Selective Nanoscale Fabrication with Roughness Reduction of Polycrystalline Silicon by Physically Induced Fluorine Bonds Using Atomic Force Microscope

Polycrystalline silicon (poly-Si) is widely used as a gate layer in integrated circuits, transistors, and channels through nanofabrication. Nanoremoval and roughness control are required for nanomanufacturing of various electronic devices. Herein, a nanoscale removal method is developed to overcome the limitations of microcracks, complex procedures, and time-consuming conventional fabrication and lithography methods. The method is implemented with a mechanically induced poly-Si phase transition using atomic force microscope (AFM). Mechanical force induces the covalent bonds between silicon and fluorine atoms which cause the phase transition of poly-Si. Then, the bond structure of the Si molecules is weakened and selectively removed by nano-Newton-scale force using AFM. A selective nanoscale removal with roughness control is implemented in 0.5 mM TBAF solution after mechanical force (43.58–58.21 nN) is applied. By the magnitude of nano-Newton force, the removal depth of poly-Si is controlled from 2.66 to 21.52 nm. Finally, the nanoscale fabrication on poly-Si wafer is achieved. The proposed nanoremoval mechanism is a simple fabrication method that provides selective, nanoscale, and highly efficient removal with roughness control.     

基于粗糙集的决策树构造算法

针对ID3算法构造决策树复杂、分类效率不高问题,基于粗糙集理论提出一种决策树构造算法。该算法采用加权分类粗糙度作为节点选择属性的启发函数,与信息增益相比,能全面地刻画属性分类的综合贡献能力,并且计算简单。为消除噪声对选择属性和生成叶节点的影响,利用变精度粗糙集模型对该算法进行优化。实验结果表明,该算法构造的决策树在规模与分类效率上均优于ID3算法。     

基于粗糙性度量的彩色图像分割方法

彩色图像分割技术是现代图像处理和图像分析领域的重要研究议题. 结合粗糙集理论, 利用像素邻域的空间信息, 可以构造图像色彩分布的上下近似以及量化粗糙性表示, 并据此设计基于量化粗糙信息的分割方法: QR measure, 该方法依据数据分布获取自适应阈值进行峰值选定和区域合并. 实验采用UC Berkeley开放的图像分割测试集, 通过比较基于多种统计信息的分割方法, 验证提出的优化算法可以取得更好的分割效果.     

表面粗糙度检查仪微机改造方法

介绍一种通过人机交互式界面选择控制设定表面粗糙度检测仪测量参数的方法。该方法可有效地消除人为因素的影响,稳定测量精度,简化操作。     

SUPPRESSION OF PERIOD DOUBLING CHATTER IN HIGH-SPEED MILLING BY SPINDLE SPEED VARIATION

Spindle speed variation is a well known technique to suppress regenerative machine tool vibrations, but it is usually considered to be effective only for low spindle speeds. In the current paper, spindle speed variation is applied to the high speed milling process, at the spindle speeds where the constant speed cutting results in period doubling chatter. The stability analysis of triangular and sinusoidal shape variations is made numerically with the semi-discretization method. It is shown that the milling process can be stabilized by increasing the amplitude of the spindle speed variation, while the frequency of the variation has no significant effect on the dynamic behaviour. The results are validated by experiments. Based on the analysis of the machined workpieces, it is shown that the surface roughness can also be decreased by the spindle speed variation technique.     

SiCp/Al复合材料三维表面粗糙度信息提取方法

为研究SiCp/Al复合材料三维表面粗糙度信息的提取方法,进行高速铣削实验,并利用OLS3000激光共聚焦扫描显微镜对表面微观轮廓进行非接触式测量.采用最小二乘法、高斯滤波法和扩展高斯滤波法针对已加工表面进行三维粗糙度信息的提取,并计算三维粗糙度参数,从受缺陷的影响程度以及稳定性两方面对3种方法的信息提取效果进行对比.结果表明:高斯滤波法和扩展的高斯滤波法对缺陷的敏感程度较高,且提取出的信息稳定性不好;最小二乘法能很好保留缺陷的信息并具有较高的稳定性,更适合对颗粒增强型铝基复合材料进行三维表面粗糙度信息的提取.     

基于DWT的路面不平度模拟的研究

为了更好地模拟实测路面不平度,提出了基于DWT的FD过程路面不平度模型.与传统的AR模型相比,该模型模拟的等级路面不平度精度高且时间开销小.利用离散小波变换对FD过程去相关,并采用平稳或非平稳FD过程最大可能性估计,对实测路面不平度进行了模拟,结果表明:所模拟的路面不平度与实测路面不平度比较相近.     

渠道糙率率定误差分析

本文研究了渠道糙率率定误差与水力测量误差的函数关系。根据水力学原理,提出了计算渠道糙率率定误差的公式,然后计算分析了南水北调中线京石段应急供水工程实测流量、水深误差产生的渠道糙率率定的误差.得到重要结论:(1)微小的水力测量误差可能产生较大的渠道糙率率定误差,现有南水北调中线典型渠道原型观测糙率误差可达11%;(2)糙率的流量误差分量相对值与流量测量误差基本相同;(3)糙率的进出口水深误差分量绝对值非常接近,两者绝对值大小不仅与水深测量误差成正比,而且与渠道长度有关,当渠道过短时,糙率的水深误差分量将成倍增加。     

Influence of surface roughness on flotation kinetics of quartz

Surface roughness of quartz particles was determined by measuring the specific surface area of particles. The wettability characteristics of particles were determined by measuring the flotation rate using a laboratory flotation cell. Experimental results show that the rod mill product has higher roughness than the ball mill product. For the particles with larger surface roughness, the flotation kinetics constant is also higher. Finally, empirical relationships between surface roughness (r) and the flotation kinetics constant (k) of quartz particles as k=A+Br+Cr ^0.5lnr+D/lnr+E/r and k=A+Br are presented, in which A, B, C, D and E are constants related to experimental conditions and mineralogical properties of mineral.