线图形简化与移位算子的协同方法

在地图综合过程中,线的图形简化和移位算子通常是分别执行的,图形简化和移位有时都会产生新的空间冲突。本文试图把这两种算子进行协同,避免在地图综合过程中进行空间冲突的多次探测,提高地图综合数据处理的效率。本文通过把线图形简化转换为线上的点移位,并构建邻近地图目标之间的移位传播路径,在考虑空间上下文关系和地图感受规则的前提下,使移位过程能考虑到线图形简化,并尽量保持有关地图目标的空间特征。最后,以道路和其周边的建筑物群为例,验证了该算法的有效性和可行性。     

顾及像面畸变的卫星视频稳像

卫星视频每帧影像外方位元素数值存在差别,相邻帧影像间的同名点在像面位置不同,且由于每帧影像均存在几何畸变,经典的帧间的投影变换模型、仿射变换模型等视频稳像的配准模型不能精确描述帧间的同名点关系。针对该问题,本文提出顾及像面畸变的卫星视频稳像算法,基于仿真的卫星视频,验证了该算法的可行性和精度。     

顾及拓扑一致性的水系三维曲线化简

鉴于常规曲线化简方法应用于水系曲线化简时难以顾及水系要素的三维特征及其拓扑关系,本文提出了一种顾及拓扑一致性的水系三维曲线化简方法。该方法首先对D-P算法进行三维扩展,实现水系中单条河流三维曲线化简,然后构建水系树结构表达其拓扑关系,最后按照水系树的层次顺序依次进行河流曲线化简和干流与支流的拓扑关系重构。试验结果表明,该方法化简精度高,既能保持水系的三维形态特征,又能保证河流交汇处的拓扑一致性。     

面向旅游规划的空间信息服务工作流构建

针对现有工作对规划支持不足的问题,该文通过集成空间信息服务、语义网络、Web服务发现与组合等技术,探索并建立了一套完整、有效,能充分提供旅游规划决策支持的空间信息服务工作流构建方法。阐述了面向旅游规划的空间信息服务工作流构建的关键技术,包括基于旅游规划本体库的空间信息服务发现方法,旅游规划语义驱动的空间信息服务组合算法,以及可靠的空间信息服务工作流过程调用机制。在此基础上开展实证研究,实现面向旅游规划的空间信息服务工作流原型系统,并对工作流构建关键方法的可行性进行了验证。     

Knowledge Transfer for Large‐Scale Urban Growth Modeling Based on Formal Concept Analysis

Cellular automata (CA) are useful for studies on urban growth and land‐use changes. Although various methods have been developed to define transition rules, modeling urban growth of large areas remains a tough challenge owing to heterogeneous geographical features. To address the problem, we present a novel method based on the combination of Formal Concept Analysis (FCA) and knowledge transfer techniques. FCA is used to solicit association rules among cities within a large area. This method can provide a theoretical basis for the knowledge transfer process. A cutting‐edge algorithm called TrAdaBoost is then integrated with the commonly‐used Logistic‐CA as the modeling framework. The proposed method is applied to the urban growth modeling of Guangdong Province, a large region with 21 cities in China, from 2005 to 2008. Compared with traditional methods, this method can achieve better results at the provincial and local levels, according to the experiments. The combination of FCA and knowledge transfer is expected to provide a useful tool for calibrating large‐scale urban CA models.     

Improvement of saponification extraction method for fatty acids separation from geological samples

The conventional saponification method could result in lower recoveries and artificial changes of long-chain fatty acids. The main reason is the error judgment of the intermediate layer suspended between the aqueous and organic layer during the liquid–liquid extraction process. This study shows that the intermediate layer consists of lots of medium- to long-chain carboxylic salts for their special physical and chemical properties. An improved saponification extraction method is also developed and the results show that the carboxylic salts distributed in the intermediate layer could be obtained completely, which greatly enhances the authenticity and accuracy of fatty acid analysis. Additionally, the possible reasons of formation of the intermediate layer are also discussed.     

南水北调中线突发水污染事件的快速预测

依据南水北调中线干渠资料,开展了正常输水情况下串联明渠内可溶污染物浓度分布规律数值模拟研究。采用数值模拟、数学归纳和统计分析方法,提出表征污染物输移扩散特征的峰值输移距离、污染带长度和峰值浓度的快速预测公式;通过示范工程验证了快速预测公式的可行性。结果表明:①串联明渠内,峰值输移距离随渠道流速减小而减小,并且污染带长度增加值随明渠内流速减小而减小,但是峰值浓度随明渠流速减小而增加;②快速预测公式计算结果与现场试验实测结果的误差均不到15%,证明了快速预测公式的合理性和可行性。这些研究结果为南水北调中线工程突发可溶性水污染事件应急预警方案的制定提供了科学依据。     

冰层取心回转钻进模拟实验台的设计与测试

极地钻探实践表明,冰盖底部冰岩交界附近地质情况异常复杂,不但可能存在暖冰、基底融水,甚至还存在厚度不等的冰岩夹层,取心钻探异常困难,而优选钻头类型、确定合理的钻进参数是保证其安全、快速钻进的重要因素。本文设计了一套能够模拟冰层回转钻进的实验台,其技术参数为：钻压、转速分别可在0～10 kN、0～300 r/min范围内调节,最大扭矩约100 N·m。该实验台能够测量钻头切削具温度、钻孔深度及钻进速度等参数,为深入研究钻头类型及结构参数、钻进参数对扭矩、钻速和切削温度的影响规律提供了手段。采用PDC复合片钻头进行了冰钻实验,结果表明,实验台能够准确调节钻压和转速,可满足实验要求。     

Late mesozoic A-Type granitoids in se China and paleo-pacific plate subduction and slab rollback北大核心CSCD

This study has reviewed the distribution and pedogenesis of late Mesozoic A-Type granitoids in SE China. These A-Type granitoids belong to four belts ( S Jiangxi-SW Fujian belt, Xiang-Gui-Yue belt, Can-Hang belt and coastal belt) due to their temporal-spatial distribution. Based on the comparative analysis of chronology, geochemistry and magmatic association, this study has discussed the formation of A-Type granitoids and the subduction and slab rollback process of paleo-Pacific plate beneath SE China.     

Variations of Hydrodynamics and Submarine Groundwater Discharge in the Yellow River Estuary Under the Influence of the Water-Sediment Regulation Scheme

The “Water-Sediment Regulation Scheme” (WSRS) is critically important to the hydrologic evaluation of the Yellow River estuary since a huge pulse of water and sediment are delivered into the sea during a short period. We used the natural geochemical tracers radium (²²³Ra, ²²⁴Ra, ²²⁶Ra) and radon (²²²Rn) isotopes as well as other hydrological parameters to investigate the mixing variations and submarine groundwater discharge (SGD) in the Yellow River estuary under the influence of the 2013 WSRS. Dramatically elevated radium and radon isotopic activities were observed during this WSRS compared with activities measured during a non-WSRS period. Radium “water ages” indicated that the offshore transport rate nearly tripled when the river discharge increased from 400 to 3400 m³/s. We calculated the SGD flux in the Yellow River estuary based on a radium mass balance model as well as radium and radon time-series models. The SGD flux was estimated at 0.02~0.20 m/day during a non-WSRS period and 0.67~1.22 m/day during the 2013 WSRS period. The results also indicate that large river discharge tends to lead more intense SGD along the river channel direction with a large amount of fresh SGD.