Fire, Volume 6, Issue 12 (December 2023) – 30 articles

The spontaneous combustion of coal caused by oxidation often leads to catastrophic fires. However, the understanding of oxidized carbon gas as a predictor of coal’s spontaneous combustion is still in its infancy. To better study the characteristics of CO₂ and CO generation during low-temperature coal oxidation, the chemical reactions and activation energies during the formation of oxidized carbon gases within coal molecules were investigated using the molecular simulation method, and the reaction characteristics at different temperatures were determined. In addition, TG was used to experimentally analyze the variations in coal weight, exothermic conditions, and gas generation patterns. The results show that the low-temperature oxidation process consists of four different phases, each of which is characterized by unique CO and CO₂ generation. The results of this study are important for the prevention and prediction of the spontaneous combustion of coal. Full article

In wildland–urban interface areas, firefighters balance wildfire suppression and structure protection. These tasks are often performed under resource limitations, especially when many structures are at risk. To address this problem, wildland firefighters employ a process called “structure triage” to prioritize structure protection based on perceived defensibility. Using a dataset containing triage assessments of thousands of structures within the Western US, we developed a machine learning model that can improve the understanding of factors contributing to assessed structure defensibility. Our random forest models utilized variables collected by wildland firefighters, including structural characteristics and the surrounding ignition zone. The models also used landscape variables not contained within the triage dataset that captured important information about accessibility, vegetation, topography, and structure density. We achieved a high overall accuracy (77.8%) in classifying structures as defensible or non-defensible. The presence of a safety zone was the most important factor in determining structure defensibility. Road proximity, vegetation composition, and topography were also found to have high importance. In addition to improving the understanding of factors considered by wildland firefighters, communities could also gain from this information by enhancing their wildfire response plans, focusing on targeted mitigation, and improving their overall preparedness. Full article

In this work, a number of experiments were conducted in a reduced scale bifurcation tunnel with a ratio of 1:10 to explore the influence of the position of longitudinal fires (placed in branch tunnel) on smoke temperature profile under forced ventilation. Three heat release rates, six ventilation velocities, and three fire locations were considered. The main findings are summarized below, as follows: The temperature of smoke downstream of the main tunnel decreases with the rate of ventilation and longitudinal fire location. In contrast, the smoke temperature downstream of the fire source inside the branch tunnel drops with the ventilation velocity; the maximum temperature of the flame under the ceiling of the tunnel rises with longitudinal fire location. The dimensionless longitudinal smoke temperatures downstream of the main tunnel decrease exponentially with longitudinal distance, and the same observation is found in the branch tunnel. The attenuation coefficient $\mathrm{k}$ in the main tunnel increases with longitudinal ventilation velocity according to a power law but does not change significantly with longitudinal fire locations. However, the exponential coefficient k′ in the branch tunnel decreases linearly with ventilation velocity, whereas it increases with longitudinal fire location inside the branch tunnel. Lastly, modified models are established for estimating the longitudinal profile of temperatures downstream of the main tunnel and branch tunnel, where the influence of the rate of ventilation and location of the fire are taken into account. Full article

This paper employs probability methods to evaluate the fire safety performance of prestressed steel–concrete beam bridges based on simulation experimental research. Firstly, fire simulation experimental sample analysis was conducted on actual small box girder bridges to assess the structural response of prestressed steel–concrete structures to fire, as is in line with engineering practice. Next, we constructed a reliability analysis model to investigate the fire resistance performance of prestressed steel–concrete beam bridges. Combining reliability theory with the finite element method, we established a reliability analysis method for the fire resistance performance of prestressed steel–concrete beam bridges. Subsequently, we proposed a safety factor evaluation model for the fire resistance performance of prestressed steel–concrete beam bridges and then established a safety factor evaluation method for the fire resistance performance of prestressed steel–concrete beam bridges based on reliability back analysis. Finally, based on the analysis of the post-fire structural response in the specific case of a steel–concrete continuous beam bridge project moving from conditions of being simply supported to continuously prestressed, a structural resistance sample of the prestressed steel–concrete beam bridge was generated via the uniform design method, and statistical analysis was conducted. Subsequently, probability methods were used to evaluate the safety of the prestressed steel–concrete beam bridge after a fire. Through analysis, we concluded that the duration of the fire had a significant impact on the structural performance of prestressed steel–concrete beam bridges and that the randomness of parameters had a significant impact on the safety reserve of prestressed steel–concrete beam bridges following the fire. Going forward, it is necessary to pay attention to this factor in specific engineering practices and strengthen the monitoring and statistical analysis of structural random characteristics. Full article

Over the past two decades, wildfire activity in the western USA has increased, especially in California. Wildfires not only affect air quality but also the environment at large, including chemical and physical properties of fire-affected soils, which are of great interest for prediction and mitigation of hydrological consequences. Hyperspectral reflectance can be used to remotely assess the effects of fires on soil and here we use it to characterize soils before and after three 2021 California wildfires (Dixie, Beckwourth Complex, and Caldor fire). We acquired reflectance spectra and compared changes in these spectra with changes in the chemistry of analyzed soils. For all three fires, the results show that 700 nm wavelength reflectance of ash samples collected 1 and 1.5 years after fire decreased between 36% and 76% compared to that of samples collected right after the fires. Additionally, significantly higher visible reflectance has been found for unburned compared to burned soil samples in each region that was studied. Infrared transmission measurements were used to characterize the carbonate content of soil and ash samples demonstrating a mostly positive relationship between carbonate content and visible reflectance, indicating a possible cause and effect between the two. Full article

Gel foam extinguishing agent (gel foam) has promising applications in the prevention and management of mine coal spontaneous combustion. Based on the research on coal spontaneous combustion and prevention technology, this article discusses recent studies on using gel foam to extinguish coal mines. The structural properties and principles of gel foam are described briefly. The research developments of three significant varieties of gel foam are then presented in detail, including silicate gel foam, acrylamide copolymer gel foam, and natural polymer gel foam. Meanwhile, the research status of gel foam anti-fire technology’s rheological properties, stability property, plugging property, and inhibitory properties are introduced. Furthermore, in conjunction with the research state, the prospects of the research direction of gel foam are proposed, which serve as a reference for future research on gel foam. Full article

Trench fires on sloped terrain are always complicated due to the corresponding flame dynamics and heat transfer mechanisms. Flame attachment may increase the rate of fire spread (ROS) by enlarging the heating area of unburned vegetation. In addition, variations in radiative and convective heat flux are of great importance to fire behavior characteristics. In this work, trench fire tests under different slopes (θ) and inclined sidewalls (A) were performed by numerical simulations based on the Lagrangian Particle Model (LPM) and Boundary Fuel Model (BFM) in the Fire Dynamics Simulator (FDS) and small-scale experiments, and the ROS, flame characteristics, and radiative/convective heat flux of the fire front are discussed in detail. The results indicate that the flame tends to adhere to the fuel bed with increasing slope angle and sidewall inclination. In particular, the flame becomes fully attached with a greater pressure difference than the buoyancy, which is caused by the unequal air entrainment between the front and behind the flame. When A = 90°, the critical slope angle of the flame adhesion (from slight tilt to full attachment) is identified as ~20°. The ROS (θ ≤ 15°) predicted by the BFM and LPM are closer to the small-scale experiments. The heat fluxes based on the experiments confirm the predominant mechanism of radiative heat transfer in trench fires at low slopes (θ ≤ 20°). Furthermore, convective heat transfer is more significant than radiative and becomes the main heating mechanism for θ ≥ 20°. Full article

Passive explosion-isolation facilities in underground coal mines, such as explosion-proof water troughs and bags, face challenges aligned with current trends in intelligent and unmanned technologies, due to restricted applicability and structural features. Grounded in the propagation laws and disaster mechanisms of gas explosions, the device in this paper enables accurate identification of explosion flames and pressure information. Utilizing a high-speed processor for rapid logical processing enables judgments within 1 ms. Graded activation of the operating mechanism is enabled by the device. The tunnel flame-proof device’s flame-extinguishing agent has a continuous action time of 6075 ms. Experiments on the active flame-proof effect of a 100 m³ gas explosion were conducted using a cross-sectional 7.2 m² large-tunnel test system. With a dosage of 5.6 kg/m², the powder flame-extinguishing agent completely extinguished the explosion flame within a 20 m range behind the explosion isolator. Numerical calculations unveiled the gas-phase chemical suppression mechanism of the powder flame-extinguishing agent NH₄H₂PO₄ in suppressing methane explosions. Building upon these findings, application technology for active flame-proofing was developed, offering technical support for intelligent prevention and control of gas explosions in underground coal mines. Full article

Mineral oil resources are depleting rapidly, and the slower conventional oil biodegradation process results in environmental pollution. To resolve this issue, cupric oxide (CuO) nanoparticles (1% wt) were introduced into a base oil to improve the lubricating capability of castor oil. In addition, 1% wt. sodium dodecyl sulfate was also blended with the base oil in order to attain the maximum dispersion stability of CuO nanoparticles in the castor oil. Afterward, thermophysical property, atomic absorption spectroscopy, and Fourier transform infrared radiation (FTIR) testing of the lubricant oil sample were performed before and after 100 h of engine operations at 75% throttle and 2200 rpm for each lubricant sample in order to check the capability of the novel oil with mineral oil. Compared with the natural mineral oil, the behavior of the CuO-based lubricant has essentially the same physical features, as measured according to ASTM standard methods. The physicochemical properties like (KV)_{40 °C}, (KV)_{100 °C}, FP, ash, and TBN decrease more in the case of the synthetic oil by 1.15, 1.11, 0.46, 1.1, and 1.2% than in the conventional oil, respectively. FTIR testing shows that the maximum peaks lie in the region of 500 to 1750 cm⁻¹, which shows the presence of C=O, C-N, and C-Br to a maximum extent in the lubricant oil sample. AAS testing shows that the synthetic oil has 21.64, 3.23, 21.44, and 1.23% higher chromium, iron, aluminum, and zinc content. However, the copper and calcium content in the synthetic oil is 14.72 and 17.68%, respectively. It can be concluded that novel bio-lubricants can be utilized as an alternative to those applications that are powered by naturally produced mineral oil after adding suitable additives that further enhance their performance. Full article

Fire spread in the Wildland–Urban Interface (WUI) can occur due to direct flame contact, convection, radiation, firebrand attack, or their combinations. Out of them, firebrand attack significantly contributes to damaging structures. To improve the resistance of buildings in wildfire-prone areas, the Australian Standards AS3959 provides construction requirements introducing Bushfire Attack Levels (BAL) based on quantified radiation heat flux. However, quantifying firebrand attack presents challenges, and the standard does not provide specific recommendations in this regard. This study aims to address this research gap by quantifying firebrand flux on houses according to the BALs in Mallee/Mulga-dominated vegetation using physics-based modelling. The study follows the AS3959 vegetation classifications and fire-weather conditions. The study considers Fire Danger Indices (FDI) of 100, 80, and 50 and identifies the housing components most susceptible to firebrand attack and radiant heat flux. The findings reveal an increasing firebrand flux with higher BAL values across all FDIs, with a greater percentage difference observed between FDIs 50 and 80 compared to FDIs 80 and 100. Furthermore, an exponential relationship is found between radiative heat flux and firebrand flux. This research contributes the development of effective strategies to mitigate the firebrand danger and enhance the resilience of structures to enhance AS3959. Full article

A global trend of increasing tree cover in savannas has been observed and ascribed to a range of possible causes, including CO₂ levels, changing rainfall and fire frequency. We tested these explanations in the Australian tropical savanna, taking 96 savanna ‘cool burning’ projects from Australia’s emissions offset scheme as case studies. We obtained readings of tree cover and explanatory variables from published remote sensing or spatial data sources. These were analysed using time-series linear regression to obtain coefficients for the influence of severe fire occurrence, annual rainfall and prior percentage tree cover. Although statistically significant coefficients for the key variables were found in only half (severe fire) or one quarter (rainfall) of the individual project models, when comparing all the model coefficients across the rainfall gradient, ecologically coherent explanations emerge. No residual trend was observed, suggesting rising CO₂ levels have not influenced tree cover over the study period. Our approach models tree cover change by separating ecological drivers from human-controlled factors such as fire management. This is an essential design feature of national emissions inventories and emissions offsets programs, where crediting must be additional to the expected baseline, and arise from human activity. Full article

In order to effectively prevent fire accidents and improve fire management capability, this paper describes the independent designs and builds of an experimental low-cost particle image velocimetry platform for a propane jet combustion flame using traditional mutual correlation theory. The particle image velocimetry (PIV) algorithm is written based on MATLAB software, allowing it to realise image preprocessing, multi-level grid window deformation inter-correlation calculations, and other functions. Fluid flow velocity and vorticity are used as entry points to study the flame combustion mechanism. The air flow field and vorticity above the propane jet flame are analysed. The results show that, from the level of fluid flow velocity, the maximum fluid flow velocity in the test area does not exceed 0.23 m/s, and the maximum transverse fluid flow velocity is close to 0.15 m/s. Additionally, the longitudinal fluid flow velocity is opposite the upper and lower portions of the longitudinal flow velocity, and there is a swirling phenomenon in the propane flame jet. From the vorticity level, the closer to the centre of the jet in the vortex plane, the faster the air flow speed, and simultaneously, in the upper and lower parts of the vortex, the air flow travels in the opposite direction and is of equal size. The particle image velocimetry platform that was independently designed in this study can efficiently characterise the dynamic flow field and the flow characteristics of complex combustion chambers, simultaneously ensuring high efficiency and reducing research costs. It provides a measurement method and experimental basis for the development of fire extinguishing equipment and numerical simulation, while also helping us to carry out a series of subsequent studies on fire extinguishing mechanisms. Full article

In this paper, four lithological parameters, that is, thermal conductivity, particle size, porosity, and saturation, are investigated by combining experimental observations with numerical simulations to study the influence laws and mechanisms of action on the combustion process of methane hydrate sediments. The variations in combustion characteristics parameters such as flame height, effective combustion ratio, and dimensionless discharge water mass with the lithological parameters are studied. In addition, the combustion mechanism of lithologic parameters on methane hydrate deposits is revealed. Combining the experimental results and simulation calculations to optimize the combustion of methane hydrate sediments, it is recommended to use methane hydrate sediment samples with high saturation and low thermal conductivity, while the oxidant concentration and porosity of methane hydrate sediment samples should be increased. Full article

In the context of a fire emergency, safe and efficient exits are of paramount importance for pedestrian evacuation. The recent rapid development in the construction industry has rendered exit structures more diverse and complex. However, little attention has been paid to the influence of exit structures on the efficiency of crowd evacuation processes. In this paper, a tentative experiment was designed to preliminarily reveal the effects of five exit structures (Exit 1, Exit 2, Exit 4, Exit 5, and Exit 3 as examples for comparison) on crowd evacuation. Exit 1 has door leaves opening outward. Exit 2 has door leaves opening inward. Exit 3 has no leaves. Exit 4 consists of double-layer exit doors with the doors opening outward. Exit 5 comprises double-layer exit doors with the doors opening both sides outwards Subsequently, according to the properties of this experiment, a social force-based simulation model was established using the AnyLogic software 8.8.4. By changing the exit width and the crowd density, data such as evacuation time, flow rate, crowd density, and time delay were investigated in detail. The results revealed a notable variation in the evacuation efficiency depending on the deign of the exit. The respective flow rates for Exits 1, 2, 3, 4, and 5 were 0.66 people/(m·s), 0.77 people/(m·s), 0.80 people/(m·s), 0.71 people/(m·s), and 0.66 people/(m·s). Although Exit 3 excelled in terms of evacuation efficiency, it is not directly applicable to real architectural structures. Therefore, Exit 2 emerged as a highly promising solution in terms of flow rate and population control in the exit area, underscoring the effectiveness and practicality of its structural design. It is prospective that the results of this study can offer engineering and technical professionals valuable references and guidance concerning the design of exit structures. Full article

This study investigated the effect of CO₂ on the burning behavior and radiative properties of a single ethanol droplet flame in microgravity. Measurements of the droplet burning rate, the flame size and temperature, and the radiative emissions were performed, under microgravity conditions for ethanol droplets burning in N₂ and CO₂ environments, using the 1.5 s drop tower facilities at the Korea Maritime and Ocean University (KMOU). The non-monotonic sooting behaviors (caused by the elevated O₂ concentrations) were found to have a significant influence on radiative heat losses in N₂ environments, resulting in non-linear droplet burning behaviors with O₂ concentrations. Due to the unique nature of CO₂ in microgravity, which absorbs radiative energy from the flame and raises the temperatures of the surrounding gases, the CO₂ environments suppressed the radiative heat losses from the flame, regardless of the non-monotonic sooting behavior observed at the higher O₂ concentrations. These experimental findings highlight the complicated physics of CO₂ gas radiation in microgravity, which has not been quantitatively explored. Full article

The ignition and combustion of three-component methane–hydrogen biofuel mixtures, considered as prospective fuels, were experimentally and numerically studied. Ignition delays in argon-diluted methane–hydrogen mixtures partially substituted with methanol or dimethyl ether were measured behind reflected shock waves in a temperature range of 1050–1900 K at pressures of 3.5–5.5 bar. The obtained results were used for validation of modern kinetic mechanisms for hydrocarbons combustion. Numerical modeling of the combustion of the considered fuels in air at elevated pressures and temperatures was carried out, simulating typical engine compressed conditions, and the dependencies of key parameters such as flame velocity and temperature on fuel composition were obtained. The results of the study can be used in developing new energy technologies, reducing the environmental impact of hydrocarbon combustion. Full article

Rice cultivation stands as the primary agricultural activity in Asia, generating a substantial amount of agricultural waste. Unfortunately, this waste is often disposed of through burning, contributing to severe environmental, health and climate issues. This study presents the characterization of PCDD/Fs, PCBs and PAHs. The emissions were quantified using a fixed-grid-system biomass plant and measuring the macro-pollutants online and sampling the organic micro-pollutants and metals in isokinetic mode, followed by ISO and CEN standards methods. Additionally, the role of agrochemicals was monitored in terms of metal catalysis resulting in POP emissions. This study provides the comprehensive characterization of the most relevant groups of pollutants (metals, PCDD/Fs, PCBs and PAHs) resulting from agricultural waste combustion. Prominent catalytic metals quantified were Cu (22–48 µg/Nm³) and Fe (78–113 µg/Nm³). Rice straw samples from AJK exhibited higher values of organochlorine micro-pollutants compared to those from Punjab and Sindh, i.e., ∑PCDD/F (2594 > 1493 > 856 pg/Nm³) and ∑PCB (41 > 38 > 30 pg/Nm³), respectively, whereas the organic micro-pollutants ∑c-PAH, indicators of incomplete combustion (PICs), were recorded high in the samples from Sindh followed by Punjab and AJK. The average EF is 100 pg/kg, 2.2 pg/kg and 1053.6 µg/kg for ∑PCDD/F, ∑PCB and ∑c-PAH. This study supports the idea that the phenomena leading to the formation of dioxin and dioxin-like compounds are influenced not only by poor combustion but also by the presence of metal catalysts in the burned fuel. Full article

Integrating fire into land management is crucial in fire-prone regions. To evaluate the effectiveness and efficiency of prescribed fire (PF), we employed the REMAINS model in NW Iberia’s Transboundary Biosphere Reserve Gerês-Xurés. We tested three levels of prescribed fire treatment effort for shrubland and grassland, employing three spatial allocation strategies: random distribution, prioritization in high-wildfire-risk zones, and creating fuel breaks by utilizing the existing road network. These approaches were assessed in isolation and in combination with three land-use scenarios: Business-as-usual (representing rural abandonment trends), High Nature Value farmland (reversing farmland abandonment), and Fire-Smart forest management (promoting fire-resistant landscapes). Our results confirm that PF is effective in reducing future wildfires (reductions up to 36%), with leverage values ranging from 0.07 to 0.45. Strategic spatial allocation, targeting wildfire-risk areas and existing road networks, is essential for maximizing prescribed fire’s efficiency (leverage effort of 0.32 and 0.45; i.e., approximately 3 ha of PF decrease subsequent wildfire by 1 ha). However, the PF treatments yield the best efficiency when integrated into land-use policies promoting ‘fire-smart’ landscapes (reaching leverage values of up to 1.78 under policies promoting ‘HNVf and ‘fire-smart’ forest conversion). These recommendations strengthen wildfire prevention and enhance landscape resilience in fire-prone regions. Full article

The number of tunnel fire accidents has increased with the scale of expressway tunnel construction and traffic flow. Due to the severity of tunnel fires, improving tunnel fire safety and reducing fire accident hazards has become a societal concern. It is essential to explore and evaluate tunnel fire safety literacy among the population. In this study, an online and on-site questionnaire survey was conducted in Hunan Province, China. A total of 1990 questionnaires were collected, of which 1573 were valid. Overall statistical analysis, descriptive statistics, and correlation analysis were performed on valid questionnaires. The results show that the overall level score rate of awareness of drivers and passengers regarding tunnel fire safety was only 0.43. In total, 58.42% of people were unaware of the pedestrian cross passages in expressway tunnels, and 68.40% were unable to recognize them. Similarly, 46.47% of people were unable to recognize evacuation signs in expressway tunnels. In addition, 39.29% of people chose the wrong evacuation behavior. The percentage of people who were aware of the correct usage of firefighting facilities in expressway tunnels was below 50.00%. Correlation analysis results show that tunnel users’ demographic characteristics significantly affected their cognition of expressway tunnel escape methods. This study shows that tunnel users’ emergency escape knowledge regarding tunnels is relatively low. Corresponding countermeasures were proposed to guide policy decisions for enhancing tunnel fire safety. Full article

An efficient catalyst is key to achieving the synthesis of electrochemical ammonia and improving safety. In this work, using biomass walnut shell as a carbon source and sodium thiosulfate as a sulfur source, sulfur-modified walnut shell-derived carbon material was synthesized via a simple low-temperature impregnation method at room temperature and atmospheric pressure as an effective electrochemical ammonia synthesis catalyst with high thermal stability. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption apparatus, thermogravimetry (TG), and other characterization methods were applied to analyze the micro-morphology and physicochemical structure of the electrocatalyst. The synthesized ammonia performance of the catalyst was measured using an ultraviolet (UV) spectrophotometer and electrochemical workstation. The catalyst design used the doping of sulfur atoms to create rich catalytic active sites, while the presence of elemental sulfur on the catalyst surface provided hydrophobicity, which was conducive to inhibiting competitive hydrogen evolution reaction (HER) and enhancing the electrocatalytic ammonia synthesis performance of the catalyst. Under normal temperature and pressure conditions, when a voltage of −0.45 V was applied, the ammonia yield in 0.05 M H₂SO₄ electrolyte was 10.39 μg_NH3 mg_cat.⁻¹ h⁻¹. The results showed that the introduction of sulfur effectively improved the electrocatalytic and thermal safety performance of bio-derived carbon materials, and the test presented that the performance of the catalyst was stable and reusable. Full article

Fire accidents cause alarming damage. They result in the loss of human lives, damage to property, and significant financial losses. Early fire ignition detection systems, particularly smoke detection systems, play a crucial role in enabling effective firefighting efforts. In this paper, a novel DL (Deep Learning) method, namely BoucaNet, is introduced for recognizing smoke on satellite images while addressing the associated challenging limitations. BoucaNet combines the strengths of the deep CNN EfficientNet v2 and the vision transformer EfficientFormer v2 for identifying smoke, cloud, haze, dust, land, and seaside classes. Extensive results demonstrate that BoucaNet achieved high performance, with an accuracy of 93.67%, an F1-score of 93.64%, and an inference time of 0.16 seconds compared with baseline methods. BoucaNet also showed a robust ability to overcome challenges, including complex backgrounds; detecting small smoke zones; handling varying smoke features such as size, shape, and color; and handling visual similarities between smoke, clouds, dust, and haze. Full article

An experimental study of ignition and flame front propagation during spark initiation in a hydrogen–air mixture in a semi-open channel with a porous coating is reported. The bottom surface of the channel was covered with a porous layer made of porous polyurethane or steel wool. The measurements were carried out for a stoichiometric mixture (equivalence ratio ER = 1.0) and for a lean mixture (ER = 0.4) of hydrogen with air, where ER is the molar excess of hydrogen. The flame front was recorded with a high-speed camera using the shadow method. Depending on the pore size, the velocity of the flame front and the sizes of disturbances generated on the surface of the flame front were determined. Qualitative features of the deflagration flame front at ER = 0.4, consisting of disturbances resembling small balls of flame, were discovered. The sizes of these disturbances significantly exceed the analytical values for the Darrieus–Landau instability. The effect of coatings made of porous polyurethane or steel wool is compared with the results obtained for an empty smooth channel. Depending on the hydrogen concentration in the hydrogen–air mixture, the velocity of the flame front compared to a smooth channel was three times higher when the channel was covered with steel wool and five times higher when the channel was covered with porous polyurethane. Full article

Mine fires are one of the common major disasters in underground mining. In addition to the external fire sources generated by mining equipment and mechanical and electrical equipment during operations, coal is exposed to air during mining, and spontaneous combustion is also the main cause of mine fires. In order to reduce the hidden danger of coal mines caused by spontaneous coal combustion during lignite mining, the microbial inhibition of coal spontaneous combustion is proposed in this paper. Via SEM, pore size analysis, and NMR and FT-IR experiments, the mechanism of coal spontaneous combustion is discussed and revealed. The modification of lignite before and after the addition of retardants is analyzed from the perspective of microstructure, and the change in flame retardancy of the lignite treated with two retardants compared with raw coal is explored. The results show that, compared with raw coal, a large number of calcium carbonate particles are attached to the surface of the coal sample after bioinhibition treatment, and the total pore volume and specific surface area of the coal sample after bioinhibition treatment are decreased by 68.49% and 74.01%, respectively, indicating that bioinhibition can effectively plug the primary pores. The results of NMR and Fourier infrared spectroscopy show that the chemical structure of the coal sample is mainly composed of aromatic carbon, followed by fatty carbon and carbonyl carbon. In addition, the contents of active groups (hydroxyl, carboxyl, and methyl/methylene) in lignite after bioretardation are lower than those in raw coal, and methyl/methylene content is decreased by 96.5%. The comparison shows that the flame-retardant performance of biological retardants is better than that of chemical retardants, which provides an effective solution for the efficient prevention and control of spontaneous combustion disasters in coal mines. Full article

In the unfortunate event of a fire, within the context of the evolution of façade fires, with a specific focus on the utilization of polystyrene thermal insulation (external thermal insulation composite system façades—ETICS façades), this study delves into the investigation of fires ignited by containers containing plastic bottles. Through an examination of the fluctuating temperatures within the affected room and its adjacent areas, as well as an assessment of the fire’s impact on polystyrene thermal insulation, this paper underscores the significance of incorporating non-combustible barriers into the building’s thermal insulation system. The tests conducted revealed that the temperature inside the room reached a maximum of 1100 °C, subsequently decreasing to 800 °C at a height of 2.5 m and approximately 400 °C at a height of 5 m. For this research, two 1100-L containers of household waste were employed, each weighing 45.5 kg and possessing a gross calorific value of 46.97 MJ/kg, with 10.7 kg of PET bottles inside, characterized by a higher calorific value of 23.90 MJ/kg as the source of the fire. Heat release rate highest values were obtained between 11 and 17 min, with a maximum value of 4919 kW. Thus, even in the absence of specific legislation, this study emphasizes the imperative need to establish safety distances for the storage of household waste away from the building’s façade to mitigate the risk of fire propagation, particularly in relation to materials such as polystyrene thermal insulation. Furthermore, in certain situations, extensive fire experiments on a grand scale, like the one undertaken in this research, hold a crucial position in confirming numerical findings for global researchers. This process assures the reliability and real-world usefulness of fire safety studies through the experimental outcomes presented in this investigation. Full article

Vegetation structural complexity (VSC) plays an essential role in the functioning and the stability of fire-prone Mediterranean ecosystems. However, we currently lack knowledge about the effects of increasing fire severity on the VSC spatial variability, as modulated by the plant community type in complex post-fire landscapes. Accordingly, this study explored, for the first time, the effect of fire severity on the VSC of different Mediterranean plant communities one year after fire by leveraging field inventory and Sentinel-1 C-band synthetic aperture radar (SAR) data. The field-evaluated VSC retrieved in post-fire scenarios from Sentinel-1 γ⁰ VV and VH backscatter data featured high fit (R² = 0.878) and low predictive error (RMSE = 0.112). Wall-to-wall VSC estimates showed that plant community types strongly modulated the VSC response to increasing fire severity, with this response strongly linked to the regenerative strategies of the dominant species in the community. Moderate and high fire severities had a strong impact, one year after fire, on the VSC of broom shrublands and Scots pine forests, dominated by facultative and obligate seeder species, respectively. In contrast, the fire-induced impacts on VSC were not significantly different between low and moderate fire-severity scenarios in communities dominated by resprouter species, i.e., heathlands and Pyrenean oak forests. Full article

The increasing frequency of wildfires has posed significant challenges to communities worldwide. The effectiveness of all aspects of disaster management depends on a credible estimation of the prevailing risk. Risk, the product of a hazard’s likelihood and its potential consequences, encompasses the probability of hazard occurrence, the exposure of assets to these hazards, existing vulnerabilities that amplify the consequences, and the capacity to manage, mitigate, and recover from their consequences. This paper employs the multiple criteria decision-making (MCDM) framework, which produces reliable results and allows for the customization of the relative importance of factors based on expert opinions. Utilizing the AROMAN algorithm, the study ranks counties in the state of Arizona according to their wildfire risk, drawing upon 25 factors categorized into expected annual loss, community resilience, and social vulnerability. A sensitivity analysis demonstrates the stability of the results when model parameters are altered, reinforcing the robustness of this approach in disaster risk assessment. While the paper primarily focuses on enhancing the safety of human communities in the context of wildfires, it highlights the versatility of the methodology, which can be applied to other natural hazards and accommodate more subjective risk and safety assessments. Full article

This paper investigates the sensitivity of factors influencing the transport of smoke in subway station fires by developing a three-dimensional physical model of a subway station using Building Information Modeling (BIM) technology and importing it into Fire Dynamics Simulator (FDS) software for numerical simulation. The orthogonal test method analyzes the effects of four common factors on temperature, CO concentration, and visibility. These factors are the mode of opening the screen door, the number of smoke vents opened, the number of smoke barriers, and the wind speed of the smoke vents. The results show that the smoke control system and the building structure influence smoke transport in subway stations, while the temperature and CO concentration gradually decrease as the distance from the fire source increases. In addition, the mode of opening the screen door is the most significant factor influencing temperature, CO concentration, and visibility using range and variance analysis. Moreover, the sensitivity analysis indicates that the optimal combination of all factors can significantly enhance the smoke exhaust efficiency. Compared with the average, the temperature optimal combination increases the smoke exhaust efficiency by 20.8%, CO concentration by 56.59%, and visibility by about 13.41%. This study provides a foundation for optimizing smoke control systems and formulating personnel evacuation strategies in subway stations. Full article

The high Andean páramos (AnP) are unique ecosystems that harbor high biodiversity and provide important ecosystem services, such as water supply and regulation, as well as carbon sequestration. In southern Ecuador, this ecosystem is threatened by anthropogenic burning activities to create pastures and agricultural land. However, knowledge of the effects of fire on soil properties and nutrient availability is still limited. This study conducted an experimental burn with different ignition patterns on an AnP plateau in southern Ecuador. Fire behavior (flame height, propagation speed, temperature reached on the soil), and fire severity were evaluated. In addition, soil samples were collected at 10 cm depth both 24 h and one year after the burns to measure the effects of fire on the main physico-chemical properties. The results indicate that the low severity of the experimental burns did not affect the physico-chemical properties of the soils, and therefore, soil quality was not altered. These results can help decision makers in the design of policies, regulations, and proposals for the conservation and environmental restoration of AnPs affected by wildfires in southern Ecuador. Full article

This paper investigates the application of the YOLOv7 object detection model combined with knowledge distillation techniques in forest fire detection. As an advanced object detection model, YOLOv7 boasts efficient real-time detection capabilities. However, its performance may be constrained in resource-limited environments. To address this challenge, this research proposes a novel approach: considering that deep neural networks undergo multi-layer mapping from the input to the output space, we define the knowledge propagation between layers by evaluating the dot product of features extracted from two different layers. To this end, we utilize the Flow of Solution Procedure (FSP) matrix based on the Gram matrix and redesign the distillation loss using the Pearson correlation coefficient, presenting a new knowledge distillation method termed ILKDG (Intermediate Layer Knowledge Distillation with Gram Matrix-based Feature Flow). Compared with the classical knowledge distillation algorithm, KD, ILKDG achieved a significant performance improvement on a self-created forest fire detection dataset. Specifically, without altering the student network’s parameters or network layers, mAP@0.5 improved by 2.9%, and mAP@0.5:0.95 increased by 2.7%. These results indicate that the proposed ILKDG method effectively enhances the accuracy and performance of forest fire detection without introducing additional parameters. The ILKDG method, based on the Gram matrix and Pearson correlation coefficient, presents a novel knowledge distillation approach, providing a fresh avenue for future research. Researchers can further optimize and refine this method to achieve superior results in fire detection. Full article