Sharp and laterally constrained multitrace impedance inversion based on blocky coordinate descent

Seismic impedance inversion is a well-known method used to obtain the image of subsurface geological structures. Utilizing the spatial coherence among seismic traces, the laterally constrained multitrace impedance inversion (LCI) is superior to trace-by-trace inversion and can produce a more realistic image of the subsurface structures. However, when the traces are numerous, it will take great computational cost and a lot of memory to solve the large-scale matrix in the multitrace inversion, which restricts the efficiency and applicability of the existing multitrace inversion algorithm. In addition, the multitrace inversion methods are not only needed to consider the lateral correlation but also should take the constraints in temporal dimension into account. As usual, these vertical constraints represent the stratigraphic characteristics of the reservoir. For instance, total-variation regularization is adopted to obtain the blocky structure. However, it still limits the magnitude of model parameter variation and therefore somewhat distorts the real image. In this paper, we propose two schemes to solve these issues. Firstly, we introduce a fast algorithm called blocky coordinate descent (BCD) to derive a new framework of laterally constrained multitrace impedance inversion. This new BCD-based inversion approach is fast and spends fewer memories. Next, we introduce a minimum gradient support regularization into the BCD-based laterally constrained inversion. This new approach can adapt to sharp layer boundaries and keep the spatial coherence. The feasibility of the proposed method is illustrated by numerical tests for both synthetic data and field seismic data.     

VHF闪电定位技术评述

介绍了时间差法、干涉法闪电VHF电磁辐射源定位技术原理,以及不同技术的发展和应用,并对比分析了不同定位技术的优缺点：时差定位技术对孤立脉冲波形辐射定位效果较好,对持续时间较长的连续脉冲定位较难,且受地形影响较大;窄带干涉仪技术对孤立脉冲和连续脉冲均能很好定位,但不能很好地对同时发生的多个辐射源定位;宽带干涉仪系统可对同时发生的多个辐射源定位,但精度相对较低。     

鲁东晚白垩世玄武岩及其中幔源包体的岩石学和地球化学研究

山东胶莱盆地大西庄的王氏群玄武岩属于高钛碱性岩系列,全岩40Ar-39Ar年龄为73.2±0.3Ma,形成于晚白垩世岩石富N2O,Mg#值为63-66,(Ne-Hy-Q)值为6.03-10.05,轻稀土富集,(La/Yb)N比值为11.18-12.56,重稀土有一是程度的分异,富集大离子亲石元素,Tb显著正异常,Zr轻微正异常,具有与大陆板内碱性玄武岩类似的特征。εNd(T)值为7.08-7.55,87Sr/86Sr(T)比值为0.7035-0.7038,反映了玄武岩浆来源于亏损的地幔源区,在上升过程中几乎没有受到地壳物质的混染,原始玄武岩浆由软流圈和新生岩石圈地幔分别部分熔融产生的熔体相混合而形成,起源深度为50-70km。玄武岩含有幔源包体,岩石类型为尖晶石二辉橄榄岩。包体的温压估算结果为T=1010-1140℃,P=20kb。包体的矿物相与平衡温压估算值以及玄武岩浆起源深度估计值表明,胶州地区晚白垩世时岩石圈厚度大约为60-70km,岩石圈地幔具有新生的性质。因此,中国东部岩石圈减薄发生在125-73Ma之间。此后,中国东部进入了统一的以拉张为主的动力学背景之下。     

基于多核CPU的大规模DEM并行三维渲染

采用数据分块进行地形数据组织,基于缓存策略进行数据调度,对各地形块采用四叉树LoD(level of detail)的细节简化算法,利用多核CPU的计算特性实现四叉树LoD的并行生成,在动态构造地形三角网后,让不同的CPU核心负责不同地形区域以实现并行渲染,基于OpenMP及OpenThreads建立原型系统。实验结果表明,并行化渲染具有明显的性能优势。     

一种新的断裂计算方法

利用单元中嵌合无厚度不连续面的方法 ,模拟断裂面的形成过程。用虚功原理建立包含断裂面影响的有限元平衡方程 ;利用余虚功原理推导了断裂面的矩阵的具体形式 ; 以第一类断裂问题 -开裂问题为例 ,建立了开裂面粘塑性开裂本构关系,进一步得到了以弹粘塑性形式表示的有限元计算格式。 通过简单算例证明了该方法的正确性。     

天山西部树轮年表的响应函数

本使用响应函数分析技术，研究新疆伊犁地区树年表中的气候信息量，得出一些有益的结论，这对于认识该区气候对森林的影响，以及在温湿气候区树木年轮中提取气候信息会有所帮助。     

长江口环境条件对日本鳗鲡(Anguilla japonica)鳗苗溯河洄游的影响

长江口是日本鳗鲡鳗苗的手要产区,利用2007年1-5月在长江口的长兴岛、横沙和杭州湾小洋山4个取样点得到的日本鳗鲡鳗苗渔获量数据,初步研究了鳗苗的补充时间分布以及补充量与潮汐、月相等环境因素之间的关系.发现鳗苗在长江口的补.充时间从1月下旬开始到5月中旬结束,鳗苗日产量峰值出现日期从长江口外向内逐渐推迟,与其洄游路线致.长江口附近潮汐为半月潮,每月有两次涨落潮,鳗苗溯河量与潮汐周期呈现一定的节律性,每月有两次鳗苗峰值.河口区鳗苗溯河具有潮流选择性,长江口内鳗苗溯河量起汛潮多于落汛潮:长江口外鳗苗溯河量和潮汐振幅呈现正相关趋势.日本鳗鲡鳗苗的溯河量与月相变化也有一定的关系;朔月望月的平均单网捕捞量之和占总平均单网捕捞量的93.13%,而上下弦只占6.87%.经过方差检验,朔月鳗苗溯河量多于望月,且二者之间存在极显著差异(P<0.01).     

Origin of graphite in early precambrian banded iron formation in Anshan,China

Graphite which occurs in the early Precambrian banded iron formation (BIF) (3.1x10⁹yr) at Gongchangling, Anshan, China, can be divided into two genetic types on the basis of its modes of occurrence: biogenic and inorganic; the former occurs in garnet-mica-quartz schist and the latter in rich magnetite ore. The garnet-mica-quartz schist is located at the bottom of the formation. Its original rock is a volcanic tuff-bearing clayey siltstone. Graphite is fairly uniformly disseminated in the schist Chemical analysis of 20 samples of graphite yields an average content of 0.29±0.22%. The average δ¹³C value of 4 samples is -26.6 ±0.6‰ (PDB). Rich magnetite ore bodies occur in the form of lenses and layers within the banded magnetite quartzite, and wallrock alteration is also noticed. Graphitebearing rich magnetite ore is composed of magnetite, maghemite and minor graphite. Late chlorite and siderite are recognized locally. Disseminated graphite is generally distributed in scaly aggregates interstitial to the grains of magnetite, occasionally found within the grains of magnetite. It is non-uniformly distributed in the horizon of rich ore, mainly in the core. No graphite is found in the outer part of the rich ore, poor ore in the same horizon, wallrock near the rich ore and altered rock, indicating that graphite has a great bearing on the rich ore. Chemical analysis of 15 samples gives an average graphite content of 0.89±0.51%. The average δ¹³C value of 18 samples is-4.7 ±2.1%.(PDB). This kind of graphite seems to have been formed by the following reaction: 6 FeCO₃=2Fe₃O₄ + 5CO₂+C in the primary sedimentary siderite under the condition of amphibole-facies regional metamorphism.     

利用Harris-Laplace和SIFT描述子进行低空遥感影像匹配

提出了基于Harris-Laplace和SIFT描述子的改进的特征匹配方法。在特征点检测阶段,采用Har-ris-Laplace算法检测出影像上的关键点,该关键点对光照变化、图像噪声和尺度变化具有不变性;然后,确定关键点的主方向,生成特征点。在特征点描述阶段,采用SIFT描述子对特征点进行描述;在特征点匹配阶段则利用BBF算法和RANSAC算法对特征点进行粗匹配和精匹配。实验结果表明,相对于基于SIFT的匹配方法,此算法在匹配速度相同的情况下,提高了匹配精度。     

安徽月山岩体的40Ar/39Ar年龄及与其有关的成矿时代估计

安徽月山岩体是长江中下游钢铁成矿带中的一个重要含矿岩体.我们对该岩体的角闪石和黑云母进行了⁴⁰Ar/³⁹Ar年龄测定.角闪石的未扰动年龄谱给出岩体侵位年龄为136Ma.根据黑云母的扰动年龄谱,估计岩体从浸位到矿化（晚期热液作用）的时间间隔不少于9Ma.月山岩体的年龄测定结果以及前人对长江中下游其它含铜岩体的年龄测定结果表明,该区所有铜矿化岩体均形成于136Ma前,且产出于沿江构造单元内.此外,月山岩体的研究还表明,对中酸性岩的年龄测定,封闭温度高的角闪石是较理想的样品,在解释与矿化有关或热液作用发育的岩体的黑云母K-Ar结果时,必须持慎重态度.