A practical method for outlier detection in autoregressive time series modelling

A practical method is developed for outlier detection in autoregressive modelling. It has the interpretation of a Mahalanobis distance function and requires minimal additional computation once a model is fitted. It can be of use to detect both innovation outliers and additive outliers. Both simulated data and real data re used for illustration, including one data set from water resources.     

伽师强震群活动过程中喀什台地磁加卸载响应比变化特征研究

应用地磁响应比方法 ,分析计算了喀什地磁台 1996— 1999年地磁资料 ,结果表明在伽师强震前地磁场有明显的异常 ,这为震磁信息提取和异常判断提供了依据     

用模式识别方法划分辽宁及其邻区的潜在震源区

采用Cora-3修改方法和Hamming方法对辽宁及其邻区的地震地质、地球物理场和地震活动性特征进行研究,划分了6级、6.5级和7级以上潜在震源区,两种方法所得结果基本一致。经k值试验、删除对象试验和删除特征试验,均表明结果比较稳定可靠。这一成果弥补了辽宁地区这方面工作的不足,并为确定辽宁及其邻区的潜在震源区提供了依据     

中国西部及西部边缘Ms≥7．0级地震关系研究

本文研究了中国西部及西部边缘地区Ｍｓ≥７．０级地震在共同应力场源作用下的活动特点和相互关系，指出了两区地震活动具有可类比性。同时，分析了西部区域地震活动，建立了地震活动的动态规律：门限自回归模型，所得结论对评估西部地区的地震形势具有一定价值的指导意义。     

Threshold of coarse sediment transport in broad and narrow natural streams

The threshold of coarse sediment transport has been examined in natural streambeds in an upland Pennine (U.K.) area. Threshold values of the total boundary shear stress (T₀) (for a given grain size), in a narrow natural stream (W/D < 11) are considerably higher than values of T₀ in a broad stream (W/D > 11). Efficiency in the entrainment process is related not only to the overall channel geometry, but also varies as a function of discharge in channels characterized by compound roughness. Empirical curves relating T₀ and a mean grain size (d ₅) are presented, but are limited in application to streams of similar physical and hydraulic characteristics as the ones examined in this investigation. Considerable divergence is noted between these empirical functions and a summary empirical function for general application obtained from a published source. The reasons for this divergence are discussed. The influence of grain shape was found not to be important in the initiation of motion criterion. This conclusion may reflect the limited range of natural grain shapes in the study streams, but might reasonably apply to other field investigations of similar streams. Modifications of the Shields' and Yalin diagrams are suggested for practical applications in shallow streams with poorly-graded bed material. The Shields' parameter may be regarded as an inverse function of the relative protrusion of individual grains in the shallow flow depth (d ₅/D). The increased importance of augmented drag forces, in the entrainment process in shallow flows, is suggested as the physical explanation for the reduced values of the Shields' parameter. However, the relationships presented should not be applied to laboratory experiments concerned with well-graded sediments (therefore beds with little deviation in level), in which the Shields' parameter may be regarded as constant at high Reynolds' grain numbers. Consistent estimated field values of ?, a threshold sediment transport parameter, might be used to compare field data to threshold values derived from statistical arguments and laboratory experiments reported in the literature.     

FORMULAS FOR INCIPIENT MOTION OF MUD WITH VARIOUS DENSITIES

ＦＯＲＭＵＬＡＳＦＯＲＩＮＣＩＰＩＥＮＴＭＯＴＩＯＮＯＦＭＵＤＷＩＴＨＶＡＲＩＯＵＳＤＥＮＳＩＴＩＥＳＹＡＮＧＭｅｉｑｉｎｇａｎｄＷＡＮＧＣｕｉｌｉｎｇＡｂｓｔｒａｃｔ：Ｍｕｄｆｏｒｍｅｄｆｒｏｍｆｉｎｅｃｏｈｅｓｉｖｅｓｅｄｉｍｅｎｔｓｃａｎｈａｖ...     

沙土含水率对起沙临界风速影响

根据重力、凝聚力与拖曳力的力矩平衡关系，推导出起沙临界风速与粒径和沙土含水率的关系，并分析了含水率对起沙临界风速的定量作用     

具有时变参数的门限自回归模型及其在气候预报中的应用

将时变参数模型引入门限自回归模型中，提出具有时变参数的门限自回归模型，并对昆明，蒙自，河口等地区３月温度序列进行预报，结果表明：这种模型比门限自回归模型的预报准确度有明显提高，这是因为用这种模型进行预报时，可以随时更新预报模式。     

2000年前辽宁地区地震活动趋势预测

根据数理统计理论和有关文献，利用辽宁地区（３８．７°－４３°Ｎ，１１９°－１２５°Ｅ）１９７０年以来的地震资料，建立了逐年最高震级时间序列的门限自回归模型和修改的震级一频度关系。同时，对辽宁地区地震活动的时空分布特征也作了详细的研究。最后，对辽宁地区未来（到２０００年）地震活动趋势和强度作了预测。