低频信号的混沌高斯化检测方法

大气天电噪声是干扰低频信号的主要噪声源。文章主要针对大气噪声的高斯化方法进行研究,提出了基于混沌方程快速求解、混沌相变判别等技术的噪声高斯化方法,以非线性信号处理技术为依据,通过实验室模拟信道环境,完成低频弱信号的混沌高斯化及检测,2PSK弱信号检测的理论实验验证了其有效性,可为低频接收技术的发展提供依据。     

大气环境监测卫星在生态环境行业应用分析

大气环境监测卫星是首颗生态环境领域大气环境监测专用卫星。卫星搭载了5台有效载荷，可实现CO2主动激光探测和大气细颗粒物的主被动结合探测，以及对气态污染物、云和气溶胶、水环境、自然生态等要素大范围、全天时综合监测，为生态环境遥感监管提供重要的数据支撑。本文从卫星载荷特点及数据获取能力出发，分析了其在生态环境行业的应用能力，并从大气环境、水环境和生态环境监测3个方面，结合在轨测试情况对卫星的应用能力进行详细阐述，可为开展大气环境监测卫星遥感应用提供参考。     

Where is the base of the Transition Region? Evidence from TRACE,SDO, IRIS and ALMA observations

Classic solar atmospheric models put the Chromosphere-Corona Transition Region (CCTR) at $～2$ Mm above the ${\tau }_{5000}=1$ level, whereas radiative MHD (rMHD) models place the CCTR in a wider range of heights. However, observational verification is scarce. In this work we review and discuss recent results from various instruments and spectral domains. In SDO and TRACE images spicules appear in emission in the 1600, 1700 and 304 Å bands and in absorption in the EUV bands; the latter is due to photo-ionization of H i and He i, which increases with wavelength. At the shortest available AIA wavelength and taking into account that the photospheric limb is $～0.34$ Mm above the ${\tau }_{5000}=1$ level, we found that CCTR emission starts at $～3.7$ Mm; extrapolating to $\lambda =0$, where there is no chromospheric absorption, we deduced a height of $3.0\pm 0.5$ Mm, which is above the value of 2.14 Mm of the Avrett and Loeser model. Another indicator of the extent of the chromosphere is the height of the network structures. Height differences produce a limbward shift of features with respect to the position of their counterparts in magnetograms. Using this approach, we measured heights of $0.14\pm 0.04$ Mm (at 1700 Å), $0.31\pm 0.09$ Mm (at 1600 Å) and $3.31\pm 0.18$ Mm (at 304 Å) for the center of the solar disk. A previously reported possible solar cycle variation is not confirmed. A third indicator is the position of the limb in the UV, where IRIS observations of the Mg ii triplet lines show that they extend up to $～2.1$ Mm above the 2832 Å limb, while AIA/SDO images give a limb height of $1.4\pm 0.2$ Mm (1600 Å) and $5.7\pm 0.2$ Mm (304 Å). Finally, ALMA mm-$\lambda$ full-disk images provide useful diagnostics, though not very accurate, due to their relatively low resolution; values of $2.4\pm 0.7$ Mm at 1.26 mm and $4.2\pm 2.5$ Mm at 3 mm were obtained. Putting everything together, we conclude that the average chromosphere extends higher than homogeneous models predict, but within the range of rMHD models..     

基于模式分集的星地激光通信技术研究

针对星地激光通信的大气湍流导致信号光损伤这一问题，实验搭建了一种能够补偿大气湍流的空间激光通信系统，采用模式分集接收结合最大比合并方法对大气湍流进行补偿，采用相干探测技术对高阶调制信号进行光电探测。在不同湍流强度下进行了传输实验，结果表明：模式分集空间激光通信系统的性能相比较于单模光纤接收系统有较大提升，随着湍流强度的增加，性能提升更加显著。在弱、中、强三种湍流强度以及相同目标误码率情况下，模式分集系统相比单模光纤接收系统分别降低了约4.2 dB、5.1 dB 和 5.5 dB的链路损耗。在弱、中、强三种湍流强度以及相同目标中断概率下，模式分集接收系统相比单模光纤接收系统分别降低了约3 dB、5.9 dB 和 4.3 dB的链路损耗。     

Far-field sonic boom prediction considering atmospheric turbulence effects: An improved approach

Accurate prediction of sonic boom is one of key challenges for the design of a low-boom supersonic aircraft. For most of available far-field prediction methods, the effect of atmospheric turbulence appearing in the planetary boundary layer cannot be considered, which results in remarkable inaccuracy of predicting ground-level sonic boom waveform. Although some efforts have been made to overcome the shortcoming, the turbulence effects are not yet well described so far. This article proposes an improved method by extending the two-dimensional Heterogeneous One-Way Approximation for the Resolution of Diffraction (HOWARD) equation to account for the axial and transverse convections of wind fluctuation as well as the effect of temperature fluctuation. The proposed method is validated by comparing the predictions with the flight-test data of JAXA D-SEND#1 LBM, which shows that the result of the proposed method is in better agreement with the flight-test data than that of the method without considering atmospheric turbulence effects. Then, distortion mechanism of sonic boom waveforms caused by atmospheric turbulence is analyzed by using the proposed method. It is indicated that the effect of turbulent convection makes uniform sonic-boom wavefronts irregular, which creates the condition of diffraction effect to perturb waveforms. Finally, the proposed method is applied to investigate the behavior of two types of waveforms given by the sonic boom minimization theory. Results show that a far-field waveform with a weaker initial shock is more beneficial for low-boom design of a supersonic aircraft.     

路径积分差分吸收激光雷达反演模型设计与测试

激光雷达作为主动探测手段，能够较好地弥补被动卫星(如OCO-2/3、GOSAT-1/2和Tan Sat等)的不足，实现高精度、全天候和全天时的观测。中国在2022年4月16日成功发射世界首颗基于主动理论探测二氧化碳柱浓度(XCO2)的激光雷达卫星。本文基于前期在秦皇岛的缩比飞行试验数据，围绕优化积分权重函数和优化差分吸收光学厚度两大核心要素，提出了基于光谱能量模型的算法框架。该框架旨在提高基于主动理论的星载激光雷达探测XCO2反演的精度。评估获得光谱能量模型在海上、陆地上的测距精度分别为0.74和6.20 m。论文的工作在10 s滑动平均值下，海洋、城市和山区的平均XCO2值分别为411.07、425.71、417.87 ppm，标准差分别为1.93、0.85、0.96 ppm。综上所述，光谱能量模型对我国发展基于差分吸收激光雷达的二氧化碳浓度算法具有重要的参考意义。     

大气环境监测卫星紫外高光谱大气成分探测仪技术发展及应用

大气环境监测卫星是我国民用空间基础设施中长期发展规划中的科研卫星。本文介绍了搭载于该卫星的新一代紫外高光谱大气成分探测仪，通过发展紫外高光谱大幅宽高分辨超光谱成像技术，使紫外谱段高光谱大气观测空间分辨率提升一倍，大幅提升气态污染物监测能力，取得良好的应用效果。     

适用于旋转通道各向异性湍流模型

基于代数雷诺应力方程的简化模型,并结合充分发展旋转通道的直接数值模拟（DNS）湍流脉动数据，发展了一种适用于旋转通道的各向异性k ω模型。采用该模型对进口雷诺数为6000，旋转数为0~0.26的旋转直通道进行模拟，结果表明:将旋转修正系数乘以传统的湍流黏度发展的各向异性k ω模型，能够准确地描述旋转状态下前缘面和后缘面的换热情况，是一种有效的各向异性湍流模型修正方法；旋转修正系数是否合理的关键是对雷诺应力比值进行准确地描述；通道的换热效果与旋转数和流向沿程无量纲位置有关,前缘面的换热随旋转数和无量纲流向距离的增加而减小，而后缘面的换热随旋转数和无量纲流向距离的增加而增大。      

大气环境监测卫星宽幅成像仪高性能碲镉汞红外探测芯片

宽幅成像仪(WSI)是大气环境监测卫星中的主要载荷之一，可以提供从可见光到长波红外的地球环境成像遥感数据。宽幅成像仪中搭载了从1.3~12.5 μm红外波段进行探测的8个波段碲镉汞红外探测器，各波段采用窄带滤光片进行分光，8个波段的碲镉汞探测器封装在短波、中波和长波3个组件中。本文中对8个波段的碲镉汞红外探测器进行了概述，内容涵盖了探测器的设计思想、制备工艺和测试方法，最后给出了目前在轨运行的高性能探测器组件的探测率性能和响应光谱，同时与各波段器件的探测率指标进行了对比。