一种快速二维 Delaunay 三角网点定位算法

在构建二维Delaunay三角网的逐点插入法中,定位待插点所在三角形的快慢是影响整个算法构网速度的关键因素。针对目前已有算法存在的搜索路径长、搜索路径求解计算量大等问题,结合三角形重心的几何性质,对点定位算法进行改进,避免求三角形重心和相交边的过程。实验结果表明,文中算法较目前其他点定位算法能够有效地缩短搜索路径,减少点定位的计算时间,提高Delaunay三角网构网过程中点定位的效率。     

面向应用的航天遥感科学论证研究

为适应中国民用航天遥感从科学试验向业务服务模式转变,更好地探索、了解与解决应用需求与航天遥感系统对接等方面遇到的技术问题,促进航天遥感统筹协调可持续发展,中国适时于2004年成立了国家航天局航天遥感论证中心。10余年来,论证中心以航天遥感系统为研究对象,系统开展了面向应用的航天遥感科学论证概念、理论方法、技术工程与应用研究。本文是论证中心团队长期从事航天遥感科学论证研究与实践的系统总结,介绍了遥感论证初步认知、遥感论证关注问题、遥感论证理论体系与模型方法集、遥感论证能力建设及遥感论证实践等方面内容,给出了遥感论证定义并详细分析了研究范围和内容,提出了由知识维、进程维和逻辑维所组成的遥感论证作用域3维空间结构,指出社会发展加快和信息化水平提高,带动整个航天遥感数据信息链向更大规模、更短响应时间周期、更综合数据集成、更高数据质量、更加智能化方向发展,航天遥感系统将进入新的"智慧遥感"发展阶段。得益于十余年来中国民用航天快速发展,我们经历了风云三号新型载荷校飞、多角度多光谱偏振遥感器论证、环境星应用工程论证等实践,取得了多方面理论方法的突破,并应用到2030民用航天发展规划、高分辨率对地观测系统、国家自然灾害空间信息基础设施、国家民用空间基础设施中长期发展、2030中国综合地球观测系统规划等论证当中。经过不断实践,快速迭代,形成了遥感论证理论体系及相应的十大模型方法,包括遥感信息流模型、遥感信息特征模型、遥感信息应用模型、遥感信息量分析模型、遥感数据工程模型、航天遥感系统结构模型、航天遥感系统状态描述模型、航天遥感系统质量模型、航天遥感系统发展动力模型及能力体系模型。这些模型方法全面反映了航天遥感系统特征、结构、状态、发展动力、条件等,可广泛用于对航天遥感系统进行顶层设计、规划、考察、分析、评价、预测,并开展实践探索。     

低温低压条件下辉石粉末的热导率实验分析:对月球及火星表面热环境研究的指示

在真空条件下矿物粉末热导率的实验测量,可为我们研究月球及行星表面的热属性和热演化,解译热红外和微波探测数据,开展月球及行星探测载荷设计提供重要的数据参数。本研究主要采用改造后的Hot Disk TPS 2500S导热仪对辉石粉末的热导率进行测量。同时,分析了真空度、温度对辉石粉末热导率的影响。实验结果表明:1)热导率随着真空度的降低呈下降趋势,大气压力在1000Pa时,辉石粉末热传导机制发生明显改变。在低压条件下(1000Pa)热导率随真空度的变化趋于平缓;2)辉石粉末热导率随温度的升高而增大,但是增大的幅度在低压和常压条件下存在明显差异。根据实验结果,提出了低压条件下辉石粉末热导率随真空度和温度变化的关系式。本研究表明,在月球和火星表面热环境的研究中,温度和压力对热导率的影响程度是不同的。上述结果对未来开展地外样品的热导率测量提供了重要的参考。     

Study on the Temporal-Spatial Evolution of Prehistoric Settlements and Its Correlation with Subsistence Strategy and Climate History in the Western Liao River Area

Western Liao River area is one of the most important birthplaces of agricultural civilization in northern China. With recent works like relics survey, site excavation and environmental archaeology going further, the time sequence, cultural content and subsistence strategy history of this area are getting explicit. Questions like ancient exploiting history of natural resources, climate background and cultural impact of subsistence strategy have been paid great attention. Traditional environmental archaeology methods like plant and animal remains analysis are mostly utilized to conduct in-site investigation, current studies rarely adopt quantitative methods to examine the sites’ macro temporal-spatial distribution and aggregation pattern. Based on abundant digitized relic survey data, GIS methods like kernel density analysis are utilized to indicate the temporal-spatial distribution and aggregation pattern of prehistoric cultures in Western Liao River area. The latitudinal, longitudinal and altitudinal migrations of site distributional core are indicated by 3D perspective shift and elevation statistics. By referencing existing studies on subsistence strategy and paleoclimate history, results of spatial analysis are used to reveal the correlation among sites’ temporal-spatial distribution, subsistence strategy adopted and climate variation. This also contributes to our understanding and utilization of massive locational information of prehistoric sites in ancient man-land relationship study.     

Study on the Global Carbon Assimilation System Based on Multisource Remote Sensing Data

The Paris agreement signed in April, 2016 aims to balance global anthropogenic carbon emissions and terrestrial carbon sinks by the middle of the 21^st century. To fulfill this goal, it is necessary to calculate carbon fluxes of different regions reliably. The global carbon assimilation system is an effective technique for achieving this goal. The Ministry of Science and Technology of China supports the project entitled as study on the global carbon assimilation system based on multisource remote sensing data through the national key research and development programs for global change and adaptation during the thirteen-five period. This project will develop synergic inversion techniques for retrieving key parameters of biological and atmospheric cycles and for assimilating multisource remote sensing and ground based data. Then, the high resolution global carbon assimilation system coupled with an ecological model will be constructed. This system is able to assimilate jointly multisource observation data and to optimize key model parameters, photosynthesis and respiration carbon fluxes of global terrestrial ecosystems, and anthropogenic carbon emission fluxes of key regions. This system will be used to study quantitatively the spatial and temporal patterns of carbon fluxes of global terrestrial ecosystems and anthropogenic carbon emission fluxes of key regions and to identify the mechanisms driving the global terrestrial carbon sinks and sources. The outputs of this study will be helpful for the fulfillment of the key research and development programs for global change and adaptation and provide valuable data and technical support for the decision-making in China.     

An Overview of Paleo-AO/NAO Studies

The discovery of decadal variability of North Atlantic Oscillation (NAO) and the introduction of Arctic oscillation (AO) concept have initiated a series of paleo-AO/NAO related studies since the mid-to-late 1990s. The progress and new findings of paleo-AO/NAO works after that time were comprehensively reviewed. The new results from the observations and modelings at four key timescales were summarized in detail: ①the reconstructions of the AO/NAO annual index over the past millennium; ②the debate on AO/NAO’s trend since early Holocene; ③the weakening of AO/NAO’s amplitude during the Last Glacial Maximum; and ④the anomalous positive phase of AO/NAO during the Last Interglacial. In addition, the possible mechanism for different timescales of AO/NAO is also summarized. Furthermore, the distinction between AO/NAO’ was mean state and amplitude, which were not explicitly separated in previous studies, were comprehensively discussed. Considering the current uncertainties related to paleo-AO/NAO studies, we encourage the community to search for more proxies having longer-than-10,000-year length with annual resolution around AO/NAO highly correlated regions. Another, we encourage long-term transient modeling on AO/NAO can be performed in order to improve our understanding of the dynamics and interaction between AO/NAO’s high-frequency variability and the climatological background, so as to further improve AO/NAO’s predictability on global warming context.     

桂东南新地-安平地区辉长岩的年代学、地球化学特征及其地质意义

桂东南新地-安平地区的辉长岩体主要沿着岑溪-梧州深大断裂带两侧分布,与早古生代地层或震旦纪地层呈侵入接触关系,并被白垩纪地层覆盖。岩相学研究表明,其主体岩性以角闪辉长岩和紫苏角闪辉长岩为主,还有少量的含长辉石岩、辉长闪长岩和辉绿(玢)岩。LA-MC-ICP-MS锆石U-Pb定年结果显示,角闪辉长岩的形成年龄为249.1±2.8 Ma(MSWD=0.44),相当于早三叠世。地球化学特征研究表明,这些辉长岩体具有较低MgO(2.13%~3.59%)和较高Fe_2O_3T(16.42%~33.53%)、P_2O_5(0.58%~1.18%)和TiO_2(1.52%~2.31%)的特征;岩体相对富集大离子亲石元素(LILE,如Ba、Rb和U),而Nb-Ta、Zr-Hf和Ti等高场强元素相对亏损,显示出与俯冲带有关的岛弧岩浆岩相似的地球化学特征,表明其可能形成于与俯冲-消减作用有关的活动大陆边缘(大陆弧)环境。结合区域地质特征分析认为,扬子板块和华夏板块结合带(称之为钦-杭结合带)西南段有古生代洋盆的存在,该洋盆一直延续至中三叠世的印支运动才最终闭合,本区广泛发育的大陆弧型辉长岩应为该洋盆发生俯冲-消减作用的地质记录。     

松辽盆地南缘基性岩脉中捕获锆石U-Pb年龄及其对基底岩浆事件的制约

团山子基性脉岩为松辽盆地南缘晚中生代最后一期岩浆活动,在其中获得了较多的捕获锆石。为了反映松辽盆地基底岩浆活动事件,对基性脉岩中捕获锆石进行了锆石LA-ICP-MS U-Pb定年。捕获锆石阴极发光(CL)图像和Th/U比值显示具有岩浆成因的特点。从锆石定年结果得到8组年龄,反映出早侏罗世晚期(176Ma)、海西期(291Ma)、加里东期(467Ma)、新元古代(942Ma)、中元古代(1368Ma)、古元古代(1886Ma和2165Ma)、新太古代(2458Ma)岩浆事件记录。松辽盆地南部基底组成以古生代和早中生代岩浆岩为主,并可能存在西保安群前寒武纪结晶基底(942Ma),并经历了复杂的岩浆演化。中元古代、古元古代、新太古代年龄的锆石具有磨圆和反应边,可能为与华北克拉通岩浆事件形成的锆石被搬运到松辽盆地南部,并被再次捕获的结果,反映松辽盆地南部与华北大陆具有一定的联系,但不确定存在该期的结晶基底。     

Regional debris flow susceptibility analysis based on principal component analysis and self-organizing map: a case study in Southwest China

A method was developed to analyze the susceptibilities of 541 regional basins affected by debris flows at the Wudongde Dam site in southwest China. Determining susceptibility requires information on source material quantity and occurrence frequency. However, the large number of debris flows can hinder the individual field investigation in a each small basin. Factors that may trigger debris flows can be identified using remotely sensed interpretation information. Susceptibility analysis can then be conducted based on these factors. In this study, SPOT5 satellite imagery, digital elevation models (DEM), a lithology distribution map, and rainfall monitoring data were used to identify 12 debris flow trigger factors: basin relief ratio, slope gradient in the initiation zone, drainage density, downslope curvature of the main channel, vegetation coverage, main channel aspect, topographic wetness index, Melton’s ruggedness number, lithology, annual rainfall, form factor, and cross-slope curvature of the transportation zone. Principal component analysis was used to obtain the eight principal components of these factors that contribute to susceptibility results. Then, a self-organizing map method was adopted to analyze the principal components, which resulted in a debris flow susceptibility classification. Field validation of 26 debris flow basins was used to evaluate the errors of the susceptibility classification, as well as assess the causes of such errors. The study found that principle component analysis and self-organizing map methodologies are good predictors of basin susceptibility to debris flows.     

A Method for Automatically Selecting Aids to Navigation Based on their Spatial Influence Domains

To address the limitations of manually selecting aids to navigation (AtNs) on charts, a method for automatically selecting AtNs based on their spatial influence domains (SIDs) is proposed. First, the associations between the spatial attributes of an AtN are analyzed. Second, an SID of the AtN is defined, and a model of the SID is constructed based on the associations between the spatial attributes. Third, the importance of the location of the AtN is weighted based on the SID model. Fourth, an algorithm to automatically select AtNs based on the maximum coverage of the SIDS of preselected AtNs is developed. Finally, several AtNs are selected automatically using the algorithm. The experimental results demonstrate that (1) the proposed method can automatically select AtNs and the results comply with the requirements; (2) the automatic selection can eliminate the human-induced errors or the inconsistent results of manual selections from different operators; and (3) the efficiency of the proposed method is higher than that of current manual methods.