Boundary-fitted grid in landscape modeling

Landscape modeling requires the delineation of system boundaries and interior features. Quite often, these components are complex and difficult to accurately represent. A rectangular grid is used to represent the study and adjacent non-study areas in most cases. When the non-study area occupies a large portion of the grid, computer memory is wasted, and computational time increases. An elliptical grid generator for non-orthogonal curvilinear coordinates is used to generate a boundary-fitted grid for a landscape model. In a boundary-fitted grid coordinate system, one coordinate axis follows the landscape domain boundary and is non-orthogonal to the second axis. The boundary-fitted grid uses elliptic partial differential equations to distribute grid points inside the landscape domain. Although the boundary-fitted grid follows the domain boundary, the grid pattern and point allocation remain structured. Thus, a landscape model can use a boundary-fitted grid without changing the model’s data structure or the computational scheme. In this study, a boundary-fitted grid and a raster-based grid were applied to the Everglades Landscape Fire Model. Use of the boundary-fitted grid decreased model simulation time by about one fifth and computer storage by 58% relative to the raster-based grid. Also, the linear characteristics of interior geographical features such as rivers and airboat trails were preserved by the boundary-fitted grid, but not by the raster-based grid. This preservation provided a more reasonable base map for simulating ecological processes, such as fire across heterogenous landscapes.     

电导法测定林木种子活力的研究

本文研究了林木种子电导法测定条件和测定电导率或相对电导率,通过回归分析建立电导率或相对电导率与种子活力指数的相关方程,找出了电导法测定林木种子活力的方法。     

三阶时滞泛函微分方程解的渐近性

本文讨论一类三阶时滞泛函微分方程解的渐近性质,给出了若干解的有界性及解趋于零的判定准则.     

福建省林木良种繁育概况及今后工作设想

本文介绍了福建省林木种质资源的收集保存、研究利用，优良家系选育，树种内种源研究，高世代种子园研究，乡土树种栽培驯化，外来树种引种，提高种子园种子产量所采取的措施，无性繁殖技术等林木良种繁育概况；并就林木育种工作存在的问题及今后工作设想提出建设性意见。     

角形区域的Teichmuler极值映照

采用二次微分的方法，得到了角形区域Ω１的Ａｆｆｉｎｅ变换关于其边界值不是极值映照．并明确给出在边界同伦下唯一极值的Ｔｅｉｃｈｍｕｌｅｒ映照．     

二阶拟线性椭圓型Euler方程组解的Pohozaev型恒等式及其应用

本文对于二阶椭圆型Euler方程组 -∑D_αF_(q_α~i)(x,u,Du)+F_(ui)(x,u,Du)=0得到了一些积分恒等式,利用这些恒等式证明了某些方程组非平凡解的不存在性。     

通用开放式绘图仪接口软件设计与实现

本文针对TANGO软件所支持的图形输出设备中不包括CALCOMP系列绘图仪的问题,设计了TANGO图形文件与CALCOMP系列绘图的接口软件.由此阐述了一种通用图形描述语言及开放式绘图仪接口软件的设计思想与技术实现.     

一类时滞微分系统有界解的收敛性

研究了一类时滞微分系统解的渐近性态．在一些比已有文献通常附加的局部李普希兹条件更弱的条件下，证明了此系统的每个有界解趋于某平衡态．我们的结果推广了已有的一些结论．