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151.
《中国航空学报》2020,33(11):2946-2958
An impact-time-control guidance law is required for the simultaneous attack of suicide attack unmanned aerial vehicles. Based on the nonlinear model, a two-phase guidance strategy is proposed. The impact time is derived in a simple analytical form of initial states and switching states, and it can be controlled by switching at an appropriate range. Firstly, a two-phase guidance law is designed to make the magnitude of the heading error decrease monotonically from its initial value to zero. And then, the feasible interval of the switching ranges and of the impact times under the acceleration constraint are given analytically in sequence. Furthermore, a general form of two-phase guidance law is proposed, which allows the magnitude of the heading error to increase in the first phase, to improve the applicability of the methodology. Having the same structure as proportional navigation guidance with a time-varying gain, the proposed algorithms are simple and easy to implement. The corresponding feedback form is presented for realistic implementation. When a predefined impact time is taken within its permissible set, the constraints on the acceleration and field-of-view will not be violated during the interception. Finally, simulations validate the effectiveness of the methodology in impact time control and salvo attack. 相似文献
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153.
An integrated cooperative guidance framework for multi-missile cooperatively attacking a single stationary target is proposed in this paper by combining both the centralized and decentralized communication topologies. Once missiles are distributed into several groups, missiles within a single group communicate with the centralized leader-follower framework, while the leaders from different groups communicate using the nearest-neighbor topology. To implement the integrated cooperative guidance framework, a group of Finite-Time Cooperative Guidance (FTCG) laws considering the saturation constraint on FOV (FTCG-FOV) are firstly derived within the centralized leader-follower framework to satisfy the communication topology of missiles in a single group. Then, an improved sequential approach is developed to adapt the FTCG-FOV to satisfy the communication topology between groups. The numerical simulations demonstrate the effectiveness and high efficiency of the integrated cooperative guidance framework and the cooperative guidance laws, as well as the superiority of the developed sequential approach. 相似文献
154.
Optimal guidance of extended trajectory shaping 总被引:3,自引:1,他引:2
To control missile's miss distance as well as terminal impact angle, by involving the timeto-go-nth power in the cost function, an extended optimal guidance law against a constant maneuvering target or a stationary target is proposed using the linear quadratic optimal control theory.An extended trajectory shaping guidance(ETSG) law is then proposed under the assumption that the missile-target relative velocity is constant and the line of sight angle is small. For a lag-free ETSG system, closed-form solutions for the missile's acceleration command are derived by the method of Schwartz inequality and linear simulations are performed to verify the closed-form results. Normalized adjoint systems for miss distance and terminal impact angle error are presented independently for stationary targets and constant maneuvering targets, respectively. Detailed discussions about the terminal misses and impact angle errors induced by terminal impact angle constraint, initial heading error, seeker zero position errors and target maneuvering, are performed. 相似文献
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157.
《中国航空学报》2020,33(12):3018-3026
The coupling region of a Hall thruster with a hollow cathode is the region between the cathode and the thruster plume. The characteristics of plasma in that region are complicated and strongly associated with the thruster working conditions and the cathode position. In this paper, a laboratory 100 W class magnetically shielded Hall thruster was coupled with a hollow cathode. Optical imaging and electrostatic probe were employed to monitor and scan the plasma plume. Plume characteristics in the coupling region in non-self-sustained mode and self-sustained mode were compared. Evolution of the coupling plume with the cathode position was studied. Experiments show that, when turning the thruster into self-sustained mode or moving the cathode further away axially, the discharge current can be reduced by 6.4–10.6% restraining the electron current and improving ionization. In particular, when the cathode is moved further, the electron conduction near the channel walls is suppressed. The electron current is reduced by 27.4% and the ion beam current is increased by 7%. Overall, this work shows that the working mode of the thruster and the position of the cathode greatly affect the coupling plasma plume. Both play an important role in improving the utilizations of propellant and current. 相似文献
158.
针对高超声速飞行器俯冲段精确打击任务需求,提出了一种能够同时满足落速与落角约束的轨迹规划方法。建立了两段式轨迹规划策略,第一段采用参数化控制剖面调节飞行速度,第二段采用传统偏置比例导引律实现落角控制。将控制剖面的参数设计分解为多参数优化与单参数搜索两个问题:通过离线求解可行初始位置范围最大的多参数优化问题,提高控制剖面对初始偏差的适应性;通过在线求解带罚函数的单参数搜索问题,得到落速偏差最小的俯冲轨迹。结合高超声速飞行器模型,对所提出的俯冲轨迹规划方法进行了仿真。结果表明,该方法能够得到满足落速与落角约束的俯冲轨迹,具有较好的求解效率,且对初始状态偏差具有较强的鲁棒性。 相似文献
159.
为提高反导任务执行效率,研究反导任务的总量模型和迭代收敛规律,利用任务转移矩阵定量描述反导任务之间的联系与作用强度.引入任务量完工比例参数表征协同反导特点,建立任务总量模型,揭示反导任务迭代收敛规律,深入探究影响收敛的主要因素.基于资源约束和时间优化的视角,确定任务关键度,规划任务优先级,优化资源配置,调控反导任务迭代收敛速度.结合实例验证了任务总量模型和迭代收敛规律是合理可行的,为计算和优化反导任务提供了理论依据和具体对策. 相似文献
160.
针对液压伺服系统常规"白箱"建模由于参数无法精确获得导致所得模型精度不高及"黑箱"建模所得模型内部结构未知的问题,本文提出基于ODE参数辨识的液压伺服系统"灰箱"建模。首先,建立了工程上实用的系统状态空间模型, 根据系统特征确定了待辨识参数,将模型辨识问题转化为常微分方程(ODE)参数辨识问题;然后,采用正弦扫频信号作为激励信号和基于带边界约束的信赖域优化算法的初值问题方法进行参数辨识;为了和ODE参数辨识结果进行对比,本文同时采用系统的频率响应数据和最小二乘法辨识得到系统的"黑箱"传递函数模型;最后,通过大量实验验证了辨识模型的精确度。实验结果表明,本文提出的基于信赖域算法的液压伺服系统模型辨识方法可以有效处理参数的边界问题,使辨识模型既具有实际的物理意义,又与实际系统高度符合。 相似文献