最优双冲量交会问题的数学建模与数值求解

基于普适变量法研究了两个共面轨道的最优双冲量交会问题。具体地,基于求解Lambert问题的普适变量法,在将给定时间段划分初始飘移阶段、轨 道转移阶段与终端停泊阶段的前提下,对两圆轨道及两拱线相同的椭圆轨道的最优双冲量交 会问题分别进行了优化数学建模,并利用数学软件Lingo进行了数值求解。数值结果表明,划分给定时间段可以得到更优解。
     

由地面宇宙线中子强度反演空间质子和重离子的分布

采用线性回归的方法研究了太阳活动平静时期空间高能质子和重离子微分通量与地面OULU宇宙线台站中子强度之间的相关性,利用地面中子强度数据来反演空间高能质子和重离子通量.从质子和重离子的能谱出发,结合OULU台站中子强度的数据,提出了由地面中子强度数据反演空间高能质子和重离子微分通量的新方法.文中以GOES卫星上350～420 MeV,420～510 MeV,510～700 MeV,＞700 MeV(P8～P11)四能道的高能质子和ACE卫星上的元素C为例,并将反演的数据与测量结果比较,二者符合较好.为了探索这种反演方法在空间辐射环境描述中的应用,同时利用2006年11月和12月质子通量的反演结果对反演方法进行了验证,证明利用这一反演方法可以从地面中子强度的数据很好地反演出空间质子和重离子的微分通量.      

分布式液压流体脉动主动控制方法

针对飞机液压能源管路系统中的周期性流体脉动诱发流固耦合振动,导致管路疲劳损伤的问题,针对管路中存在压力驻波特性,在采用单点消振时寻找误差传感器最佳布局位置困难而引起脉动抑制效果不理想的缺点,提出了一种分布式流体脉动主动控制方法,即沿管路不同位置布置多个主动消振阀和误差压力传感器,在任意飞行阶段,避开压力驻波点,以误差压力传感器的脉动测量值为控制目标,采用一种针对周期脉动主动控制的自适应前馈控制法和多通道自适应滤波-X LMS(Least Mean Square)算法,调整控制器参数,使主动消振器产生的次级脉动与管路中的初始脉动相互抵消,达到整个管路中的平均流体脉动最小的效果.为了验证分布式主动控制方法的有效性,设计了主动控制平台.实验结果表明,所提出的分布式流体脉动主动控制原理和方法能对流体脉动进行很好的抑制,消振量达10 dB以上.      

受剪紧固件DFR_τ的确定方法

本文介绍DFR_τ和其他疲劳参数之间的关系以及利用受拉光滑试件疲劳试验数据、根据强度理论并考虑擦伤影响来确定DFR_τ的方法。     

机载存储系统快速维护方法设计与实现

对一个典型的综合化航空电子系统中的存储单元进行分析,解决其配置的事务型文件系统在实际使用一段时间之后,因自身结构不断增加导致查找有效信息的时间持续增长,影响实际的文件操作效率的问题。设计了一种机载存储系统快速维护方法,通过增加预设的逻辑分区作为临时存储区,设计适合工程使用的操作流程,实现在不影响原有存储文件的情况下,对...     

基于射流搅拌燃烧反应器加压条件下的航空煤油燃烧NOx排放

为了研究碳氢燃料燃烧产物NOx的排放,构建了射流搅拌燃烧反应器(JSCR)试验系统,并经过了初步验证.随后利用该试验系统对航空煤油RP-3的燃烧NOx排放进行了测试,射流搅拌燃烧反应器内压力为2×105 Pa和3×105 Pa,进口温度为650K,当量比范围为0.5~1.2.研究结果表明:在当量比为0.5~1.2范围内,航空煤油燃烧NOx排放先随当量比的增大而增多,在当量比为0.95附近达到最大值,随后减少;NOx排放随压力的增大而增多.同时,验证了该射流搅拌燃烧反应器可作为研究碳氢燃料燃烧产物的基础试验平台.     

Changing law of launching pitching angular velocity of rotating missile

In order to provide accurate launching pitching angular velocity（LPAV） for the exterior trajectory optimization design, multi-flexible body dynamics（MFBD） technology is presented to study the changing law of LPAV of the rotating missile based on spiral guideway. An MFBD virtual prototype model of the rotating missile launching system is built using multi-body dynamics modeling technology based on the built flexible body models of key components and the special force model.The built model is verified with the frequency spectrum analysis. With the flexible body contact theory and nonlinear theory of MFBD technology, the research is conducted on the influence of a series of factors on LPAV, such as launching angle change, clearance between launching canister and missile,thrust change, thrust eccentricity and mass eccentricity, etc. Through this research, some useful values of the key design parameters which are difficult to be measured in physical tests are obtained. Finally,a simplified mathematical model of the changing law of LPAV is presented through fitting virtual test results using the linear regression method and verified by physical flight tests. The research results have important significance for the exterior trajectory optimization design.     

Damage characteristics and constitutive modeling of the 2D C/Si C composite: Part I – Experiment and analysis

This paper reports an experimental investigation on the macroscopic mechanical behaviors and damage mechanisms of the plain-woven(2D) C/Si C composite under in-plane on- and offaxis loading conditions. Specimens with 15, 30, and 45 off-axis angles were prepared and tested under monotonic and incremental cyclic tension and compression loads. The obtained results were compared with those of uniaxial tension, compression, and shear specimens. The relationships between the damage modes and the stress state were analyzed based on scanning electronic microscopy(SEM) observations and acoustic emission(AE) data. The test results reveal the remarkable axial anisotropy and unilateral behavior of the material. The off-axis tension test results show that the material is fiber-dominant and the evolution rate of damage and inelastic strain is accelerated under the corresponding combined biaxial tension and shear loads. Due to the damage impediment effect of compression stress, compression specimens show higher mechanical properties and lower damage evolution rates than tension specimens with the same off-axis angle. Under cyclic tension–compression loadings, both on-axis and off-axis specimens exhibit progressive damage deactivation behaviors in the compression range, but with different deactivation rates.     

76°/40°双三角翼前缘涡破裂及其控制实验研究

流动显示结果表明,喷流能有效地推迟双三角翼前缘涡的破裂,且随着攻角的增大,前缘涡破裂位置逐渐推后,喷流极大地改善了大攻角情况下前缘涡的非对称破裂特性,能有效地克服可能出现的机翼的"摇滚"现象.另外,后缘喷流可以减弱乃至消除前缘涡混掺现象的发生,进而有利于飞行器的操纵.      

短裂纹疲劳扩展的试验方法

近十年来,人们发现短裂纹具有一系列不同于普通长裂纹的特异扩展规律,它对耐久性损伤容限分析具有重要的意义。短裂纹扩展率试验是短裂纹研究中一项迫切而重要的,同时也是较为困难的工作。