Table of Content

25 April 2020, Volume 38 Issue 2

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Civil Aviation

Path planning method for UAV cascaded relay communication

LIU Haitao, FANG Xiaoyu, GU Xinyu, LI Dongxia

2020, 38(2):  1-6. 

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UAV cascaded relay communication is an important technical scheme for the long-distance point-to-point wireless communication. Aiming at UAV path planning problem in UAV cascaded relay communication system with a mobile user node, a joint optimization and a stepwise optimization path planning method are proposed based on the maximization of ergodic capacity criterion. And the outage probability of the UAV cascaded relay communication system is derived by using FM-EM algorithm. Simulation results demonstrate the accuracy of the proposed path planning methods. Research indicates that the stepwise optimization path planning method achieves the same performance as the joint optimization path planning method.

Lean and sweep optimization for aero-engine fan blades and aerodynamic characteristics analyses

BAI Jie, XIONG Peng, SHI Lei

2020, 38(2):  7-12. 

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The lean and sweep on the fan rotor of one aero-engine is optimized based on numerical model to improve the total pressure ratio and isentropic efficiency and ameliorate the overall performance of the engine under design conditions. Steady numerical simulation is implemented to analyze the grid independence and verify the effectiveness of the model employing 800 000 gridding plan of fan rotor. The stacking line is fitted by Bezier curve, controlling its lean and sweep with parameters; Taking total pressure ratio and isentropic efficiency at the design point as objective functions, automatic optimization is completed using artificial neural network and genetic algorithm. Comparing with the original model, the total pressure ratio and isentropic efficiency have been increased respectively by 0.18% and 0.71%. The static pressure distribution along the span and chord direction
are adjusted, reducing the tip loss and end wall loss and improving the fan aerodynamic performance at the design point.

Aeroengine residual life prediction based on time series similarity

CAO Huiling, LIANG Jiawang

2020, 38(2):  13-17. 

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Performance degradation is one of the main reasons leading to the aeroengineremoval. Aiming atthe huge difference between individual performance degradation modes of the same type of aeroengine, the engine residual life prediction method based on similarity matching is proposed. Firstly, EGTM is selected to characterize the current performance state of the engine, similar correction and Dixon outliers are used to eliminate the influence of external factors. Secondly, K-means is conducted to the EGTM data. Finally,Euclidean distance method is used to calculate the similarity degree between predicted and historical samples,giving corresponding weight of the reference samples to predict the residual life of the engine. The actual data verification of airlines, shows that the proposed method has high prediction accuracy and can provide reliable basis for maintenance plan.

Access control method based on CP-ABE in NDN

WU Zhijun, XU Enzhong

2020, 38(2):  18-24. 

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Information caching technology in NDN improves data distribution efficiency. However, information caching decouples data publishers from data. The data in the storage node is at risk due to lack of security controls.Therefore, an access control method based on CP-ABE is proposed in NDN, which combines the improved CPABE algorithm with symmetric encryption, and introduces a re-encryption module in the edge router for protected data access coordination and privilege revocation. At the same time, a hash table-based interest packet filtering mechanism is built, implementing fine-grained access control and privilege revocation on a semi-trusted cache router. Theoretical analysis and experimental simulation results show that the proposed method reduces the overhead of data publishing and data request processing and improves data access efficiency.

Identification method of accelerometer error parameter based on IMU

WANG Li, XI Xianqiang

2020, 38(2):  24-27. 

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As the core component of IMU, the accelerometer accuracy directly affects the IMU accuracy. In order to improve the output performance of accelerometer, a 24-position method is proposed to identify the accelerometer error parameters. Firstly, the accelerometer output error model is established according to the input and output formula of accelerometer. Then the accelerometer error model parameters are identified by 24-position method and the calibration process of which is designed in details giving the calculation method of scale factor, misalignment angle and zero offset of the accelerometer. Finally, position test is performed by turntable to collect data and to conduct calculation as well as data analyses. Experimental results show that the proposed method can quickly identify the accelerometer error parameters and establish an accurate accelerometer error model.

Aircraft ground AC system simulation based on PSO-BA algorithm

DING Fang, ZHOU Yang, WU Tingna, CHEN Guibo

2020, 38(2):  28-32. 

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Due to the variable working conditions, large amount of parameters and huge delay of aircraft ground AC system, the traditional PID control has been unable to meet the requirement of high efficiency and speed in practition, Bat algorithm is introduced to optimize the partical swarm algorithm and improves the traditional PID control in aircraft ground AC system. Simulation result shows that the improved PSO algorithm has strong robustness and can effectively suppress the huge delay and other problems, which provides a theoretical reference for the improvement of aircraft ground AC system.

Load balance control strategy under smart apron grid structure

FEI Chunguo, MENG Meihan

2020, 38(2):  33-37. 

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Driven by flight flow, there appear problems such as large number of scattered nodes, strong heterogeneity of data, and dynamic changes of network topology in civil aviation apron network, resulting in load unbalance, fast resource consumption and short network life. Based on the theory of grid structure, an optimized ant colony algorithm for load balance control of apron router is proposed. The heuristic factor is defined by load quantity; negatively correlated transformation is conducted to the pheromone parameter of transition probability in order to realize load balancing of path transmission. Meanwhile, the network topology is optimized by deploying network node density. Simulation results show that the routing algorithm based on ant colony optimization is superior to the original LEACH algorithm in network energy consumption balancing, data transmission rate improvement and network life cycle increasing.

Simulation analysis on influence of groove abrasion on aircraft hydroplaning

CAI Jing, XU Zheng

2020, 38(2):  38-43. 

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The abrasion condition of aircraft tires has big influence on its hydroplaning behavior, and then affects flight safety. Aiming at this problem, the tire models with different abrasion degrees are established by using finite element software, and CEL algorithm is used to establish tire—waterfilm—pavement interaction model. The influence of tire abrasion degree on the three factors‘interaction is analyzed, and the critical hydroplaning speed of tires with different abrasion degrees on pavement with various waterfilm thickness is calculated. Results show that when the groove abrasion degree is more than 50% , the drainage capacity decreases obviously, and the distribution of hydrodynamic pressure on the front edge changes. With the increase of tire abrasion degree, the critical hydroplaning speed will decrease continuously. When the groove depth gets abraded to less than the current waterfilm thickness, the critical hydroplaning speed of the tire decreases by 16%~20%, hydroplaning is more likely to occur, which will affect the maneuverability of aircraft during landing. Accordingly, airliners are suggested to revise the tire replacement standard to ‘replace the tire when the abrasion rate reaches 50%’.

Visualized airline competitiveness evaluation based on decision ball model

LONG Hanliang, CHEN Ye, XU Haiyan

2020, 38(2):  44-50. 

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Improving the competitiveness of airlines is the key to build a strong civil aviation country. A competitive evaluation index system is built considering the scale strength, operational capability, service quality and profitability. Decision ball model is applied to conduct dynamic data analyses and visualization for major airlines of the world from 2008 to 2017. Empirical analysis of airlines爷competitiveness shows that service quality and
profitability are typical shortcomings of Chinese airlines. Suggestions about competitiveness promotion are supplied basing on analyses of advanced samples.

Safety recommendation comparison of aviation accident investigation reports between China and US based on WFA

CUI Zhenxin, SUN Wenlong

2020, 38(2):  51-54. 

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After an aviation accident/incident happens, the accident investigation agencies will propose corresponding safety recommendation for the hidden dangers of aviation system found during investigation. WFA is conducted aiming at the key words of safety recommendation in the Sino-US aviation accident investigation reports, including 130 accident investigation reports issued by CAAC in 2017 and 53 accident investigation reports released by US NTSB in 2013-2017. Results show that the four aspects of safety recommendation mostly involved are ‘pilot/unit’,‘procedure/regulation’‘machine/equipment’‘practice/training’, which are the key orientations of aviation safety management. Most safety recommendation given by CAAC aims at airlines, while the US aims more at FAA; in terms of procedure and regulation, CAAC emphasizes mostly the compliance of regulation, while the US emphasizes the revision of regulation.

Comparative study on aircraft type certification system documents between China and US

LI Jing, GE Hongjuan, LIANG Zhouchi, DONG Xiaoxu, JIE Yuwen, QU Zhanwen

2020, 38(2):  55-59. 

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Aircraft type certification documents under different organizations both in China and US are analysed, including
airworthiness regulations, orders, airworthiness management procedures and advisory circulars. Differences and revision analysis of airworthiness regulations of China and US are compared by taking CCAR-25 and FAR-25 as examples, basing on that, suggestions to supplement CAAC advisory circular and improve airworthiness management procedures are proposed from aspects of the specific content of documents, designee management document framework, designee type document and so on, providing reference for document system improvement of aircraft type certification for CAAC.

Basic Science

Flexural properties of repaired composite laminate structure under hygrothermal conditions

SU Jingxin, ZHAO Wenhao, CHEN Dong, LU Pengcheng

2020, 38(2):  60-64. 

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In order to research the evolves regularities and mechanism of bending properties of composite repaired structures for civil aircraft structures when dealing with environmental changes, the bending behavior and failure mechanism of benzoxazine composite laminates under dry/hygroscopic conditions are systematically researched by means of electronic universal material testing machine, scanning electron microscope and laser confocal microscope. Results show that the bending strength of the bulk material/autoclave, bulk material/thermal compensation instrument, non-bulk material/autoclave,non-bulk material/thermal compensation instrument repair test plate can be restored to 99%,95%,97%,87% of the intact sample at room temperature. After heatmoisture treatment,the flexural properties restoration ratesare respectively reduced to 65%, 56%, 60%, 34%.
Bending fracture analysis shows that the failure mode of the intact specimen is tensile fracture of the fiber,and the failure mode of the repaired specimen is tensile fracture and debonding pull-out of the fiber. In summary,the fiber/resin interface bonding of the repaired specimen has the best performance by usingthe bulk repair material/ hot-pressing pot curing method.