【摘 要】
：
The optimal yawing angle of sun-tracking solar aircraft is tightly related to the solar azi-muth angle,which results in a large arc flight path to dynamically track the sun position.However,the limited detection range of payload usually requires solar air
【机 构】
：
School of Mechanical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China;S
论文部分内容阅读
The optimal yawing angle of sun-tracking solar aircraft is tightly related to the solar azi-muth angle,which results in a large arc flight path to dynamically track the sun position.However,the limited detection range of payload usually requires solar aircraft to loiter over areas of interest for persistent surveillance missions.The large arc sun-tracking flight may cause the target area on the ground to be outside the maximum coverage area of payload.The present study therefore devel-ops an optimal flight control approach for planning the flight path of sun-tracking solar aircraft within a mission region.The proposed method enables sun-tracking solar aircraft to maintain the optimal yawing angle most of the time during daylight flight,except when the aircraft reverses its direction by turning flight.For a circular region with a mission radius of 50 km,the optimal flight trajectory and controls of an example A-shaped sun-tracking solar aircraft are investigated theoretically.Results demonstrate the effectiveness of the proposed approach to optimize the flight path of the sun-tracking aircraft under the given circular region while maximizing the battery input power.Furthermore,the effects of varying the mission radius on energy performance are explored numerically.It has been proved that both net energy and energy balance remain nearly constant as the radius constraint varies,which enables the solar aircraft to achieve perpetual flight at almost the same latitude as the large arc flight.The method and results presented in this paper can provide ref-erence for the persistent operation of sun-tracking solar aircraft within specific mission areas.
其他文献
In this paper fretting fatigue crack behavior in 1045 steel is studied by in-situ observation and finite element analysis,in-situ fretting fatigue experiments are conducted to capture real-time fretting fatigue crack formation and propagation process.The
Reasonable and effective fatigue load spectrum is key of aircraft structural fatigue test.Two kinds of load spectra simplification approaches based on statistical consistent fatigue damage model are proposed in the paper.One method is to simplify the orig
The multiple jets impingement heat transfer is widely applied in the wing anti-icing sys-tem.It is challenging to apply the similarity criterion to carry out the anti-icing experiments due to the complex flow and heat transfer behavior.In the present stud
Research on the transition phase of tail-sitter Unmanned Aerial Vehicles (UAVs) is cru-cial for trajectory planning and performance analysis.This study focuses on the analysis of the tran-sition characteristics and path of a small dual-rotor tail-sitter U
This paper addresses the robust attitude control problem for quadrotors subject to model mismatch and disturbances.A dynamic inversion based attitude control scheme is proposed,which consists of an outer loop attitude controller and an inner loop angular
An efficient method was proposed to prepare high-performance conductive Aramid-Carbon Blend Fabrics (ACBF) with cobalt-nickel (Co-Ni) alloy coatings,which is conducive to industrial production.The grid-like substrate composed of aramid and carbon fibers w
This paper reports an experimental study on the supersonic jet surface flow structure visualization and shear stress field measurement issuing from a rectangular nozzle with extended shelf.The evolution of the near-field surface flow structures with an in
文章以周宁抽水蓄能电站为例,进行了其引水隧洞充排水试验方案设计、试验过程及试验结果的分析探讨,结果表明,充排水试验是水电站引水隧洞工程施工质量检测及查找引水系统可能存在安全隐患的主要方式,在抽水蓄能电站投产发电前,其引水发电系统充排水试验必不可少。试验结果显示,该抽水蓄能电站引水系统设计合理,施工质量良好,结构性能可靠,且所采取的充排水试验程序合理,措施得当,充排水试验取得了成功。
文章从方法、原理及其应用效果的角度全面研究了锚杆质量无损检测技术,利用波形特征与锚杆注浆密实度之间的关系总结出注浆密实度、有效锚固长度、缺陷的位置及大小等锚杆施工质量问题评价方法,为工程质量评价和检测提供一种有效的无损检测技术。
规模性节水灌溉工程是影响降低我国农业水资源损耗、提高水资源利用率的重要水利工程,同时对区域水土保持工作尤其是地下水位也带来重要的影响。文章将根据新疆某片区大规模、广域型节水工程灌溉项目实例,基于数值分析预测模型,展开了节水灌溉工程对区域地下水位变化规律影响的研究,为区域水土保持工作提供指导。研究发现:①相对于土渠,混凝土节水衬砌渠道具有良好的防渗漏性能,相等水位水力作用下,30d内混凝土渠水的渗透距离仅达到土渠的7.84%,能够起到降低水资源耗费的结果;②数值分析预测模型应用模拟得出水流渗透深度呈指数型增