基于分形理论的黄河内蒙古段河势演变特征及其与凌汛灾害关联研究

寒区河道凌汛灾害河势“弯道效应”的量化评估十分重要。基于分形理论提出河道横断面-纵剖面-平面多维度河势分形维数计算方法及其物理机制，并探讨黄河内蒙古段不同维度河势演变分形特征及其与凌汛灾害的关联关系。结果表明，黄河内蒙古段不同维度河势均具有多尺度自相似分形特征，且具有多年记忆周期的长程相关性；冰坝（严重性冰塞）发生频次与河道主槽弯曲分形维数呈正相关指数型函数关系，与河相系数、深泓点高程和河段平均底坡分形维数负相关，与水深-面积分形维数正相关，总体表明冰坝灾害更易发生于主槽偏移摆动大、蜿蜒曲折、河湾发育程度高的宽浅型弯曲河道，研究成果可为凌汛期冰塞冰坝灾害易发河段诊断及预测提供重要理论依据。     

5G双小区协作流动热点补偿研究

在通信用户数密集用户业务总量较多的UMi场景下,无线网络节点较多小区覆盖半径较小,用户在小区间移动导致小区间用户分布不均匀,原有用户数及业务量标准部署的5G异构网络相对稀疏,无法满足用户流动产生热点热时容量需求时,双小区协作流动热点补偿采用异构网络多点协作传输技术对小区进行补热,将处于相同移动状态的多个用户虚拟成一个以中心用户为中心的用户簇,建立3D MIMO流动热点模型,提出在两小区以用户最小传输速率为约束条件,最小化小区基站总功率的优化算法,得出高容量、高速率用户体验的"潮汐效应"解决方案。     

潮流能水平轴水轮机在剪切来流下的水动力分析

采用基于计算流体力学方法的全尺度数值模拟计算,建立了适用于潮流能水轮机模拟的剪切来流环境,通过数值计算结果,对潮流能水轮机随时间变化的宏观力和流场特征进行了系统分析,探索水轮机在复杂工况下的水动力特性规律。结果表明,水轮机整个叶轮的总体平均受力在剪切流工况中未受到明显影响; 单个叶片的瞬态轴向力系数和瞬态轴向扭矩系数在旋转周期内出现了明显的周期性变化,且周期性变化幅值随转速增大而增大; 非定常的瞬时轴向扭矩和力的周期性振荡容易引起单个叶片的结构性振动,可能对水轮机的机械结构造成影响。     

基于正交试验的非对称垂直轴水轮机数值模拟

运用正交试验法开展了具有非对称NACA翼型的垂直轴潮流能水轮机的非定常数值模拟研究,分析弯度、弯度位置、前缘半径、最大厚度位置对叶轮能量提取率的影响。使用极差分析法确定了各因素影响的主次顺序和各尖速比下由最优参数确定的翼型。结果表明:在不同尖速比下,弯度是影响水轮机性能的主导因素,对水轮机能量提取率的贡献率分别为44.7%(尖速比λ=2.25)、53.4%(尖速比λ=2.5)和59.4%(尖速比λ=2.75);次要因素为最大厚度所在位置,其余两个参数对其性能影响较小。针对最优参数确定的翼型进行验证,结果证实具有该翼型的水轮机的动力学性能要好于其他翼型。     

澜湄环境利益共同体模式的评价与选择研究

推进澜湄合作是构建周边命运共同体的具体实践，以“同饮一江水，命运紧相连”为主题的澜湄合作机制也为构建澜湄国家命运共同体提供了推进方向。环境问题是澜湄流域最为核心的问题之一，面向澜湄合作中的环境利益问题，文章结合共同体的理念，基于霍尔三维结构理论，总结出合作伙伴环境利益共同体模式、合作联盟环境利益共同体模式与一体化环境利益共同体模式的三种环境利益共同体模式，通过建立环境利益共同体模式的评价指标体系，利用网络层次分析法对澜湄环境利益共同体模式进行评价，选择适合澜沧江-湄公河的环境利益共同体模式。结果表明，在当前的澜湄现状下，以“澜湄六国通过开发流域资源发展本国经济而同时受到其他主体监督以保证不破坏澜沧江-湄公河的生态环境”为主要内容的合作联盟环境利益共同体模式更适合澜湄流域各国，这一模式可以有效解决流域各国经济与环境“两难重”的困境。     

The potential limitations on its basin decision-making processes of granting self-defence rights to Father Rhine

ABSTRACT

Recent grants of legal rights to rivers would seem to infuse traditional anthropocentric river governance with greater eco-centrism. Through a thought experiment, we scrutinize this proposition for the Rhine basin. We consider the governance implications of granting (procedural/material) rights to the river and elaborate on their implications for the three highly institutionalized regimes of the Rhine River of water quality, flooding and transport. Since we find that a shift to more eco-centrism has already occurred and since the right granted to the river would not be absolute, we deem radical transformations unlikely.     

Can Tolerant Diatom Taxa be Used for Effective Assessments of Human Pressure?

Because lately the low bioindicative value of tolerant species from different taxonomic groups is often questioned, in this study, we hypothesized that tolerant diatoms may be used for effective temporal assessments of human pressure. We tested this on the lowland Bzura River in central Poland, on 156 diatom samples (DSs) from two study periods of 1972 with extremely severe point‐source water pollution and of 2002–2004, where the complex wastewater management in the river catchment improved water quality considerably. Out of the total 295 diatom species recorded in the samples, only 133 tolerant ones were included in the study. Patterns in their abundance were recognized with a Kohonen artificial neural network (self‐organizing map, SOM), whereas the species significantly associated with each SOM cluster of diatom samples were identified with the indicator value (IndVal) index and the Monte Carlo test. If the hypothesis tested was not supported, the assignation of DSs to the SOM clusters would be random. However, the separation of DSs from 1972 and 2002–2004 was almost perfect because the number of exceptions was as low as 4.5%. In addition, the relatively high number (64 out of 133) of tolerant species significantly associated with any SOM cluster (and respective environmental conditions at sites from which samples assigned to it come) supports the hypothesis tested. This means that almost half of the studied species are not evenly distributed in particular clusters as might be expected for highly tolerant species. The study proves that the abundances of many diatom species, currently classified as tolerant, carry quite precise information on the differences in the quality of the environment, and indicates those tolerant diatom species whose bioindicative potential may be highest. Copyright © 2014 John Wiley & Sons, Ltd.