Discrete wavelet‐based trend identification in hydrologic time series     

Yan‐Fang Sang  Zhonggen Wang  Changming Liu 《水文研究》2013,27(14):2021-2031

Trend identification is a substantial issue in hydrologic series analysis, but it is also a difficult task in practice due to the confusing concept of trend and disadvantages of methods. In this article, an improved definition of trend was given as follows: ‘a trend is the deterministic component in the analysed data and corresponds to the biggest temporal scale on the condition of giving the concerned temporal scale’. It emphasizes the intrinsic and deterministic properties of trend, can clearly distinguish trend from periodicities and points out the prerequisite of the concerned temporal scale only by giving which the trend has its specific meaning. Correspondingly, the discrete wavelet‐based method for trend identification was improved. Differing from those methods used presently, the improved method is to identify trend by comparing the energy difference between hydrologic data and noise, and it can simultaneously separate periodicities and noise. Furthermore, the improved method can quantitatively estimate the statistical significance of the identified trend by using proper confidence interval. Analyses of both synthetic and observed series indicated the identical power of the improved method as the Mann–Kendall test in assessing the statistical significance of the trend in hydrologic data, and by using the former, the identified trend can adaptively reflect the nonlinear and nonstationary variability of hydrologic data. Besides, the results also showed the influences of three key factors (wavelet choice, decomposition level choice and noise content) on discrete wavelet‐based trend identification; hence, they should be carefully considered in practice. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

基于遥感空间信息的洪水风险识别与动态模拟研究进展          下载免费PDF全文

曾子悦  许继军  王永强 《水科学进展》1990,31(3):463-472

对地观测卫星遥感能够提供广泛可靠的空间信息，是洪水风险识别与动态模拟的重要支撑技术之一。为阐明卫星遥感技术对洪水研究的推动作用，回顾了洪水风险识别与动态模拟研究的发展历程及技术需求，以对地观测卫星遥感三大阶段的发展轨迹为主线，分析了遥感空间信息在洪水研究中的历史性贡献和阶段性效用，讨论总结了危险分区法、水文模型和微波遥感监测等3种洪水研究典型方法的应用进展。提出未来洪水风险识别与动态模拟研究的重点：遥感空间信息与模型算法的深度结合，遥感反演算法与系统的开发及应用，典型洪水研究方法集成系统的开发与应用，大数据方法与手段的应用。以期为提升洪水应急响应能力与灾害风险管理水平提供有效参考。  相似文献   

Detection of anomalous seismic phases by the wavelet transform   总被引：1，自引：0，他引：1  

Kiyoshi Yomogida 《Geophysical Journal International》1994,116(1):119-130

  相似文献   

川西地区劳动就业研究   总被引：3，自引：0，他引：3  

陈国阶 《地理研究》1993,12(3):89-99

以川西作为研究区域,对农村劳动力转移或非农就业从自然—人文相结合的观点进行了探讨。  相似文献   

平原地区活断层研究   总被引：3，自引：0，他引：3  

王华林  李家灵 《地震研究》1991,14(2):132-140

本文归纳、总结了近几年来山东省地震局在工程地震工作中采用的平原地区活断层研究的方法。几个典型实例证明,这一方法在平原地区活断层研究中是行之有效的,获得了良好的、具有科学价值的结果,同时讨论了与这一方法有关的几个问题。  相似文献   

电子探针快速自动定量矿石中矿物的方法研究     

欧阳菲  潘法忠 《岩矿测试》1991,10(4):267-270

利用电子探针、能谱仪、扫描电镜和计算机等一整套仪器,对组成矿石样品中有用矿物的含量进行定量统计。既能准确识别矿物又能精确统计各矿物在矿样中的面积百分含量(面积法)。  相似文献   

An interactive system to assist mineral identification in ore microscopy     

Tetsuya Shoji  Hiroaki Kaneda 《Mathematical Geology》1994,26(8):961-972

An interactive computer system has been developed to assist the mineral identification in ore microscopy. The reference file of the system consists of optical, mechanical, and chemical properties of about 130 ore minerals. The properties are name, chemical formula, color, bireflectance, anisotropism, internal reflection, reflectance at wavelengths of 470, 546, 589, and 650 nm, and polishing hardness and micro-indentation hardness. All the properties except reflectance and microindentation hardness are qualitative or semi-qualitative. Most of the properties are given as characters relative to the more common minerals. This implies that most of the identification processes advance on the basis of the comparison between a subject mineral and coexisting minerals. For this reason, the system asks a user at first to input already identified mineral names. This is quite different from the mineral identification procedures used in petrographic microscopy. To reduce the number of possible minerals, the system presents a series of questions to a user, and the user selects any of the prepared answers according to his observation. The user can also choose any desired question independently of the sequence. The user is expected to be able to recognize some common minerals, such as pyrite, chalcopyrite, galena, and hematite, without the assistance of the system.  相似文献   

宝石级钻石鉴定的回顾          下载免费PDF全文

Shig.  JE 《地球科学》1994,19(2):273-280,T001

概括地评述了天然钻石、实验室处理的钻石、人造钻石以及钻石仿制品的宝石学鉴定特征。  相似文献   

地下流体前兆模糊识别     

许秋龙 《内陆地震》1995,9(3):286-290

在地震的孕育、发生到发展的过程中，可能会出现多项地下流体观测量不同程度的前兆异常变化，这些异常变化是复杂多样、模糊不清的。引入模糊识别法对一定区域和一定时间段的地下流体观测数据进行了分析和处理，表明模糊识别法可较好地识别和分辨出地下流体前兆的地震异常。  相似文献   

浅层地温误读的分析与判断     

施淑嬿 《气象》1995,21(12):38-41

作者介绍了在多年地面信息资料处理中积累的关于浅层地温误读的分析与判断经验，总结出人机结合的５个分析判断方法，在工作中收到了良好效果，从而保证了信息资料和气表资料的准确性。  相似文献