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91.
GaN的MOVPE生长和m-i-n型蓝光LED的试制 总被引:1,自引:0,他引:1
利用自行研制的常压MOVPE设备和全部国产MO源,采用低温生长缓冲层技术,在蓝宝石(α-Al2O3)衬底上获得了高质量的GaN外延层。未掺杂的GaN外延层的室温电子迁移率已达114cm2/V.s,载流于浓度为2×1018。77K光致发光谱近带边发射峰波长为365nm,其线宽为4DmeV。X射线双晶衍射回摆曲线的线宽为360arcsec。用Zn掺杂生长了绝缘的i-GaN层。在此基础上研制了m-i-n型GaN的LED,并在室温正向偏压下发出波长为455nm的蓝光。 相似文献
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95.
Urban radiowave propagation: a 3-D path-integral wave analysis 总被引:1,自引:0,他引:1
A discussion concerning the need for three-dimensional (3-D) urban radiowave propagation models is presented and followed by a review of previously published work on this topic using the asymptotic path-integral technique. The limitations and advantages of this technique are explained and it is applied to study diffraction by a small number of canonical geometries. The validity of this technique is verified by comparison with controlled laboratory measurements taken at millimetric wave frequencies. Finally, its ability to classify field components according to their distribution in space is employed in order to analyze the observed field strength distributions in the model environments 相似文献
96.
着色型珠光颜料涂布纸的研制 总被引:1,自引:1,他引:0
本文论述了着色型珠光颜料涂布纸的研制工作,并对影响珠光涂料制备的几个因素进行探讨.优化结果表明,瓷土0~30%,珠光颜料70%~100%,胶粘剂25%~30%,固含量23%~25%,涂布量10~15g/m2时,其纸面呈现强烈的珠光光泽,适用于胶印. 相似文献
97.
We have examined the applicability of this simple and effective test to polymer systems widely used in the medical industry. First, it was found that not every polymer examined exhibited a distinct onset of autocatalytic oxidation detectable by DSC. However, for cases where distinct onsets are found, powerful insights can be obtained. These included activation energy of the degradation, thermal oxidative shelf life prediction, and correlation, with product performances. Actual examples are presented to illustrate the utility of the test. 相似文献
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EFFECTS OF COLD EXPANSION OF A HOLE ON FATIGUE CRACK INITIATION LOCATION AND LIFE OF AN LY12CZ ALLOY
Ling Chao Zheng Xiulin† 《Fatigue & Fracture of Engineering Materials & Structures》1992,15(3):241-247
Abstract— In the present study the effects of cold expansion of a hole on the location of fatigue crack initiation and life of LY12CZ alloy sheets are experimentally investigated and a quantitative expression of fatigue crack initiation life presented. Test results and analysis show that there may exist an optimum amount of cold expansion, for which both the coefficient of the resistance to fatigue crack initiation and the threshold are increased, and that the direction of cold expansion has no appreciable effect on fatigue crack initiation life. Observations show that, after cold expansion the fatigue crack nearly always initiates on the final entry face from which the mandrel is introduced into the hole during the final cold expansion process. Therefore it may be thought that the entry face is less resistant to fatigue crack initiation. In addition, the assumption of equivalence of residual stresses and also the strain hardening conditions on both the entry and exit faces may be questionable. 相似文献
100.
Ling Tong 《Journal of Infrared, Millimeter and Terahertz Waves》1997,18(2):431-436
This paper introduce the experiment about a new type of quasi-optic cavity Making a experimental model, measuring all parameters of the cavity, giving experiment results. It shows that theoritical research in reference[1] is correct Its results coincide with theory. At same time, it also indicates the cavity is hopeful device in MMW. 相似文献