To advance environmental risk prevention and control in the Yellow River basin and achieve high-quality development，this study utilized air pollution，water pollution and carbon emissions to characterize environmental risk factors in this region. Firstly，the kernel density estimation method was employed to construct a kernel function，perform density smoothing，and analyze the spatial agglomeration patterns and evolutionary characteristics of environmental risk factors. Secondly，a spatial autoregressive model that accounts for spatial dependence was adopted to dissect the influences of multidimensional factors on environmental risk factors. The results indicate that air pollution，water pollution，and carbon emissions are primarily concentrated in the middle and downstream cities of Yellow River basin，delineating distinct regions for environmental risk prevention and control. Optimizing industrial structures and promoting green technological innovation in enterprises can reduce environmental risk factors. However，unreasonable energy conservation and environmental protection expenditures may lead to an increase in environmental risk factors. Furthermore，an inverted U-shaped relationship was observed between economic levels and population density and risk factors. From a long-term strategic perspective，regional collaborative governance and synergistic pollution reduction and carbon mitigation should be the strategic priorities. Strengthening cooperation among middle and downstream cities，optimizing industrial structures and increasing investment in industrial technological innovation are crucial steps towards achieving an economic development model transformation.

In order to address the difficulty to quantifying the emergency coordination ability of related organizations during the formation of urban flood emergency plans，a method to evaluate the robustness of inter-organizational networks for urban flood emergency response considering cascading failure was proposed. First，the inter-organizational networks for flood control emergency plans in Beijing，Shanghai and Shenzhen were established，and attack strategies and evaluation indexes of network robustness were proposed. Secondly，network characteristic statistical parameters are computed，and the network topology properties were analyzed. Then，the natural connectivity was selected as the robustness indicator to evaluate the network robustness under node single-attack strategy and continuous attack strategy. Finally，the robustness of networks under different attacks was compared，and the key organizations that have a great influence on robustness were found. The results indicate that inter-organizational networks of urban flood control emergency plans in Beijing，Shanghai，and Shenzhen have small-world and scale-free characteristics. Under single attacks of nodes，compared with the case of non-cascading failures，the robustness of inter-organizational networks is weaker considering cascading failures. Organizations with a large number of failure nodes are key to making the networks robust. Under continuous attacks，networks are strongly robust to random attacks，but weakly robust to deliberate attacks，where organizations with high degree values are key to making networks robust.

In order to improve the safety level of China Civil Aviation，a cause analysis method，which focused on the whole process of 'taxiing-takeoff-climbing-cruising-falling-approaching and landing'，was proposed based on association rules and SNA. Firstly，a total of 1 051 civil aviation accident cases from 2010 to 2022 were collected from Aviation Safety Information System. Then，a civil aviation accident causation index system based on 'human-machine-environment-management' was established in combination with 'control navigation service procedure-training'. Secondly，the EasyData data service platform was used for annotation，followed by constructing the data-set of the cause of civil aviation accidents facing the whole process of flight. Furthermore，the FP-Growth algorithm was employed to mine the association rules with the flight phase as the subsequent term of rules. Finally，this study emphasized the co-occurrence frequency of association rules，and developed the correlation network of civil aviation accident causes by applying the centrality analysis of flight phase and accident causes. The results show that the most dangerous phases of flight are the approach and landing. Operation failures，runway safe accidents and cabin safe accidents are the main types. Among the 10 identified causes of civil aviation accidents，there are 4 human factors，2 facilities and equipment factors，3 environmental factors and 1 management factor.

In order to reduce gas explosion accidents during the production，transportation and storage of combustible gases in industrial sites，square pipes of 200 mm×200 mm×35 m and round pipes of 90 mm diameter and 10 m length were independently constructed. Under the same initial conditions，the explosion test of methane/air premixed gas with volume fraction of 9.5% was carried out，and it was studied with pressure and flame sensors. The results show that the evolution process of the wave system in two kinds of pipes with different scales and cross sections is the same. After ignition，the flame changes from layer to turbulent flow，and the acceleration of flame leads to the compression wave chasing each other，finally forming a strong shock wave. The changing trend of flame speed in the two long straight pipes is the same，and they both experience the process of acceleration-deceleration-re-acceleration-re-deceleration，with the maximum flame speed in the square tube and round tube reaching 69 and 35.7 m/s respectively. After the first compression wave reflects off the wall，the pressure rises to 117% and 114%. When the reflected wave is coupled with the flame front，the flame speed in the large-scale pipeline is reduced to 73%，and that in the small pipeline is reduced to 93%. Under the same volume fraction，the maximum overpressure values of the first compression wave in the two long straight spaces are similar，which are about 65.45 and 67.09 kPa.

To draw lessons from historical chemical accidents and guide the practice of chemical safety production management，a method for identifying critical factors in chemical accidents based on text mining and improved DEMATEL method was proposed. Firstly，text mining technology was used to fully mine the text information of 1 627 chemical accident investigation reports，based on which 14 chemical accident influencing factors were extracted according to related literature，laws and regulations. Then，the fuzzy DEMATEL method based on alpha-level sets was used to calculate the performance levels of the factors affecting chemical accidents. Finally，the correlations between critical factors and other factors were analyzed and the mechanism of chemical accidents was revealed. The results show that 8 chemical accident influencing factors are identified as the critical factors，i.e.，extreme weather，regulations，technical procedures，hidden danger investigation，risk control，education and training，supervision and management，and operation management. These 8 critical factors have direct impact on the influence factors such as facilities and equipment，material reactions，occupational quality，job responsibilities，emergency management，and safety investment，which eventually lead to chemical accidents.

In order to effectively provide early warning of the occurrence trend or state of prefabricated building workers' unsafe behaviors (PBWUBs) of working at height，and to enhance the control of PBWUBs，RF-SFLA-SVM model was proposed to conduct an early warning study on workers' unsafe behaviors. Firstly，the SHEL (Software-Hardware-Environment-Liveware) model was used to analyze the factors influencing the unsafe behaviors of prefabricated building workers in danger of working at height. RF was used to determine the key warning indicators. Then SFLA was used to find the best parameters for SVM. Finally，the RF-SFLA-SVM model was used to predict and warn about the unsafe behavioral state of the prefabricated building workers working at height，and its performance was compared with other warning models. The results show that the RF-SFLA-SVM-based warning accuracy of PBWUBs of working at height was the highest，91.67%，which was a maximum improvement of 14% compared with the warning performance of other models. The research results can give a reference for the control and prevention of PBWUBs working at height.

To further improve the fire extinguishing efficiency of environmentally friendly foam extinguishing agents，surfactants of the sodium alpha-olefin sulfonate (AOS) and phosphate betaine silicone surfactant (PBSS) and foam stabilizers of inorganic salts and polysaccharides were used to propose environmentally friendly foam extinguishing agents. The effects of inorganic salt and polysaccharide mixtures on surface tension，foaming capability，and foam stability were analyzed. Then the foam stabilization mechanism of the foam stabilizer mixtures was investigated. The results indicated that the inorganic salt and polysaccharide mixtures greatly improved the physicochemical properties of the foam extinguishing agents. The foam fire extinguishing agent mixture by 0.025% xanthan gum，0.125% gelatin，and 0.1% MgCl₂ showed the best overall performance with a surface tension of 24.34 mN/m，an initial foam height of 118.81 mm，and a 25% liquid drainage time of 132.1 s. The foam stabilizing mechanism of the foam stabilizer was attributed to the formation of hydrogen bonds between xanthan gum and gelatin，which greatly enhanced the surface strength of the foam liquid film，thereby effectively slowing down the drainage rate and bubbles coarsening of foam. Moreover，the Mg²⁺ was adsorbed around the AOS/PBSS head group due to electrostatic interaction，which impaired the electrostatic repulsion between the head groups and increased the concentration of surfactant，further improving foam stability.

In order to solve the problems such as the danger，the integrity of the train structure and the safety of personnel when the high-speed train was operated in a low-vacuum tunnel，the temperature attenuation characteristics of the high-speed train compartment in a low-vacuum tunnel in a fire were explored by numerical simulation. Then the temperature distribution inside the adjacent carriages was analyzed. Finally，the distribution characteristics of the maximum temperature inside the burning carriage were studied. The results show that the temperature of the burning carriage and adjacent carriage roof decreases exponentially along the longitudinal direction. In adjacent compartments，the power has an effect on temperature attenuation. At low fire source power (0.3-0.6 MW)，the high temperature smoke spread is relatively weak，and passengers in the adjacent carriages are relatively safe. At medium source power (0.7-1.1 MW)，the high temperature smoke spreading is significant，and the temperature abrupt point appears due to the influence of carriage wall and door. At high fire source power (1.2-1.5 MW)，the heat plume intensity is higher，and high temperature smoke spread is relatively less affected by carriage wall and door，and temperature spreading trend in the connecting part of carriage is basically the same as that in the adjacent carriage. The maximum temperature in the carriage is related to power of fire source and distance from fire source to the ceiling，and there is a linear relationship.

To solve the problem of heat damage caused by the continuous extension of coal mining depth，and to reveal the distribution characteristics of the temperature field in the deep-shaft roadway，five kinds of mining thermal insulation materials were selected to carry out the study of thermal insulation and cooling in the deep-shaft roadway，to analyze the effects of different thicknesses of the thermal insulation layer and different initial temperatures of the peripheral rock on the temperature field of the peripheral rock，the radius of the heat-regulating circle，and the temperature change of the wind flow in the roadway，and to analyze the evolution characteristics of the peripheral rock temperature field in the vicinity of the thermal insulation layer. The results show that foam heat-insulating concrete has the best heat-insulating performance and the lowest economic cost. The selection of lower thermal conductivity of the insulation layer helps to improve the thermal insulation effect of the insulation layer，and 5-10 cm is the best thickness of insulation layer，temperature field is consistent with the spatial distribution of peripheral rock layer，anchor spraying layer，and insulation layer，thermal conductivity of insulation material is negatively correlated with the tunnel peripheral rock temperature gradient，thickness of insulation layer，and temperature of the original rock are positively correlated with the tunnel peripheral rock temperature gradient，and thickness and temperature of insulation layer have a significant influence on radius of heat-regulating circle. Temperature has a certain degree of influence on radius of heat-regulating circle，compared with the roadway without a heat-insulating layer，roadway heat-insulating effect of cooling effect is significant.

In order to cultivate a good safety culture in the operation stage of the nuclear power plant，the evaluation index system of safety culture in the operation stage of the nuclear power plant was constructed by analyzing the operation characteristics of the nuclear power plant and summarizing the existing evaluation index system and evaluation model，which was divided into four levels: values，behavior，system and environment，and subdivided into 13 secondary indicators and 61 tertiary indicators. On this basis，considering the non-independence and possible mutual influence between indicators，a comprehensive method based on DEMATEL and ANP was proposed to determine the weight of the index system. The results show that this method can get the evaluation index weight of nuclear safety culture by combining the survey data，and identify that the key to improving nuclear safety culture lies in the safety awareness of decision-makers and setting an example，which provides guidance for the cultivation of safety culture in the operation stage of nuclear power plants.