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随着电气化铁路的迅速发展,电气化铁路电磁干扰对情报雷达的影响愈来愈引起人们的关注。但目前国内外对于该电磁干扰的来源和机理,及其对雷达的影响程度,尚没有明确的结论。文中对机车受电弓滑动离线引起的电磁干扰噪声进行数学建模,并定量分析了此噪声对情报雷达的影响。通过仿真得到了雷达接收干扰强度与雷达和铁道间距、机车速度之间的关系,给出了雷达的有效防护距离,对雷达的防护措施和雷达站的选址提出了有益的建议。 相似文献
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针对相干散射雷达探测中受方向敏感性的影响产生距离拓展的现象,研究了在不规则体尺度参数影响下回波距离拓展特性与雷达频率之间的依赖关系. 基于相干散射雷达回波方程,对回波展宽随不规则体尺度变化进行了计算,开展了雷达工作频率与距离拓展特性依赖关系的仿真,得到了雷达工作频率-展宽宽度拟合斜率随不规则体尺度变化规律. 结果表明,回波展宽宽度与雷达频率之间为线性相关,拟合斜率与不规则体纵向尺度之间存在一一对应的关系,通过线性回归计算的斜率可以用于反推不规则体的纵向尺度参数. 由于斜率计算无需获取绝对的雷达天线增益、馈线损耗和发射功率等参数,因此可为未标定的 VHF雷达提供一种新的不规则体尺度探测方法,这对开发新的不规则体探测技术具有重要意义. 相似文献
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采用了一种基于干扰噪声比和干扰累计时间概率的方法,对舰艇编队内不同平台间监视雷达的同频干扰进行了分析研究,在建立数学模型的过程中综合地考虑了电磁干扰在频域、时域、空域、强度等多方面特性,并通过实例分析得出了初步结论,可为编队电磁兼容性研究提供技术支持。 相似文献
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Jia Luo Yu-Long Jiang Guo-Ping Ru Bing-Zong Li Paul K. Chu 《Journal of Electronic Materials》2008,37(3):245-248
The influence of the addition of Yb to Ni on the silicidation of Ni was investigated. The Ni(Yb) film was deposited on a Si(001)
substrate by co-sputtering, and silicidation was performed by rapid thermal annealing (RTA). After silicidation, the sheet
resistance of the silicide film was measured by the four-point probe method. X-ray diffraction and micro-Raman spectroscopy
were employed to identify the silicide phases, and the redistribution of Yb after RTA was characterized by Rutherford backscattering
spectrometry and Auger electron spectroscopy. The influence of the Yb addition on the Schottky barrier height (SBH) of the
silicide/Si diode was examined by current–voltage measurements. The experimental results reveal that the addition of Yb can
suppress the formation of the high-resistivity Ni2Si phase, but the formation of low-resistivity NiSi phase is not affected. Furthermore, after silicidation, most of the Yb
atoms accumulate in the surface layer and only a small number of Yb atoms pile up at the silicide/Si(001) interface. It is
believed that the accumulation of a small amount of Yb at the silicide/Si(001) interface results in the SBH reduction observed
in the Ni(Yb)Si/Si diode. 相似文献
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M. Fahy P. Vaccaro K. Fujia M. Takahash X. M. Zhang B. A. Joyce T. Watanabe 《Microelectronics Journal》1997,28(8-10):1011-1018
The ability to grow high quality (InGa)As on the (111)A surface is essential for the production of a wide range of optoelectronic devices, but the topic has so far received little attention. What work there has been shows it to be highly problematic, reflected in the very broad photoluminescence (PL) peaks observed for GaAs:(InGa)As multiple quantum well structures. The origin of this broadening is unclear but is certainly related to the difficulty in choosing appropriate conditions for the growth of III-Vs on the (111)A surface. We have undertaken a study of the growth of (InGa)As on the GaAs(111)A, (211)A and (311)A surfaces with the goal of achieving high quality quantum well structures, the test being the ability to obtain narrow PL line widths. We have demonstrated that 80 Å 15% InGaAs(111)A single quantum wells with 12K PL peak widths of less than 8 meV can be obtained by growth at 400°C under a V:III ratio of 5:1. 相似文献
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目的:探讨比较汉防己甲素(Tet)和艾氟龙对离体兔角膜基质细胞的抑制作用及其作用机制。方法:选用原代及传代兔角膜基质细胞,Tet组加入含不同质量浓度Tet的培养液,艾氟龙组加入不同质量浓度艾氟龙的培养液,对照组加入含等量PBS的培养液。采用四甲基偶氮唑蓝(MTT)比色法检测对细胞增生的抑制;免疫细胞化学法检测E2F1的表达状况。结果:Tet和艾氟龙对角膜基质细胞生长都具有抑制作用,各时间点IC50Tet均1低于艾氟龙。免疫细胞化学结果显示,Tet组、艾氟龙组和对照组均有E2F1蛋白的表达,但Tet组和艾氟龙组中E2F1蛋白的表达均减弱,Tet组中E2F1蛋白的表达减弱更明显。结论:Tet和艾氟龙对角膜基质细胞的增生均有抑制作用,且Tet对角膜基质细胞的抑制作用强于艾氟龙。Tet和艾氟龙可能通过降低E2F1的表达使细胞周期停滞而发挥其对角膜基质细胞的抗增生作用。 相似文献
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J. Chai K.-K. Lee K. Doyle J.H. Dinan T.H. Myers 《Journal of Electronic Materials》2012,41(10):2738-2744
A key issue with the current HgCdTe/Si system is the high dislocation density due to the large mismatch between HgCdTe and Si. An alternative system that has superior lattice matching is HgCdSe/GaSb. A buffer layer to mitigate issues with direct nucleation of HgCdSe on GaSb is ZnTe1?x Se x . We have performed preliminary studies into the growth of lattice-matched ZnTe1?x Se x on both (100) and (211)B GaSb. The effects of substrate orientation, substrate temperature, and growth conditions on the morphology and crystallography of ZnTe0.99Se0.01 alloys were investigated. The lattice-matching condition yielded minimum root-mean-square (rms) roughness of 1.1?nm, x-ray rocking curve full-width at half-maximum (FWHM) value of ~29?arcsec, and density of nonradiative defects of mid-105?cm?2 as measured by imaging photoluminescence. 相似文献
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Smagina Zh. V. Zinoviev V. A. Rudin S. A. Rodyakina E. E. Novikov P. L. Nenashev A. V. Dvurechenskii A. V. 《Semiconductors》2020,54(14):1866-1868
Semiconductors - Space-arranged arrays of pits on Si(001) substrates were prepared using electron-beam lithography and plasma chemical etching. The positions of pits were arrange to the square and... 相似文献
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Sm~(3+)掺杂Co_(0.6)Zn_(0.4)Ni_(0.8)Fe_(1.2)O_4红外辐射陶瓷材料的研究 总被引:2,自引:0,他引:2
用常规固相合成法成功地制备出Sm3 掺杂Co0.6Zn0.4Ni0.8Fe1.2O4红外辐射陶瓷材料,并通过XRD、FT-IR和IRE-2型红外发射率测量仪测试了材料的微观结构,分析了材料的结构特征与红外辐射性能的关系,发现Sm3 的掺杂导致Sm3 以一定的配位形式进入Co0.6Zn0.4Ni0.8Fe1.2O4体系中,并形成了有限置换型固溶体结构.数据分析可知,Sm3 掺杂浓度对材料的红外辐射性能存在一定的影响,样品Sm0.1在全波段的积分发射率为0.74,而在>8μm波段的平均发射率最高值可达0.94. 相似文献
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We have studied the confined phonons in GaAs/Al0 3Ga0.7As superlat-tice grown by molecular beam epitaxy on oriented and misoriented GaAs (001) substrates. Raman scattering measurements have been performed at room- and low-temperatures. The results show that the phonon features in the superlattice-grown on GaAs(001) misoriented 4° toward the [110] direction are significantly different from those in the precisely oriented sample. The difference is discussed in terms of misorientation induced atomic-steps at GaAs-Al0.3Ga0.7As interfaces. 相似文献