Table of Content

21 December 2024, Volume 42 Issue 5

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Safety and airworthiness of civil aircraft

Reliability test method of airborne electronic components based on multi-stress accelerated degradation

WANG Penga, , TIAN Runcaob , DU Hongguangb , CONG Wei c , ZHANG Fana, , YU Guang , YANG Lyushan

2024, 42(5):  1-8. 

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The reliability test is one of the important sources to obtain the basic safety data. Considering the actual working
environment of airborne equipment, where multiple stress act together to cause product failure and there are complex interaction, a reliability test method based on accelerated degradation of multi-stress generalized coupling is
proposed in this paper, which can directly obtain the basic safety data for airworthiness compliance verification.
Firstly, a nonlinear Wiener accelerated degradation model considering multi-stress generalized coupling is established, and the form of stress coupling is determined by combining correlation analysis. Secondly, maximum likelihood estimation and parameter optimization method based on the multi-stress accelerated degradation model is
proposed to solve the problem of multi-parameter estimation. Finally a three-stress accelerated degradation test is
carried out with an airborne LED chip as the object to realize the life assessment. The results show that, compared
with the traditional multi-stress accelerated model, the proposed method is closer to the actual working condition,
and the error is controlled within 1%, and the accuracy of life assessment is high, which can effectively solve the real airworthiness problem of missing and inaccurate of basic data.


Research on lumped parameter model of aviation seat cushion

XIE Jianga , ZHONG Xinyanb , SHI Xiaopengb , CHEN Yingshi b , LI Weiliangb

2024, 42(5):  9-13. 

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In order to solve the problem of negative volume and long computation time caused by large deformation of aviation
seat cushion in the impact simulation of aviation seat finite element models, a lumped parameter model of aviation
seat cushion consisting of parallel nonlinear springs and linear damping is proposed. Firstly, the static and dynamic
compression test of the aviation seat cushion material is carried out, and the finite element model and the lumped
parameter model of the aviation seat cushion are established respectively. Secondly, the spring damping parameters
of the lumped parameter model are fitted according to the results of finite element simulation, and the dynamic re鄄
sponses of the two models are compared under 14, 16 and 19 g delta pulses. The results show that the consistency
between the two models is good, and the lumped parameter model of the aviation seat cushion established in this
paper can provide support for the simplification of the complex finite element model containing the seat cushion.


Research on interference effect of high intensity radiated field in RF front-end of UAV datalink#br#

MA Zhenyang a , LI Mufan b , LI Bin c

2024, 42(5):  14-21. 

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Aimming at the datalink of quadrotor unmanned aerial vehicle (UAV) is susceptible to be interferenced by high intensity radiated field (HIRF) in low altitude airspace, this paper proposes a method of field-circuit joint simulation
to investigate the interference effect. Firstly the antenna coupling effect of UAV model under HIRF is investigated
with electromagnetic simulation software, and the coupling voltages under different irradiation directions, different
signal types and different pulse width coefficients are analyzed. Secondly, the radio frequency (RF) front-end cir
cuits of the datalink are integrated into the simulation with circuit design and analysis software to assess the interference effect. The results demonstrate that the smaller the pulse width coefficient, the stronger the interference
caused by Gaussian pulses. Additionally, under identical pulse width coefficients, modulated Gaussian pulses induce stronger interference than Gaussian pulses. Moreover, the addition of the interference signal leads to a significant increase in the peak value of the intermediate frequency (IF) output signal of the RF front-end, the shift of the
peak frequency and a decrease in signal-to-noise ratio.


Research on the risk algorithm model of safety situation for modern civil aircraft route operation

LIU Sujuan, LI Zhe, HUANG Aijun

2024, 42(5):  22-27. 

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A risk algorithm model of route operation safety situation is proposed in this paper, by combining factors that affect

airline safety operations and customer concerns. Firstly, the risk index of each chapter of the Air Transport Association (ATA) is calculated from eight aspectsincluding severe/general accidentsymptoms, unsafe incidents, failure rate

per thousand hours, reporting level of operational difficulty, abnormal flight conditions, risk level of continuous airworthiness incidents, index of commercial operation release conditions and the risk of failure to implement service

bulletin (SB) above the important category level. Then, based on the fleet risk index list composed of individual aircraft risk index, the risk points of each aircraft of the airline are obtained. Finally, the symptom nodes are analyzed

on this basis, and provide measures to mitigate risks. The verification shows that the proposed algorithm model can

improve the efficiency and economy of fleet operation, thereby ensuring the safe and smooth operation of aircraft.

Study on influencing factors of natural transition of supersonic boundary layer

FAN Jiakuna , XIE Lu , XU Jiakuana, c , QIAO Lei b , BAI Junqianga, b

2024, 42(5):  28-35. 

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In order to investigate the effects of factors such as Mach number, Reynolds number, sweep angle, wall temperature

and pressure gradient on the natural transition of supersonic boundary layer in the cross-flow mode and Oblique T-S mode, linear stability theory (LST) and eN transition prediction method are used in two-dimensional or quasi three-dimensional flows such as flat plates, airfoils and infinite swept-back wings. The effects of these influencing factors

on the N factor of cross-flow mode and Oblique T-S mode are studied through variable parameter analysis. Based on

the inflow and wall conditions set in the cases in this article, the calculation results show that the growth rate of the N

factor in the cross-flow mode is positively correlated with the inflow Mach number and Reynolds number, respectively. As the sweep angle increases from 30 ° to 60 °, the N factor growth of the cross-flow mode continues to accelerate. After exceeding 60 °, N factor growth in the stationary wave begins to weaken, while the N factor in travelling

wave does not change significantly in the range of 60 ° to 75°. It can be inferred that the critical sweep angle at which

the N factor in travelling wave begins to decay is larger. The N factor growth rate of Oblique T-S mode is positively

correlated with the inflow Reynolds number, the ratio of wall temperature to inflow temperature, respectively. The N

factor growth rate decreases as the inflow Mach number increases or the positive pressure gradient increases. Therefore, the influence of the variation of inflow Mach number on natural transition is related to the type of analyzed instability mode, while the trend of the influence of the variation of inflow Reynolds number on the N factor of natural

transition of cross-flow mode and Oblique T-S mode is consistent.

Study on flow characteristics of low-pressure turbine boundary layer based on

multiple analysis methods

SUN Shuang, HUANG Zhen, KANG Jinhui, SUN Xiaopeng, WANG Maomao, LU Lehan

2024, 42(5):  36-44. 

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To investigate the unsteady flow characteristics of the low-pressure turbine suction surface boundary layer of an

aero-engine under the influence of wake, the commercial software CFX 15.0 was used for numerical simulation in

this paper, and a cascade test platform with an upstream wake simulation function was used for experimental verification. Firstly, three different upstream reduced frequencies of wakes were achieved by changing the speed of the

upstream wake bar while keeping the axial velocity unchanged. Then, by numerical simulation, the flow field data

of the low-pressure turbine suction surface boundary layer under three conditions were obtained and compared.

Three new flow field analysis methods including proper orthogonal decomposition (POD), dynamic mode decomposition (DMD) and Fourier mode decomposition (FMD), were used in the analysis. The results show that, under the

three reduced frequencies, the height of the wake center from the blade surface differs greatly when it passes

through the separation area. The influence degree of the wake in the suction surface boundary layer and the main

identified characteristics are also very different under the influence of wake.

Safe Operations in Integrated Airspace

Identification of interference type of Beidou navigation satellite system based on

learning from time-frequency graph

LIU Ruihuaa , ZHANG Yantinga , MA Zanb

2024, 42(5):  45-51. 

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Aiming at the problem that existing interference identification algorithms rely on feature engineering to extract features, which is cumbersome and the identification accuracy is greatly affected by the value of signal-to-noise ratio,

the interference type identification method of Beidou navigation satellite system (BDS) based on learning from

time-frequency graph under different signal-to-noise ratio is proposed in this paper. Taking the B1I signal of the

airborne BDS as the object, the original B1I signal and the B1I signal containing interference are subjected to

short-time Fourier transform. The time-frequency graph obtained after the transform is used as the input vector of

the support vector machine and convolutional neural network model to complete the detection and identification of

interference types. The simulation results show that the average identification accuracy of both machine learning

identification algorithms has reached over 99%, which is about 30% higher than that of traditional decision tree

identification algorithms, solving the problem of existing interference identification algorithms that heavily rely on

manually designed feature engineering to extract interference signal features and have low accuracy. The research

results can provide prior information for subsequent interference suppression work and improve the safety of BDS

in the aviation field.

Future airports and smart equipment

Optimization of land use around airports by integrating aviation noise and

CoMOLA model

WANG Chao, CUI Chunmei, LI Wenqing

2024, 42(5):  52-58. 

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Aviation noise is an important factor affecting the land use allocation around the airport, and it is of great significance to optimize the land use around the airport based on the compatibility of aviation noise to promote the development of the area around the airport. Based on the problem of land use planning around airports of aviation noise

compatibility, a model of constrained multi-objective optimization of land use allocation (CoMOLA) was constructed combing aviation noise compatibility. Combined with the aviation noise, land use compatibility model and the

non-dominant ranking genetic algorithm, the external model of land use conversion, area and comprehensive benefit was set up, and finally the compatibility between adjacent land was analyzed, and relevant solutions were proposed for the incompatible plots. The results showed that this model effectively integrated aviation noise and land

use planning around the airport, which is helpful for the policy deployment of land use planning around the airport,

enriched the territorial spatial optimization model around the airport, and had practical significance for the coordinated development of the airport.

Improved reinforcement learning algorithm for mobile robot path planning

ZHANG Wei a, , CHU Zeyuanb , YANG Yutaoa , WANG Wei a

2024, 42(5):  59-65. 

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Aiming at the problems of poor smoothness, slow convergence speed and low learning efficiency of the paths

planned by the traditional Q-learning algorithm, this paper proposes an improved Q-learning algorithm for mobile

robot path planning. Firstly, the density of obstacles and the relative position of the start point are considered to select the action set to accelerate the convergence speed of the Q-learning algorithm. Secondly, a continuous heuristic factor is added to the reward function, which consists of the distance between the current point and the end

point, and the distance of the current point from all the obstacles in the map as well as the boundary of the map. Finally, a scale factor is introduced into the initialization process of Q-value table to give the mobile robot with a priori environment information, and the proposed improved Q-learning algorithm is simulated and verified in a raster

map. The simulation results show that the convergence speed of the improved Q-learning algorithm is significantly

improved compared with the traditional Q-learning algorithm, and its adaptability in complex environments is better, which verifies the superiority of the improved algorithm.

Future airports and smart equipment

Causes and control technology for early age cracking during the formation stage of

airport cement concrete pavement

GAO Zhibin, LI Kefei

2024, 42(5):  66-72. 

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During the early stages of pouring and forming cement concrete pavement panels at airports, if there are crack defects inside the concrete structure, under the action of deformation， the micro cracks will gradually expand into

visible cracks and even develop into pavement diseases. To control the continuous expansion of early micro cracks,

this article analyzes the causes of cracking and corresponding control measures of pavement panels from three aspects including material of cement concrete pavement, pavement panel design and pavement construction, by combining with a certain airport pavement project. This study can provide a reference for similar projects required to

control early micro cracks in concrete.

Dynamic interaction and response analysis between aircraft main landing

gear and rigid runway

DU Hao , LI Peilin , HOU Tianxin

2024, 42(5):  73-82. 

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To further clarify the interaction mechanisms and dynamic responses within the aircraft-runway system, a physical

model of the dynamic interaction between the aircraft main landing gear and and rigid runway was developed firstly,

and the aircraft tire and runway foundation were simulated as rigid roller model and Pasternak foundation model,

respectively. Secondly, mathematical expressions of rigid roller model and Pasternak foundation model were derived based on the principle of displacement coordination, and a novel fast explicit integration algorithm was employed to solve the vibration response of both the aircraft landing gear and the runway structure. Finally, taking the

B737-800 aircraft as a case study, the dynamic responses of the aircraft subsystem and runway subsystem were analyzed under different runway structural strengths, aircraft taxiing speeds and pavement roughness to reveal the key

factors influencing aircraft safety, comfort degree and runway structure safety. The results indicated that the attenuation of the foundation stiffness has a great influence on the runway vibration response, with a maximum growth rate

of 56.13%. As the aircraft taxiing speed increases, the vibration displacement peak of the lower pavement of the

wheel initially rises and then falls, while the vibration acceleration peak of both the fuselage and wheels consistently increase. Due to the dissipation effect of the landing gear buffer, the influence of runway roughness on fuselage vibration acceleration has a lag effect.

Air Transportation Management

Analysis of the complementary effect of air-rail integrated transportation network

WANG Fei , WU Jiawei , HUANG Baojun

2024, 42(5):  83-88. 

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To better leverage the advantages of aviation and high-speed rail transportation, the complementary effect of air-rail

integrated transportation network was studied. Firstly, the aviation network, high-speed rail network, and air-rail integrated transportation network were constructed with cities as nodes, airline/ high-speed rail route as edges, and

daily flight frequency/high-speed rail frequency per day as weights. Secondly, using enumeration method and genetic algorithm, the robustness of the network was studied based on network weighted efficiency, and critical node combinations of the network were identified. Thirdly, the complementary effect of the high-speed rail network and aviation network was investigated from two perspectives of robustness and complementary strength under two scenarios of

random node failure and critical node failure. The results showed that the weighted efficiency of the air-rail integrated transportation network was approximately 0.317, which is significantly higher than that of the aviation network

(0.268) and the high-speed rail network (0.209). When the independent high-speed rail network was not connected,

the air-rail integrated transportation network remained connected. Under random node failure and critical node failure, the average complementary strength of the high-speed rail sub-network to the aviation sub-network is 0.072

and 0.435, respectively and the average complementary strength of the aviation sub-network to the high-speed rail

sub-network is 0.217 and 0.368, respectively, with stronger complementary effect observed under critical node failure. The results indicated that the air-rail integrated transportation network combined the advantages of the aviation

network and high-speed rail network, with better robustness. Aviation network and high-speed rail network can play

complementary effect and its complementary effect is more pronounced under critical node failure.

Aviation Environment and Sustainable Development

Data-driven airport aircraft pollutant emission inventory

and characteristics analysis

SUN Jiaojiao , HU Rong , PAN Xiaoran , DENG Songwu, , GUAN Zhaowei

2024, 42(5):  89-96. 

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Improving the accuracy of the airport aircraft pollutant emission inventory is an important prerequisite for the development of green civil aviation. Firstly, this study uses the data of flight operation and aviation routine weather

report of Guangzhou Baiyun International Airport in 2019 as the driving force to calculate and correct key parameters such as flow rate of engine fuel, pollutant emission index, mixing layer height and flight operation stage duration. Secondly, the emission inventories for hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx)

are established and compared based on the standard model of International Civil Aviation Organization and datadriven correction model(abbreviated as correction model) , and comparative analysis is conduced. Finally, the pollutant emission characteristics are explored from three dimensions including aircraft type, time and space. The results show that the annual emissions of HC, CO and NOx obtained by the corrected model are 10.26%, 11.94%, and

26.03% lower than those of the standard model. A320 aircraft type has lower emission intensities. The peak emissions of three pollutants occur from 08：00 to 10：00, while the off-peak emission times are from 02：00 to 03：00.

HC and CO emissions change little throughout the year, in contrast, NOx emissions are higher in November and

December when the mixing layer height is higher and the relative humidity is lower. The emissions of the three pollutants are concentrated in the directions corresponding to the departure route points of LMN, YIN and VIBOS.