NUMERICAL AND EXPERIMENTAL STUDY OF LURE MOVING IN WATER

The motion of a lure in water is investigated experimentally and numerically. The lure motion in water of a passing water tank is observed, and the periodic motion is/ound. From the Fourier analysis, it is found that the frequency with the largest amplitude in the lateral direction depends on the lip width of the lure. To understand the lure dynamics, a numerical simulation of the flow field around the lure is performed. The shape is measured using an X-ray computer tomography and converted into a voxel model. From visualization, it is found that vortex sheds from its lip correspond to the vibration frequency of the lure.     

浅析“SOP”在空管系统的应用

本文分析了SOP在企业中的功能、创建与实施的关键以及对SOP理解的五大误区。同时,结合空管行业特点,剖析了SOP在空管行业的运行现状,总结规律,并就如何做好空管系统SOP的运行管理提出了建议,对如何在空管系统运用SOP是非常重要的。     

北斗系统时BDT解析

通过解析术语-北斗系统时BDT,讨论与北斗授时应用相关的时间尺度、系统时间、定时误差等问题,有利于北斗PNT组合应用与标准化。     

Simulation of Wave Impact on Three-Dimensional Horizontal Plate Based on SPH Method

An improved three-dimensional incompressible smooth particle hydrodynamics （ISPH） model is developed to simulate the impact of regular wave on a horizontal plate. The improvement is the employment of a corrective function to enhance angular momentum conservation in a particle-based calculation. And a new estimation method is proposed to predict the pressure on the horizontal plate. Then, the model simulates the variation characteristics of impact pressures generated by regular wave slamming. The main features of velocity field and pressure field near the plate are presented. The present numerical model can be used to study wave impact load on the horizontal plate.     

Performance of Cross-Layer Design with Power Allocation in Space-Time Coded MIMO Systems

A cross-layer design（CLD）scheme with combination of power allocation,adaptive modulation（AM）and automatic repeat request（ARQ）is presented for space-time coded MIMO system under imperfect feedback,and the corresponding system performance is investigated in a Rayleigh fading channel.Based on imperfect feedback information,a suboptimal power allocation（PA）scheme is derived to maximize the average spectral efficiency（SE）of the system.The scheme is based on a so-called compressed SNR criterion,and has a closed-form expression for positive power allocation,thus being computationally efficient.Moreover,it can improve SE of the presented CLD.Besides,due to better approximation,it obtains the performance close to the existing optimal approach which requires numerical search.Simulation results show that the proposed CLD with PA can achieve higher SE than the conventional CLD with equal power allocation scheme,and has almost the same performance as CLD with optimal PA.However,it has lower calculation complexity.     

Parallel-Computing Wavelet-Based FDTD Method for Modeling Nanoscale Optical Resonator

An efficient wavelet-based finite-difference time-domain （FDTD） method is implemented for analyzing nanoscale optical devices, especially optical resonator. Because of its highly linear numerical dispersion properties the high-spatial-order FDTD achieves significant reduction in the number of cells, i.e. used memory, while analy- zing a high-index dielectric ring resonator working as an add/drop multiplexer. The main novelty is that the wave- let-based FDTD model is extended in a parallel computation environment to solve physical problems with large di- mensions. To demonstrate the efficiency of the parallelized FDTD model, a mirrored cavity is analyzed. The analysis shows that the proposed model reduces computation time and memory cost, and the parallel computation result matches the theoretical model.     

超声速进气道快速CFD数值模拟计算方案(英文)

根据进气道内部流动特征,并结合现有工程设计经验和试验结论,提出从进气道喉道段出口截面截断,简化取其超声速扩压段和喉道段与其外部流场统一构造出具有单一性态超声速流动的流场计算域,既缩减了CFD数值模拟的计算规模,又提高数值计算的收敛性。经实例计算分析表明,解算速度和效率大大提高,单个计算工况仅需时不到20 m in即可快速完成求解,并可基于数值计算模型提取出进气道捕获流量和最大总压恢复系数等全部主要性能参数,特别适合于在超声速进气道方案设计阶段用来快速进行性能评估和方案选型,有利于提高设计效率,缩短研制开发周期。     

撞击流混合器速度信号的Hilbert-Huang变换分析

应用激光多普勒测速系统,对撞击流混合器的流场瞬时速度进行了测量。将Hilbert-Huang变换（HHT）应用于瞬时速度信号的分析,提取出各阶内禀模态函数（IMF）并通过经验模态分解（EMD）对速度信号进行滤波降噪。通过希尔伯特谱分析（HSA）确定了撞击流混合器速度信号的能量分布状况,信号能量集中于低频区,即存在于尺度较大的流体涡旋中。分析速度信号各阶内禀模态函数在不同频段的能量分布与转换,发现不同频段IMF的能量分布与流型转变之间的对应关系。通过能量特征值的提取表明,提高螺旋桨转速有助于强化系统的混合效果。最后将撞击流混合器的流场由内而外划分为中心区、涡旋区和回流区3个部分。     

1090ES广播式自动相关监视系统的CPR算法

在1090ES广播式自动相关监视（ADS—B）系统中,为了对飞机的位置消息进行有效编码,经度和纬度采用简洁位置报告（CPR）的形式。介绍了CPR编解码算法的基本原理,详细描述了1090ESADS—B系统中经度和纬度消息的CPR编解码方法,给出了全球位置和本地位置的编解码算法和实现步骤。     

脉冲爆震发动机喷嘴性能优化研究

脉冲爆震发动机两相爆震近来得到了广泛的重视和关注,但在它走向应用之前仍有很多问题需要解决,燃油的喷射、雾化和混合就是其中之一。本文针对一种改进的预膜式空气雾化喷嘴,利用CFD程序,通过改变侧路空气射入角、空气通道直径、混合室出口孔径等参数,研究了喷嘴结构参数对雾化特性的影响,得到了汽油的雾化粒度与喷嘴结构间的关系和变化规律。并将数值模拟结果与实验结果进行对比,两者吻合较好,为喷嘴的优化设计提供了依据。