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Minghui Liu,Jiasheng Wang,Yingcen Liu,Rongwen Lu,Shufen Zhang 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.10
We report the facile synthesis of small gold nanoparticles stabilized by carbon nanospheres (Au@C) for highly active and selective hydrogenation of 4-nitrobenzaldehyde. The formation of such a Au@C unique structure can be attributed to the high distribution of Au(III) species in the melamine-formaldehyde resin nanospheres, which were formed via the coordination of Au(III) with the abundant imino groups of melamine-formaldehyde pre-polymer. After the subsequent condensation and confined in situ reduction, small gold nanoparticles, and carbon nanospheres were formed simultaneously. Under the reaction conditions of 80 °C and 1.6 MPa, 99.3% conversion and >99% selectivity were achieved for the hydrogenation of 4-nitrobenzaldehyde to 4-aminobenzaldehyde.
The drag characteristics prediction of multi-plate frictional wet clutches in vehicle transmissions
Minghui Zhang,Yanfang Liu,Tianyan Liu,Xiangyang Xu,Jin Xu,Yudong Zhang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
The multi-plate frictional wet clutch is one of the most important components in automatic transmissions. With the increasing of the rotational speed, the phenomena is tested that the drag torque firstly increases to the peak torque, and then decreases to a lower level and maintains within a certain range, and finally increases rapidly again. A fluid-structure coupled model of the whole wet clutch was established. The simulation results show that the pressure distribution is obviously nonuniform either on the frictional surface or between two sides of the clutch plate. The nonuniform pressure would cause the axial and deflection motion and so the impact would occur, which is the main reason for the drag torque’s increasing under high rotational speed. Based on the simulated results, a prediction model was built with the direct artificial neural network method. The test results show that the drag characteristics prediction model is effective and fast.
Minghui Liu,Xiaoling Wang,Xiaobin Zhu,Wenlong Chen,Xiao Li 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.9
Due to its weak dependence on the quantity of variable samples, the non-probabilistic reliability analysis method based on the convex set model is applicable to practical problems in structural engineering with inherent uncertainties. However, when dealing with the black-box limit-state function issues in practical complex structural engineering, the traditional quadratic polynomial response surface (QP-RS) method has the problem of insufficient precision in approximating a highly nonlinear function. Meanwhile, fixing the limits of interval variables is trickier in case of scant samples and meager statistical information. To remedy the above deficiencies, this paper introduces a reasonable integrated reliability analysis approach. First, an adaptive Gaussian process regression response surface (GPR-RS) method that dynamically improves the fitted accuracy near the design point of the black-box limit-state function is formulated. Furthermore, the integrated reliability index with consideration of fuzzy interval uncertainties is presented. Three validation and two application examples are employed, which have justified the approach as a more reasonable assessor of practical complex structural reliability with safer results.
Tianyan Liu,Xiangyang Xu,Minghui Zhang,Runbo Zhang,Yue Wu,Hongzhi Ji,Yanfang Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
Under the engaging process, excessive temperature of clutch plates may lead to thermal failure. Existing research has failed to find the hot spot and the radial temperature difference real-timely. They also neglected the influence of dynamic sliding process and hydraulic characteristics. Thus, a multi-domain dynamic model of the whole clutch was proposed, involving the mechanical dynamics, the hydraulic dynamics and thermics. With the thermal resistance network method, the real-time axial and radial temperature prediction of clutch plates was realized. The highest temperature occurs on the friction pairs of axial middle and the maximum value occurs on the radial 5th mass. Compared with the results by FEM, the deviation is about 6.5 %, but the time duration is reduced significantly. Furthermore, the influence of the outer hub vibration (160 Hz, 0.2 Hz) on the dynamic characteristics was discussed. This work was tested to be an effective and good basis for the health prediction of wet clutches.
Minghui Wang,Jae Young Choi,Dong Hwan Park,Siyi Liu,Yeon Ho Je 한국응용곤충학회 2024 한국응용곤충학회 학술대회논문집 Vol.2024 No.04
Spodoptera exigua is one of the worldwide distributed agricultural pest insects and has been known to show high resistance to conventional chemical insecticides. Autographa california multiple nucleopolyhedrovirus (AcMNPV) has been used as eco-friendly biological control agent for S. exigua, as it exhibits high level of host specificity, stability and safety. In this study, for formulation of AcMNPV, the optimal conditions for mass-production of AcMNPV polyhedra was established using S. exigua larvae. Mass-produced AcMNPV polyhedra was formulated as wettable powder using microencapsulation method and its control efficacy against S. exigua was evaluated both in laboratory and semi-field experiment. Chinese cabbage treated with the AcMNPV formulation showed significantly reduced damage rates, suggesting that the AcMNPV formulation in this study could be useful for control of S. exigua