Development of a GPGPU-parallelized hybrid finite-discrete element method for modeling rock fracture

The hybrid finite-discrete element method (FDEM) is widely used for engineering applications, which, however, is computationally expensive and needs further development, especially when rock fracture process is modeled. This study aims to further develop a sequential hybrid FDEM code formerly proposed by the authors and parallelize it using compute unified device architecture (CUDA) C/C++ on the basis of a general-purpose graphics processing unit (GPGPU) for rock engineering applications. Because the contact detection algorithm in the sequential code is not suitable for GPGPU parallelization, a different contact detection algorithm is implemented in the GPGPU-parallelized hybrid FDEM. Moreover, a number of new features are implemented in the hybrid FDEM code, including the local damping technique for efficient geostatic stress analysis, contact damping, contact friction, and the absorbing boundary. Then, a number of simulations with both quasi-static and dynamic loading conditions are conducted using the GPGPU-parallelized hybrid FDEM, and the obtained results are compared both quantitatively and qualitatively with those from either theoretical analysis or the literature to calibrate the implementations. Finally, the speed-up performance of the hybrid FDEM is discussed in terms of its performance on various GPGPU accelerators and a comparison with the sequential code, which reveals that the GPGPU-parallelized hybrid FDEM can run more than 128 times faster than the sequential code if it is run on appropriate GPGPU accelerators, such as the Quadro GP100. It is concluded that the GPGPU-parallelized hybrid FDEM developed in this study is a valuable and powerful numerical tool for rock engineering applications.     

中国近五千年来地质灾害事件群发周期初步研究

中国近五千年来山崩滑坡地裂等地质灾害事件存在着多种时间尺度的群发期。最显著的群发期出现在中国黄帝、夏桀、殷代、周代、西汉、东汉、西晋、元代、明清、清末时期。近８００起灾害事件时间序列谱分析表明，多尺度群发周期序列为１３８０，６００，２８８，１６２，１１８，７２，６１，３１，２４，２０，１５，１１年，具有可公度性和对数螺线性，并且与冰川泥石流、火山爆发、陨石坠落等周期序列相近，与地球运动周期、气候旋回、地质旋回一致。     

Isolation, cloning and sequencing of AFLP markers related to disease-resistance traits in Fenneropenaeus chinensis

Amplified fragment length polymorphism (AFLP) technique was used to analyze the fingerprinting of four successive generations ofFenneropenaeus chinensis to reveal their disease-resistance traits. Some loci showed quite different genetic frequencies due to artificial selection, which implied that these fragments were putative markers related to the disease-resistance trait. We developed a simple and effective method to further characterize these AFLP fragments. Specific AFLP bands were cut directly from polyacrylamide gels, re-amplified, cloned and sequenced. Eight putative genetic markers were sequenced and their sizes ranged from 63 to 209 bp. The sequences were submitted to dbGSS (database of Genome Sequence Survey); and the BLAST analysis showed low similarity to the function genes, indicating these markers were tightly linked to a disease-resistance trait but were not functional genes. This research was supported by special funds from the National Key Basic Research Program (G1999012007) and the National High-Tech Research and Development Program of China (863 Program. 2001AA620105).     

辽西建平地区三座庙序列侵入岩年代

三座庙序列侵入岩U—Pb法一致曲线年龄值1708Ma、1717Ma;K—Ar法年龄值为1670Ma、1530Ma、1316Ma,表明该系列侵入岩为中元古宙长城纪大红峪期火山喷发岩的同期侵入体,属燕辽旋回兴城运动的产物。     

渐近非扩张映象多步迭代序列的收敛性

研究了凸度量空间中用多步迭代序列来逼近渐近非扩张映象的不动点,并给出了其收敛于不动点的充分必要条件.     

有机地球化学参数在层序划分对比中的应用——以冀中拗陷束鹿凹陷沙三下亚段为例

深水细粒沉积层系的层序地层单元细分和对比,是建立合理的层序地层格架的关键,也是进行深水区岩性油气藏勘探开发的一项重要基础研究工作。但往往由于细粒沉积层系层序地层单元划分标志不明显,其划分对比较为困难,这也是层序地层学研究的难点。依据高分辨率层序地层学原理,从沉积层序的成因及其表现入手,应用表征沉积环境或沉积物特征的有机地球化学参数在纵向上的周期性变化规律,对渤海湾盆地冀中坳陷束鹿凹陷沙三段下亚段半深湖—深湖相泥灰岩沉积进行了层序地层单元划分和对比,较好地识别出了4级旋回与5级旋回,为建立高分辨率层序地层格架奠定了基础。     

鄂尔多斯盆地东北缘晚古生代陆表海含煤岩系层序地层研究

通过区域不整合面、沉积体系转换面、构造应力场转换面和水上暴露面等层序界面的识别,对研究区进行层序地层划分,指出鄂尔多斯盆地东北缘晚古生代陆表海含煤岩系发育7个三级层序。在此基础上,认为陆表海层序仍然具有“三元”结构,由低位体系域、海侵体系域和高位体系域组成。在盆地北部发育的多期河道砂岩具有低位体系域的下切谷充填特点——面状充填,如晋祠砂岩、桥头砂岩以及北岔沟砂岩等。煤层在层序格架中的定位与海平面变化的转换时期有关,主要发育在陆表海环境的海侵体系域下部以及陆相环境的高位体系域上部。     

应用粒度成因单元划分高分辨率层序地层基准面旋回

摘要　在Goodwin和Anderson于1985提出的PAC假说基础上,针对目前基准面旋回级别划分较为混乱的状况,将基准面旋回赋予了自旋回和异旋回的涵义,探索性地提出了粒度成因单元的概念和研究方法,并将其应用到柴窝堡盆地中二叠统芦草沟组高分辨率层序地层的研究中,建立了该区中二叠统草沟组高分辨率层序地层格架,划分出了2个长期基准面旋回6个中期粒度成因单元以及5段。     

两次强震峰值速度比及其余震分布特征

基于甘肃地震台网和青海地震台网对岷县-漳县MS6.6地震和门源MS6.4地震的波形记录,采用FFT方法分别计算这两次地震三分向的峰值速度,讨论分量之间峰值速度比的分布特征,进而研究其震源性质。结果表明,岷县-漳县地震具有逆冲兼左旋位错性质,南北向能量明显大于东西向;门源地震以逆冲为主,略具左旋走滑特征,两个水平分量的能量相当。结合这两次地震的余震序列分布特征及其他学者的研究结果推测,岷县-漳县地震的发震断层应该是位于临潭-宕昌断裂西北侧且与其平行的一条次级断裂;门源地震的发震断层应该是冷龙岭断裂西北侧的次级断裂,但受到冷龙岭断裂活动控制。     

一种由粗到精的光学与SAR遥感图像配准算法

由于光学遥感图像和SAR图像具有明显的非线性强度差异,且SAR图像存在斑点噪声,使得其配准存在较大难度。为此,本文结合基于特征和基于区域图像配准方法的优点,并组合为混合模型,提出一种由粗到精的自动配准算法。以光学遥感图像和SAR图像分别为参考图像和待配准图像,先以基于特征点的SAR-SIFT完成粗配准,再以基于区域的ROEWA-HOG完成精配准。① 采用SAR-SIFT算法进行特征点检测和特征匹配来计算图像的仿射变换模型,以消除参考图像和待配准图像之间明显的旋转、尺度和平移差异,至此完成图像粗配准;② 在此基础上利用分块Harris角点检测在参考图像上获得特征点,并根据特征点确定待配准图像上的同名点搜索区域;③ 计算图像的ROEWA梯度,构造以特征点为中心的模板区域内的HOG特征向量,以SSD作为相似性测度搜索待配准图像上的同名点,完成高精度的图像配准;④ 进行图像配准实验,对配准结果进行目视检查和精度评估。经过多组光学与SAR图像配准实验,验证本文算法能够结合基于特征和基于区域的图像配准方法的优点,较好地抵抗光学与SAR图像之间的非线性强度、旋转、尺度、平移差异和SAR图像的噪声影响,并逐步提高配准精度,最终配准精度达到1个像素左右,实现了光学与SAR图像的高精度自动配准,能够满足光学与SAR图像后续综合应用。