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排序方式: 共有398条查询结果,搜索用时 15 毫秒
391.
S. Bhattacharyya Marina Dan A. K. Sen 《International Journal of Infrared and Millimeter Waves》2000,21(12):2065-2075
This paper describes a technique for modelling of rain drop size distributions at Calcutta in terms of negative exponential function, from the measurements of rain rate and attenuation over a dual wavelength LOS link at millimeter and optical frequencies. The DSD model obtained is then used to determine the attenuation at 94 GHz, for comparison with experimentally obtained attenuation at 94 GHz. This is also compared with the attenuation calculated by considering other experimentally obtained DSD models. The best fit negative exponential distribution function (modified M-P model) is presented along with some other experimentally obtained and reference models. 相似文献
392.
V. A. Korotkov Ye. V. Sukhonin 《International Journal of Infrared and Millimeter Waves》1988,9(6):583-596
An iterative method for the radiative transfer equation solution is suggested for the scattering hydrometeors. The method allows to find the layer scattering indicatrix. The method is shown to be more general as compared with the four-flux theory or the perturbation method and differs strongly from these ones because even in the case of the first iteration it gives the results which are very close to ones obtained by numerical methods for all rain scattering angles. 相似文献
393.
基于ARCS动机模型理论,将翻转课堂教学理念与高中"物理学史"校本课程教学相融合,搭建高中物理学习动机激发策略基本框架.在高中物理新课标与核心素养下,以"探索力学的发展史"一课为例,将翻转课堂理念与ARCS动机模型有机地融入课堂教学中,阐述在具体实践中,如何引起和持续产生注意力(Attention),怎样建立教学目标、... 相似文献
394.
酸雨对苋菜中微量元素的影响 总被引:7,自引:0,他引:7
采用盆栽方法,研究了模拟酸雨(pH3.5)对苋菜中微量元素的影响。结果表明,酸雨使苋菜中K、Ca等营养元素严重流失,Al含量明显增高,Mn、Zn等微量元素的变化则因种植在不同原岩发育的土壤上而有所差异。在酸雨地区种植蔬菜,应增加K、Ca肥的施用,并预防由于土壤酸化使有害元素活化而被蔬菜吸收。 相似文献
395.
剖析人教版高中化学教材《化学反应原理》第2章中"测量化学反应速率"实验的教学意义与价值,重点通过数字化手持技术进行实验改进设计,引导学生从"宏观-曲线-微观-符号"四重表征的角度对实验过程进行分析,并应用互动课堂反馈系统对教学效果进行即时检测。教学结束后,从学生对化学反应速率的知识掌握程度、学习目标达成程度、四重表征思维状况3个方面进行测查分析,探讨"手持技术"与"四重表征"整合的互动课堂教学模式的实施效果。 相似文献
396.
A. Maitra Mausumi Kundu 《International Journal of Infrared and Millimeter Waves》2003,24(11):1841-1851
The propagation of wideband signals through the atmosphere has been studied at millimeter wavelengths at which the atmosphere exhibits significant dispersion as well as absorption. The wideband signals having a Gaussian spectrum are considered to be propagating at carrier frequencies in the range 10-200 GHz over line-of-sight paths under varying propagation conditions effected by the clear air and raining atmosphere. The propagation effects on the wideband signal are assessed in terms of the percentage change in the width and the group delay suffered by the pulsed envelope, also having a Gaussian shape, and the shift in the mode frequency of the signal. The results of numerical calculations, based on a closed solution of Fourier integral, show that the propagated wideband signal can be significantly affected by the atmosphere depending on rain rate, carrier frequency, path length and signal bandwidth. 相似文献
397.
398.
Zhenju Zhou Yu Zhou Yingjian Huang Qiuqing Zhu Yongming Tang 《Surface and interface analysis : SIA》2022,54(7):734-746
Corrosion evolutions of UNS C90300 bronzes with and without artificial patina were investigated in the simulated acid rain of Hong Kong. The corrosion products mainly composed of cuprite were formed on the surface exhibiting slight protection for the bronze substrate. The ratios of Sn and Zn in the corrosion products are lower than in the alloy. The artificial patina effectively enhances the corrosion resistance of bronze substrate, even after 30 days of immersion. For both bare and patinated bronzes the Sn- and Zn-based species are absent in the outer layers of corrosion products, and Cu2O species in the outer layer can partially transform into Cu (II) ionic state due to the abundant supply of dissolved oxygen. 相似文献