多GPU的可压缩湍流并行计算

利用CUDA Fortran语言发展了一种基于GPU的计算流体力学可压缩湍流求解器。该求解器基于结构网格有限体积法,空间离散采用AUSMPW 格式,湍流模型为k-ω SST两方程模型,采用MPI实现并行计算。针对最新的GPU架构,讨论了通量计算的优化方法及GPU计算与PCIe数据传输、MPI通信重叠的多GPU并行算法。进行了超声速进气道及空天飞机等算例的数值模拟以验证GPU在大网格量情况下的加速性能。计算结果表明相对于Intel Xeon E5-2670 CPU单一核心的计算时间,单块NVIDIA GTX Titan Black GPU可获得107至125倍的加速比。利用四块GPU实现了复杂外形1.34亿网格的快速计算,并行效率为91.6%。     

Proportionate flow shop: New complexity results and models with due date assignment

It is known that the proportionate flow shop minimum makespan $Fm/prpt/C_{\max }$ problem is solved optimally by any permutation job sequence. We show that the $Fm/prpt/C_{\max }$ problem is at least ordinary NP‐hard when missing operations are allowed and present some solvable cases. We then consider the standard proportionate flow shop problem (with no missing operations) and show that the solution algorithms for a class of single‐machine due date assignment problems can be extended/generalized to the corresponding proportionate flow shop problems. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 98–106, 2015     

新型优化同心筒自力发射流场机理与降温效果

针对同心筒自力发射结构优化与热环境改善的问题,基于雷诺平均方程及轴对称N-S方程,依托弹性变形和网格再生成方法结合的动网格技术,对3种不同结构形式同心筒发射装置的二维轴对称流场进行了非定常数值计算,得到了不同结构条件下动态的流场机理及导弹热环境特性。计算结果显示:导流器方案能实现燃气流迅速顺利排导;筒底收缩段设计能有效遮挡反溅燃气流;筒口导流板结构较好抑制了内筒的"倒吸效应",确保导弹和内筒的热安全;揭示了优化同心筒的流场结构与降温机理,可为相关研究提供参考。     

舰载机多机一体化机务保障调度研究

针对舰载机多机一体化机务保障调度问题,以出树、入树的形式描述实际保障过程中并行工序的约束关系,以最大保障完工时间和资源负载均衡性为目标,构建了舰载机多机一体化机务保障非线性多目标混合流水车间调度模型,并设计了一种结合基于Insert的动态邻域爬山搜索策略和并行工序的同步化修正的Memetic算法求解该模型。最后通过实例仿真验证了模型和所提算法的可行性和有效性。     

不同形状喷嘴内流场模拟分析

建立了前混合磨料水射流喷嘴内固液两相流动的数学模型,运用Fluent软件对圆柱型、圆锥收敛型、流线型和圆锥带圆柱段收敛型喷嘴内流场进行了数值模拟,分析了喷嘴形状对喷嘴内流场和磨料颗粒加速性能的影响,并通过切割实验验证了仿真结果的可靠性。结果表明:圆柱型喷嘴能量损耗较大,圆锥收敛型喷嘴对磨料颗粒的加速性能差,流线型喷嘴性能良好但不易加工,只有圆锥带圆柱段收敛型喷嘴是用作前混合式磨料水射流喷嘴的最优选择。     

基于流程仿真的物资接收系统可靠性预计方法

针对船舶物资接收时间计算的问题,新增加了对设备发生故障的考虑,通过引入接收时间可靠性的概念,将其转换为船舶物资接收系统的可靠性预计问题。为了解决上述可靠性预计问题,提出了基于流程仿真的系统可靠性预计方法。分析了物资接收系统的工作流程,依据工作流程实现了仿真程序,用蒙特卡洛法对物资接收系统的可靠性进行了求解,并分析了设备不同的可靠性水平对物资接收系统可靠性的影响。仿真结果表明,增加了对设备故障的考虑后,对物资接收时间的估计更加接近实际;基于流程仿真的系统可靠性预计方法的模型更容易理解,所得结论更加具体。     

光流算法研究

光流的测量是视频序列处理和视频挖掘中的基本问题。首先简述了光流法的基本原理,即物体亮度不变特性;然后阐述了计算光流的4类算法:微分方法、区域匹配方法、基于能量的方法和基于相位的方法,并对当前主流的能量算法进行了详细探讨;最后对各种光流算法的评测方法与测试集进行了说明。     

An exact network flow formulation for cell‐based evacuation in urban areas

In the literature two common macroscopic evacuation planning approaches exist: The dynamic network flow approach and the Cell–Transmission–Based approach. Both approaches have advantages and disadvantages. Many efficient solution approaches for the dynamic network flow approach exist so that realistic problem instances can be considered. However, the consideration of (more) realistic aspects (eg, density dependent travel times) results in non‐linear model formulations. The Cell‐Transmission‐Based approach on the other hand considers realistic traffic phenomena like shock waves and traffic congestion, but this approach leads to long computational times for realistic problem instances. In this article, we combine the advantages of both approaches: We consider a Cell‐Transmission‐Based Evacuation Planning Model (CTEPM) and present a network flow formulation that is equivalent to the cell‐based model. Thus, the computational costs of the CTEPM are enormously reduced due to the reformulation and the detailed representation of the traffic flow dynamics is maintained. We investigate the impacts of various evacuation scenario parameters on the evacuation performance and on the computational times in a computational study including 90 realistic instances.     

潜艇应急上浮六自由度运动及黏性流场数值模拟

为揭示潜艇应急上浮过程中的强非线性运动及水动力作用规律,基于RANS方程及流体体积模型,针对Suboff标模建立了潜艇应急上浮数值预报方法。通过开展不同纵倾攻角及斜航漂角下全附体模型的水动力计算,验证了该计算方法的有效性,确定了其适用范围,进而结合整体动网格技术模拟了潜艇的应急上浮过程,获得了艇体六自由度运动的时历参数及流场细节信息。数值模拟结果表明该方法能够较合理地描述潜艇上浮的运动规律,也证明了该方法在潜艇上浮多自由度运动及水动力性能研究中的潜力和适用性。     

Numerical simulation of base flow with hot base bleed for two jet models

In order to improve the benefits of base bleed in base flow field, the base flow with hot base bleed for two jet models is studied. Two-dimensional axisymmetric Navier–Stokes equations are computed by using a finite volume scheme. The base flow of a cylinder afterbody with base bleed is simulated. The simulation results are validated with the experimental data, and the experimental results are well reproduced. On this basis, the base flow fields with base bleed for a circular jet model and an annulus jet model are investigated by selecting the injection temperature from 830 K to 2200 K. The results show that the base pressure of the annular jet model is higher than that of the circular jet model with the changes of the injection parameter and the injection temperature. For the circular jet model, the hot gases are concentrated in the vicinity of the base. For the annular jet model, the bleed gases flow into the shear layer directly so that the hot gases are concentrated in the shear layer. The latter temperature distribution is better for the increase of base pressure.