Search Results (15,253)

This study investigates the mechanical performance, high-temperature resistance, and microstructural characteristics of ground granulated blast furnace slag (GGBFS)-based geopolymer composites reinforced with boron nitride (BN)-modified hemp nanofibers. BN-modified hemp nanofibers (PVA-mBN/Hemp) were produced via electrospinning and incorporated into geopolymer mixtures at varying ratios ranging from 0 to 4 wt%. The effects of nanofiber content on composite properties were evaluated through mechanical testing, ultrasonic pulse velocity (UPV) measurements, and exposure to elevated temperatures (300–1200 °C), supported by SEM-EDS, FTIR, and XRD analyses. The results indicate that low nanofiber additions (0.5–1 wt%) improve flexural strength by up to 15%, although compressive strength is slightly reduced due to increased porosity. UPV measurements confirm the changes in internal structure. At elevated temperatures, nanofiber-reinforced samples exhibit enhanced residual strength compared to the control specimens, particularly at moderate temperatures, whereas significant degradation occurs above 900 °C. Microstructural analyses reveal improved fiber-matrix interaction, reduced crack propagation, and enhanced thermal stability attributed to BN modification. Overall, the incorporation of 0.5–1 wt% BN-modified hemp nanofibers provides an effective balance between mechanical performance and high-temperature resistance, highlighting their potential for use in sustainable and fire-resistant construction materials. This study contributes to the United Nations Sustainable Development Goals (SDGs), particularly SDG 9 (Industry, Innovation, and Infrastructure), SDG 11 (Sustainable Cities and Communities), and SDG 12 (Responsible Consumption and Production). Full article

In a weakly constrained, confined space, four common ignition sources—electrical spark, open flame, tungsten filament, and electrochemical igniter—were employed to investigate how the ignition mode influences the overpressure and flame-propagation characteristics during the vented explosion of gasoline vapor. The results show that the explosion process can be divided into four stages, featuring three typical overpressure peaks. The flame velocity exhibits two pronounced accelerations: one upon rupture of the vent membrane and another when the flame reaches the vent opening. Among the ignition sources tested, the electric spark produced the most severe destructive effects associated with overpressure, while the electrochemical igniter yielded the fastest flame propagation, and the tungsten filament ignition generated the longest external flame, constituting the greatest external fire threat. Explosions initiated by the tungsten filament and electrochemical igniter experience flame instability at the outset, induced by disturbances from the ignition source itself. Full article

Climate change has intensified global wildfire risks, yet national-scale prediction remains challenging due to the difficulty of consistently monitoring fuel conditions and human ignition factors. This study introduces calendar-based time proxy variables as structural surrogates for these unobservable drivers and integrates them with the Canadian Fire Weather Index (FWI) within a parsimonious framework for seasonally fire-prone regions such as South Korea. Using 15 years of nationwide wildfire records and daily observations from 100 ASOS stations (2011–2025), predictive performance was evaluated across eight models and five feature sets (Time-only, Weather-only, Weather + Time, FWI-only, and FWI + Time). Based on test-set mean AUC, the Time-only feature set reached 0.7374, clearly exceeding the random-classifier baseline (AUC = 0.5) and indicating the independent predictive value of time proxy variables. Furthermore, integrating time proxies with FWI improved performance, with the best model (CatBoost) achieving test AUC = 0.8394 and Recall = 0.6019. Multi-model SHAP analysis revealed complementary contributions of FWI components (53.7% ± 4.7%) and time proxy variables (46.3% ± 4.7%). Overall, the results demonstrate that a simple yet structured input design based on time proxy variables provides meaningful predictive performance for nationwide wildfire early warning systems. Full article

Firefighters face high-stress occupational demands and irregular shift work that negatively impact sleep quality, which is intrinsically linked to long-term physical and psychological health. This cross-sectional study examines how the physical sleep environment (home vs. work) and station sleeping arrangements (bunk-style vs. individual dorm-style quarters) influence subjective sleep quality in this population. Sixty-six career firefighters (Age = 40.89 ± 11.05 years), completed the Pittsburgh Sleep Quality Index (PSQI) to assess their sleep in both home and fire station environments, with data analyzed using Wilcoxon Signed Ranks and Mann–Whitney U tests. The results reveal significant differences (p < 0.001), with sleep duration, efficiency, subjective quality, and global PSQI scores all performing significantly better at home than at work. Notably, no significant differences were found between bunk-style and dorm-style sleeping quarters at the station. These findings suggest that firefighters experience poorer sleep while on duty regardless of room design, indicating that operational stressors like call volume and nocturnal arousal may be more influential on sleep quality than the physical arrangement of sleeping quarters, and could inform organizational policies and wellness programs aimed at reducing occupational fatigue. Full article

Nanoparticle-modified concrete can exhibit improved mechanical performance, yet its residual compressive strength (Fc) after fire-like thermal exposure is difficult to predict because the response depends on both mixture design and heating conditions. Building on recent advances in explainable machine learning (ML) for cementitious materials, this study compiles 218 literature datapoints of post-heating Fc from 100 mm concrete cubes incorporating carbon nanotubes (CNTs) and nano-alumina (NA), exposed to 20–800 °C for up to 2 h. Seven input variables are used: cement-to-total aggregate ratio, CNT-to-cement ratio, NA-to-cement ratio, coarse-to-fine aggregate ratio, water-to-cement ratio, peak temperature, and exposure duration at temperature. Two particle-swarm-optimized ensemble regression models, Extreme Gradient Boosting (XGB-PSO) and Random Forest (RF-PSO), were developed and evaluated using a 70/30 train–test split with K-fold cross-validation on the training set. SHAP, individual conditional expectation (ICE), and partial dependence plots (PDPs) were employed to study the individual and combined effects of each input parameter on Fc prediction. The results demonstrated that the XGB-PSO model provides the best predictive performance (training R² = 0.9983; testing R² = 0.9434; testing MAE = 1.3168 MPa). Model interpretability was assessed using SHAP, ICE, and PDP analyses, revealing that temperature and exposure duration dominate strength loss, while CNTs and NA contribute positively within dose-dependent regimes. The highest predicted strengths occur for CNTs of 0.05% to 0.15% and NA of 0.65 to 2.71% (by cement mass) under moderate temperature exposure. A Python-based graphical user interface is provided to support rapid what-if assessment of CNT–NA mixtures under elevated-temperature scenarios. Full article

This study evaluates the structural performance of sliding-type evacuation ladders under realistic fire evacuation loading conditions using parametric numerical analysis. A series of finite element models was developed based on the original ladder design, and key parameters—including member thickness (1–4 mm), overlap length between modular units (40–70 mm), loading configurations, and boundary conditions at the ladder base—were systematically varied. A total of 288 numerical cases were analyzed to investigate their influence on global displacement behavior. The results indicate that a minimum member thickness of 2 mm is required to satisfy displacement-based serviceability criteria; however, this threshold may be insufficient when connection flexibility is considered. The overlap length has a more pronounced effect on structural performance for thinner members, while the loading height has a significant effect on the displacement response. In addition, the boundary condition at the ladder base plays a critical role, with vertical support conditions substantially reducing overall displacement. These findings highlight the importance of system-level structural evaluation beyond component-based testing. They also provide practical insights for improving the design criteria and installation conditions of evacuation ladders in high-rise residential buildings during fire emergencies. Full article

Oblique detonation engines have been proposed for hypersonic propulsion because detonation-based heat addition can, in principle, provide rapid energy release with reduced total-pressure penalties. We investigate non-premixed injection/mixing of an RP-3 aviation-kerosene surrogate in a constrained supersonic channel and its impact on oblique-detonation initiation, stabilization, and static pressure gain. Numerical simulations are performed for a Mach 8 inflow representative of a 30 km altitude condition using an OpenFOAM v7-based reacting-flow solver. We analyze the pressure-gain process following detonation onset, quantify the effects of the inducer-ramp angle, and qualitatively assess the predicted initiation/stabilization trends against direct-connect hot-fire experiments. The results show that non-premixed injection into a supersonic crossflow yields limited mixing over the available mixing length and results in a strongly stratified inflow to the combustor. In the constrained passage, a train of reflected shocks forms and progressively reduces the total-pressure recovery factor along the mixing section, which asymptotically approaches ~0.49. In the combustor, the inducer-ramp angle controls whether and how a stabilized oblique detonation can be established. For a 25° ramp, no self-sustained ODW is obtained under the present conditions, whereas stabilized ODWs are observed for 30° and 35° ramps, exhibiting abrupt and smooth topologies, respectively. These initiation thresholds and stabilized morphologies show qualitative consistency with the direct-connect observations. Due to fuel stratification, pressure gain varies among streamlines but consistently follows a “primary compression–plateau–secondary pressure rise” sequence; the secondary stage contributes approximately 17.54–27.98% of the static pressure rise. Full article

To realize the real-time structural health and operational safety monitoring of military and industrial devices, such as hypersonic vehicles, aero-engine blades, and thermal power plant boilers, at operating temperatures up to and beyond 1400 °C, this study presents a miniaturised, integrated, high-thermal-stability wireless sensor device. This study investigated the influence of temperature on the interdigital electrodes (IDEs) of surface acoustic wave (SAW) temperature sensors for three configurations: bare electrode, single-layer protective film, and multilayer composite film. While the exposed electrode exhibited thermal stability at 1000 °C, it underwent structural failure at 1250 °C. To achieve health monitoring at temperatures exceeding 1400 °C, an Al₂O₃/AlN/Al₂O₃ multilayer protective architecture was developed. The device demonstrated functionality up to 1400 °C with a temperature coefficient of frequency (TCF) of −40.03 ppm/°C, yielding a sensitivity of 12.0 kHz/°C at a center frequency of ~300 MHz. The electrode protection structure elevated the maximum operating temperature. A hybrid heterogeneous integration of high-temperature co-fired ceramic (HTCC) inverted-F antenna and a Langasite (LGS) SAW device with a multilayer composite film was realised. The wireless device maintained functionality from room temperature to 1400 °C and withstood 1400 °C for 2 h, exhibiting a maximum repeatability error of 12.67% (corresponding to a temperature measurement error of ~177.4 °C at 1400 °C). This integrated design enables the miniaturization of high-temperature wireless sensors, making them suitable for harsh environments. Full article

Impairment in blood supply to the brain deprives its cells of the much-needed nutrients and molecules such as oxygen and glucose necessary for its development, growth and survival. This will set up a host of pathological processes such as impaired homeostasis, energy failure, excitotoxicity, oxidative stress, impaired protein synthesis, inflammation, cytokine-mediated toxicity and impairment of blood–brain barrier. These pathological processes will result in the damage or death of the cells depending on the extent of the deprivation. Similarly, they will impair synthesis of acetylcholine (Ach) and norepinephrine (NE), which are important neurotransmitters in the cholinergic and adrenergic systems responsible for cellular communication and functions. Thus, interventions to help arrest and/or modulate the initial and subsequent pathological states and help recover the functions of the brain are needed. One of such interventions is vagus nerve stimulation, which helps activate the cholinergic and the adrenergic systems via projections of the afferent fibers of the vagus nerve to the nucleus of the solitary tract (NTS). Activation of the cholinergic and the adrenergic systems results in reduction in pro-inflammatory factors such as tumor necrosis α, increase in pro-angiogenic factors and increase in firing of adrenergic neurons in the central nervous system (CNS). Full article

This manuscript introduces a new class of count time series models, referred to as the minification integer-valued Split-BREAK (MIN–SB) process. The proposed framework extends the Split-BREAK modeling philosophy to the integer-valued setting and provides a flexible mechanism for capturing rare events, zero inflation, and structural regime changes frequently observed in safety-related data. The main stochastic properties of the MIN–SB process are derived, including stationarity conditions, explicit moment structure, and correlation dynamics. A key theoretical result reveals an implicit hidden Markov structure underlying the observable process, providing a structural explanation for zero clustering observed in rare-event count processes. Parameter estimation is developed using a simulated method of moments (SMM) approach based on zero-related statistics, and the asymptotic properties of the resulting estimators are established. A Monte Carlo simulation study demonstrates favorable finite-sample performance of the proposed estimation procedure. The practical usefulness of the model is illustrated through an empirical application to time series of injuries and fatalities caused by fire accidents in Serbia. The results show that the MIN–SB specification provides a flexible and accurate framework for modeling zero-inflated count processes arising in fire safety dynamics. Full article

In contiguous seam mining, the sudden large-scale collapse of a hard roof in an overlying goaf generates violent impact airflow, driving hazardous gases into the underlying working face and seriously threatening production safety. However, quantitative analysis of airflow responses under such transient impacts is rare for conventional exhaust ventilation systems, and proactive control strategies remain lacking. This study hypothesized that replacing exhaust ventilation with a forced ventilation system builds a sufficient counter-pressure gradient across the working face to block the downward migration of hazardous gases. Taking the Longhua Coal Mine as the engineering background, this study combines a theoretical velocity model of roof-collapse-induced impact airflow with numerical simulations and subsequently implements a forced ventilation system on site. Results show that under exhaust ventilation, roof collapse greatly intensifies air leakage in the goaf, causing the CO concentration at the return corner to spike to 5000 ppm within only 0.2 s. In contrast, the field-deployed forced ventilation system effectively suppresses this impact: by keeping the pressure difference across the air regulator within 338–417 Pa, the CO concentration drops from 36 ppm to below 15 ppm. Complemented by a real-time monitoring system for goaf pressure surges and hazardous gases, this strategy successfully shifts disaster control from passive ventilation to active aerodynamic suppression. This study provides a robust theoretical foundation and practical engineering reference for disaster prevention in contiguous seam mining. Full article

Lithium-ion battery (LIB) cells are available in various sizes, formats, and chemistries. Should a LIB be exposed to conditions outside its operating parameters, each variation affects the cell failure mechanisms and any resultant fire dynamic. Battery fires can be dynamic events that differ significantly from those solid-, liquid- or gas-based fire curves often used in standard building material fire resistance tests. This preliminary research aimed to investigate how standard building materials, sometimes used as a compartment fire envelope, such as gypsum plasterboard, react when exposed to a dynamic battery fire. The research explored batteries that produced jet fires, could act as projectiles, or produced overpressures when they failed. The results showed that cylindrical cells can travel at significant speeds and distances due to expulsing the cell’s contents through the cell’s vent or ejected end cap. These cells were shown to be capable of piercing plasterboard and remain hot enough to present a fire risk where they fall on the far side of the plasterboard. It was also found that the overpressures produced by failing prismatic cells affected the structural integrity of some building materials. The results show a need for further research into the effectiveness of standard building fire controls when exposed to LIB fires. Full article

This study examined how mechanical, electrical, and plumbing (MEP) practitioners understand and apply quality and safety management in construction projects in Taiwan. It focused on the gap between what practitioners know about best practices and what they can carry out on site, defined here as the “Cognitive–Execution Gap.” A mixed-methods design was used, combining a questionnaire survey of 130 MEP practitioners with semi-structured interviews with six senior experts. Practitioners with MEP-related academic backgrounds scored significantly higher in professional knowledge and practice than those from unrelated fields, with mean differences of 0.87 and 0.78 points on a 5-point scale, respectively (both p < 0.001). In contrast, awareness of management optimization strategies was high and similar across all demographic groups. Interview findings suggest that schedule pressure, the lower organizational status of MEP compared with civil engineering, and persistent talent shortages prevent practitioners from applying the practices that they recognize as necessary. The results provide evidence consistent with a Cognitive–Execution Gap and suggest that bridging it requires organization-level reforms, including prospectively evaluated BIM-based coordination, clearer standard operating procedures and performance indicators, and structured mentorship programs to strengthen professional capacity in MEP engineering. Full article

Coal spontaneous combustion in gob areas is a major disaster endangering safe production in underground coal mines, and accurate prediction of carbon monoxide (CO), the core signature gas of coal oxidation, is critical for early warning and targeted prevention of mine fire disasters. However, CO concentration in gob areas is governed by complex gas–solid thermal–chemical multi-field coupling, presenting strong nonlinear characteristics. Traditional numerical methods suffer from prohibitive computational cost, purely data-driven models have inherent black-box defects, and conventional Physics-Informed Neural Networks (PINNs) require explicit full governing equations, which are hard to establish for such complex systems. This paper first proposes a Physics-Informed Modified Kolmogorov–Arnold Network (PIM-KAN), which deeply integrates domain physical knowledge with KAN architecture via a physics encoding layer, a residual-modified KAN layer, a multi-physics attention mechanism, and a multi-term physical consistency constraint framework. Experiments on 3125 real coal mine field samples show that the PIM-KAN achieves R² = 0.9965 and RMSE = 0.9290 ppm, reducing RMSE by 19.5% compared with MLP, and outperforming all baseline models. Ablation studies confirm the significant contribution of each innovation module, and attention weight analysis is highly consistent with Arrhenius reaction kinetics, verifying its superior prediction accuracy, physical consistency and intrinsic interpretability. Full article

Forest fires are an increasing environmental challenge in Southern Europe, requiring reliable tools for assessing both fire-induced disturbances and subsequent ecosystem recovery. This study presents an integrated satellite-based system for automated monitoring of post-fire forest dynamics. The system combines multispectral data from Sentinel-2 and Landsat (TM, ETM+, OLI, OLI-2) with thermal anomaly information from MODIS and VIIRS within a unified processing framework. It is structured into two modules: Post-Fire Disturbance (PFDMO) and Post-Fire Recovery (PFRMO). The methodology builds on a validated algorithm integrating the Disturbance Index (DI), Vector of Instantaneous Condition (VIC), and Direction Angle (DA), enabling automated multi-temporal analysis from fire detection to recovery assessment. The system was applied to three wildfire-affected areas in Bulgaria under different environmental conditions. Results reveal substantial spatial variability in disturbance and recovery, with PFDMO values ranging from −5.17 to +10.16 and PFRMO values from −2.25 to +7.40. The results demonstrate the applicability of the proposed system for monitoring post-fire forest dynamics and illustrate its potential to support informed decision-making in forest management, biodiversity conservation, and sustainable resource use. The main contribution of the system lies in the integration of disturbance and recovery assessment within a single automated and scalable workflow based on freely available satellite data. Full article