Raster-based neighborhood visibility correlative least-cost path analysis

基于可视性的最优路径分析是地形可视性分析中的一项基本功能，属于空间决策支持的范畴，在理论研究和实际应用两方面都具有重要的意义。在传统基于可视性的最优路径分析中，影响通行能力的可视性代价信息为相互独立的0维数值。然而，用0维无关的代价来表示三维地形上点的可视性信息是不全面的，有必要采用一维或更高维的代价表达方式。本文用二维视域来描述三维可视性信息，考虑到邻近点的二维视域相互重叠造成的可视性相关性对最优路径搜索的影响，提出基于栅格邻域可视性相关的最优路径问题。本文对该问题的分类和求解进行了详细的分析和讨论。 本文的创新性工作如下： (1) 改进了传统基于可视性的最优路径搜索问题。对于存在的“真实性”不足之处，考虑地形特征如土地覆盖或土地利用，障碍物及坡度等对通行能力的影响，并将这些影响和可视性信息一起添加到传统的基于可视性的最优路径搜索过程中，所得结果更加符合实际情况。 (2) 提出并求解了一类基于栅格邻域可视性相关的最优路径问题：基于平均视距最小/最大的可视覆盖路径问题。在可视覆盖最优和路径长度最优两个约束条件下，用代表路径平均视野的开阔程度的平均视距来衡量最优可视覆盖路径问题的最优性。通过对平均视距及该类问题目标函数进行建模分析以及预先计算并存储整个地形上的视域信息，用基于视域融合操作的模拟退火算法实现了该类问题的求解。 (3) 提出并求解了一类基于栅格邻域可视性相关的最优路径问题：最小可视覆盖路径问题。在只考虑可视覆盖最优的约束条件下，用代表路径视野开阔程度即“可视覆盖面积”来衡量最优可视覆盖路径问题的最优性。通过对问题目标函数建模及求解方法的比较分析，用Dijkstra算法实现了该类问题的求解。 最后，本文比较了基于栅格邻域可视性相关的和传统基于可视性无关的最不可视路径问题得到的结果。通过对新方法和传统方法应用于求解走私路径所得结果的定量和定性的分析与对比，得出新方法比传统方法准确的结论。Least-cost path analysis based on visibility is a basic function in terrain visibility analysis, which belongs to the field of space decision making and has significant meaning both in theory and practice. In traditional least-cost path analysis the visibility information used to evaluate the traveling ability is just zero-dimensional and independent in the neighborhood. However, it is not comprehensive to use the irrelative zero-dimensional numerical values to represent the visibility information in three-dimensional terrain; the higher dimensional information should be used. Two-dimensional viewsheds are used in this dissertation to describe three-dimensional visibility; considering the visibility correlation caused by the overlapped part of the adjacent points’ viewsheds, the raster-based neighborhood visibility correlative least-cost path problems is proposed. In this dissertation the classification and resolvent of these problems are analyzed and discussed in detail. The main original work in this dissertation includes: (1) The conventional least-cost path problems based on visibility analysis are improved. The insufficiency of reality is improved by considering the influence of terrain features such as land cover, obstacles and slopes to the moving ability. By adding these influences to the least-cost path problems based on visibility analysis, the resultant paths are more practical. (2) Optimal visual coverage path problems based on average horizon which are sorts of raster-based neighborhood visibility correlative least-cost path problems are proposed and implemented. Under the two optimality constraints of visual coverage and path length, the concept of “average horizon” which represents the average wide extent of visual field of the path is advanced to analyze and model optimal visual coverage path problems. With pre-computed and stored viewshed information the problems are resolved by utilizing simulated annealing algorithm based on the operation of viewshed amalgamation. (3) The min visual coverage path problems which are sorts of raster-based neighborhood visibility correlative least-cost path problems are proposed and implemented. Under the optimality constraint of visual coverage, the area of the path visual coverage which represents the wide extent of visual field of the path is used to analyze and model min visual coverage path problems. After the objective function modeling and comparative analysis of the resolving methods, the problems are resolved using Dijkstra algorithm. Finally, the new advanced raster-based neighborhood visibility correlative and the traditional visibility irrelative least-cost path problems are compared by the study case “smugglers’ paths”. The experimental results which are got from the new method and the traditional method show that the new method produces more accurate results than the traditional one

“下行效应”与“上行效应”对东湖浮游甲壳动物群落的影响

本文通过东湖与后湖浮游甲壳动物群落的长期变化、东湖浮游甲壳动物的空间分布格局、营养水平对东湖浮游甲壳动物群落体长的影响及围隔实验这四方面的研究揭示了东湖滤食性鱼类的捕食(下行效应)与富营养化(上行效应)对东湖浮游甲壳动物群落的影响。在1989-1998年期间，东湖I、II站近邻剑水蚤和微型裸腹？的生物量大幅上升，这两个种类优势度的上升与水体富营养化关系密切。80年代至90年代哲水蚤与剑水蚤生物量之比的明显下降与哲水蚤较低的内禀增长力有关。从60年代至199 7-1 998年，鱼类捕食压力的上升导致后湖枝角类的优势种由隆线？-亚种演替为逃避能力较强的短尾秀体？，后湖剑水蚤密度的上升导致右突新镖水蚤、长江新镖水蚤和特异荡镖水蚤的优势明显下降。浮游甲壳动物群落结构在东湖I、II、I I I、IV站间具有显著差异。微型裸腹？与近邻剑水蚤的优势度随水体营养水平的上升而上升，而大型枝角类(盔型透明？与透明薄皮？)的优势度随水体中鱼类捕食压力的上升而下降，哲水蚤相对于剑水蚤的优势趋向于随鱼类捕食压力的上升而下降。郭郑湖区浮游甲壳动物的生物量与水体营养水平间正的相关性不明显，而微型裸腹？、短尾秀体？和近邻剑水蚤在郭郑湖区的分布与鱼类捕食压力关系密切。从80年代至90年代，东湖浮游甲壳动物群落的平均体长呈现明显的上升趋势。浮游甲壳动物群落体长的上升由优势种体长的上升所导致，其中微型裸腹滔与近邻剑水蚤体长的上升与水体营养水平的上升关系密切。通过围隔实验发现，滤食性鱼类的捕食导致逃避能力强的种类(如哲水蚤)及世代时间短的种类(主要是小型枝角类)的优势增强。在鱼类捕食压力较高的水体中哲水蚤的生物量较低，因为无节幼体较容易被鱼类所捕获。通过对“下行效应”与“上行效应”对浮游甲壳动物群落影响机理的鲁敏：“上行效应”与“下行效应”对东湖浮游游甲壳动物群落的影响机理的深入研究，表明滤食性鱼类的捕食与水体的营养水平均为决定东湖浮游甲壳动物群落结构的重要因子

武汉东湖后湖区浮游甲壳动物群落结构的研究

武汉东湖后湖湖区浮游甲壳动物群落结构从 6 0年代至 90年代发生了十分显著的变化。浮游甲壳动物的物种丰度下降非常明显 ,枝角类的种类数从 6 0年代的 47种下降至 90年代的 1 7种 ,桡足类的种类数由 6 0年代的 1 4种下降为 90年代的 9种。 6 0年代枝角类的优势种隆线一亚种在 90年代被短尾秀体所取代 ,6 0年代的两种优势哲水蚤——长江新镖水蚤与特异荡镖水蚤的优势在 90年代消失 ,而 6 0年代很少的一种剑水蚤——台湾温剑水蚤在90年代跃升为优势种。随着滤食性鱼类密度的上升

武汉东湖不同湖区浮游甲壳动物群落结构的比较

对武汉东湖 4个不同营养水平和不同滤食性鱼类密度的湖区 1 993— 1 998年期间的浮游甲壳动物群落结构进行了比较研究。结果表明 ,营养水平及滤食性鱼类的密度以Ⅰ、Ⅱ、Ⅲ、Ⅳ站的次序依次下降 ;各站间浮游甲壳动物总生物量及各类群 (枝角类、剑水蚤和哲水蚤 )的生物量差异较大 ,并且哲水蚤相对于剑水蚤的优势度以Ⅰ、Ⅱ、Ⅲ、Ⅳ站的次序上升。浮游甲壳动物优势种结构在Ⅰ、Ⅱ站与Ⅲ、Ⅳ站间的差异尤为明显 :近邻剑水蚤与微型裸腹生物量在营养水平及鱼类生物量高的Ⅰ、Ⅱ站显著较高 ,而盔型透明的生物量在营养水平

The Toxicity of Metal-Mixed Solution on OlFactory of Fish(Tilapia sp.)

鱼类的嗅觉是一种重要的距离感受器,它能灵敏地感受周围环境的微妙变化。在鱼的摄食、集群、防御、繁殖、迁移等活动中发挥着重要的作用,是其赖以生存的重要感受器之一,也是人类不可多得的一种灵敏的生物学监测指标[柴敏娟等,1996]。水域中存在的重金属污染物往往不是单一种的,而是繁多的,这绪多的污染物对鱼类生存有没有影响,怎样影响鱼的生理活动？这方面国内研究不多。本文选择我省淡水渔业养殖常用品种罗非鱼(TIlAPIASP.)为实验对象,用电生理方法,研究3种二价金属离子(Cu--(2+)、zn--(2+)、CA--(2+))相互混合对鱼类嗅电图(ElECTrO-OlfACTOgrAM,下简称EOg)的影响,并探讨其机制。The toxicity of various metal-mixed solutions has been studied on the Fosh olFactory receptors by electrophysiology method,and the mechaniam of toxicity has been discussed.The results indicate that: (1 )Under the condition of the epually Ca2 + concentration,the eFFects of inhibiting EOG response depend on the metallic ion concentrations of mixed solutions which respectively contain(Cu2+ +Ca2+) , (Zn2+ +Ca2+)and(Cu2++Zn2++ Ca2+ ).The higher the concentrations,the more obvious the inhibiting eFFects(2)Among the various metal-mixed solutions,the inhibiting eFFects of the solutions which contain Ca2+ are less than those of the solutions which contains no Ca2+.Especially, the eFFective LC50Values of the both ionic solutions which contain (Cu2+ + Ca2+) or (Zn2+ + Ca2+ ) are much higher than those of solutions which contain only Cu2+ or Zn2+.This Fact shows that the toxicity of metal-mixed solutions which contain Ca2+ are obviously less than that of solutions which contain no Ca2+.(3)There is an antagonistic eFFect between Ca2+ and Cu2+ ,or Ca2+ and Zn2+ ,or Ca2+ and (Cu2++Zn2+) , which suggests that Ca2+ has a detoxiFy action.(4)The toxicity of(Cu2+ +Zn2+ )mixed solution is more than that of solution of solution which contains only Cu2+ or Zn2+.The interaction brtween Cu2+ and Zn2+ is syn-ergistic eFFect.福建省自然科学基

least-cost path analysis in raster terrains

将栅格地形根据不同的邻域结构形成稀疏栅格网络和稠密栅格网络,分析了稀疏网络中最优路径问题的建模和基于Dijkstra算法的求解方法,以及稠密网络中最优路径问题的建模和基于模拟退火算法的求解方法。比较了这两种方法求解结果的准确性和效率的差异,发现基于稀疏网络的Dijkstra算法更适合于栅格地形的最优路径问题的求解