University of Trento

About: University of Trento is a education organization based out in Trento, Italy. It is known for research contribution in the topics: Population & Context (language use). The organization has 10527 authors who have published 30978 publications receiving 896614 citations. The organization is also known as: Universitá degli Studi di Trento & Universita degli Studi di Trento.

Attention-Based Adaptive Spectral–Spatial Kernel ResNet for Hyperspectral Image Classification

Abstract: Hyperspectral images (HSIs) provide rich spectral–spatial information with stacked hundreds of contiguous narrowbands. Due to the existence of noise and band correlation, the selection of informative spectral–spatial kernel features poses a challenge. This is often addressed by using convolutional neural networks (CNNs) with receptive field (RF) having fixed sizes. However, these solutions cannot enable neurons to effectively adjust RF sizes and cross-channel dependencies when forward and backward propagations are used to optimize the network. In this article, we present an attention-based adaptive spectral–spatial kernel improved residual network ( A2S2K-ResNet ) with spectral attention to capture discriminative spectral–spatial features for HSI classification in an end-to-end training fashion. In particular, the proposed network learns selective 3-D convolutional kernels to jointly extract spectral–spatial features using improved 3-D ResBlocks and adopts an efficient feature recalibration (EFR) mechanism to boost the classification performance. Extensive experiments are performed on three well-known hyperspectral data sets, i.e., IP, KSC, and UP, and the proposed A2S2K-ResNet can provide better classification results in terms of overall accuracy (OA), average accuracy (AA), and Kappa compared with the existing methods investigated. The source code will be made available at https://github.com/suvojit- $0\times 55$ aa/A2S2K-ResNet.

Attractive Fermi Gases with Unequal Spin Populations in Highly Elongated Traps

Abstract: We investigate two-component attractive Fermi gases with imbalanced spin populations in trapped one-dimensional configurations. The ground state properties are determined with the local density approximation, starting from the exact Bethe-ansatz equations for the homogeneous case. We predict that the atoms are distributed according to a two-shell structure: a partially polarized phase in the center of the trap and either a fully paired or a fully polarized phase in the wings. The partially polarized core is expected to be a superfluid of the Fulde-Ferrell-Larkin-Ovchinnikov type. The size of the cloud as well as the critical spin polarization needed to suppress the fully paired shell are calculated as a function of the coupling strength.

Copper and Nitrogen co-doped TiO2 photocatalyst with enhanced optical absorption and catalytic activity

Abstract: Cu–N-codoped TiO 2 photocatalyst is synthesized by sol–gel method to obtain enhanced optical absorption in the visible region. Optimum concentrations of Cu and N were obtained by maximizing the photocatalytic activity for the monodoped (Cu or N) TiO 2 . These optimized concentrations were used for synthesizing (Cu, N)–codoped TiO 2 . The photocatalysts were characterized using XRD, micro-Raman, SEM, XPS, BET surface area analyzer, UV–vis diffuse reflectance spectroscopy and photoluminescence. XPS study suggests the incorporation of Cu 2+ into TiO 2 lattice, which assists N to substitutionally replace oxygen in codoped TiO 2 , while maintaining the anatase phase even after doping. N-doping creates minor variation in the energy band gap of TiO 2 reducing it upto 3.0 eV, while Cu doping was able to narrow the band gap to 2.2 eV mainly due to the localized levels of Cu-3d states and shifting of Ti-3d states to lower energy (due to oxygen vacancies) in the band-gap as deduced from XPS data and confirmed by the DFT calculation. In (Cu, N)–codoped TiO 2 , visible light absorption is higher than the other TiO 2 samples, a feature that is mainly attributed to the formation of an isolated intermediate band (IB) occurring due to the strong hybridization between Cu 3d and N 2p orbitals. This IB contributes to visible light absorption by two step optical transition with the first transition from valence band (VB) to IB and the second from IB to conduction band (CB). The dopant species may also act to reduce the charge carrier recombination by acting as the trapping sites for photogenerated charges. (Cu, N)–codoped TiO 2 was able to degrade Methylene Blue dye and p -Nitrophenol solution under light irradiation with significantly better rate in comparison to monodoped and undoped TiO 2 . High photocatalytic activity is attributed to the presence of IB in the energy band gap of TiO 2 , which creates the synergic effect by higher visible light absorption and lower recombination of photogenerated charges.

Bauxite ‘red mud’ in the ceramic industry. Part 1: thermal behaviour

Abstract: Samples of red mud, by-products of alumina production from bauxite, are studied in the 120–1400°C interval. An extensive characterization was performed by thermal and X-ray diffraction analyses. The identification of gaseous species released upon heating was carried out by coupling the thermal analizer with a gas-chromatographic/mass spectrometer. Density evolution was also determined as a function of the heat treatment. Results indicate primary H2O release from aluminium hydroxides, followed by carbonate decomposition with CO2 evolution below 900°C. Alkaline oxides, mainly CaO and Na2O, lead to the formation of Ca3Al2O6 and NaAlSiO4 between 900 and 1100°C. At the highest temperatures, reduction of Fe3+ to Fe2+, involving O2 release, promotes the formation of Fe2TiO4, with the disappearance of the rutile-TiO2 phase. The various solid state reactions, ascertained at different stages of the heating process, and possible mass balances are discussed with reference to the state diagrams of principal red mud components.