敦煌雅丹地层沉积物粒度特征初步研究

雅丹地层是雅丹地貌发育前整个沉积体系的物质体现,记录了沉积过程中的大量信息,而沉积物分析则是解读其关键信息的基础.以敦煌雅丹地貌为研究对象,对其出露地层的沉积物粒度特征进行了初步研究.结果表明:(1)敦煌雅丹地层沉积物粒径组成以粉沙为主,平均含量分别为41.08％(YA)、36.82％(YB)和35.41％(YC),自...     

Zero mass scalar field with bulk viscous cosmological solutions in Lyra geometry

In this paper, we have investigated spatially homogeneous isotropic Friedmann cosmological model with bulk viscosity and zero-mass scalar field in Lyra manifold. The cosmological models are obtained with the help of the special law of variation for Hubble’s parameter proposed by Bermann (Nuovo Cimento 74B:182, 1983) and power law relation. Some physical properties of the models are discussed.     

Calculating the Light Period of BL Lac Object S5 0716+714 by Wavelet Analysis Method

A kind of wavelet analysis method for identifying the light period of the BL Lac object S5 0716+714 is introduced. The rather complete observed data in the four optical wavebands B, V, R, I are collected, and the long-term light curves based on 10-day averaging are obtained. On these light curves, the periodicity analysis is performed by using a wavelet analysis method. The result demonstrates that the wavelet analysis method is preferable for searching and identifying the light periods of BL Lac objects. From the contour map of the real part of the wavelet transform coefficient, the periodical light variations of the BL Lac object S5 0716+714 can be precisely identified. By analyzing the wavelet variance curves at the 4 wavebands, it is found that the BL Lac Object S5 0716+174 has a stable light period of 1160 days. This result is consistent with the 3.3-year period given by Raiteri et al. It is predicted that the next outburst in this object will happen around the August of 2011.     

γ射线脉冲星的代参数和能谱分析

为了对脉冲星的高能辐射进行研究,根据脉冲星观测的实际情况,重新推导了脉冲星代参数的计算公式.发现脉冲星的代参数与其γ射线能谱有很好的线性相关性,并拟合了代参数和能谱之间的线性关系.     

VARIATION FEATURES OF SOMALI CROSS-EQUATORIAL FLOW AND ITS IMPACT ON THE LOCATION OF THE SUBTROPICAL HIGH RIDGE FROM JULY TO SEPTEMBER

The variation features of the cross-equatorial flow and its impact on the ridge position of the subtropical high have been analyzed in this paper. It is shown as follows. (1) The intensity of the Somalicross-equatorial flow is increasing in winter and summer in the past 44 years and the airflow of Northem Hemisphere exchanges more and more intensively with that of Southern Hemisphere. (2) The Somalicross-equatorial flow in May has the most impact on the ridge position of the subtropical high in the typhoon season, presenting a positive correlation. (3) The diagnosis is consistent with the real situation in 2005.     

城市化发展与气象环境影响的观测与分析研究

通过分析2002年7月12日和2006年5月4日Landsat-5高分辨率资源卫星资料,表明南京市热岛分布特征与南京市的城市建设和区域经济发展的空间特征相当一致,土地利用类型、地表反照率、叶面积指数、植被覆盖度等地表参数分布与城市热岛分布相吻合.运用数值模拟手段对南京城市化对边界层特性产生的影响进行研究,结果表明,随着城市发展,地表反照率减小、植被减少、地表湿度降低,使蒸发耗热减小、感热通量增多,城市波恩比增加,地表和大气间的热交换增强.     

湿热力平流参数在贵州初夏强降水中的运用

使用NCEP(1°×1°)再分析资料计算湿热力平流参数及其积分,通过对比分析2008—2009年初夏(5—6月)地面实况降水与该因子积分后的中心大值区的对应关系。理论分析表明:湿热力平流参数综合体现了锋区附近大气的动力、热力及水汽作用,相对于常用的相当位温、湿度等常用物理量来说,在一定程度上包含了广义位温及位温平流的相互作用,对实际非均匀饱和大气的动热力变化及水汽有较好的反映。统计分析也表明:积分后的湿热力平流参数中心值区与地面6小时强降水落区有较好的对应关系,它的变化趋势及移动方向与强降水区的变化也较一致,能作为短时强降水落区预报提供参考;利用NCEP/NCAR(1°×1°)再分析资料和Micaps地面实况降水资料,选取2009年6月7-9日发生在贵州的强降水过程为例,通过把湿热力平流参数与此次过程中动、热力场结合进行诊断分析,进一步表明该参数能综合地反应锋面强降水系统中的水汽、动力及热力的垂直结构特征,能作为造成强降水的锋面系统的示踪物。     

Statistical inverse analysis based on genetic algorithm and principal component analysis: Applications to excavation problems and pressuremeter tests

This study concerns the identification of constitutive models from geotechnical measurements by inverse analysis. Soil parameters are identified from measured horizontal displacements of sheet pile walls and from a measured pressuremeter curve. An optimization method based on a genetic algorithm (GA) and a principal component analysis (PCA), developed and tested on synthetic data in a previous paper, is applied. These applications show that the conclusions deduced from synthetic problems can be extrapolated to real problems. The GA is a robust optimization method that is able to deal with the non‐uniqueness of the solution in identifying a set of solutions for a given uncertainty on the measurements. This set is then characterized by a PCA that gives a first‐order approximation of the solution as an ellipsoid. When the solution set is not too curved in the research space, this ellipsoid characterizes the soil properties considering the measured data and the tolerate margins for the response of the numerical model. Besides, optimizations from different measurements provide solution sets with a common area in the research space. This intersection gives a more relevant and accurate identification of parameters. Finally, we show that these identified parameters permit to reproduce geotechnical measurements not used in the identification process. Copyright © 2009 John Wiley & Sons, Ltd.     

钻机性能参数测试系统的研制

简要介绍了新研制钻机性能试验装置的测试技术方法、构成,测试试验台架、加载装置、加载控制器、测试控制系统等。     

基于广义Hoek-Brown准则边坡稳定性分析强度折减法

目前的强度折减法大多基于Mohr-coulomb准则,而较少基于Hoek-Brown准则。为了在Hoek-Brown准则中实施强度折减法,并使其得到的结果与Mohr-coulomb准则中强度折减法得到的结果等效,本文利用Hoek-Brown准则参数m、s、σci与粘结力c和内摩擦角φ之间的关系,在Hoek-Brown准则中同时对m、s实施强度折减,通过理论推导得到m、s折减系数之间的关系;并进一步推导得到m、s折减系数与基于Mohr-coulomb准则强度折减系数之间的关系;最后,由FLAC3D软件建立计算模型,采用所确定的折减方法计算边坡的安全系数,并将该结果与极限平衡法所得到计算结果进行比较,结果表明:本文确定的折减方法与极限平衡法所得到的安全系数的相差仅1.76%,验证了本文所确定的强度折减法的可行性。