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我们对"电磁场"课程采取了课前作业的教学方法。该方法是将下节课知识点所用到的相关数学、物理概念和公式通过作业的方式提前布置给学生。本文以分离变量法和达朗贝尔方程的求解为例说明该方法的实施。该两例将有关方程的求解分解为已经学过的数个方程,作为作业预先布置给学生。这种教学方法已收到了良好的教学效果。 相似文献
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空海空间一体化网络是军事信息化基础平台,是当今国内外重点发展的军事战略平台之一。针对当今国外空海空间一体化军事信息网络系统发展动向,首先研究空海空间一体化网络系统架构,分析其技术架构特点,其次结合其面临的复杂多异构的挑战性网络环境等问题,进行针对性分析研究,最后提出采用无线链路自适应组网关键技术和机动网随遇接入组网关键技术相结合,解决空海空间一体化网络组网中的问题,为空海空间一体化网络军事技术发展提供技术支撑。 相似文献
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Physical analysis of normally-off ALD Al2O3/GaN MOSFET with different substrates using self-terminating thermal oxidation-assisted wet etching technique 下载免费PDF全文
Cheng-Yu Huang 《中国物理 B》2022,31(9):97401-097401
Based on the self-terminating thermal oxidation-assisted wet etching technique, two kinds of enhancement mode Al$_{2}$O$_{3}$/GaN MOSFETs (metal-oxide-semiconductor field-effect transistors) separately with sapphire substrate and Si substrate are prepared. It is found that the performance of sapphire substrate device is better than that of silicon substrate. Comparing these two devices, the maximum drain current of sapphire substrate device (401 mA/mm) is 1.76 times that of silicon substrate device (228 mA/mm), and the field-effect mobility ($\mu_{\rm FEmax}$) of sapphire substrate device (176 cm$^{2}$/V$\cdot$s) is 1.83 times that of silicon substrate device (96 cm$^{2}$/V$\cdot$s). The conductive resistance of silicon substrate device is 21.2 $\Omega {\cdot }$mm, while that of sapphire substrate device is only 15.2 $\Omega {\cdot }$mm, which is 61% that of silicon substrate device. The significant difference in performance between sapphire substrate and Si substrate is related to the differences in interface and border trap near Al$_{2}$O$_{3}$/GaN interface. Experimental studies show that (i) interface/border trap density in the sapphire substrate device is one order of magnitude lower than in the Si substrate device, (ii) Both the border traps in Al$_{2}$O$_{3}$ dielectric near Al$_{2}$O$_{3}$/GaN and the interface traps in Al$_{2}$O$_{3}$/GaN interface have a significantly effect on device channel mobility, and (iii) the properties of gallium nitride materials on different substrates are different due to wet etching. The research results in this work provide a reference for further optimizing the performances of silicon substrate devices. 相似文献
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