Table of Content

25 October 2020, Volume 38 Issue 5

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Civil Aviation

Arrival airspace utilization rate of terminal area under scattered hazardous weather

ZHANG Zhaoning, XU Zihang

2020, 38(5):  1-4. 

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Hazardous weather is an important factor affecting aviation safety and causing flight delays, in order to measure the use of airspace and calculate the airspace utilization rate in terminal areas under hazardous weather, the impact of scattered hazardous weather on the aircraft‘s approach flight is analyzed. Based on the expansion theorem of maximum flow and minimum cut, the capacity change of the affected flight segment is determined, and the scattered shape is established from the perspective of flow-volume ratio, establishing the airspace utilization model of terminal approaching area under hazardous weather. Selecting a terminal area in China as instance, the hourly utilization rate of the airport under scatted hazardous weather is evaluated and compared with that under normal weather. Result shows that the utilization rate calculated by the model is consistent with the actual situation, which can reflect the impact of scattered-point hazardous weather on the utilization rate in terminal area.

Aircraft rerouting strategy research under special weather

LI Chunzhu

2020, 38(5):  5-9. 

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Special weathers on route is a main cause of aircraft flight accident. Aiming at this problem, various aircraft diversion strategy is given by using logic reasoning methods based on simulation graphics of aircraft flight track,weather position and running direction of weather. Combined with a violent typhoon 'Lekima' in 2019, the moving characteristics of the weather system near Tianjin approach area are analyzed and verified using the proposed rerouting strategy. Results show that the current strategy is feasible and effective.

Numerical simulation of transonic cavity on acoustic properties

MA Lixuan, LI Enyi, SUN Shuxia, YANG Qingxiang

2020, 38(5):  10-15. 

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A three-dimensional unstructured Navier -Stokes solver is employed for the numerical analysis of an open rectangular cavity with a length-to-depth (L/D) ratio of 5 and a width-to-depth (W/D) ratio of 1 on aerodynamic noise. Cubic k-turbulence model is used to obtain turbulent flow field, conduct artificial reconstruction and predict the near-field cavity noise combining with nonlinear acoustic solver (NLAS). Numerical results are compared with experimental data of sound pressure level (SPL), power spectral density (DSP) along cavity floor,experimental data, calculated value, formula-calculated values and resonant frequency of high-order numerical schemes in order to verify the rationality of the above method. To suppress the cavity noise and improve the environment for cavity flow field, other three kinds of structure modification are taken. Cavity SPL, the overall
SPL, vortex iso-surface under Q criterion and the nephogram of Lamb Vector under four conditions are compared and the result shows that the trailing edge slope most conducive to reduce noise by about 5db

Simulation analysis on influence of pressure sensor fault on aeroengine

YANG Kun, SUN Xiaonan

2020, 38(5):  17-22. 

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The nonlinear component level model and controller model of large bypass ratio turbofan engine are established. In order to analyze the influence of pressure sensor fault on performance parameters of the aeroengine during steady working, the constant deviation simulation fault of pressure sensor is added to the control system. Results show that when the measured value of low pressure turbine outlet pressure sensor is lower than the actual value,the simulated values of N1, N2, EGT and high pressure compressor surge margin SM will be higher than the true value, and as the value of sensor constant deviation fault increases, the deviation degree from the steady state value also increases. Impact analysis on pressure sensor fault provides reference for the airworthiness certification of aeroengine control system.

Plane distribution model of airport traffic volume based on landing wheel trace test

SHI Xingang, CAI Liangcai, WANG Guanhu

2020, 38(5):  23-28. 

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Basing on analyses of airport traffic volume characteristics, the longitudinal traffic factor is proposed. Supported by the measured data of aircraft landing wheel traces, the horizontal and longitudinal distribution of airport traffic is statistically analyzed and a plane distribution model of airport traffic is put forward. A simulation example of an airport shows that the model can evaluate the traffic volume at any point on the pavement. What爷s more, the effects of runway length, take-off and landing probability and standard deviation of wheel trace distribution on the plane distribution of traffic volume are also analyzed. The length of runway mainly affects the longitudinal overlap of wheel traces in the middle of the runway. The probability of takeoff and landing mainly affects the uniformity of wheel traces distribution at both sides. The standard deviation of wheel traces distribution influences the lateral overlap effect of wheel traces. The smaller the standard deviation of wheel traces distribution, the greater the number of maximum coverage effects.

Integrated recovery model of disrupted flights based on flight network

PENG Liansuo, WANG Zixu, WANG Xinglong

2020, 38(5):  29-34. 

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Aiming at the shortcomings of manual recover and staged recover, the integrated recovery model of disrupted flights is constructed considering aircraft, crew and passengers. Traditional flight network is improved, and a flight network generation algorithm based on breadth-first search is employed to model the flight recover decision process by using strategies including path replacement, path extension, path cancellation strategies. DW decomposition algorithm is used to design three kinds of subproblem and to get the iterative solution. Simulation of scenario examples shows that the proposed integrated recovery model can obtain a satisfactory solution within the effective time.

Dynamic passenger density prediction in baggage claim area for single flight

XING Zhiwei, WU Zhe, LUO Qian

2020, 38(5):  35-40. 

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A Bayesian network-based model is proposed to predict the density of passengers in the baggage carousel of a single flight, combining with baggage claiming process analysis and machine learning of historical data to establish Bayesian network. Incremental learning characteristics of Bayesian network is used to realize dynamic adjustment of BN model, so that it can better adapt the new data and get more accurate prediction of passenger density. Taking extracted data from a large hub airport in China as instance, expectation maximization (EM) method is used to conduct model training. Results show that the proposed model can effectively predict the density of passengers in baggage claim area with high accuracy.

Software threat modeling based on STRIDE model and civil aviation threat

GAO Jianyuan, PENG Mingtian, LI Yongjin

2020, 38(5):  41-45. 

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In order to improve the security of civil aviation passenger service system, threat modeling is built in SDL, constructing and enriching the threat knowledge base suitable for civil aviation business system. Meanwhile,effective mitigation measures are proposed aiming at various threats, forming a new threat model based on STRIDE and civil aviation threat knowledge base. This threat modeling method is effective to identify the security risks faced in the process of system construction, being not only suitable for existing systems, but also for the risk analyses during the design and development stages of new systems. The current method solves the contradiction between security personnel and system developers, which can effectively reduce the threshold of threat analysis，and the cost of software security risk and system development and operation.

Indirect effects simulation of lightning on civil aircraft based on EMA3D

YAN Fang, DUAN Xingwang, ZHAO Cong, MA Zhenyang, SHI Chunlei, ZUO Jing

2020, 38(5):  46-49. 

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TakingA320 as research object, double exponential function is used to establish the simulation model. By analyzing the distribution of surface current density and electromagnetic field, the electric field attenuation of a certain part of fuselage and the electric field transfer function in different lightning paths are studied. Simulation results show that the surface current density distribution is related to the lightning paths; the electric field distribution is related to the lightning paths and is mainly distributed around smaller curvature radius; the magnetic field distribution is basically consistent with the surface current density distribution; the electric field response bacomes greatest near 1.8 MHz.

Engineering and Technology

Design of portable voice digitization and network transmission system

NIU Yonggang

2020, 38(5):  50-54. 

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In order to realize high-precision recognition rate of digital voice and high-speed transmission of digital code, a portable voice digital network transmission system is designed, integrating the sound card chip WM8978 and Ethernet chip W5500. STM32F4 series high-speed processor is used as the MCU to conduct high fidelity digital voice coding and transmission via Internet. Test result shows that through inverse synthesis the network transmissing data of digitalized voice keeps consistent with the original speech signal, the proposed system the speed and accuracy of voice digitzation and network transmission.

Design of autonomous localization and navigation system for indoor mobile robot

ZHOU Xulong, ZHAO Yanzheng, YANG Yuemin

2020, 38(5):  55-59. 

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An autonomous localization and navigation system is designed for omnidirectional indoor mobile robots, which takes NVIDIA Jetson TX2 as upper computing platform and senses surrounding environment by lidar. Integrating wheel odometer and single axis inertial measurement unit, the designed system locates the robot by using selfadaptive Monte -Carlo algorithm basing on particle wave filter and implements autonomous navigation and obstacles avoidance by A-star algorithm and TEB algorithm. Results of Stage simulation and field experiment both show that the designed system can autonomously and accurately locate the robot, construct surrounding map with high accuracy, plan optimal path and help the robot avoid dynamic obstacles in time.

Layerwise symplectic finite element method for stress analysis of composite laminate

LIU Yanhong, ZHANG Zheng

2020, 38(5):  60-64. 

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The mechanical behavior of composite laminated plates and shells is complex, leading to difficulty in getting solution of stress. Based on the layerwise theory, the layerwise symplectic element including displacement and three out-of-plane stresses are established by combining with the principle of minimum potential energy and HR variational principle. Numerical verification shows that the derivation process of the layerwise symplectic element is simple and the numerical results converge stably. Compared with the incompatible displacement element model, the out-of-plane stress results of the current model are closer to the exact solution in the case of coarser meshes.