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Distribution of Yb <sup>3+</sup> and Yb <sup>2+</sup> Ions along YbF <sub/>3</sub> -Doped BaF <sub/>2</sub> Crystals
摘要： BaF2 crystals doped with 0.05, 0.1, and 0.2 mol% YbF3 are grown using vertical Bridgman method. Transparent crystals, (cid:2)5–6 cm in length, (cid:2)10 mm in diameter, are obtained in vacuum using a shaped graphite furnace. The absorption spectra reveal the characteristic absorption bands of the Yb3+and Yb2+ ions in the as-grown crystals. The distribution of ytterbium ions along the crystals and the e?ective segregation coe?cient of the Yb3+ and Yb2+ ions in the BaF2 host are determined by using the optical absorption method. The crystals are cleaved from the bottom to the top into 10–17 slices of (cid:2)2 mm thickness. The optical absorption spectrum of every slice is recorded. The dopant distribution along the crystal is estimated studying the absorption spectrum of every slice. Two well-shaped and strong characteristic bands, 968 nm and 352 nm, respectively, are chosen. The Yb3+ and Yb2+ ions are not uniformly distributed along the BaF2 crystals. The calculated e?ective segregation coe?cients of the Yb3+ range from 0.7 to 0.84 and from 0.66 to 0.82 for Yb2+ ions.
关键词： segregation coefficient,ytterbium ions,optical properties,barium fluoride crystals
更新于2025-09-09 09:28:46
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Ag release from sputtered Ag/a:C nanocomposite films after immersion in pure water and NaCl solution
摘要： Diamond-like carbon (DLC) coatings doped with Ag nanoparticles are promising materials for several application, as, for example, a biomaterial. In addition to their numerous properties, when doped with silver, DLCs can acquire antibacterial properties. In this study, Ag/a:C films were deposited by unbalanced magnetron sputtering. The dimension and distribution of silver nanoparticles in the carbon matrix were characterized before and after immersion in different liquid environments, ultra-pure water and NaCl (0.9%). Inductively coupled plasma-optical emission spectroscopy was used to quantify the Ag ions released from the film. Based on the aspect of Ag nanoparticles on the films surface, suggested by atomic force microscopy analysis, scanning electron microscopy was performed to access the dimension and the distribution of the nanoparticles at the surface and, then, to calculate the mass of Ag in the film, before and after exposure to both liquids. Agglomeration and coalescence of the nanoparticles in the film surface were studied and information about the segregation from the bulk to the surface was achieved, also confirmed by X-ray photoelectron spectroscopy analysis.
关键词： Coalescence,Sputtering,Ions released,Silver,Particles,Segregation,Amorphous carbon
更新于2025-09-04 15:30:14
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A Novel Weakly-supervised approach for RGB-D-based Nuclear Waste Object Detection and Categorization
摘要： This paper addresses the problem of RGBD-based detection and categorization of waste objects for nuclear decommissioning. To enable autonomous robotic manipulation for nuclear decommissioning, nuclear waste objects must be detected and categorized. However, as a novel industrial application, large amounts of annotated waste object data are currently unavailable. To overcome this problem, we propose a weakly-supervised learning approach which is able to learn a deep convolutional neural network (DCNN) from unlabelled RGBD videos while requiring very few annotations. The proposed method also has the potential to be applied to other household or industrial applications. We evaluate our approach on the Washington RGB-D object recognition benchmark, achieving the state-of-the-art performance among semi-supervised methods. More importantly, we introduce a novel dataset, i.e. Birmingham nuclear waste simulants dataset, and evaluate our proposed approach on this novel industrial object recognition challenge. We further propose a complete real-time pipeline for RGBD-based detection and categorization of nuclear waste simulants. Our weakly-supervised approach has demonstrated to be highly effective in solving a novel RGB-D object detection and recognition application with limited human annotations.
关键词： nuclear waste decommissioning,autonomous waste sorting and segregation,nuclear waste detection and categorization
更新于2025-09-04 15:30:14