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591 results on '"Chen, Zhengwei"'

152. Comparative analysis of the aerodynamic performance of trains and dynamic responses of catenaries for windbreak walls with different heights under crosswind

Author

Dong, Xiao, Liu, Tanghong, Xia, Yutao, Yang, Fan, Chen, Zhengwei, and Guo, Zijian

Abstract

Due to the deterioration of the crosswind-protection performance of the original earth embankment windbreak walls on the train with increased speed, researching the influence of the heightened windbreak walls on aerodynamic performances of trains as well as the protection of the catenary is necessary for optimizing the windproof performance. The improved delayed detached eddy simulation based on the shear stress transport (SST) κ-ω turbulence model was employed to simulate flow structures. Furthermore, the effect on the displacement of the catenary was investigated using the finite element method (FEM). The numerical case was validated against the field tests. The results show that the aerodynamic performances of the train were improved as the windbreak wall was heightened by 0.5 m. Whereas, further heightening the windbreak wall worsened the aerodynamic performance. When the windbreak wall was heightened by 0.5 and 1 m, the wind speed of the catenary was reduced by 31.17% and 53.87%, and the displacement of the catenary was reduced by 48.09% and 74.11%, respectively, compared with that of the original windbreak wall. These results reveal that the wind-protection performance on the train and catenary can be both improved by reasonably heightening windbreak walls.

Published
2023
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153. Sensitivity Analysis of Laser Quenching Parameters of ASTM 1045 of Disk Laser Based on Response Surface Method

Author

Chen Zhengwei, Yu Zhibin, Li Yunfei, Xing Han, and Chang Li

Subjects
Quenching, Materials science, Computer simulation, 020502 materials, Metals and Alloys, 02 engineering and technology, Mechanics, Condensed Matter Physics, Laser, law.invention, 0205 materials engineering, Mechanics of Materials, law, Martensite, Materials Chemistry, Hardening (metallurgy), Disk laser, Laser power scaling, CALPHAD
Abstract

Laser hardening is an important branch of laser surface hardening technology, which is widely used in metallurgy, transportation, machinery manufacturing, aerospace and other fields. At present, relying entirely on experience or process trial-and-error method, it can not effectively reveal the transient mechanism of laser quenching of disk laser, which is not conducive to shortening the research and development cycle and saving costs. The numerical simulation provides an effective way to obtain the dynamic evolution law of multi-field coupling in laser quenching process. In this paper, a thermo-mechanical coupling model of ASTM 1045 laser quenching process by disk laser is established. In the model, the temperature-dependent physical parameters were calculated by CALPHAD method. The transient law of temperature and microstructural transformation during quenching was obtained by solving the model. The formation and transformation degree of martensite were characterized by the dynamic changes of the depth and width of quenched transformation layer. The quenching structure and transformation hardening law were observed by Axioskop 2 SEM and Zeiss-IGMA HD FE-SEM to verify the accuracy of the simulation results. On this basis, the process parameters of laser quenching were sampled by Monte-Carlo method based on response surface methodology. The sensitivity effects of different process parameters on the temperature field and phase change field of laser quenching were analyzed, which laid a theoretical foundation for the optimization of process parameters. (1) Establish a thermo-mechanical coupling model for quenching process of ASTM 1045, and the sensitivity of the system is calculated. (2) The model can accurately reproduce the transient process of temperature and phase transformation field during laser quenching. (3) The laser power and laser incident angle are positively correlated with the response value. (4) The spot diameter and scanning speed are negatively correlated with response value. (5) The model can effectively calculate the sensitivity of laser quenching, predict the width and depth of quenching layer, and optimize process parameters.

Published
2019

154. sj-docx-1-pij-10.1177_13506501211047283 - Supplemental material for A method for predicting subsurface fatigue life of rolling bearings based on macro–micro coupling model

Author

Li, Chang, Chen, Zhengwei, Liu, Zhaotai, Han, Xing, and Chen, Xinxue

Subjects
FOS: Materials engineering, FOS: Other engineering and technologies, 91299 Materials Engineering not elsewhere classified, 99999 Engineering not elsewhere classified
Abstract

Supplemental material, sj-docx-1-pij-10.1177_13506501211047283 for A method for predicting subsurface fatigue life of rolling bearings based on macro–micro coupling model by Chang Li, Zhengwei Chen, Zhaotai Liu, Xing Han and Xinxue Chen in Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

Published
2021
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157. A method for predicting subsurface fatigue life of rolling bearings based on macro–micro coupling model.

Author

Li, Chang, Chen, Zhengwei, Liu, Zhaotai, Han, Xing, and Chen, Xinxue

Abstract

The fatigue life of the bearing can be predicted effectively by combining the multifield coupling condition of the working process with the internal microstructure. In this paper, a bearing fluid lubrication model is established based on the computational fluid dynamics method, and the calculation result is coupled to the thermal-solid model by the grid mapping method. Through this method, a bearing thermal-fluid-solid multifield coupling dynamics model is established to obtain the evolution information of bearings. Simultaneously, the micro-characterization experiments of SKF6406 bearing (M50 bearing steel) were carried out by electron backscatter diffraction, scanning electron microscope and nano-indentation. The microstructure model of bearing containing micro-inclusions was established by the Voronoi method. On this basis, the microscopic stress distribution characteristics and the motion law of bearing microstructure under the multifield coupling action are solved. In the end, the fatigue life prediction method of rolling bearing was established. [ABSTRACT FROM AUTHOR]

Published
2022
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163. In-depth Site-specific Analysis of N-glycoproteome in Human Cerebrospinal Fluid and Glycosylation Landscape Changes in Alzheimer's Disease

Author

Chen, Zhengwei, primary, Yu, Qinying, additional, Yu, Qing, additional, Johnson, Jillian, additional, Shipman, Richard, additional, Zhong, Xiaofang, additional, Huang, Junfeng, additional, Asthana, Sanjay, additional, Carlsson, Cynthia, additional, Okonkwo, Ozioma, additional, and Li, Lingjun, additional

Published
2021
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164. The influence of coronavirus disease 2019 on emergency department visits in Nanjing, China: A multicentre cross-sectional study

Author

Sun, Hao, primary, Liu, Keqin, additional, Li, Meng, additional, Tang, Shaowen, additional, Monte, Andrew A., additional, Wang, Jun, additional, Nie, Shinan, additional, Rui, Qinglin, additional, Liu, Wenge, additional, Qin, Haidong, additional, Tan, Xiao, additional, Ni, Haibin, additional, Yang, Wenxin, additional, Zhu, Congjian, additional, Yang, Runhua, additional, Yu, Tianhao, additional, Wang, Shengwei, additional, Jiang, Hao, additional, Chen, Xiaofeng, additional, Zhang, Wei, additional, Zhu, Yi, additional, Zhao, Huatou, additional, Yang, Shiyu, additional, Yin, Kejin, additional, Shao, Danbing, additional, Xiao, Liang, additional, Chen, Zhengwei, additional, Yuan, Weizhong, additional, Hu, Dongdong, additional, Wan, Xiaoyong, additional, Wu, Lanfu, additional, and Zhang, Jinsong, additional

Published
2020
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184. 考虑晶粒不均匀性的不锈钢激光淬火数值模拟

Author

Gao Xing, Chen Zhengwei, Li Chang, Han Xing, and Gao Hexin

Subjects
Laser quenching, Materials science, Computer simulation, Electrical and Electronic Engineering, Composite material, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials
Published
2021

185. Safety comparisons of a high-speed train's head and tail passing by a windbreak breach.

Author

Sun, Zhuang, Hashmi, Syeda Anam, Dai, Huanyun, Cheng, Xiandong, Zhang, Tingting, and Chen, Zhengwei

Subjects
HIGH speed trains, WINDBREAKS, shelterbelts, etc., AERODYNAMIC load, RELATIVE motion, WIND pressure, RAILROAD accidents
Abstract

Field tests were carried out to measure the wheel-rail forces of a high-speed train passing by a windbreak breach with a crosswind speed and a train speed of 32 m/s and 120 km/h, respectively. Unsteady Reynolds-averaged Navier-Stokes simulations and multibody dynamic simulations were carried out to reproduce the field test experiments. The results obtained indicated that the side force and yawing moment of the train plays a key role in the safety of the head and the tail of the train when it passes by a windbreak breach. By analysing the flow structures, the reasons behind the different aerodynamic loads on the train head and tail were discussed. Based on the vehicle movement, the maximum derailment coefficient (0.8) of the train head appeared to be at a higher risk of danger as compared to the maximum derailment coefficient (0.2) of the train tail. This is due to the wind loads on the train head which compel the bogies to relatively move with the carbody along the lateral direction one more time than the train tail. Whereas, for the train tail, there is no relative motion between the carbody and bogies on the tail. [ABSTRACT FROM AUTHOR]

Published
2021
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186. Detection of shrimp hemocyte iridescent virus by recombinase polymerase amplification assay

Author

Yang Zhou, Zhang Fang, Huang Jun, Huang Huijie, and Chen Zhengwei

Subjects
Hemocytes, Time Factors, White spot syndrome, Litopenaeus, Recombinase Polymerase Amplification, Polymerase Chain Reaction, Sensitivity and Specificity, Virus, Iridovirus, Recombinases, Shrimp farming, 03 medical and health sciences, Penaeidae, Animals, Molecular Biology, DNA Primers, 030304 developmental biology, 0303 health sciences, biology, 030306 microbiology, fungi, Infectious hypodermal and hematopoietic necrosis, Cell Biology, biology.organism_classification, Virology, Shrimp, Capsid, Plasmids
Abstract

Shrimp hemocyte iridescent virus (SHIV), which was first identified in white leg shrimp (Litopenaeus vannamei) in China in 2014, can cause extensive shrimp mortality and major economic losses in the shrimp farming industry in China. In this study, a novel real-time isothermal recombinase polymerase amplification (RPA) assay was developed using a TwistAmp exo kit for SHIV detection. First, five primers and a probe were designed for the major capsid protein gene (GenBank: KY681039.1) according to the TwistDx manual; next, the optimal primers were selected by a comparison experiment. The primers and probe were specific for SHIV and did not react with shrimp white spot syndrome virus (WSSV), shrimp infectious hypodermal and hematopoietic necrosis virus (IHHNV), shrimp enterocytozoon hepatopenaei (EHP), and macrobrachium rosenbergii nodavirus (MrNV) samples, as well as pathogens of acute hepatopancreatic necrosis disease (AHPND). The RPA assay reached a detection limit of 11 copies per reaction according to probit regression analysis. In addition, RPA assay detected the positive plasmid samples at concentration of 1000 copies/μL within 16.04 ± 0.72 min at a single low operation temperature (39 °C). The results proved that the proposed RPA method was an accurate, sensitive, affordable, and rapid detection tool that can be suitably applied for the diagnosis of SHIV in field conditions and in resource-poor settings.

Published
2020

187. Band alignment engineering at ultra-wide bandgap GeO2/SiO2 heterointerfaces.

Author

Liu, Jiabao, Chen, Zewei, Wei, Chengming, Yang, Cheng, Lan, Xinru, Huang, Shuiping, Meng, Dongdong, Tao, Weidong, Chen, Zhengwei, and Wang, Xu

Abstract

• Ultra-wide bandgap GeO 2 films were grown on quartz substrates. • Bandgap energies of GeO 2 films were calculated based on the energy loss spectra. • Effects of growth parameters on band alignments were studied for GeO 2 films. • Band offsets were determined for GeO 2 films grown at different growth parameters. Owing to the tremendous contribution for the carrier transport across the interface, the band alignment engineering in oxide semiconductor heterojunctions (OSHs) is of vital importance for developing oxide semiconductor optoelectronic devices. Here, we have deposited a series of ultra-wide bandgap GeO 2 thin films on quartz substrates by the direct-current reactive magnetron sputtering method to construct the OSHs and described the effect of the flow rate ratios of O 2 and Ar (O 2 :Ar) and substrate temperatures on the bandgap energies of GeO 2 films and band alignments at the interface of OSHs. Based on the energy loss spectra of O 1 s peaks, the tunable bandgap energies ranging from 4.37 to 5.37 eV have been achieved for GeO 2 films. An obvious variation of band alignments has been found in the OSHs, suggesting the dramatically influence of deposition conditions. The valence band offsets are determined to be ranging from 1.85 to 1.96 eV (from 1.88 to 1.95 eV) and the conduction band offsets are calculated to be ranging from 1.88 to 2.78 eV (from 1.74 to 2.19 eV) for the GeO 2 films grown at different O 2 :Ar (substrate temperatures), respectively, due to the nonlocalization of the oxygen vacancies in valence band and the formation of single hexagonal phase in the GeO 2 film. Our findings on the band alignment engineering in the GeO 2 /SiO 2 heterointerfaces will open the way for developing GeO 2 -based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Published
2024
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188. Photoelectrochemical Self-Powered Solar-Blind Photodetectors Based on Ga2O3 Nanorod Array/Electrolyte Solid/Liquid Heterojunctions with a Large Separation Interface of Photogenerated Carriers

Author

Chen, Kai, primary, Wang, Shunli, additional, He, Chenran, additional, Zhu, Huiwen, additional, Zhao, Hailin, additional, Guo, Daoyou, additional, Chen, Zhengwei, additional, Shen, Jingqin, additional, Li, Peigang, additional, Liu, Aiping, additional, Li, Chaorong, additional, Wu, Fengmin, additional, and Tang, Weihua, additional

Published
2019
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200. Differential Quantitative Determination of Site-Specific Intact N-Glycopeptides in Serum Haptoglobin between Hepatocellular Carcinoma and Cirrhosis Using LC-EThcD-MS/MS

Author

Zhu, Jianhui, primary, Chen, Zhengwei, additional, Zhang, Jie, additional, An, Mingrui, additional, Wu, Jing, additional, Yu, Qing, additional, Skilton, St. John, additional, Bern, Marshall, additional, Ilker Sen, K., additional, Li, Lingjun, additional, and Lubman, David M., additional

Published
2018
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