Journal of Civil Aviation University of China

Accuracy and integrity of ground-based augmentation system based on GPS/BDS

NI Yude, LU Lu, LIU Ruihua

2017, 35(6): 1-6.

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The accuracy and integrity of GBAS (ground-based augmentation system)are two important indices to describethe RNP (required navigation performance)of GBAS. The Hatch carrier phase smoothing pseudorange algorithm for GBAS accuracy enhancement is analyzed and the integrity of GBAS in H0 and H1 hypotheses is studied. Based on GPSdata provided by US CoastGuard Navigation Center and real-time data of BDS (Beidou navigation satellite system), the simulation of GBAS accuracy and integrity enhancing algorithm are carried out. Experiment results show that the accuracy and integrity of GBAS based on GPS or BDS single constellation and GPS/BDS double constellations can meet the requirement of CAT I precision approach, and GBAS accuracy and integrity in double constellations environment are better than those of single constellation corresponding performance.

Passive calibration of gain and phase errors for ADS-B anti-jamming antenna array

WANG Wenyi, ZHU Te, WU Renbiao

2017, 35(6): 7-10.

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The real array manifold and ideal array manifold may be different due to the gain and phase errors of array, and performance of algorithms will be sharply affected by the gain and phase errors. A passive calibration algorithm is proposed to calibrate the gain and phase error of the ADS-B system array. In the proposed method, one of the sensors can be used to obtain the positions of aircrafts, and the position of array antenna can be measured, then the DOA of pilot source is computed through coordinate system transformation, and the array errors are calibrated by using direction information. Gain and phase errors can be accurately estimated by the proposed method, and the performance of algorithms is effetively improved. Performance of calibrated array is highly improved. The extra pilot sources do not need to be set manually, thus the equipment complexity is reduced. Simulation results prove the effectiveness of the proposed algorithm.

Construction and implementation of ACARS ground station test environment

HU Tieqiao, SONG Demin, LI Yangbo

2017, 35(6): 11-15,25.

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The basic building and implementing methods of ACARS ground station test environment is introduced. ACARS link layer protocol is analyzed according to ARINC 618 specification, implementing ACARS ground station basic function. First of all, MFC is used to make simulated airborne CMU and simulated ground station DSP on Visio Studio 2013 platform through TCP/IP communication. Simulated airborne CMU and ground station DSP are respectively connected with VHF transceiver software radio platform through serial port to construct a real ACARS communication environment sending and receiving messages. Experiment proves that the simulated ground equipment can realize basic function of real ACARS ground station, and also lay foundation for ACARS radio station localization.

Improved Chameleon algorithm based on DPC algorithm and module density

GONG Fengxun, XING Chen, MA Yanqiu

2017, 35(6): 16-21.

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Based on Chameleon algorithm, DPC algorithm and mudule density function, a hierarchical clustering algorithm based on density is proposed. In the first stage of Chameleon algorithm, DPC algorithm is used for data processing. In the second stage, when clusters are merged with the approximation function, module density that characterizes the similarity of data within a cluster is introduced. When module density achieves maximum,termination condition and final clustering result are obtained. An improved Chameleon algorithm is used to establish dynamic model, which can automatically determine the termination condition, and can identify many shape clusters, helping traditional Chameleon algorithm find the clustering end and be less sensitive to the initial parameter setting.

Analysis on impact of RNP AR APCH aircraft noise

WANG Wei, WANG Zhen

2017, 35(6): 22-25.

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To analyze whether it has the advantages to reduce the noise of RNP AR APCH by comparing the aircraft noise effects of normal approach with RNP AR approach. The dispersive aircraft tracks in normal approach can be classified into several groups by the difference of aircraft types and turning times. Then the multiple tracks are input instead of nominal track to INM for calculating the noise. A more accurate assessment of aircraft noise impact can reflect difference between the two procedures after replacement. Result shows that total impact area of aircraft noise is not reduced, the impact area of individual noise levels is possible increased, and the range of noise in the turning region extends along the nominal flight path away from the airport and the influence width of nominal track is obviously reduced by implementing RNP AR APCH.

Test simulation study on flutter characteristics of airfoil

YU Zhijing, HUA Zhen, WANG Shuo, WANG Wei, WU Jun, ZHUGE Jingchang

2017, 35(6): 26-30.

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Aircraft stalling, air parking and airfoil flutter are three important factors that affect aircraft flight safety. It is always a critical issue in the field of flight data to fully carry out the flutter airworthiness measurement. To reduce the workload of flutter airworthiness measurement and to make the vibration test point selection more targeted, an analysing method aiming at the flutter characteristics of airfoils are proposed basing on fluid solid coupling,taking B737-800 as study object. Firstly, using coupled flow field to compute the wing mode, then by mapping coupled modes to the harmonic response and transient dynamics analysis of the wing, it would access to the regularity of flutter characteristics of the wing, thus the flutter danger points would be found out. Analysis of simulation results show that the wing deformation is mainly located in the 22%~60% wingspan area and 85% wingspan to wingtip, which is consistent with the selection of flutter measurement position in the research center of Langley. The changing trend of wing twist along semispan in flutter test simulation is matched with test results of Langley, thus it would provide reference for the analysis of wing flutter failure as well as the selection of excitation test points for the measurement of flutter airworthiness.

Hybrid model of time series for airport energy prediction

WANG Li, ZHANG Chao

2017, 35(6): 31-35.

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In order to solve the problems of single forecasting models such as low accuracy and easy falling into local optimization, a hybrid model is presented basing on time series analysis method and SVM (support vector machine), which could improve the predicting accuracy. An improved chaotic time series model is presented.
Chaotic time series model, SVM and hybrid model of time series are used for the modeling and simulation of energy consumption of Tianjin Binhai International Airport. Evaluation of the three models is based on the estimation of average behavior of mean squared error. Experimental results show that the hybrid model is an effective way to improve the forecasting accuracy achieved by any one of the models separately.

Optimization and allocation research of hub airport pavement fleet deicing resource

XING Zhiwei, CHEN Yaxiong, LUO Qian, CHEN Fei

2017, 35(6): 36-40,51.

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The airport deicing rate has far-reaching influence on airport operating quality as well as flight punctuality rate.In view of the problem about fleet resource optimization and allocation for hub airport pavement deicing, characteristics of airport deicing and fleet operation are analyzed, performance capacity-cost multi-objective optimization and allocation model about airport deicing is built, standard article swarm algorithm is improved to solve the model. Based on the deicing case of a large hub airport, the model is simulated and analysed, the fleet resource optimization and configuration results are obtained under different snow conditions. Results show that the model configuration mode is superior to the experience configuration mode in operation efficiency and cost.

Mechanical behavior study of aircraft ground turning motion

CAI Jing, CHANG Huan, LI Yue

2017, 35(6): 41-45.

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With the increasing size of civil aviation aircraft, the lateral thrust on the surface course is getting bigger and bigger because of the large weight and low speed when turning on the ground. The current pavement design specification, especially the asphalt concrete pavement design specification only considers the vertical force and ignores the lateral force, but the airport runway system has many corners, so it is necessary to consider the lateral force during the design process of these parts. And the method of front wheel manipulation turning is the main mode of civil aircraft ground turning. Because the aircraft will be influenced by complex forces in the ground turning process, which will be affected by the crosswind, pavement roughness, pilot control way and the plane speed and other factors, so in order to simplify the analysis, reasonable assumptions are made. It is considered that when the aircraft is in the low speed process of turning on the ground, the steering angle of the front wheel is constant. The instantaneous motion mode is circular motion whose radius is fixed. The simplified formula of the specific value of lateral and vertical force is obtained through analysis, which will make the lateral force calculation much easier, and it is found that the lateral force of wheels is not equal in the process of turning. For the model B737-800, the ratio of lateral and vertical force of the four tires of main landing gear is 1.33:1.29:1.04:1, and the lateral force of the outermost tire relative to the center of rotation is the biggest. The lateral force of the innermost tire is the smallest, a drop of 33% than that of the outermost tire.

Study on oscillation of n-decane in heating pipes by heat load change

TIAN Jing, HOU Yu, ZHOU Weixing, XIAO Xuefeng, WANG Guangfei

2017, 35(6): 46-51.

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Experimental study found that the supercritical endothermic hydrocarbon fuel system in supply process has produced oscillation. In order to further understand the mechanism of this phenomenon, two kinds of wall heat load regulation programs, linear change and step type change are prepared by using the decantation of the main component of hydrocarbon fuel as research object. Results show that the faster the wall heat load changes, the greater the overshoot value of outlet mass flow, the more significant temperature and velocity oscillations become. The larger the amplitude of thermal load is, the greater the oscillatory phenomenon of n -decane temperature field in quasi-critical range become, the greater the o scillation amplitude of velocity field and oscillation frequency are. The rate of change and amplitude of wall heat load can lead to oscillation of n-decane in quasi-critical temperature range, which can cause instability of fuel system supply.

Effect of salt solution on compressive strength and resistivity of cement soil

HUO Haifeng, WANG Wenbo

2017, 35(6): 52-56.

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Mechanical parameters of cement soil will be affected by the environment of salt solution during the curing process. Through strength and micro test, the variation law of compressive strength of cement soil under different corrosion grades is discussed. Results show that with the increase of sulfate ion concentration, the compressive strength increases first and then decreases, and the compressive strength will be less than that of clean water under strong corrosion grade. With the decrease of magnesium concentration, the pH value increases, soil compressive strength is increasing. There is a good linear relationship between resistivity and compressive strength of cement soil, and there is a positive correlation between the two indices.

Research on flexible direct current transmission based on WNN control for mountain wind farm

YAN Jing, WANG Lingmei

2017, 35(6): 57-60,64.

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Aiming at the significant characteristics of randomness and volatility of a wind farm, there exist problems of steady-state error and slow response speed under conventional PI control based on MMC flexible HVDC technology. WNN (wavelet neural network)is applied to the outer ring of voltage control due to its characteristic of approximating any nonlinear function. PSCAD/EMTDC and Matlab/Simulink are used to build system of electrical part and WNN control part respectively. Simulation results show that WNN control strategy has good dynamic characteristics and better guiding effect for large-scale renewable energy grid.

A* algorithm based on random walk

LIU Haohan, GUO Jingjing, LI Jianfu, FENG Mei, HE Huaiqing

2017, 35(6): 61-64.

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A* algorithm based on random walk combining with Monte-Carlo random walk is proposed to solve the plateau exploration in A* algorithm. When the A* algorithm falls into the plateau exploration, a random walk algorithm is employed to help it escape from the plateaus. In addition, a new method is proposed to test plateau exploration.The phenomenon is named plateau exploration as it continuously expand states n times without reducing the heuristic value compared with last states'expanded on last expansion. Experimental results prove the effectiveness of the improved A* algorithm.

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