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锥体法和球缺法模型分析新拌混凝土坍落度及扩展度
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作者 张立勃 《粉煤灰综合利用》 CAS 2018年第5期140-142,共3页
对新拌混凝土的稠度及工作性指标坍落度sl与扩展度sf进行了建模,根据坍落体的形状,分别建立了锥体法和球缺法两种模型,经过计算,得出了两者之间关系的推导公式;依据该推导公式,计算了某一模型下坍落度sl和扩展度sf,然后与最优经验值sl/s... 对新拌混凝土的稠度及工作性指标坍落度sl与扩展度sf进行了建模,根据坍落体的形状,分别建立了锥体法和球缺法两种模型,经过计算,得出了两者之间关系的推导公式;依据该推导公式,计算了某一模型下坍落度sl和扩展度sf,然后与最优经验值sl/sf≈0.4进行模拟分析和比较,得知两种模型各有其优缺点,但锥体法模型更接近混凝土真实的坍落情况。 展开更多
关键词 锥体 球缺法 模型 坍落度 扩展度
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A fast detection algorithm for ceramic ball surface defects based on fringe reflection 被引量:2
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作者 SUN Ying FU Lu-hua WANG Zhong 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2020年第1期28-37,共10页
A ceramic ball is a basic part widely used in precision bearings.There is no perfect testing equipment for ceramic ball surface defects at present.A fast visual detection algorithm for ceramic ball surface defects bas... A ceramic ball is a basic part widely used in precision bearings.There is no perfect testing equipment for ceramic ball surface defects at present.A fast visual detection algorithm for ceramic ball surface defects based on fringe reflection is designed.By means of image preprocessing,grayscale value accumulative differential positioning,edge detection,pixel-value row difference and template matching,the algorithm can locate feature points and judge whether the spherical surface has defects by the number of points.Taking black silicon nitride ceramic balls with a diameter of 6.35 mm as an example,the defect detection time for a single gray scale image is 0.78 s,and the detection limit is 16.5μm. 展开更多
关键词 ceramic ball surface defect fringe reflection visual detection algorithm
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Defective MoS_2 electrocatalyst for highly efficient hydrogen evolution through a simple ball-milling method 被引量:4
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作者 张丽芳 柯小行 +3 位作者 欧刚 魏呵呵 王鲁宁 伍晖 《Science China Materials》 SCIE EI CSCD 2017年第9期849-856,共8页
Molybdenum disulfide(MoS2) has attracted extensive attention as an alternative to replace noble electrocatalysts in the hydrogen evolution reaction(HER). Here, we highlight an efficient and straightforward ball mi... Molybdenum disulfide(MoS2) has attracted extensive attention as an alternative to replace noble electrocatalysts in the hydrogen evolution reaction(HER). Here, we highlight an efficient and straightforward ball milling method,using nanoscale Cu powders as reductant to reduce MoS2 engineering S-vacancies into MoS2 surfaces, to fabricate a defectrich MoS2material(DR-MoS2). The micron-sized DR-MoS2 catalysts exhibit significantly enhanced catalytic activity for HER with an overpotential(at 10 mA cm^-2) of 176 m V in acidic media and 189 m V in basic media, surpassing most of Mo-based catalysts previously reported, especially in basic solution. Meanwhile stability tests confirm the outstanding durability of DR-MoS2 catalysts in both acid and basic electrolytes. This work not only opens a new pathway to implant defects to MoS2, but also provides low-cost alternative for efficient electrocatalytic production of hydrogen in both alkaline and acidic environments. 展开更多
关键词 ELECTROCATALYST hydrogen evolution MOS2 DEFECTS Svacancies
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