The joint hyperspectral image (HSI) and light detection and ranging (LiDAR) data classification aims to interpret ground objects at more detailed and precise level. Although deep learning methods ...have shown remarkable success in the multisource data classification task, self-supervised learning has rarely been explored. It is commonly nontrivial to build a robust self-supervised learning model for multisource data classification, due to the fact that the semantic similarities of neighborhood regions are not exploited in the existing contrastive learning framework. Furthermore, the heterogeneous gap induced by the inconsistent distribution of multisource data impedes the classification performance. To overcome these disadvantages, we propose a nearest neighbor-based contrastive learning network (NNCNet), which takes full advantage of large amounts of unlabeled data to learn discriminative feature representations. Specifically, we propose a nearest neighbor-based data augmentation scheme to use enhanced semantic relationships among nearby regions. The intermodal semantic alignments can be captured more accurately. In addition, we design a bilinear attention module to exploit the second-order and even high-order feature interactions between the HSI and LiDAR data. Extensive experiments on four public datasets demonstrate the superiority of our NNCNet over state-of-the-art methods. The source codes are available at https://github.com/summitgao/NNCNet .
The use of ℓ p (p = 1,2) norms has largely dominated the measurement of loss in neural networks due to their simplicity and analytical properties. However, when used to assess the loss of visual ...information, these simple norms are not very consistent with human perception. Here, we describe a different "proximal" approach to optimize image analysis networks against quantitative perceptual models. Specifically, we construct a proxy network, broadly termed ProxIQA, which mimics the perceptual model while serving as a loss layer of the network. We experimentally demonstrate how this optimization framework can be applied to train an end-to-end optimized image compression network. By building on top of an existing deep image compression model, we are able to demonstrate a bitrate reduction of as much as 31% over MSE optimization, given a specified perceptual quality (VMAF) level.
Objective image quality assessment (IQA) plays an important role in the development of multimedia applications. Prediction of IQA metric should be consistent with human perception. The release of the ...newest IQA database (TID2013) challenges most of the widely used quality metrics (e.g., peak-to-noise-ratio and structure similarity index). We propose a new methodology to build the metric model using a regression approach. The new IQA score is set to be the nonlinear combination of features extracted from several difference of Gaussian (DOG) frequency bands, which mimics the human visual system (HVS). Experimental results show that the random forest regression model trained by the proposed DOG feature is highly correspondent to the HVS and is also robust when tested by available databases.
A new metal‐free radical 5‐exo‐dig cyclization of phenol‐linked 1,6‐enynes with O2, 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO), and tBuONO is described. With this general method, carbonylated ...benzofurans can be accessed through incorporation of two oxygen atoms into the product from O2 and TEMPO through dioxygen activation and oxidative cleavage of the NO bond, respectively.
Benzofurans are obtained by the tBuONO‐initiated radical 5‐exo‐dig cyclization of enynes under mild and metal‐free conditions. The two oxygen atoms that constitute the newly formed carbonyl groups of the benzofuran system originate from O2 and 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO), respectively.
The 1, n -enyne annulation reaction has emerged as one of the most powerful and straightforward tools to build carbo- and hetero-cyclic frameworks that are found in numerous natural products, ...pharmaceuticals and functional materials. Although the 1, n -enyne annulation methods have been well documented to date, there is a tremendous challenge with current methodologies for simultaneously incorporating external functional groups into the resulting cyclic systems. Recent advances in the radical-mediated oxidative 1, n -enyne annulation strategy involving C–H functionalization have been proven to be an ideal alternative to overcome these disadvantages. Such radical-mediated oxidative 1, n -enyne annulation can be accomplished by two different C–H functionalization modes: One proceeds through generation of the carbon-centered radicals from C–H bond direct oxidative cleavage and their subsequent addition across the CC bond or CC bond enabling the 1, n -enyne annulation; the other employs the C–H bonds as the radical acceptors to terminate the initial oxidative radical-triggered annulation of 1, n -enyne. In addition, during many annulation processes the inherent C–H bonds of 1, n -enynes were functionalized. Here, we summarize recent progress in radical-mediated oxidative annulations of 1, n -enynes involving two different conceptual C–H functionalization strategies and the inherent C–H functionalization with an emphasis on the scope, limitations and mechanisms of these different reactions.
Two-dimensional materials with high carrier mobility and tunable magnetism are in high demand for nanoelectronic and spintronic applications. Herein, we predict a novel two-dimensional monolayer KTlO ...that possesses an indirect band gap of 2.25 eV (based on HSE06 calculations) and high carrier mobility (450 cm2 V-1 s-1 for electrons and 160 cm2 V-1 s-1 for holes) by means of ab initio calculations. The electron mobility can be increased up to 26 280 cm2 V-1 s-1 and 54 150 cm2 V-1 s-1 for bilayer and trilayer KTlO, respectively. The KTlO monolayer has a calculated cleavage energy of 0.56 J m-2, which suggests exfoliation of the bulk material as a viable means for the preparation of mono- and few-layer materials. Remarkably, the KTlO monolayer demonstrates tunable magnetism and half-metallicity with hole doping, which are attributed to the novel Mexican-hat-like bands and van Hove singularities in its electronic structure. Furthermore, monolayer KTlO exhibits moderate optical absorption over the visible light and ultraviolet regions. The band gap value and band characteristics of monolayer KTlO can be substantially manipulated by biaxial and uniaxial strains to meet the requirement of various applications. All these novel properties make monolayer KTlO a promising functional material for future nanoelectronic and spintronic applications.
Ammonia removal and recovery from wastewater have been a critical issue worldwide and a key to achieve a sustainable nitrogen cycle and circular economy. Conventional ammonia removal via air ...stripping needs pH adjustment pretreatment with chemical additives while electrokinetic technologies can provide electrochemically in-situ pH control without chemicals needed. The integration of electrokinetic and air stripping technologies is a potential process for the simultaneous removal/recovery of ammonia/ammonium from wastewater. This study consolidates research findings of the separate research domains of electrokinetic and air stripping technologies and aims to identify an integrated process for the simultaneous nitrogen removal/recovery from waste streams. Process integration involves research on improved ammonia removal efficiencies and liquid side mass transfer performances using innovative air stripping system designs and gas-liquid contactors, e.g., rotating packed beds and membrane contactors, compared with the conventional stripping tower process. Findings in the applications and performances of electrokinetic separation processes, including electrodialysis, electrodeionization, capacitive deionization, electrochemical cell, and bio-electrochemical systems, on the removal/recovery of ammonia/ammonium, are a crucial link to integration as well. Energy consumptions between 5–20.4 kWh/kg–NH4-N with a removal ratio of around 90% for electrokinetic processes are currently achievable, and some groups can be implemented on the biodegradable organic substrates from urine. Innovative hybrid technologies of ammonia nitrogen removal/recovery with energy production and co-product valorization that reduce the overall cost and energy consumption via integrated processes optimization, and discussions on the environmental impact assessment (via life cycle assessment) and economic benefit analysis (via techno-economic analysis) of ammonia recovery practices on waste streams are investigated.
•Advanced NH3 stripping processes enhance the gas-liquid mass transfer rate.•Energy-efficient electrokinetic processes facilitate NH4+/NH3 recovery.•Novel hybrid technology for NH4+/NH3 recovery and energy production was discussed.•Establishes a sustainable nitrogen cycle to promote environmental and economic benefits.
Sub‐freezing temperature presents a significant challenge to the survival of current Li‐ion batteries (LIBs) as it leads to low capacity retention and poor cell rechargeability. The electrolyte in ...commercial LIBs relies too heavily on ethylene carbonate (EC) to produce a stable solid electrolyte interphase (SEI) on graphite (Gr) anodes, but its high melting point (36.4 °C) severely restricts ion transport below 0 °C, causing energy loss and Li plating. Here, a class of EC‐free electrolytes that exhibits remarkable low‐temperature performance without compromising cell lifespan is reported. It is found that at sub‐zero temperatures, EC forms highly resistive SEI that seriously impedes electrode kinetics, whereas EC‐free electrolytes create a highly stable, low‐impedance SEI through anion decomposition, which boosts capacity retention and eliminates Li plating during charging. Pouch‐type LiCoO2 (LCO)|Gr cells with EC‐free electrolytes sustain 900 cycles at 25 °C with 1 C charge/discharge, and LiNi0.85Co0.10Al0.05O2 (NCA)|Gr cells last 300 cycles at −15 °C with 0.3 C charge, both among the best‐performing in the literature under comparable conditions. Even at −50 °C, the NCA|Gr cell with EC‐free electrolytes still delivers 76% of its room‐temperature capacity, outperforming EC‐based electrolytes.
A new class of ethylene carbonate (EC)‐free electrolytes, based on methyl acetate and fluorinated ethers, is proposed for Li‐ion batteries operating at sub‐freezing temperatures. The EC‐free electrolyte demonstrates all‐round performance advantages over the traditional EC‐based electrolyte and presents a viable solution to improve the capacity retention and rechargeability of metal‐ion batteries in cold climates.
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•Dynamic recrystallization grains nucleated at 4-, 3- and 2-grain junctions in turn.•Two proposed recrystallization nucleation mechanisms operate well at grain junctions.•The ...nucleation priority of one grain junction can be predicted by Taylor factors.
Despite the important role of grain junctions to the dynamic recrystallization (DRX) of nickel-based superalloys, the nucleation mechanisms operating there and the influence factors besides deformation condition on nucleation priority are still unclear. The microstructure evolution considering grain junction effects has not been explored in depth yet. In this paper, DRX nucleation at the 2-, 3- and 4-grain junctions of a nickel-based superalloy was investigated. A proposed passive grain boundary bulging (PGBB) mechanism operated well at 2-grain junctions, and accounted for the continuity of necklace structure during the early stage of hot deformation. For the 3-grain junctions, a two-step strain-induced bulging of grain boundary fragments, which closely adjoined the junctions, was found to dominate the DRX nucleation. In addition, an increasing nucleation priority from 2-, 3- to 4-grain junctions was confirmed by the established thermodynamic model, while the nucleation priority differences of the same kind grain junctions were quantitatively analyzed by using the Taylor factors of their component grains. Finally, the DRX microstructure evolution of a 4-grain stacking unit during hot deformation was described. The understanding of DRX associated with 2-, 3- to 4-grain junctions made it more effective to tailor the microstructure of nickel-based superalloy forgings.
The pathogenesis of mucoinfective lung disease in cystic fibrosis (CF) patients likely involves poor mucus clearance. A recent model of mucus clearance predicts that mucus flow depends on the ...relative mucin concentration of the mucus layer compared with that of the periciliary layer; however, mucin concentrations have been difficult to measure in CF secretions. Here, we have shown that the concentration of mucin in CF sputum is low when measured by immunologically based techniques, and mass spectrometric analyses of CF mucins revealed mucin cleavage at antibody recognition sites. Using physical size exclusion chromatography/differential refractometry (SEC/dRI) techniques, we determined that mucin concentrations in CF secretions were higher than those in normal secretions. Measurements of partial osmotic pressures revealed that the partial osmotic pressure of CF sputum and the retained mucus in excised CF lungs were substantially greater than the partial osmotic pressure of normal secretions. Our data reveal that mucin concentration cannot be accurately measured immunologically in proteolytically active CF secretions; mucins are hyperconcentrated in CF secretions; and CF secretion osmotic pressures predict mucus layer-dependent osmotic compression of the periciliary liquid layer in CF lungs. Consequently, mucin hypersecretion likely produces mucus stasis, which contributes to key infectious and inflammatory components of CF lung disease.
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