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Parameter identification approach using improved teaching and learning based optimization for hub motor considering temperature rise

Li Yong, Wang Yuan, Zhang Taohua, Hu Han, Wu Hao

Metrology and Measurement Systems

2023

Vol. 30, nr 1

99--115

Temperature rise of the hub motor in distributed drive electric vehicles (DDEVs) under long-time and overload operating conditions brings parameter drift and degrades the performance of the motor. A novel online parameter identification method based on improved teaching-learning-based optimization (ITLBO) is proposed to estimate the stator resistance, 𝑑-axis inductance, 𝑞-axis inductance, and flux linkage of the hub motor with respect to temperature rise. The effect of temperature rise on the stator resistance, 𝑑-axis inductance, 𝑞-axis inductance, and magnetic flux linkage is analysed. The hub motor parameters are identified offline. The proposed ITLBO algorithm is introduced to estimate the parameters online. The Gaussian perturbation function is employed to optimize the TLBO algorithm and improve the identification speed and accuracy. The mechanisms of group learning and low-ranking elimination are established. After that, the proposed ITLBO algorithm for parameter identification is employed to identify the hub motor parameters online on the test bench. Compared with other parameter identification algorithms, both simulation and experimental results show the proposed ITLBO algorithm has rapid convergence and a higher convergence precision, by which the robustness of the algorithm is effectively verified.

Dynamics of plant litter storage in a subtropical forest headwater stream during the rainy season

Hu Wanrong, Wu Fuzhong, Ni Xiangyin, Peng Yan, Wang Zheng, Zhao Zemin, Wang Yuan, Yue Kai

Polish Journal of Ecology

2022

vol. 70, nr 4

129--141

Plant litter is not only the major source of carbon (C) and nutrients for heterotrophic organisms in forest headwater streams, but also an important component of stream C storage. The dynamics of stream litter storage (i.e., the standing stock) are thus closely related to forest C fluxes, but has not been well assessed in the literature. To fill this gap, we investigated the monthly dynamics of plant litter storages at 17 reaches of a subtropical headwater stream from stream source to mouth during the rainy season (from March to August) of 2021. We found that (1), across sampling reaches, the mean litter storages of leaves, twigs (< 1 cm in diameter), fine woody debris (FWD, < 10 cm in diameter), reproductive parts (flowers and/or fruits), and barks in the stream during the rainy season were 25.6, 11.9, 16.7, 0.3, and 0.6 g/m2, respectively, and the storage peak of total litter was in May, while the storage peaks at most of the sampling reaches were in April and May; (2) litter storage, especially leaf litter, at the stream source reach (i.e., reach 1) was significantly higher than those in the other reaches, and riparian forest type affected the storages of twig and FWD litter, with higher values in reaches with broad-leaved than mixed riparian forests; and (3) stream physicochemical characteristics, especially channel gradient, channel width, and water discharge and alkalinity, had significant effects on litter storage, but their effects varied among different litter types. Overall, our study clearly assessed the dynamics of plant litter storages in a headwater stream of subtropical forests, which will help us to better understand the role of headwater streams in forest carbon storage and cycling.

Design and fabrication of 125I seeds for brachytherapy using capillary-based microfluidic technique

Wang Yuan, Zhang Miao, Song Tong, Chang Zhenqi

Nukleonika

2021

Vol. 66, No. 2

55--60

A new kind of 125I seeds with a core-shell structure were synthesized by an easy assembling–disassembling coaxial capillaries microfluidic device. The dose distribution of a 125I brachytherapy source fabricated by arranging six 125I seeds collinearly within a cylindrical titanium capsule was simulated by modelling the source in a water phantom using Monte Carlo N-Particle Transport code. The infl uence of the motion and the core size of the 125I seeds on the dose distribution was also studied in this work.