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101.
Thermoelastic buckling behavior of thick rectangular plate made of functionally graded materials is investigated in this article.
The material properties of the plate are assumed to vary continuously through the thickness of the plate according to a power-law
distribution. Three types of thermal loading as uniform temperature raise, nonlinear and linear temperature distribution through
the thickness of plate are considered. The coupled governing stability equations are derived based on the Reddy’s higher-order
shear deformation plate theory using the energy method. The resulted stability equations are decoupled and solved analytically
for the functionally graded rectangular plates with two opposite edges simply supported subjected to different types of thermal
loading. A comparison of the present results with those available in the literature is carried out to establish the accuracy
of the presented analytical method. The influences of power of functionally graded material, plate thickness, aspect ratio,
thermal loading conditions and boundary conditions on the critical buckling temperature of aluminum/alumina functionally graded
rectangular plates are investigated and discussed in detail. The critical buckling temperatures of thick functionally graded
rectangular plates with various boundary conditions are reported for the first time and can be served as benchmark results
for researchers to validate their numerical and analytical methods in the future. 相似文献
102.
In this research work, an exact analytical solution for buckling of functionally graded rectangular plates subjected to non-uniformly
distributed in-plane loading acting on two opposite simply supported edges is developed. It is assumed that the plate rests
on two-parameter elastic foundation and its material properties vary through the thickness of the plate as a power function.
The neutral surface position for such plate is determined, and the classical plate theory based on exact neutral surface position
is employed to derive the governing stability equations. Considering Levy-type solution, the buckling equation reduces to
an ordinary differential equation with variable coefficients. An exact analytical solution is obtained for this equation in
the form of power series using the method of Frobenius. By considering sufficient terms in power series, the critical buckling
load of functionally graded plate with different boundary conditions is determined. The accuracy of presented results is verified
by appropriate convergence study, and the results are checked with those available in related literature. Furthermore, the
effects of power of functionally graded material, aspect ratio, foundation stiffness coefficients and in-plane loading configuration
together with different combinations of boundary conditions on the critical buckling load of functionally graded rectangular
thin plate are studied. 相似文献
103.
Enrique de Amo Imen Bhouri Juan Fernández-Sánchez 《Rendiconti del Circolo Matematico di Palermo》2011,60(3):469-476
In this work we study the some general fractal sums of pulses defined in ? by: $$F(t) =\sum^{+\infty}_{n=1}a_nG(\lambda_n^{-1}(t-X_n))$$ where (a n ), (λ n ) two positive scalar sequences such that ∑a n is divergent, and (λ n ) is non-increasing to 0, G is an elementary bump and X n are independent random variables uniformly distributed on a sufficiently large domain Ω. We investigate the Hausdorff dimension of the graph of G and in particular we answer a question given by Tricot in (Courbes et dimensions fractales, Springer, Berlin, 1995). 相似文献
104.
Imen Ben Hassen 《Journal of Functional Analysis》2011,260(10):2933-2963
We estimate the rate of decay of the difference between a solution and its limiting equilibrium for the following abstract second order problem
105.
Tabbene O Karkouch I Slimene IB Elfeddy N Cosette P Mangoni ML Jouenne T Limam F 《Applied biochemistry and biotechnology》2011,164(1):34-44
When cultured in minimal growth medium, the B38 strain of Bacillus subtilis did not exhibit any antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) clinical isolate. Coculturing B38 strain with viable MRSA cells weakly increased antibacterial activity production
(20 AU/ml). Addition of dead MRSA cells in a B38 culture, increased by 8-fold the B. subtilis strain antibacterial activity reaching 160 AU/ml against MRSA strain. This antibacterial activity recovered from cell-free
supernatants was stimulated by an autoinducing compound which is sensitive to the action of proteinase K suggesting a proteinaceous
nature. This compound was heat-stable till 80 °C and showed a molecular mass around 20 kDa as determined by SDS-PAGE. These
results suggest that the production of antibacterial compounds by B38 strain is dependent on the amount of the autoinducing
compound. 相似文献
106.
Martins N Mateus N Vinci D Saidi O Brigas A Bacsa J Xiao J 《Organic & biomolecular chemistry》2012,10(20):4036-4042
A new ferrocenyl oxazaphospholidine oxide 3 was synthesized together with its P-epimer 2 in the reaction of ferrocene lithium with phosphoramidite chloride 1. 3 was successfully derivatized into planar chiral 1,2-ferrocenes, including phosphine ligands, via highly diastereoselective ortho-lithiation and subsequent functionalization; these compounds display opposite planar chirality to those obtained from 2. Some of these 1,2-ferrocenes were further lithiated, allowing for the introduction of a free phosphine group at the oxazaphospholidine ring. The X-ray structures of the compounds 2 and 3 as well as those of the new 1,2-ferrocenes 4 and 7 have been determined. 相似文献
107.
The crystal structure, the 13C NMR spectroscopy and the complex impedance have been carried out on [Cd3(SCN)2Br6(C2H9N2)2]n. Crystal structure shows a 2D polymeric network built up of two crystallographically independent cadmium atoms with two different octahedral coordinations. This compound exhibits a phase transition at (T=355±2 K) which has been characterized by differential scanning calorimetry (DSC), X-rays powder diffraction, AC conductivity and dielectric measurements. Examination of 13C CP/MAS line shapes shows indirect spin–spin coupling (14N and 13C) with a dipolar coupling constant of 1339 Hz. The AC conductivity of this compound has been carried out in the temperature range 325–376 K and the frequency range from 10−2 Hz to 10 MHz. The impedance data were well fitted to two equivalent electrical circuits. The results of the modulus study reveal the presence of two distinct relaxation processes. One, at low frequency side, is thermally activated due to the ionic conduction of the crystal and the other, at higher frequency side, gradually disappears when temperature reaches 355 K which is attributed to the localized dipoles in the crystal. Moreover, the temperature dependence of DC-conductivity in both phases follows the Arrhenius law and the frequency dependence of σ(ω,T) follows Jonscher's universal law. The near values of activation energies obtained from the conductivity data and impedance confirm that the transport is through the ion hopping mechanism. 相似文献
108.
A. Kashefi M. Mahdinia B. Firoozabadi M. Amirkhosravi G. Ahmadi M.S. Saidi 《Acta Mechanica Sinica》2014,30(2):259-273
This study describes a multidimensional 3D/lumped parameter(LP) model which contains appropriate inflow/outflow boundary conditions in order to model the entire human arterial trees. A new extensive LP model of the entire arterial network(48 arteries) was developed including the effect of vessel diameter tapering and the parameterization of resistance, conductor and inductor variables. A computer aided-design(CAD) algorithm was proposed to effciently handle the coupling of two or more 3D models with the LP model, and substantially lessen the coupling processing time. Realistic boundary conditions and Navier–Stokes equations in healthy and stenosed models of carotid artery bifurcation(CAB) were used to investigate the unsteady Newtonian blood flow velocity distribution in the internal carotid artery(ICA). The present simulation results agree well with previous experimental and numerical studies. The outcomes of a pure LP model and those of the coupled 3D healthy model were found to be nearly the same in both cases. Concerning the various analyzed 3D zones, the stenosis growth in the ICA was not found as a crucial factor in determining the absorbing boundary conditions.This paper demonstrates the advantages of coupling local and systemic models to comprehend physiological diseases of the cardiovascular system. 相似文献
109.
110.
O. Mounkachi A. El Kenz E.H. Saidi 《Journal of magnetism and magnetic materials》2009,321(16):2402-2406
By ab-initio calculation we show that the (Ga,Fe)N ground state may be changed from anti-ferromagnetic to ferromagnetic by acceptor defect like Ga vacancies. The electronic structures are calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that we can increase the magnetic moment of Fe in p-type GaN by oxygen co-doping. Mechanism of exchange interactions between magnetic ions in p-type (Ga,Fe)N is also studied. The effect of external magnetic field on the electronic structure of (Ga, Fe)N and p-type (Ga, Fe)N is investigated. 相似文献