排序方式: 共有34条查询结果,搜索用时 15 毫秒
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采用均衡分析方法,说明了美国的钢铁保护关税行为对贸易双方社会福利产生的影响,自由贸易才能使世界福利极大化,而保护性的贸易政策只会使世界总福利水平降低。 相似文献
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采用本地轨道从标系对两邻飞船间相对运动动力学展开研究,指出在相对运动中也存在平衡状态,用相平面方法分析了其稳定性,基于此分析,综合出相对运动控制方法,即距离速率控制方法,受控运动轨迹是一条稳定的稳态直线,进而建立了全方位距离速率控制方法。最后以系绳卫星系统和飞船安全为例完成了计算机模拟。 相似文献
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平流层气球轨迹控制系统平衡点估算研究 总被引:2,自引:0,他引:2
简单介绍了平流层气球的特点和研究现状,引出并描述了轨迹控制系统,它几乎无需消耗能源,使长耗时平流层平台成为可能。提出了平流层气球轨迹控制飞行系统的仿真模型,并分别从风速轮廓线、大气密度以及气球、绳和集成翼方面逐一详细分析并进行建模,最后分析了整个飞行系统的特点和求解系统平衡点的难点所在,提出了一种可行的平衡点估算方法。结果表明,该平衡点估算方法可以快速有效地求得整个飞行系统的平衡点。 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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V.V. Lyahov V.M. Neshchadim 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
This paper offers a model of the magnetopause based on the theory of the contact discontinuity; the boundary layer between the two states of space plasma. The structure of the magnetopause is explored for the effects of polarization, and the profiles of the polarizing electrostatic field are obtained. 相似文献
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V.V. Lyahov V.M. Neshchadim 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
In this paper, we prove the necessity of using the Cauchy problem, i.e., initial value problem, for solving the equilibrium (steady state) current sheet. In this connection, it appears that equilibrium current sheaths exhibit structural instability. 相似文献
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The inter-satellite electromagnetic force presents several significant advantages that help to expand its space applications to the multi-satellite missions gradually. For a satellite swarm, whether the electromagnetic force is applied to enable collective maneuver and how to provide a better performance and broader applications for such swarm highlight an important issue. Considering the trajectory planning problem of satellite swarm using inter-satellite electromagnetic force, a behavior-based collective planning scheme is developed by designing the desired velocity of each satellite as the sum of several different behavioral contributions, which are used to represent the internal and external interactions of the swarm. Therefore, the desired configuration is associated with the equilibrium points of the pre-designed kinematical field. Furthermore, the trajectory planning problem could be translated to a parameter optimization problem considering the swarm dynamics with inter-satellite electromagnetic force. Then based on the analysis of the applicability and advantages triggered by integrating the inter-satellite electromagnetic force into such behavior-based planning scheme, the collective trajectory planning problem with sole electromagnetic force actuation and hybrid actuation with thruster are studied respectively. Numerical simulations are carried out to verify the validity of the proposed algorithm, and the satellite swarm performance enhanced by inter-satellite electromagnetic force is discussed at last. 相似文献
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基于过程神经网络的热平衡温度预测研究 总被引:3,自引:0,他引:3
为缩短航天器热平衡试验周期,以降低航天器研制成本,提出了一种基于过程神经网络的热平衡温度预测模型。为简化该模型的学习过程,提出了一种基于正交基函数展开的基本学习算法,利用基函数的正交性不仅可以简化模型中的时间累积运算过程,而且能提高模型对解决实际问题的适应性。同时,为增强模型的外推预测能力,在基本学习算法的基础上给出了一种基于新增样本的学习算法,使模型既能对新增样本进行快速学习又不损失对原有样本的记忆。实际应用表明,该预测模型能够利用某型号卫星热平衡试验中某监测点进入稳定工况后40小时内的试验数据提前42.5—68小时获得该监测点的极限热平衡温度。 相似文献