考虑结构性的冻融作用对黄土湿陷系数的影响     

丑亚玲  郏书胜  张庆海  曹伟  盛煜 《岩土力学》2018,39(8):2715-2722

结构性是黄土的基本属性,黄土的湿陷特性与其结构性之间有着必然的联系。针对冻融作用对不同结构性黄土湿陷性的影响,以水泥作为模拟土颗粒间的联结材料制备了人工结构性土,开展了不同水泥含量的人工结构性土与相应的原状土、重塑土的湿陷试验,分析了结构性、冻融作用、初始含水率、湿重度及荷载大小对湿陷系数的影响规律。试验结果表明：冻融前后,人工结构性黄土的湿陷系数均比原状土、重塑土的湿陷系数小,且随着水泥含量的增加,湿陷系数有所减小;冻融之后,各土样的湿陷系数几乎均有所增加,但增加的程度和土样初始结构、含水率、干密度（压实系数）及竖向荷载关系密切,尤其当含水率接近最优含水率和土样为重塑土或水泥含量较低的人工结构性土时,冻融后湿陷系数增大幅度显著。在标准荷载200 kPa下,冻融前后原状土、重塑土的湿陷系数与其湿重度之间基本呈较好的线性负相关关系,而人工结构性黄土湿陷系数与湿重度之间并不呈线性关系;竖向荷载为50 kPa时,重塑黄土和5%水泥含量黄土的湿陷系数与冻融次数之间存在着较好的对数关系。以水泥作为土颗粒间联结材料,制备的人工结构性土是否能很好地代替原状土反映结构性黄土的湿陷特性,还需更进一步深入研究。  相似文献   

CO_2 Density-Raman Shift Relation Derived from Synthetic Inclusions in Fused Silica Capillaries and Its Application     

SONG Yucai  CHOU I’Ming  HU Wenxuan  Burruss ROBERT  LU Wanjun 《《地质学报》英文版》2009,83(5):932-938

Abstract: The densities of CO2 inclusions in minerals are commonly used to determine the crystallizing conditions of the host minerals. However, conventional microthermometry is difficult to apply for inclusions of small size (< 5–10 μm) or low density. Raman analysis is an alternative method for determining CO2 density, provided that the CO2 density–Raman shift relation is known. This study aims to establish this CO2 density–Raman shift relation by using CO2 inclusions synthesized in fused silica capillaries. By using this newly-developed synthetic technique, we formed pure CO2 inclusions, and their densities were determined by microthermometry. The Raman analysis showed that the relation between CO2 density (D in g/cm3) and the separations (Δ in cm?1) between the two main bands (i.e. Fermi diad bands) in CO2 Raman spectra can be represented by a cubic equation: D (g/cm3)=0.74203(?0.019Δ3+5.90332Δ2?610.79472Δ+21050.30165)?3.54278 (r2=0.99920). Our calculated D value for a given Δ is between those obtained from two previously-reported equations, which were derived from different experimental methods. An example was given in this study to demonstrate that the densities of natural CO2 inclusions that could not be derived from microthermometry could be determined by using our method.  相似文献   

Review of the Study of Nonlinear Atmospheric Dynamics in China （1999-2002）   总被引：1，自引：0，他引：1  

DIAO Yin  FENG Guolin  LIU Shi  LIU Shikuo  LUO Dehai  HUANG Sixun  LU Weisong  CHOU Jifan 《大气科学进展》2004,21(3):399-406

Researches on nonlinear atmospheric dynamics in China (1999-2002) are briefly surveyed. This review includes the major achievements in the following branches of nonlinear dynamics: nonlinear stability theory,nonlinear blocking dynamics, 3D spiral structure in the atmosphere, traveling wave solution of the nonlinear evolution equation, numerical predictability in a chaotic system, and global analysis of climate dynamics.Some applications of nonlinear methods such as hierarchy structure of climate and scaling invariance, the spatial-temporal series predictive method, the nonlinear inverse problem, and a new difference scheme with multi-time levels are also introduced.  相似文献   

Recent Advances in Predictability Studies in China （1999-2002）   总被引：10，自引：2，他引：8  

MU Mu  DUAN Wansuo  CHOU Jifan 《大气科学进展》2004,21(3):437-443

Since the last International Union of Geodesy and Geophysics (IUGG) General Assembly (1999), the predictability studies in China have made further progress during the period of 1999-2002. Firstly, three predictability sub-problems in numerical weather and climate prediction are classified, which are concerned with the maximum predictability time, the maximum prediction error, and the maximum allowable initial error, and then they are reduced into three nonlinear optimization problems. Secondly, the concepts of the nonlinear singular vector (NSV) and conditional nonlinear optimal perturbation (CNOP) are proposed,which have been utilized to study the predictability of numerical weather and climate prediction. The results suggest that the nonlinear characteristics of the motions of atmosphere and oceans can be revealedby NSV and CNOP. Thirdly, attention has also been paid to the relations between the predictability and spatial-temporal scale, and between the model predictability and the machine precision, of which the investigations disclose the importance of the spatial-temporal scale and machine precision in the study of predictability. Also the cell-to-cell mapping is adopted to analyze globally the predictability of climate,which could provide a new subject to the research workers. Furthermore, the predictability of the summer rainfall in China is investigated by using the method of correlation coefficients. The results demonstrate that the predictability of summer rainfall is different in different areas of China. Analysis of variance, which is one of the statistical methods applicable to the study of predictability, is also used to study the potential predictability of monthly mean temperature in China, of which the conclusion is that the monthly mean temperature over China is potentially predictable at a statistical significance level of 0.10. In addition,in the analysis of the predictability of the T106 objective analysis/forecasting field, the variance and the correlation coefficient are calculated to explore the distribution characteristics of the mean-square errors.Finally, the predictability of short-term climate prediction is investigated by using statistical methods or numerical simulation methods. It is demonstrated that the predictability of short-term climate in China depends not only on the region of China being investigated, but also on the time scale and the atmospheric internal dynamical process.  相似文献   

农村居民点整理潜力测算与布局优化研究——以江苏省江都市为例   总被引：5，自引：1，他引：4  

李鑫  甘志伍  欧名豪  黄琪  丑建立 《地理科学》2013,(2):150-156

通过自然、经济与社会因素方面构建限制修正系数,用限制修正系数把理论潜力修正至现实潜力,且从区位、自然等方面对整理后居民点进行布局优化,在ArcGIS 9.3中用多因素综合评价法评价栅格单元的居民点建设适宜度,把适宜度高的栅格变成居民点用地,直到所选择栅格面积等于现状居民点释放完潜力而保留的面积。研究发现2008年江都市居民点整理的理论潜力是6 128 hm2,经限制因素修正后现实潜力是2 013 hm2,其中半数以上在仙女镇;经布局优化后居民点集中分布,且主要集中分布在城镇周围与交通便捷地区,改变了目前散乱分布状况,居民点分布斑块数减少,其集聚度显著增加。  相似文献   

On-line estimation of unit hydrographs using the wavelet-based LMS algorithm / Estimation en ligne des hydrogrammes unitaires grâce à l'algorithme des moindres carrés moyens à base d'ondelettes     

CHIEN-MING CHOU  RU-YIH WANG 《水文科学杂志》2013,58(5):721-738

Abstract

This study applies the discrete wavelet transform (DWT) to decompose the unit hydrograph, thereby generating parsimonious reparameterizations of the unit hydrograph. A model compression method is then employed to significantly compress the unit hydrograph requiring that fewer coefficients be estimated. Moreover, a wavelet-based linearly constrained least mean squares (WLCLMS) algorithm is also used to estimate on-line the wavelet coefficients of the unit hydrograph. The updated wavelet coefficients of the unit hydrograph, convoluted with effective rainfall input in the wavelet domain, allow for accurate prediction of one-step-ahead runoff in the time domain. The proposed approach allows the unit hydrographs to vary in time and accurately predicts runoff from a basin in Taiwan, thus making it highly promising for flood forecasting.  相似文献   

基于DEM不同路径算法的沟壑密度提取   总被引：1，自引：0，他引：1  

郭兰勤  丑述仁 《地下水》2011,(6):145-147

沟壑密度是评价小流域沟蚀程度的重要指标,同时也是反映地表破碎程度的因子。采用合理的汇流阈值设置方法,在黄土高原县南沟流域,通过基于坡向流量分配的多流向算法(DEMON)和传统的单流向算法D8实现沟壑密度的提取。结果表明:多流向算法和单流向算法都能提取较合适的沟壑密度,其中多流向算法提取的结果更好一些。因此,本研究对地表破碎程度的描述和当地地形地貌的反映有重要的意义。  相似文献   

利用P波和S波的初动和振幅比计算中小地震的震源机制解   总被引：41，自引：2，他引：39  

刘杰  郑斯华  康英  啜永清 《地震》2004,24(1):19-26

应用Snoke最新发展的利用P波、 SV波、 SH波的初动和振幅比联合计算地震震源机制解的程序, 使用一些省地震局数字台网得到的数字波形资料, 尝试计算了中小地震的震源机制解, 并与原来仅用P波初动得到的结果进行对比研究。 结果表明, 这种方法是可行的。 该方法为数字地震资料在地震预测中的应用提供了一种新的可能。  相似文献   

美国气候新政背景下的中国未来CO2排放情景预测     

丑洁明  代如锋  董文杰  班靖晗  胡川叶 《气候变化研究进展》2018,14(1):95-105

本文应用LMDI分解分析方法对中国2000—2014年生产部门CO₂排放量变化做因素分解分析,同时结合STIRPAT模型建立CO₂预测模型,分析2017—2030年中国的CO₂排放情况。结果表明,经济增长和能耗强度变化对中国CO₂排放量变化的影响分别为114.9%、-22.6%。基于预测模型变量构建未来情景,设定正常路线、减排路线和激进路线3条路线,共包含9种情景。正常路线的低碳情景和减排路线的基准情景下可实现2025年达到CO₂排放峰值,减排路线的低碳情景可实现2020年达到排放峰值。  相似文献   

CONDITIONAL SAMPLING AND SCALE ANALYSIS OF THE MARINE ATMOSPHERIC MIXED LAYER -- SOFIA EXPERIMENT     

ANNE RéCHOU  PIERRE DURAND 《Boundary-Layer Meteorology》1997,82(1):81-104

During the SOFIA experiment, performed in the Azores region in June1992, airborne missions were conducted in the atmospheric boundary layerwith two aircraft instrumented for turbulence measurements. We show howthe conditional sampling technique, applied to the velocity, temperatureand moisture fluctuations, is able to describe the various parcels whichconstitute the turbulent field. Each parcel, so identified, is characterized byits fractional area and by its contribution to the transfers of sensible heat andlatent heat. On the other hand, a scale analysis is conducted by filteringthe turbulent signals in five non-overlapping frequency bands, definedaccording to the characteristic turbulent scales. The contribution of eachband to the turbulent energy and to the transfers is thus presented. Theimportance of the lowest frequencies, which are generally removed fromthe signals by high-pass filtering before computing turbulent fluxes, isshown. In the final section, the conditional sampling technique is applied tothe signals filtered in the various bands. Despite a slight deformation of theeddies due to the filtering technique, the contribution of each parcel can beestimated at the various scales analysed.  相似文献