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ASYMPTOTIC LIMITS AND STABILIZATION FOR THe 1D NONLINeAR MINDLIN-TIMOSHeNKO SYSTeM

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Journal of Systems Science & Complexity 2010年第3期23卷 414-430页

作者： F.D.ARARUNA P.BRAZ e SILVA e.ZUAZUA Departamento de Matemática Universidade Federal da Paraíba Departamento Ikerbasque Research Professor Basque Center for Applied Mathematics(BCAM)

This paper shows how the so called von Karman model can be obtained as a singular limit of a modified Mindlin-Timoshenko system when the modulus of elasticity in shear κ tends to infinity, provided a regularizing term through a fourth order dispersive operator is added. Introducing damping mechanisms, the authors also show that the energy of solutions for this modified Mindlin-Timoshenko system decays exponentially, uniformly with respect to the parameter k. As κ→∞, the authors obtain the damped von Karman model with associated energy exponentially decaying to zero as well.

关键词： Mindlin-Timoshenko system singular limit uniform stabilization vibrating beams von Karman system.

exact Solutions of Kolmogorov-Petrovskii-Piskunov equation Using the Modified Simple equation Method

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Acta Mathematicae Applicatae Sinica 2014年第3期30卷 749-754页

作者： e.M.e.Zayed S.A.Hoda Ibrahim Mathematics Department Faculty of ScienceZagazig University

The modified simple equation method is employed to find the exact solutions of the nonlinear Kolmogorov-Petrovskii-Piskunov （KPP） equation. When certain parameters of the equations are chosen to be special values, the solitary wave solutions are derived from the exact solutions. It is shown that the modified simple equation method provides an effective and powerful mathematical tool for solving nonlinear evolution equations in mathematical physics.

关键词： modified simple equation method Kolmogorov-Petrovskii-Piskunov equation exact solutions solitary wave solutions

SOMe OSCILLATION CRITeRIA FOR SeCOND ORDeR NONLINeAR FUNCTIONAL ORDINARY DIFFeReNTIAL eQUATIONS

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Acta Mathematica Scientia 2007年第3期27卷 602-610页

作者： e.M.e.Zayed M.A.el-Moneam Mathematics Department Faculty of ScienceZagazig UniversityZagazigEgypt

The main objective of this article is to study the oscillatory behavior of the solutions of the following nonlinear functional differential equations（a（t）x＇（t））＇＋δ1p（t）x＇（t）＋δ2q（t）f（x（g（t））） = 0,for 0 ≤ to≤ t, where 51 = ：el and δ±1. The functions p,q,g ： [t0, ∞） → R, f ： R → are continuous, a（t）〉 0,p（t） ≥0,q（t）〉 0 for t ≥ to,lirn g（t） = ∞, and q is not identically zero on any subinterval of [to, ∞）. Moreover, the functions q（t）, g（t）, and a（t） are continuously differentiable.

关键词： Oscillatory and nonoscillatory solutions nonlinear functional differential equations

SOMe ReMARKS ON HYDROFOIL CAVITATION

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Journal of Hydrodynamics 2012年第3期24卷 305-314页

作者： ARNDT Roger e. A. Saint Anthony Falls Laboratory University of Minnesota MinneapolisMN 55414 USA

This paper reviews numerical and experimental investigations of sheet/cloud cavitation carried out at the St. Anthony Falls Laboratory and at two collaborating facilities （Versuchsanstalt Ftir Wasserbau, Obernach, Germany and Osaka University, Japan） for more than a decade. Although significant advances have been made in the analysis of this flow several issues are still unresolved. The purpose of this paper is to examine the overall features of the problem, review the progress made to date and suggest avenues for new investigation.

关键词： cavitation hydrofoil numerical simulations

Improvement of sintering,nonlinear electrical,and dielectric properties of ZnO-based varistors doped with TiO2

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Chinese Physics B 2016年第6期25卷 575-580页

作者： Osama A Desouky K e Rady Bilbis Higher Institute of engineering (BHIe) Bilbis Sharqia Egypt engineering Basic Sciences Department Faculty of engineering Menoufia University Shebin EI-Kom Egypt

The effects of TiO2 on sintering and nonlinear electrical properties of（98.5-x）ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2（x = 0.3,0.5,0.7,0.9 mol%） ceramic varistors prepared by the ceramic technique are investigated in this *** optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption *** optimum sintering temperature is found to be 1200℃,at which each of the samples shows a maximum firing shrinkage and minimum water *** minimum water absorption appears in a sample of x = 0.9 mol%.Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase *** crystal size of ZnO decreases with increasing TiO2 *** addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x = 0.7 mol% of TiO2,further addition negatively affects it.A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 *** temperature and composition dependences of the dielectric constant and AC conductivity are also *** increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.

关键词： ZnO varistors water absorption nonlinear electrical properties dielectric constant

Destructive Interactions between Pore Forming Agents and Matrix Phase during the Fabrication Process of Porous BiFeO_3 Ceramics

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Journal of Materials Science & Technology 2015年第8期31卷 798-805页

作者： e.Mostafavi A.Ataie School of Metallurgy and Materials engineering College of EngineeringUniversity of Tehran

Porous bismuth ferrite ceramics were synthesized by sacrificial pore former method. A mixture of BiFeO3 and 20 wt% of various pore formers including high density polyethylene, polyethylene glycol, polyvinyl alcohol, urea and graphite was intensively milled for 10 h in a planetary ball mill, uniaxially cold pressed and then subjected to the multi-stage heat treatment. The results revealed that urea and polyvinyl alcohol are appropriate candidates for maintaining the strength of the final porous structure. Density and porosity measurements showed that by employing 20 wt% of high density polyethylene and graphite, a porous sample with a maximum porosity of nearly 40% could be obtained. Mercury porosimetry results showed that using urea as a pore former gives porous bismuth ferrite with a mean pore diameter of 7μm, uniform pore distribution as well as interconnected pores. Moreover, reactions between BiFeO3 matrix phase and thermal decomposition products of pore formers can lead to degradation of the BiFeO3 phase in the final porous samples. Analysis of X-ray diffraction patterns illustrated that in the samples pro- cessed with graphite, high density polyethylene and polyvinyl alcohol as pore former, BiFeO3 matrix phase partially or completely decomposed to intermediate phases of Bi2Fe4O9 and Bi25FeO40. Using of urea did not damage the matrix phase and porous BiFeO3 within the original perovskite structure could be prepared. Furthermore, thermodynamic investigation was carried out for prediction of possible in- teractions between matrix phase and pore former at elevated temperatures.

关键词： Multiferroic Bismuth ferrite Porous ceramics Sacrificial pore former Porosity Phase composition

electronic,optical,and mechanical properties of BN,AlN,and InN with zinc-blende structure under pressure

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Chinese Physics B 2017年第8期26卷 320-327页

作者： A R Degheidy e B elkenany Department of Physics Faculty of ScienceMansoura UniversityP.O.Box 35516MansouraEgypt

In this work, the electronic, optical, and mechanical properties of BN, AlN, and InN under the action of pressure are calculated. For each of these compounds, the energy band structure, band gaps（e^L_g, e~Γ_g, e^X_g）, refractive index（n）,dielectric constants（ε_∞, ε_0）, elastic constants（C_11, C_12, C_44）, and relevant parameters such as bulk（B_u）, shear（S_h）, and Young＇s（Y_0） moduli are studied, and other important parameters such as bond-stretching（α）, bond-bending（β） force constant, internal-strain parameter（ζ）, effective charges（e~＊_T, Z~＊）, anisotropy factor（I_s）, Poisson＇s ratio（P_o）, Cauchy ratio（C_a）, the ductility index（μ_D）, and linear compressibility（C0_） are also calculated. The effects of pressure on all studied properties are investigated. Our results are in good agreement with the available experimental and theoretical data for BN,AlN, and InN.

关键词： electronic properties optical properties mechanical properties BN A1N InN

Schrodinger equation for an Open System

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Chinese Physics Letters 2002年第9期19卷 1238-1243页

作者：毕桥 H.e.Ruda ComplexityScienceCenter YangzhouUniversityYangzhou225002 energeniusCentreforAdvancednanotechnology UniversityofTorontoTorontoM5S3E4Canada

We present a Schr?dinger (Liouville) type of equation for a quantum open system. It has a correlated part, and various master equations may be its special cases. It also has significant applications for constructing decoherence-free subspace for quantum computation. It is related to the original Schrodinger (Liouville) equation for the total system through a non-unitary similarity transformation. It is unnecessary for its correlated part to be self-adjoint, so there is a complex spectrum for the corresponding Hamiltonian (Liouvillian), which enables the time evolution of states to be asymmetric. This shows just the correlation to produce evolution of world.

关键词： Liouville equation

Heavy metals partitioning in the sediments of Izmir Inner Bay

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Journal of environmental Sciences 2008年第4期20卷 413-418页

作者： GUVeN Duyusen e AKINCI Gorkem Dokuz eylul University Faculty of Engineering Department of Environmental EngineeringKaynaklar Campus35160BucalzmirTurkey.

Izmir Bay is known to be polluted by high concentrations of heavy metals and organic pollutants. Sediment samples taken from 7 different stations in Izmir Inner Bay were analyzed for their total organic matter content and, Cu, Cr, Pb and Zn. In addition, the chemical distribution of the metals were determined by means of the BCR （Community Bureau of Reference） extraction Procedure （developed by european Commission for Standards, Measurement and Testing） which allows the determination of metals bound as four fractions; exchangeable and acid soluble, reducible （bound to iron-manganese oxides）, oxidizable （bound to organics） and residual. The results show that Izmir Inner Bay contains sediments with high metal concentrations. According to the chemical distribution of metals, Cr and Cu tend to accumulate mostly on the organic fraction of the sediment. Pb is mostly found in the reducible fraction where Zn is mobile in the sediment, and it is distributed evenly on each fraction.

关键词： heavy metal pollution Izmir Inner Bay sediment sequential extraction