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shells--structures
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Dielectric core-shells with enhanced scattering efficiency as back-reflectors in dye sensitized solar cells
, Article RSC Advances ; Vol. 4, issue. 7 , Oct , 2014 , p. 3621-3626 ; Majles Ara M.H ; Tajabadi F ; Dabirian, A ; Mohammadpour, R ; Taghavinia, N ; Sharif University of Technology
Abstract
Particulate back-reflector films are conventionally used for the improvement of light harvesting in dye solar cells (DSC). The back-reflection of the films is directly related to the scattering efficiency of the individual particles. Inspired by the idea of multilayer optical thin films, here it is demonstrated theoretically and experimentally that putting a SiO2 shell around spherical rutile-TiO2 particles leads to improved light scattering by the particles. These dielectric core-shells not only enhance the overall diffuse reflection of the films, but they also cause a relative improvement in the red and near infrared regions. Back-reflector films of these core-shell particles employed in...
Deformation and stress analysis of sandwich cylindrical shells with a flexible core using harmonic differential quadrature method
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Vol. 37, issue. 1 , January , 2014 , p. 325-337 ; 16785878 ; Kargarnovin, M. H ; Fallah, F ; Sharif University of Technology
Abstract
In this paper, based on the high-order theory (HOT) of sandwich structures, the response of sandwich cylindrical shells with flexible core and any sort of boundary conditions under a general distributed static loading is investigated. The faces and the core are made of isotropic materials. The faces are modeled as thin cylindrical shells obeying the Kirchhoff–Love assumptions. For the core material, it is assumed to be thick and the in-plane stresses are negligible. The governing equations are derived using the principle of the stationary potential energy. Using harmonic differential quadrature method (HDQM), the equations are solved for deformation components. The obtained results are...
Monolithic quantum dot sensitized solar cells
, Article Journal of Physics D: Applied Physics ; Volume 46, Issue 48 , December , 2013 ; 00223727 (ISSN) ; Ghane, Z ; Ghazyani, N ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
2013
Abstract
We report a new design of solar cells based on semiconductor quantum dots (QDs), monolithic quantum dot sensitized solar cells (MQDSCs). MQDSCs offer the prospect of having lower cost and a simpler manufacturing process in comparison to conventional double substrate QDSCs. Our proposed monolithic QDSCs have a triple-layer structure, composed of a CdS sensitized mesoporous TiO2 photoanode, a scattering layer made by a core-shell structure of TiO 2/SiO2, and a carbon active/graphite counter electrode layer, which are all deposited on a single fluorine doped tin oxide (FTO) glass substrate. Mesoporous TiO2 was sensitized with CdS QDs by successive ionic layer adsorption and reaction. Here,...
Buckling analysis of cross-ply laminated conical panels using GDQ method
, Article Composites Part B: Engineering ; Volume 55 , 2013 , Pages 440-446 ; 13598368 (ISSN) ; Kouchakzadeh, M. A ; Shakouri, M ; Sharif University of Technology
2013
Abstract
The buckling analysis of cross-ply laminated conical shell panels with simply supported boundary conditions at all edges and subjected to axial compression is studied. The conical shell panel is a very interesting problem as it can be considered as the general case for conical shells when the subtended angle is set to 2π and also cylindrical panels and shells when the semi-vertex angle is equal to zero. Equations were derived using classical shell theory of Donnell type and solved using generalized differential quadrature method. The results are compared and validated with the known results in the literature. The effects of subtended angle, semi-vertex angle, length, thickness and radius of...
Confined nematic liquid crystal between two spherical boundaries with planar anchoring
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 88, Issue 1 , 2013 ; 15393755 (ISSN) ; Mozaffari, M. R ; Ejtehadi, M. R ; Sharif University of Technology
2013
Abstract
Nematic shells of liquid crystals have been provided in microscales. Defect structures in the shells are very essential in the electro-optical applications of such colloidal objects. We have numerically minimized the free energy of symmetric and asymmetric spherical shells of the nematic liquid crystal. Considering degenerate planar anchoring on the surfaces and isotropic nematic elasticity, a variety of defect structures are observed by controlling or varying the thicknesses of the shell and its degree of asymmetry. In symmetric shells, our calculations show that boojums (bipolar) defects appear in thick shells and tetrahedral (baseball) defects in thin shells. In asymmetric shells, while...
Surface/interface effects on elastic behavior of an edge dislocation in the shell of a core-shell nanowire
, Article European Journal of Mechanics, A/Solids ; Volume 41 , September–October , 2013 , Pages 86-100 ; 09977538 (ISSN) ; Rezazadeh Kalehbasti, S ; Shodja, H. M ; Sharif University of Technology
2013
Abstract
The elastic behavior of an edge dislocation placed in the shell of a free-standing core-shell nanowire is considered within the theory of surface/interface elasticity. Using the method of complex potential functions the expressions for the stress field of the dislocation, image forces on the dislocation, and the dislocation strain energy are derived and studied in detail. A special attention is paid to non-classical effects revealed within the surface/interface elasticity approach where a characteristic length parameter referred to as surface/interface modulus is introduced. These effects are (i) the stress oscillations along the shell surface and core-shell interface for negative values of...
Comparison of different strategies for the assembly of gold colloids onto Fe3O4@SiO2 nanocomposite particles
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 49 , 2013 , Pages 30-38 ; 13869477 (ISSN) ; Yaghmaei, S ; Roostaazad, R ; Arpanaei, A ; Sharif University of Technology
2013
Abstract
Three strategies were employed for the assembly of gold nanoparticles on silica-coated magnetite particles (SCMPs). In strategy I, citrate-coated gold nanoparticles were attached on the surface of amine-SCMPs. In strategy II, amine-SCMPs were coated with carboxylated gold nanoparticles via amide bond formation. In strategy III, the thiol-SCMPs surface was coated with gold nanoparticles. Among the above examined strategies, coating amine-SCMPs with gold nanoparticles via strategy I resulted in a better coverage and stronger intensity of absorption bands. Furthermore, results obtained through strategy I showed that decreasing the pH of the solution from 7 to 3 leads to a further red-shift of...
Accurate calculation of the natural frequencies of reticulated and solid cylindrical composite shells
, Article Applied Mechanics and Materials, 29 July 2011 through 31 July 2011, Bangkok ; Volume 110-116 , July , 2012 , Pages 4598-4606 ; 16609336 (ISSN) ; 9783037852620 (ISBN) ; Kargarnovin, M. H ; Jam, J. E ; Sharif University of Technology
2012
Abstract
There are hundreds models of reticulated structures including the squared reticulated cylindrical shells. It is considered as comprising of a number of circumferential and longitudinal rods. Analytical governing equation for natural frequencies has been derived for this type of structures and to verify the validity of solutions, Finite Element Method (FEM) is used. The comparison of results demonstrate close agreement between analytical and FE solutions. Also a comparison is preformed between a reticulated and equivalent solid hollow cylinder shell. The equivalent solid hollow cylinder has equal weight, length and outer diameter with the squared reticulated cylindrical shell. This comparison...
Supercritical synthesis and characterization of graphene-pbs quantum dots composite with enhanced photovoltaic properties
, Article Industrial and Engineering Chemistry Research ; Volume 54, Issue 30 , 2015 , Pages 7382-7392 ; 08885885 (ISSN) ; Tavakoli, M. M ; Outokesh, M ; Shafiekhani, A ; Simchi, A ; Sharif University of Technology
American Chemical Society
2015
Abstract
Lead sulfide quantum dots (PbS QDs) were decorated onto a graphene surface in a semi-core-shell structure using supercritical ethanol. The temperature of ethanol played significant role in controlling size and agglomeration of QDs as well as the extent of reduction of graphene. Average size of the QDs was estimated by transmission electron microscopy to be around 3.96 nm and by quantum models to be about 4.34 nm. PbS QDs prepared at 330 °C were of high purity, and the yield was 99%. Instrumental and chemical analyses demonstrated formation of a strong bond between PbS QDs and graphene, through a Pb-O-C bridge. UV and photoluminescence measurements along with theoretical considerations...
Analytical solution for axisymmetric buckling of joined conical shells under axial compression
, Article Structural Engineering and Mechanics ; Volume 54, Issue 4 , 2015 , Pages 649-664 ; 12254568 (ISSN) ; Shakouri, M ; Sharif University of Technology
Techno Press
2015
Abstract
In this study, the authors present an analytical approach to find the axisymmetric buckling load of two joined isotropic conical shells under axial compression. The problem of two joined conical shells may be considered as the generalized form of joined cylindrical and conical shells with constant or stepped thicknesses. Thickness of each cone is constant; however it may be different from the thickness of the other cone. The boundary conditions are assumed to be simply supported with rigid rings. The governing equations for the conical shells are obtained and solved with an analytical approach. A simple closed-form expression is obtained for the buckling load of two joined truncated conical...
Buckling analysis of nonlocal anisotropic thin-walled cylindrical shells subject to combined loading
, Article Journal of Engineering Mechanics ; Volume 142, Issue 12 , 2016 ; 07339399 (ISSN) ; Fazelzadeh, S. A ; Sohrabpour, S ; Sharif University of Technology
American Society of Civil Engineers (ASCE)
2016
Abstract
The equilibrium governing equations of nonlocal anisotropic thin-walled circular cylindrical shell under combined axial compressive force, torsional load, and external pressure are explicitly derived. This is accomplished by appropriately combining the equilibrium equations and the strain-displacement relations according to Flügge's shell theory and the stress-stain equations of Eringen's nonlocal elasticity theory. An analytical solution for the buckling of the shells is presented by using the complex method. This model is validated by a good agreement between the results given by the present model and available data in the literature. Furthermore, the model is utilized to elucidate the...
Effects of imperfection shapes on buckling of conical shells under compression
, Article Structural Engineering and Mechanics ; Volume 60, Issue 3 , 2016 , Pages 365-386 ; 12254568 (ISSN) ; Spagnoli, A ; Kouchakzadeh, M. A ; Sharif University of Technology
Techno Press
Abstract
This paper describes a systematic numerical investigation into the nonlinear elastic behavior of conical shells, with various types of initial imperfections, subject to a uniformly distributed axial compression. Three different patterns of imperfections, including first axisymmetric linear bifurcation mode, first non-axisymmetric linear bifurcation mode, and weld depression are studied using geometrically nonlinear finite element analysis. Effects of each imperfection shape and tapering angle on imperfection sensitivity curves are investigated and the lower bound curve is determined. Finally, an empirical lower bound relation is proposed for hand calculation in the buckling design of conical...
Theoretical and experimental analysis of the free vibrations of a shell made of n cone segments joined together
, Article Thin-Walled Structures ; Volume 108 , 2016 , Pages 416-427 ; 02638231 (ISSN) ; Saadat Foumani, M ; Navazi, H. M ; Sharif University of Technology
Elsevier Ltd
Abstract
This paper investigates the free vibrations of a shell made of n cone segments joined together. The governing equations of the conical shell were obtained by applying the Sanders shell theory and the Hamilton principle. Then, these governing equations are solved by using the power series method and considering a displacement field which is harmonic function about the time and the circumferential coordinate. Using the boundary conditions of the two ends of the shell and the continuity conditions at the interface section of shell segments, and solving the eigenvalue problem, the natural frequencies and the mode shapes are obtained. Very good agreements exist between the analytical results of...
Free vibrational characteristics of rotating joined cylindrical-conical shells
, Article Thin-Walled Structures ; Volume 107 , 2016 , Pages 657-670 ; 02638231 (ISSN) ; Saadat Foumani, M ; Sharif University of Technology
Elsevier Ltd
Abstract
The aim of this study is to investigate the free vibration of a rotating joined cylindrical-conical shell in the presence of the centrifugal and Coriolis forces as well as the initial hoop tension resulting from rotation of the shell. Based on the equations of general rotating shells of revolution, the equations of motion of rotating cylindrical and rotating conical shells are derived, and then these governing equations were solved by employing the power series method. For validation and comparison purposes, the results of the special cases of the studied problem were compared with the results reported in the literatures. Another comparison study was also conducted by the results of finite...
On dynamic instability of a pressurized functionally graded carbon nanotube reinforced truncated conical shell subjected to yawed supersonic airflow
, Article Composite Structures ; Volume 153 , 2016 , Pages 938-951 ; 02638223 (ISSN) ; Asadi, H ; Wang, Q ; Sharif University of Technology
Elsevier Ltd
Abstract
The aeroelastic flutter characteristics of a functionally graded carbon nanotube reinforced composite (FG-CNTRC) truncated conical shell under simultaneous actions of a hydrostatic pressure and yawed supersonic airflow are scrutinized. The nonlinearity in geometry of the conical shell is considered in Green–Lagrange sense and the model is derived according to the Novozhilov nonlinear shell theory. The aerodynamic pressure is modeled based on the quasi-steady Krumhaar's modified supersonic piston theory by considering the effect of the panel curvature and flow yaw angle. Parametric studies are conducted to investigate the effects of boundary conditions, semi-vertex angle, distribution and...
A stabilized piezolaminated nine-nodded shell element formulation for analyzing smart structures behaviors
, Article Mechanics of Advanced Materials and Structures ; Volume 23, Issue 2 , 2016 , Pages 187-194 ; 15376494 (ISSN) ; Salmani, H ; Afshari, S. S. G ; Sharif University of Technology
Taylor and Francis Inc
2016
Abstract
An explicit hybrid stabilization method is utilized together with a reduced order integration scheme to stabilize spurious zero energy modes from the sub-integrated degenerated shell element. This stabilization is achieved after employing appropriate contravariant higher order stress modes. The relevant finite element formulation of the piezolaminated nine-nodded shell element is then derived to analyze smart structures behaviors. To show the capabilities of the presented formulation, it has been implemented in a finite element code. The developed code is used to analyze some typical problems. The results are compared with those obtained from other schemes in the literature and experiments
Aero-thermo-elastic stability analysis of sandwich viscoelastic cylindrical shells in supersonic airflow
, Article Composite Structures ; Volume 147 , 2016 , Pages 185-196 ; 02638223 (ISSN) ; Sadeghmanesh, M ; Haddadpour, H ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
The aero-thermo-elastic stability of layered cylindrical shells with viscoelstic cores is investigated. The Donnell's shell theory for the outer layers and the first order shear deformation theory for the viscoelastic layer are employed in conjunction with the von Karman-Donnell kinematic nonlinearity to construct the model. The pre-stresses and pre-deformations arisen from the temperature rise and static aerodynamic pressure are first determined by solving the nonlinear thermo-elastic equilibrium equations using by an exact analytical method. The results are then used in the linear aeroelastic stability equations and analyzed with the Galerkin's procedure to determine the supersonic flutter...
High antimicrobial activity and low human cell cytotoxicity of core-shell magnetic nanoparticles functionalized with an Antimicrobial Peptide
, Article ACS Applied Materials and Interfaces ; Volume 8, Issue 18 , 2016 , Pages 11366-11378 ; 19448244 (ISSN) ; Rai, A ; Pinto, S ; Evangelista, M ; Cardoso, R. M. S ; Paulo, C ; Carvalheiro, T ; Paiva, A ; Imani, M ; Simchi, A ; Durães, L ; Portugal, A ; Ferreira, L ; Sharif University of Technology
American Chemical Society
2016
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with antimicrobial agents are promising infection-targeted therapeutic platforms when coupled with external magnetic stimuli. These antimicrobial nanoparticles (NPs) may offer advantages in fighting intracellular pathogens as well as biomaterial-associated infections. This requires the development of NPs with high antimicrobial activity without interfering with the biology of mammalian cells. Here, we report the preparation of biocompatible antimicrobial SPION@gold core-shell NPs based on covalent immobilization of the antimicrobial peptide (AMP) cecropin melittin (CM) (the conjugate is named AMP-NP). The minimal inhibitory...
An analytical approach for buckling analysis of generally laminated conical shells under axial compression
, Article Acta Mechanica ; Volume 227, Issue 4 , 2016 , Pages 1181-1198 ; 00015970 (ISSN) ; Shakouri, M ; Kouchakzadeh, M. A ; Sharif University of Technology
Springer-Verlag Wien
Abstract
In the present investigation, the buckling of generally laminated conical shells with various boundary conditions subjected to axial pressure is studied using an analytical approach. The governing equations are obtained using classical shell theory with Donnell assumptions in strain–deformation relations and the principle of minimum potential energy. The differential equations are solved using trigonometric functions in circumferential and power series in longitudinal directions. All types of boundary conditions can be applied in this method. The results are compared and validated with the results available in the literature, and good agreement is observed. Finally, the effects of the...
Free vibrations of a rotating shell made of p joined cones
, Article International Journal of Mechanical Sciences ; Volume 124-125 , 2017 , Pages 83-94 ; 00207403 (ISSN) ; Saadat Foumani, M ; Navazi, H. M ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In this paper, a method has been presented to study the free vibration of a rotating shell consisting of p coupled conical shells. This method considers the Coriolis and centrifugal forces as well as the initial hoop tension resulting from rotation of the shell. Matrix transform and power series methods were employed to solve the equations. The advantage of using the matrix transform approach is that the dimension of the coefficient matrix, which is finally constructed to obtain the natural frequencies of a shell made of p cones, remains 8×8. The obtained results were validated with the help of existing special cases of the studied problem reported in the literature, and by means of FEM...