下辽河平原景观格局演变与预测分析     

吕乐婷  杨勇  姜俊超  乔皓  白少杰 《地理信息世界》2021,28(5):73-78

以下辽河平原为研究对象,选取1980年、2010年和2018年Landsat TM/ETM+OLI卫星图像进行解译,得到3期土地利用数据,定量分析下辽河平原近40年土地利用时空变化特征.结合地形、交通通达度及限制转化因子采用FLUS(Future Land Use Simulation)模型对流域未来土地利用变化情景及景观格局进行了预测.结果表明:1980-2018年水田、林地、草地、沼泽面积均减少,其中水田面积减少量最大,占比减少了8.59％,旱地、水域和城镇的面积均有所上升,旱地的增长面积最大,占比增加了6.19％;水田、林地、水域转入为旱地面积最大,旱地转出为建设用地面积最大;1980-2018年景观格局发生了较大变化,景观的破碎化程度降低,斑块之间的连通度、聚集程度升高,土地利用的集约化程度增大;2018-2040年,下辽河平原建设用地和水田的变化面积最大,城市化过程更加显著,景观的多样性及空间异质性降低,人类对环境的干扰能力变大.  相似文献   

基于点云数据的不规则文物三维重建——以经幢为例     

喜文飞  李灵索  杨勇  李国柱  李春梅  李金平 《测绘通报》2020,(12):87-89

海量点云数据可以较好地构建文物的三维建模，针对文物复杂的表面结构，传统的算法很难达到精细建模，为了解决复杂模型表面的空间三角网构网问题，本文结合空间三角形的法向量构建三角网，以空间三角网表面的曲率为约束条件，构建物体表面的空间三角网，然后对构建的空间三角网进行精细建模。以昆明市文物——经幢为例进行三维重建试验，结果表明，新方法适合室内文物的三维建模，可以达到较好的效果。  相似文献   

黑河中游夏季昼夜水汽同位素特征及水汽来源分析          下载免费PDF全文

孟鸿飞  张明军  王圣杰  邱雪  杜铭霞  张亚宁  余秀秀  周苏娥 《干旱区地理》2020,43(2):360-370

基于2012年6~8月的实测水汽同位素数据及相关气象数据，对黑河中游夏季昼夜的同位素基本特征、水汽来源方向及潜在蒸发源地进行了研究。结果表明：空气水汽线斜率白天大于夜晚和水汽过量氘值白天大于夜晚，综合说明白天局地蒸发较夜晚强烈；夏季受西风水汽影响显著。其中，6月主要受西风水汽和北冰洋水汽影响，7、8月主要受西风水汽和东南方向水汽影响，且8月受东南方向水汽影响最为明显；水汽运移路径上下垫面地形和气压带移动会影响水汽后向轨迹高度，西北方向上水汽输送通道较顺畅，风速较大，有利于水汽的输送；水汽蒸发源地主要集中在研究区周围及以东、以北部，其次是西北部。绿洲是主要的水汽蒸发源地，其次是城市和河流，白天较夜晚局地蒸发强烈且面积大。  相似文献   

贵州夜郎湖表层水体地球化学昼夜变化及其影响因素     

王家录  任娟  王勇  李维杰  娄昭  陈佳 《热带地理》2020,40(2):335-345

为探究岩溶水库水文地球化学行为过程,对贵州普定夜郎湖表层水体进行了为期3 d的高分辨率昼夜监测。结果表明：1）多变的天气和水文条件叠加导致水体离子指标昼夜变化不显著,规律性较差。而水温、DO、pH值、SpC、SIc、pCO₂等常规理化指标受水温变化和生物作用表现出明显的昼夜波动。2）利用亨利常数和主成分分析,得到温度变化、生物作用、人类活动、水库的蓄水与放水对夜郎湖水库水文地球化学特征变化的贡献率分别为21.66%、17.28%、14.08%和10.22%,说明作用于水库水文地球化学行为的因子具有多元性。3）δ ¹⁸O表现出与DO一致的波动趋势,即白天上升,晚上下降,反映在短时间尺度上,氢氧稳定同位素变化受控于生物过程（主要是呼吸作用过程）;而对比水库水体和大气降水的d-excess（d值）发现,水库水体的d值（8.21‰）显著偏低于当地大气降水的d值（9.64‰）,说明在长时间尺度上,主要受蒸发效应引起的不平衡分馏影响。  相似文献   

Correspondence between the large volcanic eruptions and ENSO events over AD 1525–2000     

Fang  Xiuqi  Zheng  Xue  Zhang  Xing 《地理学报(英文版)》2020,30(1):103-118

ENSO is an interannual mode which may be affected by external forcing, such as volcanic eruptions. Based on the reconstructed volcanic eruptions chronology and ENSO sequences, both 195 large volcanic eruptions(VEI≥4) and 398 ENSO(El Ni?o and La Ni?a) events were extracted from 1525 to 2000. An analysis of the correspondence between the large volcanic eruptions and ENSO events was performed by matching the large volcanic eruptions with the types and magnitudes of ENSO events present in the 0–2 years after the eruptions. The results show the following:(1) The percentages of ENSO events within the 3 years after the large eruptions had increased to 68.3% from 31.7% compared with those with no-eruptions in the previous 0–2 years. In addition, the ratio of El Ni?o to La Ni?a events turned from 2:3 to 1:1, and more El Ni?o events occurred in the 0 year after eruptions in the low-latitudes of the Northern Hemisphere and in the tropics but more La Ni?a events occurred in the 0 year after in the high-latitudes of the Northern Hemisphere and the Southern Hemisphere.(2) After the eruptions, the weak(W) El Ni?o events had increased by 8 percentage points and the very strong(VS) El Ni?o events had decreased by 10 percentage points; conversely, there was a decrease by 15 percentage points of the weak La Ni?a events and an increase by 11.4 percentage points of the very strong La Ni?a events. Specifically, the percentages of strong La Ni?a events increased to a peak at 1(+1) year after the eruptions.(3) The percentage of eruptions followed by single-year ENSO was the greatest. The percentage of ENSO events that occurred in the consecutive 2 years following an eruption was approximately equal to the percentage of events that occurred consecutively 3 years following an eruption, and both sets of ENSO magnitudes showed a decreasing trend.  相似文献   

Pedestrian network generation based on crowdsourced tracking data     

Xue Yang  Chang Ren  Yang Chen  Zhong Xie  Qingquan Li 《International journal of geographical information science》2020,34(5):1051-1074

ABSTRACT

Pedestrian networks play an important role in various applications, such as pedestrian navigation services and mobility modeling. This paper presents a novel method to extract pedestrian networks from crowdsourced tracking data based on a two-layer framework. This framework includes a walking pattern classification layer and a pedestrian network generation layer. In the first layer, we propose a multi-scale fractal dimension (MFD) algorithm in order to recognize the two different types of walking patterns: walking with a clear destination (WCD) or walking without a clear destination (WOCD). In the second layer, we generate the pedestrian network by combining the pedestrian regions and pedestrian paths. The pedestrian regions are extracted based on a modified connected component analysis (CCA) algorithm from the WOCD traces. We generate the pedestrian paths using a kernel density estimation (KDE)-based point clustering algorithm from the WCD traces. The pedestrian network generation results using two actual crowdsourced datasets show that the proposed method has good performance in both geometrical correctness and topological correctness.  相似文献   

Jason-2高度计电离层GIM误差分析及修正研究     

黄霞凤  苗洪利  苗翔鹰  薛文文 《海洋学报》2019,41(7):143-148

基于Jason-2高度计2015年地球物理数据集(GDR)38个周期太平洋海域的全球电离层图(GIM)电离层校正值和双频校正值的数据，分不同季度和不同纬度区域比较二者的差异，结果表明:GIM值与双频校正值之间存在明显的差异，GIM校正值普遍高于双频校正值，说明GIM高估了电离层路径延迟，GIM校正值与双频校正值的差异与季节和纬度区间有关。用梯度下降法得到GIM值的修正方程，将修正方程应用于2016年Jason-2的全年数据，修正后的GIM值与双频校正值十分接近，在各年份中均具有良好的适用性。在单频高度计不能使用电离层双频校正算法的情况下，可以利用不同季度和不同纬度区域的修正方程对同等高度的高度计GIM值进行修正以达到双频校正值的精度水平。  相似文献   

山西省大同市新荣区石墨矿岩石矿物地球化学特征与成因     

梁钰琦  赵永  吴光存  张越  夏庆霖 《地球学报》2020,41(6):827-834

山西省大同市新荣区石墨矿带总体呈北东—南西向展布, 长约22 km, 赋矿层位为中下太古界右所堡组, 岩性为含石墨黑云斜长片麻岩。目前该矿带上已有7个勘查区, 累计查明晶质石墨矿物资源量约 5000万吨, 但对其矿床成因类型研究相对较少。本文收集整理和分析总结了区域内地质资料及化验分析结果, 采用变质岩原岩恢复的四种方法确定该矿带的成因: 从石墨矿带的矿体产状和岩石组合、岩相学和矿物学特征定性判断该矿带矿床为沉积岩区域深变质成矿类型; 矿体样品地球化学微量元素比值(Sr:Ba等)符合副变质岩特征; 稀土元素配分曲线及其研究表明矿体及围岩具有沉积岩变质特征; 以TiO2-F图解、[(al+fm)–(c+alk)]/Si图解以及(al-alk):c图解展示的岩石化学特征半定量地确认新荣区石墨矿带矿床为以黏土岩为主的区域变质成矿。新荣区石墨矿带成因类型的确定填补了该区域矿床成因类型研究的空白, 为下一步地质找矿及建模提供了重要依据; 三种图解相结合, 逐步缩小原岩范围, 锁定原岩类型, 为变质岩原岩恢复及矿床成因研究提供了新的思路和判别方法。  相似文献   

Peroxymonosulfate Improves the Activity and Stability of Manganese Oxide for Oxidation of Arsenite to Arsenate     

Yong Liu  Fen Zhang  Jingtao Hou  William Hartley 《洁净——土壤、空气、水》2020,48(2)

Manganese oxide has been widely investigated for oxidation of arsenite (As(III)) to arsenate (As(V)) due to its high redox potential; however, it becomes extremely unstable after reuse. Here, As(III) oxidation activity and stability of manganese oxide in the presence of peroxymonosulfate (PMS) is investigated. Batch experimental results reveal that manganese oxide/PMS exhibits high catalytic activity for As(III) oxidation compared to manganese oxide or PMS alone. Addition of PMS to manganese oxide not only reveals long‐term stability for As(III) oxidation, but also shows high As(III) oxidation activity in the presence of coexisting ions such as As(V) and phosphate. Quenching tests reveal that As(III) oxidation in the manganese oxide/PMS system is attributed to activation of PMS by manganese oxide at different oxidation states (Mn(III) and Mn(IV)), and the generation of sulfate radicals that are responsible for As(III) oxidation.  相似文献   

长河坝—黄金坪水库区域地震台网监测能力分析     

杜瑶  吴彤  冯薪  丁勇  赵昱  郑昭  王宇玺  王余伟 《地震地磁观测与研究》2020,41(5):25-32

位于四川省甘孜藏族自治州康定市内大渡河干流的长河坝-黄金坪水电站，为大渡河流域开发中，以长河坝、大岗山、瀑布沟等形成主要梯级格局开发方案中，"三库22级"水电站中的第10和11级电站，其地震监测台网也采用梯级设计方式，长河坝-黄金坪上下游水库地震监测台网统一设计、建设及监测，共享同一地震监测能力。通过对监测设备的技术指标、台基地噪声水平和震级-频度对数关系的分析，结果表明，长河坝-黄金坪水库区域地震固定台站建成后，地震监测能力达到并优于设计的理论监测能力，地震监测震级达到下限为M_L 0.5的设计要求。  相似文献