Experimental study on ignition behavior and heat transfer mechanism of multi-fire source fire in naturally ventilated tunnel

Development and validation of a novel method to predict flame behavior in tank fires based on CFD modeling and machine learning

Modeling study on fire propagation behavior and analysis of energy flow paths in double-layer LFP battery module

Fire behaviour of vacuum-infused glass fibre reinforced polymer sandwich panels: The role of polyurethane and polyethylene terephthalate foam cores and panel architecture

Firing behavior of hybrid scale-free neuronal networks

Neuronal firing behaviors are fundamental to brain information processing, and their abnormalities are closely associated with neurological disorders. This study conducts a comprehensive bifurcation and firing-behavior analysis of an improved Tabu Learning neuron model using a semi-analytical discrete implicit mapping framework. First, a discrete implicit mapping is constructed for the Tabu Learning neuron, enabling high-precision localization of stable and unstable periodic orbits within chaotic regimes and overcoming the limitations of conventional time-domain integration. Second, an eigenvalue-centered analysis is used to classify bifurcation types and stability, summarized in explicit bifurcation tables that reveal self-similar offset bifurcation routes, coexisting periodic and chaotic attractors, and chaotic bubbling firing patterns. Third, the proposed neuron model and its discrete mapping are implemented on an FPGA platform, where hardware experiments faithfully reproduce the analytically predicted stable and unstable motions, thereby tightly linking theoretical analysis and digital neuromorphic hardware. Overall, this work establishes a unified analytical–numerical–hardware framework for exploring complex neuronal dynamics and provides a potential basis for neuromodulation strategies and neuromorphic computing system design.

Wildfires threaten tropical rainforest conservation and restoration around the world, and they pose a particular risk to the unique species assemblages in eastern Madagascar. Following an intense period of wildfires in 2020–2022 that impacted 33% of 46 tropical forest restoration sites installed by the non‐profit organization Green Again Madagascar along Madagascar's central east coast, we compared fire intensity, fire severity, and native tree mortality in a subset of 11 experimental plantings to learn how tree planting choices impacted wildfire risk. Each restored site contained four 25 × 25 m treatment plots, which varied in tree planting size (81 vs. 625 m 2 ), density (123 vs. 1111 trees/ha), and species composition (fire‐vulnerable vs. fire‐resilient species planted on plot edges). Seventy‐five percent of 2772 trees were killed, with strong differences in mortality (41–100%) among 27 native species. The strongest treatment effect was species composition; plantings that included fire‐resilient tree species reduced overall mortality by 72%. Other tree planting choices (size, density, and position) had little or no impact on fire behavior or tree mortality. We conclude that wildfires impose a strong environmental filter on native Malagasy trees, selecting for species capable of resisting burning or resprouting following fire. Including these species in restoration plantings will increase the resilience of restored rainforests to wildfires but is unlikely to offer protection to the many endemic trees that are vulnerable to fire mortality.

Background. Vegetation, terrain and weather properties vary greatly spatially and temporally, all of which influence the resulting fire behavior. Aims. This study aims to enhance the applicability and predictive accuracy of the Rothermel model for mixed fuel spread rates under varying wind conditions in Northeast China. Methods. Surface fuels from Pinus koraiensis and Quercus mongolica plantations constructed laboratory fuel beds with controlled moisture content, wind speed, and packing ratios. A total of 142 controlled flame spread experiments were conducted under varying wind conditions. Empirical ROS data were then utilized to calibrate key parameters in the Rothermel model. Key results. Observed ROS values ranged from 1.38 to 11.09 m·min⁻¹. Direct application of the Rothermel model showed limited accuracy for mixed fuels (MAE = 2.536 m·min⁻¹; MRE = 135.1%). Targeted adjustment of the wind coefficient (ϕw) under flat terrain conditions yielded the most significant improvement. Further calibration of the reaction intensity (IR) parameter enhanced model performance substantially, achieving MAE = 0.393 m·min⁻¹ and MRE = 24.9%. Conclusion. The unmodified Rothermel model inadequately predicts ROS in mixed Pinus koraiensis–Quercus mongolica surface fuels. Parameter calibration using empirical combustion data significantly reduces prediction errors and improves model accuracy. Implications. This research offers a technique for applying the Rothermel model locally in China, thereby aiding in the country's forest fire suppression and management efforts.

Although nervous system maturation is a key factor underlying the difference in muscle strength between children and adults, specific neural strategies for modulating motor unit (MU) firing during graded force production remain largely unexplored. This study aimed to clarify the differences in MU firing behavior between children and young adults during submaximal isometric ramp contractions. Eighteen healthy children (aged 6-12 years) and 18 healthy young adults performed maximal voluntary contractions (MVCs) and submaximal ramp contractions to 50% of MVC for isometric knee extension. High-density surface electromyography data were collected from the vastus lateralis muscle and were decomposed to identify individual MU firing. MUs were analyzed according to their recruitment thresholds (RTs) to compare their firing rates (FRs) and the change in FR (ΔMU FR) at various force intervals. Children consistently exhibited significantly higher MU FRs than adults across almost all RT groups and force levels. ΔMU FR was higher in children only during the initial 10%-20% MVC interval for the lowest-threshold MUs but was significantly lower for higher threshold MUs at higher force levels. Higher MU FRs in children likely represent a functional adaptation to compensate for immature muscle contractile properties, thereby ensuring effective force generation. This distinct neural control strategy, which combines high initial rates with subsequent firing saturation, may reflect the ongoing maturation of spinal motor control. These findings provide a valuable reference for assessing pediatric neuromuscular disorders and can inform the design of more effective exercise and rehabilitation programs.

This study examines the influence of thermal treatment on the ignition properties of Norway spruce (Piceaabies (L.) H. Karst.) and sessile oak (Quercus petraea (Matt.) Liebl.) wood. Using a cone calorimeter both untreated and thermally modified samples (180°C for 6 h) were analysed to determine key fire modelling parameters: combustion efficiency, critical heat flux, ignition temperature, thermal inertia, and thermal response parameter. Obtained results reveal that thermally treated wood exhibits higher combustion efficiency than its untreated equivalent, with spruce generally outperforming oak. The effect of thermal treatment on other properties was species-dependent. Thermally treated spruce showed an increase in critical heat flux and a decrease in both thermal inertia and the thermal response parameter. Conversely, thermally treated oak displayed a reduction in critical heat flux and an increase in both thermal inertia and the thermal response parameter. These results highlight the complex, species-specific effects of thermal modification on the fire behaviour of wood.

Fire hazard presents a critical challenge to the structural reliability of underground modular infrastructure. This study examines the fire resistance performance of prefabricated monolithic utility tunnels featuring longitudinal threaded connections. A series of fire exposure tests was conducted on assembled utility tunnel specimens using different bolt materials and thermal conditions, enabling evaluation of fire behavior, deformation behavior, and residual capacity. The observed thermal properties revealed significant temperature gradients across tunnel sections, with the peak internal–external differential reaching 536.8 °C. Post-fire mechanical degradation was evident in reduced stiffness and ductility, and the residual load-bearing capacity declined by up to 12.28% compared to unexposed specimens. Specimens using high-strength threaded bolts demonstrated superior performance compared to stainless steel bolt specimens, exhibiting a 4.67% higher residual capacity and 13.87% less residual deformation. A sequential thermal–mechanical finite element model was developed and calibrated based on experimental results, offering a reliable simulation framework for investigating fire-induced damage and residual strength in modular utility tunnel systems. These findings provide a quantitative basis for fire safety assessment.

Purpose The advanced finite element software SAFIR has been extensively validated and benchmarked against the cases set out in the German National Annex for EN 1991-1-2 (2010) (DIN EN, 1991-1-2/NA, 2010; Wald et al., 2012; Ferreira et al., 2018a; Zaharia and Gernay et al.; Ferreira et al., 2018b; Pintea and Franssen, 1997). The existing validation studies focus on recent forms of construction and are not necessarily relevant to historic structures. This paper explores the use of advanced numerical techniques to estimate the anticipated fire behaviour of existing floor systems used in historic buildings in the UK. The main objective is to benchmark the numerical model against standard fire resistance test data for historic floor constructions. Design/methodology/approach The methodology involves using SAFIR software to validate the thermo-mechanical behaviour of historic types of floors using standard fire resistance test evidence. The numerical analysis is based on two steps. In the first step, a heat transfer analysis is performed to determine the heat distribution through the floor section. In the second step, the mechanical analysis is performed based on the temperature output from the thermal analysis, which considers a reduction of the material properties at elevated temperatures. Findings This paper provides a thorough examination of standard fire resistance test data for filler joists and hollow pot floors, which were conducted as part of the Investigation of Building Fires study in the UK during the 1950s. The overarching objective of the paper is to validate the applicability of modern numerical tools such as SAFIR software in evaluating the thermo-mechanical performance of historic forms of construction. Through the thermo-mechanical analysis and validation exercises, this paper demonstrates the accuracy of advanced numerical techniques in evaluating the fire behaviour of historic forms of construction. Specifically, it aims to validate numerical methods by comparing them against fire resistance test data, focusing on two significant historical floor types: filler joists and hollow pot floors. The analysis presented in the paper shows that the formulation for the material properties (steel and concrete) from the Eurocodes can accurately capture the behaviour in fire of the two floor systems. Research limitations/implications One limitation is that these numerical methods cannot predict local integrity failure (e.g. cracking or spalling) or the effects of undetected defects. Originality/value The study presented in the paper highlights the potential of applying advanced numerical techniques to enhance the understanding and evaluation of the fire performance of historical elements of structure. This not only facilitates more accurate assessments of fire resistance but also offers invaluable insights for architects, engineers and preservationists involved in the conservation and refurbishment of historic buildings.

Litter flammability is a key factor in fire behavior prediction and management, particularly in ecosystems with frequent fire regimes. While numerous studies have examined the physical, morphological, and chemical traits influencing flammability and have speculated about the relative importance of each factor, few have isolated the effects of bulk density and leaf morphology on fire dynamics or performed other mechanistic studies. This research investigates how these factors contribute to litter combustion by standardizing leaf shape and size across four Quercus species while measuring key fire behavior metrics, including flame height, burn duration, temperature variation, and mass loss. Results indicate that bulk density plays a significant role in flame height and mass loss and has a lesser, but not negligible impact on flame duration and max temperature. Each species responded similarly but each to a different degree in response to equal changes in bed height and bulk density, indicating bulk density has a non-linear effect on flammability characteristics. These findings underscore the importance of considering inherent leaf traits alongside bulk density when predicting fire behavior and informing fire management.

Fuel traits are important determinants of fire behavior and regime in savannas and, thus, of how fire affects plant communities. However, whether these traits are correlated, predictable and how they are influenced by biotic and abiotic drivers remain to be rigorously evaluated. We hypothesized that, given their overall dependence on grass biomass, fuel traits were mutually correlated (via correlations to grass biomass), change predictably in space and time, and that they influence fire regimes. We sampled 31 plots distributed in five soil classes in a savanna‐dominated landscape in Brazil and measured the following surface fuel traits: fuel height, continuity, bulk density, bed flammability, composition, total load and grass load. We also obtained data on landscape predictors, such as soil clay content, fire history, climate, canopy cover, elevation , and on future (post‐sampling) fire incidence. We used Pearson correlation and principal component analyses to test for associations among fuel traits, and generalized linear model for assessing 1) landscape predictors effects on fuel traits; and 2) fuel trait effects on future fire incidence. We found two leading axes of fuel trait variability. The first axis was positively correlated with fuel height, continuity, total load, bed flammability, grass load and cover. In this axis, flammability increased with time since last fire and clay content and decreased with canopy cover and rainfall seasonality. The second axis was positively correlated with fuel bulk density, continuity, shrub and litter covers, and negatively with fuel bed flammability. In this axis, flammability decreased with canopy cover and clay content. Grass fuel load was the best predictor of future fire incidence. Our results suggest that fuel traits change predictably in space and time and explain variability in fire regimes in savannas. These findings contribute to a better understanding of fire regimes while providing important information for managers and decision makers.

Mid-term effects of silvicultural treatments on fuel dynamics and fire behavior in different developmental stages of Larix principis-rupprechtii

Impacts of commercial thinning on stand demography, fuel loads, microclimate and fire behaviour in Eucalyptus delegatensis forest in eastern Tasmania

The hidden variable: Impacts of human decision-making on prescribed fire outcomes.

Abstract This study examines the impact of a low-intensity forest understory fire on turbulent heat transfer using sonic anemometer measurements at lower (3 m), mid- (10 m), and upper (19 m) canopy from five in situ towers within the burn plot and one upwind control tower. The fire induced up to a 50-fold increase in kinematic vertical turbulent heat flux, primarily driven by increased temperature perturbations. The maximum flux occurred at midcanopy due to decreasing temperature and increasing vertical velocity perturbations from the lower to upper canopy. A double peak in turbulent heat flux during fire-front passage resulted from interactions between fire-induced turbulence and atmospheric flow, where a downdraft immediately following the fire front temporarily suppressed flux before the second peak emerged. The flux increase was largely due to intensified ejection events rather than a higher event frequency, indicating enhanced heat transfer efficiency. At mid- and upper canopy levels, sweep events increased at all but one tower, while at the lower canopy, inward interactions increased and outward interactions decreased across all towers. The arrival of a sea-breeze front, bringing cooler air and stronger winds, dampened fire effects. During the fire, spectral energy for temperature and heat flux intensified at higher frequencies, particularly in the lower canopy, flattening the spectral curve in the inertial subrange. Buoyancy-driven turbulence dominated heat transfer, although some mechanically generated turbulence was also present. These findings enhance the understanding of fire-induced turbulence and heat transfer, aiding the development of fire behavior and smoke dispersion models for improved fire management. Significance Statement This study investigates fire-induced turbulence and heat transfer during a low-intensity forest understory fire, using unprecedented sonic anemometer data from multiple in situ towers at lower, mid-, and upper canopy levels, along with an upwind control tower. The findings reveal up to a 50-fold increase in vertical turbulent heat flux, peaking at midcanopy, and highlight complex fire–atmosphere interactions. Key dynamics include a strong downdraft trailing the fire front, producing a double peak in heat flux, a substantial rise in ejection event contributions across the canopy, increased inward interactions in the lower canopy, and interactions with an incoming sea-breeze front. These insights enhance fire behavior and smoke dispersion models, informing more effective fire management strategies.

Experimental and numerical study on the fire resistance behavior of steel truss girder structure in double deck suspension bridges

Landscape-level, participatory wildfire governance reduces fire hazard and potential carbon emission.