نتایج جستجو برای: Surface effect

تعداد نتایج: 2188158  

پایان نامه :وزارت علوم، تحقیقات و فناوری - پژوهشگاه پلیمر و پتروشیمی ایران - پژوهشکده پتروشیمی 1389

this is an original study on the effect of a polyisobutylene – polydimethylsiloxane (pibpdms) block copolymer modifier used as an interfacial active agent on the dynamics behaviour of single newtonian drops suspended in a polyisobutylene (pib) newtonian matrix. the results were divided in two sections. the first part included the experiments carried out on the non-modified and 2% block cop...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده مهندسی 1392

flow in natural river bends is a complex and turbulent phenomenon which affects the scour and sedimentations and causes an irregular bed topography on the bed. for the reason, the flow hydralics and the parameters which affect the flow to be studied and understand. in this study the effect of bed and wall roughness using the software fluent discussed in a sharp 90-degree flume bend with 40.3cm ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده علوم 1390

a novel silver (ag) nanocomposite electrode was proposed that fabricated from metal nanostructures and ionic liquids. the combined application of unique properties of nanomaterials and ionic liquids in the design of this ag nanocomposite results in electrodes with interesting advantages compared to the conventional metal disk electrode. in the first part of this thesis, the elecrocatalytic eff...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده علوم 1391

in this thesis protic and aprotic ammonium-based ionic liquids were synthesized and their surface tensions were measured in the range of 298-373k. the protics are alkyl ammonium-based ils with the carboxylate (formate, acetate, propionate) anion and aprotics are quaternary ammonium-based ils with bis(trifluoromethylsulfonyl)imide anion. capillary rise method was used for surface tension measure...

Journal: :iranian journal of oil & gas science and technology 2014
kobra kalvandi sina sodagar

resonances are intrinsic characteristics of an elastic object, which are completely independent of thesource of excitation. the appropriate utilization of the information contained within the resonancespectra and the identification of the resonance frequencies of the object can be used as a potent toolfor material characterization. in this paper, a new mathematical model for the wave diffractio...

پایان نامه :وزارت علوم، تحقیقات و فناوری - پژوهشگاه دانشهای بنیادی (مرکز تحقیقات فیزیک نظری و - پژوهشکده علوم نانو 1392

among the low–dimensional allotropes of carbon, nanotubes and graphene have attracted very much attention from nano–science and nanotechnology specialists. they have been proposed as building blocks in nanometer device engineering. however, these structures are not defect–free. in this thesis, we focused on defective carbon nanotubes and graphene, and studied the effect of couple of very common...

Journal: :journal of ultrafine grained and nanostructured materials 2015
hessam rouhi reza ansari mansour darvizeh

it has been revealed that the surface stress effect plays an important role in the mechanical behavior ofstructures (such as bending, buckling and vibration) when their dimensions are on the order ofnanometer. in addition, recent advances in nanotechnology have proposed several applications fornanoscale shells in different fields. hence, in the present article, within the framework of surfaceel...

Journal: :journal of nanostructures 2014
m. mohammadimehr b. rousta navi a. ghorbanpour arani

in this research, the surface stress effect on the nonlocal vibration of piezoelectric square plate reinforced by single walled carbon nanotubes (swcnts) based on classical plate theory (cpt) and first order shear deformation theory (fsdt) is presented. the elastic properties of piezoelectric nanocomposite plate are estimated by eshelby-mori-tanaka and the extended mixture rule approaches. the ...

Behnam Gheshlaghi Jafar Eskandari Jam Yaser Mirzaei,

In this work,The free nonlinear vibrations of nanotubes using the Euler-Bernoulli beam theory along with the von Kármán geometric nonlinearity in presence of surface effects has been investigated. Natural frequencies of a simply-supported nanotube in terms of the Jacobi elliptic functions are obtained by using the free vibration modes of the corresponding linear problem. The numerical results d...

Journal: :international journal of nano dimension 0
j. e. jam composite materials and technology center, mut, tehran, iran. a. t. samaei composite materials and technology center, mut, tehran, iran.

in this paper, the modified euler-bernoulli beam model is presented to examine the influence of surface elasticity and residual surface tension on the critical force of axial buckling of nanotubes in the presence of rotary inertia. an explicit solution is derived for the buckling loads of microscaled euler beams considering surface effects. the size-dependent buckling behavior of the nanotube d...

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