Search

Your search keyword '"Xuan, Weidong"' showing total 43 results
Start Over Author "Xuan, Weidong" Search Limiters Full Text
43 results on '"Xuan, Weidong"'

27. Enhancement of Damping Capbility of MnCu Alloy by High Magnetic Field.

Author

Wang, Diwei, Niu, Hongkang, Zhang, Sibin, Xuan, Weidong, Ren, Zhongming, and Tian, Qingchao

Subjects
MAGNETIC alloys, MAGNETIC fields, DYNAMIC mechanical analysis, TRANSMISSION electron microscopes, MARTENSITIC transformations
Abstract

The directionally solidified MnCuNiFe alloy was prepared under high magnetic field. The microstructure, composition distribution, phase transformation behavior and damping capacity of the alloy were studied by means of metallographic microscope, scanning electron microscope, transmission electron microscope, X-ray diffraction, differential scanning calorimetry, thermal expansion analysis and dynamic mechanical analysis. It is revealed that magnetic field has definite effect on the refinement of dendrite microstructure as well as the enrichment of Ni element, and thus induces the occurrence of martensitic transformation at about 300 K. The preferred (111) orientation modulated by high magnetic field, especially the induced fct1 → fcc martensitic transformation, together with the twin boundary relaxation, ensure that the directionally solidified MnCuNiFe alloy prepared under high magnetic field owns high-damping capacity in a wide-temperature range from 200 K to 320 K. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

34. Atomization mechanism and powder morphology in laminar flow gas atomization

Author

Hu Tao, LI Chuan-Jun, Chen Chaoyue, Li Xia, Xu Jinxin, Wang Jiang, Ren Zhongming, Shen Lu-Yu, Xuan Weidong, Yu Jian-Bo, Shuai San-San, and Li Xing-Gang

Subjects
Physics::Fluid Dynamics, Morphology (linguistics), Materials science, Chemical engineering, General Physics and Astronomy, Laminar flow, Mechanism (sociology)
Abstract

Metal powders prepared by laminar flow gas atomization have the advantages of small particle size and narrow particle size distribution. At present, the research on laminar flow gas atomization mainly focuses on the influence of process parameters on atomization and powder characteristics, but the atomization mechanism of laminar flow gas atomization is still not clear. In this work, the atomization gas flow, primary and secondary breakup mechanism, and particle morphology of the laminar flow gas atomization process are systematically investigated through numerical simulation and experimental analysis. The characteristics of single-phase atomization gas flow through the De Laval nozzle are studied using the standard k-ε turbulence model. The flow field structure shows a “necklace”-like structure with an expansion wave cluster of oblique shock. The primary and secondary atomization mechanism are investigated using the coupled level-set and volume-of-fluid model, which is validated by solidified fragments and powders after the atomization experiment, and results of the numerical simulation also provide some important advices for the application and specific process of laminar gas atomization technology. The studies indicate that the melts at the periphery of the liquid column are mainly peeled off by filaments or ligaments, which exhibits the small dimension and pressurized melt atomization characteristics. The secondary atomization is mainly based on the disintegration of spherical droplets in the mode of Rayleigh-Taylor instability deformation and sheet-thinning breakup. The simulation results also show that increasing the gas pressure and melt superheat can effectively reduce the probability of irregular powders to occur. The AlSi10Mg powders are obtained under a pressure of 2.0 MPa in the experiment on gas atomization, and the properties of the powders are analyzed. The results show that the powders have good sphericity and flowability, and the proportion of hollow powders is very low. In addition, the mean particle size of the AlSi10Mg powders is 54.3 μm, and the yield of fine powders reaches 48.7%, which is greatly improved compared with the traditional gas atomization processes. Moreover, about 90% of the powders have particle sizes in a range of 30–100 μm, which indicates that a narrow particle size distribution can be obtained by the laminar gas atomization technology.

Published
2021

43. Appropriateness of Potential Evapotranspiration Models for Climate Change Impact Analysis in Yarlung Zangbo River Basin, China.

Author

Pan, Suli, Xu, Yue-Ping, Xuan, Weidong, Gu, Haiting, and Bai, Zhixu

Subjects
CLIMATE change models, STANDARD deviations, EVAPOTRANSPIRATION
Abstract

Evapotranspiration (ET) is an important element in the water and energy cycle. Potential evapotranspiration (PET) is an important measurement of ET. Its accuracy has significant influence on agricultural water management, irrigation planning, and hydrological modelling. However, whether current PET models are applicable under climate change or not, is still a question. In this study, five frequently used PET models were chosen, including one combination model (the FAO Penman-Monteith model, FAO-PM), two temperature-based models (the Blaney-Criddle and the Hargreaves models) and two radiation-based models (the Makkink and the Priestley-Taylor models), to estimate their appropriateness in the historical and future periods under climate change impact on the Yarlung Zangbo river basin, China. Bias correction methods were not only applied to the temperature output of Global Climate Models (GCMs), but also for radiation, humidity, and wind speed. It was demonstrated that the results from the Blaney-Criddle and Makkink models provided better agreement with the PET obtained by the FAO-PM model in the historical period. In the future period, monthly PET estimated by all five models show positive trends. The changes of PET under RCP8.5 are much higher than under RCP2.6. The radiation-based models show better appropriateness than the temperature-based models in the future, as the root mean square error (RMSE) value of the former models is almost half of the latter models. The radiation-based models are recommended for use to estimate PET under climate change in the Yarlung Zangbo river basin. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results