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761.
762.
以点位误差描述线元位置不确定性的误差带方法 总被引:1,自引:1,他引:0
从实用的角度出发,提出按两端点的点位误差描述线元误差带的方法.主要内容包括对各种情况加以解释并给出各种不同情形的统一公式. 相似文献
763.
The groundwater inverse problem of estimating heterogeneous groundwater model parameters (hydraulic conductivity in this case) given measurements of aquifer response (such as hydraulic heads) is known to be an ill-posed problem, with multiple parameter values giving similar fits to the aquifer response measurements. This problem is further exacerbated due to the lack of extensive data, typical of most real-world problems. In such cases, it is desirable to incorporate expert knowledge in the estimation process to generate more reasonable estimates. This work presents a novel interactive framework, called the ‘Interactive Multi-Objective Genetic Algorithm’ (IMOGA), to solve the groundwater inverse problem considering different sources of quantitative data as well as qualitative expert knowledge about the site. The IMOGA is unique in that it looks at groundwater model calibration as a multi-objective problem consisting of quantitative objectives – calibration error and regularization – and a ‘qualitative’ objective based on the preference of the geological expert for different spatial characteristics of the conductivity field. All these objectives are then included within a multi-objective genetic algorithm to find multiple solutions that represent the best combination of all quantitative and qualitative objectives. A hypothetical aquifer case-study (based on the test case presented by Freyberg [Freyberg DL. An exercise in ground-water model calibration and prediction. Ground Water 1988;26(3)], for which the ‘true’ parameter values are known, is used as a test case to demonstrate the applicability of this method. It is shown that using automated calibration techniques without using expert interaction leads to parameter values that are not consistent with site-knowledge. Adding expert interaction is shown to not only improve the plausibility of the estimated conductivity fields but also the predictive accuracy of the calibrated model. 相似文献
764.
We study the effect of eccentricity and inclination on small amplitude librations around the equilibrium points L
4 and L
5 in the circular restricted three-body problem. We show that the effective libration centres can be displaced appreciably
from the equilateral configuration. The secular extrema of the eccentricity as a function of the argument of pericentre are
shifted by ∼25 °
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
765.
766.
Jacques Henrard 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):291-302
We describe and comment the results of a numerical exploration of the numerous natural families of periodic orbits associated with the L
4 equilibrium point of the restricted problem of three bodies (and of course by symmetry those associated with the L
5 equilibrium point). These families are organized in a very structured network or coweb and this structure evolves, when the mass ratio varies, in a very organized way. 相似文献
767.
Fractal geometry is receiving increased attention as a model for many natural phenomena. In this paper, we address two issues in dealing with unorganized 3-D measured data using fractal geometry: extraction of fractal characters and fractal surface (geochemical landscapes) reconstruction. We start from a set of randomly measured 3-D data on a plane. After classification and concentration of the input data, we present methods for estimating the fractal dimension and texture deviation as fractal characters, and then an improved subdivision scheme is developed to reconstruct fractal surface on the basis of the extracted fractal characters. We demonstrate both characterization and reconstruction with irregularly measured geochemical data from 1767 stream sediment samples in the middle district (450km2 in area) of Zhejiang, China. 相似文献
768.
B. Andrew Haggart 《第四纪科学杂志》1989,4(1):67-76
Differences in the timing of maxima and minima and shape between sea-level curves from the western Forth valley, lower Strathearn, inner Moray Firth and eastern Solway Firth areas of Scotland are interpreted as being due to differences in isostatic uplift and different methodologies used to interpret the basic data. Possible changes in the relative rates of uplift between areas suggest that the practice of applying the western Forth ‘model’ of relative sea-level change to other parts of Scotland must be questioned. 相似文献
769.
In this paper, we investigate a generalization of the Hill's problem to the case where no restriction is made about the nature of the field of force perturbing two small bodies in gravitational interaction. We apply the general equations obtained to the dynamics of two bodies located in the vicinity of the triangular lagrangian points of the restricted three-body problem. 相似文献
770.
交会法测定水平位移的精度分析 总被引:5,自引:0,他引:5
对目前常用的几种典型交会测量方法进行了理论上的精度分析 ,并利用某大坝水平位移监测点的实测数据进行分析、验证 ,得出了一些有益的结论。 相似文献