共查询到18条相似文献，搜索用时 156 毫秒
1.
利用遥测系统实时监测水情资料,由于遥测系统自身的原因以及水文要素测量的具体要求,数据常常携带异常误差。采用有异常误差的实测流量资料对实时校正模型进行参数辨识,要求算法既能抵御异常误差的影响,又具有较强的实时跟踪能力,以适应实时洪水预报的要求。在递推最小二乘算法的基础上,引入抗差理论,削弱异常值对参数估计的影响;引入遗忘因子,实时跟踪模型时变参数的变化。计算实例表明,带有遗忘因子的抗差递推最小二乘算法对异常误差不敏感,又具有较强的实时跟踪能力。 相似文献
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赵超 《中国科学院研究生院学报》2010,27(4):556-562
用于估计马斯京根模型参数的方法很多,但这些方法在数据存在异常值时缺乏抵御异常值影响的抗差性能. 推导出一种有限制条件的参数抗差估计算法,通过含有随机误差和异常误差的人工数据和真实数据比较抗差算法与传统最小二乘算法的抗差性. 研究表明抗差估计算法能减小异常值对参数估值的影响. 相似文献
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在测量平差过程中,一般都是对一系列带有偶然误差的观测值,运用概率统计的方法来消除观测值之间的不符值。对于与偶然误差同时存在的各种系统误差,在观测过程中采用相应的方法来消除或减弱其对观测成果的影响,同时用闭合差时候超限来检验观测值中是否含有粗差。数据探测法是利用统计假设检验的原理来对粗差进行探测,从而剔除探测出的粗差。由于该方法计算比较方便,已广泛应用于测量平差中。 相似文献
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缺资料地区日降雨时间上向下尺度化方法探讨 总被引：4，自引：0，他引：4
降雨是流域水循环的主要影响因子之一,雨强时程分布对于流域水循环具有重要的意义,在相同的下垫面条件下,如果降雨强度不同,产流机制也会出现很大的不同.然而,要想获得完整长系列的短历时降雨资料,难度很大.本文以黄河流域为例,提出了日降雨时间上向下尺度化模型,探讨了缺资料地区通过日雨量在时间上向下尺度化生成短历时降雨资料的方法.文中根据黄河流域降雨特点,把全流域分成5个降雨区划,采用1991年～1997年731个站点大于10mm雨日的短历时降雨记录,对向下尺度化模型的参数进行了分区率定和分析.通过分析实测短历时降雨资料发现,黄河流域日降雨量和历时相关关系很差,相比而言,与雨强相关关系较好.文中建立了1个日雨量～雨力关系模型,并分区率定了模型的参数.日降雨时间上向下尺度化模型的参数反映了雨强日内分布的集中程度,大体趋势是从西到东增强的.本文采用Nash-Sutcliffe效率系数和MSEQ两种指标对模型进行了评估,分区统计结果显示,提出的模型和方法是有效的,下一步的工作是在流域水文模拟中进行应用和作进一步地验证. 相似文献
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【目的/意义】在大数据分析过程中,异常值探测是非常重要的一类分析方法。大数据分析中的异常值探测
是从海量、不完整的、有噪声的、随机的海量数据中发现与其它数据显著不同的或潜在有价值的信息和知识的过
程。对异常值探测方法及其应用进行系统梳理,以期为相关研究提供有益借鉴。【方法/过程】首先针对当前大数据
分析相关研究中常用的异常值探测方法进行分类梳理,并通过原理图来解释各种异常值探测方法的基本思想和原
理,然后结合相关算法给出大数据分析时异常值探测方法的实际应用,最后将各种异常值探测方法的特征进行对
比分析。【结果/结论】各种异常值探测算法在实际问题中应该根据其特点有选择地应用。指出未来研究方向包括：
对算法自身的研究和对应用领域的拓展。 相似文献
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磁法勘探是地球物理勘探的重要分支,它是通过观测和分析由岩石、矿石或其他探测对象磁性差异所引起的磁异常,进而研究地质构造及矿产资源或其他探测对象分布规律的地球物理方法。2012年我单位在辽宁省铁岭县三道林子矿区开展矿工作,在工作过程中,对本矿区采用1：10000 高精度磁法测量扫面工作,了解矿区内磁铁石英岩捕虏体在混合岩内的分布情况,在对所取得的磁测成果进行资料整理利用磁场强度变化特征,研究磁异常的展布规律,为在矿区内开辰铁矿找矿工作提供依据。 相似文献
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通过珲春河流域长系列降雨资料,统计计算多年平均降水量。分析降水的时空分布特征;用各分区逐年降水量系列进行频率计算,求得不同频率的年降水量;利用最大年降水量与最小年降水量比值来分析降水量的年际变化特征,并通过降水的趋势分析得出降水变化不明显结论。 相似文献
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隧道的岩溶突水灾害频繁发生,为了探明隧道岩溶分布,多种物探方法应用于隧道岩溶水害探测。本文利用大地电磁测深法、高密度电法和瞬变电磁法探测溆怀高速燕子洞隧道的岩溶分布。三种物探方法对根据地下介质的电阻率差异的地球物理特征,则充水溶洞是为低阻异常体。在大地电磁法的E1、E3测线,高密度电法的G1、G2测线,瞬变电磁的S1和S3测线有明显的异常反应,有效准确的探明的隧道的岩溶通道的分布情况。 相似文献
11.
Bilić-Zulle L 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2011,21(1):49-52
The comparison of methods experiment is important part in process of analytical methods and instruments validation. Passing and Bablok regression analysis is a statistical procedure that allows valuable estimation of analytical methods agreement and possible systematic bias between them. It is robust, non-parametric, non sensitive to distribution of errors and data outliers. Assumptions for proper application of Passing and Bablok regression are continuously distributed data and linear relationship between data measured by two analytical methods. Results are presented with scatter diagram and regression line, and regression equation where intercept represents constant and slope proportional measurement error. Confidence intervals of 95% of intercept and slope explain if their value differ from value zero (intercept) and value one (slope) only by chance, allowing conclusion of method agreement and correction action if necessary. Residual plot revealed outliers and identify possible non-linearity. Furthermore, cumulative sum linearity test is performed to investigate possible significant deviation from linearity between two sets of data. Non linear samples are not suitable for concluding on method agreement. 相似文献
12.
Xianqiang Yang Weili Xiong Junxia Ma Zeyuan Wang 《Journal of The Franklin Institute》2017,354(13):5678-5693
This paper considers the parameter estimation for Wiener time-delay systems with the output data contaminated with outliers. The time-delay and corrupted output data bring great challenges to the parameter estimation problem. The statistical model of the estimation problem is constructed based on the Laplace distribution and the identification problem is formulated in the scheme of the expectation-maximization (EM) algorithm. The negative effect of outliers imposed on the parameter estimation problem is sufficiently suppressed and the unknown time-delay and model parameters can be estimated simultaneously. The simulation example is given to demonstrate the effectiveness of the proposed algorithm. 相似文献
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分别用T213和AVN全球分析资料提供初始场的猜值和侧边界条件，利用MM5V3中尺度模式对2002年9—11月气象资料进行模拟试验，重点分析两种方案对强降水中心、降水分布的模拟能力，并相对实测降水、地面和高空基本气象要素的观测进行了统计检验。通过对比发现，采用不同的大尺度模式提供的初边值，对区域天气预报是有显著影响的。 相似文献
14.
Peng Yun Panlong Wu Xingxiu Li Shan He Kai Wu 《Journal of The Franklin Institute》2021,358(8):4503-4527
For target tracking systems, the probability of detecting a target is difficult to determine, and the process noise often has non-Gaussian heavy-tailed characteristics owing to interference from outliers. To address the issues associated with single target tracking within clutters in scenarios with an unknown detection probability and heavy-tailed process noise, this paper presents a variational Bayesian-based adaptive probabilistic data association filter (VB-APDAF). The beta distribution, Pearson type VII distribution and multinomial distribution are used to model the detection probability, the process noise, and the association events, respectively. To guarantee the conjugation, a novel parameter estimation strategy is employed. In this strategy, the previous state is introduced in the state update process to construct the joint probability density function of parameters to be estimated and data set. The VB framework is used to estimate the target state, detection probability, and associated events. An experiment was performed under simulated conditions to demonstrate the effectiveness of the proposed filter. 相似文献
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为了提高高维数据集合离群数据挖掘效率,在分析了传统的离群数据挖掘算法优点和缺点的基础上,提出了一种离群点检测算法,首先将非线性问题转化为高维特征空间中的线性问题,然后利用非线性数据变换进行维数约减,对从高维采样数据中恢复得到低维数据集,通过本文提出的离群数据假设,并结合本文给出的离群聚类方法对所得数据对象投影分量是否是离群数据进行判别。仿真实验的结果表明了该方法能够有效地发现高维数据集中的离群点。与此同时,该算法具有参数估计简单、参数影响不大等优点,为离群点检测问题的机器学习提供了一条新的途径。 相似文献
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《Journal of The Franklin Institute》2023,360(7):4493-4518
This paper presents a new robust multiplicative watermark detector. Due to the strong robustness against various attacks, polar harmonic Fourier moment (PHFM) magnitudes are used as the employed watermark carrier. The distribution of PHFM magnitudes is highly non-Gaussian and can be properly modeled by a heavy-tailed probability density function (PDF). In this paper, we proved that Weibull distribution can suitably fit the distribution of PHFM magnitudes, and based on this, we presented a statistics-based watermark decoder by using the Weibull as a prior for the PHFM magnitudes. In watermark embedding, a multiplicative manner was used to embed watermark information in PHFM magnitudes of the highest entropy blocks to achieve better robustness and imperceptibility. In watermark detection, we developed a Weibull distribution-based statistical watermark decoder, which uses the maximum likelihood (ML) decision rule. Compared with Bessel K form (BKF), Cauchy, and generalized Gaussian (GG)-based decoders, the Weibull-based decoder demonstrates stronger robustness. In addition, the proposed watermark decoder is more robust against geometrical and common image processing attacks than existing statistical watermark decoders. 相似文献
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Robust identification of the linear parameter varying (LPV) finite impulse response (FIR) model with time-varying time delays is considered in this paper. A robust observation model based on Laplace distribution is established to deal with the output data contaminated with the outliers, which are commonly existed in modern industries. A Markov chain model is utilized to model the correlation between the time delays as they do not simply change randomly in reality. A transition probability matrix and an initial probability distribution vector are used to govern the switching mechanism of the time delays. Since it is difficult to optimize the complex log likelihood function directly, the derivations of the proposed algorithm are performed under the framework of Expectation-Maximization (EM) algorithm. A numerical example and a chemical process are utilized to verify the effectiveness of the proposed approach. 相似文献
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利用淮河流域1960-2008年141个气象站的日降水资料,以及王家坝和吴家渡水文站的日实测流量资料,分析研究时段内淮河流域面雨量时空变化特征及水文站实测径流量的响应,初步探讨实测径流量与降水的相关关系。结果表明,1960-2008年淮河流域面雨量呈增加趋势,但增加趋势不显著。淮河流域面雨量年内分配极不均匀,有显著的季节变化,且年际变幅大,区域差异明显。与面雨量相对应,淮河中上游主要水文站实测径流量存在明显年际震荡,这种年际差异在淮河中游更为显著,水资源更加不稳定。近50年来淮河中上游径流量变化趋势和其汇水区域面雨量变化趋势基本一致,两者呈显著的正相关,降水是影响该区域实测径流的一个重要因素,人类活动对实测径流的影响不明显。 相似文献