Maximum likelihood environmental calibration and the compute program WACALIB a correction

A recently discovered error in the part of the computer program WACALIB that implements maximum likelihood (ML) calibration has been discovered and corrected. The new version of WACALIB has been re-run with all the data-sets from which results based on the earlier version of WACALIB had been published. The new results suggest that ML regression and calibration perform as well or even better than weighted averaging (WA), at least when judged by the apparent root mean squared error. Further work involving cross-validation is required to evaluate more fully the relative performance of WA and ML approaches.     

Modelling peak accelerations from earthquakes

This paper deals with the prediction of peak horizontal accelerations with emphasis on seismic risk and insurance concerns. Non‐linear mixed effects models are used to analyse well‐known earthquake data and the consequences of mis‐specifying assumptions on the error term are quantified. A robust fit of the usual model, using recently developed robust weighted maximum likelihood estimators, is presented. Outlying data are automatically identified and subsequently investigated. A more appropriate model accounting for the extreme value nature of the responses, is also developed and implemented. The implication on acceleration predictions is demonstrated. Copyright © 2006 John Wiley & Sons, Ltd.     

回归预测模型的稳健性讨论--以润扬大桥工程为例

经典的LS估计法(least squares estimation,LS estimation)是对每个观测数据都给予相同的权重,由此带来了对于异常值的处理不当,从而影响了回归模型的有效性,本文采用迭代加权最小二乘法来进行稳健估计(RobustEstimation),并基于MATLAB软件结合润扬大桥工程实例说明了此法的有效性。     

方向数据插值方法研究

方向数据是矢量数据的标量表示,通常标量数据的插值方法不适用于方向数据。本文根据方向数据的特征,把其分解成沿坐标轴的分量,通过对分量数据的插值形成表面,最后合成反算出方向数据,给出了一种对于方向数据的行之有效的插值方法;并用实验进行了验证,对其插值结果和精度进行了统计和分析,取得了较为理想的内插结果。     

Ordered weighted averaging with fuzzy quantifiers: GIS-based multicriteria evaluation for land-use suitability analysis

The objective of this paper is to incorporate the concept of fuzzy (linguistic) quantifiers into the GIS-based land suitability analysis via ordered weighted averaging (OWA). OWA is a multicriteria evaluation procedure (or combination operator). The nature of the OWA procedure depends on some parameters, which can be specified by means of fuzzy (linguistic) quantifiers. By changing the parameters, OWA can generate a wide range of decision strategies or scenarios. The quantifier-guided OWA procedure is illustrated using land-use suitability analysis in a region of Mexico.     

偏重钻铤在丁集矿冻结造孔施工中的应用

钻井技术的关键是预防及控制孔斜,通过对目前常用4种防斜钻具组合的适岩性、井深、井斜及钻效等指标对比,在冻结造孔施工中选用了适用地层广、防斜性能好并具有纠斜作用的偏重钻铤。为发挥偏重钻铤的防斜作用,宜增大转速,并使钻铤减去部分的重量应位于离轴线尽可能远的部位。在淮南丁集冻结孔施工的三十多口钻孔中,井斜一般均在0．5°以内,钻效超过2400m/台·月。     

加权支持向量回归机及其在水质预测中的应用

支持向量机是一种基于结构风险最小化原理的学习技术，也是一种新的具有很好泛化性能的回归方法。本文对用于回归估计的标准支持向量机加以改进，提出了一种新的用于回归估计的支持向量机学习算法，针对各样本重要性的差异，给各个样本的惩罚系数和误差要求赋予不同权重，并利用加权支持向量回归机的理论及其算法构建水质预测模型。实验结果表明，该方法对水质具有较好的预测效果。     

THE APPROACH TO REMOTE SENSING OF WATER VAPOR BASED ON GPS AND LINEAR REGRESSION T_m IN EASTERN REGION OF CHINA

The approach to remote sensing of water vapor by using global positioning systems(GPS)isdiscussed.In order to retrieve the vertical integrated water vapor(IWV)or the precipitable water(PW),the weighted“mean temperature”of the atmosphere,T_m would be estimated to the specificarea and season.T_m depends on surface temperature,tropospheric temperature profile,and thevertical distribution of water vapor.The surface temperature dependence is borne out by acomparison of T_m and the values of surface temperature T_s using radiosonde profiles of BeijingStation(No.54511)throughout 1992.The analysis of radiosonde profiles spanning a one-yearinterval(1992)from sites in eastern region of China with a latitude range of 20-50°N and alongitude range of 100-130°E yields the coefficients α and b of a linear regression equation T_m=α bT_s.     

A Single-Station Spectral Model of the Monthly Median foF2 and M(3000)F2

A new single-station model (SSM) for monthly median values of the ionospheric parameters foF2 and M(3000)F2 has been developed. Fourier analysis provides a tool for decomposing the time-varying ionospheric parameters. The 12–month smoothed sunspot number R ₁₂ was used as an external solar characteristic because of its availability and predictability. However, for the first time, the solar activity is described not only by R ₁₂ , but also by the linear coefficient K _R representing the tendency of the change of solar activity. A general non-linear approximation of the influence of the solar-cycle characteristics R ₁₂ and K _R and ionospheric parameters foF2 and M(3000)F2 was accepted. The new SSM is applied to several European stations and its statistical evaluation shows better results than the other two SSMs used in the paper. The approach described in the paper does not contradict the use of different synthetic ionospheric indices (as the T-index, MF2–index); the basic aim is to show only that using one additional new characteristic of the solar-cycle variations, such as K _R , improves the monthly median model.