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造船质量标准中关于圆度率与百分率的表述
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作者 郑本成 李捷 《舰船标准化工程师》 2004年第5期42-44,共3页
本文用国内外的一些实例分析了椭圆率与圆度率的概念,对与百分率表示法和百分率在计算中的使用提出了推荐性的建议,以期达到标准上的统一。
关键词 造船工业 质量标准 标准化 圆度率 百分
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基于机器视觉技术的烟叶规整度数字化表征
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作者 梁晏凯 杨家琪 +6 位作者 罗姗 孔明 徐超 詹映 彭云发 刘晨凯 李一辉 《今日制造与升级》 2024年第5期94-98,共5页
为了研究烟叶规整度的表征方法,通过机器视觉平台采集烟叶图像,并对图像进行灰度化、滤波、二值化等预处理。利用深度优先搜索算法结合哈希表标记每个连通区域,以区分每片烟叶。随后,提取每片烟叶的边缘轮廓,并计算其对应的边缘坐标平... 为了研究烟叶规整度的表征方法,通过机器视觉平台采集烟叶图像,并对图像进行灰度化、滤波、二值化等预处理。利用深度优先搜索算法结合哈希表标记每个连通区域,以区分每片烟叶。随后,提取每片烟叶的边缘轮廓,并计算其对应的边缘坐标平均值、最小外接圆面积和最大内切圆面积,同时对烟叶进行了不同角度的模拟切丝。结果表明,烟叶的圆度率可以通过其最大内切圆与最小外接圆的面积比值来表征,而模拟切丝后的长丝波动与圆度率呈负相关(相关系数为-0.81),即圆度率越高,切丝后的长丝波动越小。因此,所建立的圆度率方法能有效表征烟叶的规整度:当烟叶的圆度率越接近1时,烟叶形状越规整,无论从哪个角度进行切丝,形成的烟丝长短基本一致,烟丝结构的波动也越小。 展开更多
关键词 机器视觉 滤波 边缘轮廓 模拟切丝 圆度率
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基于超像素的印刷电路板过孔分割算法 被引量:1
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作者 宋熙煜 周利莉 +3 位作者 陈健 曾磊 闫镔 徐一夫 《计算机应用》 CSCD 北大核心 2015年第A02期258-262,共5页
现有的SIOX等主流图像分割算法对印刷电路板(PCB)CT分层图像中的过孔分割质量较差,而实际中常用的基于Hough变换的分割算法在PCB图像噪声大时容易出现分割错误。为解决以上问题,提出一种基于超像素的PCB CT图像过孔分割算法。首先通过... 现有的SIOX等主流图像分割算法对印刷电路板(PCB)CT分层图像中的过孔分割质量较差,而实际中常用的基于Hough变换的分割算法在PCB图像噪声大时容易出现分割错误。为解决以上问题,提出一种基于超像素的PCB CT图像过孔分割算法。首先通过对比实验在六种常用的超像素分割算法中选择一种最适合PCB CT图像的算法进行超像素分割,利用具有局部特征表达能力的超像素代替像素作为分割的基本处理单元。针对过孔表现出的显著圆形特征,引入圆度率对超像素的形状特征进行描述和表达,在此基础上设计一种全新的超像素合并与筛选策略来提取过孔目标,最后通过形态学处理得到最终分割结果。通过实验对比,选择ERS算法对PCB CT分层图像进行超像素分割;与基于Hough变换的分割算法相比,新提出方法在分割准确率和召回率两方面均提高了约10%,特别是在图像背景噪声较大时出现错误分割的概率明显小于基于Hough变换的分割算法。基于超像素的PCB CT图像过孔分割算法克服了PCB CT图像噪声大、图像灰度不均匀等情况对分割带来的困难,能够准确地从PCB CT图像的复杂背景中提取出过孔目标。 展开更多
关键词 印刷电路板 过孔分割 超像素 圆度率 超像素合并 HOUGH变换
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Study on applicability of modal analysis of thin finite length cylindrical shells using wave propagation approach
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作者 李冰茹 王宣银 +1 位作者 葛辉良 丁渊明 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第10期1122-1127,共6页
Donnell’s thin shell theory and basic equations based on the wave propagation method discussed in detail here, is used to investigate the natural frequencies of thin finite length circular cylindrical shells under va... Donnell’s thin shell theory and basic equations based on the wave propagation method discussed in detail here, is used to investigate the natural frequencies of thin finite length circular cylindrical shells under various boundary conditions. Mode shapes are drawn to explain the circumferential mode number n and axial mode number m, and the natural frequencies are cal-culated numerically and compared with those of FEM (finite element method) to confirm the reliability of the analytical solution. The effects of relevant parameters on natural frequencies are discussed thoroughly. It is shown that for long thin shells the method is simple, accurate and effective. 展开更多
关键词 Wave propagation Natural frequency Mode shape Cylindrical shell
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Wafer-scale arrayed p-n junctions based on few-layer epitaxial GaTe 被引量:5
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作者 Xiang Yuan Lei Tang +12 位作者 Peng Wang Zhigang Chen Yichao Zou Xiaofeng Su Cheng Zhang Yanwen Liu Weiyi Wang Cong Liu Fansheng Chen Jin Zou Peng Zhou Weida Hu Faxian Xiu 《Nano Research》 SCIE EI CAS CSCD 2015年第10期3332-3341,共10页
Two-dimensional (2D) materials have attracted substantial attention in electronic and optoelectronic applications with the superior advantages of being flexible, transparent, and highly tunable. Gapless graphene exh... Two-dimensional (2D) materials have attracted substantial attention in electronic and optoelectronic applications with the superior advantages of being flexible, transparent, and highly tunable. Gapless graphene exhibits ultra-broadband and fast photoresponse while the 2D semiconducting MoS2 and GaTe exhibit high sensitivity and tunable responsivity to visible light. However, the device yield and repeatability call for further improvement to achieve large-scale uniformity. Here, we report a layer-by-layer growth of wafer-scale GaTe with a high hole mobility of 28.4 cm^2/(V.s) by molecular beam epitaxy. The arrayed p-n )unctions were developed by growing few-layer GaTe directly on fhree-inch Si wafers. The resultant diodes reveal good rectifying characteristics and a high photovoltaic external quantum efficiency up to 62% at 4.8 μW under zero bias. The photocurrent reaches saturation fast enough to capture a time constant of 22 μs and shows no sign of device degradation after 1.37 million cycles of operation. Most strikingly, such high performance has been achieved across the entire wafer, making the volume production of devices accessible. Finally, several photoimages were acquired by the GaTe/Si photodiodes with reasonable contrast and spatial resolution, demonstrating the potential of integrating the 2D materials with silicon technology for novel optoelectronic devices. 展开更多
关键词 GATE wafer-scaletwo-dimensional materials p-n junction imaging PHOTODIODE PHOTOSENSOR
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