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31.
Taking into account magneto-optical effects, we have obtained numerical solutions of the transfer equations for the Stokes parameters, calculated the linearly polarized intensity (U) and constructed its monochromatic images of unipolar sunspots. By comparison with the observational material of the vector magnetograph of the Marshall Space Flight Center, Huntsville (Alabama), we have found that the model of radial magnetic fields may give rise to U monochromatic images close to those observed. The same conclusion has been obtained previously by Landi Degl'Innocenti (1979), although his analysis was performed with the Milne-Eddington approximation instead of a detailed sunspot model. Moreover, we have shown that the model of spiral magnetic fields leads to results in contrast with observations. 相似文献
32.
Xie-Yan Song Hua-Wen Qi Paul T. Robinson Mei-Fu Zhou Zhi-Min Cao Lie-Meng Chen 《Lithos》2008,100(1-4):93-111
The Emeishan continental flood basalt (ECFB) sequence in Dongchuan, SW China comprises a basal tephrite unit overlain by an upper tholeiitic basalt unit. The upper basalts have high TiO2 contents (3.2–5.2 wt.%), relatively high rare-earth element (REE) concentrations (40 to 60 ppm La, 12.5 to 16.5 ppm Sm, and 3 to 4 ppm Yb), moderate Zr/Nb and Nb/La ratios (9.3–10.2 and 0.6–0.9, respectively) and relatively high Nd (t) values, ranging from − 0.94 to 2.3, and are comparable to the high-Ti ECFB elsewhere. The tephrites have relatively high P2O5 (1.3–2.0 wt.%), low REE concentrations (e.g., 17 to 23 ppm La, 4 to 5.3 ppm Sm, and 2 to 3 ppm Yb), high Nb/La (2.0–3.9) ratios, low Zr/Nb ratios (2.3–4.2), and extremely low Nd (t) values (mostly ranging from − 10.6 to − 11.1). The distinct compositional differences between the tephrites and the overlying tholeiitic basalts cannot be explained by either fractional crystallization or crustal contamination of a common parental magma. The tholeiitic basalts formed by partial melting of the Emeishan plume head at a depth where garnet was stable, perhaps > 80 km. We propose that the tephrites were derived from magmas formed when the base of the previously metasomatized, volatile-mineral bearing subcontinental lithospheric mantle was heated by the upwelling mantle plume. 相似文献
33.
34.
Correlations between heavy metals and organic carbon extracted by dry oxidation procedure in urban roadside soils 总被引:1,自引:0,他引:1
Xue Song Wang 《Environmental Geology》2008,54(2):269-273
The organic fraction in soils has a significant influence on heavy metal transport. In this study, the organic carbon content
was measured by dry oxidation procedure from 21 Xuzhou urban roadside soils to assess the relationships between the concentrations
of heavy metals (Pb, Cu, Zn, and Cr) and the amount of organic carbon. The anthropogenic heavy metals (e.g. Pb, Cu, Zn) were
strongly correlated with organic carbon (denoted by Corg−c) extracted by dry oxidation while natural heavy metal (e.g. Cr) showed no correlation to the Corg−c. The anthropogenic heavy metals were also strongly correlated with the amount of the total carbon. These results show that
the anthropogenic heavy metals are mainly enriched in the organic matter in the Xuzhou urban roadside soils. 相似文献
35.
Application of MODFLOW and geographic information system to groundwater flow simulation in North China Plain, China 总被引:2,自引:0,他引:2
Shiqin Wang Jingli Shao Xianfang Song Yongbo Zhang Zhibin Huo Xiaoyuan Zhou 《Environmental Geology》2008,55(7):1449-1462
MODFLOW is a groundwater modeling program. It can be compiled and remedied according to the practical applications. Because
of its structure and fixed data format, MODFLOW can be integrated with Geographic Information Systems (GIS) technology for
water resource management. The North China Plain (NCP), which is the politic, economic and cultural center of China, is facing
with water resources shortage and water pollution. Groundwater is the main water resource for industrial, agricultural and
domestic usage. It is necessary to evaluate the groundwater resources of the NCP as an entire aquifer system. With the development
of computer and internet information technology it is also necessary to integrate the groundwater model with the GIS technology.
Because the geological and hydrogeological data in the NCP was mainly in MAPGIS format, the powerful function of GIS of disposing
of and analyzing spatial data and computer languages such as Visual C and Visual Basic were used to define the relationship
between the original data and model data. After analyzing the geological and hydrogeological conditions of the NCP, the groundwater
flow numerical simulation modeling was constructed with MODFLOW. On the basis of GIS, a dynamic evaluation system for groundwater
resources under the internet circumstance was completed. During the process of constructing the groundwater model, a water
budget was analyzed, which showed a negative budget in the NCP. The simulation period was from 1 January 2002 to 31 December
2003. During this period, the total recharge of the groundwater system was 49,374 × 106 m3 and the total discharge was 56,530 × 106 m3 the budget deficit was −7,156 × 106 m3. In this integrated system, the original data including graphs and attribution data could be stored in the database. When
the process of evaluating and predicting groundwater flow was started, these data were transformed into files that the core
program of MODFLOW could read. The calculated water level and drawdown could be displayed and reviewed online. 相似文献
36.
Huijun Jin Zhi Wei Shaoling Wang Qihao Yu Lanzhi Lü Qingbai Wu Yanjun Ji 《Engineering Geology》2008,101(3-4):96-109
The Qinghai–Tibet Highway and Railway (the Corridor) across the Qinghai–Tibet Plateau traverses 670 km of permafrost and seasonally frozen-ground in the interior of the Plateau, which is sensitive to climatic and anthropogenic environmental changes. The frozen-ground conditions for engineering geology along the Corridor is complicated by the variability in the near-surface lithology, and the mosaic presence of warm permafrost and talik in a periglacial environment. Differential settlement is the major frost-effect problem encountered over permafrost areas. The traditional classification of frozen ground based on the areal distribution of permafrost is too generalized for engineering purposes and a more refined classification is necessary for engineering design and construction. A proposed classification of 51 zones, sub-zones, and sections of frozen ground has been widely adopted for the design and construction of foundations in the portion of the Corridor studied. The mean annual ground temperature (MAGT), near-surface soil types and moisture content, and active faults and topography are most commonly the primary controlling factors in this classification. However, other factors, such as local microreliefs, drainage conditions, and snow and vegetation covers also exert important influences on the features of frozen ground. About 60% of the total length of the Corridor studied possesses reasonably good frozen-ground conditions, which do not need special mitigative measures for frost hazards. However, other sections, such as warm and ice-rich or -saturated permafrost, particularly in the sections in wetlands, ground improvement measures such as elevated land bridges and passive or proactive cooling techniques need to be applied to ensure the long-term stability of thermally unstable, thick permafrost subsoils, and/or refill with non-frost-susceptible soils. Due to the long-history of the construction and management of the Corridor by various government departments, adverse impacts of construction and operation on the permafrost environment have been resulted. It is recommended that an integrated, executable plan for the routing of major construction projects within this transportation corridor be established and long-term monitoring networks installed for evaluating and mitigating the impact from anthropogenic and climatic changes in frozen-ground conditions. 相似文献
37.
乌鲁木齐河流域地下水水质监测网设计 总被引:1,自引:0,他引:1
文章运用地下水易污性编图及污染源分布图法进行了乌鲁木齐河流域地下水水质监测网设计。共设计了130监测孔,现有46个监测孔,另需要84个新的监测孔。按监测类型分为面源监测点22个,点源监测点87个,重点水源地与泉水监测点21个。按监测运行分长期监测点55个,流域普查监测点75个。普查监测点监测频率为1次/5年,长期监测点监测频率为1次/年。首期有针对性地在污染严重的柴窝堡新化厂排污区、乌鲁木齐河谷老排污区、米泉污灌区、米泉工业污染区、老龙河污染区取了25个污染水样测试分析,结果显示地下水已经受到严重污染。 相似文献
38.
旋转轴套在超深井工作时,其井下流动是三维湍流流动,旋转轴套的旋转和表面曲率效应以及随之而来的哥氏力和离心力,使流场在超深井的流动中极其复杂,同时,由于流体介质泥浆属于液固两相流,更致使内部流场测试困难,而且超深井中的工况在使用常规方法已很难得到较准确的数据。为此,将计算流体力学软件Fluent应用于超深井下流场的模拟,基于Navier-Stokes方程和Reynolds应力方程模型,建立多种仿真模型,在相同条件下,使用CFD仿真软件Fluent模拟仿真的不同结果,优化与旋转轴套叶片设计相关的几何参数,提高 相似文献
39.
40.
河流集合预报方法(ESP)在水资源中长期预测中的应用研究 总被引:1,自引:0,他引:1
中长期径流预测是水文水资源研究领域中的一项重要内容,为水资源规划管理及可持续利用、防汛抗旱、水库调度与发电计划制作、工农业用水计划编制等提供科学依据,对国民经济发展具有十分重要的意义.但由于大气圈极其复杂,水文要素并非仅是气象强迫输入的函数.它还受流域基本特性,前期来水以及人类活动等诸多因素的影响,中长期径流预测在其计算中存在着多种不确定性.因此,中长期径流预测一直是水文预测研究中难度较大的课题之一.本文引入河流集合预报方法(ESP),以丹江口水库为应用实例,利用水文气象历史资料和新安江水文模型,预测分析水库2007年10月份每旬的平均入库流量及概率分布统计,并经与实测流量过程对比分析,满足水库运行调度需求,为水库发电计划制作提供了可靠依据. 相似文献