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121.
X. F. Xu N. Xu W. Hu J. D. Wu Y. Q. Shen Z. F. Ying 《Applied Physics A: Materials Science & Processing》2009,96(2):415-421
The Fourier transform infrared (FTIR) spectra and switching current response in sodium nitrite:poly(vinyl alcohol) nanocomposite
films have been studied as a function of composition of NaNO2. The switching current data fitted well to infinite-grain model (IGM) in the region t<t
s
and to finite-grain model (FGM) in the region t≥t
s
. The microscopic parameters like the dimensionality, the domain wall velocity, and the nucleation rate have been evaluated
which provide more physical insight of the switching phenomena in the composite films. The polarization current and nucleation
rate are optimum in 50 wt.% composite film and have been discussed in terms of grain size and strain variations with the composition.
The effect of applied field and pulse width variation on the switching behavior of 50 wt.% composition has also been studied.
The exponential field dependence of the domain wall velocity and the nucleation rate indicate that nucleation mechanism is
responsible for switching phenomena in the composite films. The writing pulse width affects significantly on the switching
behavior of the composite films. 相似文献
122.
The multi-scale analysis of fracture toughness of ferroelectric ceramics under complicate mechanical–electrical coupling effect is carried out in this paper. The generalized stress intensity factor (SIF) arising from spontaneous strains and polarization transformation in switching domain zones is accurately obtained by using an extended Eshelby theory. Taking BaTiO3 ferroelectric ceramic for example, it is discovered that the crack propagation can be induced by domain switching arising from negative electrical field when the crack surface is parallel to the isotropic plane, and the obtained critical electric displacement intensity factor (EDIF) approximates closely to that obtained by the Green’s function method. Additionally, as pinning dislocations and slip dislocations can strongly influence properties of ferroelectric devices and induce the property degradation, it is necessary to investigate the dislocation toughening effects on fatigue and fracture mechanisms. The results show that the dislocation shielding and anti-shielding effects on mode II SIF, mode I SIF and EDIF are obviously different when a dislocation locates at a position near the crack tip. Through the calculation of the critical applied EDIF for crack propagation by using mechanical energy release rate (MERR) theory, it is discovered that the slip angles obviously influence fracture toughness, and the mode II SIF arising from dislocation has little influence on fracture toughness, however, the mode I SIF and EDIF arising from dislocation have great influences on fracture toughness. 相似文献
123.
T. Zhang X. G. Li X. P. Wang Q. F. Fang M. Dressel 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(3):309-312
Using different temperature and field protocols, the memory behaviors in the dc magnetization and magnetic relaxation are
observed at temperature below blocking temperature TB = 93 K in weakly interacting manganite La0.6Pb0.4MnO3 nanoparticles. The results indicate that the magnetic dynamics of this nanoparticle system is strongly correlated with a
wide distribution of particle relaxation times, which may arise from the particle weak interaction and distribution of the
particle size. 相似文献
124.
Excited light and corresponding intrinsic fluorescence diffusion inside teeth tissue are an essential problem for light-based
carious lesion detection. Based on finite element numerical analysis of diffusion equation, the photon density distribution
of both excited light and autofluorescence of 2D premolar teeth model is obtained. The dependence of excited light and autofluorescence
density distribution inside the teeth model on the scattering coefficient of enamel (5–25 mm−1) and dentine (100–140 mm−1) is numerically simulated and analyzed. The fitted results reveal that fluorescence intensity decreases exponentially. Optical
penetration depth and fluorescence relative depth declined with the increment of scattering coefficient of enamel. And the
dentine had the opposite effect. Finally, the experiment of measurement of fluorescence intensity on the teeth surface is
conducted and the result is compared with the numerical computation. 相似文献
125.
H. C. Guo X. H. Zhang S. H. Tang Y. Q. Qin Y. Y. Zhu 《Applied physics. B, Lasers and optics》2010,98(2-3):253-259
With the nonlinear diffraction concept, we present a diffractive study of optical parametric interactions in nonlinear photonic crystals. The nonlinear diffraction concept enables the design of complicated nonlinear photonic crystal structures in an intuitive way. We show that there are two basic linear sequences, the anti-stacking and the para-stacking sequences, existing in a one-dimensional structure; and we present the realization of multiple phase-matching resonances in the combination of the two basic sequences. The parameters affecting the structure factor of a two-dimensional nonlinear photonic crystal are investigated, which indicate that not only the Ewald construction but also the relative domain size determines two-dimensional nonlinear diffractions. 相似文献
126.
127.
Housheng Su Ningzi Zhang Michael Z.Q. Chen Hongwei Wang Xiaofan Wang 《Nonlinear Analysis: Real World Applications》2013,14(1):798-806
This paper investigates adaptive flocking of multi-agent systems (MASs) with a virtual leader. All agents and the virtual leader share the same intrinsic nonlinear dynamics, which satisfies a locally Lipschitz condition and depends on both position and velocity information for the agent itself. Under the assumption that the initial network is connected, an approach to preserving the connectivity of the network is proposed. On the basis of the Lyapunov stability theory, an adaptive flocking control law is derived, for making the MASs track the virtual leader without collision. Finally, a numerical example is presented to illustrate the effectiveness of the theoretical results. 相似文献
128.
C. Feng X.B. GuoX.P. Zhang X.X. LuB. Wei W. ChenY. Zhang Q.R. LiZ.J. Ying B.S. Cao 《Physica C: Superconductivity and its Applications》2010,470(21):1959-1961
This paper presents the design, fabrication, and performance of a compact high temperature superconducting duplexer at VHF-band. The duplexer consists of a T-junction and two four-pole filters with an ultra-narrow bandwidth of 400 kHz at 216 MHz and 220 MHz, respectively. By using gap-coupled feedlines in the filter design procedure, the duplexer is constructed by connecting the two filters using a T-junction with short-length branches. The two filters are fabricated on separate substrates and are carefully packaged to achieve a high isolation between the duplexer channels. The duplexer has a compact size of 41.6 mm × 28 mm. The measured results at 73 K show a high performance. The return loss is −17 dB, the insertion losses of both channels are less than 0.16 dB, and the out-of-band rejections are higher than 60 dB. The isolation between the two channels is better than 76 dB. 相似文献
129.
L.?Q.?Chen X.?Liu J.?T.?Chen Z.?C.?Zhang J.?L.?LiEmail author L.?J.?Wang W.?Jiang 《Applied Physics A: Materials Science & Processing》2012,106(4):785-789
Graphene/carbon composite films were prepared by electrospraying a graphene/polyacrylonitrile composite solution on SiO2-coated silicon substrates and subsequent heat treatment. The as-produced graphene/carbon composite films had a porous structure
comprising graphene layers. With a magnetic field applied perpendicularly to the sample, an unexpectedly significant positive
magnetoresistance attributed to e–e interaction and weak localization has been observed, which constantly increases with the
magnetic field in the temperature range of 300–50 K from 0 to 80 kOe. 相似文献
130.
The retention characteristics of 25 2-cyano-3-methylthio-3-substituted amine-acrylates are determined using reversed-phase thin-layer chromatography (RP-TLC) with methanol-water mixtures as eluents. The relationship between Rm values and partition coefficients (C log P) are established. The Rm values decrease linearly with increasing methanol concentration in the eluent. The Rm values extrapolated to zero organic modifier concentration (Rm0) in the eluent are highly related to C log P. The Rm0 value can be used to evaluate the lipophilicity of this kind of compound. 相似文献