冲压发动机超声速进气道研究进展

超声速进气道是冲压发动机的关键部件之一。简要介绍了冲压发动机常用的典型进气道。重点叙述了进气道的最新研究成果,主要包括等溢流角弯曲前缘侧壁压缩进气道设计概念、支板引射压缩进气道、双模态超燃冲压发动机变几何进气道、全外压缩式超声速“参数进气道”、固定型面方转椭圆形超声速进气道（REST）等的设计概念与方案。最后概括了先进进气道的发展趋势。     

客舱英文广播的现状及对策分析

国际民航组织规定英语是国际民航的专门用语。广播的正确性、传递信息的准确性是衡量广播质量高低的标准。目前中国民航客舱英语广播不尽人意,没有达到广播应有的效果。本文根据交际理论,对客舱英文广播的现状进行分析,同时提出相应的改进对策以提高客舱英文广播的质量,进而提高安全水平和服务质量。     

Dark energy,co-evolution of massive black holes with galaxies,and ASTROD-GW

The detection of low frequency band (100 nHz–100 mHz) and very low frequency band (300 pHz–100 nHz) gravitational waves (GWs) is important for exploration of the equation of state of dark energy and the co-evolution of massive black holes (MBHs) with galaxies. Most galaxies are believed to have a massive black hole in the galactic core. In the formation of these black holes, merging and accretion are the two main processes. Merging of massive black holes generate GWs which could be detected by space GW detectors and Pulsar Timing Arrays (PTAs) to cosmological distances. LISA (Laser-Interferometric Space Antenna) is most sensitive to the frequency band 1 mHz–100 mHz, ASTROD-GW (ASTROD [Astrodynamical Space Test of Relativity using Optical Devices] optimized for Gravitational Wave detection) is most sensitive to the frequency band 100 nHz–1 mHz and PTAs are most sensitive to the frequency band 300 pHz–100 nHz. In this paper, we discuss the sensitivities and outlooks of detection of GWs from binary massive black holes in these frequency bands with an emphasis on ASTROD-GW. The GWs generated by the inspirals, merging and subsequent ringdowns of binary black holes are standard sirens to the cosmological distance. Using GW observations, we discuss the methods for determining the equation of state of dark energy and for testing the co-evolution models of massive black holes. ASTROD-GW is an optimization of ASTROD to focus on the goal of detection of GWs. The mission orbits of the 3 spacecraft forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4 and L5. The 3 spacecraft range interferometrically with one another with arm length about 260 million kilometers. With 52 times longer in arm length compared to that of LISA, the strain detection sensitivity is 52 times better toward larger wavelength. The scientific aim is focused for gravitational wave detection at low frequency. The science goals include detection of GWs from MBHs, and Extreme-Mass-Ratio Black Hole Inspirals (EMRI), and using these observations to find the evolution of the equation of state of dark energy and to explore the co-evolution of massive black holes with galaxies.     

A new inversion algorithm for HF sky-wave backscatter ionograms

HF sky-wave backscatter sounding system is capable of measuring the large-scale, two-dimensional (2-D) distributions of ionospheric electron density. The leading edge (LE) of a backscatter ionogram (BSI) is widely used for ionospheric inversion since it is hardly affected by any factors other than ionospheric electron density. Traditional BSI inversion methods have failed to distinguish LEs associated with different ionospheric layers, and simply utilize the minimum group path of each operating frequency, which generally corresponds to the LE associated with the F₂ layer. Consequently, while the inversion results can provide accurate profiles of the F region below the F₂ peak, the diagnostics may not be so effective for other ionospheric layers. In order to resolve this issue, we present a new BSI inversion method using LEs associated with different layers, which can further improve the accuracy of electron density distribution, especially the profile of the ionospheric layers below the F₂ region. The efficiency of the algorithm is evaluated by computing the mean and the standard deviation of the differences between inverted parameter values and true values obtained from both vertical and oblique incidence sounding. Test results clearly manifest that the method we have developed outputs more accurate electron density profiles due to improvements to acquire the profiles of the layers below the F₂ region. Our study can further improve the current BSI inversion methods on the reconstruction of 2-D electron density distribution in a vertical plane aligned with the direction of sounding.     

Numerical simulation of time delay interferometry for a LISA-like mission with the simplification of having only one interferometer

In order to attain the requisite sensitivity for LISA, laser frequency noise must be suppressed below the secondary noises such as the optical path noise, acceleration noise etc. In a previous paper (Dhurandhar, S.V., Nayak, K.R., Vinet, J.-Y. Time delay interferometry for LISA with one arm dysfunctional. Class. Quantum Grav. 27, 135013, 2010), we have found a large family of second-generation analytic solutions of time delay interferometry with one arm dysfunctional, and we also estimated the laser noise due to residual time-delay semi-analytically from orbit perturbations due to Earth. Since other planets and solar-system bodies also perturb the orbits of LISA spacecraft and affect the time delay interferometry (TDI), we simulate the time delay numerically in this paper for all solutions with the generation number n ? 3. We have worked out a set of 3-year optimized mission orbits of LISA spacecraft starting at January 1, 2021 using the CGC2.7 ephemeris framework. We then use this numerical solution to calculate the residual optical path differences in the second-generation solutions of our previous paper, and compare with the semi-analytic error estimate. The accuracy of this calculation is better than 1 cm (or 30 ps). The maximum path length difference, for all configuration calculated, is below 1 m (3 ns). This is well below the limit under which the laser frequency noise is required to be suppressed. The numerical simulation in this paper can be applied to other space-borne interferometers for gravitational wave detection with the simplification of having only one interferometer.     

极远紫外成像光谱仪在空间科学中的应用与展望

极远紫外成像光谱仪是空间科学研究中重要的数据获取工具,通过对不同天体目标极远紫外辐射的观测,可以反演出天体中主要物质的含量和变化规律,从而为空间天气、宇宙起源等许多前沿科学提供研究资料。文章分析了极远紫外成像光谱仪在空间科学研究中的优势,介绍了国际发展概况．列举了日地空间环境观测、地外行星体观测和宇宙空间观测3个应用领...     

量子光谱成像技术及其在对地观测中的应用前景

综述了量子光谱成像技术的发展概况,简述了量子光谱成像原理的理论,详细介绍了纠缠双光子源的鬼成像,亚波长干涉以及热光的无透镜成像和热光的非定域双缝干涉实验及其原理。最后对量子光谱成像技术在未来的军用和民用对地观测的应用方面做出了展望。     

基于联合隐马尔科夫模型的SAR图像去噪方法

提出一种联合隐马尔科夫模型的SAR图像去噪方法。基于贝叶斯准则估计隐马尔科夫树状模型的参数集合,得到各小波系数的期望值和收缩系数;引入二阶马尔科夫随机场模型去除小波系数尺度内的相关性,根据每个小波系数邻域内所有小波系数的隐状态和收缩系数,计算得到新的收缩系数,并对各小波子带的小波系数进行收缩,从而有效复原无噪声图像。实验表明,方法具有很强的噪声抑制能力,相对隐马尔科夫模型大幅提高了等效视数,且较好地保持了边缘。     

基于多组合窗函数的NLFM信号匹配滤波器设计

文章研究了在相位逗留原理的基础上采用由多种窗函数线性组合得到的组合窗设计NLFM信号的波形与脉冲压缩滤波器,重点分析了组合窗函数的组合参数及窗函数数量对NLFM信号脉冲压缩结果的影响。仿真结果表明,在一定条件下对基于三种窗函数线性组合的组合窗设计的NLFM信号进行谱修正滤波后,主副瓣比（RMS）可提高4．6～8．9dB,而主瓣展宽和主瓣损失变化较小。     

基于双力源的叠加式多维力传感器校准装置研

介绍了一种基于叠加机原理的双力源多维力传感器校准装置的设计与研制,对装置的测量不确定度进行了分析,通过对三分量力传感器的校准实验,证明了校准装置不仅可以对多分量力传感器进行单分量校准,还能方便地实现耦合误差的校准。