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Microstructure, fractography, and mechanical properties of hardox 500 steel tig-welded joints by using different filler weld wires
, Article Materials ; Volume 15, Issue 22 , 2022 ; 19961944 (ISSN) ; Haowei, M ; Yarigarravesh, M ; Assari, A. H ; Tayyebi, M ; Tayebi, M ; Hamawandi, B ; Sharif University of Technology
MDPI
2022
Abstract
This paper deals with the effects of three low-carbon steel filler metals consisting of ferritic and austenitic phases on the weld joints of the tungsten inert gas (TIG) welding of Hardox 500 steel. The correlation between the microstructure and mechanical properties of the weld joints was investigated. For this purpose, macro and microstructure were examined, and then microhardness, tensile, impact, and fracture toughness tests were carried out to analyze the mechanical properties of joints. The results of optical microscopy (OM) images showed that the weld zones (WZ) of all three welds were composed of different ferritic morphologies, including allotriomorphic ferrite, Widmanstätten...
Bearing Prognostics under the Load-Varying Conditions, Using Combination of Data-Drive and Physic-based Methods
, Ph.D. Dissertation Sharif University of Technology ; Behzad, Mehdi (Supervisor) ; Rohani, Abbas (Co-Supervisor) ; Ming J. Zuo (Co-Supervisor)
Abstract
In this research, an artificial intelligence (AI) based model and a physics-based model have individually employed for prognostics of rolling element bearing (REB) under constant operating condition. Then a combination of physics-based models and data-driven model (Hybrid model) has been developed for remaining useful life (RUL) prediction of rolling element bearing (REB) under the load de-rating condition. The well-known crack propagation model Paris’ law has been employed to develop a physics-based model which can describe the degradation rate of the REB when the applying load is changed. To this aim, the elastic solution of the contact mechanics and Hertz stress between curved surfaces is...
Down from the pedestal: Revisiting the exploit of literature in EFL language classes
, Article International Journal of Applied Linguistics and English Literature ; Volume 4, Issue 2 , 2015 , Pages 158-168 ; 22003592 (ISSN) ; Lari, Z ; Mosalli, Z ; Sharif University of Technology
Australian International Academic Centre PTY LTD
2015
Abstract
According to Arthur (2006, p. 200), “Through the use of literature, a language learning experience might become at the same time a source of immediate pleasure and satisfaction for the student. This possibility makes literature an appealing teaching device for ESL teachers”. However, numerous factors may contribute to the teachers’ lack of interest in using literary texts as a teaching tool. This study was an attempt to investigate Iranian EFL teachers’ attitude toward using literature in language classes and their perception toward the probable reasons of some teachers’ lack of interest in doing so. Altogether forty-four language teachers (19 females and 25 males, with a mean age of 26)...
Inclusion of carbon nanotubes in a hydroxyapatite sol-gel matrix
, Article Ceramics International ; Volume 35, Issue 7 , 2009 , Pages 2987-2991 ; 02728842 (ISSN) ; Nemati, Z. A ; Sadeghian, Z ; Sharif University of Technology
2009
Abstract
In this study, the inclusion of multi-walled carbon nanotubes as the second phase in the hydroxyapatite matrix, in order to improve the mechanical strength, has been performed via the sol-gel process. The stability of carbon nanotube sol with the changes of pH and dispersant values (sodium dodecyl sulfate) was evaluated by zeta potential analysis. The results indicated that synthesis of hydroxyapatite particles in the presence of the carbon nanotubes had the best result in homogenization of the carbon nanotube dispersion and faster crystallization of hydroxyapatite. The crystallization of hydroxyapatite phase was investigated with differential scanning calorimetry (DSC) and X-ray diffraction...
Fourier optics approach in evaluation of the diffraction and defocus aberration in three-dimensional integral imaging
, Article Computational Modelling of Objects Represented in Images: Fundamentals, Methods and Applications III - Proceedings of the International Symposium, CompIMAGE 2012 ; 2012 , Pages 81-84 ; 9780415621342 (ISBN) ; Kavehvash, Z ; Mehrany, K ; Sharif University of Technology
CRC
2012
Abstract
The unwanted effects of diffraction and defocus aberration in three-dimensional integral imaging are taken into account by using the Fourier optics approach. The concepts of point spread function and optical transfer function widely in use for conventional two-dimensional imaging are generalized and applied to three-dimensional integral imaging systems. The effects of diffraction and defocus aberration are then studied and the performance of the conventional single lens imaging system is compared against that of the integral imaging
Multi-target sputter deposition of Ni50Ti 50 - XHfx shape memory thin films for high temperature microactuator application
, Article Sensors and Actuators, A: Physical ; Volume 121, Issue 2 , 2005 , Pages 543-548 ; 09244247 (ISSN) ; Cao, Y. Z ; Barber, Z. H ; Sharif University of Technology
2005
Abstract
High temperature shape memory NiTiHf thin films with varying hafnium contents up to 28.7 at.% were fabricated by DC magnetron sputtering using simultaneous sputter deposition from separate elemental targets. The required film composition was achieved by adjusting the power ratio to the targets. The as-deposited films were amorphous; a post deposition annealing was performed at 550 °C to crystallize the films. Two-micron thick films were characterized by energy dispersive spectroscopy in a scanning electron microscope, temperature controlled X-ray diffraction, differential scanning calorimetry, and atomic force microscopy. The results showed that above 10 at.% Hf additions the transformation...
Subsidy cut and its effect on tehran electricity company: A system dynamics approach
, Article Proceedings of the 2012 - Summer Computer Simulation Conference, SCSC 2012, Part of SummerSim 2012 Multiconference ; Volume 44, Issue 10 , 2012 , Pages 113-120 ; 9781618399847 (ISBN) ; Fard, S. Z
2012
Abstract
In recent years, subsidy payment has been made a main challenge for governments due to growth of population and energy price in global markets. Targeted subsidy plan has been implemented in Iran since last year, and this article discusses its effects on costs and revenues of Tehran Electricity Company as one of the major subdivisions of Iran's electricity industry. In the new system, structural changes have been made in electricity tariffs, so it is not possible to predict the future trends in electricity consumption only based on the past consumptions. In order to model the decision making structure in the recent conditions, a system dynamics method is applied. In addition to modeling the...
Interactions of coinage metal clusters with histidine and their effects on histidine acidity; Theoretical investigation
, Article Organic and Biomolecular Chemistry ; Volume 10, Issue 47 , Oct , 2012 , Pages 9373-9382 ; 14770520 (ISSN) ; Jamshidi, Z ; Tehrani, Z. A ; Fattahi, A ; Sharif University of Technology
2012
Abstract
Understanding the nature of interaction between metal nanoparticles and biomolecules such as amino acids is important in the development and design of biosensors. In this paper, binding of M3 clusters (M = Au, Ag and Cu) with neutral and anionic forms of histidine amino acid was studied using density functional theory (DFT-B3LYP). It was found that the interaction of histidine with M3 clusters is governed by two major bonding factors: (a) the anchoring N-M and O-M bonds and (b) the nonconventional N-H⋯M and O-H⋯M hydrogen bonds. The nature of these chemical bonds has been investigated based on quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. In the next...
Can anion interaction accelerate transformation of cytosine tautomers? Detailed view form QTAIM analysis
, Article Structural Chemistry ; Volume 23, Issue 6 , 2012 , Pages 1843-1855 ; 10400400 (ISSN) ; Tehrani, Z. A ; Fattahi, A ; Jamshidi, Z ; Sharif University of Technology
2012
Abstract
The relative stabilities and noncovalent interactions of the six low-lying energy tautomers of cytosine nucleobase with some biological anions (such as F-, Cl-, and CN-) have been investigated in gas phase by density functional theory (DFT) method in conjunction with 6-311++G (d,p) atomic basis set. Furthermore, to systematically investigate all possible tautomerisms from cytosine induced by proton transfer, we describe a study of structural tautomer interconversion in the gas phase and in a continuum solvent using DFT calculation. We carried out geometrical optimizations with the integral equation formalism of polarizable continuum (IEF-PCM) model to account for the solvent effect, and the...
Interactions of glutathione tripeptide with gold cluster: Influence of intramolecular hydrogen bond on complexation behavior
, Article Journal of Physical Chemistry A ; Volume 116, Issue 17 , 2012 , Pages 4338-4347 ; 10895639 (ISSN) ; Jamshidi, Z ; Javan, M. J ; Fattahi, A ; Sharif University of Technology
2012
Abstract
Understanding the nature of the interaction between metal nanoparticles and biomolecules has been important in the development and design of sensors. In this paper, structural, electronic, and bonding properties of the neutral and anionic forms of glutathione tripeptide (GSH) complexes with a Au 3 cluster were studied using the DFT-B3LYP with 6-31+G**-LANL2DZ mixed basis set. Binding of glutathione with the gold cluster is governed by two different kinds of interactions: Auâ€"X (X = N, O, and S) anchoring bond and Au··•·•H-X nonconventional hydrogen bonding. The influence of the intramolecular hydrogen bonding of glutathione on the interaction of this peptide with the gold cluster has been...
Implementing distance line protection schemes among IEC61850-enabled substations
, Article Proceedings of the IEEE Power Engineering Society Transmission and Distribution Conference ; April , 2014 , Page(s): 1 - 5 ; ISSN: 21608555 ; ISBN: 9781479936557 ; Darabi, Z ; Vakilian, M
2014
Abstract
As digital technology has developed, relays have evolved from simple electro-mechanical devices into robust microprocessor-embedded intelligent electronic devices (IEDs). Distance protection, one of the most important and sophisticated forms of substation protection, quickly and selectively detects and clears phase faults in sub-transmission and transmission lines. The installation of a substation automation system (SAS) involves implementing control, monitoring, and protection logic by programming the IEDs and providing an appropriate communication network. IEC61850 has gradually satisfied the need for a standard communication protocol so that IEDs from different manufacturers can...
Efficient diastereo- and enantioselective synthesis of α,β-disubstituted γ-phosphono sulfonates
, Article Tetrahedron Asymmetry ; Volume 20, Issue 21 , 2009 , Pages 2429-2431 ; 09574166 (ISSN) ; Mirjafary, Z ; Saeidian, H
2009
Abstract
The first asymmetric synthesis of α,β-disubstituted γ-phosphono sulfonates is reported. The key step is the Michael addition of a lithiated enantiopure sulfonate bearing an inexpensive chiral sugar auxiliary to α,β-unsaturated phosphonates in good diastereoselectivities. After chromatographic purification, the cleavage of the chiral sugar auxiliary proceeds without any epimerization or racemization to form the corresponding isopropyl sulfonate in very good overall yield (75%) and excellent diastereomeric and enantiomeric excess (de, ee ≥ 95%). © 2009 Elsevier Ltd. All rights reserved
High-performance UV‐Vis-NIR photodetectors based on plasmonic effect in Au nanoparticles/ZnO nanofibers
, Article Applied Surface Science ; Volume 483 , 2019 , Pages 1110-1117 ; 01694332 (ISSN) ; Arab Bafrani, H ; Naseri, A ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this study, UV‐Vis-NIR photodetectors based on decorated ZnO nanofibers (NFs) with optimized coverage of Au nanoparticles (NPs) fabricated via combined simple electrospinning and sputtering techniques are introduced. The effect of different coverages of Au NPs resulted from different Au nominal layer thicknesses on the morphology and optical properties of the ZnO fibers are investigated through various characterization methods. It is discovered that 4 nm Au nominal thickness provides the highest UV on/off ratio (~460), responsivity (~332 A/W), detectivity (~2.93×10 11 Jones) as well as faster rise and decay times as compared to pure ZnO nanofibers. A broad spectral response from UV to NIR...
Engineering quantum Hall phases in a synthetic bilayer graphene system
, Article Physical Review B ; Volume 102, Issue 8 , 2020 ; Grass, T ; Vaezi, A ; Liu, Z ; Hafezi, M ; Sharif University of Technology
American Physical Society
2020
Abstract
Synthetic quantum Hall bilayer (SQHB), realized by optically driven monolayer graphene in the quantum Hall regime, provides a flexible platform for engineering quantum Hall phases as discussed in Ghazaryan et al. [Phys. Rev. Lett. 119, 247403 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.247403]. The coherent driving which couples two Landau levels mimics an effective tunneling between synthetic layers. The tunneling strength, the effective Zeeman coupling, and two-body interaction matrix elements are tunable by varying the driving frequency and the driving strength. Using infinite density matrix renormalization group techniques combined with exact diagonalization, we show that the system...
Effect of Ni, Pd and Ni-Pd nano-islands on morphology and structure of multi-wall carbon nanotubes
, Article Applied Surface Science ; Volume 253, Issue 20 , 2007 , Pages 8458-8462 ; 01694332 (ISSN) ; Mortazavi, Z ; Akhavan, O ; Moshfegh, A. Z ; Lahooti, Sh ; Sharif University of Technology
Elsevier
2007
Abstract
In this research, the effect of Ni, Pd and Ni-Pd catalysts have studied on morphology and structure of synthesized multi-wall carbon nanotubes (MWCNTs). Initially, thin films of Ni (with two thicknesses of 10 and 20 nm), Pd/Ni (5/10 nm) and Pd (10 nm) were deposited as catalysts on SiO 2 (60 nm)/Si(1 0 0) substrates, using dc magnetron sputtering technique. The deposited films were annealed at 900 °C in ammonia environment for 45 min, in order to obtain nano-structured catalyst on the surface. Using scanning electron microscopy (SEM), the average size of Ni nano-islands (synthesized by the 10 and 20 nm Ni films), Pd and Ni-Pd nano-islands were measured about 55, 110, 45 and 50 nm,...
Delafossite-alumina nanocomposite for enhanced catalytic wet peroxide oxidation of anionic pollutants
, Article Journal of Hazardous Materials ; Volume 417 , 2021 ; 03043894 (ISSN) ; Nouri, O ; Xie, Z ; Setayesh, S. R ; Wei, Z ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Mass transfer efficiency and catalytic reactivity are the two major hurdles for heterogeneous catalytic wet peroxide oxidation (CWPO) technologies. To address these issues, nanocomposite CuFeO2/Al2O3 was synthesized and assessed as a novel catalyst for enhanced adsorption and oxidation of anionic pollutants (catechol and reactive red 195 (RR195)) in waters. With a positive charge on the nanocomposite by introducing Al2O3, the adsorption of anionic pollutants was promoted. The surface complexation reaction on CuFeO2/Al2O3, which fits well to the Langmuir isotherm, has engined the mass transfer of pollutants to the nanocatalyst that demonstrated 96.46% and 99.75% removal of catechol and RR195...
Unified modeling and experimental realization of electrical and thermal percolation in polymer composites
, Article Applied Physics Reviews ; Volume 9, Issue 4 , 2022 ; 19319401 (ISSN) ; Arabshahi, Z. S ; Saberi, A. A ; Moshfegh, A. Z ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
Correlations between electrical and thermal conduction in polymer composites are blurred due to the complex contribution of charge and heat carriers at the nanoscale junctions of filler particles. Conflicting reports on the lack or existence of thermal percolation in polymer composites have made it the subject of great controversy for decades. Here, we develop a generalized percolation framework that describes both electrical and thermal conductivity within a remarkably wide range of filler-to-matrix conductivity ratios (Y f / Y m), covering 20 orders of magnitude. Our unified theory provides a genuine classification of electrical conductivity with typical Y f / Y m ≥ 10 10 as...
Kinetic parameters estimation of MgO-C refractory by shrinking core model
, Article Journal of Materials Science and Technology ; Volume 22, Issue 6 , 2006 , Pages 826-832 ; 10050302 (ISSN) ; Nemati, Z. A ; Sadrnezhaad, S. K ; Moghimi, Z. A ; Sharif University of Technology
2006
Abstract
Kinetics of oxidation of MgO-C refractories was investigated by shrinking core modeling of the gas-solid reactions taking place during heating the porous materials to the high temperatures. Samples containing 4.5-17 wt pct graphite were isothermally oxidized at 1000-1350°C. Weight loss data was compared with predictions of the model. A mixed 2-stage mechanism comprised of pore diffusion plus boundary layer gas transfer was shown to generally control the oxidation rate. Pore diffusion was however more effective, especially at graphite contents lower than 10 wt pct under forced convection blowing of the air. Model calculations showed that effective gas diffusion coefficients were in the range...
Binary and ternary NiTi-based shape memory films deposited by simultaneous sputter deposition from elemental targets
, Article Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films ; Volume 23, Issue 5 , 2005 , Pages 1425-1429 ; 07342101 (ISSN) ; Cao, Y. Z ; Sadrnezhaad, S. K ; Barber, Z. H ; Sharif University of Technology
2005
Abstract
The most challenging requirement for depositing NiTi-based shape memory thin films is the control of film composition because a small deviation can strongly shift the transformation temperatures. This article presents a technique to control film composition via adjustment of the power supplied to the targets during simultaneous sputter deposition from separate Ni, Ti, and X (e.g., Hf) targets. After optimization of sputter parameters such as working gas pressure, target-substrate distance, and target power ratio, binary Ni100-x Tix thin films were fabricated and characterized by energy dispersive x-ray spectroscopy in a scanning electron microscope (to measure the film composition and...
Pseudo-triangulating a simple polygon from its visibility graph
, Article 2015 5th International Conference on Computer and Knowledge Engineering, ICCKE 2015, 29 October 2015 ; October , 2015 , Pages 106-111 ; 9781467392808 (ISBN) ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Visibility graph of a simple polygon in a plain is a graph in which the number of its vertices corresponds with the number of vertices in the polygon and each of its edges corresponds with a pair of visible vertices in the polygon. Visibility graph reconstruction of a polygon is one of the old and important problems in computational geometry for which no algorithm has been offered yet. Considering that the problem of visibility graph reconstruction of a pseudo-triangle has been solved, we present an O(n2)-time algorithm for pseudo-triangulation of a simple polygon, using the visibility graph corresponding with the polygon (n is number of vertices of the polygon). To do so, first we present a...