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本文讨论解线性方程组算法的数值稳定性问题,对常见的两种数值稳定性定义(分别由Wilkinson和 Wozniakowski给出)进行了分析,并讨论了它们相互间的强弱关系,证明了前者的要求强于后者,在此基础上,我们引进了更为合理的数值稳定性的概念,并且证明了它与Wo~z niakowski的定义是等价的。 相似文献
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A comparison of the field emission characteristics of vertically aligned graphene sheets grown on different SiC substrates 下载免费PDF全文
The field emission (FE) properties of vertically aligned graphene sheets (VAGSs) grown on different SiC substrates are reported. The VAGSs grown on nonpolar SiC (10-10) substrate show an ordered alignment with the graphene basal plane-parallel to each other, and show better FE features, with a lower turn-on field and a larger field enhancement factor. The VAGSs grown on polar SiC (000-1 ) substrate reveal a random petaloid-shaped arrangement and stable current emission over 8 hours with a maximum emission current fluctuation of only 4%. The reasons behind the differing FE characteristics of the VAGSs on different SiC substrates are analyzed and discussed. 相似文献
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Bingyan Jiang 《中国物理 B》2022,31(9):97306-097306
The Onsager-Casimir reciprocal relations are a fundamental symmetry of nonequilibrium statistical systems. Here we study an unusual chirality-dependent Hall effect in a tilted Weyl semimetal Co3Sn2S2 with broken time-reversal symmetry. It is confirmed that the reciprocal relations are satisfied. Since two Berry curvature effects, an anomalous velocity and a chiral chemical potential, contribute to the observed Hall effect, the reciprocal relations suggest their intriguing connection. 相似文献
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A self-powered sensitive ultraviolet photodetector based on epitaxial graphene on silicon carbide 下载免费PDF全文
A self-powered graphene-based photodetector with high performance is particularly useful for device miniaturization and to save energy.Here,we report a graphene/silicon carbide(SiC)-based self-powered ultraviolet photodetector that exhibits a current responsivity of 7.4 m A/W with a response frequency of over a megahertz under 325-nm laser irradiation.The built-in photovoltage of the photodetector is about four orders of magnitude higher than previously reported results for similar devices.These favorable properties are ascribed to the ingenious device design using the combined advantages of graphene and SiC,two terminal electrodes,and asymmetric light irradiation on one of the electrodes.Importantly,the photon energy is larger than the band gap of SiC.This self-powered photodetector is compatible with modern semiconductor technology and shows potential for applications in ultraviolet imaging and graphene-based integrated circuits. 相似文献
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莫尔条纹常用于工程技术上的精密测量.本文则从一个新的角度出发,对它的一种新的应用做了探讨.通过对叠合光栅的莫尔条纹和叠加静电场等势线的数学表达式分别进行总结,探寻并指出了二者的相似关系和内在联系.进而给出了一种针对给定静电场设计相应的光栅、并利用光栅产生的莫尔条纹模拟该场的普遍方法.文中相应地给出若干实例作为详细说明和... 相似文献
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Defects in silicon carbide(SiC) substrate are crucial to the properties of the epitaxial graphene(EG) grown on it. Here we report the effect of defects in SiC on the crystalline quality of EGs through comparative studies of the characteristics of the EGs grown on SiC(0001) substrates with different defect densities. It is found that EGs on high quality SiC possess regular steps on the surface of the SiC and there is no discernible D peak in its Raman spectrum. Conversely, the EG on the SiC with a high density of defects has a strong D peak, irregular stepped morphology and poor uniformity in graphene layer numbers. It is the defects in the SiC that are responsible for the irregular stepped morphology and lead to the small domain size in the EG. 相似文献
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