一种新的空谱联合高光谱图像分类方法

针对现有高光谱图像分类方法对空间和谱间信息的利用不充分,限制了地物分类的准确度的问题,该文提出一种基于正交线性判别分析和三维离散小波变换的高光谱图像空谱联合分类算法。该算法首先利用正交线判别分析对高光谱图像进行特征提取和特征缩减;然后将提取后的特征经三维离散小波从不同尺度、频率和方向上分解,以级联的方式获得具有正交类判别信息的空谱融合特征集;最后,将空谱融合特征集作为概率支持向量机的输入特征,分类的结果再通过马尔可夫随机场利用空间上下文信息细化分类图,进一步提升分类准确度。在Indian Pines和Salinas两组数据集上的实验表明,相比其他算法,该算法能达到更高的总体分类准确度和Kappa系数,并且在大部分的地物类别上的分类准确度有着较为明显地提升。     

指数函数模量成层地基上变截面坝的随机地震反应分析

利用剪切梁理论推导出了指数函数剪切模量成层地基上变截面坝的自振频率方程及任意阶振型函数的解析表达式,在此基础上用振型叠加原理分别给出了地基和变截面坝的地震反应解析表达式.利用随机振动理论,并基于基岩输入地震加速度的功率谱密度函数(白噪声谱和过滤白噪声谱),研究了地基和变截面坝对地震的随机动力响应问题.数值计算表明:①在白噪声谱的情况下,土层和变截面坝的最大期望反应均有别于过滤白噪声谱时的相应值;②平稳输入与输出时地基和变截面坝的最大期望反应与平稳输入非平稳输出的相应值很接近;③平稳输入过高地估计了土层和变截面坝的随机响应.     

Long-term distribution of seabed shear stresses beneath random waves

The long-term distribution of seabed shear stresses under random waves is presented. The approach combines short-term distribution of maximum bottom shear stresses with a joint frequency table of significant wave height and peak period. An example of application is given where the long-term probability of exceeding a given level of the maximum bottom shear stress in the central North Sea is presented. The example includes estimation of the return period of the critical shear stress for sheet flow conditions, as well as the bottom shear stresses associated with the 1, 10 and 100 years return periods.     

On Intercomparison Of Instruments Used Within The Vatnajökull Glacio-Meteorological Experiment

As an important deliverable of a glaciometeorological experiment the participating research institutes produced a common data set that consists of temperature, humidity, wind and radiation data collected by different types of weather station at an elevation of 2 m above the glacier surface. Although all of the instruments had been calibrated in laboratories, intercomparison measurements were carried out under field conditions before and after the Vatnajökull experiment.This note deals with the intercomparison measurements and considers the observed differences in sensor characteristics. In spite of the fact that different types and brands of sensors were used under difficult field circumstances, the estimated accuracy of the common data set obtained is almost as good as suggested by the manufacturers' specifications. The long-term stability of the sensor calibrations also proved to be good. The reliability of the observed values included in the common Vatnajökull dataset is therefore considered to be high.     

原子荧光光度计检测土壤中痕量汞

探讨用AFS-230E型原子荧光光度计测定土壤中痕量汞元素的方法。文中所用原子荧光法具有操作简单、快速、灵敏度高、基体干扰少、分析结果稳定等特点。测定汞的回收率为90%~105%,检出限为0.00005mg/L,满足种植地土壤痕量汞检测的要求。     

Markov chain Monte Carlo (MCMC) sampling methods to determine optimal models,model resolution and model choice for Earth Science problems

We present an overview of Markov chain Monte Carlo, a sampling method for model inference and uncertainty quantification. We focus on the Bayesian approach to MCMC, which allows us to estimate the posterior distribution of model parameters, without needing to know the normalising constant in Bayes' theorem. Given an estimate of the posterior, we can then determine representative models (such as the expected model, and the maximum posterior probability model), the probability distributions for individual parameters, and the uncertainty about the predictions from these models. We also consider variable dimensional problems in which the number of model parameters is unknown and needs to be inferred. Such problems can be addressed with reversible jump (RJ) MCMC. This leads us to model choice, where we may want to discriminate between models or theories of differing complexity. For problems where the models are hierarchical (e.g. similar structure but with a different number of parameters), the Bayesian approach naturally selects the simpler models. More complex problems require an estimate of the normalising constant in Bayes' theorem (also known as the evidence) and this is difficult to do reliably for high dimensional problems. We illustrate the applications of RJMCMC with 3 examples from our earlier working involving modelling distributions of geochronological age data, inference of sea-level and sediment supply histories from 2D stratigraphic cross-sections, and identification of spatially discontinuous thermal histories from a suite of apatite fission track samples distributed in 3D.     

Scour below marine pipelines in shoaling conditions for random waves

This paper provides an approach by which the scour depth below pipelines in shoaling conditions beneath non-breaking and breaking random waves can be derived. Here the scour depth formula in shoaling conditions for regular non-breaking and breaking waves with normal incidence to the pipeline presented by Cevik and Yüksel [Cevik, E. and Yüksel, Y., (1999). Scour under submarine pipelines in waves in shoaling conditions. ASCE J. Waterw., Port, Coast. Ocean Eng., 125 (1), 9–19.] combined with the wave height distribution including shoaling and breaking waves presented by Mendez et al. [Mendez, F.J., Losada, I.J. and Medina, R., (2004). Transformation model of wave height distribution on planar beaches. Coast. Eng. 50 (3), 97–115.] are used. Moreover, the approach is based on describing the wave motion as a stationary Gaussian narrow-band random process. An example of calculation is also presented.     

塔河油田φ177．8mm套管开窗侧钻井技术难题与对策探讨

近年来,塔河油田为满足部分侧钻井的地质避水要求,采取从石炭系巴楚组或奥陶系上部桑塔木组泥岩段进行开窗侧钻,但泥岩在井内液体浸泡下存在易坍塌、掉块等不稳定问题,给钻井、完井带来了巨大的安全隐患。此文介绍了塔河油田中177．8mm套管开窗侧钻井技术现状与难题,探讨了下φ127mm套管、膨胀波纹管、实体膨胀管封隔泥岩三种技术方案的可行性。     

Research and Application of Cosmic-ray Fast Neutron Method to Measure Soil Moisture in the Field

It is very difficult to measure large region soil moisture. In recent years, measurement of surface soil moisture by the cosmic ray fast neutron probe has gradually attracted more attention. By this passive, non-invasive and intermediate scale measurement, soil moisture at a horizontal scale of around 300 m can be observed, which makes this method available to fill the gap between little scale of traditional point measurement and large scale of remote sensing in the measurement of soil moisture. In this paper, Cosmic-ray Soil Moisture Observing System (COSMOS) and Wireless Sensor Network (WSN) were used to observe field soil moisture in Zhangye Oasis. The results of the COSMOS soil moisture well reflected the variation trend of soil moisture at the field scale. There were some regular changes with the cosmic ray soil moisture during the irrigation period. Combined with irrigation data in cosmic-ray probe footprint, a bimodal change was showed in the cosmic-ray soil moisture figure during irrigation period. This was because that the order of irrigation of the three communities was different in cosmic-ray probe footprint. WSN data were used to validate this result and we found that root-mean-square error between cosmic-ray soil moisture and SoilNET average soil moisture was very large during irrigation periods because of the impact of cosmic-ray measurement theory. While root-mean-square error would decrease from 0.037 m³/m³ to 0.028 m³/m³ after we eliminated the data in irrigation period. So COSMOS can be used to measure field soil moisture under high heterogeneity condition and provide truly ground data for the validation of remote sensing