Urban green space planning based on computational fluid dynamics model and landscape ecology principle: A case study of Liaoyang City,Northeast China

As a result of environmental degradation,urban green space has become a key issue for urban sustainable development.This paper takes Liaoyang City in Northeast China as an example to develop green space planning using the computational fluid dynamics (CFD) model,landscape ecological principles and Geographical Information System (GIS).Based on the influencing factors of topography,building density and orientation,Shou Mountain,Longding Mountain and the Taizi River were selected as the urban ventilation path...     

浙江省湿地资源调查量测研究与实施

湿地资源类型、分布及面积是重要的地理国情信息。本文介绍如何利用测绘地理信息技术,基于1∶10 000基础地理信息数据,结合多种专业资料,完成对浙江全省湿地资源的量测与统计,并总结相关经验,指出开展该项工作的关键技术环节及解决方案。     

回归分析与人工神经网络在建筑物沉降预计中的应用

随着高层建筑物的逐渐增多,对其做好沉降预警工作具有重要意义。本文中分别采用回归分析法和人工神经网络建立沉降预计模型,对工程实例进行沉降预计,通过图表表现出的预测值与真实值的差异,说明两种方法的优缺点以及两者的实际应用价值,最终两种方法均取得了令人满意的预计结果。     

Geological cycling of potassium and the K isotopic response: insights from loess and shales

Shales are a major sink for K into seawater delivered from continental weathering, and are potential recorders of K cycling. High precision K isotope analyses reveal a > 0.6 ‰ variation in δ⁴¹K values (⁴¹K/³⁹K relative to NIST SRM 3141a) from a set of well characterized post-Archean Australian shale (PAAS) samples. By contrast, loess samples have relatively homogenous δ⁴¹K values (− 0.5 ± 0.1 ‰), which may represent the average K composition of upper continental crust. Most of the shales analyzed in this study have experienced K enrichment relative to average continental crust, and the majority of them define a trend of decreasing δ⁴¹K value (from − 0.5 to − 0.7 ‰) with increasing K content and K/Na ratio, indicating cation exchange in clays minerals is accompanied by K isotope fractionation. Several shale samples do not follow the trend and have elevated δ⁴¹K values up to − 0.1 ‰, and these samples are characterized by variable Fe isotope compositions, which reflect post-depositional processes. The K isotope variability observed in shales, in combination with recent findings about K isotope fractionation during continental weathering, indicates that K isotopes fractionate during cycling of K between different reservoirs, and K isotopes in sediments may be used to trace geological cycling of K.

     

黔东北地区南华系两界河组CIA指数特征及意义

化学蚀变指数(CIA)是判断源岩风化程度的化学指标。通过分析黔东北地区苗哨溪剖面两界河组的CIA特征,为讨论其古气候特征提供地球化学方面的依据。结果表明,两界河组CIA值介于55. 48～89. 33之间,均值为72. 49,除极个别数值为55. 48、89. 33之外,其它数值皆介于65～75之间,指示两界河组具有温暖湿润的古气候特征。通过综合分析两界河组岩石组合、沉积构造及古气候特征,认为两界河组为间冰期沉积。在此基础上,结合最新同位素年代学数据,认为其可与富禄组中上部进行对比。     

定向钻铺管回拖力计算模型

在定向钻穿越铺管的过程中,管道在孔内的受力情况非常复杂,但是回拖力计算又是机具选择的重要参考依据,所以管道受力分析及回拖力计算就显得非常重要。通过分析管道在弯曲段和稳定段的受力情况,分别建立管道弯曲段和稳定段的受力模型,最终总结出计算管道回拖力的方法。经实例计算检验,这种计算方法更加接近实际。      

Analysis of trace elements (heavy metal based) in the surface soils of a desert–loess transitional zone in the south of the Tengger Desert

It is very important to strengthen the research about the heavy metal pollution of soil in vulnerable ecological regions of the south-central arid area of Northwest China for regulating and guiding local industrial and municipal activities and for protecting the environment. In this study, 48 surface soil samples were collected in the desert–loess transitional zone in the south of the Tengger Desert. The distributions of elements (heavy metal based) and the differences between urban and natural soils were analyzed. We observed that As, Pb, Cu, Zn and S were clearly enriched in the Baiyin area, and Ni and Cr were mainly enriched in the Zhongwei area. V, Mn, Ti, Bi, Co and W were enriched in the southeast margin of the Tengger Desert, where there is relatively little human activity. Over the entire study area, Ce, La and Nd were widely distributed across regions whether with strong or weak human activity. Based on the distributions of elements, we suggest that in the desert–loess transitional zone in the south of the Tengger Desert, the distribution and abundances of element As, Pb, Cu, Zn, S, Ni and Cr are strongly related to the human activities in the area, but the elements V, Mn, Ti, Bi, Co, W, Ce, La and Nd are derived mainly from natural sources.     

基于Delaunay三角网的大规模CORS基准站

连续运行参考系统(CORS)的核心技术--GPS网络实时动态定位(RTK,技术已经成为GPS高精度定位中一种重要技术,其定位精度与站间距离密切相关.在构建了站间距离和网络分布适中的Delaunay三角网后,探讨了两个相邻CORS基准站网络的联合组网、基准站点删除与插入等网络局部更新以及参考站最优选择问题,提出了相应的优化算法,实验证明该算法高效快捷、简便可靠.