http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
The Relative Efficiency of Container Terminals in Small and Medium-Sized Ports in China
Zi-Yao DING,Geon-Sik JO,Ying WANG,여기태 한국해운물류학회 2015 The Asian journal of shipping and Logistics Vol.31 No.2
The promotion of domestic consumption in China will gradually ramp up the small and medium-sized port container industry, and this will require greater port efficiency and an updated development strategy. The aim of this paper is to evaluate operational and productivity efficiency change in 21 coastal small and medium sized-port container terminals in China. The first step was carried out using data envelopment analysis (DEA) and the Malmquist productivity index (MPI), and the factors affecting productivity efficiency change were then estimated and quantified using Tobit regression. The empirical results indicate that the most efficient terminals are the Rizhao and Lianyungang port terminals. Furthermore, the terminals that hold a share of more than 50% of Chinese state-owned shipping line show the highest increase in productivity efficiency change. Lastly, the results indicate manpower structure; Chinese state-owned shipping line shareholding; registered capital; and shipping routes have positive effect and the factor, number of terminal operators, have a negative correlation.
Machining characteristics of USV-MF complex assisted WEDM-LS based on multi-physical coupling
Yan Wang,Shun-wen Yao,Zi-jun Ding,Chen-zhen Wu,Wei Xiong 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.2
Ultrasonic vibration (USV) and magnetic field (MF) complex assisted techniques are combined with low speed wire electrical discharge machining (USV-MF complex assisted WEDM-LS) to improve the machining performance of conventional WEDM-LS. Firstly, the simulation results of multi-physical coupling simulation model show that under the influence of ultrasonic vibration, the working fluid fluidity is greatly enhanced and its temperature is significantly decreased. Then, a three-phase flow model of bubble, working fluid and debris in the machining area is established to investigate the effects of ultrasonic vibration on bubble and debris, and the process of bubble rupture is simulated. The simulation results show that with the increase of ultrasonic frequency, the movement of bubble and debris becomes fiercer and fiercer, when ultrasonic frequency is 30 kHz and ultrasonic amplitude is 10 μm, the bubble is collapsed. Finally, comparison of the experimental results of conventional WEDM-LS, USV assisted WEDM-LS, MF assisted WEDM-LS and USV-MF complex assisted WEDM-LS in machining TiNi-01 shape memory alloy reveals that the ratio of normal discharge and the material removal rate are both increased, the workpiece surface roughness value is decreased and the workpiece surface quality is improved in the process of USV-MF complex assisted WEDM-LS.