Determining the Spectrum of the Nonlinear Local Lyapunov Exponents in a Multidimensional Chaotic System

For an n-dimensional chaotic system, we extend the definition of the nonlinear local Lyapunov exponent(NLLE) from one-to n-dimensional spectra, and present a method for computing the NLLE spectrum. The method is tested on three chaotic systems with different complexity. The results indicate that the NLLE spectrum realistically characterizes the growth rates of initial error vectors along different directions from the linear to nonlinear phases of error growth. This represents an improvement over the traditional Lyapunov exponent spectrum, which only characterizes the error growth rates during the linear phase of error growth. In addition, because the NLLE spectrum can effectively separate the slowly and rapidly growing perturbations, it is shown to be more suitable for estimating the predictability of chaotic systems, as compared to the traditional Lyapunov exponent spectrum.     

局部均值伪最近邻算法在降水预报中的应用

分析北京地区日降雨量资料发现,相较于其他降雨事件,大雨或暴雨事件发生的次数较少,因此该地区的降水量预报属于样本不均衡问题。在样本不均衡的情况下,K最近邻算法的分类误差率将会大大提高,这也就使传统的基于K最近邻算法的降水量预报方法的应用受到了限制。针对北京地区降水量预报这一样本不均衡问题,应用局部均值伪最近邻算法构建了北京市的降水量预报模型。该方法利用北京地区日降雨量资料和美国国家环境预报中心全球格点资料,将降雨量作为类,将美国国家环境预报中心全球格点资料的各种因子场作为天气样本特征,计算得到不同天气样本在所有类中的局部均值伪最近邻,通过决策规则实现最优分类。利用提出的降水预报模型对北京市2010年6—8月进行了24 h降水预报,实验结果表明,提出的预报方法对于降水等级预报的预报准确率以及晴雨预报的TS评分、正样本概括率、空报率和漏报率均优于传统的K最近邻预报方法,该方法具有较好的预报效果。     

Geographically weighted regression with parameter-specific distance metrics

Geographically weighted regression (GWR) is an important local technique to model spatially varying relationships. A single distance metric (Euclidean or non-Euclidean) is generally used to calibrate a standard GWR model. However, variations in spatial relationships within a GWR model might also vary in intensity with respect to location and direction. This assertion has led to extensions of the standard GWR model to mixed (or semiparametric) GWR and to flexible bandwidth GWR models. In this article, we present a strongly related extension in fitting a GWR model with parameter-specific distance metrics (PSDM GWR). As with mixed and flexible bandwidth GWR models, a back-fitting algorithm is used for the calibration of the PSDM GWR model. The value of this new GWR model is demonstrated using a London house price data set as a case study. The results indicate that the PSDM GWR model can clearly improve the model calibration in terms of both goodness of fit and prediction accuracy, in contrast to the model fits when only one metric is singly used. Moreover, the PSDM GWR model provides added value in understanding how a regression model’s relationships may vary at different spatial scales, according to the bandwidths and distance metrics selected. PSDM GWR deals with spatial heterogeneities in data relationships in a general way, although questions remain on its model diagnostics, distance metric specification, and computational efficiency, providing options for further research.     

考虑尺度敏感性的长江中下游暖区暴雨初始扰动方案比较分析

弱天气尺度强迫背景下的长江中下游暖区暴雨突发性强,高度非线性,难以准确预报,这时考虑不确定因素的集合预报成为重要选项,而对流尺度集合预报核心问题是积分一段时间后离散度偏低,会导致预报失败。比较包含不同尺度扰动信息的对流尺度集合预报方案间的差异性并据此优化初始扰动方案,针对2018年5月4—5日一次典型长江中下游暖区暴雨过程,分别采用动力降尺度（DOWN）、增长模繁殖法（BGM）、局地增长模繁殖法（LBGM）和混合扰动法（BLEND）等四种方法进行集合预报试验,以期探讨对离散度和预报效果的影响。结果表明,在模式积分0~6 h,具有中小尺度扰动信息的BGM和LBGM的离散度优于DOWN,其中LBGM相比于BGM具有一定程度上的改进,说明具有更准确中尺度特征的扰动能够在积分初始阶段获得有效增长,即考虑了中小尺度天气系统局地性的LBGM能弥补BGM的不足;但是,在模式积分12 h以后,具有更多大尺度特征扰动的DOWN优于区域模式中的增长模繁殖法BGM和LBGM,说明经过初始误差快速增长一段时间后,大尺度扰动开始起主要作用。而具有不同尺度扰动信息的BLEND方案则兼具LBGM和DOWN的优势,几乎在整个预报时段离散度较高且概率预报评分较好,体现出混合扰动的优越性。以上结果进一步说明,初始扰动的尺度特征在暖区暴雨的集合预报效果中具有关键性的作用,因而通过调整初始扰动的尺度信息来优化集合预报性能的混合扰动思想,在业务上具有一定的指导意义和推广价值。     

Tasting cheesescapes in Canterbury (New Zealand)

Food tourism is a means to connect agriculture produce and tourism activity. Food tourism allows destinations to convey the authenticity that comes from their food heritage, which is closely linked to natural and cultural landscapes. Food and landscapes in New Zealand are strongly related to dairy production, cheese production being one of the main features. This study showcases cheesescapes in Canterbury, the largest region in the South Island of New Zealand in terms of milk production. On one hand, thanks to food tourism, the producers can explore ways to diversify their production. On the other hand, visitors are able to identify with the inhabitants of a country and ‘taste’ a portion of its landscape through gastronomy.     

Graphic symbols and local identity: the case of use and perception of municipal emblems in the Liberec Region (Czechia)

This paper analyses the role of graphic symbols in local representation and in the process of local identity formation. The extent of graphic symbols utilization by local development actors in the region, its importance for image formation of the locality (municipality) from the point of view of the local development actors and an assessment of the degree of identification with the municipal emblems among the local population are evaluated, based on the results of a corresponding survey targeted at municipal representatives. Municipal emblems tend to (and also should) have a local representative function. These should emphasize local specificity, uniqueness. Municipal emblems have a potential to play the role of connecting, mediating and activating factors also on a higher as well as a local level. Municipal emblems are still not used enough and in the right way by actors of municipality representations. These are often misunderstood and deemed unimportant for local development.     

区域地球化学样品分析质量管理计算机控制

使用通用的Microsoft Office系统中的Excel软件,根据不同项目及不同元素的内检质量和一级标准物质质量,判断分析测试质量。对区域地球化学样品分析测试质量进行计算机及局域网质量控制,利用Access工具建立数据库,编制一级标准物质质量控制表、密码检查质量控制表,制作质量监控图及打印检测报告等质量监控体系,实现对化探样品分析数据质量的管理。     

喷射式局部反循环绳索取心钻具

针对金矿复杂破碎地层钻探存在的岩心采取困难、孔内漏失严重等问题,改进绳索取心钻具,增加了局部反循环装置,研制出一套适应性广、取心可靠的可调喷射反循环钻具,提高岩心采取率,取得了良好的效果。介绍了该钻具的结构原理、适应范围及应用效果。     

城市目标图像快速更新方法

城市地理环境数据的快速获取与更新是应急测绘保障中的重要任务。本文探讨了一种在应急测绘保障情况下基于城市目标区域的正射影像快速更新方法。该方法能利用最新遥感影像资料对旧正射影像进行基于目标区的局部自动更新。实验证明了该方法的有效性和实用性。     

太平矿暗斜井充水水源分析

在综合分析太平煤矿井水文地质条件、出水点岩性特征的基础上,通过钻孔探放、水样化验资料的对比分析,认为该矿＋700水平胶带暗斜井的间接充水水源可能来自摩梭河;基于涌水点位置与出水量,以及瞬变电磁法确定的巷道前方富水区域情况,确定了采用浅层注浆法封堵的治水方案。