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81.
针对微小卫星姿态控制中存在的多重指向约束和角速率约束问题,提出一种基于对数型势函数的多约束姿态机动规划方法。首先针对微小卫星携带的光学传感器需躲避强光天体而天线需指向地面保证对地通信这一约束特性,采用对数型势函数方法保证约束姿态指向满足任务要求;其次,针对姿态角速率限制的问题,引入障碍Lyapunov函数确保姿态角速率始终处于约束范围内。与在线优化方法相比,该方法具有计算量小的显著优势,非常适合星上处理能力有限的微小卫星。此外,考虑外界干扰力矩的影响,引入自适应干扰估计律,增强了控制系统的鲁棒性。最后,通过数学仿真对本文方法进行了校验,仿真结果表明,该方法能够快速实现卫星姿态机动到期望指向,与此同时,在整个姿态机动过程中,均满足多重指向约束和姿态角速率约束 要求 。 相似文献
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Robust H∞ controller design for attitude stabilization of flexible spacecraft with input constraints
Chuang Liu Keke Shi Zhaowei Sun 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(5):1498-1522
This paper addresses the attitude stabilization and vibration suppression problem for flexible spacecraft subject to model parameter uncertainty, controller perturbations, external disturbances and input constraints. The attitude model of flexible spacecraft is described and converted into a state space form in terms of passive and active vibration suppression schemes. A novel state feedback controller is proposed based on the exactly available expectation of a new variable, which is introduced to model a randomly occurring controller gain perturbation. Based on Lyapunov stability theory, sufficient conditions for the existence of the nonfragile H∞ controller considering input constraints are given based on linear matrix inequalities (LMIs) in terms of additive perturbation and multiplicative perturbation. Then, the developed controller subject to required constraints can be obtained, where the nonfragile property is fully considered to improve the tolerance to uncertainties in the controller. Numerical simulations are performed to demonstrate the effectiveness and superiority of the proposed control strategy in attitude stabilization and vibration suppression, where it should be noted that the passive vibration suppression scheme is superior for high natural frequencies while the active vibration suppression scheme is superior for low natural frequencies. Moreover, the low natural frequencies have more influence on the performance of attitude stabilization and vibration suppression. 相似文献
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Qiaoyun Fan Xuyang Zhong 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(4):1132-1142
A novel autonomous star identification algorithm is presented in this study. In the proposed algorithm, each sensor star constructs multi-triangle with its bright neighbor stars and obtains its candidates by triangle voting process, in which the triangle is considered as the basic voting element. In order to accelerate the speed of this algorithm and reduce the required memory for star database, feature extraction is carried out to reduce the dimension of triangles and each triangle is described by its base and height. During the identification period, the voting scheme based on double feature constraints is proposed to implement triangle voting. This scheme guarantees that only the catalog star satisfying two features can vote for the sensor star, which improves the robustness towards false stars. The simulation and real star image test demonstrate that compared with the other two algorithms, the proposed algorithm is more robust towards position noise, magnitude noise and false stars. 相似文献
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T.C. Slaba S.R. Blattnig M.S. Clowdsley S.A. Walker F.F. Badavi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
Long-term human presence in space requires the inclusion of radiation constraints in mission planning and the design of shielding materials, structures and vehicles. It is necessary to expose the numerical tools commonly used in radiation analyses to extensive verification, validation and uncertainty quantification. In this paper, the numerical error associated with energy discretization in HZETRN is addressed. An inadequate numerical integration scheme in the transport algorithm is shown to produce large errors in the low energy portion of the neutron and light ion fluence spectra. It is further shown that the errors result from the narrow energy domain of the neutron elastic cross section spectral distributions and that an extremely fine energy grid is required to resolve the problem under the current formulation. Since adding a sufficient number of energy points will render the code computationally inefficient, we revisit the light ion and neutron transport theory developed for HZETRN and focus on neutron elastic interactions. Two numerical methods (average value and collocation) are developed to provide adequate resolution in the energy domain and more accurately resolve the neutron elastic interactions. An energy grid convergence study is conducted to demonstrate the improved stability of the new methods. Based on the results of the convergence study and the ease of implementation, the average value method with a 100 point energy grid is found to be suitable for future use in HZETRN. 相似文献
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对颤振主动抑制控制律的优化设计进行了研究,提出了一种基于“极点配置”思想,考虑低速稳定性的工程性控制律初值设置方法;在优化过程中,除考虑阵风响应等约束外,还考虑了鲁棒性问题。以某型收音机的动力相似模型为实例进行计算。计算结果表明,设计的优化控制律能有效抑制颤振,保证低速稳定性,且系统满足工程稳定裕度要求。 相似文献
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针对面对称中高升阻比飞行器再入攻角的优化问题,从工程角度系统分析了升力再入攻角优化问题的多种约束,基于平衡滑翔条件结合失速攻角、初始再入攻角和平衡滑翔攻角等,得到了再入段飞行的攻角设计空间,并给出了再入攻角剖面设计的具体可行方法。所提出的设计方案可用于快速选定满足各种过程约束的速度-攻角剖面;将该攻角设计方法应用于覆盖区优化问题,在继承已有方法的快速求解速度下,仿真结果及对比表明所规划的攻角剖面具有与直接法相似的最优性。 相似文献
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翼肋主要作用是维持机翼外形,对于机翼的总弯曲刚度贡献较小,但是翼肋的重量却在翼盒的结构重量中占有相当大的比例(一般为8%~12%),因此有必要通过一定的结构优化方法减轻翼肋的结构重量。在MSC.PATRAN平台上二次开发了应力约束全局化的拓扑优化方法,并首次将该方法应用于翼肋的拓扑优化;采用了一套工程估算方法,可用于翼肋的初步设计和快速重量估算。结果表明:在满足稳定性要求的情况下,经过拓扑优化的翼肋结构减重效果明显。 相似文献