In order to alleviate the traffic congestion induced by different rainfall intensities, a dynamic control method of variable speed limit in merging zones considering rainfall intensity heterogeneity was proposed. The impacts of capacity reduction and vehicle lane-changing probability on the traffic flow state were comprehensively considered, and the dynamic relationship between rainfall intensity heterogeneity and vehicle free-flow speed was explored. Then, a traffic flow prediction model was constructed based on the cell transmission model. Taking into account the total travel time and total turnover, the variable speed limit optimization model was constructed, considering the influence of rainfall intensity heterogeneity on the variable speed limit value solution, and the optimal variable speed limit dynamic control method was obtained by using the particle swarm algorithm. Simulation and analysis of the evolution of traffic flow under different speed limit control methods were conducted. The results show that when implementing the RVSL under light, moderate, and heavy rainfall, the objective function is reduced by 8.41%, 40.57%, and 32.91% compared with variable speed limit (VSL), and by 17.48%, 55.14% and 44.69% compared with fixed speed limit (FSL). The method can effectively reduce congestion and improve the efficiency of the highway.

In order to promote the safe and eco-friendly operation of wet dust collection systems by mitigating hydrogen fire and explosion risks caused by metal waste dust in contact with water, a custom-designed metal-water hydrogen evolution testing system and a water-based Cinnamomum camphor leaf extract (prepared via decoction) were utilized. Experiments assessed the hydrogen suppression efficiency of Cinnamomum camphor leaf extract at various mass concentrations. Surface analysis and theoretical calculations were conducted to study the adsorption behavior, chemical reaction kinetics, and inhibition mechanism of Cinnamomum camphor leaf extract on hydrogen evolution from aluminum-zinc (Al-Zn) dust. The hydrogen suppression stability at the optimal mass concentration was evaluated under varying environmental conditions. Experimental results demonstrated that higher mass concentrations of extract improved its ability to suppress hydrogen evolution from Al-Zn dust. At a mass concentration of 50 mg/L, the hydrogen suppression efficiency reached 97.86%, and the reaction rate constant was nearly zero, suggesting negligible hydrogen production. Cinnamomum camphor leaf extract spontaneously adsorbs onto the Al-Zn dust surface, following the monolayer Langmuir model and involving both physical and chemical adsorption. The surface analysis reveals that Cinnamomum camphor leaf extract forms a protective film on the Al-Zn dust via complexation, effectively preventing dust-water contact and suppressing hydrogen evolution. Tests under varying external conditions demonstrated that Cinnamomum camphor leaf extract consistently suppressed hydrogen evolution from Al-Zn dust, despite variations in temperature fluctuations, pressure changes, and water disturbances in the wet dust collection system.

To enhance the scientific nature and effectiveness of online emergency language services, based on Hovland's persuasion theory, it identified the factors influencing the effectiveness of online emergency language services, clarified the input and output indicators for evaluating emergency language services, constructed an evaluation system for the effectiveness of online emergency language services during the emergency response phase, and established an evaluation process for the effectiveness of emergency language services. Taking the 6·21 Yinchuan Barbecue Shop Explosion Accident as an example, big data analysis was conducted on the information released by official media on the Weibo platform during the emergency response phase. Five types of media accounts were identified as decision-making units (DMU): emergency (including firefighting) media, public prosecution and law enforcement media, central-level mainstream media, other government media, and local-level media. The date envelopment analysis(DEA) method was employed to evaluate the effectiveness of emergency language services. The results of this study illustrated that the effectiveness of online emergency language service is from high to low for the central-level mainstream media, public prosecution and law enforcement media, emergency (include firefighting) media, other government and local-level media. There is a significant gap between other government and local-level media and the top three types of media in terms of emergency language service effectiveness. Further exploration is needed to identify ways to improve the effectiveness of emergency language services for these media types.

In order to enhance mine safety management, a ultra-large refined three-dimensional numerical model for an oversea ultra-large-scale block caving mine was established. The spatiotemporal evolution patterns of underground cave bodies and surface rock movement throughout the mining were simulated using FLAC^3D, and the safety of surface infrastructures was evaluated according to composite surface subsidence criteria. Results demonstrate that caving morphology development exhibits discontinuous, intermittent and leapfrogging characteristics. A definitive transition threshold exists in propagation modes - vertical caving dominates prior to surface breakthrough, shifting to lateral propagation afterwards. Caving crater expansion follows bimodal evolutionary patterns: initial rapid large-scale caving due to weak superficial strata, transitioning to velocity attenuation in mid-late stages through debris infill, ultimately forming cave zones with high spatial correlation to undercut areas and location. Evaluations based on composite subsidence criteria confirm that critical surface infrastructures remain outside the subsidence limit throughout the mining. Furthermore, the "priority exceedance" characteristic of curvature parameters proves effective as an early warning indicator for surface breakthrough.

To study the influence of similar scenario knowledge transfer on the subjective probability of safety accidents of engineers under avoidance behavior, the scenario similarity variable was introduced, and a subjective probability evolution model for safety accidents among engineering personnel groups was constructed and simulated. The results show that knowledge transfer in similar scenarios accelerates the convergence of the mean subjective probability, and reduces the subjective probability differences between individuals and scenarios, but also leads to the underestimation of accident rates in high-accident-rate scenarios. There is a "high-risk" accident scenario with the largest number of fatalities, where the accident rate ranges from 0.4 to 0.8. When there is a significant mortality rate difference between two scenarios, scenario knowledge transfer reduces losses only if the low-mortality-scenario has a higher accident rate than the high-mortality one. With close mortality rates but greatly varying accident rates, incomplete knowledge transfer may cause greater losses.

The goals of carbon peaking and carbon neutrality support the development of HFCV industry. Safe parking of HFCV in outdoor three-dimensional parking lot is the key to large-scale promotion. Therefore, a scaled-down physical experimental platform was built to investigate the effects of outdoor multi-story parking lot closure conditions (closed, semi-open, open), leakage location, mass flow rate nd aperture on hydrogen diffusion characteristics. The experimental results show that as the opening degree of the outdoor multi-story parking lot increases, and the related indexes of helium at the leakage source rise. For example, when the leakage occurs at the center with a large aperture at the flow rate is 0.18 kg/s, the maximum volume fractions of helium on the first, second, and third floors are 21.3%, 27% and 45.3%, respectively. The corresponding hydrogen volume fractions far exceed the lower explosive limit, posing an extremely high risk of combustion and explosion. With the increase of leakage mass flow, both the volume fraction and pressure of helium increase, and the safety risk increases. There is an obvious positive correlation between leakage mass flow rate of helium and volume fraction and pressure. Under the same degree of openness, helium tends to accumulate in corners, and its diffusion along walls is more efficient than that in open areas. The diffusion process is guided by the spatial boundary, showing a non-uniform diffusion trend. In addition, the larger the pore size, the higher the helium leakage rate.

To prevent WMSDs among the working population in member states, the European Union (EU) conducted special surveys from various perspectives and implemented ergonomic prevention measures. In accordance with the principle of random sampling, participants were selected. Surveys were conducted among occupational populations in different industries according to unified requirements and covered aspects, such as prevalence of WMSDs, causative factors, industry distribution characteristics and various targeted ergonomic prevention measures. The results showed that prevalence of WMSDs varied between 40%-79% in EU-28. Among the common physical risk factors, there were repetitive hand or arm movements, keyboard operations repetitive movements, working in tiring or painful positions, etc. There were many organizational and social psychological risk factors, such as work-related stress, the pace of work, working at high speed, etc. The ergonomics preventive measures included using equipment to help with lifting or moving, providing training on how to lift and move heavy loads, and provision of ergonomic equipment, etc. The findings show that prevalence of WMSDs is higher. There are many influencing factors. The more WMSDs ergonomics preventive measures are taken, the better the preventive effect.

In order to explore the heterogeneity sources of the influencing factors of traffic accident severity on low-grade highway and analyze the causal mechanisms of accident severity, based on traffic accident records of a low-grade highway in Chongqing city in the past 7 years, combined with the classification of collision vehicle types, the accident severity inducement analysis model was constructed using the fixed parameter Logit, mixed Logit, and random parameter Logit models considering heterogeneity sources. The differences in goodness-of-fit and heterogeneity of different models were analyzed, and the influence of significant variables on accident severity was quantified using average elasticity coefficient. The results show that the Logit model with random parameters considering heterogeneous sources has the highest goodness-of-fit under the same type of accident conditions. In the comprehensive accident model, the non-motor vehicle of the involved party has the greatest influence on the accident severity. The frontal collision is a heterogeneous variable that obeys a normal distribution of (-0.668, 0.749²). The mean and variance of the parameters are positively influenced by summer and large accident-causing vehicles. The season and involved vehicle types exhibit the largest effect intensity in the vehicle-to-vehicle accident model. The parameters associated with summer, mid-sized accident-causing vehicles, and side collisions follow a one-sided triangular distribution with mean (variance) of 0.586, 0.948, and 0.631, and have mean heterogeneity with the factors of night and horizontal curve radius greater than 1 600 m. The severity of vehicle-to-non-motor vehicle accidents is significantly affected by the variables of non-motor vehicle, night, and frontal collision. The parameters corresponding to the night and involved non-motor vehicle variables obey the unilateral triangular distribution of the mean (variance) 2.040 and 1.330, the mean value of parameters is significantly correlated with the weekend and age over 59 years old. Reasonably segmenting the accident dataset of low-grade highways in mountainous areas helps to reduce the heterogeneity effect in the factors affecting accident severity and improve the accuracy and reliability of accident severity cause analysis results.

In order to prevent the accident of people entrapped in the grain mass of warehouse and protect the life safety of workers, the discrete element engineering EDM(EDEM) method was proposed to simulate the distribution of human body pressure. Firstly, the soft sphere particle model and the basic particle contact model Hertz-Mindlin (no slip) were selected to construct the wheat, corn and rice grain particle models, and the multi-body pressure model of the human body was constructed by coupling multi-body dynamics and EDEM. Secondly, the accident area model was constructed and the simulation parameters were set considering the factors such as accident scene and calculation amount. Finally, the simulation of particle motion process and the analysis of human body surface pressure were completed, and the human body force distribution measuring device of people entrapped in the grain mass was developed. The results show that the buried time of different grains is slightly different, with wheat being less than corn and less than rice. The maximum pressure on the surface of the human body can reach 1.4×10⁶ Pa which fluctuates violently. The average maximum pressure of the weighted sum of the wheat warehouse is 9 864 Pa, that of corn warehouse is 8 255 Pa, and that of rice warehouse is 7 283 Pa. The pressure distribution data provides a reference for accident prevention and related safety training, and provides ideas for the development of protective devices.

In order to improve the issues that excessive reliance on government physical reserves can lead to high sunk costs when no emergencies occur or high emergency procurement costs due to insufficient supplies. Firstly, the option contract was introduced to construct a hybrid reserve decision-making model for emergency supplies, incorporating social donations into the decision-making framework. Secondly, the selection of optimal hybrid reserve mode and allocation of reserve amount under the option contract mechanism were studied to minimize expected costs of the government. Then, the optimal decision based on the Karush-Kuhn-Tucker (KKT) conditions and optimal strategies were proposed. The standard implicit functions were obtained for the optimal amount of government physical reserves, contracted enterprise physical reserves, and contracted enterprise production capacity reserves. Finally, taking material donations and financial donations as the key channels for emergency supply provision. A sensitivity analysis and numerical simulations of related parameters were conducted. The effects of option contract premiums, disposal costs of donated materials, and the amount of material and fund donations on optimal reserve strategies and expected costs of the government were explored. The results indicate that the government may flexibly choose whether to execute contracts for reducing expected costs and expanding reserve scale. The increase in procurement costs in the spot market for emergency supplies enhances the sensitivity of expected costs of the government to changes in demand. The government should actively guide social forces to participate in emergency rescue and flexibly adjust donation strategies according to the intensity of emergencies.