HHT-EEMD用于IGS站高程时间序列分析

利用经验模态分解（EMD）和整体经验模态分解（EEMD）方法,将BJFS站2000~2015年高程时间序列进行分解,发现其不仅存在1 a、0.5 a、0.25 a、2个月、1个月以及长周期等周期项,还存在以往方法很难探测出来的近似2 a周期信号。与EMD分解结果对比,整体经验模态分解可以明显减弱模式混叠现象。对各分量进行Hilbert 变换（HHT）,得到时间-频率-能量的Hilbert 频谱图。结果表明,年周期和2 a周期变化是高程运动的主要贡献项。利用小波变换方法对比验证EEMD的分解结果表明,与小波分析相比,EEMD重构信号与高程序列差异的RMS更小,证明了HHT-EEMD方法在数据资料分析过程中的有效性。对环境负载及GRACE负载造成的测站位移进行功率谱分析得出,环境负载确实会造成IGS站高程时间序列的1 a、0.5 a以及季节性运动,GRACE负载还验证了2 a信号的存在。     

Minimal cut-based recursive decomposition algorithm for seismic reliability evaluation of lifeline networks

In this paper, a new probabilistic analytical approach, the minimal cut-based recursive decomposition algorithm (MCRDA), is presented to evaluate the seismic reliability of large-scale lifeline systems. Based on the minimal cut searching algorithm, the approach calculates the disjoint minimal cuts one by one using the basic procedure of the recursive decomposition method. At the same time, the process obtains the disjoint minimal paths of the system. In order to improve the computation efficiency, probabilistic inequality is used to calculate a solution that satisfies the prescribed error bound. A series of case studies show that MCRDA converges rapidly when the edges of the systems have low reliabilities. Therefore, the approach can be used to evaluate large-scale lifeline systems subjected to strong seismic wave excitation.     

Influence of pore size and geometry on peat unsaturated hydraulic conductivity computed from 3D computed tomography image analysis

In organic soils, hydraulic conductivity is related to the degree of decomposition and soil compression, which reduce the effective pore diameter and consequently restrict water flow. This study investigates how the size distribution and geometry of air‐filled pores control the unsaturated hydraulic conductivity of peat soils using high‐resolution (45 µm) three‐dimensional (3D) X‐ray computed tomography (CT) and digital image processing of four peat sub‐samples from varying depths under a constant soil water pressure head. Pore structure and configuration in peat were found to be irregular, with volume and cross‐sectional area showing fractal behaviour that suggests pores having smaller values of the fractal dimension in deeper, more decomposed peat, have higher tortuosity and lower connectivity, which influences hydraulic conductivity. The image analysis showed that the large reduction of unsaturated hydraulic conductivity with depth is essentially controlled by air‐filled pore hydraulic radius, tortuosity, air‐filled pore density and the fractal dimension due to degree of decomposition and compression of the organic matter. The comparisons between unsaturated hydraulic conductivity computed from the air‐filled pore size and geometric distribution showed satisfactory agreement with direct measurements using the permeameter method. This understanding is important in characterizing peat properties and its heterogeneity for monitoring the progress of complex flow processes at the field scale in peatlands. Copyright © 2010 John Wiley & Sons, Ltd.     

热解石墨坩埚的应用

本文介绍本院研制的热解石墨坩埚的特性和应用情况。该坩埚具有纯度高、致密、耐高温、耐强酸强碱腐蚀、易洗涤等特点,已广泛应用于矿物、建材、玻璃等方面试样的前处理。与铂、银、镍、刚玉、石英等坩埚比较,具有引入杂质少成本低等优点。     

从景观生态学构建城市旅游开发与规划的操作模式

本文尝试建立一个关于旅游开发与规划的应用理论模式,以兼顾理论的抽象性和操作性。模式的构建依据地理空间分析方法,同时借用景观生态学斑、廊、基的概念。文中详细论述了该斑廊基网络结构操作模式的基本特点、变换空间分析方法等运行机制,并以不同城市旅游规划、设计实例说明三大操作块的功能和操作意义。     

气象场相关结构对EOFs展开稳定性的影响

本文从矩阵扰动理论出发,提出利用矩阵的范数(norm)作为度量气象场随机扰动的稳定性指标,并由此间接推估EOFs展开的稳定性。经理论论证、数值试验和实例计算表明,气象场的相关性越好,达到稳定相关结构所需样本越小,由此得到的EOFs稳定性也越好,反之则不然。上述规律又直接受样本大小n和站点数目p的影响。对于不同的气象场来说,达到稳定EOFs的样本临界值不同,必须警惕EOFs展开有可能不是稳定的。     

ELIMINATING COMPLEX EIGENVECTORS AND EIGENVALUES IN MULTIWAY ANALYSES USING THE DIRECT TRILINEAR DECOMPOSITION METHOD

The direct trilinear decomposition method(DTDM)is an algorithm for performing quantitative curveresolution of three-dimensional data that follow the so-called trilinear model,e.g.chromatography-spectroscopy or emission-excitation fluorescence.Under certain conditions complexeigenvalues and eigenvectors emerge when the generalized eigenproblem is solved in DTDM.Previouspublications never treated those cases.In this paper we show how similarity transformations can be usedto eliminate the imaginary part of the complex eigenvalues and eigenvectors,thereby increasing theusefulness of DTDM in practical applications.The similarity transformation technique was first used byour laboratory to solve the similar problem in the generalized rank annihilation method(GRAM).Because unique elution profiles and spectra can be derived by using data matrices from three or moresamples simultaneously,DTDM with similarity transformations is more efficient than GRAM in the casewhere there are many samples to be investigated.     

第二代航磁黄沙坪异常的分解及其矿产新空间

本文采用同时具有识別、分解、解释异常三重作用的三元解释法■,在黄沙坪异常负值区有效地提取了由未知的深源磁性体引起的剩余异常。该异常与已知的中、浅源磁性体分处于极为类同的成矿地质背景中。后者与隐伏岩体、铅锌多金属盲矿体之间有着密切的成生联系。这为前者间接找矿提供了有力的依据。定量解释结果中,两者间的磁矩等效关系,论证了已知矿床西侧深部空间里,仍存在找到又一个大型矿床的前景。