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91.
同步相量测量技术为电网动态安全监测提供了数据基础,非接触式电压传感技术具备安全、便捷、成本低的优势,有利于测量装置实现海量布点。现有非接触式电测量的缺陷在于复杂电压经探头传变后二次侧输出电压发生畸变,难以还原一次侧电压相量。为解决电压畸变问题,文中提出了一种对带内信号分频计算的相量测量算法。首先对探头输出电压进行预处理,滤除带外信号与噪声,随后采用矩阵束法计算带内信号频率,以此构建信号模型进行时域拟合求解带内信号相量,最后将带内信号相量还原至一次侧后合成得到综合相量。仿真结果表明,所提方法能够利用探头二次侧输出电压采样值计算一次侧电压相量。实验数据显示所提方法的幅值测量误差小于4.5%,相位误差小于1°,频率误差小于0.04 Hz,频率变化率误差小于4 Hz/s。 相似文献
92.
室温下,InPBi表现出强而宽的光致发光光谱,其宽光谱特性来自于材料中的PIn反位深能级和与Bi相关的深能级。该特性使得InPBi有希望应用于制备光学相干层析扫描系统中的超辐射光源。文章利用透射电子显微镜和三维原子探针研究了InPBi薄膜材料的结构性能,发现Bi原子在InPBi薄膜中的分布极不均匀,在InPBi/InP界面出现了Bi的富集区,从该区域沿[001]方向出现了Bi的纳米面,此纳米面位于(110)平面上。这种Bi原子的富集分布阻碍了PIn反位参与的载流子复合过程,对InPBi的光学性能有显著的影响。研究结果可为制造光学相干层析扫描系统的超辐射发光二极管提供一定的理论基础。 相似文献
93.
Writing with Fluid: Structuring Hydrogels with Micrometer Precision by AFM in Combination with Nanofluidics 下载免费PDF全文
Nicolas Helfricht Andreas Mark Marina Behr Andreas Bernet Hans‐Werner Schmidt Georg Papastavrou 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(31)
Hydrogels have many applications in biomedical surface modification and tissue engineering. However, the structuring of hydrogels after their formation represents still a major challenge, in particular due to their softness. Here, a novel approach is presented that is based on the combination of atomic force microscopy (AFM) and nanofluidics, also referred to as FluidFM technology. Its applicability is demonstrated for supramolecular hydrogel films that are prepared from low‐molecular weight hydrogelators, such as derivates of 1,3,5‐benzene tricarboxamides (BTAs). BTA films can be dissolved selectively by ejecting alkaline solution through the aperture of a hollow AFM‐cantilever connected to a nanofluidic controller. The AFM‐based force control is essential in preventing mechanical destruction of the hydrogels. The resulting “chemical writing” process is studied in detail and the influence of various parameters, such as applied pressure and time, is validated. It is demonstrated that the achievable structuring precision is primarily limited by diffusion and the aperture dimensions. Recently, various additive techniques have been presented to pattern hydrogels. The here‐presented subtractive approach can not only be applied to structure hydrogels from the large class of reversibly formed gels with superior resolution but would also allow for the selective loading of the hydrogels with active substances or nanoparticles. 相似文献
94.
I. Povstugar C. H. Zenk R. Li S. Neumeier O. Dolotko 《Materials Science & Technology》2016,32(3):220-225
Novel Cr containing Co-Al-W base superalloys were studied by atom probe tomography and neutron diffraction. Cr is found to predominantly partition to the γ matrix and decrease partitioning of W to γ′. Furthermore, Cr significantly enhances the γ′ volume fraction, decreases the γ/γ′ lattice misfit and deteriorates the creep resistance. Addition of Ni to the Cr containing alloys affects partitioning of W and Al, further decreases the lattice misfit and results in the formation of irregularly shaped precipitates. Al, W and Cr tend to occupy the ‘B'sublattice in the γ′-A3B phase (L12 type), while Co and Ni reside in the ‘A' sublattice. 相似文献
95.
96.
目的针对传统逆子结构理论在求解过程中界面响应难以实测的问题,提出一种利用频响探针技术来获取该界面响应的关键技术。方法首先基于该频响探针的动力学微分方程,从理论上推导了该频响探针技术的理论公式,然后对建立的二级单点刚性耦合系统进行了有限元数值验证,将利用频响探针技术预测得到的难测原点频响函数与有限元计算值进行比较,并将该预测值代入逆子结构理论公式中,得到了部件频响函数的预测值,将该预测值与有限元计算值进行了对比验证。结果预测值与有限元计算值高度吻合,验证了该理论的准确性。结论该频响探针关键技术在获取界面响应不可测数据方面,有很好的应用价值。 相似文献
97.
临界直径是确定炸药合理装药直径、预防炸药拒爆和不完全爆轰的重要指标,对炸药性能提高和高效利用有着十分重要的意义。设计了一种连续压导探针和楔形装药装置,在对炸药爆速进行测试的同时,利用炸药在临界直径不完全爆轰的特征,通过寻找爆轰波传播的拐点确定炸药临界直径。试验结果表明:装药密度为0.9g/cm3的铵油炸药爆速为3 261 m/s,临界直径为12.5 mm。提供了一种可同时测得炸药爆速和临界直径的方法,该方法简单,试验费用低,对炸药参数测试具有一定的指导意义。 相似文献
98.
99.
Alexander S. Chang Lincoln J. Lauhon 《Current Opinion in Solid State & Materials Science》2018,22(5):171-187
Microscopy has played a central role in the advancement of nanoscience and nanotechnology by enabling the direct visualization of nanoscale structure, leading to predictive models of novel physical behaviors. Electronic and photonic device technologies, whose features and performance are often improved through miniaturization, have particularly benefited from new capabilities in the characterization of material structure and composition. This paper reviews recent applications of atom probe tomography to semiconducting materials with nanoscale architectures that are designed to impart novel properties and device functionality by virtue of their shape and size. A review is necessary because rapid advances in atom probe instrumentation and analysis in the last decade have greatly expanded the utility of atom probe tomography to address scientific questions and technical questions in this area. The paper is organized in terms of the surface topologies of nanoscale architectures. We begin with nominally planar interfaces including thin film heterostructures and superlattices with open surfaces. Distinctive capabilities in the analysis of interfaces are introduced, as are challenges arising from measurement artifacts. We then discuss nanowires and nanowire heterostructures with surfaces that are closed along one dimension, for which atom probe tomography has provided unique and important understandings on the doping processes. Finally, we consider nanocrystals and quantum dots with completely closed surfaces. Along the way, current challenges and opportunities for atom probe tomography are highlighted, and the reader is directed to complementary reviews of more technical aspects of atom probe analysis. 相似文献
100.