大涵道比涡扇发动机分开式排气系统设计参数影响研究

为了分析外涵可用压比、内外涵出口面积以及核心外罩长度四个参数对大涵道比涡扇发动机分开式排气系统气动性能的影响,以该排气系统为原型采用数值模拟的方法对其性能进行研究。结果表明：存在一个最佳外涵可用压比使推力系数最大,但此时外涵处于欠膨胀状态,其设计规律与单喷管设计不同;存在一个使得推力系数最大的最佳喷管出口面积,此时喷管处于微弱的过膨胀状态,这主要与核心外罩／尾锥上的压强分布有关;核心外罩长度对排气系统性能存在一定程度的影响。     

高精度多用温度仪表检测仪

介绍了一种温度计量综合标准仪器的工作原理,技术参数,结构功能特点及校准方法。     

航班地面等待模型中的延误成本分析与仿真

研究了航班地面等待模型中延误成本的计算问题。建立了单元受限地面等待问题的数学模型,分析了航班延误成本的构成,给出了航班延误显性成本的计算方法,并将其应用于数学模型中目标函数的计算。最后,用分段排序和定步长排序对模型进行了仿真,并与先到先服务(F irst com e,first served,FCFS)排序进行了比较。仿真结果表明,对航班延误成本进行定量分析,能够更有效地控制航班延误的地面等待成本。     

Time delay of ionospheric TEC storms to geomagnetic storms and pre-storm disturbance events in East Asia

Using the TEC data at Beijing (39.61°N, 115.89°E)/Yakutsk (62.03°N, 129.68°E) stations of East Asia regions and relevant geomagnetic data from 2010 to 2017, we have studied the time delay of ionospheric storms to geomagnetic storms and compare it with our previous results of Taoyuan (25.02°N, 121.21°E) station (Zhang et al., 2020). The data shows a well-known local time dependence of the time delay, and seasonal dependences are different at these stations. In addition, there is no correlation between the time delay and the magnetic storm intensity /solar activity, except the time delay of negative storms has weakly negative dependence on the solar activity. Comparing with the results of Taoyuan station which is located at EIA region in East Asia, we find that the time delay increases nonlinearly as the latitude decreases due to different ionospheric backgrounds at these places. Moreover, the pre-storm disturbance events are found to have similar statistical characteristics as the pre-storm enhancement in Europe middle latitudes (Bure?ová and La?tovi?ka, 2007). By subtracting the common features of the pre-storm disturbance events, we preliminarily infer that auroral activity might be main driver of the pre-storm disturbance events.     

Polysaccharide from Loquat Leaves to Prepare Hierarchical Porous Carbon as a Matrix for Active Sulfur

Fossil fuel exhaustion and overdevelopment usually lead to a recession,which is worsened by the environmental pollution.So it is of high priority to develop high-efficiency energy storage device.Here,agreen and environment-friendly strategy is devised to fabricate carbon materials from biomass.By water extraction and alcohol precipitation,polysaccharide is extracted from loquat leaves.After calcining under high temperature,hierarchical porous carbon materials(HPCM)are obtained,possessing a variety of macropores,mesopores and micropores.Such ample and hierarchical pores enable the electrolyte infiltration and the buffering of the volume expansion of sulfur in repeated electrochemical reactions.The structure stability of the entire electrode can thus be well maintained.When evaluated as the scaffold for sulfur,the electrochemical performance of carbon/sulfur composite was tested.Even after 500 cycles,the reversible capacity is retained as high as 485.4 mA·h/g at the current density of 1.6 A/g.It also offers a notable rate capability,attaining the discharge capacity of 700.7 mA·h/g at 2 C.All the electrochemical performance results prove the feasibility of the proposed strategy.     

逼近无控旋转目标航天器的混合势函数安全制导

研究了追踪航天器逼近无控旋转目标航天器的安全制导问题，逼近过程中，追踪航天器需要躲避空间中的障碍物，同时需要避免与目标航天器的太阳能电池帆板和天线等附件发生碰撞。建立了视线坐标系下的两航天器间的相对运动方程，采用四元数描述目标航天器的姿态运动。将参考位置设为引力源，设计了吸引势函数。针对安全逼近问题，建立了球面安全区和锥面安全走廊，设计了安全势函数。将障碍物假设为具有一定半径的球体，设计了障碍物势函数。吸引势函数、安全势函数和障碍物势函数一起组成了混合势函数。为了解决整个势场中除参考位置外还可能存在其他局部极小点问题，对混合势函数进行了修正，保证参考位置位于混合势函数的最低点。利用Lyapunov稳定性理论对混合势函数进行了稳定性分析，推得符合要求的控制加速度，使追踪航天器沿着混合势函数的负梯度方向逼近无控旋转目标航天器。最后通过数值仿真验证了该方法的有效性。     

Statistical study of energetic electrons in Jupiter’s inner magnetosphere by Juno/JEDI

The Juno spacecraft made the first in-situ observations of energetic particles in the polar region of Jupiter’s magnetosphere. After Jupiter Orbit Insertion (JOI) in July 2016, data from ~20 Juno perijoves (PJs) obtained by Juno/JEDI are accumulated, providing an excellent opportunity to study the long term spatio-temporal distribution of energetic particles in Jupiter’s radiation belt. We transform Juno’s position from a Cartesian to a magnetic coordinate system by tracing magnetic field lines based on a fourth order Runge-Kutta method. Then the fluxes of energetic electrons from PJ1 to PJ14 sorted by different locations in magnetic coordinate space and the data are well organized by the L-shell parameter. The variation of electron flux increases with L-shell. The deviation (the ratio of the 75th percentile to the 25th percentile) of 0.51 MeV electron flux varies from a factor of 1.23 near L = 9.5 to 27.57 near L = 15.5. However, the mean flux decreases by about one order of magnitude in the same region. The electron spectra at larger L-shells are softer than that at smaller L-shells. On the other hand, the electron flux decreases more rapidly with increased L-shell when the location is off the equator. Along an L-shell, the electron flux decrease at first and then increase again from equator to mid-latitude region. In addition, we compare the statistical results with the widely used GIRE2 model. JEDI data correspond well with the GIRE2 model when the L-shell is > 14.75. GIRE2 underestimate the electron flux for L-shell smaller than 13.25. These results of this analysis are applicable to estimate the effects of the radiation environment in Jupiter’s magnetosphere.     

量子计算及其在空气动力学中的应用前景综述

量子计算是最重要的后摩尔计算技术之一，拥有经典计算机无可比拟的超强计算能力，未来能够对各行业应用产生颠覆性的影响。针对量子计算给空气动力学带来的机遇和挑战，详细综述了量子计算机、量子算法、量子底层软件栈等方面的研究进展。结合空气动力学领域常用的基础方法，在综述量子计算线性方程组求解、插值操作、数值积分、优化搜索等最新进展的基础上，结合典型量子算法深入分析了量子计算在空气动力学领域的应用前景，并指出了需要重点关注的研究方向。     

基于受摄轨道模型的小卫星轨道摄动分析研究

小卫星在实际运行中受到多种摄动力的作用,这会对其轨道造成不同程度的影响,因此在小卫星的轨道设计与控制中,摄动是必须考虑的重要因素。本文以500km高的小卫星太阳同步轨道为研究对象,运用轨道摄动的基本理论,估计了地球非球形引力、大气阻力、太阳光压及第三体引力的量级并进行比较;建立小卫星轨道摄动分析模型,并在此模型的基础上,利用计算机仿真技术,对小卫星轨道摄动问题展开仿真研究,验证了几种主要摄动力的量级估计的结果,分析比较了几种主要摄动力对小卫星运行轨道的影响程度及规律,本文结果对小卫星轨道设计与控制具有很好的参考价值。     

基于脉冲星的空间飞行器自主导航技术研究

研究了利用X射线脉冲星实现空间飞行器自主导航的原理,指出通过测量脉冲星发射的脉冲到达航天器与到达太阳系质心的时间差可以确定该航天器的位置。给出了两种适合用于处理脉冲星观测量的方法,即基于最小二乘(LS)的方法和基于卡尔曼滤波(KF)的方法。通过数值仿真验证了X射线脉冲星自主导航技术的可行性,并且说明采用KF算法能够有效利用卫星轨道运动方程中包含的导航信息,从而获得更高的导航精度。