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991.
Recently, a 4-node quadrilateral membrane element AGQ6-I, has been successfully developed for analysis of linear plane problems. Since this model is formulated by the quadrilateral area coordinate method (QACM), a new natural coordinate system for developing quadrilateral finite element models, it is much less sensitive to mesh distortion than other 4-node isoparametric elements and free of various locking problems that arise from irregular mesh geometries. In order to extend these advantages of QACM to nonlinear applications, the total Lagrangian (TL) formulations of element AGQ6-I was established in this paper, which is also the first time that a plane QACM element being applied in the implicit geometrically nonlinear analysis. Numerical examples of geometrically nonlinear analysis show that the presented formulations can prevent loss of accuracy in severely distorted meshes, and therefore, are superior to those of other 4-node isoparametric elements. The efficiency of QACM for developing simple, effective and reliable serendipity plane membrane elements in geometrically nonlinear analysis is demonstrated clearly. 相似文献
992.
Rapid solidification processing (cooling rate from the interval 105–106 K s−1) was used to prepare deeply undercooled cryolite-alumina melts. Such prepared samples were analyzed by the XRD method. Besides
cryolite, XRD patterns belonging to ι-Al2O3 were recorded. The influence of annealing on the XRD patterns of deeply undercooled melts was also investigated. 相似文献
993.
It is shown that in a closed equispaced three-level ladder system, by controlling the relative phase of two applied coherent fields, the conversion from absorption with inversion to lasing without inversion (LWI) can be realized; a large index of the refraction with zero absorption can be gotten; considerable increasing of the spectrum region and value of the LWI gain can be achieved. Our study also reveals that the incoherent pumping will produce a remarkable effect on the phase-dependent properties of the system. Modifying value of the incoherent pumping can change the property of the system from absorption to amplification and enhance significantly LWI gain. If the incoherent pumping is absent, we cannot get any gain for any value of the relative phase. 相似文献
994.
Y.S. Fu Y.F. Song S.A. Kulinich J. Sun J. Liu X.W. Du 《Journal of Physics and Chemistry of Solids》2008,69(4):880-883
The nanostructure of a single-crystal ZnO flocky sphere was synthesized by using a simple chemical route in the Zn2+–triethanolamine system. Formation of such quasi-single-crystal nanostructures was achieved through oriented attachment of a large number of ZnO nanoparticles in three dimensions. It is suggested that the adsorption of triethanolamine molecules on the surface of ZnO particles plays an important role in their oriented attachment, leading to the formation of flocky spheres with single-crystal structure. 相似文献
995.
Li Liu Ling‐Xiang Qiao Shi‐Zhong Liu Dong‐Mei Cui Chun‐Mei Zhang Zheng‐Ji Zhou Zu‐Liang Du Wai‐Yeung Wong 《Journal of polymer science. Part A, Polymer chemistry》2008,46(10):3193-3206
A new family of organometallic/inorganic composite Langmuir‐Blodgett (LB) films consisting of rigid‐rod polyplatinayne polymer ([Pt‐T(OMe‐Fl)T]∞ or [Pt‐T(F‐Fl)T]∞, where the triplet bonds are abbreviated by T, and fluorene ring by Fl) as the π‐conjugated organometallic molecule, polyoxometalate (POM, POM = K3PMo12O40, H3PW12O40, or H6P2W18O62) of the Keggin and Dawson structures as the inorganic component, and dimethyldioctadecylammonium bromide (DODA) or a mixture of octadecanoic acid (OA) and docosanoic acid (DA) as the auxiliary film‐forming agent were prepared and characterized by π–A isotherms, UV–Vis absorption spectra, photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low‐angle X‐ray diffraction. Our experimental results indicate that steady, even, and ordered Langmuir and LB films are formed in pure water and polyoxometalate subphases. It was shown that the POM molecules are probably embedded inside the polyplatinayne molecules in the LB film structure and they can quench the luminescence of the Pt polyyne. These Pt‐polyyne based LB films display interesting electric conductivity behavior. [Pt‐T(OMe‐Fl)T]∞/DODA/HPW12 monolayer film shows a good electrical conductivity, and the tunneling current amounts to ±100 nA when the voltage is set at ±8 V. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3193–3206, 2008 相似文献
996.
An approach for solving Fredholm integral equations of the first kind is proposed for in a reproducing kernel Hilbert space (RKHS). The interest in this problem is strongly motivated by applications to actual prospecting. In many applications one is puzzled by an ill-posed problem in space C[a,b] or L2[a,b], namely, measurements of the experimental data can result in unbounded errors of solutions of the equation. In this work, the representation of solutions for Fredholm integral equations of the first kind is obtained if there are solutions and the stability of solutions is discussed in RKHS. At the same time, a conclusion is obtained that approximate solutions are also stable with respect to ∞ or L2 in RKHS. A numerical experiment shows that the method given in the work is valid. 相似文献
997.
In pH 5.5 phosphate buffer solution,N-n-undecyl-N'-(sodium-p-amino-benzenesulfonate)thiourea(UPT)produced a pair of redox peaks on the bare glassy carbon electrode.At the multi-walled carbon nanotube(MWNT)modified electrode,the electrochemical behavior of UPT enhanced greatly.In the presence of bovine serum albumin (BSA),the peak currents of UPT decreased linearly due to the formation of a super-molecular complex.This method was successfully applied to the determination of BSA in a bovine serum sample. 相似文献
998.
999.
In this paper, we first establish some existence theorems of systems of generalized vector equilibrium problems. From these
results, we obtain new variants of Ekeland’s variational principle in a Hausdorff t.v.s., a minimax theorem and minimization
theorems. Some applications to the existence theorem of systems of semi-infinite problem, a variant of flower petal theorem
and a generalization of Schauder’s fixed point theorem are also given. 相似文献
1000.
Ordered ferromagnetic-nonmagnetic heterogeneous Fe60Pb40 nanowire arrays were successfully fabricated by alternating current (AC) electrodeposition into nanoporous alumina templates. Transmission electron microscopy (TEM) image and selected-area diffraction (SAED) pattern analysis showed that the Fe60Pb40 nanowires are polycrystalline with an average diameter of 22 nm and lengths up to several micrometers. X-ray diffraction (XRD) observations indicated that α-Fe and fcc Pb phase coexist and do not form metastable alloy phase. The as-deposited samples were annealed at 200, 300, 400 and 500 °C, respectively. Magnetic measurements showed that nanowires have high magnetic anisotropy with their easy axis parallel to the nanowire arrays, and the coercivity of the samples increased with the annealing temperature up to 400 °C and reached a maximum (2650 Oe). The change of magnetic properties associated with the microstructure was discussed. 相似文献