    , Article IPAC 2014: Proceedings of the 5th International Particle Accelerator Conference ; Jul , 2014 , p. 3537-3540 Molaee, A ; Samadfam, M ; Mohammadzadeh, M ; Shafiee, M ; Sharif University of Technology
    In order to design Button Beam Position Monitors (BPMs) for synchrotron facilities, one algorithm by C# have been developed which can calculate all required parameters to analyze optimal design based on vacuum chamber and button dimensions. Beam position monitors are required to get beam stabilities on submicron levels. For this purpose, different parameters such as capacitance, sensitivity versus bandwidth, intrinsic resolution, induced charge and voltage on buttons are calculated. Less intrinsic resolution and high sensitivity and capacitance are desired. To calculate induced charge and voltage on each button, Poisson's equation has been solved by Green method. For sensitivities... 

    Gas barrier and mechanical properties of crosslinked ethylene vinyl acetate nanocomposites

    , Article Journal of Composite Materials ; Volume 47, Issue 23 , 2013 , Pages 2987-2993 ; 00219983 (ISSN) Ahmad Ramazani, S. A ; Shafiee, M ; Abedsoltan, H ; Shafiee, A ; Sharif University of Technology
    In this research, the effects of crosslinking agent and clay content on the morphology, barrier and mechanical properties of ethylene vinyl acetate-organoclay nanocomposites prepared by solution method were studied. Dicumyl peroxide has been used as crosslinking agent. The morphology of the prepared nanocomposites was investigated using wide-angle X-ray diffraction and transmission electron microscopy. Wide-angle X-ray diffraction and transmission electron microscopyindicated that the prepared nanocomposites had predominantly intercalated morphologies. The obtained results of permeability tests showed that the permeability of ethylene vinyl acetate films dramatically decreases with addition... 

    Long-term prediction of solar and geomagnetic activity daily time series using singular spectrum analysis and fuzzy descriptor models

    , Article Earth, Planets and Space ; Volume 61, Issue 9 , 2009 , Pages 1089-1101 ; 13438832 (ISSN) Mirmomeni, M ; Kamaliha, E ; Shafiee, M ; Lucas, C ; Sharif University of Technology
    Of the various conditions that affect space weather, Sun-driven phenomena are the most dominant. Cyclic solar activity has a significant effect on the Earth, its climate, satellites, and space missions. In recent years, space weather hazards have become a major area of investigation, especially due to the advent of satellite technology. As such, the design of reliable alerting and warning systems is of utmost importance, and international collaboration is needed to develop accurate short-term and long-term prediction methodologies. Several methods have been proposed and implemented for the prediction of solar and geomagnetic activity indices, but problems in predicting the exact time and... 

    Study of two-layer tapered depth of interaction PET detector

    , Article Applied Radiation and Isotopes ; Volume 174 , 2021 ; 09698043 (ISSN) Behnamian, H ; Yousefnejad, S ; Shafiee, M ; Rafiei, A ; Sharif University of Technology
    Elsevier Ltd  2021
    Improving detection efficiency in small animal PET scanners without degrading spatial resolution is one of the main problems of these scanners. Commercial small animal PET scanners use different methods to achieve desirable levels of sensitivity and spatial resolution. GE Healthcare eXplore VISTA PET scanner uses double layer (LYSO-GSO) depth-of-interaction (DOI) capable cuboid detector modules. In this work, the design of GE Healthcare eXplore VISTA PET scanner is improved using tapered detector geometry instead of cuboid geometry. Using tapered detector geometry, the gaps between adjacent modules are filled and the sensitive volume has increased about 11.5%. The new designed PET scanner... 

    Modeling and comparison of different simulations for release of amoxicillin from chitosan hydrogels

    , Article Polymer - Plastics Technology and Engineering ; Volume 52, Issue 11 , 2013 , Pages 1147-1153 ; 03602559 (ISSN) Mirzaei B., E ; Ramazani S. A., A ; Shafiee, M ; Alemzadeh, I ; Ebrahimi, H ; Sharif University of Technology
    In this research work, different devices made of glutaraldehyde cross-linked chitosan hydrogels loaded by amoxicillin, have been prepared using freeze-drying method. Effects of system parameters such as cross-linker concentration, pH, and gel structure on the morphology and release behavior of devices have been investigated using standard methods. Morphological studies were performed using SEM instrument and controlled releases are followed via spectrophotometeric method. Reaction of glutaraldehyde with chitosan has been studied using FTIR instrument. SEM micrographs have shown that with increasing cross-linker percentage in hydrogel, pore sizes increased where pore size distribution... 

    Studies on glutaraldehyde crosslinked chitosan hydrogel properties for drug delivery systems

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 62, Issue 11 , 2013 , Pages 605-611 ; 00914037 (ISSN) Mirzaei, B. E ; Ramazani, S. A. A ; Shafiee, M ; Danaei, M ; Sharif University of Technology
    Chitosan was crosslinked with different amount of glutaraldehyde to prepare appropriate hydrogels to be used as drug delivery system. The swelling behavior of freeze-dried hydrogels in aqueous media at different temperature and pHs has been examined. The swelling, porosity and biocompatibility behavior of samples were investigated to check effects of polymer/polymer and polymer/drug interactions on these system characteristics. Obtained experimental results illustrates that with increasing crosslinking agent from 0.068 to 0.30, swelling of the prepared samples degrees from 1200% to 600% and pore diameters change from 100 to 500 μm. To investigate systems biocompatibility in gastric... 

    Investigation of Thermomechanical Properties of UHMWPE/Graphene Oxide Nanocomposites Prepared by in situ Ziegler-Natta Polymerization

    , Article Advances in Polymer Technology ; Volume 34, Issue 4 , February , 2015 ; 07306679 (ISSN) Bahrami, H ; Ramazani, A.S.A ; Kheradmand, A ; Shafiee, M ; Baniasadi, H ; Sharif University of Technology
    John Wiley and Sons Inc  2015
    The graphene-based Ziegler-Natta catalyst has been used to prepare ultrahigh molecular weight polyethylene/graphene oxide (UHMWPE/GO) nanocomposite via in situ polymerization. The morphological investigations have been conducted using X-ray diffraction patterns and scanning electron microscopy method. The obtained results indicated that no diffraction peak is detected in a GO pattern, which could be due to the exfoliation of graphene nanosheets in the UHMWPE matrix. Morphological investigations indicated that GO nanosheets are dispersed almost uniformly in polymeric matrix, and that there should exist a good interaction between nanofillers and matrix. The mechanical properties of the... 

    Preparation and investigation of tribological properties of ultra-high molecular weight polyethylene (UHMWPE)/graphene oxide

    , Article Polymers for Advanced Technologies ; Volume 27, Issue 9 , 2016 , Pages 1172-1178 ; 10427147 (ISSN) Bahrami, H ; Ramazani S. A., A ; Shafiee, M ; Kherad Mand, A ; Sharif University of Technology
    John Wiley and Sons Ltd 
    This article has been devoted to investigation of the tribological properties of ultra-high molecular polyethylene/graphene oxide nanocomposite. The nanocomposite of ultra-high molecular polyethylene/graphene oxide was prepared with 0.5, 1.5, and 2.5 wt% of graphene oxide and with a molecular weight of 3.7 × 106 by in-situ polymerization using Ziegler–Natta catalyst. In this method, graphene oxide was used along with magnesium ethoxide as a novel bi-support of the Ziegler–Natta catalyst. Analyzing the pin-on-disk test, the tribological properties of the nanocomposite, such as wear rate and mean friction coefficient, were investigated under the mentioned contents of graphene oxide. The... 

    Three-dimensional simulation of hydrodynamics in a rotating disc contactor using computational fluid dynamics

    , Article Chemical Engineering and Technology ; Volume 32, Issue 1 , 2009 , Pages 93-102 ; 09307516 (ISSN) Ghaniyari Benis, S ; Hedayat, N ; Ziyari, A ; Kazemzadeh, M ; Shafiee, M ; Sharif University of Technology
    The 3D simulation of the hydrodynamic behavior of a rotating disc contactor (RDC) by means of computational fluid dynamics (CFD) was investigated for the n-butanol-succinic acid-water (BSW) system. For the two-phase liquid-liquid flow, the velocity distribution of the continuous phase and drop size distributions were determined using the k-ω turbulence model in conjunction with the Eulerian-Eulerian approach and MUSIG model. In this system in which the holdup of the dispersed phase is low, the continuous phase velocity was computed by simultaneously solving the Navier-Stokes equations beside the different models of turbulence. The motions of the dispersed phase was calculated while... 

    Fuzzy descriptor systems and spectral analysis for chaotic time series prediction

    , Article Neural Computing and Applications ; Volume 18, Issue 8 , 2009 , Pages 991-1004 ; 09410643 (ISSN) Mirmomeni, M ; Lucas, C ; Shafiee, M ; Nadjar Araabi, B ; Kamaliha, E ; Sharif University of Technology
    Predicting future behavior of chaotic time series and systems is a challenging area in the literature of nonlinear systems. The prediction accuracy of chaotic time series is extremely dependent on the model and the learning algorithm. In addition, the generalization property of the proposed models trained by limited observations is of great importance. In the past two decades, singular or descriptor systems and related fuzzy descriptor models have been the subjects of interest due to their many practical applications in modeling complex phenomena. In this study fuzzy descriptor models, as a more recent neurofuzzy realization of locally linear descriptor systems, which have led to the... 

    3D simulation of solutes concentration in urinary concentration mechanism in rat renal medulla

    , Article Mathematical Biosciences ; Volume 308 , 2019 , Pages 59-69 ; 00255564 (ISSN) Mahdavi, S. S ; Abdekhodaie, M. J ; Farhadi, F ; Shafiee, M. A ; Sharif University of Technology
    Elsevier Inc  2019
    In this work, a mathematical model was developed to simulate the urinary concentration mechanism. A 3-D geometry was derived based on the detail physiological pictures of rat kidney. The approximate region of each tubule was obtained from the volume distribution of structures based on Walter Pfaller's monograph and Layton's region-based model. Mass and momentum balances were applied to solve for the change in solutes concentration and osmolality. The osmolality of short and long descending nephrons at the end of the outer medulla was obtained to be 530 mOsmol/kgH2O and 802 mOsmol/kgH2O, respectively, which were in acceptable agreement with experimental data. The fluid osmolality of the short... 

    Effect of organoclay modified binders on fatigue performance

    , Article RILEM Bookseries ; Volume 4 , 2012 , Pages 869-878 ; 22110844 (ISSN) ; 9789400745650 (ISBN) Tabatabaee, N ; Shafiee, M. H ; Scarpas, A ; Kringos, N ; Al Qadi, I. L ; Loizos, A ; Sharif University of Technology
    Organoclay modification is receiving attention as a nano-modifier for asphalt binders. Nanoparticles are able to effectively mend the damaged sites of the nanocomposite without external intervention. Particle-polymer interaction results in packing particles into developed cracks, thereby mending the cracks during patch formation. This study investigates the rheological properties of organoclay modified binders with a focus on their fatigue properties. To this end, the dissipated energy concept, the ratio of dissipated energy change and plateau value (PV) energy were examined during fatigue tests using a dynamic shear rheometer. The effects of strain level, frequency and temperature on unaged... 

    High-Voltage, high-current electrical switching discharge synthesis of ZnO nanorods: A new method toward rapid and highly tunable synthesis of oxide semiconductors in open air and water for optoelectronic applications

    , Article ACS Applied Materials and Interfaces ; Volume 13, Issue 39 , 2021 , Pages 46951-46966 ; 19448244 (ISSN) Sharifi Malvajerdi, S ; Abrari, M ; Karimi, V ; Shafiee, M ; Ghollamhosseini, S ; Taheri Ghahrizjani, R ; Ahmadi, M ; Wang, D ; Sun, H ; Soltanmohammadi, M ; Imani, A ; Ghanaatshoar, M ; Mohseni, S. M ; Taghavinia, N ; Sharif University of Technology
    American Chemical Society  2021
    A novel method of oxide semiconductor nanoparticle synthesis is proposed based on high-voltage, high-current electrical switching discharge (HVHC-ESD). Through a subsecond discharge in the HVHC-ESD method, we successfully synthesized zinc oxide (ZnO) nanorods. Crystallography and optical and electrical analyses approve the high crystal-quality and outstanding optoelectronic characteristics of our synthesized ZnO. The HVHC-ESD method enables the synthesis of ZnO nanorods with ultraviolet (UV) and visible emissions. To demonstrate the effectiveness of our prepared materials, we also fabricated two UV photodetectors based on the ZnO nanorods synthesized using the subsecond HVHC-ESD method. The...