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151.
152.
Acta Geotechnica - Electro-osmotic consolidation is taken as a valid and practical approach for soft ground improvement, and it is of vital significance to study the consolidation behaviour of... 相似文献
153.
Natural Hazards - East African countries (Uganda, Kenya, Tanzania, Rwanda, and Burundi) are prone to weather extreme events. In this regard, the past occurrence of extreme rainfall events is... 相似文献
154.
155.
近十余年来,湖南省矿业权出让管理制度不断规范和完善,矿业权市场建设成效显著,市场化配置水平也明显提高。党的十八届三中全会对资源配置提出了"使市场在资源配置中起决定性作用和更好发挥政府作用"的更高要求,为进一步分析研判湖南省矿产资源的市场化配置现状及存在问题,笔者对我国及该省矿业权出让管理制度建设情况进行了梳理,并对其2003年以来探矿权、采矿权出让情况进行统计分析,针对资源市场化配置等方面存在的问题提出有关思考和建议。 相似文献
156.
Estimating the yaw-attitude of BDS IGSO and MEO satellites 总被引:1,自引:1,他引:0
Xiaolei Dai Maorong Ge Yidong Lou Chuang Shi Jens Wickert Harald Schuh 《Journal of Geodesy》2015,89(10):1005-1018
157.
中国东北红河国家级自然保护区湿地植被空间格局与环境梯度关系(英文) 总被引:1,自引:0,他引:1
Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protection and restoration of natural wetlands. In this study, the spatial patterns of wetland plants and the environmental gradient of wetland habitats were assessed in the Honghe National Nature Reserve (HNNR) in Northeast China, a wetland of international importance on the Ramsar list. Biophysical parameters’ values of wetland plants were obtained by field sampling methods, and wetland mapping at the community scale was completed using remote sensing techniques. Digital delineation of the surface water system, hydrological zoning and wetness index were produced by spatial analysis methods in Geographic Information System. An ecological ordination method and two clustering methods were used to quantify the relationship between the spatial distribution patterns of wetland plants and the corresponding environmental gradients. Such quantitative analyses also present the specific diversity of different types of wetland plants based on the environmental attributes of their habitats. With the support from modern geo-information techniques, the experimental results indicate how four ecotypes of wetland plants spatially transit from forest swamp, shrub wetland and meadow into marsh wetland with increasing wetness index and water table. And they also show how wetland spatial distribution patterns are controlled by an environmental gradient of wetness. Another key finding of this research work is that our results present the exact fundamental differences between marsh and non-marsh plants of 11 wetland plant communities within the core study area. Hence, this case study gives a good sample for better understanding of the complex correlation between the spatial patterns of wetland plants and their environmental attributes using advanced digital analysis methods. It is also useful to show how to integrate geoinformatic techniques with statistical analysis methods based on the field data base. 相似文献
158.
We explore self-similar hydrodynamic evolution of central voids embedded in an isothermal gas of spherical symmetry under
the self-gravity. More specifically, we study voids expanding at constant radial speeds in an isothermal gas and construct
all types of possible void solutions without or with shocks in surrounding envelopes. We examine properties of void boundaries
and outer envelopes. Voids without shocks are all bounded by overdense shells and either inflows or outflows in the outer
envelope may occur. These solutions, referred to as type
void solutions, are further divided into subtypes
and
according to their characteristic behaviours across the sonic critical line (SCL). Void solutions with shocks in envelopes
are referred to as type
voids and can have both dense and quasi-smooth edges. Asymptotically, outflows, breezes, inflows, accretions and static outer
envelopes may all surround such type
voids. Both cases of constant and varying temperatures across isothermal shock fronts are analyzed; they are referred to as
types
and
void shock solutions. We apply the ‘phase net matching procedure’ to construct various self-similar void solutions. We also
present analysis on void generation mechanisms and describe several astrophysical applications. By including self-gravity,
gas pressure and shocks, our isothermal self-similar void (ISSV) model is adaptable to various astrophysical systems such
as planetary nebulae, hot bubbles and superbubbles in the interstellar medium as well as supernova remnants.
相似文献
159.
160.
城市化对江苏气候变化影响的数值模拟个例分析 总被引:5,自引:3,他引:2
利用MM5模式对2003年夏季6、7两个月典型区域气候极端事件进行数值模拟,研究城市化急剧扩张对区域气候极端事件的影响和可能机制.研究发现:苏南及邻近地区城市化区域的扩张,会引起区域降水分布的变化.在城市化区域,降水将减少,而在城市化的下风区会有局地的降水增加;同时,在苏南城市化区域中,太湖等湖泊的影响也很重要,会加强其邻近地区局地降水强度.城市化区域的地面气温有明显的上升,对高温天气的作用更大.城市化也会影响地面风场,阻挡穿越城市化区域的风;苏南沿海城市化区域扩张,会使海陆风环流增强,加大了海面向陆面的风.城市化区域的潜热通量明显减少,而感热通量显著增加.城市化增暖产生的局地热源,使城市化区域及邻近地区局地环流发生变化,增强了低层城市化区域向周边辐散的强度.随着高度的增加,城市化的影响也越来越小. 相似文献