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Inhomogeneities in semiconductor solids can be imaged by two-dimensional mapping of the amplitude of periodically modulated tip current in scanning tunneling microscopy that is induced by illumination of semiconductor samples with a chopped light. It has been shown that it is possible to distinguish between plural origins of the photo-modulated current by analyzing the response properties of the current signal. A judicial choice of the modulation frequency is important for the required contrasts to be obtained. 相似文献
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Dielectric and microwave absorbing properties of low power plasma sprayed Al2O3/Nb composite coatings 总被引:1,自引:0,他引:1
Liang Zhou Wancheng ZhouMalin Chen Fa LuoDongmei Zhu 《Materials Science and Engineering: B》2011,176(18):1456-1462
Al2O3/Nb composite coatings were sprayed on graphite substrates by low power atmospheric plasma spraying (LPAPS) with an internally fed powder torch. The composite particles were agglomerated with different mass fractions by spray-drying technology. The microstructure and dielectric properties of coatings were investigated. The microstructure of composite coatings shows a uniform dispersion of metal particles in the composite coatings. Both the real (?′) and imaginary (?″) parts of the complex permittivity increase with increasing Nb content over the frequency range of 8.2-12.4 GHz, which is ascribed to space charge polarization and conductance loss, respectively. By calculating the microwave-absorption as a single-layer absorber, reflection loss values exceeding −10 dB can be obtained in the frequency range of 10.0-11.8 GHz with 10 wt% Nb content coating when the coating thickness is 1.5 mm. 相似文献
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利用有限元法建立了三维锂电解槽电热场仿真模型,考察了电解槽结构参数对电热场的影响。结果表明,缩短阴阳极间距(ACD),增加阳极半径(Ar)、阴极厚度(Ct)及阴极高度(Ch)均可以在保持能量平衡的前提下提高电解槽的电流强度。对上述参数进行无量纲化研究,得到了方程:CI=30000×(ACD/40)~(-0.24519)×(Ar/150)~(0.79291)×(Ct/225)~(0.09835)×(Ch/700)~(0.37953),对于电解槽的放大设计,可以根据上述方程,不对电解槽进行复杂的建模计算,进而节省资源,提高效率。 相似文献
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Barium strontium titanate (BaxSr1−xTiO3) films were deposited by sol-gel technique on platinized silicon substrate for the composition range x = 0.0 to 1.0 in steps of 0.1. The as-deposited films were found to be amorphous. The films crystallize on annealing in air at 700 °C for 1 h. Dielectric constant (ε′) and loss tangent (tanδ) were measured in the temperature range − 180 °C to 150 °C in the frequency range 0.1 to 100 kHz. Both ε′ and tanδ show a small dispersion for all the compositions. This dispersion is more at the peak value than at room temperature. A comparison of the room temperature and peak value of the dielectric constant for various compositions are made with the reported values. Transition temperatures are reported for the entire composition range. All the compositions show a transition from ferroelectric to paraelectric phase except strontium titanate. Transition temperature shows a systematic decrease with increase in strontium content. The variation is at a rate of 3.4 °C/mol% of SrTiO3. Curie constants are also reported for the entire composition range. 相似文献
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Emilio Alvarez-Parrilla Laura A. de la Rosa Ryszard Amarowicz Fereidoon Shahidi 《Food chemistry》2012
The potential of fresh and processed Jalapeño and Serrano pepper extracts for the control of lipid oxidation in several systems was investigated. The assays used included β-carotene/linoleate model system, striped corn oil, ground pork meat and Cu(II)-induced oxidation of human low-density lipoprotein (LDL). The results showed that all extracts were effective in at least one system, although their potency varied. Extracts of smoked Jalapeño were particularly effective. The lipid-protective effect of the extracts was mainly due to the presence of phenolic compounds, but other phytochemicals, such as chlorophylls were also involved. 相似文献
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Reproducible tip fabrication and cleaning for UHV STM 总被引:1,自引:0,他引:1
Several technical modifications related to the fabrication and ultra-high vacuum (UHV) treatments of the scanning tunneling microscope (STM) tips have been implemented to improve a reliability of the tip preparation for high-resolution STM. Widely used electrochemical etching drop-off technique has been further refined to enable a reproducible fabrication of the tips with a radius 相似文献
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Ch 是一种C/C++脚本语言,用Ch 脚本语言对通信设备进行测试具备简单,快速,可直接嵌入等优点。RobotFramework 是基于Python 语言开发的开源的自动化测试系统,它具有简单明了的上下级结构,可灵活重用的KeyWord,独立于平台和应用,具有很强的扩展性等多种优点。首先介绍构建与实现了一个适合通信设备的Ch 脚本测试新框架,并利用RobotFramework 极强的扩展性,把Ch 测试脚本无缝融合进RobotFramework,融合后的Ch 测试框架同时具备了Ch 脚本和RobotFramework的优点。 相似文献
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An AFM image would not be the true topography of a surface because of the limitation of a finite size of the tip. The true topography of the surface can be deduced if we can know the tip shape. In this paper a simple method has been established to determine the profile of an AFM tip. A geometrical model for the tip and a spherical object has been proposed to show the procedure for deducing the tip shape from AFM images. Isolated spheres and closely packed spheres with different diameters have been observed to confirm the tip shape by this method. It is a non-destructive method to determine the tip shape and the results can be used for future reconstruction of an AFM image. 相似文献