Mechanical Dispatch Reliability Prediction for Civil Aircraft Considering Operational Parameters

To effectively predict the mechanical dispatch reliability(MDR),the artificial neural networks method combined with aircraft operation health status parameters is proposed,which introduces the real civil aircraft operation data for verification,to improve the modeling precision and computing efficiency.Grey relational analysis can identify the degree of correlation between aircraft system health status(such as the unscheduled maintenance event,unit report event,and services number)and dispatch release and screen out themost closely related systems to determine the set of input parameters required for the prediction model.The artificial neural network using radial basis function(RBF)as a kernel function,has the best applicability in the prediction of multidimensional,small sample problems.Health status parameters of related systems are used as the input to predict the changing trend ofMDR,under the artificial neural network modeling framework.The case study collects real operation data for a certain civil aircraft over the past five years to validate the performance of the model which meets the requirements of the application.The results show that the prediction quadratic error Ep of the model reaches 6.9×10−8.That is to say,in the existing operating environment,the prediction of the number of delay&cancel events per month can be less than once.The accuracy of RBF ANN,BP ANN and GA-BP ANN are compared further,and the results show that RBF ANN has better adaptability to such multidimensional small sample problems.The efforts of this paper provide a highly efficientmethod for theMDR prediction through aircraft system health state parameters,which is a promising model to enhance the prediction and controllability of the dispatch release,providing support for the construction of the civil aircraft operation system.

Grey Incidence Analysis Applied to Civil Aircraft Customization Process

The airlines need to select the optional equipment according to their individual development demands and the manufacture′s standard specification manual when purchasing a new airplane.For this customization process,the selection theory is mainly based on qualitative analysis and quantitative analysis.The grey incidence analysis(GIA)is used for modeling,which evaluates the correlations between optional equipment and airlines′individual demands.Meanwhile,the customization demands are quantitatively processed as different weights in evaluation index system with analytical hierarchy process.Then,the value of grey incidence degree is obtained which shows whether the optional equipment is on the purchasing list or not.Finally,two airlines′customization demands are applied in the example of aircraft cabin′s seats,so two different purchasing priorities and equipment installation lists can be obtained.The results and comparisons verify the reasonable of modeling,which provides an objective scheme of aircraft equipment selection.

Civil Aircraft Assisted Space-Air-Ground Integrated Networks: Architecture Design and Coverage Analysis

In this paper, we propose a novel AIenabled space-air-ground integrated networks(SAGIN). This new integrated networks architecture consists of LEO satellites and civil aircrafts carrying aerial base stations, called "civil aircraft assisted SAGIN(CAA-SAGIN)". The assistance of civil aircrafts can reduce the stress of satellite networks, improve the performance of SAGIN, decrease the construction cost and save space resources. Taking the Chinese mainland as an example, this paper has analyzed the distribution of civil aircrafts, and obtained the coverage characteristics of civil aircraft assisted networks(CAAN). Taking Starlink as the benchmark, this paper has calculated the service gap of CAAN, and designed the joint coverage constellation. The simulation results prove that the number of satellites in CAASAGIN can be greatly reduced with the assistance of civil aircrafts at the same data rate.

Estimation of the Aircraft CO_2 Emissions of China's Civil Aviation during 1960-2009

Based on data collected by Chinese Civil Aviation Statistic Center, the annual CO 2 emissions of aircrafts during 1960-2009 were calculated, and the emission intensity and its dynamic characteristics were analyzed. The results show that the total CO 2 emissions of aircrafts in China increased from 120 × 10 3 t in 1960 to 41.44 × 10 6 t in 2009. The CO 2 emission intensity decreased from 2.9 kg (converted t km) 1 in 1960 to 0.96 kg (converted t km) 1 in 2009 at an average rate of 0.04 kg (converted t km) 1 per year. The average share of CO 2 emissions of aircrafts on the total CO 2 emissions from the sector of transportation, storage and post was 6.6% during 1980-2005, and 0.25% on the total emissions from fossil fuel combustion during 1971-2008.

Hierarchical Colored Timed Petri Nets for Maintenance Process Modeling of Civil Aircraft

Civil aircraft maintenance process simulation model is an effective method for analyzing the maintainability of a civil aircraft. First, we present the Hierarchical Colored Timed Petri Nets for maintenance process modeling of civil aircraft. Then, we expound a general method of civil aircraft maintenance activities, determine the maintenance level for decomposition, and propose the methods of describing logic of relations between the maintenance activities based on Petri Net. Finally, a time Colored Petri multi-level network modeling and simulation procedures and steps are given with the maintenance example of the landing gear burst tire of a certain type of aircraft. The feasibility of the method is proved by the example.

OPTIMAL DESIGN AND AERODYNAMIC CALCULATION OF WING CONFIGURATION OF CIVIL AIRCRAFT

An effective method of optimal design of wing configuration is provided. The SUMT (sequential unconstained minimization technique) method is a good technique for solving the nonlinear programming. The application of penalty in optimal design of wing configuration has been solved well. The present method for the aerodynamic calculation is the combination of both the nonlinear panel method and the suction analogy method of vortexlift spanwise distribution on large swept wing-tip. The calculation results are in good agreement with experimental data. According to the computation and experiment,the mechanism of the increased lift and reduced drag about the sheared wing-tip wing has been analyzed, and some opinions of interest are proposed.

Optimization of Maintenance in Civil Aviation Aircraft Equipments

As the economic level rising,the function and stability of civil aircraft have been greatly improved.However,with the development of science and technology in modern civil aviation transportation,the frequent occurrence of flight accidents has threatened people’s safety.The main reason is the internal failure of the engine body or the daily maintenance management is incomplete.Therefore,the relevant maintenance management departments should attach great importance to the first core research and management of civil aircraft stability and safety.In view of various equipment problems existing in the operation of civil aircraft,the practical application of data collection mode and maintenance information disclosure mode of modern aircraft maintenance equipment is analyzed.This paper describes some characteristics of aircraft maintenance work,and combined with the main factors affecting the risk of civil aircraft maintenance,giving countermeasures and suggestions to effectively improve the level of civil aircraft maintenance risk management.

Discussion on Continuous Airworthiness and Maintenance of Civil Aircraft

With China’s rapid economic development,the civil aviation market’s development area has expanded.On this basis,the state has proposed more extensive and stringent civil aviation rules.Many factors can affect the civil aircraft during the real operation process,and this can have an impact on the aircraft’s regular functioning to some level.To ensure that civil aircraft remain airworthy,appropriate maintenance work must be performed on a regular basis to prevent compromising the aircraft’s safety performance.For the purpose of reference,this paper discusses the continual airworthiness and maintenance of civil aircraft.

民机典型机身框段垂直入水冲击特性研究

为了研究民机典型机身框段垂直入水冲击特性,采用入水冲击试验系统开展不同高度下的圆柱体入水冲击试验,研究其入水冲击响应;基于LS-DYNA任意拉格朗日-欧拉(arbitrary Lagrange-Euler,ALE)方法建立流体域均匀网格及局部加密网格模型,通过对比圆柱体入水冲击试验结果验证网格收敛性及流体域模型;基于验证的流体域模型及机身框段模型,研究机身框段在6.02 m/s速度下的入水冲击特性,并分析与刚性地面冲击特性的差异性以及不同入水冲击速度下的机身框段冲击响应特性。结果表明:ALE方法在结构入水冲击方面具有较高的模拟精度,且采用局部加密网格时可以极大减少流体域模型网格数量和入水冲击计算时间。机身框段入水冲击时的失效模式与刚性地面冲击时的失效模式较为一致,但机身框段结构整体变形程度减小,客舱地板横梁变形程度增大;机身框仍是吸能最多的部件,但水也吸收了大量的冲击能量,使得地板导轨处的加速度始终小于刚性地面冲击时的加速度;随着机身框段入水冲击速度的增大,机身框发生弯折和上翘的程度加剧。

融入思政元素的飞机工程课程群混合式教学实践

在立德树人背景下,开展课程思政教学是必然趋势。针对专业课程价值塑造弱化的问题,飞机性能工程课程群根据国产民机和签派员岗位能力,依托超星在线教学平台,明确育人目标,将“课程思政”融入线上线下混合式教学,实现思政教学与“双线教学”双向贯通,课程群组成了课堂学习共同体,形成协同效应,打造有温度、有深度的立体课堂,丰富学生的学习方式,建立家国情怀和情感认同,达到“知识——技能——价值”一体化育人目标。

高度修正实现刚度等效的梁结构有限元建模方法

民用飞机中对于梁结构的有限元建模,一般采用刚度等效方法将梁建成杆单元与剪切板单元的组合形式,这种有限元简化方法仅能保证截面刚度与真实截面刚度近似等效,但有限元中的截面面积与实际面积却相差较大,致使有限元分析的结果不能准确反映结构严重部位的应力情况。针对传统刚度等效有限元建模方法的不足,提出一种采用高度修正的刚度等效有限元建模方法;将该方法的计算结果与传统建模方法的计算结果、理论计算结果、试验测量结果进行对比。结果表明:本文提出的高度修正的有限元建模方法比传统杆板系建模方法更准确,与试验结果更接近;将该方法用于民用飞机结构有限元建模,能够对真实结构进行更准确地模拟,分析结果也更精确。

基于LSTM-AE的民机空调热交换器性能异常检测方法

空调热交换器性能异常检测技术是快速判断民机空调系统运行状态并合理安排维修任务的关键,传统的异常检测方法难以有效处理高维时序数据,无法实现系统早期故障预警。为此,本文提出了一种基于长短期记忆网络(LSTM,long-short term memory)与自编码器(AE,autoencoder)模型的无监督异常检测方法,用以识别民机空调系统异常运行状态。首先,基于民机空调系统原始传感器参数构建表征空调热交换器性能的特征监测参数;其次,构建LSTM-AE模型进行数据特征重构并计算重构误差;最后,使用孤立森林(iForest, isolation forest)进行无监督异常监测。将本文构建的无监督异常检测方法与传统方法对比,并建立模型评估指标,验证结果表明,所构建的模型方法可以对民机空调热交换器性能异常状态进行有效检测。

冻雨天气对民机飞行的影响及运行控制研究:以贵阳龙洞堡机场为例

冻雨是影响民航在冬季安全运行的常见恶劣天气之一,在飞机表面形成的积冰等污染物会导致飞机机翼临界角减小,引起民机飞行的不安全事件。贵州省是我国低温雨雪凝冻灾害天气影响最严重的地区,为提高冻雨天气下民机飞行的安全性,选取贵阳龙洞堡机场为样本,梳理冻雨在民航运输中的危害性,再结合机场区域的地形特征,以贵阳2019年1月18日一次冻雨气象来研究冻雨产生的机制,研究发现贵阳地域纬度较低但海拔高度偏高的独特地形,加之区域内存在较强的逆温层,形成的上暖下冷温度场结构是造成冻雨的必备条件。最后从强化冻雨天气下的预报预警工作、落实冻雨天气下的机组操作规则、严格执行冻雨天气下的管制规定和制定冻雨天气下的工作预案等四个方面提出运行控制建议。

民用飞机远距离通信天线设计

随着通信技术的不断发展,民用飞机的通信手段也日益更新。目前民用飞机的通信方式主要包括三种,分别为高频(high frequency)通信系统、甚高频(very high frequency)通信系统和卫星通信(satellite communication)系统。天线是通信系统设备的最后一级,其结构与性能的好坏将影响整个无线电系统的通信质量。简要介绍了高频和卫星通信天线的基本辐射原理以及工程实例。高频通信天线采用回线天线的形式,卫星通信天线采用2×6的相控阵天线形式,相控阵天线单元采用缝隙耦合馈电的微带贴片天线形式,最后对通信天线的发展进行了展望。

民用飞机应急场景分析与建模方法

按照基于场景的民用飞机系统工程正向研制过程,为确保在飞机研制早期需求捕获与功能分析的完整性,针对应急场景开展识别、分析与建模方法研究。分析在飞机研制早期考虑应急场景的必要性,给出应急场景的定义和范围;针对民用飞机不同运行阶段,开展基于外部风险事件的应急场景识别,给出不同阶段的外部风险事件,并按照外部风险事件在不同阶段的演化结果给出相应的应急场景清单;研究形成一种基于DoDAF的应急场景建模方法,选取典型应急场景,形成应急场景建模的典型案例。通过对民用飞机应急场景分析与建模方法研究,形成可参考的外部风险清单和应急场景清单,同时形成面向应急场景的建模技术途径,为面向安全保证、基于应急场景的需求捕获与初步机组应急操作程序定义奠定基础。

民机航电系统虚拟化计算平台功能安全评估研究

围绕虚拟化后影响机载计算平台安全的时空隔离性、故障隔离性、可调度性等主要问题,开展虚拟化环境下机载计算平台的安全等级评定研究,考虑虚拟化后航电系统的特点,提出了一种基于层次分析法(AHP)和灰度关联分析法(GARD)的安全性计算方法。建立了机载虚拟化计算平台安全评估判断树,利用AHP方法计算了各安全能力的权重,给出了系统整体安全性得分,并在此基础上,结合GRAP方法,参照航空电子系统安全性评估,计算得出了测试系统与DAL安全等级要求适配度最高的安全等级。

面向声爆/气动力的飞行器布局设计知识挖掘

声爆抑制是发展新一代超声速民机必须突破的关键技术。飞行器总体布局参数对其声爆特性有重要影响。数据挖掘(DM)可以从大量的数据中通过算法搜索隐藏的信息,是飞行器设计知识提取的有力工具。选取后掠角、展弦比、梢根比、上反角、机身长细比5个总体布局参数作为设计变量,目标函数定义为远场感知噪声级,同时计算升、阻力系数作为气动力衡量指标。基于总变差分析(ANOVA)、决策树算法、自组织映射(SOM)网络组成的数据挖掘体系提取低声爆设计知识库。获得所选设计变量与声爆/气动力的相关度,并实现对设计变量的分层与降维。后掠角有最高设计优先级,长细比、上反角重要程度次之,展弦比与梢根比为低敏感变量。对于算例中的飞行器,在合理区间内选择较大的后掠角、上反角能够使声爆最小化的同时,设计适于超声速巡航的小展弦比布局。

民用飞机客舱空气质量状况调查

目的对国内民用飞机客舱空气质量进行调查评估。方法基于便利抽样监测不同机型飞机的客舱温度、相对湿度、风速、气压、照度、噪声、一氧化碳、二氧化碳、空气细菌总数及真菌总数参数,对载客巡航过程中检测到的各项参数在不同机型及不同点位的分布情况、参数间的相关性进行统计学分析。结果所调查56架飞机客舱平均温度、平均相对湿度、平均气压、风速中位数、平均噪声值、照度中位数、平均一氧化碳浓度、平均二氧化碳浓度、空气细菌总数中位数和空气真菌总数中位数分别为23.7℃、34.5%、84.9 kPa、0.07 m/s、72.1 dB(A)、141 lx、0.124 mg/m^(3)、0.11%、2个/皿和1个/皿;中型飞机客舱风速高于大型飞机(Z=-2.28,P<0.05),其他参数在不同机型间差异无统计学意义(P>0.05);中舱二氧化碳浓度低于前舱和后舱,但中舱噪声、风速均高于前舱和后舱,以上差异均具有统计学意义(P<0.05),其他参数均无差异(P>0.05);湿度与细菌总数、真菌总数均无显著相关关系(P>0.05),风速与二氧化碳浓度存在显著负相关关系(P<0.05),与湿度无显著相关关系(P>0.05)。结论抽样调查结果显示,我国飞机客舱空气质量水平较好,大多数参数可满足标准限值要求,但仍存在湿度偏低、噪声较高的情况,虽然这些情况通常不会影响飞行安全,但会在一定程度上降低旅客和机组人员的舒适度。另外,某些参数在不同点位及机型具有差异。适当增大风速可有效降低二氧化碳浓度。目前,民用飞机客舱空气质量作为航空环境卫生重要内容,其监测没有统一的行业标准和规范,本研究可以为民用飞机客舱空气质量标准及监测方法的制定提供参考和数据支持。

基于CNN-GRU-Attention的民机重着陆预测模型

重着陆事件是民用飞机着陆阶段最容易出现的事故之一,对其进行预测对于提升飞行安全具有重大意义。因此提出了一种基于卷积神经网络(Convolution Neural Network,CNN)和门控循环单元(Gated Recurrent Unit,GRU)并融合了注意力机制的重着陆预测模型,以飞机实际运行过程中采集的快速存取记录器(Quick Access Recorder,QAR)数据作为数据集。对QAR数据进行预处理并通过轮载信号确定数据集区间;通过Spearman相关系数对与飞机着陆相关的参数进行相关性分析,从中提取了24个特征参数作为预测模型输入,以重着陆判定指标垂直加速度作为输出,建立基于CNN-GRU-Attention的重着陆预测模型。实验结果表明,所提模型与其他预测模型相比具有更好的预测效果。