基于数字剖面的河流阶地与新构造运动研究 ——以内蒙古西拉木伦河河流阶地为例

野外调查发现在内蒙古东部西拉木伦河流域存在12级阶地序列。利用数字剖面野外系统对该河流阶地剖面的记录完成全程数字化采集,并进行数字剖面桌面系统厚度自动计算和剖面图、柱状图自动生成,发现该阶地序列中T7、T8、T9保存完好,而时代最为古老的T12 根据基座玄武岩形成于上新世—早更新世的年龄,其形成时代应为上新世—早更新世。通过计算新构造运动抬升速率,将其形成、演化过程划分为6个阶段。数据表明,自中新世以来,该地区新构造运动存在一定的周期性,在总体上新构造运动的强度逐渐趋于缓和。     

大兴安岭新林镇岩体的同位素特征及其地质意义

新林镇岩体位于大兴安岭北部,主要由花岗闪长岩、石英二长岩、二长花岗岩、碱长花岗岩组成,局部见到细粒辉长岩和闪长岩包体。岩石地球化学和岩石学特征表明,该杂岩体属于高钾钙碱性I型花岗岩。两个花岗闪长岩的锆石LA-ICP-MS U-Pb定年结果分别为(132±3)Ma和(131±3)Ma,属于早白垩世岩浆活动的产物。样品的Sr-Nd同位素组成比较均一,而Hf同位素特征变化较大,其εHf(t)变化介于1.32~8.32之间,Hf模式年龄与Nd模式年龄一致,表明花岗质岩浆主要起源于元古代增生的地壳物质,在岩石形成过程中有地幔组分的贡献。岩体的同位素特征将额尔古纳地块地壳增生时间限定在新元古代,而兴安地块地壳增生发生在新元古代—显生宙,暗示它们具有不同的地壳演化过程。     

南华北盆地阜阳区块古生代地震层序划分及地震相研究

阜阳区块位于南华北盆地的周口坳陷东部,面积约11000km^2,占坳陷面积的三分之一;该盆地按照中、新生界构造特征将其划分为六凹四凸;随着油气勘探的深入和地质研究的深化,笔者利用该区地震剖面进行地震层序研究与划分,并进一步进行了沉积相的研究,为该区古生代的油气勘探提供科学依据。     

Wind tunnel experiments of air flow patterns over nabkhas modeled after those from the Hotan River basin,Xinjiang,China(Ⅱ):vegetated

This paper examines the results of wind tunnel experiments on models of nabkha, based on those studied in the Hotan River basin. Semi-spherical and conical models of nabkhas were constructed at a ratio of 40:1 in light of the on-site observation. Artificial vegetation of simulated Tamarix spp. was put on top of each model. Parameters of the shape, including height, width, and diameter of vegetated semi-spherical and conical nabkha, were measured in the Hotan River basin. Wind tunnel experiments on the semi-spherical and conical nabkha used clean air devoid of additional sediments at five different wind speeds (6–14 m/s) to study the influence of vegetation on airflow patterns. Results of the experiments indicate that vegetation at the top of the nabkhas enhances the surface roughness of the sand mounds, retards airflow over the sand mounds, reduces airflow energy, eliminates erosional pits occurring on the top surface of non-vegetated sand mounds and enhances the range of influence of the vortex that forms on the leeward slope. Vegetation changes the airflow pattern upwind and downwind of the sand mound and reduces the transport of sand away from the nabkha. This entrapment of sediment by the vegetation plays an important role in sustaining the nabkha landscape of the study area. The existence of vegetation makes fine materials in wind-sand flow to possibly deposit, and promotes nabkha formation. The imitative flow patterns of different morphological nabkhas have also been verified by on-site observation in the river basin. __________ Translated from Journal of Desert Research, 2007, 27(1): 15–19 [译自: 中国沙漠]     

从地缘关系视角解析“一带一路”的行动路径

“一带一路”倡议是人类历史上最伟大的全球治理工程,开辟了政治地理学研究的新纪元,为地缘关系研究提供了大舞台。地理学是从时间、空间和自然—社会系统三个维度理解陆地表层过程的科学,对地缘关系研究具有独特的功能和作用。因此,从地理学视角研究地缘关系具有其他学科无法比拟的优势。“一带一路”是当前最具挑战的科学和政策命题,从地缘关系视角研究“一带一路”,需要加强四个方面的结合：① 在科学思维上,需要还原论与系统论思维相结合;② 在科学数据建设上,需要社会人文与自然环境数据相结合;③ 在科学问题选择上,需要社会过程、人文过程、政治过程和自然过程相结合;④ 在研究方法上,需要经验方法、实证方法、系统方法与大数据研究方法相结合。中国地理学者应兼顾政治地理学科建设、地缘关系的学科交叉研究和“一带一路”全球实践开展研究。     

不同水汽环境条件下云凝结核浓度对热带气旋发展影响的数值研究

利用WRF模式模拟在清洁海洋大气和污染大气环境下,气溶胶的云凝结核浓度(Cloud Condensation Nuclei, CCN)对热带气旋的强度变化影响。在污染环境下,云凝结核浓度增多,台风区域云水混合物浓度增大,眼墙附近上升运动减小,而台风外围螺旋雨带对流发展,从而抑制低层入流,台风强度减弱,外围尺度增大。在不同环境场水汽条件下,通过热、动力结构和云微物理量的对比分析,结果表明:环境场水汽条件对台风的发展起到至关重要的作用。当环境场水汽条件较干时,CCN浓度对台风发展影响作用不明显,台风发展缓慢。而在充足水汽条件下,CCN浓度对热带气旋发展有明显的影响。本文结果表明,在考虑污染情形下台风变化,需要综合考虑环境场水汽条件。     

Improved Weather Radar Echo Extrapolation Through Wind Speed Data Fusion Using a New Spatiotemporal Neural Network Model

Weather radar echo extrapolation plays a crucial role in weather forecasting. However, traditional weather radar echo extrapolation methods are not very accurate and do not make full use of historical data. Deep learning algorithms based on Recurrent Neural Networks also have the problem of accumulating errors. Moreover, it is difficult to obtain higher accuracy by relying on a single historical radar echo observation. Therefore, in this study, we constructed the Fusion GRU module, which leverages a cascade structure to effectively combine radar echo data and mean wind data. We also designed the Top Connection so that the model can capture the global spatial relationship to construct constraints on the predictions. Based on the Jiangsu Province dataset, we compared some models. The results show that our proposed model, Cascade Fusion Spatiotemporal Network (CFSN), improved the critical success index (CSI) by 10.7% over the baseline at the threshold of 30 dBZ. Ablation experiments further validated the effectiveness of our model. Similarly, the CSI of the complete CFSN was 0.004 higher than the suboptimal solution without the cross-attention module at the threshold of 30 dBZ.     

基于临界条件的中国航空气象危险要素区域分布与风险区划

根据航空飞行安全的气象保障规范和临界条件,探讨了我国区域内影响飞机起降的气象要素的区域特征;在气象要素影响分析的基础上,建立飞机起降安全的气象要素评价指标;采用层次分析法(AHP)确定各评价指标的权重,利用模糊综合评价方法构建了飞机起降气象安全风险的评价标准和评价体系,运用区间梯形隶属度函数来计算评估单元各指标针对各风险等级的隶属度,最后根据最大隶属度原则作出风险评估与区划。分析表明,我国北方地区航空安全气象环境较南方地区好,南方出现航空飞行不利影响的恶劣气象条件的频率显著高于北方;我国航空安全气象风险由北至南逐渐递增,尤以东部沿海地区、福建和江西东北部地区、贵州东部及湖南地区的风险等级最高。     

边缘系数建筑物雷达点云数据简化方法

针对基于LiDAR点云数据进行建筑物自动重建中存在的数据冗余问题,该文设计了一种定量描述激光点位于地物边缘区几率大小的指标——边缘系数,并据此提出了基于边缘系数的建筑物LiDAR点云数据简化方法。该方法利用激光点与其邻域点的位置、数量及分布计算该点的边缘系数,通过试验分析确定边缘系数的阈值并对点云数据进行分割,最后保留建筑物边缘区域的点,实现点云数据的简化。实验表明,该方法在对点云数据进行高效压缩的同时有效保留了位于地物边缘处的点云,有助于提高海量点云数据处理能力和建筑物重建效率。