Study on electromechanical performance of steering of the electric articulated tracked vehicles

Jiaqi Wu,Guoqiang Wang,Huanyu Zhao,Kangkang Sun 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7

Articulated tracked vehicles (ATVs) usually use hydraulic drive or mechanical drive modes. Electrically driven tracked vehicles have become a promising development direction for saving energy and meeting the environment requirements. In this study, based on the mechanical motion equation and the dynamic ATV equation, the electromechanical coupling model of the track vehicles is established by coupling the motor equation. The typical mechanical and electrical parameters in the ATV steering process are measured and compared with the numerical results to verify the correctness of the electromechanical coupling model. Experimental results indicate the main mechanical and electrical parameters of the ATV electro-mechanical system are changed at different articulated point deflection angles. The characteristic parameters of ATV include the change in current and voltage, the size of trajectory radius and the change of power under different deflection angles (10°, 15°, 20°, 25° and 30°), all of which are of great significance for the control of ATV. The current and voltage signals of ATV under specific trajectory can be calculated in reverse by the model, thereby providing a theoretical basis for the trajectory control of articulated vehicles. Therefore, this study provides a reference for the theoretical analysis of electromechanical performance, road driving performance and vehicle design of the electric ATV.

Modal Analysis of Resonance and Stable Domain Calculation of Active Damping in Multi-inverter Grid-connected Systems

Wu, Jian,Chen, Tao,Han, Wanqin,Zhao, Jiaqi,Li, Binbin,Xu, Dianguo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

Interaction among multiple grid-connected inverters has a negative impact on the stable operations and power quality of a power grid. The interrelated influences of inverter inductor-capacitor-inductor filters constitute a high-order power network, and consequently, excite complex resonances at various frequencies. This study first establishes a micro-grid admittance matrix, in which inverters use deadbeat control. Multiple resonances can then be evaluated via modal analysis. For the active damping method applied to deadbeat control, the sampling frequency and the stable domain of the virtual damping ratio are also presented by analyzing system stability in the discrete domain. Simulation and experimental results confirm the efficiency of modal analysis and stable domain calculation in multi-inverter grid-connected systems.

Resonance Characteristics Analysis of Grid-connected Inverter Systems based on Sensitivity Theory

Wu, Jian,Han, Wanqin,Chen, Tao,Zhao, Jiaqi,Li, Binbin,Xu, Dianguo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

Modal Analysis of Resonance and Stable Domain Calculation of Active Damping in Multi-inverter Grid-connected Systems

Jian Wu,Tao Chen,Wanqin Han,Jiaqi Zhao,Binbin Li,Dianguo Xu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

Interaction among multiple grid-connected inverters has a negative impact on the stable operations and power quality of a power grid. The interrelated influences of inverter inductor–capacitor–inductor filters constitute a high-order power network, and consequently, excite complex resonances at various frequencies. This study first establishes a micro-grid admittance matrix, in which inverters use deadbeat control. Multiple resonances can then be evaluated via modal analysis. For the active damping method applied to deadbeat control, the sampling frequency and the stable domain of the virtual damping ratio are also presented by analyzing system stability in the discrete domain. Simulation and experimental results confirm the efficiency of modal analysis and stable domain calculation in multi-inverter grid-connected systems.

Resonance Characteristics Analysis of Grid-connected Inverter Systems based on Sensitivity Theory

Jian Wu,Wanqin Han,Tao Chen,Jiaqi Zhao,Binbin Li,Dianguo Xu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

CuMOF-decorated biodegradable nanofibrous membrane: facile fabrication, high-efficiency filtration/separation and effective antibacterial property

Huizhi Wu,Qian Geng,Yonghan Li,Yuqian Song,Jiaqi Chu,Rong Zhou,Xin Ning,Senjie Dong,Ding Yuan 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

Here, a multifunctional poly (lactic acid)/copper-based metal–organic framework (PLA/CuMOF) degradablecomposite membrane featuring superior antibacterial and self-cleaning properties was fabricated viaa simple electrospinning process for high- efficiency filtration/separation. Benefiting from the decrease offiber diameter, the improved surface roughness and the surface charge of CuMOF, PLA/CuMOF fibrousmembrane achieved excellent capture ability for ultra-fine particles and superb purification capabilityfor real PM2.5 smoke. The differences of filtration capacity between PLA membrane and PLA/CuMOF membranewas further explored using analogue simulation with dynamic particle capture and airflow fielddistribution. Impressively, PLA/CuMOF fibrous membrane combines robust self-cleaning ability, effectiveantibacterial effect, and thermal management capability. Moreover, owing to the special selective wettabilityand chemical stability, PLA/CuMOF membrane possessed the stable oil–water separation performanceunder harsh environment (e.g., high acid, alkali, and salt). This degradable multifunctionalfiltration/separation fibrous membrane emerges a broad application prospect ranging from environmentalgovernance, industrial security to personal protection.

A Ultra-Low Specific On-Resistance and Extended Gate SJ LDMOS Structure

Lijuan Wu,Jiaqi Chen,Hang Yang,QiLin Ding,Xing Chen,Shaolian Su 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.3

A new structure of extended gate (EG) SJ LDMOS is proposed in this paper to overcome the substrate assisted depletion (SAD) eff ect in the structure of Super-Junction lateral double diff used metal oxide semiconductor (SJ LDMOS). Different from other surface SJ structures, the SJ layer of the structure is located in the body of the drift region. Gate oxide and silicon layer form the EG Structure-Oxide-Semiconductor structure that is similar to Metal–Insulator–Semiconductor capacitor. The the N-drift of the EG structure can obtain the charge compensation to overcome the SAD eff ect, and a nearly rectangular electric field is achieved. In the on-state, the EG structure has two conductive channels and the accumulation layer is formed on the drift region. By accumulating high concentration electrons in the channels, the specifi con-resistance ( R ON,sp ) is greatly reduced. When the drift length is 24 μm, 431.4 V breakdown voltage ( V B ) and 9.8 mΩ cm 2 R ON,sp are achieved, and the fi gure of merit is 18.9 MW cm −2 .

Association between the severity of hypodontia and the characteristics of craniofacial morphology in a Chinese population: A cross-sectional study

Xin Xiong,Jiaqi Liu,Yange Wu,Chengxinyue Ye,Qinlanhui Zhang,Yufan Zhu,Wenke Yang,Jun Wang 대한치과교정학회 2023 대한치과교정학회지 Vol.53 No.3

Objective: To investigate craniofacial differences in individuals with hypodontia and explore the relationship between craniofacial features and the number of congenitally missing teeth. Methods: A cross-sectional study was conducted among 261 Chinese patients (males, 124; females, 137; age, 7–24 years), divided into four groups (without hypodontia: no teeth missing, mild: one or two missing teeth, moderate: three to five missing teeth, severe: six or more missing teeth) according to the number of congenitally missing teeth. Differences in cephalometric measurements among the groups were analyzed. Further, multivariate linear regression and smooth curve fitting were performed to evaluate the relationship between the number of congenitally missing teeth and the cephalometric measurements. Results: In patients with hypodontia, SNA, NA-AP, FH-NA, ANB, Wits, ANS-Me/N-Me, GoGn-SN, UL-EP, and LL-EP significantly decreased, while Pog-NB, AB-NP, N-ANS, and S-Go/N-Me significantly increased. In multivariate linear regression analysis, SNB, Pog-NB, and S-Go/N-Me were positively related to the number of congenitally missing teeth. In contrast, NA-AP, FH-NA, ANB, Wits, N-Me, ANS-Me, ANS-Me/N-Me, GoGn-SN, SGn-FH (Y-axis), UL-EP, and LL-EP were negatively related, with absolute values of regression coefficients ranging from 0.147 to 0.357. Further, NA-AP, Pog-NB, S-Go/N-Me, and GoGn-SN showed the same tendency in both sexes, whereas UL-EP and LL-EP were different. Conclusions: Compared with controls, patients with hypodontia tend toward a Class III skeletal relationship, reduced lower anterior face height, flatter mandibular plane, and more retrusive lips. The number of congenitally missing teeth had a greater effect on certain characteristics of craniofacial morphology in males than in females.

数字化转型背景下大学生手机依赖对学习投入的影响

董高志(Gaozhi Dong),余嘉祺(Jiaqi Yu),罗小茵(Xiaoyin Luo),吴晓茵(Xiaoyin Wu),吴钧埔(Junpu Wu),罗云(Yun Luo) YIXIN 출판사 2023 教育教学研究论丛 Vol.1 No.5

本研究采用大学生手机成瘾倾向量表、大学生学习投入量表、心理弹性量表简版和延迟满足量表对610 名大学生施测,旨在考察数字化转型背景下大学生手机依赖对学习投入的影响,以及心理弹性和延迟满足在其中的中介作用。研究发现:大学生手机依赖、学习投入、心理弹性与延迟满足两两显著相关;心理弹性和延迟满足分别在手机依赖与学习投入之间起中介作用;心理弹性和延迟满足在大学生手机依赖和学习投入间起链式中介作用。手机依赖不仅可以直接影响大学生的学习投入,还可以通过心理弹性和延迟满足间接影响大学生的学习投入。 This study tested 610 college students using the mobile phone addiction tendency scale, the college student learning engagement scale, the simplified version of the psychological resilience scale, and the delayed gratification scale. The aim was to examine the impact of mobile phone dependence on learning engagement among college students in the context of digital transformation, as well as the mediating role of psychological resilience and delayed gratification. Research has found that there is a significant correlation between mobile phone dependence, learning engagement, psychological resilience, and delayed gratification among college students; Psychological resilience and delayed gratification respectively mediate the relationship between mobile phone dependence and learning engagement; Psychological resilience and delayed gratification play a chain mediating role between mobile phone dependence and learning engagement among college students. Mobile phone dependence not only directly affects the learning engagement of college students, but also indirectly affects their learning engagement through psychological resilience and delayed gratification.

Research Progress of Interface Conditions and Tribological Reactions: A Review

Huajie Tang,Jianlin Sun,Jiaqi He,Ping Wu 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-

Tribology plays a crucial role in progress of industry and engineering. The dependence of interfaceconditions and interfacial reactions provides the strategies for friction reduction as well as anti-wear inindustrial processes. That is to modify the surface structure of materials or tune the properties oflubricants. This review provides an overview on the important interface conditions and surface-inducedtribological reactions with emphasis on the underlying of their formation and action mechanism. Thetribological features of asperity, debris and surface texture arefirstly dictated. Then the main surfaceinducedphysicochemical reactions including wetting/dewetting, deposition/adsorption are discussed. Inparticular, the thermal, mechanical and electrical effects that trigger tribochemical reactions are alsoaddressed. Finally, some deficiencies in related investigations are summarized, with perspectives for thedevelopment of tribology in both science research and industrial application.