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1

Research on a novel hybrid shielding structure of magnetic coupler for inductive power transfer system

Liu Yun Rui, Wang Chunfang, Xia Dongwei, Yue Rui

Archives of Electrical Engineering

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2021

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Vol. 70, nr 1

129--143

EN

With the development of wireless power transfer technology, more and more attention has been paid to its electromagnetic safety. In this paper, a novel hybrid shielding structure composed of the innermost fan-shaped ferrite, the interlayer nanocrystalline stripand the outermost aluminum foil is proposed to shield the electromagnetic field of the inductive power transfer system. Eight structure parameters of the proposed shielding areoptimized by finite element simulation, in order to reduce the magnetic leakage of the system and improve the utilization rate of shielding materials. In addition, the proposed structure is compared with two types of typical double-layer hybrid shielding from the perspectives of the weight, the coupling coefficient and the magnetic flux leakage. Both simulation and experiment results show that the cost and weight of the proposed shield are about 60% lower than the traditional disk shield. More over, the shielding layer proposed in this paper can not only effectively reduce the magnetic flux leakage of the system, but also maintain a high coupling coefficient.

2

Multiphysics simulation and shed structure optimization of catenary icing insulator

Wang Sihua, Wang Junjun, Zhou Lijun, Chen Long, Zhao Lei

Archives of Electrical Engineering

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2021

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Vol. 70, nr 3

675--688

EN

It is not easy to make the insulators of the railway catenary for the dry and cold environment of the icy Qinghai-Tibet plateau, without causing serious ice-related flashover accidents. To study the operating status of catenary icing insulators, a two-dimensional icing model of catenary cantilever insulators was established based on the winter environmental characteristics of the Golmud station on the Qinghai-Tibet Railway. Compared different directions of ice growth, the spatial electric field distribution, and surface temperature distribution characteristics of icing insulators were analyzed by multi-physical field coupling simulation. The results show that as the thickness of the ice layer increases and the length of the icicle increases, the field intensity of the insulator gradually increases, and the surface temperature continues to rise. When the ice edge grows vertically downward, the electric field intensity of the insulator is the smallest, and the electric field intensity is the largest when the ice edge grows horizontally. Although the surface temperature of the insulator will rise with the increase of icing degree, it is lower than the freezing point and will not have a great impact on insulation performance. Secondly, when the cantilever insulator is arranged obliquely, the increase in the inclination angle will cause the electric field to increase and the temperature to rise slightly, so the inclination angle of the oblique cantilever should be reduced as much as possible during installation. Finally, the insulator with better insulation performance is obtained by optimizing the structure of the flat cantilever insulator.

3

Evaluation of brain injury criteria based on reliability analysis

Hazay Máté, Bojtar Impre

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 1

173--185

EN

Purpose: Among the proposed brain injury metrics, Brain Injury Criteria (BrIC) is a promising tool for performing safety assessment of vehicles in the future. In this paper, the available risk curves of BrIC were re-evaluated with the use of reliability analysis and new risk curves were constructed for different injury types based on literature data of tissue-level tolerances. Moreover, the comparison of different injury metrics and their corresponding risk curves were performed. Methods: Tissue-level uncertainties of the effect and resistance were considered by random variables. The variability of the tissue-level predictors was quantified by the finite element reconstruction of 100 frontal crash tests which were performed in Simulated Injury Monitor environment. The applied tests were scaled to given BrIC magnitudes and the injury probabilities were calculated by Monte Carlo simulations. New risk curves were fitted to the observed results using Weibull and Lognormal distribution functions. Results: The available risk curves of diffuse axonal injury (DAI) could be slightly improved, and combined AIS 4+ risk curves were obtained by considering subdural hematoma and contusion as well. The performance of several injury metrics and their risk curves were evaluated based on the observed correlations with the tissue-level predictors. Conclusions: The cumulative strain damage measure and the BrIC provide the highest correlation (R2 = 0.61) and the most reliable risk curve for the evaluation of DAI. Although the observed correlation is smaller for other injury types, the BrIC and the associated reliability analysis-based risk curves seem to provide the best available method for estimating the brain injury risk for frontal crash tests.

4

Computational modelling of foot orthosis for midfoot arthritis: a Taguchi approach for design optimization

Zhang Haowei, Liv Miko Lin, Yang Junyan, Cheung James Chung-Wai, Sun Wanju, Wong Duo Wai-Chi, NI Ming

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 4

75--83

EN

Evaluation of the internal biomechanics of the foot-and-ankle complex is challenging for the prescription of orthosis particularly for midfoot arthritis patients in which the joint condition is crucial. Methods: Using computational modeling and design optimization techniques, the objective of this study was to compare the biomechanical functions among different combinations of design factors using computer simulation. A finite element foot model was reconstructed from a midfoot arthritis patient. Orthotic designs with 3 levels for each of the 3 design factors (arch height, lateral wedge angle, and insole stiffness) contributed to 9 configurations using a fractional factorial design were tested. Results: An increase in peak plantar stress of the midfoot was facilitated by a medium arch height and wedge angle, and stiffest insole material, notwithstanding the combination neither reduced the peak plantar stress of other foot regions nor was consistent with the combination that minimized the stress of the articular cartilage. Conclusions: Insole with high arch (H = 30 mm), low stiffness (E = 1.0 MPa), and medium wedge angle (A = 5) could minimize the stress of the cartilage at the arthritic joint (primary outcome) and could be beneficial to the patients. Also, insole stiffness predominantly influenced cartilage stress. However, secondary outcomes including the stress of the navicular and medial cuneiform and the regional plantar stress did not produce the same solution. Future studies can consider a patient-specific loading profile to further the investigation on the stabilizing effect and the attenuation of load transfer induced by the insole.