Natural slopes usually display complicated exposed rock surfaces that are characterized by complex and substantial terrain undulation and ubiquitous undesirable phenomena such as vegetation cover and rockfalls.This st...Natural slopes usually display complicated exposed rock surfaces that are characterized by complex and substantial terrain undulation and ubiquitous undesirable phenomena such as vegetation cover and rockfalls.This study presents a systematic outcrop research of fracture pattern variations in a complicated rock slope,and the qualitative and quantitative study of the complex phenomena impact on threedimensional(3D)discrete fracture network(DFN)modeling.As the studies of the outcrop fracture pattern have been so far focused on local variations,thus,we put forward a statistical analysis of global variations.The entire outcrop is partitioned into several subzones,and the subzone-scale variability of fracture geometric properties is analyzed(including the orientation,the density,and the trace length).The results reveal significant variations in fracture characteristics(such as the concentrative degree,the average orientation,the density,and the trace length)among different subzones.Moreover,the density of fracture sets,which is approximately parallel to the slope surface,exhibits a notably higher value compared to other fracture sets across all subzones.To improve the accuracy of the DFN modeling,the effects of three common phenomena resulting from vegetation and rockfalls are qualitatively analyzed and the corresponding quantitative data processing solutions are proposed.Subsequently,the 3D fracture geometric parameters are determined for different areas of the high-steep rock slope in terms of the subzone dimensions.The results show significant variations in the same set of 3D fracture parameters across different regions with density differing by up to tenfold and mean trace length exhibiting differences of 3e4 times.The study results present precise geological structural information,improve modeling accuracy,and provide practical solutions for addressing complex outcrop issues.展开更多
The Gaoligong Mountains(GLGM),located in southwestern China,extend north to south along the western border of the Hengduan Mountains,spanning approximately 600 km.In this study,we consolidated findings from 17 bird su...The Gaoligong Mountains(GLGM),located in southwestern China,extend north to south along the western border of the Hengduan Mountains,spanning approximately 600 km.In this study,we consolidated findings from 17 bird surveys conducted in the GLGM between 2010 and 2022.We found that the GLGM harbors tremendous bird diversity,with a total of 796 documented bird species in the region.Nearly a quarter(23.0%)of these species are listed as state key protected species or as Chinese and global threatened species.Analysis of species richness at the county level showed a decreasing trend with increasing latitude,with the greatest diversity in Yingjiang(661 species).Observations indicated that the GLGM belongs to the Oriental realm,primarily composed of bird species from southern and southwestern China.The GLGM plays an important role in avian conservation by sheltering exceptional bird diversity,providing corridors and flyways for bird migration and dispersal,and mitigating the effects of climate change.In response to the conservation needs of birds and other wildlife,the Chinese government has established numerous protected areas within the GLGM.Despite these efforts,avian conservation still faces considerable challenges in the GLGM due to limitations in the protected area network,transboundary nature of the regions,and existing gaps in monitoring and research.展开更多
Aero-engine fan blades of ten use a cavity structure to improve the thrust-to-weight ratio of the aircraft.However,the use of the cavity structure brings a series of difficulties to the manufacturing and processing of...Aero-engine fan blades of ten use a cavity structure to improve the thrust-to-weight ratio of the aircraft.However,the use of the cavity structure brings a series of difficulties to the manufacturing and processing of the blades.Due to the limitation of blade manufacturing technology,it is difficult for the internal cavity structure to achieve the designed contour shape,so the blade has uneven wall thickness and poor consistency,which affects the fatigue performance and airflow dynamic performance of the blade.In order to reduce the influence of uneven wall thickness,this paper proposes a grinding allowance extraction method considering the double dimension constraints(DDC)of the inner and outer contours of the hollow blade.Constrain the two dimensions of the inner and outer contours of the hollow blade.On the premise of satisfying the outer contour constraints,the machining model of the blade is modified according to the distribution of the inwall contour to obtain a more reasonable distribution of the grinding allowance.On the premise of satisfying the contour constraints,according to the distribution of the inwall contour,the machining model of the blade is modified to obtain a more reasonable distribution of the grinding allowance.Through the grinding experiment of the hollow blade,the surface roughness is below Ra0.4μm,and the contour accuracy is between-0.05~0.14 mm,which meets the processing requirements.Compared with the allowance extraction method that only considers the contour,the problem of poor wall thickness consistency can be effectively improved.It can be used to extract the allowance of aero-engine blades with hollow features,which lays a foundation for the study of hollow blade grinding methods with high service performance.展开更多
基于青海牛苦头露天金属矿边坡工程,首先根据地质因素和工程因素,把边坡分成5个地质区域。然后对地勘资料和室内试验数据进行统计分类,利用CSMR(Chinese Slope Mass Rating)法对边坡进行分级评价。选取代表性剖面进行二维数值计算分析,...基于青海牛苦头露天金属矿边坡工程,首先根据地质因素和工程因素,把边坡分成5个地质区域。然后对地勘资料和室内试验数据进行统计分类,利用CSMR(Chinese Slope Mass Rating)法对边坡进行分级评价。选取代表性剖面进行二维数值计算分析,运用GEO-SLOPE软件对边坡稳定性进行初算,再采用MSARMA法综合考虑边坡的排水能力与地震荷载情况对边坡进行极限平衡分析。最后依据分析计算结果和实际工况优选合适的边坡角。展开更多
学术成果通过社交媒体传播日益流行,由此催生Altmetrics相关研究的兴起。当前该领域研究主要集中于国际科研成果在国际社交媒体平台的交流活动,对国际科研成果面向本土社交媒体用户传播的研究较为缺乏。本研究通过采集和对比分析Nature...学术成果通过社交媒体传播日益流行,由此催生Altmetrics相关研究的兴起。当前该领域研究主要集中于国际科研成果在国际社交媒体平台的交流活动,对国际科研成果面向本土社交媒体用户传播的研究较为缺乏。本研究通过采集和对比分析Nature期刊在国际主流学术平台Web of Science(以下简称WoS)和本土社交媒体平台微信上的用户使用数据,揭示Nature期刊论文跨语种平台用户行为模式。研究发现,不同平台用户使用数据差异明显,仅存在微弱负相关,进一步针对使用量前100的文献进行主题和内容分析发现,议程设置对微信平台用户选择偏好具有明显影响,微信用户更倾向于非专业化标题文章,且更多受惊奇驱动和实用价值驱动。展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC3080200)the National Natural Science Foundation of China(Grant No.42022053)the China Postdoctoral Science Foundation(Grant No.2023M731264).
文摘Natural slopes usually display complicated exposed rock surfaces that are characterized by complex and substantial terrain undulation and ubiquitous undesirable phenomena such as vegetation cover and rockfalls.This study presents a systematic outcrop research of fracture pattern variations in a complicated rock slope,and the qualitative and quantitative study of the complex phenomena impact on threedimensional(3D)discrete fracture network(DFN)modeling.As the studies of the outcrop fracture pattern have been so far focused on local variations,thus,we put forward a statistical analysis of global variations.The entire outcrop is partitioned into several subzones,and the subzone-scale variability of fracture geometric properties is analyzed(including the orientation,the density,and the trace length).The results reveal significant variations in fracture characteristics(such as the concentrative degree,the average orientation,the density,and the trace length)among different subzones.Moreover,the density of fracture sets,which is approximately parallel to the slope surface,exhibits a notably higher value compared to other fracture sets across all subzones.To improve the accuracy of the DFN modeling,the effects of three common phenomena resulting from vegetation and rockfalls are qualitatively analyzed and the corresponding quantitative data processing solutions are proposed.Subsequently,the 3D fracture geometric parameters are determined for different areas of the high-steep rock slope in terms of the subzone dimensions.The results show significant variations in the same set of 3D fracture parameters across different regions with density differing by up to tenfold and mean trace length exhibiting differences of 3e4 times.The study results present precise geological structural information,improve modeling accuracy,and provide practical solutions for addressing complex outcrop issues.
基金supported by the National Key R&D Program of China(2022YFC2602500,2022YFC2602502)Biodiversity Survey and Assessment Project of the Ministry of Ecology and Environment,China,Second Xizang Plateau Scientific Expedition and Research Program(STEP,2019QZKK0501)+3 种基金Major Science and Technique Programs in Yunnan Province(202102AA310055)National Natural Science Foundation of China(32070435)Science and Technology Basic Resources Investigation Program of China“Wild germplasm collection and preservation in Great Gaoligong Mountain”(2021FY100200)Project for Talent and Platform of Science and Technology in Yunnan Province Science and Technology Department(202205AM070007)。
文摘The Gaoligong Mountains(GLGM),located in southwestern China,extend north to south along the western border of the Hengduan Mountains,spanning approximately 600 km.In this study,we consolidated findings from 17 bird surveys conducted in the GLGM between 2010 and 2022.We found that the GLGM harbors tremendous bird diversity,with a total of 796 documented bird species in the region.Nearly a quarter(23.0%)of these species are listed as state key protected species or as Chinese and global threatened species.Analysis of species richness at the county level showed a decreasing trend with increasing latitude,with the greatest diversity in Yingjiang(661 species).Observations indicated that the GLGM belongs to the Oriental realm,primarily composed of bird species from southern and southwestern China.The GLGM plays an important role in avian conservation by sheltering exceptional bird diversity,providing corridors and flyways for bird migration and dispersal,and mitigating the effects of climate change.In response to the conservation needs of birds and other wildlife,the Chinese government has established numerous protected areas within the GLGM.Despite these efforts,avian conservation still faces considerable challenges in the GLGM due to limitations in the protected area network,transboundary nature of the regions,and existing gaps in monitoring and research.
基金Supported by National Natural Science Foundation of China(Grant No.U1908232)National Science and Technology Major Project(Grant No.2017-VII-0002-0095).
文摘Aero-engine fan blades of ten use a cavity structure to improve the thrust-to-weight ratio of the aircraft.However,the use of the cavity structure brings a series of difficulties to the manufacturing and processing of the blades.Due to the limitation of blade manufacturing technology,it is difficult for the internal cavity structure to achieve the designed contour shape,so the blade has uneven wall thickness and poor consistency,which affects the fatigue performance and airflow dynamic performance of the blade.In order to reduce the influence of uneven wall thickness,this paper proposes a grinding allowance extraction method considering the double dimension constraints(DDC)of the inner and outer contours of the hollow blade.Constrain the two dimensions of the inner and outer contours of the hollow blade.On the premise of satisfying the outer contour constraints,the machining model of the blade is modified according to the distribution of the inwall contour to obtain a more reasonable distribution of the grinding allowance.On the premise of satisfying the contour constraints,according to the distribution of the inwall contour,the machining model of the blade is modified to obtain a more reasonable distribution of the grinding allowance.Through the grinding experiment of the hollow blade,the surface roughness is below Ra0.4μm,and the contour accuracy is between-0.05~0.14 mm,which meets the processing requirements.Compared with the allowance extraction method that only considers the contour,the problem of poor wall thickness consistency can be effectively improved.It can be used to extract the allowance of aero-engine blades with hollow features,which lays a foundation for the study of hollow blade grinding methods with high service performance.
文摘基于青海牛苦头露天金属矿边坡工程,首先根据地质因素和工程因素,把边坡分成5个地质区域。然后对地勘资料和室内试验数据进行统计分类,利用CSMR(Chinese Slope Mass Rating)法对边坡进行分级评价。选取代表性剖面进行二维数值计算分析,运用GEO-SLOPE软件对边坡稳定性进行初算,再采用MSARMA法综合考虑边坡的排水能力与地震荷载情况对边坡进行极限平衡分析。最后依据分析计算结果和实际工况优选合适的边坡角。
文摘学术成果通过社交媒体传播日益流行,由此催生Altmetrics相关研究的兴起。当前该领域研究主要集中于国际科研成果在国际社交媒体平台的交流活动,对国际科研成果面向本土社交媒体用户传播的研究较为缺乏。本研究通过采集和对比分析Nature期刊在国际主流学术平台Web of Science(以下简称WoS)和本土社交媒体平台微信上的用户使用数据,揭示Nature期刊论文跨语种平台用户行为模式。研究发现,不同平台用户使用数据差异明显,仅存在微弱负相关,进一步针对使用量前100的文献进行主题和内容分析发现,议程设置对微信平台用户选择偏好具有明显影响,微信用户更倾向于非专业化标题文章,且更多受惊奇驱动和实用价值驱动。
