Longitudinal behaviors of the IRI-B parameters of the equatorial electron density profiles retrieved from FORMOSAT-3/COSMIC radio occultation measurements

The electron density profiles in the bottomside F₂-layer ionosphere are described by the thickness parameter B0 and the shape parameter B1 in the International Reference Ionosphere (IRI) model. We collected the ionospheric electron density (N_e) profiles from the FORMOSAT-3/COSMIC (F3/C) radio occultation measurements from DoY (day number of year) 194, 2006 to DoY 293, 2008 to investigate the daytime behaviors of IRI-B parameters (B0 and B1) in the equatorial regions. Our fittings confirm that the IRI bottomside profile function can well describe the averaged profiles in the bottomside ionosphere. Analysis of the equatorial electron density profile datasets provides unprecedented detail of the behaviors of B0 and B1 parameters in equatorial regions at low solar activity. The longitudinal averaged B1 has values comparable with IRI-2007 while it shows little seasonal variation. In contrast, the observed B0 presents semiannual variation with maxima in solstice months and minima in equinox months, which is not reproduced by IRI-2007. Moreover, there are complicated longitudinal variations of B0 with patterns varying with seasons. Peaks are distinct in the wave-like longitudinal structure of B0 in equinox months. An outstanding feature is that a stable peak appears around 100°E in four seasons. The significant longitudinal variation of B0 provides challenges for further improving the presentations of the bottomside ionosphere in IRI.     

有限元法在光学侧窗热防护设计中的应用

光学侧窗热环境极为严酷,可采用液体对流内冷却技术对光学侧窗进行热防护。以有限元法对光学侧窗温度场进行了分析研究,研究结果表明:该方法计算精度可靠;液体对流内冷却技术能有效起到降温的作用。同时还定量的给出了冷却液用量对结构温度场的影响,为设计的经济可行性提供了保障。     

主燃孔位置对基于RQL高温升燃烧室流动与燃烧特性影响的数值模拟

为将富油燃烧/快速淬熄/贫油燃烧（RQL）用于高温升燃烧室设计，以实现温升与排放的良好统一，对不同主燃孔位置下 的单头部矩形燃烧室流动、淬熄区气流混合、燃烧和排放特性进行数值模拟。结果表明：燃烧室中心回流区的长度和高度随着主 燃孔轴向距离的增大而增大。随着主燃孔轴向距离的增大，主燃孔射流深度增加，射流角度逐渐向下游偏转，导致淬熄区内气流 的混合效果减弱；随着主燃孔位置的后移，富油区内的当量比显著增大，导致CO和碳烟的生成量迅速增加，淬熄区内的沿程高温 区域面积逐渐缩小，燃烧效率逐渐降低。当X/H=0.7时，燃烧室沿程NO生成量始终处在较大值；而当X/H=0.9时，燃烧室沿程NO 生成量始终处于较小值，但CO的生成量增大。     

Ansys在镀锌锅空间温度场分析中的应用

利用Ansys对镀锌锅上方空间的温度场进行模拟。在模拟过程中，利用Ansys软件中的FlotranCFD模块建立模型，计算锌锅上方空间的流场和温度场分布情况，分析温度的主要影响因素，为热镀锌生产线的工程设计提供了理论依据。此方法也为温度分析提供了一种新的思路。     

Three dimensional investigation of the shock train structure in a convergent–divergent nozzle

Three-dimensional computational fluid dynamics analyses have been employed to study the compressible and turbulent flow of the shock train in a convergent–divergent nozzle. The primary goal is to determine the behavior, location, and number of shocks. In this context, full multi-grid initialization, Reynolds stress turbulence model (RSM), and the grid adaption techniques in the Fluent software are utilized under the 3D investigation. The results showed that RSM solution matches with the experimental data suitably. The effects of applying heat generation sources and changing inlet flow total temperature have been investigated. Our simulations showed that changes in the heat generation rate and total temperature of the intake flow influence on the starting point of shock, shock strength, minimum pressure, as well as the maximum flow Mach number.     

基于C8051单片机的多路温度无线遥测系统

基于C8051F020单片机和DTD465无线数传模块设计了多路温度双向无线遥测系统.温度测量采用铂电阻;无线数传模块基于FSK调制,采用高效前向纠错信道编码技术;系统为低功耗设计.介绍了测量站和主控站的软件,以及数据通信协议.系统已成功地应用于汽车导航实验中,使用结果表明,本系统软硬件设计完善,可靠性高,使用方便.     

On the measurements of the moon’s infrared temperature and its relation to the phase angle

Radiometric measurements of the thermal radiation originating from the moon’s surface were obtained using an infrared detector operating at wavelengths between 8 and 14 μm. The measurements cover a full moon cycle. The variation of the moon’s temperature with the lunar phase angle was established. The lunar temperatures were 391 ± 2.0 K for the full moon, 240 ± 3.5 K for the first quarter, and 236 ± 3 K for the last quarter. For the rest of the phase angles, the lunar temperature varied between 170 and 380 K. Our results are comparable with those obtained previously at these phase angles. For the new moon phase, the obtained temperature was between 120 and 133 K. With the exception of the new moon phase, our measurements at all the phase angles were consistent with those obtained using Earth-based data and those obtained by the Diviner experiment and the Clementine spacecraft. At the new phase, our measurements were comparable with those obtained from the ground but were significantly higher than those obtained by the Diviner and Clementine data. We attribute this inconsistency to either the calibration curve of our detector, which does not perform well at very low temperatures, or to infrared emission from the atmosphere. A simple linear model to predict the lunar temperature as a function of the phase angle was proposed. The experimental errors that affect the measured temperatures are discussed.     

D-region ionospheric disturbances associated with the Extremely Severe Cyclone Fani over North Indian Ocean as observed from two tropical VLF stations

The D-region ionospheric disturbances due to the tropical cyclone Fani over the Indian Ocean have been analysed using Very Low Frequency (VLF) radio communication signals from three transmitters (VTX, NWC and JJI) received at two low latitude stations (Kolkata-CUB and Cooch Behar-CHB). The cyclone Fani formed from a depression on 26th April, 2019 over the Bay of Bengal (Northeastern part of the Indian Ocean) and turned into an extremely severe cyclone with maximum 1-min sustained winds of 250 km/h on 2 May, 2019 which made landfall on 3 May, 2019. Out of six propagation paths, five propagation paths, except the JJI-CHB which was far away from the cyclone track, showed strong perturbations beyond $3\sigma$ level compared to unperturbed signals. Consistent good correlations of VLF signal perturbations with the wind speed and cyclone pressure have been seen for both the receiving stations. Computations of radio signal perturbations at CUB and CHB using the Long Wave Propagation Capability (LWPC) code revealed a Gaussian perturbation in the D-region ionosphere. Analysis of atmospheric temperature at different layers from the NASA’s TIMED satellite revealed a cooling effect near the tropopause and warming effects near the stratopause and upper mesosphere regions on 3 May, 2019. This study shows that the cyclone Fani perturbed the whole atmosphere, from troposphere to ionosphere and the VLF waves responded to the disturbances in the conductivity profiles of the lower ionosphere.     

梳状电容式微加速度计温度性能优化

零偏温度漂移是影响高精度MEMS加速度计整体性能的关键指标，敏感结构机械零位的温度漂移和电路零位(电容检测电路）的温度漂移是加速度计零偏温度漂移的直接原因。分析了影响加速度计零偏温度系数的3种主要影响因素，提出了某型加速度计伺服电路温度性能测试筛选方法，有效减小了电路零位的温度漂移。采用了全硅表头，同时对表头封装粘接方式进行优化，大幅减小了表头机械零位的温度漂移。经过这些优化措施后，加速度计的温度性能得到了明显改善，零偏温度系数由1.3mg/℃减小到0.5mg/℃，零偏的常温稳定性(1h）达到0.108mg，重复性(6次）达到0.141mg。     

激光脉冲圈焊工艺研究与应用

基于有限元软件MSC.MARC软件平台Hypermesh软件模块仿真模拟了激光连续圈焊和激光脉冲圈焊的温度场分布,模拟结果表明:激光脉冲圈焊可有效控制被焊工件温度场分布,焊接热影响区小,为此采用激光脉冲圈焊工艺焊接簧片式电磁阀簧片组件.研究了激光焊接频率与焊点重叠率以及激光焊接速度与焊缝强度和焊点重叠率之间的关系,从而得出了激光脉冲圈焊焊接工艺规范,即激光峰值功率Pf--300 W,激光基值功率Pj=200 W,激光焊接速度v=3.33 mm/s,激光频率f=20 Hz等,采用该焊接规范焊接完成的簧片式电磁阀已经应用于嫦娥五号探测器推进分系统、轨道器子系统以及上升器推进子系统的液体动力装置之中,并已经完成了飞行和月球探测任务.