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The role of mixed reaction promoters in polyol synthesis of high aspect ratio ag nanowires for transparent conducting electrodes
, Article Journal of Electronic Materials ; Volume 49, Issue 8 , 2020 , Pages 4822-4829 ; Khosravi, A ; Dehghani, M ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
Springer
2020
Abstract
In recent years, thin silver nanowires (Ag NWs) with diameters smaller than 150 nm have been synthesized by implementation of NaCl or FeCl3 as reaction promoters and high molecular weight polyvinylpyrrolidone (PVP) as the capping agent. However, the yield of Ag NWs still remains low, mostly due to the insufficient aspect ratio (AR) of the synthesized nanostructures and the production of Ag nanoparticles, which is an undesirable by product. This study proposes a modified technique to alleviate the problem by using a mixture of FeCl3/CuCl2 as the reaction promoter and two different types of PVP with molecular weight of 360 k and 40 k as the capping agents. The appropriate mixtures of...
Heat transfer of swirling impinging jets ejected from Nozzles with twisted tapes utilizing CFD technique
, Article Case Studies in Thermal Engineering ; Volume 6 , September , 2015 , Pages 104-115 ; 2214157X (ISSN) ; Mokhtari, M ; Haghshenasfard, M ; Barzegar Gerdroodbary, M ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
This research investigated the forced convection heat transfer by using the swirling impinging jets. This study focused on nozzles, which equipped with twisted tapes via a numerical approach. The computational domain created by utilizing the fully structured meshes, which had very high quality from the viewpoint of aspect ratio and skewness. The numerical simulations were performed at four different jet-to-plate distances (L/D) of 2, 4, 6 and 8, four Reynolds numbers of 4000, 8000, 12,000 and 16,000, and also four different twist ratios (y/w) of 3, 4, 5 and 6. The mesh-independent tests were conducted based upon the average Nusselt number. The obtained results revealed good agreement with...
Geometrical influence of a deposited particle on the performance of bridged carbon nanotube-based mass detectors
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 94 , 2017 , Pages 31-46 ; 13869477 (ISSN) ; Ceballes, S ; Abdelkefi, A ; Sharif University of Technology
Abstract
A nonlocal continuum-based model is derived to simulate the dynamic behavior of bridged carbon nanotube-based nano-scale mass detectors. The carbon nanotube (CNT) is modeled as an elastic Euler-Bernoulli beam considering von-Kármán type geometric nonlinearity. In order to achieve better accuracy in characterization of the CNTs, the geometrical properties of an attached nano-scale particle are introduced into the model by its moment of inertia with respect to the central axis of the beam. The inter-atomic long-range interactions within the structure of the CNT are incorporated into the model using Eringen's nonlocal elastic field theory. In this model, the mass can be deposited along an...
Effective shear modulus of solids reinforced by randomly oriented- / aligned-elliptic multi-coated nanofibers in micropolar elasticity
, Article Composites Part B: Engineering ; Volume 143 , 15 June , 2018 , Pages 197-206 ; 13598368 (ISSN) ; Shodja, H. M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Accurate estimation of the in-plane shear modulus of solids reinforced by nano-/micro-size elliptical multi-coated fibers is the focus of this paper. It is well-known that at the scales comparable to the nanoscopic length scales of the material, traditional theory of elasticity ceases to hold and, moreover, due to lack of consideration of such length scales has an innate weakness of sensing the size effect. Therefore, it is proposed to formulate and calculate the effective shear modulus of the nano-/micro-composite within micropolar theory which introduces two material characteristic lengths into the field equations. For this purpose, Mori-Tanaka theory is extended to treat nested...
Seismic assessment of unanchored steel storage tanks by endurance time method
, Article Earthquake Engineering and Engineering Vibration ; Volume 10, Issue 4 , 2011 , Pages 591-603 ; 16713664 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Abstract
Liquid storage tanks are essential structures that are often located in residential and industrial areas; thus an assessment of their seismic performance is an important engineering issue. In this paper, the seismic response of unanchored steel liquid storage tanks is investigated using the endurance time (ET) dynamic analysis procedure and compared to responses obtained for anchored tanks under actual ground motions and intensifying ET records. In most cases, the results from ground motions are properly obtained with negligible differences using ET records. It is observed that uplifting of the tank base, which is closely related to the tank aspect ratio, has the greatest significance in the...
Physical bounds of metallic nanofingers obtained by mechano-chemical atomic force microscope nanolithography
, Article Applied Surface Science ; Volume 255, Issue 6 , January , 2009 , Pages 3513-3517 ; 01694332 (ISSN) ; Abdolahad, M ; Sharif University of Technology
2009
Abstract
To obtain metallic nanofingers applicable in surface acoustic wave (SAW) sensors, a mechano-chemical atomic force microscope (AFM) nanolithography on a metallic thin film (50 nm in thickness)/piezoelectric substrate covered by a spin-coated polymeric mask layer (50-60 nm in thickness) was implemented. The effective shape of cross-section of the before and after etching grooves have been determined by using the AFM tip deconvolution surface analysis, structure factor, and power spectral density analyses. The wet-etching process improved the shape and aspect ratio (height/width) of the grooves and also smoothed the surface within them. We have shown that the relaxed surface tension of the...
Sensitivity analysis of torque transmission efficiency of a half-toroidal CVT
, Article 2006 SAE World Congress, Detroit, MI, 3 April 2006 through 6 April 2006 ; 2006 ; 01487191 (ISSN) ; Zohoor, H ; Sharif University of Technology
SAE International
2006
Abstract
In this research a computer model based on elasto hydrodynamic fluid film lubrication is developed in order to calculate the torque transmission efficiency of a half-toroidal CVT variator. Validation of this model is verified by comparing the experimental and the model results. Sensitivity of torque transmission efficiency to eleven parameters is investigated. These parameters are: dimensionless roller curvature, aspect ratio, half cone angle, fluid viscosity index, pressure constant for Roelands model, input rotational velocity, absolute viscosity at atmospheric pressure, Young modulus of disks and power rollers, Poisson ratio of disks and power rollers, number of power rollers and variator...
Optimizing the geometry of a half-toroidal CVT
, Article Powertrain and Fluid Systems Conference and Exhibition, San Antonio, TX, 24 October 2005 through 27 October 2005 ; 2005 ; 01487191 (ISSN) ; Zohoor, H ; Sharif University of Technology
SAE International
2005
Abstract
In this research a model is developed which calculates the torque transmission efficiency of a half-toroidal CVT as a function of variator geometry, gear ratio and input torque. The different criteria which are considered to be important in a half toroidal CVT performance are torque transmission efficiency, variator weight, roller fatigue life and bearing torque loss. Variation of geometrical characteristics such as roller curvature, number of power rollers, aspect ratio and half cone angle affect these criteria in different ways. Therefore, in order to find the optimal quantity for each geometrical parameter an optimization problem should be developed. The objective function of this...
Experimental and analytical study of block slit damper
, Article Journal of Constructional Steel Research ; Volume 141 , February , 2018 , Pages 167-178 ; 0143974X (ISSN) ; Pournamazian Najafabadi, E ; Esmaeilpour Estekanchi, H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This study proposes a novel type of metallic yielding damper called block slit damper or BSD. This damper is a slit damper with very low height to thickness ratio. This device has high shear capacities, and is more economical than SSD devices with high height to thickness ratios. Based on theoretical analysis the formulation for the BSD device's main parameters is derived. Then to investigate the hysteretic behavior of the proposed devices, 5 specimens with different aspect ratios (height-width ratios) were manufactured and tested in a quasi-static manner. The tests revealed that by reducing the aspect ratios, the shear and energy dissipation capacity increases while the displacement...
A depthwise averaging solution for cross-stream diffusion in a Y-micromixer by considering thick electrical double layers and nonlinear rheology
, Article Microfluidics and Nanofluidics ; Volume 19, Issue 6 , 2015 , Pages 1297-1308 ; 16134982 (ISSN) ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
Springer Verlag
2015
Abstract
Both nonlinear rheology and finite EDL thickness effects on the mixing process in an electroosmotically actuated Y-sensor are being investigated in this paper, utilizing a depthwise averaging method based on the Taylor dispersion theory. The fluid rheological behavior is assumed to obey the power-law viscosity model. Analytical solutions are obtained assuming a large channel width to depth ratio for which a 1-D profile can efficiently describe the velocity distribution. Full numerical simulations are also performed to determine the applicability range of the analytical model, revealing that it is able to provide accurate results for channel aspect ratios of ten and higher and quite...
Electrokinetic mixing at high zeta potentials: Ionic size effects on cross stream diffusion
, Article Journal of Colloid and Interface Science ; Volume 442 , 2015 , Pages 8-14 ; 00219797 (ISSN) ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
Academic Press Inc
2015
Abstract
The electrokinetic phenomena at high zeta potentials may show several unique features which are not normally observed. One of these features is the ionic size (steric) effect associated with the solutions of high ionic concentration. In the present work, attention is given to the influences of finite ionic size on the cross stream diffusion process in an electrokinetically actuated Y-shaped micromixer. The method consists of a finite difference based numerical approach for non-uniform grid which is applied to the dimensionless form of the governing equations, including the modified Poisson-Boltzmann equation. The results reveal that, neglecting the ionic size at high zeta potentials gives...
A characteristic-based numerical simulation of water-titanium dioxide nano-fluid in closed domains
, Article International Journal of Engineering, Transactions A: Basics ; Volume 33, Issue 1 , 2020 , Pages 158-163 ; Razavi, S. E ; Adibi, O ; Sharif University of Technology
Materials and Energy Research Center
2020
Abstract
A new characteristic-based method is developed and used for solving the mixed and forced convection problems. The nano-fluid flow with heat transfer is simulated with a novel characteristic-based scheme in closed domains with different aspect ratios. For this purpose, a FORTRAN code has been written and developed. Water as a pure fluid and water-titanium dioxide as a nano-fluid were considered. The governing equations are solved by the finite volume utilizing a characteristic-based scheme for the convective fluxes. The simulation is done at Grashof numbers from 100 to 104, Reynolds numbers from 100 to 1000, and volume fractions of nano-particles from 0% to 10%. Streamlines, isotherms,...
Laminar falling film flow of aqueous Li Br solution on a horizontal elliptical tube
, Article International Journal of Fluid Mechanics Research ; Volume 40, Issue 4 , 2013 , Pages 324-343 ; 10642277 (ISSN) ; Saidi, M. H ; Sharif University of Technology
2013
Abstract
Flow hydrodynamics of laminar falling film of aqueous Li Br solution (Li Br - H2O) on a horizontal elliptical tube has been investigated in this research. The film velocity distribution and film thickness, namely, the flow characteristics are determined by solving analytically simultaneous simplified Navier - Stokes equations and continuity equation in polar and Cartesian coordinates. The analysis is based on steady state laminar flow of falling liquid film of Li Br - H2O on a horizontal elliptical tube in polar model and Cartesian model (CM), for cases in which traction on the film surface is considered negligible. Models are compared with each other in three cases of aspect ratios (Ar),...
On the influence of centerline strain on the stability of a bimorph piezo-actuated microbeam
, Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1246-1252 ; 10263098 (ISSN) ; Kamali Eigoli, A ; Zohoor, H ; Vossoughi, G ; Sharif University of Technology
2011
Abstract
The nonlinear equation of motion for pre-stretched EulerBernoulli beams is derived. The effect of pre-tension and pre-compression in EulerBernoulli beams is studied. It is shown that compressive strain affects the bending stiffness much more than tensile strain. Based on the derived equation, the dynamic model of bimorph piezo-actuated beams, which is accurate, yet simple, is then developed. Afterwards, the critical voltage, which makes the piezo-actuated microbeam unstable, is numerically investigated. It is shown that the strain of the centerline is proportional to the beam's aspect ratio squared. Results show that the more the aspect ratio, the less the critical voltage. In addition, it...
HPGR effect on the particle size and shape of iron ore pellet feed using response surface methodology
, Article Transactions of the Institutions of Mining and Metallurgy, Section C: Mineral Processing and Extractive Metallurgy ; 2017 , Pages 1-9 ; 03719553 (ISSN) ; Halali, M ; Hejazi, R ; Saghaeian, M ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
In this study the effect of HPGR operational parameters on the dimensional properties of pellet feed was examined and optimized using factorial methodology. The operational parameters considered include feed moisture, specific pressure and roll speed. For this study, size and shape of particles with Blaine number in the range 1800–2200 cm2 g−1 was thoroughly investigated. It was deduced that increasing the specific pressure and decreasing the roll speed would result in reduction of D80 but would increase the Blaine number. The circularity, aspect ratio and roughness descriptors of the particles were measured by SEM micrographs and image analysis software. It was observed that particles...
HPGR effect on the particle size and shape of iron ore pellet feed using response surface methodology
, Article Mineral Processing and Extractive Metallurgy: Transactions of the Institute of Mining and Metallurgy ; Volume 127, Issue 1 , 2018 , Pages 40-48 ; 25726641 (ISSN) ; Halali, M ; Hejazi, R ; Saghaeian, M ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
In this study the effect of HPGR operational parameters on the dimensional properties of pellet feed was examined and optimized using factorial methodology. The operational parameters considered include feed moisture, specific pressure and roll speed. For this study, size and shape of particles with Blaine number in the range 1800–2200 cm2g−1 was thoroughly investigated. It was deduced that increasing the specific pressure and decreasing the roll speed would result in reduction of D80 but would increase the Blaine number. The circularity, aspect ratio and roughness descriptors of the particles were measured by SEM micrographs and image analysis software. It was observed that particles tended...
Investigation of iron ore particle size and shape on green pellet quality
, Article Canadian Metallurgical Quarterly ; Volume 59, Issue 2 , 2020 , Pages 242-250 ; Halali, M ; Hejazi, R ; Saghaeian, M ; Sheikh Zadeh, V ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Particle size and shape of iron ore concentrate are effective parameters in the production of quality green pellets. In this research, the effect of particle morphology on green pellet quality was studied. It was concluded that pellet quality improved with increasing specific surface area. Drop number and green compression strength of pellets ground by HPGR were found to be superior over those ground in the ball mill. The chief reasons were related to particle shape and the fraction of fine particles. Smaller particle size results in a higher order of bonding between particles and therefore the formation of a stronger system. Also, the rougher and less circular shape of particles resulted in...