The characteristics of copper wires are widely used in fire accident investigations. This article adopts two working conditions, GSL-1100X tube furnace radiation heating and n-hexane open flame heating, to heat the copper wire to a temperature of 100~1 000 ℃, and reduce it to room temperature through furnace cooling, natural cooling, and water cooling. Using MATLAB software, based on foreground assisted K-means algorithm to cluster and identify the L*a*b* color of wires in photos, quantitatively analyzed the relationship between the surface color of copper wires and heating and cooling conditions. The results show that the surface color of copper wires changes from dark gold to black, then to red, and finally to dark gray with increasing temperature; The overall color change of the open flame heating condition lags behind that of the radiation heating condition; In the open flame heating condition, the color of water cooling tends to be bluer and has a smaller change compared to natural cooling. Based on the above analysis, a fire scene accident investigation approach based on the surface color of copper wires is proposed, providing reference for rapid fire investigation.

In this paper, the inhibitory effect of silica composite ammonium polyphosphate additives on the propagation of premixed explosions is investigated by experimental methods. The hydrogen blending ratio for premixed gas fuels is 20%. The concentration of the compound inhibitor is 0.5 g/L, with 3 kinds of mass ratios. The experimental results show that the composite additive has a significant inhibitory effect on the propagation of hydrogen-methane explosions and it can limit the expansion of the explosion flame in the early stage. The additive absorbs heat and decomposes during the middle and late stages of the explosion development, reducing the amount of heat released from the explosion flame, as well as impeding the transfer of heat between the flame and the fuel, and disrupting the chain reaction process of the original explosion system by the decomposition products. The flame speed under the influence of composite explosion suppressant decreased by a maximum of 91%, greatly attenuating the accumulation and release of pressure. The explosion development process is effectively limited.

The purpose of this study was to obtain a new type of powder explosion suppressant, and a new type of composite porous powder explosion suppressant was prepared by a series of modification processes. The explosion suppression effect of methane before and after powder modification was discussed by carrying out methane inhibition experiments in a self-built small-sized pipeline. The explosion suppression effect was analyzed by the maximum explosion overpressure, flame propagation rate and flame propagation pattern. The experimental results show that the explosion suppression performance of modified waste incineration fly ash (MFA) is improved compared with that of unmodified waste incineration fly ash (FA), and the maximum explosion pressure of 9.5% methane is reduced by 30.55% and the peak velocity of 9.5% methane is reduced by 40.24% by 0.12 g/L MFA. At the same time, it was found that MFA had higher mass loss and lower pyrolysis temperature compared with FA, and had both physical and chemical inhibition effects.

Fire tests on EVs were carried out to measure the heat release rate and total heat release of the EV fires to provide technical support for comprehensive understanding of the fire hazards of electric vehicles, the rational determination of fire fighting and rescuing strategies and prevention and protection measures for electric vehicles and car parks. The influence of different factors on the heat release rate of electric vehicle fires is also presented in this paper. The research results show that the fire growth rate induced by over-charging batteries to ignite the EVs is significantly larger than other ignition methods like over-heating batteries and external fire sources. The development of the heat release rate curve of inducing a NCM lithium battery by over-heating to ignite the vehicle is similar to that of inducing a lithium iron phosphate battery by over-charging to ignite the vehicle. When an external fire source of about 300 kW was used underneath the carriage to ignite the EV, the fire growth rate was approximately equivalent to that of a medium-speed fire. When an external fire source of about 30 kW was used underneath the carriage to ignite the EV or a fire source of 5 kW was used to ignite the interior of the EV carriage, the fire growth rates were approximately equivalent to that of a slow-speed fire. For the electric vehicles of the same model, the maximum heat release rate caused by thermal runaway of the lithium battery was higher than that caused by an external fire source. However, the total heat released during the tests were identically the same despite the different ignition method.

This article conducted pottery jar fire tests at different liquid level heights, elucidating the evolution of flame morphology from the initial blue bimodal shape to a yellow conical flame, and distinguishing its combustion stages based on the rate of mass loss. The leakage combustion phenomenon observed during the stable combustion stage of the pottery jar fire was found, and the typical location where the external flame appeared was at the maximum belly width. The fracture time of ceramic jars with different liquid levels was calculated, revealing the development pattern of cracks on the jar wall. Cracks first appeared at the jar mouth and then flowed down along the jar wall. The research results indicate that as the liquid level increases, the probability of cracks appearing on the ceramic jar wall decreases. Among them, when cracks appear on the wall of the ceramic jar at a liquid level of 26, 27 cm, the tensile stress at the mouth of the jar is 8~17 MPa; When cracks appear on the walls of ceramic jars with liquid levels of 28, 29, 30 cm, the tensile stress at the mouth of the jar reaches over 30 MPa; The large pottery jar test broke for the first time at a temperature difference of 18.8 ℃ at the mouth, with a tensile stress of 5.1 MPa.

To investigate the risk of exposure to toxic and harmful gases during the profession of fire scene investigators, this paper designs an experimental method based on mass spectrometry detection technology. By collecting environmental gases at fire scenes, we identify the components of toxic and harmful gases, and by then collecting the exhaled breath of fire investigators, we determine the main components of human exhaled breath. Finally, by analyzing the changes in the exhaled air of fire scene investigators, further conclusions can be drawn. The results show that environmental gases at fire scenes contain various volatile organic compounds that are harmful to human health. Human exhaled breath does not contain exogenous compounds from the fire scenes. However, the analysis of exhaled breath before and after entering the fire scene reveals significant differences in the protective effects of different protective equipment against toxic and harmful gases. Improper selection can lead to the inhalation of a substantial amount of toxic and harmful gases, posing a threat to human health. Although human metabolism can expel exogenous toxic and harmful substances, personal protection is still necessary. Therefore, it is recommended that fire investigators reasonably select and wear respiratory protective equipment during their profession to prevent the hazards of toxic and harmful gases in their work and ensure personal health.

A large number of pipelines pass through walls and floors in high-rise buildings, and fire sealing at the penetrating parts is an important mean to block the spread of fire and ensure the safety of buildings and people. The current standards specify the performance requirements for fire sealing structures, but due to the unclear heat conduction and temperature distribution patterns of fire sealing structures and penetrations, the effectiveness of sealing schemes is difficult to ensure. In response to this issue, this article designed fire-resistant sealing specimens to conduct fire resistance tests, analyzed the test phenomena and temperature changes of fire-resistant sealing specimens during the fire process, compared the temperature differences of fire-resistant sealing structures and penetrations during the fire process, and proposed suggestions for the design of fire-resistant sealing structures and the revision of relevant standards.

This paper takes a teaching building of a university as the research object, on the basis of on-site observation data, uses PyroSim and Pathfinder software to carry out numerical simulation of fire, to study the influence of the change rule of smoke visibility and ambient temperature at the exit of the teaching building on the evacuation of the personnel, and to make a safety judgement according to the evacuation result, and based on the principle of system dynamics, puts forward a reasonable SD safety countermeasure model. The research results show that optimizing the necessary safety exits can effectively improve the evacuation efficiency, and the total evacuation time is shortened by 132.5 s; Adding the necessary automatic sprinkler system and mechanical smoke exhaust system, 300 s after the fire occurs, the exit temperature is reduced, and the smoke visibility is increased by about 20 m, which can greatly improve the escape safety of the exit.

Aiming at the problem that it is difficult to evacuate from large public buildings when a fire occurs, a fire evacuation path planning method based on improved Harris Hawks optimization algorithm was proposed. Firstly, the digital map required for path planning was modeled by the grid method, and the objective function of path planning evaluation was constructed with the shortest path as the goal. Secondly, Latin hypercube sampling, lens inverse learning strategy and adaptive weighting factor were introduced to improve the traditional Harris Hawks optimization algorithm, and B-spline curve smoothing method was used to smooth the planning path. Finally, it was compared with the other three algorithms in the case of no fire and fire to verify the excellent performance of the proposed algorithm. The experimental results show that in the case of no fire, the average path length of the proposed algorithm is 21.82 m, and the planning time is 20.4 s, which are reduced by 5.9% and 6.8% respectively compared with those before improvement. In the case of fire, the average path length is 22.45 m, and the planning time is 21.5 s, which is 39.0% and 48.8% lower than that before the improvement. Compared with other comparison algorithms, the proposed algorithm has good advantages in path search speed, average length and stability, and can obtain the comprehensive optimal path planning performance.

In order to study the smoke control effect of point smoke exhaust system in the asymmetric V-shaped tunnel, the scale model experiments were carried out. Taking the design fire of 20 MW as an example, based on the study of the reasonable smoke exhaust volume rate in normal tunnel, the influences of different slope combinations and different opening modes of smoke exhaust vent on the smoke control effect were studied for the V-shaped tunnel when the fire source was located at the slope changing point. The results show that smoke exhaust of 140 m3/s can effectively control the smoke for the design fire of 20 MW. For the V-shaped tunnel, when 3 smoke vents are opened symmetrically on both sides of the fire source, the smoke diffusion on the side with a large slope cannot be effectively controlled. In this case, the number of smoke exhaust vents on the side with a large slope can be appropriately increased. When the slope difference between the two sides of V-shaped asymmetrical tunnel is too large, especially when the slope of the large slope side is too large, it is difficult to control the smoke effectively.

In urban subway systems, the convergence of multiple pedestrian flows can lead to evacuation difficulties during emergencies. This study constructs a subway multi-stream pedestrian evacuation model based on the hydraulic model and System Dynamics (SD) theory. By combining specific case studies, it reveals the evacuation patterns at exit bottlenecks where multiple pedestrian flows converge under extreme unfavorable conditions, considering the evacuation of commercial area personnel through the station concourse. The findings reveal that: When multiple pedestrian flows converge at exit bottlenecks, evacuation efficiency demonstrates a "fast-slow-fast" trend; As occupant numbers increase, the utilization efficiency duration of emergency exits decreases from 74.02% to 64.78%, indicating reduced effective utilization time with higher crowd density; The specific flow rate at concourse exits experiences transient reduction when influenced by converging pedestrian streams from specific zones, whereas it remains stable otherwise; Compared with Pathfinder simulations, the System Dynamics model demonstrates closer alignment with actual evacuation scenarios and superior computational efficiency.

The study focuses on developing a novel foam jetting device through adjustments to its convergence angle and inlet/inlet length disparity. This enhancement resulted in an increased effective shooting distance of foam at 46.7 m. Furthermore, the paper presents a simulation model that examines the flow dynamics within the two-phase foam stream and investigates the relationship between geometric features, gas volume fraction at the outlet (indicative of foam generation efficacy), and the range of jetting. The experimental results confirm an accuracy rate of 93.27% in device performance verification, contributing to advancements in foam extinguishing agent foaming efficiency and the development of high-performance foam guns and fire suppression systems.

To optimize the energy consumption and battery life of fire alarms using narrowband cellular IoT, we conducted an experimental analysis of the communication energy consumption characteristics of these devices. By establishing a test environment for evaluating the wireless communication reliability and low-power consumption patterns of fire alarms, we analyzed the coupling characteristics of typical operational states, communication, and power consumption of narrowband cellular IoT based fire alarms under different signal conditions. This analysis aimed to identify the operational states and common causes of power loss that critically affect energy consumption. The results showed that the heartbeat connection is the most critical factor affecting the energy consumption of narrowband cellular IoT based fire alarms. Additionally, as network signal quality deteriorates, the communication energy consumption of fire alarms significantly worsens, with peak current increases up to 350% and usage duration reduced to as low as 20.8% of the ideal state. Therefore, it is crucial to enhance the link attenuation resistance of narrowband IoT fire alarms during wireless networking, prevent excessively low signal quality, reasonably limit the frequency of heartbeat connections, and consider battery selection under poor signal coverage conditions.

This article takes the body insulation structure of a fire reconnaissance robot as the research object, establishes a multi-layer composite insulation structure model using phase change capsules, and uses COMSOL software to simulate and analyze the temperature field changes of the structure in high temperature environments. At the same time, it explores the influence of different phase change capsule stacking methods and insulation materials on the thermal protection performance of the structure. By analyzing the safety temperature characteristics of the electronic components carried in the robot, the MOGA algorithm is used to optimize the thickness of the insulation structure under the optimal combination obtained. The results indicate that under a certain thickness of the structure, the double-layer stacking of paraffin capsules has the best thermal protection effect for the anti insulation structure. At the same time, the structure of SiC aerogel as the thermal insulation material has better thermal protection performance than other thermal insulation materials. In addition, while meeting the thermal protection requirements of firefighting robots, the optimized insulation layer thickness of the body has been reduced by 1.86 mm, and the total thickness of the structure has been reduced by 25.41%, effectively improving the thermal protection efficiency of the structure.

As a kind of rescue and disaster relief mobile robot, the traditional firefighting mobile robot can replace the firefighters to go deep into dangerous areas and complete the tasks such as detection and investigation, fire fighting and rescue. However, the traditional firefighting mobile robot has limitations in terms of environmental perception and response speed. By considering the advantages of high altitude reconnaissance and detection of the quadrotor unmanned aerial vehicle(UAV), the air-ground collaborative intelligent firefighting system is designed. The quadrotor UAV detects the fire in real time at high-altitude according to the cruise track and shares the location information to the firefighting mobile robot in time through the wireless local area network(ROS networking). After receiving the response, the firefighting mobile robot goes quickly to the fire site to perform the fire extinguishing operations. The experimental results show that, compared with the traditional firefighting mobile robot, the new air-ground collaborative intelligent firefighting system proposed in this paper has the advantages of quickly detecting fire source, timely reaching and accurate firefighting. It can improve the fire rescue ability and efficiency of firefighting after fire accidents.

Through mechanics, high-temperature thermal insulation test and finite element simulation analysis, we compared the change rule of tear strength of aramid base fabrics with four different fabric organizations before and after composite with silicone rubber foam layer, and explored the thermal insulation performance and heat conduction mechanism of aramid plain fabrics composite with different thicknesses of silicone rubber foam. The results showed that the introduction of silicone rubber foam increased the overall tear strength of plain fabrics and significantly improved the thermal insulation properties of the fabrics, effectively slowing down the heat shrinkage phenomenon. After comprehensive evaluation, it can be seen that the 5 mm thickness silicone rubber foam composite aramid plain fabric performs the best in balancing the relationship between heat insulation and heat dissipation, with a back temperature reduction in the contact heat environment and the convective heat environment. In addition, the finite element simulation analysis method was adopted in this study. The simulation results show a good degree of agreement with the experimental data, with an error within 10%, verifying the reliability of the model. This research can provide basic technical support for the research and development of high-performance composite fabrics and the optimized design of personal protective equipment.

To explore the endothermic and cooling efficiencies of different gaseous fire extinguishing agents during the release process, a 1 m×1 m×1 m fire extinguishing test platform was set up to conduct gaseous fire extinguishing agent spraying tests. The endothermic capacities of typical gaseous fire extinguishing agents (Halon 1301, HFC-227ea, perfluorohexanone and 2-BTP) on the gas storage cylinders, nozzles and protected objects throughout the release process were analyzed, as well as the impact of the initial temperature of the protected objects on the cooling efficiencies of the new clean gaseous fire extinguishing agents (perfluorohexanone and 2-BTP). Test results shows that Halon 1301 and HFC-227ea vaporized during the transmission process, therefore poor cooling performance was observed. Whereas for 2-BTP and perfluorohexanone, no phase change in the pipeline results in quick vaporization and heat absorption when the agent droplets reaching the surface of the target. Hence, the two agents exhibit high cooling effectiveness than others. Overall, the cooling efficiency ranking for the four agents is 2-BTP＞perfluorohexanone＞HFC-227ea＞Halon 1301. Compared with perfluorohexanone, 2-BTP not only allowed the largest temperature reduction on the target but also led to a slow temperature recovery after the agent was discharged. This is because 2-BTP absorbs the largest amount of heat when using the same amount of agents. Therefore, the choice of fire suppression agents and corresponding system design is critical to improve cooling efficiency and fire suppression performance.

In order to develop highly efficient halogen-free flame retardants of epoxy resins (EP), a novel flame retardant DOPPO, which contains two phosphorus oxidation states and hydroxyl groups, was synthesized from p-Hydroxybenzaldehyde, phosphorus oxychloride, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The influence of DOPPO on the thermal, flame-retardant, and fire-resistant performance of EP composites was studied. Tests showed that the flame retardance and fire resistance of EP composites are influenced by the molecular structure of organic phosphorus-containing flame retardant. Compared with DOPh and TPP, DOPPO shows obvious synergistic flame retardant effect, and the most efficient flame retardance and fire resistance in EP. In detail, when the phosphorus content in EP is low at only 0.42%, the EP/DOPPO acquired the UL 94 V-0 rating and obtained a higher LOI value of 34.6%, the formation of more compact expanded char residues can inhibit the release of heat and toxic smoke. TG-IR analysis shows the generation of phosphorus containing volatiles, which may provide DOPPO with gas phase flame retardant function for EP. The better flame-retardant performance of DOPPO is ascribed to the quenching effect of the phosphaphenanthrene group in the gas phase and the charring effect of phosphate ester group and phosphaphenanthrene group with hydroxyl group in the condensed phase. And, the results from the large-plate combustion test reveals that DOPPO was superior to DOPh and TPP in terms of expansion ratio as well as fire-resistant performance of the fireproof coatings.

In order to reduce the damage to the ecological environment and property losses caused by the frequent occurrence of forest fires, a forest fire positioning system based on the wireless sensor network is designed. The system is composed of fire collection nodes, gateway nodes, and fire monitoring nodes. The fire collection nodes use a variety of sensors to collect the fire parameters within the monitoring area, utilize the improved DV-Hop positioning algorithm to locate the fire, and transmit the positioning data to the gateway nodes. Then, the data is sent to the 4G network via the gateway nodes and finally transmitted to the remote fire monitoring center for fire monitoring, fire warning, and historical data query. Experiments have proven that the system can quickly and accurately locate the fire within the monitoring area and issue an alarm in a timely manner, thus preventing the occurrence of forest fires.

Wildfires are a great threat to the safe operation of transmission lines, especially small-scale wildfires. Once they occur, they may lead to transmission line tripping and affect the normal supply of power. In order to effectively monitor and deal with this hidden danger, based on the Himawari-8 geostationary meteorological satellite, this paper proposes an algorithm to optimize the monitoring effect of small-scale mountain fires. The algorithm not only uses the spatial context technology to identify high-intensity fire points, but also carries out accurate dynamic monitoring of small-scale wildfires by deeply exploiting the advantages of high time resolution of geostationary meteorological satellites and combining with the timing change characteristics of fire points. The practical application proves that the algorithm has significant advantages in monitoring small-scale wildfires, and can effectively realize the early detection of fire points and real-time tracking of fire changes.

In order to accelerate the development of new-quality fire-fighting combat capabilities and give full play to the key role of data in emergency rescue command and dispatch, as well as in combat operations, this paper analyzes the deficiencies of traditional data, studies the characteristics of data elements, and brings into play the multiplier effect of data elements. It explores new combat mechanisms, optimizes the combat command process, and leads the transformation of decision-making methods. Through the practical application of data fusion technology, it promotes cross-departmental and cross-field data sharing and collaboration, provides solid data support for the construction of a comprehensive and intelligent emergency rescue command and combat system, and achieves the goals of accurate prediction and early warning, correct analysis and decision-making, and efficient command and combat.

In order to strengthen the implementation of the main responsibility of enterprise fire safety, better optimize the business environment, do a good job of pre-fire prevention supervision, work research, data analysis, literature search and other methods are used to analyze and study the problems that the current fire safety self-management ability of enterprises, the level of industry supervision and the supervision measures of fire rescue organizations are not suitable for the current fire safety situation. The paper points out that the enterprise must improve the fire safety management system, strengthen the fire training and education, and improve the level of fire safety management, the competent departments of the industry and the fire rescue agencies will further promote the implementation of the main responsibilities of enterprises for fire safety from the aspects of enhancing their supervisory capacity, improving supervisory methods, and clarifying the boundaries of fire safety responsibilities for fire and residential building departments, tighten the chain of fire safety responsibility, prevent major fire safety risks, and reduce fire accidents in an all-round way.