准周期量子动力系统的数值求解

本文提出了研究准周期量子动力系统的计算方法.传统计算方法通常使用大的周期系统来近似计算准周期系统,这会产生丢番图逼近误差.我们的方法将准周期系统在高维周期结构中表示和计算,这样不仅可以避免丢番图逼近误差,而且可以将周期系统的高效算法,比如快速Fourier变换直接运用到新的算法中.我们将算法用于计算具有准周期势的线性薛定谔方程和准周期初值的非线性薛定谔方程.数值结果表明了算法的可靠性和高效性,并可以用于研究包含Anderson局域化、非线性光子准晶在内的准周期量子行为.     

基于投影能量函数和Pin-SVM的电力系统暂态稳定评估

提出一种基于Pin-SVM的电力系统暂态稳定评估方法。首先,采用系统指标(如平均机械功率、初始加速度和系统冲击等)和投影能量函数指标(如投影角速度、投影角加速度和投影动能PKE)构建暂态稳定指标的原始特征集,通过最大相关最小冗余特征选择方法对暂态指标集进行特征压缩,寻找对电网暂态变化敏感度高的特征子集;然后,基于Pin-SVM思想将特征子集映射到高维空间,实现非线性暂态稳定评估问题的线性转换,进而引入分位数改变系统稳定类与不稳定类之间的最近点位置,将暂态稳定分类问题转换为在Pin-SVM中寻找最优分位数距离问题,以减小边界干扰样本的影响,提高电力系统暂态评估方法的评估准确率和稳定性。最后,以IEEE-39节点系统、IEEE-145节点系统和某实际算例进行仿真计算,计算结果验证了该方法的有效性和准确性。     

Addendum to “On the consistency of MPS” [Comput. Phys. Comm. 184 (3) (2013) 732–745]

The analogies between the Moving Particle Semi-implicit method (MPS) and Incompressible Smoothed Particle Hydrodynamics method (ISPH) are established in this note, as an extension of the MPS consistency analysis conducted in Souto-Iglesias et al. (2013).     

电磁层析无损检测系统中碳纤维复合材料缺陷重建的仿真

在电磁层析成像系统中,对带缺陷的碳纤维复合材料进行了图像重建仿真。分别建立了单方向和编织型材料的Ansoft Maxwell三维模型来显示碳纤维复合材料的方向性,仿真结果和试验基本符合。对于单方向的碳纤维复合材料,采用了简单比较法和线性反投影算法来确定缺陷的位置。结果表明,使用更加精确的重建算法的电磁层析无损检测技术可以用来探测碳纤维复合材料中的缺陷．     

基于MAS的供应链可靠性综合评估模型

为了保证供应链的正常运作,构建了一种基于MAS的供应链可靠性综合评估模型。模型上最底层的节点Agent利用遗传投影寻踪法计算节点可靠度,中间层的子系统Agent利用特征值赋权法计算子系统可靠度,最上层的系统Agent负责供应链整体可靠性评估。应用实例表明,该模型可以从局部到整体对供应链可靠性进行全面评估。     

Enhanced‐image‐quality raster‐scanning chipset using feedback‐control actuation

Abstract— A new raster‐scanning chipset which provides enhanced projection performance is presented. The design is novel in that it combines electrostatic and electromagnetic actuation methods, along with a unique feedback‐control scheme to produce SVGA and WVGA projected images. A micromirror, the actuators, and drive electronics are integrated into a small, power‐efficient system, a scanning chipset, to increase its reliability and manufacturability.     

Enabling a commercial computational fluid dynamics code to perform certain nonlinear analysis tasks

In this work we enable the commercial computational fluid dynamics code Fluent, to successfully trace a complete solution branch, even past turning points. Here the so-called Recursive Projection Method (RPM) is implemented as a computational shell “wrapped” around Fluent, in conjunction with a pseudo-arc-length method for convergence on the unstable branch. The case study is a mixed convection flow in a stagnation point chemical vapor deposition (CVD) reactor. Multiple steady states coexist over a range of inlet Reynolds numbers, due to the competition of the two dominant physical mechanisms: forced and free convection. Continuation on the solution branch reveals a curve consisting of a stable branch, dominated by free convection, followed, past the first turning point, by an unstable branch. Past a second turning point, follows another stable branch dominated by forced convection. Taking the problem a step further, it is augmented with a chemical model describing the deposition of silicon (Si) from silane (SiH₄), silylene (SiH₂) and hydrogen (H₂). The solution branch does not alter since the gas mixture is dilute and the carrier gas, in this case nitrogen (N₂), and the precursor, in this case SiH₄, are of similar molar masses; the concentration differences cannot lead to solutal convection. Results for the mass fraction distribution inside the reactor and the film growth rates are reported in all parts of the solution branch.     

基于几何校正的聚束SAR快速分级后投影算法

快速分级后投影(Fast Factorized Back Projection, FFBP)算法大幅减少了原始后投影算法的插值次数,提升运算效率。然而图像合成过程中仍然需要大量的图像域2维插值操作,庞大的计算量限制了其在实际中的应用。该文提出一种基于几何校正的聚束SAR快速分级后投影算法。该算法利用几何校正的方法实现子图像配准,即在满足聚焦性能的前提下,通过距离维平移和角度维旋转完成子图像在不同坐标系下的投影和子图像合成。该算法避免了逐点插值运算,进一步降低了FFBP算法的计算量。仿真结果表明,该算法能高精度聚焦成像,并且其运算效率相对于基于图像域2维插值的FFBP算法显著提高。