共查询到20条相似文献，搜索用时 93 毫秒
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遥测系统观测的雨量资料常会包含粗差，根据降雨量的特征，结合抗差理论，包为民等曾提出三步抗差修正方法。将此法应用到龙颈上水库等10个水库流域的实测资料当中，验证其有效性，并分析比较各步抗差修正的效果及降雨特征与抗差效果之间的关系。结果表明，抗差修正方法可行，且第一步和第三步结合的修正效果最好；降雨中心较明确，多年降雨特征相似，强度变幅稳定的洪水，不容易出现误抗。 相似文献
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本文根据定位参数Ｍ估计理论,导出了ＬＰ估计的影响函数,分析了ＬＰ估计的抗差能力,同时还推导了ＬＰ估计的渐近效率,综合抗差能力和效率,分析了ＬＰ估计的优劣性,明确指出,用现测数据中含有粗差扰动的数据和Ｐ为（１,１．２５）的ＬＰ估计进行处理,结果较优,效率较高。 相似文献
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大岗山水电站右岸边坡位于大渡河断裂和磨西断裂所切割的断块上,地震发生频繁且烈度高,岩体卸荷强烈,构造稳定性差,裂隙发育集中。已有研究成果显示出边坡开挖过程中锚索支护的重要性,也有较多学者对抗剪洞支护的设计进行了较全面的研究。在已有的锚索支护基础上,基于卸荷理论对设计抗剪洞的再次支护效果和和采用拟静力法模拟的抗震效果进行评估,通过不同高程的关键点的位移响应,较系统地论证抗剪洞设置的必要性。通过研究应力的变化发现锚索支护段和抗剪洞支护段之间形成较为明显的拉裂区域。对工程后期监测提出建议。 相似文献
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土体抗拉张力学特性研究进展 总被引：6，自引：0，他引：6
在传统土力学的观念中,土体通常不主动作为抗拉材料使用,土的抗拉强度很小,因而土体的抗拉强度往往被忽略或几乎视为零,造成土体抗拉强度理论远落后于抗剪强度理论。实际上,土体的抗拉张力学特性在土体变形与破坏的过程中起着非常重要的作用。总结了土体抗拉张力学特性试验的发展过程及发展特点,介绍了土体抗拉张力学试验的最新进展,并结合非饱和土力学及其抗拉强度理论的研究热点,认为对非饱和土合理统一的"吸力"认识仍然是非饱和土抗拉张特性研究的关键。然后,从岩土破坏模式角度,总结了岩土拉剪耦合破坏规律的8类破坏模式,分析了土体在此研究领域的现状,最后阐明了土体尤其是非饱和土的抗拉张力学特性研究现状的5个特点,展望了土体抗拉张力学特性新的重要研究方向。 相似文献
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当精密单点定位的观测值含有异常数据时,Kalman滤波的精度将会降低。采用抗差Kalman滤波方法能够有效抑制观测异常,提高滤波的精度和可靠性。运用武汉国际GPS服务跟踪站数据对该方法进行了验证。结果表明,抗差Kalman滤波的精度比Kalman滤波的精度有一定程度提高,说明抗差Kalman滤波能够有效抑制观测异常。 相似文献
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齿坎式挡土结构物极限抗滑力研究 总被引：1，自引：1，他引：0
以齿坎式挡土结构物的现场抗滑试验为依据,运用非线性弹性有限元方法,对齿坎长度分别为0、0.7 m和1.0 m的挡土结构物的现场试验进行了理论分析,研究了位于软弱地基中的挡土结构物中的齿坎抗滑机制,其有限元理论分析能很好地表征现场试验成果,并运用强度折减的有限元方法对齿坎式挡土结构物进行极限设计,该理论研究可为工程设计提供齿坎抗滑作用的设计理论。 相似文献
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Hybrid Estimation of Semivariogram Parameters 总被引：1，自引：0，他引：1
Two widely used methods of semivariogram estimation are weighted least squares estimation and maximum likelihood estimation.
The former have certain computational advantages, whereas the latter are more statistically efficient. We introduce and study
a “hybrid” semivariogram estimation procedure that combines weighted least squares estimation of the range parameter with
maximum likelihood estimation of the sill (and nugget) assuming known range, in such a way that the sill-to-range ratio in
an exponential semivariogram is estimated consistently under an infill asymptotic regime. We show empirically that such a
procedure is nearly as efficient computationally, and more efficient statistically for some parameters, than weighted least
squares estimation of all of the semivariogram’s parameters. Furthermore, we demonstrate that standard plug-in (or empirical)
spatial predictors and prediction error variances, obtained by replacing the unknown semivariogram parameters with estimates
in expressions for the ordinary kriging predictor and kriging variance, respectively, perform better when hybrid estimates
are plugged in than when weighted least squares estimates are plugged in. In view of these results and the simplicity of computing
the hybrid estimates from weighted least squares estimates, we suggest that software that currently estimates the semivariogram
by weighted least squares methods be amended to include hybrid estimation as an option. 相似文献
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Normal and lognormal estimation 总被引：3，自引：0，他引：3
Jean-Michel M. Rendu 《Mathematical Geology》1979,11(4):407-422
A comprehensive theoretical study of the problem of estimation of regionalized variables with normal or lognormal distribution is presented. Unbiased linear estimators are derived, under both assumptions that the population mean is known and unknown, and their error variance is calculated. The minimum variance kriging estimators are studied in more detail and are compared with the conditional expectations. The emphasis is on the study of lognormally distributed variates. The derived mathematical formulas are applicable to the optimal contouring of sample values with the appropriate distribution, as well as the optimal estimation of blocks of ore in mineral deposits. 相似文献
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Evaluation and comparison of spatial interpolators II 总被引：4，自引：0，他引：4
The performance of several variations on ordinary kriging and inverse distance estimators is evaluated. Mean squared errors (MSE) were calculated for estimates made on multiple resamplings from five exhaustive data bases representing two distinctly different types of estimation problem. Ordinary kriging, when performed with variograms estimated from the sample data, was more robust than inverse-distance methods to the type of estimation problem, and to the choice of estimation parameters such as number of neighbors.Notice: Although the research described in this article has been funded in part by the United States Environmental Protection Agency through Cooperative Agreement CR818526 to the Harry Reid Center for Environmental Studies, University of Nevada-Las Vegas, it has not been subjected to Agency review. Therefore it does not necessarily reflect the views of the Agency. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献
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在矿产勘查、矿山设计、生产及管理等各阶段都需要进行资源储量估算的工作。地质统计学方法相对于传统储量估算方法具有明显优势,在资源储量估算中获得了广泛的应用。估值过程中单元块尺寸的合理选择对储量估算结果至关重要,然而,在以往实践中块尺寸通常根据经验或主观判断进行选择,缺乏科学依据。本文在总结前人工作及地质统计学资源储量估算经验的基础上,将块尺寸的选取问题明确地划分为勘探阶段和生产阶段。针对不同阶段的特点,重点讨论了块尺寸与品位、储量、估计精度、选别开采单元的关系,为块尺寸的合理选择提供参考。并以某特大型钼矿为工程背景,进行了深度解析及数据实验,得出了块尺寸不仅影响资源品位分布、矿石量而且影响开采技术经济指标的结论,综合考虑估计精度和选别开采单元,推荐该矿床选择15m×15m×15m的单元块尺寸进行储量估算。 相似文献
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Peter K. Kitanidis 《Mathematical Geology》1985,17(2):195-208
The parameters of covariance functions (or variograms) of regionalized variables must be determined before linear unbiased estimation can be applied. This work examines the problem of minimum-variance unbiased quadratic estimation of the parameters of ordinary or generalized covariance functions of regionalized variables. Attention is limited to covariance functions that are linear in the parameters and the normality assumption is invoked when fourth moments of the data need to be calculated. The main contributions of this work are (1) it shows when and in what sense minimum-variance unbiased quadratic estimation can be achieved, and (2) it yields a well-founded, practicable, and easy-to-automate methodology for the estimation of parameters of covariance functions. Results of simulation studies are very encouraging. 相似文献
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Angelika van der Linde 《Mathematical Geology》1993,25(1):1-7
Least squares estimation (LSE) is theoretically related to quadratic unbiased estimation of variance components. It is argued that these methods of estimation of variance components essentially generalize LSE though they are not formally equivalent. 相似文献
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在固体矿产资源评价中,333、3341类资源量的估算,要正确地选择工业指标和估算方法,确定估算参数、勘查类型、工程间距,按规定圈定矿体及共生、伴生矿体,准确划分资源量类型、块段,在实际操作中遇到的具体问题要进行认真分析,合理处理,并应注意在资源量估算过程中常见的80多个问题。 相似文献
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Roland Froidevaux 《Mathematical Geology》1984,16(4):327-350
One of the tasks routinely carried out by geostatisticians is the evaluation of global mining reserves corresponding to a given cutoff grade and size of selective mining units. A long with these recovery figures, the geostatistician generally provides an assessment of the global estimation variance, which represents the precision of the overall average grade estimate, when no cutoff is applied. Such a global estimation variance is of limited interest for evaluating mining projects; what is required is the reliability of the estimate of recovered reserves or, in other words, the conditional estimation variance. Unfortunately, classical linear geostatistical methods fail to provide an easy way to estimate this variance. Through the use of simulated deposits (representing various types of regionalization)the present paper reviews and discusses the effects of changes in cutoff grade and selective mining unit size on the conditional estimation variance. It is shown that, when the cutoff grade is applied to a pointsupport (sample-size)distribution, the conditional estimation variance appears to be readily accessible by classical formulas, once the conditional semivariogram is known. However, the evaluation of the conditional estimation variance seems to be less straightforward for the general case when a cutoff is applied to the average grade distribution of selective mining units. Empirical approximation formulas for the conditional estimation variance are tentatively proposed, and their performance in the case of the simulated deposits is shown. The limitations of these approximations are discussed, and possible ways of formalizing the problem suggested. 相似文献