Contemporary crustal motion and deformation of South America plate     

Jin Shuanggen  Zhu Wenyao 《地球空间信息科学学报》2013,16(2):8-12

This paper presents the contemporary motion and active deformation of South America plate and relative motion of Nazca-South America plate using space geodetic data. The South America plate is moving at average 14.5 mm/a with an azimuth of 15.2° and shrinking in the west-east at 10.9 mm/a. The geodetic deformations of sites with respect to the South America plate are in quite good agreement with the estimated deformations from NNR-NUVEL1A, but the deformation of the western South America regions is very large.  相似文献   

Determination of weighted mean tropospheric temperature using ground meteorological measurements     

Liu Yanxiong  Chen Yongqi  Liu Jingnan 《地球空间信息科学学报》2013,16(1):14-18

The weighted mean tropospheric temperature is a critical parameter in the conversion of wet zenith delay to precipitable water vapor in GPS Meteorology. This parameter can not be calculated from the radiosonde data in real time through the conventional methods. In this study, we first discuss the admissible error of weighted mean temperature to enable the accuracy of the conversion better than 1 mm, then summarize the performance of some of the existing methods. An empirical formula is established that satisfies the real-time requirement in GPS meteorology using Sequential Regression Analysis method. It is shown that this real-time formula as compared with other empirical methods is more accurate for local applications.  相似文献   

Semiparametric regression and model refining     

Sun Haiyan  Wu Yun 《地球空间信息科学学报》2013,16(4):10-13

This paper presents a semiparametric adjustment method suitable for general cases. Assuming that the regularizer matrix is positive definite, the calculation method is discussed and the corresponding formulae are presented. Finally, a simulated adjustment problem is constructed to explain the method given in this paper. The results from the semiparametric model and G-M model are compared. The results demonstrate that the model errors or the systematic errors of the observations can be detected correctly with the semiparametric estimate method.  相似文献   

Improvement of theories and methods in geodetic joint inversion     

Xu Caijun 《地球空间信息科学学报》2013,16(1):12-18

This paper first establishes the prior globe dynamical model by geophysics, which is a solid earth elastic deformation model. Then, the parameters of the globe dynamic model can be obtained by inverting the geodetic data. The inverse method can be used in seismology and geology, and to make earth-quake prediction.  相似文献   

Estimation of unconfined aquifer parameters by genetic algorithms     

M. Rajesh  D. Kashyap 《水文科学杂志》2013,58(3):403-413

Abstract

Unconfined aquifer parameters, viz. transmissivity, storage coefficient, specific yield and delay index from a pumping test are estimated using the genetic algorithm optimization (GA) technique. The parameter estimation problem is formulated as a least-squares optimization, in which the parameters are optimized by minimizing the deviations between the field-observed and the model-predicted time–drawdown data. Boulton's convolution integral for the determination of drawdown is coupled with the GA optimization technique. The bias induced by three different objective functions: (a) the sum of squares of absolute deviations between the observed and computed drawdown; (b) the sum of squares of normalized deviations with respect to the observed drawdown; and (c) the sum of squares of normalized deviations with respect to the computed drawdown, is statistically analysed. It is observed that, when the time–drawdown data contain no errors, the objective functions do not induce any bias in the parameter estimates and the true parameters are uniquely identified. However, in the presence of noise, these objective functions induce bias in the parameter estimates. For the case considered, defining the objective function as the sum of the squares of absolute deviations between the observed and simulated drawdowns resulted in the best possible estimates. A comparison of the GA technique with the curve-matching procedure and a conventional optimization technique, such as the sequential unconstrained minimization technique (SUMT), is made in estimating the aquifer parameters from a reported field pumping test in an unconfined aquifer. For the case considered, the GA technique performed better than the other two techniques in parameter estimation, with the sum-of-squares errors obtained from the GA about one fourth of those obtained by the curve matching procedure, and about half of those obtained by SUMT.

Citation Rajesh, M., Kashyap, D. & Hari Prasad, K. S. (2010) Estimation of unconfined aquifer parameters by genetic algorithms. Hydrol. Sci. J. 55(3), 403–413.  相似文献   

Identification of aquifer parameters from residual drawdowns: an optimization approach     

《水文科学杂志》2013,58(6):1139-1148

Abstract

An optimization method based on nonlinear least squares is proposed for the identification of aquifer transmissivity and two storage coefficients, one for the pumping phase and the other for the recovery phase, using only residual drawdowns at an observation well. The method is applicable irrespective of whether pumping and recovery storage coefficients are the same or are different and the argument of well function during recovery is less than or greater than 0.01. The method can check for the changed value of storage coefficient during the recovery phase and can quantify this change. Use of the method is illustrated through examples, which show that the parameters are estimated reliably.  相似文献   

非线性模型参数估计的大洪水解算方法     

王永弟  丁海勇 《地理空间信息》2012,10(6):142-144,1

直接搜索算法作为非线性模型参数估计的一种求解方法,具有无需求导,适用范围更广的优点,因而成为近年来的研究热点。将大洪水算法作为一种新的直接搜索算法引入到非线性模型的参数估计中,并以实例进行了计算分析,结果表明:大洪水算法是一种简单有效的非线性模型参数估计的直接搜索解算方法,不但在算法性能上表现优越,而且解的搜索不依赖于初值,能以较大概率收敛到全局最优解,是一种值得推广的直接搜索算法。  相似文献   

月球重力场模型研究进展和我国将来月球卫星重力梯度计划实施   总被引：4，自引：0，他引：4  

郑伟  许厚泽  钟敏  员美娟 《测绘科学》2012,37(2):5-9

本文介绍了基于国际探月观测数据建立的月球重力场模型:8×4、15×8、13×13、5×5、7×7、16×16-1/2/3、Lun60d、GLGM-1/2、LP75D/G、LP100K/J、LP165P、LP150Q和SGM90d;通过对比SST-HL/LL-Doppler-VLBI和SST-HL/SGG-Doppler-VLBI跟踪观测模式的优缺点,建议我国将来首期月球卫星重力测量计划采用SST-HL/SGG-Doppler-VLBI较优;其次,通过对比静电悬浮、超导和量子卫星重力梯度仪的优缺点,建议我国将来首期月球卫星重力梯度计划采用静电悬浮重力梯度仪;并建议我国将来首颗月球重力梯度卫星的轨道高度(50～100 km)选择在已有月球探测卫星的测量盲区,轨道倾角(90°±3°)设计为有利于月球卫星观测数据全球覆盖的近极轨模式。  相似文献   

Statistical inverse analysis based on genetic algorithm and principal component analysis: Applications to excavation problems and pressuremeter tests   总被引：1，自引：0，他引：1  

S. Levasseur  Y. Malecot  M. Boulon  E. Flavigny 《国际地质力学数值与分析法杂志》2010,34(5):471-491

This study concerns the identification of constitutive models from geotechnical measurements by inverse analysis. Soil parameters are identified from measured horizontal displacements of sheet pile walls and from a measured pressuremeter curve. An optimization method based on a genetic algorithm (GA) and a principal component analysis (PCA), developed and tested on synthetic data in a previous paper, is applied. These applications show that the conclusions deduced from synthetic problems can be extrapolated to real problems. The GA is a robust optimization method that is able to deal with the non‐uniqueness of the solution in identifying a set of solutions for a given uncertainty on the measurements. This set is then characterized by a PCA that gives a first‐order approximation of the solution as an ellipsoid. When the solution set is not too curved in the research space, this ellipsoid characterizes the soil properties considering the measured data and the tolerate margins for the response of the numerical model. Besides, optimizations from different measurements provide solution sets with a common area in the research space. This intersection gives a more relevant and accurate identification of parameters. Finally, we show that these identified parameters permit to reproduce geotechnical measurements not used in the identification process. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

钻机性能参数测试系统的研制          下载免费PDF全文

丁景祥 《探矿工程》2010,37(6):45-49

简要介绍了新研制钻机性能试验装置的测试技术方法、构成,测试试验台架、加载装置、加载控制器、测试控制系统等。  相似文献