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Table of Content

    25 February 2017, Volume 35 Issue 1
    Civil Aviation
    Atmospheric turbulence spectrum width estimation based on optimal processor
    LI Hai, JIANG Ting, LU Xiaoguang, ZHOU Meng
    2017, 35(1):  1-6. 
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    Turbulence detection of airborne weather radar is mainly based on the estimation of spectrum width, which is a crucial step. Besides the movement of atmospheric turbulence, the azimuth and beam width of the antenna as well as the motion of airborne platform may also lead to spectrum width increase, which would affect the accuracy of spectrum width estimating result for real turbulence. A method of turbulence spectrum width estimation based on space-time optimal processor is proposed to solve the above problem. The proposed algorithm can suppress the influence of interference factors with space-time adaptive processing principle and achieve an accurate estimation for the turbulence spectral width. Simulation result proves the method爷s effectiveness.

    Numerical analysis of thermal comfort inside aircraft cabin and departure lounge bridge
    HAO Guihe, LIANG Xiaobei
    2017, 35(1):  7-10,21. 
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    Bridge-load air conditioning is used to maintain the thermal comfort inside aircraft cabin and lounge bridge when an aircraft docks at airport. Reasonable bridge-load air conditioning control should keep the required thermal comfort, and realize energy saving for environmental protection. Numerical simulation (CFD) of aircraft cabin and lounge bridge environment including temperature field and velocity field is made. ADPI (air diffusion performance index), irregularity coefficient of temperature and speed are chosen as thermal evaluation indicators to study the relationship between fresh air supply speed of bridge-load air conditioning and thermal comfort inside the aircraft cabin and lounge bridge. CFD simulation results show that only when the speed of air supply is set appropriately,the ADPI reaches maximum. With the optimum air supply speed, different modes of air supply have different effect. Uniform air supply mode is better than central air supply mode. The results will improve bridge-load air conditioning control.

    Study on effect of hydrothermal environment to civil aircraft composite laminates strength
    JIA Baohui, LIU Xuan, LU Xiang, LIN Yueguo
    2017, 35(1):  11-16. 
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    Based on modified stiffness theory, the hydrothermal effect on composite laminates of civil aircraft is studied.Specifically, the strength of unidirectional composite board T300/3238A under five kinds of hydrothermal conditions and laminate CCF300/5228 under ghydrothemal environment and normal dry state are studied with mathematical model of stress-strain constitutive equation, Hoffman strength theory and stiffness correction method. Lastly, initial layer cracking load and ultimate lod are calculated and then compared with experimental data, the over all failure process, failure load, and strength impact in hydrothermal environment of this composite laminate can be predicted accurately. Combinng with experiments and theoretical method, this approach is feasible to analyze the hydrothermal effect on composite laminates in civil aircraft maintenance applications.

    Environmental damage assessment for military aircraft metal structure under service
    QING Guanghui, XIONG Bang, WANG Weize
    2017, 35(1):  17-21. 
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    The maintenance program compiling of military aircrafts is different from civil aircrafts because of the special working environment of them. On the basis of civil aircraft metal structure environmental damage modeling, the relevant standards for military aircraft are studied. The main factors about the environmental damage of military aircraft metal structure are analyzed thoroughly and the military aircraft metal structural damage assessment model is created. G1 method is used to determine the weight of each index which is modified by the expert weight. By using the above methods, the damage level of a certain part under three kinds of services environments is obtained by taking into account the military aircraft service. Finally, the model which is called G1-Grey relational coefficient is used to verify the method.

    Airport surface traffic simulation based on Flexsim
    XING Zhiwei, LI Shijiao
    2017, 35(1):  22-25. 
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    Flexsim is applied to simulate and analyze the airport surface traffic situation. Through analysis of airport surface traffic operation mechanism, entity objects in Flexsim are mapped to different components of the airport scene traffic by using object oriented discrete virtual reality simulation technology. Then the whole process of airport traffic system operation can be demonstrated by visual virtual reality 3D animation based on Flexsim simulation development platform. Experimental results show that the relationship between various components of the system is displayed vividly by using the proposed method to simulate the airport scene traffic. The bottleneck of system operation and the key influencing factors can be found quickly combined with data statistical analysis function of the Flexsim simulation platform. This method provides effective technical means for airport operation strategy optimization.

    Research on intelligent data distribution model of aviation logistics
    WANG Tiankai, LUO Yunsheng, DING Jianli
    2017, 35(1):  26-31. 
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    In the field of aviation logistics, in order to allocate mass data to interested information customer effectively,and implement information interaction and resource sharing, it is crucial to establish an industry-level data exchange platform for the operation of aviation logistics enterprise. Data exchange platform iLink for aviation logistics is researched and designed based on SOA. The data distribution method is based on dynamic priority of 'first come first serve'algorithm, which can realize automatical transmission converts among different message formats and intelligent distribution to participants according to the format and content of aviation logistics data packets.Experimental results show that the method has good performance in terms of sending and receiving data.

    Study on polymer grouting material in runway reinforcement
    CHENG Guoyong, HUANG Xudong, HOU Dongwen
    2017, 35(1):  32-35,46. 
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    Polymer grouting technology has been widely used in civil engineering, roads, railways and other existing building foundation reinforcement. Due to the special requirements of airport pavement construction of non-stop flight, this technology has not been applied in the field of airport engineering. Some polymer materials are chosen as subgrade reinforcement materials, and the compressive strength, elastic modulus, maximum expansion force with the change of material density are studied. Test results show that when the density of polymer solidified slurry increases from 86.72 kg/m3 to 290.66 kg/m3, the yield compressive strength increases from 1.55 MPa to 11.61 MPa, the elastic modulus increases from 21.25 MPa to 106.17 MPa, and the stress-strain relation appears brittle tendency with the increase of density. The polymer solidified slurry density is between 92.13 kg/m3 and 420.36 kg/m3,and the maximum expansion force is between 0.11 MPa and 1.12 MPa. The greater the density is, the greater the maximum expansion force becomes, and the faster the growth rate of expansion force is. Generally, within 60s, the expansion force will be able to reach the maximum expansion force by about 90%. The conclusion can provide reference for dealing with the application of polymer grouting reinforcement technology in airport non-stop flight.

    Fatigue life analysis of composite pavement with multiple overlay
    LI Longhai, YANG Ru
    2017, 35(1):  36-41. 
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    In order to solve the problem that the fatigue life of overlay is far lower than the design value, two ABAQUS finite element models are established to analyze the mechanical response of the road construct, one is composite pavement with multiple overlay, the other is pavement overlaying the same thickness of asphalt concrete, which can exclude the possibility that the attenuation rule of fatigue life is completely caused by overlay thickness.Calculation result indicates that the layer service life decrease with the increase of overlay times, which shows that the mean fatigue life of the overlay is not improved with the addition of asphalt concrete, which should be considered when making an overlay decision.

    Experimental study on affection of loose dowel to load transfer of pavement joints
    ZHANG Runfeng, CUI Xiaoyun, YANG Jian
    2017, 35(1):  42-46. 
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    The cement concrete pavement slab structure model is poured by a certain scale, and the joint is provided with dowels and have different loosening lengths. Using different loading levels to determinate relevant data, load transfer coefficient and mechanical characteristics between dowel and pavement concrete under different loose lengths are studied. Results show that when load is small, the joint load transfer coefficient does not change significantly; When it reaches 1~3 kN, load transfer coefficient increases significantly; When it is bigger than 5 kN,load transfer coefficient is relatively stable. When dowel loose gap length reachs 0~10 cm, concrete strain joints,load transfer coefficient rod and concrete interface gradually decrease as the loose length increases, shear strain of dowelincreasesfirstlyandthendecreases.Sincetheloosegapiswiderthan10cm,anyindexhasnoobviouschange.

    Engineering and Technology
    Asynchronous motor vector control system based on fuzzy adaptive algorithm
    HE Yongbo, XIA Wenqing, DONG Yushan
    2017, 35(1):  47-51. 
    Asbtract ( 1960 )  
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    In the asynchronous motor vector control system, the parameters of conventional PI speed regulator do not adjust to the change of motor real-time speed. Considering about this, an optimal design method for real-time auto tuning of parameters is proposed. Based on the analysis of AC asynchronous motor mathematical model and vector control system, the speed regulator is improved. Meanwhile, the asynchronous motor vector control system based on fuzzy adaptive PID speed controller is constructed so that the self adjustment of speed regulator parameters can be realized. The speed strategy has fast response without overshoot and oscillation, and improves the anti-disturbance performance. Simulation show that the controller effectively improves the dynamic and static characteristics,robustnessand selfadaptive ability of the system, aswell as the overallsystem control performance.

    Parameter analyses of transmitting circuit in digital ultrasonic inspection instrument
    ZHAN Xianglin, SHI Zhichao
    2017, 35(1):  52-56. 
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    Transmitting circuits are introduced at first. And then the system principle is explained. On the basis of theoretical calculation, detailed relations between circuit resistors, capacitors and exciting pulses are concluded. Finally,transmitting circuit is simulated and tested, and experiment results show that the designed circuit can produce ideal exciting pulse and has practical value.

    Research on HDFS visualization and its application in QAR data
    FENG Xingjie, WU Xiyu
    2017, 35(1):  56-59. 
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    As an open software framework developed by Apache, Hadoop provides the distributed processing of large data
    sets that across clusters of computer by simple programming models. It is designed to scale up from single servers to thousands of machines, each offering local computation and storage. And now a wide variety of companies and organizations use Hadoop for both research and production. The core modules of Hadoop are HDFS (Hadoop distributed file system)and MapReduce distributed programming model. An HDFS cluster primarily consists of a NameNode that manages the file system metadata and DataNodes that store the actual data. However, the management issues of HDFS cluster resources has became urgent. There is a web page to browse HDFS provided by Hadoop, but this interface of HDFS is not friendly for users because command line is the main method to achieve operation of the document now. In order to use HDFS conveniently, using the struts2 develop framework and JFreeChart, the architecture of HDFS is researched and then an HDFS visualization system is designed based on web interface. And the development efficiency based on Hadoop for QAR data is improved.

    Basic Research
    Effects of impurity concentration on ductility of Mn-doped γ-TiAl alloys
    SONG Qinggong, JIANG Qingjie, GU Weifeng, HU Xuelan
    2017, 35(1):  60-64. 
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    Using the first-principle method based on density functional theory, Mn-doped γ-TiAl alloy systems, of which the concentrations of Mn substituting Ti or Al are 1/54, 1/36, 1/24 and 1/16 respectively, have been investigated with CASTEP aimes at improving its ductility. Meanwhile, the structure, energy, plastic and electronic properties are calculated and analyzed. The average atom formation energy of all the doped systems is negative, indicating the energy stability of each system. The Mn-substituting-Al systems have got a lower formation energy, which shows that the Mn tends to substitute Al. Results of both the axial ratio and elastic modulus show that doping with Mn can improve the ductility of γ-TiAl alloys by substituting Al, with Ti12Al11Mn showing the best ductility. Comparison of the overlap population of Ti12Al11Mn and pure γ-TiAl indicates doping with Mn can weaken the anisotropy of the covalent bonds in γ-TiAl systems, which contributes partly to the ductility improvement of γ-TiAl alloys.