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New insights into the in-process densification mechanism of cold spray Al coatings: Low deposition efficiency induced densification

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Journal of Materials Science & Technology 2019年第3期35卷 427-431页

作者： Richard Jenkins Shuo Yin Barry Aldwell Morten Meyer Rocco Lupoi Trinity College Dublin The University of Dublin Department of Mechanical and Manufacturing Engineering

This work details new insights into the in-process densification mechanism of cold spray Al coatings. The results show a trend counter to common observations: coating plastic deformation levels and coating density decreases with an increase in particle impact velocity. A lower particle impact velocity and the consequent lower deposition efficiency(DE) results in greater tamping energy per unit volume of deposit,which is the primary reason for the observed trend. This is the first time that DE has been shown to have a non-linear impact on the density of a cold spray coating, with particle in-process tamping being the primary mechanism for coating densification.

关键词： Coating Hardness test Plastic deformation tamping

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Structure optimal design research on backfill hydraulic support

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Journal of Central South University 2017年第7期24卷 1637-1646页

作者： ZHANG Qiang ZHANG Ji-xiong QI Wen-yue ZHOU Nan TAI Yang State Key Laboratory of Coal Resource and Safe Mining School of MinesChina University of Mining&TechnologyXuzhou 221116China

Backfill hydraulic support is the key equipment in achieving coal mining and solid backfilling simultaneously in solid backfill mining *** on the summary and analysis of main types,basic structural properties and filed application of backfill hydraulic support,this work has firstly proposed the basic principle of backfill hydraulic support optimization design and provided the method of optimal design of key structural components,like four-bar linkage,rear canopy and tamping structure;the method is further elaborated as changing hinging position of upper bar to optimize four-bar linkage,by lengthening or shortening the rear canopy to optimize length ratio of canopy;and by changing length and hinging position of tamping structure as well as suspension height of backfill scrape conveyor to realize optimization of tamping *** this basis,the process of optimal design of backfill hydraulic support is *** optimal design case of ZC5200/14.5/30 six columns-four bar linkage used in 7203 W workface of Zhaizhen Coal Mine shows that the backfill properties like horizontal roof gap,vertical horizontal gap,tamping angle and tamping head gap are improved obviously through optimizing four-bar linkage,canopy length and tamping structure according to the optimal design method proposed in this work.

关键词： backfill hydraulic support structure optimal design four-bar linkage rear canopy tamping structure

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维普期刊数据库

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Clinical analysis of 47 cases with placenta accreta

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生殖医学杂志 2009年第S2期18卷 31-35页

作者：张超边旭明刘欣燕杨剑秋范光升刘俊涛 Department of Obstetrics & Gynecology Peking Union Medical College HospitalPeking Union Medical CollegeChinese Academy of Medical Sciences

Objective:To explore the incidence,risk factors and treatment for placenta accreta. Methods:A retrospective analysis was carried out from May 1997 to May 2007 in Peking Union Medical College Hospital which involved 47 placenta accreta cases and 141 controls. Results:According to our study,the incidence of placenta accreta was 0.262%（47/17,918）.The percentages of placenta previa in case group were significantly higher than those of control group（Ptamping was 86.67%,and UAE was 100%. Conclusion:The incidence of placenta accreta in the second trimester seems increasing,which was higher than the incidence in the third *** incidence of placenta accreta was only related to placenta *** artery embolism was the best conservative *** in the third trimester tamping was still the most effective conservative *** majority of the cases could reserve their reproductive functions.

关键词： Placenta accreta Therapy Uterine artery embolism tamping

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