基于均值平移与模拟泛洪的图像分割算法

针对图像处理的特点，综合考虑执行速度与健壮性要求，提出了一种顺序搜索LUV空间候选点的均值平移实现方法。为了克服传统的基于特征空间分析的图像分割方法对像素点空间关系考虑不够充分的缺陷，借鉴Vincent ＆ Soille沉浸模拟分水岭算法思想，构造了一种与均值平移方法相适应的新的模拟泛洪方法执行图像分割。新方法比较符合人的主观感知，且易于容纳更多的特征以满足特定的图像分割需求。对实验用彩色图像的分割结果表明了该方法的有效性。     

Mean Free-Air Gravity Anomalies in the Mountains

Mean free-air gravity anomalies are often needed in geodesy for gravity field modelling. Two possible ways of compiling the mean free-air gravity anomalies are discussed. One way is via simple Bouguer gravity anomalies and the second and more time consuming way is via refined Bouguer gravity anomalies. In flat areas the differences between using any of the two ways should not be significant. In the mountains however, every effect introducing a high dependency, such as e.g. terrain effect, can negatively affect the interpolation process. In fact, a numerical experiment conducted in one part of Rocky Mountains revealed large and systematic differences. The effect of these differences on the geoid model is more then two meters in the test area. Our investigation shows that this bias is caused by the location of gravity measurement points, chosen mostly on hill-tops. At such points, the terrain correction to gravity is systematically larger than the mean value of the correction. Therefore, it is not possible to prevent the mean free-air gravity anomalies obtained from simple Bouguer gravity anomalies from having a systematic bias. One can see this bias as a result of the aliasing effect because the simple Bouguer gravity anomalies in the mountains contain a higher frequency signal (terrain effect) that is, according to sampling theorem, impossible to reconstruct by sparse measured gravity data, see e.g. (Goos et al., 2003). Therefore, the more rigorous way of computing the mean free-air gravity anomalies is via refined Bouguer gravity anomalies.     

封冻河道下流速分布和阻力问题探讨

封冻河道的水流阻力计算和水流速度重分布问题一直是河冰研究的重要问题之一,多年来,很多学者进行了相关研究,然而研究大多采用了冰盖区、河床区及过流断面水流平均速度相等的假定.依据Prandtal半经验紊流理论,采用目前普遍使用的对数流速分布公式,对上述假定进行了研究分析,由分析来看,这种假定的正确性需要探讨;分析也表明,阻力计算时若假定冰盖区和床面区的能坡相等,对宽浅式河道也将导出谬误.依据分析,就如何解决相应的问题提出了思路和建议.     

利用声波阻抗信息识别裂隙流体异常

基于岩石物理学和利用声波阻抗信息识别流体异常的新方法，结合理论模型和实际资料，对砂岩和碳酸盐岩中流体饱和EDA介质进行了等效的流体分析。这里首先提出了一种计算EDA介质等效波速的几何平均法。在此基础上研究了不同状况下EDA介质的几种流体属性的敏感性，并将结果与实际资料进行了比较，发现二有较好的一致性。这既证明了几何平均法的可行性，也证明了EDA介质在流体识别方面的可拓展性。对EDA介质的最终分析结果表明，合理的流体属性地提取，要考虑各种因素特别是信噪比的影响，同时裂隙密度在很大程度上决定了流体属性的敏感度。     

Two kinds of moment ratio diagrams and their applications in hydrology

We refocus attention on moment ratio diagrams and their uses in hydrology with four major objectives: (1) to summarize the information available in the literature about possible uses of the traditional moment ratio diagram introduced by Karl Pearson, which uses the coefficient of skewness and of kurtosis to compare the shapes of various distributions commonly used in hydrology; (2) to complete this traditional MRD by integrating into it the regions occupied by the log-Pearson Type III and generalized gamma distributions which are more and more used in hydrology; (3) to present another MRD which uses ratios of moments of orders –1 (harmonic mean), quasi zero (geometric mean) and 1 (arithmetic mean); (4) to stress the need to consider the different MRD's (along with the more recently introduced L-moment ratio diagrams) as complementary tools for choosing between distributions fitted to hydrologic data. Finally, using Monte Carlo simulation we compare the two types of diagrams as tools to identify and discriminate between different distributions.     

求算界限温度日期的一种新方法──样条函数插值法

本文根据某站点各月平均气温,通过计算机,用样条函数插值法模拟年温变化曲线,进而直接求算出主要界限温度初终日期、间隔日数及其相应积温,并与用滑动平均法得出的结果进行了比较检验。     

秩亏网伪逆平差值的修正估计

本文在[1]的基础上提出了秩亏的带权测量平差模型中禾知参数向量的一种线性有偏估计——秩亏网伪逆平差值的修正估计,并着重讨论了该估计在均方误差意义下改进最小二乘估计的优越性、可容许性及新产生的偏差。最后通过实例验证了所得结果。     

信息替换的均生函数主分量多步预测

提出随着时间的推移，用新信息取代旧信息的“限定记忆”的时间序列数据处理方法。且仅对均生函数外延矩阵的前Ｌ阶方阵作主分量分析，用数目较少又包含主要信息量的主分量因子对时间序列建模。该方案用于四川省２８个县市的年平均气温的多步预测值与实况值相对误差均在±４％以内，表明该方案用于气温多步预测是有效的。     

Preliminary Study of Reconstruction of a Dynamic System Using an One－Dimensional Time Series

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