Next Issue
Volume 6, December
Previous Issue
Volume 6, October
 
 

Fire, Volume 6, Issue 11 (November 2023) – 36 articles

Cover Story (view full-size image): In many areas, fires ≥400 ha are considered large and potentially unpredictable, with the result that managers may opt for full suppression. Medium-sized fires (40 – 400 ha) may be more indicative of wildfires before widespread fire suppression and may have effects more typical of those expected from similarly-sized prescribed fires. We characterized and contrasted the burn severity and frequency of wildfire from 1984 – 2020 by vegetation type in the discontinuous, variable ecosystems of Utah. Medium-sized fires had higher severity than large fires in non-forested vegetation types, but forested vegetation types showed the reverse. Large fires had higher severity in the most severe quartile of area burned. Managers planning prescribed fires <400 ha may find data from medium-sized fires to be more indicative of typical effects than vegetation type averages that are weighted to large fires. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
13 pages, 2233 KiB  
Article
The Bulk Density and Cohesion of Submicron Particles Emitted by a Residential Boiler When Burning Solid Fuels
Fire 2023, 6(11), 445; https://doi.org/10.3390/fire6110445 - 19 Nov 2023
Viewed by 1400
Abstract
Particles emitted from combustion sources have a negative impact on human health and the environment. The solid fuel boilers that are used in households are a significant source of air pollution. The present study analyzes particulate matter (PM) produced during the combustion of [...] Read more.
Particles emitted from combustion sources have a negative impact on human health and the environment. The solid fuel boilers that are used in households are a significant source of air pollution. The present study analyzes particulate matter (PM) produced during the combustion of wood pellets, wood logs, and coke in a residential boiler. The captured particles’ particle size distribution, bulk density, and cohesion are identified. A cascade impactor was used to capture the particles, and an optical digital microscope was used to determine the bulk density and cohesion (angle of repose) of the particles. The results show that the highest particle mass concentration emitted by the boiler falls within the interval of 89–146 nm, with the combustion of wood logs producing the most particles and coke combustion producing the least. The bulk density of particles of 51–595 nm (impactor stages 4–8) ranges from 320 to 785 kg/m3 for wood logs, 372–1108 kg/m3 for wood pellets, and 435–1330 kg/m3 for coke. The PM1 particles (impactor stage 4) have the highest bulk density. In the particle size range studied, the bulk density of particles decreases significantly with increasing particle size. Full article
(This article belongs to the Special Issue Solid Fuels – Analysis, Burning and Emissions)
Show Figures

Figure 1

21 pages, 19615 KiB  
Article
Fire Hazard Analysis on Different Fire Source Locations in Multi-Segment Converging Tunnel with Structural Beams
Fire 2023, 6(11), 444; https://doi.org/10.3390/fire6110444 - 18 Nov 2023
Viewed by 1372
Abstract
To investigate the fire risk in a complex tunnel with varying cross-sections, sloped structures, and dense upper cover beams, this study considered four fire source positions: the immersed tube section, confluence section, highway auxiliary road section, and four-lane sections of the main line. [...] Read more.
To investigate the fire risk in a complex tunnel with varying cross-sections, sloped structures, and dense upper cover beams, this study considered four fire source positions: the immersed tube section, confluence section, highway auxiliary road section, and four-lane sections of the main line. It also considered four beam spacings: 1 m, 1.8 m, 3.6 m, and 7.2 m. The Fire Dynamics Simulation Software FDS was utilized to create a comprehensive tunnel model. The analysis focused on temperature and visibility changes at a 2 m height under a 20 MW fire condition for different fire source positions. These changes were then compared with critical danger values to assess the safety of evacuating personnel within the tunnel. Subsequently, this study proposed corresponding emergency rescue strategies. The findings indicated that when the beam grid spacing exceeded 3.6 m, the upper dense beam gap showed a robust smoke storage capacity, leading to a reduced distance of high-temperature smoke spread. However, this increased smoke storage disrupted the stability of the smoke layer, resulting in a heightened smoke thickness. The location of the ventilation vent at the entrance of the immersed tunnel section caused a non-uniform ventilation flow under the girder, deflecting the smoke front towards the unventilated side and decreasing visibility in the road auxiliary area. In comparison to scenarios without a beam lattice, the presence of a beam lattice in the tunnel amplified fire hazards. When the beam lattice spacing was 3.6 m or greater, the extent of the hazardous environment, which is unfavorable for personnel evacuation, expanded. With the exception of the scenario where the fire source was located in the highway auxiliary roadway, all other conditions surpassed 150 m, which is roughly one-third of the tunnel length. Consequently, more targeted strategies are necessary for effective evacuation and rescue efforts. Full article
(This article belongs to the Special Issue Advance in Tunnel Fire Research)
Show Figures

Figure 1

11 pages, 7163 KiB  
Article
Assessing the Fire-Modified Meteorology of the Grassland and Forest Intersection Zone in Mongolia Using the WRF-Fire Model
Fire 2023, 6(11), 443; https://doi.org/10.3390/fire6110443 - 18 Nov 2023
Viewed by 1506
Abstract
Climate change is already significantly affecting the frequency of wildfires in most regions of the world, and the risk of wildfires is expected to amplify further with global warming. Accordingly, there is growing concern about the mechanisms and impacts of extreme fires. In [...] Read more.
Climate change is already significantly affecting the frequency of wildfires in most regions of the world, and the risk of wildfires is expected to amplify further with global warming. Accordingly, there is growing concern about the mechanisms and impacts of extreme fires. In this study, a coupling of the Weather Research and Forecasting model and the Rothermel Fire model (WRF-Fire) is employed to reproduce the spread of fire within the national boundary of inner Mongolia from 21 to 27 May 2009. Simulations were run with or without feedback from fire-to-atmosphere models, and the study focused on how the energy flux of simulated fires changes the local meteorological environment. The coupled simulation could reproduce the burned area well, and the wind speed was the dominant factor in the fire spread, with a maximum value no more than 6.4 m/s, when the terrain height changes little and the proportion of grassland is low. After the feedback, the propagation speed of the fire accelerated, accompanying the release of latent and sensible heat, and local circulation formed near the front of the fire, leading to a convergence and divergence zone in the downwind area. It is worth noting that during a period of more than 140 h of simulation, the area of the fire field increased by 17% from ignition time. Therefore, considering the fire–atmosphere interaction is necessary for accurately predicting fire behavior. Full article
(This article belongs to the Special Issue Vegetation Fires and Biomass Burning in Asia)
Show Figures

Figure 1

21 pages, 4881 KiB  
Article
Methods of Extinguishing Fires in Objects with High Voltage
Fire 2023, 6(11), 442; https://doi.org/10.3390/fire6110442 - 18 Nov 2023
Viewed by 1548
Abstract
In this study, based on a real fire in an object intended to produce electricity, the method of fire extinguishing by fire protection units with components of the Integrated Rescue System was characterised. The goal was to examine the effectiveness of extinguishing the [...] Read more.
In this study, based on a real fire in an object intended to produce electricity, the method of fire extinguishing by fire protection units with components of the Integrated Rescue System was characterised. The goal was to examine the effectiveness of extinguishing the mentioned type of fire in cooperation with other components of the Integrated Rescue System and the effectiveness of the intervention, where the priority task was the rescue of people from a fire-endangered building with forces and resources deployed in the vicinity of the fire. In the study, the time factor of the arrival of individual components, material and technical equipment, and security was also considered and, based on calculations, the possibilities of the starting units to extinguish the fire and ensure the evacuation of people in the building. Subsequently, after evaluating and examining all possibilities, conclusions were chosen and determined from the results at the place of the intervention and recommendations were defined for future fires in similar objects. Full article
Show Figures

Figure 1

51 pages, 15309 KiB  
Review
Recent Advances and Emerging Directions in Fire Detection Systems Based on Machine Learning Algorithms
Fire 2023, 6(11), 441; https://doi.org/10.3390/fire6110441 - 17 Nov 2023
Cited by 1 | Viewed by 2115
Abstract
Fire detection is a critical safety issue due to the major and irreversible consequences of fire, from economic prejudices to loss of life. It is therefore of utmost importance to design reliable, automated systems that can issue early alarms. The objective of this [...] Read more.
Fire detection is a critical safety issue due to the major and irreversible consequences of fire, from economic prejudices to loss of life. It is therefore of utmost importance to design reliable, automated systems that can issue early alarms. The objective of this review is to present the state of the art in the area of fire detection, prevention and propagation modeling with machine learning algorithms. In order to understand how an artificial intelligence application penetrates an area of fire detection, a quantitative scientometric analysis was first performed. A literature search process was conducted on the SCOPUS database using terms and Boolean expressions related to fire detection techniques and machine learning areas. A number of 2332 documents were returned upon the bibliometric analysis. Fourteen datasets used in the training of deep learning models were examined, discussing critically the quality parameters, such as the dataset volume, class imbalance, and sample diversity. A separate discussion was dedicated to identifying issues that require further research in order to provide further insights, and faster and more accurate models.. The literature survey identified the main issues the current research should address: class imbalance in datasets, misclassification, and datasets currently used in model training. Recent advances in deep learning models such as transfer learning and (vision) transformers were discussed. Full article
(This article belongs to the Special Issue Intelligent Fire Protection)
Show Figures

Figure 1

18 pages, 5324 KiB  
Article
Shoot Flammability Patterns in Native and Exotic Street Tree Species at the Wildland–Urban Interface of Eastern Australia
Fire 2023, 6(11), 440; https://doi.org/10.3390/fire6110440 - 17 Nov 2023
Viewed by 1270
Abstract
Street trees provide ecosystem services such as heat mitigation, improved community well-being, and biodiversity conservation. At the wildland–urban interface (WUI), high-flammability street trees also provide a conflicting ecosystem disservice, heightening risks of wildfire spread into urban areas. We addressed this service–disservice conflict by [...] Read more.
Street trees provide ecosystem services such as heat mitigation, improved community well-being, and biodiversity conservation. At the wildland–urban interface (WUI), high-flammability street trees also provide a conflicting ecosystem disservice, heightening risks of wildfire spread into urban areas. We addressed this service–disservice conflict by assessing shoot flammability patterns in 10 street tree species, to identify low-flammability species that can potentially mitigate wildfire risks at the WUI. We found significant differences among species in flammability attributes including time-to-flame (TTF), flame duration (FD), number of flaming events (nF), and flame temperature (FT), and identified low-flammability species for each attribute. Overall, species’ rankings from least to most flammable differed considerably across the four attributes. For example, native water gum (Tristaniopsis laurina) had the slowest TTF, but had the longest FD. Among nine shoot traits, we found that high leafing intensity was the most frequent trait correlated with flammability. In particular, high leafing intensity was significantly related to fast TTF and high FT. Lack of coordination among flammability attributes suggests that, in general, selection of low-flammability street tree species should consider how each flammability attribute differentially contributes to wildfire spread risk. Nonetheless, native Tuckeroo (Cupaniopsis anacardioides) emerged as a potential candidate for further exploration as a low-flammability street tree as it had comparatively long TTF, short FD, and low nF. We found no consistent evidence that exotic species were less flammable than native species, and suggest that native trees be the focus of further research to identify low-flammability street trees. Full article
Show Figures

Figure 1

17 pages, 3952 KiB  
Article
Fire and Rescue Services Reconfiguration for Better Dealing with Post-Flashover Building Fires
Fire 2023, 6(11), 439; https://doi.org/10.3390/fire6110439 - 16 Nov 2023
Viewed by 1201
Abstract
The reconfiguration of fire and rescue services is the focus of this research. The main purpose is to propose an alternative organizational model for better dealing with post-flashover building fires. The primary source of empirical information is a survey involving 267 managers from [...] Read more.
The reconfiguration of fire and rescue services is the focus of this research. The main purpose is to propose an alternative organizational model for better dealing with post-flashover building fires. The primary source of empirical information is a survey involving 267 managers from the Bulgarian fire and rescue services to gather insights. The research methodology meticulously encompasses the identification of changes concerning the efficiency and effectiveness of the fire and rescue services, the discernment of inherent challenges, the definition of specific factors and criteria relevant to their activities, and the determination of strategic priorities. The goal is to suggest a new, more efficient way to organize these services in Bulgaria, whose approach can be applicable to other contexts in similar conditions as well. The proposed model suggests that the Bulgarian fire and rescue services should work independently from the Ministry of Interior as the State Agency under the Council of Ministers. In addition, a comparison between this newly proposed model and the current one is conducted to highlight its potential advantages. Full article
(This article belongs to the Special Issue Compartment Fire and Safety)
Show Figures

Figure 1

20 pages, 28376 KiB  
Article
The Destructive Sir Ivan Fire in New South Wales, Australia; Simulations Using a Coupled Fire—Atmosphere Model
Fire 2023, 6(11), 438; https://doi.org/10.3390/fire6110438 - 15 Nov 2023
Viewed by 1262
Abstract
The destructive Sir Ivan Dougherty fire burned 55,000 hectares around 250 km northwest of Sydney in New South Wales on 12 February 2017. Record hot temperatures were recorded in the area during the lead-in days and the fire conditions at the time were [...] Read more.
The destructive Sir Ivan Dougherty fire burned 55,000 hectares around 250 km northwest of Sydney in New South Wales on 12 February 2017. Record hot temperatures were recorded in the area during the lead-in days and the fire conditions at the time were described as the ‘worst ever seen in NSW’. The observed weather conditions were hot, dry and very windy ahead of a synoptic frontal wind change during the afternoon. ‘Extreme’ to ‘catastrophic’ fire weather was predicted, and the potential for extreme fire behaviour was identified several days in advance. The Australian coupled fire–atmosphere model ACCESS-Fire has been run to explore the characteristics of the Sir Ivan fire. Several features resulting from fire–atmosphere interaction are produced in the simulations. Simulated heat flux along the fire perimeter shows increased intensity on the northern fire flank in response to gradual backing winds ahead of the main frontal wind change. Temporal and spatial variability in fire activity, seen as pulses in fire intensity and fireline wind speed, develop in response to boundary layer rolls in the wind fields. Deep moist convection consistent with the observed pyrocumulonimbus (pyroCb) cloud is simulated over the fire at around the time of the frontal wind change, and matches guidance from the ‘PyroCb Firepower Threshold’ tool, which showed transient favourable conditions. After the wind change, short-lived near-surface and elevated vortices suggest organised rotating features on the northern flank of the fire. The coupled model captures processes that cannot be produced in uncoupled fire predictions and that are not captured in current operational meteorological forecast products provided to Australian fire agencies. This paper links the features from coupled simulations to available observations and suggests pathways to embed the learnings in operational practice. Full article
(This article belongs to the Section Fire Science Models, Remote Sensing, and Data)
Show Figures

Figure 1

15 pages, 17486 KiB  
Article
Denoising of Images for Temperature and Chemiluminescence Measurements of Premixed Flames Applying the Abel Transform
Fire 2023, 6(11), 437; https://doi.org/10.3390/fire6110437 - 15 Nov 2023
Viewed by 1249
Abstract
The temperature field and chemiluminescence measurements of axisymmetric flame are obtained simultaneously in only one image. Digital Laser Speckle Displacement measures temperature fields, and direct image flame determines chemiluminescence values. Applying the Abel transform of axisymmetric objects for volume visualization requires smooth intensity [...] Read more.
The temperature field and chemiluminescence measurements of axisymmetric flame are obtained simultaneously in only one image. Digital Laser Speckle Displacement measures temperature fields, and direct image flame determines chemiluminescence values. Applying the Abel transform of axisymmetric objects for volume visualization requires smooth intensity profiles. Due to the nature of the experimental setup, direct image flame is corrupted with speckle noise and a crosstalk effect. These undesirable effects deteriorate the measurement results. Then, experimental data need crosstalk correction and speckle noise reduction to improve the measurements. This work aims to implement a methodology to reduce the speckle noise of highly noisy data intensity profiles to create smooth profiles appropriate to applying the Abel transform. The method uses a Four-Order Partial Differential Equation to reduce speckle noise and a Curve fitting utilizing a set of Gaussian functions to decrease residual undesirable effects. After this, correction of crosstalk is necessary to avoid this effect. The methodology is applied to premixed flames generated with Liquid Petroleum Gas for different mixes. Full article
(This article belongs to the Special Issue Premixed and Non-premixed Flame Propagation and Suppression)
Show Figures

Figure 1

16 pages, 4295 KiB  
Article
Study on the Influence of Ventilation Speed on Smoke and Temperature Characteristics of Complex Underground Spaces
Fire 2023, 6(11), 436; https://doi.org/10.3390/fire6110436 - 13 Nov 2023
Cited by 3 | Viewed by 1281
Abstract
This study explores the intricate behaviors of smoke flow, temperature distribution, carbon monoxide (CO) levels, and visibility dynamics within complex underground spaces during fire incidents. A key revelation is the profound impact of ventilation speed, with the identification of a critical range between [...] Read more.
This study explores the intricate behaviors of smoke flow, temperature distribution, carbon monoxide (CO) levels, and visibility dynamics within complex underground spaces during fire incidents. A key revelation is the profound impact of ventilation speed, with the identification of a critical range between 2 and 3 m/s that consistently proves to be instrumental in curbing smoke-related hazards and ensuring the safe evacuation of personnel. Furthermore, this paper underscores the influence of accelerated longitudinal winds on temperature profiles, particularly under high HRR conditions, underscoring the importance of accounting for wind effects in comprehensive fire response strategies. Regarding CO concentration, which is a critical safety concern, this study demonstrates that higher ventilation speeds effectively reduce hazardous gas levels, thereby fortifying overall safety measures. The visibility is analyzed, with the findings indicating that elevated ventilation speeds enhance visibility, albeit with considerations about potential drawbacks on personnel evacuation due to excessive wind speed. In conclusion, this paper offers a comprehensive understanding of the pivotal role played by ventilation speed in underground space safety by encompassing smoke control and temperature management. Full article
Show Figures

Figure 1

12 pages, 2813 KiB  
Article
Shock Tube Study of Ignition Delay Times for Hydrogen–Oxygen Mixtures
Fire 2023, 6(11), 435; https://doi.org/10.3390/fire6110435 - 11 Nov 2023
Viewed by 1244
Abstract
This paper presents the results of measurements of ignition delay times in hydrogen–oxygen mixtures highly diluted with argon. The experiments were carried out behind an incident shock wave at temperatures from 870 to 2500 K, pressures from 0.5 to 1.5 atm, and equivalence [...] Read more.
This paper presents the results of measurements of ignition delay times in hydrogen–oxygen mixtures highly diluted with argon. The experiments were carried out behind an incident shock wave at temperatures from 870 to 2500 K, pressures from 0.5 to 1.5 atm, and equivalence ratios from 0.1 to 2.0. The results obtained were processed in terms of the partial pressure of the combustible mixture stoichiometric part that is consumed in the combustion process. An almost linear dependence of the ignition delay time on the reciprocal value of the partial pressure was found for both rich and lean mixtures. The measured data are compared with calculations based on the previously developed kinetic model and experimental data from other authors. Full article
(This article belongs to the Special Issue State-of-the-Art on Hydrogen Combustion)
Show Figures

Figure 1

19 pages, 6709 KiB  
Article
Numerical Investigation of the Effects of Diffusion Time on the Mechanisms of Transition from a Turbulent Jet Flame to Detonation in a H2-Air Mixture
Fire 2023, 6(11), 434; https://doi.org/10.3390/fire6110434 - 10 Nov 2023
Viewed by 1126
Abstract
The current study primarily aimed to simulate detonation initiation via turbulent jet flame acceleration in partial-premixed H2-air mixtures. Different vertical concentration gradients were generated by varying the duration of hydrogen injection (diffusion time) within an enclosed channel filled with air. H [...] Read more.
The current study primarily aimed to simulate detonation initiation via turbulent jet flame acceleration in partial-premixed H2-air mixtures. Different vertical concentration gradients were generated by varying the duration of hydrogen injection (diffusion time) within an enclosed channel filled with air. H2-air mixtures with average hydrogen concentrations of 22.5% (lean mixture) and 30% (near stoichiometric mixture) were investigated at diffusion times of 3, 5, and 60 s. Numerical results show that the vertical concentration gradient significantly influences the early stage of flame acceleration (FA). In the stratified lean mixture, detonation began at all the diffusion times, and comparing the flame-speed graphs showed that a decrease in the diffusion time and an increase in the mixture inhomogeneity speeded up the flame propagation and the jet flame-to-detonation transition occurrence in the channel. In the stratified H2-air mixture with an average hydrogen concentration of 30%, the transition from a turbulent jet flame to detonation occurred in all the cases, and the mixture inhomogeneity weakened the FA and delayed the detonation initiation. Full article
(This article belongs to the Special Issue Hydrogen Safety: Challenges and Opportunities)
Show Figures

Figure 1

12 pages, 5341 KiB  
Article
Research on the Fire Extinguishing Efficiency of Low-Pressure Water Mist in Urban Underground Utility Tunnel Cable Fires
Fire 2023, 6(11), 433; https://doi.org/10.3390/fire6110433 - 10 Nov 2023
Viewed by 1338
Abstract
Low-pressure water mist fire extinguishing systems are a cost-effective and highly reliable option for fire protection. However, they have not yet seen widespread use in urban underground utility tunnels. To validate the fire extinguishing effectiveness of the system in cable fires within urban [...] Read more.
Low-pressure water mist fire extinguishing systems are a cost-effective and highly reliable option for fire protection. However, they have not yet seen widespread use in urban underground utility tunnels. To validate the fire extinguishing effectiveness of the system in cable fires within urban utility tunnels and to identify the key factors influencing its efficiency, a scaled-down test platform for low-pressure water mist fire extinguishing in utility tunnels was constructed, and a series of fire extinguishing tests was conducted. The test results demonstrate that low-pressure water mist can rapidly and effectively extinguish cable fires in utility tunnels, with the quickest fire extinguishing time of 7 s. Within 50 s of activating the system, the internal temperature of the tunnel can be reduced from 650 °C to 40 °C. Among the influencing factors, the pressure and nozzle flow coefficient have a significant impact on the fire extinguishing efficiency, while nozzle spacing has a relatively smaller effect. Thus, when the nozzle spacing meets the requirement of “no dead zones”, priority should be given to increasing the pressure and nozzle flow coefficient. Full article
Show Figures

Figure 1

14 pages, 2313 KiB  
Article
Optimal Ventilation Design for Flammable Gas Leaking from Gas Box Used in Semiconductor Manufacturing: Case Study on Korean Semiconductor Industry
Fire 2023, 6(11), 432; https://doi.org/10.3390/fire6110432 - 09 Nov 2023
Cited by 1 | Viewed by 1344
Abstract
Highly flammable substances such as hydrogen and silane are used in the semiconductor manufacturing process. When gas leaks, it is mixed with outside air and connected to a treatment facility through the duct inside the gas box. This study investigated optimal exhaust design [...] Read more.
Highly flammable substances such as hydrogen and silane are used in the semiconductor manufacturing process. When gas leaks, it is mixed with outside air and connected to a treatment facility through the duct inside the gas box. This study investigated optimal exhaust design to prevent fire explosions and health problems by optimizing the exhaust volume when hydrogen leaks from the gas box of semiconductor manufacturing equipment. After selecting the leakage rate amount based on the KS C IEC 60079-10-1, SEMI S6-0707E, and SEMI F-15 standards, a gas box was manufactured. Subsequently, the fan speed required to ventilate the gas box more than five times per minute according to the SEMI standard and the opening area and location that can reduce the lower explosive limit (LEL) to less than 25% in the event of hydrogen leakage were determined. When the air intakes were placed on the left and right, the flow rate was measured at 32 L per minute (LPM), and the maximum concentration was measured at 9111 ppm. This is less than 25% of the LEL of hydrogen and is believed to be capable of preventing fire and explosion, even if a similarly flammable gas leaks inside the gas box. Full article
Show Figures

Figure 1

15 pages, 2348 KiB  
Article
Research on the Fire Hazard of Different Cables Based on Cone Calorimetry
Fire 2023, 6(11), 431; https://doi.org/10.3390/fire6110431 - 09 Nov 2023
Viewed by 1206
Abstract
In recent years, due to the extensive application and inherent fire hazard of cable materials, the combustion characteristics of frequently used cables, including electrical cables, wires, optical fibers, and network cables have been studied based on ISO 5660 cone calorimetry. The fire hazard [...] Read more.
In recent years, due to the extensive application and inherent fire hazard of cable materials, the combustion characteristics of frequently used cables, including electrical cables, wires, optical fibers, and network cables have been studied based on ISO 5660 cone calorimetry. The fire hazard associated with these cables under different radiation intensities was explored in this study, with parameters such as time to ignition (TTI), heat release rate per unit area (HRRPUA), peak heat release rate (PHRR), total heat release (THR), and mass loss rate (MLR) being investigated for each cable type. Based on an experimental analysis, the risk of fire for all four cable types was augmented by an increase in the external radiation intensity, with electrical cables considered as posing the greatest risk. Regarding smoke toxicity, the lowest risk of smoke toxicity was demonstrated by the network cable, with an FED (fractional effective dose) of 0.0203, followed by optical fibers, with an FED of 0.0507; electrical wires, with an FED of 0.0417; and electrical cables, with an FED of 0.0501. Notably, no significant distinctions were exhibited by the other three cable types, and the smoke toxicity of all four cables did not reach lethal concentration levels in humans. Consequently, considering both thermal hazard and smoke toxicity, it became evident that electrical cables posed the greatest overall fire hazard. Full article
(This article belongs to the Special Issue Cable and Electrical Fires)
Show Figures

Figure 1

19 pages, 3521 KiB  
Article
Empirical Modelling of Stem Cambium Heating Caused by Prescribed Burning in Mediterranean Pine Forest
Fire 2023, 6(11), 430; https://doi.org/10.3390/fire6110430 - 09 Nov 2023
Cited by 1 | Viewed by 1360
Abstract
Little is known about the interactions between the variables involved in the post-fire response of Mediterranean pine species to prescribed burning (PB). Thus, it is essential to develop an empirical model in order to assess the influence of tree and stand attributes, burn [...] Read more.
Little is known about the interactions between the variables involved in the post-fire response of Mediterranean pine species to prescribed burning (PB). Thus, it is essential to develop an empirical model in order to assess the influence of tree and stand attributes, burn season, and fire severity on the probability of stem cambium damage occurring. Prescribed burnings were conducted in different seasons and areas covering a wide climatic and ecological range. Potential explanatory variables were measured. A random effects hurdle model framework was used to evaluate the temperature duration above 60 °C as a proxy for stem cambium damage at tree scale. The results showed significant differences in cambium damage between the PB seasons. Pinus nigra was more resistant than other pine species. Bark thickness was critical for protecting cambium. Volume of crown scorch, percentage of stem scorch, and maximum outer bark temperature were directly related to temperature duration above 60 °C in the cambium. Prescribed burning conducted under tree canopy in Mediterranean pine species generally results in a low level of cambium damage. Empirical models could help managers to predict the effects of PB and thus select the most suitable prescriptions. Full article
Show Figures

Figure 1

15 pages, 4103 KiB  
Article
A Study of the Degradation Mechanism of Ladder-like Polyhedral Oligomeric Silsesquioxane via Fourier Transform Infrared Spectroscopy
Fire 2023, 6(11), 429; https://doi.org/10.3390/fire6110429 - 09 Nov 2023
Viewed by 1232
Abstract
As a result of global warming, fire outbreaks are becoming a common occurrence. There is, therefore, the need for an effective, low-cost and environmentally friendly fire-retardant material. Amine-terminated polyhedral oligomeric silsesquioxane, ATL-POSS, is a low-cost, water-soluble, fire-retardant material based on aminosilane coupling agents. [...] Read more.
As a result of global warming, fire outbreaks are becoming a common occurrence. There is, therefore, the need for an effective, low-cost and environmentally friendly fire-retardant material. Amine-terminated polyhedral oligomeric silsesquioxane, ATL-POSS, is a low-cost, water-soluble, fire-retardant material based on aminosilane coupling agents. Because of its solubility in water, it can serve as a general-purpose fire retardant. The ATL-POSS nanoparticles reported in this paper have high char retentions of about 75 and 54% in nitrogen and air atmospheres, respectively. Differential scanning calorimetry (DSC) was used to determine the phase transition temperatures. It was shown that ATL-POSS is an amorphous material. The thermal stability and rate of decomposition of POSS was determined by using thermogravimetric analysis (TGA). The TGA derivative curves (DTA) show that the degradation of ladder-like POSS occurred in multiple stages and that the rate of degradation is affected by the heating rate. The mechanism of decomposition of ATL-POSS was determined by using Fourier transform infrared spectroscopy, FTIR. The FTIR technique was chosen for this study because of its accessibility and ability to distinguish ladder-like POSS from the cage-type POSS structures. The FTIR spectra showed that the -Si-O-Si- cyclic structure was the predominant structure of POSS. By analyzing the FTIR spectra of the thermally treated POSS residues, obtained at the specified test temperatures, the detailed degradation mechanism of POSS was inferred. It was shown that the terminal silanol group was degraded at test temperatures below 400 °C. Silica was shown to be the final product of the pyrolysis of POSS. The presence of the FTIR transmission peaks at 1000 and 1100 cm−1, due to asymmetric vertical and horizontal stretching vibrations of the Si-O-Si, respectively, was the key evidence used to infer the ladder-like structure of POSS. Full article
(This article belongs to the Special Issue Recent Developments in Flame Retardant Materials)
Show Figures

Figure 1

18 pages, 3165 KiB  
Article
Harnessing Natural Disturbances: A Nature-Based Solution for Restoring and Adapting Dry Forests in the Western USA to Climate Change
Fire 2023, 6(11), 428; https://doi.org/10.3390/fire6110428 - 09 Nov 2023
Viewed by 1821
Abstract
Natural disturbances (wildfires, droughts, beetle outbreaks) shaped temperate forests for millennia, including dry forests of the western USA. Could they now best restore and adapt dry forests to climate change while protecting nearby communities? Mechanical fuel-reduction treatments (e.g., thinning) reduce landscape heterogeneity and [...] Read more.
Natural disturbances (wildfires, droughts, beetle outbreaks) shaped temperate forests for millennia, including dry forests of the western USA. Could they now best restore and adapt dry forests to climate change while protecting nearby communities? Mechanical fuel-reduction treatments (e.g., thinning) reduce landscape heterogeneity and appear ineffective since <1% of the treated area encounters fire each year and fires are still increasing. We propose and analyze a nature-based solution (NbS), using natural disturbances, to see whether it is feasible, how long it might take, and whether it could more effectively restore and adapt dry forests to climate change. We compared 2010–2019 disturbance rates on ~16 million ha of federal dry forests with historical data. We evaluated how much adaptation is achieved by comparing how trees are selected by treatments and disturbances. We found an NbS, which works with natural disturbances and prioritizes community protection, is feasible in western USA dry forests since disturbances are occurring mostly within historical rates. Natural disturbances, unlike mechanical treatments, select survivors that are more likely to be genetically adapted to survive future disturbances and climate change, while perpetuating ecosystem services. Natural disturbances also could ecologically restore forest heterogeneity, better maintain carbon storage, and reduce management needs. A fully developed disturbance-based NbS could more effectively adapt dry forests to climate change within ~30–40 years if active management is reprioritized to protect the built environment and communities near public forests. Full article
(This article belongs to the Special Issue Nature-Based Solutions to Extreme Wildfires)
Show Figures

Figure 1

24 pages, 12068 KiB  
Article
Geostatistical Modeling of Wildfire Occurrence Probability: The Case Study of Monte Catillo Natural Reserve in Italy
Fire 2023, 6(11), 427; https://doi.org/10.3390/fire6110427 - 08 Nov 2023
Viewed by 1359
Abstract
The increasing incidence of wildfires in the Mediterranean region has raised significant scientific and environmental concerns. This study focuses on a retrospective analysis of wildfire ignition and propagation within the context of the Monte Catillo Natural Reserve in Italy. After conducting a comprehensive [...] Read more.
The increasing incidence of wildfires in the Mediterranean region has raised significant scientific and environmental concerns. This study focuses on a retrospective analysis of wildfire ignition and propagation within the context of the Monte Catillo Natural Reserve in Italy. After conducting a comprehensive review of the current state-of-the-art wildfire susceptibility mapping, propagation modeling, probability assessment, forest vulnerability models, and preventive silvicultural measures, we examine the regulatory framework surrounding wildfires in the national context, with a specific focus on prevention, prediction, and active firefighting measures. A geostatistical model of wildfire occurrence was developed, starting with the characterization of the area vegetation and anthropogenic factors influencing wildfire ignition. After that, wildfire observations from the period between 2010 and 2021 were included. The objective is to generate a wildfire hazard map for two distinct vegetation communities. To accomplish this, a statistical analysis was applied using the Poisson Model, assessing its goodness-of-fit by comparing observed frequencies with experimental data through the chi-square test. In conclusion, this model serves as a valuable tool for characterizing wildfire hazards, including ignition probabilities and propagation scenarios, within the Monte Catillo Natural Reserve. The research significantly contributes to enhancing our understanding of wildfire dynamics and plays a crucial role in the development of effective strategies for wildfire risk management. Full article
(This article belongs to the Special Issue Spatial Statistics and Operational Research for Wildfires Management)
Show Figures

Figure 1

15 pages, 12438 KiB  
Article
Updated Land Use and Land Cover Information Improves Biomass Burning Emission Estimates
Fire 2023, 6(11), 426; https://doi.org/10.3390/fire6110426 - 07 Nov 2023
Cited by 1 | Viewed by 1258
Abstract
Biomass burning (BB) emissions negatively impact the biosphere and human lives. Orbital remote sensing and modelling are used to estimate BB emissions on regional to global scales, but these estimates are subject to errors related to the parameters, data, and methods available. For [...] Read more.
Biomass burning (BB) emissions negatively impact the biosphere and human lives. Orbital remote sensing and modelling are used to estimate BB emissions on regional to global scales, but these estimates are subject to errors related to the parameters, data, and methods available. For example, emission factors (mass emitted by species during BB per mass of dry matter burned) are based on land use and land cover (LULC) classifications that vary considerably across products. In this work, we evaluate how BB emissions vary in the PREP-CHEM-SRC emission estimator tool (version 1.8.3) when it is run with original LULC data from MDC12Q1 (collection 5.1) and newer LULC data from MapBiomas (collection 6.0). We compare the results using both datasets in the Brazilian Amazon and Cerrado biomes during the 2002–2020 time series. A major reallocation of emissions occurs within Brazil when using the MapBiomas product, with emissions decreasing by 788 Gg (−1.91% year−1) in the Amazon and emissions increasing by 371 Gg (2.44% year−1) in the Cerrado. The differences identified are mostly associated with the better capture of the deforestation process in the Amazon and forest formations in Northern Cerrado with the MapBiomas product, as emissions in forest-related LULCs decreased by 5260 Gg in the Amazon biome and increased by 1676 Gg in the Cerrado biome. This is an important improvement to PREP-CHEM-SRC, which could be considered the tool to build South America’s official BB emission inventory and to provide a basis for setting emission reduction targets and assessing the effectiveness of mitigation strategies. Full article
(This article belongs to the Special Issue Biomass-Burning)
Show Figures

Figure 1

12 pages, 2464 KiB  
Article
Combustion Performance of Various Polylactic Acid Plastics with Different Porous Structures Constructed by 3D Printing
Fire 2023, 6(11), 425; https://doi.org/10.3390/fire6110425 - 07 Nov 2023
Cited by 1 | Viewed by 1274
Abstract
Polylactic acid (PLA) has intrigued widespread attention as a biodegradable and environmentally friendly polymer, and recent research has revealed that the use of porous PLA in heat sinks for thermal management materials offers promising development potential. However, the heat transfer performance is closely [...] Read more.
Polylactic acid (PLA) has intrigued widespread attention as a biodegradable and environmentally friendly polymer, and recent research has revealed that the use of porous PLA in heat sinks for thermal management materials offers promising development potential. However, the heat transfer performance is closely related to its structure theoretically, whether it is virgin, and how the pore structure affects its heat transfer. Therefore, a novel approach is proposed to address this issue by preparing porous PLA through 3D printing at low complexity and cost, the combustion performance is employed to evaluate the heat transfer indirectly, and the higher burning speed represents higher efficient heat transfer. A new framework is developed to investigate combustion performance and three series of PLA with different pore structures in pore shape, size, and interval are studied by combining experimental tests, respectively. It demonstrates that adjusting the pore structure of PLA significantly alters its combustion performance, evidenced by significant variations in flame growth index, which are 83% better for the 2 mm holes than the largest holes and 71% better for the 2 mm interval than for the sparsest pore structure. Generally, it provides some experimental basis for designing porous thermal management materials; the various pore structures generate different combustion performances, corresponding to various heat transfer. Full article
Show Figures

Figure 1

23 pages, 2448 KiB  
Systematic Review
How Does Fire Suppression Alter the Wildfire Regime? A Systematic Review
Fire 2023, 6(11), 424; https://doi.org/10.3390/fire6110424 - 06 Nov 2023
Viewed by 1889
Abstract
Fire suppression has become a fundamental approach for shaping contemporary wildfire regimes. However, a growing body of research suggests that aggressive fire suppression can increase high-intensity wildfires, creating the wildfire paradox. Whether the strategy always triggers the paradox remains a topic of ongoing [...] Read more.
Fire suppression has become a fundamental approach for shaping contemporary wildfire regimes. However, a growing body of research suggests that aggressive fire suppression can increase high-intensity wildfires, creating the wildfire paradox. Whether the strategy always triggers the paradox remains a topic of ongoing debate. The role of fire suppression in altering wildfire regimes in diverse socio-ecological systems and associated research designs demands a deeper understanding. To reconcile these controversies and synthesize the existing knowledge, a systematic review has been conducted to screen 974 studies on the relationship between fire suppression and wildfire regimes. The rigorous screening process led to the selection of 37 studies that met our stringent criteria for inclusion. The selected literature was quantitatively analyzed in terms of study areas, study design and methods, and the impact of fire suppression on wildfire regimes. Several critical findings were revealed: 1. Numerous studies have focused on northern mid- and high-latitude biomes, neglecting tropical savannas where wildfires are frequent and intense. Further exploration in these regions is imperative. 2. Existing studies have predominantly employed methods such as difference analysis, regression analysis, and scenario simulations. Appropriate methods could be selected based on the study area, data availability, and understanding of fire regimes. 3. Despite the consensus that fire suppression reduces the total burned area, the emergence of the wildfire paradox remains controversial, with approximately equal amounts of the literature supporting and contradicting the wildfire paradox. A noteworthy pattern was observed: the wildfire paradox is more likely to occur in fuel-limited systems, specific vegetation types, and smaller scale and longer term studies. This systematic review highlights that the occurrence of the wildfire paradox is intricately tied to ecosystem feedback mechanisms for suppression and the research scale adopted. It is necessary to incorporate a comprehensive and multi-scale assessment of how local wildlands respond to suppression into wildfire management policy-making processes. This assessment will ensure a more informed and effective wildfire management strategy adapted to local conditions. Full article
Show Figures

Figure 1

20 pages, 13762 KiB  
Article
Fire Regimes of Utah: The Past as Prologue
Fire 2023, 6(11), 423; https://doi.org/10.3390/fire6110423 - 06 Nov 2023
Viewed by 11554
Abstract
(1) Background: Satellite monitoring of fire effects is widespread, but often satellite-derived values are considered without respect to the characteristic severity of fires in different vegetation types or fire areas. Particularly in regions with discontinuous vegetation or narrowly distributed vegetation types, such as [...] Read more.
(1) Background: Satellite monitoring of fire effects is widespread, but often satellite-derived values are considered without respect to the characteristic severity of fires in different vegetation types or fire areas. Particularly in regions with discontinuous vegetation or narrowly distributed vegetation types, such as the state of Utah, USA, specific characterization of satellite-derived fire sensitivity by vegetation and fire size may improve both pre-fire and post-fire management activities. (2) Methods: We analyzed the 775 medium-sized (40 ha ≤ area < 400 ha) and 697 large (≥400 ha) wildfires that occurred in Utah from 1984 to 2022 and assessed burn severity for all vegetation types using the differenced Normalized Burn Ratio. (3) Results: Between 1984–2021, Utah annually experienced an average of 38 fires ≥ 40 ha that burned an annual average of 58,242 ha with a median dNBR of 165. Fire was heavily influenced by sagebrush and shrubland vegetation types, as these constituted 50.2% (17% SD) of area burned, a proportion which was relatively consistent (18% to 79% yr−1). Medium-sized fires had higher mean severity than large fires in non-forested vegetation types, but forested vegetation types showed the reverse. Between 1985 and 2021, the total area burned in fires ≥ 40 ha in Utah became more concentrated in a smaller number of large fires. (4) Conclusions: In Utah, characteristic fire severity differs both among vegetation types and fire sizes. Fire activity in the recent past may serve as an informative baseline for future fire, although the long period of fire suppression in the 20th century suggests that future fire may be more active. Fire managers planning prescribed fires < 400 ha in forests may find the data from medium-sized fires more indicative of expected behavior than statewide averages or vegetation type averages, both of which are weighted to large fires. Full article
Show Figures

Figure 1

15 pages, 3637 KiB  
Article
Experimental Study on Pedestrian Behaviors during Fire Emergency Conditions with Minecraft: Case Studies in a Classroom
Fire 2023, 6(11), 422; https://doi.org/10.3390/fire6110422 - 06 Nov 2023
Viewed by 1462
Abstract
The comprehension of the fire evacuation process is crucial for developing effective evacuation management strategies to enhance pedestrian safety. In this study, we construct a classroom with internal obstacles forming intersecting pathways in Minecraft, and conduct a series of virtual evacuation experiments involving [...] Read more.
The comprehension of the fire evacuation process is crucial for developing effective evacuation management strategies to enhance pedestrian safety. In this study, we construct a classroom with internal obstacles forming intersecting pathways in Minecraft, and conduct a series of virtual evacuation experiments involving multiple pedestrians to investigate the pedestrian behaviors. Case studies in a single-exit classroom demonstrated that normal obstacles and fire in the main evacuation path prompt pedestrians to detour, and pedestrians exhibit fire-avoidance behavior in advance during fire emergency. In the two-exit classroom experiments, normal obstacles have a limited effect on the exit choices of pedestrians, as they primarily choose the nearest exit. Pedestrians positioned in the center of classroom are influenced by their initial orientations, and some pedestrians opt for exits in their initial facing directions. The presence of fire has a greater influence on pedestrians’ exit choices, with most opting for exits away from the fire. Furthermore, during fire emergencies, some pedestrians engage in risk-taking behavior by choosing higher-risk paths in pursuit of a faster evacuation. These adventurous pedestrians proactively plan routes that maximize their distance from the fire and exhibit orderly queuing behavior. These findings are helpful to reveal pedestrian behaviors during fire emergencies. Full article
(This article belongs to the Special Issue Ensuring Safety against Fires in Overcrowded Urban Areas)
Show Figures

Figure 1

31 pages, 2607 KiB  
Review
Bushfire Management Strategies: Current Practice, Technological Advancement and Challenges
Fire 2023, 6(11), 421; https://doi.org/10.3390/fire6110421 - 03 Nov 2023
Viewed by 1796
Abstract
Bushfires are classified as catastrophic disasters capable of inflicting significant destruction. The key detrimental consequences of bushfires include the loss of human lives, trauma within communities, economic losses and environmental damage. For example, the estimated economic loss from the September 2019 to March [...] Read more.
Bushfires are classified as catastrophic disasters capable of inflicting significant destruction. The key detrimental consequences of bushfires include the loss of human lives, trauma within communities, economic losses and environmental damage. For example, the estimated economic loss from the September 2019 to March 2020 bushfires in New South Wales (Australia) was about AUD 110 billion, including more than 3000 burned houses. There has been a notable increase in both the frequency and intensity of bushfires, as clearly demonstrated by recent bushfire events. Bushfires are an intricate phenomenon that transpires across various spatial and temporal scales. Further, the changing circumstances of landscapes, vegetation patterns, weather conditions and ecosystems account for the complexity. Therefore, continual attention is essential for the development of bushfire management strategies. In this context, this paper undertakes a comprehensive literature review of bushfire management strategies, encompassing aspects such as bushfire prediction, detection, suppression and prevention. Based on the review, a bushfire management framework is proposed that can eliminate or successfully mitigate the consequences of bushfires. Further, the paper delves into the domains of fire weather conditions, the initiation of bushfires and the adverse consequences stemming from these fires. Both terrestrial and aerial remote sensing methods have proven to be effective in predicting and detecting bushfires. Nevertheless, a simple unique solution cannot be proposed for bushfire management. Changing weather conditions, topography and the geographic mix of asset types need to be considered when deciding on bushfire management strategies and their breadth and depth of application. Full article
(This article belongs to the Special Issue Recent Developments in Flame Retardant Materials)
Show Figures

Figure 1

22 pages, 6790 KiB  
Article
Thermal Characteristics of Epoxy Fire-Retardant Coatings under Different Fire Regimes
Fire 2023, 6(11), 420; https://doi.org/10.3390/fire6110420 - 02 Nov 2023
Viewed by 1516
Abstract
Different systems of fire protection coatings are used to protect the metal structures of stories and trestles at oil and gas facilities from low (when filling cryogenic liquids) and high temperatures (in case of the possible development of a hydrocarbon fire regime). This [...] Read more.
Different systems of fire protection coatings are used to protect the metal structures of stories and trestles at oil and gas facilities from low (when filling cryogenic liquids) and high temperatures (in case of the possible development of a hydrocarbon fire regime). This paper presents the results of experiments of fireproof coatings on an epoxy binder after the simulation of a liquefied hydrocarbons spill and subsequent development of a hydrocarbon fire regime at the object of protection and exposure of structures to a standard fire regime. According to the experimental results, the temperatures on the samples at the end of the cryogenic exposure were determined and the time from the beginning of the thermal exposure to the limit state of the samples at a hydrocarbon and standard temperature fire regime was determined. As a result, temperature–time curves in the hydrocarbon and standard fire regimes were obtained, showing good convergence with the simulation results. The solution of the inverse task of heat conduction using finite element modeling made it possible to determine the thermophysical properties of the formed foam coke at the end of the fire tests of steel structures with intumescent coatings. It was determined that an average of 12 mm of intumescent coating thickness is required to achieve a fire protection efficiency of 120 min and for the expected impact of the hydrocarbon fire regime, the coating consumption should be increased by 1.5–2 times compared to the coating consumption for the standard regime. Full article
Show Figures

Figure 1

30 pages, 8655 KiB  
Article
Optimizing Drone-Based Surface Models for Prescribed Fire Monitoring
Fire 2023, 6(11), 419; https://doi.org/10.3390/fire6110419 - 02 Nov 2023
Viewed by 1410
Abstract
Prescribed burning and pyric herbivory play pivotal roles in mitigating wildfire risks, underscoring the imperative of consistent biomass monitoring for assessing fuel load reductions. Drone-derived surface models promise uninterrupted biomass surveillance but require complex photogrammetric processing. In a Mediterranean mountain shrubland burning experiment, [...] Read more.
Prescribed burning and pyric herbivory play pivotal roles in mitigating wildfire risks, underscoring the imperative of consistent biomass monitoring for assessing fuel load reductions. Drone-derived surface models promise uninterrupted biomass surveillance but require complex photogrammetric processing. In a Mediterranean mountain shrubland burning experiment, we refined a Structure from Motion (SfM) and Multi-View Stereopsis (MVS) workflow to diminish biases in 3D modeling and RGB drone imagery-based surface reconstructions. Given the multitude of SfM-MVS processing alternatives, stringent quality oversight becomes paramount. We executed the following steps: (i) calculated Root Mean Square Error (RMSE) between Global Navigation Satellite System (GNSS) checkpoints to assess SfM sparse cloud optimization during georeferencing; (ii) evaluated elevation accuracy by comparing the Mean Absolute Error (MAE) of six surface and thirty terrain clouds against GNSS readings and known box dimensions; and (iii) complemented a dense cloud quality assessment with density metrics. Balancing overall accuracy and density, we selected surface and terrain cloud versions for high-resolution (2 cm pixel size) and accurate (DSM, MAE = 57 mm; DTM, MAE = 48 mm) Digital Elevation Model (DEM) generation. These DEMs, along with exceptional height and volume models (height, MAE = 12 mm; volume, MAE = 909.20 cm3) segmented by reference box true surface area, substantially contribute to burn impact assessment and vegetation monitoring in fire management systems. Full article
(This article belongs to the Special Issue Drone Applications Supporting Fire Management)
Show Figures

Figure 1

20 pages, 11597 KiB  
Article
Desert/Forest Fire Detection Using Machine/Deep Learning Techniques
Fire 2023, 6(11), 418; https://doi.org/10.3390/fire6110418 - 29 Oct 2023
Viewed by 1564
Abstract
As climate change and human activity increase the likelihood of devastating wildfires, the need for early fire detection methods is inevitable. Although, it has been shown that deep learning and artificial intelligence can offer a solution to this problem, there is still a [...] Read more.
As climate change and human activity increase the likelihood of devastating wildfires, the need for early fire detection methods is inevitable. Although, it has been shown that deep learning and artificial intelligence can offer a solution to this problem, there is still a lot of room for improvement. In this research, two new deep learning approaches to fire detection are developed and investigated utilizing pre-trained ResNet-50 and Xception for feature extraction with a detailed comparison against support vector machine (SVM), ResNet-50, Xception, and MobileViT architectures. Each architecture was tuned utilizing hyperparameter searches and trials to seek ideal combinations for performance. To address the under-representation of desert features in the current fire detection datasets, we have created a new dataset. This novel dataset, Utah Desert Fire, was created using controlled fires and aerial imaging with a DJI Mini 3 Pro drone. The proposed modified ResNet-50 architecture achieved the best performance on the Utah Desert Fire dataset, reaching 100% detection accuracy. To further compare the proposed methods, the popular forest fire detection dataset, DeepFire, was deployed with resulting performance analyzed against most recent literature. Here, our proposed modified Xception model outperformed latest publications attaining 99.221% accuracy. The performance of the proposed solutions show an increase in classification accuracy which can be leveraged for the identification of both desert and forest fires. Full article
Show Figures

Figure 1

18 pages, 4870 KiB  
Article
Reconstruction Method of 3D Turbulent Flames by Background-Oriented Schlieren Tomography and Analysis of Time Asynchrony
Fire 2023, 6(11), 417; https://doi.org/10.3390/fire6110417 - 27 Oct 2023
Viewed by 1241
Abstract
Background-oriented Schlieren tomography (BOST) is widely used for 3D reconstruction of turbulent flames. Two major concerns are associated with 3D reconstruction. One is the time asynchrony within the data acquisition of the high-speed camera. The other is that the ray tracing process requires [...] Read more.
Background-oriented Schlieren tomography (BOST) is widely used for 3D reconstruction of turbulent flames. Two major concerns are associated with 3D reconstruction. One is the time asynchrony within the data acquisition of the high-speed camera. The other is that the ray tracing process requires significant computational consumption. This study proposes a ray tracing optimization method based on the k-d tree. The study results show that the average search nodes for each ray are only 0.018% of 3D flame with 3.07 million grid nodes. In addition, a parameter estimation method of the unknown azimuth power spectrum function is proposed. First, a typical Sandia turbulent jet diffusion flame dataset was built and validated accordingly, with experiments. The algorithm’s applicability to the 3D reconstruction of temperature and density fields is discussed on this basis. The root-mean-square error (RMSE) of the cross-section density for 3D reconstruction is below 0.1 kg/m3. In addition, the RMSE of the cross-section temperature is below 270 K. Finally, an uncertainty analysis of the flame reconstruction based on a physical model is performed by optimizing the ray tracing method. For the time asynchronous variance of 1 ms, the density uncertainty of the 3D reconstruction is below 1.6 × 10−2 kg/m3, and the temperature uncertainty is below 70 K. The method can provide an essential basis for the design of BOST systems and the 3D reconstruction of turbulent flames. Full article
(This article belongs to the Special Issue Sooting Flame Diagnostics and Modeling)
Show Figures

Figure 1

14 pages, 5542 KiB  
Article
The Incorporation of Ladle Furnace Slag in Fire Insulating Gypsum-Based Materials
Fire 2023, 6(11), 416; https://doi.org/10.3390/fire6110416 - 27 Oct 2023
Viewed by 1198
Abstract
Ladle slag, a byproduct of steel manufacturing, exhibits inherent reactivity and undergoes hydration when exposed to water. Nevertheless, these reaction byproducts often remain metastable, leading to microstructural alterations when incorporated into cementitious materials, thereby limiting the recycling potential of ladle slag. This study [...] Read more.
Ladle slag, a byproduct of steel manufacturing, exhibits inherent reactivity and undergoes hydration when exposed to water. Nevertheless, these reaction byproducts often remain metastable, leading to microstructural alterations when incorporated into cementitious materials, thereby limiting the recycling potential of ladle slag. This study explores the fire insulating capacity and the physical, mechanical, and leaching characteristics of gypsum-based materials with substantial quantities of ladle slag in instead of gypsum. The mechanical strength of the specimens declines as the ladle slag content increases. Nevertheless, the percentage decrease in compressive strength at various temperatures (300 °C, 500 °C, and 700 °C) is less pronounced when higher amounts of ladle slag are used. Fire-resistant properties, assessed using the EN 1363-1 standards, diminish with increasing slag proportions; although the inclusion of ladle slag introduces certain endothermic processes that positively affect the fire insulating capacity, resulting in a 20% reduction when 60%wt of slag is employed. Notably, no gas emissions were observed during the fire test, indicating the absence of environmental hazards. In conclusion, ladle slag does not pose a leaching threat to the environment, making it a viable and sustainable alternative to gypsum in gypsum-based materials. Full article
(This article belongs to the Special Issue Recent Developments in Flame Retardant Materials)
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop