Zhang Ming, Nie Hong, Wei Xiao‐hui, Qian Xiaomei and Zhou Enzhi
The purpose of this paper is to introduce a co‐simulation method to study the ground maneuvers of aircraft anti‐skid braking and steering.
Abstract
Purpose
The purpose of this paper is to introduce a co‐simulation method to study the ground maneuvers of aircraft anti‐skid braking and steering.
Design/methodology/approach
A virtual prototype of aircraft is established in the multibody system dynamics software MSC.ADAMS/Aircraft. The anti‐skid braking control model, which adopts the multi‐threshold PID control method with a slip‐velocity‐controlled, pressure‐bias‐modulated (PBM) system, is established in MATLAB/Simulink. EASY5 is used to establish the hydraulic system of nose wheel steering. The ADAMS model is connected to block diagrams of the anti‐skid braking control model in MATLAB/Simulink, and is also connected to the block diagrams of nose wheel steering system model in EASY5, so that the ground maneuvers of aircraft anti‐skid braking and steering are simulated separately.
Findings
Results are presented to investigate the performance of anti‐skid braking system in aircraft anti‐skid simulation. In aircraft steering simulation, the influence of two important parameters on the forces acting on the tires is discussed in detail, and the safe area to prevent aircraft sideslip is obtained.
Originality/value
This paper presents an advanced method to study the ground maneuvers of aircraft anti‐skid braking and steering, and establishes an integrated aircraft model of airframe, landing gear, steering system, and anti‐skid braking system to investigate the interaction of each subsystem via simulation.
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Keywords
The purpose of this paper is to predict the main economic indices of online shopping in China.
Abstract
Purpose
The purpose of this paper is to predict the main economic indices of online shopping in China.
Design/methodology/approach
A fractional order weakening buffer operator (WBO) for the GM(1,1) model is put forward in order to solve the problem of limited nonlinear data. The order number of WBO can adjust in line with the scenario.
Findings
The experimental results indicate that the proposed method can consider the scenario and obtain more accurate forecasting results.
Originality/value
This study found that the slowdown of growth trend after the previous high speed expansion period will continue, and the online shopping sellers should make more efforts to develop potential consumers to increase its turnover.
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Shuowen Yan, Pu Xue, Long Liu and M.S. Zahran
This study aims to investigate the design and optimization of landing gear buffers to improve the landing-phase comfort of civil aircraft.
Abstract
Purpose
This study aims to investigate the design and optimization of landing gear buffers to improve the landing-phase comfort of civil aircraft.
Design/methodology/approach
The vibration comfort during the landing and taxiing phases is calculated and evaluated based on the flight-testing data for a type of civil aircraft. The calculation and evaluation are under the guidance of the vibration comfort standard of GB/T13441.1-2007 and related files. The authors establish here a rigid-flexible coupled multibody dynamics finite element model of one full-size aircraft. Furthermore, the authors also implement a dynamic simulation for the landing and taxiing processes. Also, an analysis of how the main parameters of the buffers affect the vibration comfort is presented. Finally, the optimization of the single-chamber and double-chamber buffers in the landing gear is performed considering vibration comfort.
Findings
The double-chamber buffer with optimized parameters in landing gear can improve the vibration comfort of the aircraft during the landing and taxiing phases. Moreover, the comfort index can be increased by 25.6% more than that of a single-chamber type.
Originality/value
To the best of the authors’ knowledge, this study first investigates the evaluation methods and evaluation indexes on the aircraft vibration comfort, then further conducts the optimization of the parameters of landing gear buffer with different structures, so as to improve the comfort of aircraft passengers during landing process. Most of the current studies on aircraft landing gear have focused on the strength and safety of the landing gear, with very limited research on cabin vibration comfort during landing and subsequent taxiing because of the coupling of runway surface unevenness and airframe vibration.
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Bin Fu, Xiao Hui Gao and Lifeng Wu
The purpose of this paper is to explore the relationship among the air quality index (AQI) of Beijing-Tianjin-Shijiazhuang region and find countermeasures to control the pollution…
Abstract
Purpose
The purpose of this paper is to explore the relationship among the air quality index (AQI) of Beijing-Tianjin-Shijiazhuang region and find countermeasures to control the pollution situation.
Design/methodology/approach
This study used the grey convex relation model to calculate the grey correlation degree through the AQI of Beijing-Tianjin-Shijiazhuang region.
Findings
By analyzing the calculation results among the three cities, it was concluded that the air quality of the three cities is closely related. Therefore, the Beijing-Tianjin-Shijiazhuang region should collaboratively improve the air quality for common development.
Research limitations/implications
More approaches may be adopted to calculate the grey correlation degree in the further research studies.
Practical implications
There exist some practical difficulties in implementing these governance measures.
Originality/value
The paper gives the countermeasures to control the pollution situation in Beijing-Tianjin-Shijiazhuang region.
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Keywords
Hui Xiao, Xiaotong Guo, Fangzhou Chen, Weiwei Zhang, Hao Liu, Zejian Chen and Jiahao Liu
Traditional nondestructive failure localization techniques are increasingly difficult to meet the requirements of high density and integration of system in package (SIP) devices…
Abstract
Purpose
Traditional nondestructive failure localization techniques are increasingly difficult to meet the requirements of high density and integration of system in package (SIP) devices in terms of resolution and accuracy. Time domain reflection (TDR) is recognized as a novel positioning analysis technology gradually being used in the electronics industry because of the good compatibility, high accuracy and high efficiency. However, there are limited reports focus on the application of TDR technology to SiP devices.
Design/methodology/approach
In this study, the authors used the TDR technique to locate the failure of SiP devices, and the results showed that the TDR technique can accurately locate the cracking of internal solder joints of SiP devices.
Findings
The measured transmission rate of electromagnetic wave signal was 9.56 × 107 m/s in the experimental SiP devices. In addition, the TDR technique successfully located the failure point, which was mainly caused by the cracking of the solder joint at the edge of the SiP device after 1,500 thermal cycles.
Originality/value
TDR technology is creatively applied to SiP device failure location, and quantitative analysis is realized.