基于PPDC模型的中国生态环境质量区划

投影寻踪聚类(PPC)模型在多因素聚类分析中被广泛应用并取得了满意的效果,然而,模型还存在诸如密度窗宽参数取值经验确定等不足,有待改进提高.针对投影寻踪聚类模型存在的问题,首次把投影寻踪聚类的思想和动态聚类方法结合起来构造投影指标,建立了投影寻踪动态聚类(PPDC)新模型,新模型在整个运算过程中毋需人为给定参数,具有聚类结果客观、明确以及稳定性好、操作简便等特点.应用投影寻踪动态聚类模型对中国生态环境质量进行评价,获得了有切实意义的区划结果.此研究为生态环境质量评价开创了一条新途径,也进一步为生态保护、建设和监督管理提供科学依据和技术支持.     

A Genetic Fuzzy Analytical Hierarchy Process Based Projection Pursuit Method for Selecting Schemes of Water Transportation Projects

1IntroductionOpti mal selection of schemes of water transportationprojects is a process of choosing a relatively opti malscheme froma number of schemes of water transporta-tion programming and management projects,on thebasis of the principle such that bot…     

动态波形匹配预测火山岩地层的横向变化

讨论一种根据3D地震数据计算地层横向变化的方法动态波形匹配方法,该方：该方法利用动态规划算法对相邻地震道地震波形进行动态波形匹配并计算波形匹配费用．把波形匹配费用作为相邻地震道地震波形之间差异大小程度的度量．对大庆油田一块800km^2的3D地震数据的计算表明,动态波形匹配费用可以较好地度量相邻地震道地震波形之间的差异,表示地下地质体的横向变化,如断层、裂缝发育带和火山岩岩体等．     

Study on Precipitation Image Downscaling Based on the Method of Ill-posed Problems Solving

Downscaling of remote sensing precipitation products and the forecasting of circulation model are always the intense interests in hydrology and meteorology. The essence of downscaling is primarily to enhance resolution of observation or simulated rainfall field, and to appropriately increase its details or high frequency characteristics. Precipitation, as the main driving factors of the earth’s hydrologic cycle, not only affects the moisture and heat condition of a certain river basin, but also affects the global water and heat circulation. Based on the properties of rainfall self-similarity structure, the mathematically ill-posed precipitation problem solving method was used in low resolution downscaling precipitation for high resolution reconstruction. When solving the downscaling ill-posed problem, the greedy method of orthogonal matching pursuit was introduced so as to get the best high-resolution estimation in an optimal sense. It is hard to imagine that we might be able to find very similar (in mathematical norms) precipitation patterns over relatively large storm-scales. However, finding similar features over sufficiently small sub-storm scales seems more feasible. Based on the characteristics that small scale organized precipitation features tend to recur across different storm environments, the precipitation of both high and low resolution was obtained by training, which could be used to reconstruct the desired high-resolution precipitation field. Multi-source merged precipitation products were used in this experiment. Given the consideration of incompleteness of merged precipitation dataset, it was firstly interpolated based on the method of Fields of Experts (FoEs), which could solve the problem that common interpolation method could hardly work on the interpolation for dataset where consecutive missing data exists. Secondly, ideal experiments of precipitation products downscaling were carried out, where smooth coupling sampling and resampling operator were adopted respectively. Assessment based on the metrics of fidelity and spatial structural similarity demonstrates that the method used in this paper is feasible.     

基于投影寻踪原理的动态聚类模型及其在气候区划中的应用

以投影寻踪原理为基础, 结合动态聚类方法, 建立了基于投影寻踪原理的动态聚类模型, 并首次将其应用于气候区划分析中。首先, 利用线性投影技术将多因素聚类问题转换为投影特征值的线性聚类问题; 其次, 利用动态聚类方法完成投影特征值序列的聚类分析; 最后, 通过气候区划实例验证了基于投影寻踪原理的动态聚类模型的可行性与有效性。     

动态DEM匹配方法研究

在回顾现有制导技术之后,提出了一种新的导弹制导思想---利用动态DEM匹配方法实现导弹制导。在介绍这一思想及其实现步骤之后,文章着重介绍动态DEM匹配阶段中涉及的几个关键环节,即特征提取、特征描述、特征匹配、变换参数的解求以及相关匹配的改进等问题,最后,用实验验证了上述思想,得出结论,并为今后进一步研究提出了若干建议。     

利用搜索算法原理进行等高线接边

一般情况下，立体像对测行的等高线数据进行接边处理，以距离作为等高线匹配的标准存在一定的缺陷。本文介绍了一种将等高线本身具有的图形特征作为匹配标准并利用搜索算法原理找共轭等高线的算法。此算法具有处理等高线数据异常的能力，较适合一般情况下等高线的接边处理，在此算法中为了盲目的搜索，提出一种计算关联值的方法并以此来选择前进的方向，提高搜索效率。此算法经过了上机实验，结果令人满意。     

投影寻踪自回归和多维混合回归模型及其在大河长河段洪水预报中的应用

投影寻踪自回归和多维混合回归模型，是将投影寻踪技术应用于时间序列分析中的一种新型的非线性时序分析模型。本文将此模型用于长江寸滩－宜昌河段的洪水演算，不必使用区间雨量资料，仅仅根据上下游站的流量资料，就可做出预见期为４８－７２ｈ的复杂长河段洪水预报，并取得了令人满意的的研究成果。     

SPOT立体图像的有限元最小二乘匹配

本文将多点最小二乘匹配算法扩展为有限元最小二乘匹配,导出了有限元最小二乘匹配的数学模型,并提出了自动产生视差格网的方案;通过试验研究了有限元最小二乘匹配中有关参数,例如,辐射变换参数、虚拟观测的权值以及视差格网间隔的确定。有限元最小二乘匹配算法无需预先进行核线重排列,就可以直接答解出有限个格网点的上下视差和左右视差。这种算法亦可用于其他任何投影方式成象的立体图象的自动匹配。     

Indigenous Lands with secure land-tenure can reduce forest-loss in deforestation hotspots

Due to human activities, most natural ecosystems of the world have disappeared and the rest are threatened. At a global scale, 40% of the remaining forests occur in Indigenous Peoples Lands (IPL). While several studies show that IPL contribute to conserve forest-cover and halt forest-loss, other studies have found opposite results. The differing results on the role of IPL in forest conservation and loss are probably because of the effect of other variables, e.g. land tenure security. In this study, we addressed the role of IPL in forest conservation and loss, differentiating IPL with land-tenure security (IPL-S) and insecurity (IPL-I). We worked in a deforestation hotspot, the South American Dry Chaco region. First, we mapped IPL in the Dry Chaco. Then, covering the period 2000–2019, we measured forest cover and loss in IPL-S, IPL-I and in areas that are not Indigenous (non-IPL). Finally, we used a matching estimators method to statistically evaluate if IPL-S and IPL-I halt forest loss. To avoid bias, we accounted for the effect of variables such as Country (Argentina/Bolivia/Paraguay), Protected Area (yes/no), etc. We created the first map of IPL for the Dry Chaco, and found that at least 44% of the remaining forests are in IPL, and 67% of them are IPL-I. Our results also showed that IPL-S work as deforestation barriers. Inside PA, the effect of IPL-S was not always significant, probably because PA were already reducing forest loss. The effect of IPL-I on halting forest-loss was variable. We conclude that land-tenure security is key for IPL to reduce forest-loss, adding evidence on the importance of securing land-tenure rights of Indigenous communities for conservation purposes. At a regional scale, a large proportion of the remaining forests are Indigenous and conservation initiatives should be co-developed with locals, respecting their rights, needs and cosmovisions.