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901.
This article presents two decision support plug‐ins in free GIS software: ArcGIS Explorer Desktop. The ubiquitous WebGIS Analysis Toolkit for Extensive Resources (uWATER) focuses on providing GIS analysis functions: spatial and attribute queries in the public services tool for users with limited access to commercial GIS software. The interface of uWATER is general enough to support decision‐making in numerous management issues in natural resources, economics and agriculture. The uWATER‐Pumping Assessment (uWATER‐PA) toolkit, on the other hand, is an extended package targeting the specific environmental issue of groundwater pumping impacts. The uWATER‐PA package is an excellent alternative to evaluating complex groundwater pumping assessment issues before investing significant time, labor, and funds in monitoring and detailed scientific study. It incorporates simulation of the physics of groundwater flow and user interaction into GIS software. A graphical user interface makes both data entry and interpretation of results intuitive to non‐technical individuals. Results are presented as colored drawdown maps and can be saved in GIS format for future dissemination. The impact of drawdown on existing wells can be characterized and mapped, through the use of uWATER's spatial query capabilities and the drawdown maps generated by uWATER‐PA.  相似文献   
902.
北京中生代地层及生物群研究   总被引:2,自引:0,他引:2  
在前人研究的基础上,我们对北京地区中生代地层和生物群进行了研究。依植物化石资料与岩性对比,肯定了三叠系的存在。上统含拟丹尼蕨等晚三叠世标准化石,时代明确;中统未见化石;下统含二叠—三叠纪过渡性化石,时代归属有争议。侏罗系在北京地区分布广、厚度大、矿产丰富、沉积类型复杂。文中从动、植物化石组合,岩相与火山活动等多方面做了新的探讨。白垩系出露面积很小,属断陷盆地沉积,但化石极丰富,含标准的热河生物群及与之有演替关系的房山生物群分子;另对盆地的地质演化历程也有简单叙述。  相似文献   
903.
We study two asymptotic regimes of unstable miscible displacements in porous media, in the two limits, where a permeability-modified aspect ratio, RL=L/H(kv/kh)1/2, becomes large or small, respectively. The first limit is known as transverse (or vertical) equilibrium, the second leads to the problem of non-communicating layers (the Dykstra–Parsons problem). In either case, the problem reduces to the solution of a single integro-differential equation. Although at opposite limits of the parameter RL, the two regimes coincide in the case of equal viscosities, M=1. By comparison with high-resolution simulation we investigate the validity of these two approximations. The evolution of transverse averages, particularly under viscous fingering conditions, depends on RL. We investigate the development of a model to describe viscous fingering in weakly heterogeneous porous media under transverse equilibrium conditions, and compare with the various existing empirical models (such as the Koval, Todd–Longstaff and Fayers models).  相似文献   
904.
We present multi-color photometric observations and a one-dimensional spectrum, acquired from March 2016 to May 2017, for the short-period eclipsing binary PS Vir, by using the 2.16-m,85-cm and 60-cm telescopes at Xinglong station, which is administered by National Astronomical Observatories, Chinese Academy of Sciences. The spectral type was determined as G2V from the onedimensional spectrum. The photometric solution was reduced from BV Rc light curves. The results imply that PS Vir is a W-subtype contact binary with a mass ratio of q = 0.305(±0.008) and a fill-out factor of f = 14.4(±1.8)%. The orbital period may be undergoing a cyclic oscillation with an amplitude of A = 0.0027(±0.0001) d and a modulated period of 11.7(±0.2) yr, which may result from the light-time effect due to a third body. The lower limit on mass for the assumed component is 0.12 M⊙.Moreover, the more massive component of PS Vir may be a bit more evolved star as determined from the mass-luminosity diagram.  相似文献   
905.
We report a ~6.1 yr quasi-periodicity for the blazar S5 0716+714 using the radio light curves at 4.8, 8 and 14.5 GHz observed by the University of Michigan Radio Astronomical Observatory (UMRAO) from 1981 to 2012, by means of the Jurkevich, discrete correlation function (DCF) and power spectral analysis techniques. There are a general correlation among light curves at different frequencies and a time lag of \(170\pm 10\) days between 4.8 and 14.5 GHz light curves can be confirmed. We also estimate the orbit parameters assuming a binary black hole system, and the magnetic field strength under the jet comoving frame.  相似文献   
906.
J. Yang  Y. Jiang  B. Yang  R. Zheng  D. Yang  J. Hong  H. Li  Y. Bi 《Solar physics》2012,279(1):115-126
We will present detailed observations of the asymmetrical eruption of a large quiescent filament on 24 November 2002, which was followed by a two-ribbon flare, three coronal dimmings, endpoint brightenings, and a very fast halo-type coronal mass ejection (CME). Before the eruption, the filament lay along the main neutral line (MNL) underneath a single-arcade helmet streamer with a simple bipolar configuration. However, photospheric magnetic fields on both sides of the filament showed an asymmetrical distribution, and the filament and MNL were not located just at the center of the streamer base but were closer to the eastern leg of the streamer arcade. Therefore, instead of erupting along the streamer’s symmetrical axis, the filament showed a nonradial and asymmetrical eruption. It lifted from the eastern flank of the streamer arcade to impact the western leg directly, leading to an asymmetrical CME that expanded westward; eventually the streamer was disrupted significantly. Accordingly, the opposite-polarity coronal dimmings at both sides of the filament forming in the eruption also showed an asymmetrical area distribution. We thus assume that the streamer arcade could guide the filament at the early eruption phase but failed to restrain it later. Consistent with previous results, these observations suggest that the global background magnetic field can impose additional action on the initial eruption of the filament and CME, as well as the dimming configuration.  相似文献   
907.
就主采空区地表塌陷对铁路客运专线的危害性按照《建筑物、水体、铁路及主要井巷煤柱留设与压煤开采规程》及相关规范技术要求,对线路与主采空区之间的安全距离进行了量化评价,之后就小窑采空区场地对高等级铁路稳定性运用浅埋采空平衡拱的理论量化评价。以上两种量化评价的结果是可以保障线路与主采空区之间的安全距离,该小窑采空区顶板不受力,顶板地基稳定性差,最后文中对场地地基稳定性差的线路基础提出处理措施与建议。  相似文献   
908.
张敏  张立晶  袁淑芬  傅玉  张阳 《吉林地质》2010,29(2):109-111
可视化地层模型信息系统是基于GMS平台上建立的,可直观地显现不同性质的空间展布形态和空间组合特征,实现了研究区地层的拆分与组合,剖面的任意切割与显示,指定深度切割水平剖面,任意视角观测地层等信息的三维可视化直观表达,近年来已成为研究地质方面的一个新的亮点,为地质研究人员提供了方便快捷的资料信息。本文以洮儿河扇形地为例介绍可视化地层模型信息系统在水文地质环境地质中的应用。  相似文献   
909.
杜秋定  王剑  汪正江  邓奇  杨菲 《地球科学》2021,46(7):2529-2543
扬子地块莲沱组及相当地层单元的划分和对比,一直是我国南华系(即Cryogenian)研究关键难题之一.新元古代裂谷盆地开启早期,构造-沉积分异作用,同裂谷相变很大,使得盆地边缘区地层序列不完整.过分依赖岩石地层单元对比,历存分歧,典型的就是关于莲沱组与板溪群地层对比、时代归属以及莲沱组的沉积环境问题.本文通过对扬子地块...  相似文献   
910.
贵州中三叠世生物礁   总被引:13,自引:0,他引:13       下载免费PDF全文
贺自爱  杨宏  周经才 《地质科学》1980,15(3):256-264
贵州中三叠世生物礁,早在六十年代中期,殷鸿福、杨遵仪就已提出线索。作者在六十年代初研究贵州三叠纪地层时,已对三叠系相变带的特征和规模,以及板庚碳酸盐岩体有了初步认识。七十年代初,作者又到花江进行调查,发现一套壮观的藻礁灰岩。  相似文献   
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