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排序方式: 共有1248条查询结果,搜索用时 109 毫秒
971.
Liang Zhang Shijie Xu Zhiping Zhang Naigang Cui 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(6):1968-1980
This paper is devoted to developing a closed-loop vibration suppression controller for a satellite with large flexible appendages based on component synthesis vibration suppression (CSVS) method. The dynamics model of a flexible satellite is firstly established by using the Newton–Euler methodology, and the dynamics model of the flywheel is also developed. A novel CSVS method is presented based on zero-vibration differentiator (ZVD), which can guarantee multi-order vibration suppression. Combined with the proposed CSVS method, traditional closed-loop controllers such as PD or sliding mode controllers can be applied to active vibration suppression. The stability of the proposed closed-loop CSVS controller is proved by the Lyapunov theory. Subsequently, the dynamic optimal control allocation algorithm is proposed for six flywheels, and a novel nonsingular fast terminal sliding mode controller is developed to obtain practical voltage control input for the flywheel drive control system. Finally, numerical simulations are carried out to validate the effectiveness of the proposed method. 相似文献
972.
布谷鸟搜索(CS)算法是一种新型的受自然现象启发的元启发式智能优化算法,其强大的全局搜索能力和收敛速度受到了广泛关注。多目标布谷鸟搜索(MOCS)算法是一种在单目标布谷鸟算法基础上发展的可以直接求解Pareto解集的多目标优化算法。针对原始MOCS算法的不足,采用一系列措施以提高算法的收敛精度、收敛速度以及解的均匀性:通过引入非支配排序与拥挤距离来改进解的适应度评估;通过改进随机游走策略来提高局部搜索能力;通过引入改进的自适应丢弃概率策略来提高算法的收敛速度;加入档案管理机制,提高解的均匀性。典型的多目标数值算例结果表明,改进的MOCS算法相较于当前主流的NSGA-Ⅱ算法拥有更快的收敛速度和更高的收敛精度。以RAE2822双目标升阻比优化设计为例,将改进的MOCS算法应用于多目标气动优化中,改进的MOCS算法共获得64个Pareto解,优化后的翼型气动性能有明显的提升,设计者可以根据自己的偏好选取不同的Pareto解。对于气动优化问题,改进的MOCS算法与目前主流的NSGA-Ⅱ相比,收敛速度更快。 相似文献
973.
Fractional order modeling and control of dissimilar redundant actuating system used in large passenger aircraft 总被引:1,自引:1,他引:0
In this paper, a methodology has been developed to address the issue of force fighting and to achieve precise position tracking of control surface driven by two dissimilar actuators. The nonlinear dynamics of both actuators are first approximated as fractional order models. Based on the identified models, three fractional order controllers are proposed for the whole system. Two Fractional Order PID (FOPID) controllers are dedicated to improving transient response and are designed in a position feedback configuration. In order to synchronize the actuator dynamics, a third fractional order PI controller is designed, which feeds the force compensation signal in position feedback loop of both actuators. Nelder-Mead (N-M) optimization technique is employed in order to optimally tune controller parameters based on the proposed performance criteria. To test the proposed controllers according to real flight condition, an external disturbance of higher amplitude that acts as airload is applied directly on the control surface. In addition, a disturbance signal function of system states is applied to check the robustness of proposed controller. Simulation results on nonlinear system model validated the performance of the proposed scheme as compared to optimal PID and high gain PID controllers. 相似文献
974.
研究了分数阶Hopfield型神经网络的全局渐近稳定性,通过LMI方法得到了一种实现系统全局渐近稳定性的LMI形式条件,通过实例仿真验证了结论的正确性。 相似文献
975.
传统最优控制航迹规划一般以逆风精确着陆、控制能量小为优化目标,但传统最优控制的操纵过程一般是一条连续变化的曲线,工程上不易实施;与之相比,传统分段航迹规划操纵简单,工程上容易实施,能实现逆风精确着陆的目标,但控制能耗大。为了兼顾逆风精确着陆、能耗低和控制操作简单等目标,提出了一种基于梯度下降法的翼伞最优分段航迹规划方法。该方法将控制变量参数化,将逆风精确着陆、控制能耗小、能实现避障等多目标优化问题转化为加权单目标优化问题,并通过梯度下降法求解得到分段常值最优归航航迹。所提算法与基于伪谱法的最优控制规划航迹和基于遗传算法的分段规划航迹进行了对比,算法仿真结果表明本文提出的最优分段航迹规划法既可以实现着陆精度高、控制能量小、逆风着陆和避障的优化目标,同时规划的航迹又由分段常值实现控制,工程上容易实施,兼顾了最优控制航迹规划和分段航迹规划的优点。 相似文献
976.
Kwangwon Lee Chandeok Park Sang-Young Park Daniel J. Scheeres 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
This study presents a semi-analytic approach for optimal tracking and formation keeping with high precision. For a continuous-thrust propulsion system, optimal formation keeping problems near a general Keplerian orbit are formulated with respect to a reference trajectory which is an explicit function of time. A nonlinear optimal tracking control law is then derived in generic form as a function of the states by employing generating functions in the theory of Hamiltonian systems. The applicability of the overall process is not affected by the complexity of dynamics and the selection of coordinates. As it allows us to design a nonlinear optimal feedback controller in the Earth-centered inertial frame, a variety of nonlinear perturbations can be incorporated easily without complicated coordinate transformations. Numerical experiments demonstrate that the nonlinear tracking control logic achieves superior tracking accuracy and cost reduction by accommodating higher-order nonlinearities. 相似文献
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