Application of Entropy Method to Quantify Future Ecological Flow in the Yellow River Basin

Due to both anthropogenic and climate change impacts, precipitation and runoff in the Yellow River basin have decreased in the past 50 years, leading to more pressure in sustaining human beings and ecosystem needs. It is essential to evaluate the flow condition in the Yellow River basin and see whether it may satisfy its ecological flow in the future. Therefore, this study applied an entropy-based method to calculate the flow duration curves from both observed and simulated data to evaluate the impact of climate change on ecological flow in the Yellow River basin. The simulated FDCs from H08 and DBH models show good agreement with each other and fit observation well. Results show that the decadal FDC at each station is generally predicted to be higher or stay in the higher range under both RCP 2.6 and 8.5 scenarios, suggesting an increase in water amount in the future. It is found that the high flows increase much faster than the low flows, resulting in larger slopes than the references ones, which is due to the larger entropy and M values in the future. At most of the stations, the future values of Q95 and Q90 will safely exceed the threshold. It is found that at the Lanzhou, Wubao, Longmen, and Huayuankou stations, there will be no or little threat to future ecological flow. Still, at the Toudaoguai and Sanmanxia stations, the ecological requirement is not always satisfied. The water stress at the Tangnaihai station from the upper stream of the Yellow River may be threatened in the future.     

浙江新昌硅化木赋存地层岩石学与古生态环境研究

在新昌早白垩世盆地中存在丰富的硅化木，它们是重要而又典型的古植物地质遗迹，新昌硅化木赋存的地层为早白垩世馆头组，其岩石类型包括砾岩、岩屑长石砂岩／长石岩屑砂岩、粘土岩，还有少量的礁灰岩和泥灰岩。岩石学研究表明，它们形成于干燥的快速堆积的山间盆地，属河湖相沉积。新昌硅化木为南洋杉型木，生活在热带－亚热带的气候条件。结合硅化木特征与地层岩石学研究，探讨了新昌硅化木形成的古生态环境。     

陇西盆地段黄河发育时代问题的新认识

根据陇西盆地的两个次级盆地阶地即兰州盆地最高级黄河阶地和陇西盆地黄河一级支流大夏河最高级阶地的磁性地层学研究表明,二者的形成时代大致相同,约为１．６ＭａＢ．Ｐ．左右,也即此时黄河才开始在这两个盆地中出现．这一结果修订了黄河在陇西盆地中出现的最早时间．完整的黄河阶地系列实际上是第四纪期间青藏高原阶段性隆升的忠实记录．     

Wada分形吸引域边界上的混沌鞍

应用广义胞映射图论（Generalized Cell Mapping Digraph)方法，数值地研究Thompson的逃逸方程在最佳逃逸点附近的分岔。发现了嵌入在Wada分形吸引域边界上的混沌鞍，混沌鞍是状态空间不稳定（非吸引）的混沌不变集合。Wada分形吸引域边界是具有Wada性质的边界，即吸引域边界上的任意点也同时是至少两个其它吸引域的边界点，称为Wada域边界。我们证明Wada域边界上的混沌鞍导致局部鞍结分岔具有全局不确定性结局，研究了Wada域边界上混沌鞍的形成与演化，证明最终的逃逸分岔是混沌吸引子碰撞混沌鞍的边界激变。     

Deep Learning Unravels a Dynamic Hierarchy While Empowering Molecular Dynamics Simulations

Molecular dynamics (MD) provide predictive understanding of the behavior of condensed matter. However, its true potential remains largely untested because relevant timescales are often inaccessible, limited portions of conformation space get sampled, and infrequent events are usually irreproducible. A culprit is the huge informational burden required to iterate integration steps. To address the problem, deep learning is applied to encode the dynamics into a shorthand embodiment retaining only essential topological features of the vector field that steers MD integration. The flow is simplified via an equivalence relation that identifies conformations within basins of attraction in potential energy and encodes the dynamics onto a modulo-basin “quotient space” where fast motions are averaged out. The quotient space projection enables coverage of realistic timescales while unraveling the underlying dynamic hierarchy. Deep learning is exploited to propagate the simplified trajectory beyond MD-accessible timescales and to reconstruct it at atomistic level. As shown, the quotient-encoding-propagating-decoding scheme generates within a few hours protein folding pathways with experimentally verified outcomes. By contrast, MD computations covering comparable timespans would take over a hundred days on special-purpose supercomputers. Thus, quotient space constitutes a model for hierarchical understanding of MD simulation while enabling access to realistic timescales.     

Nanoscale simulation of Na-Montmorillonite hydrate under basin conditions,application of CLAYFF force field in parallel GCMC

The swelling of Na-Montmorillonite is simulated by Monte Carlo molecular simulations in NP_zzT and μVT ensembles, in two sedimentary basin conditions of 423 K at 750 atm and 483 K at 1050 atm and by using the CLAYFF force field [J. Phys. Chem. B 108, 1255–1266 (2004)]. The CLAYFF force field predicts a one, two-layer stable hydrate under 423 K at 750 atm and a one-layer stable hydrate under 483 K at 1050 atm with the stable basal spacings of 12.54 and 12.44 Å. The adsorbed water molecules are 45.22 and 41.92 per clay layer, with water densities of 0.28 and 0.26 g/cm³ and total energy of 2.11 and 3.65 kcal/mol of water. The predicted structure of Na-Montmorillonite are consistent with those reported in literature for high temperature and pressure conditions, however the results did not indicate a one-layer hydrate as the stable phase under basin conditions of 423 K at 750 atm [Clays Clay Miner. 34, 385 (1986)]. This work allows addressing the issue of the effect of basin condition on the structure of Na-Montmorillonite hydrate.     

和田河流域资源开发利用与可持续发展

主要分析了田河流域的水，土资源概况及存在的问题，在研究流域人口，经济，资源，环境诸因素之间相互关系的基础上，用系统动力学模型动态定量模拟了流域人口，资源和经济发展的规模，并为流域今后的可持续发展提供了原则与对策。     

南海深海盆磁异常分析及其动力学意义

在南海深海盆分布着大范围规律性很强的条带状磁异常。通过插值切割法对其中东部次海盆和西南次海盆的磁异常进行分析。发现南海深海盆区的磁力异常具有叠加性，西南次海盆主要受约5km以上的浅部磁源的影响，表现为NE－SW向展布，5km以下磁异常的展布开始变得模糊，强度也变弱；而东部次海盆不仅受5km以上的EW向浅部磁源的影响，同时深部磁源也起着很大的作用，在方向上也表现为EW向，但是强度随着深度而减弱。由此提出了两海盆地磁异常差异所反映的地球动力学过程，认为西南次海盆的磁源是通过大陆边缘裂谷作用过程形成；而东部次海盆深部和浅部磁异常的磁源具有同时性和相同形成机理，是通过海底扩张作用的方式形成的。在结合其它研究结果的基础上，探讨了南海西南次海盆和东部次海盆的动力学机制和演化历史。     

Wada bifurcations and partially Wada basin boundaries in a two-dimensional cubic map

The partially Wada basin boundaries are referred to the coexistence of Wada points and non-Wada points in the same basin boundary. We demonstrate two types of Wada bifurcations and analyze the transitions from totally Wada basins to partially Wada basins and from totally Wada basins to totally Wada basins in a two-dimensional cubic map. We describe some numerical experiments giving the evidence of partially Wada basin boundaries. Our results show that the basin cell erosion and the basin cell bifurcation can induce the Wada basin boundary metamorphoses.     

受迫Holmes-Duffing系统安全域分形及时滞速度反馈控制

以受迫Holmes-Duffing系统为研究对象, 对系统施加时滞速度反馈控制, 研究周期激励引起的系统安全域的分形侵蚀及时滞速度反馈对分形侵蚀安全盆的控制作用. 利用Melnikov函数法给出时滞受控系统的安全盆的边界分形条件. 再以时滞量为变参数, 运用四阶Runge-Kutta方法和点映射方法数值研究了时滞对受控系统安全盆的影响规律. 结果表明在弱反馈下, 时滞量的增大能够提高安全盆边界分形的阈值, 从而抑制安全盆的分形侵蚀. 说明时滞速度反馈能够有效抑制系统的安全盆侵蚀.