Experimental Study on A Sloshing Mitigation Concept Using Floating Layers of Solid Foam Elements

A sloshing mitigation concept taking advantage of floating layers of solid foam elements is proposed in the present study. Physical experiments are carried out in a liquid tank to investigate the hydrodynamic mechanism of this concept. Effects of the foam-layer thickness, excitation amplitude, and excitation frequency on the sloshing properties are analyzed in detail. It is found that the floating layers of solid foam elements do not evidently affect the fundamental natural sloshing frequency of the liquid tank evidently among the considered cases. At the resonant condition, the maximum wave height and dynamic pressure are greatly reduced as the foam-layer thickness increases. Higher-order pressure components on the tank side gradually vanish with the increase of the foam-layer thickness. Cases with different excitation amplitudes are also analyzed. The phenomenon is observed when the wave breaking in the tank can be suppressed by solid foam elements.     

Process and Contextual Factors Supporting Action-Oriented Learning: A Thematic Synthesis of Empirical Literature in Natural Resource Management

Despite a long-term focus on learning in natural resource management (NRM), it is still debated how learning supports sustainable real-world NRM practices. We offer a qualitative in-depth synthesis of selected scientific empirical literature (N?=?53), which explores factors affecting action-oriented learning. We inductively identify eight key process-based and contextual factors discussed in this literature. Three patterns emerge from our results. First, the literature discusses both facilitated participation and self-organized collaboration as dialogical spaces, which bridge interests and support constructive conflict management. Second, the literature suggests practice-based dialogs as those best able to facilitate action and puts a strong emphasis on experimentation. Finally, not emphasized in existing reviews and syntheses, we found multiple evidence about certain contextual factors affecting learning, including social-ecological crises, complexity, and power structures. Our review also points at important knowledge gaps, which can be used to advance the current research agenda about learning and NRM.     

大城市郊区村域土地利用功能演变及其对乡村振兴的启示——以成都市江家堰村为例

村域是我国农村社会经济活动的基本单元,村域土地利用功能的合理发挥对于实现乡村振兴多元目标具有重要的理论和现实意义。本文首先对村域土地利用功能变化及影响机制进行了理论探究,然后以成都市郊区江家堰村为例,定量揭示了其发展转型过程中的土地利用功能变化、影响机制,提出了土地多功能利用助推乡村振兴途径。结果表明：① 土地利用功能因土地利用类型和土地利用方式变更发生变化,并受自然资源禀赋、社会经济条件、区域政策等间接影响,不同类型乡村其土地利用功能变化趋势往往不同;② 江家堰村经历了乡村旅游发展阶段、土地综合整治和生态建设阶段,其土地利用功能变化主要表现为生产功能转化为生产-生态复合功能,生活功能转化为生产-生活复合功能,土地利用功能呈现多元化和复合化特征;③ 大城市郊区乡村土地利用功能变化受自然因素、区位条件、产业转型、区域政策及土地利用主体等因素的综合影响。乡村振兴过程中,应充分发挥土地利用的多功能属性,促进乡村价值提升。     

4-硝基苯并-15-冠醚-5液液萃取分离锂同位素

以4-硝基苯并-15-冠醚-5(4-NO_2-B15C5)做萃取剂,苯甲醚和1-丁基-3-甲基咪唑双(三氟甲烷磺酰)亚胺盐([C_4mim][NTf_2])作稀释剂和协萃剂,以1 mol/L LiCl溶液作萃取溶剂,构建高效的冠醚—离子液体/锂盐溶液的溶剂萃取体系。重点考察了有机相组成、冠醚浓度和锂盐阴离子等对锂同位素分离的影响。结果表明,4-硝基苯并-15-冠醚-5具有良好的锂同位素分离效果,在萃取CF_3COOLi时最大单级分离系数(α)可达1.043±0.01。     

Stability and long-range correlation of air temperature in the Heihe River Basin

Journal of Geographical Sciences - Air temperature (AT) is a subsystem of a complex climate. Long-range correlation (LRC) is an important feature of complexity. Our research attempt to evaluate...     

辽东岫岩王家堡子地区二长花岗岩U-Pb年代学、地球化学特征及其地质意义

辽东半岛岫岩王家堡子地区位于胶-辽-吉造山/活动带中段。本文对该区内的二长花岗岩（龙潭沟岩体与罗圈沟岩体）进行了U-Pb年代学与地球化学特征研究,并探讨了其地质意义。结果表明：龙潭沟岩体与罗圈沟岩体侵位年龄分别为（122.37±0.30）Ma和（124.37±0.91）Ma,年代为早白垩世;二岩体具高SiO₂质量分数,低Mg、Co、Cr、Ni质量分数,富集LREE和LILE,亏损HFSE,说明二者为地壳物质熔融的产物;高Al₂O₃、K₂O质量分数,低Na₂O、MnO和CaO质量分数,高Sr质量分数,低Y、Yb质量分数,富集LILE及LREE,Eu呈负异常,亏损HREE等地球化学特征,也表明二者具有埃达克岩与高钾钙碱性I型花岗岩的性质。龙潭沟岩体岩浆来源于洋壳俯冲导致的加厚陆壳底部基性岩部分熔融,而罗圈沟岩体岩浆则是俯冲洋壳导致地幔物质上涌,使得玄武质下地壳发生部分熔融的结果,并且岩浆受到了地幔橄榄岩的混染。认为龙潭沟岩体与罗圈沟岩体均为碰撞环境中的产物,辽东岫岩王家堡子地区在124~122 Ma处于由古太平洋板块俯冲引起的挤压环境中,构造挤压向拉伸环境的转换应在122~110 Ma之间完成,岩石圈的减薄与破坏也随之开始。     

生计风险及其对重点生态功能区农户生活满意度的影响

基于甘南黄河水源补给区入户调查数据,在分析农户生计风险及生活满意度特征的基础上,探明生计风险对农户生活满意度的影响。结果发现：① 甘南黄河水源补给区农户面临的主要生计风险为自然灾害、家人患病和子女学费开支,其对农户的冲击最为严重且持续时间较长;② 农户大多遭受多重风险的冲击,其生计风险多样化指数为4.12,面临家人患病与自然灾害、家人患病与子女学费开支、家人患病与建房开支等风险组合冲击的家庭较多;③ 农户的生活满意度处于中等水平,且经济示范区高于重点保护区和恢复治理区;④ 农户生活满意度除受子女学费开支、草场/耕地质量下降、人畜饮水困难、家人去世开支、生态政策等风险的严重程度和持续时间、家人患病风险的持续时间以及金融资本、自然资本、社会资本、心理资本、生计方式多样化程度的影响外,受家人患病与子女学费开支、自然灾害与子女就业困难及生计风险的综合严重性程度与综合持续性程度交互作用的影响更加显著。最后,提出防范生计风险、提高生活满意度的政策建议。     

Spatiotemporal variations of aridity index over the Belt and Road region under the 1.5°C and 2.0°C warming scenarios

Journal of Geographical Sciences - Aridity index reflects the exchanges of energy and water between the land surface and the atmosphere, and its variation can be used to forecast drought and flood...     

Theory and Application of Pseudo-Reservoir Hydraulic Stimulation for Coalbed Methane Indirect Extraction in Horizontal Well: Part 1—Theory

Pseudo-reservoir stimulation in horizontal well is an effective technique for indirectly extracting coalbed methane (CBM) in soft coal from the surrounding rocks (pseudo-reservoir). However, systematic studies of the theory and on-site application of this technique are still lacking, which severely hinders its application. In this paper, the technical principles of pseudo-reservoir stimulation are analyzed firstly, and then, the technical advantages are demonstrated by experimental tests and theoretical analysis. The results show that the pseudo-reservoir generally possesses considerable gas adsorption capacity, with the gas content of 1.56–4.22 cm³/g (avg. 2.51 cm³/g) in Well XC-01, which can be extracted as supplementary resources. The fracability of the pseudo-reservoirs is 0.73–0.92, which is much higher than that of the coal seam, i.e., 0.03–0.43. Meanwhile, the compressive and tensile strength and cohesion of the pseudo-reservoir are higher than those of the coal seam, indicating pseudo-reservoir stimulation is more conducive to forming fracture network, and maintaining wellbore stability and fracture conductivity. The technical feasibility of pseudo-reservoir stimulation is determined by the regional geological conditions, showing simple tectonic conditions and well-developed surrounding rocks with high fracability and mechanical strength but low permeability, water sensitivity and water content are beneficial for the technique application. Note that the fracture conductivity in pseudo-reservoir is more stable and higher than that in coal seam, pseudo-reservoir stimulation is beneficial for the CBM extraction from both hard and soft coal seams. By minimizing the gas diffusion distance, this technique overcomes the technical obstacles to the CBM commercialized production in soft coal.

     

黄河三角洲潮滩高浓度悬浮沉积物的控制因素

黄河口潮滩以其悬浮沉积物浓度高而闻名。但是,目前对其高浓度悬浮沉积物的控制因素和来源的了解尚不清晰。因此,本文基于黄河口潮滩上为期7天的水动力(水深,波高和水流速度)和悬浮沉积物浓度观测,对黄河口潮滩不同海况下悬浮沉积物的控制因素和来源进行分析。数据显示,在大部分时间里,黄河口潮滩处于1级海况下(波高小于0.1m),SSC的变化范围为0.1-3.5 g/L,潮流的沉积物输运为悬浮沉积物的主要来源。但是,当水动力作用增强并且导致海底发生大规模侵蚀时,再悬浮沉积物成为了悬浮沉积物的主要来源,水体中的悬浮沉积物浓度可达到17.3 g/L。我们发现悬浮泥沙通量主要受平流输运的控制,而波浪引起的切应力也可通过影响悬浮泥沙浓度影响悬浮泥沙通量的变化。在观测期间, 1级海况下,流致再悬浮沉积物浓度(RSC)大于波致RSC。与此相反,在2级海况下,波致RSC大于流致RSC,例如,在观测期间出现的单个波浪事件导致6小时内海床被侵蚀了11.8 cm。该研究揭示了河控河流三角洲潮滩附近高悬浮沉积物浓度的不同控制因素,并有助于我们更好地了解三角洲的沉积和侵蚀机制。