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91.
92.
We investigate the molecular beam epitaxy growth of metamorphic InxGal-xAs materials (x up to 0.5) on GaAs substrates systematically. Optimization of structure design and growth parameters is aimed at obtaining smooth surface and high optical qualdty. The optimized structures have an average surface roughness of 0.9-1.8 nm. It is also proven by PL measurements that the optical properties of high indium content (55%) InGaAs quantum wells are improved apparently by defect reduction technique and by introducing Sb as a surfactant. These provide us new ways for growing device quality metamorphic structures on GaAs substrates with long-wavelength emissions. 相似文献
93.
94.
采用Monte Carlo方法模拟了HgI2、非晶Se和CdTe几种直接X射线转换探测器在医用X射线范围(10—100keV)的透过谱、背向散射谱、吸收效率和光电灵敏度. 对X射线和HgI2的作用过程模拟采用了EGSnrc Monte Carlo代码系统, 对信号电荷的产生考虑了电荷产生的高斯噪声和材料深陷阱作用造成的部分电荷收集影响. 结果表明, 载流子平均自由程(Schubweg)在相对于探测材料厚度较小时, 陷阱作用能很大地影响探测灵敏度. HgI2的灵敏度是非晶Se的5倍以上, CdTe的灵敏度是非晶Se的10倍以上, 采用高Z序数材料可以大大提高探测灵敏度. 相似文献
95.
96.
Gain Measurement and Anomalous Decrease of Peak Gain at Long Wavelength for InAs/GaAs Quantum-Dot Lasers 下载免费PDF全文
Mode gain spectrum is measured by the Fourier series expansion method for InAs/GaAs quantum-dot (QD) lasers with seven stacks of QDs at different injection currents. Gain spectra with distinctive peaks are observed at the short and long wavelengths of about 1210nm and 1300nm. For a QD laser with the cavity length of 1060μm, the peak gain of the long wavelength first increases slowly or even decreases with the injection current as the peak gain of the short wavelength increases quickly, and finally increases quickly before approaching the saturated values as the injection current further increases. 相似文献
97.
采用纳米级镍/铁双金属体系同步处理含Cr(VI)和p-NCB的废水,考察了反应温度、初始pH值和Cr(VI)、p-NCB浓度变化以及Ni(II)存在对处理效率的影响.结果表明:纳米级镍/铁双金属应用于Cr(VI)和p-NCB同步处理,可以取得良好的去除效率.反应产物为Cr(III)和苯胺.Ni(II)可以促进p-NCB的还原降解,而水中的Cr(VI)会与p-NCB起竞争作用,从而抑制p-NCB的还原降解. 相似文献
98.
本文简要介绍了计算C G系数的生群元矩阵方程法,给出计算二十面体群C G系数时采用的简化计算方法,并给出了Ⅰ群C G系数的计算结果。 相似文献
99.
XuHai Yang ZhiGang Li ChuGang Feng Ji Guo HuLi Shi GuoXiang Ai FengLei Wu RongChuan Qiao 《中国科学G辑(英文版)》2009,52(3):333-338
A geostationary (GEO) satellite may serve as a navigation satellite, but there is a problem that maneuvers frequently occur
and the forces are difficult to model. Based on the technique of determining satellite orbits by transfer, a predicted orbit
with high accuracy may be achieved by the method of statistical orbit determination in case of no maneuver force. The predicted
orbit will soon be invalid after the maneuver starts, and it takes a long time to get a valid orbit after the maneuver ends.
In order to improve ephemeris usability, the method of rapid orbit forecasting after maneuvers is studied. First, GEO satellite
movement is analyzed in case of maneuvers based on the observation from the orbit measurement system by transfer. Then when
a GEO satellite is in the free status just after maneuvers, the short arc observation is used to forecast the orbit. It is
assumed that the common system bias and biases of each station are constant, which can be obtained from orbit determination
with long arc observations. In this way, only 6 orbit elements would be solved by the method of statistical orbit determination,
and the ephemeris with high accuracy may be soon obtained. Actual orbit forecasting with short arc observation for SINOSAT-1
satellite shows that, with the tracking network available, the precision of the predicted orbit (RMS of O-C) can reach about
5 m with 15 min arc observation, and about 3 m with 30 min arc observation.
Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA12Z322), the National
Basic Research Program of China (Grant No. 2007CB815503), and the West Light Program of Chinese Academy of Sciences (Grant
No. 2007LH01) 相似文献
100.
介绍了海棠果果汁、果酱综合利用加工技术的工艺流程、操作要点及主要技术指标,探讨了生产中出现的问题及应采取的措施。 相似文献