用代数应力模型模化型腔充填过程中的紊流流动

针对型腔充填过程中的紊流流动，用代数应力模型研究紊流流动现象．成功地将代数应力模型引入ＰＨＯＥＮＩＣＳ软件中，完成了恒温流体充填过程三维时均速度和自由表面的计算模拟．与实验结果相比说明，本文基于ＰＨＯＥＮＩＣＳ软件开发的充填模拟具备了对复杂型腔充填过程的数值计算．     

A non-singular continuum theory of dislocations

We develop a non-singular, self-consistent framework for computing the stress field and the total elastic energy of a general dislocation microstructure. The expressions are self-consistent in that the driving force defined as the negative derivative of the total energy with respect to the dislocation position, is equal to the force produced by stress, through the Peach-Koehler formula. The singularity intrinsic to the classical continuum theory is removed here by spreading the Burgers vector isotropically about every point on the dislocation line using a spreading function characterized by a single parameter a, the spreading radius. A particular form of the spreading function chosen here leads to simple analytic formulations for stress produced by straight dislocation segments, segment self and interaction energies, and forces on the segments. For any value a>0, the total energy and the stress remain finite everywhere, including on the dislocation lines themselves. Furthermore, the well-known singular expressions are recovered for a=0. The value of the spreading radius a can be selected for numerical convenience, to reduce the stiffness of the dislocation equations of motion. Alternatively, a can be chosen to match the atomistic and continuum energies of dislocation configurations.     

Phragmen-Lindelöf alternative results for the initial boundary problem of stokes equation

In this paper we prove Phragmén-Lindelöf type alternative for the initial boundary problem of Stokes equation, i. e. we show that the energy expression for the solution of the initial boundary problem must either grow exponentially or decay exponentially with axial distance from the end of a semi-infinite strip. For the case of decay, we also establish the pointwise estimate for the maximum module of the Stokes flow and present a method for obtaining explicit bounds for the total energy.Project supported by the National Natural Science Foundation of China and Zhongshan University Science Foundation     

ON THE MECHANISM OF TURBULENT COHERENT STRUCTURE(II)──A PHYSICAL MODEL OF COHERENT STRUCTURE FOR THE ROUGH BOUNDARY LAYER

In this paper, the differences of turbulent coherent structure between the smooth and rough boundary layers are analysed. Based on the discussing the transient properties from the smooth wall to the rough wall, the physical model of coherent structure for the rough boundary layer are established. The width of slowly-moving turbulent spot and the bursting time are obtained, which are in agreement with experimental results.The project supported by the National Nature Science Foundation of China     

基于石墨烯的光纤湿度传感研究

将还原氧化石墨烯(r GO)沉积在侧边抛磨光纤(SPF)上制作了一种新型的光纤湿度传感器。在高湿度区域[相对温度(RH)为70%~95%],传感器的光功率变化达到6.9 d B,尤其在RH为75%~95%区域,传感器对湿度变化能实现相关系数为98.2%的线性响应,灵敏度可达0.31 d B/(%RH),响应速度快于0.13(%RH)/s,并且具有很好的可重复性。对传感机理的理论分析可以解释实验结果,并且表明这种基于石墨烯的光纤传感器亦可广泛应用于其他种类化学气体的探测。这种全新机理的光学传感器是对石墨烯电化学传感器的一种很好的补充,并将促进石墨烯在化学传感技术中的应用。     

装备现场级综合诊断系统设计

为了更好地应对基层保障人员在高技术武器装备现场保障过程中保障效能不足的问题,基于网络为中心的架构和标准化的信息描述,提出了一种装备现场级综合诊断系统的技术方案;利用便携式自动测试设备和远程技术支持系统集成各级保障机构的测试诊断资源和装备全寿命周期的保障信息资源,并通过网络将相关的诊断资源提供给现场的保障人员,为现场的装备故障诊断提供直接的、实时的、工程化的支持,能有效提高部队对复杂武器系统的现场抢修效能。     

风云三号C星全球导航卫星掩星探测仪首次实现北斗掩星探测

全球导航卫星掩星探测仪(GNOS)是国际首台北斗系统(BDS)和全球定位系统(GPS)双系统兼容掩星探测仪, 2013年9月23日随风云三号卫星C星(FY3 C)发射入轨, 目前已测得大量掩星数据. 介绍了FY3 C-GNOS的组成; 统计了2013年10月12日全天的FY3 C-GNOS掩星事件及其全球分布情况; 通过与GPS精密定轨结果进行对比分析, 测试了BDS在轨实时定位精度, 检验了BDS掩星产品的可靠性和一致性. 初步分析结果表明: 14颗BDS卫星在轨运营的条件下, BDS和GPS兼容掩星探测仪可将掩星事件数提高约33.3%; BDS实时定位平均偏差优于6 m, 标准偏差优于7 m; 5-25 km高度范围内, BDS与GPS内符合精度大气折射率优于2%, 温度优于2 K, 湿度优于1.5 g/kg, 压强优于2%, 电离层峰值密度优于15.6%. GNOS的在轨正常运行及BDS与GPS掩星定位精度及反演产品的一致性为北斗掩星探测的业务化运行奠定了基础.     

Xe54+离子与Xe原子碰撞过程中的辐射电子俘获及退激发辐射的理论研究

基于多组态Dirac-Fock理论方法和冲量近似, 对Xe⁵⁴⁺与Xe在197 MeV/u碰撞能量下, 炮弹离子的俘获及退激发过程进行了理论研究. 计算了炮弹离子从中性靶原子俘获一个电子到nl (n=1, 2, 3, 4, 5; l=s, p, d) 轨道上的辐射电子俘获截面和相应的辐射光子能量, 以及俘获末态退激发辐射跃迁的能量和概率. 结合这些计算结果, 进一步模拟了碰撞产生的炮弹离子的退激发X射线谱的结构, 并与兰州重离子加速器装置上的最新实验观测结果进行了比较, 符合得很好.     

基于ZigBee的煤矿井下预警防爆监测系统设计

针对矿山井下的特殊环境,提出了一种基于ZigBee技术的煤矿井下预警防爆监测系统,实现煤矿井下环境信息和人员位置的实时监测,以减少事故发生率;井下系统采用CC2530+CC2401芯片作为ZigBee节点的核心,井下主控制器通过CAN总线实现与井上上位机的通信;上位机使用Labview软件实现程序编程,实时显示煤矿井下采集到的CH₄、CO、O₂浓度、温湿度和人员坐标等参数并进行Web发布;该系统结合了基于模糊逻辑算法的预警技术、基于物理隔离的防爆技术,同时提出了一种融合LQI的RSSI加权质心算法;实验证明该系统运行稳定可靠,提高了人员定位的精度,具有良好的应用前景。