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Wenming Guo,Hanning Xiao,Haibo Lei,Pengzhao Gao,Wen Xie,Qing Li 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.6
In this paper, the influence of SiO2 on the microstructure and consolidation mechanism of recrystallized silicon carbide (RSiC)was studied by comparing the relationship of the weight losses and microstructural evolution with the SiO2 contents at different firing temperatures. The results showed that the presence of SiO2 resulted in a basic weight loss proportional to the SiO2 content and an additional weight loss independent of the SiO2 content. The consolidation mechanism of SiC was not altered by the introduction of SiO2, involving surface diffusion at low temperatures and an evaporation-condensation process at the high temperature, while the residual ambient atmosphere primarily including SiO(g), Si2C(g) and Si(g) inhibited the recrystallization of SiC by altering the mass transport from SiC2(g), Si2C(g) and Si(g) for pure SiC to that combined with the gaseous transport of SiO(g), Si2C(g), Si(g) and SiC(g), and the surface diffusion of C(s) at the high temperature.
Concealment of iris features based on artificial noises
Wenming Jiao,Heng Zhang,Qiyan Zang,Weiwei Xu,Shuaiwei Zhang,Jian Zhang,Hongran Li 한국전자통신연구원 2019 ETRI Journal Vol.41 No.5
Although iris recognition verification is considered to be the safest method of biometric verification, studies have shown that iris features may be illegally used. To protect iris features and further improve the security of iris recognition and verification, this study applies the Gaussian and Laplacian mechanisms and to hide iris features by differentiating privacy. The efficiency of the algorithm and evaluation of the image quality by the image hashing algorithm are selected as indicators to evaluate these mechanisms. The experimental results indicate that the security of an iris image can be significantly improved using differential privacy protection.
Wenming Jiang,Haixiao Jiang,Guangyu Li,Feng Guan,Junwen Zhu,Zitian Fan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8
In this work, microstructure, mechanical properties and fracture behavior of the magnesium/steel bimetal using compoundcasting assisted with hot-dip aluminizing were investigated, and the interface bonding mechanism of the magnesium/steelbimetal were also analyzed. The results indicate that the magnesium/steel bimetal obtained without hot-dip aluminizing hadlarger gaps through the whole interface without reaction layers between magnesium and steel, leading to a poor mechanicalbonding. After the steel substrate was hot-dip aluminized, an intermetallic layer along with an Al topcoat layer wereformed on the surface of the steel substrate, and the intermetallic layer was constituted by Fe2Al5,τ10-Al9Fe4Si3, FeAl3andτ6-Al4.5FeSi phases. In the case of the magnesium/steel bimetal obtained with hot-dip aluminizing, a compact and uniforminterface layer with an average thickness of about 17 μm that consisted of Fe2Al5,τ10-Al9Fe4Si3, FeAl3and Al12Mg17intermetalliccompounds was formed between the magnesium and the steel, obtaining a superior metallurgical bonding. The interfacelayer had much higher nano-hardnesses compared to the magnesium and steel matrixes, and its average nano-hardness wasup to 11.1 GPa, while there were respectively 1.1 and 4.2 GPa for the magnesium and steel matrixes. The shear strength ofthe magnesium/steel bimetal with hot-dip aluminizing reached to 23.3 MPa, which increased by 8.59 times than that of thecomposites without hot-dip aluminizing. The fracture of the magnesium/steel bimetal with hot-dip aluminizing representeda brittle fracture nature, initiating from the interface layer.
Wenming Huang,Libin Wang,ShengLi Li,ZhiJun Cao 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.5
Objective: An experiment was conducted to determine the effect of reduced energy density of close-up diets on metabolites, lipolysis and gluconeogenesis in cows during the transition period. Methods: Thirty-nine Holstein dry cows were blocked and assigned randomly to three groups, fed a high energy density diet (HD, 1.62 Mcal of net energy for lactation [NEL]/kg dry matter [DM]), a medium energy density diet (MD, 1.47 Mcal NEL/kg DM), or a low energy density diet (LD, 1.30 Mcal NEL/kg DM) prepartum; they were fed the same lactation diet to 28 days in milk (DIM). All the cows were housed in a free-stall barn and fed ad libitum. Results: The reduced energy density diets decreased the blood insulin concentration and increased nonesterified fatty acids (NEFA) concentration in the prepartum period (p<0.05). They also increased the concentrations of glucose, insulin and glucagon, and decreased the concentrations of NEFA and β-hydroxybutyrate during the first 2 weeks of lactation (p<0.05). The plasma urea nitrogen concentration of both prepartum and postpartum was not affected by dietary energy density (p>0.05). The dietary energy density had no effect on mRNA abundance of insulin receptors, leptin and peroxisome proliferator-activated receptor-γ in adipose tissue, and phosphoenolpyruvate carboxykinase, carnitine palmitoyltransferase-1 and peroxisome proliferator-activated receptor-α in liver during the transition period (p>0.05). The HD cows had higher mRNA abundance of hormone-sensitive lipase at 3 DIM compared with the MD cows and LD cows (p = 0.001). The mRNA abundance of hepatic pyruvate carboxykinase at 3 DIM tended to be increased by the reduced energy density of the close-up diets (p = 0.08). Conclusion: The reduced energy density diet prepartum was effective in controlling adipose tissue mobilization and improving the capacity of hepatic gluconeogenesis postpartum.
Wenming Zhang,Xiaofan Lu,Jiaqi Chang,Genmin Tian,Lianfeng Xia 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.6
Suspension bridges bear large eccentric live loads in rush hours when most vehicles travel in one direction on the left or right side of the bridge. With the increasing number and weight of vehicles and the girder widening, the eccentric live load effect on the bridge behavior, including bending and distortion of the main girder, gets more pronounced, even jeopardizing bridge safety. This study proposes an analytical algorithm based on multi-catenary theory for predicting the suspension bridge responses to eccentric live load via the nonlinear generalized reduced gradient method. A set of governing equations is derived to solve the following unknown values: the girder rigid-body displacement in the longitudinal direction; the horizontal projection lengths of main cable’s segments; the parameters of catenary equations and horizontal forces of the side span cable segments and the leftmost segments of middle span cables; the suspender tensions and the bearing reactions. Then girder’s responses, including rigid-body displacement in the longitudinal direction, deflections, and torsion angles; suspenders’ responses, including the suspender tensions and the hanging point displacements; main cables’ responses, including the horizontal forces of each segment; and the longitudinal displacement of the pylons’ tower top under eccentric load can be calculated. The response of an exemplar suspension bridge with three spans of 168, 548, and 168 m is calculated by the proposed analytical method and the finite element method in two eccentric live load cases, and their results prove the former’s feasibility. The nonuniform distribution of the live load in the lateral direction is shown to impose a greater threat to suspension bridge safety than that in the longitudinal direction, while some other specific features revealed by the proposed method are discussed in detail.
Wenming Sun,Jing Liu,Hong Wang,Zhenwei Zhang,Liang Zhang,Yuxiang Bu 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.4
For guidance for developing Fe/Co-Sn-based anode materials for lithium-ion batteries, the mechanical, thermodynamic and electronic properties of FeSn5 and CoSn5 intermetallic phases under pressures ranging from 0 to 30 GPa have been investigated systematically using first-principles total-energy calculations within the framework of the generalized gradient approximation. The pressure was found to have significant effects on the mechanical, thermodynamic and electronic properties of these compounds. In the selected pressure range, CoSn5 has a more negative formation enthalpy than FeSn5. Based on the calculated elastic constants, the bulk modulus, shear modulus, and Young’s modulus were determined via the Viogt-Reuss-Hill averaging scheme. The variations of specific heats at constant volume for FeSn5 and CoSn5 in a wide pressure (0 - 30 GPa) and temperature (0 - 1000 K) range are also predicted from phonon density of states calculation. The calculated results suggested that both FeSn5 and CoSn5 are mechanically stable at pressure from 0 to 30 GPa. FeSn5 is dynamically stable at pressure up to, 30 GPa, at least, however, CoSn5 is dynamically stable no higher than 15 GPa.