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911.
A. Cig J. Ma
ka M. Mair G. Gritzner G. Plesch V. Zrubec 《Physica C: Superconductivity and its Applications》1999,320(3-4):267-276
The effects of the thallium and mercury content x on the as-sintered and post annealed samples of MxPb0.4Sr1.6Ba0.4Ca2Cu3O8+δ {M: Tl (0.32≤x≤0.74) or Hg (0.18≤x≤0.68)} have been studied by magnetization and transport measurements. For Tl-1223 we have found the optimum Tl doping level to be x=0.53 regarding the grain properties, the content of superconducting phase, the first penetration field Hplwl, the transport (Jctr), magnetic intergrain (JcM) and intragrain (Jcg) critical current densities. The critical temperature Tc of the as-sintered Tl-1223 sample decreased with increasing Tl content. Post-annealing in oxygen improved the Tc for Tl contents of x≥0.53 and had generally positive effects on the critical current densities. The intergrain properties of the Hg-1223 samples were much worse than those of the Tl-based superconductors. 相似文献
912.
913.
研究了一种新型的坚实可靠的自适应控制算法在HL-2A装置等离子体电流控制中的应用,并使用MATLAB进行了计算机仿真。结果表明,该控制方法与典型的PID控制相比,能显著地提高系统的动态响应性能。且具有较好的抗干扰性。 相似文献
914.
新型钕铁硼电磁阻尼演示仪 总被引:1,自引:0,他引:1
利用稀土永磁材料钕铁硼(Nd-Fe-B)设计制作出一种新型电关演示仪,可演示阻尼振动的三种状态(欠阻尼状态、临界阻尼状态、过阻尼状态),配合投影仪使用,演示效果显著。 相似文献
916.
A new, general and exact method for resolving waveguide and grating problems is presented whereby the unknown electric field in a given dielectric distribution in the presence of an arbitrary source distribution can be obtained exactly from the known complete electric field solution in a simpler dielectric structure in the presence of the same source distribution. The method can be used in the form of an iterative scheme. The solution can also be obtained through an implicit equation which can be solved numerically without convergence problem by matrix inversion. The application of the method to the case of abnormal reflection under normal incidence from a segmented waveguide is given as an example. 相似文献
917.
Previous calculations of transport coefficients of particle systems in two or more dimensions have used computer simulations or various approximations, like those implicit in the Boltzmann equation or in the standard probability theory of diffusion. Here an exactly solved model of crystal growth in three dimensions is transformed into a 2D model of steady particle transport. Then the exact, many-body stationary distribution and exact transport coefficients can be found as well as correlation functions. The model is highly asymmetric. In the transverse direction, particles are strongly attracted, so that long transverse rows of particles tend to form at low temperature. Kinks in these rows are rare, so the transverse positions of kinks effectively move continuously on a large distance scale. 相似文献
918.
919.
A simple and general derivation of Josephson's formulae for the tunneling currents is presented on the basis of Sewell's general formulation of superconductivity in relation to off-diagonal long-range order (ODLRO). 相似文献
920.
We present the results of an investigation of the cathodoluminescence of the Eu2+ ion in gallium chalcogenides (Ga2S3) and europium thiogallate (EuGa2S4). We show that the intense wide-band radiation of these compounds is due to the 4f-5d transitions of the Eu2+ ions. With increase in the Eu2+ percent composition from 0.1 to 5.0 mol.% the luminescence brightness increases and then decreases.
Translated from Zhurnal Prikladnoi Spektrskopii, Vol. 67, No. 2, pp. 268–270, March–April, 2000. 相似文献