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纺织纤维——线密度的测定——重量法和振动仪法
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作者 王军 《中国纤检》 1996年第4期27-30,32,共5页
1 范围 本国际标准规定了测定纺织纤维线密度的重量法和振动仪法,分别适用于: a)纤维束; b)单根纤维。 对于人造纤维可以测得有效数据,对天然纤维精度略差。 本试验步骤仅适用于在试验准备过程中纤维能保持伸直和平行的纤维束。
关键词 振动仪 平均线密度 置信区间 重量法 纺织纤维 纤维束 变异系数 根纤维 平均 谐振频率
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一种快速有效的印刷体文字识别算法 被引量:13
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作者 任金昌 赵荣椿 张炜 《中国图象图形学报(A辑)》 CSCD 北大核心 2001年第10期1011-1015,共5页
为了利用低成本的硬件来实现对印刷体文字的快速识别 ,提出了一种基于多级分类的印刷体文字快速识别算法 ,该算法从预处理、特征提取 ,到模式匹配各个阶段 ,都对传统方法作了合理的改进 .该算法首先是采用 36×36 ,而不是传统的 48&... 为了利用低成本的硬件来实现对印刷体文字的快速识别 ,提出了一种基于多级分类的印刷体文字快速识别算法 ,该算法从预处理、特征提取 ,到模式匹配各个阶段 ,都对传统方法作了合理的改进 .该算法首先是采用 36×36 ,而不是传统的 48× 48点阵进行归一化 ,从而有效地减少了计算量和字典容量 ;其次是采用改进的粗外围特征 ,并进行二重分割 ,以提高特征的稳定性 ;最后在各级分类中采用了不同的判别准则 ,包括绝对值距离、欧氏距离及相似度准则 ,以适应于时间、准确性的不同要求 .同时用该算法对一级汉字 70 0 0个样本进行了实验 ,其结果表明 ,实际正确识别率 (正识率 )达 95 % ,前 5位累积正识率可达 98% ,从而为“电子阅读笔”的开发与研制打下了坚实的理论基础 . 展开更多
关键词 印刷体 文字识别 多级分类 规范化 粗外围特征 平均线密度 特征提取 识别算法
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The Neglected Significance of Glomerular Density as a 5-year Progression Indicator for IgA Nephropathy 被引量:4
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作者 陈振杰 李航 +8 位作者 蔡建芳 张鑫 李超 邹佩美 李明喜 陈丽萌 李雪梅 李学旺 文煜冰 《Chinese Medical Sciences Journal》 CAS CSCD 2017年第3期145-151,共7页
Objective To investigate whether glomerular density (GD) could be an independent prognostic factor for patients of IgA nephropathy with estimated glomerular filtration rate (eGFR) of 30 to 60 ml/min per 1.73 m2, ... Objective To investigate whether glomerular density (GD) could be an independent prognostic factor for patients of IgA nephropathy with estimated glomerular filtration rate (eGFR) of 30 to 60 ml/min per 1.73 m2, or for patients with time-average proteinuria 〈 0.5 g/d. Methods A total of 173 patients with biopsy-confirmed IgA nephropathy diagnosed from January 2000 to December 2010 were included. All of these patients were followed up for more than 5 years. The endpoint was a 〉 30% of decline in eGFR from baseline after 5-year follow-up. The optimal cut-off value of GD was calculated by ROC curve. Kaplan-Meier method and Cox regression analysis was used for survival analysis. Results A 30% of decline in eGFR occurred in 14.5% of all patients. The optimal diagnostic cut-off value of GD was 1.99/mm2 (AUC = 0.90, sensitivity = 84.0%, specificity = 81.8%) determined by ROC curve. The low GD group (GD 〈 1.99 per mm2) experienced a significant increase in renal endpoint for patients with eGFR of 30 to 60 ml/min per 1.73 m2 (six patients in lower GD group, while one patient in the other group). For patients with time-average proteinuria 〈 0.5 g/d, the lower GD group showed a higher eGFR decline from baseline (4.5±16.7 ml/min per 1.73 m2 vs. –8.1±21.4 ml/min per 1.73 m2, P = 0.038); two patients in this group reached the endpoint, while no patients in the higher GD group did. Conclusion GD could be an independent prognostic factor for patients of IgA nephropathy with eGFR at 30 to 60 ml/min per 1.73 m2 of body surface, particularly for those with time-averaged amount of urine protein less than 0.5 g per day. 展开更多
关键词 glomerular density IgA nephropathy renal progression
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Radio spectral index of BL Lac objects 被引量:1
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作者 YUAN YuHai FAN JunHui LONG XiaoLi 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第5期1035-1040,共6页
In this paper, the preliminary data from University of Michigan Radio Astronomy Observatory database (UMRAO) are used to discuss the radio spectral index properties of 8 BL Lacs. To do so, we calculated the radio sp... In this paper, the preliminary data from University of Michigan Radio Astronomy Observatory database (UMRAO) are used to discuss the radio spectral index properties of 8 BL Lacs. To do so, we calculated the radio spectral index, a (F oc va), which was obtained by fitting the averaged flux densities in the bands (4.8 GHZ, 8 GHz, and 14.5 GHz) by binning the original for 7 d. We also calculated the time delay between the averaged lightcurves and the spectral variance. Our calculations and analysis give the following results. 1) The averaged logarithmic flux density at 8 GHz (logF) and the corresponding spectral index (or) have strong correlation for all the BL Lacs; 2) the lightcurves and the spectral variability have the similar profile for all the BL Lacs; 3) the lightcurves delay spectral variability for all sources but PKS 0735+178, with the delay time ranging from 31 d to 125 d. 展开更多
关键词 GALAXIES BL Lacs spectral variability parameter time delay
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