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铁路营业线施工引发的行车、人身安全事故一直困绕着一代代铁路工作者,为在列车通过前让施工人员、机具、材料等能及时撤到安全限界,确保安全'_按婴铁墅“故障一安全”原则,利用感应线圈原理、系统软件开发等手段研发铁路施工安全防护装置,增加一道安全屏障。 相似文献
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Nonpolar (1120) a-plane GaN films have been grown by low-pressure metal-organic vapor deposition on r-plane (1102) sapphire substrate. The structural and electrical properties of the a-plane GaN films are investigated by high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and van der Pauw Hall measurement. It is found that the Hall voltage shows more anisotropy than that of the c-plane samples; furthermore, the mobility changes with the degree of the van der Pauw square diagonal to the c direction, which shows significant electrical anisotropy. Further research indicates that electron mobility is strongly influenced by edge dislocations. 相似文献
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The breakdown and the current collapse characteristics of high electron mobility transistors (HEMTs) with a low power F-plasma treatment process are investigated. With the increase of F-plasma treatment time, the saturation current decreases, and the threshold voltage shifts to the positive slightly. Through analysis of the Schottky characteristics of the devices with different F-plasma treatment times, it was found that an optimal F-plasma treatment time of 120 s obviously reduced the gate reverse leakage current and improved the breakdown voltage of the devices, but longer F-plasma treatment time than 120 s did not reduce gate reverse leakage current due to plasma damage. The current collapse characteristics of the HEMTs with F-plasma treatment were evaluated by dual pulse measurement at different bias voltages and no obvious deterioration of current collapse were found after low power F-plasma treatment. 相似文献
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采用原位聚合法制备了纳米羟基磷灰石(n-HA)/聚苯硫醚共聚物(PPS-COOCH 3)复合材料(n-HA/PPS-COOCH 3)。研究了n-HA的加入对复合材料的结晶行为、热学性能、亲水性能的影响。采用透射电子显微镜(TEM)观察了复合材料中无机纳米粒子的大小及分散情况。结果表明,共聚物和复合材料都属于结晶性物质,n-HA在复合材料中保持了原来的结晶形态。n-HA的加入可以提高复合材料的亲水性和热稳定性,适量的n-HA可作为异相成核剂增加复合材料中聚合物的结晶度。n-HA在复合材料中分布均匀且保持了纳米状态。 相似文献
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