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Pore structure and surface morphology are the key factors affecting coal spontaneous combustion. However, there are few studies that focus on quantitative descriptions of them. This paper presents an investigation into the evolution of the surface physical structure of different metamorphic coal during low-temperature oxidation. Specific surface area analyzer and atomic force microscopy were used to quantify the physical structure. The results indicate that the average pore size of coal decreases as the temperature increase, with low-metamorphic coal demonstrating a more pronounced reduction. Conversely, the specific surface area exhibits a gradual increase with temperature, particularly for the lignite. The evolution of surface morphology gradually changes from the fluctuation of low temperature to a flat surface with fewer high peaks. Meanwhile, the fractal dimension increasing with temperature also explain that the pore structure and surface morphology tend to become more complex during coal oxidation, especially the lignite. That is, the slopes of the fitting lines of fractal dimension vs temperature are higher for XLT coal than for YL coal and SG coal. The effect of coal surface structure on oxidizability is interpreted by the pore connectivity and oxygen adsorption on the surface during the coal oxygen compound reaction. • The fractal dimension of pore structure and surface morphology of coal was obtained. • AFM profiles with high statistical occupancy were selected for fractal calculation. • An approach to quantifying the evolution of coal oxidation was provided. [ABSTRACT FROM AUTHOR]

General anomaly detection has been an important research due to its broad and significant applications. Those algorithms that are based on weakly supervised or partially observed anomalies have attracted particular interest currently. However, most such algorithms treat the unlabeled set as a substitute for normal samples and ignore the potential anomalies in it, which on the one hand causes the noise of the normal set, and on the other hand, fails make full use of the abnormal supervision information. To address this issue, we propose a m eta- p seudo-label based framework for a nomaly d etection (MPAD). The framework strives to obtain effective pseudo anomalies from the unlabeled samples to supplement the observed anomaly set. Specifically, a teacher network is improved based on the feedback of a student network on a validation set, thereby generating more conducive pseudo anomalies to assist the student network while incurring less confirmation bias. In addition, we also design a model roll-back scheme to guarantee the performance of the student network. Extensive experiments show that the proposed MPAD algorithm outperforms current popular algorithms on five real datasets, and the framework can effectively improve the utilization of unlabeled samples while maintaining an advanced degree of robustness. In addition, the results of ablation experiments confirm the effectiveness of each module of our MPAD. Parameter experiments provide sufficient reference for parameter selecting. [ABSTRACT FROM AUTHOR]

• Methane reduced the oxidation degree, resulting in a less compact aromatic structure. • Methane inhibited the oxidation of coal, leading to a low graphitization degree. • Methane increased interlayer spacing and reduced crystallite height of crystallite. • Methane can affect the oxidation order of aliphatic side chains in crystallite. The residual coal in gobs is usually oxidized under a lean-oxygen condition due to methane emissions, thus affecting the crystalline structure of coal that is closely associated with heat transfer during low-temperature oxidation. This study set out to investigate the crystalline structure development of coal during low-temperature oxidation under this practical condition. For this purpose, non-isothermal oxidation and X-ray diffraction (XRD) experiments were employed to conduct lean-oxygen oxidation of coal and crystalline structure analysis, respectively. The results indicate that crystalline structure was closely associated with methane at different temperatures. Methane in gobs reduced the oxidation degree of coal, making the crystalline structure became less orderly; it restrained the condensation of crystalline structure, resulting in a less compact aromatic structure compared with that under aerial conditions. The condensation occurs between aromatic layers and along the plane of the aromatic layer (methane < 20.0 %), while it mainly happens between aromatic layers when methane was higher(>20.0 %). During self-heating, the rising methane increased the interlayer spacing of aromatic layers and reduces the crystallite height, the graphitization degree, and the number of effectively stacked aromatic layers. Methane's influence on crystallite diameter was found to be sensitive to oxidation temperature. Crystallite diameter consistently grew with oxidation temperature regardless of methane, but the growth rate became apparent only when the oxidation temperature exceeded 150 ℃ and methane concentration was lower than 20.0 %. The findings of this research will promote our understanding of crystalline structure development under oxygen-lean conditions caused by methane emission in gobs. [ABSTRACT FROM AUTHOR]

• Free radicals relate to both oxygen and methane in the oxidation environment. • The g-factor grows with the rising methane and the oxidation temperature. • The rising methane changed the free racial type during coal oxidation in gob. • Free radical concentration decreases with methane and increases with temperature. Methane dilutes the oxidation environment of coal in the gob, thus affecting the free radical reaction in low-temperature oxidation of coal. To investigate methane's effects in this process, three coal samples (i.e., anthracite, coking coal, gas-fat coal) were non-isothermally oxidized to different temperatures in methane-containing environments and then analyzed in an electron paramagnetic resonance (EPR) spectrometer. The experimental results demonstrate that the g-factor and free radical concentration were not only related to oxygen but also associated with methane in the oxidation environment. The g-factor grew with the rising methane and the oxidation temperature. With the rising methane, the free radicals of the anthracite changed from carbon-centred radicals to carbon-centred radicals with an adjacent oxygen atom. Besides, the free radical concentration was found to decrease with methane and increase with oxidation temperature. The rising methane restrains the increase of free racial concentration during coal spontaneous combustion. It is inferred that the influence of methane is related to the competitive adsorption of coal on different gases. The results of this study added to our understanding of the role that methane plays in the low-temperature oxidation of coal and can serve as a reference in coal spontaneous combustion prevention in working face gobs with methane emissions. [ABSTRACT FROM AUTHOR]

• A tailor-made IL ([C 2 IM][EtSO 4 ]) is first introduced to separate propylene and propane. • Structure optimization of IL is performed by formulating and solving a CAILD-based MINLP problem. • An optimized IL-based ED process is proposed for the propylene/propane separation. • The IL-based process has 68.9% energy savings and 74.7% cost reduction. • The marginal price of the IL is proposed to evaluate the economic feasibility. In the petrochemical industry, the separation of propylene/propane is usually paid much attention due to its high energy-consuming and environmental challenges. In this work, an energy-efficient extractive distillation (ED) separation process of propylene/propane is proposed by introducing a tailor-made ionic liquid (IL) solvent. The structure optimization of ILs is performed with a novel design objective in the computer-aided ionic liquid design (CAILD) method. By solving a formulated CAILD-based mixed-integer nonlinear programming (MINLP) problem, the ethylimidazolium ethyl sulfate ([C 2 IM][EtSO 4 ]) is identified as the best IL solvent. The separation performance of [C 2 IM][EtSO 4 ] in the ED process of propylene/propane is then evaluated through rigorous process simulation in Aspen Plus. For comparison, the conventional separation process of propane/propylene is also simulated and optimized. Based on the optimized operations, in-depth energy and economic assessment are conducted for an industrial-scale separation of propane/propylene in a Chinese refining industry. Remarkably, the [C 2 IM][EtSO 4 ]-based ED process has 68.9% energy savings and 74.7% cost reduction when compared to the conventional process. [ABSTRACT FROM AUTHOR]

Abstract: In this work, hierarchically porous TiO2–B nanoflowers have been successfully synthesized via a facile solvothermal method followed by calcination treatment. The TiO2–B nanoflowers are constructed by thin nanosheets, presenting ultrahigh specific surface area, up to 214.6m2 g−1. As anode materials for Li-ion batteries, the TiO2–B sample shows high reversible capacity, excellent cycling performance and superior rate capability. The specific capacity of TiO2–B could remain over 285mAhg−1 at 1C and 181mAhg−1 at 10C rate after 100 cycles. We believe that the pseudocapacitive mechanism, ultrahigh surface area and scrupulous nanoarchitecture of the TiO2–B are responsible for the enhancement of electrochemical properties. [Copyright &y& Elsevier]