• Coupled systems mechanics
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• v.9 no.3
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• pp.201-217
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• 2020

This paper employs differential quadrature method (DQM) and nonlocal strain gradient theory (NSGT) for studying free vibrational characteristics of porous functionally graded (FG) nanoplates coupled by visco-elastic foundation. A secant function based refined plate theory is used for mathematical modeling of the nano-size plate. Two scale factors are included in the formulation for describing size influences based on NSGT. The material properties for FG plate are porosity-dependent and defined employing a modified power-law form. Visco-elastic foundation is presented based on three factors including a viscous layer and two elastic layers.The governing equations achieved by Hamilton's principle are solved implementing DQM. The nanoplate vibration is shown to be affected by porosity, temperature rise,scale factors and viscous damping.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.92-97
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• 2002

We establish a visible light emission from porous polycrystalline silicon nano structure(PPNS). The PPNS layer are formed on heavily doped n-type Si substrate. 2um thickness of undoped polycrystalline silicon deposited using LPCVD (Low Pressure Chemical Vapor Deposition) anodized in a HF: ethanol(=1:1) as functions of anodizing conditions. And then a PPNS layer thermally oxidized for 1 hr at $900 ^{\circ}C$. Subsequently, thin metal Au as a top electrode deposited onto the PPNS surface by E-beam evaporator and, in order to establish ohmic contact, an thermally evaporated Al was deposited on the back side of a Si-substrate. When the top electrode biased at +6V, the electron emission observed in a PPNS which caused by field-induces electron emission through the top metal. Among the PPNSs as functions of anodization conditions, the PPNS anodized at a current density of $10mA/cm^2$ for 20 sec has a lower turn-on voltage and a higher emission current. Furthermore, the behavior of electron emission is uniformly maintained.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.129-139
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• 2018

The effects of N doping concentration and dopant moieties on the electrochemical properties of nanoporous graphene and their dependence on annealing temperature are investigated. Four types of N moieties - amide, amine, graphitic-N, and oxidized-N - are obtained, which transformed into pyridinic-N and pyrrolic-N upon annealing. The diffusion coefficient (D') of the ions in the electrode is the maximum at $400^{\circ}C$ because of a high level of N doping, whereas the second highest D0 value is obtained at $700^{\circ}C$ owing to a high level of reduction and N doping. The highest specific capacitance is obtained for the sample annealed at $400^{\circ}C$.

• Advances in nano research
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• v.7 no.4
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• pp.223-231
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• 2019

In this article the frequency response of magneto-flexo-electric rotary porous (MFERP) nanobeams subjected to thermal loads has been investigated through nonlocal strain gradient elasticity theory. A quasi-3D beam model beam theory is used for the expositions of the displacement components. With the aid of Hamilton's principle, the governing equations of MFERP nanobeams are obtained. Further, administrating an analytical solution the frequency problem of MFERP nanobeams are solved. In addition the numerical examples are also provided to evaluate the effect of nonlocal strain gradient parameter, hygro thermo environment, flexoelectric effect, in-plane magnet field, volume fraction of porosity and angular velocity on the dimensionless eigen frequency.

• Advances in aircraft and spacecraft science
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• v.6 no.4
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• pp.297-314
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• 2019

Dynamic stability of a porous metal foam nano-dimension plate on elastic substrate exposed to bi-axial time-dependent forces has been studied via a novel 3-variable plate theory. Various pore contents based on uniform and non-uniform models have been introduced. The presented plate model contains smaller number of field variables with shear deformation verification. Hamilton's principle will be utilized to deduce the governing equations. Next, the equations have been defined in the context of Mathieu-Hill equation. Correctness of presented methodology has been verified by comparison of derived results with previous data. Impacts of static and dynamical force coefficients, non-local coefficient, foundation coefficients, pore distributions and boundary edges on stability regions of metal foam nanoscale plates will be studied.

• Advances in nano research
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• v.7 no.5
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• pp.325-335
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• 2019

In the present study, nonlocal strain gradient theory (NSGT) is developed for wave propagation of functionally graded (FG) nanoscale plate in the thermal environment by considering the porosity effect. $Si_3N_4$ as ceramic phase and SUS304 as metal phase are regarded to be constitutive material of FG nanoplate. The porosity effect is taken into account on the basis of the newly extended method which considers coupling influence between Young's modulus and mass density. The motion relation is derived by applying Hamilton's principle. NSGT is implemented in order to account for small size effect. Wave frequency and phase velocity are obtained by solving the problem via an analytical method. The effects of different parameters such as porosity coefficient, gradient index, wave number, scale factor and temperature change on phase velocity and wave frequency of FG porous nanoplate have been examined and been presented in a group of illustrations.

• Structural Monitoring and Maintenance
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• v.6 no.2
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• pp.147-159
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• 2019

In present article, a size-dependent refined thick beam element has been established based upon nonlocal elasticity theory. Next, it is used to explore vibration response of porous metal foam nanobeams on elastic medium. The established beam element introduces ten degrees of freedom. Different porosity distributions called uniform, symmetric and asymmetric will be employed. Herein, introduced thick beam element contains shear deformations without using correction factors. Convergence and verification studies of obtained results from finite element method are also provided. The impacts of nonlocality factor, foundation factors, shear deformation, slenderness ratio, porosity kinds and porosity factor on vibration frequencies of metal foam nano-sized beams have been explored.

• Steel and Composite Structures
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• v.41 no.6
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• pp.821-829
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• 2021

Nonlinear dynamic response of a sandwich beam considering porous core and nano-composite face sheet on nonlinear viscoelastic foundation with temperature-variable material properties is investigated in this research. The Hamilton's principle and beam theory are used to drive the equations of motion. The nonlinear differential equations of sandwich beam respect to time are obtained to solve nonlinear differential equations by Homotopy perturbation method (HPM). The effects of various parameters such as linear and nonlinear damping coefficient, linear and nonlinear spring constant, shear constant of Pasternak type for elastic foundation, temperature variation, volume fraction of carbon nanotube, porosity distribution and porosity coefficient on nonlinear dynamic response of sandwich beam are presented. The results of this paper could be used to analysis of dynamic modeling for a flexible structure in many industries such as automobiles, Shipbuilding, aircrafts and spacecraft with solar easured at current time step and the velocity and displacement were estimated through linear integration.

• Advances in nano research
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• v.14 no.3
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• pp.295-302
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• 2023

The characteristics of motile microorganism and three dimensional Darcy-Forchheimer nanofluid flow by a porous rotatable disk with heat generation/absorption is reported. Thermophoretic and Brownian motion aspects are included by utilizing Buongiorno model. Moreover, slip conditions are considered on velocity, thermal, concentration and microorganism. Shooting procedure is implemented to find the numerical results of physical quantities are evaluated parametrically. The different physical parameters like heat sink/source parameter, thermal, Brownian number, thermophoresis parameter, concentration, Peclet number, bioconvected Lewis number, microorganism on concentration and density of motile microorganism distributions is considered. Graphs of concentration and microorganism are plotted to examine the influence of distinct prominent flow parameters.

• Nanomaterials
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• v.12 no.20
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• pp.3605-3620
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• 2022

Microtube-like porous carbon (MPC) and tube-like porous carbon-sulfur (MPC-S) composites were synthesized by carbonizing milkweed pappus with sulfur, and they were used as cathodes for lithium-sulfur batteries. The morphology and uniformity of these materials were characterized using X-ray powder diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy with an energy-dispersive X-ray analyzer, thermogravimetric analysis, and X-ray photoelectron spectrometry. The electrochemical performance of the MPC-S cathodes was measured using the charge/discharge cycling performance, C rate, and AC impedance. The composite cathodes with 93.8 wt.% sulfur exhibited a stable specific capacity of 743 mAh g^-1 after 200 cycles at a 0.5 C.