以空气-水作为介质,探究气举泵气液两相流的压力和流量特性,并基于压力信号的时域、功率谱密度函数(power spectral density,PSD)和概率密度函数(probability density function,PDF)分析鉴别流型。结果表明:除了进气喷嘴附近外,其他位...以空气-水作为介质,探究气举泵气液两相流的压力和流量特性,并基于压力信号的时域、功率谱密度函数(power spectral density,PSD)和概率密度函数(probability density function,PDF)分析鉴别流型。结果表明:除了进气喷嘴附近外,其他位置的局部平均压力随气体流速的增大逐渐上升达到峰值后减小,峰值随着浸没比的减小而向右移动且上升速度增大;液体流速随着气体流速增大急剧上升达到峰值后几乎保持不变,最大提升效率约为49%,与最大液体流速并不发生在同一个气体流速下;在不同的气流量下,观测到气泡流、帽弹流、弹状流、搅拌流和环状流的出现,不同流型可通过PSD和PDF估计量进行识别;特别是,浸没比越小越有利于形成大气塞。目前,关于气举泵的研究非常有限,本研究结果可为气液固三相流和气液两相流的研究提供数据和技术支撑。展开更多
国土空间规划是落实主体功能区战略、绘制未来“美丽国土一张蓝图”的重要抓手,资源环境承载能力和国土空间开发适宜性评价是国土空间规划编制的前提和基础.以贵州省黔西南布依族苗族自治州义龙新区为研究对象,围绕生态保护、农业生产...国土空间规划是落实主体功能区战略、绘制未来“美丽国土一张蓝图”的重要抓手,资源环境承载能力和国土空间开发适宜性评价是国土空间规划编制的前提和基础.以贵州省黔西南布依族苗族自治州义龙新区为研究对象,围绕生态保护、农业生产、城镇建设功能特征,以定量方法为主、定性方法为辅,依次开展了资源环境要素单项评价、资源环境承载能力集成评价、国土空间开发适宜性评价,并与现状土地利用进行对比,识别其国土空间开发问题和潜力.结果表明:①义龙新区生态保护极重要区面积占比为36.93%,农业生产适宜区面积占比为24.84%,城镇建设适宜区面积占比为25.08%,三者可分别作为重点生态功能区、农产品主产区、城市化发展区.②生态保护极重要区中基本农田面积为23.60 km 2、一般农用地面积为15.21 km 2,农业生产不适宜区中基本农田面积为72.17 km 2、一般农用地面积为27.63 km 2,地块功能指向重叠性较大,建议结合城市发展意向,明确不同区域功能指向的侧重.③后备耕地面积为131.87 km 2,后备建设用地面积为114.85 km 2,与实地核查结果相符.研究显示,构建的喀斯特地区“双评价”方法体系可以很好地应用于区域国土空间规划,实现了格网单元地域功能优化分区.展开更多
Functional zoning is a key step for the integrated planning and scientific management of a national park.Selecting the Three-River-Source National Park(TNP)as the study area,this paper establishes an evaluation system...Functional zoning is a key step for the integrated planning and scientific management of a national park.Selecting the Three-River-Source National Park(TNP)as the study area,this paper establishes an evaluation system including 13 evaluation indexes which are classified into four categories,namely:ecosystem services;potential distribution of key species habitats;ecological sensitivity;and ecological resilience through the comprehensive analysis on the regional eco-environmental features in the study area.The results of the comprehensive analysis,combined with the functions and requirements of management of national parks,indicate that TNP is divided into the first-level zone(the core conservation area,the ecological restoration area and the traditional utilization area)with definite targets of space management and the second-level zone with implementation of control measures.This method of functional zoning lays a solid foundation for the scientific planning of TNP;moreover,our study provides new insights into other national parks’functional zoning.展开更多
The reintroduction of rare and endangered species is one of the most important approaches to conservation and ecosystem restoration,but it has still proven to be an adventurous undertaking and most reintroduction prog...The reintroduction of rare and endangered species is one of the most important approaches to conservation and ecosystem restoration,but it has still proven to be an adventurous undertaking and most reintroduction programmes fail,so successful demonstrations are needed.Père David’s deer(Elaphurus davidianus,Milu in Chinese)could be considered one of conservation’s great success stories,as this species’path on the road to extinction has been reversed by a combination of ex-situ conservation and successful re-introduction in China.The species had been consigned to an imperial hunting ground when the last Chinese herds were exterminated during the fall of the Qing Dynasty(1644-1912).Fortunately,a few of the last remaining individuals were sent to European zoos.From these animals,a herd was bred on the 14;Duke of Bedford’s estate,Woburn Abbey,and between 1985and 1987,and 38 Milu were donated back to China for re-introduction in Beijing Milu Park(BMP),the former imperial hunting ground.An additional 39 deer were released at Dafeng National Nature Reserve(DFNNR),Jiangsu Province in 1986.In both of these safe and protected locations,the Milu thrived allowing for over 700 Milu to be sent to a further 82 sites throughout the species’original Chinese range over the last 36 years.As a result,the Milu population totaled 9136 by 2021,with 2855 individuals now living back in the wild;while another 5681 individuals inhabit the DFNNR,and 186 reside in BMP.Wild Milu,however,still face significant conservation challenges.The population lacks genetic diversity,leading to severe inbreeding depression and carrying multiple risks,such as high miscarriage rates,a reduced lifespan,and susceptibility to disease.Environmental constraints such as pollution and habitat fragmentation further result in small,fragmented wild populations.Moreover,the species currently lacks a national level conservation master plan,the associated coordinated monitoring platforms,and breeding plans for China’s captive populations.Finally,there is now a lack of international cooperation in the conservation of this species.We therefore call for both a national-level conservation master plan in China and international cooperation to develop a shared database and germplasm databank covering Milu across all countries with ex-situ populations,as crucial steps for securing the long-term conservation of Milu and preventing it from ever becoming“extinct in the wild”again.展开更多
文摘以空气-水作为介质,探究气举泵气液两相流的压力和流量特性,并基于压力信号的时域、功率谱密度函数(power spectral density,PSD)和概率密度函数(probability density function,PDF)分析鉴别流型。结果表明:除了进气喷嘴附近外,其他位置的局部平均压力随气体流速的增大逐渐上升达到峰值后减小,峰值随着浸没比的减小而向右移动且上升速度增大;液体流速随着气体流速增大急剧上升达到峰值后几乎保持不变,最大提升效率约为49%,与最大液体流速并不发生在同一个气体流速下;在不同的气流量下,观测到气泡流、帽弹流、弹状流、搅拌流和环状流的出现,不同流型可通过PSD和PDF估计量进行识别;特别是,浸没比越小越有利于形成大气塞。目前,关于气举泵的研究非常有限,本研究结果可为气液固三相流和气液两相流的研究提供数据和技术支撑。
文摘国土空间规划是落实主体功能区战略、绘制未来“美丽国土一张蓝图”的重要抓手,资源环境承载能力和国土空间开发适宜性评价是国土空间规划编制的前提和基础.以贵州省黔西南布依族苗族自治州义龙新区为研究对象,围绕生态保护、农业生产、城镇建设功能特征,以定量方法为主、定性方法为辅,依次开展了资源环境要素单项评价、资源环境承载能力集成评价、国土空间开发适宜性评价,并与现状土地利用进行对比,识别其国土空间开发问题和潜力.结果表明:①义龙新区生态保护极重要区面积占比为36.93%,农业生产适宜区面积占比为24.84%,城镇建设适宜区面积占比为25.08%,三者可分别作为重点生态功能区、农产品主产区、城市化发展区.②生态保护极重要区中基本农田面积为23.60 km 2、一般农用地面积为15.21 km 2,农业生产不适宜区中基本农田面积为72.17 km 2、一般农用地面积为27.63 km 2,地块功能指向重叠性较大,建议结合城市发展意向,明确不同区域功能指向的侧重.③后备耕地面积为131.87 km 2,后备建设用地面积为114.85 km 2,与实地核查结果相符.研究显示,构建的喀斯特地区“双评价”方法体系可以很好地应用于区域国土空间规划,实现了格网单元地域功能优化分区.
基金National Key Research and Development Program of China,No.2017YFC0503806
文摘Functional zoning is a key step for the integrated planning and scientific management of a national park.Selecting the Three-River-Source National Park(TNP)as the study area,this paper establishes an evaluation system including 13 evaluation indexes which are classified into four categories,namely:ecosystem services;potential distribution of key species habitats;ecological sensitivity;and ecological resilience through the comprehensive analysis on the regional eco-environmental features in the study area.The results of the comprehensive analysis,combined with the functions and requirements of management of national parks,indicate that TNP is divided into the first-level zone(the core conservation area,the ecological restoration area and the traditional utilization area)with definite targets of space management and the second-level zone with implementation of control measures.This method of functional zoning lays a solid foundation for the scientific planning of TNP;moreover,our study provides new insights into other national parks’functional zoning.
文摘The reintroduction of rare and endangered species is one of the most important approaches to conservation and ecosystem restoration,but it has still proven to be an adventurous undertaking and most reintroduction programmes fail,so successful demonstrations are needed.Père David’s deer(Elaphurus davidianus,Milu in Chinese)could be considered one of conservation’s great success stories,as this species’path on the road to extinction has been reversed by a combination of ex-situ conservation and successful re-introduction in China.The species had been consigned to an imperial hunting ground when the last Chinese herds were exterminated during the fall of the Qing Dynasty(1644-1912).Fortunately,a few of the last remaining individuals were sent to European zoos.From these animals,a herd was bred on the 14;Duke of Bedford’s estate,Woburn Abbey,and between 1985and 1987,and 38 Milu were donated back to China for re-introduction in Beijing Milu Park(BMP),the former imperial hunting ground.An additional 39 deer were released at Dafeng National Nature Reserve(DFNNR),Jiangsu Province in 1986.In both of these safe and protected locations,the Milu thrived allowing for over 700 Milu to be sent to a further 82 sites throughout the species’original Chinese range over the last 36 years.As a result,the Milu population totaled 9136 by 2021,with 2855 individuals now living back in the wild;while another 5681 individuals inhabit the DFNNR,and 186 reside in BMP.Wild Milu,however,still face significant conservation challenges.The population lacks genetic diversity,leading to severe inbreeding depression and carrying multiple risks,such as high miscarriage rates,a reduced lifespan,and susceptibility to disease.Environmental constraints such as pollution and habitat fragmentation further result in small,fragmented wild populations.Moreover,the species currently lacks a national level conservation master plan,the associated coordinated monitoring platforms,and breeding plans for China’s captive populations.Finally,there is now a lack of international cooperation in the conservation of this species.We therefore call for both a national-level conservation master plan in China and international cooperation to develop a shared database and germplasm databank covering Milu across all countries with ex-situ populations,as crucial steps for securing the long-term conservation of Milu and preventing it from ever becoming“extinct in the wild”again.
