Table of Content

25 February 2021, Volume 39 Issue 1

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Civil Aviation

Flight status conformance assessment of fly-by turns based on time tolerance

WU Renbiao, AN Li, ZHANG Zhe, WANG Peng

2021, 39(1):  1-5. 

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Flight status changes during maneuvering flight cannot be effectively identified by common fixed distance threshold assessing method, in senarios with large amount of monenvering flight. To resolve this problem, aiming at the reasonable time variation during flight operation, and according to the initial turning time distribution, the fly-by turning position distribution model is built by using Monte Carlo method and then the flight status conformance assessing method basing on time tolerance is obtained. Practical flight data are used to verify the effectiveness of the current method and the results show that: this method can effectively demonstrate the fly-by turning flight status conformance extent; compared with fixed distance threshold assessing method, this method can effectively warn abnormal turning status in advance and improve the effectiveness and rationality of assessing results.


Arrival aircraft route planning based on arrival procedure selection

SONG Xiangbo, MOU Lei, YANG Yue

2021, 39(1):  6-10. 

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In order to improve the efficiency of arrival aircraft in the terminal control area and solve the increasing flight delay, a route planning model for arrival aircraft based on PBN is established and simulated with the goal to realize conflict pre-allo cation. Experimental resulf shows that, the simulated number of aircraft entering terminal control area is greater than the actual hourly maximum flow at each en-try point after the optimized allocation of the arrival procedures. On the basis of improving the efficiency of aircraft entering the terminal control area and reducing the number of flight conflicts, this method can assist controllers to sequence arrival aircrafts and reduce their workload.


SWIM network routing mechanism based on NDN

WU Zhijun, XU Xinran

2021, 39(1):  11-16. 

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In order to reduce the data transmission delay and the high load of data source node, NDN routing mechanism is introduced into SWIM network, naming the information in a hierarchical way to improve the aggregation degree of the route. Caching strategy is adopted to improve the response speed to the same request. Aiming at the possible node failure, a rerouting mechanism is proposed to reduce the transmission delay. Simulation results show that the proposed mechanism can achieve fast response to the same information request and reduce the average load of network. When node failure appears, the rerouting mechanism can effectively reduce the network delay as well as the average number of retransmissions, and reduce negative impact on network performance.


Crowd counting algorithm based on multi-scale feature fusion via adversarial neural network#br#

HAN Ping, LIU Zhanfeng, JIA Yunfei, NIU Yonggang

2021, 39(1):  17-22. 

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The crowd counting algorithm of adversarial neural network based on multi-scale feature fusion is proposed to solve the difficulty in crowd feature extraction and information loss in feature fusion. First, shallow crowd features at different scales are extracted through multi-scale feature extraction structure with different size convolution kernels extracts. Next, shallow crowd features and deep-level crowd features of the convolutional network are connected through residual structure to achieve the fusion of crowd features at different scales and depths.Finally, the alternate learning between generator network and discriminator network is realized through adversarial method in order to generate high-quality crowd density maps. Experimental results on two datasets of ShanghaiTech and UCF_CC_50 show that this model can greatly improve the accuracy and robustness of crowd counting in complex crowd environments compared with traditional neural network models.


Parameter identification of magneto-rheological damper Bouc-Wen model

YANG Yonggang, DING Youchuang

2021, 39(1):  22-27. 

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It is not easy to identify the parameters of magneto-rheological damper dynamic model. Therefore, it is proposed to build a Bouc-Wen model in Simulink, choosing nonlinear least square algorithm to conduct iteration; relation between current and damping force controlling parameters is determined by using the curve fitting toolbox parameter estimation, and then all the parameter identification results are determined. Finally, Bouc-Wen model is validated by the test data of other amplitude frequencies. Results show that there exists high fitting degree between test results and simulation results, proving the effectiveness of the current method in parameter identification.


Development of parameterized modeling simulation platform for magnetorheological shimmy damper#br#

TIAN Jing, LI Xiaofei

2021, 39(1):  28-33. 

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There exist problems such as large similar work, complex finite element analysis process and long R&D cycle of the designing process of magneto-rheological shimmy dampers. Basing on the parameter description of magnetorheological damper parts‘sizes, the parameterized modeling and simulation platform of magneto-rheolo-gical damper structure is built by secondary development of CATIA and ANSYS in VB 6.0 environment. Simulation results show that this platform can quickly model the damper and conduct simulating analyses on the magnetic field distribution of dampers with different size parameters, which simplifies the designing process and shortens the R&D cycle.


Influencing factors of aircraft dynamic response under unevenness excitation

YUAN Jie, WU Yifang, ZHANG Zhekai, LIU Shifu

2021, 39(1):  34-40. 

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The runway roughness analysis software ProFAA developed by FAA is used to run simulation on common commercial aircraft types such as B727, B737 and B747 under random excitation, cosine excitation, and measured runway excitation, studying the relation between aircraft dynamic response and speed, wavelength, amplitude as well as roughness indices. Simulation results show that: the aircraft dynamic response is proportional to the taxiing speed and excitation amplitude; aircrafts are more sensitive to the unevenness excitation of medium and long waves, and the value of sensitive wavelength is related to the aircraft type and taxiing speed; the increase of roughness indices aggravates the dynamic response of aircraft, but the correlations among them are different, BBI (Boeing bump index) has the highest correlation with the dynamic response of aircraft.



Assessment system construction and trend foresight of UAV ground impact risk#br#

HAN Peng, ZHAO Yifei, LIU Hong

2021, 39(1):  40-47. 

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With increasing application scenarios and the growth of flight time, the risk of ground impact in low-altitude airspace flight has been increasingly focused. Main inducements of ground hazards are obtained through the existing UAV operation data and accident investigation conclusion. Combing current UAV ground impact risk assessment modeling points, UAV system failure model, impact area model, ground object distribution model and the injury evaluation model are summarized according to the risk assessment process. Some typical models are compared, summarizing the shortcomings existing in these researches including single failure mode, non-uniform distribution and injury model, etc. Finally, the research trend of UAV operation risk and related technologies are prospected, ground hazard risk assessment system and the development trend of industry and regulatory technologies are summarized.


Application of fault tree method in time limited dispatch

HU Wei, CAI Jing

2021, 39(1):  48-51. 

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TLD analysis is an important part of aircraft system safety analysis. One of the important links is to calculate the system LOTC rate after component failure. The current function analyzing method is cmparatively conservative, and its application in complex systems is insufficient. Therefore, the fault tree method is applied to the TLD analysis and is proved simple and accurate. It can be used in any complex system and help to improve the operability and accuracy of TLD analysis.


Basic Science

Impact resistance of TC4 plate against blunt projectile under different layer orders#br#

HU Jing, WANG Lujun, HU Ang

2021, 39(1):  52-58. 

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In order to study the ballistic resistance and failure modes of TC4 titanium alloy plate under different material layer orders, high velocity impact experiment of blunt projectile on TC4 titanium alloy target plate is conducted by light gas gun. Based on the analysis of experimental phenomena, validity of simulation model and material parameters are verified by ABAQUS, and the influence of layer order and material on the ballistic resistance of TC4 titanium alloy is further analyzed. Experimental results indicate that the TC4 titanium alloy has certain toughness characteristics, the failure of shear plugging is mainly caused by annular shear force under the penetration of blunt projectile. Delamination decreases the ballistic resistance of TC4 plate, layer order
influences its ballistic resistance, the impact resistence performance with layer order with soft target in front of hard target is better than that with the reverse layer order.


Consistency rule mining algorithm based on variable precision dominance relation rough set model#br#

TAO Zhi, HU Liu, WANG Dan

2021, 39(1):  59-64. 

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In order to conduct data mining in dominance-based information system with noise data, the modified knowledge granularity is proposed as the uncertainty measure for the improved rough rule set, and the relative reduction of heuristic information attributes is obtained. Then, the consistency rule set is derived basing on the parameter values provided by variable precision dominance relation rough set, analyzing the influential sensitivity degree of parameter values on rule set. Obviously, the consistency rule set obtained by the algorithm has higher certainty and coverage, the inconsistency caused by data noise is also eliminated, thus ensuring the accuracy and rationality of prediction and classification. Instance analysis proves that this algorithm is an effective method for rule acquisition.