空间双组元发动机离心式喷注器的喷注流场诊断技术研究

对空间双组元发动机核心部件喷注器的喷雾流场可视化诊断技术开展了研究,有效识别了传统分析手段难以发现的雾化场缺陷,对发动机工作特性进行早期诊断,实现故障预防和设计优化.离心式喷注器的雾化喷注流场包含了大量的数据信息,可以通过高速摄影和图像分析进行数据挖掘分析.通过均值图像和余弦相似性计算对喷注流场的空间分布结构进行诊断,...     

管理学的两难境地与出路

管理学从它延生之时起就步入了“科学”的误区,出现脱离管理实践的趋向。经过近百年的发展,既不能得到管理理论工作者的热爱,又不能得到管理实践工作者的广泛认同与实际应用,步入了进退两难的尴尬境地。管理学要走出两难困境,必须重新审视管理学的学科性质。作者认为管理学是一种实践理论而不是一种科学理论。就其学科性质而言,是一门实践性学科。     

Space very long baseline interferometry in China

Space very long baseline interferometry (VLBI) has unique applications in high-resolution imaging of the fine structure of astronomical objects and high-precision astrometry due to the key long space–Earth or space–space baselines beyond the Earth’s diameter. China has been actively involved in the development of space VLBI in recent years. This review briefly summarizes China’s research progress in space VLBI and the future development plan.     

Development of secondary flow field under rotating condition in a straight channel with square cross-section

The developing secondary flow fields in the entrance section of a rotating straight channel were experimentally investigated using Particle Image Velocimetry (PIV). The effects of streamwise position, Reynolds number and rotation number on the development of the secondary flow fields were revealed. The results show that the absolute values of vorticity flux of the trailing side roll cells increase with increasing radius of the measured plane and rotation number. When the absolute value of vorticity flux exceeds a critical value, the merging of the trailing side roll cells appears. Moreover, when the number of the trailing side vortex pairs is even, the absolute values of vorticity flux of the leading side vortices increase along streamwise direction. Otherwise, the absolute values decrease along the streamwise direction. By the circulation analysis, this phenomenon was found to have relationship with the merging of the trailing side roll cells, and further concluded that the secondary flow field in a rotating channel has to be treated as a whole. At last, the increase of the Reynolds number was found to be able to induce the merging position moves upstream.     

视场角受限的三维攻击角度控制导引律

考虑末制导阶段捷联导引头视场角限制及攻击角度约束,提出一种基于三维比例导引攻击角度控制的导引律。首先,利用三维矢量制导模型和四元数理论实现三维比例导引的攻击角度预测,进而基于空间几何原理设计一种能够满足视场角约束的三维比例导引攻击角度控制方法。对闭环制导动力学进行分析,并采用李雅普诺夫原理证明视场角受限情况下的制导误差收敛性。分析该制导方法在导弹速度大小变化情况下的轨迹不变性,进而保证制导方法在速度大小变化情况下的有效性。理论分析和仿真校验结果说明了该方法的正确性和有效性。提出的方法可为视场角受限下的攻击角度控制导引律设计提供参考。     

Use of coated silicon field emitters as neutralisers for fundamental physics space missions

Spacecraft neutralisers are required as part of the ion propulsion system for accurate station keeping in fundamental physics missions. This paper describes the use of thin layers of insulating materials as coatings for the gated silicon field emitter array structure used in a spacecraft neutraliser. These thin coatings are postulated to reduce power consumption and reduce overheating. The power consumption and lifetime of aluminium nitride and amorphous hydrogenated diamond-like carbon coatings have been tested by current–voltage and endurance tests. Diamond-like carbon coatings were promising, performing better in endurance tests than uncoated samples, but further work is required to characterise the coating’s physical properties and its effects on field emission. The thermal conductivity of the coating material had little effect on measured sample lifetimes. Aluminium nitride had reduced power consumption compared to diamond-like carbon coated and uncoated samples. A thin (∼5 nm) layer of aluminium nitride was found to be optimal, meeting European Space Agency specifications for the neutraliser engineering model.     

威海天文台1米望远镜天体测量试验

利用威海天文台1米望远镜观测了2009年10月7日晚的疏散星团M39.观测过程中使用了I滤光片,并将CCD绕光轴旋转90°分别成像.使用最新的UCAC3星表和Platais的自行星表归算表明,该望远镜具有良好的天体测量性能,最好的单次位置测量精度达到了4～5 milli-arcsec.此外,观测资料还发现UCAC3星表具有明显的自行不准确性,证实了文献[14]的最新发现.     

THE SPACE APPLICATION ACHIEVEMENTS OF THE CHINESE UNMANNED SPACECRAFT "SZ-3"

During the 3rd mission of Chinese Unmanned Spacecraft the application sys tem of "SZ-3" (Shenzhou, a divine ship) gets a great success, all its goals are achieved. Many areas of science and breakthrough technology, including earth observation, earth environment monitoring, space material, space life science etc., are carried out in the mission. There are 44 payload instruments totally.All the instruments are working well during the orbit flight and a lot of good results are obtained. Many areas, for example the moderate resolution imag ing spectroradiometer, the solar ultraviolet spectral irradiance monitor and the space protein crystallization facility perform better than required and expected.A brief introduction of the experiments and the achievements of the mission is given in this paper.     

概念汽车与汽车设计的发展和创新

本文从概念汽车设计中的文化和科的角度，论述了概念汽车的设计对汽车工业发展的影响和作用。