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小孔内径测量的传感器精度分析
小孔孔径 测量 传感器探针 精度
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2014/4/23
针对小孔的结构特点，介绍了电容传感器探针测量小孔孔径的原理；分析了测量时电容传感器由于参数的线性化、电容探针与小孔的中心线偏心带来的测量误差；并针对以上因素影响，采取了自动对中机构实现测量过程中的最小化偏心，通过标定得到了孔径值与测量值之间的对应关系。实验结果表明，系统的重复性精度可达到 ，稳定性能达到六个小时内漂移不超过 ，该指标完全可以满足实际测量要求。
为了克服传统脉冲远场涡流传感器由于结构的限制带来的激励磁场在空间出现发散、对大壁厚管道检测能力较弱以及难以对缺陷进行准确定位的问题，在分析了脉冲远场涡流检测原理的基础上，采用仿真与实验相结合的方法，仿真分析了基于连通磁路的脉冲远场涡流传感器的聚磁效果，研究了该传感器对管道轴向内外壁裂纹缺陷的定量评估能力，比较了检测线圈处于不同位置时的缺陷分类识别效果。仿真结果表明，该传感器通过引导磁场的定向传播实...
硅晶元等高精度平面度测量时，为提高测量可信性，对所用位移传感器标定已成为业界常规。本研究针对用于基于逐次两点法(STPM)测量硅平面的两电容式位移传感器2804/3890J设计了一种压电陶瓷标定系统，实现其标定间隔达到8nm/1mv，提高了标定的精确度。建立基于灰色理论的GM（0，2）系统数学模型，确立待标定传感器测量结果的回归模型，以得到传感器特性的最佳估计，并确定其联合不确定度，得到被标传感器...
高精度分划板自动对焦评价函数研究
自动对焦 对焦评价函数 离散余弦变换 分划板
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2014/4/22
本文提出了一种基于离散余弦变换系数的自动对焦评价方法，用来准确、快速地反映分划板对焦过程。该方法对分化板图像进行离散余弦变换，通过组合有效的离散余弦变换系数来提供对焦评价值。进行了十字刻线和十字瞄准线两种不同分化板的对焦实验，结果表明，当对焦目标为分划板图像时，本文方法提供的对焦评价值，具有更好的单峰性、更高的灵敏度和更快的运算速度，拥有比空域评价法更优异的性能。
器件老化处理对有机发光磁效应的影响
老化处理 有机磁效应 Alq3 阳离子 界面退化
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2013/8/26
制备了基于小分子tris-(8-hydroxyquinoline)aluminum(III) (Alq3)的有机发光二极管, 并在室温下对器件进行大电流老化处理; 然后测量了器件的光电性能, 以及电致发光磁效应(magneto-electroluminescence, MEL)随老化时间的变化关系. 实验结果显示, 经老化处理后, 器件的发光效率降低、工作电压增大; 但器件的MEL 随老化时间则表...
Statistical anomalies in 2011-2012 Russian elections revealed by 2D correlation analysis
Statistical anomalies Russian elections 2D correlation analysis Applications
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2012/5/28
Here we perform a statistical analysis of the official data from recent Russian parliamentary and presidential elections (held on December 4th, 2011 and March 4th, 2012, respectively). A number of ano...
含单势垒量子隧穿结构电子稳恒输运中的接点效应
电子输运 介观体系 散射矩阵理论 费米-托马斯近似
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2014/1/10
基于散射矩阵理论和费米-托马斯近似，通过对含单势垒的量子隧穿结构的研究，得到了稳恒输运中介观结构的电导特性.结果表明,稳恒条件下接触效应对介观体系中的电子透射以及内部特征势有明显的影响；电势降所呈现的电导特性与经典电路中的基尔霍夫定律相违背，整个介观体系的电阻不能简单地视为接触电阻和散射电阻串联，必须考虑接点和介观器件间的量子相干性.因此，接点效应对于进一步研究介观体系中的电子输运起到非常重要的作...
Unbiased Cultural Transmission in Time-Averaged Archaeological Assemblages
cultural transmission Wright-Fisher model time-averaging
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2012/4/20
Unbiased models are foundational in the archaeological study of cultural transmission. Applications have as- sumed that archaeological data represent synchronic samples, despite the accretional nature...
Opinion formation in time-varying social networks: The case of Naming Game
Opinion formation time-varying social networks The case of Naming Game Social and Information Networks
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2012/4/19
We study the dynamics of the Naming Game as an opinion formation model on time-varying social networks. This agent-based model captures the essential features of the agreement dynamics by means of a m...
Computational comparison of the bending behavior of aortic stent-grafts
Computational comparison bending behavior of aortic stent-grafts
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2012/4/19
Secondary interventions after endovascular repair of abdominal aortic aneurysms are frequent because stent-graft (SG) related complications may occur (mainly endoleak and SG thrombosis). Complications...
Hemaka's constant
Hemaka's constant Popular Physics
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2012/4/19
As proposed in a previous paper, the decorations of ancient objects can provide some information on the approximate evaluations of constant {\pi}, the ratio of circumference to diameter. Here we discu...
Persistence and Uncertainty in the Academic Career
Persistence Uncertainty Academic Career Physics and Society
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2012/4/19
Understanding how institutional changes within academia may affect the overall potential of science requires a better quantitative representation of how careers evolve over time. Since knowledge spill...
Epidemic Variability in Hierarchical Geographical Networks with Human Activity Patterns
Epidemic Variability Hierarchical Geographical Networks Human Activity Patterns Social and Information Networks
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2012/4/19
Recently, some studies have revealed that non-Poissonian statistics of human behaviors stem from the hierarchical geographical network structure. On this view, we focus on epidemic spreading in the hi...
Variability of Contact Process in Complex Networks
Variability of Contact Process Complex Networks Social and Information Networks
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2012/4/19
We study numerically how the structures of distinct networks influence the epidemic dynamics in contact process. We first find that the variability difference between homogeneous and heterogeneous net...
A Jumping Cylinder on an Incline
Jumping Cylinder Incline Popular Physics
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2012/4/19
The problem of a cylinder of mass m and radius r, with its center of mass out of the cylinder axis, rolling on an incline that makes an angle with respect to the horizontal is analyzed. The equation o...