Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has...Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application.Theoretical analysis on machining mechanics indicates that work material property,machining strategy,and cutting tool geometry largely afFect machining distortion on the machined microstructure.Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials.Experimental results demonstrate that the material property,cutting tool edge radius,and cutting force play a significant role in the machined micro-structure accuracy and surface finish,while grain boundary of brass has no significant effect on the micro-milling performance.The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool.The main reasons to achieve this outcome are based on:the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius,which contributes to better machinability of brass.One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool.It is believed that the outcomes of this study would largely benefit the research community and end-users.展开更多
目的研究微学习教学法在急危重症综合救治能力培训中的应用效果。方法选取2022年1月—2023年6月于徐州医科大学附属医院东院重症医学科(intensive care unit,ICU)培训的25名学员纳入微学习组,另将徐州医科大学附属医院本部ICU培训的25...目的研究微学习教学法在急危重症综合救治能力培训中的应用效果。方法选取2022年1月—2023年6月于徐州医科大学附属医院东院重症医学科(intensive care unit,ICU)培训的25名学员纳入微学习组,另将徐州医科大学附属医院本部ICU培训的25名学员纳入对照组。对照组采取传统教学法培训,微学习组采取传统教学基础上联合微学习教学法培训,对比2组学员出科理论考试成绩、技能考试成绩以及对教学方法的满意度测评。结果出科考核微学习组学员的理论成绩和技能总成绩均高于对照组[(82.16±6.78)分、(84.32±3.09)分vs.(78.04±6.67)分、(77.84±3.32)分],差异有统计学意义(P<0.05);微学习组教学满意度评分高于对照组[(93.16±3.25)分vs.(88.48±5.00)分],差异有统计学意义(P<0.001)。结论在急危重症综合救治能力培训中应用微学习教学法,学员的理论和技能成绩更高,满意度更高。展开更多
文摘针对某铁路项目现有微台阶法等施工开挖台架机械化水平低,作业效率低等问题,设计出一种适配多种开挖工法的履带式悬挑开挖台架,以满足现场采用微台阶等工法开挖的需求,并能克服走行低效的问题.经实地应用与分析,开挖工序单循环进尺两榀,开挖工序使用本台架较传统平均用时节约0.8 h,单循环进尺三榀较传统平均用时节约0.5 h;立架工序单循环立架两榀,使用本台架立架工序较传统平均用时节约0.4 h,单循环立架三榀较传统台架平均用时节约0.5 h.
文摘Ultra-precision machining has been well known as a very precise and effective way to prototype and fabricate different types of components with microstructures.In this paper,an ultra-precision micro-milling method has been presented to produce a micro-step pillar array as an embossing mold for semiconductor application.Theoretical analysis on machining mechanics indicates that work material property,machining strategy,and cutting tool geometry largely afFect machining distortion on the machined microstructure.Experimental investigation has been conducted on micromachining of the micro-step pillar array using different types of cutting tools and work materials.Experimental results demonstrate that the material property,cutting tool edge radius,and cutting force play a significant role in the machined micro-structure accuracy and surface finish,while grain boundary of brass has no significant effect on the micro-milling performance.The best outcome among the tests done is achieved when using brass as work material and cutting with a straight-edge single crystalline diamond tool.The main reasons to achieve this outcome are based on:the brass material having a higher elastic modulus and the diamond tool having a smaller cutting edge radius,which contributes to better machinability of brass.One micro-step pillar array has been successfully obtained with very precise feature and dimensional accuracy using brass work material and single-crystal diamond tool.It is believed that the outcomes of this study would largely benefit the research community and end-users.
文摘目的研究微学习教学法在急危重症综合救治能力培训中的应用效果。方法选取2022年1月—2023年6月于徐州医科大学附属医院东院重症医学科(intensive care unit,ICU)培训的25名学员纳入微学习组,另将徐州医科大学附属医院本部ICU培训的25名学员纳入对照组。对照组采取传统教学法培训,微学习组采取传统教学基础上联合微学习教学法培训,对比2组学员出科理论考试成绩、技能考试成绩以及对教学方法的满意度测评。结果出科考核微学习组学员的理论成绩和技能总成绩均高于对照组[(82.16±6.78)分、(84.32±3.09)分vs.(78.04±6.67)分、(77.84±3.32)分],差异有统计学意义(P<0.05);微学习组教学满意度评分高于对照组[(93.16±3.25)分vs.(88.48±5.00)分],差异有统计学意义(P<0.001)。结论在急危重症综合救治能力培训中应用微学习教学法,学员的理论和技能成绩更高,满意度更高。
