深空天文测角测速组合自主导航可观测性分析方法

导航系统的性能与其可观测性密切相关,而可观测矩阵是分析导航系统可观测性能的重要依据。本文基于分段线性定常系统(PWCS)方法给出导航系统的可观测矩阵,进而针对测角测速组合导航系统开展可观测性分析。通过分析测角测速组合导航系统可观测矩阵的秩和条件数,得到导航系统的可观测性和整体可观测度,并研究导航系统的可观测阶数对导航系统的影响;同时基于奇异值分解(SVD)方法给出测角测速组合导航系统各个状态分量的可观测性分析方法。最后,以小行星探测工程任务巡航段为背景,系统地给出了不同量测模型的导航系统可观测性结果,分析了不同可观测性分析方法对导航系统可观测性刻画的适用性。本文所提出的可观测性分析方法,对导航系统可观测性分析具有很好的参考性,可为组合导航系统量测模型的优选提供参考,具有良好的理论和应用价值。     

芳香烃对涡轴发动机排气冒烟影响的试验

为掌握涡轴发动机排气中的冒烟数及芳香烃体积分数对冒烟数的影响,设计了某涡轴发动机冒烟数测量试验方案,通过在RP-3航空煤油中添加甲苯(C6H5CH3)获得不同芳香烃体积分数,开展发动机排气冒烟试验;并根据实测冒烟数(SN)拟合得到了与计算冒烟质量浓度指数(CI)的关系式。试验结果表明:某型涡轴发动机采用基准燃油时各状态冒烟数均小于40,优于设计指标;最大起飞状态下芳香烃体积分数每增加3%可导致冒烟数升高6%。该试验为涡轴发动机排气冒烟数测量和预估提供了一种有效方法,并为通过减少燃油中芳香烃体积分数来抑制发动机冒烟数提供了依据。      

掺混长直链烷烃对航空煤油雾化性能影响

将藻基生物航空煤油加工过程的中间产物C13~C18分别与航空煤油按10%比例进行掺混,对掺混燃油的喷雾雾化性能进行了对比研究。结果表明:随掺混直链烷烃碳数增加,对燃油喷雾雾化影响逐渐增大。其中按10%比例掺混直链烷烃C18:雾化锥角最大减幅为5.07%;液滴平均速度最大变化17.6%;索泰尔平均直径最大变化15%;Ohnesorge数和韦伯数随着喷射压力增加而明显变化,会对液滴二次破碎产生影响。总体来说,加入长直链烷烃会对航空煤油的雾化性能产生一定的影响。      

旋流预混预蒸发装置蒸发和排放特性

采用数值模拟和试验两种方法获得了两种结构的贫油预混预蒸发装置(Lean premixing and prevaporizing system,简称LPP)出口的油气混合均匀性,并采用单管燃烧室验证了LPP装置的燃烧特性.径向旋流预混装置出口的油气混合比轴向旋流预混装置更均匀;旋流器的叶片数和旋流角、预混管长度、气流速度、喷油方式等对油气混合均匀性均有比较显著的影响;在当量比高至0.5左右时,LPP燃烧室NOX和CO排放比传统燃烧室低得多;只要LPP装置出口存在回流,燃烧时就会出现回火现象.      

Magnetic connectivity and solar energetic proton event intensity profiles at deka-MeV energy

We present an analysis of the time-intensity profiles of 25 solar energetic proton events at 18.2 MeV, modelled by fitting an analytical function form (a modified Weibull function) to the observed intensities. Additionally relying on previous work that characterized the magnetic connectivity between the event-related solar flare and the observer in these events with three angular parameters, we investigate the fit function parameters, the connectivity parameters, and the iron-to-carbon ratio of the events for dependencies and correlations. We find that the fit parameter controlling the basic shape of the profile (parameter a) is not clearly dependent on the connectivity parameters or the Fe/C ratio, suggesting that the profile shapes of neither well and weakly connected nor generally “impulsive” and “gradual” events differ systematically during the early stages of the event at 1 AU. In contrast, the time scaling of the fit function (parameter b) is at least moderately correlated with both the magnetic connectivity parameters and the Fe/C ratio, in that well-connected and iron-rich events are typically shorter in relative duration than weakly connected and nominal-abundance events; intensity rise times display a similar correlation with the connectivity parameters. We interpret the former result as following from the combined effect of various transport processes acting on the particles in interplanetary space, while the latter is essentially consistent with established knowledge regarding the observed dependence of the time-intensity profile shapes of solar energetic particle events on their magnetic connectivity and heavy ion abundances. The desirability of modelling the particle transport effects in detail and extending the analysis to cover higher energies is indicated.     

Catching spiral – S0 transition in groups. Insights from SPH simulations with chemo-photometric implementation

We are investigating the co-evolution of galaxies within groups combining multi-wavelength photometric and 2D kinematical observations. Here we focus on S0s showing star formation in ring/arm-like structures. We use smooth particle hydrodynamical simulations (SPH) with chemo-photometric implementation which provide dynamical and morphological information together with the spectral energy distribution (SED) at each evolutionary stage. As test cases, we simulate the evolution of two such S0s: NGC 1533 and NGC 3626.     

Galaxy evolution in groups. USGC U268 and USGC U376 in the Leo cloud

With the aim of investigating galaxy evolution in nearby galaxy groups, we analyzed the spectral energy distribution of 24 galaxies, members of two groups in the Leo cloud, USGC U268 and USGC U376. We estimated the ages and stellar masses of the galaxies by fitting their total apparent magnitudes from far-ultraviolet to near-infrared with population synthesis models. The comparison of the results for a subsample of galaxies with smooth particle hydrodynamic (SPH) simulations with chemo-photometric implementation, shows that in most cases the estimated stellar masses obtained with the two different approaches are in good agreement. The kinematical and dynamical analysis indicates that USGC U268 is in a pre-virial collapse phase while USGC U376 is likely in a more evolved phase towards virialization.     

Solar physics with the Square Kilometre Array

The Square Kilometre Array (SKA) will be the largest radio telescope ever built, aiming to provide collecting area larger than 1?km². The SKA will have two independent instruments, SKA-LOW comprising of dipoles organized as aperture arrays in Australia and SKA-MID comprising of dishes in South Africa. Currently the phase-1 of SKA, referred to as SKA1, is in its late design stage and construction is expected to start in 2020. Both SKA1-LOW (frequency range of 50–350?MHz) and SKA1-MID Bands 1, 2, and 5 (frequency ranges of 350–1050, 950–1760, and 4600–15,300?MHz, respectively) are important for solar observations. In this paper we present SKA’s unique capabilities in terms of spatial, spectral, and temporal resolution, as well as sensitivity and show that they have the potential to provide major new insights in solar physics topics of capital importance including (i) the structure and evolution of the solar corona, (ii) coronal heating, (iii) solar flare dynamics including particle acceleration and transport, (iv) the dynamics and structure of coronal mass ejections, and (v) the solar aspects of space weather. Observations of the Sun jointly with the new generation of ground-based and space-borne instruments promise unprecedented discoveries.     

Successes and challenges in non-destructive testing of aircraft composite structures

Composite materials are increasingly used in the aerospace industry. To fully realise the weight saving potential along with superior mechanical properties that composites offer in safety critical applications, reliable Non-Destructive Testing (NDT) methods are required to prevent catastrophic failures. This paper will review the state of the art in the field and point to highlight the success and challenges that different NDT methods are faced to evaluate the integrity of critical aerospace composites. The focus will be on advanced certificated NDT methods for damage detection and characterization in composite laminates for use in the aircraft primary and secondary structures.     

Nonthermal effects on the cylindrical dusty ion shocks in nonthermal viscous space plasma

The propagating cylindrical shock dust ion wave (CDISW) in dusty four component plasma with three viscous component (ion and two polarity charged grains) has been introduced. The three dimensional (3D) Cylindrical Burgers (CB) equation is derived. The propagating cylindrical shock characteristics are established to becomes a very significantly improved by the supports of electron nonthermality, ion and negative (positive) kinematics viscosity coefficients. Furthermore, the shock strength depends on cylindrical directions. The obtained results may be profitable in understanding both the laboratory and space applications of plasmas.