面向水流三维登记探索的多波束点云去噪及应用

针对多波束点云数据去噪难以保留精细特征,无法精确“锁定”河床形态问题,本文提出了一种面向自然资源确权水流三维登记探索的多波束点云去噪算法。以KD树搜索为基础,引入统计滤波理论进行多尺度噪声分类,并剔除大尺度噪声;针对小尺度噪声,在信息熵理论基础上,以主成分分析算法为基础,以信息熵最小原则确定最优邻域,并据此构建曲率信息熵对双边滤波因子进行优化改进,以实现水下地形点云去噪与精细特征保留的目的。试验结果表明,本文算法具有可行性,能够有效保证水下地形的精细特征,并能够应用于自然资源水流三维登记。     

面向对象高分辨率影像信息提取中的尺度效应及最优尺度研究

本文从面向对象的遥感信息提取中的尺度效应研究入手,对影像对象的分形维数、紧凑度、面积、均值、标准差和与邻域均值差分等特征进行了实验.在此基础上,根据"类内同质性大,类问异质性大"的最佳分类原则,提出了面向对象的RMAS方法,该方法的思想是,当对象RMAS值最大时,对象内部的异质性最小,对象外部的异质性最大,此时的分割尺...     

PS InSAR公共主影像优化选取的一种新方法

在原有的公共主影像优化选取模型的基础上,对影响干涉图相关性的3个主要参数进一步综合优化,提出并实现了一种基于三基线和最小的公共主影像优化选取新方法。理论分析和实验结果表明,与原有方法相比,新的公共主影像优化选取方法简单、可行,选取的公共主影像合理、准确。     

地震波场模拟中的褶积微分算子法

褶积微分算子是将偏导数算子的带限傅氏谱进行反傅氏变换得到的,具有对称或反对称和衰减速度快的特点。根据频谱分析理论,选用序列在结束时能光滑趋于零的截断窗口将褶积算子截断,结合考虑微分算子守恒定律,将褶积算子中心值进行修正,得到适合于波场模拟的最优权系数。给出用褶积微分算子模拟声波波场的实现途径与实例。理论分析与模型试算证明了褶积微分算子法的正确性与有效性。     

China summer precipitation simulations using an optimal ensemble of cumulus schemes

RegCM3 (REGional Climate Model) simulations of precipitation in China in 1991 and 1998 are very sensitive to the cumulus parameterization. Among the four schemes available, none has superior skills over the whole of China, but each captures certain observed signals in distinct regions. The Grell scheme with the Fritsch-Chappell closure produces the smallest biases over the North; the Grell scheme with the Arakawa-Schubert closure performs the best over the southeast of 100°E; the Anthes-Kuo scheme is superior over the northeast; and the Emanuel scheme is more realistic over the southwest of 100°E and along the Yangtze River Basin. These differences indicate a strong degree of independence and complementarity between the parameterizations. As such, an ensemble is developed from the four schemes, whose relative contributions or weights are optimized locally to yield overall minimum root-mean-square errors from observed daily precipitation. The skill gain is evaluated by applying the identical distribution of the weights in a different period. It is shown that the ensemble always produces gross biases that are smaller than the individual schemes in both 1991 and 1998. The ensemble, however, cannot eliminate the large rainfall deficits over the southwest of 100°E and along the Yangtze River Basin that are systematic across all schemes. Further improve-ments can be made by a super-ensemble based on more cumulus schemes and/or multiple models.     

Extension of subset simulation approach for uncertainty propagation and global sensitivity analysis

The subset simulation (SS) method is a probabilistic approach which is devoted to efficiently calculating a small failure probability. Contrary to Monte Carlo Simulation (MCS) methodology which is very time-expensive when evaluating a small failure probability, the SS method has the advantage of assessing the small failure probability in a much shorter time. However, this approach does not provide any information about the probability density function (PDF) of the system response. In addition, it does not provide any information about the contribution of each input uncertain parameter in the variability of this response. Finally, the SS approach cannot be used to calculate the partial safety factors which are generally obtained from a reliability analysis. To overcome these shortcomings, the SS approach is combined herein with the Collocation-based Stochastic Response Surface Method (CSRSM) to compute these outputs. This combination is carried out by using the different values of the system response obtained by the SS approach for the determination of the unknown coefficients of the polynomial chaos expansion in CSRSM. An example problem that involves the computation of the ultimate bearing capacity of a strip footing is presented to demonstrate the efficiency of the proposed procedure. The validation of the present method is performed by comparison with MCS methodology applied on the original deterministic model. Finally, a probabilistic parametric study is presented and discussed.     

沪蓉西主干线施谭坝边坡工程最优坡比分析

山区高速公路建设中会遇到大量的边坡开挖,其坡比对工程的设计与投资影响较大。因此研究边坡坡比的优化问 题,具有显著的经济效益和社会效益。为了保证边坡开挖工程既安全可靠又经济合理,在分析边坡工程地质条件的基础上,采用剩余推力法计算天然斜坡的稳定性。并根据规范从经济效益考虑,确定在开挖与支护总费用最低时的边坡开挖坡比为最优坡比。实例分析表明,施谭坝边坡工程的最优坡比为1: 0.65,该稳定性分析方法及最优坡比优化设计方案具有实用性和合理性。     

关于深基坑土钉支护设计中几个问题的探讨

在深基坑土钉支护设计中,目前存在着混乱的现象,如何既经济又安全可靠地设计土钉支护方案成为岩土工程界一个关键而又迫切的问题。本文从土钉受力及基坑变形控制等方面出发,对土钉支护中几个关键性问题进行了较为详细的分析,提出了土钉支护设计中土钉长度、间距的确定思想,并对其他一些问题做了较为详细的分析与探讨。     

济南市水资源概况及开发利用初探

综合分析济南的气候、自然、地理,尤其是水文地质条件,根据济南水资源基本特征与资源量,认为济南市水资源总量相对充足,水资源供求的突出矛盾集中体现为供水结构不合理、水资源开发利用不合理。结合济南市的水资源特征,制定了保障济南市水资源可持续利用方案及相应措施。     

洋河水库防洪实时优化调度模型研究

针对河北省洋河水库特点,建立了有模糊约束条件的防洪优化调度模型,提出了含变动罚函数的离散微分动态规划法,给出了模糊防洪库容计算公式。由成果分析表明,所提模型与方法是可行和实用的。