利用晕渲图进行数字高程模型位置精度检查方法的探讨   总被引：1，自引：0，他引：1  

李若 《四川测绘》2010,33(1):11-12

本文介绍了DEM位置精度检测的方法，针对DEM内插生成等高线与采集等高线进行套合检查的情况，论述了晕渲图与内插等高线的基本一致，说明了晕渲图的制作与等高线套合检查的关键技术指标，详细分析了套合检查过程中遇到的具体情况，对于DEM精度控制有很好地指导作用。  相似文献   

频谱偏移法在2020年6月26日于田M_S 6.4地震前的跟踪分析     

孙玺皓  李霞  苏维刚  张朋涛  马亮 《地震地磁观测与研究》2021,42(2):176-177

  相似文献   

人参败毒散加减治疗脾肺气虚、寒湿郁肺型新型冠状病毒感染（或肺炎）28例          下载免费PDF全文

吴添沐 《应用海洋学学报》2022,38(10):4

目的：观察人参败毒散加减治疗脾肺气虚、寒湿郁肺型新型冠状病毒感染（或肺炎）的临床疗效。方法：选择脾肺气虚、寒湿郁肺型新型冠状病毒感染（或肺炎）患者28 例,采用西药联合人参败毒散加减治疗。观察患者平均连续2次呼吸道标本核酸检测阴性的时间、中医证候积分和复阳情况。结果：平均连续2次核酸转阴时间为（10.22±8.84）d;治疗后患者胸闷气短、咳嗽咳痰、纳差、便溏、神疲乏力症状积分均较治疗前降低,差异均有统计学意义(P<0.05);出院后14 d有1 例患者在隔离点出现复阳。结论：人参败毒散加减治疗脾肺气虚、寒湿郁肺型新型冠状病毒感染（或肺炎）疗效颇佳,且可对反复复阳患者起到稳定转阴的作用,值得临床推广运用。  相似文献   

洞穴石笋沉积特征研究--以贵州荔波董歌洞4号石笋为例   总被引：8，自引：1，他引：7  

林玉石  袁道先  张美良  覃嘉铭  程海  王兆荣  冉景丞 《地球学报》2004,25(4):459-466

在综合研究南方20多个大型石笋纵剖面的基础上,以董歌洞4号石笋为代表,论述石笋沉积特征与气候演化的对应性.4号石笋从距今147.838±2.6 ka开始沉积以来,形成了53个沉积纹(壳)层组,组成24个亚旋回,构成9个旋回,呈现韵律式旋回性沉积特征.石笋纹(壳)层组分、结构、叠复构造呈多级次旋回性很突出,其中沉积间断具普遍性、沉积速率具多变性,间断和速率变化级次亦明显.以系统测试和测年引证沉积特征的同时揭示:①～⑨旋回间沉积间断时间累积达75.804 ka,占石笋形成时间的51.21%,①～⑨旋回实际沉积时间仅72.222 ka,占形成时间的48.79%;④旋回之前,沉积速率很小,最小仅0.36 mm/100a,比最大速率小22～24倍,自⑤旋回起,沉积速率很大,最大达39.03 mm/100a,是最小速率的3.8倍.石笋沉积特征与气候环境演化的成生关系表明,石笋沉积多旋回性的纹(壳)层组、亚旋回、旋回与气候演化的气候期、阶段和旋回彼此对应,石笋沉积的多级次旋回及其变化就是气候演化的级次及旋回性转(跃)变时间,彼此同时显示.论证了石笋沉积的多旋回性与气候演化的不稳定性,及其彼此协调的宏观、微观综合表现特征.  相似文献   

Status,trends and challenges in the sustainability of small-scale fisheries in the Philippines: Insights from FISHDA (Fishing Industries' Support in Handling Decisions Application) model     

《Marine Policy》2014

Managing small-scale fisheries in a developing country like the Philippines is very challenging because of high pressures from expanding fishing population, poverty and lack of alternative options. Thus, resource-focused fisheries management initiatives such as marine protected area (MPA) establishment will likely result in further marginalization of the poor fishers which could pose more serious problems in coastal communities. In this study, the status of small-scale fisheries in 44 coastal towns in the Philippines was assessed using FISHDA (Fishing Industries' Support in Handling Decisions Application), a simple decision support tool which requires minimal or easily-generated data. Results showed that 68% (30 out of 44) of the studied towns have unsustainable fisheries unless 58% of their fishing grounds are protected from all fishing activities. Alternatively, 53% of the active fishers in towns with unsustainable fisheries must totally stop fishing to avert fishery collapse. Alarming as it may sound, this is still an underestimate as catches incurred by the highly efficient and destructive illegal fishing activities such as blast, poison and large-scale fishing, which are reported to be still rampant in many coastal areas in the Philippines, were not accounted for in this study. This study demonstrated that MPAs alone may not be enough to avert fishery collapse even if MPA size is increased from the current 3% to 15% of the municipal waters, i.e. up to 15 km from the shore, as required by the Philippine law. Various challenges confronting the fishery and important recommendations to address them are further discussed.  相似文献   

水下滑翔器整体外形设计及水动力性能分析   总被引：1，自引：0，他引：1       下载免费PDF全文

孟凡豪  严天宏  何波  徐新胜 《海洋工程》2014,32(2):61-71

对水下滑翔器的整体外形设计与水动力性能进行研究。在Slocum等几种典型水下滑翔器样机的基础上,对滑翔器的主体和附体进行一体化设计,得到阻力最小的新型水下滑翔器构型设计。利用CFD方法对水下滑翔器进行模拟仿真,通过分析对比五种主体构型,得到了比较合理的主体线型,然后用正交设计方法和曲线拟合法对附体进行了优选工作,最后得到了性能更优的整体载体外形。模拟仿真实验表明,滑翔器在8°左右攻角航行时,具有最大的升阻比;和Slocum等经典样机相比,新的载体具有更好的水动力性能。通过上述研究工作,也可以缩短水下滑翔器研制周期,降低设计成本,并为水下滑翔器的更优设计提供了有力的技术指导和参考。  相似文献   

内蒙古中部地区中-新元古代黑色岩系中的金矿床及找矿远景          下载免费PDF全文

荣丹文  张劼  荣晓伟  李建伏  高伯兴 《山东国土资源》2014,30(3):51-55

内蒙古中部地区中—新元古代黑色岩系发育,形成于渣尔泰-白云鄂博裂陷槽内,命名为渣尔泰群和白云鄂博群。目前,仅在白云鄂博群的黑色岩系中发现并勘查了一批原生金矿。矿石主要类型为细脉型和蚀变变质岩型。金矿受层位和构造破碎带控制,金平均品位低,可形成大型或超大型矿床。因此,内蒙古中部中—新元古代黑色岩系中金矿资源潜力大,找矿远景好。  相似文献   

Spatial structure analysis of a reptile community with airborne LiDAR data     

N. Sillero  Luís Gonçalves-Seco 《International journal of geographical information science》2014,28(8):1709-1722

The analysis of the spatial structure of animal communities requires spatial data to determine the distribution of individuals and their limiting factors. New technologies like very precise GPS as well as satellite imagery and aerial photographs of very high spatial resolution are now available. Data from airborne LiDAR (Light Detection and Ranging) sensors can provide digital models of ground and vegetation surfaces with pixel sizes of less than 1 m. We present the first study in terrestrial herpetology using LiDAR data. We aim to identify the spatial patterns of a community of four species of lizards (Lacerta schreiberi, Timon lepidus, Podarcis bocagei, and P. hispanica), and to determine how the habitat is influencing the distribution of the species spatially. The study area is located in Northern Portugal. The position of each lizard was recorded during 16 surveys of 1 h with a very precise GPS (error < 1 m). LiDAR data provided digital models of surface, terrain, and normalised height. From these data, we derived slope, ruggedness, orientation, and hill-shading variables. We applied spatial statistics to determine the spatial structure of the community. We computed Maxent ecological niche models to determine the importance of environmental variables. The community and its species presented a clustered distribution. We identified 14 clusters, composed of 1–3 species. Species records showed two distribution patterns, with clusters associated with steep and flat areas. Cluster outliers had the same patterns. Juveniles and subadults were associated with areas of low quality, while sexes used space in similar ways. Maxent models identified suitable habitats across the study area for two species and in the flat areas for the other two species. LiDAR allowed us to understand the local distributions of a lizard community. Remotely sensed data and LiDAR are giving new insights into the study of species ecology. Images of higher spatial resolutions are necessary to map important factors such as refuges.  相似文献   

Spatial analysis of geometric design consistency and road sight distance     

Maria Castro  César De Santos-Berbel 《International journal of geographical information science》2013,27(12):2061-2074

Because of the high number of crashes occurring on highways, it is necessary to intensify the search for new tools that help in understanding their causes. This research explores the use of a geographic information system (GIS) for an integrated analysis, taking into account two accident-related factors: design consistency (DC) (based on vehicle speed) and available sight distance (ASD) (based on visibility). Both factors require specific GIS software add-ins, which are explained. Digital terrain models (DTMs), vehicle paths, road centerlines, a speed prediction model, and crash data are integrated in the GIS. The usefulness of this approach has been assessed through a study of more than 500 crashes. From a regularly spaced grid, the terrain (bare ground) has been modeled through a triangulated irregular network (TIN). The length of the roads analyzed is greater than 100 km. Results have shown that DC and ASD could be related to crashes in approximately 4% of cases. In order to illustrate the potential of GIS, two crashes are fully analyzed: a car rollover after running off road on the right side and a rear-end collision of two moving vehicles. Although this procedure uses two software add-ins that are available only for ArcGIS, the study gives a practical demonstration of the suitability of GIS for conducting integrated studies of road safety.  相似文献   

Cartography: visualization of spatial data (3rd ed.), by Menno-Jan Kraak and Ferjan Ormeling     

Claire Jarvis 《International journal of geographical information science》2013,27(7):1214-1215

Conventionally, a raster operation that needs to scan the entire image employs only one scanning order (i.e., single scanning order (SSO)), and the scan usually runs from upper left to lower right and row by row. We explore the idea of alternately applying multiple scanning orders (MSO) to raster operations that are based on the local direction, using the flow accumulation (FA) calculation as an example. We constructed several FA methods based on MSO, and compared them with those widely used methods. Our comparison includes experiments over digital elevation models (DEMs) of different landforms and DEMs of different resolutions. For each DEM, we calculated both single-direction FA (SD-FA) and multi-direction FA (MD-FA). In the theoretical aspect, we deducted the time complexity of an MSO sequential algorithm (MSOsq) for FA based on empirical equations in hydrology. Findings from the experiments include the following: (1) an MSO-based method is generally superior to its counterpart SSO-based method. (2) The advantage of MSO is more significant in the SD-FA calculation than in the MD-FA calculation. (3) For SD-FA, the best method among the compared methods is the one that combines the MSOsq and the depth-first algorithm. This method surpasses the commonly recommended dependency graph algorithm, in both speed and memory use. (4) The differences between the compared methods are not sensitive to specific landforms. (5) For SD-FA, the advantage of MSO-based methods is more obvious in a higher DEM resolution, but this does not apply to MD-FA.  相似文献