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Gang Chen,Yu Jin,Jing Wang,Cheng Zhang,Qiang Chen,Hongming Zhang,Xingjian Zhao,Zhiyong Li,Changhai Xie,Zhiming Du 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9
Isothermal compression tests were carried out to study the hot deformation behavior of T2 copper under various conditions. The deformation parameters, such as temperature and strain rate, have strong influence on flow stress and microstructureevolution of the alloy. A unified dislocation density-based model considering dynamic recovery and recrystallization wasestablished. And material parameters of the developed model were optimized by genetic algorithm. Comparisons betweenthe experimental and model data demonstrates that the developed model can precisely describe the flow behavior at quitewide range of deformation conditions. Meanwhile, the designed iterative procedure allows the model to be applied in timevariantdeformation conditions. Processing map and microstructure examination were constructed to optimize the processingwindow of the studied alloy. According to the processing maps, flow instability mainly appeared at low temperatures of500–650 °C and strain rates higher than 0.1 s−1. The optimum deformation parameters of T2 copper was concluded as thetemperature range of 700–800 °C and the strain rate of 0.1–1 s−1.
HU CHEN,YUNFEI LIU,YINONG LU,HONGMING WU,HAO QIAN,BAOSHUAI HUANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.4
The Eu3+-doped CdTe quantum dots (QDs) have been successfully synthesized in aqueous phase through microwave-assisted hydrothermal method. The as-prepared products were characterized by X-ray diffraction (XRD) technique, high-resolution transmission electron microscope (HRTEM), energy dispersive spectrum (EDS), X-ray photoclectron spectrum (XPS), UV-visble (UV-Vis) absorption spectrum and photoluminescence (PL). As the results show, the average sizes of the cubic phase CdTe and CdTe:1%Eu3+ are an average size of 3.7 nm and 3.5 nm, respectively. The average lattice parameter of CdTe:Eu3+ decreases with increasing Eu3+ ions concentration. Furthermore, compared to green emission of the host CdTe, the CdTe:1%Eu3+ presents additional orange fluorescence emission of Eu3+ ions. Recombination luminescence color is almost located in the yellow region of the CIE 1931, and the CIE 1931 coordinate is (0.448, 0.513). The effect of different Eu3+ doping concentration on the luminescence of CdTe:Eu3+ QDs was discussed in detail. It suggests that CdTe:Eu3+ QDs are potential phosphors for white light-emitting materials.
Novel assessment method of heavy metal pollution in surface water
Yingran Liu,Hongming Yu,Yu Sun,Juan Chen 대한환경공학회 2017 Environmental Engineering Research Vol.22 No.1
The primary purpose of this research is to understand those elements that define heavy metals contamination and to propose a novel assessment method based on principal component analysis (PCA) in the Yangping River region of Lingbao City, China. This paper makes detailed calculations regarding such factors the single-factor assessment (Pi) and Nemerow’s multi-factor index (PN) of heavy metals found in the surface water of the Yangping River. The maximum values of Pi (Cd) and Pi (Pb) were determined to be 892.000 and 113.800 respectively. The maximum value of PN was calculated to be 639.836. The results of Pearson’s correlation analysis, hierarchical cluster analysis, and PCA indicated heavy metal groupings as follows: Cu, Pb, Zn and As, Hg, Cd. The PCA-based pollution index (Pαn) of samplings was subsequently calculated. The relative coefficient square was valued at 0.996 between Pαn and PN, which indicated that Pαn is able to serve as a new heavy metal pollution index; not only this index able to eliminate the influence of the maximum value of Pi, but further, this index contains the principal component elements needed to evaluate heavy metal pollution levels.
Study on Wheel-Side Drive System with a Single Trailing Arm
Wang Bin,Chen Xinbo,Lyu Hongming,Niu Xinwei 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.5
In order to reduce unsprung mass and ensure driving comfortability, a novel electrical vehicle (EV) drive system, which integrated the wheel-side reducer and a single trailing arm, was studied in this paper. Firstly, the general structure of the drive system was studied, in which the reducer not only worked as a wheel-side reducer but also as the single trailing arm. Then, the transmission power losses were modeled by integrating different load-independent and load-independent models of power losses. Next, the experiment of the power losses test for the wheel-side drive system was conducted, which declared the patterns of power losses of electric motor and the whole drive system. Finally, the power losses of wheel-side reducer based on NEDC are studied, which illustrates oil churning and gear sliding power losses are the main types of transmission power losses. At low rotational velocities, gear friction power losses are larger than oil churning power losses. While at high rotational velocities, oil churning power losses are dominant. The transmission efficiency of the reducer based on NEDC varies among the range of 78 ~ 95 %, which depends on the torque and rotational velocity transmitted from the driving motor to EV’s wheel.
Orthorhombic carbon oC24: A novel topological nodal line semimetal
Li, Zhen-Zhen,Chen, Jia,Nie, Simin,Xu, Lifang,Mizuseki, Hiroshi,Weng, Hongming,Wang, Jian-Tao Elsevier 2018 Carbon Vol.133 No.-
<P><B>Abstract</B></P> <P>We identify by <I>ab initio</I> calculations a stable three-dimensional carbon allotrope that constructed by inserting benzene rings into the carbon-carbon bonds in a previously reported oC8 carbon. This new carbon phase has a 24-atom orthorhombic unit cell in C m m m ( D 2 H 19 ) symmetry and thus termed oC24. Phonon mode analysis confirms its dynamical stable. Total-energy calculations show that it is energetically stable comparable with (5,5) carbon nanotube. Detailed electronic band calculations reveal that oC24 is a topological node-line semimetal with two mirror-inversion symmetric nodal lines that go through the whole Brillouin zone in bulk and a projected surface flat band around the Fermi level. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Simulation Research of Multi-morphological Microstructures Chaining Mechanism of Nano-magnetic Fluid
Lei Yang,Yibiao Chen,Yao Yao,Shuaikang Wei,Yuhui Xie,Decai Li,Jun Yu,Hongming Zhou,Yiping Feng 한국자기학회 2024 Journal of Magnetics Vol.29 No.1
For nano-magnetic fluid(NMF), the magnetic nano-particle(MNP) kinematic behavior in a magnetic field and the chain-like microstructure evolution are important to study the NMF properties at the microscopic level. However, the chain structure formation mechanism and the effects of multiple environmental factors on microstructural morphology remain unclear. In this paper, the interaction of a two-particle system, chain structure formation process, microstructure evolution and response time simulation of NMF is investigated by the discrete element simulation method. The results show that the magnetic dipole and repulsive forces dominate the chain structure formation and evolution under a uniform magnetic field. MNPs assemble into chain-like structures and various complex structures along the magnetic f ield direction. The volume fraction, magnetization intensity and particle size significantly affect the microstructure and the response time. The above study can obtain the specific morphology of the microstructure at different working conditions and broaden the application of NMF in practical engineering.