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Pradeep Singh,Vikas Shrivastava,I. B. Singh,D. P. Mondal 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6
Three group of porous Ti4Al4Co samples made of (i) unmilled powder and vacuum sintered (S1), (ii) milled powder andvacuum sintered (S2), and (iii) milled powder sintered in open atmosphere (S3) were prepared. Phase change, crystallite sizeand lattice strain variations due to powder milling and sintering were examined by SEM and XRD. To evaluate mechanicalproperty, alloy samples were subjected to the uniaxial compression test. For corrosion analysis, Tafel plot was plotted usingelectrochemical corrosion system in simulated body fluid (SBF) as electrolytic medium. From the obtained results, it wasfound that significant microstructural transformation takes place due to milling and change in sintering atmosphere. SampleS1possessed 139 MPa compressive strength, which was about 48% and 76% higher than samples S2and S3respectively. Corrosion current density for S3was found as 5.5 ± 0.3 μA/cm2 which is 7 and 12 times lower than S2and S1samples.
Pradeep Adhikari,신만석,전자영,김현우,홍승범,서창완 한국생태학회 2018 Journal of Ecology and Environment Vol.42 No.4
Background: Subalpine ecosystems at high altitudes and latitudes are particularly sensitive to climate change. In South Korea, the prediction of the species richness of subalpine plant species under future climate change is not well studied. Thus, this study aims to assess the potential impact of climate change on species richness of subalpine plant species (14 species) in the 17 mountain national parks (MNPs) of South Korea under climate change scenarios’ representative concentration pathways (RCP) 4.5 and RCP 8.5 using maximum entropy (MaxEnt) and Migclim for the years 2050 and 2070. Results: Altogether, 723 species occurrence points of 14 species and six selected variables were used in modeling. The models developed for all species showed excellent performance (AUC > 0.89 and TSS > 0.70). The results predicted a significant loss of species richness in all MNPs. Under RCP 4.5, the range of reduction was predicted to be 15.38–94.02% by 2050 and 21.42–96.64% by 2070. Similarly, under RCP 8.5, it will decline 15.38–97.9% by 2050 and 23.07–100% by 2070. The reduction was relatively high in the MNPs located in the central regions (Songnisan and Gyeryongsan), eastern region (Juwangsan), and southern regions (Mudeungsan, Wolchulsan, Hallasan, and Jirisan) compared to the northern and northeastern regions (Odaesan, Seoraksan, Chiaksan, and Taebaeksan). Conclusions: This result indicates that the MNPs at low altitudes and latitudes have a large effect on the climate change in subalpine plant species. This study suggested that subalpine species are highly threatened due to climate change and that immediate actions are required to conserve subalpine species and to minimize the effect of climate change.
Pradeep Kankeri,S. Suriya Prakash,Sameer Kumar Sarma Pachalla 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.5
The objective of this study is to understand the behaviour of hollow core slabs strengthened with FRP and hybrid techniques through numerical and analytical studies. Different strengthening techniques considered in this study are (i) External Bonding (EB) of Carbon Fiber Reinforced Polymer (CFRP) laminates, (ii) Near Surface Mounting (NSM) of CFRP laminates, (iii) Bonded Overlay (BO) using concrete layer, and (iv) hybrid strengthening which is a combination of bonded overlay and NSM or EB. In the numerical studies, three-dimensional Finite Element (FE) models of hollow core slabs were developed considering material and geometrical nonlinearities, and a phased nonlinear analysis was carried out. The analytical calculations were carried out using Response-2000 program which is based on Modified Compression Field Theory (MCFT). Both the numerical and analytical models predicted the behaviour in agreement with experimental results. Parametric studies indicated that increase in the bonded overlay thickness increases the peak load capacity without reducing the displacement ductility. The increase in FRP strengthening ratio increased the capacity but reduced the displacement ductility. The hybrid strengthening technique was found to increase the capacity of the hollow core slabs by more than 100% without compromise in ductility when compared to their individual strengthening schemes.