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881.
882.
测定金属电阻温度系数的方法研究 总被引:1,自引:0,他引:1
从金属电阻率与温度的线性关系出发,设计了测定金属电阻温度系数的实验方案。利用基本的电磁学仪器和热学仪器组合进行实验,以漆包铜线作为待测金属丝测定出铜的电阻温度系数,分析了导致系统误差产生的主要原因,并就待测金属丝的选取原则、温度控制的方法进行了讨论。 相似文献
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Recent research shows that Hawking radiation from black hole horizon can be treated as a quantum tunneling process, and fermions tunneling method can successfully recover Hawking temperature. In this tunneling framework, choosing a set of appropriate matrices γ^μ is an important technique for fermions tunneling method. In this paper, motivated by Kerner and Man's fermions tunneling method of 4 dimension black holes, we further improve the analysis to investigate Hawking tunneling radiation from a rotating charged black hole in 5-dimensional gauged supergravity by constructing a set of appropriate matrices γ^μ for general covariant Dirac equation. Finally, the expected Hawking temperature of the black hole is correctly recovered, which takes the same form as that obtained by other methods. This method is universal, and can also be directly extend to the other different-type 5-dimensional charged black holes. 相似文献
886.
以碰撞为能量交换机制,按局部热力学平衡近似处理低气压等离子体,并考虑辉光放电二极之间的电位分布,得到了电子密度与气体压力的关系和电子温度与电场强度的关系。提出了一种利用压强、电压和电流就获得电子温度和密度的诊断方法。用Langmuir探针方法验证了获得的结果。 相似文献
887.
We examine how noise interacts with encoding mechanisms of neuronal stimulus in a cold receptor. From ISI series and bifurcation diagrams it is shown that there are considerable differences in interval distributions and impulse patterns caused by purely deterministic simulations and noisy simulations. The ISI-distance can be used as an effective and powerful way to measure the noise effects on spike trains of the cold receptor quantitatively. It is also found that spike trains observed in cold receptors can be more strongly affected by noise for low temperatures than for high temperatures in some aspects; meanwhile, the spike train has greater variability with increasing noise intensity. 相似文献
888.
GUO Yang LIU Yao-Ping LI Jun-Qiang ZHANG Sheng-Li MEI Zeng-Xia DU Xiao-Long 《中国物理快报》2010,27(6):171-174
A Van der Pauw Hall measurement is performed on the intended doped ZnO films (Na doped ZnO) grown by using the molecular beam epitaxial method. All as-grown samples show n-type conductivity, whereas the annealed samples (annealing temperature 900℃) show ambiguous carrier conductivity type (n- and p-type) in the automatic Van der Pauw Hall measurement. A similar result has been observed in Li doped ZnO and in as-doped ZnO films by other groups before. However, by tracing the Hall voltage in the Van der Pauw Hall measurement, it is found that this alternative appearance of both n- and p-type conductivity is not intrinsic behavior of the intended doped ZnO films, but is due to the persistent photoconductivity effect in ZnO. The persistent photoconductivity effect would strongly affect the accurate determination of the carrier conductivity type of a highly resistive intended doped ZnO sample. 相似文献
889.
We report the temperature-dependent resistivity and dielectric function (1 kHz- 3 MHz) of a charge ordering system La1.5Sr0.5NiO4-δ. The primary data of ac impedance was measured by a four-terminal pair arrangement. Above 180K, the resistivity is independent of frequency. At lower temperatures, the dielectric function couM not be fitted by a Debye model with a single relaxation time, it should have a distribution. At T = 130 K, there is a sudden increase in the p - T relation, meanwhile an anomaly dielectric response occurs on the temperature dependant dielectric spectrum in the whole measured frequency range, in which the dielectric constant has a high value even at high frequency region. Our analysis suggests that the current system would be more consistent with the Zener polaron model. 相似文献
890.
Numerical Study on Open-Circuit Voltage of Single Layer Organic Solar Cells with Schottky Contacts: Effects of Molecular Energy Levels, Temperature and Thickness 下载免费PDF全文
We numerically investigate the effects of the exciton generation rate G, temperature T, the active layer thickness d and the position of LUMO level EL related to the cathode work function Wc at a given energy gap on the opencircuit voltage Voc of single layer organic solar cells with Schottky contact. It is demonstrated that open-circuit voltage increases concomitantly with the decreasing cathode work function Wc for given anode work functions and exciton generation rates. In the case of given cathode and anode work functions, the open-circuit voltage first increases with the exciton generation rate and then reaches a saturation value, which equals to the builtin voltage. Additionally, it is worth noting that a significant improvement to Voc could be made by selecting an organic material which has a relative high LUMO level (low |EL| value). However, Voc decreases as the temperature increases, and the decreasing rate reduces with the enhancement of exeiton generation rate. Our study also shows that it is of no benefit to improve the open-circuit voltage by increasing the device thickness because of an enhanced charge recombination in thicker devices. 相似文献