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981.
《The Professional geographer》2013,65(1):3-13
Vector data are not uncommon in geography, and include examples such as transportation flows, particulate transport, and cartographic distortion. The directional and vector means and variances of these types of data are easily computed using a complex-arithmetic extension of the equations for scalar mean and variance. The January surface wind field over the contiguous United States provides an example with which to compare the information provided by scalar, directional and vector-based statistics. Spatial patterns of the mean and variance of January wind velocity (the wind vector) resemble patterns of wind speeds and directions but are not a simple superposition of the two, and one cannot necessarily infer the nature of the velocity field from separately computed salar and directional statistics. However, scalar and directional means and variances can lend insight into the features contributing to the velocity mean and variance. Scalar, directional, and vector-based analyses thus provide complementary methods with which to examine the spatial patterns of wind, or of any flow field that can be represented as a vector. 相似文献
982.
《The Professional geographer》2013,65(4):425-429
Geographic Software Reviewed in this article: LIFE TABLES and the LESLIE MATRIX. CONDUIT MENTMAP2. Lawrence W. Carstensen Jr. PC-MATLAB, Version 1.0. The Math Works, Inc. QUICKMAP, version 1.0. Sammamish Data Systems, Inc. SYSTAT: THE SYSTEM FOR STATISTICS, Version 2.1, Systat Inc. USA DISPLAY. Instant Tecall 相似文献
983.
Annalise G. Blum Stacey A. Archfield Robert M. Hirsch Richard M. Vogel Julie E. Kiang Robert W. Dudley 《水文科学杂志》2013,58(12):1404-1414
ABSTRACTAccurate estimators of streamflow statistics are critical to the design, planning, and management of water resources. Given increasing evidence of trends in low-streamflow, new approaches to estimating low-streamflow statistics are needed. Here we investigate simple approaches to select a recent subset of the low-flow record to update the commonly used statistic of 7Q10, the annual minimum 7-day streamflow exceeded in 9 out of 10 years on average. Informed by low-streamflow records at 174 US Geological Survey streamgages, Monte Carlo simulation experiments evaluate competing approaches. We find that a strategy which estimates 7Q10 using the most recent 30 years of record when a trend is detected, reduces error and bias in 7Q10 estimators compared to use of the full record. This simple rule-based approach has potential as the basis for a framework for updating frequency-based statistics in the context of possible trends. 相似文献
984.
用高阶统计量方法对探地雷达数据进行处理,基本思路是采用信号识别与检测中的高阶统计量参数,对不同模型的探地雷达数据记录进行处理与重构,结果表明不同模型具有不同阶数的高阶统计量特征。模型实验与实际应用都表明,高阶统计量对压制背景噪声和多次反射波有较好的效果。 相似文献
985.
传统的地震统计学多局限于规则的统计范围,或是需要较多的人工干预,本文引入了基于地理信息系统的空间统计学方法,将其应用于地震空间统计中,能够高效、快速地挖掘含有地理信息的各要素之间的相互联系。本文以川滇地区2019年发生的ML≥1.0地震数量的空间统计为例,详述了对地震数据进行空间统计的流程。统计结果表明,0.5°×0.5°是最适合该地震数据集空间统计的矩形范围,发生地震次数最多的区域位于四川盆地西南缘的威远?长宁地区,此外龙门山断裂带、龙门山断裂带与鲜水河?小江断裂系交汇处、丽江?小金河断裂沿线以及滇南地区均为地震发生次数较高的区域。此外,还利用该方法计算了2015—2019年全国各省地震能量释放情况。结果显示在该时间段内,释放地震能量总量最多的省份为四川省,新疆维吾尔自治区和西藏自治区次之,而台湾地区陆地区域、四川省、西藏自治区等地区具有较高的每万平方公里地震能量释放量和每万人地震能量承受量。并通过上述应用实例,探索了地理信息系统在地震统计领域的初步应用。 相似文献
986.
对我国近几十年来的统计预测技术进行了回顾,并对未来的发展提出了一些看法。 相似文献
987.
988.
《The Professional geographer》1987,39(2):229-237
CHAOS CLlM 3.77 LP88 and TPR088 MAPEDIT PRODESIGN II RANDMAP SPATIAL AUTOCORRELATION SIMULATION GAME . Daniel A. Griffith STATA THINKTANK NOTEBOOK II 相似文献
989.
The Kapuskasing Structural Zone (KSZ) reveals a section through the Archean lower crustal granoblastic gneisses. Our new paleomagnetic data largely agree with previous work but we show that interpretations vary according to the choices of statistical, demagnetization and field-correction techniques. First, where the orientation distribution of characteristic remanence directions on the sphere is not symmetrically circular, the commonly used statistical model is invalid [Fisher, R.A., Proc. R. Soc. A217 (1953) 295]. Any tendency to form an elliptical distribution indicates that the sample is drawn from a Bingham-type population [Bingham, C., 1964. Distributions on the sphere and on the projective plane. PhD thesis, Yale University]. Fisher and Bingham statistics produce different confidence estimates from the same data and the traditionally defined mean vector may differ from the maximum eigenvector of an orthorhombic Bingham distribution. It seems prudent to apply both models wherever a non-Fisher population is suspected and that may be appropriate in any tectonized rocks. Non-Fisher populations require larger sample sizes so that focussing on individual sites may not be the most effective policy in tectonized rocks. More dispersed sampling across tectonic structures may be more productive. Second, from the same specimens, mean vectors isolated by thermal and alternating field (AF) demagnetization differ. Which treatment gives more meaningful results is difficult to decipher, especially in metamorphic rocks where the history of the magnetic minerals is not easily related to the ages of tectonic and petrological events. In this study, thermal demagnetization gave lower inclinations for paleomagnetic vectors and thus more distant paleopoles. Third, of more parochial significance, tilt corrections may be unnecessary in the KSZ because magnetic fabrics and thrust ramp are constant in orientation to the depth at which they level off, at approximately 15-km depth. With Archean geothermal gradients, primary remanences were blocked after the foliation was tilted to rise on the thrust ramp. Therefore, the rocks were probably magnetized in their present orientation; tilting largely or entirely predates magnetization. 相似文献
990.
This paper describes a procedure for extending local statistics to categorical spatial data. The approach is based on the notion that there are two fundamental characteristics of categorical spatial data; composition and configuration. Further, it is argued that, when considered locally, the latter should be measured conditionally with respect to the former. These ideas are developed for binary, gridded data. Local composition is measured by counting the numbers of cells of a particular type, while local configuration is measured by join counts. The approach is illustrated using a small, empirical data set and an ad hoc procedure is developed to deal with the impact of global spatial autocorrelation on the local statistics.The author gratefully acknowledges financial support from the GEOIDE Network of Centres of Excellence (ENV #4) and the helpful comments of three anonymous reviewers. 相似文献