Five kinds of Al-Zn-Mg-Cu-Zr based alloys with different Sc additions were prepared by ingot metallurgy. The effects of minor Sc on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr based alloys were inve...Five kinds of Al-Zn-Mg-Cu-Zr based alloys with different Sc additions were prepared by ingot metallurgy. The effects of minor Sc on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr based alloys were investigated using tensile tests, optical microscopy （OM）, and transmission electron microscopy （TEM）. The results show that the ultimate tensile strength and yield strength are improved by 94 and 110 MPa, respectively, and the elongation to failure remains at a reasonable extent （11.1%） in the Al-Zn-Mg-Cu-Zr based alloy with 0.21 wt.% Sc addition after solution heat treatment at 475°C for 40 min and then aged at 120°C for 24 h. The addition of minor Sc induces the formation of Al3（Sc,Zr） particles, which are highly effective in refining the cast microstructures, retarding recrystallization, and pinning dislocations. The increment of strength is attributed mainly to fine grain strengthening, precipitation strengthening of Al3（Sc,Zr） particles, and substructure strengthening.展开更多
With the rapid development of shale gas exploration and development in China,casing deformation in shale gas horizontal wells happens frequently,which directly impacts the development efficiency and benefits of shale ...With the rapid development of shale gas exploration and development in China,casing deformation in shale gas horizontal wells happens frequently,which directly impacts the development efficiency and benefits of shale gas.In order to explore casing deformation prediction,prevention and treatment methods,this paper analyzes the geological and engineering causes of casing deformation in shale-gas horizontal wells through laboratory work,such as the casing resistance to internal pressure alternating test,the ground simulation test and systematical casing deformation characteristic analysis of MIT24 caliper logging,and the large-scale physical simulation test and numerical simulation of casing deformation.Then,combined with the generalized shear activity criterion,a new method for evaluating casing deformation risk points and some technical measures for preventing casing deformation were formulated.And the following research results were obtained.First,the deformation characteristics of 119 casing deformation points in 23 wells interpreted by MIT24 caliper logging are consistent with the mechanical behaviors of shear compression deformation test.Second,the large-scale physical simulation test shows that natural fault-fractures slip obviously under the state of strike-slip stress.Third,numerical simulation shows that the compression stress on casing increases with the increase of fault-fracture slip.When the fault-fracture slip is between 7.5 mm and 9.0 mm,the casing reaches the critical yield strength and begins to undergo plastic deformation.The“temporary fracture plugging+long segment and multi-cluster”and other technologies are field tested in 28 wells in Weiyuan area of southern Sichuan Basin.The casing deformation rate decreases from 54%(before this research)to 14.3%,and the segment loss rate decreases from 7.8%to 0,which reveals remarkable achievements in casing deformation treatment.In conclusion,the shear slip of fault and macro fractures(referred to as fault-fracture)is the main cause of casing deformation in shale gas horizontal wells,and some measures(e.g.“temporary fracture plugging+long segment and multi-cluster”,reducing fracturing scale and releasing wellbore pressure properly)shall be taken in advance to reduce the fault-fracture activity before the risk point of casing deformation is fractured,so as to reach the goal of casing deformation prevention.展开更多
背景与目的:研究期刊载文特征,对于期刊管理、把握正确办刊方向具有重要意义。本文探讨《中国普通外科杂志》发展的客观规律及其在医学领域的影响程度,对其2017-2022年间的载文特征进行分析,为期刊发展和影响力提升提供参考。方法:采用...背景与目的:研究期刊载文特征,对于期刊管理、把握正确办刊方向具有重要意义。本文探讨《中国普通外科杂志》发展的客观规律及其在医学领域的影响程度,对其2017-2022年间的载文特征进行分析,为期刊发展和影响力提升提供参考。方法:采用文献计量学方法,检索“中国知网”获得《中国普通外科杂志》2017-2022年发表的论文,从发文量、基金文献量、发文机构、作者、关键词等维度进行统计,并对期刊的海外传播情况进行分析。结果:统计区间内,期刊发文量总体上呈下降趋势,基金文献量呈波动状态,但刊物基金文献比呈上升趋势,发文机构主要来源于高水平医院。核心作者群有黄耿文、王志明、李新营、纪连栋等,研究热点主要聚焦于肿瘤的外科治疗及预后等,有97篇文献在Web of Science中被116篇文献引用。结论:《中国普通外科杂志》已聚集了一批高质量的作者群体,并得到了学科领域内重要研究机构的认可,期刊学术质量日益提升。建议在编辑加工过程减少论文中的无效关键词,提升论文被检索的频率和成果的利用率,避免核心作者群过于依赖同一单位,同时充分发挥海外编委作用,提升期刊国际化传播能力。展开更多
为了解决已有研究成果无法有效解决动态障碍空间中的不确定数据聚类问题,根据障碍集合是否发生变化,分别解决静态障碍和动态障碍空间下的聚类问题。提出了静态障碍空间中的不确定数据聚类算法(DBSCAN clustering algorithm for static o...为了解决已有研究成果无法有效解决动态障碍空间中的不确定数据聚类问题,根据障碍集合是否发生变化,分别解决静态障碍和动态障碍空间下的聚类问题。提出了静态障碍空间中的不确定数据聚类算法(DBSCAN clustering algorithm for static obstacles in grid space,STA_GOBSCAN)、障碍物动态增加情况下的不确定数据聚类算法(DBSCAN clustering algorithm for dynamic increase of obstacles in grid space,DYN_GOCBSCAN)、障碍物动态减少情况下的不确定数据聚类算法(DBSCAN clustering algorithm for dynamicreduction of obstacles in grid space,DYN_GORBSCAN)和障碍物动态移动情况下的不确定数据聚类算法(DBSCAN clustering algorithm for dynamic movement of obstacles in grid space,DYN_GOMBSCAN),采用KL距离对不确定数据进行相似性度量,并利用网格对数据空间进行划分。理论研究和实验结果表明所提出的算法具有较高的效率和准确率。展开更多
基金supported by the National High-Tech Research and Development Program of China (No. 2006AA03Z523)
文摘Five kinds of Al-Zn-Mg-Cu-Zr based alloys with different Sc additions were prepared by ingot metallurgy. The effects of minor Sc on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr based alloys were investigated using tensile tests, optical microscopy （OM）, and transmission electron microscopy （TEM）. The results show that the ultimate tensile strength and yield strength are improved by 94 and 110 MPa, respectively, and the elongation to failure remains at a reasonable extent （11.1%） in the Al-Zn-Mg-Cu-Zr based alloy with 0.21 wt.% Sc addition after solution heat treatment at 475°C for 40 min and then aged at 120°C for 24 h. The addition of minor Sc induces the formation of Al3（Sc,Zr） particles, which are highly effective in refining the cast microstructures, retarding recrystallization, and pinning dislocations. The increment of strength is attributed mainly to fine grain strengthening, precipitation strengthening of Al3（Sc,Zr） particles, and substructure strengthening.
基金supported by the Scientific Research and Technology Development Project of CNPC“Research and field test of key technologies for effective exploitation of deep shale gas”(No.2019F-31JT).
文摘With the rapid development of shale gas exploration and development in China,casing deformation in shale gas horizontal wells happens frequently,which directly impacts the development efficiency and benefits of shale gas.In order to explore casing deformation prediction,prevention and treatment methods,this paper analyzes the geological and engineering causes of casing deformation in shale-gas horizontal wells through laboratory work,such as the casing resistance to internal pressure alternating test,the ground simulation test and systematical casing deformation characteristic analysis of MIT24 caliper logging,and the large-scale physical simulation test and numerical simulation of casing deformation.Then,combined with the generalized shear activity criterion,a new method for evaluating casing deformation risk points and some technical measures for preventing casing deformation were formulated.And the following research results were obtained.First,the deformation characteristics of 119 casing deformation points in 23 wells interpreted by MIT24 caliper logging are consistent with the mechanical behaviors of shear compression deformation test.Second,the large-scale physical simulation test shows that natural fault-fractures slip obviously under the state of strike-slip stress.Third,numerical simulation shows that the compression stress on casing increases with the increase of fault-fracture slip.When the fault-fracture slip is between 7.5 mm and 9.0 mm,the casing reaches the critical yield strength and begins to undergo plastic deformation.The“temporary fracture plugging+long segment and multi-cluster”and other technologies are field tested in 28 wells in Weiyuan area of southern Sichuan Basin.The casing deformation rate decreases from 54%(before this research)to 14.3%,and the segment loss rate decreases from 7.8%to 0,which reveals remarkable achievements in casing deformation treatment.In conclusion,the shear slip of fault and macro fractures(referred to as fault-fracture)is the main cause of casing deformation in shale gas horizontal wells,and some measures(e.g.“temporary fracture plugging+long segment and multi-cluster”,reducing fracturing scale and releasing wellbore pressure properly)shall be taken in advance to reduce the fault-fracture activity before the risk point of casing deformation is fractured,so as to reach the goal of casing deformation prevention.
文摘背景与目的:研究期刊载文特征,对于期刊管理、把握正确办刊方向具有重要意义。本文探讨《中国普通外科杂志》发展的客观规律及其在医学领域的影响程度,对其2017-2022年间的载文特征进行分析,为期刊发展和影响力提升提供参考。方法:采用文献计量学方法,检索“中国知网”获得《中国普通外科杂志》2017-2022年发表的论文,从发文量、基金文献量、发文机构、作者、关键词等维度进行统计,并对期刊的海外传播情况进行分析。结果:统计区间内,期刊发文量总体上呈下降趋势,基金文献量呈波动状态,但刊物基金文献比呈上升趋势,发文机构主要来源于高水平医院。核心作者群有黄耿文、王志明、李新营、纪连栋等,研究热点主要聚焦于肿瘤的外科治疗及预后等,有97篇文献在Web of Science中被116篇文献引用。结论:《中国普通外科杂志》已聚集了一批高质量的作者群体,并得到了学科领域内重要研究机构的认可,期刊学术质量日益提升。建议在编辑加工过程减少论文中的无效关键词,提升论文被检索的频率和成果的利用率,避免核心作者群过于依赖同一单位,同时充分发挥海外编委作用,提升期刊国际化传播能力。
文摘为了解决已有研究成果无法有效解决动态障碍空间中的不确定数据聚类问题,根据障碍集合是否发生变化,分别解决静态障碍和动态障碍空间下的聚类问题。提出了静态障碍空间中的不确定数据聚类算法(DBSCAN clustering algorithm for static obstacles in grid space,STA_GOBSCAN)、障碍物动态增加情况下的不确定数据聚类算法(DBSCAN clustering algorithm for dynamic increase of obstacles in grid space,DYN_GOCBSCAN)、障碍物动态减少情况下的不确定数据聚类算法(DBSCAN clustering algorithm for dynamicreduction of obstacles in grid space,DYN_GORBSCAN)和障碍物动态移动情况下的不确定数据聚类算法(DBSCAN clustering algorithm for dynamic movement of obstacles in grid space,DYN_GOMBSCAN),采用KL距离对不确定数据进行相似性度量,并利用网格对数据空间进行划分。理论研究和实验结果表明所提出的算法具有较高的效率和准确率。
