Volume 44,Issue 4,2021 Table of Contents

1 Innovative and effective method of suspension concept design

TAN Kanlun , LI Yangsa , LIU Qiang , WANG Jian

2021, 44(4):1-9. DOI: 10.11835/j.issn.1000-582X.2020.003

[Abstract](668) [HTML](1254) [PDF 3.17 M](1186)

Abstract:
The traditional method of suspension concept design requires a large number of trials and errors by using multibody simulations. It has thus high demand for time and manpower but the results are unstable. To solve these problems, a new method containing two steps has been developed. A novel analytical method is first applied to design hardpoints, and then elastic parts are designed using a secondary developed software based on ADAMS and MATLAB. Compared with the traditional method, the new method improves the development speed by about eight times. The new method also includes a control standard of 135 parameters of suspension kinematics and vehicle dynamics. It can judge the pros and cons of concepts and thus guide the design. Compared to the traditional method for parameter judgment, which relies on the experience of designers, the new method is more comprehensive, accurate and stable, leading to a higher design quality.

2 Road grade estimation using intelligent algorithms for fuel cell vehicles

WANG Cheng , ZHANG Caizhi

2021, 44(4):10-18. DOI: 10.11835/j.issn.1000-582X.2020.006

[Abstract](504) [HTML](1117) [PDF 3.56 M](1286)

Abstract:
Road grade is important for fuel cell hybrid vehicle (FCHV) in energy management strategies. However, the accurate road grade is difficult to obtain in real time. This study proposed a road grade estimation method based on an intelligent algorithm (long short-term memory recurrent neural network, LSTM). Based on the vehicle dynamic model, appropriate input variables were selected for the network input. For comparison, multilayer perceptron (MLP) algorithm was applied and the normalized root mean square error (NRMSE) of the estimation results in different literatures were listed. The results show that this method can estimate the road slope accurately without installing additional sensors with the RMSE (root mean square error) value and NRMSE value of the estimation error of 0.65 degree and 4.6%, respectively.

3 Transport of water in an anion exchange membrane fuel cell

LI Meng , SUI PangChieh

2021, 44(4):19-28. DOI: 10.11835/j.issn.1000-582X.2020.004

[Abstract](707) [HTML](1548) [PDF 1.93 M](1390)

Abstract:
This paper aimed to study the water management of alkaline anion exchange membrane fuel cells (AEMFC) via experiments and numerical simulations. Tokuyama A201 membrane was used to prepare and assemble a laboratory-scale AEMFC single cell. A two-dimensional steady-state isothermal model of the AEMFC was established to study the battery performance and internal water transport mechanisms. The model was based on mass conservation, composition conservation, and charge conservation, and considered the electrochemical reactions inside the battery. The battery performance and internal water transport and water distribution were analyzed through model calculations. The results show that the calculated polarization curve trend under certain parameters was in good agreement with the data obtained from the single cell tests. An increase in current density increased the net flux of water from the anode to the cathode, which was conducive to the reaction of the cathode. The anode and cathode both required humidification. Increasing the anode inlet gas humidity could speed up the net migration of water from the anode to the cathode. Too low inlet gas humidity of the cathode had a great impact on cell performance at high current densities.

4 A parameter measurement method for autonomous-rail rapid tram based on four-view stereo vision

PENG Jing , GAO Xiaofei , LONG Haiquan , ZHOU Chuande

2021, 44(4):29-36. DOI: 10.11835/j.issn.1000-582X.2021.004

[Abstract](402) [HTML](1196) [PDF 1.76 M](1068)

Abstract:
In order to solve the problems of autonomous-rail rapid tram parameter measurement limited by the body length, measurement accuracy and efficiency, a parameter measurement method has been developed through a stereo vision system based on four-view vision. A related angle’s visual measurement model was established by defining car body plane, wheel rotation angle, articulated disc angle and its zero degree based on space vector. High-precision algorithm of cooperative identification and optimization was studied to realize precise angle measurement. An autonomous-rail rapid tram parameter measurement method based on C/S was developed to realize fast measurement. In order to verify the feasibility of the method, a three-section autonomous-rail rapid tram was taken as an example to measure the angles. The results show that the method is fast and effective. The measurement accuracies of wheel steering angle and hinge steering angle are better than ±0.1ånd ±0.05°, respectively. Our method provides a detection method with a wide view, high efficiency and high precision for the parameter measurement of autonomous-rail rapid trams.

5 Design and analysis of a novel type micro-dispensing mechanism with large displacement

LI Xuan , DING Bingxiao , ZHOU Shuangwu , LI Yangmin

2021, 44(4):37-51. DOI: 10.11835/j.issn.1000-582X.2020.113

[Abstract](502) [HTML](1668) [PDF 4.05 M](1128)

Abstract:
To solve the issues of low accuracy and limited speed of a micro liquid-delivery system, a novel micro-dispensing mechanism with a large stroke using a piezoelectric actuator was proposed. To compensate the limited stroke of the piezoelectric actuator, hybrid amplification mechanisms were integrated with the designed flexure-based mechanism. Referring to the operation principle of three typical amplification mechanisms, the magnification ratio was derived. Based on Lagrange’s theorem, the stiffness model of the mechanism was established. In addition, the natural frequency of the mechanism was derived. To validate the correctness of the theoretical analysis, simulations were performed via the ANSYS Workbench, demonstrating that the errors of the stiffness model and magnification ratio were 8.5% and 7.2%, respectively. The proposed mechanism provides insights to the design of the high-performance liquid micro delivery system.

6 Magnetic circuit optimization design and finite element analysis of giant magnetostrictive actuator

TU Jianwei , LIU Zhaofu , LI Zhao

2021, 44(4):52-63. DOI: 10.11835/j.issn.1000-582X.2020.286

[Abstract](466) [HTML](1685) [PDF 4.66 M](1307)

Abstract:
Giant magnetostrictive actuator (GMA) is a new type of vibration control driving device. However, due to its complicated internal magnetic circuit, the intensity and uniformity of the magnetic induction in the internal magnetic circuit of GMA will seriously affect the working performance of the actuator. In order to solve the above problems, based on the theory of linear magnetostriction and electromagnetics under static conditions, a finite element model of the GMA was established using the finite element software ANSYS. The impacts of the material parameters of the excitation coil, the magnet and the inner wall of the magnet on the magnetic induction intensity were systematically studied. At the same time, the design principles of reducing the magnetic leakage, increasing the magnetic induction intensity and improving the uniformity of the magnetic induction in the GMM rod were proposed. The intensity and uniformity of the magnetic induction at the axial centerline of the giant magnetostrictive rod were used as the evaluation criteria. Parameters such as the opening and closing magnetic circuit, the axial length of the excitation coil, the magnetic permeability of the material, the air gap, and the radius of the magnetizer were optimized. The results show that when the closed magnetic circuit was adopted, the intensity and uniformity of the magnetic induction were greatly improved. After the optimization of the magnetic circuit, the magnetic induction intensity increased by 0.1 T, and the uniformity increased by 10.27%.

7 Effects of auxiliary slots on the cogging torque of an interior permanent-magnet synchronous motor

TAO Caixia , FU Minglu , GAO Fengyang , WAN Yingli , LIU Hanqing

2021, 44(4):64-76. DOI: 10.11835/j.issn.1000-582X.2020.106

[Abstract](769) [HTML](2174) [PDF 4.71 M](1489)

Abstract:
Aiming at finding the solution to the problem of vibration and noise resulting from the torque fluctuation of a permanent magnet motor caused by cogging torque, auxiliary slots were used to reduce the cogging torque. The principle of suppressing cogging torque was analyzed and by changing the number, depth, width, slot area and slot shape of the auxiliary slot, Ansoft Maxwell software was used to model the permanent magnet motor, and the finite element method was used to analyze the effect of the auxiliary slot on cogging torque of the permanent magnet synchronous motor. Taking a 4-pole 36-slot motor as an example, the analysis results show that with two auxiliary rectangular slots whose depth, width and area are 0.7 mm, 1.2 mm, and 0.84 mm²respectively, the weakening effect is the most obvious, with the cogging torque 75.2% lower than that without an auxiliary slot. In addition, the back electromotive force changes little before and after the application of the auxiliary slot, and the amplitude of the fundamental wave of the air gap magnetic density decreases; the degree of 5th and 7th harmonic weakening is significant; the waveform distortion rate drops to 17.78%, and the motor performance is improved.

8 Differential protection of the distribution line based on 5G communication and dynamic time wrapping algorithm

HUANG Fuquan , WANG Tinghuang , ZHANG Haitai , LIU Zijun , LI Guodong

2021, 44(4):77-85. DOI: 10.11835/j.issn.1000-582X.2020.112

[Abstract](625) [HTML](988) [PDF 4.68 M](1330)

Abstract:
The access of distributed new energy generation device in modern distribution network makes the traditional three-section current protection difficult to realize. The differential protection needs the laying of optical fiber infrastructures, and its very high construction and maintenance costs make its wide application difficult. The ultra-low delay of 5G communication makes it possible to realize the differential protection of data transmission channels in the power grid, which can be a solution to the problem of high optical-fiber costs. However, the uncertainty of delay and jitter of 5G communication has a negative impact on the calculation accuracy of protection action criterion. To solve this problem, the dynamic time wrapping (DTW) algorithm is used to tolerate the time delay and jitter, and a differential protection criterion based on DTW distance is constructed to eliminate the influence of transmission delay and jitter on calculation and comparison of differential protection. Finally, the influence of parameter selection on the result is analyzed by simulation, and the validity of differential protection criterion algorithm based on DTW distance is verified.

9 Effects of chemical washing on the stability of soil aggregates and the form of heavy metals

CHENG Jianxiong , XIE Gengxin , DING Wenchuan , YAN Zhuoyi , LI Qiao , WANG Ying

2021, 44(4):86-96. DOI: 10.11835/j.issn.1000-582X.2020.285

[Abstract](355) [HTML](1103) [PDF 4.14 M](981)

Abstract:
In order to investigate the characteristics of heavy metal removal with chemical washing from soil which was considered as a heterogeneous system, the soil aggregates were screened and graded on particle sizes of 0.25 mm to 2.00 mm, 0.05 mm to less than 0.25 mm and less than 0.05 mm. Then the effects of EDTA, citric acid and ferric chloride (FeCl₃) on the aggregate structure, the mass fraction of lead (Pb) and cadmium (Cd) and their speciation during washing were investigated. The results show that the removal rates of heavy metals in aggregates of different particle sizes were significantly different (P<0.05). Pb and Cd in small aggregates (particle sizes less than 0.05 mm) had higher removal rates than that in large aggregates. After washing, the proportion of residual state Cd on small aggregates increased, but the proportion of effective state Pb also increased. After washing, the average diameter of the aggregates of the three different particle sizes decreased by 77.25%, 80.98% and 49.15%, respectively. The disintegration of water-stable aggregates might increase the specific adsorption capacity of soil to Pb and Cd. Compared with EDTA and citric acid, FeCl₃ had lower structural damage to water-stable aggregates and better heavy metal leaching effect, which was beneficial to the subsequent safe reuse of soil.

10 The relationship of air pollution and respiratory diseases: Evidence from micro data of a hospital in Chongqing

WANG Feng , LIU Xin

2021, 44(4):97-106. DOI: 10.11835/j.issn.1000-582X.2020.297

[Abstract](713) [HTML](1575) [PDF 436.04 K](1446)

Abstract:
Based on the micro data of 45 380 cases of respiratory diseases in a hospital from January 2013 to December 2018, this paper uses the Poisson regression model to analyze the statistical relationship between urban air quality and the incidence of various respiratory diseases. The confirmed amount of various respiratory diseases in the hospital was used as the proxy variable of the incidence of respiratory diseases and matched with the monthly average concentration index of various air pollution of Chongqing from the monthly report of urban air quality issued by the Ministry of Ecology and Environment of the People’s Republic of China. The results show that air pollution is an important inducement of respiratory diseases. When the monthly average concentration of PM_2.5 increases by 1 μg/m³, the number of cases of bronchial asthma, chronic bronchitis, upper respiratory tract infection, community-acquired pneumonia, emphysema and chronic obstructive pulmonary diseases will increase by 0.2% to 1.1%.

11 Traffic congestion detection based on deep learning

DING Jie , LIU Jinfeng , YANG Zuliang , YAN Gaowei

2021, 44(4):107-116. DOI: 10.11835/j.issn.1000-582X.2020.298

[Abstract](982) [HTML](2503) [PDF 3.42 M](1679)

Abstract:
Aimed at traffic congestion detection, a method of detecting traffic congestion images using convolutional neural network (CNN) was proposed. First, a neural network classification model with three layers of convolutional layers was designed based on the TensorFlow framework. Then, the classification model was trained and evaluated using road congestion and non-congestion pictures. Finally, the well-trained model was used to carry out road congestion detection. Compared with many other deep learning classification models, the proposed convolutional neural network model showed high efficiency in congestion detection, and the detection accuracy reached 98.1%.

12 The second phases in as-cast Mg-8Zn-4Al-(0-1)Sr magnesium alloys

WU Juying , LI Jingren , ZHANG Jintao , LUO Li , YANG Mingbo , WU Lu , PAN Hucheng

2021, 44(4):117-128. DOI: 10.11835/j.issn.1000-582X.2020.111

[Abstract](482) [HTML](1588) [PDF 7.57 M](1013)

Abstract:
To systematically investigate the effect of Sr addition on the second phases in the as-cast Mg-8Zn-4Al magnesium alloy and provide the theoretical basis for the design of the Mg-Zn-Al series alloys containing Sr element, the type and formation mechanism of second phases in the ZA84 as-cast magnesium alloys with low Sr mass fractions (0.1%, 0.3%, and 1.0%) were investigated and analyzed by using scanning electron microscope (SEM), energy dispersive spectrometer (EDS), differential scanning calorimetry (DSC), and X-ray diffractometer (XRD). The results indicate that for the ZA84 as-cast alloy without Sr addition, besides the quasicrystal phase (Q), an extra Mg₃₂(Al, Zn)₄₉ phase with a small amount is found to exist in the alloy. With Sr addition, there are Al4Sr and Mg₃₂(Al, Zn)₄₉ phases in the as-cast alloy; the Al4Sr phase increases and Mg₃₂(Al, Zn)₄₉ phase decreases with increase of Sr content. In the Mg₃₂(Al,Zn)₄₉ phases of the as-cast Mg-8Zn-4Al-(0.1-1)Sr magnesium alloys, Sr mainly exists in two forms, i.e. indissolved and dissolved Sr atoms; in the Mg₃₂(Al,Zn)₄₉ phase where Sr atoms are not dissolved, the Zn concentration is relatively high and Al concentration is low. The results provide the necessary theoretical support for the design of reinforced and heat-resistant Mg-8Zn-4Al alloy.

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