A distribution function based bandwidth selection method for kernel quantile estimation

The key problem in nonparametric frequency analysis of flood and droughts is the estimation of the bandwidth parameter which defines the degree of smoothing. Most of the proposed bandwidth estimators have been based on the density function rather than the cumulative distribution function or the quantile that are the primary interest in frequency analysis. We propose a new bandwidth estimator derived from properties of quantile estimators. The estimator builds on work by Altman and Léger (1995). The estimator is compared to the well-known method of least squares cross-validation (LSCV) using synthetic data generated from various parametric distributions used in hydrologic frequency analysis. Simulations suggest that our estimator performs at least as well as, and in many cases better than, the method of LSCV. In particular, the use of the proposed plug-in estimator reduces bias in the estimation as compared to LSCV. When applied to data sets containing observations with identical values, typically the result of rounding or truncation, the LSCV and most other techniques generally underestimates the bandwidth. The proposed technique performs very well in such situations.     

Stochastic and statistical methods in hydrology and environmental engineering

Recent developments in stochastic and statistical methods in hydrology and environmental engineering presented in the upcoming sequence of research papers are evaluated, compared and put into proper perspective. These papers are being published as a memorial to Professor T. E. Unny who was a founding Editor of the journalStochastic Hydrology and Hydraulics. As explained in this introductory paper, other activities that took place to celebrate Professor Unny's lifetime academic accomplishments include an international conference held in his honor at the University of Waterloo in June, 1993 and the publication of a four-volume conference proceedings in 1994.     

从屏幕色到印刷的转换方法

从屏幕色到印刷的转换方法朱元泓。是，人们感到头痛的是屏。的效果。为了达到理想的印刷色土要进行多次重复尝试（从修改荧光屏，浪费材料，特别是多色地图电子复制设计Ａ屏幕色转换为印刷色的新方法，即逆解组纶堡方ｄ值修正法，并说明两种方法可达到的精度。ｊ色通过红...     

温江站有无降水日的边界层特征对比分析

本文基于2016年6月21日~7月31日温江站边界层塔和加密探空观测获取的资料，对比分析了该站有雨日和无雨日的边界层大气特征，得到以下结论：1、温江站7月的降水量较多，降水时段以凌晨2:00~6:00居多，呈现典型的“夜雨”特征。2、边界层内大气各个气象要素场在有无降水日具有非常明显的差异，探空观测的低层大气表现为：无雨日白天边界层呈现典型的混合边界层特征。有雨日边界层大气温度总是小于无雨日，在极大值出现的午后时段二者的差值最大。有雨日近地层大气比湿在8:00、14:00和20:00三个时次都明显高于无有雨日，比湿日变化幅度低于无雨日。温江站边界层低层大气的风速总体较小，有雨日的风速明显大于无雨日。3、边界层塔观测显示：有雨日太阳短波辐射以及各个地表通量的极大值仅为无雨日的2/3左右。白天，有雨日的温度低于无雨日，日变化幅度比无雨日低3oC左右；夜间二者都呈现显著的逆温现象。有雨日白天比湿高于无雨日，夜间则低于无雨日，有无雨日比湿日变化幅度比无雨日少2g/kg；白天，有雨日风速日变幅也略小于无雨日，除了午后时段有雨日在凌晨2:00时还出现另外一个风速极大值点；有雨日的气压值总是略高于无雨日，白天的气压差值比夜间大。白天，有雨日各个地面观测量的极值出现时间总是略晚于无雨日1h左右。     

Uses of springwater

The many uses of springwater around the world span history. Springwater has been used for basic survival, medicinal purposes, and for man's entertainment, pleasure, and dalliance. Hippocrates and ancient Greek physicians were versed in the health benefits of mineral water therapy. In early recorded history, the Egyptians, Arabians, and Mohammedans discussed the use of mineral waters for healing the ill. Mythology and legend date the thermal springs of Bath, England, to 800 BC. Hannibal refreshed himself with bubbling springwater at Vergeze on his way to attack Rome in 218 BC. Therapeutic application of mineral waters was very popular in the late 1800s and early 1900s. Significant expenditures were made throughout Europe and the United States to develop lavish resorts and vacation spots at the famous mineral springs. The Romans may have initiated the uses of mineral waters, but the French are traditionally the modern developers and promoters of bottled waters. Evian was exported to the United States as early as 1905. Mountain Valley, of Hot Springs, Arkansas, has been bottled since 1871. Poland Spring water of Maine has been distributed since the mid-1800s. Springwater has become the health drink of today. Uses of springwater through time, famous springs and famous consumers of springwater, and the therapeutic attributes of springwater are summarized in the following paper. Research included technical, nontechnical, and trade information. The paper provides a retrospective of historical aspects of the development of springwaters, a concise summary of medicinal characteristics of springwater, and insight to commercial enterprise of bottled water.     

逐步波形反演方法及应用

本文针对天然地震波形反演面临的困难及其复杂性，提出了逐步波形反演方法，第一步，运用波形反演中的试错法，求得地震台站下方成层介质的初步结构；第地一步，以第一步结果为初值，令各层厚度不变，反演速度；第三步，以第二步结果为初值，令速度不变，反演厚度。以上各步还可交替进行，直至得到满意结果。     

软弱破碎围岩变形特性

本文在连续十余年原位监测试验资料的基础上,描述了全断面开挖的软弱围岩变形u-t全过程曲线;阐明了不同变形阶段的变形速率、变形量以及这些变形的时空效应;探讨了岩体工程地质特性、埋深、洞径、开挖方式和支护及时性等主要因素对围岩变形特性的影响;并针对具体工程提出了围岩稳定性状态划分及其判别标准、失稳险情预报原则、变形控制标准与初期支护抗力的确定原则、后期支护最佳施作时期的选择以及合理开挖方式。     

Statistical analysis of the largest possible earthquake magnitudes on the Ecuadorian coast for selected return periods

ABSTRACT

In this work, we have studied the largest earthquake magnitudes on the Ecuadorian coast by using the principles of Extreme Value Analysis based on its two approaches: Block Maxima and Peaks-over-Threshold. First, before modelling the recorded earthquakes, the K-means clustering technique was applied to determine a classification according to the level of magnitude of the earthquakes. Then, models based on the Extreme Value theory of earthquake magnitudes were developed for each of the four clusters that were found, and finally, the best-fitted models were those known as Fréchet and Gumbel ones. The zone with the greatest earthquake magnitudes on the Ecuadorian coast is located between the north of the province of Manabí and the south of the province of Esmeraldas, with a return period of 50 years for an earthquake with magnitude greater than 7.7 M_W.     

青藏高原东北部典型花粉类型埋藏特征及其与植被关系的研究

取自青藏高原东北部不同植被类型的 6个土壤剖面花粉与植被关系研究表明，表土花粉较好地代表当地植被的组成，区域外花粉百分比低于30％，但桦、杨花粉在植被中的代表性较差；土壤剖面典型花粉类型的埋藏特征表明：在土壤表层 8cm以下，花粉总浓度迅速降低。氧化作用对花粉的破坏性最大，花粉浓度随土壤的pH值升高呈指数形式递减，pH值 7．6以上，花粉浓度迅速降低，花粉在土壤中的运移作用不明显。