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41.
P.?G.?ChufyrevEmail author N.?V.?Sidorov N.?N.?Mel'nik 《Journal of Applied Spectroscopy》2005,72(5):667-670
Using the Raman scattering spectra, we investigated the ordering of the structural units in the cation sublattice and the
photorefractive properties of lithium niobate single crystals of variable composition, i.e., nominally pure ones with different
Li/Nb ratios and those doped with the nonphotorefractive cations Mg2+, Gd3+, and Y3+. It is shown that at low concentrations of Mg2+, Gd3+, and Y3+ the magnitude of the photorefractive effect is substantially determined by the ordering of the structural units of the cation
sublattice. It has been found for the first time that the intensity of the line corresponding to the bridge valence vibrations
of oxygen atoms in the octahedrons of NbO6 is sensitive to the dipole ordering of the cation sublattice of the crystal.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 611–614, September–October, 2005. 相似文献
42.
Applying the time-dependent density functional theory (TD-DFT) method the design of molecular logical functions from the dithieno[3,2-b:2,3-d]thiophene (thiophene) and azo-dye Disperse Orange 3 (DO3) molecules joined with various electron-insulator bridges is performed. Based on the results of the investigations, the main design rules for the selection of the bridge fragment between a photo-acceptor and photo-donor of a charge transfer molecular device are proposed. 相似文献
43.
Simon A. King 《Transactions of the American Mathematical Society》2004,356(11):4519-4542
We introduce a numerical isomorphism invariant for any triangulation of . Although its definition is purely topological (inspired by the bridge number of knots), reflects the geometric properties of . Specifically, if is polytopal or shellable, then is ``small' in the sense that we obtain a linear upper bound for in the number of tetrahedra of . Conversely, if is ``small', then is ``almost' polytopal, since we show how to transform into a polytopal triangulation by local subdivisions. The minimal number of local subdivisions needed to transform into a polytopal triangulation is at least . Using our previous results [The size of triangulations supporting a given link, Geometry & Topology 5 (2001), 369-398], we obtain a general upper bound for exponential in . We prove here by explicit constructions that there is no general subexponential upper bound for in . Thus, we obtain triangulations that are ``very far' from being polytopal. Our results yield a recognition algorithm for that is conceptually simpler, although somewhat slower, than the famous Rubinstein-Thompson algorithm.
44.
Existence results for some fourth-order nonlinear elliptic problems of local superlinearity and sublinearity 总被引:1,自引:0,他引:1
Guixiang Xu 《Journal of Mathematical Analysis and Applications》2003,281(2):633-640
In this paper we study the existence of positive solutions for the problem
(0.1) 相似文献
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交流电桥的示波器测量方法 总被引:1,自引:0,他引:1
传统的交流电桥教学采用毫伏表,本文给出了一种采用示波器的电桥教学与测量方法,能更直观展示电桥的幅、相关系,有更好的教学效果。 相似文献
48.
The influence of the thickness of a covering liquid layer and its viscosity as well as the impact velocity on energy loss during the normal impact on a flat steel wall of spherical granules with a liquid layer was studied. Free-fall experiments were performed to obtain the restitution coefficient of elastic–plastic Al2O3 granules by impact on the liquid layer, using aqueous solutions of hydroxypropyl methylcellulose with different concentrations for variation of viscosity (1–300 mPa s). In the presence of a... 相似文献
49.
为了提高声表面波传感器应变灵敏度,该文提出了一种桥型声表面波应变传感器。首先根据受压弯曲构件中应变分布特点设计了桥型声表面波应变传感器,并建立有限元模型,结合微扰法分析了桥型结构几何参数与声表面波应变传感器灵敏度的关系。根据分析结果确定桥型声表面波应变传感器几何结构参数,并与传统声表面波应变传感器的应变灵敏度进行了对比研究,在此基础上搭建受压弯曲微动平台开展实验研究,结果表明:在直梁构件受压弯曲应变测量时,Y34°切向的桥型声表面波应变传感器的应变灵敏度为1692 Hz/με,传统声表面波传感器应变灵敏度为1328 Hz/με,桥型声表面波应变传感器的应变灵敏度较传统声表面波应变传感器有明显提高。 相似文献
50.