On the joint robust estimation of parameters and variance     

Jia Pei-zhang 《Chinese Astronomy and Astrophysics》1992,16(4):465-472

A method of joint estimation of the parameters and the variance σ² in the linear model is presented in this paper. The M-estimators with finite rejection points are adopted for estimating the parameters. In order to estimate the variance σ², the Grubbs statistics and the Kurtosis test statistics are adopted to test the residual sequence {;r_i};. And the sample variance of {;r_i}; after discarding the outliers is taken as the estimation of σ². This method of estimating σ² is less computational demanding and more accurate, compared with the well-known method which takes 1.483 med_i |r_i| as the estimation of σ. The breakdown point of the above estimation of σ² is more than 20%, while the brekdown point is less than 10%, if only the Grubbs statistics is used.  相似文献   

应用三轴风速仪研究成都平原大气扩散参数及结果分析     

靳小兵  陈永林  曾涛 《成都信息工程学院学报》1992,(1)

本文介绍了应用三轴风速仪测试大气扩散参数的方法和原理,计算了成都平原大气扩散参数,并对其结果进行了分析,提出了本地区应用三轴风速仪可以代替平衡球的依据,并对三轴法的优缺点进行了评价。指出了以往将静风与有风时处理混为一起的不合理性。  相似文献   

抚松大营铅锌矿床同位素地质特征及矿床成因     

于长霞 《吉林地质》1990,(3)

本文主要通过对抚松大营铅锌矿床同位素特征的研究,讨论了成矿物质来源、成矿流体性质、岩浆活动对成矿作用的影响,从而证明矿床成因属沉积—热液叠加型层控矿床。  相似文献   

张强凹陷长北背斜生油岩有机地球化学特征     

商出岫  姚丹姝  王瑞璞 《国土资源》1996,(4)

张强凹陷长北背斜侏罗系上统有沙海组和九佛堂组两套生油合系，其有机质丰度属中等，沙海组生油岩多为腐泥腐殖型．地球化学分析表明，沙海组下段的生油岩处于低熟—成熟阶段，该地区各层原油主要来源于侏罗系上统沙海组下段生油岩．  相似文献   

Source parameters of some large earthquakes in the eastern Mediterranean region based on an itertive maximum entropy technique     

G. N. Stavrakakis  S. V. Blionas 《Pure and Applied Geophysics》1990,132(4):679-698

TeleseismicP-waves of some large earthquakes that occurred in the eastern Mediterranean region have been analysed by using an iterative maximum entropy technique in order to obtain the independent spectral parameters, the long-period spectral level ₀ and the corner frequencyf ₀ of the far-field displacement spectra.Based on these parameters, the seismic source parameters seismic momentM ₀, source dimensionr, fault lengthl, average displacement u, shear stress drop , radiated energyE _s and apparent stressn are calculated for the considered earthquakes by using Brune's and Madariaga's models.The striking feature of the source parameters obtained in this study is the low stress drop value which varies between 5 and 15 bars. If Madariaga's model had been used, higher stress drop values would have been obtained.The low stress drop earthquakes in the eastern Mediterranean region might be interpreted either by the possible presence of low strength material near the source or by the partial stress drop model.  相似文献   

鲁中地区分类强对流天气环境参量特征分析   总被引：13，自引：3，他引：10  

高晓梅  俞小鼎  王令军  王文波  王世杰  王新红  韩晓 《气象学报》2018,76(2):196-212

将山东中部地区16 a暖季(4-9月)106次伴随瞬时风力不低于8级的强对流个例划分为雷暴大风、冰雹雷暴大风和强降水混合型等3种类型,利用常规探空资料和地面观测资料,通过箱须图的形式分别讨论3种类型对应的一系列关键环境参数的分布特征和预报阈值。进一步,又将上述106次个例中的特强对流个例,包括产生25 m/s以上瞬时大风的特强雷暴大风个例、产生不小于20 mm直径冰雹的特强冰雹个例以及50 mm/h或以上强度的特强短时强降水个例提取出来构成一个子集,讨论其关键环境参数分布特征和预报阈值,并与全部对流个例的相应关键环境参数进行比较。最后,对鲁中地区强对流系统的触发机制进行了简要阐述和讨论。结果表明:(1)雷暴大风型、冰雹雷暴大风型和强降水混合型对应的850和500 hPa温差的最低阈值为25℃; 3种类型对应的地面露点最低阈值分别为13、16和24℃; 相应的大气可降水量最低阈值分别为20、24和32 mm; 相应对流有效位能的最低阈值分别为300、900和1300 J/kg; 相应的0-6 km风垂直切变最低阈值分别为12.0、12.5和8.0 m/s。(2)通过地面露点、大气可降水量以及暖云层厚度等关键参数的分布特征可以将上述3种类型的前两种与第3种类型即强降水混合型进行一定程度的区分,但要通过各个关键参数的分布特征区分前两种强对流天气是困难的。(3)对于伴随冰雹的强对流天气,适宜的融化层高度为3.0-3.9 km; (4)特强雷暴大风、特强冰雹和特强短时强降水等3种特强对流类型与全部强对流个例的3种类型相比,其条件不稳定度明显增大,体现为850和500 hPa温差的增大、水汽条件有所加强、对流有效位能明显增大,3种类型特强对流天气对应的对流有效位能最低阈值分别为1000、1100和2000 J/kg; 相应的0-6 km风垂直切变最低阈值分别为16、12和11 m/s,即特强雷暴大风型和特强短时强降水型的风垂直切变阈值明显增大。上述工作构成了山东中部伴随雷暴大风的强对流天气短时预报的一个基础,结合各类强对流天气发生的气候概率,可以通过决策树或模糊逻辑方法制作成适合于地、市气象台的分类强对流天气短时预报系统。   相似文献   

A New Sensitivity Analysis Approach Using Conditional Nonlinear Optimal Perturbations and Its Preliminary Application     

Qiujie REN  Mu MU  Guodong SUN  Qiang WANG 《大气科学进展》2023,40(2):285-304

Simulations and predictions using numerical models show considerable uncertainties, and parameter uncertainty is one of the most important sources. It is impractical to improve the simulation and prediction abilities by reducing the uncertainties of all parameters. Therefore, identifying the sensitive parameters or parameter combinations is crucial. This study proposes a novel approach: conditional nonlinear optimal perturbations sensitivity analysis(CNOPSA) method. The CNOPSA method fully consi...  相似文献   

藏东南大气中多环芳烃的污染特征及来源分析     

罗汉  张强  岳平  奚立宗  刘琴  尹春  王元兵  秦豪君  王琦  李宝梓  王劲松 《大气科学》2023,(3):853-865

为探究青藏高原东南部大气中多环芳烃(Polycyclic Aromatic Hydrocarbons,简称PAHs)的污染、源及输送特征,利用鲁朗地区(29.77°N,94.73°E)总悬浮颗粒物(Total Suspended Particles,简称TSP)和大气中的14种PAHs含量,结合同期气象环境数据进行了综合分析。结果表明,该地区TSP中PAHs和气相的PAHs质量浓度变化范围分别为0.22～5.05 ng m^-3和0.83～63.75 ng m^-3,平均值分别为2.13 ng m^-3和11.33 ng m^-3。薪柴和柴油的燃烧是污染的主要方式,汽油燃烧等其他排放为次要方式。PAHs来自本地污染和远距离传输(Long Range Transmission,简称LRT)共同的影响。本地污染在四季各个源地均不相同。冬春季本地污染大,源在东南及正南方,夏秋季受本地和外来输送共同作用,本地源在东南方且占比小,LRT占比大。LRT受西北气流、西风气流和西南气流三支气流影响,污染严重时西南气流占主导...  相似文献   

烃源岩评价分析项目的优化组合   总被引：1，自引：0，他引：1  

曹寅  钱志浩  张渠 《海相油气地质》2008,13(3)

在我国石油天然气行业中,对烃源岩评价的实验分析技术已形成一套比较成熟的方法,其中大部分已制订成国家标准或行业标准。但是在实际过程中,或者是全面测试,以致浪费大、收益小,或者是为过度节约而少测样品,造成信息严重丢失。为了分析测试能既节约成本又成果优秀,对各分析项目依据其有效性和局限性,分为基本项目、选择项目和补充项目三大类。针对不同的研究目的,分别提出了烃源岩样品快速筛选分析、烃源岩系统评价分析、下古生界海相烃源岩研究分析等相关实验测试分析项目的优化组合设计方案。  相似文献   

Rupture line and damage effects in Aqaba area, Egypt     

El-Sayed Mohamed Salem 《Arabian Journal of Geosciences》2008,1(2):97-110

Strong-motion parameters, peak ground acceleration, peak ground velocity, and peak ground displacement depend on several factors, such as the source of earthquake, distance between the source and site, and the characteristics of that site. Five seismographs and two accelographs were installed by the Egyptian Geological Survey team along the western side of the Gulf of Aqaba from Taba to Sharm El-Sheikh to record seismic events during the period from September 1995 to June 1996. During this period, two events were recorded by the accelographs. The two accelographs were located on the surface of the basement rocks, the first near the epicenter and the second at a farther distance. However, the farthest accelograph recorded higher values compared to the nearer one. Fault mechanics are an important factor in determining the values of strong motion parameters, where the direction of the rupture line plays an important role in detecting the values of strong motion parameters, the strong motion parameters and damage effects seem to be attenuated very fast in the direction perpendicular to the rupture line. This can be interpreted by the fact that the farthest accelograph lies at the extension of the fault rupture (azimuth = 30°), while the nearer one was perpendicular to the strike of the fault rupture.  相似文献