基于尺度变换随机共振的瞬变电磁弱信号检测

晚期瞬变电磁信号是大参数、多频率、且各频率分量未知的电磁信号,特别在晚期还是强噪声背景下的微弱信号.随机共振系统可以在极限信噪比的情况下提取微弱信号,但仅适用于小参数、单一频率或频率已知的高频信号的情况,为此,本文提出一种基于尺度变换的随机共振算法用于检测晚期瞬变电磁信号,该方法充分利用了随机共振检测弱信号的优势,通过...     

县域主体功能区划中可利用水资源指标测算评价研究——以山西省河津市为例

可利用水资源是县域主体功能区规划指标体系的重要指标之一,主要是评价一个地区剩余和潜在可利用水资源对未来社会经济发展的支撑力.以河津市9个乡镇为基本单元,分析各个乡镇的可开发利用水资源,调水量等指标,得出河津市人均水资源潜力空间分布图,并针对各个乡镇在主体功能区中的不同职能提出更加切合乡镇具体情况的水资源利用措施.     

Streamflow scaling properties: investigating characteristic scales from different statistical approaches

This paper studies the links between scaling properties of river flow time series by comparing the results of three techniques applied to an extended data set of 34 French discharge gauging stations. The three approaches used are based on different mathematical tools and hypotheses: (1) shape analysis of flood hydrographs; (2) a multifractal framework through spectral and moment analyses, and (3) flood frequency analysis through the fitting of flood duration frequency curves (QdF). The general aim is to test the hypothesis of scaling invariance of river flow and the shape invariance of the hydrographs, in order to investigate the link between scaling properties and flow dynamics. In particular, the coherence between different approaches widely used in the literature to describe these characteristics is evaluated through the estimation of parameters defining the range of time‐scales on which the scaling properties are valid. The results show that most of these timescale parameters are linked to the flow dynamics and suggest that the approaches applied are interrelated. Copyright © 2008 John Wiley & Sons, Ltd.     

周日观测下动态目标测量数据的实时处理

Ｇｅｏ－ｒｏｂｏｔ系统用于变形监人理论上对系统的数据处理作了论述,从实际上论证了系统数据处理方法的实用性和可靠性,极大地克服了现在常规地面测量方法的诸多缺陷,减轻了测量工作的过去强度。１９９７年１１月,该系统首次在五强海水电站水坝进行现场试测,取得了令人满意的结果。     

视觉比例尺对建立心像地图的影响

地图并不是地面实际情况的简单缩小的拷贝,它是人类依据不同需要对地面事物认识后进行抽象和概括的地面模型。比例尺不仅确立了图面与实地之间的几何比例关系,而且反映了人类对空间认知抽象的程度。地图作为人类进行空间认知的有力工具,其地位从来就没有被其它的事物所动摇过,究其原因是地图的空间表达方式比其它表达方式更适合人类的思维。心像地图是人脑在综合了或智能处理了各种感觉所获得的诸多信息后产生的内部表征。而地图又是诸多信息源中最为重要的一种形式。本文通过视觉感受到心像的形成过程、分析心像地图的特性,提出了适应视觉感受因素的视觉比例尺的概念,并分析了视觉比例尺对建立心像地图的影响。     

兰州台地磁观测常见故障的判断与排除

在地磁观测中,当绝对观测磁力仪,相对记录磁变仪,辅助设备等发生故障以及观测所得不准或其它问题时,将如何快速判别及排除,作了较详细的叙述。     

On the form factor scale effect

Four geosim families, with fully available resistance test results, have been re-analyzed to check the possible scale effect on the form factor. The form factor determined by Prohaska's method, with exponent n=4 and ITTC'57 correlation line, increases with the model size in all four cases analyzed. Because of its high correlation coefficient, a linear variation of the form factor with the scale is assumed. It is possible to have a first estimation of the ship's form factor extrapolating for λ=1 in the regression line. Form factor Reynolds number dependency will always be associated with a friction line. Using the ITTC'57 correlation line, the following equation K_S−K_M=1.91·(λ−1)·10⁻³ can be used to estimate the scale effect on the form factor. Calculations carried out, for axisymetric bodies, with some CFD codes are in good agreement with the experimental findings.     

中国土地利用/土地覆盖的多尺度空间分布特征分析

研究了我国土地利用影响因素及其空间规模相关性,采用数理统计与ＧＩＳ手段从多个规模尺度上探讨了我国土地利用的空间分布特征。其结果对全国以及各级政府进行土地利用规划、制定相应的土地开发与利用政策等具有一定的参考意义。     

基于尺度因素的地下水随机分析

针对小尺度的各态历经假设的失效,研究了小尺度上多孔介质特性参数统计特征。利用基于K-L(Karhunen-Loeve)展开和混沌展开的谱模型,分析了尺度大小对地下水流动的影响。结果表明,尺度大小导致了特征值系列和特征函数系列的变化,尺度的变化对水头、含水量、流速影响程度不同;水头和流速方差与尺度相关,尺度越大,水头和流速方差越大;研究尺度的变化对水头、含水量、流速均值产生的影响较小。