High-rise teaching buildings are complex public buildings that combine the evacuation risks of school buildings and high-rise buildings. In this regard, studying fire product transport patterns and personnel evacuation characteristics of high-rise school buildings is crucial for safe and rapid evacuation. In this paper, we applied Pyrosim2018 software to build a model of a teaching building and performed numerical fire simulation to analyze temperature, CO gas, and visibility to determine the available evacuation time ASET; meanwhile, we performed evacuation simulation by Pathfinder 2019 to determine the required evacuation time and analyze the congestion problem during evacuation. By improving the evacuation route, secondary simulations were conducted and compared with the previous results. The results show that visibility is the main factor affecting evacuation in of the event of a fire in this school building. Based on the visibility analysis, it is recommended that personnel evacuate from floors four and above within 709.2 S when the fire location is at a specific position on the third floor. While the original safety exits of the school building can avoid a large number of casualties, they cannot guarantee the safe evacuation of all people, and planning a reasonable evacuation route can obviously relieve the evacuation pressure in the high-rise corridor.

The circular-hole rotating core fog nozzle has excellent atomization performance and has been widely used in the realm of spray dust. As part of this study, a mathematical model was developed for predicting the Sauter mean diameter (SMD) of nozzles of this type. The coaction between the SMD of the nozzle and the three influencing factors of axial distance, water supply pressure, and outlet diameter was investigated based on the customized spray’s experimental platform and orthogonal design method. According to the comparative analysis of the size range, the axial distance, outlet diameter and water supply pressure are three parameters that affect the SMD of the nozzle, and the degree of influence is axial distance > outlet diameter > water supply pressure. On this basis, a mathematical model was developed using the multiple regression method to predict the SMD of the nozzle. We analyzed the results and compared them to the SMD value predicted by the multiple regression mathematical model and the orthogonal experiment results. The change trend was the same, the values were essentially the same, and the average relative error was just 16.11%. Accordingly, the mathematical model presented in this paper may be used for the prediction and calculation of the droplet size for circular-hole rotating core micro-fog nozzles.

The fractal dimension is widely used in many fields as a parameter to characterize the geometric complexity and geometric distribution relationship of research objects. To study the surface characteristics of sulfide ore particles, the fractal theory was applied to quantitatively characterize the surface fractal dimension Ds of sulfide ore microparticles in three particle size ranges, 60–100 mesh, 100–140 mesh and >200 mesh, based on the area–perimeter method. Using an optical microscope, grain projection images of the particles were obtained. The grain shape and characteristics of sulfide ore particles were studied by means of an image processing system. The results demonstrate that the grain shape of sulfide ore particles can be expressed by fractal dimension, and the particle surface fractal dimension ranges from 2.4392 to 2.5492. It was found that the fractal properties begin to decrease due to the increasing of the particle size. The larger the fractal dimension, the finer the particles are. The fractal dimension of sulfide ore particles can be used as an important indicator of their particle shape distribution characteristics, which can provide important information for further study of the relevant physical and chemical properties of sulfide ore particles and provide a new theoretical method and basis for the adhesion and removal of sulfide ore dust. With the quantitative description of the fractal distribution of sulfide ore particles, a new way to study the adhesive force between particles is offered for further research.