基于特征层融合的高光谱图像异常检测算法研究   总被引：1，自引：0，他引：1  

李智勇  匡纲要  皱焕新  吴昊 《遥感学报》2003,7(3):304-308

介绍了一种基于特征层融合的异常检测算法。目前，其他的目标检测算法都需要知道有确定类别标记的样本，而一般的异常检测则是利用统计特征差异分割出图像中不同于背景的点。此方法减少了对先验信息的依赖，但是其结果存在较大虚警。提出的异常检测算法是利用低概率检测算法对高光谱数据先进行特征层融合，再进行分割、提取异常点，其结果降低了虚警和漏警。用这一方法对OMIS系统产生的数据进行了处理，取得了较好的结果。  相似文献   

Aftershocks hazard in Italy Part I: Estimation of time-magnitude distribution model parameters and computation of probabilities of occurrence     

Barbara Lolli  Paolo Gasperini 《Journal of Seismology》2003,7(2):235-257

We analyzed the available instrumental data on Italian earthquakes from1960 to 1996 to compute the parameters of the time-magnitudedistribution model proposed by Reasenberg and Jones (1989) andcurrently used to make aftershock forecasting in California. From 1981 to1996 we used the recently released Catalogo Strumentale deiTerremoti `Italiani' (CSTI) (Instrumental Catalog Working Group, 2001)joining the data of the Istituto Nazionale di Geofisica e Vulcanologia(INGV) and of the Italian major local seismic network, with magnituderevalued according to Gasperini (2001). From 1960 to 1980 we usedinstead the Progetto Finalizzato Geodinamica (PFG) catalog(Postpischl, 1985) with magnitude corrected to be homogeneous with thefollowing period. About 40 sequences are detected using two differentalgorithms and the results of the modeling for the corresponding ones arecompared. The average values of distribution parameters (p= 0.93±0.21, Log₁₀(c) = –1.53±0.54, b = 0.96±0.18 and a = –1.66±0.72) are in fair agreementwith similar computations performed in other regions of the World. We alsoanalyzed the spatial variation of model parameters that can be used topredict the sequence behavior in the first days of future Italian seismic crisis,before a reliable modeling of the ongoing sequence is available. Moreoversome nomograms to expeditiously estimate probabilities and rates ofaftershock in Italy are also computed.  相似文献   

巴基斯坦沿海地区地震危险性分析   总被引：1，自引：0，他引：1       下载免费PDF全文

ShahidA．Khan M．AliShah M．Qaisar 《地震学报》2003,25(4):361-373

通过确定性和概率性方法，对发展迅速的巴基斯坦沿海地区进行了地震危险性评估．根据该地区的地震构造和地质条件，确定了5个地震区域的11个断层作为该地区的潜在震源，计算了每个潜在震源的最大可能震级．根据与之相关震源的最大可信震级，计算了7个沿海城市的峰值加速度（PGA）．瓜达尔（Gwadar）和奥尔马腊（Ormara）的峰值加速度分别为0.21和0.25 g，处于地震危险性水平较高的地区；杜尔伯德（Turbat）和卡拉奇（Karachi）位于地震危险性水平较低的地区，峰值加速度小于0.1 g．同时，分别绘制了50年和100年超越概率为10％的PGA区划图，区划图的分区间隔为0.05 g．   相似文献   

夏季降水概率预报系统的试验研究     

柴凤岐  王正旺  杨万昌  杨建民  刘洁 《山西气象》2002,(1):4-7

降水概率天气预报的最大优点能够有效的发挥天气预报的潜在经济效益。我们根据山西省长治市的气候区划，将长治市的13个县区分为3片，应用T106资料，并通过对T106资料以及3片的实时资料制作0，1化处理，分别建立了3片的夏季（6月－8月）降水概率预报方程，并将整个系统挂接于MICAPS系统下。计算快捷，图文并茂，准确率较高。  相似文献   

Improved stress release model: Application to the study of earthquake prediction in Taiwan area     

朱守彪  石耀霖 《地震学报(英文版)》2002,15(2):171-178

Introduction Stress release model (SRM) was proposed by Vere-Jones (1978) for statistical study of seismicity. Physically it is a stochastic version of the elastic rebound theory of earthquake genesis. The classical elastic rebound model suggests that the stress has been slowly accumulating until the burst of an earthquake occurrence for stress release. This can be simulated by the jump Markov process in stochastic field, and SRM was developed on the basis of Knopoff (s Markov model (Knop…  相似文献   

2000年6月6日甘肃景泰5.9级地震前中短期震兆特征研究     

张敏 《高原地震》2002,14(4):23-28

运用“全时空和有限时空扫描”方法^①，对2000年6月6日甘肃景泰5．9级地震前青海地区的地震活动性和前兆观测资料进行了深入系统的分析处理。研究了该次地震前的中短期震兆特征。这些震兆包括：1年尺度的中短期空区、半年尺度的短期空区；西宁水氡、湟源水氡、乐都气氡震前l～5个月的短期异常；长宁水氡点的流量减少异常；二十里铺土地电EW向和NS项的反向异常；平安电磁波EW向的高值突跳。这些异常在时间上具有一定的同步性，空间上表现逐渐向震中迁移的特性。  相似文献   

How to obtain earthquake ground motions for engineering design   总被引：2，自引：0，他引：2  

Ellis L Krinitzsky 《Engineering Geology》2002,65(1):1-16

The earthquake ground motions that ultimately are selected for engineering design depend chiefly on the criticality of a site or structure and the engineering analyses that are to be performed. Several key steps are necessary in this selection process: They are (1) a reconnaissance to understand the hazards and obtain preliminary earthquake ground motions; (2) decisions on the application of deterministic or probabilistic methods; (3) selection of appropriate motions for requirements in design; (4) consideration of thresholds at which motions become significant for engineering; and (5) decisions on specifying appropriate earthquake ground motions for sizes of earthquakes, distances from sources, the structures, sites, and testing to be done. This paper presents five tables that show steps for evaluating these factors and for enabling the investigator to specify earthquake ground motions appropriate for engineering design.  相似文献   

Weibull模型在油气田早期开发方案设计中的应用   总被引：2，自引：0，他引：2  

龚久和  冯文光 《矿物岩石》2003,23(1):98-100

油气田开发早期勘探程度低，已知储层参数少，正确确定油气田开发方案是世界难题。制作Weibull开发模型的Qc/Qmax-ER图版的根据是探明储量、峰值产量及经济极限产量，假定采收率、生产年限，采用该图版油气田（藏）早期全局最优开发方案设计的方法，可以对整个开发期的各种开发指标进行预测。  相似文献   

Application of Brownian model in the north- western Beijing, China     

冉洪流  周本刚 《地震学报(英文版)》2004,17(Z1)

Introduction Since the tens years, the research on active fault has been stepped from qualitative phase toquantitative phase. With the developing of research on fault activity, fault segmentation, interac-tion among the adjacent or near fault segments, geodetic and paleoearthquake, scientists have re-alized that strong earthquake recurrence along active fault has different properties and multiplepatterns (Working Group on California Earthquake Probabilities, 1988, 1990, 1995, 1999, 2003…  相似文献   

Sustaining productive ecosystems in face of risk     

Reiner Schwarz 《GeoJournal》2004,59(3):219-225

Ecosystems lacking human induced energy input from outside are in danger to degrade if man requires any sustainable yield. The risk of failure strongly depends on the amount of exploitation. This is shown by a simple one dimensional analytical feed-back model. Natural fluctuations determine the degradation probability of productive ecosystems. The stability behaviour of the latter is demonstrated by an analytical model in the two dimensional phase space. Full quantitative evaluation of the risk needs simulation experiments. One is carried out in the thorn shrub savannah rangelands at a site in Namibia where a fully calibrated simulation model shows that the less a sustainable yield is required, the more the breakdown is delayed. In this case of highly fluctuating rainfall any sustainability sensu strictu does not exist. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献