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651.
Study on electric variations of media in epicentral area by geomagnetic transfer functions 总被引:1,自引:0,他引:1
StudyonelectricvariationsofmediainepicentralareabygeomagneticransferfunctionsXiao-PingZENG;(曾小苹)Yun-FangLINI;(林云芳)Zhong-JieZH... 相似文献
652.
Distribution and source of heavy metals in the surface sediments from the near-shore area,north Jiangsu Province,China 总被引:1,自引:0,他引:1
Samples of surface sediment and vibrocore were collected in the near-shore area of north Jiangsu Province for grain size, elements, 210Pbexcess and 137Cs analyses. In our study area, the diversity of metal concentration was controlled not by the grain size, but by the source. The element content of the old Yellow River Delta was used as baseline for our study area. Geoaccumulation indexes indicate that no station was polluted by Cu, Pb, Zn and As, but the Igeo values of As were close to zero in some stations. Slight pollution caused by Cd was observed in some stations. Correlation and enrichment factors suggest that Cu, Pb and Zn are lithogenic in origin, while As and Cd are mixed in origin. Especially, in some polluted stations Cd was obviously anthropogenic in origin. 相似文献
653.
上扬子地区是我国页岩气重要开采区,也是氦气工业性开采的唯一地区,但对于其氦气生成潜力研究仍处于空白阶段.据此,对上扬子东南地区采集的144件岩石样品进行场发射扫描电镜及铀、钍强度测试,理论计算了页岩气中氦气达到我国工业开采标准(0.05%)需要满足的理论条件.岩石扫描电镜结果表明,富含铀、钍的副矿物(锆石、独居石、铀钍石及磷灰石等)主要赋存于造岩矿物石英和长石中.岩石铀、钍强度测试结果表明,三大类岩石中铀平均含量呈现:沉积岩(8.96×10-6)>岩浆岩(4.83×10-6)>变质岩(1.89×10-6);钍平均含量呈现:沉积岩(11.01×10-6)≈变质岩(10.4×10-6)>岩浆岩(5.9×10-6).岩浆岩中铀、钍平均含量呈现:酸性岩>中性岩>基性岩>超基性岩;沉积岩中铀平均含量呈现泥页岩(13.86×10-6)>>砂岩(2.54×10-6)>碳酸盐岩(1.67×10-6);钍平均含量呈现泥页岩(12.50×10-6)≈砂岩(12.76×10-6)>碳酸盐岩(5.96×10-6).不同沉积时代沉积岩中铀、钍平均含量也呈现上述分布规律.沉积岩中铀、钍含量主要与岩石的沉积环境与物源有关,与沉积时代无关.单位时间、单位质量岩石氦气生成量的大小为:泥页岩>酸性岩>中性岩>砂岩>变质岩>碳酸盐岩>基性岩>超基性岩.以中国南方地区上奥陶统五峰组—下志留统龙马溪组页岩为例,当该层位泥页岩中残余氦气含量为U,Th元素衰变释放出来氦气含量的80%以上时,适合进行"页岩气+氦气"的共同开采,提高页岩气的开采价值. 相似文献
654.
黑龙江省三江平原垦区是中国耕地规模最大的连片农垦区和第三大区际商品粮供应基地。近年来,随着这一地区工业化和城镇化进程的加快,如何科学的选择和建设区域的中心城市成为该区完善区域城镇体系和推进城镇化进程的紧迫任务和现实课题。基于此,应用改进的引力模型来计算县级单位与农场间的空间联系强度,界定出各县级单位的腹地范围,明确三江平原垦区的中心城市;以各农垦分局为研究单元,研究各农垦分局的碎化程度;通过明确县级单位拥有农场腹地数目,确定各农垦分局的中心城市;结果发现建三江、虎林、富锦、友谊和密山等宜作为三江平原垦区的中心城市;提出通过壮大中心城市的综合实力、推动场县共建和深化对外合作等措施来推动三江平原垦区城镇化进程。 相似文献
655.
Jiongxin Xu 《地球表面变化过程与地形》2008,33(8):1157-1173
Based on data from 35 stations on the tributaries of the Yellow River, annual specific sediment yield (Ys) in eight grain size fractions has been related to basin‐averaged annual sand–dust storm days (Dss) and annual precipitation (Pm) to reveal the influence of eolian and fluvial processes on specific sediment yield in different grain size fractions. The results show that Ys in fine grain size fractions has the highest values in the areas dominated by the coupled wind–water process. From these areas to those dominated by the eolian process or to those dominated by the fluvial process, Ys tends to decrease. For relatively coarse grain size fractions, Ys has monotonic variation, i.e. with the increase in Dss or the decrease in Pm, Ys increases. This indicates that the sediment producing behavior for fine sediments is different from that for relatively coarse sediments. The results all show that Ys for relatively coarse sediments depends on the eolian process more than on the fluvial process, and the coarser the sediment fractions the stronger the dependence of the Ys on the eolian process. The Ys–Dss and Ys–Pm curves for fine grain size fractions show some peaks and the fitted straight lines for Ys–Dss and Ys–Pm relationships for relatively coarse grain size fractions show some breaks. Almost all these break points may be regarded as thresholds. These thresholds are all located in the areas dominated by the coupled wind–water process, indicating that these areas are sensitive for erosion and sediment production, to which more attention should be given for the purpose of erosion and sediment control. A number of regression equations were established, based which the effect of rainfall, sand–dust storms and surface material grain size on specific sediment yield can be assessed. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
656.
657.
高性能计算通过应用超级计算机与并行处理技术解决复杂的计算问题,是信息技术发展比较迅猛的领域之一。气象应用始终是高性能计算的重要领域,高性能计算技术有效地解决了高分辨率、高精度气象数值预报模式发展限制,在气象预报预测业务中发挥着核心支撑作用。数十年以来,由于数值天气模式研究和业务运行对计算资源的强烈需求,国内外气象领域高性能计算机及应用迅速发展起来。气象领域对高性能计算能力及系统的可靠性需求日益提升。高性能计算技术将与气象预报应用日益融合,相互影响促进,不断创新发展。为满足气象预报预测业务和科研工作需求,中国气象部门将进一步提升高性能计算能力,并致力于优化集约高性能计算系统布局,高效管理计算资源,发挥最大效益。 相似文献
658.
The capture dynamics is an important field in Astronomy and Astronautics. In this paper, the near-optimal lunar capture in the Earth–Moon transfer is investigated under the frame of the planar circular restricted three-body problem. We try to work out how to achieve the permanent lunar capture with the minimum maneuver consumption. This problem is decomposed into two parts: the pre-maneuver part and the post-maneuver part. In the pre-maneuver part, considering the criteria of the gravitational capture, we obtain the minimum pre-maneuver velocity via the numerical backward integration. In the post-maneuver part, using the Poincaré section and the KAM theory, we find the maximum post-maneuver velocity to achieve the permanent capture. Synthesized the results of the two parts, a new method is presented to find the near-optimal maneuver position and the minimum maneuver consumption. The method presented is simple and visible, and can provide abundant capture orbits for the design of low energy Earth–Moon transfers. 相似文献
659.
Samples of suspended particulate matters(SPMs),surface sediment and road dust were collected from the Yangtze estuarine and nearby coastal areas,coastal rivers,and central Shanghai.The samples were analyzed for the presence of 16 polycyclic aromatic hydrocarbons(PAHs)in the USEPA priority-controlled list by GC-MS.The compound-specific stable carbon isotopes of the individual PAHs were also analyzed by GC-C-IRMS.The sources of PAHs in the SPMs and surface sediments in the Yangtze estuarine and nearby coastal... 相似文献
660.
据KCl含量的概率分布特征,晶间卤水分为7个总体。晶间卤水KCl,在三级系统内水平分异有2种、剖面分异有5种,二级系统内水平分异呈环带状、剖面分异形式为三级系统内分异形式的组合,垂直分异有13种;富集的总体为Ⅳ(kcl)、Ⅲ(kcl)用V(kcl)、三级系统为(8)和(10)号、部位为固相钾高含处;分异及富集的成因主要为晶间卤水的阶段性淡化。 相似文献