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91.
Wu Baisheng 《Acta Mechanica Sinica》1997,13(2):165-170
A finite element asymptotic analysis for determining the lower bound dynamic buckling estimates of imperfection-sensitive
structures under step load of infinite duration is presented. The lower bound dynamic buckling loads and the corresponding
displacements are sought in the form of asymptotic expansions based on the static stability criterion and they can be determined
by solving numerically (FEM) several linear problems with a single nonsingular sub-stiffness matrix.
The project supported by the State Education Commission of China 相似文献
92.
凹角型区域椭圆边值问题的自然边界归化 总被引:3,自引:0,他引:3
In this paper, the natural boundary reduction for some elliptic boundary value problems with concave angle domains and their natural boundary methods are investigated. The natural integral equations and the Poisson integral formulae are given. The finite element methods of the natural integral equations are discussed in details. The convergences of the approximate solutions and their error estimates are obtained. Finally, some numerical examples are presented to show that our methods are effective. 相似文献
93.
94.
Techniques used to implement an unstructured grid solver on modern graphics hardware are described. The three‐dimensional Euler equations for inviscid, compressible flow are considered. Effective memory bandwidth is improved by reducing total global memory access and overlapping redundant computation, as well as using an appropriate numbering scheme and data layout. The applicability of per‐block shared memory is also considered. The performance of the solver is demonstrated on two benchmark cases: a NACA0012 wing and a missile. For a variety of mesh sizes, an average speed‐up factor of roughly 9.5 × is observed over the equivalent parallelized OpenMP code running on a quad‐core CPU, and roughly 33 × over the equivalent code running in serial. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
95.
96.
The paper presents a hybrid Cartesian grid and gridless approach to solve unsteady moving boundary flow problems. Unlike the Chimera clouds of points approach, the hybrid approach uses a Cartesian grid to cover most of the computational domain and a gridless method to calculate a relatively small region adjacent to the body surface, making use of the flexibility of the gridless method in handling surface grid with complicated geometry and the computational efficiency of the Cartesian grid. Four cases were conducted to examine the applicability, accuracy and robustness of the hybrid approach. Steady flows over a single NACA0012 airfoil and dual NACA0012 airfoils at different Mach numbers and angles of attack were simulated. Moreover, by implementing a dynamic hole cutting, node identification and information communication between the Cartesian grid and the gridless regions, unsteady flows over a pitching NACA0012 airfoil (small displacement) and two‐dimensional airfoil/store separation (large displacement) were performed. The computational results were found to agree well with earlier experimental data as well as computational results. Shock waves were accurately captured. The computational results show that the hybrid approach is of potential to solve the moving boundary flow problems. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
97.
Amarande Murisier Marie Andrie Szabolcs Fekete Matthew Lauber Valentina D'Atri Katharina Iwan Davy Guillarme 《Journal of separation science》2022,45(12):1997-2007
The present study describes the possibilities offered by an innovative bioinert size exclusion chromatography column for size variant characterization of complex monoclonal antibody products. This size exclusion chromatography column includes a novel column hardware surface. The column was prepared from metallic hardware components that were treated to have prototype hydrophilically modified hybrid organic–inorganic silica surfaces called hybrid surface technology. This provides a significant reduction in nondesired hydrophobic and electrostatic interactions that can occur between column and analyte when performing size exclusion chromatography analysis with volatile mobile phase. Compared to a reference stainless-steel column packed with the same batch of packing material, peak tailing, band broadening, and above all recovery of high molecular weight species were distinctly improved for all types of monoclonal antibody products. Based on our observations, we found that 50 mM ammonium acetate in water was a suitable mobile phase offering good compromise in terms of liquid chromatography performance and mass spectrometry sensitivity. In addition, method repeatability (intra- and interday relative standard deviations) on elution times and high molecular weight species peak areas were found to be excellent. By using this innovative size exclusion chromatography material, the low and high molecular weight species contained in various stressed and nonstressed monoclonal antibody products were successfully characterized with mass spectrometry detection. 相似文献
98.
设计了一种航天器中远距仅测角导航硬件在环测试的光学模拟器,可对仅测角导航视觉传感器的硬件、软件和算法的性能及可靠性进行验证。首先对该光学模拟器进行了系统描述,包括硬件组成和星图模拟软件设计。硬件选用的都是商用、现成的部组件,可大幅节约研发成本,缩短开发周期。其次,重点阐述屏幕亮度与恒星星等之间的关系,以及该光学模拟器的光学原理。最后对该光学模拟器的星图模拟进行实验测试,并介绍了一种基于Clohessy-Wiltshire (CW)方程的仅测角导航模型,用于硬件在环测试。验证了几何校正后的光学模拟器完全满足航天器中远距仅测角导航硬件在环测试要求,并得出相对于几何校正前,终端时刻的相对位置精度提高了25.5%,相对速度精度提高了31.3%。 相似文献
99.
100.
Many applications in applied mathematics and engineering involve numerical solutions of partial differential equations (PDEs). Various discretisation procedures such as the finite difference method result in a problem of solving large, sparse systems of linear equations. In this paper, a group iterative numerical scheme based on the rotated (skewed) five-point finite difference discretisation is proposed for the solution of a fourth order elliptic PDE which represents physical situations in fluid mechanics and elasticity. The rotated approximation formulas lead to schemes with lower computational complexities compared to the centred approximation formulas since the iterative procedure need only involve nodes on half of the total grid points in the solution domain. We describe the development of the parallel group iterative scheme on a cluster of distributed memory parallel computer using Message-Passing Interface (MPI) programming environment. A comparative study with another group iterative scheme derived from the centred difference formula is also presented. A detailed performance analysis of the parallel implementations of both group methods will be reported and discussed. 相似文献