Large-scale storage tanks are widely used for flammable liquid fuels, where crosswind, ullage height, and wall properties can strongly alter fuel combustion, flame–wall interaction, and the resulting thermal load on the tank wall. This study experimentally investigates the coupled effects of wind velocity, ullage height, and wall material on flame behavior, fuel burning rate, wall-temperature evolution, and heat-transfer mechanisms in n-heptane storage-tank fires. Under the combined effects of crosswind and ullage height, two characteristic internal flame regimes, namely bottom-contacting and non-bottom-contacting flames, are identified. Flame bottom-contacting occurs more readily in quartz-glass tanks than in steel tanks under otherwise identical conditions, indicating that differences in wall thermal and radiative properties significantly affect flame–wall–fuel thermal coupling. These material-dependent heat-transfer characteristics also modify the thermal feedback to the fuel and consequently influence the burning rate. Crosswind-induced flame asymmetry further produces distinct thermal responses on the windward and leeward walls. Based on the identified flame modes and regional heat-transfer mechanisms, separate governing equations are established for the two sides of the tank. A physics–machine learning hybrid framework is then developed by coupling the physical-model predictions with XGBoost-based residual correction. The hybrid model achieves coefficients of determination above 0.80, with prediction errors generally within ±20%. Additional evaluation using a larger-diameter steel tank shows that the framework can capture the overall wall-temperature variation beyond the original experimental scale, although quantitative accuracy remains affected by scale effects and flame-mode transitions. These results provide a physically interpretable framework for analyzing and predicting wall thermal loads in liquid-fuel storage-tank fires.
Abstract The mechanical properties of structural concrete are greatly influenced by both lateral confinement and elevated temperature. Nevertheless, it remains challenging to establish a constitutive formulation that can simultaneously capture thermal strain development, irreversible deformation, and stiffness deterioration in concrete subjected to multiaxial loading during fire exposure. Hence, this paper proposes a three-dimensional nonisothermal plastic damage model for concrete. Specifically, a capped yield surface that evolves with temperature is used to define the plastic behavior, and a nonassociated flow rule is adopted to govern the plastic strain increment. The evolution of plasticity and stiffness degradation is further governed by hardening and damage formulations that depend on both temperature and confinement, with regularization introduced to reduce mesh sensitivity during strain-softening. Moreover, a stress triaxiality measure is embedded in the load-induced strain formulation to capture the contribution of lateral confinement during heating. For numerical implementation, the model is implemented in Abaqus version 2021 through a UMAT subroutine, and the stress update is carried out by an explicit scheme that couples adaptive Runge-Kutta-Dormand-Prince sub-stepping with stress correction to maintain the accuracy of the updated stress state. Its predictive capability is assessed against 26 material-level tests and five concrete-filled steel composite column tests under ambient-temperature and fire conditions. The comparisons indicated that the model captures key experimental features, including confinement-induced strength enhancement, thermal deterioration, thermal strain evolution, and stiffness degradation, thereby supporting its application to nonlinear analysis of structural concrete under ambient and fire scenarios.
Ultrafine magnetite and quartz particles readily undergo heteroaggregation during pulp conditioning, resulting in gangue entrainment and poor magnetic separation selectivity. Conventional dispersants mainly improve overall suspension stability but rarely address selective regulation of interfacial interactions between different minerals. In this study, a synergistic dispersant composed of sodium hexametaphosphate (SHMP) and sodium dodecylbenzene sulfonate (SDBS) was employed to regulate magnetite-quartz heteroaggregation. Dynamic settling tests, turbidity analysis, magnetic separation experiments, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Zeta potential measurements, and Extended Derjaguin-LandauVerwey-Overbeek theory (E-DLVO) calculations were performed to elucidate the mechanism. The results show that the SHMP-SDBS system effectively suppresses heteroaggregation by selectively modifying the surface properties of both magnetite and quartz. This interfacial regulation effectively inhibited aggregate formation and improved suspension stability during the conditioning process. Under the optimized conditions, the quartz rejection efficiency reached similar to 90%, while the total iron (TFe) grade of the industrial concentrate increased from 67.71% to 71.63% with a 98.20% recovery. Mechanistic analysis indicates that SHMP preferentially chemisorbs on magnetite, whereas SDBS predominantly interacts with quartz, enhancing electrostatic and hydration repulsion between particles. The increased interaction energy barrier predicted by E-DLVO calculations prevents irreversible particle attachment. The improved separation performance originates from selective interfacial regulation of heteroaggregation rather than conventional dispersion enhancement, providing a practical strategy for upgrading ultrafine magnetite ores.
This work investigates the feasibility of using Th-based fuels containing transuranic (TRU) as alternative fuel for small modular reactors (SMRs) with Annular fuel. Monte Carlo code RMC 3.5.0 and cross-section library ENDF/B-VIII.1 were employed to establish the Chinese SMR core with annular fuel. This code was used to study the neutronic characteristics of the proposed Th-based fuel (233U, TRU, 0.94Th)O2, (233U, TRU, 0.945Th)O2 and (233U, TRU, 0.95Th)O2. Fuel burn-up parameters, including effective multiplication factor (keff), fissile nuclide mass evolution, reactor-grade plutonium (rgPu) mass, minor actinides (MA), neutron poison (135Xe and 149Sm) mass variation, were analyzed during 2000 effective full power days (EFPDs) for proposed Th-based fuel types and compared with traditional UO2 fuel. Analysis of the neutron flux distribution, effective delayed neutron fraction (βeff), fuel temperature reactivity coefficient (FTC), moderator temperature reactivity coefficient (MTC), prompt neutron lifetime (l), neutron generation time (Λ) and visualized power distribution provide valuable insights into the neutronic behavior and performance of the proposed fuel types. The neutronic analysis results confirm the viability of using the proposed Th-based fuel types as alternatives to UO2, because of their acceptable safety parameter values and favorable power distribution across the core compared to UO2.
Currently, the development of the agricultural specialty industry in Southwest China faces challenges such as insufficient brand competitiveness and lagging processing technology, which restrict industrial development performance. Taking Sichuan Province in Southwest China as an example, the research employs the Analytic Hierarchy Process (AHP) combined with the Fuzzy Comprehensive Evaluation (FCE) method to evaluate performance. The former decomposes the problem into the target layer, criterion layer, and solution layer and uses an expert-scoring method to determine the weights of each indicator. The latter uses fuzzy mathematical theory to compute comprehensive evaluation results using membership functions and weight matrices. Based on the evaluation results, the factors affecting performance improvement are analyzed in depth, and industry optimization measures are developed. The overall performance level of the agricultural specialty industry in Sichuan Province in 2023 was moderate, with a comprehensive evaluation value of 3.10. The economic performance was poor, with a comprehensive evaluation value of only 2.95. The social and ecological performance was moderate, with comprehensive evaluation values of 3.26 and 3.38, respectively. The performance evaluation method can effectively quantify the multidimensional performance of the agricultural specialty industry in Sichuan Province, providing reliable technical support for the scientific diagnosis and industrial optimization of the agricultural specialty industry in Southwest China.
