Table of Content

10 December 2022, Volume 40 Issue 6

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Civil Aviation

Prediction of wind speed by lidar based on PSO-Elman neural network

LIN Jiaquan , SONG Delong , ZHUANG Zibo , LI Jinfeng

2022, 40(6):  1-6. 

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The turbulence warning of civil airports requires refined wind field data. In this paper, a wind speed prediction model of particle swarm optimization(PSO) based on Elman neural network(PSO-Elman) is established to achieve the purpose of wind field refinement using lidar detection related data. Firstly, the spectrum width, signal to noise ratio and echo distance measured by the lidar experimental platform of Lanzhou Zhongchuan International Airport are used as the input data of PSO-Elman network. Then, the PSO algorithm is used to optimize the internal parameters of Elman network, and fitness function was established to improve the prediction accuracy and to reduce the convergence time. Finally, the non-linear function mapping of the convergent network is established to predict the wind speed between the radial distance gates. The simulation results show that the relative error between the measured and extended wind speed and the predicted wind speed is 6%, and the linear regression coefficiency between the measured and predicted wind speed is 0.919, which proves the effectiveness and feasibility of the wind speed prediction model.

Research on civil aircraft operational requirement evaluation software based on scene operation#br#

CHU Shuanglei , WEI Zhiqiang , REN Qiang , LIU Fei

2022, 40(6):  7-11. 

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At present, the evaluation index for the demonstration program of civil aircraft operation requirement is not comprehensive and complete, which is difficult to identify key indicators that affect the quality and competitiveness of civil aircraft products. Based on the analysis of the operational environment and operational mission of civil aircraft, an index system of operational requirements for civil aircraft is established from six dimensions: aircraft adaptability, aircraft convenience, equipment matching, maintenance rationality, aircraft advancement and dispatch reliability. The index weight is calculated by analytic hierarchy process, the membership degree of the index is determined by fuzzy set method. Indicators are quantitatively calculated combined with the objectivity of index membership and the subjectivity of expert qualitative analysis. A model for evaluating the operational requirements of civil aircraft is proposed, C# language is used to develop the evaluation software of civil aircraft operation requirement index system. An example of B737-800 is used to verify the rationality and feasibility of the evaluation model.

The invulnerability of China′s air route network based on percolation centrality

MENG Linghang , TIAN Chuan , LIU Yonggang

2022, 40(6):  12-17. 

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To effectively identify the weak parts in the route network and evaluate the decay of the route network's operational efficiency after the failure of critical nodes, an empirical study on the invulnerability of China's air route network is conducted from the perspective of a complex cyber system. Firstly, the percolation centrality is established by modifying the degree centrality based on actual origin destination(OD) pairs. The statistical comparison shows that the percolation centrality can reflect the operational importance of route points more accurately than the degree centrality and the betweenness centrality. The numerical node attack experiment is then conducted, taking the degree, betweenness and the percolation centrality each separately as the attack preference, to observe the growth of non-linear coefficient after the air route network is attacked. The results show that China's route network is robust to random attacks while vulnerable to targeted attacks. Taking the percolation centrality as preference, the attack accuracy and intensity is superior to centrality and betweenness, and the effectiveness of air route percolation centrality as measure of importance is thus verified.


Fault diagnosis of CFM56-7B engine based on SelBagging algorithm

CAO Huiling, CHENG Baorong

2022, 40(6):  18-23. 

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Aiming at the phenomenon that the redundant and poorly performing base learners in the Bagging algorithm increase the consumption of diagnostic procedures, a SelBagging selective integrated learning algorithm is proposed, which measures the diversity of the integrated system by calculating the Kohavi-Wolpert variance of the subset of the base learner. According to the diversity of the integrated system and the classification performance of the base learner, a subset of the base learners is selected with large differences and good classification performance for integration. By modeling the processed engine fingerprint map fault identification data, the results show that the SelBagging algorithm can effectively improve the classification accuracy, and has better and more stable classification results than the traditional Bagging algorithm. Finally, the actual fault case verifies that the SelBagging fault diagnosis model can be used for fault diagnosis of aero-engines.

Modal analysis of typical bending pipe of aero-engine

WANG Zhiguo

2022, 40(6):  24-31. 

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In order to tackle the abnormal operation problems caused by the vibration of the bending pipes of aero-engine system with different structural characteristics, the paper constructs the performance analysis models of the bending pipe with the different bending angles and the different pipe head lengths as the parameters. Then numerical simulation calculation is done to get the bending pipe vibration characteristics of the different bending angles and the pipe head lengths with the vibration modal analysis method. The results are analyzed and compared with the ones obtained by the vibration modal test of the bending pipes with different angles. The results show that the natural frequency of the same order of the models (1-4) mainly display the decreasing trend with small discrepancy along with the increase of bending angles, and the main deformation of the structure with bending superimpose torsion constantly and the amplitude of deformation increases gradually. Then the natural frequency of the same order of the models(5-9) display complex change with the increase of the length of the pipe head, and the main deformation of the structure isthe same asthe models(1-4) basically, except that the bending pipe with curved section located at the middle of the pipe is more affected. It is concluded that the vibration characteristics of bending pipe are complex with respect to the straight pipe. And it is necessary to analyze comprehensively the bending pipe vibration from multiple angles to keep away the vibration range generated by the coupling with the aero -engine vibration and thus improving the reliability of the design and use of the bending pipe in the aero-engine system.

Recognition method of visual inspection results of dent damage in laminates

LIU Yanhong, DAI Shengxin

2022, 40(6):  32-36. 

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In order to improve the accuracy and reliability of the visual inspection results of the dent damage of composite laminates, a recognition method is proposed to identify the marked sucker by color and to minimize the distance between the marked sucker and the dent damage based on the image of the marked sucker placed in the detected dent damage. The experimental results show that this method can ensure that the recognition rate of dent damage detection reaches 99.95%. On the other hand, the computer program of the method is simple, the workload of image analysis and numerical calculation are less, which can provide reference for improving the accuracy and reliability of visual inspection results of composite laminates for domestic aircraft,

Evaluation of emergency logistics capability of civil airport

SONG Yunxue, LI Sha

2022, 40(6):  37-44. 

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In order to improve the comprehensive assessment system of the current civil airport emergency logistics capability, a civil airport emergency support capability evaluation system is established. It includes 5 major first-level indicators of emergency response capability of staff, emergency equipment level, airport environment, management status, and airport operation, and 30 second-level indicators of a combination weighting methods based on AHP-factor analysis. An evaluation is conducted through airport simulation cases. The results show that the evaluation index system established and the evaluation method proposed in this paper are feasible and accurate for the evaluation of civil airport emergency logistics capabilities.

Visual analysis of indoor trajectories based on AOI division

HE Huaiqing, ZHANG Yumin, LIU Haohan

2022, 40(6):  45-52. 

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In large-scale indoor activities, the acquired indoor trajectories data has the characteristics of high spatial and temporal complexity, high-dimensionality and irregularity, which bring many challenges to visual analysis. In order to solve this problem, a visual analysis method based on the area of interest(AOI) division of indoor trajectories was designed for the problems of spatial and temporal distribution of indoor personnel, crowd movement patterns, and abnormal behavior patterns. Users can customize the area of interest and conduct indoor trajectory analysis based on this unit to determine its spatio-temporal pattern, movement pattern or abnormal behavior. Finally, the data of China Vis2019 Challenge was used to verify the effectiveness of the method, and valuable information was obtained through exploratory analysis of indoor personnel trajectories.

Airworthiness Column

Research and application of digital airworthiness certification management based on C-PRO model#br#

ZHU Yuping, GU Xin, SUN Huipeng

2022, 40(6):  53-59. 

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In order to solve the problems in airworthiness certification, such as unbalanced allocation of review resources, difficulty in overall monitoring, and difficulty in sharing review experience, the paper firstly analyzes the pain points and management needs in the airworthiness certification review process based on the current review practice; secondly, the C-PRO model which combines with Certification Plan Tree, Certification Regulation Tree and the Certification Object Tree is established, and a new airworthiness certification management method is proposed based on this model; finally, a digital airworthiness collaborative platform is constructed according to the fore -mentioned research. The platform has been put into use in domestic key type certification review projects. It has effectively remedied the defect in the type certification field, improved the review efficiency, and ensured the development of domestic aircraft type certification review.

Basic Science

New construction of two kinds of approximate unbiased bases

XU Dengming , LI Feiya

2022, 40(6):  60-64. 

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Mutually unbiased bases are the main topics in quantum information theory. In general, it is difficult to determine the maximal number of mutually unbiased bases over a finite dimensional complex vector space. For this reason, mutually unbiased bases with relaxed inner product conditions, the so called approximately mutually unbiased bases, have been gradually considered. Exponential sums over finite fields play an important role in the construction of approximately mutually unbiased bases. In this paper, two new approximately mutually unbiased bases are constructed using two kinds of exponential sums over finite fields.