多约束的平面点集形状重构方法

针对平面点集空间分布的复杂性,本文提出了一种基于Delaunay三角网的平面点集形状重构方法。首先采用一种简单且实用的数据结构以表达Delaunay三角网中嵌入的几何信息和拓扑信息,然后由外向内迭代过滤Delaunay三角网得到一个大概边界,最后进一步考虑边界的凹凸信息和空洞现象,获取最终的精细边界。试验结果表明与其他典型的Delaunay三角网重构方法相比,本文提出的算法能更好地适用于平面点集空间分布的复杂性,通过所构建的数学模型实现了凸凹多边形内外边界提取。     

Diatom-environmental relationships in 64 alkaline southeastern Ontario (Canada) lakes: a diatom-based model for water quality reconstructions

Lake eutrophication is a problem in many areas of Ontario, although the history of nutrient enrichment is poorly documented. The aim of this study was to construct a diatom-based transfer function to infer past phosphorus levels in Ontario lakes using paleolimnological analyses. The relationship between diatom assemblages and limnological conditions was explored from a survey of diatoms preserved in the surface sediments of 64 Southern Ontario lakes, spanning a total phosphorus gradient of 0.004 to 0.054 mg L^-1. Over 420 diatom taxa were identified, 98 of which were sufficiently common to be considered in statistical analyses. Canonical correspondence analysis (CCA) determined that pH, ammonium, aluminum, spring total phosphorus (TP), strontium, total nitrogen (TN), maximum depth (MaxZ), chlorophyll a (Chla) and mean depth were significant variables in explaining the variance in the diatom species data. The environmental optima of common diatom taxa for the limnologically important variables (TP, pH, TN, MaxZ, Chla) were calculated using weighted averaging (WA) regression and calibration techniques, and transfer functions were generated. The diatom inference model for spring TP provided a robust reconstructive relationship (r² = 0.637; RMSE = 0.007 mg L^-1; r² _boot = 0.466; RMSE_boot = 0.010 mg L^-1). Other variables, including pH (r² = 0.702; RMSE = 0.208; r² _boot = 0.485; RMSE_boot = 0.234), TN (r² = 0.574; RMSE = 0.0899 mg L^-1; r² _boot = 0.380; RMSE_boot = 0.127 mg L^-1) and MaxZ (r² = 0.554; RMSE = 1.05 m; r² _boot = 0.380; RMSE_boot = 1.490 m), were also strong, indicating that they may also be reconstructed from fossil diatom communities. This study shows that it is possible to reliably infer lakewater TP and other limnological variables in alkaline Southern Ontario lakes using the WA technique. This method has the potential to aid rehabilitation programs, as it can provide water quality managers with the means to estimate pre-enrichment phosphorus concentrations and an indication of the onset and development of nutrient enrichment in a lake.     

Kriging with imprecise (fuzzy) variograms. II: Application

The geostatistical analysis of soil liner permeability is based on 20 measurements and imprecise prior information on nugget effect, sill, and range of the unknown variogram. Using this information, membership functions for variogram parameters are assessed and the fuzzy variogram is constructed. Both kriging estimates and estimation variances are calculated as fuzzy numbers from the fuzzy variogram and data points. Contour maps are presented, indicating values of the kriged permeability and the estimation variance corresponding to selected membership values called levels.     

基于粗糙集与BP神经网络的底板破坏深度预测

基于粗糙集理论,以指标集为基础,建立了底板破坏深度影响因素的知识表达系统,提出了规则提取原则,通过粗糙集决策规则的数据处理,得出获得各因素对底板破坏深度的影响顺序为:采深、煤层倾角、工作面斜长、采厚、底板抗破坏能力、工作面是否有切穿型断层或破碎带。由于底板抗破坏能力、工作面是否有切穿型断层或破碎带这些参数难以确定,采用其余4种影响因素建立BP神经网络的预测模型,并根据建立的模型预测肥城煤田的9101和9507工作面的底板破坏深度。通过与实测结果对比,证明该网络模型的计算结果比规程提供的经验公式计算结果更接近实际。     

结合水平集与光流的序列影像运动分割技术研究

提出一种结合变分水平集分割与变分光流的运动分割方法。该方法将光流能量函数与水平集分割能量函数进行整合形成新的运动分割能量函数,并采用变分方法进行优化。采用无人机序列影像对该运动分割方法进行实验分析,实验结果表明该方法在目标运动位移过大时,既能准确地估计出运动矢量,又能精确地分割出目标区域。     

A systematic comparison of different object-based classification techniques using high spatial resolution imagery in agricultural environments

Geographic Object-Based Image Analysis (GEOBIA) is becoming more prevalent in remote sensing classification, especially for high-resolution imagery. Many supervised classification approaches are applied to objects rather than pixels, and several studies have been conducted to evaluate the performance of such supervised classification techniques in GEOBIA. However, these studies did not systematically investigate all relevant factors affecting the classification (segmentation scale, training set size, feature selection and mixed objects). In this study, statistical methods and visual inspection were used to compare these factors systematically in two agricultural case studies in China. The results indicate that Random Forest (RF) and Support Vector Machines (SVM) are highly suitable for GEOBIA classifications in agricultural areas and confirm the expected general tendency, namely that the overall accuracies decline with increasing segmentation scale. All other investigated methods except for RF and SVM are more prone to obtain a lower accuracy due to the broken objects at fine scales. In contrast to some previous studies, the RF classifiers yielded the best results and the k-nearest neighbor classifier were the worst results, in most cases. Likewise, the RF and Decision Tree classifiers are the most robust with or without feature selection. The results of training sample analyses indicated that the RF and adaboost. M1 possess a superior generalization capability, except when dealing with small training sample sizes. Furthermore, the classification accuracies were directly related to the homogeneity/heterogeneity of the segmented objects for all classifiers. Finally, it was suggested that RF should be considered in most cases for agricultural mapping.     

侧扫声呐图像分割的中性集合与量子粒子群算法

针对现有的侧扫声呐图像分割方法存在分割准确率不高和效率偏低的问题,提出了一种基于中性集合和量子粒子群算法的侧扫声呐图像阈值分割方法。通过基于中性集合计算图像灰度共生矩阵,实现了侧扫声呐图像精细纹理的表达,提高了分割精度;基于二维最大熵理论,采用量子粒子群算法计算二维最优分割阈值向量,实现了分割阈值向量的快速准确获取,提高了分割效率和精度。最终实现了高噪声侧扫声呐图像目标的准确、高效分割。通过对含有不同目标的侧扫声呐图像的分割试验,验证了该算法的有效性。     

Relativistic Information Entropy on Uncertainty Analysis

- in this paper, a new approach to relativistic information entropy is used to assess some relative uncertainties in structural reliability assessment. This approach is composed of the information theory and the relativistic theory, and can be used to measure the relativity of parameter uncertainty and system uncertainty in structural reliability theory based on the same generalized relativistic reference system. Therefore, the structural reliability assessment can be assessed reasonably by the approach.     

Decadal Climatic Anomalies in the Northern Adriatic Sea Inferred from a New Oceanographic Data Set

Abstract. In 1997, Artegiani et al. depicted for the first time the seasonal climatology of the Adriatic Sea; they used the ATOS data set, formed by 5540 oceanographic stations sampled over this continental basin from 1911 to 1980. Lately, two Italian institutes working on the Adriatic Sea for long time, IBM and IRPEM, merged their recent data sets for the northernmost part of the basin. This yielded 3600 new oceanographic stations, concentrated in an area where 809 ATOS stations were located. The new data were quality checked, and then a seasonal climatology was drawn up as a first analysis step. The new climatology differed significantly from the ATOS results; this could be explained, at least partially, by the climatic changes that have occurred on this area. For example, air temperature increased significantly over northern Italy starting from 1988. Variations of the observed air temperature and Po River runoff qualitatively agree with sea surface temperature and salinity variations. A preliminary computation of heat fluxes based on ECMWF reanalysis confirms an increased heat flux to the Northern Adriatic Sea starting from 1988.     

影响计算海湾内台风波浪的诸因素

本文阐明了影响计算海湾内台风波浪的重要因素，使用我们目前已改进了的模式，可克服以往的计算缺陷，而使计算效果达到最佳。同时，阐述了不同海湾、不同的地理环境对台风浪波能的消衰不同。并强调了台风增水对台风浪计算的影响，其也直接影响着工程设计波浪参数的合理选取。