This paper presents a new method for simulating the evolution of a gully head in a loess catchment with cellular automata(CA) based on the Fisher discriminant. The experimental site is an indoor loess catchment that w...This paper presents a new method for simulating the evolution of a gully head in a loess catchment with cellular automata(CA) based on the Fisher discriminant. The experimental site is an indoor loess catchment that was constructed in a fixed-intensity rainfall erosion test facility. Nine high-resolution digital elevation model(DEM) data sets were gathered by close range photogrammetry during different phases of the experiment. To simulate the evolution of the catchment gully head, we assumed the following. First, the 5th and 6th DEM data sets were used as a data source for acquiring the location of the catchment gully head and for obtaining spatial variables with GIS spatial analysis tools. Second, the Fisher discriminant was used to calculate the weight of the spatial variables to determine the transition probabilities. Third, CA model was structured to simulate the evolution of the gully head by iterative looping. The status of the cell in the CA models was dynamically updated at the end of each loop to obtain realistic results. Finally, the nearest neighbor, G-function, K-function, Moran′s I and fractal indexes were used to evaluate the model results. Overall, the CA model can be used to simulate the evolution of a loess gully head. The experiment demonstrated the advantages of the CA model which can simulate the dynamic evolution of gully head evolution in a catchment.展开更多
基于北京都市区的POI(Points of Interest)数据,应用点模式分析法识别城市主次中心,通过对比去除就业中心前后的集聚度,探讨就业中心对不同产业的集聚作用。研究发现,在北京市多中心的空间结构下,所有产业均表现为集聚分布,其中生产性...基于北京都市区的POI(Points of Interest)数据,应用点模式分析法识别城市主次中心,通过对比去除就业中心前后的集聚度,探讨就业中心对不同产业的集聚作用。研究发现,在北京市多中心的空间结构下,所有产业均表现为集聚分布,其中生产性服务业在主中心内呈现明显集聚特征;生产性服务业和生活性服务业的内部产业间倾向于邻近分布,主中心内产业邻近度更高;从主次中心来看,主中心对金融及商务服务行业具有较强吸引力,而郊区次中心产业分布相对分散,需进一步强化集聚能力。展开更多
基金National Natural Science Foundation of China(No.41171320,41101349)National Innovation and Entrepreneurship Program(No.201210319025)
文摘This paper presents a new method for simulating the evolution of a gully head in a loess catchment with cellular automata(CA) based on the Fisher discriminant. The experimental site is an indoor loess catchment that was constructed in a fixed-intensity rainfall erosion test facility. Nine high-resolution digital elevation model(DEM) data sets were gathered by close range photogrammetry during different phases of the experiment. To simulate the evolution of the catchment gully head, we assumed the following. First, the 5th and 6th DEM data sets were used as a data source for acquiring the location of the catchment gully head and for obtaining spatial variables with GIS spatial analysis tools. Second, the Fisher discriminant was used to calculate the weight of the spatial variables to determine the transition probabilities. Third, CA model was structured to simulate the evolution of the gully head by iterative looping. The status of the cell in the CA models was dynamically updated at the end of each loop to obtain realistic results. Finally, the nearest neighbor, G-function, K-function, Moran′s I and fractal indexes were used to evaluate the model results. Overall, the CA model can be used to simulate the evolution of a loess gully head. The experiment demonstrated the advantages of the CA model which can simulate the dynamic evolution of gully head evolution in a catchment.
文摘基于北京都市区的POI(Points of Interest)数据,应用点模式分析法识别城市主次中心,通过对比去除就业中心前后的集聚度,探讨就业中心对不同产业的集聚作用。研究发现,在北京市多中心的空间结构下,所有产业均表现为集聚分布,其中生产性服务业在主中心内呈现明显集聚特征;生产性服务业和生活性服务业的内部产业间倾向于邻近分布,主中心内产业邻近度更高;从主次中心来看,主中心对金融及商务服务行业具有较强吸引力,而郊区次中心产业分布相对分散,需进一步强化集聚能力。
文摘选取两组有机化合物的熔点数据,采用ADMEWORKS Model Buider软件计算并选取描述符,以所选描述符为自变量,熔点为因变量。通过三种模式识别方法——K-最近邻法（K-Nearest Neighbor Method,KNN）、K-均值聚类法（K-Means Clustering Method,KMC）和投影寻踪方法（Projection Pursuit Method,PP）对样本进行分类,将分类后的样本分别以多元线性回归（Multiple Linear Regression,MLR）、偏最小二乘（Partial Least Squares,PLS）和人工神经网络（Artificial Neural Network,ANN）建立QSPR模型。结果表明,三种模式识别方法均可以提高模型的预测能力。模型的预测能力不仅与结构相似度有关,还与建模方法有关。非线性模型预测能力要优于线性模型。
