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301.
低温回路热管是一种应用前景广阔的航天器热控设备。为了利用低温回路热管实现航天器低温部件的主动控温,进行了低温回路热管传热性能试验,并对试验中发现的低温回路热管控温性能进行了理论分析,进而对现有低温回路热管的结构进行了改进。改进后的低温回路热管能够在全功率范围内保持系统温差(主蒸发器与冷凝器温差)恒定,并能通过调节储液器上的加热功率,实现一定温度范围内的主动温度控制,使低温回路热管具有了毛细泵回路的控温功能。 相似文献
302.
The optimal guidance problem for an interceptor against a ballistic missile with active defense is investigated in this paper.A class of optimal guidance schemes are proposed based on linear quadratic differential game method and numerical solution of Riccati differential equation.By choosing proper parameters, the proposed guidance schemes are able to drive the interceptor to the target and away from the defender simultaneously.Additionally, fuel cost, control saturation,chattering phenomenon a... 相似文献
303.
The hot jet injection is utilized to actively control the oblique detonation wave, such as initiating and stabilizing an oblique detonation wave at a desired position that is shorter than the length of induction zone, and adjust the height of the oblique detonation wave at the exit of combustor when the oblique detonation wave engine is working on off-design flight conditions.The fifth order Weighted Essentially Non-Oscillatory(WENO) scheme and a two-step reversible reaction mechanism of the sto... 相似文献
304.
The application of reliability analysis and reliability sensitivity analysis methods to complicated structures faces two main challenges: small failure probability(typical less than 10-5) and time-demanding mechanical models. This paper proposes an improved active learning surrogate model method, which combines the advantages of the classical Active Kriging – Monte Carlo Simulation(AK-MCS) procedure and the Adaptive Linked Importance Sampling(ALIS) procedure.The proposed procedure can... 相似文献
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《中国航空学报》2022,35(8):221-235
Aimed at the problem of instability in engine control caused by vector deflection in experiment of turbofan engines with Axisymmetric Vectoring Exhaust Nozzle (AVEN), a vector deflection stability control method of aero-engine based on Linear Active Disturbance Rejection Control (LADRC) is proposed. Firstly, based on CFD numerical simulation, aerodynamic performance model of AVEN is established, and the aerodynamic load change rule of the nozzle throat area actuator during vector deflection is revealed. Subsequently, the integrated model of AVEN/turbofan engine is established by Simulink/AMESim co-simulation. Finally, the nozzle throat area control loop based on LADRC is designed. The simulation results show that the integrated model can reflect the influence of vector deflection on the stability of the control system. The accuracy comparison between the fan rotor speed and the test data during vector deflection is larger than 1%, indicating a high degree of confidence. Compared with the conventional PID control, the designed LADRC control loop reduces the speed of the low-pressure rotor during vector deflection by 70%, which effectively improves the control stability of the vector deflection. Meanwhile, the fuel flow ratechange during the vector deflection process is smaller and more economical, which provides an important reference for engineering applications. 相似文献
307.
太阳活动区是太阳活动的主要发生源区,活动区的形态、结构、特征是预报太阳爆发的主要依据.因此,活动区的识别是实现太阳爆发预报的前提.SDO/HMI能够提供连续、高时空精度的全日面光球观测图像.参照文献[1]SOHO/MDI综合磁图中活动区的自动识别方法,利用实时可得的HMI全日面磁图,通过阈值法、数学形态法和区域增长法相结合的方式,开展了活动区的快速自动识别研究.将2010—2018年的自动识别结果与NOAA/SWPC每日发布的活动区结果进行比较发现:通过磁图自动识别的活动区数目与SWPC活动区数目整体变化趋势基本一致,两者的相关系数为0.87;从活动区整体标识的数目上来看,通过磁图自动识别的活动区数目少于SWPC发布的结果.未被自动标识的活动区主要为面积小、磁场弱且磁类型简单的活动区,引发太阳爆发的可能性极小,因此不会对太阳爆发的实际预报产生影响.本文的研究方法和结果能够为太阳活动预报提供实时的活动区数据,加速太阳爆发预报模型的实际应用. 相似文献
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S.C. Tripathy K. Jain S. Kholikov F. Hill S.P. Rajaguru P.S. Cally 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(2):691-704
We analyze data from the Helioseismic Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) instruments on board the Solar Dynamics Observatory (SDO) to characterize the spatio-temporal acoustic power distribution in active regions as a function of the height in the solar atmosphere. For this, we use Doppler velocity and continuum intensity observed using the magnetically sensitive line at 6173?Å as well as intensity at 1600?Å and 1700?Å. We focus on the power enhancements seen around AR 11330 as a function of wave frequency, magnetic field strength, field inclination and observation height. We find that acoustic halos occur above the acoustic cutoff frequency and extends up to 10?mHz in HMI Doppler and AIA 1700?Å observations. Halos are also found to be strong functions of magnetic field and their inclination angle. We further calculate and examine the spatially averaged relative phases and cross-coherence spectra and find different wave characteristics at different heights. 相似文献