Evacuation Time Research Articles

Exploring the Application Potential and Performance of SiO2 Aerogel Mortar in Various Tunnel High-Temperature Environments

SiO2 aerogel is a super-insulating material that can be used for tunnel fireproofing to eliminate high-temperature spalling and extend the safe evacuation time of personnel. This study aimed to replace traditional aggregates with SiO2 aerogel in mortar preparation and evaluate its mechanical properties, thermal conductivity, and durability (freeze–thaw, water, and moisture resistance). Furthermore, the high-temperature characteristics of SiO2 aerogel and the damage evolution pattern of SiO2 aerogel mortar were investigated with varying fire durations (0.5, 1, 1.5, 2, 2.5, and 3 h) and fire temperatures (1000, 1100, and 1200 °C) as environmental variables. The results revealed that the critical temperature and critical time of SiO2 aerogel particles from amorphous to crystalline structures were about 1100 °C and 1.5 h, respectively. SiO2 aerogel mortar exhibited a compressive strength of 3.5 MPa, a bond strength of 0.36 MPa, and a thermal conductivity of 0.165 W/m·K. The residual mass ratio and residual compressive strength of SiO2 aerogel mortar were 81% and 1.8 MPa after 1100 °C for 2.5 h. The incorporation of SiO2 aerogel significantly improved the fire resistance of the mortar. Therefore, SiO2 aerogel mortar has the potential to be used as a fireproof coating and can be applied in tunnels to reduce high-temperature spalling and extend the safe evacuation time for personnel.

Effect of transient inhalation on powder evacuation and dispersion in a typical dual air inlet dry powder inhaler

An optically accessible research dry powder inhaler (DPI) was used to investigate the impact of initial acceleration during inhalation on the powder evacuation and drug dispersion processes. The inhaler featured a swirling chamber connected with two inlets, closely resembling commercial devices such as the Aerolizer® and Osmohaler®. The dimensions of the inhaler were kept similar to the commercial devices, mimicking their flow situations. High-speed microscopic imaging and an in-house developed image processing technique were used to extract relevant statistics. The current literature on DPI flow dynamics provides valuable insights into the correlation between inspiratory flow rate, peak inspiratory pressure, and inhaler performance. However, it lacks data correlating powder evacuation characteristics and deagglomeration mechanisms for transient inhalation conditions inside the DPIs. This paper is an attempt to fill this gap by investigating the evacuation pattern and deagglomeration mechanism for three different initial accelerations qualitatively representing asthma severity and steady-state inhalation conditions representing laminar, transitional, and turbulent channel flow, using both pure drug and carrier particles. The study's key findings revealed that powder evacuation progressed in two stages. The first stage was slow, with a slope ranging from 0.25 to 0.27. Also, the evacuation rate was independent of the initial inhalation acceleration. The second stage was rapid, with a slope ranging from 0.87 to 1.23, which led to faster and complete powder evacuation. The slow stage consumed approximately ∼60 % of the total evacuation time to evacuate only ∼20% of the loaded drug, while the rapid stage evacuated ∼80% of the powder in the remaining time. The data collected from these experiments advances the understanding of the DPI flow dynamics and provides high-quality data for validating computational models used in the analysis of such inhaler systems.

Numerical analysis and validation on the phased evacuation time in high-rise buildings

The main aim of this study is to investigate the numerical analysis of phased evacuation and validate the feasibility of high-rise buildings using the control volume model. Based on the same spatial configuration, the number of participants on each floor, and four-phased evacuations of an actual fire drill conducted by a Japanese academic group in 2018, the numerical analysis results for these phased evacuations of this high-rise building have been investigated. The numerical results are in good agreement with the fire drill data in the aspects of the total number of people reaching the ground floor, the space-time feature curve and the first participant on each floor descending to the ground floor. The changes in the number of waiting participants versus time on each floor were obtained and compared in this study with the fire drill data to comprehend the transient situations of the internal participants in this high-rise building during the phased evacuation. Furthermore, the results of the first-order approximation method of NFPA, the Melinek and Booth method and the Route B calculation of the Japanese Building Center Verification Method for the total building evacuation are presented to discuss the differences between the phased evacuation and the total building evacuation.

Design for Storm Surge Flooding Adaptation: Facilitating Emergency Evacuation with Adaptive Landscape Form-Based Codes

Lack of consensus and funding led to a focus on building retrofits after storm surge flooding and collective inaction for undertaking cross-jurisdictional adaptation pathways planning. Using Seabrook, TX, United States, as a test case, this paper demonstrates the feasibility of using design games (participatory community visioning and design processes) to develop consensus-based, performance-driven, form-based codes from an adaptive landscape framework to facilitate emergency evacuation during storm surge flooding. The framework provides bottom-up mechanisms to enhance the sizes, coverages, quantities, and connectivity of multi-scalar engineered structural and nature-based solutions as a complex adaptive system to increase evacuation time and decrease flood-prone population.

Crowd model calibration at strategic, tactical, and operational levels: Full-spectrum sensitivity analyses show bottleneck parameters are most critical, followed by exit-choice-changing parameters

ABSTRACT Crowd motion simulation requires specification of a range of parameters, each reflecting certain aspects of agent behavior. But what parameters matter the most? Are they all equally important? The question is important given that available data and resources for parameter calibration are limited, and priorities often need to be made. Here, for the first time, a full-spectrum sensitivity analysis of crowd model parameters is reported. It is shown that estimates of simulated evacuation time are, by far, most dependent on the value of locomotion/operational parameters, especially those that determine discharge rate at bottlenecks. The next most critical set of parameters are those that influence change of direction choices. If a crowd simulation model fails to reproduce bottleneck flows accurately, efforts to refine other modeling layers will be in vain. Similarly, if the model fails to represent exit choice adaptation/changing accurately, efforts to refine the exit choice model will be fruitless.

A fine discrete floor field cellular automaton model with natural step length for pedestrian dynamics

This paper proposes an extended floor field cellular automaton (FFCA) model for evacuation simulations, which integrates the natural step length into pedestrian movement. The model enables pedestrians to occupy multiple grids and extends the interaction area to a disk with a radius determined by the natural step length. These modifications facilitate pedestrian movement in various directions, limited only by the chosen numerical resolution. The model is calibrated to reproduce known density-velocity relations by simulating different evacuation scenarios. The flow rate through the bottleneck scenario matches the experimental results very well. Interestingly, the evacuation time, crowd shape near the exit and average conflict frequency are found to be independent of the discretisation degree, which is different from previous work. Compared with the traditional FFCA model, the proposed model yields larger and more reasonable velocity variation and evacuation path. The main parameters have a similar influence on the evacuation time, indicating that the proposed model retains the robustness of the traditional FFCA model.

Real-time evacuation route optimization in the fire scenarios of cruise ships

The optimization of evacuation routes for evacuees in fire scenarios on cruise ships directly affects evacuation efficiency. A time-varying equivalent weight Dijkstra algorithm (TVEWDA) is proposed, combining a fire dynamics simulator (FDS) to find optimal evacuation routes in case of a sudden cruise ship fire. First, the FDS software is used to simulate a cruise ship's single and multi-source fire scenarios. Second, the Dijkstra algorithm using only distance between nodes is improved by considering the effects of CO concentration, visibility, and temperature. The evacuees’ speed is taken into consideration within the TVEWDA. The effects of congestion are considered in the evacuees’ moving speed. Finally, the TVEWDA and a cruise ship evacuation network model are integrated to develop a real-time evacuation route optimization model. Simulation results show that the evacuation time achieved by the TVEWDA is 22% shorter than that of the Dijkstra algorithm using only distance between nodes and 11% shorter than that of an improved social force model in the multi-source fire scenario. This approach is well-suited to guide the evacuation of cruise ship evacuees in the event of single-source or multi-source fires, effectively ensuring the safety of passengers and the preservation of their property.

Tsunami Evacuation Accessibiliyu Simulation Using Network Analysis Tools In Tsunami Prone Areas Of Tanggamus District

Geological activity in the Sunda Strait received attention through the tsunami that occurred at the end of 2018 and the tectonic earthquake in the Sunda Strait subduction zone with Magnitude 6.9 on August 2, 2019. These conditions raise concerns about the threat of earthquake and tsunami disasters in the surrounding area. Tanggamus Regency, which is located within a fairly close radius to the Sunda Strait, has a very wide tsunami-prone lowland, especially in the area around the tip of Teluk Semangka. Based on these conditions, this research generally aims to map evacuation service areas, map evacuation times, and analyze effective evacuation models. To answer these challenges, this research was conducted following several methodological stages. It started with defining the study area using spatial analysis, digitizing the road network and interlinking it with the Network Analysys tool on the ArcGIS platform. Based on the observation, it was found that the most at-risk areas are those that have the farthest distance from the Temporary Evacuation Site (TES) location when traveled without a vehicle. Each region has a TES location that can be reached using the available roadways. There are 3 sub-districts that have a travel time of more than 30 minutes to reach the TES, namely, Semaka sub-district, Wonosobo sub-district and Kota Agung Barat sub-district. It is expected that the results of this study can be one of the considerations in tsunami disaster mitigation efforts in Tanggamus Regency.

Battery thermal safety management with form-stable and flame-retardant phase change materials

Phase change materials (PCMs), characterized by zero energy consumption and high energy storage density capability, have a wide range of applications. However, the development of organic PCM is restricted by their low thermal conductivity, easy leakage and high combustibility. In this study, we produced a composite phase change materials (CPCM) with both high thermal conductivity and flame-retardant effect for application in battery thermal safety management. We demonstrated that addition of a porous network structure of EG as a shaping support to increase PA's thermal conductivity, and incorporation of environmentally safe and non-toxic silica-based flame retardant (SiO2 sol) improved the flame retardant properties. The optimum mass ratio of the CPCM was obtained by comprehensive analysis of the shape and thermal stability, energy storage performance and thermal conductivity. It was also verified by cone calorimetry that the CPCM outperformed pure PA in several aspects: heat release, smoke release rate and emission of toxic gases. The cooling and thermal runaway experiment of the battery module showed that the addition of CPCM had a positive effect on absorption of battery heat and extending the time between the thermal runaway spread of battery modules (21 s increasing to 396 s), providing valuable time for the safe evacuation of people in the event of a runaway fire.

Simulation Study on Fire Product Movement Law and Evacuation in a University High-Rise Teaching Building

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.

Society of Family Planning Clinical Recommendation: Management of hemorrhage at the time of abortion

Hemorrhage after abortion is rare, occurring in fewer than 1% of abortions, but associated morbidity may be significant. Although medication abortion is associated with more bleeding than procedural abortion, overall bleeding for the two methods is minimal and not clinically different. Hemorrhage can be caused by atony, coagulopathy, and abnormal placentation, as well as by such procedure complications as perforation, cervical laceration, and retained tissue. Evidence for practices around postabortion hemorrhage is extremely limited. The Society of Family Planning recommends preoperative identification of individuals at high risk of hemorrhage as well as development of an organized approach to treatment. Specifically, individuals with a uterine scar and complete placenta previa seeking abortion at gestations after the first trimester should be evaluated for placenta accreta spectrum. For those at high risk of hemorrhage, referral to a higher-acuity center should be considered. We propose an algorithm for treating postabortion hemorrhage as follows: (1) assessment and examination, (2) uterine massage and medical therapy, (3) resuscitative measures with laboratory evaluation and possible reaspiration or balloon tamponade, and (4) interventions such as embolization and surgery. Evidence supports the use of oxytocin as prophylaxis for bleeding with dilation and evacuation; methylergonovine prophylaxis, however, is associated with more bleeding at the time of dilation and evacuation. Future research is needed on tranexamic acid as prophylaxis and treatment and misoprostol as prophylaxis. Structural inequities contribute to bleeding risk. Acknowledging how our policies hinder or remedy health inequities is essential when developing new guidelines and approaches to clinical services.

Aeromedical Evacuation, the Expeditionary Medicine Learning Curve, andthe Peacetime Effect.

Organizational proficiency increases with experience, which is known as a learning curve. A theoretical peacetime effect occurs when knowledge and skills degrade during peacetime. In this study, the intertheater evacuation system was examined for evidence of a military learning curve and peacetime effect. Data on medical evacuations from U.S. Central Command occurring between January 1, 2003, and December 31, 2022, were acquired from the TRANSCOM Regulating and Command & Control Evacuation System. Priority mission evacuation time corresponding to peak periods of activity in Iraq and Afghanistan and minimal activity in Afghanistan was analyzed. Any reduction or increase in the delivery time of casualties would be considered a change in proficiency. There was a marginal monthly decline of 0.019 days (27.4 min) to perform a priority evacuation from Iraq (95% confidence interval [CI], 0.009 to 0.028 days, P < .001) and a decline of 0.010 days (14.4 min) from Afghanistan (95% CI, 0.003 to 0.016 days, P = .004) over 40 months from peak monthly average times. There was a monthly marginal increase in priority evacuation average time from Afghanistan of 0.008 days (11.5 min) (95% CI, 0.005 to 0.011, P < .001) between January 2013 and December 2020. The number of monthly evacuations estimated to maintain or improve monthly average evacuation time is approximately 50. An intertheater aeromedical evacuation system increased in proficiency during periods of conflict and declined during relative peacetime. There is evidence of a peacetime effect on intertheater aeromedical evacuation.

Revolutionizing indoor emergency evacuation prediction with machine learning: A Hand‐searching technique and content analysis on Random Forest algorithm

AbstractMachine learning and emergency evacuation prediction share a meaningful association in the context of the Industrial Revolution 4.0 era, given that machine learning can potentially enhance emergency evacuation prediction processes. Machine learning has the potential to revolutionise emergency evacuation prediction by providing a data‐driven approach that aids decision‐making and response time in emergencies. The complexity of emergency situations can lead to tragic accidents, as individual behaviour heavily influences evacuation time. While some researchers have explored emergency evacuation, existing computer evacuation models lack detailed analysis. To address this gap, this study focuses on reviewing the Random Forest algorithm, an advanced machine learning algorithm based on Decision Trees, in the application of forecasting emergency evacuation time. Through a qualitative research approach using the innovative Hand‐searching technique, we conducted a systematic review employing Content Analysis Theory. Multiple sources were examined, including Google Scholar, Science Direct, Scopus, and Universiti Kebangsaan Malaysia e‐Journal System. The study's findings shed light on the performance, prediction factors, advantages, and limitations of Random Forest in identifying impacts during an emergency evacuation. These insights hold significant implications for emergency responders, building designers, and policymakers.

Simulation analysis of evacuation processes in a subway station based on multi-disaster coupling scenarios

ObjectiveThis study aimed to improve knowledge on ways to effectively solve problems associated with subway station emergencies and provide methodological guidance for safety management. Process and methodA real case was considered—the Nanning Chaoyang Square subway station—and the AnyLogic simulation modeling software was used to build a simulation model of the evacuation process in the station in different disaster and disaster coupling scenarios. In particular, the characteristics of various disaster scenarios and the coupling effect between multiple disasters were analyzed, the social force model was improved during the analysis of pedestrian movement, and the key factors affecting the evacuation process in fire outbreak, flooding, and fire and flood coupling scenarios were analyzed. The number of evacuated pedestrians and evacuation times in each scenario were compared for analysis, to propose targeted suggestions. ResultsThe impact of fire products on pedestrians increased rapidly during the fire growth stage. When a fire or flood occurred on Side A of the station hall floor, the impact on the evacuation capacity was the greatest. The results support the claim that different multi-disaster coupling scenarios have different effects on evacuation risk owing to the influence of pedestrian evacuation strategies.

Evacuation dynamics of heterogeneous crowds involving individuals with different types of disabilities

In this paper, the movement experiment of mixed disabled group including visual disabilities, hearing disabilities, physical disabilities, mental disabilities, intellectual disabilities and people without disabilities is conducted to analyze the movement characteristics in the corridor. The results show that mental and intellectual disabilities have a higher global velocity than the rest of the crowds. The density range of the mixed disabled group (0.48–2.25 m−2) is narrower than that of the elderly group (0.27–2.64 m−2) in the analysis of fundamental diagram. In the same density range, the differences in velocity and specific flow between two groups are 0.00 ± 0.09 m/s and 0.04 ± 0.11 (m∙s)-1, respectively; the specific flow of the mixed disabled group is increases by (3.84 ± 10.67) % compared to the elderly group. Further analysis shows that evacuation time of the mixed disabled group is inversely proportional to the exit width, the same relationship as for the elderly group, with the curve below that of the elderly group; the flow of the mixed disabled group is greater than that of the elderly group. The spatial distribution of nearest neighbor for the mixed disabled group presents an elliptical shape; with increasing density, the shape of the spatial distribution tends to be circular. For wheelchair users and other crowds, the area of the nearest neighbor spatial distribution decreases as the exit width decreases. However, the area of wheelchair users is larger than that of other crowds. The findings of this study are hoped to be a guide for pedestrian safety management and engineering egress design.

Simulation of a multi-floor evacuation with the extended social force model in a multi-corridor environment

Abstract For the stagnation problem that easily occurs in the process of simulating multi-floor and multi-staircase evacuation using a traditional social force model, in this paper, it is proposed to improve the social force model by introducing a moth-flame optimization algorithm, thus to establish a new evacuation model. The model firstly integrates the field model into a social force model as the pedestrian self-driving direction. Meanwhile, an objective optimization function of minimum system evacuation time is established based on the evaluation indexes, such as staircase congestion degree and average velocity, and the moth-flame optimization algorithm is improved by introducing dynamic inertia weight and random reverse learning strategy, thus establishing an evacuation optimization method. Finally, a simulation and numerical analysis is carried out for the multi-floor evacuation process using the experimental simulation platform built, which deeply analyzes the key factors influencing the model, gives the change relationships among the parameters such as evacuation time, initial pedestrian velocity, the number of pedestrians and staircase width, and verifies the effectiveness of the model.

Evacuation effect analysis of guidance strategies on subway station based on modified cellular automata model

With the extension of the subway network and the increase in passenger flow, higher traffic pressure and risk level have occurred. Adopting appropriate guidance strategies is a critical factor in improving the evacuation effect and reducing casualties in subway stations. Automatic fare gate (AFG) groups are the key facilities in evacuation guidance, as their limited traffic capacity can easily cause congestion. This study proposes a modified cellular automata model that combines the multi-phase goals of passengers in the evacuation process to characterize the behavior of three guidance strategies: (A) Balancing passengers’ AFG group selection; (B) Balancing passengers’ AFG selection; (C) Setting dedicated AFGs for slower passengers. The pedestrian parameters obtained by field observation are used as inputs for the proposed evacuation model. The total evacuation time and the average waiting time for different types of passengers and key facilities are calculated. The impact of different guidance strategies on evacuation performance is explored in various scenarios. The results show that a combination of A and B strategies would achieve the shortest total evacuation time. While a combination of A, B, and C strategies would achieve the shortest average waiting time. The improvement of evacuation efficiency brought by guidance is proved significant even when only part of the people executes the arrangement.

ASSESSMENT OF THE FIRE RESISTANCE OF BUILDINGS FROM FIREPROOF REINFORCED CONCRETE BUILDING STRUCTURES

The authors conducted an analysis of the current state of evacuation of low-mobility population groups from high-rise residential buildings in the event of a fire. The analysis of the literature made it possible to formulate a number of obstacles to the effective evacuation of people from high-rise residential buildings. Norms in the field of fire safety are not perfect and, as a rule, are aimed at ordinary categories of citizens. The goal of approaches to evacuation calculations is to reduce the time it takes to evacuate residents of a high-rise building in the event of a fire. The authors substantiated the possibility of safe self-evacuation in the event of a fire of the less mobile population groups using fire elevators. Mathematical and graphical calculations of people's evacuation time were carried out using the Pathfinder software complex with the use (without use) of fire elevators. The authors performed a mathematical calculation of the time of evacuation of people and the time of blocking by dangerous factors of fire evacuation routes during a fire in accordance with the methodology of DSTU 8828:2019 Fire safety. Terms. Kyiv: Technical Committee "Fire Safety and Fire Fighting Equipment". To confirm the effectiveness of using fire elevators for the evacuation of people belonging to the M4 population groups with limited mobility (disabled people who move around in wheelchairs), the calculation part was performed. The object of the calculations is a high-rise apartment building on the street. Baidy Vyshnevetskoho, 68 in Cherkasy. The authors determined the dependence of the evacuation time on the movement parameters of people of different mobility groups. The authors compared calculations of evacuation time by stairwell and using fire elevators. Fire elevators are effective when evacuating people from floors for the category of mobility group M4. The researchers proposed management solutions to increase the level of fire safety, ensure the constant readiness and operability of fire elevators for evacuating people with reduced mobility from high-rise residential buildings. Keywords: evacuation routes, evacuation exits, high-rise residential buildings, fire elevators, evacuation time.

Investigation and simulation of non-adaptive psychology of crowd evacuation under toxic gas leakage accident in chemical park

Chemical parks promote economic development, but accidents have caused casualties. Non-adaptive crowd psychology during evacuations can lead to panic, which can result in irrational behavior. Exploring ways to control panic and improve evacuation efficiency is crucial. In this paper, we conduct a questionnaire survey to grasp the psychological rules of evacuating people in the context of toxic gas leakage accidents in chemical parks, and define the weight of panic influence factor accordingly. Combined with a specific chemical park scenario, ALOHA software was used to simulate and analyze the consequences of toxic gas (liquid ammonia as an example) leakage, and the evacuation available time was obtained as 720s. The simulation experiments of personnel evacuation in the accident context were conducted by using Anylogic software based on the social force model, and the required evacuation time was 663.9s, 706.3s, 725.4s and 744.5s respectively under different panic influence factors. Drawing on the idea of building fire performance assessment, the safety criteria for evacuation under toxic gas leakage considering evacuation panic is proposed, namely RSET < ASET, to determine the safety status of personnel evacuation under different panic impact factors, which is hoped to provide some effective guidance for emergency evacuation in chemical parks.

Evacuating Pets and People: Time, Decisions, and Resources

Abstract Increasingly, research focuses on challenges associated with people threatened by disasters but who refuse evacuation without their pets. Less attention is paid to decision making processes and costs of evacuating or sheltering-in-place with pets. Pet owners consider whether or not to evacuate, but—importantly—they also consider the financial costs of staying at pet-friendly shelters, securing necessary supplies for safe pet evacuation, and the impact of pet preparation on evacuation timing (temporal costs). Decision making is compounded by the risks they face, the preparations necessary, and their perceived impact on their animals. Those without pets in their household can be impacted by those with pets, as people often make evacuation decisions in groups. We detail the influence these factors have on evacuation decision making and close with a discussion of the implications for disaster planning.