Table of Content

23 April 2016, Volume 34 Issue 2

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Civil Aviation

Reliability assessment of airborne oxygen system based on Bayesian network

WANG Peng, CHEN Xi,YAN Fang, ZHAO Changxiao

2016, 34(2):  1-5. 

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By analyzing airborne oxygen system architecture, the system reliability assessment model is built based on Bayesian network. The failure rate of leaf node and posteriori failure probability of root nodes are obtained by the forward and backward inferences, the key factors of system reliability are identified based on importance sequence and joint importance, the most probable explanation (MPE)is given. The advantages of the method are explained by comparing with FTA. Quantitative analysis proves the effectiveness of reliability assessment by using Bayesian network, and assessment results can also provide referencial information for the system structure design and fault diagnosis.

Research on fuel tank flammability assessment for civil aircraft

WEN Bo, LU Zhong

2016, 34(2):  6-9,14. 

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Fuel tank flammability assessment for civil aircraft is a vital part of civil aircraft fuel system airworthiness certification. A further research on the evaluation method provided by FAA is given. Factors which can affect the fuel tank flammability are analyzed, the parameter calculation method related to the fuel tank flammability is cleared, and the civil aircraft fuel tank flammability assessment process based on Monte Carlo simulation is given. Whether the temperature of fuel in unit time is between the upper and lower flammability limit will decide the fuel tank flammability at that point. The ratio of flammable time account for the total time is a vital reference to the fuel tank flammability assessment.

DME pulse interference mitigation method based on NLS

LI Dongxia, LI Si, CUI Yanmin

2016, 34(2):  10-14. 

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To mitigate the deleterious influence of distance measure equipment (DME)interference signals on orthogonal frequency division multiplexing (OFDM)receiver of L-band digital aeronautical communications system 1 (LDACS1), a new DME interference suppression method is proposed based on nonlinear least squares (NLS). The DME pulse is taken as the signal of interest because of its higher power characteristic; meanwhile, the frequency and complex amplitude of DME signal are estimated under the criterion of NLS. Then DME signal is reconstructed, and suppressed by subtracting the estimated DME signal from the received signal of OFDM receiver. Computer simulation indicates that the proposed method can reconstruct DME signal and reduce the impact of interference effectively, and improve the reliability of OFDMreceiver of L-DACS1 system significantly.

Tracking loop design of anti-rotation BD receiver

HU Tieqiao, LIU Ruijie, LI Ruiqin

2016, 34(2):  14-18. 

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In the case of carrier rotation, the navigation satellite signal received by receiver will have additional lager Doppler frequency shift, resulting in a decline in the receiver tracking performance and even failure. In order to solve this problem, a scheme is proposed to help the receiver track navigation satellite normally with rotating carrier. Based on traditional loop, the adding of auxiliary channel realizes real-time estimation of rotating speed to assist loop tracking. Simulation proves that the improved loop can effectively reduce the adverse effects caused by carrier rotation and achieve normal signal tracking.

Research on aircraft fuel consumption influencial parameters in climbing phase based on comprehensive relevance

CAO Huiling, WANG Xiaoyu

2016, 34(2):  19-22,51. 

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Based on analysis of real QAR data, the influential factors of aircraft fuel consumption in climbing phase, and comprehensive relevance is established by grey correlation analysis and correlation coefficient approach, then the fuel consumption influencial parameter is optimized by comprehensive relevancy. At last, the fuel flow model is established by support vector machine (SVM), and the accuracy is verified with actual data. Research results indicate that the prediction model is accurate and simple after parameter optimization, and fuel consumption prediction is attainable.

Research on calculation model of repair support cost based on engineering estimation method

HUANG Aijun, LIU Yanhong, XU Jianxin, WU Yaogang

2016, 34(2):  23-26. 

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After aircraft delivering, the cost of repair support including the charging range and standard should be confirmed. Then the cost calculation model of repair support should be established. The cost of repair support has been evaluated using engineering estimation method. The engineering estimation method estimates the cost using cost decomposition structure from bottom to top, so the model should be established after the actions and works have been known reasonably. At last the calculation model has been validated with the aircraft scheduled maintenance cost.

Plane layout optimization of airport flight area based on energy conservation

FENG Xing, LI Runing, AN Ran, TAN Yongfeng

2016, 34(2):  27-31. 

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As the sustainable development strategy is put forward, the green airport target is proposed in civil aviation. The airport flight area layout is taken as research object with the fuel consumption of aircraft taxiing as research target. Through analysis of aircraft operating conditions and the geometry of key points such as the airport apron position,the end of parallel taxiway and the end of runway in the flight area layout of single airport apron, single runway and single parallel taxiway, combining with the airport aircraft landing gear, the mathematical model of the overall fuel consumption of aircraft taxiing at the airport is established. On this basis, taking 4E international airport as an example, the minimum fuel consumption of aircraft taxiing is chosen as optimization goal, the fitness function is built, and the optimization is carried out using improved genetic algorithm. And the optimal flight area layout form is attained finally. The improved genetic algorithm has a quite good performance in the quality and time efficiency of convergence solution optimization, helping to solve the problem of airport flight area layout effectively.

Implementation and lifetime appraisal of low power wireless sensor network nodes

WANG Bingyuan, LIU Ximeng, LYU Zhongyi

2016, 34(2):  32-36. 

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Energy constraint is a crucial factor limiting the performance of single-lamp monitoring WSN (wireless sensor network)for airfield navigation lights. To reduce energy consumption of nodes and thus prolong lifetime of WSN,nodes are designed from three aspects appr including hardware energy consumption, software controlling structure and routing algorithm. Lifetime appraisal of nodes facilitates reliability design of WSN and maintenance of nodes. By accomplishment of differential-sample-based node energy consumption measurement, the appraisal of lifetime is fundamentally made valid.

Progress and developing trend of airport pavement roughness evaluation technology

CHENG Guoyong, GUO Wenhou, LEI Yawei

2016, 34(2):  36-41. 

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The methods, indicators and their characteristics of the current pavement roughness evaluation are analyzed as well as their applications. Combining with the 1/4 car model, the evaluating progress of the current pavement evaluation method and indices are derived, their characteristics are summarized and the future developing trend is anticipated. The principles, technical standards, characteristics and conversion between different indices of the current method in pavement roughness evaluation are studied including the three meter ruler method, level instrument method, continuous road roughness meter method, recursive section instrument, laser profilemeter method and bump integrator method. It is pointed out that two shortcomings of IRI(international roughness index), in coordination of the roughness scope with plane scale and incapability of measuring the coupling effect are produced by road surface under all wheels. It is proposed to study the airliner-scale-adapted pavement roughness evaluation system with the airliner scale by the establishment of a full scale aircraft model.

Engineering and Technology

Thermo-electrical coupling simulation of composites爷damage caused by lightning

LU Xiang, SU Wenzheng, LIN Yueguo, JIA Baohui

2016, 34(2):  42-45. 

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Lightning is an important cause of internal damage of composite structures, it leads to severely degraded performance of composite material and directly affects flight safety. A lightning damage model of the carbon fiber composite material IM600/133 laminates is established with finite element analysis software ABAQUS. The model simulates the law of materials爷recession depending on the material properties with temperature changes. Thermoelectric coupling analysis is conducted for the model. Electric field distribution and temperature distribution of the internal laminate are simulated during the lightning. Results show that the potential variation at the lightning attachment point is similar to the lightning current waveform during a lightning; the temperature distribution is influenced by the laminate ply direction, but also by the heat conduction effect of an adjacent layer; lightning damages appear mainly in the early lightning.

Text clustering method based on weighted LDA model

LI Guo, ZHANG Chunjie, ZHANG Zhiyuan

2016, 34(2):  46-51. 

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In order to overcome the shortcomings and limitations of traditional clutering algorithms in dealing with largescale and high dimension text clustering, a text clustering method is presented based on weighted LDA(latent dirichlet allocation)model. Two distributions are obtained by LDA: the topic distribution and the word distribution of different topics hidden in the text, which are then combined as the text feature to obtain the final text similarity. Using the classic K-Means algorithm in both English and Chinese corpus, the experimental results show that compared with the pure VSMcombined with K-Means, this algorithm has better clustering effect.

Management Science

Analysis of airline's service attributes on passenger-sharing rate:Take Beijing-Shanghai Air Express for instance

ZHAO Guihong, ZHENG Xing, HE Hongsheng

2016, 34(2):  52-55,61. 

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Differences between airlines'service attributes which may influence their passenger-sharing rates are analyzed,and these airlines are on the same air route. The result can help airlines improve their service levels effectively.Based on the data of China Eastern Airlines, Air China and Shanghai Airlines which are all on the Beijing-Shanghai Air Express, LOGIT model and multiple regression equation which is obtained from the model are constructed, results show that the number of flights has a significant impact on the three airlines'passengersharing rates. In addition, after making analysis of the final model, the sequence of service superiority between the three airlines is found.

Selection of aeronautical material suppliers based on AHP-BP neural networks

TAO Liquan, YANG Kun

2016, 34(2):  56-61. 

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According to the requirements of airworthiness regulations, a special index system for the selection of aeronautical material suppliers is proposed with the establishment of AHP-BP neural network model. The weight of each index is determined through AHP, and then combined with BP neural networks, the implicit knowledge and discipline from the training data is extracted, so that it can be used for new suppliers conveniently. The momentum gradient descent back-propagation algorithm is used in the model with well extensibility and increasing dynamic nature of the evaluation. Verification shows that AHP-BP neural network model is with strong practicability for the selection of aeronautical material suppliers.

Basic Science

Iterative algorithm for Lipschitz continuous and strongly monotone inverse variational inequalities

HE Songnian, LIU Hongzhi

2016, 34(2):  62-64. 

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Let C be a nonempty closed convex subset of a real Hilbert space H, f:H→H be a Lipschitz continuous and strongly monotone mapping. Then, inverse variational inequality is considered (in short, IVI (C, f));find ξ∈H such that f(ξ)∈C,＜ξ,v - f(ξ)＞≥0,∀v∈C.A new existence and uniqueness theorem for inverse variational inequalities is proved and two iterative algorithms are introduced to improve the previous relevant results.