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1.
Differential game formulations provide an adequate basis for a guidance law synthesis against highly maneuvering targets. This paper deals with a guidance law based on a linear-quadratic differential game formulation. This guidance law has many attractive properties: it is continuous, linear with respect to the state variables, and its gain coefficients can be precalculated offline. Nevertheless, due to the lack of hard control constraints in the formulation, the magnitude of the control can exceed the admissible level imposed by the nature of the problem. In this paper, the upper bound of the interceptor control is obtained depending on the system parameters and the penalty coefficients of the game performance index. It is shown that the interceptor can guarantee an arbitrarily small miss distance without exceeding the control constraints if it has sufficient maneuverability and if the penalty coefficients are chosen properly. By manipulating the penalty coefficients, it is possible to reduce significantly the maneuverability requirements compared to the case of zero interceptor penalty coefficient. 相似文献
2.
储能器是一种储存能量的装置,随着高温超导悬浮轴承运用到飞轮储能器中,储能效率得到了大大的提高。它的主要结构是由高温超导体和永磁体组成。文中提出一种全新高温超导悬浮轴承,并研究其的力学性能,为新型超导悬浮轴承的研究与开发做好了基础准备。 相似文献
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This study evaluated the performance of in-vitro freehand aspiration of a simulated cyst with ultrasound aspiration guided by a newly designed laser assisted (LA) device. The LA device was equipped with an adjustable light source generating a sector light plane. This laser light plane was parallel to and overlapped the ultrasound acoustical plane, to help with needle positioning. Five operators randomly performed 30 freehand or LA ultrasound guided aspirations of a simulated cyst. The frequency was set at 8 MHz and depth at 4 cm. Procedure time and number of syringe withdrawals were statistically compared before and after using the LA device. Both experienced and inexperienced operators required significantly less time to perform the aspiration and had fewer syringe withdrawals when using the LA device. The LA device provides a reference plane in space, allowing the operator to more accurately position and adjust needle direction. Additional in-vivo testing is required to test the clinical practicability. 相似文献
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结合2015-2016年新情况,概述近期高分子学科新动态,给出年度基金申请指南,指出基金申请中存在的一些问题. 相似文献
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概述了近期高分子科学前沿问题以及最新研究进展,对今后高分子科学的发展进行展望,介绍了2012年国家自然科学基金化学科学部高分子科学学科基金申请指南和申请注意事项等。 相似文献
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An active flow control experiment was conducted on a cropped NACA 0018 airfoil to study 3D effects and maneuverability aspects
made possible by a segmented actuation system installed in the airfoil. The 14 piezo-fluidic actuators were installed at the
corner of the cropped region, inclined at 30° to the local surface, facing downstream. Operating all actuators at unison significantly
increased lift and generated a pitch-down moment. Operating all actuators at the same magnitude but varying the phase along
the span generated larger lift-increment, with respect to the uniform phase excitation. Significant rolling moment can be
generated when only half-span of the wing is actuated. The latter effect, as indicated by the 3D pressure distribution, persists
to the leading edge even though the excitation was introduced close to the trailing edge. When a pair, out of the possible
fourteen actuators is not operating, very little of the control authority is lost. This is an important finding when issues like fault tolerance and robustness
of fluidic-piezo actuators are considered. 相似文献
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本文对目标拦截的导引方法进行了研究和模拟,是项目“军事指挥实时动态真实感模拟系统RDMSS”的目标拦截模拟部分,主要内容是:对导弹的导引弹道进行了分析和模拟,并提出用样条预测的新方法进行目标导引;给出了模拟爆炸和火焰喷射的简易方法;最后在SGI/Indigo2上实现了一个简单的仿真模拟系统,对飞机的飞行、导弹及反导弹的发射和拦截过程作了成功的模拟,取得了良好的效果. 相似文献
10.
A. Miele M. Ciarcià M. W. Weeks 《Journal of Optimization Theory and Applications》2007,132(3):377-400
In a previous paper of Miele et al. (J. Optim. Theory Appl. 132(1), 2007), we employed the single-subarc sequential gradient-restoration algorithm to optimize the three-dimensional rendezvous between
a target spacecraft in a planar circular orbit and a chaser spacecraft with an initial separation distance and separation
velocity. The achieved continuous solutions are characterized by two, three, or four subarcs depending on the performance
index (time, fuel) and the constraints. In this paper, based on the solutions in Miele et al. (J. Optim. Theory Appl. 132(1), 2007), we employ the multiple-subarc sequential gradient-restoration algorithm to produce pieced guidance trajectories implementable
in real time via constant control components. In other words, in this investigation, we force the controls to behave as parameters
in each subarc. With the above understanding, we investigate four problems: (P1) minimum time, fuel free; (P2) minimum fuel,
time free; (P3) minimum time, fuel given; (P4) minimum fuel, time given.
Problem P1 results in a two-subarc solution, each subarc with constant controls: a max-thrust accelerating subarc followed
by a max-thrust braking subarc. Problem P2 results in a four-subarc solution, each subarc with constant controls: an initial
coasting subarc, followed by a max-thrust braking subarc, followed by another coasting subarc, followed by another max-thrust
braking subarc. Problems P3 and P4 result in two, three, or four-subarc solutions depending on the performance index and the
constraints, albeit with constant controls in each subarc.
For each of the problems studied, the performance index of the multiple-subarc pieced guidance trajectory approximates well
the performance index of the single-subarc continuous optimal trajectory of Miele et al. (J. Optim. Theory Appl. 132(1), 2007) as well as the performance index of the multiple-subarc pieced optimal trajectory: the pairwise relative differences in
performance index are less than 1/100.
This research was supported by NSF under Grant CMS-0218878. 相似文献