空间机器人地面实验系统的一种鲁棒自适应控制方法

基于李亚普诺夫稳定性直接方法, 针对具有参数及模型不确定性的空间机器人地面实验系统, 提出了一种新的鲁棒自适应控制器。该控制器由三部分组成: 线性PD反馈项, 补偿动力学的自适应控制项, 补偿建模不确定性的鲁棒控制项。控制策略能有效地克服未建模的摩擦力和外部扰动以及吊丝配重系统未补偿掉的重力影响, 并且能保证全局最终一致有界。仿真表明了算法的可行性和有效性     

红外／紫外双色制导系统数学模型及数字仿真

介绍了便携式防空导弹双色导引头中所采用的数字式控制系统代替传统的模拟式控制系统的方法。对导引头和自动驾驶仪部分的数学模型作了简化，并作了全弹道数字仿真。仿真结果表明，该双色制导体系设计方便，抗干扰能力强等。     

GPS total electron content and surface latent heat flux variations before the 11 March 2011 M9.0 Sendai earthquake

The present paper describes the variations of the GPS total electron content (TEC) from the International GNSS service network and surface latent heat flux (SLHF) from the Scientific Computing Division of the National Center for Atmospheric Research (NCAR) before the 11 March 2011 M9.0 Sendai earthquake, respectively. The analysis shows pronounced enhancements in the GPS TEC and SLHF a few days prior to the earthquake event. The maximum increase in the GPS TEC was about 30 TECu with an extended spatial distribution on a geomagnetically quiet day (Dst ? −20 nT, between two moderate geomagnetic storms), 8 March, 3 days prior to the earthquake. This giant positive disturbance was possibly associated with the impending disastrous earthquake and contributed from the enhanced solar radiation. Moreover, there were several anomalous regions of SLHF on the global map, but an area of enhanced SLHF very close to the epicenter. The purpose of this paper is to report the existence of the changes in surface and ionosphere, and show the potential application of multi-source data to identify seismic precursors.     

Surface shape control of integrated paraboloid space reflector consisting of sub-reflectors exploiting modulated solar pressure

Reflectors are very critical space elements and can be used not only as solar collectors/reflectors, telecommunication radio antennas and telescopes but also for dual-usage such as solar sails and solar concentrators to probe and sublimate materials from asteroids when actively controlling the surface shape. In this paper, the surface shape of a slack reflector with negligible elastic deformations will be controlled to be a paraboloid by actively modulating the solar radiation pressure (SRP) force using reflectivity control devices (RCDs) across the reflector. Nonlinear static equilibrium equations for an arbitrary infinitesimal within the reflector along the radial, circumferential and transverse directions are established considering the external modulated SRP force and internal tensions respectively. The coupled radial stress differential governing equation and reflectivity algebraic equation are obtained for the paraboloid reflector by the help of the formulation of an inverse problem based on equilibrium equations previously established. Some analytical and numerical analysis for reflectors with ideal and non-perfect SRP force models are performed respectively. The conclusions concerning about how to control the reflector’s surface shape successfully using allowed reflectivity, resulting in reasonable stress range, moreover, how to get the feasible solutions influenced by the reflector’s size parameters, are all based on the presented analytical and numerical analysis.     

Anomalous enhancement of electric field derived from ionosonde data before the great Wenchuan earthquake

The seismo-ionospheric coupling is a hot topic of modern scientific research. One of the most reasonable mechanisms is the hypothesis of quasistatic electric field. With a preliminary analytical method, electric field in F2-region before Wenchuan earthquake was derived from the five lower latitude ground-based ionosondes: Lhasa (29.63°N, 91.17°E), Chongqing (29.50°N, 106.40°E), Kunming (25.00°N, 102.70°E), Guangzhou (23.15°N, 113.35°E) and Haikou (23.15°N, 110.35°E). The results show that there was an anomalous enhancement of electric field in F2-region close to the epicenter with maximal amplitude ∼2 mV/m (about 10 times of the background) at 15:00 LT on 9 May, which is in line with the amplitudes of anomalous electric field related to some previous earthquakes observed by satellites.     

铝合金高速微小孔钻削工艺

铝合金微小孔钻削加工及其工艺难点 铝合金是以铝为主的合金总称,通过添加铜、硅、镁、锌、锰以及镍、铁、钛、铬、锂等合金元素,在保持纯铝质轻等优点的同时,其"比强度"可胜过很多合金钢,成为理想的结构材料,广泛用于机械制造、运输机械、动力机械及航空工业等方面.飞机的机身、蒙皮、压气机等常用铝合金制造,以减轻自重.     

一种实现实时多任务操作机制的方法

介绍一种实现实时多任务操作机制的方法和两个实例，这种方法可以用于嵌入式系统中。     

Mutations in cauliflower and sprout broccoli grown from seeds flown in space

Cauliflower and sprout broccoli are widely planted vegetables particularly in Fujian Province, China. To study the mutation in these two types of vegetables induced from spaceflight, we flew the seeds on the 20th Chinese recoverable satellite which orbited the Earth for 18 days. After returning to the Earth, the cauliflower seeds were planted for two generations and the sprout broccoli seeds for one generation at the Xiamen Agriculture Research Institute. Of the 12 cauliflowers planted for the first generation, two showed significant phenotypical changes in both the size of the plant and the weight of the flower head. In addition, most of the space flown plants were found to be resistant to the black rot attack in the field. Cauliflowers planted for the second generation from the seeds in one of the two plants that displayed phenotypical changes in the first generation showed similar mutations. For the first generation of sprout broccoli, the rate of emergence from the flown seeds was lower than that of the control by 30%. No significant changes in the phenotype between the sprout broccolis planted from the flown seeds and the control were observed except one of the mutated sprout broccolis showed a change in the appearance in the lesser bud of the chief flower head. Results of the study demonstrated that DNA damages in some of the genes may have occurred in the seeds flown in space, and some of the changes in the genes may have inherited from the first to the second generation. The improved resistance to the black rot attack and increased size of the flower head are apparently beneficial.     

整体叶盘片光饰抛光试验及发展应用探析

介绍了整体叶盘叶片利用机械光饰机进行的抛光试验,根据叶片试验取得的数据,分析了该种加工方法所具有的特点,以及应用时应采取的一些措施,为该种方法的应用提供了一定的借鉴经验.