Table of Content

25 October 2017, Volume 35 Issue 5

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Civil Aviation

Short-term air traffic flow forecast based on K-nearest neighbor algorithm

ZHAO Yuandi, CHEN Junfu, LIU Zeyu, SHENG Shouqiong, BAI Zhijian

2017, 35(5):  1-5,11. 

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It's worth to predict available short-term air traffic flow and reduce ATCO workload. An air traffic flow model is built based on K-nearest neighbor. First, relative errors from different K values are compared to determine the appropriate K values. After that, space parameter is introduced to improve the model. Then these three kinds of state vectors are combined and new K-nearest neighbor models are proposed including time dimension model, to route-time dimension model and time-space parameter model. Radar data within a certain sector is used to test K-neighbor model, showing out that K-nearest neighbor model with time-space parameter has minimum error,whose average error equals to 14.6%. Distance measuring method based on weight index can attain the goal of prediction accuracy optimization. Gaussian function can produce a better result under time parameter model while it is weaker when space parameter is taken into consideration. Statistics show prediction's error is only 13.94% under the index weight distance method of inverse function model with time-space parameter. The improved K -nearest neighbor model has applicability for different traffic situations and strong portability for complicated air traffic situation of China.

Design and implementation of improved correction algorithm for ADS-B based on FPGA

HU Tieqiao, LIU Danyang, LI Yangbo

2017, 35(5):  6-11. 

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ADS-B(automatic dependent surveillance broadcast)system is based on Mode S data link, which is widely used in the field of air traffic management owing to its low cost and high precision. However, ADS-B is vulnerable to interference. The very severe overlapping Mode A/C False FRUIT (replies unsynchronized to interrogator transmission)environment leads to bit errors of ADS-B signal. In order to solve this problem, an improved signal correction method is presented combining with serial operation characteristics and resource allocation of FPGA,CRC (cyclic redundancy check)and bit confidence for ADS-B signal. This method is designed and tested by FPGA platform. ADS-B signal test results of FPGA platform show that this improved method needs less hardware consumption and can improve signal processing speed without affecting the performance of error correction,ensuring the transmission reliability of ADS-B signal and making correction rate reaches 100%.

Multiple regression analysis of bleed valve regulation model based on SVM

CAO Huiling, WANG Xin

2017, 35(5):  12-16. 

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Aero engine's 2.5 bleed valve is an important mechanism to eliminate the risk of stall and surge. Stall and surge mechanism of axial-flow compressor are analyzed; after 30 trouble-free flights'QAR (quick access recorder)data analyzed and disposed, 3 flight sections'identification models of 2.5 bleed valve control models are set up by using SVMmethod. Applicating the models on a flight's QAR data, the bleed valve opening is calculated and compared with the actual value, proving that the models have higher accuracy and certain application value in the condition monitoring and fault diagnosis of aero-engine.

Research on energy consumption model of aircraft cabin

LIN Jiaquan, ZHANG Xuefeng

2017, 35(5):  17-21. 

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The unreasonable use of air conditioning load bridge has resulted in the inability to achieve energy saving and emission reduction and meet the requirements of cabin comfort control, aircraft cabin energy consumption model is constructed to predict the thermal load of aircraft cabin and achieve optimal control of bridge load air conditioning. Taking A320 aircraft cabin of TBIA as research object, various factors affecting cabin energy consumption is analyzed using heat balance method. Meanwhile, the meteorological parameter model, cabin envelope heat balance model and cabin air heat balance model are constructed. Heat transfer process is simulated and calculated, and the energy consumption of aircraft cabin at different time is obtained. Results provide a theoretical basis for future study of heat transfer comfort control of aircraft cabin and the energy saving control of aircraft air conditioning system.

Research on dispatching model of aircraft ground deicing

ZHANG Wei, LI Biao

2017, 35(5):  22-25,29. 

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In order to ensure the normal operation of airport's winter flights, ovoiding large-scale delays and accidents by deicing in time, a reasonable allocation of de-icing resource is required to maximize its utility. According to the deicing resource conditions and constraints of each participant, a heuristic scheduling model based on game allocation scheme is proposed, Which is able to achieve the highest resource efficiency, getting optimal solution of the whole scheduling model combined with the heuristic algorithm. Simulation with real operation data of Beijing Capital International Airport shows that the current model is better than single game model.

Combined forecasting model for passenger traffic volume on route

FAN Wei, ZHU Jiejie

2017, 35(5):  26-29. 

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Prediction of passenger traffic volume on route is one of the most important technologies of route network optimization. Traditional prediction method is based on passenger booking data. Generally used models include regression method, time series method and so on. However, these models consider less about the randomness of route flow data and the continuous growth of passenger volume. In order to solve these problems, combined forecast model is proposed based on regression method, which rely on two different reference periods.Construction of the model is divided into four stages: a. using load factor data to forecast and the visiting rate data of first-order accumulative smoothing makes the target curve becomes smooth and monotonous; b. using DOWmethod to predict the target year data; c. using the fitting curve of the adjacent point value to simulate the annual growth amount and build a forecasting model; d. taking average weighted value based on forecasting results from the above two stages, and establishing a new combined forecasting model. XMNPEK segment guest rate data of an airline in 2011-2015 is used to predict the load factor data for the first half of 2016. Comparedmwith traditional regression method and time series method, mean absolute error of the current method is reduced from 4.76 and 4.21 to 3.77 and the prediction accuracy is improved obviously.

Crew recovery time-space network model with various types of airplanes based on BP equation algorithm

ZHANG Qing, MA Yongxiu, YANG Zhengquan, CHEN Zengqiang

2017, 35(5):  30-35. 

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Aircrew scheduling recovery is an important part of airlines work. To abate the effect on flight operation planning from abnormal aircrew scheduling, various types of airplane crew recovery time-space network model is built up.Before the establishment, the objective constraint according to abnormal aircrew scheduling is analyzed.Meanwhile, the minimum of airlines operation aircrew recovery of multi-types of airplanes based on time-space network model and heuristic binary search algorithm on costs is the optimization goal. These models are applied to the actual operational data of some domestic airline to carry on the instance analysis. Minimum vertex cover and BP（Bethe-Peierls）equation algorithm are used to solve it. Results showed that the usage of minimum vertex cover and BP equation algorithm accelerate the aircrew scheduling recovery and increase the robustness of aircrew scheduling recovery. They adjust automatically when some factor changes. Whole-related structure is employed to help aircrew scheduling automatically adjust to urgent change of factors. This model is simple to operate and with strong systematicness to be used widely.

Design and implementation of civil aviation threat information early warning system

HAN Ping, WANG Jie, JIA Yunfei, NIU Yonggang, LI Shan, ZHANG Jundong, WU Yanquan

2017, 35(5):  36-40. 

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To monitor terrorists爷threat information from microblog and to improve the aviation security efficiency, an early warning system of civil aviation terrorist threat information is proposed. Topic crawler technique is used to collect microblog information from internet and evaluate their threats level with sentimental analysis method. Data visualization technology is also adopted to show the information for civil aviation public security department. Operation results show that the system runs stably and has good warning performance, which can prevent unsafe events effectively.

Engineering and Technology

Research on multi-source security log fusion method

WANG Shuang

2017, 35(5):  41-46. 

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In order to effectively find hidden attacks in network, taking multi-source log as research object, an improved weighted trust value D-S evidence theory is proposed to fuse logs. With data preprocessing and dynamic selfadaptive time interval threshold algorithm, super warning log is aggregated. Taking detection rates of different alarm events by safety equipment as evidence, the weights of alarm data are dynamically revised and fused.Comparison between experimental result and traditional D-S evidence theory algorithm indicates that the improved weighted trust value D-S evidence theory can improve the detection accuracy of network alarm event.

Cayley approach for 3D points registration in visual SLAM

ZHANG Hongyan, WANG Jingyan, ZHOU Lusha, WANG Binghui

2017, 35(5):  47-51. 

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An essential problem in SLAM system is to compute the 3D rigid body transformation of cameras, which aligns two sets of points when correspondences are known. The errors accumulated during the locating and mapping process result in the drift of scale for the pairs of points. The Euclidean transformation will be degraded into the similarity transformation due to the drift. A closed-form solution using Cayley transform is presented to estimate the similarity transformation between 3D corresponding points. The accuracy and robustness of the proposed Cayley approach are verified by simulation and error analysis. Apart from SLAM system, this approach is also suitable for 3D reconstruction and registration in computer vision.

Study on applicability implementation based on S1000D

ZHAO Hongli, CHEN Fei, GUO Qing

2017, 35(5):  52-55. 

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Applicability is an effective information filtering method, correctly using the applicability mechanism provided in S1000D, automatic processing of applicability can be achieved and the correct information can be delivered to the end user. Based on the study of S1000D applicability, the method of creating ACT, PCT and CCT is analyzed.Taking the civil aircraft as an example, the applicability data modules are written, and the rules and logic of applicability declarations and applicability test are analyzed. Studying result of applicability implementation mechanism can supply guiding reference for correct using of applicability in authoring technical documents.

Basic Research

Periodic inventory policy based on uncertain random demand

ZHANG Chunxiao, LI Runhui

2017, 35(5):  56-59,64. 

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In classic periodic inventory model, demand is usually considered as a random variable, but in production practice, the distribution function of new equipment demand cannot be obtained due to lack of historical sale data. So companies usually take product demand data of the original equipment as reference, and invite relevant experts to provide a subjective estimate to the unit demand distribution of new equipment. To describe the randomness and subjective uncertainty of the new equipment demand,chance theory is introduced and the demand is assumed as a uncertain random variable. A periodic order optimization model is built and an optimal analytical solution for profit maximization is obtained. Finally, numerical examples verify the feasibility of the current model, and a sensitivity analysis for parameters is taken.

Improved fuzzy rough set model

TAO Zhi, PAN Liping, HE Danfeng

2017, 35(5):  60-64. 

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Fuzzy rough set model is a generalization of classical rough set model. However, it has its own defects and shortcomings. An improved fuzzy rough set model is established on the fuzzy rough set model. One domain is expanded into two domains, and the membership function of fuzzy rough set is redefined. Therefore, the new model's rough approximation accuracy and application range are effectively improved. This new model is proved to be effective and practical by theory and case analysis.