圆柱贮箱类耦合系统的平动响应分析

本文以一种新方法建立了水平激励下圆柱贮箱类液固耦合系统的动力学方程。利用两类完全不同的Ｌａｇｒａｎｇｅ函数来描述液体子系统和结构子系统的运动,联立可得耦合系统的动力学方程。通过数值仿真发现,在一定的激励幅值和频率下,该耦合系统会出现零位漂移、分叉等非线性动力学现象。     

基于耦合气动参数的HGV多模型估计

利用气动参数对未知气动力建模是提高高超声速滑翔目标跟踪精度的有效途径。对目标气动加速度及其导数项进行分析,在非耦合气动参数模型的基础上,考虑气动加速度在转弯和俯仰方向存在的先验信息,推导滚转和螺旋2种耦合气动参数模型。利用一种分离估计模型对目标状态与气动参数进行估计,分别给出状态滤波器和气动参数滤波器的表达式。同时,考虑不同飞行模式下参数的机动频率,构建基于耦合气动参数的交互多模型跟踪算法。仿真表明,本文所提算法精度显著高于针对该类目标的其他跟踪算法。同时,滚转模型的性能优于螺旋模型,且计算复杂度更小。      

火工品电参数测试技术研究

介绍了火工品电参数测试方法,搭建了火工品电参数测试系统。设计了火工品电容放电式点火电路,阐述了电容充放电原理和充放电电路的参数计算方法,实现了点火回路电流的测试。采用“四线”制测试方法实现对火工品桥路直流阻值瞬态变化特性的测试,通过点火回路电压值的变化进行了火工品桥丝熔断时间的测试,证明了采用本测试系统进行火工品电参数测试的可靠性和正确性,为火工品电参数测试的研究提供了有效的测试方法。     

正态应力和疲劳强度结构可靠性的参数估计

结构可靠性的参数估计是机械可靠性的主要问题之一。强度和应力分别为疲劳寿命变量和正态变量的结构模式是一种较常见的模式。研究这一模式结构可靠性的参数估计问题,给出了疲劳强度和正态应力的两个分布中一个分布参数已知另一个分布参数未知时,结构可靠性的点估计和近似区间估计方法,并用MonteCarlo方法对近似区间估计的可靠性进行了模拟研究。     

改进变异策略的自适应差分进化算法及其应用

针对标准差分进化(Differential Evolution,DE)算法存在控制参数难以选取以及变异策略缺乏稳健性的不足,提出一种基于改进变异策略的自适应DE算法.该方法用随机选取子种群的最优个体替代全种群最优个体进行变异操作;然后采用柯西分布和正态分布分别对收缩因子和交叉概率进行扰动,并在进化过程中利用胜出个体自适应地递推调整参数分布.对五个典型Benchmark函数的测试结果表明:该方法在全局搜索能力、收敛速度和精度以及可靠性上比标准DE算法都有了大幅度提高.将该方法用于分布式孔径雷达的方向图综合问题,通过较少的仿真次数即可稳定的获得更低的旁瓣电平.     

基于云蚁群算法的高效节能氩弧焊工艺参数优化研究

为在氩弧焊加工过程中提升效率的同时降低能耗,研究了一种氩弧焊高效节能工艺参数的多目标优化模型及算法。首先确定了以焊接速度及焊接电流为优化变量,在综合考虑焊接设备、工件特性、操作方法及焊接质量等约束的前提下,建立了以最小电能消耗以及最短加工时长为优化目标的多目标工艺参数优化模型;提出一种基于云模型的蚁群算法(CBACO)以对所构建的优化模型进行求解,其中包含一种适当的编码方式、一种局部与全局相结合的探索策略、一种基于云模型的变异因子、传统的单点交叉因子、单形交叉因子以及适当的选择策略;通过一个针对某航空器油箱的焊接实例,对所提出的优化模型及算法的实用性进行了验证,结果表明优化参数可在保证加工质量的前提下有效地节省时间60.41%~69.05%,节省电能34.88%~46.30%。     

相控阵雷达长时跟踪波束调度与波形优化策略

针对相控阵雷达多目标跟踪波束调度和波形参数优化控制的问题，本文提出了一种基于马尔可夫决策过程（MDP）的相控阵雷达跟踪波束调度与波形参数优化策略，该方法以无迹卡尔曼滤波（UKF）算法为基础来估计目标的状态。首先将本文的序列决策问题建模为马尔可夫决策过程，定义了资源的效费比和长期回报率，然后与当前实际跟踪误差综合考虑作为MDP的回报函数，进而给出了调度的优化模型，最后将长时决策问题转化为动态规划算法结构进行求解，并且提出了一种并行混合遗传粒子群优化算法来求解各决策时刻的最优策略。仿真结果表明了长时策略的先进性以及寻优算法的优越性，与传统的短时策略相比，跟踪精度可提高11.17%。     

一起语音告警信号的故障研究

以某型飞机语音告警信号为例,分析了故障告警原理,找到了故障原因,为类似语音告警信号的排故提供参考。     

Standing window of oblique detonation with pathological behaviour

Standing of an Oblique Detonation Wave (ODW) on a wedge within combustor is the prerequisite of thrust generation for ODW engine which is regarded as a novel and conceptual propulsion device with hypersonic flight Mach number. Usually a standing window of ODW is defined as the wedge angle ranged from the ODW detached angle from wedge (upper limit) to the angle that a Chapman-Jouguet (CJ) detonation occurs (lower limit). For pathological detonation cases, however, the CJ detonation cannot be achieved, and thus the lower limit of the standing window of ODW should be revisited. In present study, two types of reactions in hypersonic incoming flow that include the behavior of pathological detonation, that is, the single-step irreversible reaction with mole variation and the two-step irreversible reactions with exothermic process followed by endothermic process, have been used for studying standing behavior of ODW. The steady detonation polar analysis of ODW is carried out for both reaction systems. The results reveal that the reaction with more mole decrement and the reactions with stronger endothermic process show the pathological detonation feature and therefore modify the lower limit of standing window of ODW. Three equivalent parameters are proposed to quantitatively measure the standing window range of ODW from points of view of thermodynamics, Mach number of incoming flow and heat effect of reactions. It is found that the standing window of ODW is determined by the specific heat ratio, the overdrive degree of detonation and the endothermic level of the hypersonic incoming flow, regardless of whether the detonation is pathological or not.     

Crustal deformation characteristics of Sichuan-Yunnan region in China on the constraint of multi-periods of GPS velocity fields

In order to obtain deformation parameters in each block of Sichuan-Yunnan Region (SYG) in China by stages and establish a dynamic model about the variation of the strain rate fields and the surface expansion in this area, we taken the Global Positioning System (GPS) sites velocity in the region as constrained condition and taken advantage of the block strain calculation model based on spherical surface. We also analyzed the deformation of the active blocks in the whole SYG before and after the Wenchuan earthquake, and analyzed the deformation of active blocks near the epicenter of the Wenchuan earthquake in detail. The results show that, (1) Under the effects of the carving from India plate and the crimping from the potential energy of Tibetan Plateau for a long time, there is a certain periodicity in crustal deformation in SYG. And the period change and the earthquake occurrence have a good agreement. (2) The differences in GPS velocity fields relative Eurasian reference frame shows that the Wenchuan earthquake and the Ya'an earthquake mainly affect the crustal movement in the central and southern part of SYG, and the average velocity difference is about 4–8?mm/a for the Wenchuan earthquake and 2–4?mm/a for the Ya'an earthquake. (3) For the Wenchuan earthquake, the average strain changed from 10 to 20 nanostrian/a before earthquake to 40–50 nanostrian/a after the earthquake, but before and after the Ya’an earthquake, the strain value increased from about 15 nanostrian/a to about 30 nanostrian/a. (4) The Wenchuan earthquake has changed the strain parameter of each active block more or less. Especially, the Longmen block and Chengdu block near the epicenter. The research provides fundamental material for the study of the dynamic mechanism of the push extrusion from the north-east of the India plate and the crimp from Qinghai Tibet Plateau, and it also provides support for the study of crustal stress variation and earthquake prediction in Sichuan Yunnan region.