Study on the resolution of multi-aircraft flight conflicts based on an IDQN

With the rapid growth of flight flow, the workload of controllers is increasing daily, and handling flight conflicts is the main workload. Therefore, it is necessary to provide more efficient conflict resolution decision-making support for controllers. Due to the limitations of existing methods, they have not been widely used. In this paper, a Deep Reinforcement Learning(DRL) algorithm is proposed to resolve multi-aircraft flight conflict with high solving efficiency. First, the characteristics ...     

Pattern control for large-scale spacecraft swarms in elliptic orbits via density fields

Space swarms, enabled by the miniaturization of spacecraft, have the potential capability to lower costs, increase efficiencies, and broaden the horizons of space missions. The formation control problem of large-scale spacecraft swarms flying around an elliptic orbit is considered. The objective is to drive the entire formation to produce a specified spatial pattern. The relative motion between agents becomes complicated as the number of agents increases. Hence, a density-based method is adopted...     

分布式卫星系统(DSS)及其自主控制技术分析

DSS系统本身的复杂性以及工作环境的不确定性 ,导致利用传统的控制方法对其进行控制十分困难。本文对DSS及其自主控制技术进行了分析。首先介绍了DSS的概念、结构及其支撑技术 ;其次阐述了卫星自主运行的研究进展 ,解析了空间飞行器RemoteAgent智能自主控制系统的基本构成 ;然后介绍了DSS自主运行技术的研究现状 ;接下来重点分析了基于multi -agent的DSS自主控制涉及的关键技术及面临的挑战 ;最后进行了总结     

Electrical discharge and arc milling with automatic tracking of optimal flushing direction: A novel high-efficiency compound machining method

The arc milling method has the advantages of high machining efficiency and low cost and is independent of the strength and hardness of machined materials. However, frequent electrode back-offs and the risk of workpiece burning may occur if erosion products are not removed promptly. In this study, it was found that the flushing method of the working medium had a significant impact on the machining performance of arc milling. Based on this, a novel highefficiency compound machining method of elect...     

Controlling secondary flow in high-lift low-pressure turbine using boundary-layer slot suction

The design of high-lift Low-Pressure Turbines (LPTs) causes the separation of the boundary layer on the suction side of the blade and leads to a strong secondary flow.This present study aims to minimize secondary losses through endwall slot suction and incoming wakes in a front-loaded high-lift LPT cascade with Zweifel of 1.58 under low Reynolds number of 25000.Two slotted schemes for the boundary layer of the endwall were designed (Plan A and Plan B),and the effects of suction mass flow on seco...     

Geometric error measuring,modeling, and compensation for CNC machine tools:A review

Geometric error,mainly due to imperfect geometry and dimensions of machine components,is one of the major error sources of machine tools.Considering that geometric error has significant effects on the machining quality of manufactured parts,it has been a popular topic for academic and industrial research for many years.A great deal of research work has been carried out since the 1970s for solving the problem and improving the machining accuracy.Researchers have studied how to measure,detect,mode...     

Interfacial characteristics in CNTs-AgCuTi systems

AgCuTi-based composite fillers reinforced with Carbon Nanotubes（CNTs） were prepared by mechanical ball milling and ultrasonic agitation. The morphological features, chemical components, and melting characteristics of the composite fillers with different content of CNTs addition were investigated using Field Emission Scanning Electron Microscopy（FESEM）, XRay Diffraction（XRD） and a Differential Scanning Calorimeter（DSC）. After being heated at 900 ℃, the microstructure of the composite fillers was ...     

Design and development of a five-axis machine tool with high accuracy,stiffness and efficiency for aero-engine casing manufacturing

In order to satisfy the machining requirements of aero-engine casing in modern aviation industry, this paper investigates three main issues during the design and development process of a five-axis machine tool with high accuracy, stiffness and efficiency, including whole structure design,key components design, and supporting stiffness design. First, an appropriate structure of five-axis machine tool is determined considering the processing characteristics of aero-engine casing. Then, a dual driv...     

A multi-frame track-before-detect algorithm based on root label clustering for multiple targets

In this paper, a novel multi-frame track-before-detect algorithm is proposed, which is based on root label clustering to reduce the high computational complexity arising by observation area expansion and clutter/noise density increase. A criterion of track extrapolation is used to construct state transition set, root label is marked by state transition set to obtain the distribution information of multiple targets in measurement space, then measurement plots of multi-frame are divided into sever...     

Effect of longitudinal lift distribution on sonic boom of a canard-wing-stabilator-body configuration

After the last flight of the Concorde in 2003, sonic boom has been one of the obstacles to the return of a supersonic transport aircraft to service. To reduce the sonic boom intensity to an acceptable level, it is of great significance to study the effect of lift distribution on far-field sonic boom, since lift is one of the most important contributors to an intense sonic boom. Existing studies on the longitudinal lift distribution used low-fidelity methods, such as Whitham theory, and in turn,o...