A closer look at regime shifts based on coastal observations along the eastern boundary of the North Pacific     

Laurence C. Breaker 《Continental Shelf Research》2007

At least six regime shifts have been reported in the North Pacific since 1920. They occurred in 1925, 1939, 1946, 1976–1977, 1989 and 1999. The major change in 1976–1977 corresponds to a regime shift that is now widely accepted as a canonical event since it had a significant impact on virtually all climatic and ecosystem indicators. We seek to determine if daily sea surface temperature (SST) from Pacific Grove, in central California, and Scripps Pier, in southern California, and coastal observations from several other locations along the west coast of North America can be used to detect and resolve these events. Cumulative sums (CUSUMs) were initially calculated to enhance the detection process. The CUSUM trajectories during the 1976–1977 event at Pacific Grove and Scripps Pier were distinctive, highly correlated, and in phase. The turning point patterns from this event were then used to search for other events that have been reported since 1920. Turning point patterns very similar to the 1976–1977 event were detected in 1946 and 1989. The events in 1925 and 1939 were generally similar, but the CUSUM patterns for the event in 1999 departed significantly from the other events. Further examination of the 1976 and 1989 events revealed inflection points in the CUSUMs near the beginning and end of each transition that correspond to critical values or extrema in the original data. The inflection points and/or critical values provide an improved basis for determining the duration of these events.  相似文献   

Modification of the pattern informatics method for forecasting large earthquake events using complex eigenfactors   总被引：4，自引：0，他引：4  

J.R. Holliday  J.B. Rundle  K.F. Tiampo  W. Klein  A. Donnellan   《Tectonophysics》2006,413(1-2):87

Recent studies have shown that real-valued principal component analysis can be applied to earthquake fault systems for forecasting and prediction. In addition, theoretical analysis indicates that earthquake stresses may obey a wave-like equation, having solutions with inverse frequencies for a given fault similar to those that characterize the time intervals between the largest events on the fault. It is therefore desirable to apply complex principal component analysis to develop earthquake forecast algorithms. In this paper we modify the Pattern Informatics method of earthquake forecasting to take advantage of the wave-like properties of seismic stresses and utilize the Hilbert transform to create complex eigenvectors out of measured time series. We show that Pattern Informatics analyses using complex eigenvectors create short-term forecast hot-spot maps that differ from hot-spot maps created using only real-valued data and suggest methods of analyzing the differences and calculating the information gain.  相似文献   

焦作市连阴雨天气分析与预报   总被引：1，自引：0，他引：1  

闫小利刘跃红  李艳红卢学锋 《河南气象》2004,(4):18-19

利用1980-2002年气象资料，分析了焦作市连阴雨天气的气候特征和环流特征，并在寻找出连阴雨预报和结束指标的基础上，利用T213预报场确定相似场，通过计算相似系数，作出连阴雨天开始、持续和结束的预报。  相似文献   

用动态规划的二维物体识别的方法     

郑肇葆  李捍东 《测绘学报》1994,23(1):45-52

二维物体的识别是计算机视觉与航空摄影测量领域里重要的研究目标。本文提出在图像预处理阶段运用边缘提取的算法和数学形态学先得到轮廓线，形成对特征的描述。基于这些特征描述建立了用动态规划法进行特征匹配的数学模型和算法。实验结果表明它不仅具有可靠性和稳健性，而且在计算机上易于编程实现。  相似文献   

山东大汶口盆地蒸发岩特征及成钾规律   总被引：1，自引：0，他引：1  

李钟模 《盐湖研究》1994,2(2):1-10

大汶口盆地是目前苏、鲁、豫、皖诸省早第三纪唯一发现钾盐矿的盆地．研究其特征和成钾规律，对下一步的找钾工作具有一定的指导意义，该盆地具有同断陷同沉积的性质．盐类物质来源丰富，具多源性．杂卤石的分布很有规律，可作为找钾的标志矿物．钾盐赋存在完整韵律的中上部．  相似文献   

用模式识别方法划分辽宁及其邻区的潜在震源区   总被引：1，自引：0，他引：1       下载免费PDF全文

蒋秀琴  王国新 《地震地质》1993,15(1):51-56

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  相似文献   

雷歌研究历程、格局及问题     

杨励轩 《广东海洋大学学报》2013,(2)

雷歌研究自清末民初的黄景星起至今近90年,在雷歌起源、流变、词曲形态、音韵及音调等方面积累了较多描述性研究成果,为后续研究提供了宝贵资料,但研究格局僵化,领域有限,主题高度重复,缺乏方法论意识,研究成果宏观上表现零散、随意及表层化,突破性成果匮乏,微观上则有概念模糊缺乏足够实证材料之弊端。  相似文献   

深地震反射剖面构造信息识别研究   总被引：2，自引：1，他引：1  

李文辉  高锐  王海燕  李洪强 《地球物理学报》2012,55(12):4138-4146

随着我国深部探测计划的实施,近年来在中国大陆地区实施了多条深地震反射剖面,获得了大量揭示地壳上地幔精细结构的宝贵资料. 为了更充分地挖掘这些资料中所包含的深部构造信息,本文在研究和总结前人工作的基础上,提出一种快速识别深地震反射剖面构造格架的方法. 该方法通过数据预处理、强振幅提取、中值滤波、对象识别、连续性计算和连续性滤波实现对深地震反射剖面构造格架识别. 同时,该方法还可通过对象倾角计算对复杂区域进行属性分析.  相似文献   

河北及邻区地震时空概率增益综合预测研究     

齐玉妍  孙丽娜  邱玉荣  李姜  金学申 《中国地震》2015,31(1):78-88

结合地震空间分布非均匀性指标Kcv值预测方法和图像信息学算法对河北及邻区2013~2017年ML≥5.0地震发生概率增益进行预测。根据河北及邻区40多年的地震观测资料,对地震空间分布非均匀性指标Kcv值进行了空间扫描和震例统计,得到了此方法应用于河北地区的预测效能,并对河北及邻区2013~2017年ML≥5.0地震发生概率增益进行了预测;对图像信息学算法在研究区进行了地震危险性概率预测的回溯性检验,得到了此方法应用于研究区的预测效能R值及概率增益K值,并进行了5年尺度的地震危险性预测。在上述2个单项预测方法的基础上,基于概率增益综合预测模型,得到了5年尺度河北及邻区ML≥5.0地震发生概率增益的综合预测结果。  相似文献   

Large-scale shaking table model tests on seismically induced failure of Concrete-Faced Rockfill Dams     

《Soil Dynamics and Earthquake Engineering》2016

An increasing number of high Concrete-Faced Rockfill Dams (CFRDs) have been and are being built in highly seismic hazardous regions. Because there are few examples, the failure mechanisms for each damaged CFRD still remain unclear, which prevents a rational evaluation of aseismic performance of a CFRD. In this paper, a series of large-scale shaking table tests are conducted to determine the dynamic failure modes of CFRDs, especially the failure mechanism of the face slab. A type of model slab material is developed according to similitude rules. Particle Image Velocimetry (PIV) is used and improved to track the motion of each grain and subsequently measure the entire velocity field of the deforming cross-sections of dam models. The failure processes of the dams, the failure mechanisms of the slab fractures and the slab dislocations are discussed based on the experimental results. The experiments indicate that large deformations of the uppermost part of the dam caused the face slab to curve upward and crack. Another important fracture morphology of the face slab is the dislocation of its joint. The change in the granular fabric caused the granular slope to slide down and thrust outward, eventually dragging the upper half of the face slab down against its lower half; this motion is accompanied by the formation of a joint dislocation. Therefore, the stability and anti-deformation ability of both the downstream slope and the crest region of the upstream slope should be improved to withstand earthquake. The results of the shaking table model tests are consistent with the numerical simulation, and both results support the prototype dam׳s seismically induced failure characteristics.  相似文献