Modeling atmospheric chemistry and transport with dynamic adaptive resolution

We discuss an adaptive resolution system for modeling regional air pollution based on the chemical transport model STEM. The grid adaptivity is implemented using the generic adaptive mesh refinement tool Paramesh, which enables the grid management operations while harnessing the power of parallel computers. The computational algorithm is based on a decomposition of the domain, with the solution in different subdomains being computed with different spatial resolutions. Various refinement criteria that adaptively control the fine grid placement are analyzed to maximize the solution accuracy while maintaining an acceptable computational cost. Numerical experiments in a large-scale parallel setting (~0.5 billion variables) confirm that adaptive resolution, based on a well-chosen refinement criterion, leads to the decrease in spatial error with an acceptable increase in computational time. Fully dynamic grid adaptivity for air quality models is relatively new. We extend previous work on chemical and transport modeling by using dynamically adaptive grid resolution. Advantages and shortcomings of the present approach are also discussed.     

Volume rendering visualization of 3D spherical mantle convection with an unstructured mesh

We propose a new approach to utilize the algorithm of hardware-assisted visibility sorting (HAVS) in the 3D volume rendering of spherical mantle convection simulation results over unstructured grid configurations. We will also share our experience in using three different spherical convection codes and then taking full advantages of the enhanced efficiency of visualization techniques, which are based on the HAVS techniques and related transfer functions. The transfer function is a powerful tool designed specifically for editing and exploring large-scale datasets coming from numerical computation for a given environmental setting, and generates hierarchical data structures, which will be used in the future for fast access of GPU visualization facilities. This method will meet the coming urgent needs of real-time visualization of 3D mantle convection, by avoiding the demands of huge amount of I/O space and intensive network traffic over distributed parallel terascale or petascale architecture.     

应用CHIMEHERB人工皮覆盖网状植皮创面

应用CHIMEHERB人工皮覆盖烧伤切(削)痂后自体网状植皮创面30例、44个创面,每例平均应用体表面积为5.22％,网状皮扩展比例为1:3.结果有明显积液者5个创面(11.36);感染3个创面(6.82％);需要补植皮创面4个(9.1％).人工皮具有良好的透气性和透湿性,可给创面造成无菌的内环境,未观察到过敏反应和排异现象,贮藏不需特殊设备,使用方便,具有人工皮所要求的基本特性,作为自体网状植皮表层覆盖物,可取得良好效果,值得临床推广应用.     

尼罗罗非鱼对两种网目定置网片反应特性的比较

本文就尼罗罗非鱼对两种网目(12.6和8.4cm)定置网片的反应特性进行了比较研究。结果表明:在两网片邻近区域内的分布尾次数较中间区域为少;随着时间推移,其分布重心有移向大网目网片一侧的倾向。此外,罗非鱼对两种网目网片的趋网、碰网、穿网尾次数及趋网、碰网、穿网时刻也有一定的差异。     

Interactions between nonlinear water waves and non-wall-sided 3D structures

Interactions between water waves and non-wall-sided cylinders are analyzed based on velocity potential theory with fully nonlinear boundary conditions on the free surface and the body surface. The finite element method (FEM) is adopted together with a 3D mesh generated through an extension of a 2D Delaunay grid on a horizontal plane along the depth. The linear matrix equation for the velocity potential is constructed by imposing the governing equation and boundary conditions through the Galerkin method and is solved through an iterative method. By imposing the gradient of the potential equal to the velocity, the Galerkin method is used again to obtain the velocity field in the fluid domain. Simulations are made for bottom mounted and truncated cylinders with flare in a numerical tank. Periodic waves and wave groups are generated by a piston type wave maker mounted on one end of the tank. Results are obtained for forces, wave profiles and wave runups. Further simulations are made for a cylinder with flare subjected to forced motion in otherwise still open water. Results are provided for surge and heave motion in different amplitudes, and for a body moving in a circular path in the horizontal plane. Comparisons are made in several cases with the results obtained from the second order solution in the time domain.     

引入导航网格的室内路径规划算法

随着社会、经济的不断发展进步,室内导航定位越来越重要,其导航定位精度、准确性倍受业界关注,而路径规划是该研究方向的重要组成部分。针对传统的基于节点的拓扑模型无法较好解决室内空间"路网"的模糊性问题,该文分析了室内外导航定位的差异,并对传统路径规划算法的局限性进行了分析,提出将基于Delaunay三角剖分导航网格的A*算法应用于室内导航路径规划中。通过算例验证了该方法的有效性,具有较好的实用价值。     

MapGIS和Section整合绘制边界约束下的属性等值线的方法——以堆积铝土矿为例

矿体作为一种特殊的地质体,其厚度等值线应受限于边界之内,这种约束特征用常规的计算机等值线绘制无法体现,为了表示边界线的约束特征,通过MapGIS和Section整合,可对边界线进行处理,提取子图元,赋予子图元边界线特有的相关属性,在属性结构相同的条件下使之与探矿工程子图元融合,然后采用Krining泛克立格法网格化模型绘制厚度等值线,形成的等值线均受限于边界线范围之内,真实的反映了矿体属性的本质,这种方法还可以绘制品位等其它属性等值线。作为约束条件的属性值必须是相同的,一般为零厚度、边界品位,边界含矿率等。矿体边界的属性值无法获得一致时,可通过外推边界的方法令其一致,具备此条件后即可进行属性等值线绘制。该方法实用、简捷。     

汉江河谷旬阳段区域滑坡规律及斜坡不稳定性预测

基于斜坡工程地质测绘和实验室分析,文中讨论了研究地段区域滑坡规律。引入信息量及二态变量回归分析建立了斜坡不稳定性两种预测模型。文章重点论证和提出了影响因素筛选、多边形网格单元划分的原则及预测精度评价的原理方法。编制了斜坡不稳定性分区图,检验表明其预测精度高;两预测分区图对比表明有很好的一致性。