Prediction tests by using “ISF” method for the geomagnetic disturbances

A so-called “ISF” prediction method for geomagnetic disturbances caused by solar wind storms blowing to the Earth is suggested. The method is based on a combined approach of solar activity, interplanetary scintillation (I) and geomagnetic disturbance observations during the period 1966–1982 together with the dynamics of solar wind storm propagation (S) and fuzzy mathematics (F). It has been used for prediction tests for 37 geomagnetic disturbance events during the descending solar activity phase 1984–1985, and was presented in 33rd COSPAR conference. Here, it has been improved by consideration of the three dimensional propagation characteristics of each event, the search for the best radio source and the influence of the southward components of interplanetary magnetic fields on the geomagnetic disturbances. It is used for prediction tests for 24 larger geomagnetic disturbance events that produced space anomalies during the period 1980–1999. The main results are: (1) for the onset time of the geomagnetic disturbance, the relative error between the observation, T_obs, and the prediction, T_pred, ΔT_pred/T_obs  10% for 45.8% of all events, 30% for 78.3% and >30% for only 21.7%; (2) for the magnetic disturbance magnitude, the relative error between the observation, ∑K_p,obs, and the prediction, ∑K_p,pred, Δ∑K_p,pred/∑K_p,obs  10% for 41.6% of all events, 30% for 79% and 45% for 100%. This shows that the prediction method described here has encouraging prospects for improving predictions of large geomagnetic disturbances in space weather events.     

高强度钢在马氏体点以下的贝氏体转变

许多高强度结构钢中都发现有马氏体开始转变点以下的贝氏体转变现象。综合使用膨胀法、导磁率法和金相硬度法测定了12CrNi3A,12Cr2Ni4A,30CrMnSiA和32Cr2MolVA等4种高强度钢在300℃左右等温时,在已转变的绝热马氏体存在的条件下发生的等温贝氏体转变。而且,已存在的马氏体量愈多,则随后发生的贝氏体转变时问愈短;证实马氏体有诱发贝氏体转变的效果。膨胀法与导磁率法对研究钢在马氏体开始转变点以下的贝氏体等温转变是十分有效的工具。     

有轴向通流的双旋转轴间流动换热的数值模拟

采用混合长度模型,用共轭数值计算的方法研究了具有轴向通流且内轴加热情况下的双旋转轴间的换热,得到了内轴、双轴间隙内的温度场,内轴外壁面的温度分布情况,内轴外壁面对流换热系数的分布情况,并与实验结果进行了比较,结果表明:经过修正的混合长度模型对具有轴向通流的双旋转轴间换热情况的计算是可行的.      

航天测控通信IP网中可控组播的实现

航天测控通信IP网中部分业务以组播方式传输,由于IP组播标准协议缺乏控制和管理方面的机制,带来了用户和业务管理等方面的问题。根据航天测控通信IP网络环境选择相应的组播协议,并对组播源、组播接收者、任意源组播RP、组播流四个方面配置相应的策略,实现了组播业务的可控传输。     

X射线天文卫星观测需求分析与控制总体设计

对X射线天文卫星观测需求进行了分析,提炼了观测任务对观测模式、源的高精度定位与对准、轨道、热控、测控数传等多项需求与约束;针对X射线观测的多需求、多约束难点,设计了集巡天观测、定点观测与小天区扫描观测于一体的观测模式,解决了一颗卫星同时实现全天扫描、银道面深度扫描、重要惯性区域扫描、重要及机遇目标深度观测以及伽马暴全天监测的多种观测需求的难题,该技术已在我国硬X射线调制望远镜卫星上得到应用.     

某型涡桨发动机吹风流场计算与试验对比

为评估安装于某型飞机的某涡桨发动机吹风流场,针对其装机状态,采用UG软件建立实体模型及流域计算模型,采用ICEM软件对流域进行网格划分,采用Fluent软件进行吹风流场稳态数值模拟,湍流模型选择S-A模型,转动域及静止域采用动参考系模型进行参数传递。为验证计算模型及计算方法的准确性,对发动机吹风流场的关键点风速进行了试验测量,结果表明:无量纲速度差基本在0.15内,单发在4.32 m高处无量纲速度差0.17,双发在6 m高处无量纲速度差0.3,吻合程度较好。验证了计算模型、计算方法的可行性,可进一步推广应用。     

箭载SINS快速自对准技术

为适应运载火箭快速发射需求,捷联惯导系统采用自对准技术逐渐取代了复杂的光学瞄准系统。针对初始对准中Kalman滤波器收敛缓慢的问题,提出了基于低通滤波的运载火箭快速自对准方法。该方法基于凝固惯性系自对准算法,采用移动窗双矢量构造方案,实现了自对准实时解算。通过在凝固惯性系间姿态转换矩阵后端引入低通滤波器,降低杆臂效应引起的有害加速度影响,保证自对准精度。该方法不需要进行复杂的Kalman滤波运算,能够快速收敛,工程实现简单。数字仿真和试验数据表明,采用基于低通滤波的凝固惯性系自对准方法可以达到Kalman滤波对准同等级精度的同时缩短对准时间到5min以内,验证了该方法的有效性。     

Rotor Airload and Acoustics Prediction Based on CFD/CSD Coupling Method

An advanced airload and noise prediction method based on computational fluid dynamics/computational structural dynamics(CFD/CSD)coupling for helicopter rotor has been developed in this paper.In the present method,Navier-Stokes equation is applied as the governing equation,and a moving overset grid system is generated in order to account for the blade motions in rotation,flapping and pitching.The blade structural analysis is based on 14-DOF Euler beam model,and the finite element discretization is conducted on Hamilton′s variational principle and moderate deflection theory.Aerodynamic noise is calculated by Farassat 1 Aformula derived from FW-H equation.Using the developed method,numerical example of UH-60 Ais performed for aeroelastic loads calculation in a low-speed forward flight,and the calculated results are compared with both those from isolated CFD method and available experimental data.Then,rotor noise is emphatically calculated by CFD/CSD coupling method and compared with the isolated CFD method.The results show that the aerodynamic loads calculated from CFD/CSD method are more satisfactory than those from isolated CFD method,and the exclusion of blade structural deformation in rotor noise calculation may cause inaccurate results in low-speed forward flight state.     

对高层体系结构(HLA)的剖析

高层体系结构(HLA)着眼于仿真应用之间互操作和仿真应用的重用，从而大大改善综合仿真环境的有效性和经济性，并且促进分布交互式仿真(DIS)的发展。但是，HLA并非尽善尽美，有待日臻完善。     

随时间变化的应变疲劳可靠性模型

鉴于应变载荷和应变强度的随机波动性和可靠性的时间变化性，建立了随时间变化的动态应变疲劳干涉模型，算例演示了2种情况下（Manson－Coffin公式和3参数暴函数公式广P－ε－N曲线）动态应变可靠度的计算方法。