Temporal variation of soil erosion resistance on sloping farmland during the growth stages of maize (Zea mays L.)

Maize growth has great effects on soil properties and thus likely induces the changes in soil erosion resistance on sloping farmland. However, temporal variation of soil erosion resistance during the growth stages of maize is still unclear in the mountainous yellow soil area where maize is the dominant crop. In this study, four maize plots (MP) and four bare land plots (CK) were conducted to investigate soil erosion resistance, and multiple indicators of soil erosion resistance were measured including the total soil anti-scourability (TAS), mean weight diameter (MWD), soil erodibility K factor and soil shear strength (SH). A comprehensive soil erosion resistance index (CSERI) was employed to quantify the temporal variation of soil erosion resistance during the growth stages of maize (seedling stage, SS; jointing stage, JS; tasselling stage, TS; maturing stage, MS). The results showed that TAS, MWD, SH increased significantly with maize growth and SH decreased when at MS. But K factor decreased significantly over time. CSERI increased significantly during the growth stages of maize and the CSERI of JS, TS, MS increased on average by 74.72, 180.68 and 234.57% than that of SS. Compared to CK, CSERI of MP increased by 49.90, 66.82, 55.60 and 38.61% during the growth stages of maize. The temporal variation of soil erosion resistance was closely related to the changes in maize cover, maize roots and soil organic carbon. The findings demonstrated that it is necessary to consider the temporal variation of soil erosion resistance in the mountainous yellow soil area.     

重要性权值的驾车导航POI表达规则

在导航电子地图中,针对驾车任务的POI自适应表达是提高导航电子地图信息传输效率的关键。针对这一问题,提出了基于重要性权值的驾车导航POI表达规则。首先,分析了POI重要性权值的影响因素;其次,从影响因素出发,研究了基于权值的POI规则表达的各规则项;最后,设计了POI自适应表达规则库,并在嵌入了数据处理规则库的绘图软件上进行了技术实现。试验结果表明,利用基于权值的POI表达规则进行地图表达,可以提高地图内容的层次性与清晰性,优化驾车导航服务。     

新元古代扬子—华夏陆块拼合带：来自华南重磁异常的启示

扬子和华夏两大陆块是构成华南大陆的最基本单元, 但它们的拼合带位置（尤其是西延位置）是人们长期争论的焦点。本文以国家专项“深部探测技术与实验研究”探测得到的深反射地震剖面以及华南大陆的地质资料为约束, 对重、 磁异常作地壳构造融合解译, 追踪扬子—华夏陆块拼合带。由于华南大陆广泛发育具有剩磁多期、 多类的火山—侵入岩, 本文将磁异常换算为受剩磁影响小的解析信号作构造解译, 减小剩磁造成的地质解释偏差。研究认为, 扬子与华夏两陆块的拼合带东界为鹰潭—萍乡—衡阳—贺州—北海一线, 而西界为宜昌—张家界—铜仁—都匀—百色一线, 鹰潭以东和以北的拼合带位置因为受大规模岩浆岩的干扰而不清。     

利用双线偏振雷达分析人工防雹作业效果

以北京市平谷区2011年6月11日防雹作业为例,利用双线偏振雷达资料,选取与作业区条件十分接近的云块为对比区,根据回波移动方向和速度,跟踪分析在不同高度上防雹作业前后云体宏观结构特征和粒子相态等微物理变化过程。作业后云体所呈现特征为:1作业区的云顶高度、强回波中心高度迅速下降,对比区变化不明显;2作业区水平反射率Zh减小,差分反射率Zdr、零相关系数ρhv增大,单位差分传播相移Kdp小范围内波动,对比区Zh、Zdr、Kdp变化不明显;ρhv增大;3作业区对流减弱,高层较大冰雹粒子、大雨滴下沉明显,最终以霰粒子为主;而对比区域则对流仍然旺盛,冰雹粒子有增多趋势。以上特征表明防雹作业可有效抑制冰雹胚胎成长为冰雹的过程,通过偏振雷达观测参量可对防雹作业效果进行较好的验证。     

M-Quadtree索引:一种基于改进四叉树编码方法的云存储环境下空间索引方法

为了解决基于"键-值"模型的云存储环境仅支持简单的关键字查询,不支持多维空间查询的问题,提出了一种新的分布式空间索引方法——M-Quadtree索引。在索引构建过程中,设计了一种基于改进四叉树的空间数据划分方法,该方法规定了叶节点区域的最小数据量,通过四叉树叶节点的再合并,解决了划分后各子区域间存储量不平衡的问题,并且满足了MapReduce并行化要求。给出了MapReduce框架下M-Quadtree索引的快速构建、查询与更新算法,并在搭建的Hadoop平台进行了关键参数对索引效率的影响以及不同规模数据下索引的创建、查询和更新试验。与现有分布式空间索引的对比试验及分析结果表明,M-Quadtree索引在数据存储量负载均衡、算法并行化和空间查询效率等方面表现得更好。     

西准噶尔玛依勒地区枕状玄武岩年代学、地球化学及岩石成因

通过对造山带内洋岛玄武岩的时代及地球化学性质研究,不仅可以进行古海山/大洋高原的识别,而且还可以进行古洋盆演化及古构造格局恢复。笔者等最新在西准噶尔玛依勒山北侧识别出一套枕状玄武岩,其与火山碎屑岩、硅质岩共生。枕状玄武岩斜长石微晶普遍发育中空骸晶结构,是在水下熔岩急剧萃冷条件下迅速结晶的产物。通过LA-ICP-MS锆石U-Pb测年,获得枕状玄武岩206Pb/238U加权平均年龄为437.2±2.2Ma,该年龄的获得填补了志留纪碱性玄武岩的空白。岩石地球化学分析结果显示,玛依勒枕状玄武岩为碱性玄武岩系列,岩石具有中等Si O2(44.89%~47.81%),高Ti O2(3.28%~4.12%)及P2O5(0.50%~0.70%),低Mg O(3.49%~6.79%),轻、重稀土元素分异较为明显((La/Yb)N=5.5~7.3),无明显Eu异常(Eu/Eu*=0.96~1.06),相对富集Rb、Th、U,亏损Ba、K、Sr,没有明显Nb、Ta负异常,这些地球化学特征与洋岛玄武岩(OIB)极其相似。微量元素含量及反映源区性质的比值表明,枕状玄武岩来源于富集地幔源区,主要组成为尖晶石和石榴石二辉橄榄岩,并发生了5%±的部分熔融,其形成于大洋板内与地幔柱有关的海山/大洋岛屿环境。结合前人研究,认为西准噶尔乃至古亚洲洋在中古生代洋内俯冲的同时,大洋板内可能存在地幔柱活动。     

Research on Formation Mechanisms of Hot Dry Rock Resources in China

As an important geothermal resource, hot dry rock(HDR) reserves have been studied in many countries. HDR resources in China have huge capacity and have become one of the most important resources for the potential replacement of fossil fuels. However, HDR resources are difficult to develop and utilise. Technologies for use with HDR, such as high–temperature drilling, reservoir characterisation, reservoir fracturing, microseismic monitoring and high–temperature power stations, originate from the field of oil and drilling. Addressing how to take advantage of these developed technologies is a key factor in the development of HDR reserves. Based on the thermal crustal structure in China, HDR resources can be divided into four types: high radioactive heat production, sedimentary basin, modern volcano and the inner–plate active tectonic belt. The prospective regions of HDR resources are located in South Tibet, West Yunnan, the southeast coast of China, Bohai Rim, Songliao Basin and Guanzhong Basin. The related essential technologies are relatively mature, and the prospect of HDR power generation is promising. Therefore, analysing the formation mechanisms of HDR resources and promoting the transformation of technological achievements, large–scale development and the utilisation of HDR resources can be achieved in China.     

阿根廷米纳毕戈塔地区水系沉积物采样粒度试验研究

中国地质调查局与阿根廷地质矿产调查局合作在阿根廷西北部米纳毕戈塔地区进行1︰25万水系沉积物测量,该区属于干旱-半干旱高寒山区,为突出找矿效果,消除或减少风积物干扰,需要确定适合于该区的水系沉积物采样粒度。为此,在该区选择一个有已知矿床的1︰5万图幅进行采样粒度试验,分别选择10~60目、-60目、60~80目、-80目4个粒度级进行粒度试验;根据我国区域地球化学勘查规范,每个粒度分析39种元素。结果表明,大部分元素在4种粒度水系沉积物中的分布形态基本一致,都能够较好地反映出区内已知矿床,说明采用的采样方法可以有效地避免风成砂干扰;金、银、铜、锡等成矿元素在4种粒度中的分布略有差异,10~60目的金、铜和锡异常对已知矿体的反应更清晰准确。因此,本区水系沉积物地球化学测量的最佳采样粒度是10~60目。根据本次试验结果,中-阿地调局在本区联合开展1︰25万水系沉积物地球化学测量时采用了10~60目水系沉积物作为采样介质,取得了很好的效果。这是本区第一次进行水系沉积粒度试验,对本区将来的地球化学调查和研究具有指导意义。