Underground coal gasification (UCG) is essentially the multi-field coupled thermochemical conversion process. One of the most significant characteristics during the UCG process is the formation of the pronounced oxygen concentration gradient along the gasification channel, which leads to significant zoning characteristics in the underground reaction zone. In this work, the coal reaction behavior driven by oxygen concentration gradient from 0% to 100% (10 levels) is focused. Meanwhile, the numerical model combining reaction kinetics and empirical component distribution is used to compare the gas production performance under different oxygen concentrations. Under the low oxygen concentrations (<21% O-2), the maximum generation rate and content of CO are relatively high, reaching 0.23 mol/(kg & centerdot;K) and 0.75, respectively. In contrast, under the high oxygen concentration (21% similar to 100% O-2), the maximum generation contents of CO2, CH4, and H-2 are higher. As the oxygen concentration increases from 0% to 100%, the apparent activation energy of coal firstly increases from 31.56 to 90.69 kJ/mol, and then decreases exponentially to 20.62 kJ/mol. Meanwhile, compared to the oxygen-lean conditions, the enthalpy change, entropy change, and Gibbs free energy change are lower under the oxygen-enriched conditions. The critical oxygen concentration for the kinetic-thermodynamic parameters of coal is 8%. The gradient distribution of oxygen along the gasification channel is the core driver behind the zonal evolution in UCG. Therefore, in the actual UCG application, the precise regulation of oxygen concentration is essential to optimize syngas composition, improve gasification reaction intensity, and achieve stable evolution of the reaction three zones.
Living in a changing climate, human society now faces more frequent and severe natural disasters than before. As a consequence, rapid disaster response during the “Golden 72 Hours” of search and rescue becomes a vital humanitarian necessity and community concern. However, traditional disaster damage analysis routinely fails to generalize across distinct urban morphologies and new disaster events. Effective damage mapping typically requires exhaustive and time-consuming manual data annotation. To address this issue, we introduce Smart Transfer, a novel Geospatial Artificial Intelligence (GeoAI) framework, leveraging state-of-the-art vision Foundation Models (FMs) for rapid building damage mapping with post-earthquake Very High Resolution (VHR) imagery. Specifically, we design two novel model transfer strategies: first, Pixel-wise Clustering (PC), ensuring robust prototype-level global feature alignment; second, a Distance-Penalized Triplet (DPT), integrating patch-level spatial autocorrelation patterns by assigning stronger penalties to semantically inconsistent yet spatially adjacent patches. Extensive experiments and ablations on the recent 2023 Türkiye-Syria earthquake show promising performance in multiple cross-region transfer settings, namely Leave One Domain Out (LODO) and Specific Source Domain Combination (SSDC), achieving an average F1-score of 0.64 and mIoU of 0.69. Moreover, Smart Transfer provides a scalable, automated GeoAI solution to accelerate building damage mapping and support rapid disaster response, offering new opportunities to enhance disaster resilience in climate-vulnerable regions and communities. The data and code are publicly available at https://github.com/ai4city-hkust/SmartTransfer.
This study proposes an innovative ultrasonic-assisted oily bubble flotation strategy to enhance carbon recovery from coal gasification fine slag (CGFS). Experimental results demonstrate that under 1200 W ultrasonic pretreatment for 15 min, oily bubble flotation significantly outperforms traditional air bubble flotation, achieving a maximum combustible recovery (CR) of 81.83 % and a concentrate yield of 63.73 % (compared to a 30.33 % CR and 21.22 % yield for air bubbles). SEM and EDS analyses reveal that high-intensity ultrasound effectively strips spherical inorganic minerals from the carbon skeleton. This allows the oily bubble concentrate to achieve an exceptional carbon purity of 92 % and a minimal oxygen content of 7.01 %, up from 67.24 % carbon in the raw CGFS. XPS results confirm that the 1200 W oily bubble process maximizes hydrophobic C-C bonds to 71.20 % while suppressing hydrophilic COOH groups to 9.06 %. Furthermore, ultrasonic cavitation helps clear blocked pores, increasing the most probable pore size from 2.06 mu m to 2.30 mu m, while the carbon skeleton remains structurally intact (evidenced by a stable fractal dimension of 2.79). This physical and chemical cleaning step restores the natural hydrophobicity of the carbon surface, allowing the oily bubbles to create a strong hydrophobic bridge that makes the process highly efficient for decarbonizing CGFS. Ultimately, this combined strategy provides a practical and efficient technical route for the resource utilization of solid waste in the coal chemical industry.
The mining of lead-zinc ore encounters significant spatial variations in rock mechanical properties due to the complex lithological assemblage, as well as technical challenges such as explosibility and difficulties in mineral processing. These factors result in insufficient adaptability of existing mining equipment and constrained economic benefits. The use of mechanical rock-breaking equipment to assist the operation of roadheaders can effectively reduce the risk of structural failure, eliminate the hazards of gas explosions, and significantly decrease pick wear while improving mineral processing efficiency. Therefore, this study introduces the drilling-splitting-cutting process in lead-zinc mining engineering, with a focus on optimizing the drill hole layout for typical lead-zinc ore rock masses. The results indicate that during the splitting process, employing a rectangular slotting scheme that increases the depth of the free surface while decreasing the depth of the splitting hole can significantly improve the fragmentation effect. For multi-hole sequential fracturing, a longitudinally aligned arrangement should be used. The maximum effective fracturing distance is exponentially negatively correlated with the tensile strength of the rock mass, while the depth of the splitting holes is negatively correlated with the fractured zone area. Field comparative test results show that the drilling-splitting-cutting process improves excavation efficiency by 84 % compared to single-roadheader excavation and by 9 % compared to drilling-cutting processes. Additionally, it reduces pick consumption by 40 % and 28 %, significantly enhancing construction economics.
The rapid expansion of global PV trade is accompanied by a notable "energy leakage" effect, where energy-intensive production processes are relocated via international trade to regions with lower energy efficiency, thereby undermining the overall emission reduction potential of the PV industry. This study integrates life-cycle data of PV products from 139 countries and constructs a multi-regional model based on 2021 actual trade flows, uncovering the embodied energy transfer characteristics across the entire supply chain from silicon feedstock, wafers to modules. The results reveal a profound fossil energy dependence (91.3-92.69%) throughout the supply chain. While current trade patterns enhance local energy efficiency through specialization, regional electricity mix disparities and cross-border transportation result in a net increase of 347.6 billion MJ energy input in the global supply chain, creating a vicious cycle of "scale expansion-energy leakage escalation". Policy interventions show divergent effects: carbon tariffs and geopolitical conflicts reduce energy leakage through regionalized production reshoring at the cost of $2.3 billion trade losses, whereas technological breakthroughs achieve a win-win of "scale expansion and energy consumption reduction" (cutting 12.8 billion MJ fossil energy input). The study proposes a clean transition pathway leveraging process-specific differentiation and regional synergy to resolve the energy-environment paradox in PV trade.
