基于融合技术的结构性栅格时空数据平台的构建

时空数据融合是当前研究地理现象空间格局的数据存储、处理方法与有效途径。在构建国家资源环境时空数据平台过程中 ,我们设计了基于 1 km栅格单元的土地利用现状与变化数据库。这种时空数据表达方式的优点 :(1 )在保持面积信息不损失情况下明显减少了数据存储量 ,并且满足区域分析的空间尺度要求 ;(2 )便于多时间序列的数据存储与变化分析 ,以及变化专题信息提取与结果显示 ;(3)有利于区域土地利用变化环境背景与驱动力分析 ,可以实现与其他多源数据的有效融合 ;(4 )从小尺度到大尺度的空间尺度转换非常便利 ,在空间聚合的基础上能够快速实现从区域分析扩大至国家尺度、全球尺度的分析。     

围岩稳定分析的熵突变准则研究

地下工程围岩体具有高度的非线性,可以借助当代非线性科学研究和预测它的力学行为。应用耗散结构理论、熵及突变论等非线性科学理论研究岩石非线性稳定问题,揭示了岩体失稳过程和破坏机理,建立了符合实际的岩体破坏分析方法和失稳判据。     

用于水资源系统观测网空间布局优化设计的技术方法

论述了观测网空间优化设计的重要性和我国目前观测网点布设存在的问题,在综合国内外水资源科学研究状的基础上,介绍了目前用于观测网优化设计的几种技术方法,包括数据理论方法,克里格技术和信息熵方法,特别推荐基于信息熵与随机数学相结合而发展起来的优化设计方法,这种根据观测数据信息含量大小建立信息关系度量的技术手段,特别适合在基础数据不完整的情况下运用。     

Directional spread parameter at intermediate water depth

The characteristics of directional spread parameters at intermediate water depth are investigated based on a cosine power ‘2s' directional spreading model. This is based on wave measurements carried out using a Datawell directional waverider buoy in 23 m water depth. An empirical equation for the frequency dependent directional spreading parameter is presented. Directional spreading function estimated based on the Maximum Entropy Method is compared with those obtained using a cosine power ‘2s' parameter model. A set of empirical equations relating the directional spreading parameter corresponding to the peak of wave spectrum to other wave parameters like significant wave height and period are obtained. It shows that the wave directional spreading at peak wave frequency can be related to the non-linearity parameter, which allows estimation of directional spreading without reference to wind information.     

Study of Water Motion at the Dissolved Oxygen Minimum Layer and Local Oxygen Consumption Rate from the Lagrangian Viewpoint

By using the Euler-Lagrangian method, we examine water movements within the layer of minimum oxygen concentration and estimate local oxygen consumption rates for 15 regions of the global ocean. To do this, a number of labeled particles (which represent water parcels) are deployed at the center of a grid with 15 depth levels and tracked backward in time for 50 years in a three-dimensional velocity field. We assume that a particle picks up oxygen when it encounters the point of maximum oxygen concentration along the 50 years segment of its path. We introduce a contribution rate from waters distributed throughout the global ocean to the oxygen concentration of a local layer under consideration. Water parcels which are assumed to pick up oxygen within the oxygen minimum layer of an oceanic region under consideration make a very small contribution to the overall oxygen concentration of this layer. In addition, these parcels move out of the layer and water parcels from the upper layers take their place. The averaged Lagrangian local oxygen consumption rate is 0.033 ml/l/yr for the depth of the oxygen minimum layer, 0.20 ml/l/yr at 100 m depth (euphotic layer), 0.043 ml/l/yr for layers from 150 m to 800 m depth and 0.012 ml/l/yr for deep layers from 800 m to 3000 m. The present Lagrangian numerical experiment produces a maximum difference between observed and calculated concentrations of oxygen and, therefore, a maximum oxygen consumption rate. Although the present method has an ambiguity as to how oxygen is picked up, we nevertheless were able to identify regions in which the water parcels pick up oxygen of maximum concentration. We found that the South Equatorial Current (SEC) transports oxygen of higher concentration to the middle latitude regions of both the North Atlantic and the North Pacific across the equator.     

An integrated approach to scaling issues in environmental change study

IntroductionOn the basis of our understanding of ecological principles, we can expect that global changes in climate, atmospheric composition and land use should affect the structure, function, productivity and the sustainable use of terrestrial ecosystems[1-3]. It is crucial for scientists to gain capacity to obtain sufficient data and effective understanding of ecosystem behaviors at larger scales, to extent models developed from local experiments to large areas where ground truth data are s…     

深埋泥岩地层的最小主应力测定方法探讨

结合理论分析与实际资料统计,根据泥岩地层在水力压裂垂直裂缝剖面中所占的比例大小和瞬时停泵压力的变化趋势,获得了鄂尔多斯盆地西峰地区长8层(2 100 m)和靖边地区盒8地层(3 000 m)的泥岩最小主应力,这可为油气钻采、压裂设计以及测井、地震资料解释提供参考依据。间接证据表明,利用该方法求取的泥岩地层地应力更符合实际情况。      

基于熵变加权法的水安全综合指数评价

为了构建水安全综合评价的模型,采用熵变加权法对水安全评价体系的各子系统进行赋权,得到水安全的综合评价指数公式。将方法应用于山东省区域水资源安全评价,并与其它方法的评价结果进行了比较分析。结果表明：基于熵变加权法的水安全综合指数能反映出样本与评价标准之间的远近程度,并且可以同时评价多个样本;熵变加权法的应用减少了评价的主观性,使评价结果客观、合理,具有良好的实用性。     

基于CEEMDAN的GNSS变形监测去噪方法

为了提高GNSS变形监测数据去噪的有效性和可靠性,提出一种自适应完备集合经验模态分解(complete ensemble empirical mode decomposition with adaptive noise, CEEMDAN)去噪方法。首先将GNSS变形序列经CEEMDAN分解为若干特征模态函数;其次引入排列熵理论确定高低频分界值K,利用小波分析对高频分量进行去噪,去噪后与低频分量重构得到去噪序列;最后通过仿真和实测边坡GNSS变形监测数据,利用信噪比、均方根误差、相关系数等指标对比分析CEEMDAN、EMD和小波去噪方法。结果表明,CEEMDAN方法的去噪效果和精度优于EMD和小波去噪方法,证明了本文所提方法的有效性和可靠性。