Volume 47,Issue 11,2024 Table of Contents

1 Influences of frame flexibility on natural characteristics of dual-rotor wind turbine drivetrain

SHUAI Quan , ZHU Caichao , TAN Jianjun , WU Yaru , TAN Shuping , LAO Wenxin

2024, 47(11):1-14. DOI: 10.11835/j.issn.1000-582X.2023.109

[Abstract](91) [HTML](14) [PDF 6.38 M](80)

Abstract:
The dual-rotor wind turbine is an innovative horizontal axis design that harnesses the wake of the front turbine for additional power generation, leading to a higher wind energy utilization coefficient. However,the longer axial span required to minimize the flow field interference between the front and rear turbines complicates the drivetrain’s modal characteristics, raising the risk of resonance due to multi-point elastic support in the flexible frame. This study incorporates frame flexibility and elastic support into a rigid-flexible coupling dynamic model of the drivetrain using multibody dynamics. The analysis of the drivetrain’s coupling vibration modes reveals that the first two torsional vibration natural frequencies are 5.63 Hz and 6.01 Hz, corresponding to the rear and front turbine drivetrains, respectively. The drivetrain exhibits three vibration modes: local vibration in either the front or rear turbine, coupled vibration in either turbine drivetrain, and coupled vibration between both turbines. The study concludes that frame flexibility redistributes modal energy across components, affecting the drivetrain’s natural characteristics.

2 Reliability analysis of AMT gear transmission system for mining trucks

QIN Datong , GAO Di , LIU Changzhao , LYU Chang , SUN Dandan

2024, 47(11):15-26. DOI: 10.11835/j.issn.1000-582X.2024.11.002

[Abstract](53) [HTML](9) [PDF 3.43 M](49)

Abstract:
To accurately predict the dynamic reliability of the automated manual transmission(AMT) gear system in mining trucks, a rigid-flexible coupling dynamic model was developed. This model considers the flexibility of key components and the effects of internal and external load excitations. Dynamic load analysis was conducted for the sixth-gear and seventh-gear transmission, which are subject to high service frequency and harsh operating conditions. Based on this analysis, the dynamic reliability of these gear systems was evaluated, taking into account the fluctuating loads, degradation in component strength, and the correlation between component failures. The study identified weak elements in the AMT transmission system and provided insights into the reliability of the system and its components over service time. These findings lay the foundation for improving the reliability and performance of AMT gear transmission systems for mining trucks.

3 Critical transition relations for fatigue failure of PEEK gear under oil-jet lubrication

HU Xinlei , LI Jing , LIU Huaiju , WEI Peitang , LU Zehua , WU Ruo

2024, 47(11):27-36. DOI: 10.11835/j.issn.1000-582X.2023.223

[Abstract](41) [HTML](14) [PDF 3.60 M](52)

Abstract:
Polyetheretherketone (PEEK) gears are high-performance polymer gears widely used in automobiles, drones, robots, and other fields. However, the complex failure mechanism of PEEK gears and the lack of basic data on loading capacity lead to a shortage of a reasonable design basis in power transmission applications. To address the unclear failure mechanism and the lack of fundamental durability data of PEEK gears, fatigue performance tests of PEEK helical gear pairs under oil-jet lubrication were carried out, and the contact stress and bending stress were calculated. The failure mechanism were investigated by using scanning electron microscopy and other equipment. Experimental results show that the primary failure modes of PEEK gears under oil-jet lubrication were tooth surface pitting failure and tooth root fatigue fracture. The critical transition relationship between PEEK gear contact fatigue failure and bending fatigue failure was identified, and an evaluation method for the failure form of PEEK gears was proposed. When the ratio of contact stress to bending stress of the PEEK gear was smaller than 1.02, the PEEK gear mainly suffered from root fatigue fracture; when the ratio of contact stress to bending stress was larger than 1.10, the PEEK gear mainly suffered from tooth surface pitting failure. When the ratio was in the range from 1.02 to 1.10, there was a critical failure threshold between tooth surface contact fatigue and root bending fatigue.

4 Highway lane-changing behavior: a data-driven analysis of driver intentions

YANG Chonghui , ZHENG Ling , ZUO Yifang , WANG Kan , ZENG Jie , DING Xuecong

2024, 47(11):37-50. DOI: 10.11835/j.issn.1000-582X.2023.111

[Abstract](41) [HTML](10) [PDF 4.77 M](78)

Abstract:
Understanding human driving behaviors has significant implications for promoting decision-making in intelligent vehicles and improving driving safety. This study focuses on highway lane-changing behavior, using the NGSIM (Next Generation Simulation) Dataset to extract key parameters and analyze the correlation between these parameters and driving behaviors. A GMM-HMM-based model for lane-changing intention recognition was developed, achieving an accuracy of 95.6% in predicting lane changes 1.0 s before they occur, and an accuracy of over 80% in recognizing lane-changing intentions. This model can be applied to intelligent vehicle design to effectively reduce lane-changing risks and improve driving safety.

5 Equivalent electrochemical impedance-thermal coupling model for lithium-ion batteries considering skin effect and high-frequency additional heat

TANG Guofeng , ZHU Guangyao , HU Minghui , HU Jiamin , JIN Guoqing

2024, 47(11):51-64. DOI: 10.11835/j.issn.1000-582X.2023.110

[Abstract](42) [HTML](4) [PDF 5.76 M](57)

Abstract:
Developing an accurate equivalent electrochemical impedance-thermal coupling model is crucial for calculating impedance and estimating temperature during low-temperature heating of batteries using high-frequency alternating current (AC). The NSGA-II algorithm was used to identify parameters for seven equivalent impedance models across a frequency range of 10 Hz to 100 000 Hz. The study found that a model using a resistor and inductor parallel module better accounts for the skin effect at high frequencies without increasing computational complexity compared to a single inductor module. The proposed model, which incorporates time-varying heat transfer coefficients and high-frequency additional heat, was validated under both constant-frequency and variable-frequency conditions. It reduced the maximum temperature prediction error from 2.93 °C to 0.35 °C, with an RMSE of only 0.23 °C compared with existing models, proving its practicality and accuracy.

6 Bilinear weighted least square state estimation of the electricity-water coupled system

CUI Jingxin , ZHAO Xia , WANG Luo

2024, 47(11):65-80. DOI: 10.11835/j.issn.1000-582X.2023.207

[Abstract](41) [HTML](11) [PDF 1.23 M](42)

Abstract:
Multi-energy flow state estimation is a critical area of research in the energy internet. Current research on the state estimation of electricity-water coupling system is still in its infancy, facing challenges such as poor adaptability to water network conditions and insufficient utilization of electricity-water coupling information. To address these issues, this paper proposes a bilinear weighted least square (WLS) state estimation method for water networks, considering the correction of the friction coefficient. By incorporating virtual measurements of water pumps and bi-directional transmission of coupling information, a bilinear WLS state estimation method is developed, suitable for interdependent, cooperative and joint operations of electricity-water coupling systems. The effectiveness of the proposed method is verified by an 11-node water network and two electricity-water coupling systems, formed by coupling with IEEE-14 node and IEEE-118 node power systems. Numerical results highlight the necessity of correcting the friction coefficient in water network state estimation, the computational efficiency and adaptability of the bilinear WLS method for low flow rate water networks, and the the improvement in accuracy, data consistency and observability achieved through cooperative and joint estimation for both power systems and water networks.

7 Electrical parameters identification of permanent magnet synchronous motor based on improved snake optimization algorithm

HE Wei , CHEN Bo , JIA Qingjian , NING Huiming

2024, 47(11):81-93. DOI: 10.11835/j.issn.1000-582X.2023.212

[Abstract](49) [HTML](11) [PDF 2.31 M](41)

Abstract:
The precise design of the drive unit controller for space antennas depends on the accurate identification of the electrical parameters of the permanent magnet synchronous motor(PMSM). Achieving reliable parameters through precise identification is essential for the motor’s performance. However, the standard snake optimization algorithm(SOA) used in PMSM parameters identification faces several issues, such as slow convergence speed, low accuracy, and susceptibility to local optima. To address these limitations, three strategies are proposed in this paper. First, the Tent chaotic map and quasi-opposition-based learning strategy are introduced to enrich the diversity of the initial snake population. Second, improvements to the thresholds for food quantity and environmental temperature are made to enhance the algorithm’s convergence speed. Finally, the cuckoo search algorithm based on Cauchy mutation is utilized to improve the global optimization capabilities and robustness of the algorithm. These three strategies, combined with the standard SOA, form an improved snake optimization algorithm. The proposed algorithm is applied to identify the electrical parameters of the PMSM in the space antenna drive unit. Results show that, compared with the standard SOA, the improved algorithm achieves higher identification accuracy, faster convergence speed, and better robustness.

8 Effects of stretching rate and temperature on the piezoelectric properties of PVDF-HFP thin films

WANG Yang , WU Liangke

2024, 47(11):94-103. DOI: 10.11835/j.issn.1000.582X.2024.11.008

[Abstract](37) [HTML](14) [PDF 2.96 M](50)

Abstract:
Stretching is one of the most effective methods to improve the piezoelectric properties of PVDF-HFP films. In this study, PVDF-HFP piezoelectric films were prepared using the solution casting method, and the changes in morphology and crystal structure during stretching were studied by varying the stretching rate and temperature. The results indicate that tensile stress can induce a transformation of the matrix’s internal structure from spherical crystals to fibrous crystals, thereby facilitating the transition from the non-polar α-phase to the polar β-phase. Under optimal conditions of a elongation ratio of 5, a stretching temperature of 60 ℃, and a stretching rate of 10 mm/min, the relative β-phase content exceeds 90 %, and the calibrated open circuit voltage reaches 1.50 V under a maximum poling electric field E_maxof 60 MV/m. Furthermore, when the maximum poling electric field is increased to 100 MV/m, the calibrated open circuit voltage rises to 2.24 V. The higher poling field improves the orientation of dipole moments within the matrix, leading to enhanced piezoelectric performance.

9 Microstructure and low-temperature impact toughness of large-thickness steel for offshore wind power

SHI Li , Long Jie , PANG Huiyong , LIN Mingxin , ZHANG Haijun , WU Tao

2024, 47(11):104-111. DOI: 10.11835/j.issn.1000-582X.2023.050

[Abstract](33) [HTML](7) [PDF 5.05 M](46)

Abstract:
To address the issues of low impact energy and high variability in the core of 85 mm thick S355G10+N steel plates used in offshore wind power, the microstructure of steel plates with different thickness was investigated through metallographic examination, scanning electron microscope, and energy spectrum analysis, combined with theoretical calculations of inclusion formation. The results show that the microstructure of the steel is predominantly granular bainite, with minor amounts of ferrite and pearlite. While the surface and the 1/4 thickness region of the plate exhibit homogeneity, significant segregation and lath bainite are observed in the core. Impact fracture morphology shows that MnS and (Nb,Ti)C inclusions generated by center segregation act as fracture initiation points, with intergranular fracture occurring around these inclusions. The presence of lath bainite in the center segregation zone increases crack propagation, and the combined effect of inclusions and lath bainite significantly reduces the impact toughness of the steel plate core.

10 Research on structures, aromaticity and spectral properties of Al₂₄N₂₄ through the density functional theory

GUO Yajing , LI Xiuyan

2024, 47(11):112-119. DOI: 10.11835/j.issn.1000.582X.2024.11.011

[Abstract](41) [HTML](7) [PDF 2.34 M](55)

Abstract:
The physical-chemical properties and electronic structures of Al₂₄N₂₄ were optimized using density functional theory (DFT) at the B3LYP/6-31g(d) level. The results revealed four stable ground-state structures with point groups S₄, C₂, S₈, and O for Al₂₄N₂₄ clusters. None of the Al₂₄N₂₄ clusters exhibited p-type or n-type transport behavior in the gas phase, nor did they display bipolar characteristics; however, all four clusters favored hole transport. Based on the optimized gas-phase structures, nuclear independent chemical shift (NICS) values were calculated, confirming the aromaticity of all isomers. The IR-Raman spectra of the four clusters were analyzed, revealing that the internal vibration modes of each molecule significantly influenced the distribution of IR and Raman peak values. A slight blue shift in the IR spectra was observed with an increasing number of eight-membered rings, while no such shift was detected in the Raman spectra. Notably, the Al₂₄N₂₄ molecule with O symmetry contained six eight-membered rings, leading to vibrational spectra distinct from the other three clusters.

11 Study on structures and properties of alkali metals doped B180/- clusters

ZHAI Huili , MA Guanghui , LI Chenggang

2024, 47(11):120-130. DOI: 10.11835/j.issn.1000-582X.2023.001

[Abstract](54) [HTML](10) [PDF 2.62 M](53)

Abstract:
Boron-based nanomaterials have attracted significant attention in cluster science due to their unique molecular structures and chemical bonding. In this study, we systematically investigated the structures and properties of M₂ (M=Li, Na, K) doped B0/ ?18 clusters at the PBE0/6-311+G(d) level using the CALYPSO structure prediction program combined with density functional theory. Structure predictions found that all doped systems exhibit tubular configurations. Except for Li₂B₁₈, which has C1 point group symmetry, the global minimum structures of the other clusters adopt a D_9d point group symmetry tubular shape, with the two M atoms localized along the axis of the tubular structure. Stability analyses indicated that K₂B₁₈ and Li₂B?18clusters exhibit relatively strong stability in the neutral and anionic series, respectively. Charge transfer analysis revealed that electrons are transferred from the M atoms to the base boron fragment. Magnetic properties analysis indicated that the total magnetic moment is zero for the closed-shell structures of Li₂B₁₈, Na2B18 and K₂B₁₈ clusters. However, the open-shell structures of Li₂B?18, Na₂B?18 and K₂B?18 clusters exhibit magnetic moments of 1 μB. Dipole moment and polarizability analyses showed that both the dipole moment and the first hyperpolarizability are zero for the highly symmetrical structures. Additionally, simulated photoelectron spectra, IR spectra and Raman spectra, generated using Multiwfn software, provide a theoretical basis for further experiments. At last, the relationships between thermodynamic parameters (C_v and S) and temperature were discussed.

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