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高光谱遥感的物质组分和物质成分反演的应用分析

高光谱遥感的最大特点是可以提取和重建像元光谱,从而依据光谱特征直接识别地物类型、地物组成,乃至地物的成分,反演地物的物理、化学参量。本文阐述了高光谱的光谱识别方法所能探测的岩石、土壤、植被和人工建筑物的物质组分或成分;另外,与多光谱相比较的角度,讨论了高光谱图像地物特征识别和物质成分反演等技术方法的应用。     

斜压海洋能量传递对风场的响应

风是海水运动的重要动力因素,也是海洋内部的主要能量来源.本文在应用陆架海洋模式HAMSOM对东中国海海水运动进行数值模拟的基础上,通过傅里叶变换、旋转谱分析等研究方法,对风向海洋的能量输运进行研究.研究结果显示,风场向海洋输运的最有效途径是风杨扰动量与流场扰动量的相互作用;惯性能量主要来源于海洋表层,由风场提供,向下传递;而潮频率能量大部分来自海底的内潮与底地形相互作用,向上传递.     

2003年北黄海5.1级地震的地震活动特征

对2003年北黄海5．1级地震的地震活动背景、地震序列、震中周围中小地震活动图像及地震学参数等进行了详细分析。认为该次地震为前-主-余型，经历了一个活跃-平静-发震的过程；地震前震中附近出现了孕震空区和一些地震活动性参数异常。     

Evolution mechanism of the western Pacific subtropical high

Ever since Charney et al.[1] studied the multiple equilibrium states in atmosphere with highly truncated spectral method in 1979, many Chinese researchers, such as Li Maicun et al. (1983)[2], Liu Chongjian et al. (1983)[3], Miu Jinhai et al. (1985)[4] and…     

Using a H∞ filter assimilation procedure to estimate root zone soil water content

Root zone soil water content impacts plant water availability, land energy and water balances. Because of unknown hydrological model error, observation errors and the statistical characteristics of the errors, the widely used Kalman filter (KF) and its extensions are challenged to retrieve the root zone soil water content using the surface soil water content. If the soil hydraulic parameters are poorly estimated, the KF and its extensions fail to accurately estimate the root zone soil water. The H‐infinity filter (HF) represents a robust version of the KF. The HF is widely used in data assimilation and is superior to the KF, especially when the performance of the model is not well understood. The objective of this study is to study the impact of uncertain soil hydraulic parameters, initial soil moisture content and observation period on the ability of HF assimilation to predict in situ soil water content. In this article, we study seven cases. The results show that the soil hydraulic parameters hold a critical role in the course of assimilation. When the soil hydraulic parameters are poorly estimated, an accurate estimation of root soil water content cannot be retrieved by the HF assimilation approach. When the estimated soil hydraulic parameters are similar to actual values, the soil water content at various depths can be accurately retrieved by the HF assimilation. The HF assimilation is not very sensitive to the initial soil water content, and the impact of the initial soil water content on the assimilation scheme can be eliminated after about 5–7 days. The observation interval is important for soil water profile distribution retrieval with the HF, and the shorter the observation interval, the shorter the time required to achieve actual soil water content. However, the retrieval results are not very accurate at a depth of 100 cm. Also it is complex to determine the weighting coefficient and the error attenuation parameter in the HF assimilation. In this article, the trial‐and‐error method was used to determine the weighting coefficient and the error attenuation parameter. After the first establishment of limited range of the parameters, ‘the best parameter set’ was selected from the range of values. For the soil conditions investigated, the HF assimilation results are better than the open‐loop results. Copyright © 2010 John Wiley & Sons, Ltd.     

细粒含量对冰碛土抗剪强度影响的实验研究

为研究细粒组颗粒在浸水/降雨条件下产生迁移对冰碛土抗剪强度的影响,从西藏林芝市帕隆藏布嘎隆寺沟流域内采取冰碛土样品,进行7种不同细粒（粒径小于2 mm）含量情况下的冰碛土比重和相对密度的测试,开展了不同围压下的大型饱和固结不排水三轴（CU）实验。结果表明：（1）细粒含量对干密度的影响较小,不同细粒含量的冰碛土孔隙比大致相同,细颗粒对孔隙具有改造作用,不同细粒含量会引起孔隙结构的差异,从而导致冰碛土的结构差异,最终导致抗剪强度的不同;（2）细颗粒迁移导致冰碛堤坡脚和内部一定深度细粒含量较高,达到一定的量值时,抗剪强度明显降低,冰碛堤容易发生剪切破坏;（3）细粒含量对抗剪强度参数的变化具有重要影响,从中还可以反映出冰碛土结构控制的变化：粗颗粒控制→粗细颗粒共同控制→细颗粒控制。研究结果对于评价冰碛堤的稳定性具有重要意义。     

Simple formulas for the dynamic stiffness of pile groups

Simple formulas are derived for the dynamic stiffness of pile group foundations subjected to horizontal and rocking dynamic loads. The formulations are based on the construction of a general model of impedance matrices as the condensation of matrices of mass, damping, and stiffness, and on the identification of the values of these matrices on an extensive database of numerical experiments computed using coupled finite element–boundary element models. The formulations obtained can be readily used for the design of both floating piles on homogeneous half‐space and end‐bearing piles and are applicable for a wide range of mechanical and geometrical parameters of the soil and piles, in particular for large pile groups. For the seismic design of a building, the use of the simple formulas rather than a full computational model is shown to induce little error on the evaluation of the response spectra and time histories. Copyright © 2009 John Wiley & Sons, Ltd.     

基于强度参数演化行为的岩石峰后应力-应变关系研究

基于岩石材料峰后强度参数的演化行为,结合强度准则,提出了建立峰后应力-应变关系的一般方法。在此基础上,基于摩尔-库仑强度准则,以最大主应变 作为应变软化参数,假设黏聚力 ,内摩擦角 为主应变 的分段线性函数条件下,给出了岩石材料的峰后应力-应变关系式的求法。在数值算例中,利用提出的方法,给出了大理岩在不同围压下的应力-应变曲线,算例显示,利用这一方法求得的峰后应力-应变关系曲线变化趋势与试验数据基本一致,表明该方法在研究峰后应力-应变关系上具有一定的合理性。     

RESPONSE OF EQUATORIAL PACIFIC UPPER OCEAN CURRENT TO WESTERLY WIND BURSTS

The characteristics of the response of equatorial Pacific upper ocean current to westerly wind bursts(WWB)were analyzed in the frequency domain by using wind and ADCP data collected by the Shiyan3 during TOGA-COARE IOP,1992-1993.The preliminary results showed that the response consistedof an eastward surface jet at shallower than 60m depth,a westward counter current centering near100m and a shear layer between them,with the variations of all three being nonlinear and nearlysynchronous.The oceanic responses in the frequency domain were characterized by occurrences of a remotely forced mixed Rossby-gravity wave with period of 8-10 days in the surface jet andcountercurrent at shallower than 110 m depth,and two locally forced waves with periods of 24 daysand 4-5 days limited in shallower than 70m depth.These fluctuations of the responses depended much more on zonal wind than meridional wind.The results also revealed that the oceanic response toWWB resulted from momentum transport and energy propagation assoc