This thesis provides an interpretation about how wildland firefighters can experience risk by relations of trust. The author shows that the risk taking and wildland firefighting literatures inadequately account for how trust underpins self-construction processes among people who participate in risky activities. To supplement the literatures within these terms, the author uses interview data and personal stories about managing wildland fire to propose a general trajectory of being and becoming a wildland firefighter that details the significance of trust in self-construction processes. The author argues that in the process of being and becoming a wildland firefighter, risk is sometimes increased, decreased, concealed, revealed, and anticipatorily transformed through trust. The author provides a framework for viewing risk that can be used to understand danger to the self. / Graduate

With over 10,000 acres burned in wildland fires in 2014 in Mississippi, accurate fire hazard prediction is of great importance. Soil moisture, fuel moisture, and fire hazard are inextricably linked. Remote estimation of soil moisture in the Southeastern United States for fire hazard modeling is hampered by the use of models engineered for other physiographic regions and the prevalence of deep, fast-draining sands underneath heavy vegetation. United States Geologic Service hydrographs were investigated and compared to nearby soil moisture and precipitation readings in an attempt to identify the links between stream gauge readings and watershed soil moisture. Stream gauge peaks corresponded within a three day window of soil moisture peaks 73.3% of the time, with 43.8% of peaks occurring simultaneously, thus verifying the indicative nature of local hydrographs. With further study, this easily accessed proxy variable could enhance currently used soil moisture models and drought indices.

Current field models for wildfire prediction are mostly based on dry or low-moisture fuel combustion research. To better study live fuel combustion behavior and develop the current semi-empirical bush combustion model, a laminar flow flat-flame burner was used to provide a convection heating source to ignite individual live fuel samples. In this research project, four Utah species were studied: Gambel oak (Quercus gambelii), canyon maple (Acer grandidentatum), big sagebrush (Artemisia tridentata) and Utah juniper (Juniperus osteosperma). Leaf geometrical parameters and time-dependent combustion behavior were recorded. Qualitative results included various combustion phenomena like bursting, brand formation and bending. Quantitative results included determination of best correlations for (a) leaf geometrical properties (individual leaf dry mass (mdry), thickness (Δx), leaf width (W) and leaf length (L)) and (b) combustion characteristics (e.g., time to ignition (tig), time of flame duration (tfd), time to maximum flame height (tfh), time to burnout (tbrn), and maximum flame height (hf,max)). A semi-empirical bush model was expanded to describe the combustion behavior of the three Utah species (Gambel oak, canyon maple and Utah juniper). Leaf placement and bush structure were determined from the statistical model. A new flame area simulation was explored in the semi-empirical bush model in order to improve the bush burning predictions.

With the continued rise in wildfires in California, and around the world, technological advancements are needed to improve the safety and effectiveness of wildland firefighters. One area that provides an opportunity for such development is the deployment of temporary communications networks. Currently, radio repeaters are set up on mountain tops in the response area; such repeaters do not provide flexibility once installed, still have blind spots, and require the time of valuable assets like helicopters to install. This thesis will establish the feasibility of airborne radio repeaters for wildland firefighting. In order to successfully demonstrate the feasibility of such an airborne system, the resulting system should be rapidly deployable, improve communications range and reliability, and be compatible with existing regulations and guidelines. The design process for the repeater payload is described, as well as important troubleshooting steps. The resulting product is then compared to the initial requirements through testing and observation. Although audio filtering provided by off-the-shelf handheld radios prevented the repeater from functioning as intended, the proposed 2m/70cm dual-band digital communications relay was capable of being carried by the Altavian Nova and was able to successfully demonstrate the feasibility of such a system. As such it will be an important contribution to communications needed for fighting future wildfires.

The current uses of unmanned aerial vehicles (UAVs) in wildland firefighting center around mapping, scouting, and firing operations. These operations and additional operations are often held back by lack of range and lift capacity of current UAV options. Software design tools were developed in this research to aid in designing a UAV for wildland firefighting. The tools help create a mission profile, estimate the mass of the UAV, select a motor and rotor, select a battery, and generate and analyze a finite element (FE) sector model. These tools leverage parametric analysis and studying existing hardware to create a design. The FE model is generated based on the mission profile, a motor and rotor, and battery as design parameters and a set of design variables. The tools developed for creating a mission profile, estimating mass, selecting a motor and rotor, and selecting a battery successfully aid the preliminary design of an octocopter, hexacopter, and quadcopter. The FE tool was designed around an octocopter's geometry, which leads to complications in generating FE models for a hexacopter or quadcopter. Recommendations were made for altering the FE tool to account for hexacopters and quadcopters. Other recommendations were made to support future work in creating an optimized design of a wildland firefighting UAV. / Master of Science / The use of multirotor UAVs in various industries is rapidly expanding. One industry that currently uses UAVs but is limited in their capabilities is wildland firefighting. Wildland firefighters use UAVs for scouting, mapping, and firing operations. Scouting includes finding road access to the fire, finding water sources, searching for spot fires, and many other applications. Mapping is typically done to understand the size of the fire. Firing operations are conducted to start small, controlled fires to remove fuel from the fires path. However, these operations as well as future applications of UAVs are often limited by the flight time and the lifting capabilities current UAV options offer. Tools were developed in this research to create a preliminary design of a UAV for wildland firefighting. The design parameters and variables of the UAV design are outlined throughout the tools. The tools allow for compiling mission requirements, selecting motors/rotors and a battery to use in the UAV, and a preliminary structural analysis of the UAV design. The preliminary structural analysis includes extracting stresses, strains, and displacements experienced through a simplified mission as well as the natural frequencies of the finite element sector model. The design of octocopters, hexacopters, and quadcopters were explored using the set of design tools. The tools were successfully in selecting components for each style of UAV and at the preliminary structural analysis of the octocopter design. However, the structural analysis was not able to be conducted for the hexacopter and quadcopter design due to geometric conditions in the finite element model.

No description available.

Historical land use and changes in climate have altered fire behavior and severity in fire-prone ecosystems of western North America. A variety of fuels treatments are used to abate fire hazard, restore ecosystem processes, and increase forest resilience. Mechanical fuels treatments are increasingly used to alter forest structure and fuel continuity due to impediments to the use of prescribed fire. An increasingly common fuels treatment is mechanical mastication. Mastication does not remove fuels, but instead rearranges live and dead vertical woody fuels into a compacted layer on the forest floor. While mastication reduces potential fire intensity, these compacted fuels are flammable and capable of causing tree mortality and other negative ecological consequences when they burn in prescribed fires or wildfires. A current knowledge gap is quantitative information about the rate at which masticated fuels decompose and the rate at which vegetation reestablishes within sites previously masticated. Using 25 sites across northern California and southern Oregon, this thesis examines how masticated fuels change over time. Results from this study demonstrate that the majority of mass lost from masticated fuel beds occurred in the 1 and 10-hour woody fuel classes. Because surface fire behavior is driven by these fine fuels, these findings are valuable to the planning and retreatment of masticated fuels treatments and the corresponding fire suppression efforts in masticated sites. In combination with masticated wood surface fuels, shrubs and small trees play an important role in fire behavior, acting as ladder fuels that exacerbate surface fire behavior and threaten to ignite residual trees. A lack of understanding of how woody vegetation recovers following masticated fuel treatments gives rise to questions and challenges regarding treatment longevity. In this study, species with the ability to resprout tended to recover more quickly than obligate seeding species. Residual conifer saplings or trees that establish in masticated fuelbeds also recovered rapidly, reducing the efficacy of fuels treatments. Future implementation of masticated fuels treatments should consider both woody fuel decomposition and the corresponding recovery of shrubs and small trees to maximize treatment longevity. / Master of Science

Fire dynamics is a complex process involving multi-mode heat transfer, reacting fluid flow, and the reaction of combustible materials. High-fidelity predictions of fire behavior using computational fluid dynamics (CFD) models come at a significant computational cost where simulation times are often measured in hours, days, or even weeks. A new simulation method is to use a machine learning approach which uses artificial neural networks (ANNs) to represent underlying connections between data to make predictions of new inputs. The field of image analysis has seen significant advancements in ANN performance by using feature based layers in the network architecture. Inspired by these advancements, a generalized procedure to design ANNs to make spatially resolved predictions in multi-physics applications is presented and applied to different fire applications. A deep convolutional inverse graphics network (DCIGN) was developed to predict the two-dimensional spatially resolved spread of a wildland fire. The network uses an image stack corresponding to the spatially resolved landscape, weather, and current fire perimeter (which can be obtained from measurements) to predict the fire perimeter six hours in the future. A transpose convolutional neural network (TCNN) was developed to predict the spatially resolved thermal flow field in a compartment fire from coarse zone fire model predictions. The network uses thirty-five parameters describing the geometry of the room and the ventilation conditions to predict the full-field temperature and velocity throughout the room. The data for use in training and testing both networks was generated using high-fidelity CFD fire simulations. Overall, the ANN predictions in each network agree with simulation predictions for validation scenarios. The computational time to evaluate the ANNs is 10,000x faster than the high-fidelity fire simulations. This work represents a first step in developing super real-time full-field fire predictions for different applications. / Ph. D. / The National Fire Protection Agency estimates the total cost of fire in the United States at $300 billion annually. In 2017 alone, there were 3,400 civilian fire fatalities, 14,670 civilian fire injuries, and an estimated $23 billion direct property loss in the United States. Large scale fires in the wildland urban interface (WUI) and in large buildings still represent a significant hazard to life, property, and the environment. Researchers and fire safety engineers often use computer simulations to predict the behavior of a fire to assist in reducing the hazard of fire. Unfortunately, typical simulations of fire scenarios may take hours, days, or even weeks to run which limits their use to small areas or sections of buildings. A new method is to use a machine learning approach which uses artificial neural networks (ANNs) to represent underlying connections between data to make new predictions of fire behavior. Inspired by advancements in the field of image processing, this research developed a procedure to use machine learning to make rapid high resolution predictions of fire behavior. An ANN was developed to predict the perimeter of a wildland fire six hours in the future based on a set of images corresponding to the landscape, weather, and current fire perimeter, all of which can be obtained directly from measurements (US Geological Survey, Automated Surface Observation System, and satellites). In addition, an ANN was developed to predict high-resolution temperature and velocity fields within a floor of a building based on predictions from a coarse model. The data for use in training and testing these networks was generated using high-resolution fire simulations. Overall, the network predictions agree well with simulation predictions for new scenarios. In addition, the time to run the model is 10,000x faster than the typical simulations. The work presented herein represents a first step in developing high resolution computer simulations for different fire scenarios that run very quickly.

Any rere any milions d'hectàrees són destruïdes pels incendis forestals, no només a Europa sinó arreu del món, tan sols cal recordar els dramàtics episodis viscuts a Califòrnia i Austràlia recentment. A banda de l'evident impacte mediambiental que això provoca -emissió de gasos d'efecte hivernacle, pèrdua de biodiversitat, acceleració de l'erosió del sòl, etc.- els incendis són també un problema social de primer ordre, que posa en perill a les persones i els seus béns. Davant d'aquesta situació, en les darreres dècades s'ha impulsat fortament la recerca en l'àmbit dels incendis forestals. Tanmateix, l'estudi dels incendis forestals és certament complex per les condicions i l'entorn on aquests es desenvolupen, a banda també del gran nombre de fenòmens -físics, químics i socials- que interaccionen al llarg de diferents escales espacials i temporals, per a donar lloc a l'inici i propagació del foc. És per això que bona part de la recerca sobre el comportament dels incendis forestals ha tingut lloc bàsicament al laboratori, tot i que qüestions com ara com traslladar aquests resultats experimentals als incendis reals, o bé fins a quin punt aquest tipus d'experimentació és útil o què és el que realment es pot extrapolar i què no, no han tingut encara cap resposta clara.L'objectiu d'aquesta tesi ha estat doncs el de contribuir a l'estudi del canvi d'escala en l'experimentació en incendis forestals pel què fa al comportament del foc, mitjançant les tècniques de l'anàlisi dimensional i de semblança. En primer lloc s'ha realitzat una extensa revisió bibliogràfica centrada bàsicament en aquells treballs que havien aplicat d'alguna manera o altra l'anàlisi dimensional i de semblança a l'estudi dels incendis i en particular dels incendis forestals. S'ha vist que no es possible realitzar un escalatge complet d'aquest fenomen i que el més utilitzat ha estat l'escalatge de Froude. A més s'ha detectat que mai abans s'ha aplicat aquest tipus d'anàlisi als models que s'utilitzen normalment avui dia en l'experimentació de laboratori. A continuació s'ha fet doncs una anàlisi exhaustiva de totes les variables que determinen el comportament d'un incendi forestal en els diferents escenaris experimentals (de laboratori i de camp). A partir d'aquestes variables s'ha realitzat una anàlisi dimensional per a estudiar la propagació d'un front de flames -tan bàsic com en condicions de vent i pendent- així com una anàlisi de semblança que ha permès obtenir les lleis d'escala per a les diferents variables que caracteritzen la propagació d'un incendi forestal. S'ha dissenyat i executat un programa experimental al laboratori amb l'objectiu de validar si es complien les lleis d'escala trobades i de determinar-ne el rang de validesa i les possibles causes en cas que no es complissin.Els resultats obtinguts han mostrat que per a fronts de flama bàsics propagant-se sense vent ni pendent, totes les variables analitzades segueixen les lleis d'escala derivades de l'estudi teòric, en el rang de longituds de front de flama abraçat que va dels 25 cm als 3 m. Nogensmenys cal remarcar que paràmetres com la humitat i el tipus de combustible o les característiques de la instal·lació experimental utilitzada poden alterar enormement els resultats si no es controlen adequadament. En el cas dels fronts de flama propagant pendent amunt, els resultats han mostrat que les lleis d'escala de la geometria de flama es compleixen per a tot el rang de pendents estudiat que va de 0 fins a 30°, mentre que en el cas de la llei d'escala de la velocitat de propagació deixa de complir-se per a pendents de 30°. Finalment, en el cas dels fronts de flama propagant en condicions de vent, els resultats han mostrat que per a velocitats del vent superiors a aproximadament 2,5 m/s les lleis d'escala tant de la velocitat de propagació com de la geometria de flama deixen de complir-se.Al final d'aquest treball s'apunten les causes que poden conduir a l'incompliment de les lleis d'escala així com als factors que poden restar validesa als experiments efectuats a escala de laboratori, quan es vol extrapolar els resultats a escales més grans o fins i tot a incendis reals. / Year after year millions of hectares are destroyed by wildland fires, not only in Europe but all over the world; just remember the dramatic episodes recently occurred in California or Australia. Besides the evident environmental impact caused by these fires -emission of greenhouse gases, biodiversity loss, soil erosion, etc- wildland fires represent also a social problem of primary order that threatens human life and their assets.Because of this situation, during the last decades research on wildland fires has been greatly boosted. Nevertheless, the study of forest fires is really complex due to the conditions and the environment in which they develop and to the number of phenomena -physical, chemical and social- that interact all along the different spatial and temporal scales that give rise to the start and development of a fire. That is partly the reason because the study of wildland fire behaviour has mainly been developed in laboratories, but questions like how these experimental results can be translated to real fires?, or is really this kind of experimentation useful?, or what can be extrapolated? These questions have not yet received a clear answer.The goal of this work was to improve the knowledge on the effect of changing the scale in the experimental study of forest fire behaviour, by means of dimensional and similarity analysis. First an extended bibliographic review has been done, centred on those works that had applied in one or another way the dimensional and similarity analysis to the study of fires and more specifically to forest fires. It was observed that it is not possible to undergo a complete scaling of a forest fire and that the most used partial scaling technique was the Froude scaling. Moreover it was detected that this kind of analysis was never before applied to the laboratory models used currently to obtain experimental data on wildland fires. Thus, an exhaustive analysis of all the variables affecting forest fire behaviour has been carried out for the diverse experimental scenario (in the lab and field). From these variables, a complete dimensional analysis has been developed in order to study the spread of a flames front -both in basic conditions and with slop or wind- and a subsequent similarity analysis has provided the scaling laws governing all the variables under study. A complete experimental program has been designed and developed in the laboratory with the aim of validating the scaling laws previously found and to establish the possible causes of any failure of the laws. The results obtained show that in the case of a basic flame front, spreading under no wind and no slope conditions, all the variables analysed followed the scaling laws obtained during the theoretical study for flames front lengths ranging from 25 cm to 3 m. For the tests under slop conditions, the results indicate that the scaling laws corresponding to the flame geometry are verified for all the slopes tested which range from 0 to 30°, while in the case of the rate of spread scaling law is no longer verified for the 30° slope. Finally, in the case of flame fronts spreading under wind conditions, the results show that for wind speed values greater than 2,5 m/s neither of the scaling laws corresponding to the flame geometry and the rate of spread, are verified. It has also been observed that parameters such as moisture content, the type of fuel or the specific design of the experimental device used can have a big influence on the results obtained if they are not adequately controlled.At the end of this work, the main causes leading to the failure of the scaling laws are pointed out together with the factors that can make the laboratory experiments less reliable when trying to extrapolate the results to larger scales or even to real fires.

The average intensity and frequency of wildland fires have been on the rise over the years, leading to an increase in the risk to homes located in the Wildland-Urban Interface (WUI). Fire suppression is the most used method of wildland fire control, but this suppression can cause wildland fires to become more frequent and devastating. Increased development in the WUI also puts these homes at greater risk. Current methods of passive fire protection are effective, but these methods are expensive, time consuming to set up, and not fully effective. This research proposes a permanent passive fire protection system that is built into the structure. A flame- resistant material would be attached to the sheathing with the roofing and siding attached over the material. This system would allow the easily replaceable exterior components of the structure to burn, and the interior of the structure would be protected. This system protects the structural supports of the building, so the house does not collapse, and the exterior components can be replaced. To test this permanent passive fire protection system 21 small-scale specimens were constructed with five different flame-resistant materials and three different types of siding. The flame-resistant materials include structural wrap, Kaowool, ceramic fiber insulation, Pyrogel, and intumescent paint. The sidings include wood siding, vinyl siding, and hardie board. The testing took place in a burn room to simulate the conditions of a wildland fire. Post-burn charring evaluations and temperature analyses were conducted to determine which type of material and siding were most effective at protecting the small-scale models. The charring evaluation included determining the percent charring of the OSB face of the specimens, and the temperature analysis included determining the percent difference between the internal and external temperatures of the specimens. The performance, cost and installation, constructability, and replaceability of each of the materials were considered in deciding which materials were most effective. Overall, the Pyrogel outperformed the other materials, but this material is by far the most expensive. The ceramic fiber material was overall the second most effective flame-resistant material, and this material could be as effective as the Pyrogel if used in conjunction with the other materials tested. Further testing of material combinations is required to determine if different flame-resistant material combinations could be as effective as the Pyrogel material on its own. The results of this project did prove the feasibility of a permanent passive fire protection system, but further testing of large-scale specimens is required to test the effectiveness of the system in more complex circumstances.