为了解岩溶碳循环及碳汇效应研究热点和发展方向,基于Web of Science核心合集引文索引数据库,对1997年1月1日-2023年6月30日间的573篇文献进行了文献计量学引文分析。利用Cite Space软件对关键词频率、国家(地区)和机构分布、作者影响...为了解岩溶碳循环及碳汇效应研究热点和发展方向,基于Web of Science核心合集引文索引数据库,对1997年1月1日-2023年6月30日间的573篇文献进行了文献计量学引文分析。利用Cite Space软件对关键词频率、国家(地区)和机构分布、作者影响、研究热点、共被引文献以及主题演变进行了分析。结果表明,以刘再华为核心的研究团队继承和发扬了袁道先提出的岩溶作用参与全球碳循环并具有碳汇效应的观点,并提出了偶联碳酸盐岩风化碳汇模型,极大推动了岩溶碳汇的研究。关键词聚类的时间线图和关键词时区图清楚地展现了该领域的发展动态,可认为岩溶碳循环及碳汇效应领域经历3个发展阶段:1)1997-2006年的起步阶段,粗略估算了全球碳酸盐岩风化回收大气CO_(2)的量为0.110~0.608 Gt C·a^(-1),占全球碳遗漏的15%~30%;2)2007-2014年的碳酸盐岩化学风化研究快速发展阶段,主要关注不同流域在外源酸、径流条件及植被覆盖对碳酸盐岩风化的影响;3)2015年之后以大气-生物-土壤-水-基岩为系统的岩溶关键带理论指导下的碳循环及碳汇效应研究新阶段,考虑了水生生物光合作用、气候变化及土地利用变化等条件下岩溶碳循环及碳汇效应。展开更多
[ Objective] The reseamh aimed to analyze the relationship between vertical distribution of four automatic stations and local precipitation in Taihang Mountain of Linzhou. [ Method] Using mesoscale detection and stati...[ Objective] The reseamh aimed to analyze the relationship between vertical distribution of four automatic stations and local precipitation in Taihang Mountain of Linzhou. [ Method] Using mesoscale detection and statistical data of the automatic stations in Henan, the geographical distribution of the precipitation affected by underlying surface in mountainous area of Linzhou was analyzed. [ Result] Surface mesoscale wind field convergence line formed by thermal action of inhomogeneous underlying surface and mountainous terrain and upward movement played the strengthening role to the low-level jet. They affected formation and development of strong convective weather. The geographic distribution of precipitation in mountainous area was highly affected by the terrain, and rainfall, precipitation days and intensity in mountainous area were significantly greater than that in the surrounding hills region. In particular, rainfall on the windward slope significantly increased, and rainfall increased as mountain height within a certain height. [ Conclusion] Hourly ground data analysis at automatic stations had very good forecast indication role in formation, development and dissipation of heavy rain in mountainous areas.展开更多
In order to achieve omnidirectional locomotion on rough terrain with multi-legged biomimetic robot,a free gait generation approach is proposed based on local rules.The phase coordinates of each operation leg was estab...In order to achieve omnidirectional locomotion on rough terrain with multi-legged biomimetic robot,a free gait generation approach is proposed based on local rules.The phase coordinates of each operation leg was established according to the motion task and a universal depiction of leg-end locomotion was implemented;the mathematical relation of gait pattern and walking velocity of multi-legged robot was put forward;combined polynomial curve was adopted to generate the leg-end trajectory,which was capable of accomplishing walking missions and accommodating to landform conditions;a distributed network of local rules for gait control was constructed based on a set of local rules operating between adjacent legs.In the simulation experiments,adaptive regulation of inter-leg phase sequence,omnidirectional locomotion and ground accommodation were realized.Moreover,statically stable free gait was obtained simultaneously,which provided multi-legged robot with the capability of walking on irregular terrain reliably and expeditiously.展开更多
Augmented reality is the merging of synthetic sensory information into a user's perception of a real environment. As one of the most important tasks in augmented scene modeling, terrain simplification research has...Augmented reality is the merging of synthetic sensory information into a user's perception of a real environment. As one of the most important tasks in augmented scene modeling, terrain simplification research has gained more and more attention. In this paper, we mainly focus on point selection problem in terrain simplification using triangulated irregular network. Based on the analysis and comparison of traditional importance measures for each input point, we put forward a new importance measure based on local entropy. The results demonstrate that the local entropy criterion has a better performance than any traditional methods. In addition, it can effectively conquer the 'short-sight' problem associated with the traditional methods.展开更多
文摘[ Objective] The reseamh aimed to analyze the relationship between vertical distribution of four automatic stations and local precipitation in Taihang Mountain of Linzhou. [ Method] Using mesoscale detection and statistical data of the automatic stations in Henan, the geographical distribution of the precipitation affected by underlying surface in mountainous area of Linzhou was analyzed. [ Result] Surface mesoscale wind field convergence line formed by thermal action of inhomogeneous underlying surface and mountainous terrain and upward movement played the strengthening role to the low-level jet. They affected formation and development of strong convective weather. The geographic distribution of precipitation in mountainous area was highly affected by the terrain, and rainfall, precipitation days and intensity in mountainous area were significantly greater than that in the surrounding hills region. In particular, rainfall on the windward slope significantly increased, and rainfall increased as mountain height within a certain height. [ Conclusion] Hourly ground data analysis at automatic stations had very good forecast indication role in formation, development and dissipation of heavy rain in mountainous areas.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No. 2006AA04Z245)the Program for Changjiang Scholars and Innovative Research Team in University(Grant No. IRT0423)
文摘In order to achieve omnidirectional locomotion on rough terrain with multi-legged biomimetic robot,a free gait generation approach is proposed based on local rules.The phase coordinates of each operation leg was established according to the motion task and a universal depiction of leg-end locomotion was implemented;the mathematical relation of gait pattern and walking velocity of multi-legged robot was put forward;combined polynomial curve was adopted to generate the leg-end trajectory,which was capable of accomplishing walking missions and accommodating to landform conditions;a distributed network of local rules for gait control was constructed based on a set of local rules operating between adjacent legs.In the simulation experiments,adaptive regulation of inter-leg phase sequence,omnidirectional locomotion and ground accommodation were realized.Moreover,statically stable free gait was obtained simultaneously,which provided multi-legged robot with the capability of walking on irregular terrain reliably and expeditiously.
基金This paper is supported by the State Key Laboratory for Image Processing & Intelligent Control (No. TKLJ9903) National Defe
文摘Augmented reality is the merging of synthetic sensory information into a user's perception of a real environment. As one of the most important tasks in augmented scene modeling, terrain simplification research has gained more and more attention. In this paper, we mainly focus on point selection problem in terrain simplification using triangulated irregular network. Based on the analysis and comparison of traditional importance measures for each input point, we put forward a new importance measure based on local entropy. The results demonstrate that the local entropy criterion has a better performance than any traditional methods. In addition, it can effectively conquer the 'short-sight' problem associated with the traditional methods.
