机载多光谱影像语义分割模型在农田防护林提取中的应用

农田防护林是农田生态系统的屏障,其健康状况的监测与评估在我国北方农田林网管理中尤为重要。本文以新疆生产建设兵团第三师51团为研究区,使用复合翼无人机CW-20搭载Micro MCA12 Snap多光谱相机获取农田防护林的多光谱影像,经辐射校正、裁剪等预处理,通过优选有效特征和模型比较,提出农田防护林提取的有效方法。首先,基于原始12波段,依据相关性系数矩阵和最佳指数因子（Optimum Index Factor,OIF）选取最优3波段和植被指数特征进行组合,构建8种农田防护林提取方案;然后,通过建立语义分割Deeplabv3+模型进行精度评价,得到最优3波段组合6（波长710 nm）、8（波长800 nm）、 11（波长900 nm）波段为最佳特征组合;最后,以最优3波段为基础,将Deeplabv3+模型与U-Net、ENVINet5模型进行对比分析。结果表明：Deeplabv3+模型能够更深层次的挖掘光谱中潜在的信息,相比其他模型,能够较好地处理正负样本不均衡问题,获得最高MIoU值85.54%,比U-Net、ENVINet5的MIoU值则分别高出21.21%、27.19%。该研究结果可为基于多光谱遥感影像的语义分割在农田防护林提取及健康状况监测的应用提供借鉴和参考。     

基于非线性扫描技术的可控震源地震勘探分辨率提高方法

可控震源地震扫描信号易被地下介质吸收并形成高频部分衰减,降低对地下地质体的分辨能力.分析地震信号扫描方式,研究非线性扫描信号特性及其在补偿地层吸收衰减的地震相关子波信号影像中的作用,利用正演模拟和现场试验验证非线性扫描信号在提高可控震源地震勘探地震分辨率中的作用.结果表明:非线性扫描通过控制高频能量信号的时间分配,提高激发信号的高频成分,选择合适的非线性扫描信号类型和激发能量,能够提高地震勘探分辨率.该研究结果对实现高分辨率地震勘探具有一定的参考意义.     

Relationship between flow speed variability of three tidewater glaciers and surface melt intensity in Greenland between 1979 and 2006

The margin of the Greenland ice sheet has undergone rapid changes over the past decade as a result of the thinning, acceleration, and retreat of many fast-flowing tidewater outlet glaciers. Satellite observations show that three major tidewater outlet glaciers in Greenland retreated between 2000 and 2005, with synchronous increases in flow speed, causing a deficit in ice sheet mass budget and the potential for sea level rise. In this study, we investigated whether this acceleration was related to surface melt processes, and found that both flow speed and positive degree day (PDD) anomalies of the three glaciers varied together, indicating a causal relationship. Jakobshavn Isbræ had lower flow speeds before 2000, during which PDD anomalies were negative, except for modest warming in 1993 and 1995. From 1999–2000, during which it is thought a threshold was passed, the flow speed of the glacier started to increase. However, the two glaciers in east Greenland showed a delayed response. Abrupt warming occurred in the vicinity of the two glaciers around 2001, but flow speed did not increase until 2003 for the Helheim Glacier, and until 2004 for the Kangerdlugssuaq Glacier. Furthermore, the two eastern glaciers switched to a deceleration mode more quickly than Jakobshavn Isbræ. The observed differences in both acceleration and deceleration among the glaciers suggest that the relationship between surface melt and outlet glacier dynamics is not simple but complex.     

Initiation of primary cell culture from amphioxus <Emphasis Type="Italic">Branchiostoma belcheri tsingtauense</Emphasis>

Amphioxus, a cephalochordate, is an important model fish for studies in evolution and comparative biology. A successful cell culture from amphioxus tissues in vitro would help understanding some basic issues. To determine the optimal culture conditions for proliferation of amphioxus cells, primary cultures were initiated from buccal cirri, tail, gill, gut and metapleural fold of amphioxus Branchiostoma belcheri tsingtauense. The media tested were L-15, F-12, M 199, MEM, DMEM, PRMI 1640 and LDF, each was supplemented with 20% fetal bovine serum. The optimal conditions include tail tissue cultured in L-15 or F-12 with supplement of 20% FBS and 1.5% NaCl at about 25°C. Supported by Doctoral Initial Fund of Ludong University (No.43304)     

2021-04-16河北滦州MS4.3地震前的大气电场异常信号分析

中国科学院国家空间科学中心分布在天津市宝坻区和廊坊市永清县的2个观测台站在2021-04-16河北滦州M_S4.3地震前均观测到大气电场异常。宝坻站监测到过境云与地质活动混合型电场异常信号;永清站监测到湾型持续电场异常信号,属于典型的临震前小时尺度先兆信号,其幅度和持续时间均明显高于宝坻站的异常电场信号。对比电场异常期间2个台站的气象活动和空间天气活动发现,虽然2台站电场异常信号的表现方式不同,但背景变化中均隐含大型地质活动信号。分析结果表明,未来可通过分析多源活动导致的空间静电演变过程,形成有效的识别方法,在一定的气象活动范围内,从大气静电监测数据中提取中等以上强度地震的前兆信息。     

中国经济增长与制度变迁的空间面板数据分析

以North的体制经济学为理论依据,将新古典经济学的Solow增长模型扩展为一个包含制度变量的计量经济学模型,并结合空间面板数据分析方法,使用1997—2005年中国省区的社会经济数据实证检验了经济制度环境对经济增长的影响。研究结果表明:该时期的制度变迁对中国的经济增长具有显著贡献力,证实了North的制度经济学理论假设。此外,空间面板数据的分析方法深入地揭示了省域经济活动之间存在的空间自相关性,即地区之间通过技术扩散、要素转移以及社会文化交流等在地理空间上发生相互影响。     

北京市制造业空间格局演化及影响因子分析

制造业的空间扩散是推动城市空间结构呈现多极化、多中心地域系统的主要驱动力, 对制造业区位变迁及影响因素的研究是认识城市空间重构机制的微观基础。本研究基于北京市1996、2001、2010 年制造业企业数据, 以邮政编码区为空间单元, 刻画了北京市制造业空间集聚格局及演化特征。采用计量模型, 检验了导致北京制造业空间重构的主要区位因子, 对比了这些影响因子作用强度随时间的变化以及在制造业行业间的差异。结果表明, 北京市的制造业在中心城区的集聚度明显减弱, 呈显著的郊区化集聚;主要集聚区位于距市中心半径为15~35 km的空间范围内, 总体空间格局呈现出大都市区尺度上的扩散以及产业园区尺度的再集聚特征。计量模型计算结果显示, 区位通达度、集聚经济、科技园区规划与政策引导是北京制造业总体空间格局演化的主要驱动因素, 但不同区位因子的作用强度存在行业间差异。本研究揭示了北京市的制造业空间重组机制是政府规划引导下的市场经济作用机制。认识到城市经济活动空间重组中市场与政府的交互作用机理, 有助于决策者对转型期大都市区制造业空间集聚和扩散格局进行更加有效地引导, 以优化大都市区的空间结构与功能体系。     

Assessment of Terrestrial Ecosystem Sensitivity and Vulnerability in Tibet

The Tibetan Plateau serves an important shelter function for the ecological security of Asia, and especially China. Here, we proposed and improved indicators and methods for assessing the ecological sensitivity and vulnerability of the terrestrial alpine Plateau ecosystems and assessed the freeze-thaw erosion, land desertification, water-caused soil loss, and land salinization sensitivity, together with ecological vulnerability, from the overall ecological sensitivity, ecological pressure, and elasticity aspects in Tibet. The results indicate that the terrestrial ecosystem of Tibet is quite sensitive to freeze-thaw erosion, land desertification and water-caused soil loss. Extremely and highly sensitive regions account for 9.62% and 83.69%, respectively, of the total area of the Tibet Autonomous Region. Extremely and highly vulnerable areas account for 0.09% and 52.61%, respectively, primarily distributed in the Himalayan and Gangdise mountain regions in west Tibet; the Nyainqentanglha, Tanggula, Hoh Xil, and Kunlun mountain regions; and the northwest and northern regions of the Changtang Plateau. The results will aid the development of customized protection schedules according to different ecological issues in each region.     

城乡中学生地理研学旅行需求的比较分析 ——以陕西省杨陵区为例

研学旅行是课堂教学的拓展与延伸,对培养学生实践能力具有重要的促进作用。对中学生地理研学需求的分析,能够帮助学校、研学机构更加有序地开展地理研学旅行。本文以杨陵第四初级中学和杨凌高新初级中学287名学生为研究对象,利用问卷调查,在地理研学旅行认知、经历、参与意愿的调查分析基础上,对杨陵区城乡中学生地理研学旅行需求进行比较。以期为城乡中学开展地理研学旅行提供参考,在研学活动的组织与实施过程中能充分考虑城乡差异,为不同学生制定合适的地理研学方案,推动城乡中学地理实践教育活动的均衡发展。     

高分辨率全球尺度水文模型发展综述

主要从高分辨率全球尺度水文模型（HRGHM）的发展历程、模型的一般结构与特点、模型数据集的发展和模型所面临的主要问题等几个方面对全球尺度水文模型的发展情况进行了综述。HRGHM能够使水文学家从全球的角度深入了解水资源的产生及循环过程,并且对相关环境问题的解决、气候的模拟与预报以及水资源的管理具有重要的意义。经过几十年的发展和努力,在全球尺度数据集的研究和发展方面已经取得了丰硕的成果,并且在HRGHM的实践中得以应用,但空间数据的缺乏仍然是其发展的最大羁绊。HRGHM所面临的问题除了数据的匮乏还在于非线性问题、尺度问题和确定性问题等水文机理和技术层面的问题。