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991.
992.
We have studied the densification behaviour, microstructure and electrical properties of WO_3 ceramics with V_2O_5 as the additive ranging from 0.5 to 15mol%. Scanning electron microscopic photos indicated that the grain size of WO_3-V_2O_5 specimens is smaller than that of pure WO_3. The addition of V_2O_5 to WO_3 showed a tendency to enhance the densification rate and to restrict the grain growth. Electrical properties of all specimens were measured for different electrodes at different temperatures. The formation of the grain boundary barrier layer was confirmed by the non-ohmic I-V behaviour. The nonlinear coefficient was obtained at the current density J=0.01, 0.1 and 1mA/cm^2 for a series of WO_3-V_2O_5 samples. The V0.5mol% specimen showed an abnormal phenomenon that the nonlinear characteristics appeared at 350℃ and disappeared at lower and higher temperatures. This implies that it could be applied as a high-temperature varistor. The double Schottky barrier model was adopted to explain the phenomena for the WO_3-V_2O_5 varistors. 相似文献
993.
994.
995.
Determination of the global responses characteristics of a piecewise smooth dynamical system with contact 总被引:2,自引:0,他引:2
Jun Jiang 《Nonlinear dynamics》2009,57(3):351-361
In this paper the global response characteristics of a piecewise smooth dynamical system with contact, which is specifically
used to describe the rotor/stator rubbing systems, is studied analytically. A method to derive the global response characteristics
of the model is proposed by studying each piece of the equations corresponding to different phases of the rotor motion, i.e.,
the phase without rubbing, the phase with rubbing and the phase of self-excited backward whirl. After solving the typical
responses in each phase and deriving the corresponding existence boundaries in the parameter space, an overall picture of
the global response characteristics of the model is obtained. As is shown, five types of the coexistences of the different
rotor responses and deep insights into the interactive effect of parameters on the dynamic behavior of the model are gained. 相似文献
996.
Yaqi Gong Jianping Fan Cheng Wang 《力学学报》2009,41(3):342
基于Tadokoro理论模型,采用有限元方法对离子交换膜金属复合材料
(ionic polymer metal composite, IPMC)的电致动特性进行了数值模拟.
通过比较求解控制方程中不考虑水分子扩散阻力和考虑水分子扩散力的两种计算模型,
着重探讨和比较了水分子扩散阻力对钠离子携带周围水分子的迁移运动规律和变形过程中各
个特征物理量的影响. 结果表明,控制方程中增加水分子扩散阻力这一非线性项,对最终的
宏观挠曲位移影响并不明显;但是对于钠离子浓度、等效应变、内部平衡力分布等物理量影
响很大;这种影响还具有区域性特征,主要集中于电极板附近区域,其他区域影响较弱. 控
制方程中增加水分子扩散力可以更准确地描述钠离子在迁移过程各物理量的变化规律. 相似文献
997.
998.
I. Kh. Abdukadyrova 《Journal of Applied Spectroscopy》2000,67(4):751-754
The influence of radiation on the change in the optical properties of a crystalline quartz is investigated. The results of
the measurement of the optical spectra of luminescence, reflection, and scattering in specimens irradiated with different
fluences of neutron radiation are presented. It is shown that the corresponding spectral characteristics experience substantial
changes in the region of fluences that are associated with rearrangement of the crystalline structure. The results of approximation
of some radiation kinetics are given, and the trend in the process of accumulation of disordered zones is established.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 543–545, July–August, 2000. 相似文献
999.
Qiang Wang Changqing Liu Ying Li 《International Journal of Infrared and Millimeter Waves》2000,21(1):91-100
A shielded microstripline (MSL) of elliptic cross-section with finite metallization thickness penetrating into the substrate is presented. The quasi-static characteristics of this kind of MSL are studied with finit difference method (FDM). The effect of metal cross-section shape and metal penetrating depth is also studied. 相似文献
1000.
Fuyong Xu Keyu Zhao Bin You Xiaohui Lin 《International Journal of Infrared and Millimeter Waves》2000,21(1):45-56
In this paper, the transmission properties such as the dispersion and attenuation characteristics for the dominant mode of the trapezoidal-groove waveguide with arbitrarily inclined angle are analyzed and discussed by using the mode-matching method. Some calculated results are in very good agreement with the published data. The obtained conclusions are of important significance in theoretical studies and actual applications of trapezoidal-groove waveguides for millimeter and submillimeter waves. 相似文献