Simulating Rainfall, Water Evaporation and Groundwater Flow in Three-Dimensional Satellite Images with Cellular Automata

Remote sensing has been used in numerous environmental simulations with the aim of solving and improving many different kinds of problems, e.g., meteorology applications, soil quality studies, water resource exploration, and environmental protection. Besides, cellular automata have been widely used in the field of remote sensing for simulating natural phenomena over two-dimensional satellite images. However, simulations on Digital Elevation Models (DEM), or three-dimensional (3D) satellite images, are scarce. This paper presents a study of modeling and simulation of the weather phenomena of rainfall, water evaporation and groundwater flow in 3D satellite images through a new algorithm, developed by the authors, named RACA (Rainfall with Cellular Automata). The purpose of RACA is to obtain, from the simulation, numerical and 3D results related to the total cumulative flow and maximum level of water that allow us to make decisions on important issues such as analyzing how climate change will affect the water level in a particular area, estimating the future water supply of a population, establishing future construction projects and urban planning away from locations with high probability of flooding, or preventing the destruction of property and human life from future natural disasters in urban areas with probability of flooding

When Whereabouts is No Longer Thereabouts:Location Privacy in Wireless Networks

Modern mobile devices are fast, programmable and feature localization and wireless capabilities. These technological advances notably facilitate mobile access to Internet, development of mobile applications and sharing of personal information, such as location information. Cell phone users can for example share their whereabouts with friends on online social networks. Following this trend, the field of ubiquitous computing foresees communication networks composed of increasingly inter-connected wireless devices offering new ways to collect and share information in the future. It also becomes harder to control the spread of personal information. Privacy is a critical challenge of ubiquitous computing as sharing personal information exposes users' private lives. Traditional techniques to protect privacy in wired networks may be inadequate in mobile networks because users are mobile, have short-lived encounters and their communications can be easily eavesdropped upon. These characteristics introduce new privacy threats related to location information: a malicious entity can track users' whereabouts and learn aspects of users' private lives that may not be apparent at first. In this dissertation, we focus on three important aspects of location privacy: location privacy threats, location-privacy preserving mechanisms, and privacy-preservation in pervasive social networks. Considering the recent surge of mobile applications, we begin by investigating location privacy threats of location-based services. We push further the understanding of the privacy risk by identifying the type and quantity of location information that statistically reveals users' identities and points of interest to third parties. Our results indicate that users are at risk even if they access location-based services episodically. This highlights the need to design privacy into location-based services. In the second part of this thesis, we delve into the subject of privacy-preserving mechanisms for mobile ad hoc networks. First, we evaluate a privacy architecture that relies on the concept of mix zones to engineer anonymity sets. Second, we identify the need for protocols to coordinate the establishment of mix zones and design centralized and distributed approaches. Because individuals may have different privacy requirements, we craft a game-theoretic model of location privacy to analyze distributed protocols. This model predicts strategic behavior of rational devices that protects their privacy at a minimum cost. This prediction leads to the design of efficient privacy-preserving protocols. Finally, we develop a dynamic model of interactions between mobile devices in order to analytically evaluate the level of privacy provided by mix zones. Our results indicate the feasibility and limitations of privacy protection based on mix zones. In the third part, we extend the communication model of mobile ad hoc networks to explore social aspects: users form groups called "communities" based on interests, proximity, or social relations and rely on these communities to communicate and discover their context. We analyze using challenge-response methodology the privacy implications of this new communication primitive. Our results indicate that, although repeated interactions between members of the same community leak community memberships, it is possible to design efficient schemes to preserve privacy in this setting. This work is part of the recent trend of designing privacy protocols to protect individuals. In this context, the author hopes that the results obtained, with both their limitations and their promises, will inspire future work on the preservation of privacy

An Initial Framework Assessing the Safety of Complex Systems

Trabajo presentado en la Conference on Complex Systems, celebrada online del 7 al 11 de diciembre de 2020.Atmospheric blocking events, that is large-scale nearly stationary atmospheric pressure patterns, are often associated with extreme weather in the mid-latitudes, such as heat waves and cold spells which have significant consequences on ecosystems, human health and economy. The high impact of blocking events has motivated numerous studies. However, there is not yet a comprehensive theory explaining their onset, maintenance and decay and their numerical prediction remains a challenge. In recent years, a number of studies have successfully employed complex network descriptions of fluid transport to characterize dynamical patterns in geophysical flows. The aim of the current work is to investigate the potential of so called Lagrangian flow networks for the detection and perhaps forecasting of atmospheric blocking events. The network is constructed by associating nodes to regions of the atmosphere and establishing links based on the flux of material between these nodes during a given time interval. One can then use effective tools and metrics developed in the context of graph theory to explore the atmospheric flow properties. In particular, Ser-Giacomi et al. [1] showed how optimal paths in a Lagrangian flow network highlight distinctive circulation patterns associated with atmospheric blocking events. We extend these results by studying the behavior of selected network measures (such as degree, entropy and harmonic closeness centrality)at the onset of and during blocking situations, demonstrating their ability to trace the spatio-temporal characteristics of these events.This research was conducted as part of the CAFE (Climate Advanced Forecasting of sub-seasonal Extremes) Innovative Training Network which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 813844

The Multi-Agent Transport Simulation MATSim

"The MATSim (Multi-Agent Transport Simulation) software project was started around 2006 with the goal of generating traffic and congestion patterns by following individual synthetic travelers through their daily or weekly activity programme. It has since then evolved from a collection of stand-alone C++ programs to an integrated Java-based framework which is publicly hosted, open-source available, automatically regression tested. It is currently used by about 40 groups throughout the world. This book takes stock of the current status. The first part of the book gives an introduction to the most important concepts, with the intention of enabling a potential user to set up and run basic simulations.The second part of the book describes how the basic functionality can be extended, for example by adding schedule-based public transit, electric or autonomous cars, paratransit, or within-day replanning. For each extension, the text provides pointers to the additional documentation and to the code base. It is also discussed how people with appropriate Java programming skills can write their own extensions, and plug them into the MATSim core. The project has started from the basic idea that traffic is a consequence of human behavior, and thus humans and their behavior should be the starting point of all modelling, and with the intuition that when simulations with 100 million particles are possible in computational physics, then behavior-oriented simulations with 10 million travelers should be possible in travel behavior research. The initial implementations thus combined concepts from computational physics and complex adaptive systems with concepts from travel behavior research. The third part of the book looks at theoretical concepts that are able to describe important aspects of the simulation system; for example, under certain conditions the code becomes a Monte Carlo engine sampling from a discrete choice model. Another important aspect is the interpretation of the MATSim score as utility in the microeconomic sense, opening up a connection to benefit cost analysis. Finally, the book collects use cases as they have been undertaken with MATSim. All current users of MATSim were invited to submit their work, and many followed with sometimes crisp and short and sometimes longer contributions, always with pointers to additional references. We hope that the book will become an invitation to explore, to build and to extend agent-based modeling of travel behavior from the stable and well tested core of MATSim documented here.

O controlo da artificialização do solo na política e legislação territorial: os casos da Argentina, Colômbia e Peru

The land takes is a major environmental challenge, specifically for biodiversity and the degradation and fragmentation of ecosystems. The most used tools to control it are the design of public policies and spatial planning. Although land take has serious effects in Latin America, little is known about the control mechanisms of land take in this region. This paper evaluates the land take control mechanisms implemented by the spatial planning plans of Buenos Aires (Argentina), Bogota (Colombia) and Lima (Peru). The evaluation was carried out through a content analysis based on three variables, the frequency of the terms related to land take control, the consistency of their inclusion in the plans, and the consistency found between the strategic documents and the regulatory documents. The findings reveal that the land take does not emerge as important concerns compared to the objectives of the plans. The main strategies to control land take in the three cities were the programs for a more compact city, land zoning and the imposition of economic charges on new urban projects. It was found that Bogotá is the city that has the most complementary programs for the control of land take, while Buenos Aires is the city that shows the least complementary strategies. It was established that the main trade offs of land take are the demographic increase and the economic dynamics of each city, but none of the cities analyzed have programs to prevent these causes.A ocupação do solo é um importante desafio ambiental, especificamente para a biodiversidade, a degradação e fragmentação dos ecossistemas. As ferramentas mais utilizadas para controlá-la são o desenho de políticas públicas e o ordenamento do território. Embora a apropriação de terras tenha sérios efeitos na América Latina, pouco se sabe sobre os mecanismos de controlo da apropriação de terras nessa região. Este artigo avalia os mecanismos de controle fundiário implementados pelos planos de ordenamento do território de Buenos Aires (Argentina), Bogotá (Colômbia) e Lima (Peru). A avaliação foi realizada por meio de análise de conteúdo com base em três variáveis, a frequência dos termos relacionados ao controle da ocupação do solo, a consistência da sua inclusão nos planos e a coerência encontrada entre os documentos estratégicos e os documentos regulatórios. Os resultados revelam que a ocupação da terra não surge como uma preocupação importante em relação aos objetivos dos planos. As principais estratégias de controlo da ocupação do solo nas três cidades foram os programas para uma cidade mais compacta, o zonamento fundiário e a imposição de encargos econômicos sobre novos projetos urbanos. Constatou-se que Bogotá é a cidade que apresenta mais programas complementares de controlo de ocupação de terras, enquanto Buenos Aires é a cidade que apresenta menos estratégias complementares. Constatou-se que os principais trade-offs de ocupação do solo são o aumento demográfico e a dinâmica económica de cada cidade, mas nenhuma das cidades analisadas possui programas de prevenção dessas causas.Mestrado em Estudos Ambientai

Modelos de simulación en tiempo real de sistemas granulares mediante autómatas celulares.

RESUMEN Las herramientas de formación basadas en simulación y realidad virtual se han convertido en las últimas décadas en una potente erramienta para la formación y el entrenamiento de multitud de tareas, especialmente aquéllas que conllevan un coste o un riesgo elevado.   Debido a las exigencias de este tipo de aplicaciones, los modelos dinámicos utilizados deben  reproducir el comportamiento del sistema simulado con suficiente realismo como para qu los hábitos adquiridos por los aprendices sean correctos. Además, deben ser suficientemente robustos y eficientes como para poder ejecutarse de forma interactiva en tiempo real.   Dentro del ámbito de la simulación de maquinaria pesada, los sistemas granulares y la interacción con el terreno (arena, grava, material granel, etc.) forman parte de las tareas  fundamentales que realiza el usuario. Sin embargo, como consecuencia de una metodología inadecuada, existe una deficiencia importante en los modelos existentes para simulación interactiva en tiempo real.   A lo largo de este trabajo se revisa la metodología de modelado utilizada habitualmente, y se desarrolla un conjunto de modelos dinámicos para la simulación de sistemas granulares.   Para conseguir modelos con un comportamiento suficientemente realista, se parte de estudios teóricos sobre el comportamiento de los sistemas granulares y la interacción con el suelo. A partir de estos estudios, y utilizando el modelo computacional de los Autómatas Celulares, se desarrolla un conjunto de modelos dinámicos que permiten la simulación interactiva de un sistema granular y una herramienta   Los modelos se validan  utilizando los trabajos teóricos anteriores, y se analiza el significado de los parámetros para permitir su ajuste en función del tipo de material que se desee simular.   Para conseguir una implementación eficiente de los modelos que permita la simulación en tiempo real, se analizan las propiedades estadísticas de la dinámica del sistema. Gracias a este análisis se consigue alcanzar un coste inferior a cuadrático respecto a las dimensiones del sistema simulado.   Se revisan las técnicas de representación gráfica existentes y se mejora la representación de las zonas de flujo por medio de l utilización de técnicas de multitextura programadas en el procesador gráfico. ______________________________________________________________________________________________The training tools based on simulation and virtual reality have become in recent decades into a powerful tool for education and training of many tasks, especially those that involve a cost or a high risk.   Due to the demands of such applications, the dynamic models have to reproduce the behavior of the system simulated with sufficient realism so that the habits acquired by trainees are correct. Furthermore, they must be sufficiently robust and efficient to be able to run interactively in real time. Within the scope of the simulation of heavy machinery, granular systems and the interaction with the ground (sand, gravel, bulk material, etc..) are part of the fundamental tasks performed by the user. However, as a result of inadequate methodology, there is a major deficiency in existing models for real-time interactive simulation. Throughout this work we review the modeling methodology used routinely, and developed a set of dynamic models for the simulation of granular systems. To obtain models with a sufficiently realistic behavior is part of theoretical studies on the behavior of granular systems and interaction with the ground. From these studies, and using the computational model of cellular automata, we develop a set of dynamic models that allow for interactive simulation of a granular system and a tool. The models are validated using the previous theoretical work, and discusses the significance of the parameters to allow adjustment of the type of material you want to simulate. To achieve an efficient implementation of the models to allow the simulation in real time, we analyze the statistical properties of the dynamics of the system. Thanks to this analysis we reach a cost of less than quadratic with respect to the dimensions of the simulated system. We review the existing techniques of graphic representation and improving the representation of the flow areas through the use of techniques multitextured programmed in the processor graph.

Bio-inspired Medium Access Control for Wireless Sensor Networks

This thesis studies the applications of biologically inspired algorithms and behaviours to the Medium Access Control (MAC) layer of Wireless Sensor Networks (WSNs). By exploring the similarity between a general communications channel and control engineering theory, we propose a simple method to control transmissions that we refer to as transmission delay. We use this concept and create a protocol inspired by Particle Swarm Optimisation (PSO) to optimise the communications. The lessons learned from this protocol inspires us to move closer to behaviours found in nature and the Emergence MAC (E-MAC) protocol is presented. The E-MAC protocol shows emergent behaviours arising from simple interactions and provides great throughput, low end-to-end delay and high fairness. Enhancements to this protocol are later proposed. We empirically evaluate these protocols and provide relevant parameter sweeps to show their performance. We also provide a theoretical approach to proving the settling properties of E-MAC. The presented protocols and methods provide a different approach towards MAC in WSNs