Beamforming of Whole Airspace Phased Array TT&C System Based on Linear Subarrays

The whole airspace phased array telemetry,track and command(TT&C)system is regarded as the development tendency of next generation TT&C system,and the distribution of the antenna units and the beamforming technology have sparked wide interest in this field.A method for antenna distribution is proposed based on the linear subarrays technology.A symmetrical truncated cone conformal array is composed of the linear subarrays placed on the generatrix.The impact of truncated cone bottom radius and elevation angle on beamforming are studied and simulated.Simulation results verify the system design.

Research on Operation of UAVs in Non-isolated Airspace

In order to explore the safe operation of UAVs in non-segregated airspace,a collision risk model for cylindrical UAVs based on conflict areas was constructed and the risk of conflict between manned and unmanned aerial vehicles was researched.According to the results of risk analysis,a strategy for solving the conflict of aircraft is proposed,and the risk assessment experiment of unmanned aerial vehicle(UAV)in non-isolated airspace conflict is carried out.The results show that under the experimental conditions,large unmanned aerial vehicles equipped with ADS-B,TCAS and other airborne sensing systems will indeed interfere with other aircraft in airspace when they enter non-isolated airspace.Especially when the number of aircraft in airspace is large,the automatic avoidance system of UAV will increase the avoidance time and trigger the safety alarm,but the safety level is still acceptable.This indicates that it is relatively safe for UAVs to enter non-isolated airspace under limited conditions.The results can be used as a reference for the safe operation of unmanned aerial vehicle(UAV)in non-isolated airspace.

Analysis on Potential Conflict Frequency of Intersected Air Routes in Terminal Airspace Design

In order to obtain accurate conflict risks in terminal airspace design,the concept and calculation model of potential conflict frequency for intersected routes are proposed.Conflict frequency is represented by the product of horizontal conflict frequency and vertical conflict probability.The horizontal conflict frequency is derived from the probability density distribution of conflicts in a period of time.Based on the recorded radar trajectory data,the concept and model of ROUTE distance are proposed,and the probability density function of aircraft height at a specified ROUTE distance is deduced by kernel density estimation.Furthermore,vertical conflict probability and its horizontal distribution are achieved.Examples of three intersected arrival and departure route design schemes are studied.Compared with scheme 1,the conflict frequency values of the other two improved schemes decrease to53% and 24%,respectively.The results show that the model can quantify potential conflict frequency of intersected routes.

Dynamic airspace sectorization via improved genetic algorithm

This paper deals with dynamic airspace sectorization （DAS） problem by an improved genetic algorithm （iGA）. A graph model is first constructed that represents the airspace static structure. Then the DAS problem is formulated as a graph-partitioning problem to balance the sector workload under the premise of ensuring safety. In the iGA, multiple populations and hybrid coding are applied to determine the optimal sector number and airspace sectorization. The sector constraints are well satisfied by the improved genetic operators and protect zones. This method is validated by being applied to the airspace of North China in terms of three indexes, which are sector balancing index, coordination workload index and sector average flight time index. The improvement is obvious, as the sector balancing index is reduced by 16.5 %, the coordination workload index is reduced by 11.2 %, and the sector average flight time index is increased by 11.4 % during the peak-hour traffic.

Optimization of a Route Network in Dakar Airspace: Surface Navigation

In this paper, the map of a network of air routes was updated by removing the non-optimal routes and replacing them with the best ones. An integer linear programming model was developed. The aim was to find optimal routes in superspace based on performance-based navigation. The optimal routes were found from a DIJKSTRA algorithm that calculates the shortest path in a graph. Simulations with python language on real traffic areas showed the improvements brought by surface navigation. In this work, the conceptual phase and the upper airspace were studied.

Design of Simulation System for Effectiveness Evaluation of Future Airspace Window Shooting

Future Airspace Window Shooting is a newly developed technology, which needs effectiveness evaluation before widely used. Future airspace window shooting technology, simulation system development principles and software chosen to develop the simulation system are introduced in the first. And then the overall design of the system, realization of the system and effectiveness evaluation through simulation are discussed in detail. Through the simulation, it is known that the FAW shooting has more superior performance when facing maneuvering targets.

Dynamic reconfiguration for en-route airspace

As the air traffic demand is anticipated to be increased significantly in the near future,dynamic and effective allocation of the airspace resource is becoming a world-wide focus in the research field of air traffic management（ATM）.Taking the U.S.targeting the en-route airsapce,a dynamic airspace configuration（DAC） algorithm to reconfigure the airspace in consideration of higher efficiency and safety is presented.First,a modeling technique based on graph theory is proposed to generate a mathematical model for the airspace,and then,the graph model is partitioned into subgraphs for the purpose of sectorizatoin.The final step generates sector configuration with desirable geometry shape.Through analysis on the Cleveland airspace center（ZOB） in the U.S.,the algorithm is proved to be robust to time-varying traffic load.

ESTIMATION METHOD OF AIRSPACE CONNECTIVITY PROBABILITY IN MILITARY AANET

Connectivity is the premise and foundation of networking and routing.For the probabilistic flight path of military aircraft resulting in the difficulty of Aeronautical Ad hoc NETwork(AANET) research,an estimation method of connectivity probability is proposed.The method takes airspace as the research object,starts with actual flight characteristics,and applies conclusions of random waypoint mobility model.Building a connectivity model by establishing Airspace Unit Circle(AUC) from the perspective of circle-circle coverage,the method obtains a theory of airspace network connectivity.Experiment demonstrates its correctness.Finally,according to the actual condition simulation,relationship between the number of aircraft,communication radius,and the flight area under connectivity probabilities is achieved,results provide reference for creating a network that under certain aerial combat condition.

An Improved AOMDV Routing Protocol for Airspace Communication Network

The airspace communication network based on spacecraft has a wide range of applications in regional information enhancement and emergency communication. In this paper, a routing algorithm for congestion degree detection of multipath routing (CD_AOMDV) is proposed. The method of combining the whole congestion degree detection and local congestion degree detection before service initiation is adopted. Timely and accurate judgment of the congestion degree reduced the loss rate of the hot nodes, so the average packet loss rate reduced. Simulation results show that compared with the traditional AOMDV protocol, the CD_AOMDV proposed in this paper has reduced the packet loss and improved delay performance, which is more suitable for the airspace communication network.

Performance Evaluation of Terminal Airspace System Safety, Delay and Predictability of Muritala Mohammed International Airport, Ikeja Lagos, Nigeria

This paper outlines a multi-dimensional user-oriented performance metrics approach in evaluating the operation of the terminal airspace system to aid in the airport and airspace planning and decision making. Safety, delay and predictability metrics contribute to the analytical framework. From the findings, the occurrence of air incidence has a high severity level at departure, and arrival phases of flight, higher likelihood at the radar room and much of the incidences were as a result of faulty equipment and inherent absence of modern airspace infrastructure. Also, in Lagos terminal airspace, the number of incidences has no close correlation with the level of traffic complexity. Total schedule arrival delay ranges from 1 - 392 minutes representing an average of 7.8 - 17.9 minutes per aircraft that arrived Lagos airport at that period. Besides, the total approach contact time ranges from 1 - 57 minutes, translating to 4.6 - 7.1 minutes per aircraft. However, variability in arrival time of 1 - 5 minutes is common from published airline arrival scheduled time. In the same vein, the variability of 1 - 5 minutes is common from approach contact times of aircraft. These figures indicate sound arrival predictability signature for Lagos airport. Also, departure time variability above 30 minutes is familiar from the ATC clearance time for the various routes under study. However, there is about or more 25% variability of more than 15 minutes, and this indicates possible inconsistency of predicting departure times from the times Air Traffic Control (ATC) clearance was acquired. Above all, the predictability of departure times in Lagos airport is weak compared to those of the arrival. Taken by it, this may be a sign of airspace congestion or ATC deficiencies at the Lagos airport. This is an indication of the lack of users’ confidence in Nigeria’s air transport industry to deliver just-in-time service.

Chronic airspace disease:Review of the causes and key computed tomography findings

Chronic airspace diseases are commonly encountered by chest,body or general radiologists in everyday practice.Even though there is significant overlap in the imaging findings of different causes of chronic airspace disease,some key clinical,laboratory and imaging findings can be used to guide the radiologist to the correct diagnosis.The goal of this article is to review and compare these features.

数字低空空域栅格化的表征度量与最优标定

低空飞行空间范围小、目标速度慢、环境要素杂,传统的经纬度表征方式无法满足智联环境下的低空精细管理要求,为此本文研究了数字低空空域栅格化的表征度量与最优标定问题。首先,从“点-线-面”视角构建了多维度低空空域结构要素量化表征规则,提出了低空空域多层级栅格量化表征方法;然后,通过判定不同空域栅格的“点-线-面”位置关系,提出了基于栅格交集矩阵的低空空域拓扑关系度量方法;最后,综合考虑低空无人机碰撞指数、低空栅格利用指数等优化目标,以及节点与栅格匹配约束、空间位置约束、无人机与无人机/障碍物安全约束等限制条件,建立了面向多维性能的低空空域栅格粒度最优标定模型。针对城市低空典型飞行任务场景对所提方法的有效性及优化效果进行了验证分析。实验结果表明,针对任意设定的低空空域和无人机飞行任务,在可接受的无人机碰撞指数和栅格利用指数下,所提方法可对数字低空栅格粒度进行最优配置,从根源上有效确保低空飞行活动的安全和高效。研究成果对于支撑数字低空空域精细化管理和异质飞行器融合运行具有一定的理论价值和应用意义。

低空空域无人机运行安全保障技术研究综述

低空空域飞行活动日趋频繁,无人机类型多样且性能差异较大,飞行过程中易与建筑物或其他航空器发生飞行冲突。为实现低空空域的规范化、安全化、精细化和智慧化管控,需不断提升保障无人机运行安全的技术手段,例如冲突风险探测、安全风险评估等。文章从无人机的轨迹预测与意图识别、低空空域飞行冲突探测、低空空域风险评估及预警告警等3方面进行了研究。首先,总结了在无人机轨迹预测和意图识别方面的研究成果和面临的问题挑战;其次,基于低空空域冲突探测形式,分析不同探测方法的优缺点;随后,围绕低空空域风险评估及预警告警技术,分析当前研究需要解决的核心问题;最后,对无人机冲突探测和风险评估技术等方面进行了展望。

防空作战中多边形责任区预警机空域配置方法

针对防空作战中不规则多边形责任区预警机空域配置问题,基于预警机巡逻航线最短直飞距离和最小转弯直径所形成的实时探测区,通过寻优算法确定预警机责任子区和相应的预警机巡逻可用空域,再基于预警机稳定覆盖度评估准则,对其空域配置进一步寻优,得到预警机空域配置优化方案。通过算例仿真验证了此种方法在不规则多边形责任区中规划预警机空域配置的可行性和提升作战效能的有效性,其方法具有较强的实用价值和军事价值。

基于仿人发育的混合空域智能无人机防碰撞策略研究

随着低空开放政策的实施,无人机将会脱离隔离空域,进入低空与各式各样飞行器混合进行飞行;而防碰撞能力作为无人机的关键技术,在混合空域中保持无人机安全飞行起到了至关重要的作用;通过对人的发育式学习防碰撞机理进行分析,建立了面向混合空域中密集障碍的实体模型和发育模型,最终构建了基于仿人发育的无人机防碰撞方法;仿真实验表明,提出的方法不仅使无人机可以通过学习与发育不断提高飞行安全性,而且还可以随着环境熟悉度的提升,加快无人机防碰撞行为,提高了无人机在混合空域密集障碍中的安全性与智能性。

基于风险地图的城市物流无人机路径规划研究

近年来物流无人机技术迅猛发展,但城市低空空域的复杂性、电磁环境的干扰以及城市内居民的生命财产安全都对物流无人机在城市的推广提出挑战。在此背景下,研究评估无人机运行综合风险并生成的风险地图,以无人机运输安全性、经济性和路径平滑程度为目标规划无人机全局路径,并增加对无人机航线保护区结构的约束。在原始NSGA III算法的基础上对航路点选择机制、交叉和变异操作进行改进,使算法更适应路径规划的需求。实验证明,模型能有效地避开禁飞区,确保路径的多样性、经济性和安全性,为物流运输经营者和低空空域监管方提供高质量、多样化的备选路径,满足不同决策者需求,为无人机城市物流活动的安全高效运行提供有效的解决方案。

一种联合空域监管系统设计

面向适应多样化联合行动样式和空域资源敏捷性使用需求,提出了一种联合空域监管系统设计方法。系统性介绍了空域监管系统能力特征、技术架构模型与功能分类,研究了空域实时数据处理、空域动态监视、空域监管决策等关键技术。对系统的关键技术内容及解决措施进行了重难点设计,提出了切实可行的解决方案,能够有效解决当前空域监管缺少科学、高效技术手段的突出问题,为实现全域全程空域资源综合监管机制提供了系统性基础模型和技术指导,为构建联合行动空域监管体系指明了发展方向。

鼻丘气房形态特征及额窦口参数在慢性额窦炎中的相关性研究

目的三维重建分析鼻丘气房(ANC)形态特征及额窦口(FSO)参数在慢性额窦炎(CFS)中的相关性。方法回顾性分析2019年9月-2022年6月新乡医学院第一附属医院80例确诊单侧CFS患者鼻窦CT,通过Mimics21.0软件分别测量三组间ANC和FSO相关参数,采用Kruskal-wallis检验比较三组间相关参数,采用Spearman秩相关检验分析ANC形态特征及FSO参数的相关性,分析其与CFS病情发展的相关性研究。结果1.ANC体积、表面积、上下径、左右径、前后径在三组间总体比较均有统计学差异(P<0.05);2分组ANC上下径均高于0分组、1分组(P<0.05)。2.FI值及FI截面积在三组间总体比较均有统计学差异(P<0.05);0分组FI值及FI截面积均高于1分组、2分组(P<0.05);1分组FI值及FI截面积均高于2分组(P<0.05)。3.FI值与FI截面积呈正相关(r=0.485,P<0.05);FI值、FI截面积分别与ANC体积、上下径及左右径均呈负相关(r=-0.372,r=-0.332,r=-0.357,r=-0.253,r=-0.423,r=-0.193,P<0.05)。结论1.鼻丘气房体积、上下径及左右径与FI值、FI截面积均呈负相关,ANC形态通过影响FI值、FI截面积,可使CFS病情加重。2.FI值、FI截面积与CFS病情程度呈负相关,可作为额窦口参数中评估FSO是否狭窄的一个客观监测指标。

全空域相控阵测控系统下的目标跟踪方法

随着我国航天测控(Tracking Telemetry and Command, TT&C)领域的不断发展,面向全空域相控阵TT&C的工程应用越来越多,传统TT&C系统中的校相及跟踪方法无法适应新的工程应用。针对目前全空域相控阵TT&C系统中校相及目标跟踪方法与传统TT&C系统不通用的问题,结合工程实践应用,介绍了全空域相控阵TT&C系统中的校相及目标跟踪方法。实践表明,所提方法具有良好的目标跟踪能力,可满足工程需要。