Control of three-dimensional wakes using evolution strategies

We investigate three-dimensional cylinder wakes of incompressible fully developed flows at $\mathit{Re}=300$, resulting from control induced by tangential motions of the cylinder surface. The motion of the cylinder surface, in two dimensions, is optimized using evolution strategies, resulting in significant drag reduction and drastic modification of the wake as compared to the uncontrolled flow. The quasi-optimal velocity profile obtained in 2D is modified by spanwise harmonics and applied to 3D flows. The results indicate important differences in the flow physics induced by two and three dimensional control strategies. To cite this article: P. Poncet et al., C. R. Mecanique 333 (2005).     

一种基于SMR主动隔振模型的功率流控制方法

用功率流指标描述主动隔振系统中能量的传输，以传输到接受性的功率流最小为最优化控制目标，推导主动隔振系统中功率流传递的最优控制表达式，提出一种基于SMR主动隔震模型的主动功率流的最优化控制策略，对比分析了被动和主动模型下总功率流的传递特性以及主动控制时传递到基础的各功率流分量的分布特征。针对工程实际中的柔性安装问题，对四边筒支矩形薄板扩动隔振进行了研究。     

高压隔离开关智能组件硬件系统的抗电磁干扰策略

高压隔离开关智能组件是变电站智能一次设备的关键部件,但嵌入在一次设备中运行的智能组件电磁环境恶劣,可能导致隔离开关智能组件的误操作.为了提高智能组件的抗干扰能力,本文提出了改进硬件平台系统抗电磁干扰的设计理念.对智能组件系统所处的电磁干扰环境,电磁干扰源、抗电磁干扰机理做了详细分析,研究了设计电磁兼容性问题,总结出了智能组件系统硬件设计中应采取的抑制电磁干扰措施.通过对设计的硬件系统进行现场测试,试验效果验证了硬件系统抗干扰策略的可行性和有效性.     

有源电力滤波器的定频滞环空间矢量控制策略研究

本文通过基于空间电压矢量（SVPWM）滞环电流控制策略,搭建了以DSP2407控制芯片为控制核心、定频滞环SVPWM为控制策略的有源电力滤波器控制系统,针对两种负载做了无功补偿实验,同时分析了在该控制策略下有源电力滤波器的补偿效果。实验结果验证了定频滞环SVPWM控制策略理论的正确性及可行性。     

Conceptional design of a heavy ion linac injector for HIRFL-CSRm

A room temperature heavy ion linac has been proposed as a new injector of the main Cooler Storage Ring(CSRm) at the Heavy Ion Research Facility in Lanzhou(HIRFL), which is expected to improve the performance of HIRFL. The linac injector can supply heavy ions with a maximum mass to charge ratio of 7 and an injection kinetic energy of 7.272 MeV/u for CSRm; the pulsed beam intensity is 3 emA with the duty factor of 3%. Compared with the present cyclotron injector, the Sector Focusing Cyclotron(SFC), the beam current from linac can be improved by 10–100 times. As the pre-accelerator of the linac, the 108.48 MHz 4-rod Radio Frequency Quadrupole(RFQ) accelerates the ion beam from 4 keV/u to 300 keV/u, which achieves the transmission efficiency of 95.3% with a 3.07 m long vane.The phase advance has been taken into account in the analysis of the error tolerance, and parametric resonances have been carefully avoided by adjusting the structure parameters. Kombinierte Null Grad Struktur Interdigital H-mode Drift Tube Linacs(KONUS IH-DTLs), which follow the RFQ, accelerate ions up to the energy of 7.272 MeV/u for CSRm. The resonance frequency is 108.48 MHz for the first two cavities and 216.96 MHz for the last 5 Drift Tube Linacs(DTLs). The maximum accelerating gradient can reach 4.95 MV/m in a DTL section with the length of17.066 m, and the total pulsed RF power is 2.8 MW. A new strategy, for the determination of resonance frequency,RFQ vane voltage and DTL effective accelerating voltage, is described in detail. The beam dynamics design of the linac will be presented in this paper.     

First-order kernel density estimation of abdomen medical image intensity and spatial information and application to segmentation

Kernel density estimators (KDE) used for many medical image applications only consider the intensity information of each pixel or its neighbors without the ability of expressing the structure and shape of tissues and organs, and they suffer from boundary bias problem. In this paper, we propose a new first-order kernel density estimation (FOKDE) method for 1D intensity information and 2D spatial information of medical image in two steps. First, the FOKDE of intensity information is estimated and applied to medical image segmentation with the multi-thresholding algorithm. Second, we estimate the FOKDE of spatial information on the initial segmentation, which can express the structure and shape of organs and tissues. In order to evaluate the FOKDE and KDE of the 2D spatial information, we apply them to medical image segmentation with the hill-climbing strategy. Density estimation experiments and segmentation application results on the simulated dataset and real abdomen CT images show us that the FOKDE has smaller boundary bias than the KDE, and that it can estimate the structure and shape of tissues and organs with spatial information effectively.     

基于粒子群优化算法的伺服系统测试点优选策略研究

针对某型雷达天线伺服系统测试点多,故障诊断需测试较多测试点而导致的故障诊断时间长,效率低的问题,提出了一种基于粒子群优化的测试点优选方法。该方法首先基于系统所需的故障诊断率和所能容忍的故障虚警率构建目标优化函数,其次利用粒子群算法对目标函数进行优化以选择最少的测试点完成故障定位和诊断。该方法避免了对所有测试点的测试,节省了测试时间,可在最短的时间内完成测试点的优选。仿真实验验证了算法的有效性。     

量子移动通信中纠缠信令越区切换策略及仿真

量子移动通信是量子力学与移动通信相结合的崭新的通信技术,具有灵活、高效、安全、保密的优势.本文提出了基于纠缠度计算的同小区内不同扇区天线之间纠缠信令的越区切换策略.研究了量子移动通信终端与天线纠缠度随距离及角度变化关系.在此基础上,对信令的越区切换进行了建模仿真.结果表明,本文所提出的纠缠信令切换策略可靠性高,对于对构建未来量子移动通信系统及其信令标准的制定具有重要的技术支撑作用.     

基于多指标博弈的核电施工企业安全投入研究

核电的发展离不开安全的保障,核电建设的快速发展使得核电建筑施工企业在市场竞争和项目施工两个方面面临安全投入策略的选择问题,基于此,根据多指标博弈理论构建了两个博弈模型,分别讨论了竞争条件下和施工监管条件下企业安全投入的策略选择,研究结果表明合理的安全投入将会使企业在竞争中占据优势地位,同时在施工阶段企业需要根据监管方的策略变化选择与之适合的安全投入策略,从而实现自身效用最大化的目的。