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Resolution Increase and Noise Removal in Particle Size Distribution Measurement with Shifrin Transform 被引量:1
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作者 韩月 杨宗苓 +4 位作者 乔星 钱鹏 袁银男 丁思红 戴兵 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2015年第4期446-451,共6页
Based on the laser diffraction and Shifrin transform,the measurement method of particle size distribution has been improved extensively.While in real measurements,some noise peaks exist in the inversion data and are e... Based on the laser diffraction and Shifrin transform,the measurement method of particle size distribution has been improved extensively.While in real measurements,some noise peaks exist in the inversion data and are easily to be misread as particle distribution peaks.The improved method used a truncation function as a filter is hard to distinguish adjacent peaks.Here,by introducing the bimodal resolution criterion,the filter function is optimized,and to a quasi truncation function with the optimized filter function is studied to achieve optimal bimodal resolution and to remove noise peaks.This new quasi truncation function fits multimode distribution very well.By combining the quasi truncation function with Shifrin transform,noise peaks are removed well and the adjacent peaks are distinguished clearly.Finally,laser diffraction experiments are conducted and the particle size distribution is analyzed by adoping the method.The results show that the quasi truncation function has better bimodal resolution than the truncation function.Generally,by combining the quasi truncation function with the Shifrin transform,in particle size distribution measurements with laser diffraction,the bimodal resolution is greatly increased and the noise is removed well.And the results can restore the original distribution perfectly.Therefore,the new method with combination of the quasi truncation function and the Shifrin transform provides a feasible and effective way to measure the multimode particle size distribution by laser diffraction. 展开更多
关键词 DIFFRACTION particle size distribution Shifrin transform quasi truncation function INVERSION
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二维分形轮廓微凸体面积分布函数的研究
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作者 刘帅 原园 +1 位作者 刘晨茜 乔路群 《机械工程学报》 北大核心 2025年第21期329-344,共16页
微凸体面积分布函数是对Korcak公式微分获得,其表达形式直接决定分形接触模型的准确性。根据Korcak公式建立了微凸体截面直径与数量的关系式N(Λ>l)=λ(l_(max)/l)^(B),采用数值方法分别对Weierstrass-Mandelbrot函数、傅里叶变换和... 微凸体面积分布函数是对Korcak公式微分获得,其表达形式直接决定分形接触模型的准确性。根据Korcak公式建立了微凸体截面直径与数量的关系式N(Λ>l)=λ(l_(max)/l)^(B),采用数值方法分别对Weierstrass-Mandelbrot函数、傅里叶变换和机械加工生成的二维分形轮廓进行分析计算,拟合出参数λ、B和l_(max)与分形参数、截断高度的数学表达式,并推导出修正的微凸体面积分布函数。结果表明:参数B仅与轮廓分形维数D和截断高度有关,在任意分形轮廓平均高度附近,B的值近似等于D-1;参数λ和l_(max)取决于基准取样长度、取样长度、轮廓参数等因素,不同的分形轮廓对应的λ和l_(max)表达式互不相同;对比Weierstrass-Mandelbrot函数、机械加工生成的二维分形轮廓的实测截断面积,修正的微凸体面积分布函数能较为精确获得不同类型分形轮廓的真实截断面积,而经典微凸体面积分布函数适用于取样长度为γ^(-nmin)的WM函数模拟的分形轮廓真实截断面积的计算。 展开更多
关键词 分形轮廓 微凸体 微凸体面积分布函数 取样长度 截断高度
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