Quantifying War: From the Battle of Britain to Terrorism

Conflicts are central events in history, defining eras and the lives of their peoples. In this thesis, we demonstrate the use of three quantitative methods to three case studies from historical and conflict modelling. We begin with the application of the bootstrap to the Battle of Britain. The bootstrap allows us to answer counterfactual questions about the Battle of Britain, including the importance of targeting and tactical decisions on the final outcome of the battle. We quantify the final outcome using theoretical prior distributions associated with historical viewpoints. We next conduct a changepoint analysis of historical battle deaths. This requires the adaptation of changepoint analysis methods to heavy-tailed data, for which we formulate an algorithm before applying the algorithm to the case study. We find evidence for changes in the distribution of battle deaths through time. We finish with a case study of coalescence and fragmentation modelling, which has been proposed for insurgent-counter-insurgent conflict. We demonstrate that gel-shatter cycles are a previously unrecognised yet ubiquitous feature of such systems and discuss the robustness of these systems to perturbations in the underlying rules. Together, these case studies demonstrate the ability of modern methods to refine and deepen our understanding of historic conflicts

Development of electrical resistivity imaging methods for geological and archaeological prospecting

Not availabl

Aeroelastic Wing Flutter Testing and Analysis

La integración de nuevas cargas subalares en una aeronave modifica las características de distribución de masa (centro de gravedad) y momento de inercia del ala. Este efecto, sumado a la contribución de las cargas aerodinámicas, produce que los modos y frecuencias propias de vibración varíen con la presión dinámica (función de la velocidad de vuelo y altitud). Este fenómeno fuertemente no lineal implica que, bajo determinadas condiciones de presión dinámica, se produzca el acoplamiento en frecuencia (resonancia autosostenida) de dos o más modos de vibración inicialmente ortogonales entre sí. El fenómeno aeroelástico anterior se conoce como "flameo" ("flutter" en inglés), que salvo cambio de las condiciones de vuelo, llevará a la pérdida de la aeronave y la vida del piloto. Por otra parte, la integración de nuevas cargas subalares requiere llevar a cabo una serie de procesos que conducirán a una nueva envolvente de vuelo, dentro de la cual se garantice que la aeronave puede volar con seguridad. Este estudio requiere llevar a cabo cálculos teóricos para predecir las condiciones de flameo y una posterior validación mediante ensayos en vuelo, conocido como "expandir la envolvente". Ejecutar esta tarea con seguridad requiere unos medios y personal altamente cualificados y especializado, cuyos costes derivados son extraordinariamente elevados. Como consecuencia, las empresas especializadas llevan a cabo estos ensayos y guardan los resultados como secreto industrial. Todo lo anterior justifica que sea muy complicado encontrar métodos validados para procesar datos de vuelos y extraer los parámetros de vibración a distintas presiones dinámicas. Entre los distintos métodos publicados para identificar parámetros de vibración de vuelos de ensayos de flameo, la gran mayoría han sido verificados únicamente con modelos teóricos, dándose el caso de que muchos de ellos dan resultados incongruentes entre sí o que al ser validados con datos reales arrojan resultados incoherentes. Por este motivo, el objetivo principal era desarrollar técnicas robustas, coherentes y repetitivas para procesar datos de vuelo de flameo. El autor del presente estudio ha tenido acceso a una base de datos de ensayos en vuelo de flameo, cortesía del Ejército del Aire de España, y cuenta con autorización de la Oficina de Comunicaciones del Ejército del Aire para publicar resultados de su investigación sobre esos datos. La presente tesis desarrolla dos métodos de procesado de datos de ensayos en vuelo de flameo específicos sobre datos procedentes de una excitación tipo "Sine-Dwell". El primero está basado en un modelo matemático y en técnicas de optimización. El segundo en técnicas de aprendizaje profundo. El desarrollo de ambas técnicas se inicia con una primera verificación de distintas técnicas documentadas en la literatura científica, seguidos por el entrenamiento de las siguientes redes neuronales; De perceptrón multicapa, redes neuronales profundas y redes neuronales convolucionales. Establecida una línea de base de comparación, se procedió a seleccionar una técnica clásica (basada en modelo teórico y optimización), de acuerdo con la fuente bibliográfica, validada con datos reales procedentes de ensayos en vuelo de flameo y una de las redes neuronales entrenadas. Partiendo de las lecciones aprendidas se desarrolló una técnica innovadora basada en el modelo clásico de modelo teórico y optimización, verificación con datos sintéticos y comparación de las tres técnicas seleccionadas anteriormente. Finalmente, las tres técnicas fueron validadas con datos reales de ensayos en vuelo de flameo. Los resultados obtenidos son altamente satisfactorios, alcanzando los objetivos previstos inicialmente. Las técnicas presentadas se han verificado con datos sintéticos, comparadas con modelos bibliográficos previamente validados de forma independiente, y validadas en este estudio con datos reales. Los resultados son coherentes con lo esperado. La velocidad de proceso permite el análisis de los datos en tiempo real, aumentan la consciencia situacional del director de ensayos y facilitan la toma de decisiones para continuar o detener el test, en condiciones de peligro, con mayor seguridad

Bio-Inspired Collective Decision-Making in Game Theoretic Models and Multi-Agent Systems

Collective decision-making can be investigated in a variety of different contexts, from opinion dynamics to swarm robotics. In the context of honeybee swarms, the evolutionary dynamics corresponding to the honeybee consensus problem can be studied via game theoretic tools. Evolutionary game theory provides the necessary tools to capture the relevant aspects for the decision-making process, whereas mean-field game theory serves well as a framework to analyse the optimal response of a large number of interacting players, even in the case of adversarial disturbance, where the aim is to ensure the robustness of the system to worst-case deterministic perturbations. The interactions among players, often originating in the corresponding real system from a social or physical structure, e.g. humans or animals for social and nodes of a power network for physical, can be captured by means of a network. In this thesis, the model originating in the context of bio-inspired collective decision-making is formulated in a game theoretic framework. The study of the corresponding consensus problem is carried out by analysing the stability property of the system and the corresponding optimal strategies in the presence of an adversarial disturbance. A threshold is identified to prevent a situation of deadlock, which happens when the population is stuck in a scenario where no option has predominantly taken over. The analysis is then extended to compartmental models, which share similarities with the original system and gives insight on asymmetric evolutions of the system. Through this link, other relevant applications are considered, such as duopolistic competition in marketing and virus propagation in smart grids. Finally, structured environments are explored as an extension to the original model, and the structure is captured by means of undirected graphs or of the Barabási-Albert scale-free (SF) complex network model

Air Force Institute of Technology Research Report 2011

This report summarizes the research activities of the Air Force Institute of Technology’s Graduate School of Engineering and Management. It describes research interests and faculty expertise; lists student theses/dissertations; identifies research sponsors and contributions; and outlines the procedures for contacting the school. Included in the report are: faculty publications, conference presentations, consultations, and funded research projects. Research was conducted in the areas of Aeronautical and Astronautical Engineering, Electrical Engineering and Electro-Optics, Computer Engineering and Computer Science, Systems and Engineering Management, Operational Sciences, Mathematics, Statistics and Engineering Physics

Optimal Control of Epidemics in the Presence of Heterogeneity

We seek to identify and address how different types of heterogeneity affect the optimal control of epidemic processes in social, biological, and computer networks. Epidemic processes encompass a variety of models of propagation that are based on contact between agents. Assumptions of homogeneity of communication rates, resources, and epidemics themselves in prior literature gloss over the heterogeneities inherent to such networks and lead to the design of sub-optimal control policies. However, the added complexity that comes with a more nuanced view of such networks complicates the generalizing of most prior work and necessitates the use of new analytical methods. We first create a taxonomy of heterogeneity in the spread of epidemics. We then model the evolution of heterogeneous epidemics in the realms of biology and sociology, as well as those arising from practice in the fields of communication networks (e.g., DTN message routing) and security (e.g., malware spread and patching). In each case, we obtain computational frameworks using Pontryagin’s Maximum Principle that will lead to the derivation of dynamic controls that optimize general, context-specific objectives. We then prove structures for each of these vectors of optimal controls that can simplify the derivation, storage, and implementation of optimal policies. Finally, using simulations and real-world traces, we examine the benefits achieved by including heterogeneity in the control decision, as well as the sensitivity of the models and the controls to model parameters in each case

Spatio-temporal modelling of civil violence: Four frameworks for obtaining policy-relevant insights

Mathematical modelling of civil violence can be accomplished in different ways. In this thesis, four modelling frameworks are investigated, each of which leads to different insights into the spatio-temporal properties of civil violence. These frameworks vary with respect to the extent in which empirical data is used in generating model assumptions, and the extent in which simplifying assumptions distance the model from the real world. An overarching objective is to compare the insights and underlying assumptions of each framework, and to consider how they might be consolidated to aid policy decision-making. Within each framework, novel contributions both to the mathematical modelling of social systems, and to the theoretical understanding of civil violence are made. First, a novel data-driven approach for analysing local patterns of geographic diffusion in event data is presented, and applied to offences associated with the 2011 London riots. Second, by considering the decision-making of individuals, thereby taking an agent-based perspective, and using existing theory to construct model assumptions, a parametric statistical model of discrete choice is derived that more closely inspects the targets chosen by rioters, and how these choices might have changed over time. The application of this model to the policy domain is explored by considering police deployment strategies. Third, focusing on the interaction between two adversaries, and employing stochastic point process models, a series of multivariate and nonlinear Hawkes processes are proposed and used to explore spatio-temporal dependency during the Naxal insurgency in India. Fourth, a novel spatially-explicit differential equation-based model of conflict escalation between two adversaries is derived. A bifurcation is identified that results from the spatial disaggregation of the model. Implications for the interpretation of the model in the real world and potential applications are discussed