Highly efficient iterative methods for solving linear equations of three-dimensional sphere discontinuous deformation analysis     

Gang-Hai Huang  Yuan-Zhen Xu  Xiong-Wei Yi  Ming Xia  Yu-Yong Jiao  Shu Zhang 《国际地质力学数值与分析法杂志》2020,44(9):1301-1314

The efficiency of solving equations plays an important role in implicit-scheme discontinuous deformation analysis (DDA). A systematic investigation of six iterative methods, namely, symmetric successive over relaxation (SSOR), Jacobi (J), conjugate gradient (CG), and three preconditioned CG methods (ie, J-PCG, block J-PCG [BJ-PCG], and SSOR-PCG), for solving equations in three-dimensional sphere DDA (SDDA) is conducted in this paper. Firstly, simultaneous equations of the SDDA and iterative formats of the six solvers are presented. Secondly, serial and OpenMP-based parallel computing numerical tests are done on a 16-core PC, the result of which shows that (a) for serial computing, the efficiency of the solvers is in this order: SSOR-PCG > BJ-PCG > J-PCG > SSOR>J > CG, while for parallel computing, BJ-PCG is the best solver; and (b) CG is not only the most sensitive to the ill-condition of the equations but also the most time consuming under both serial and parallel computing. Thirdly, to estimate the effects of equation solvers acting on SDDA computations, an application example with 10 000 spheres and 200 000 calculation steps is simulated on this 16-core PC using serial and parallel computing. The result shows that SSOR-PCG is about six times faster than CG for serial computing, while BJ-PCG is about four times faster than CG for parallel computing. On the other hand, the whole computation time using BJ-PCG for parallel computing is 3.37 hours (ie, 0.061 s per step), which is about 36 times faster than CG for serial computing. Finally, some suggestions are given based on this investigation result.  相似文献   

球体剖分瓦块的大区域真三维地理场景构建     

邹煚  王金鑫  李仕学  杨晶  赵光成 《测绘科学》2017,42(10)

针对目前地理信息科学领域存在的三维地理场景大都是局部的、基于投影的2.5维表面模型的问题,该文提出了利用球体大圆弧八叉树剖分(SGOG)瓦块建立大区域真三维地理场景的方法。将SGOG特定剖分层次的顶点与全球共享DEM数据进行匹配,构建大区域真三维地形框架;以地形起伏度为阈值,采用不同层次的瓦块进行自适应建模,大大减少了数据量;粘贴遥感纹理,建立虚拟地理场景。中国大陆地区的实验结果表明:所提方法不但顾及了地球曲率,克服了投影变形的缺陷,而且可以利用SGOG多尺度特性,灵活建立各种(混合)尺度的模型,并可实现地表上下空间的一体化建模。  相似文献   

Toroidal oscillations of a transradially isotropic elastic sphere     

Alka Gupta  Sarva Jit Singh 《Journal of Earth System Science》1990,99(3):383-391

In order to consider the effect of anisotropy on the periods of the oscillations of the Earth, the problem of toroidal oscillations of a transradially isotropic elastic sphere is considered. At each point, the medium is assumed to be transversely isotropic about the radius through the point. The roots of the frequency equation are obtained for different values of the anisotropy parameter α. It is found that, for large order oscillations, the percentage change in the frequency of the toroidal oscillations on account of the anisotropy is nearly equal to |α-1| × 100.  相似文献   

Added mass and damping of a sphere section in heave     

D.V. Evans  P. McIver 《Applied Ocean Research》1984,6(1):45-53

The Norwegian wave-power buoy¹ consists of a half-immersed floating sphere which is open to the sea at the bottom end. It is a two degree-of-freedom device involving the independent motion of the outer rigid sphere and the pressure across the internal free surface. A simpler model of the device is to represent the oscillatory flow through the bottom opening as another rigid body motion being that of the curved surface which would complete the sphere.The wave-induced forces on this surface and also the outer spherical surface due to independent oscillations of either are determined semi-analytically using a simple extension of the method of Havelock,² recently simplified and generalised by Hulme,³ for the complete half-immersed sphere. In particular the 2 × 2 added mass and damping matrices are determined as a function of frequency and relative size of bottom opening to sphere radius. These quantities are essential in any theoretical analysis of a multi-degree of freedom wave-energy device.  相似文献   

浑浊介质光学特性参数测量方法的研究   总被引：1，自引：0，他引：1  

韩永辉  贺忠海  王智丽  徐可欣  杜军兰 《海洋技术学报》2004,23(2):19-23

浑浊介质光学特性参数的精确测量对于介质中成分的确定具有重要意义。文章设计了单积分球系统测量浑浊介质的光学特性参数。系统中采用了自行设计的准直光路以使系统更好地符合逆倍增法(IAD)的模拟边界条件。采取双光路补偿及光源调制的方法以提高系统的测量精度及信噪比。测量得到了不同浓度浑浊介质在632.8nm及1064nm波长处的光学特性参数，并据之由漫射理论计算得到的光径向分布与漫反射系统实际测量结果符合很好。  相似文献   

Transient dynamic response of submerged sphere shell with an opening subjected to underwater explosion     

Wen-Hao Lai 《Ocean Engineering》2007,34(5-6):653-664

This investigation applies the time domain FEM/DAA coupling procedure to predict the transient dynamic response of submerged sphere shell with an opening subjected to underwater explosions. The elastic–plastic material behavior of the transient fluid–structure interaction relate to structural response equation also presented herein. This analysis also examines the transient responses of structures to different charge distances. The effects of standoff distance on pressure time history of the shell to underwater explosion (3001b TNT) are presented. Additionally, the transient dynamic responses to underwater explosion shockwaves in the sea and the air are compared.  相似文献   

基于SVDD的变形监测数据可靠性分析研究     

彭磊  贾莹媛  杨富春  杨志文 《北京测绘》2012,(1):12-14,4

提出了一种基于支持向量数据描述的异常值检测方法,该方法在检测异常值方面具有快速形象、通用性强、可有效处理小样本数据等优点。实验结果证明当在训练样本中加入异常值时,训练得到的模型具有很高的正常数据识别率和异常数据识别率,因此,该方法用于异常值的检测是完全可行的。  相似文献   

CE318型太阳光度计标定方法初探   总被引：12，自引：1，他引：11       下载免费PDF全文

杨志峰  张小曳  车慧正  张晓春  胡秀清  张立军 《应用气象学报》2008,19(3):297-306

初步探索了CE318型太阳光度计的室内和野外标定方法, 并对两种方法的标定结果进行对比。基于积分球辐射源的辐亮度标定方法, 对CE318型太阳光度计不同波段天空散射辐射通道进行标定实验; 分别采用Langley标定法和标准仪器相对标定方法, 对CE318型太阳光度计的不同波段太阳直接辐射通道进行了标定实验。实验结果显示:天空散射辐射通道的标定结果在670 nm, 870 nm和1020 nm波段与仪器出厂时给定的标定结果偏差不超过6%, 而440 nm波段处得到的标定结果要高于出厂时给定的结果, 偏离幅度约18.9%。太阳直接辐射各通道的标定结果普遍大于出厂时给定的结果, 说明滤光片老化较为严重, 需要进行更换, 以保证观测精度。由于标准仪器相对标定方法对太阳直接辐射通道的标定结果明显优于Langley法, 因此利用标准仪器相对标定方法对中国气象局太阳光度计站网仪器进行定期标定更能够保证仪器观测数据的准确性。  相似文献   

Non-symmetrical sparking may hint “zits” on a pulsar surface     

Zhengli Wang  Jiguang Lu  Jingchen Jiang  Shunshun Cao  Weiyang Wang  Enwei Liang  Renxin Xu 《Astronomische Nachrichten》2024,345(2-3):e240010

Pulsar electrodynamics could be relevant to the physics of stellar surface, which remains poorly understood for more than half a centenary and is difficult to probe due to the absence of direct and clear observational evidence. Nevertheless, highly sensitive telescopes (e.g., China's Five-hundred-meter Aperture Spherical radio Telescope, FAST) may play an essential role to solve the problem since the predicted surface condition would have quite different characteristics in some models of pulsar structure, especially after the establishment of the standard model of particle physics. For instance, small hills (or “zits”) may exist on solid strangeon star surface with rigidity, preferential discharge, that is, gap sparking, may occur around the hills in the polar cap region. In this work, with the 110-min polarization observation of PSR B0950 $$08 targeted by FAST, we report that the gap sparking is significantly non-symmetrical to the meridian plane on which the rotational and magnetic axes lie. It is then speculated that this asymmetry could be the result of preferential sparking around zits which might rise randomly on pulsar surface. Some polarization features of both single pulses and the mean pulse, as well as the cross-correlation function of different emission regions, have also been presented.  相似文献   

近地质时期岩石圈板块构造运动的力学分析     

程学友 《地质与勘探》1995,31(5):15-22

运用相对运动的地球动力学理论，把软流圈以上的岩石圈和软流圈以下的地球内圈，作为两个独立的运动单元来考察它们随地球自转时所发生的变化和各自的运动状态。完整的岩石圈碎裂成岩石块之后，它们各自作为独立的单元，在纬向西漂力、经向离极力和洋底扩张力联合作用下，产生相对运动。  相似文献