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Zhang T.,Du W.Y.,Zhan C.Y.,Wang M.M.,Deng H.W.,Xie Z.M.,Li H. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8
The synergistic effect of ZrC nanoparticle pining and Re solution in W matrix on the thermal stability of tungsten was studied by investigating the evolution of the microstructure, hardness and tensile properties after annealing in a temperature range of 1000e1700 C. The results of metallography, electron backscatter diffraction pattern and Vickers micro-hardness indicate that the rolled W-1wt%Re-0.5 wt% ZrC alloy has a higher recrystallization temperature (1600 Ce1700 C) than that of the rolled pure W (1200 C), W-0.5 wt%ZrC (1300 C), W-0.5 wt%HfC (1400e1500 C) and WeK-3wt%Re alloy fabricated by the same technology. The molecular dynamics simulation results indicated that solution Re atoms in W matrix can slow down the self-diffusion of W atoms and form dragging effect to delay the growth of W grain, moreover, the diffusion coefficient decrease with increasing Re content. In addition, the ZrC nanoparticles can pin the grain boundaries and dislocations effectively, preventing the recrystallization. Therefore, synergistic effect of solid solution Re element and dispersed ZrC nanoparticles significantly increase recrystallization temperature
Chang Y.Jeong,Jung G.Cho,Ju W.Baek,Du I.Song,Dong W.Yoo 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-
A novel zero-voltage-transition (ZVT) isolated PWM boost converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter[8]. A simple auxiliary circuit which includes only one active switch provides zero-voltage-switching (ZVS) condition to all semiconductor devices. (Two active switches are required for the previous ZVT converter.) This leads to reduced cost and simplified control circuit comparing to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 kW, 100 kHz laboratory prototype.
Loss-Separation Study on Silica-insulated Gas-atomized Fe-Si-Al Soft Magnetic Composites
T. T. Xu,B. W. Zhang,Z. Shi,W. W. Guan,K. Wan,X. Y. Shi,W. Liu,H. L. Su,Z. Q. Zou,Y. W. Du 한국자기학회 2020 Journal of Magnetics Vol.25 No.2
Fe-Si-Al soft magnetic composites were composed of gas-atomized Fe-9.6wt.%Si-5.4wt.%Al alloy powders insulated with silica nanoparticles. The influence of silica insulation content on the core’s magnetic properties was studied. It was found that increasing the silica mass ratio deteriorated the effective permeability and core loss in the frequency range of 40-120 kHz, while improved the quality factor at 100 kHz and DC-bias performance. The effective demagnetizing field reflected by density and the core’s volume resistivity may cause the variations of these magnetic parameters. Loss separation fitting was performed using the Bertotti formula, indicating that silica insulation increased the hysteresis loss and reduced the eddy-current loss. The hysteresis loss took over at the frequency lower than 120 kHz in this work. With increasing the frequency, the eddy-current loss grew more quickly than the hysteresis loss. Therefore, different methods should be adopted to reduce the core loss according to the core’s application frequency.
Preparation and thermoelectric properties of AgPb18SbTe20−xSex (x = 1, 2, 4) materials
H. Li,K.F. Cai,Y. Du,H.F. Wang,S.Z. Shen,X.L. Li,C.W. Zhou,Y.Y. Wang 한국물리학회 2012 Current Applied Physics Vol.12 No.1
AgPb18SbTe20xSex (x ¼ 1, 2, 4) bulk materials were prepared by combining hydrothermal synthesis and melting. Thermoelectric properties were measured from room temperature up to 773K. The materials showed n-type conduction and exhibited degenerate semiconductor behavior. The power factors of the materials varied greatly with increase of Se content (x). Partial substitution of Se for Te in AgPb18SbTe20resulted in remarkable reduction of thermal conductivity in the whole temperature range and increase of power factor at lower temperatures; therefore, the dimensionless figure of merit, ZT, was enhanced below 600K. A maximum ZT value of w0.82 is obtained at 523K for the AgPb18SbTe18Se2 sample.
Zheng, S.L,Du L,Zhou Y.W. 한국지능정보시스템학회 2022 한국지능정보시스템학회 학술대회논문집 Vol.2022 No.6
Along with the Internet economy developing entrepreneurship has become the good choice of college students. However, there are still many problems. School-enterprise cooperation provides a new direction for training students to conduct cross-border e-commerce entrepreneurship. Based on the triple helix theory, it is found that conditions of incubator, school-enterprise cooperation degree, entrepreneurship education and entrepreneurial environment of universities directly affect the success rate of incubator of cross-border e-commerce entrepreneurial projects.
Du, W.,Li, Y.J.,Zhao, G.Y.,Yin, Y.L.,Kong, X.F. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.8
Two experiments were carried out to study the effects of dietary energy level on nutrient digestion, nitrogen (N) utilization, growth performance, insulin-like growth factor-I (IGF-I), and insulin-like growth factor binding protein-3 (IGFBP-3) in plasma, liver and longissimus dorsi muscle in growing-finishing pigs. In experiment 1 (Exp 1), 15 castrated male pigs (Duroc${\times}$Landrace${\times}$Large White) (Body weight, BW, 55.6${\pm}$1.8 kg) were divided into three groups and fed rations containing 13.33, 14.87 and 17.35 MJ digestible energy (DE)/kg as treatments I, II and III, respectively, using soybean oil as an energy source. The experiment lasted 8 days and faecal and urinary samples were collected during the last 3 days. The results showed that the digestibility of dry matter (DM), energy and N was increased from treatments I to III (p<0.01). N-retention and N-retention rate were not influenced by dietary DE level (p>0.05). In experiment 2 (Exp 2), 36 female pigs (Duroc${\times}$Landrace${\times}$Large White) (BW 41.5${\pm}$3.8 kg) were divided into three groups. The pigs were fed with the same three rations used in Exp 1 for 60 days. At the end of Exp 2, eight pigs were selected from each group for blood sampling and 4 pigs for slaughter trial. The results indicated that average daily feed intake (ADFI) and N-intake were significantly decreased (p<0.01), and DE intake (p<0.01) and average daily gain (ADG) (p<0.05) were increased. IGF-I and IGFBP-3 in plasma were increased (p<0.05). No significant differences in IGF-I and IGFBP-3 in liver and longissimus dorsi muscle were found between different treatments. It was concluded that higher dietary DE level improved nutrient digestibility, ADG and feed/gain ratio when soybean oil was used as an energy source in the ration of growing-finishing pigs. No significant differences were found in Nretention and IGF-I and IGFBP-3 in liver and longissimus dorsi muscle between different treatments.
Du, J.,Chen, H.,Yang, H.,Sang, R.,Qian, Y.,Li, Y.,Zhu, G.,Mao, Y.,He, W.,Kang, D.J. Elsevier 2013 Microporous and mesoporous materials Vol.182 No.-
A porous Nd-doped TiO<SUB>2</SUB> monolith was successfully synthesized with polystyrene spheres as a template using a sol-gel method followed by calcination at high temperature. The porous Nd-doped TiO<SUB>2</SUB> monolith was characterized by X-ray diffractometry, scanning electron microscopy and Brunauer-Emmett-Teller measurements. Nd doping can increase the TiO<SUB>2</SUB> surface area by hindering the growth of large TiO<SUB>2</SUB> particles, and suppressing the recombination of photo-produced hole/electron (h<SUP>+</SUP>/e<SUP>-</SUP>) pairs. Moreover, its porous structure can provide a large surface area, facilitating enhanced adsorption and fast transfer of pollutants. To evaluate the photocatalytic activity of the porous Nd-doped TiO<SUB>2</SUB> monolith, the photo-degradation for methyl orange was investigated under UV-Vis irradiation. The porous 0.5% Nd-doped TiO<SUB>2</SUB> monolith showed better behavior than the other as-prepared samples and Degussa P25 due to its narrow band gap, high efficiency for h<SUP>+</SUP>/e<SUP>-</SUP> pair separation, and large surface area. The synergistic combination of Nd doping and the porous structure is a promising material design strategy for use in the degradation of organic pollutants.