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Yuming Qi,Tengwu He,Miaolin Feng 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7
Adding nanotwins to a metal could be a way to effectively improve its strength without suppressing its tensile ductility, whichsuggests that their unique nanostructure may alter microstructure evolution and deformation mechanisms. In this work, weperform a molecular dynamics-based tension simulation of two-dimension (2D) polycrystalline copper (Cu) with embeddednanotwins under uniaxial stress conditions. The results of MD-simulation reveal that the spacing of the twin boundarieshad a significant effect on the mechanical properties of nanotwinned materials. Specifically, an irregular relationship isfound between the twin boundary spacing ( DT ) and the strength of the material. It exhibits that the peak stress reached amaximum at DT = 12.5 nm and decreased thereafter with increasing average DT . However, flow stress reaches a maximumat a critical value of DT = 7 nm. According to the analysis of microstructure evolution, the presence of nanotwins hinder themotion of partial dislocations and stacking faults, and the stress-concentrated region leads to the transition from coherenttwin boundaries to incoherency. The stress-concentrated region locates in the step of incoherent would release the intrinsicstacking faults responsible for the formation of hierarchical contraction nanotwins stacking faults which efficiently improvesthe strength of Cu. In addition, as the tension proceeds, some samples begin to display the secondary twinning. This workwill be helpful for further investigation the nucleation and evolution of 2D nanotwinned metals and for formulating effectivestrength criteria for 2D nanotwinned metals.
Research on Prediction of Reverse Returned Logistics Based on Grey-Markov Model
Yuming Luo 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.8
In order to improve the prediction accuracy of reverse returned logistics, considering it has the characteristics of high volatility and uncertainty, the paper used the theory of Markov Chain to modify the result of Grey prediction. And a Grey-Markov prediction model was established. Several parallel region has been divided used the prediction curve of Grey prediction model as symmetric center. And each region was a state interval. A practical example show that the average relative error rate and the variance ratio of Grey-Markov prediction model was smaller, and the prediction accuracy is higher comparing with the Grey prediction model. The model is effective and feasible.
Influence of Carbon Fiber on Corrosion Behavior of Carbon Steel in Simulated Concrete Pore Solutions
( Yuming Tang ),( Yuchao Dun ),( Guodong Zhang ),( Xuhui Zhao ),( Yu Zuo ) 한국부식방식학회(구 한국부식학회) 2017 Corrosion Science and Technology Vol.16 No.4
Galvanic current measurement, polarization curves, electrochemical impedance spectroscopy and weight loss test were used to study the corrosion behavior of carbon steel before and after carbon fibers coupling to the carbon steel in simulated concrete pore solutions, and the film composition on the steel surface was analyzed using XPS method. The results indicate that passive film on steel surface had excellent protective property in pore solutions with different pH values (13.3, 12.5 and 11.6). After coupling with carbon fibers the area ratio of carbon steel to carbon fiber was 12.31), charge transfer resistance Rct of the steel surface decreased and the Fe3+/Fe2+ value in passive film decreased. As a result, stability of the film decreased and the corrosion rate of steel increased. Decreasing of the area ratio of steel to carbon fiber from 12.3 to 6.15 resulted in the decrease in Rct and the increase in corrosion rate. Especially in the pore solution with pH 11.6, the coupling leads the carbon steel to corrode easily.
Yuming Cui 대외경제정책연구원 2013 East Asian Economic Review Vol.17 No.3
The aim of this paper is to estimate the degree of RMB misalignment from its equilibrium exchange rate by applying the Behavioral Equilibrium Exchange Rate (BEER) approach. We employ monthly data with reference to China’s top 20 trading partners covering the period of 1997 to 2012. We find that the RMB was slightly overvalued before 2001 and significantly undervalued by up to 20 per cent in the end of 2006. There is evidence showing that the RMB approached to its equilibrium level from 2007 to 2008. However, the global financial crisis interrupted the trend of declining misalignment of RMB exchange rate. The RMB’s total misalignment increased to around 25 per cent in the mid-2011 mainly because the RMB was re-pegged to the US dollar and some currencies of China’s main trading partners depreciated during the period of crisis. More recently, the degree of RMB misalignment slightly declined since 2012 when the RMB proceeded to appreciate and China’s ratio of current account surplus to GDP dropped considerably. Our findings prove that there is a trend of the RMB approaching to its equilibrium exchange rate since 2007 except for the period of crisis.
Synergistic Effect of Copper and Cobalt in Cu-Co-O Composite Nanocatalyst for Catalytic Ozonation
Yuming Dong,Lina Wu,Guangli Wang,Hui Zhao,Pingping Jiang,Cuiyun Feng 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.11
A novel Cu-Co-O composite nanocatalyst was designed and prepared for the ozonation of phenol. A synergistic effect of copper and cobalt was observed over the Cu-Co-O composite nanocatalyst, which showed higher activity than either copper or cobalt oxide alone. In addition, the Cu-Co-O composite revealed good activity in a wide initial pH range (4.11-8.05) of water. The fine dispersion of cobalt on the surface of copper oxide boosted the interaction between catalyst and ozone, and the surface Lewis acid sites on the Cu-Co-O composite were determined as the active sites. The Raman spectroscopy also proved that the Cu-Co-O composite was quite sensitive to the ozone. The trivalent cobalt in the Cu-Co-O composite was proposed as the valid state.
Yuming Dong,Hui Zhao,Zhiliang Wang,Guangli Wang,Aizhen He,Pingping Jiang 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.1
ZnO nanoparticles were synthesized through a facile route and were used as ozonation catalysts. With the increase of calcination temperature (150-300 oC), surface hydroxyl groups and catalytic efficiency of asobtained ZnO decreased remarkably, and the ZnO obtained at 150 oC showed the best catalytic activity. Compared with ozonation alone, the degradation efficiency of phenol increased above 50% due to the catalysis of ZnO-150. In the reaction temperatures range from 5 oC to 35 oC, ZnO nanocatalyst revealed remarkable catalytic properties, and the catalytic effect of ZnO was better at lower temperature. Through the effect of tertbutanol on degradation of phenol and the catalytic properties of ZnO on degradation of nitrobenzene, it was proposed that the degradation of phenol was ascribed to the direct oxidation by ozone molecules based on solidliquid interface reaction.
Sanshool from Zanthoxylum L. Induces Apoptosis in Human Hepatocarcinoma HepG2 Cells
Yuming You,Min Zhou,Hongjia Lu,Gasper Gerald Shirima,Yajiao Cheng,Xiong Liu 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.6
Anti-proliferation and apoptosis induction activities of sanshool isolated from Zanthoxylum bungeanum (Rutaceae) in HepG2 cells were investigated. Cell proliferation was analyzed using MTT assays. Apoptotic bodies were observed under scanning electron microscopy. Nucleus staining using dichlorofluorescin diacetate (DAPI) was performed and the mitochondrial membrane potential (ΔΨm) using rhodamine-123 was observed under laser confocal microscopy. Sanshool inhibited cell proliferation in both a dose and time-dependent manner. The anti-proliferation activity was stimulated with apoptosis induction based on an increase in the sub-G1 cell population, DNA fragmentation, and typical apoptotic morphological changes. Sanshool also disrupted ΔΨm and up-regulated mRNA and protein expressions of p53 and caspase-3. Sanshool induced apoptosis via a mitochondrion-dependent pathway. Thus, sanshool is a potential anticancer medicine.
Research on Integrated Optimization of the Reverse Logistics Network
Yuming Luo 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.7
Considered the integrate of forward and reverse logistics, the separability of recycle products, the timeliness of recycle products, the paper established a location-routing-inventory control optimization model with batch transportation of recycle products. A matching hybrid genetic algorithm containing heuristic rule was introduced according the characteristics above. The algorithm used three-stage real-code that represents the transport order of vehicles. And the quantity of new products and recycle products will be determined too. The unreasonable solution will be eliminated in the iterative process of genetic algorithm. The simulated test analysis shows the validity and the correctness of the model and algorithm.
Yuming Zhao 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.7
The optimal scheduling of crude-oil operation in refineries has been researched by various groups during the past decade. Different mixed integer linear programming or mixed nonlinear programming formulations are derived. This paper proposes a novel MINLP formulation with multiple charging tanks charging a distiller overlapingly and oil residency time constraint that is based on multi-operation sequencing with synchronized start time (MOS-SST). It is different from previous formulations because of its consideration for oil residency time constraint and multiple charging tanks charging a distiller overlapingly. A branch and bound algorithm combined with the Lagrangian Relaxation Subgradient Optimization algorithm is proposed to solve this model, resulting in a satisfactory optimal result.