八工位聚氨酯注塑回转自动生产线回转盘系统结构设计

本文介绍了八工位聚氨酯注塑回转自动生产线中回转盘系统的总体设计思路及各部件的结构设计，该系统具有运行平稳，定位准确和制造简单的特点。     

我国电子商务应用技术与发展战略

简述了我国电子商务应用技术的选择和发展电子商务的战略，提出发展我国电子商务应注意的问题。     

4D Lattice Flower Constellations

4D Lattice Flower Constellations is a new constellation design framework, based on the previous 2D and 3D Lattice theories of Flower Constellations, that focus on the generation of constellations whose satellites can have different semi-major axis and still present a constellation structure that is maintained during the dynamic of the system. This situation can arise when dealing with satellites with very different instruments, or when it is of interest to coordinate two different constellations. In that sense, 4D Lattice Flower Constellations constitutes the most general representation of the Flower Constellation formulation. In addition, the effects of the $J_2$ perturbation are taken into account in order to generate distributions that maintain their initial design configuration under this perturbation for longer periods of time with a low fuel budget. Finally, examples of application are presented, showing the possibilities in satellite constellation design of this new approach.     

Automatic detection of typical dust devils from Mars landscape images

This paper presents an improved algorithm for automatic detection of Martian dust devils that successfully extracts tiny bright dust devils and obscured large dust devils from two subtracted landscape images. These dust devils are frequently observed using visible cameras onboard landers or rovers. Nevertheless, previous research on automated detection of dust devils has not focused on these common types of dust devils, but on dust devils that appear on images to be irregularly bright and large. In this study, we detect these common dust devils automatically using two kinds of parameter sets for thresholding when binarizing subtracted images. We automatically extract dust devils from 266 images taken by the Spirit rover to evaluate our algorithm. Taking dust devils detected by visual inspection to be ground truth, the precision, recall and F-measure values are 0.77, 0.86, and 0.81, respectively.     

The bistatic radar capabilities of the Medicina radiotelescopes in space debris detection and tracking

An accurate measurement of the position and trajectory of the space debris fragments is of primary importance for the characterization of the orbital debris environment. The Medicina Radioastronomical Station is a radio observation facility that is here proposed as receiving part of a ground-based space surveillance system for detecting and tracking space debris at different orbital regions (from Low Earth Orbits up to Geostationary Earth Orbits). The proposed system consists of two bistatic radars formed by the existing Medicina receiving antennas coupled with appropriate transmitters. This paper focuses on the current features and future technical development of the receiving part of the observational setup. Outlines of possible transmitting systems will also be given together with the evaluation of the observation strategies achievable with the proposed facilities.     

高温合金小孔钻削攻丝加工的方法

高温合金材料的小孔加工,特别是孔径尺寸上下偏差差值小的孔及小螺纹的加工,保证一次加工合格率较为困难,本文结合实际加工的某零件,从高温合金的切削特点、加工技法等方面进行探讨,详细叙述小孔钻削、攻丝加工的经验和方法,通过方法改进,高效高质完成产品的高精度尺寸要求.     

关于PA-34飞机空中最小操纵速度的试验研究

主要介绍空中最小操纵速度,并以PA-34飞机的一次飞行试验为例,对空中最小操纵速度试飞的试验目标、试验方法和条件以及试验结果进行了论述。从飞机实际操作影响、FAA适航条款(14CFR23部)[1]等方面对该飞机的空中最小操纵速度试验结果进行了分析和讨论。试验表明,PA-34飞机的空中最小操纵速度满足FAA适航条款要求,飞机向好发动机方向适度倾斜会减小最小操纵速度。     

双模式化学推进技术发展研究

阐述了卫星双模式推进系统的技术特征、工作原理及应用优势。总结了国内外对双模式推进技术研究的历史发展和研究现状,针对双模式推进系统的未来发展,对双模式推进的关键技术进行了总结和分析,说明了双模式推进技术研究的必要性和重要性。提出了我国双模式推进系统相关的发展策略和途径。在此基础上,根据我国已有的航天器单、双组元推进技术基础和航天任务对寿命、控制精度及工作环境提出了新的要求,并指出了发展双模式推进系统的初步设想。     

Automated techniques for the analysis of magnetic field inversion in filaments with the Solar Feature Catalogue

We present an automated comparison of magnetic field inversion line maps from SOHO/MDI magnetograms with solar filament data from the Solar Feature Catalogue created as part of the European Grid of Solar Observations project. The Euclidean distance transform and connected component labelling are used to identify nearest neighbour filament skeletons and inversion lines. Several filament-inversion line characteristics are defined and used to automate the decision whether a particular filament/inversion line pair is suitable for quantitative comparison of orientation and separation. The technique is tested on a total of 207 filaments from four H_α images, and the distributions of angles and distances between filament skeletons and LOS magnetic inversion lines are presented for six degrees of magnetic field smoothing. The results show the approach is robust and can be applied for a statistical analysis of magnetic field in filaments.     

复合材料自动铺带技术研究(Ⅱ)——柱面上沿"自然路径"铺带的压辊坐标生成

根据可展曲面上“自然路径”与测地线等价原理,应用沿弧长展开方法,研究了柱面上“自然路径”轨迹生成、铺带头轨迹坐标和姿态坐标计算模型与方法,讨论了简单边界的处理原则与方法,为实现柱面自动铺带CAD/CAM提供了依据。