In recent years, vulnerable populations have become the main targets of casualties in many building fire accidents. It is of great significance to study the behavioral patterns of vulnerable populations during emergency evacuation and to design specialized strategies conducive to the evacuation of vulnerable populations to improve evacuation efficiency and reduce casualties. In this paper, simulations are carried out using AnyLogic based on a social force model to explore the impact of dedicated exits in public places on the evacuation of vulnerable populations. A model of a normal room with three exits was created in which pedestrians were divided into two categories: normal and vulnerable populations with different evacuation speeds and footprint sizes. Simulation results show that dedicating middle exits reduces evacuation time in most cases while dedicating side exits significantly increases evacuation time. Middle exits as dedicated exits can balance the evacuation speed of vulnerable and normal populations, and improve the overall evacuation efficiency of vulnerable populations. Calculating the balance analysis index OPS for building evacuation, the results show that the balance of exits is the key to the evacuation time, and the closer the OPS value is to 0 the better the evacuation balance, which leads to a shorter evacuation time. This paper illustrates the impact of dedicated exits on the evacuation of vulnerable populations. Also, it provides a basis for the need for dedicated exits in different situations by calculating OPS values.

Respiratory infectious diseases can cause public health emergencies, threatening human well-being, social operation, and economic development. Clarifying the transmission mechanism of respiratory infectious diseases is essential for control measures. We review the main research findings on the transmission mechanism of respiratory infectious diseases in recent decades. The source characteristics of respiratory infectious diseases, the airborne transmission mechanism, the exposure of susceptible persons, and the infection risk assessment methods are discussed. Given that the dynamic scenario of respiratory infectious disease transmission has attracted wide attention in recent years, we summarize the effects of human movement on indoor airflow, pathogen diffusion, and human exposure. Considering the everyday use of facemasks, the effects of facemasks on source characteristics and infection risk are also discussed. Finally, future research prospects are proposed. The transmission mechanism of infectious diseases can be comprehensively explored by delving into patients' pathological characteristics and personnel protection measures. This exploration can be facilitated by establishing a multi-pose manikin database, enabling personalized and refined evaluations. Interdisciplinary cooperation will play a pivotal role in fostering a holistic understanding. Furthermore, it is crucial to account for the impact of individuals' activity patterns on disease transmission dynamics. This review is expected to reference public health emergency management.

China has a population of 1.4 billion, ranking first in the world. With the increase in China's economic development and population, the construction of various types of buildings in China is also increasing, and associated safety hazards are gradually increasing. Therefore, it is necessary to study the safe evacuation of people inside and outside the building in emergency situations. In recent years, some scholars have used the traditional statistical method of literature review to analyze the research frontiers in the field of safety evacuation, but few scholars have used bibliometric methods to analyze and review the current situation of research in this field. Therefore, this paper adopts the analysis method combining bibliometrics and traditional literature review to summarize the research status of crowd evacuation published by Chinese scholars in the Web of Science core database, and uses VOSviewer to analyze the authors, institutions, and keywords of the literature search results, so as to identify their research hotspots. The results show that the last three years have been the peak period of crowd evacuation studies, with many disciplines involved in this field and they are closely related, led by the number of papers related to architecture. Simulation, model, behavior, among others, have been the most used keywords in this research field, and the research on path planning and exit selection behavior has also increased significantly. According to the keyword analysis, three hot spots of safety evacuation research, namely large-scale group evacuation, evacuation path planning and evacuation exit selection are analyzed in detail.

Building exit has always been an emphasis of research in the field of evacuation. Existing studies on crowd flow characteristics at building evacuation bottlenecks usually focus on plane exit, but insufficient attention has been paid to the characteristics of crowd flow at the convex exit. Convex exit can be considered as such a structure like a double-bottleneck linked passage. This paper aims to study the influence of geometric structure characteristics of the convex exit on crowd evacuation and put forward the optimal design strategy of this structure, so as to improve the efficiency of evacuation in an emergency. Using social force model-based software, MassMotion, it is found that convex exit is indeed more efficient and safer than common plane exit in terms of evacuation time and pedestrians' congestion, especially when the desired speed is relatively higher, indicating that convex exits are more suitable for crowd evacuation in case of emergency. Four size-related parameters of convex exit are analyzed in detail, namely the width of the bottleneck at passage (W_p), the passage width (W), the passage length (L), and the exit width (W_e), to find out the optimum design of convex exit. The research shows that the optimal size ratio is that W_p: W: L: W_e equals 1.5:1.75:3.5:1, and as the overall magnification of building size and the number of pedestrians increases, the evacuation time gradually tends to a stable value, which indicates that this optimal ratio has good adaptability in size effect. Finally, based on the in-depth mechanism of pedestrian flow at the convex exit, three possible application scenarios are proposed to illustrate the feasible optimum design of the convex exit. The results of this study can provide new ideas for research on the structure of building exits.

In dense crowd evacuation, especially in emergencies such as fires, the safe evacuation of large public facilities will face major challenges. At the same time, as cluster congestion tends to occur in the space where the flow rate drops sharply, the superposition of fire incidents and bottleneck areas can easily evolve into malignant disasters and crowd stampedes with serious harm and influence. In this paper, Massmotion based on social force model is used to carry out a numerical simulation on exit position and corner exit form to find out the mechanism and influence law of the slight architectural adjustment on the flow at bottleneck. The results show that the traditional middle exit design is not the best, and the evacuation efficiency of the corner exit is higher than that of the middle exit. Compared with other corner exits, the average time interval between two adjacent persons passing through the bottleneck under the 30° corner exit is the shortest, and the probability of outlet clogging drops the fastest, exceeding 18% of the slowest descending speed. At the 0° corner exit, the waiting time cost of pedestrians is high and the risk of evacuation is high. The outcomes of this work can provide reference for the structural design of the building and the safe evacuation of personnel, so as to improve the evacuation efficiency and safety of pedestrians in the building to some extent.