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Shear Thickening Polishing of Black Lithium Tantalite Substrate
B. H. Lyu,Q. Shao,W. Hang,S. H. Chen,Q. K. He,J. L. Yuan 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.9
To achieve high efficiency in the polishing process to obtain a high surface quality of black LT substrate (a kind of soft brittle material), shear thickening polishing (STP), which is a “gentle” finishing process developed in recent years, was employed in this study. The influence of three key parameters in the STP process including polishing speed, diamond abrasive size and diamond abrasive concentration were analyzed. To investigate the potential mechanical effect of the nanometre abrasive, nano-SiO 2 abrasive particles were added in the slurry, and the concentration of SiO 2 abrasive was also taken as a factor. Taguchi method was utilized to evaluate the influence of the four factors and optimize the polishing conditions. The surface roughness (Ra/Rz) was used as the evaluation index, and the optimized polishing conditions were verified through experiments. Diamond abrasive size has the most significant effect on Ra/Rz, followed by diamond abrasive concentration and then SiO 2 concentration, as the polishing speed has been selected and limited in a small variation rang according to the previous study. Based on the S/N average response analysis, the surface quality is the best under the conditions with 8000# diamond abrasive, 5 wt% diamond abrasive concentration, 90 rpm polishing speed and 10 wt% SiO 2 concentration. After 4 min polishing, the surface roughness Ra/Rz is reduced rapidly from 200.5/1374.6 to 4.2/22.1 nm without embedded abrasive particles on the surface of the black LT substrate. It also shows that the mechanical effect plays a dominant role in the material removal. A certain amount (10 wt% in this study) of nano-SiO 2 can reduce friction between solid colloidal and workpiece, and helps to improve surface quality.
Choi, H.S.,Kim, S.J.,Choi, H.W.,Park, C.E.,Gao, Y.J.,Hang, Y.,Jeong, S.Y.,Kim, J.P.,Bae, J.S.,Cho, C.R. ELSEVIER 2017 Current Applied Physics Vol.17 No.8
<P>We prepared single-crystal Si nanoparticles (Si NPs) similar to 50 nm in diameter using a laser photopyrolysis technique and formed a nitrogen-doped carbon layer on them using pyrrole and FeCl3 to increase the cycle stability of the Si anodes during volume expansion and contraction. The surface chemical bonding states of the nitrogen-doped carbon-coated Si NPs were investigated. The specific capacity and capacity retention of the sample with 1 g of FeCl3 were the highest at approximately 967.1 mAh g(-1) and 87.3% after 300 cycles at 1 C, respectively. The diffusion coefficient of Li ions after 1000 test cycles was 9.64 x 10(-8) cm(2) s(-1). The higher cycling stability of the Si@NC NPs could be attributed to the nitrogen doped carbon layers, which provided an efficient transport pathway for the electrons. (C) 2017 Elsevier B.V. All rights reserved.</P>
Hung, C.D.,Hong, C.H.,Kim, S.K.,Lee, K.H.,Park, J.Y.,Dung, C.D.,Nam, M.W.,Choi, D.H.,Lee, H.I. International Society for Horticultural Science ; 2016 Scientia horticulturae Vol.211 No.-
<P>Efficient protocols for in vitro shoot growth and ex vitro root formation from in vitro-derived shoots under light-emitting diodes (LEDs) with simple ventilation were developed for rabbiteye blueberry cv. 'Titan'. Red LEDs promoted shoot elongation while blue LEDs induced short shoots with enhanced accumulation of leaf chlorophyll contents. A combined treatment of 80% red with 20% blue LEDs was found the most suitable for plant growth, and more effective than 50% red mixed with 50% blue LEDs or fluorescent lamps as the control treatment. The use of ventilated vessels with ambient CO2 enrichment from a growth chamber resulted in healthy plants having greatly improved shoot length, leaf expansion, leaf chlorophyll contents and dry weight of both shoots and roots. In vitro-cultured shoots could be directly rooted at 100% under non-sterile conditions using a perlite-peat mixture with careful controls of high humidity. These results suggest that LEDs, particularly when coupled with ventilated vessels, should be used as a primary light source for replacing conventional fluorescent tubes in large-scale production of rabbiteye blueberries. (C) 2016 Elsevier B.V. All rights reserved.</P>
Applicability of CPT-based methods in predicting toe bearing capacities of driven piles in sand
Hung, L. C.,Nguyen, T. D.,Lee, J. H.,Kim, S. R. SPRINGER SCIENCE + BUSINESS MEDIA 2016 Acta geotechnica Vol.11 No.2
<P>This paper presents a study on applicability of predicting toe bearing capacities from cone penetration test (CPT) for PHC (pretensioned spun high-strength concrete) driven piles into deep sandy deposits in the Nakdong River deltaic area west of Busan City in South Korea. Using toe bearing capacities obtained from pile driving analyzer (PDA) tests as reference values, which were reliably calibrated by on-site O-cell tests, the applicability of the CPT-based methods was evaluated using a statistical rank index (RI). A total of 82 piezocone penetration test soundings and 190 PDA test piles were used for reliability analysis in this study. Three correction steps were applied to obtain reliable PDA and CPT data sets before ranking is carried out. The RI index is combined from four criteria: (1) the best-fit line, (2) the arithmetic mean and standard deviation, (3) the cumulative probabilities, and (4) the log-normal and histogram distributions. Based on these criteria the performance of some SPT-based methods in the literature is evaluated.</P>