15,528 research outputs found

    A note on multi-dimensional Camassa-Holm type systems on the torus

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    We present a 2n2n-component nonlinear evolutionary PDE which includes the nn-dimensional versions of the Camassa-Holm and the Hunter-Saxton systems as well as their partially averaged variations. Our goal is to apply Arnold's [V.I. Arnold, Sur la g\'eom\'etrie diff\'erentielle des groupes de Lie de dimension infinie et ses applications \`a l'hydrodynamique des fluides parfaits. Ann. Inst. Fourier (Grenoble) 16 (1966) 319-361], [D.G. Ebin and J.E. Marsden, Groups of diffeomorphisms and the motion of an incompressible fluid. Ann. of Math. 92(2) (1970) 102-163] geometric formalism to this general equation in order to obtain results on well-posedness, conservation laws or stability of its solutions. Following the line of arguments of the paper [M. Kohlmann, The two-dimensional periodic bb-equation on the diffeomorphism group of the torus. J. Phys. A.: Math. Theor. 44 (2011) 465205 (17 pp.)] we present geometric aspects of a two-dimensional periodic μ\mu-bb-equation on the diffeomorphism group of the torus in this context.Comment: 14 page

    Chemically Oscillating Reactions during the Diagenetic Formation of Ediacaran Siliceous and Carbonate Botryoids

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    Chemically oscillating reactions are abiotic reactions that produce characteristic, periodic patterns during the oxidation of carboxylic acids. They have been proposed to occur during the early diagenesis of sediments that contain organic matter and to partly explain the patterns of some enigmatic spheroids in malachite, phosphorite, jasper chert, and stromatolitic chert from the rock record. In this work, circularly concentric self-similar patterns are shown to form in new chemically oscillating reaction experiments with variable mixtures of carboxylic acids and colloidal silica. This is carried out to best simulate in vitro the diagenetic formation of botryoidal quartz and carbonate in two Ediacaran-age geological formations deposited after the Marinoan–Nantuo snowball Earth event in South China. Experiments performed with alkaline colloidal silica (pH of 12) show that this compound directly participates in pattern formation, whereas those with humic acid particles did not. These experiments are particularly noteworthy since they show that pattern formation is not inhibited by strong pH gradients, since the classical Belousov–Zhabotinsky reaction occurs in solu-tion with a pH around 2. Our documentation of hundreds of classical Belousov–Zhabotinsky experiments yields a number of self-similar patterns akin to those in concretionary structures after the Marinoan–Nantuo snowball Earth event. Morphological, compositional, and size dimensional com-parisons are thus established between patterns from these experiments and in botryoidal quartz and carbonate from the Doushantuo and Denying formations. Selected specimens exhibit circularly concentric layers and disseminations of organic matter in quartz and carbonate, which also occurs in association with sub-micron-size pyrite and sub-millimetre iron oxides within these patterns. X-ray absorption near edge structure (XANES) analyses of organic matter extracted from dolomite concretions in slightly younger, early Cambrian Niutitang Formation reveal the presence of carboxylic and N-bearing molecular functional groups. Such mineral assemblages, patterns, and compositions collectively suggest that diagenetic redox reactions take place during the abiotic decay of biomass, and that they involve Fe, sulphate, and organic matter, similarly to the pattern-forming experiments. It is concluded that chemically oscillating reactions are at least partly responsible for the formation of diagenetic siliceous spheroids and concretionary carbonate, which can relate to various other persistent problems in Earth and planetary sciences

    Environmentally persistent free radicals mediated removal of Cr(VI) from highly saline water by corn straw biochars

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    Heavy metal ions coexisting with salts in the contaminant water are difficult to remove due to the interference of salts. Herein, biochars were pyrolyzed by corn straw at different temperatures, aiming to remove Cr(VI) in the presence of salts. Results show that biochars had surprisingly selective adsorption of Cr(VI). X-ray photoelectron and X-ray absorption near edge spectra revealed that Cr(VI) was reduced to Cr(III). All the adsorption was conducted at pH~7, which differed from the previous studies that Cr(VI) could only be reduced at pH 2~4. Environmental persistent free radicals (EPFRs) on biochars were found to play the role in reducing Cr(VI) in neutral solutions, which was confirmed by electron spin resonance and free radical quenching. The biochar with EPFRs reveals a highly selective removal of Cr(VI), which has implications for the remediation of contaminated water. This work provides a new insight into biochar’s properties and potential environmental applications

    On Cooperative Fault Management in Multi-Domain Optical Networks Using Hybrid Learning

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    This paper presents a hybrid learning approach for cooperative fault management in multi-domain optical networks (MD-ONs). The proposed approach relies on a broker-based MD-ON architecture for coordination of inter-domain service provisioning. We first propose a self-supervised learning design for soft failure detection. The self-supervised learning design makes use of a clustering algorithm for extracting normal and abnormal patterns from optical performance monitoring data and a supervised learning-based classifier trained with the learned patterns for online detection. To facilitate high soft failure detection accuracy in the absence of sufficient abnormal data for training, the proposed design estimates model uncertainties during predictions and identifies instances associated with high uncertainties as also soft failures. Then, we extend the self-supervised learning design and present a federated learning framework for the broker plane and DMs to learn cooperatively while complying with the privacy constraints of each domain. Finally, a data-driven soft failure localization scheme that operates by analyzing the patterns of data is proposed as a complement to the existing approaches. Performance evaluations indicate that the self-supervised learning design can achieve soft failure detection accuracy of up to ∼ 97% with 0.01%-0.04% false alarm rate, while federated learning enables DMs to realize >90% soft failure detection rates in the cases of highly unbalanced data distribution (two of the three domains possess zero abnormal data for training)

    Defining and Testing a Safety Cognition Framework Incorporating Safety Hazard Perception

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    This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers. This material may be found at https://ascelibrary.org/doi/10.1061/%28ASCE%29CO.1943-7862.0001718 There has been insufficient research focusing on checking the reliability of construction employees’ hazard perceptions by comparing them with empirical safety data. There have also been limited studies focusing on how site employees’ perceptions could be affected by multiple external and internal factors such as workers’ experience levels

    Controllable preparation of an eggshell membrane supported hydrogel electrolyte with thickness-dependent electrochemical performance

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    The preparation of thin gel electrolyte membranes with controllable thickness is important to explore the thickness-dependent electrochemical behaviors; this can further guide the fabrication of energy devices. Here we employ an in situ polymerization method to prepare a BSA–PDMAA–SiO2 cross-linked nanocomposite hydrogel on surfaces of eggshell membranes, which can be used as integrated separator and electrolyte in a supercapacitor after absorbing the electrolyte. The novel controlled thickness of the coated hydrogel therefore offers superior space utilization essential for all-solid-state devices. The composite gel can reach a high ionic conductivity of 8.8 mS cm−1 and a resulting Csp value of 161 F g−1 at the current density of 1 A g−1 when assembled in the supercapacitor, while the eggshell membrane based device has limited values of 2.7 mS cm−1 and 88 F g−1. A new insight into hybrid material preparation from low-cost natural life waste is presented in this work to obtain high performance gel electrolytes in energy devices

    Knowledge-based recommendation with hierarchical collaborative embedding

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    © 2018, Springer International Publishing AG, part of Springer Nature. Data sparsity is a common issue in recommendation systems, particularly collaborative filtering. In real recommendation scenarios, user preferences are often quantitatively sparse because of the application nature. To address the issue, we proposed a knowledge graph-based semantic information enhancement mechanism to enrich the user preferences. Specifically, the proposed Hierarchical Collaborative Embedding (HCE) model leverages both network structure and text info embedded in knowledge bases to supplement traditional collaborative filtering. The HCE model jointly learns the latent representations from user preferences, linkages between items and knowledge base, as well as the semantic representations from knowledge base. Experiment results on GitHub dataset demonstrated that semantic information from knowledge base has been properly captured, resulting improved recommendation performance

    Complete genome sequence of the African strain AXO1947 of Xanthomonas oryzae pv. oryzae

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    Citation: Huguet-Tapia, J. C., Peng, Z., Yang, B., Yin, Z., Liu, S., & White, F. F. (2016). Complete genome sequence of the African strain AXO1947 of Xanthomonas oryzae pv. oryzae. Genome Announcements, 4(1). doi:10.1128/genomeA.01730-15Citation: Tapia, J., . . . & White, F. (2013). Complete Genome Sequence of the African Strain AXO1947 of Xanthomonas oryzae pv. oryzae. Genome Announcements, 4(1). https://doi.org/10.1128/genomeA.01730-15Xanthomonas oryzae pv. oryzae is the etiological agent of bacterial rice blight. Three distinct clades of X. oryzae pv. oryzae are known. We present the complete annotated genome of the African clade strain AXO194 using long-read single-molecule PacBio sequencing technology. The genome comprises a single chromosome of 4,674,975 bp and encodes for nine transcriptional activator-like (TAL) effectors. The approach and data presented in this announcement provide information for complex bacterial genome organization and the discovery of new virulence effectors, and they facilitate target characterization of TAL effectors. © 2016 Huguet-Tapia et al

    Study on interface reaction characteristics between different acidity and alkalinity slag

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    In this paper, the interface reaction between different acidity and alkalinity of slag was explored by comparing the changing of wetting angle and viscosity in the interface between the binary slags. And the results indicated that, the reaction temperature range of Al2O3 and basic slag was relatively larger when the reaction interface was acid slag, and the fusion temperature would change when the content of calcium and magnesium were changed in the base slag. Al2O3, SiO2 are prone to react with other components and formed the new silicate phase compared to CaO, MgO, what made interfacial diffusion relatively better
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