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The process of pressurized injection of ultra-fine powder extinguishing agents (UPEA) and the effect of injection from the nozzle directly affects the spatial dispersion characteristics and the effectiveness of fire extinguishing. Combining CFD simulations and experimental measurements, the UPEA pressurized injection process and injection effects were investigated. The transient process of injection is divided into three stages, initial injection stage, steady injection stage, and post-injection stage. The post-injection stage is divided into a slow decay process and a residual gas release process. Investigating the effect of different filling conditions on the effectiveness of particle injection. In the stable injection stage, the higher the filling ratio, the lower the mass flow of UPEA particles at the same filling pressure. At the same filling ratio, the higher the filling pressure, the higher the mass flow of UPEA particles. The maximum mass flow of the UPEA particles was 5.38 kg/s at a filling ratio of 20% and a filling pressure of 3.6 MPa. The steady injection time is mainly influenced by the particle filling ratio.

Heavy gas dispersion is significantly impacted by meteorological conditions. In this study, the widely-used heavy gas dispersion model SLAB is revised by using alternative parametrizations for the meteorological parameters, mixing layer height, and wind speed profile. The Nozaki method and the stability modified logarithmic wind profile evolved from the Monin-Obukhov similarity theory are adopted to calculate the mixing layer height and wind speed profile in the improved SLAB-M model, respectively. Dense gas dispersion model evaluation protocols are used to evaluate SLAB-M, and the datasets from the Jack Rabbit II (JR II) 2015 Trials are used to compare the accuracy of the simulations to observed data. The statistical performance measures (SPMs) of SLAB-M are overall a little better than that of SLAB, and SLAB-M effectively simulates heavy gas dispersion under the different meteorological conditions of the JR II 2015 Trials. Thus, it can better satisfy the requirements of consequence assessment and emergency response for the leakage and dispersion of hazardous gasses.

In order to understand the distribution characteristics of biomarkers in source rocks, which may be related to organic input, Quaternary sediments from the Caohai Basin and the Chaiwobu Lake were analyzed for sterols. As a result, various sterols have been found in the sediments. The composition of sterols in the sediments revealed that cholesterols and cholestadienols are more abundant than their C29 counterparts in the Chaiwobu Lake sediments and that C29 sterols are more abundant in the peats from the Caohai Basin. It is also found that stanol/sterol ratios in clays are higher than in peats. Studies show that organic input to the Chaiwobu Lake is mainly plankton and zooplankton and to the Caohai Basin is mainly terrestrial high plant. The authors have proposed that the relative abundance of C27 or C29 sterane in source rocks may reflect input characteristics to some extent and the stanol/sterol ratios may reflect the redox conditions of the depositional environments.