全文获取类型
收费全文 | 59篇 |
免费 | 10篇 |
国内免费 | 100篇 |
专业分类
航空 | 107篇 |
航天技术 | 17篇 |
综合类 | 12篇 |
航天 | 33篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 7篇 |
2016年 | 15篇 |
2015年 | 19篇 |
2014年 | 5篇 |
2013年 | 28篇 |
2012年 | 1篇 |
2010年 | 6篇 |
2009年 | 1篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 1篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1990年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 828 毫秒
41.
This article proposes a linear parameter varying (LPV) switching tracking control scheme for a flexible air-breathing hypersonic vehicle (FAHV). First, a polytopic LPV model is constructed to represent the complex nonlinear longitudinal model of the FAHV by using Jacobian linearization and tensor-product (T-P) model transformation approach. Second, for less conservative controller design purpose, the flight envelope is divided into four sub-regions and a non-fragile LPV controller is designed for each parameter sub-region. These non-fragile LPV controllers are then switched in order to guarantee the closed-loop FAHV system to be asymptotically stable and satisfy a specified performance criterion. The desired non-fragile LPV switching controller is found by solving a convex constraint problem which can be efficiently solved using available linear matrix inequality (LMI) techniques, and robust stability analysis of the closed-loop FAHV system is verified based on multiple Lypapunov functions (MLFs). Finally, numerical simulations have demonstrated the effectiveness of the proposed approach. 相似文献
42.
星载多光谱遥感器太阳定标技术的进展 总被引:1,自引:0,他引:1
顾名澧 《中国空间科学技术》2002,22(2):35-43
星载多光谱遥感器的太阳定标器一般选择太阳作为基准光源 ,通过它将太阳辐射引入星载遥感器并调节到星载遥感器的动态范围内 ,对星载遥感器进行绝对辐射定标 ,也可对星载遥感器性能变化进行监测和校正。文章介绍一些最具代表性的星载多光谱遥感器的太阳定标器 ,并进行了分析 ,以反映太阳定标技术的现状与发展。目前采用太阳漫射器的星上定标方法可以实现全视场、全孔径、端点到端点的定标。这一方法的严重缺点是漫射器反射比随时间变化。为了解决这一问题 ,设计一种比辐射计或反射比标定装置来监测漫射器的辐亮度、反射比以及太阳常数。因此这种定标方法是很有前途的 ,在现代一些先进的星载多光谱遥感器上获得应用。通过对此方法的分析 ,提出了在太阳漫射器研制中的一些关键技术。 相似文献
43.
SU Xiang-dong WANG Tian-min HAO Wei-chang HE Li 《中国航空学报》2006,19(B12):113-118
The corrosion behavior of the nitinol alloy was studied in various corrosion media of different Cl^- ion concentrations. The results demonstrate that the Cl^- ion concentration has significant influences on the corrosion behavior of the nitinol alloy. In order to enhance the corrosion resistance, protective films were generated on the surface of the nitinol alloy by means of the electrochemical passivation method, for which five different electrolytic solutions were investigated. The surface analysis indicates full growth of all samples passivated in the different electrolytic solutions with layers, however, showing different morphological features. Without any defects like micro-cracks and pores, the surface of the samples passivated in the molybdate solution turns out smoother and denser than those passivated in other solutions. It is shown that the electro-chemical passivation will reduce Ni content but increase Ti content in the surface, reaching the Mole ratio of Ti:Ni = 9.01:1 on the outermost surface. Potentiodynamic polarization test demonstrates that the samples electrochemically passivated in the molybdate solution present a significant increase in breakdown potential due to titanium enrichment on the outermost surface. 相似文献
44.
Residual Strength of Stiffened LY12CZ Aluminum Alloy Panels with Widespread Fatigue Damage 总被引:2,自引:0,他引:2
Li Zhong Ge Sen Lu Guozhi Chen Li Ding Huiliang 《中国航空学报》2008,21(1):48-52
Experimental and analytical investigations on the residual strength of the stiffened LY12CZ aluminum alloy panels with widespread fatigue damage (WFD) are conducted. Nine stiffened LY12CZ aluminum alloy panels with three different types of damage are tested for residual strength. Each specimen is pre-cracked at rivet holes by saw cuts and subjected to a monotonically increasing tensile load until failure is occurred and the failure load is recorded. The stress intensity factors at the tips of the lead crack and the adjacent WFD cracks of the stiffened aluminum alloy panels are calculated by compounding approach and finite element method (FEM) respectively. The residual strength of the stiffened panels with WFD is evaluated by the engineering method with plastic zone linkup criterion and the FEM with apparent fracture toughness criterion respectively. The predicted residual strength agrees well with the experiment results. It indicates that in engineering practice these methods can be used for residual strength evaluation with the acceptable accuracy. It can be seen from this research that WFD can significantly reduce the residual strength and the critical crack length of the stiffened panels with WFD. The effect of WFD crack length on residual strength is also studied. 相似文献
45.
针对飞机空调车维修周期长与继电保护状态不易判断等问题,本文采用嵌入式USB主机技术,为飞机空调车提供了方便快捷的继电保护状态数据采集存储途径,并为控制系统控制策略的发展和完善提供了客观充足的数据依据。在飞机空调车运行实验过程中,该数据采集系统运行稳定,数据记录完整、准确。离线数据分析过程中,数据曲线能较好地反映飞机空调车的继电保护状态判断状况。实践证明,在飞机空调车中引入USB主机技术对继电保护状态进行实时数据采集是可行的。 相似文献
46.
James Glimm Department of Applied Mathematics Statistics University at Stony Brook Stony Brook USA NY Center for Data Intensive Computing Brookhaven National Laboratory Upton USA NY Li Xiaolin Liu Yingjie 《南京航空航天大学学报(英文版)》2001,18(Z1)
INTRODUCTIONWe propose and demonstrate a tracking fi-nite difference algorithm which is( a) fully con-servative and ( b) improves local truncation errorby one order( from O( 1 ) to O( Δx) near trackeddiscontinuities.Discontinuities in the solutions of systems ofnonlinear hyperbolic conservation laws are widelyrecognized as a primary difficulty for numericalsimulation.Surprisingly,the nonlinearities actu-ally help,as they cause information,which flowsalong solution characteristics,to flow… 相似文献
47.
EFFECTOFHEATTREATMENTONINTERMEDIATETEMPERATURESTRESSRUPTUREPROPERTIESOFALLOYK403ZhengYunrong,LiShuyuan,MaShuwei(BeijingInstit... 相似文献
48.
LI Yinghui LI Weigang DING Bai WU Dawei LIU Zhaoxia HE Li ZHOU Wanlong XU Zi 《空间科学学报》2018,38(5):814-819
The development of Chinese manned space engineering has a great role in promoting the progress of Chinese space medicine. With the accelerated implementation of Chinese Space Station Program, China's space medicine has made fruitful achievements over the past three years. This report summarizes the major progress of Chinese space medicine in terms of basic research and space applications from 2016 to 2018. 相似文献
49.
A new water-cooling Gardon-type heat power measuring apparatus is designed to meet the need of heat power source management and distribution. The steady state measurement mathematic model of the apparatus is built up in theory and the system amplification coefficient is defined as the ratio of the heat power to the temperature difference of the device, with which the value of the measured source power can be calculated easily with the corresponding temperature difference. In order to obtain an optimal heat power measuring system, the coefficients that can influence the relationship between the amplification coefficient, the temperature difference, and the heat power are analyzed. On the basis of these analyses, a set of experimental device is constructed and a number of experiments are carried on. Compared with the input heat power sample data, the error of the experimental measuring results is less than ±2%, and the experimental measuring values are in good agreement with the calculated theoretical ones. The heat power measuring apparatus can be applied in heat flux or heat power measurement in other fields due to its simple structure and high accuracy. 相似文献
50.