Unmanned Aerial Systems for Wildland and Forest Fires

Wildfires represent an important natural risk causing economic losses, human death and important environmental damage. In recent years, we witness an increase in fire intensity and frequency. Research has been conducted towards the development of dedicated solutions for wildland and forest fire assistance and fighting. Systems were proposed for the remote detection and tracking of fires. These systems have shown improvements in the area of efficient data collection and fire characterization within small scale environments. However, wildfires cover large areas making some of the proposed ground-based systems unsuitable for optimal coverage. To tackle this limitation, Unmanned Aerial Systems (UAS) were proposed. UAS have proven to be useful due to their maneuverability, allowing for the implementation of remote sensing, allocation strategies and task planning. They can provide a low-cost alternative for the prevention, detection and real-time support of firefighting. In this paper we review previous work related to the use of UAS in wildfires. Onboard sensor instruments, fire perception algorithms and coordination strategies are considered. In addition, we present some of the recent frameworks proposing the use of both aerial vehicles and Unmanned Ground Vehicles (UV) for a more efficient wildland firefighting strategy at a larger scale.Comment: A recent published version of this paper is available at: https://doi.org/10.3390/drones501001

NUMERICAL CALCULATIONS OF WATER DROP USING A FIREFIGHTING AIRCRAFT

The study involved a numerical analysis of the water dropping process by fixed-wing aircraft. This method, also known as air attack, is used for aerial firefighting, primarily in green areas such as forests and meadows. The conducted calculations allowed for the analysis of the process over time. The calculations were performed based on a SolidWorks model of the M18B Dromader aircraft. After defining the computational domain and setting the boundary conditions, the simulations were carried out using the ANSYS Fluent software. The resulting water dropping area was used to analyze the intensity of water distribution. The volumetric distribution and airflow velocity distribution were analyzed for specified time steps. The boundary layer where air no longer mixes with water during the final phase of water dropping was also determined. The obtained results provide an important contribution to further analyses aimed at optimizing the water dropping process by fixed-wing aircraft

Efficient Algorithms for Graph-Theoretic and Geometric Problems

This thesis studies several different algorithmic problems in graph theory and in geometry. The applications of the problems studied range from circuit design optimization to fast matrix multiplication. First, we study a graph-theoretical model of the so called ''firefighter problem''. The objective is to save as much as possible of an area by appropriately placing firefighters. We provide both new exact algorithms for the case of general graphs as well as approximation algorithms for the case of planar graphs. Next, we study drawing graphs within a given polygon in the plane. We present asymptotically tight upper and lower bounds for this problem Further, we study the problem of Subgraph Isormorphism, which amounts to decide if an input graph (pattern) is isomorphic to a subgraph of another input graph (host graph). We show several new bounds on the time complexity of detecting small pattern graphs. Among other things, we provide a new framework for detection by testing polynomials for non-identity with zero. Finally, we study the problem of partitioning a 3D histogram into a minimum number of 3D boxes and it's applications to efficient computation of matrix products for positive integer matrices. We provide an efficient approximation algorithm for the partitioning problem and several algorithms for integer matrix multiplication. The multiplication algorithms are explicitly or implicitly based on an interpretation of positive integer matrices as 3D histograms and their partitions

Experimental flow characterization and computational model development of aqueous film-forming foam (ARFF) firefighting jets

Over the past few decades, aircraft rescue firefighting (ARFF) research has made technical strides on multiple fronts. Continuing efforts have helped develop computer-aided engineering tools to quantify risk assessment for a variety of ARFF aspects like aircraft pool fire combustion and dynamic crash-related events. To continue this work, a study was conducted to characterize firefighting agent application behavior and to quantify the flow characteristics that differentiate water and AFFF jets. Progress will lead to further simulation capability including a combined aircraft crash-fire-suppression application risk assessment model. An aqueous firefighting agent application laboratory was specially constructed to carry out experiments on firefighting jets ranging from 1 to 11 megapascals and 4 to 25 liters per minute at AFFF concentration levels ranging from 0 (pure water) to 12 percent by volume. Experimental flow characterization consisted of flow visualization, agent ground pattern distribution analysis, and 2-D phase Doppler particle analysis (PDPA). Flow visualization results depicted minimal differences in terms of overall jet structure between AFFF versus water jets. However, PDPA results showed AFFF enhances jet break-up generating droplet sizes 25 to 100 percent less compared to water jets with AFFF jets lagging water jet velocities by as much as 10 percent in certain instances. Agent ground pattern results confirmed flow performance factors such as ground coverage area, reach, and maximum span all benefit from an increase in nozzle pressure flow rate. An Euler-Lagrange, large eddy simulation computational fluid dynamic (CFD) strategy accounting for droplet collision and break-up was employed to predict firefighting jet flow dynamics with and without the addition of AFFF. AFFF influence was handled computationally via material property variation from pure water in terms of density, viscosity, and surface tension effects. CFD model results were agreeable with flow visualization and phase Doppler data reproducing global trends in both droplet velocity and size data, particularly with respect to the influence of AFFF. However, oversimplified nozzle injection conditions led to greater differences than expected. CFD model result errors were difficult to quantify entirely due to PDPA upper particle size range limitations and complexities associated with direct comparisons to data. High fidelity, near field characterization of AFFF-surface interactions is needed to better understand agent accumulation fluid mechanics with eventual application to fire suppression of aircraft bodies engulfed in fire

From Building Information Modeling to City Information Modeling

With the development of Geographic Information System (GIS), the concept of digital city is implemented widely. However, in practice, most of the GIS models are relatively poorly attributed, semantically. Building Information Modeling (BIM) is a process involving the generation and management of digital representations of physical and functional characteristics of building, which is most used in small scale projects. In order to address the target problem of completing the semantic attribution of 3D digital city model, a framework of integrating BIM technology into GIS is demonstrated. A new concept of city information modeling (CIM) is proposed with the goal of bringing great benefits to the urban construction and city management. The composition of city information model is discussed. The data schema behind BIM and GIS (i.e. IFC and CityGML) are compared and mapped with each other. A case study of land planning of campus is demonstrated to present the potential benefits of CIM

Trajectory and aerodynamic analyses of air launched fire-extinguishing projectiles

Wildfires are a devastating source of human and environmental loss, and the available means to combat them in their early stages can be improved. With the aid of Unmanned Aerial Systems and FEB (Fire-extinguishing balls), wildfires’ early stages might be suppressed while keeping human lives safe and firefighters risk-free. Considering the use of a fixed wing Unmanned Aircraft Vehicle to launch the fire-extinguishing projectile, launching the FEB as it is, without any modification, does not seem to be the best available option, with problems ranging from difficulty in predicting its trajectory to the possible bad impact performance, with the possibility of the FEB rolling away from the target as it lands. Therefore, three other configurations for the projectile with FEB as its basis were studied, all of them utilizing fins for the means of stability. These configurations differed in terms of tail design attached to the FEB: one is a tube, the other a tangential cone, and the other a symmetrical NACA airfoil revolved around its axis. Their aerodynamic static coefficients were obtained through CFD (computational fluid dynamics), while the dynamic ones were obtained through analytical expressions. Using an implemented 6-DOF (degrees of freedom) model, 17 trajectories were studied for each of these configurations. Other analyses were carried out, as the consideration of the influence of wind turbulence, consideration of a fourth configuration with double the area of the fins, and asserting the importance of the consideration of the dynamic coefficients while testing different values for some of these coefficients. Regarding the FEB-projectile configurations, CFD results suggest that the tube configuration has a transient behavior in the tested speeds, and that the tangential cone is a very suitable way of streamlining the FEB in these range of speeds, with no considerable difference to the NACA tail configuration. Trajectory results highlight the importance of considering the mean wind speed and direction, the importance of obtaining an appropriate estimate of the wind turbulence, and the importance of the dynamic coefficients for the full aerodynamic characterization of the projectile, concretely for its stability and attitude results. Ultimately, between the tested configurations, the best candidate is the cone tail configuration, for its simplicity in construction and performance in the trajectories.Os incêndios florestais são uma fonte devastadora de custos humanos e ambientais, e os meios disponíveis para combater as suas fases iniciais poderão ser melhoradas. Com o auxílio de sistemas de aeronaves não-tripuladas e de FEB (bolas extintoras), os incêndios florestais poderão ser extintos nas suas fases iniciais, mantendo vidas humanas livres de risco. Considerando o uso de uma aeronave não tripulada de asa fixa para lançar o projétilextintor, lançar a bola extintora tal como é não aparenta ser a melhor opção, sendo alguns dos problemas relacionados com o seu lançamento a dificuldade em prever a sua trajetória e um possível mau desempenho no impacto, com a possibilidade da bola rolar para longe do seu alvo. Assim, três configurações para o projétil extintor que tem a FEB como base foram estudados, todos eles utilizando empenagens como forma de estabilização. As configurações diferem em termos da cauda acoplada à FEB: uma delas é um tubo, outra um cone tangencial, e outra um perfil NACA simétrico girado em torno do seu eixo. Os coeficientes aerodinâmicos estáticos foram obtidos através de CFD (dinâmica de fluidos computacional), enquanto que os dinâmicos foram obtidos por expressões analíticas. Implementando um modelo de trajetória 6-DOF (6 graus de liberdade) 17 trajetórias foram estudadas para cada uma das configurações. Outras análises foram realizadas, como a relevância na trajetória da turbulência do vento, a consideração de uma quarta configuração com o dobro da área das empenagens, e a determinação da importância dos coeficientes dinâmicos, testando vários valores para alguns dos coeficientes. Em relação às configurações do projétil testadas, os resultados CFD sugerem que a configuração com o tubo possui um comportamento transiente nas velocidades testadas, e que o cone tangencial é uma forma bastante eficaz de tornar a esfera mais aerodinâmica, nesta gama de velocidades não havendo uma diferença considerável entre esta configuração e a configuração com a cauda NACA. Os resultados das trajetórias destacam a importância da consideração da velocidade e orientação do vento médio, a importância de obter uma estimativa apropriada para a turbulência do vento, e a relevância dos coeficientes dinâmicos para a caracterização aerodinâmica completa do projétil, concretamente em relação à estabilização e atitude. Entre as configurações testadas, o melhor candidato é a configuração com cauda em cone, pela sua simplicidade de construção e desempenho nas trajetórias