自动照准全站仪精密三角高程测量在跨河水准测量中的应用

随着全自动智能型全站仪的发展及光学水准仪的逐步淘汰,精密三角高程测量在跨河高程传递方面应用广泛。本文详细介绍了基于全自动照准全站仪的精密三角高程测量的四边形跨河水准测量方法的原理及步骤,并对该方法中对向观测获取跨河点间高差进行了理论推导和精度分析,证明了控制在一定跨河距离内并采取相应措施消除其他误差的情况下,该方法可用于二等水准跨河测量;最后通过实例证实了该方法能满足二等跨河水准测量精度要求。     

京津冀协同治理的回顾与前瞻

京津冀区域治理是伴随三地协作发展的进程,从政府层面的管制转向各利益主体协调治理,从自上而下的竞争合作转向上下结合的协同合作的一系列有效应对举措。经过30多年的努力,学界和政府部门已经形成了较为丰富的京津冀区域治理研究成果。通过梳理自1984年以来相关区域的研究,尝试从时空维度厘清京津冀区域治理的研究脉络及其变化,剖析目前京津冀区域治理所涉及的治理模式、协调体系、以及形成的发展策略,为改进和提高京津冀区域治理效果提供参考。京津冀协同治理过程是学术界与政府的互动融合过程,其中政府的作用居主导地位。未来将在治理主体、治理机制、治理效果评价和文化、医疗、养老等领域的协调发展方面得到深化和细化。     

国外乡村空间研究的进展与启示

任何空间都是社会的产物。在工业化、城镇化、信息化和政策的驱动下,中国乡村空间正在发生剧烈重构。乡村空间研究作为国外乡村地理学研究的核心内容之一,具有多学科、多视角、多维度、多方法的特点,形成了一个丰富的研究图景。为了更全面地把握国外乡村空间研究的进展,论文对国外近40 a的乡村空间研究文献进行了梳理。研究发现,国外学者从物质、想象和实践等层面诠释了乡村空间的内涵,并通过建立“乡村空间的三重模型”,强调了日常生活实践的重要性,引入了生活空间,构建了较为系统的乡村空间研究架构。在理论视角上,国外乡村空间研究经历了功能主义、政治经济学和社会建构主义3个阶段;在时间的演进上,实现了由生产主义空间研究到后生产主义空间研究的转换;在空间维度上,实现了聚落空间、经济空间、社会空间和文化空间的多重叠加。国外乡村空间研究实现了从物质层面到社会表征、从客体性空间到主体性空间、从静态单维空间到动态多维空间的转变,启示我们对乡村空间进行跨学科研究以及“社会-文化”研究的重要性。中国乡村空间建设要重视农民的主体性地位、强调乡村空间的多功能性、尊重乡村空间的“地域性”和“差异性”、恢复乡村空间的意义生产功能。     

How forest gaps shaped plant diversity along an elevational gradient in Wolong National Nature Reserve?

Journal of Geographical Sciences - Understanding the underlying ecological processes that control plant diversity within (α-diversity) and among (β-diversity) forest gaps is important for...     

四种重金属对刺参幼参的急性致毒效应

采用静水试验法,在水温18.5℃~20℃的条件下,用Cu2 ,Zn2 ,Cd2 和Cr6 四种重金属对刺参幼参进行了单一急性毒性试验。结果表明:Cu2 对刺参幼参的24h,48h,72h和96hLC50分别为0.299,0.176,0.133和0.120mg/L;Zn2 的24h,48h,72h和96hLC50分别为6.700,3.624,2.577和1.951mg/L;Cd2 的24h,48h和72hLC50分别为4.246,2.588和2.137mg/L;Cr6 的24h,48h和72hLC50分别为31.974,7.499和3.808mg/L;Cu2 ,Zn2 ,Cd2 和Cr6 对刺参幼参的安全浓度分别为0.018,0.362,0.259和0.750mg/L。四种重金属对刺参幼参的毒性大小依次为Cu2 >Cd2 >Zn2 >Cr6 。     

Preliminary study on different nutrient pools supplies for the phytoplankton growth in the Jiaozhou Bay in China in the fall of 2004

The source and significance of two nutrients, nitrogen and phosphorous, were investigated by a modified dilution method performed on seawater samples from the Jiaozhou Bay, in autumn 2004. This modified dilution method accounted for the phytoplankton growth rate, microzooplankton grazing mortality rate, the internal and external nutrient pools, as well as nutrient supplied through remineralization by microzooplankton. The results indicated that the phytoplankton net growth rate increased in turn from inside the bay, to outside the bay, to in the Xiaogang Harbor. The phytoplankton maximum growth rates and microzooplankton grazing mortality rates were 1.14 and 0.92 d-1 outside the bay, 0.42 and 0.32 d-1 inside the bay and 0.98 and 0.62 d-1 in the harbor respectively. Outside the bay, the remineralized nitrogen (Kr=24.49) had heavy influence on the growth of the phytoplankton. Inside the bay, the remineralized phosphorus(Kr=3.49) strongly affected the phytoplankton growth. In the harbor, the remineralized phosphorus (Kr=3.73) was in larger demand by phytoplankton growth. The results demonstrated that the different nutrients pools supplied for phytoplankton growth were greatly in accordance with the phytoplankton community structure, microzooplankton grazing mortality rates and environmental conditions. It is revealed that nutrient remineralization is much more important for the phytoplankton growth in the Jiaozhou Bay than previously believed.     

Changes in timber haul emissions in the context of shifting forest management and infrastructure

Background  

Although significant amounts of carbon may be stored in harvested wood products, the extraction of that carbon from the forest generally entails combustion of fossil fuels. The transport of timber from the forest to primary milling facilities may in particular create emissions that reduce the net sequestration value of product carbon storage. However, attempts to quantify the effects of transport on the net effects of forest management typically use relatively sparse survey data to determine transportation emission factors. We developed an approach for systematically determining transport emissions using: 1) -remotely sensed maps to estimate the spatial distribution of harvests, and 2) - industry data to determine landscape-level harvest volumes as well as the location and processing totals of individual mills. These data support spatial network analysis that can produce estimates of fossil carbon released in timber transport.     

基于遗传—神经网络方法的广西台风灾害评估模型研究

选取1981—2018年影响广西且灾情记录比较完整的86个台风样本,基于台风灾害伤亡人数、直接经济损失划分灾情等级,选取致灾因子,利用遗传算法与神经网络相结合的方法建立广西台风灾害评估模型.结果表明:选取的台风灾害致灾因子与台风灾情等级之间具有显著的相关性,构建的遗传—神经网络集合预报模型对台风灾情预估效果较好,训练样...     

西辽河流域归一化植被指数与气象因子相关性分析

为了解西辽河流域归一化植被指数(NDVI)的分布规律、变化趋势及对气候变化的响应,利用2000—2018年西辽河流域11个气象站逐日气象资料和MODIS归一化植被指数数据集,通过线性回归和相关分析,探讨了生长季各月NDVI与气象因子的时滞性,以及气象站周围10 km缓冲区内不同植被类型NDVI与气象因子的相关性.结果表...     

论新型基础测绘体系建设

基础测绘作为测绘事业的核心组成部分,具有法定性、战略性、公益性和专业性.新型基础测绘要在承载法律法规赋予的法定任务基础上,面向自然资源管理、国土空间规划、工程建设管理、公共安全与应急管理以及其他政务管理和公众服务等对公共测绘地理信息成果及服务的需要,建立由理念、成果、服务、技术和机制等要素构成的新型基础测绘体系,提升基...