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231.
为根据飞机高/低速风洞测压试验数据给出飞机的机翼,机身和尾翼的气动载荷分布,供外载荷计算使用,介绍了一种基于测压风洞试验的大展弦比飞机气动载荷分布计算方法。通过将测压试验数据插值到载荷计算模型网格中,并将测压试验数据与测力试验数据相协调,再对压力分布数据进行切面/纵向积分、样条插值和线性化拟合后,对飞机活动面中立、偏襟翼、偏副翼、偏方向舵和偏升降舵状态时的机身、短舱、机翼及翼身组合体气动载荷分布进行了计算。总结了各剖面区域表面压力随迎角,侧滑角,以及飞机舵面变化的规律,验证了测压数据与测力数据进行协调的必要性。对飞机气动载荷的设计优化有重要的反馈评估作用。 相似文献
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《中国航空学报》2023,36(4):338-353
Reinforcement Learning (RL) techniques are being studied to solve the Demand and Capacity Balancing (DCB) problems to fully exploit their computational performance. A locally generalised Multi-Agent Reinforcement Learning (MARL) for real-world DCB problems is proposed. The proposed method can deploy trained agents directly to unseen scenarios in a specific Air Traffic Flow Management (ATFM) region to quickly obtain a satisfactory solution. In this method, agents of all flights in a scenario form a multi-agent decision-making system based on partial observation. The trained agent with the customised neural network can be deployed directly on the corresponding flight, allowing it to solve the DCB problem jointly. A cooperation coefficient is introduced in the reward function, which is used to adjust the agent’s cooperation preference in a multi-agent system, thereby controlling the distribution of flight delay time allocation. A multi-iteration mechanism is designed for the DCB decision-making framework to deal with problems arising from non-stationarity in MARL and to ensure that all hotspots are eliminated. Experiments based on large-scale high-complexity real-world scenarios are conducted to verify the effectiveness and efficiency of the method. From a statistical point of view, it is proven that the proposed method is generalised within the scope of the flights and sectors of interest, and its optimisation performance outperforms the standard computer-assisted slot allocation and state-of-the-art RL-based DCB methods. The sensitivity analysis preliminarily reveals the effect of the cooperation coefficient on delay time allocation. 相似文献
234.
《中国航空学报》2020,33(8):2242-2256
In cabin-type component alignment, digital measurement technology is usually adopted to provide guidance for assembly. Depending on the system of measurement, the alignment process can be divided into measurement-assisted assembly (MAA) and force-driven assembly. In MAA, relative pose between components is directly measured to guide assembly, while in force-driven assembly, only contact state can be recognized according to measured six-dimensional force and torque (6D F/T) and the process is completed based on preset assembly strategy. Aiming to improve the efficiency of force-driven cabin-type component alignment, this paper proposed a heuristic alignment method based on multi-source data fusion. In this method, measured 6D F/T, pose data and geometric information of components are fused to calculate the relative pose between components and guide the movement of pose adjustment platform. Among these data types, pose data and measured 6D F/T are combined as data set. To collect the data sets needed for data fusion, dynamic gravity compensation method and hybrid motion control method are designed. Then the relative pose calculation method is elaborated, which transforms collected data sets into discrete geometric elements and calculates the relative poses based on the geometric information of components. Finally, experiments are conducted in simulation environment and the results show that the proposed alignment method is feasible and effective. 相似文献
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Jinhui Huang Wenxiang Liu Yingxue Su Feixue Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(3):811-822
Space networks, in which connectivity is deterministic and intermittent, can be modeled by delay/disruption tolerant networks. In space delay/disruption tolerant networks, a packet is usually transmitted from the source node to the destination node indirectly via a series of relay nodes. If anyone of the nodes in the path becomes congested, the packet will be dropped due to buffer overflow. One of the main reasons behind congestion is the unbalanced network traffic distribution. We propose a load balancing strategy which takes the congestion status of both the local node and relay nodes into account. The congestion status, together with the end-to-end delay, is used in the routing selection. A lookup-table enhancement is also proposed. The off-line computation and the on-line adjustment are combined together to make a more precise estimate of the end-to-end delay while at the same time reducing the onboard computation. Simulation results show that the proposed strategy helps to distribute network traffic more evenly and therefore reduces the packet drop ratio. In addition, the average delay is also decreased in most cases. The lookup-table enhancement provides a compromise between the need for better communication performance and the desire for less onboard computation. 相似文献
239.
简述了模糊可靠性理论、有关定义并探讨了理论在结构强度设计中的应用方法,最后以航天器复合材料舱段结构为例,把蒙特卡罗法和模糊可靠性理论结合起来,进行模糊随机可靠性分析和计算。 相似文献
240.
以某型飞行器为例,运用气动参数建模分析的手段,建立典型空气动力学模型。将传统的模型辨识方法与现代计算机技术相结合,对气动力辨识输入参数进行了分析,采用迭代算法得出辨识参数,并对观测量和物理几何参数误差影响辨识精度进行了分析,选用某型飞行器现有试验测量数据作为输入量,进行气动参数辨识,将辨识得到的气动参数进行了仿真验证。利用辨识得到的气动参数仿真计算的弹道与试验结果吻合度较高,说明气动参数辨识可行。 相似文献