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51.
The problem of robust stability of a singular time-delay system is investigated. A novel Lyapunov–Krasovskii functional (LKF) is introduced which is a singular-type complete quadratic Lyapunov–Krasovskii functional with polynomial parameters. Stability conditions are derived in the form of linear matrix inequalities. Numerical examples are given to illustrate the effectiveness and lower conservatism of the new proposed stability criterion. 相似文献
52.
Jian-Lin Li 《Journal of Functional Analysis》2011,260(4):1086-1095
In the present paper we will study the spectral property of a class of self-affine measures under the condition of compatible pair. We first answer a question of Dutkay and Jorgensen concerning the relationship between spectral self-affine measure and compatible pair. We then consider the spectra of Bernoulli convolutions and obtain a sharp result which extends the corresponding result of Jorgensen, Kornelson and Shuman. Finally, we provide a structural property for the integer spectrum of a spectral self-affine measure. 相似文献
53.
This paper is concerned with the existence and stability of periodic traveling curved fronts for reaction-diffusion equations with time-periodic bistable nonlinearity in two-dimensional space. By constructing supersolution and subsolution, we prove the existence of periodic traveling wave fronts. Furthermore, we show that the front is globally stable. 相似文献
54.
This paper presents fuzzy versions of kernel operators and kernel systems on L-ordered sets and establishes a one-to-one correspondence between them. 相似文献
55.
In this paper,we point out that several assertions(Propositions 3.15 and 5.2(v)) in a previous paper by Majumdar and Samanta are not true in general,by counterexamples. 相似文献
56.
Let M and N be nonzero subspaces of a Hilbert space H, and PM and PN denote the orthogonal projections on M and N, respectively. In this note, an exact representation of the angle and the minimum gap of M and N is obtained. In addition, we study relations between the angle, the minimum gap of two subspaces M and N, and the reduced minimum modulus of (I - PN)PM, 相似文献
57.
58.
The optical characteristics of transparent lead magnesium niobate titanate (PMNT) electro-optic ceramic, including the electro-optic phase modulation, electric hysteresis property and thermo-optic coefficient, are investigated in detail. Based on this novel ceramic, a polarization independent electro-optic switch by using fiber Sagnac interferometer (FSI) structure is realized. An initial π-shift is introduced into the Sagnac loop to eliminate the effect of the polarization orientation of the incident light on the switch performance. Then an electrically controllable PMNT phase retarder is used to switch the optical signal between the reflection and transmission ports. Some theoretical analyses are given and the switch performances are also discussed, including the thermal characteristic and different switching frequency response. 相似文献
59.
By using the radio frequency-magnetron sputtering (RF-MS) method, both pure ZnO and boron doped ZnO (ZnO:B) thin films were deposited on glass substrates at ambient temperature and then annealed at 450 °C for 2 h in air. It is found that both ZnO and ZnO:B thin films have wurtzite structure of ZnO with (0 0 2) preferred orientation and high average optical transmission (≥80%). Compared with the resistivity of 6.3 × 102 Ω cm for ZnO film, both as-deposited and annealed ZnO:B films exhibit much lower resistivity of 9.2 × 10−3 Ω cm and 7.5 × 10−3 Ω cm, respectively, due to increase in the carrier concentration. Furthermore, the optical band gaps of 3.38 eV and 3.42 eV for as-deposited and annealed ZnO:B films are broader than that of 3.35 eV for ZnO film. The first-principles calculations show that in ZnO:B thin films not only the band gap becomes narrower but also the Fermi level shifts up into the conduction band with respect to the pure ZnO film. These are consistent with their lower resistivities and suggest that in the process of annealing some substituted B in the lattice change into interstitial B because of its smaller ion radius and this transformation widens the optical band gap of ZnO:B thin film. 相似文献
60.
Xiaolian ChaoZupei Yang Mingyuan DongYi Zhang 《Journal of magnetism and magnetic materials》2011,323(15):2012-2016
The phase structure, microstructure, piezoelectric properties, dielectric characteristic and the ME effect of magnetoelectric Pb[Zr0.23Ti0.36+0.02(Mg1/2W1/2)+0.39(Ni1/3Nb2/3)]O3 (PZT)+xNi0.8Co0.1Cu0.1Fe2O4 (NCCF) composite ceramics were prepared by the conventional solid state reaction method. The structural analysis of both the constituent phases and their composites was carried out by X-ray diffraction, energy dispersive spectrometry and scanning electron microscopy. The results showed cubic spinel structure for ferrite phase and tetragonal perovskite structure for ferroelectric phase. The piezoelectric constant, dielectric constant, Curie temperature, remanent polarization and coercive electric field decreased with increase of ferrite content. The coercive field strength, saturation magnetization and remanent magnetization increased with increasing ferrite content. 相似文献