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Wei Zhang,Huarui Xu,Guisheng Zhu,Aibing Yu 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.4
Tetragonal barium titanate (BaTiO3) powder with a uniform size distribution was successfully prepared by an ion-exchange treatment followed by hydrothermal process, and with a high precursor concentration. Ion-exchange treatment of the bariumtitanium chloride led to the formation of the homogeneous Ba-Ti hydroxide sol. Then, hydrothermal (240 ℃ for 7 h) led to the preparation of BaTiO3 powders with a very narrow size distribution (90 ± 3 nm) and a very high tetragonal content (90%), which were confirmed respectively by scanning electron microscopy and differential scanning calorimetry. Further, using the regenerated resin to ion-exchange, the BaTiO3 yield reached 99%.
Study on the Unsteady Cavitation Flow Characteristics Inside the Mixed Transport Twin Screw Pump
Xuejing Zhang,Li Wang,Guisheng Zhu,Wei Han 한국유체기계학회 2024 International journal of fluid machinery and syste Vol.17 No.1
With the development of screw pumps towards high speed, high pressure, and large flow rate, cavitation in screw pumps has become a phenomenon that cannot be ignored. Based on ANSYS CFX, use SST turbulence model and combine with Rayleigh-Plesset equation to effectively simulate the internal flow of mixed transport twin screw pump, analyze the changes in cavitation morphology and the evolution of cavitation within the entire cycle of the pump, and explore the degree of cavitation on the surface of the screw rotor and the changes in pressure and velocity at the monitoring point with rotation period under different inlet pressures and speeds, and then analyze the changes in cavitation of the twin screw pump under different temperature. The calculation results indicate that cavitation first occurs at the inlet and then gradually penetrates into the interior of the chamber, mainly concentrated in the inlet section and the first chamber. The inlet pressure has a significant impact on cavitation phenomenon. As the inlet pressure decreases, the cavitation intensity continues to strengthen, and the cavitation area also continues to expand. Rotating speed can also affect cavitation, but the effect of speed changes on cavitation is not as significant as that of inlet pressure changes. In addition, increasing the water temperature will also increase the cavitation area. This study reveals the characteristics of cavitation flow in mixed transport twin screw pump, which is of great significance in avoiding cavitation and improving pump performance.
Jintong Chen,Rui Sun,Guisheng Li,Ming Fang,Gaoshan Xu,Mingya Zhang,Jinghui Li 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11
The influence of changes in temperature from 250 to 400 °C with 50 °C intervals during ECAP processing on the textureevolution and recrystallization behavior for Mg–9Al–1Zn alloy was studied. The results demonstrate that {10 1 2} extensiontwins and dislocation slip are the dominating deformation modes in low temperature (250 °C and 300 °C) ECAP processing,and those twins gradually disappear with increasing temperature. Most of the recrystallized grains are observed to exhibit(0001) poles 70°–90° away from the normal direction due to reorientation of the grains caused by twins and dislocationslips, with the texture changing from a strong basal texture to the texture component close to { 1 2 1 0} and {01 1 0}. Theproduction of ultrafine recrystallized grains in the specimens treated by ECAP at 400 °C was aided by grain fragmentationcaused by twins interaction, as well as dislocation slip and temperature increase during severe plastic deformation (SPD).
Gang He,Yanna Zhu,Guisheng Zhang,Guotong Qiao 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.12
Security is an important problem in wireless sensor networks. Intrusion detection system is one of the most common methods of network security, for which more and more people have shown solicitude. In this paper, a dynamic random password authentication (DRPA) method is proposed for the identity authentication of communication nodes, which can detect and prevent malicious behavior at each stage of the network operation. This paper introduces the method of automatic generation of random passwords. When a user wants to communicate, the password will be verified to confirm whether it is a normal user or a malicious user. The password’s generation and verification process is very suitable for wireless sensor networks. By using NS2, the simulation experiments are carried out and the results show that this method is superior to the other methods.