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陈永生 《数学的实践与认识》1974,(2)
某机械厂承担了一批水管的铸造业务,为了便于检查和清洗管道,使用单位要求在90°弯头上开一个检查孔,盖上盖子后,管內仍保持圆滑无阻.这个孔盖的周边曲线该怎么画线?这一问题颇有实际意义.所要求的曲线,显然是平面切割圆环的相贯线,我们叫它圆环曲线.本文介绍了圆环曲线的直角坐标方程及该曲线的几何画线方法. 相似文献
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利用价格低廉、性能优良的金属纳米颗粒增强太阳电池的光吸收具有广阔的应用前景. 通过建立三维数值模型, 模拟了微晶硅薄膜电池前表面周期性分布的Al纳米颗粒阵列对电池光吸收的影响, 并对其结构参数进行了优化. 模拟结果表明: 对于球状Al纳米颗粒阵列, 影响电池光吸收的关键参数是周期P与半径R的比值, 或者说是颗粒的表面覆盖度; 当P/R=4–5时, 总的光吸收较参考电池提高可达20%. 与球状颗粒相比, 优化后的半球状Al纳米颗粒阵列可获得更好的陷光效果, 但后者对颗粒半径R的变化较敏感. 另外, 结合电场分布, 对电池光吸收增强的物理机理进行了分析. 相似文献
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光电效应实验是大学物理非常重要的经典实验之一。然而,由于实验条件和技术水平的限制,无法将实验现象可视化。基于Comsol软件的粒子追踪模块对光电效应过程进行了模拟仿真研究。该模拟仿真可以实现如下功能:1)可通过调节入射波长(频率)、阳极电压、阴极功函数、极板间距和阴极发射电流等参数展开研究;2)可模拟、展现电子在不同电压下的运动轨迹;3)可通过阳极光电流与阳极电压和阴极发射电流的关系曲线,获得遏止电压,验证光电效应的基本规律。通过该模拟仿真实验,使学生对光电效应的过程和规律有了更深刻的理解和认识。 相似文献
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Effect of substrate temperature on microstructure and optical properties of single-phased Ag20 film deposited by using radio-frequency reactive magnetron sputtering method 下载免费PDF全文
Using a radio-frequency reactive magnetron sputtering technique, a series of the single-phased Ag20 films are deposited in a mixture of oxygen and argon gas with a flow ratio of 2:3 by changing substrate temperature (Ts). Effects of the Ts on the microstructure and optical properties of the films are investigated by using X-ray diffractometry, scanning electron microscopy and spectrophotometry. The single-phased Ag20 films deposited at values of Ts below 200℃ are (111) preferentially oriented, which may be due to the smallest free energy of the (111) crystalline face. The film crystallization becomes poor as the value of Ts increases from 100℃ to 225℃. In particular, the Ag20 film deposited at Ts=225℃ loses the (111) preferential orientation. Correspondingly, the film surface morphology obviously evolves from a uniform and compact surface structure to a loose and gullied surface structure. With the increase of Ts value, the transmissivity and the reflectivity of the films in the transparent region are gradually reduced, while the absorptivity gradually increases, which may be attributed to an evolution of the crystalline structure and the surface morphology of the films. 相似文献
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利用X射线衍射谱(XRD)和X射线光电子谱(XPS)研究了热处理对AgxO样品的结构及成份的影响.研究结果表明所有制备的AgxO样品基本为无定型,并且AgO和Ag2O两种成份共存;两组具有代表性的AgxO样品经过高温热处理后分别呈现了(Ag+Ag2O)和Ag2O的多晶结构,结构及成份的巨大差异与样品制备条件息息相关;AgO和Ag2O两种成份的热分解临界温度分别为200℃和300℃;热处理过程中,伴随着AgxO的热分解及体内的氧原子向样品表面的扩散过程,并且Ag2O具有相对致密的结构. 相似文献
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The study of amorphous incubation layers during the growth of microcrystalline silicon films under different deposition conditions 下载免费PDF全文
<正>The structural un-uniformity of μc-Si:H films prepared using a very high frequency plasma-enhanced chemical vapour deposition method has been investigated by Raman spectroscopy,spectroscopic ellipsometer and atomic force microscopy.It was found that the formation of amorphous incubation layer was caused by the back diffusion of SiH_4 and the amorphous induction of glass surface during the initial ignition process,and growth of the incubation layer can be suppressed and uniformμc-Si:H phase is generated by the application of delayed initial SiH_4 density and silane profiling methods. 相似文献