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831.
Scholars are rarely able to examine anti-dam movements that result in project suspensions or cancellations since these cases are rare empirically. Yet, they are central to understanding how anti-dam movements can succeed. This paper analyzes the movements against Myanmar’s Myitsone Dam and Thailand’s Kaeng Suea Ten Dam. Likely the most successful anti-dam movements in Southeast Asia in recent years, they achieved suspension over 6 and 37 years, respectively. The research is based on 60 semistructured interviews carried out over a period of 8 months. Leveraging thinking from both the constructionist and structural schools within the field of social movement studies, it is found that the framing of the Myitsone Dam as a project threatening the national cultural heritage of Myanmar (in combination with political change in the country in 2010/2011) largely explains the movement’s success. Meanwhile, the set of sophisticated tactics (including inter alia demonstrations, Thai Baan research, 24/7 monitoring of the dam site, and spiritual activities) was decisive for the efficacy of the movement against Thailand’s Kaeng Suea Ten Dam.  相似文献   
832.
基于闪电先导随机模式对不同连接形态的模拟   总被引:5,自引:5,他引:0       下载免费PDF全文
考虑到下行负极性地闪过程中大多上行正先导发展时不分叉的观测事实,基于已有的闪电先导二维随机模式,改变上行正先导的模拟方案,使其发展时不产生分叉,并对雷击高建筑物过程中下行先导与上行连接先导 (upward connecting leader,UCL) 之间头部-头部连接和头部-侧面连接 (侧击) 的两种形态进行模拟。以高度为440 m的建筑物为例,通过改变下行先导始发点 (高度为1000 m) 与高建筑物的水平距离,模拟高建筑物上雷击过程中先导之间的连接过程,结果表明:当下行先导始发点与高建筑物的水平距离从0增加到700 m时,UCL的长度呈持续增大趋势,UCL受侧击的概率总体上呈先增大后减小的趋势 (在距离为500 m时达到最大值58%),侧击时UCL连接点以上的部分占整个UCL长度的比例总体呈持续增大趋势 (13%~49%)。  相似文献   
833.
Aimed at the hydrodynamic response for marine structures slamming into water, based on the mechanism analysis to the slamming process, and by combining 3D N?S equation and turbulent kinetic equation with structure fully 6DOF motion equation, a mathematical model for the wind-fluid-solid interaction is established in 3D marine structure slamming wave at free poses and wind-wave-flow complex environments. Compared with the results of physical model test, the numerical results from the slamming wave well correspond with the experimental results. Through the mathematical model, the wave-making issue of 3D marine structure at initial pose falls into water in different complex wind, wave and flow environments is investigated. The research results show that various kinds of natural factors and structure initial poses have different influence on the slamming wave, and there is an obvious rule in this process.  相似文献   
834.
Processes like injection, magma flow and differentiation and influence of the regional strain field are here described and contrasted to shed light on their role in the formation of small plutons and large batholiths their magmatic structures. The final geometric and compositional arrangement of magma bodies are a complex record of their construction and internal flow history. Magma injection, flow and differentiation, as well as regional stresses, all control the internal nature of magma bodies. Large magma bodies emplaced at shallow crustal levels result from the intrusion of multiple magma batches that interact in a variety of ways, depending on internal and external dynamics, and where the early magmatic, growth-related structures are commonly overprinted by subsequent history. In contrast, small plutons emplaced in the brittle-ductile transition more likely preserve growth-related structures, having a relatively simple cooling history and limited internal magma flow. Outcrop-scale magmatic structures in both cases record a rich set of complementary information that can help elucidate their evolution. Large and small granitic bodies of the Sierra Pampeanas preserve excellent exposures of magmatic structures that formed as magmas stepped through different rheological states during pluton growth and solidification. These structures reveal not only the flow pattern inside magma chambers, but also the rheological evolution of magmas in response to temperature evolution.  相似文献   
835.
陈兴  薛春纪 《岩石学报》2016,32(5):1301-1314
乌拉根铅锌矿是中国西北地区目前探明金属量最大的铅锌矿床,但大规模成矿所需H2S的成因方式尚不清楚。在野外调查和矿相学观察基础上,论文通过场发射扫描电镜(FESEM)、能谱(EDS)和质谱(MS)观测分析表明,矿石中发育闪锌矿纳米莓球、丝/管状结构,它们由他形闪锌矿微晶集合而成,莓球直径30~700nm,丝/管状结构与莓球密切共生;常见与闪锌矿等矿石矿物共生的方解石纳米莓球结构,由他形方解石微晶集合而成,莓球直径20~800nm;也常见与矿石矿物共生的菱铁矿微米莓球、丝/管状结构,它们由他形菱铁矿微晶集合而成,莓球直径1~3μm,表面毛糙,丝/管状结构常出现在莓球周围并连接着莓球。这些纳/微米莓球在矿石中成群落不均匀分布,属细菌微生物成因,丝/管状结构为胞外聚合物的表现。矿石δ34SCDT变化大且显著偏负值(-27.9‰~15.0‰)。乌拉根大规模铅锌硫化物成矿所需H2S可能主要通过细菌硫酸盐还原(BSR)产生,盆地流体中烃类有机质催化下的细菌微生物硫酸盐还原反应是乌拉根铅锌大规模成矿的重要过程。  相似文献   
836.
乌尼特坳陷属于二连盆地五大坳陷之一,早白垩世在区域引张力下形成一系列地堑、半地堑,其伸展构造由伸展断层及变换构造组成。伸展断层中的主边界断层主要为铲式,混杂岩断陷带主边界断层多在混杂岩深层滑脱,复式向斜断陷带主边界断层多在浅层滑脱。平面上主边界断层表现为简单弧形或波状延伸,位移量通过变换断层及走向斜坡等进行调节/传递。首尾相连的断陷间主要以狭窄的背向型(divergent)及宽阔的相向型(convergent)变换带进行构造变换,穿过变换带断陷极性常常发生变化。早白垩世早期,乌尼特坳陷由多个相互独立的小型断陷组成;早白垩世中期,随着伸展量不断加大,相邻断陷边界断层逐渐侧向连接成为区域性边界断层,相邻断陷侧向连接成为大型复式断陷;早白垩世晚期,断陷群下沉坳陷进入后裂陷期。  相似文献   
837.
海洋链霉菌由于其独特的生理和代谢功能,成为海洋微生物活性物质的主要来源。对2010-2013年初的海洋放线菌天然产物的统计表明,研究最多的是链霉菌放线菌,占海洋放线菌新天然产物的60%。本文综述了自1976年第一个海洋链霉菌天然产物到2016年6月的40年间报道的547个海洋链霉菌天然产物的结构、生物活性及其微生物来源。其结构包括含氮化合物(如生物碱)、聚酮、萜类、甾体等,其中含氮化合物是主要类型, 占海洋链霉菌天然产物总数的61%;而67%的海洋链霉菌天然产物表现出细胞毒、抑菌、抗疟和抗寄生虫等生物活性。  相似文献   
838.
The Helvetic nappe system exhibits three-dimensional (3-D) features such as the lateral variation in geometry between the Morcles and Doldenhorn fold nappes or the Rawil depression. We perform 3-D finite element simulations of linear and power-law viscous flow to investigate fold nappe formation during shortening of a half graben with laterally varying thickness. 3-D ellipsoids and corresponding 2-D intersection ellipses are used to quantify finite strain. Fold nappes which formed above a thicker graben have (i) larger amplitudes, (ii) a less sheared and thinned overturned limb, and (iii) a larger thickness than fold nappes formed above a thinner graben. These results agree with observations for the Morcles and Doldenhorn nappes. We also perform 3-D simulations for a tectonic scenario suggested for the evolution of the Rawil depression. The basement is shortened and extended laterally and includes a graben which is oblique to the shortening direction and acts as mechanical weak zone. The graben causes laterally varying basement uplift generating a depression whose amplitude depends on the graben orientation and the stress exponent of basement and sediments. The axial plunge of the depression is smaller (approximately 10°) than the observed plunge (approximately 30°) indicating that additional processes are required to explain the geometry of the Rawil depression.  相似文献   
839.
Haiyun Shi  Guangqian Wang 《水文研究》2015,29(14):3236-3246
Due to climate change and its aggravation by human activities (e.g. hydraulic structures) over the past several decades, the hydrological conditions in the middle Yellow River have markedly changed, leading to a sharp decrease in runoff and sediment discharge. This paper focused on the impacts of climate change and hydraulic structures on runoff and sediment discharge, and the study area was located in the 3246 km2 Huangfuchuan (HFC) River basin. Changes in annual runoff and sediment discharge were initially analysed by using the Mann–Kendall trend test and Pettitt change point test methods. Subsequently, periods of natural and disturbed states were defined. The results showed that both the annual runoff and sediment discharge presented statistically significant decreasing trends. However, compared with the less remarkable decline in annual rainfall, it was inferred that hydraulic structures might be another important cause for the sharp decrease in runoff and sediment discharge in this region. Consequently, sediment‐trapping dams (STDs, a type of large‐sized check dam used to prevent sediment from entering the Yellow River main stem) were considered in this study. Through evaluating the impacts of the variation in rainfall patterns (i.e. amount and intensity) and the STD construction, a positive correlation between rainfall intensity and current STD construction was found. This paper revealed that future soil and water conservation measures should focus on areas with higher average annual rainfall and more rainstorm hours. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
840.
The cyclic behaviour of slender cantilever columns in full-scale models of precast industrial buildings, designed by Eurocode 8, was studied experimentally and analytically. The shear span ratio of the columns was 12.5, which is more than allowed by Eurocode 8 for columns in frame structures (10). High deformability and a large deformation capacity (8%~drift) of the columns was observed. A lumped plasticity model was used in the analysis. In the paper the observed behaviour of the models has been compared with the predicted behaviour obtained by several empirically based models and procedures. It was observed that these models, which were developed for much lower shear span ratios (2–6), were not applicable for the analyzed very slender columns without appropriate additional considerations and modifications. In the case of such columns the yield drift is dominated by the flexural mode (it is practically proportional to the height of the column) and the ultimate drift under cyclic loading conditions is only slightly dependent on the shear span (indicating that the ratio of the equivalent length of the plastic hinge to the height of the column decreases with the increasing shear span). An appropriately modified lumped plasticity model incorporating in-cycle and repeated-cycle strength deterioration was chosen for future use in performance-based design and seismic risk studies.  相似文献   
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