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The production practices in Shendong mining area show that the CO concentration at the return air corner of shallow coal seams often exceeds the limit, but the temperature of the residual coal in the goaf has not significantly increased, and no other indicative gas of spontaneous combustion in coal seams has been detected. In order to provide scientific basis for CO management at the return air corner of the fully mechanized mining face in Shendong mining area and the prevention and control of coal seam spontaneous combustion fires, based on the "three zones" distribution parameters of spontaneous combustion of coal in goaf and the characteristic parameters of spontaneous combustion of coal, and based on the mechanism of CO production in shallow buried mining area, the source and influencing factors of CO in working face were analyzed, and the calculation model of CO concentration at the return air corner in working face was established. The concentrations of CO at the return air corner in different working faces in Shendong mining areas were calculated by using the model. The results showed that the relative error between the observed and measured values remained between 0.32% and 6.92%. The quantitative analysis of the proportion of CO production from each source to the total production of CO in the return air corner is of great significance to the effective control of CO concentration in the air return corner of the working face. [ABSTRACT FROM AUTHOR]

Sea ice formation over open water exerts critical control on polar atmosphere‐ocean‐ice interactions, but is only crudely represented in sea ice models. In this study, a collection depth parameterization of new ice for flux polynya models is modified by including the sea ice concentration and ice growth rate as additional factors. We evaluated it in a climate model BCC‐CSM2‐MR and found that it improves simulation of Antarctic sea ice concentration and thickness in most of Indian and Atlantic sectors. Disagreement between the observed Antarctic sea ice expansion during 1981–2014 and the modeled decline still exists but is mitigated when the modified scheme is implemented. Further analysis indicates that these improvements are associated with the overcoming of premature closure of open water, which enhances the response of ocean to surface wind intensification during 1981–2014, and consequently slowdowns the sea surface temperature increase and the resulting Antarctic sea ice reduction. Plain Language Summary: Open water ice formation critically modulates sea ice variations and the associated polar atmosphere‐ocean interaction, but is not well represented in sea ice models. In this study, a modified collection depth parameterization of new ice based on an existing scheme is presented after including sea ice concentration and ice growth rate as additional factors. We evaluated this modified scheme in BCC‐CSM2‐MR and found that it can improve the simulation of mean Antarctic sea ice thickness and concentration in winter as well as Antarctic sea ice expansion from 1981 to 2014. Further analysis implies that these improvements can be attributed to the overcoming of the premature closure of open water areas in model simulations. Key Points: A modified collection thickness parameterization of new ice suitable for large‐scale climate simulations is presentedIt improves the simulation of Antarctic sea ice thickness and concentration, as well as Antarctic sea ice expansion during 1981–2014The improved simulations can be attributed to the overcoming of the premature closure of open water areas where new ice forms [ABSTRACT FROM AUTHOR]

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BCC-CSM2-HR is a high-resolution version of the Beijing Climate Center (BCC) Climate System Model. Its development is on the basis of the medium-resolution version BCC-CSM2-MR which is the baseline for BCC participation to the Coupled Model Intercomparison Project Phase 6 (CMIP6). This study documents the high-resolution model, highlights major improvements in the representation of atmospheric dynamic core and physical processes. BCC-CSM2-HR is evaluated for present-day climate simulations from 1971 to 2000, which are performed under CMIP6-prescribed historical forcing, in comparison with its previous medium-resolution version BCC-CSM2-MR. We focus on basic atmospheric mean states over the globe and variabilities in the tropics including the tropic cyclones (TCs), the El Niño–Southern Oscillation (ENSO), the Madden-Julian Oscillation (MJO), and the quasi-biennial oscillation (QBO) in the stratosphere. It is shown that BCC-CSM2-HR keeps well the global energy balance and can realistically reproduce main patterns of atmosphere temperature and wind, precipitation, land surface air temperature and sea surface temperature. It also improves in the spatial patterns of sea ice and associated seasonal variations in both hemispheres. The bias of double intertropical convergence zone (ITCZ), obvious in BCC-CSM2-MR, is almost disappeared in BCC-CSM2-HR. TC activity in the tropics is increased with resolution enhanced. The cycle of ENSO, the eastward propagative feature and convection intensity of MJO, the downward propagation of QBO in BCC-CSM2-HR are all in a better agreement with observation than their counterparts in BCC-CSM2-MR. We also note some weakness in BCC-CSM2-HR, such as the excessive cloudiness in the eastern basin of the tropical Pacific with cold Sea Surface Temperature (SST) biases and the insufficient number of tropical cyclones in the North Atlantic. [ABSTRACT FROM AUTHOR]

Catalysts readily suffer from particle attrition in fluidized beds. In this article, a commercial fluid catalytic cracking catalyst was sieved into several particle-size intervals to investigate the size effect on particle attrition. It is shown that an exponential decay equation presents a suitable description of attrition and that catalyst attrition is dependent on particle size. Steady-state specific attrition rate decreases with increasing particle size; however, initial specific attrition rate and decay time parameter change irregularly. For comparison of attrition resistances, a long attrition test is required to reach steady-state attrition, and the steady-state specific attrition rate is recommended. It is seen that the smallest particle-size interval is the most seriously attrited, while the two largest particle-size intervals are the most attrition-resistant. Furthermore, weak interactions appear among attrition behaviors of different intervals, and a linear combination method is effective to combine all interval samples to predict the attrition of the original full-sized sample. © 2016 American Institute of Chemical Engineers AIChE J, 63: 914-920, 2017 [ABSTRACT FROM AUTHOR]