Table of Content

05 June 2022, Volume 40 Issue 2

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Civil Aviation

Static source error correction of civil aircraft based on stepwise regression analysis 

ZHANG Peng , BAI Yanhui

2022, 40(2):  1-5. 

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Aiming at the static source error of civil aircraft air data system, the correlation between error and main influencing factors is analyzed by stepwise regression analysis, the static source error correction model is studied and an effective error correction scheme is proposed to improve the accuracy of static pressure measurement. B777 aircraft model is taken as an example, the consistency between 3D modeling created by Solidworks and the real machine experiment is verified by computational fluid dynamics(CFD) simulation method. Static pressure measurements under different flight conditions were obtained through simulation and post-processing, and the errors are corrected according to the error correction scheme proposed by the stepwise regression method. The error of the calculated airspeed according to the revised static pressure solution is less than 3%, which meets the requirements of airworthiness clause. The revised scheme has high practical application value, and can provide reference for the design of static pressure source error correction scheme for civil aircraft.

A study on the rainstorm that causes flight delays——An event of rainstorm over Sichuan Basin on July 11, 2018

LIU Haiwen , HOU Shaoyu , MAO Jiangnan , GONG Yuanfa

2022, 40(2):  6-13. 

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Rainstorm is one of the main bad weathers that cause large-scale flight delays. The rainstorm in Sichuan Basin on July 11, 2018 (7.11 rainstorm hereafter) was analyzed using the national hourly encrypted precipitation data, National Centers for Environmental Prediction (NCEP)-final reanalysis data(FNL) and FY-2E infrared cloud chart, by the methods of weather analysis and medium scale numerical simulation.The results showed that the heavy rainfall on July 11 occurred at 02 ∶ 00 am and 08 ∶ 00 am on the 11th. The former is a night rain, and the latter is a daytime precipitation. At 500 hPa, the Baikal Lake vortex extends to the Westerly trough of Sichuan Basin, at 700 hPa, the Southwest vortex and shear line located in the basin, the West Pacific Subtropical High (WPSH) and typhoon Maria are the main weather patterns that affect the 7.11 rainstorm. The mesoscale numerical model weather research forecast(WRF) can better simulate the spatial distribution of the 24-hour accumulated precipitation, but the simulation result of daytime precipitation is not good. In addition, the duration of the southwest vortex simulated by the model is shorter than that of the actual situation.

Identification method for non-normative NOTAM based on NLP 

XIANG Heng , ZHANG Chi , LI Meng

2022, 40(2):  14-18. 

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Aiming at the non-normative problems of item Q and item E in the notice to airmen（NOTAM）, a method of text similarity calculation in natural language processing is proposed to identify the non-normative NOTAMs. Firstly, translating the item E into Chinese by statistical machine translation method, and translating the item Q into Chinese by establishing a database. Then, Word2vec model is used to calculate the similarity between the two sentences, and the recognition standard of non -normative NOTAMs is established. Based on the similarity calculation of item Q and item E in 500 collected NOTAMs, 0.7 is set as the benchmark of non -normative NOTAMs. The data test shows that the recognition accuracy of NOTAMs is 96.2%, which verifies the feasibility of non-normative NOTAMs recognition method based on NLP.

Aptitude assessment of newly certified professional air traffic controllers at EC and PLC consoles

JIANG Nan

2022, 40(2):  19-23. 

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In order to clarify the newly certified professional controller’s aptitude at executive controllers(EC) and planning controllers(PLC) consoles, firstly, we established a comprehensive assessment index system to test the new controller’s ability based on analytic hierarchy process(AHP). Several senior controllers scored the performance of the new controllers at both the EC console and the PLC console. The result shows that the comprehensive performance of the new controller will significantly be improved with the increase of the time of independent work, meanwhile the performance of controller at the EC console is always better than that at the PLC console. Secondly, the number of no-consequence violations at different consoles of new controllers is counted. The result shows that the number of no-consequence violations at EC console is less than that at PLC console. Finally, based on the above evaluation results, the performance of new controllers at EC console is generally better than that in PLC console. This result can provide reference for the work arrangement of newly certified controllers. It is suggested that on the premise of ensuring safe operation, newly certified professional controllers should be arranged to work at EC console more often, and the training for those at PLC console should be reinforced appropriately.

Research on methods of identifying unruly passengers in civil aviation 

CAO Weidong, XU Xiuli

2022, 40(2):  24-30. 

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Aiming at various unruly behavior of civil aviation passengers, such as making calls and disturbing other passengers, a Tag+Bi-LSTM+CRF neural network model is proposed to obtain the identity of unruly passengers. Considering that there are multiple entities in a sentence in a civil aviation text record, the pattern of entities appearing in the sentence may contain useful semantic information. The characters in the named entity recognition are marked with the BIOES method and then connected in series with word embedding and position embedding for the purpose of enriching input expressions. First, use the Yedda tool to label the entities at random in record text of civil aviation passengers, and combine word embedding and location embedding as input to the model. Second, the bi-directional long short-term memory(Bi-LSTM) model is used to obtain the contextual features of the sequence text. Then, the sequence labeling result is obtained through the conditional random field(CRF) model. Finally, a dropout layer is added into the input layer and Bi-LSTM layer to prevent overfitting. The experimental results show that the accuracy, recall rate and F1 of the unruly passenger identification are as high as 96% or more, and it can effectively obtain information of the unruly passengers with regard to behavior, grade, punishment, and time limit.

Research on requirements validation method of civil aircraft customer service engineering development

XU Qiang

2022, 40(2):  31-35. 

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For the development of civil aircraft based on requirements, the correctness and completeness of the defined requirements are crucial to the entire development process. The current research and application work are not enough with regard to defining the principles and methods of customer requirements validation. Through the research and exploration of the method of validating the customer requirements for the civil aircraft, we are more assured of this method and its selection principles along with the tools of validation. The final customer service product thus developed can meet the requirements and expectations of stakeholders.

Airworthiness Column

Approach of strain based rigid-elastic coupling modeling for flexible aircraft 

YANG Jianzhong, LU Yong, YANG Shibin

2022, 40(2):  36-41. 

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As the proportion of structural weight of advanced civil transport aircraft gets smaller and smaller, the aircraft shows higher flexibility, traditional rigid model assumption may lead to large errors in the study of aircraft flight control. Considering the large deformation movement of the wing, strain based nonlinear beam model is used to establish a coupling model of structural dynamics and traditional rigid flight dynamics. The aerodynamic parameters of the rigid-elastic coupling aircraft equivalent to the rigid model are obtained by the equivalent method, and the differences between the traditional rigid model and the rigid-elastic coupling model on aileron and vertical gust response are compared through simulation. The results show that the elasticity of the wing will reduce the aileron efficiency by 18.77% during the roll maneuver. Under the action of vertical gust, the wing root bending moment predicted by the rigid-elastic coupling model is 8.35% lower than that by rigid model, and elastic motion of the wing also has an impact on rigid motion.

Study on airworthiness compliance of large aircraft anti/deicing system based on CS25

WANG Gang, ZHENG Li, FENG Chao

2022, 40(2):  42-46. 

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To ensure the safety of large aircraft flying through clouds, large airliners should design and install wings, windshields and nacelle anti/deicing systems. First of all, based on the 3 parameters that affect icing intensity: liquid water content(LWC ), ambient temperature and median volume diameter(MVD), and in combination with appendixes C and O of CS25, this paper describes 4 kinds of icing envelops’ characteristics. Secondly, based on the current design level of anti/deicing system, the airworthiness terms of the anti/deicing system are reviewed with 25.1420(a)(1) asthe certification target. Finally, based on the CS25 and AC-25-28, airworthiness compliance analysis is carried out according to the characteristics of the aircraft's various systems, which provides a reference for the design and airworthiness certification of the large passenger aircraft anti/deicing system.

Engineering and Technology

Design of a new non-contact permanent magnet wall-climbing robot 

JIANG Dezheng , ZHU Bing , REN Wenfeng , FU Xingwei , ZHAO Yanzheng

2022, 40(2):  47-51. 

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In order to improve the adsorption capacity of the wall climbing robot at arbitrary position in the steel pipe, a design scheme for novel non-contact permanent magnetic wall-climbing robot mechanism is proposed, starting with the structural design and combined with the structural characteristics of a certain type of steel pipe. Firstly, the design of permanent magnetic adsorption module is introduced in detail. Secondly, according to the geometric position change of the wall climbing robot in the steel pipe, the change of the adsorption force is calculated, and the static constraints in the limit case are analyzed. Finally, by simulation and field test, the wall climbing robot can realize reliable adsorption at arbitrary position in the steel pipe under large load.

Further discussion on coefficients of Terzaghi's ultimate bearing capacity 

CHENG Guoyong , WANG Zhaoyuan , LIU Dahai

2022, 40(2):  52-57. 

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The ultimate foundation bearing capacity is a classic problem of soil mechanics, with a wide range of influ－ ence and a extensive application. The currently adopted Terzaghi’s ultimate bearing capacity formula fails to provide an analytical solution for the parameter Nγ. The empirical formulas proposed by the predecessors are quite different, with unclear basis, it is difficult to get unified. Thus the author obtains the analytical solution of Terzaghi foundation bearing capacity coefficients of Nγ, Nq and Nc with the principle of limit equilibrium, verifies the correctness of the coefficients Nq and Nc along with that of the parameter Nγ in theory and expands the scope of application of Prandtl-Reissner’s formula on the relationship between Nq and Nc. The research result provides useful references for the study and research on the basic theory of bearing capacity.

A stress recovery method based on the programme of Gauss points in adjacent elements

QING Guanghui, XU Jingyu

2022, 40(2):  58-64. 

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For the two-dimensional incompatible 4 -nodes quadrilateral element model, a new isoparametric element is constructed using the Gaussian points in adjacent elements around the nodes, and the stresses of the nodes included in the element can be calculated directly. This method avoids the calculation process of average value of stress results of adjacent elements at common nodes in the common extrapolation method and the program is easier. A simple linear interpolation method is used to calculate the boundary node stress from the internal node stress of the model. Examples show that the accuracy of the stress in the model is higher than that of the extrapolation method, and the convergence analysis of the stress proves the correctness and effectiveness of the method, which is a method with universal applicability. When the method is used to analyze the stress concentration problem of plate with holes, the stress concentration factor obtained is closer to the theoretical solution than that of the extrapolation method.