Expanded superposition method for impedance functions of inclined‐pile groups

This paper presents a superposition method expanded for computing impedance functions (IFs) of inclined‐pile groups. Closed‐form solutions for obtaining horizontal, vertical, and rocking IFs, estimated by using pile‐to‐pile interaction factors, are proposed. IFs of solitary inclined piles, crossed IFs, and explicit incorporation of compatibility conditions for pile‐head movements are also appropriately taken into consideration. All of these factors should be known in advance and will be computed and shown for the most relevant cases. The accuracy of the proposed closed‐form solutions is verified for 2 × 2 and 3 × 3 square inclined‐pile groups embedded in an isotropic viscoelastic homogeneous half‐space soil medium, with hysteretic damping. The pile‐to‐pile interaction factors are computed by means of a three‐dimensional time‐harmonic boundary elements–finite elements coupling formulation. The results indicate that the IFs obtained from the proposed method are in good agreement with those obtained from the coupling formulation. Furthermore, crossed vertical‐rocking IFs of solitary piles need to be appropriately considered for obtaining rocking IFs when the number of piles is small. Copyright © 2015 John Wiley & Sons, Ltd.     

晋城市粮食产量预测方法比较研究

提高粮食产量预测精度是科学编制土地利用总体规划的重要课题。该文首先运用灰色关联分析方法对影响粮食产量的因素做出关联因子排序,分析表明粮食单产对粮食总产量的影响最大,粮食作物播种面积次之。其次在灰色关联分析的基础上选取主要影响因子,通过比较线性回归模型、灰色GM(1,1)模型和灰色多元线性回归组合模型的预测结果,得到灰色多元线性回归组合模型预测结果最佳。     

使用多指数模型的 SAR 海冰图像偏差场校正

提出了一种使用多指数模型的SAR 海冰图像入射角偏差场校正的新算法, 该算法先对SAR 图像进行方 位向取平均, 然后用多指数模型对一维校正场建模, 应用熵值最小化方法求取最优的一维校正场, 再用推出的二维 校正场对原始图像进行校正。实验结果表明, 该算法对于SAR 海冰图像的入射角偏差场校正是有效的。与Karvonen 的算法相比, 该算法有更好的校正效果, 且不需要提供像素的入射角信息。     

一次由气旋发展与边界层东北气流触发的强对流天气分析

利用多种探测资料及NCEP/NCAR FNL 1°×1°再分析资料,对2019年4月24日发生在山西的大范围强对流天气进行了分析。结果表明：1）此次过程是在弱天气尺度强迫背景下,地面锋面气旋发展和低层偏东北气流伸入河套地区,触发了1个持续拉长状对流系统（persistent elongated convective systems,PECS）和1个β中尺度持续拉长状对流系统（meso-β-scale PECS,MβECS）发生发展造成的。2）与MβECS对应,雷达回波上表现为涡旋状的回波中镶嵌着多个对流单体,PECS则表现为4个线状回波和1个强降水单体风暴。雷达产品能更精细刻画较小尺度系统特征,但分类强对流的某些典型特征并不明显。3）物理量诊断揭示,低层锋生作用不仅使暖锋加强触发MβECS发展造成北部强对流,且使得冷锋加强和气旋发展,此背景下形成的边界层急流和地面中尺度系统导致中南部对流单体合并、加强并高度组织化。强对流范围和强度与涡旋或辐合线尺度及风场辐合强度密切相关,气旋内温压风湿场的扰动特征能更好地解释较小尺度系统形成发展的物理机制,且这些特征较强对流提前1～3 h出现,对强对流临近预报具有很好的指示意义。4）低层东北气流是干冷与暖湿空气的一个倾斜交界面,该面上各种要素并不均匀,围绕该支气流形成一个气旋式次级环流圈,是中尺度对流系统的重要触发机制;气流两侧存在较大纬向风垂直切变,是造成对流风暴传播、持续时间长的重要原因之一。     

地震心理预测的模糊数学模型

本文应用二级模糊综合评判方法,建立了地震心理预测的数学模型,并应用灰关联分析和概率论确定模型中的参数。既考虑了心理反应过程的模糊性,又考虑了它的随机性,使这个模型不仅比较合理,而且非常灵活、简便和实用。     

Ultimate uplift capacity of model rigid metal piles in clay

Summary Laboratory model test results for estimation of the ultimate uplift capacity of rigid metal piles embedded in a compacted near-saturated clayey soil are presented. The length-diameter ratio of the piles was varied from 10 to 15. The direction of the uplift load on the pile was varied from 0 to 50°. Based on the present test results and the results of existing model studies, an empirical relationship for estimating the pile uplift capacity has been presented.     

中深孔直斜两用轻便钻塔的研制及应用

在调研国产立轴式岩心钻机的基础上,经过充分论证,提出了直、斜两用钻塔的设计方案。直、斜两用钻塔的成功研发,解决了国产立轴式岩心钻机不宜施工斜孔的问题,拓展了国产立轴式岩心钻机的使用空间。介绍了该钻塔的设计思路、结构设计及其生产试验效果。     

Facies model of a fine‐grained,tide‐dominated delta: Lower Dir Abu Lifa Member (Eocene), Western Desert,Egypt

Existing facies models of tide‐dominated deltas largely omit fine‐grained, mud‐rich successions. Sedimentary facies and sequence stratigraphic analysis of the exceptionally well‐preserved Late Eocene Dir Abu Lifa Member (Western Desert, Egypt) aims to bridge this gap. The succession was deposited in a structurally controlled, shallow, macrotidal embayment and deposition was supplemented by fluvial processes but lacked wave influence. The succession contains two stacked, progradational parasequence sets bounded by regionally extensive flooding surfaces. Within this succession two main genetic elements are identified: non‐channelized tidal bars and tidal channels. Non‐channelized tidal bars comprise coarsening‐upward sandbodies, including large, downcurrent‐dipping accretion surfaces, sometimes capped by palaeosols indicating emergence. Tidal channels are preserved as single‐storey and multilateral bodies filled by: (i) laterally migrating, elongate tidal bars (inclined heterolithic strata, 5 to 25 m thick); (ii) forward‐facing lobate bars (sigmoidal heterolithic strata, up to 10 m thick); (iii) side bars displaying oblique to vertical accretion (4 to 7 m thick); or (iv) vertically‐accreting mud (1 to 4 m thick). Palaeocurrent data show that channels were swept by bidirectional tidal currents and typically were mutually evasive. Along‐strike variability defines a similar large‐scale architecture in both parasequence sets: a deeply scoured channel belt characterized by widespread inclined heterolithic strata is eroded from the parasequence‐set top, and flanked by stacked, non‐channelized tidal bars and smaller channelized bodies. The tide‐dominated delta is characterized by: (i) the regressive stratigraphic context; (ii) net‐progradational stratigraphic architecture within the succession; (iii) the absence of upward deepening trends and tidal ravinement surfaces; and (iv) architectural relations that demonstrate contemporaneous tidal distributary channel infill and tidal bar accretion at the delta front. The detailed facies analysis of this fine‐grained, tide‐dominated deltaic succession expands the range of depositional models available for the evaluation of ancient tidal successions, which are currently biased towards transgressive, valley‐confined estuarine and coarser grained deltaic depositional systems.     

北斗IGSO/MEO卫星姿态控制及光压差异分析

为规避GPS等国外卫星导航系统动态偏航姿态控制模式中的地影机动以及正午和午夜机动,北斗IGSO/MEO卫星采用了动态偏航和零偏航两种姿态控制模式。针对姿态控制模式引起的卫星本体、帆板受照及光压力的变化对定轨、定位解算造成的影响,该文通过对卫星姿态及受照的分析,查找由于姿态变化所造成的卫星光压摄动力变化的转换点,指出引起动偏、零偏下卫星光压摄动力差异的主要因素是零偏下入射太阳光线与太阳帆板不垂直,存在小角度夹角;两种姿态控制模式下光压摄动力的差异量级在10-8 m/s2。该研究成果可以为北斗卫星轨道确定提供技术支持。     

悬臂式支护结构中几种控制变形的方法

悬臂式支护结构是基坑工程中常用的支护形式,多以排桩、地下连续墙、工法桩、钢板桩等形式出现。基坑工程中在条件受限的情况下,无法做内撑,但周边部分建（构）筑物对基坑变形很敏感,需要采取一些辅助措施来控制基坑的变形。结合工程实例介绍了悬臂式支护结构中常用的几种控制变形的方法,包括双排桩外拉、锚杆（索）加固、基坑内斜撑、基坑内土加固、坑内预留反压土等,并对这几种方法的适用范围、技术要求等进行了分析,为今后类似工程的设计施工提供借鉴。