球齿轮传动齿廓接触特性分析

 对球齿轮齿廓进行了接触特性研究。在建立了球齿轮齿廓曲面方程和啮合模型基础上,利用计算机仿真的方法对其进行了齿面接触分析研究。针对球齿轮啮合传动时接触形式表现为轮齿凸面与马鞍面之间的点接触,对啮合齿面的接触椭圆进行了分析计算,确定了接触椭圆的方向和尺寸,得到了球齿轮机构在任一偏摆平面内啮合传动时接触椭圆的变化规律：在轮齿根部和顶部啮合时,接触椭圆较小,因而接触应力较大;而在轮齿中部啮合时,接触椭圆较大,所以接触应力较小。上述结论对进一步研究球齿轮的传动理论与实际应用具有重要的指导意义。     

基于二元信道互信息的属性约简方法及其应用

由于知识的粗糙性和信息熵的密切关系,基于互信息的属性约简一直以来都是粗糙集研究的热点,但现有方法都不同程度地依赖于属性值的分布情况,从而影响最终约简结果.为解决此问题,从信息论的角度对属性进行细分,定义了一种新的基于二元信道互信息的属性重要度度量方法,以此为启发式信息构造新的约简算法,实验证明了该算法的有效性;将其应用于重要气象因子的提取,获得了满意的效果.     

Phobos regolith simulants PGI-1 and PCA-1

The Martian moon Phobos is the target of the upcoming JAXA Martian Moons eXploration (MMX) mission. There are currently no known samples of Phobos, so spacecraft hardware testing and scientific studies require Phobos regolith simulants. Here, we present two new Phobos regolith simulants: Phobos Captured Asteroid-1 (PCA-1) and Phobos Giant Impact (PGI-1). These two simulants reflect the two hypotheses for Phobos’s formation, and thus the two broad possibilities for composition. This work follows previous efforts to document the development of mineralogically accurate simulants, in an effort to overcome past pitfalls with inappropriate uses of simulants. We report physical and geotechnical properties of PCA-1 and PGI-1, including their reflectance spectra, grain size distributions, abrasivity, cohesion, strength, and hardness. Our intent is for PCA-1 and PGI-1 to be open standards for Phobos simulants, and we present the simulant recipes and production methodology for use and modification by the community.     

Loopy belief propagation based data association for extended target tracking

The data association problem of multiple extended target tracking is very challenging because each target may generate multiple measurements. Recently, the belief propagation based multiple target tracking algorithms with high efficiency have been a research focus. Different from the belief propagation based Extended Target tracking based on Belief Propagation (ET-BP) algorithm proposed in our previous work, a new graphical model formulation of data association for multiple extended target tracking is proposed in this paper. The proposed formulation can be solved by the Loopy Belief Propagation (LBP) algorithm. Furthermore, the simplified measurement set in the ET-BP algorithm is modified to improve tracking accuracy. Finally, experiment results show that the proposed algorithm has better performance than the ET-BP and joint probabilistic data association based on the simplified measurement set algorithms in terms of accuracy and efficiency. Additionally, the convergence of the proposed algorithm is verified in the simulations.     

基于边缘计算和VPRS的火箭设备单机双层判读与实时诊断

为提高参数自动判读的效率，增强设备单机状态诊断的时效性和准确性，提出一种基于边缘计算和变精度粗糙集(VPRS)的运载火箭设备单机双层判读与实时诊断方法。首先构建了边缘层-判读服务器层的双层判读架构。然后，基于边缘计算技术设计了边缘层判读方法，对参数原始数据进行阈值判断与数据筛选。随后，在判读服务器层，定义AIPL(AutoIP Language)判据描述语言设计高阶判据并进行高阶判读；基于VPRS建立了实时诊断模型，对设备单机的历史数据进行约简，挖掘出了简化后的状态诊断规则。最后，以XX火箭设备单机遥测数据自动判读系统升级改造为例，验证了所提方法的可行性与有效性。     

Optimum design and experiment of composite leaf spring landing gear for electric aircraft

The composite leaf spring landing gear of an electric aircraft is optimized. With the strength and workability as constraints and the minimum structural weight as an objective, the two-stage optimization of the leaf spring landing gear with glass fiber unidirectional prepreg is carried out using a genetic algorithm, namely, the optimization of continuous thickness of layup, and the optimization of the layup sequence and discrete thickness. In the optimization process, the ground loads are calculated according to the structural stiffness of each chromosome, thus the stiffness constraints are relaxed, and the optimization results are compared with those using stiffness constraints. The static experiment verification reveals that the numerical simulation and experimental results are consistent, that is, the optimized leaf spring meets the strength requirements. The results show that the leaf spring landing gear based on two-stage optimization method achieves the objective of weight reduction.     

Longitudinal MLT wind structure at higher mid-latitudes as seen by meteor radars at central and Eastern Europe (13°E/49°E)

The mid-latitude mesosphere and lower thermosphere (MLT) wind speeds measured by two SKiYMET meteor radars (MRs) at Collm (51°N, 13°E) and Kazan (56°N, 49°E) during 2016–2017 were analyzed to study longitudinal wind structures. The differences between monthly mean prevailing wind speeds and tidal amplitudes were compared with the corresponding differences obtained from TIMED/TIDI satellite winds and gradient wind speeds from the AURA/MLS instrument. It is shown that the MR wind difference between the two sites is statistically significant. The difference of the horizontal prevailing winds can be explained by a superposition of the background zonal flow, which is different at the two latitudes, with stationary planetary waves of different origin. Non-migrating tides contribute significantly to the difference of the semidiurnal tidal winds between the two sites.     

中子星性质的模型依赖性

采用相对论平均场理论（RMFT）下的GL85,GL92,TM1和TM2等核物质参数组,研究了这些参数组对中子星的粒子数密度分布、状态方程及质量-半径关系的影响.结果表明,在不同的参数组下,超子出现的密度、顺序和种类均不同;状态方程的软硬情况也较大不同;中子星的引力质量和相应的半径有明显不同.计算结果也表明,采用GL85,TM1和TM2等参数组得到的中子星质量和半径均在脉冲星的观测数据范围内,而采用GL92参数组得到的中子星质量小于中子星质量下限1.4M⊙（M⊙=1.99×1030kg为太阳质量）.     

某无人机起落架缓冲器防卡滞优化设计

以某无人机起落架为研究对象,基于经典卡滞分析理论,建立了起落架卡滞特性分析数学模型,并分析了在不同地面载荷工况下的卡滞特性,发现在右转弯工况下临界摩擦系数小于0.1,存在卡滞隐患.进而以存在卡滞隐患的右转弯工况为例,开展了缓冲器上下支承初始间距、轮轴半轴长和扭力臂位置角对卡滞特性的参数影响研究,并在此基础上进行了针对该工况的起落架结构参数优化设计,通过优化设计,可使起落架减重6％左右.     

Glacier mapping based on rough set theory in the Manas River watershed

Precise glacier information is important for assessing climate change in remote mountain areas. To obtain more accurate glacier mapping, rough set theory, which can deal with vague and uncertainty information, was introduced to obtain optimal knowledge rules for glacier mapping. Optical images, thermal infrared band data, texture information and morphometric parameters were combined to build a decision table used in our proposed rough set theory method. After discretizing the real value attributes, decision rules were calculated through the decision rule generation algorithm for glacier mapping. A decision classifier based on the generated rules classified the multispectral image into glacier and non-glacier areas. The result of maximum likelihood classification (MLC) was used to compare with the result of the classification based on the rough set theory. Confusion matrix and visual interpretation were used to evaluate the overall accuracy of the results of the two methods. The accuracies of the rough set method and maximum likelihood classification were compared, yielding overall accuracies of 94.15% and 93.88%, respectively. It showed the area difference based on rough set was smaller by comparing the glacier areas of the rough set method and MLC with visual interpreter, respectively. The high accuracy for glacier mapping and the small area difference for glacier based on rough set theory demonstrated that this method was effective and promising for glacier mapping.