富勒烯C 4 0的密度泛函理论研究

采用密度泛函理论B3LYP/6-31+G*对富勒烯C40的各个异构体进行了计算研究,对它们的几何构型、相对能量、HOMO-LUMO能量间隙进行比较分析.结果显示,异构体遵循五元环比邻惩罚规则,稳定性高的异构体通常具有更高的正球形,最稳定的异构体是含有10个B55键的C40-38.     

Spatial optimization by simulated annealing and linear programming

Forest management planning comprises selection among treatment alternatives in management units. A traditional linear programming (LP) approach may effectively account for a profit maximization objective combined with sustainability constraints, e.g. on the temporal distribution of harvest volume flows, cash‐flow, and net present value development, but it fails to account for spatial constraints, especially those associated with final felling. By applying a simulated annealing adjacency model based on net present value maximization and combined with an LP consequence computation model, it is possible to delineate optimal strategies of final felling scheduling. Evaluation is made of the trade‐off between (1) the incremental cost (determined by use of the LP model) of an optimal adjacency model solution, and (2) the potential damage cost resulting from adjacency characteristics such as windthrow and bark injuries. The decision support system may contribute significantly to reduce damage costs and may improve the reliability of forest management planning.     

基于森林空间收获问题的模拟退火算法邻域搜索技术比较

邻域搜索是当前提高启发式算法求解效率的核心技术之一,然而近期关于该搜索策略的性能却产生了较大争议。模拟退火算法作为一种典型的启发式算法,已广泛应用于一系列的林业规划问题。为此,本研究以模拟退火算法为例,系统评估2种不同邻域搜索技术在森林空间收获安排问题中的应用效果。规划模型以50年规划周期(10个规划分期)内的最大化木材收获为目标函数,以蓄积均衡收获、蓄积期末存量、单位限制模型和绿量限制等为主要约束条件。测试方法以模拟退火算法为原型,以每次优化过程中随机选择的小班数量为标准,共包括1-邻域和2-邻域2种不同的搜索技术。模拟规划数据由3个假设的栅格数据集组成,其共产生了3293个(林分Ⅰ)、29536个(林分Ⅱ)和81625个(林分Ⅲ)0-1型决策变量。研究结果表明:模拟退火算法2-邻域搜索技术能够提高各规划问题的最大目标函数值;但当规划问题的决策变量数(或小班数量)较大时(即林分数量≥3600),单纯增加邻域范围并不能提高规划问题的平均目标函数值。因此,鉴于模拟退火算法的优化结果对规划问题具有较高的敏感性,因此森林经营决策人员应慎重选择模拟退火算法邻域搜索作为相关规划问题的优化求解技术。      

An aggregation index (AI) to quantify spatial patterns of landscapes

There is often need to measure aggregation levels of spatial patterns within a single map class in landscape ecological studies. The contagion index (CI), shape index (SI), and probability of adjacency of the same class (Qi), all have certain limits when measuring aggregation of spatial patterns. We have developed an aggregation index (AI) that is class specific and independent of landscape composition. AI assumes that a class with the highest level of aggregation (AI =1) is comprised of pixels sharing the most possible edges. A class whose pixels share no edges (completely disaggregated) has the lowest level of aggregation (AI =0). AI is similar to SI and Qi, but it calculates aggregation more precisely than the latter two. We have evaluated the performance of AI under varied levels of (1) aggregation, (2) number of patches, (3) spatial resolutions, and (4) real species distribution maps at various spatial scales. AI was able to produce reasonable results under all these circumstances. Since it is class specific, it is more precise than CI, which measures overall landscape aggregation. Thus, AI provides a quantitative basis to correlate the spatial pattern of a class with a specific process. Since AI is a ratio variable, map units do not affect the calculation. It can be compared between classes from the same or different landscapes, or even the same classes from the same landscape under different resolutions.     

Shortest Path Algorithm for Hypergraphs

Based on strong isomorphism for hypergraphs,vertex isomorphism is defined,which preserves hyper-adjacency property between vertices.Adjacency-matrixes of hypergraphs and weighted hypergraphs are presented respectively.The Floyd's algorithm is generalized to finding shortest paths between all pairs of vertices in a hypergraph.The publication provides an instance which verifies the practicability of the modified algorithm and whose results have been compared with those of the method given by LI Chun-ming.Time complexity of the presented algorithm is obtained to be(O(n~3)).     

古英语词序的句法研究

本文从历史比较语言学的角度研究了句法学领域少有探讨的古英语(Old English,OE)的句法。在简要分析了古英语的屈折性和句法特征之后,从跨语言的角度发现古英语句法和现代斯拉夫语族的俄语具有某些句法上的相似性,并找到存在差异的原因。用生成句法学的方法探讨了古英语词序的两个重要问题,一是动词和宾语的变异,即表层结构OV和VO词序的交替,提出了统一潜在的无标记VO词序。由于古英语的名词屈折特征强,必须在拼读之前进行核查,提到Spec-AgrOP以满足进入逻辑式的“完全解释原则”。这就形成了拼读后语音表达式     

环状给水管网关联矩阵的建立

利用AutoCAD VBA开发技术,定义环状给水管网的管段实体扩展数据结构,借助遍历查询手段构建管段与节点关系的峰矩阵,转换峰矩阵为邻接矩阵,自动快捷地为管网系统水力分析做好准备。     

Algorithm and Its Implementation for the Network Maximal Flow

On the algorithm of the network maximal flow, the paper provides a method of achieving it. The concrete procedure is to achieve the algorithm by using stack and structural array. First of all, an adjacency list should be established and its composition chiefly includes orientation, capacity, flux and so on. Afterwards the labeling method is adopted to find the augmenting chain according to the adjacency list. In the process, some spots are stored in the stack by means of the depth superior traverse and range superior traverse and the course way is also conserved in the array. Keep on doinh this till the maximum flow and the flow of each arc are all found.     

基于多目标遗传算法的管孔组合特征识别

提出一种管孔组合方式的自动识别方法.提取木材显微横切面的边缘后,基于类圆区域面积直方图,通过最大类间方差将封闭区域分为2类,将导管与其他形状相似、大小不同的组织分开；同时,引入封闭区域平均面积作为另一目标函数.最后采用管孔集邻接度来判断管孔的组合方式.试验表明该方法能够对各种导管的分布和组合获得满意的分割效果,并给出管孔的组合方式.     

农村地类分布格局及形成机理研究——以扬州市区为例

通过构建地类邻接比、村域土地城镇化率等指标,运用兼业农户选址理论模型,以扬州市区为例,从中观、微观尺度分析了农村地类分布格局及形成机理。研究表明:（1）农村地类分布具有空间耦合性,源地类对目标地类空间分布具有决定影响,其中集镇、公路分布对目标地类有中观尺度影响,坑塘水面（沟渠）、农村公路对目标地类分布有微观尺度影响;（2）微观尺度下,农村主要地类由于地形因素而分别呈现同心圆和带状分布模式;中观尺度下,农村地类往往呈U型分布,主要体现在土地城镇化率的空间差异,上述模式的形成是农户按生产空间成本最小化或比较利益最大化的选择结果;（3）运用地类邻接比指标可从微观尺度分析源地类与目标地类之间的空间依存度;兼业农户选址理论模型可从中观尺度分析农户居民地选址与经济发展之间的内在关系,具有一定的方法论意义。