全文获取类型
收费全文 | 114篇 |
免费 | 18篇 |
国内免费 | 31篇 |
专业分类
航空 | 86篇 |
航天技术 | 34篇 |
综合类 | 14篇 |
航天 | 29篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 8篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有163条查询结果,搜索用时 15 毫秒
41.
丛伟 《沈阳航空工业学院学报》2000,17(1):54-56
本文通过截线扫描法构造B-Spline曲面,介绍了扫描面的特性,并结合具体实例说明该方法在造型设计中的应用价值。 相似文献
42.
为节省样板制造、更改依据保存及样板实物长期保存和维护带来的高额费用,实现装配夹具的全面数字化管理,迫切需要完成样板装配夹具数字化.以波音747口框装配夹具为例,给出了已有工具球孔但无孔位数据的定位器数字化改造方法以及无工具球孔的定位器数字化改造方法;创新运用功能性测量和实测反推理论值的方法,给出了整套夹具各个定位器的理论工具球数值.装配夹具的数字化改造精简掉工装定检和维修过程中样板的借用和搬运,尤其适用于样板尺寸大、不易搬运和使用不便的样板装配夹具,缩短了工装定检和维修周期,节省了成本,提高了经济效率. 相似文献
43.
驾驶员模型建模精度分析方法研究 总被引:1,自引:0,他引:1
针对频域内驾驶员描述函数和辨识方法和最小二乘的驾驶员模型参数的估计方法,按照严谨公式的规范条件建立了驾驶员模型建模精度评介公式,并对驾驶员完成俯仰跟踪任务时的仿真结果和驾驶员模型辨识结果进行了精度检验计算,同时还探讨了提高建模精度的有关技术问题。 相似文献
44.
多变量线性系统的特征模型及控制方法 总被引:6,自引:0,他引:6
对多输入 -多输出高阶线性定常系统从理论上详细推导出了其特征模型 ,并给出了基于特征模型的自适应模糊广义预测控制方案。所建立的特征模型为智能控制器设计和一些高阶对象的低阶控制器设计提供了理论依据 ,特别是为大型空间挠性航天器的控制提供了一种有效的途径。通过对一个航天器控制的仿真研究验证了所给方法的有效性 相似文献
45.
多变量线性时变系统的特征模型及自适应模糊控制方法 总被引:1,自引:0,他引:1
对于阶数及参数未知的高阶系统,如何设计一个工程上易于实现的低阶控制器,以实现有效的高性能控制,这是目前航天等领域亟待解决的问题。该文采用将对象特征和控制性能要求相结合的方法,对多输入一多输出高阶线性时变系统和一类非线性时变系统从理论上详细推导出了其特征模型,在此基础上设计了基于特征模型的稳定的自适应模糊广义预测控制方案。由于控制结构中使用了分层模糊系统,从而减少了模糊规则数目。通过对一个挠性航天器控制的仿真实验验证了所给方法的有效性。 相似文献
46.
47.
E. Kallio P. Janhunen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,33(12):2176-2181
The interaction between the solar wind and Mercury is anticipated to be unique because of Mercury’s relatively weak intrinsic magnetic field and tenuous neutral exosphere. In this paper the role of the IMF in determining the structure of the Hermean magnetosphere is studied using a new self-consistent three-dimensional quasi-neutral hybrid model. A comparison between a pure northward and southward IMF shows that the general morphology of the magnetic field, the position and shape of the bow shock and the magnetopause as well as the density and velocity of the solar wind in the magnetosheath and in the magnetosphere are quite similar in these two IMF situations. A Parker spiral IMF case, instead, produces a magnetosphere with a substantial north–south asymmetric plasma and magnetic field configuration. In general, this study illustrates quantitatively the role of IMF when the solar wind interacts with a weakly magnetised planetary body. 相似文献
48.
49.
The very high accuracy of the Doppler and range measurements between the two low-flying and co-orbiting spacecraft of the
GRACE mission, which will be at the μm/sec and ≈10 μm levels respectively, requires that special procedures be applied in
the processing of these data. Parts of the existing orbit determination and gravity field parameters retrieval methods and
software must be modified in order to fully benefit from the capabilities of this mission. This is being done in the following
areas: (i) numerical integration of the equations of motion (summed form, accuracy of the predictor-corrector loop, Encke's
formulation): (ii) special inter-satellite dynamical parameterization for very short arcs; (iii) accurate solution of large
least-squares problems (normal equations vs. orthogonal decomposition of observation equations); (iv) handling the observation
equations with high accuracy. Theoretical concepts and first tests of some of the newly implemented algorithms are presented.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
50.
Reduction in clamping force due to applied longitudinal load to aerospace structural bolted plates 总被引:1,自引:0,他引:1
The main purpose of the present work is to experimentally and numerically study why and how the magnitude of the bolt clamping force reduces in the aerospace structural bolted plates when they are subjected to a longitudinal tensile load. In the experimental method, a holed plate of aluminium alloy 7075-T6 was clamped using a single bolt fastener, and then tested under an increasing static longitudinal tensile load. The bolt clamping magnitude was determined by using the measured axial compressive strains of a steel bush placed between the nut and plate. Two clamped specimens with different initial clamping forces were studied. In each specimen the actual clamping forces were determined during the longitudinal loading on the plate. In the numerical method, a three-dimensional (3D) finite element model was generated in order to simulate and quantify the bolt clamping force in the plate model loaded in tension. Both experimental and numerical results showed that the clamping force reduces considerably in the aluminium bolted plates under the longitudinal tensile loading. This is because of the transverse contraction of the plate material that causes the clamped material to release from the initial compression, and as a result, the clamping force to relax. 相似文献