Firing Line Research Articles

Slope effect on junction fire with two non-symmetric fire fronts

Background In Pedrógão Grande on 17 June 2017, two fire fronts merged and the propagation of the fire was influenced by the interaction of these non-symmetric fire fronts. Aims This wildfire motivated us to study a junction fire with two non-symmetrical fire fronts. The analysis of the movement of the intersection point and the angle (γ) between the bisector of the fire lines and the maximum rate of spread (ROS) direction is of particular relevance. Methods The study was carried out at Forest Fire Laboratory of the University of Coimbra in Lousã (Portugal) with laboratory experiments. Key results We found that, for small rotation angles (δ), the non-dimensional ROS of the intersection point depends on the slope angle (α) and the initial angle between fire fronts. Conclusions For high α, the non-dimensional ROS was highly influenced by the convection process and γ where the maximum ROS occurred, increased when δ increased. However, the radiation process was more relevant for lower α and influenced the non-dimensional ROS. For these cases, the maximum spread direction was close to that of the fire line bisector. Implications The present work aimed to explain fire behaviour during the Pedrógão Grande wildfire.

Simulated behaviour of wildland fire spreading through idealised heterogeneous fuels

Homogeneous vegetation is widely used in wildland fire behaviour models, although real vegetation is heterogeneous in nature and composed of different kinds of fuels and non-combustible parts. Many features of fires can arise from this heterogeneity. For land management and firefighting, creating heterogeneous fuel areas may be useful to reduce fire intensity and rate of spread (ROS), and alter fire geometry. Recently, an empirical model for fire spread in spinifex grasslands was developed and validated against experimental measurements. In this study, physics-based grassland fire behaviour simulations were conducted with varying percentages of fuel cover and alternating square and rectangular patches of burnable and non-burnable material. The environmental conditions and thermophysical properties of the grassland were kept constant throughout the simulation to separate the effects of fuel heterogeneities from other parameters. For three sets of nominal wind velocities, 3, 5.6 and 10 m s−1, we identified ‘go’ and ‘no go’ fires. Reasonable agreement between the non-dimensionalised simulated ROS and observed ROS in spinifex was found. There is a significant reduction of fire intensity, ROS, flame length, fire width and fire line length due to the heterogeneous effect of vegetation.

On the interaction of wind, fire intensity and downslope terrain with implications for building standards in wildfire-prone areas

Background Wildfires can have detrimental impacts on the environment and urban structures when they spread from wildland areas. Aims In this work, a numerical study was performed to investigate the effect of downslope terrain on fire-induced flows in the presence of a building structure. Fires with intensities of 4 and 15 MW m−1 were considered on inclined terrain with downslope angles varying from 0° to −30°, and wind speeds of 6 and 12 m s−1. Methods Simulations were conducted using a large eddy simulation (LES) solver, implemented in the open-source platform FireFOAM. Key results The results were validated with experimental measurements of a full-scale building model. Results show that at a wind velocity of 12 m s−1, structures on steeper downslope terrains are at higher risk of wildfire damage, whereas at a constant wind velocity of 6 m s−1, these structures are at a lower risk. Conclusions The outcomes of the study highlight the physical effect of sloped terrain on buildings downwind of a line fire. Implications The results from this study can be used to evaluate the validity of risk management measures including building standards and asset protection zones and can better inform ways of improving these measures.

Effect of flame zone depth on the correlation of flame length with fireline intensity

Background Previously established correlations of flame length L with fireline intensity IB are based on theory and data which showed that flame zone depth D of a line fire could be neglected if L was much greater than D. Aims We evaluated this correlation for wildland fires where D is typically a non-negligible proportion of L (i.e. roughly L/D < ~2). Methods Experiments were conducted to measure flame length L from line-source fires using a gas burner where IB and D were controlled independently (0.014 ≤ L/D ≤ 13.6). Key results The resulting correlation showed D significantly reduced L for a given IB over the entire range of observations and was in accord with independent data from spreading fires. Flame length is reduced because the horizontal extent of deep flame zones entrains more air for combustion than assumed by theory involving only the vertical flame profile. Conclusions Analysis suggested that the noted variability among published correlations of L with IB may be partly explained by varying L/D ratios typical of wildland fires. Implications Fire behaviour modelling that relies on correlations of L with IB for scaling of heat transfer processes would likely benefit by including the effects of D.

Smart Fire-fighter cum Oil Tank Cleaner Robot

Abstract: Nowadays, fire disasters are one of the most dangerous events that can occur unexpectedly and inflict significant damage. Humans face serious risks on the job such as heat exhaustion, burns, physical and mental stress. Additionally, they frequently come into contact with high levels of carbon monoxide and other toxic hazards. With these dangerous exposures, this line of work presents a likelihood for many diseases. Humans may not be able to react quickly enough when a fire breaks out. So, in order to solve this problem, a smart firefighter could be created. Similarly, oil tank cleaning is an important task which involves potential hazards such as, fires or explosions, toxic gas and vapor releases, oxygen shortages and other physical dangers. It can even cause exposure to radiation, and environmental contamination, among others. Cleaning the inner surfaces of tight facilities used primarily for storing bulk goods or oils, such as silos, receives special care. The build-up substance, the surface material, and the ambient conditions all influence confined space cleaning technologies. This document discusses four cleaning strategies. The proposed study examines firefighting robots and oil tank cleaning robots in order to achieve better results.

The Moving Firefighter Problem

The original formulation of the firefighter problem defines a discrete-time process where a fire starts at a designated subset of the vertices of a graph G. At each subsequent discrete time unit, the fire propagates from each burnt vertex to all of its neighbors unless they are defended by a firefighter that can move between any pair of vertices in a single time unit. Once a vertex is burnt or defended, it remains in that state, and the process terminates when the fire can no longer spread. In this work, we present the moving firefighter problem, which is a generalization of the firefighter problem where the time it takes a firefighter to move from a vertex u to defend vertex v is determined by a function τ. This new formulation models situations such as a wildfire or a flood, where firefighters have to physically move from their current position to the location of an entity they intend to defend. It also incorporates the notion that entities modeled by the vertices are not necessarily instantaneously defended upon the arrival of a firefighter. We present a mixed-integer quadratically constrained program (MIQCP) for the optimization version of the moving firefighter problem that minimizes the number of burnt vertices for the case of general finite graphs, an arbitrary set F⊂V of vertices where the fire breaks out, a single firefighter, and metric time functions τ.

NUMERICAL AND EXPERIMENTAL MODELING OF LOW-CALORIE GAS FUELS COMBUSTION PROCESSES

Methane, which is found in coal seams, has long been seen as an alternative to imported natural gas. Capturing that victorious methane can immediately increase the versatility of the production of footwear, increase the safety of the minds of the workforce, and change the negative impact to dovkillya. And yet, there are low technical and technological folds, which galmuyut the development of the type of bottle and utilization of methane.One of the main directions of extraction of coal mine methane is the generation of thermal energy in boiler houses and other heat generators. However, this type of paliva is unstable in concentration and important, due to the fact that the technical riven has the same characteristics. The current development of technology and technology, in general, allows you to successfully improve the nutrition of methane. There are very few data on environmental and energy indicators for the process of scalding with different palnikov outbuildings.In the coal mines of the Donbass, there is a widespread stagnation of the boiler room with bottom (hollow) toe shoes. Further indications of scalding with different design features of this type of stokers will help to improve nutrition by reducing the chemical insufficiency of scalding gas and increasing the thermal pressure of the boiler. It is shown that the computer simulation and re-verification of the efficiency of coal mine methane scorching in scorching boilers from the stoking of bottom (hollow) stokers is shown to be possible.In the robot, an experimental simulation of the process of burning coal methane in the bottom of the burners of a modernized design was carried out, and tests were carried out on the distribution of medium-mass parameters in the gas at the exit from the fire line from the vicarious grids. And also, an analysis of stationary watering of the average characteristics of the flow fluidity, temperature, concentration of components, nitrogen oxide and nitrogen oxide fluidity was carried out.

Influence of Recycled Glass Ceramic Waste On Physical and Mechanical Properties of Foamed Concrete

Concrete is the most used man-made material and foamed concrete is a type of concrete widely known with high workability, low density and excellent thermal and sound insulation properties. Its global market has also been predicted to increase. Growing of population and economy, along with urbanization generate wastes which increase yearly. One of the solutions to reduce waste in landfills is by using waste in manufacturing. Glass, classed as a form of ceramic waste (GCW) has been left in the landfills unrecycled due to the challenges it causes. The primary purpose of this research is to find the optimal GCW composition as a quartz sand additive for Foamed Concrete-based Glass Ceramic Waste (FC-GCW) which will reduce the amount of unrecycled GCW that ends upin landfills while producing a sustainable product. The samples were prepared by grinding the GCW and mixing varying percentages of GCW (0, 5, 10, 15, 20, 25, and 30%) with a consistent quantity of cement, quartz sand, water, and foam. Physical (density, water absorption, porosity and Energy Dispersive X-ray (EDX)) test and analysis and mechanical (compressive strength) test were performed on the samples. During physical tests, the density increased as the GCW percentage increased, but water absorption andporosity decreased. FC-GCW 20% had appropriate density, water absorption, and porosity values of 0.887 g/cm3, 22.6 %, and 88.9%, respectively, which demonstrated that the material is lightweight and porous.For EDX analysis between FC-GCW control and FC-GCW 20%, it was found that when GCW was included, the weight percentage of Oxygen and Calcium decreased while the weight percentage of Silica increased, showing GCW increased Silica content, and pozzolanic reaction occurred to from Calcium Silicate Hydrate (C-S-H) gel.For mechanical testing, it was discovered that FC-GCW 20% had the highest average compressive strength of 0.94 MPa and 2.01 MPa for 7 and 28 days, respectively. This research's contribution can be applied to areas where low densities are preferred and low compressive strength is required, such as of road sub-base, fire breaks, raising floor level, void fill, harbour fill, bridge abutments and ground stabilization.

Notas para un emplumado amanecer: ojos, pasamontañas y corazones en las lecturas ‘deleuzianas’ de Lemebel

From a critical gender perspective, this article offers an analysis of the chronicle that Pedro Lemebel dedicates to Subcomandante Marcos, paying special attention to the Deleuzian dimensions that it incorporates. Dimensions that are not only present in what could be interpreted as a theoretical wink, but also in the practices -visual, oral, written- with which Lemebel seems to overflow and enrich his philosophical origin. If, in general, within the multiple recreations of becoming that are promoted in his chronicles, Lemebel tends to question the symbolic universe of the new man, the text that consecrates Subcomandante Marcos seems to introduce unusual forms of subversion that question and at the same time confront the local revolutionary imaginary. However, it is not only a matter of destabilizing the binarized discourses of the revolution, but also of making visible other possible forms of disrespect and resistance. And that is what seems to be re-created in the memoirs that, in the context of the Chilean revolt of 2019, have taken Lemebel's name from the line of flight to the front line of fire.

Multi-Objective Scheduling of Fuel Treatments to Implement a Linear Fuel Break Network

We developed and applied a spatial optimization algorithm to prioritize forest and fuel management treatments within a proposed linear fuel break network on a 0.5 million ha Western US national forest. The large fuel break network, combined with the logistics of conducting forest and fuel management, requires that treatments be partitioned into a sequence of discrete projects, individually implemented over the next 10–20 years. The original plan for the network did not consider how linear segments would be packaged into projects and how projects would be prioritized for treatments over time, as the network is constructed. Using our optimization algorithm, we analyzed 13 implementation scenarios where size-constrained projects were prioritized based on predicted wildfire hazard, treatment costs, and harvest revenues. We found that among the scenarios, the predicted net revenue ranged from USD 3495 to USD 6642 ha−1, and that prioritizing the wildfire encounter rate reduced the net revenue and harvested timber. We demonstrate how the tradeoffs could be minimized using a multi-objective optimization approach. We found that the most efficient implementation scale was a sequence of relatively small projects that treated 300 ha ± 10% versus larger projects with a larger treated area. Our study demonstrates a decision support model for multi-objective optimization to implement large fuel break networks such as those being proposed or implemented in many fire-prone regions around the globe.

Iran-Saudi Arabia Rivalry and the Yemen Crisis

Iran’s confrontation with the USA and its allies within the framework of its revolutionary Islamic identity has led many Arab countries, especially Saudi Arabia, to be vigilant. After the 1979 Iranian Revolution, the relations between Iran and Saudi Arabia deteriorated fundamentally, and the ideological and geopolitical struggle between the two countries deepened. This situation not only affected the two countries, but also drew many countries in the region to the firing line. While regional instability has increased in the Middle East, sectarian rivalry and ideological struggle have also escalated. The Arab Spring process, on the other hand, made the Hobbesian anarchic structure among the Middle Eastern states even more evident. In this respect, after the Arab Spring, an axis of tension has emerged between Iran and Saudi Arabia, covering countries such as Yemen, Syria, Lebanon, Iraq and Bahrain. The hottest point of this tension axis has been Yemen. As a matter of fact, the progress of the Zaydi Houthis, known as Shiite, in Yemen was supported by Iran, but was found unacceptable by Saudi Arabia and its allies. Ultimately, Saudi Arabia and its allies started a struggle against the Houthis, which they saw as part of Shiite expansionism. On the other hand, with the aggressive policy of Saudi Arabia towards them, the Houthis have further developed their relations with Iran for pragmatic and ideological reasons. In essence, the Houthis, which emerged as a result of Yemen’s local and social problems, gradually became another denominator in the equation of the Iran-Saudi Arabia rivalry.

Collective Effects of Fire Intensity and Sloped Terrain on Wind-Driven Surface Fire and Its Impact on a Cubic Structure

The combined effects of percent slope and fire intensity of a wind driven line fire on an idealized building has been numerically investigated in this paper. The simulations were done using the large eddy simulation (LES) solver of an open source CFD toolbox called FireFOAM. A set of three fire intensity values representing different heat release rates of grassland fuels on different inclined fuel beds have been modeled to analyze the impact of factors, such as fuel and topography on wind-fire interaction of a built area. An idealized cubic structure representing a simplified building was considered downstream of the fire source. The numerical results have been verified with the aerodynamic measurements of a full-scale building model in the absence of fire effects. There is a fair consistency between the modeled findings and empirical outcomes with maximum error of 18%, which acknowledge the validity and precision of the proposed model. The results show that concurrent increase of fire intensity and terrain slope causes an expansion of the surface temperature of the building which is partially due to the increase of flame tilt angle upslope on the hilly terrains. In addition, increasing fire intensity leads to an increase in the flow velocity, which is associated with the low-pressure area observed behind the fire front. Despite limitations of the experimental results in the area of wind-fire interaction the result of the present work is an attempt to shed light on this very important problem of fire behavior prediction. This article is a primary report on this subject in CFD modeling of the collective effects of fire intensity and sloped terrain on wind driven wildfire and its interaction on buildings.

The Use of Cybernetic Systems Based on Artificial Intelligence as Support for the Decision-Making Process in the Military Field

Abstract In the future, at the strategic, operational, and tactical levels of warfare, replacing human will and human decision with autonomous Artificial Intelligence (AI) weapon systems becomes every day a high possible scenario. These systems are already in use and have the ability to successfully deal with threats faster than humans. Countering AI weapon systems will represent a great challenge in a future war. Both military and commercial robots will in the future incorporate “artificial intelligence” (AI) that could make them capable of performing tasks and missions on their own. In the military context, this gives rise to a debate as to whether such robots should be allowed to carry out missions, especially if there is a possibility that any human life may be in the line of fire. Thus, it can be stated that unconventional knowledge will be required for successfully defeat of such a weapon system.

Location of Photovoltaic Panels in the Building Envelope in Terms of Fire Safety

Abstract The increasing amount of energy consumed by the operation of buildings results in an increasing environmental burden. This has a direct impact on the innovation of renewable energy technology and its application in building industry. In accordance with the requirements of the “Europe 2020 Strategy” and “Europe 2030 Project”, the long-term goal is to achieve the maximum use of renewable energy sources in the buildings´ operation. One of the solutions is the building-integrated photovoltaic power plant. The paper analyses efficiency and incorporation of photovoltaic (PV) systems into the roofs and perimeter walls. PV systems are a renewable energy source used in the construction of zero energy buildings producing minimal environmental pollution. Semi-transparent building-integrated photovoltaics (BIPV) are one of the technologies that have the potential to increase the building´s energy efficiency as well as aesthetically complete the building´s design. The paper deals with material characteristics of PV panels in terms of the fire risk and definition of the fire hazardous area that arises during their combustion. It is focused on the incorporation of various types of PV technology into the facades and roofs, structural and material solutions of fire-dividing structures to which PV systems are fastened considering their location in the fire hazardous area. Based on the external fire simulations, conclusions in this paper bring the optimal position of PV systems in the building envelope in relation to fire open areas, fire lines and fire hazardous areas. The safety of firefighters during the intervention also depends on the position of PV systems. The case study presented in this paper uses a model solution to give the optimal position of PV systems in the building envelope considering the fire safety.

Fire Fighting Robot

Firefighters are generally responsible for putting out fires, but they are frequently exposed to greater dangers when doing so, particularly in hazardous locations such as nuclear power plants, petroleum refineries, and gas tanks. They confront additional challenges, particularly when a fire breaks out in a confined space, since they must investigate the ruins of structures and overcome obstructions in order to extinguish the fire and save the victim. As a result, this study describes the construction of a fire-fighting robot that can put out fires without exposing firefighters to undue danger. The robot is build using sensors, motors, Arduino and pump. These robots are mainly used in industrial areas for where there is high risk of fire. Fire-fighting robots provide greater access into small spaces and to extinguish fire in narrow places.

Advanced Analysis of Collision-Induced Blast Fragmentation in V-Type Firing Pattern

The firing pattern of blastholes influences the geometric aspects of a blast design in terms of change in blasting burden and spacing. This in turn changes the effective stiffness of a blasthole and confinement of the explosive and aids in better fragmentation. However, during the blasting, the fragments tend to collide and further fragment the rock. In comparison with other patterns, the V-type firing pattern increases the chances of collision between the fragments during flight. The process is scantly documented and accordingly field experiments were conducted using three firing patterns, viz., line, diagonal, and V-type, in a mine with minor variation in rock factor and minor to moderate changes in blast design variables. Sixteen blast design variables such as burden, spacing, charge per hole, in-hole charge density, etc. along with firing pattern were considered for the analysis and fragmentation modeled with the help of surface response analysis and artificial neural networks. The analysis revealed that there is a significant influence of firing patterns on fragmentation. The V-type pattern showed significant reduction in fragment sizes that can be ascribed to in-flight collision processes. A surface response model was developed using advanced ANOVA and resulted in an adjusted R2 and RMSE of 0.89, 0.025, respectively. Further, modeling with ANN was attempted that showed better results than ANOVA with R2 and RMSE of 0.96 and 0.040 in training, and 0.884 and 0.049 in validation tests. Since, diagonal and V-type patterns have similar design parameters, the reduction in fragment size in the former pattern can be ascribed to the collision of rock fragments during their flight in blasting.

Numerical and Experimental Investigation on the Effect of Mechanical Smoke Extraction Caused by External Wind in Subway Station Halls

When fires break out in subway station halls, traditional smoke extraction (TSE) systems are employed with the aim of preventing smoke from spreading to the platform and passageways. The functionality of TSE systems under the influence of external winds needs to be further explored. Based on a numerical method, this study investigated the effect on TSE systems under the influence of external wind. A numerical model was established and validated by means of full-scale field tests to ensure accuracy. Subsequently, the validated model was applied to study the effect of the external wind directions and speeds on the smoke diffusion distance. The results showed that when all entrances and exits were on the windward side, the external wind direction led to serious longitudinal diffusion of the smoke toward the side with fewer entrances and exits of the station hall, and the diffusion distance increased with increasing wind speed. The diffusion distance reached a maximum value of 61.32 m when the outdoor wind was 5 m/s, which was 67.9% higher than that under no wind. When all the entrances and exits were on the leeward side, the external wind had little influence on the degree of smoke spread, with the greatest smoke diffusion distance being only 4.76% longer than that under no wind. When two entrances and exits were on the windward side and the other on the leeward side, the external wind caused smoke to spread to a passageway, and the degree of smoke spread was more unfavorable at higher wind speeds, with the longest diffusion distance being 7.28 m. To prevent smoke from spreading to passageways and to effectively shorten the longitudinal diffusion distance of smoke, an optimized smoke control (OSC) system was proposed, employing center and passageway smoke barriers, which were able to shorten the diffusion distances by 35.45%, 13.64%, and 2.35%. In particular, smoke diffusion did not occur in passageways. This study provides a reference for the fire safety engineering design of subway stations.

Plane graphs of diameter two are 2-optimal

Let G be a connected graph with n vertices. Suppose a fire breaks out at some vertex of G. At each time interval, firefighters can protect up to k vertices, and then the fire spreads to all unprotected neighbors. Let dnk(v) denote the minimum number of vertices that the fire may damage when a fire breaks out at vertex v. The k-expected damage of G, denoted by εk(G), is the expectation of the proportion of vertices that can be damaged from the fire, if the starting vertex of the fire is chosen uniformly at random, i.e., εk(G)=∑v∈V(G)dnk(v)/n2. A class of graphs G is called k-optimal if εk(G) tends to 0 as n tends to infinity for any G∈G. In this paper, we prove that planar graphs of diameter two are 2-optimal, which is the best possible.

In the line of fire: Debris throwing by wild octopuses.

Wild Octopus tetricus frequently propel shells, silt, and algae through the water by releasing these materials from their arms while creating a forceful jet from the siphon held under the arm web. These "throws" occur in several contexts at a site in Jervis Bay, Australia, including in interactions with other octopuses. Material thrown in interactive contexts frequently hits other octopuses. Some throws appear to be targeted on other individuals, as suggested by several kinds of evidence: Throws in interactive contexts were more vigorous than others, and more often used silt, rather than shells or algae. High vigor throws were more often accompanied by uniform or dark body patterns than other throws. Some throws were directed differently from beneath the arms and such throws were more likely to hit other octopuses. Throwing at other individuals in the same population, as apparently seen in these octopuses, is a rare form of nonhuman projectile use, previously seen only in some social mammals.

Experimental and analytical study on inclined turbulent fire in still air. Part 1. Line fire

In this paper, an experimental and theoretical analysis is conducted on the behavior of the inclined turbulent line fires under different initial Froude numbers (Fr0) and initial flame angles (θ0). The flame temperature and flow fields are measured, and the flame geometry is extracted from video images. Experimental results show that the curvature of flame trajectory increases with the increase of Fr0 or the decrease of θ0. The axial temperature and flame length decrease as θ0 decreases under the same Fr0, indicating the enhancement of flame entrainment due to the cross stream-buoyancy. A prediction model to describe the flame motion is established by analyzing the mass and momentum equations. The model combined with the kinetic energy equation incorporates the effects of buoyancy and streamline curvature on the flame entrainment. The model predicts the flame trajectory and correlates the flame entrainment coefficient of turbulent line fires under different Fr0 and θ0. Model calculations show that the comprehensive effect of buoyancy and streamline curvature on the flame entrainment increases as Fr0 increases within a certain range or as θ0 decreases, in agreement with the experimental indications. The results of this paper are expected to help understand the flame motion and develop radiative heat transfer models of turbulent line fires.