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381.
目前,水位流量关系受单一因素影响的拟合,已有了比较成熟的方案,但对于受多因素影响的水位流量关系的拟合,尚没有理想的方案。多方案加权模型就是基于多因素影响的水位流量关系而建立的,本文运用了系统理论方法和数理统计理论对多方案加权模型从理论上进行了分析,并通过对湖南省朗梨水文站的实测水位流量资料的拟合,对其有效性进行了探讨。 相似文献
382.
将自适应选权滤波应用到参数估计中,对于合理地选取未知参数及其方差-协方差阵的初值,提出了利用选权拟合的方法。算例结果表明,采用新方法单点定位可以在较短的时间内达到dm甚至cm级的精度。 相似文献
383.
Reducing Influence of Gravity Model Error in Precise Orbit Determination of Low Earth Orbit Satellites 总被引:1,自引:0,他引:1
GUO Jinlai HU Min ZHAO Qile GUO Daoyu 《地球空间信息科学学报》2007,10(2):105-110
Based on the orbit integration and orbit fitting method, the influence of the characters of the gravity model, with different precisions, on the movement of low Earth orbit satellites was studied. The way and the effect of absorbing the influence of gravity model error on CHAMP and GRACE satellite orbits, using linear and periodical empirical acceleration models and the so-called "pseudo-stochastic pulses" model, were also analyzed. 相似文献
384.
This work evaluates objective functions for multiresponse non-linear modeling using computersimulations.Tests are performed under a variety of signal-to-noise ratios and noise variance-covariancestructures.The standard error of prediction for the model parameters,computed from 50 trials,is usedfor performance comparisons.The full rank and rank-deficient problems are considered.For the fullrank problem one model was investigated,a first-order two-step consecutive reaction model,and twoobjective functions were considered,the total sum of squares and the determinant criterion.Nodistinction could be made between the two objective functions for this model.For the rank-deficient case two models were investigated,a first-order two-step consecutive reactionas in the full rank case,and a pH titration model described by the Henderson-Hasselbalch equation.Three objective functions were investigated for the rank-deficient case,the total sum of squares,aweighted total sum of squares and the determinant criterion.The total sum of squares was found toperform poorly under all conditions tested compared to the weighted total sum of squares and thedeterminant criterion.The determinant criterion was found to perform much better than the other twocriteria when the data have a combination of a low signal-to-noise ratio and high variance-covariancenoise structure. 相似文献
385.
Within a single well, a least-squares model such as Ø = a +bT
sonic
may be appropriate, insofar as random errors in core measurement and in sonic tool response are concerned. However, if several wells are in the reservoir, and if structural variation across the field exists, no single least-squares solution will adequately describe all wells with the same precision. Interpolation, via a cubic spline, is offered as an alternative to model this type of variation. However, to control both inter- and intra-well variability, a combination of least squares and interpolation is the model of choice. 相似文献
386.
387.
A feasibility study has been carried out to assess the potentialof an Artificial Neural Network (ANN) for determiningthe direction of incidence of an Atmospheric Cerenkov Event(ACE) from the arrival-time information registered by aspaced-array of wide-angle Cerenkov detectors. Theresults obtained so far, using both, simulated and experimental data, indicate that a properly-trained net can yield a degree of accuracy which is comparable with what is achieved through the conventional 2-minimization, wavefront-fitting procedure. 相似文献
388.
深入分析了现有的三次样条拟合方法,指出ldquo;拟合过冲rdquo;现象产生的原因,并提出新的三次样条拟合方法和正弦函数拟合方法. 这两种新拟合方法都具有消除ldquo;过冲rdquo;现象,拟合函数连续、一阶导数连续、计算简便、计算量小、易于操作等优点. 同时,指明了ldquo;端点飞翼rdquo;现象产生的原因,并提出一种处理资料曲线的端点问题的技巧. 该技巧能够在不改变资料曲线的条件下消除ldquo;端点飞翼rdquo;现象. 拟合新方法和新技巧能结合运用,得到完全没有ldquo;拟合过冲rdquo;和ldquo;端点飞翼rdquo;的拟合曲线,为时序曲线固有模态函数分解提供了可靠的技术基础. 相似文献
389.
390.