基于刷扫和研磨的复合式小行星取样器取样过程仿真与分析

针对小行星表面微重力环境及样品机械属性未知的特点,提出了一种基于刷扫和研磨的复合式取样器设计方案。该取样器通过刷扫和研磨的复合方式进行取样,能够提高小行星表面取样任务的成功率。为了研究该取样器刷扫取样时刷轮叶片数、刷轮转速、推进速度、星壤参数等对取样效率的影响,研磨和刷扫复合取样的优越性以及刷扫和研磨时的驱动力矩,开展了样品颗粒相互作用建模及研磨取样动力学分析。基于离散元仿真软件EDEM,构建了取样器3D模型并仿真其在小行星表面取样,获得了样品收集质量与取样时间的关系曲线,分析了各个参数对取样效率的影响。结果表明:刷轮叶片数越多,刷轮转速越大,推进速度越大,取样器取样效率更高,刷扫和研磨的复合取样方法比起单一的刷扫取样,具有更高的取样效率。该研究为设计小行星取样器、取样参数设定和取样效果分析提供了依据。     

The calculation of ionospheric absorption with modern computers

New outcomes are proposed for ionospheric absorption starting from the Appleton–Hartree formula, in its complete form. The range of applicability is discussed for the approximate formulae, which are usually employed in the calculation of non-deviative absorption coefficient. These results were achieved by performing a more refined approximation that is valid under quasi-longitudinal (QL) propagation conditions. The more refined QL approximation and the usually employed non-deviative absorption are compared with that derived from a complete formulation. Their expressions, nothing complicated, can usefully be implemented in a software program running on modern computers. Moreover, the importance of considering Booker’s rule is highlighted. A radio link of ground range D = 1000 km was also simulated using ray tracing for a sample daytime ionosphere. Finally, some estimations of the integrated absorption for the radio link considered are provided for different frequencies.     

运输机超低空空投下滑阶段PIO趋势评估与抑制

提出了超低空空投下滑阶段的PIO问题,研究了空投下滑拉平阶段产生PIO的主要原因.基于描述函数法分析了速率限制反馈(RLF) PIO抑制系统的相位补偿能力和PIO产生机理,推导了抑制PIO发生的计算公式.应用RLF连续信号相位补偿法抑制PIO的发生,对阶跃、离散和正弦三种易于诱发PIO现象的跟踪任务进行了数值仿真.结果表明,超低空空投下滑拉平阶段会发生PIO,严重威胁飞行安全,RLF对PIO具有较好的抑制效果.     

Evaluation of simulation-based training for aircraft carrier marshalling with learning cubic and Kirkpatrick’s models

Simulation-based training is a promising way to train a carrier flight deck crew because of the complex and dangerous working environment. Quantitative evaluation of simulation-based training quality is vital to make simulation-based training practical for aircraft carrier marshalling.This paper develops a personal computer-based aircraft carrier marshalling simulation system and a cave automatic virtual environment(CAVE)-based immersive environment. In order to compare the training effectiveness of simulation-based training and paper-based training, a learning cubic model is proposed and a contrast experiment is carried out as well. The experimental data is analyzed based on a simplified Kirkpatrick’s model. The results show that simulation-based training is better than paper-based training by 26.80% after three rounds of testing, which prove the effectiveness of simulation-based aircraft carrier marshalling training.     

基于模糊层次分析法的飞机空调系统健康管理

以飞机空调系统为研究对象,运用模糊层次分析法的思想,对飞机空调系统的六大子系统进行评估比较．得出其各自的权重,随后根据各子系统中关键部附件的使用寿命,计算出各自的寿命权重．最后运用模糊优先规划法、逼近于理想解法等方法对空调系统的各参数进行归纳整理,得出空调系统的健康状况。     

星载电子设备元器件随机振动疲劳分析

星载电子设备通常要经历各种振动环境,在恶劣的随机振动环境中,设备中的元器件管脚及焊点容易出现疲劳问题。文章应用Miner疲劳损伤累积理论及三带宽技术,提出了一种实用有效的分析元器件管脚及焊点进行随机振动疲劳寿命的方法。     

Exploring The Saturn System In The Thermal Infrared: The Composite Infrared Spectrometer

The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm^{− 1} (1 mm to 7μ m), with a spectral resolution that can be set from 0.5 to 15.5 cm^{− 1}. The far infrared portion of the spectrum (10–600 cm^{− 1}) is measured with a polarizing interferometer having thermopile detectors with a common 4-mrad field of view (FOV). The middle infrared portion is measured with a traditional Michelson interferometer having two focal planes (600–1100 cm^{− 1}, 1100–1400 cm^{− 1}). Each focal plane is composed of a 1× 10 array of HgCdTe detectors, each detector having a 0.3-mrad FOV. CIRS observations will provide three-dimensional maps of temperature, gas composition, and aerosols/condensates of the atmospheres of Titan and Saturn with good vertical and horizontal resolution, from deep in their tropospheres to high in their mesospheres. CIRS’s ability to observe atmospheres in the limb-viewing mode (in addition to nadir) offers the opportunity to provide accurate and highly resolved vertical profiles of these atmospheric variables. The ability to observe with high-spectral resolution should facilitate the identification of new constituents. CIRS will also map the thermal and compositional properties of the surfaces of Saturn’s icy satellites. It will similarly map Saturn’s rings, characterizing their dynamical and spatial structure and constraining theories of their formation and evolution. The combination of broad spectral range, programmable spectral resolution, the small detector fields of view, and an orbiting spacecraft platform will allow CIRS to observe the Saturnian system in the thermal infrared at a level of detail not previously achieved.This revised version was published online in July 2005 with a corrected cover date.     

航空发动机安全边界与“即用性”燃料认证方法

在航空替代燃料缺乏足够飞行数据,几乎不可能通过有限发动机和飞行实验来评价其安全特性状况下,研究开发了一种简便却可保证适航安全性的方法来研究航空替代燃料的安全性能.“即用性”航空替代燃料被认为是发动机更换最频繁的部件,从而采用相似类比、使用经验方法来验证“即用性”燃料的适航符合性.以航空煤油实际使用经验为基准,提炼燃料性能、燃料系统、燃烧性能、发动机性能、飞机性能5个层次上参数化描述的安全边界,与通过航空替代燃料在5个层次上得到的工作边界进行相似类比,从而预测发动机使用替代燃料的安全性.该方法提炼了替代燃料在发动机安全性上的判定准则,还降低了认证流程的燃料成本和时间成本.      

直升机机载设备国产化LRU互换性验证技术

针对型号研制中LRU级原位替换验证需求,结合试飞阶段工作实际,提出了LRU功能、物理、性能互换性三级流程;基于灰色关联理论对LRU互换性影响因素进行分析,建立了优先替换原则;基于置信度的数理分析,验证了替换充分性,并给出了具体互换性合格判据;最后,基于某型直升机试飞阶段国产化项目典型互换性验证实例,证明了各阶段方法的科学性、准确性及实用性。