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ANGULAR DISTRIBUTION OF SOLUTIONS OF HIGHER ORDER LINEAR DIFFERENTIAL EQUATIONS
Wu, Zhaojun,Sun, Daochun Korean Mathematical Society 2007 대한수학회지 Vol.44 No.6
In this paper, we study the location of zeros and Borel direction for the solutions of linear homogeneous differential equations $$f^{(n)}+A_{n-1}(z)f^{(n-1)}+{\cdots}+A_1(z)f#+A_0(z)f=0$$ with entire coefficients. Results are obtained concerning the rays near which the exponent of convergence of zeros of the solutions attains its Borel direction. This paper extends previous results due to S. J. Wu and other authors.
RADIAL OSCILLATION OF LINEAR DIFFERENTIAL EQUATION
Wu, Zhaojun Korean Mathematical Society 2012 대한수학회보 Vol.49 No.5
In this paper, the radial oscillation of the solutions of higher order homogeneous linear differential equation $$f^{(k)}+A_{n-2}(z)f^{(k-2)}+{\cdots}+A_1(z)f^{\prime}+A_0(z)f=0$$ with transcendental entire function coefficients is studied. Results are obtained to extend some results in [Z. Wu and D. Sun, Angular distribution of solutions of higher order linear differential equations, J. Korean Math. Soc. 44 (2007), no. 6, 1329-1338].
RADIAL OSCILLATION OF LINEAR DIFFERENTIAL EQUATION
Zhaojun Wu 대한수학회 2012 대한수학회보 Vol.49 No.5
In this paper, the radial oscillation of the solutions of higher order homogeneous linear differential equation $$f^{(k)}+A_{n-2}(z)f^{(k-2)}+{\cdots}+A_1(z)f^{\prime}+A_0(z)f=0$$ with transcendental entire function coefficients is studied. Results are obtained to extend some results in [Z. Wu and D. Sun, Angular distribution of solutions of higher order linear differential equations, J. Korean Math. Soc. 44 (2007), no. 6, 1329-1338].
Yu Wu,Zhaojun Wu,Kai Liu,Fu Li,Yujie Pang,Jianbin Zhang,Huayan Si 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.10
This work presents a simple method for the preparation of the Mg-doped nanocomposite copper silicates (Mgx-Cu1x-SiO3) (x=0.25, 0.5, 0.75 and 0.9) using coal gangue waste as the silicon source for CO2 capture at low temperature. The as-prepared Mgx-Cu1x-SiO3 was systemically characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller surface area analysis (BET). The results suggest that all Mgx-Cu1x-SiO3 possess large surface areas, micropores and mesoporous structures composed of the agglomerates of small nanoparticles. They exhibit high CO2 adsorption capacity at 298.15 K under 1 bar, and that of Mg0.9-Cu0.1-SiO3 was the highest with the value of 16.73 cm3/g. The Freundlich isotherm model fits the CO2 adsorption isotherm well. Thermodynamic analysis indicates that the CO2 adsorption on Mg0.9-Cu0.1-SiO3 is exothermic (Ho<0), chaotic (So<0), and spontaneous (Go<0). This work highlights the low-temperature adsorption behavior of silicate materials on CO2, which can provide some research basis for the utilization of silica in coal gangue.
Sinicization of Arabian Calligraphy and Its Influencing Factors
Yang Zhaojun,Wu Chuke 아시아사회과학학회 2021 Jornal of Asia Social Science Vol.2 No.1
Arab culture has been introduced into China for nearly 1,000 years. Since its introduction, it has been continuously integrated with Chinese culture and has bred a series of cultural and artistic phenomena with Chinese characteristics and strong Arab-Islamic color. Among them, Chinese Arabian calligraphic is a classic and also a model of Islamism Sinicization. This paper introduces the origin of Arabian calligraphy, its main fonts and main forms of its sinicization. On this basis, three main cultural factors that affect Arabian calligraphy were discussed, providing some thoughts for exploring and studying Arabian calligraphy in China.
Optimizing opportunistic preventive maintenance strategy for multi-unit system of CNC lathe
Yue Wu,Zhaojun Yang,Jili Wang,Xiaojuan Chen,Wei Hu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1
Due to the many components in the multi-unit system (i.e., CNC machine tools), the existing preventive maintenance (PM) strategies conducting independent PM for every component are time-consuming and waste unnecessary maintenance and downtime costs. Hence, this paper introduces the idea of opportunistic maintenance into the PM and proposes an opportunistic imperfect PM approach, which is a more realistic PM policy for a multi-unit system. In this approach, the effect of PM is assumed to be imperfect to correct the failure rate of each unit. According to the corrected failure rate function, the imperfect PM strategy of a single unit is optimized by minimizing the proposed unit maintenance cost rate under the limitation of minimum reliability. Then, these independent imperfect PM strategies for units are rescheduled by the proposed opportunistic PM strategy under the condition of judging the reliability OM threshold of units. We further optimize the opportunistic PM strategy by minimizing the total maintenance cost. Finally, the advantage of our approach is verified by the case study of 18 CNC lathes.
Preparation of mesoporous silica from coal slag and its metal ion adsorption behavior
Xinying Zhang,Yu Wu,Xuefang Li,Xianlong Meng,Huihu Shi,Zhaojun Wu,Jianbin Zhang 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.5
A novel mesoporous silica (MS) with the high specific surface area up to 1,199m2/g was prepared from coal slag by SO3 2 leaching and hydrothermal synthesis. Its application in metal ion removal was explored using Pb2+, Cu2+, Co2+ and Cd2+ as the model ions. The effects of adsorption time, pH, initial metal ion concentration, adsorbent dosage and adsorption temperature on the metal ion adsorption behaviors of the as-prepared MS were systematically, and the maximum adsorption capacities were measured to be 55.76mg·g1, 33.49mg·g1, 24.29mg·g1 and 22.98mg· g1 for Pb2+, Cu2+, Co2+ and Cd2+, respectively. The metal ion adsorption on the as-prepared MS followed pseudo-second- order kinetics, and the adsorption isotherm fitted the Langmuir isotherm model, indicating that the adsorption was spontaneous, endothermic and enthalpy driven.
Wang, Xiaodong,Liu, Xingguo,Qin, Boqiang,Gu, Zhaojun,Wu, Zongfan,Xu, Hao,Zhu, Hao,Cheng, Guofeng,Liu, Huang The Ecological Society of Korea 2015 Journal of Ecology and Environment Vol.38 No.3
In order to understand the mechanisms of conversion between different algal dominance, an experiment was performed in a greenhouse from 22 June to 10 July 2011. The experiment included a treatment group subjected to three instances of nutrient enrichment and a control with no nutrient enrichment. The initial water was dominated by Ankistrodesmus of Chlorophyta. The average water temperature at 08:30 h and 14:00 h during the experiment was $31.6^{\circ}C$ and $34.6^{\circ}C$, respectively. The results showed that the total nitrogen (TN), total phosphorus (TP), dissolved total nitrogen (DTN), dissolved total phosphorus (DTP), and soluble reactive phosphorus (SRP) concentrations in the treatment were significantly higher than in the control (P < 0.05). However, the TN/TP and DTN/DTP in the control was higher than in the treatment (P < 0.05). The dominant algae in the control did not change during the experiment, while the dominant algae in the treatment switched to Planktothrix of Cyanophyta on day 9. The chlorophyll a (Chl-a), wet weight of all algae, wet weight of Cyanophyta, and percentage of Cyanophyta in the control were all significantly lower than in the treatment (P < 0.05). Amounts of zooplankton, especially rotifers, were present at the end of the experimental period. The density of rotifers between the control and treatment was not significantly different (P > 0.05), while the copepod density in the treatment was higher than in the control (P < 0.05). We conclude that green algae dominance quickly switches to cyanobacteria dominance after nutrient enrichment in a greenhouse with elevated temperature.