航天发动机多余物自动检测系统

针对现有多余物检测装置检测效率低、精度低等问题,研制了一种航天发动机多余物自动检测系统,系统包括电机驱动转台的机械装置、驱动控制电路和信号调理采集电路。本文采用阈值比较和累积平均能量比较方法,实现多余物的粒径识别和空间定位。     

导弹舱体多余物检测系统设计

本文设计一套导弹舱体多余物检测系统,采用电机驱动被测导弹按规定转速转动,采用与导弹轴向平行的传声器阵列采集导弹舱体内的多余物碰撞声信号,对信号进行处理分析来判断导弹内是否存在多余物。基于传声器阵列采集信号的同步性、舱段内多余物活动范围和信号衰减规律等特征,提出一种将多次碰撞信号能量累加的方法,能够确定多余物的位置。基于检测流程和算法编制多余物检测软件,实现多余物检测过程的自动化。     

基于支持向量机的飞行器多余物信号识别

针对飞行器控制电路在生产制造过程中可能引入金属线头等微小多余物,从而留下短路等安全隐患的问题,提出了一种基于微粒碰撞噪声检测（PIND）的飞行器多余物材质识别方法。首先,利用短时自相关函数提取PIND信号的脉冲部分;然后,提取多种时频域统计特征,并与梅尔频率倒谱系数（MFCC）特征结合起来;最后,训练多分类支持向量机模型实现材质分类。为验证所提方法的有效性,采集了3种不同材质多余物的PIND信号进行模型训练及测试,实验结果表明,所提方法材质识别准确率达98%,优于同类方法的相关结果。      

浅谈先进检测技术支撑航天制造发展

检测技术是支撑航天制造发展的基础,检测技术水平直接关系着航天装备制造质量。主要介绍了检测技术在航天制造中的重要性,分析了航天装备制造过程中在检测方面现状和存在问题,结合航天发展需要给出发展建议,更好发挥检测技术对航天制造的支撑作用。     

2005年的世界航天活动

□□2005年全球共进行了55次航天发射(失败3次),与2004年(55次发射,失败5次)相比,发射次数持平,而失败率有所下降.     

火箭的癌症——多余物事故记实

1992年3月22日晚,全国亿万观众早早地围坐到电视机前,我国用“长征2号E”(简称“长二捆”)火箭为澳大利亚发射美制通信卫星的时刻就要到来.人们的心禁不住激烈地跳动起来。 18时40分,西昌卫星发射中心的操作人员准时批动了点火按钮。旋即,人们看到了火箭尾喷管喷出了通红的烈焰,发射架周围浓烟翻腾。然而,托举“澳星”的“长二捆”火箭却没有象人们希望的那样     

应用于制导系统弹载天线的研究

论述了弹载天线的圆极化形成机理,主要就弹尾方向天线辐射方向图的形成进行了设计和仿真,测量了天线的方向图,并进行了结果分析。     

表面等离子体共振生物传感器在微生物检测中的应用

在地球环境及航天空间环境中存在有多种多样的微生物,快速、准确地检测这些微生物成为亟待解决的问题.在众多微生物检测方法中,表面等离子体共振生物传感器凭借其快速、灵敏的检测特点,近年来发展迅速.本文综述了表面等离子体共振生物传感器在微生物检测领域中的应用,以期为地面及航天环境的微生物检测工作提供技术参考.     

2009年的世界航天活动

<正>2009年,世界航天活动呈现出蓬勃发展的态势,发射了不少新型卫星,载人航天也顺风顺水,美国还一举发射了2个月球探测器。1美国美中不足2009年,美国在多个航天领域都有突出的表现。例如:成功发射了"开普勒"空间望远     

一种实用高效的压力传感（变送）器校验系统

介绍了一种实用高效的压力传感 (变送 )器校验系统 ,较详细地阐述了这一系统的特点、硬件配置及软件设计方案。     

Reconnection active layers

The analysis presented shows that the classical model of non-linear magnetic field line reconnection changes considerably in the presence of sheared magnetic fields and/or high tangential plasma flow components. This shear excites large amplitude Alfvén waves on both sides of the reconnection layer where the magnetic field is rotated to a common direction within the layer. In addition two slow shock (or rarefaction) waves within the reconnection layer are necessary to account for the remaining shear in plasma flow. The detailed structures of such reconnection layers with implications for magnetopause reconnection events are discussed.     

Observations of an active region filament

An active region filament was well observed on September 4, 2002 with THEMIS at the Teide observatory and SOHO/MDI. The full Stokes parameters of the filament were obtained in Hα and FeI 6302 Å lines. Using the data, we have studied the fine structure of the filament and obtained the parameters at the barb endpoints, including intensity, velocity and longitudinal magnetic field. Our results indicate: (a) the Doppler velocities are quiet different at barb endpoints; (b) the longitudinal magnetic fields at the barb endpoints are very weak; (c) there is a strong magnetic field structure under the filament spine.     

Multiwavelength monitoring of active galactic nuclei

Recent multiwavelength monitoring of active galactic nuclei (AGN), particularly with the IUE satellite, has produced extraordinary advances in our understanding of the energy-generation mechanism(s) in the central engine and of the structure of the surrounding material. Examples discussed here include both ordinary AGN and blazars (the collective name for highly variable, radio-loud AGN like BL Lac objects and Optically Violently Variable quasars). In the last decade, efforts to obtain single-epoch multiwavelength spectra led to fundamentally new models for the structure of AGN, involving accretion disks for AGN and relativistic jets for blazars. Recent extensions of multiwavelength spectroscopy into the temporal domain have shown that while these general pictures may be correct, the details were probably wrong. Campaigns to monitor Seyfert 1 galaxies like NGC 4151, NGC 5548 and Fairall 9 at infrared, optical, ultraviolet and X-ray wavelengths indicate that broad-emission line regions are stratified by ionization, density, and velocity; argue against a standard thin accretion disk model; and suggest that X-rays represent primary rather than reprocessed radiation. For blazars, years of radio monitoring indicated emission from an inhomogeneous synchrotron-emitting plasma, which could also produce at least some of the shorter-wavelength emission. The recent month-long campaign to observe the BL Lac object PKS 2155-304 has revealed remarkably rapid variability that extends from the infrared through the X-ray with similar amplitude and little or no discernible lag. This lends strong support to relativistic jet models and rules out the proposed accretion disk model for the ultraviolet-X-ray continuum.     

有源集成背馈式接收天线设计

为了提高接收天线系统的增益以及灵敏度,对于天线与射频前端组成的接收系统采用了一种有源集成接收天线的设计方案,从而省略了传统设计中的有源电路与微带天线之间的匹配网络.依照此方案,设计并实现了一个背馈结构的矩形微带天线与前级低噪声放大器电路的有源集成.矩形微带天线的馈电点与低噪声放大器的输入端通过金属探针相连,当天线在2.48?GHz谐振时,通过选择合适的馈电点位置,天线产生放大器设计所需的输入阻抗.有源集成背馈式接收天线工作于S波段,最终的测试结果显示了其优良的特性.     

Latitudinal distribution of solar coronal active regions

We studied the cyclic evolution of the latitudinal distribution of solar coronal active regions based on daily images from SOHO EIT for the period 1995–2017. Fully automated software was used, which included the following steps: initial preparation of images in the data series, normalization of histograms and correction of limb brightening, segmentation of images using threshold intensity values obtained from their histograms, scanning of segmented images in heliographic coordinates and obtaining profiles of latitudinal distribution of coronal active regions for each image of the data series. From the output data, we obtained a temporary change in the latitudinal distribution profiles and the migration of activity centers on the solar disk. From the period of minimum activity to the next minimum in both hemispheres, activity centers begin to migrate from high latitudes towards the equator. At the same time, the general center of activity repeatedly changes the direction of migration. The latitudinal distribution of the so-called presence factor of coronal active regions closely resembles the magnetic butterfly diagram, which proves their direct causal relationships. Variations in the presence factor of coronal active regions are correlated with cyclic variations in the sunspot daily numbers.     

Multiple wavelength observations of flaring active regions

We present observations of flaring active regions with the Very Large Array (V.L.A. at 6 cm and 20 cm wavelengths) and the Westerbork Synthesis Radio Telescope (W.S.R.T. at 6 cm wavelength). These are compared with photospheric magnetograms (Meudon) and with Hα and offband Hα photographs (Big Bear and Ottawa River Solar Observatories). The 6 cm radiation of these active regions marks the legs of dipolar loops which have their footpoints in lower-lying sunspots. The intense, million degree radiation at 6 cm lies above sunspot umbrae in coronal regions where the longitudinal magnetic field strength H_? = 600 Gauss and the height above the sunspot umbrae h = 3.5±0.5 × 10⁹ cm. Circularly polarized horseshoe structures at 6 cm ring the sunspot umbrae. The high degree of circular polarization (?_c = 95%) of the horseshoes is attributed to gyroresonant emission above sunspot^? penumbrae. The 20 cm radiation of these active regions exhibits looplike coronal structures which extend across regions of opposite magnetic polarity in the underlying photosphere. The 20 cm loops are the radio wavelength counterparts of the X-ray coronal loops. We infer semilengths L = 5 × 10⁹ cm, maximum electron temperatures T_e(max) = 3 × 10⁶ K, emission measures ∫N_e²d$\text{l}$ = 10²⁸ cm^?5, and electron densities N_e = 10⁹ cm^?3 (or pressures p = 1 dyn cm^?2) for the 20 cm bremsstrahlung. A total of eight solar bursts were observed at 6 cm or 20 cm wavelength with second-of-arc angular resolution. The regions of burst energy were all resolved with angular sizes between 5″ and 30″, brightness temperatures between 2 × 10⁷ K and 2 × 10⁸ K, and degrees of circular polarization between 10% and 90%. The impulsive phase of the radio bursts are located near the magnetic neutral lines of the active regions, and between the flaring Hα kernels which mark the footpoints of magnetic loops. In one case there was preburst heating in the coronal loop in which a burst occurred. Snapshot maps at 10 s intervals reveal interesting burst evolution including rapid changes of circular polarization and an impulsive burst which was physically separated from both the preburst radio emission and the gradual decay phase of the burst.     

LINERs as low-luminosity active galactic nuclei

Many nearby galaxies contain optical signatures of nuclear activity in the form of LINER nuclei. LINERs may be the weakest and most common manifestation of the quasar phenomenon. The physical origin of this class of objects, however, has been ambiguous. I draw upon a number of recent observations to argue that a significant fraction of LINERs are low-luminosity active galactic nuclei. The evidence in favor of this interpretation includes the similarity in the properties of the host galaxies of LINERs and Seyferts, the detection of broad-line regions, the detection of black holes in a handful of nearby galaxies that are spectroscopically recognized as LINERs, the presence of a compact nuclear source seen in the radio, ultraviolet, and X-rays, and the detection of nonthermal spectra in the hard X-ray band. The spectral energy distributions of LINERs differ dramatically from those of luminous AGNs, most notably in the absence of the “big blue bump.” This and other characteristics suggest that the central engine in LINERs is fed by a very low accretion rate.     

主动对等计算系统的路由机制

针对无结构对等计算系统路由机制中用户需求粒度过细,忽略需求模糊性和多元性的问题,提出了基于用户需求的路由机制.借鉴模糊理论,提出了从文件类型、文件质量、下载速度多方面综合评价节点能力的路由模型.给出了节点能力因素及节点能力的定义,采用隶属度的方式来描述节点提供资源的能力与用户需求的符合程度.分析和实验结果表明,该机制在满足用户需求和减少网络开销方面能够达到很好的均衡.      

CORONAS-F observations of active phenomena on the sun

Complex observations in the framework of the CORONAS-F Mission aimed at the study of active phenomena inthe solar corona are described. The main features are given for the following experiments: (1) XUV-imaging spectroscopy with high temporal and spatial resolution, (2) X-ray spectroscopy, (3) X-ray and gamma-ray photometer/spectrometer, and (4) solar cosmic rays. Some new observational data on the structure and dynamics of flares and transient events are discussed along with their analysis.