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动力增程型高超声速飞行器的再入轨迹规划 被引量:5
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作者 冯玥 王容顺 +2 位作者 梅映雪 孙洪飞 吴了泥 《北京航空航天大学学报》 EI CAS CSCD 北大核心 2020年第8期1503-1513,共11页
为研究飞行过程中的动力装置启动时刻及燃料消耗情况,对轨迹进行优化,进而提出一种动力增程型弹道的再入模式。推导Sanger弹道的解析解,分析得到高超声速飞行器再入航程最优所必须的迎角及初始速度取值条件等相关前提,利用该结论设计动... 为研究飞行过程中的动力装置启动时刻及燃料消耗情况,对轨迹进行优化,进而提出一种动力增程型弹道的再入模式。推导Sanger弹道的解析解,分析得到高超声速飞行器再入航程最优所必须的迎角及初始速度取值条件等相关前提,利用该结论设计动力装置的启动方式使航程最远、燃料利用率最大。将轨迹设计为Sanger弹道和拟平衡滑翔弹道相结合的混合弹道:再入前期利用助推器间隔点火的方式形成等高类周期跳跃弹道以保证足够远的航程;再入后期采用拟平衡滑翔弹道,将最优控制问题转化为复杂多约束非线性规划问题,性能指标综合考虑了轨迹平滑和航程。仿真实现了所提出的动力增程型再入弹道;并在燃料充足、弹道倾角取值合适的条件下,得到"打水漂"弹道形式,该弹道能量损失极慢,具有足够远的飞行能力。仿真表明,与不同点火方式及求解方法得出的弹道相对比,所提动力增程型再入弹道具有3.47~3.84倍的航程、1.04~1.18倍的末端动能以及4.47~15.79倍的燃料利用率。 展开更多
关键词 高超声速飞行器 助推器 动力增程 再入返回 解析解 “打水漂”弹道 轨迹规划
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What Life Is and How It Originated
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作者 William Day 《Journal of Philosophy Study》 2013年第10期895-904,共10页
This paper refutes the mechanistic interpretation of cellular dynamics and contends that the life-giving principle is sustained growth a biological system and is uninterrupted growth balanced in a dynamic state by syn... This paper refutes the mechanistic interpretation of cellular dynamics and contends that the life-giving principle is sustained growth a biological system and is uninterrupted growth balanced in a dynamic state by synthesis and dissolution. The process began by an oxidation/reduction reaction on the surface of pyrite energized photovoltaically by sunlight. Hydrogen sulfide was oxidized, carbon dioxide was reduced, and phosphate on the surface of the pyrite was a reactant. The first organic compounds were sulfides and phosphoglycerates. These organophosphates were at the center of the energy cycle of all life where the dehydration of a relatively unreactive "low-energy" two-phosphoglycerate transforms it into the "high-energy" phosphoenolpyruvate. Life began as a growth process and continues to grow ceaselessly out of necessity. It cannot discontinue the life-giving energy flow without irreparable loss of the process. All forms of life past and present were and are stabilized systems in which the growth process is contained in metabolic turnover. 展开更多
关键词 origin of life life principle metabolic turnover
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Extracting predictable components and forecasting techniques in extended-range numerical weather prediction 被引量:1
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作者 WANG QiGuang CHOU JiFan FENG GuoLin 《Science China Earth Sciences》 SCIE EI CAS 2014年第7期1525-1537,共13页
This paper refers to the CNOP-related algorithms and formulates the practical method and forecast techniques of extracting predictable components in a numerical model for predictable components on extended-range scale... This paper refers to the CNOP-related algorithms and formulates the practical method and forecast techniques of extracting predictable components in a numerical model for predictable components on extended-range scales.Model variables are divided into predictable components and unpredictable chaotic components from the angle of model prediction error growth.The predictable components are defined as those with a slow error growth at a given range.A targeted numerical model for predictable components is established based on the operational dynamical extended-range forecast(DERF)model of the National Climate Center.At the same time,useful information in historical data are combined to find the fields for predictable components in the numerical model that are similar to those for the predictable components in historical data,reducing the variable dimensions in a similar judgment process and further correcting prediction errors of predictable components.Historical data is used to obtain the expected value and variance of the chaotic components through the ensemble forecast method.The numerical experiment results show that this method can effectively improve the forecast skill of the atmospheric circulation field in the 10–30 days extended-range numerical model and has good prospects for operational applications. 展开更多
关键词 extended-range forecast predictable components chaotic components analogue correction of errors fast non-adjointalgorithm
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Lift enhancement method by synthetic jet circulation control 被引量:9
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作者 ZHANG PanFeng YAN Bo DAI ChenFeng 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第9期2585-2592,共8页
A novel circulation control technique is proposed to overcome the shortcomings of blowing jet circulation control, which uses the synthetic jet as the actuator and avoids the limitation about air supply requirement. T... A novel circulation control technique is proposed to overcome the shortcomings of blowing jet circulation control, which uses the synthetic jet as the actuator and avoids the limitation about air supply requirement. The effectiveness of synthetic jet circulation control to enhance lift of NCCR1510-7067N airfoil is confirmed by solving the 2-D unsteady Reynolds-averaged Na- vier-Stokes equations. The aerodynamic characteristics and the flow structure (especially close to the trailing edge) of NCCR 1510-7067N airfoil at zero angle of attack are also presented to discuss the mechanism of lift enhancement of the airfoil with synthetic jet circulation control. The results indicate that the synthetic jet can effectively delay the separation point on the airfoil trailing edge and increase the circulation and lift of the airfoil by Coanda effect. The numerical simulation results demonstrate that the lift augmentation efficiency with synthetic jet circulation control reaches △C1/Cμ,=114 in the present study, which is much higher than the value 12.1 in the case with steady blowing jet circulation control. 展开更多
关键词 synthetic jet circulation control numerical simulation lift enhancement
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