Parallelization of the flow-path network model using a particle-set strategy

High-performance simulation of flow dynamics remains a major challenge in the use of physical-based, fully distributed hydrologic models. Parallel computing has been widely used to overcome efficiency limitation by partitioning a basin into sub-basins and executing calculations among multiple processors. However, existing partition-based parallelization strategies are still hampered by the dependency between inter-connected sub-basins. This study proposed a particle-set strategy to parallelize the flow-path network (FPN) model for achieving higher performance in the simulation of flow dynamics. The FPN model replaced the hydrological calculations on sub-basins with the movements of water packages along the upstream and downstream flow paths. Unlike previous partition-based task decomposition approaches, the proposed particle-set strategy decomposes the computational workload by randomly allocating runoff particles to concurrent computing processors. Simulation experiments of the flow routing process were undertaken to validate the developed particle-set FPN model. The outcomes of hourly outlet discharges were compared with field gauged records, and up to 128 computing processors were tested to explore its speedup capability in parallel computing. The experimental results showed that the proposed framework can achieve similar prediction accuracy and parallel efficiency to that of the Triangulated Irregular Network (TIN)-based Real-Time Integrated Basin Simulator (tRIBS).     

大巴山西段高川地体构造变形特征及其意义

勉略缝合带华北与华南大陆于印支期完成拼合的主要拼接带,在中国大陆的形成与演化中占据重要地位。但是,勉略带的东、西延伸,至今没有确定的结论,尤其陕西省勉县以东到湖北随州一带,还没有找到确凿的缝合带的证据。现今一些重要的文章多认为勉略带在勉县以东到达宁陕县两河口之后向南转折,沿着高川岩片的位置顺大巴山弧形构造带向东延伸到湖北随州一带。然而,本文的研究表明,高川岩片是一个独立于大巴山构造带的外来地质体,并称之为高川地体。高川地体是一个由近南北向右行走滑断层与轴向近南北向的走滑剪切褶皱构造组成的右行走滑构造系统,作者认为,它是大巴山冲断推覆构造向南推覆过程中,被从原勉略缝合带中挤过来的一片,它仅仅是被挟持在大巴山冲断—推覆构造带与大巴山前陆构造带之间的地壳浅层地质体,高川地体现在的位置不能代表勉略带向东的延伸。因此,大巴山弧形构造带也不是中国南北大陆最终碰撞拼贴的位置     

The Cauvery Shear Zone, Southern Granulite Terrain, India: A crustal-scale flower structure

The Cauvery Shear Zone (CSZ) is a crustal-scale shear system within the Southern Granulite Terrain along the southern margin of the Archaean Dharwar craton. Structural interpretation of satellite data and field observations reveal four major shear zones within the CSZ system. They show dextral shear kinematics synchronous with a major Neoproterozoic tectono-metamorphic event (D2) associated with intracrustal melting and migmatisation. The disposition, geometry and contemporaneity of shear fabrics of the CSZ system are modelled in terms of a crustal-scale flower structure akin to transpressional and collisional orogens. In the light of recent seismic evidence for a displaced Moho structure and a mid- to lower-crustal low velocity zone, the flower structure across the CSZ may extend to mantle depths.     

Neoproterozoic alkaline magmatism at Sivamalai, southern India

The Sivamalai alkaline complex lies at the southern margin of the Cauvery Shear System that separates the Archaean and Proterozoic domains of the Southern Granulite Terrain in India. U–Pb TIMS dating of zircon from a pegmatitic syenite sample in the complex yields a concordant age of 590.2 ± 1.3 (2σ) Ma which is interpreted to date the intrusion of the alkaline rocks. A lower concordia intercept at 168 ± 210 Ma defined by two grains with high common lead may indicate post-magmatic disturbances due to recrystallisation which is also evident in the CL images of the zircons. EPMA dating of monazite from a post-kinematic pegmatite which intrudes the crystalline basement hosting the alkaline rocks yields an age of 478 ± 29 (2σ) Ma and provides a lower bracket for the main phase of tectonism in this part of the Southern Granulite Terrain. The Pan-African high-grade metamorphism and ductile deformation has thus most likely affected the alkaline rocks. This is supported by the presence of a metamorphic foliation and extensive recrystallisation textures seen in the rocks. The major and trace element concentrations measured on selected samples reveals the presence of both enriched and depleted rock types. The enriched group includes ferrosyenite and nepheline syenite while the depleted group has only nepheline syenites. The trace element depletion of some nepheline syenites is interpreted to be a result of fractional crystallization involving the removal of accessory phases like zircon, titanite, apatite and allanite.     

基于DEM的地形简化方法对比分析

地形简化作为一门重要的数据压缩技术已广泛应用于DEM。在大量简化算法中，地形简化指标作为地形简化的核心环节，其好坏直接关系到地形简化的好坏。本文对基于局部误差、曲率和法向量的五个地形简化指标进行了分析评价，用离散的高斯合成曲面来模拟真实DEM，以解析得到的高斯曲率作为地形简化指标“真值”，对比研究了在离散高斯曲面上得到的五个简化指标与解析所得“真值”，通过对各个指标“保特征性”可信度的分析，获得了对这五个指标的整体评价，最后，实例验证了本文结论的正确性。     

次网格地形坡度坡向参数化及其对区域气候模拟的影响

随着数值模式水平分辨率的提高，模式下垫面特征的描述更加仔细，针对东亚地区复杂的地形和植被特征，发展适合非均匀下垫面的地表通量参数化方案，对改进数值模式和刻画高原附近地区复杂地形动力和热力。效应的能力非常必要。本文通过计算次网格地形坡度、坡向参数及其对到达地面短波辐射通量的影响，提出次网格地形热力效应的参数化方案，改进数值模式中复杂地形区域地面热量平衡的计算。利用p—σ区域气候模式的数值试验结果表明，次网格地形热力效应参数化方案的引入，对东亚地区夏季气候尤其是降水的模拟有明显的改进。     

工程场地的特征与工程地质分区

工程场地与城市在空间尺度上相去甚远 ,但工程场地所具备的与环境行为相近的共性 ,使其属性分析可以推广应用到城市建设所面对的整个工程地质环境。从这一意义上说 ,工程场地是整个城市宏观工程地质环境的微观单元 ,众多微观单元的组合构成了环境的宏观总体。为此 ,工程场地的三大属性特性、适宜性、稳定性 ,可以作为城市工程地质环境分析中分析方法的基础。从工程场地分析推广到城市工程地质环境分析 ,还将有助于保证城市工程地质环境分析的定量化水平。     

A bilinear approximation of the surface relief in terrain correction computations

A new method is presented for the computation of the gravitational attraction of topographic masses when their height information is given on a regular grid. It is shown that the representation of the terrain relief by means of a bilinear surface not only offers a serious alternative to the polyhedra modeling, but also approaches even more smoothly the continuous reality. Inserting a bilinear approximation into the known scheme of deriving closed analytical expressions for the potential and its first-order derivatives for an arbitrarily shaped polyhedron leads to a one-dimensional integration with – apparently – no analytical solution. However, due to the high degree of smoothness of the integrand function, the numerical computation of this integral is very efficient. Numerical tests using synthetic data and a densely sampled digital terrain model in the Bavarian Alps prove that the new method is comparable to or even faster than a terrain modeling using polyhedra.     

2002年6～7月安阳市连续性高温天气过程分析

利用1970～2000年安阳市高温天气资料和实时资料，分析了安阳市2000年6～7月两次区域性连续高温天气的天气形势、地面要素特征、地形影响及高温天气变化周期，揭示了高温天气的成因，找出了预报着眼点。     

机载扫描激光地面测绘系统分析

本文根据机载扫描激光地面测绘系统的功能和要求，分析了它的工作原理，概括出该系统中扫描激光测距的特点，介绍了一种最新的机载扫描激光地面测绘系统，最后提出了几个需要继续研究的问题