地震动记录选取及其对网架屋盖动力响应的影响

地震动记录的合理选取对预测结构响应有着重要的作用。本文通过对风雨操场建筑混合结构的抗震性能分析,提出了一种对水平及竖向地震动频谱特性均进行控制的改进选波方法。为了评价不同选波方法的可靠性和有效性,根据初选条件选取55组三向地震动记录,并以55组地震动的统计反应谱作为目标反应谱,以55组记录计算的结构响应均值作为"预测值",通过与单周期点和双频段选波方法的计算结果对比,分析表明:改进选波方法计算的结构基底剪力、柱顶位移、支座位移和网架竖向位移的相对误差和变异系数均小于前两种选波方法,其计算结果更加可靠有效。     

超大沉井基础取土下沉刃脚土压力变化规律研究

依托常泰长江大桥主塔沉井基础工程,采用三维有限元方法,模拟了大型沉井首次取土下沉阶段刃脚土压力的变化过程,并结合现场刃脚土压力实测数据,分析了沉井下沉工序对刃脚土压力分布的影响以及取土过程中刃脚土压力的变化规律。现场监测结果表明：刃脚实际土压力变化规律基本上佐证了数值模拟结果。井孔内取土导致取土区域沉井刃脚处土压力下降,取土区域刃脚土压力随取土厚度的增大而逐渐降低,土体压应力转移至尚未取土区域的刃脚处。在由内井孔向外井孔区域取土的过程中,刃脚土压力向外井孔刃脚区域转移,导致外井壁和外隔墙区域刃脚土压力逐渐增大,直至达到其极限承载力,外井壁区域土体进入塑性状态,沉井出现明显下沉。给出的沉井刃脚处土压力的变化规律可为同类大型沉井可控下沉提供指导。     

武汉钰龙金融广场超深基坑工程设计方案选型

以武汉钰龙金融广场超深基坑工程为实例,在结合常用的深基坑设计方案的基础上分别从基坑总体设计方案选定、基坑围护体系选定和设计、支撑体系选定、基坑降水选定、土方开挖方案选型和换撑方案的选定等方面进行探讨,并确定最终的基坑工程设计方案选型,即地下连续墙围护+3道内支撑+管井降水处理承压水的支护方案。     

基于双边结构张量的局部自适应图像超分辨率重建

利用超分辨率重建技术可以有效提高图像的空间分辨率,其中先验模型的选取尤为关键。在最大后验概率(MAP)的框架下引入双边结构张量测度,联合像素邻域4个方向的梯度算子提出一种局部自适应先验方法,构建图像超分辨率重建模型,并利用迭代重加权范数(iteratively reweighted norm)对其进行转换求解。基于标准的测试图像进行了实验,并将本方法与拉普拉斯先验、Huber-Markov先验以及BTV先验的重建结果进行对比,验证了该方法的有效性。     

Towards More Snow Days in Summer since 2001 at the Great Wall Station,Antarctic Peninsula:The Role of the Amundsen Sea Low

The variation in the precipitation phase in polar regions represents an important indicator of climate change and variability.We studied the precipitation phase at the Great Wall Station and Antarctic Peninsula(AP)region,based on daily precipitation,synoptic records and ERA-Interim data during the austral summers of 1985?2014.Overall,there was no trend in the total precipitation amount or days,but the phase of summer precipitation(rainfall days versus snowfall days)showed opposite trends before and after 2001 at the AP.The total summer rain days/snow days increased/decreased during 1985?2001 and significantly decreased at a rate of?14.13 d(10 yr)?1/increased at a rate of 14.31 d(10 yr)?1 during 2001?2014,agreeing well with corresponding variations in the surface air temperature.Further,we found that the longitudinal location of the Amundsen Sea low(ASL)should account for the change in the precipitation phase since 2001,as it has shown a westward drift after 2001[?41.1°(10 yr)?1],leading to stronger cold southerly winds,colder water vapor flux,and more snow over the AP region during summertime.This study points out a supplementary factor for the climate variation on the AP.     

Simulation of the Direct Radiative Effect of Mineral Dust and Sea Salt Aerosols in a Doubled Carbon Dioxide Climate

The authors examine the equilibrium climatic response to the direct radiative effect(DRE)of mineral dust and sea salt aerosols in a doubled-CO2climate with two-way coupling of aerosol-climate interactions.In response to the drier and windier conditions,dust emissions increase by 26%in the Sahara Desert and by 18%on the global scale relative to present day.Sea salt emissions increase in high latitudes(60°)but decrease in middle latitudes(30°–60°)of both hemispheres due to the poleward shift of westerlies,leading to a 3%decrease in global emissions.The burdens of dust and sea salt increase by 31%and 7%respectively,because reductions in rainfall over the tropical oceans increase the lifetime of particles in the warmer climate.The higher aerosol loading in the doubled-CO2climate reinforces aerosol DRE by0.2 W m 2,leading to an additional cooling of 0.1°C at the surface compared with the climatic effects of aerosols in present day.The additional cooling from changes in natural aerosols compensates for up to 15%of the regional warming induced by doubled CO2.     

矿业开发与生态环境一体化

概述了矿业开发与生态环境的关系 ,矿业开发与生态环境一体化的原则和组织 ,国内外现状和发展趋势 ,对河南省矿业生态环境存在问题及其原因进行了综合分析 ,论述了矿业开发与生态环境一体化的准则与前景 ,提出今后工作建议。     

地幔岩包体中金富集规律——以中国东部地幔岩包体为例

采集中国东部玄武岩中橄榄岩包体27件,测定了其主量元素氧化钙、贵金属金以及其中21件橄榄岩包体的铂族元素。橄榄岩包体中金与氧化钙质量分数的相关性表明,金在地幔演化初期可能主要赋存于单斜辉石中,反映地幔包体中金可能与地幔演化及熔融程度有关。饱满型或弱亏损型橄榄岩包体具有相似平坦的铂族元素球粒陨石标准化分布模式,其都对应有高的金质量分数;而强亏损型橄榄岩包体的铂族元素球粒陨石标准化分布模式呈下降趋势,且对应橄榄岩包体的金质量分数均较低。     

用正行列式解瓶颈指派问题

用正行列式作为工具,给出了瓶颈指派问题新的解法,并利用正行列式的值求出了瓶颈指派问题的全部最优解。最后通过一个实例说明该算法的实用和有效性。     

APPEARANCE PATTERN OF TOOTH GERMS WITH DEVELOPMENTAL PROCESS IN MYLOPHARYNGODON PICEUS

The pharyngeal dental formula of Mylopharyngodon piceus is 4-5 as a rule, and the dentition isasymmetrical. It is difficult to identify each tooth in the larval dentition. In this paper the appearancepattem of tooth germ with developmental process in this fish is described in detail. The formationpattern of the left dentition is contrasted with that of the right one. In the developmental process,the left pharyngeal dentition lacks teeth at position An3. Thus the left dentition is D-type as designatedby Nakajima(1984), while the right one is A-type.