准同时岩相古地理图的制作新方法

本文以“层序地层学”理论为基础,运用“空间上相序的有序性”及“时间上环境变化的同步性”原理,解决了区域地层等时或准等时对比的问题,基本实现了用等时或准等时地层单元作为岩相古地理图的编图单位,克服了传统制作方法用不等时的岩石地层单位“组、段”为编图单位造成的岩相古地理图的“歪曲”及垂向沉积环境变化“掩盖”的弊病。“准同时岩相古地理图制作新方法”可分为单剖面层序地层柱状图、高分辨率层序地层柱状对比图、准同时岩相古地理系列图等3个研究阶段。同一海盆中,海平面升降是同步的,那么区域上相应的三级层序是等时的,其中以层序界面、首泛面、最大海泛面及海退面等物理界面划分出的低水位、海进、高水位及强迫性海退楔等体系域亦是等时的。因此,将区域上各单剖面柱状图中的上述相应的物理界面相连,就形成了研究区的等时对比格架图,然后对等时格架中的地层再进行进一步对比,形成对比图,在此基础上选取等时地层单位进行岩相古地理系列图的编制。笔者并以江西省中部萍乐坳陷西段乐平世早期岩相古地理研究成果实例做了进一步的阐述,通过“准同时岩相古地理图制作的新方法”,提高了等时对比精度,制作的岩相古地理系列图不但充分反映了该时期岩相古地理的纵横变化,而且清楚地反映出地壳运动与海平面升降的联合作用对沉积环境变化的控制,并将编图单位缩短到尽可能短的时间内,使古地理图精度更高、内容更丰富、更接近客观实际。     

二维视电阻率断面的快速最小二乘反演

快速最小二乘反演是以平滑限定的最小二乘方法为基础,是对二维视电阻率断面进行反演的一种方法。反演过程不需要提供初始模型,在首次迭代时使用一均匀介质地下模型作为初始模型,该模型的视电阻率偏导数值可以用解析法得到。在后面的迭代中,使用了拟牛顿法去修改每一次迭代的偏导数矩阵,避免了偏导数矩阵的直接计算,从而减少了计算时间和存储空间。同时运用牛顿矩阵校正技术解最小二乘方程组也减少了大量的计算时间。总之,该方     

A macroscopic damage‐plastic constitutive law for modeling quasi‐brittle fracture and ductile behavior of concrete

A new phenomenological macroscopic constitutive model for the numerical simulation of quasi‐brittle fracture and ductile concrete behavior, under general triaxial stress conditions, is presented. The model is particularly addressed to simulate a wide range of confinement stress states, as also, to capture the strong influence of the mean stress value in the concrete failure mechanisms. The model is based on a two‐surface damage‐plastic formulation. The mechanical behavior in different domains of the stress space is separately described by means of a quasi‐brittle or ductile material response:

相似文献   

CHARACTERISTICS OF SEASONAL VARIATION OF RAINFALL OVER THE TIBETAN PLATEAU DURING SUMMER 1998 AND ITS IMPACT ON EAST ASIAN WEATHER*

The seasonal variation of rainy season over the Tibetan Plateau in summer 1998 is analyzed by using daily observational rainfall data for Lhasa from 1955 to 1996,and rainfall data at 70 stations from January to August of 1998 over the Tibetan Plateau (TP) and adjacent regions,as well as TBB data from May to August of 1998.The onset date of rainy season for Lhasa is climatologically 6 June.Among the analyzed years,the earliest onset date is 6 May,while the latest may delay to 2 July.The obvious inter-decadal variation can be found in the series of onset date.The onset date of summer 1998 over middle TP (onset date of Lhasa) is 24 June,which is relatively later than the normal case.The onset for rainy season of 1998 started over southeast and northeast parts of TP and then propagated westward and northward.The convection over east and west parts of TP shows that there is a quasi 12-15 day oscillation.In June,the convection over middle and lower reaches of Yangtze River is formed by the westward propagation of convection over subtropical western Pacific.while in July.it is formed by the eastward propagation of convection over TP.Besides,it is also found that there exists good negative and obvious advance and lag correlation between the convection over the middle and western TP and that over the subtropical western Pacific and southern China.Therefore it can be inferred that a feedback zonal circulation with a quasi two-three week oscillation exists between the ascending region of TP and descending region of subtropical western Pacific,i.e.the convection over TP may affect the subtropical high over western Pacific and vice versa.     

准四年周期的北半球夏季遥相关与东亚夏季风环流的相互关系

利用ＮＭＣ的２００ｈＰａ和８５０ｈＰａ风场资料研究了北半球夏季遥相关和东亚夏季风异常环流在准４年时间尺度上的相互关系。研究发现当北半球夏季出现积雪强迫型遥相关时,东亚－西太平洋地区既存在异常纬向环流,也存在异常经向环流;而当出现东亚太平洋型遥相关时,东亚－西太平洋地区以异常纬向环流为主。分析还发现源于北太平洋的异常涡旋在向南传播的过程中,先取西南路径,在到达菲律宾东部以后折向东南。     

含大地形的准地转正压模式的孤立波解

该文由修正过的含大地形的准地转正压模式方程出发,考虑青藏高原大地形的实际情况,忽略其东西向地形坡度,再利用约化摄动方法,求其孤立波解,并得到结论：当基本气流无切变时,地形是产生Rossby孤立波的必要因子。     

时间平均基流中准定常波的传播及多向折射

应用几何光学中的射线理论，直观地讨论了准定常波在时间平均基流中的传播，解释了定常 传播的纬向非均匀性。结果表明：折射指数平方可表示为基流绝对对基流流函数的微商，定常波的传播路径与折射指数平方的空间分布有着密切的关系。     

低平流层准两年变率研究

分析ＮＣＡＲ／ＮＣＥＰ４０年分析资料得出,赤道低平流层纬向风年际变率的平均周期约２８．２个月,最大振幅的２０ｈＰａ,西（东）风距平平垂直下传平均速度１．２１（１．０４）ｋｍ／月。用１０ｈＰａ和７０ｈＰａ月平均纬向风标准化距平之差反映整层准两年变率的相位。低平流层两半球中纬气温有与之配合的振荡,西（东）风切变时,中纬气温偏低（高）。赤道纬向风准两年变率引起的经圈环流异常是联系低续续向风与中纬气温准年     

区域似大地水准面精化模型算法的优选

建立高精度、高分辨率的区域似大地水准面模型是GPS高程测量在实际应用中必须解决的首要问题,分别介绍BP神经网络、曲面拟合的模型及算法,并基于焦作市GPS测量数据,通过MATLAB编程计算和分类实验,验证几种算法的有效性与可靠性,结果证明神经网络算法要优于其它算法,最后给出有益的结论.     

EGM96/2008重力场模型在似大地水准面构建中的应用

似大地水准面的构建可以将GPS测量的高程迅速转化为正常高,极大降低高程测量的成本,提高相关工作效率。将EGM96/2008重力场模型与“移去-恢复”法相结合,在矿区内建立似大地水准面,并使用不同的插值方法,验证最优方案。结果表明,使用二次线性插值的EGM2008重力场模型拟合效果更好,模型外符合精度达到3.6 mm,更适合应用于该区域似大地水准面构建。