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Zhang Hongming,Liu Chengcheng,Zhang Shiwei,Wang Youhua,Lei Gang,Zhu Jianguo 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6
This paper proposes an axial–radial flux hybrid excitation permanent magnet eddy current coupling (HE-PMEC), where the ferrite magnet is employed for producing the radial flux and the DC excitation current is adopted for producing the axial flux. Moreover, a shielding layer is developed to regulate the radial magnetic field. Its magnetic field distribution, electromagnetic performance, and temperature distribution are calculated based on the 3D finite element method (FEM). By adjusting the applied DC excitation current density and the insertion depth of the shielding layer, the variable current starting process, the variable current braking process, and the speed regulation characteristic of the proposed HE-PMEC are obtained. It can be seen that the starting process, braking process, and speed regulation ability of the HE-PMEC have been enhanced greatly. Furthermore, the copper ring shape of the HE-PMEC is optimized by using the proposed improved multilevel optimization method. It can be seen that the performance of the HE-PMEC can be improved by using the new optimized copper ring shape. Lastly, compared with the conventional PMECs, the proposed HE-PMEC has shown its superior electromagnetic performance.
Youhua Li,Lubing Shi,Zhongming Liu,Xiaopeng Wang,Xuetao Qiao,Zhihong Zhang,Shidang Yan 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12
For high-speed, heavy-load gear units, the meshing tooth surfaces are generally under the mixed lubrication state, which is crucial for gear pitting or micro pitting damage. To clarify the effects of lubrication state on tooth pitting damage, carrying out both numerical and experimental studies on the contact severity of gears under different lubrication states is necessary. In this paper, a 3D line-contact elasto hydrodynamic lubrication model considering fractal surface roughness was developed and used to investigate the lubrication characteristics of involute gears. Both the distributions of pressure and film thickness fluctuated under the rolling contact of rough surfaces. The fluctuations became more substantial with the increase of load and roughness. Furthermore, from the calculated film thickness ratio λ, the contact of gear tooth surfaces with a fractal roughness of Ra = 0.8 μm was always under full lubrication state (λ > 1). When the roughness was increased to Ra = 3.2 μm, the contact was first transmitted into the mixed lubrication state (0.2 < λ < 1) under the load of 1000 N*m and finally deteriorated to boundary lubrication state (λ < 0.2) under the load of 2000 N*m. The boundary lubrication state that occurred under the contact of highly rough surfaces could induce the formation of gear pitting damage. The contact fatigue test showed the gear tooth surface roughness increased from 0.7 μm to around 2.7 μm after 8 million running cycles and then suffered pitting failure after another 2 million cycles, which was consistent with the simulation analysis prediction.
Liu Chengcheng,Zhang Hongming,Wang Shaoheng,Wang Youhua,Lei Gang,Zhu Jianguo 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3
High speed permanent magnet synchronous motor (HSPMSM) is an important driving motor for electric vehicles. Compared with the electric motor operated under normal speed, it is critical to reduce the torque ripple, vibration, and noise of the HSPMSM. Furthermore, The air-gap fux density total harmonic distortion and electromotive force total harmonic distortion determine by torque performance and vibration noise. This article uses analytical methods to analyze the infuence of permanent magnet sinusoidal segmentation (PMS) on the electromagnetic performance of surface-mounted HSPMSM. The fnite element method is used to calculate the infuence of diferent permanent magnet segmentation numbers, diferent adjacent permanent magnet decreasing thickness, and diferent center PM width on the electromagnetic performance of permanent magnet sinusoidal segmented surface-mounted high-speed permanent magnet synchronous motor (M2). Comparing the efectiveness of PMS in surface-mounted HSPMSM and interior HSPMSM. Furthermore, the rotor dynamics analysis and vibration noise analysis on M2 are performed, and the infuence of PMS on the stress and vibration noise of both motors’ rotors is summarized. This article proposes a parameter preprocessing grouping multiphysical multi-objective high-dimensional multilevel optimization method. Taking M2 as an example, a global optimization design was carried out for the high-dimensional structural parameters brought by PMS, which improved the electromagnetic performance of M2 and reduced the vibration noise and rotor stress.
Ping Yang,Rujin Zhou,Youhua Zhang,Shui Cao,Dan Zhang,Hongbing Ji,Linhai Duan,Xiuhong Meng 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.3
HP-Cu-BTCs (CTAB), HP-Cu-BTC(N,N), HP-Cu-BTC(SDBS) series with open metal coordination site Cu(I), cage window sites, tunable porosity, high specific surface area, cavity, etc., were synthesized using cationic surfactant (cetyltrimethylammonium bromide, neutral organic amine, and an anionic surfactant as templates, respectively, A variety of techniques were used to analyze the materials before and after CO2 cycle adsorption at 303K. A high BET specific surface area (1,194.06 m2/g) and total pore volume (0.63 cm3/g) were found in the synthesized HP-Cu-BTC(NN). The synthesized HP-Cu-BTC(N,N) not only has high CO2 adsorption capacity (7.4293 mmol/g) but also good selectivity (37.20) for adsorption separation of CO2/N2. Besides, FT-IR spectroscopy, CO2-TPD curves and adsorption kinetic curve demonstrated that the adsorption mechanism of synthesized HP-Cu-BTC(N,N) was mainly attributable to physisorption and it could be regenerated at relatively low temperature. The mesoporous structure not only improves the uptake capacity but also improves the diffusion and mass transfer of CO2. At the same time, the CO2-TPD showed that the HP-Cu-BTCs may have two major adsorption sites. One is to absorb CO2 molecules through van der Waals forces. The other is the electrostatic interaction of the open Cu sites with CO2. Therefore, the CO2/N2 adsorption selectivity of HP-Cu-BTC(N,N) is significantly higher than that of conventional Cu-BTC. After five consecutive adsorption/desorption cycles, the adsorbents retained an excellent adsorption property. Thus, it is a very good adsorbent for the CO2 capture.
Oh, Seil,Choi, Eue-Keun,Zhang, Youhua,Mazgalev, Todor N. Ovid Technologies Wolters Kluwer -American Heart A 2011 Circulation. Arrhythmia and electrophysiology Vol.4 No.4
<P>Autonomic denervation may suppress atrial fibrillation (AF) vulnerability. This study was designed to assess the short- to mid-term effects of botulinum toxin, a cholinergic neurotransmission blocker, on AF inducibility.</P>