Papers by Author: Jun Gao

Paper TitlePage

Authors: Jian Hong Gong, Shu Xia Lin, Jun Gao
Abstract: Boride inclusions in the synthetic diamond single crystals grown from Fe-Ni-C-B system under high temperature and high pressure were studied in the present paper. Both chemical composition and structure of the inclusions incorporated into the diamond during the process of diamond growth were successfully determined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It was found that the inclusions related to boron trapped in the diamond consisted of f.c.c. (FeNi)23(CB)6, (FeNi)3(CB), Fe2B, FeB, hexagonal Ni3B, and B4C.
Authors: Xing Rong Chu, Lionel Leotoing, Dominique Guines, Jun Gao
Abstract: The accuracy of simulation result depends greatly on the implemented hardening law. An appropriate hardening model should be able to describe the coupling effects of the strain, strain rate and temperature on the flow stress of the material. Based on the stress-strain curves obtained from uniaxial tensile tests, two different types of hardening models (power law and saturation) are proposed to describe the flow stresses of an aluminum alloy AA5086 under different temperatures (20, 150 and 200°C) and tensile speeds (1, 10 and 100 mm·s-1). The correlation results are compared to experimental data and the roles of the hardening models in predicting the material flow stress are compared and discussed.
Authors: Jian Hong Gong, Shu Xia Lin, Jun Gao
Abstract: In the present paper, boron-doped diamond was synthesized by static pressure method using Fe-Ni-C-B system catalyst, whose resistance-temperature characteristic curve was studied. Experiments results proved that the boron-doped diamond has different ionization energy in different temperature interval and the reasons were analyzed. The maximum operating temperature is about 773K for such boron-doped diamond. The research provides experimental basis for high-temperature semiconductor diamond.
Authors: Jian Hong Gong, Shu Xia Lin, Wang Li, Jun Gao
Abstract: The structural and electronic properties of diamond and graphite were investigated by the first-principles total-energy pseudopotential method based on density functional theory. The band structure, DOS and PDOS were calculated. Results showed that diamond had a wide band gap, and its direct transition energy is 6.0 eV. But graphite’s band gap is about zero, meaning without transition energy. That explains the reasons of diamond acting as an insulator but graphite acting as a conductor. DOS and PDOS analysis results indicate both diamond and graphite are sp hybridization and p states contribute mostly to the bonding of crystal. While their covalent bonds style are different.
Authors: Shu Xia Lin, Jun Gao, Jan Hong Gong, Cheng Lin Zhang
Abstract: The drawability of ME20 and ZE10 magnesium alloys sheets under mechanical press were investigated. The deep drawing experiment was tried out based on research production of AZ31 sheet forming. The forming temperature range of two sheets was obtained, and the ZE10 magnesium alloys sheets were formed well at lower temperature than ME20 alloy. The microstructures of ME20 consisted of fine grains and precipitates did not change evidently during the drawing process. The equiaxed grains of ZE10 included a great deal of twinning were refined obviously. The drawability was related with alloy compositions and grain size. The fractures were observed through SEM to probe the fracture mechanism of two sheets.
Authors: Shou Hai Wang, Jun Gao, Gu Ren Fei, Ping Zhang, Jun Huang, Li Li Xu
Abstract: Acrylonitrile-butadiene-styrene (ABS) / polymethyl methacrylate (PMMA) with the addition of maleic anhydride grafted polystyrene (KT-5) and polyolefin elastomer (POE) were melt processed in a co-rotating twin-screw extruder. The effect of KT-5 and POE content on the mechanical properties of ABS/PMMA was investigated. Experiment results indicate that KT-5 can improve the tensile strength and the composites are toughened effectively as the addition of POE. According to Orthogonal tests, it demonstrates that POE ha a greater effect on the blends than KT-5, and there exist no obvious interactivity between the two components.
Authors: Bin Zhang, Benjamin Ducharne, Jun Gao
Abstract: Energy harvesting from ambient environment vibration is a potential method to supply the low-power consumption devices. This paper demonstrates a new method to proceed energy harvesting using a piezoceramic. Both the mechanical and electrical excitations (hybrid stimulation) have been exerted on a piezoceramic. Current was measured though a current amplifier to calculate the induced polarization. By comparing the hybrid stimulation and the pure mechanical one, it can be found that the hybrid stimulation method enable to amplifier the harvested energy, which is promising to be used in energy harvesting and sensor applications.
Authors: Guang Ying Ma, Wang Yao, Jun Gao, Peng Wang, Jia Bin Wang
Abstract: In this paper, the finite element software was used to analyze the rigidity of the pump body and the rotor shaft, in order to provide some useful information for the optimal design of pump. The analysis result shows that the rigidity of the pump body model is adequate, but the rotor shaft displacement is a little large, which should be modified. Nomenclature F Centrifugal force of the impeller [N] m Quality of the impeller [kg] w Rotational speed of the impellor [r/min] r Effective radius of the impeller [m] F1 Force on one bearing block [N] M Bending moment on one bearing block [N*m]
Authors: Yuan Chen, Xiao Peng Tan, Jun Gao
Abstract: This paper proposes two types of adaptive control schemes combined by the conventional computed-torque control and different fuzzy compensators for the robust tracking control of robotic manipulators with structured and unstructured uncertainties. Fuzzy compensators based on feed-forward and feed-back are developed to compensate these modeling uncertainties. The validity of the two types of adaptive control schemes is shown by numerical simulations of a three link rotary robot manipulator.
Authors: Shu Xia Lin, Cheng Lin Zhang, Jun Gao, Li Qun Ruan
Abstract: In this paper, AZ31B drawing test was carried out under the mechanical press with crank-slide mechanism. The influence of drawing temperature and drawing clearance on the wall thickness of AZ31B drawn parts was studied through testing. Some conclusions were drawn, which are: with the increase of drawing temperature, minimum wall thickness ( Tmin ) and maximum wall thickness ( Tmax ) of AZ31B drawn parts substantially decreased; with the increase of drawing clearance, Tmin and Tmax of AZ31B drawn parts increased.
Showing 1 to 10 of 24 Paper Titles