A water distribution system (WDS) design deals with achieving the desired network performance. WDS design can involve new and / or existing network redesigns in order to keep up with the required service performance. Very often, WDS design is expensive, which encourages cost effectiveness in the required investments. Moreover, WDS design is associated with adverse environmental implications such as greenhouse gas (GHG) emissions due to energy consumption. GHGs are associated with global warming and climate change. Climate change is generally understood to cause reduction in water available at the sources and increase water demand. Urbanization that takes into account factors such as demographics (population ageing, household occupancy rates, etc.) and other activities are associated with water demand changes. In addition to the aforementioned issues, the challenge of meeting the required hydraulic performance of WDSs is worsened by the uncertainties that are associated with WDS parameters (e.g., future water demand). With all the factors mentioned here, mitigation and adaptive measures are considered essential to improve WDS performance in the long-term planning horizon. In this thesis, different formulations of a WDS design methodologies aimed at mitigating or adapting the systems to the effects of future changes such as those of climate change and urbanization are explored. Cost effective WDS designs that mitigate climate change by reducing GHG emissions have been investigated. Also, water demand management (DM) intervention measures, i.e., domestic rainwater harvesting (RWH) systems and water saving appliance schemes (WSASs) have been incorporated in the design of WDSs in an attempt to mitigate, adapt to or counteract the likely effects of future climate change and urbanization. Furthermore, flexibility has been introduced in the long-term WDS design under future uncertainty. The flexible methodology is adaptable to uncertain WDS parameters (i.e., future water demand in this thesis) thereby improving the WDS economic cost and hydraulic performance (resilience). The methodology is also complimented by strategically incorporating DM measures to further enhance the WDS performance under water demand uncertainty. The new methodologies presented in this thesis were successfully tested on case studies. Finally, conclusions and recommendations for possible further research work are made. There are potential benefits (e.g., cost savings, additional resilience, and lower GHG emissions) of incorporating an environmental objective and DM interventions in WDS design. Flexibility and DM interventions add value in the design of WDSs under uncertainty.

Multiscale mathematical modelling is one of the major driving forces behind the systems biology revolution. The inherently interdisciplinary nature of its study and the multiple spatial and temporal scales which characterise its dynamics make cell migration an ideal candidate for a systems biology approach. Due to its ease of analysis and its compatibility with the type of data available, phenomenological continuum modelling has long been the default framework adopted by the cell migration modelling community. However, in recent years, with increased computational power, complex, discrete, cell-level models, able to capture the detailed dynamics of experimental systems, have become more prevalent. These two modelling paradigms have complementary advantages and disadvantages. The challenge now is to combine these two seemingly disparate modelling regimes in order to exploit the benefits offered by each in a comprehensive, multiscale equivalence framework for modelling cell migration. The main aim of this thesis is to begin with an on-lattice, individual-based model and derive a continuum, population-based model which is equivalent to it in certain limits. For simple models this is relatively easy to achieve: beginning with a one-dimensional, discrete model of cell migration on a regular lattice we derive a partial differential equation for the evolution of cell density on the same domain. We are also able to simply incorporate various signal sensing dynamics into our fledgling equivalence framework. However, as we begin to incorporate more complex model attributes such as cell proliferation/death, signalling dynamics and domain growth we find that deriving an equivalent continuum model requires some innovative mathematics. The same is true when considering a non-uniform domain discretisation in the one-dimensional model and when determining appropriate domain discretisations in higher dimensions. Higher-dimensional simulations of individual-based models bring with them their own computational challenges. Increased lattice sites in order to maintain spatial resolution and increased cell numbers in order to maintain consistent densities lead to dramatic reductions in simulation speeds. We consider a variety of methods to increase the efficiency of our simulations and derive novel acceleration techniques which can be applied to general reaction systems but are especially useful for our spatially extended cell migration algorithms. The incorporation of domain growth in higher dimensions is the final hurdle we clear on our way to constructing a complex discrete-continuum modelling framework capable of representing signal-mediated cell migration on growing (possibly non-standard) domains in multiple dimensions.

Phytoplankton are single celled organisms capable of phytosynthesis, and are present in all the major oceans and lakes in the world. Phytoplankton contribute to 50% of the total primary production on Earth, and are the dominating primary producer in most aquatic ecosystems. This thesis is based on the 1D deterministic model by Jäger et. al. (2010) which models phytoplankton dynamics in freshwater lakes, where phytoplankton growth is limited by the availability of light and phosphorus. The original model is here extended to two dimensions to include a horizontal dimension as well as a vertical dimension, in order to simulate phytoplankton dynamics under varying lake bottom topographies. The model was solved numerically using a grid transform and a finite volume method in MATLAB. Using the same parameter settings as the 1D case studied by Jäger et. al. (2010), an initial study of plankton dynamics was done by varying the horizontal and vertical diffusion coefficients independently.

A análise de texturas dinâmicas tem se apresentado como uma área de pesquisa crescente e em potencial nos últimos anos em visão computacional. As texturas dinâmicas são sequências de imagens de textura (i.e. vídeo) que representam objetos dinâmicos. Exemplos de texturas dinâmicas são: evolução de colônia de bactérias, crescimento de tecidos do corpo humano, escada rolante em movimento, cachoeiras, fumaça, processo de corrosão de metal, entre outros. Apesar de existirem pesquisas relacionadas com o tema e de resultados promissores, a maioria dos métodos da literatura possui limitações. Além disso, em muitos casos as texturas dinâmicas são resultado de fenômenos complexos, tornando a tarefa de caracterização um desafio ainda maior. Esse cenário requer o desenvolvimento de um paradigma de métodos baseados em complexidade. A complexidade pode ser compreendida como uma medida de irregularidade das texturas dinâmicas, permitindo medir a estrutura dos pixels e quantificar os aspectos espaciais e temporais. Neste contexto, o objetivo deste mestrado é estudar e desenvolver métodos para caracterização de texturas dinâmicas baseado em metodologias de complexidade advindas da área de sistemas complexos. Em particular, duas metodologias já utilizadas em problemas de visão computacional são consideradas: redes complexas e caminhada determinística parcialmente auto-repulsiva. A partir dessas metodologias, três métodos de caracterização de texturas dinâmicas foram desenvolvidos: (i) baseado em difusão em redes - (ii) baseado em caminhada determinística parcialmente auto-repulsiva - (iii) baseado em redes geradas por caminhada determinística parcialmente auto-repulsiva. Os métodos desenvolvidos foram aplicados em problemas de nanotecnologia e tráfego de veículos, apresentando resultados potenciais e contribuindo para o desenvolvimento de ambas áreas. / Dynamic texture analysis has been an area of research increasing and in potential in recent years in computer vision. Dynamic textures are sequences of texture images (i.e. video) that represent dynamic objects. Examples of dynamic textures are: evolution of the colony of bacteria, growth of body tissues, moving escalator, waterfalls, smoke, process of metal corrosion, among others. Although there are researches related to the topic and promising results, most literature methods have limitations. Moreover, in many cases the dynamic textures are the result of complex phenomena, making a characterization task even more challenging. This scenario requires the development of a paradigm of methods based on complexity. The complexity can be understood as a measure of irregularity of the dynamic textures, allowing to measure the structure of the pixels and to quantify the spatial and temporal aspects. In this context, this masters aims to study and develop methods for the characterization of dynamic textures based on methodologies of complexity from the area of complex systems. In particular, two methodologies already used in computer vision problems are considered: complex networks and deterministic walk partially self-repulsive. Based on these methodologies, three methods of characterization of dynamic textures were developed: (i) based on diffusion in networks - (ii) based on deterministic walk partially self-repulsive - (iii) based on networks generated by deterministic walk partially self-repulsive. The developed methods were applied in problems of nanotechnology and vehicle traffic, presenting potencial results and contribuing to the development of both areas.

This thesis presents a study on time series analysis, which was conducted based on the following hypothesis: time series influenced by additive noise can be decomposed into stochastic and deterministic components in which individual models permit obtaining a hybrid one that improves accuracy. This hypothesis was confirmed in two steps. In the first one, we developed a formal analysis using the Nyquist-Shannon sampling theorem, proving Intrinsic Mode Functions (IMFs) extracted from the Empirical Mode Decomposition (EMD) method can be combined, according to their frequency intensities, to form stochastic and deterministic components. Considering this proof, we designed two approaches to decompose time series, which were evaluated in synthetic and real-world scenarios. Experimental results confirmed the importance of decomposing time series and individually modeling the deterministic and stochastic components, proving the second part of our hypothesis. Furthermore, we noticed the individual analysis of both components plays an important role in detecting patterns and extracting implicit information from time series. In addition to these approaches, this thesis also presents two new measurements. The first one is used to evaluate the accuracy of time series modeling in forecasting observations. This measurement was motivated by the fact that existing measurements only consider the perfect match between expected and predicted values. This new measurement overcomes this issue by also analyzing the global time series behavior. The second measurement presented important results to assess the influence of the deterministic and stochastic components on time series observations, supporting the decomposition process. Finally, this thesis also presents a Systematic Literature Review, which collected important information on related work, and two new methods to produce surrogate data, which permit investigating the presence of linear and nonlinear Gaussian processes in time series, irrespective of the influence of nonstationary behavior / Esta tese apresenta um estudo sobre análise de séries temporais, a qual foi conduzida baseada na seguinte hipótese: séries temporais influenciadas por ruído aditivo podem ser decompostas em componentes estocásticos e determinísticos que ao serem modelados individualmente permitem obter um modelo híbrido de maior acurácia. Essa hipótese foi confirmada em duas etapas. Na primeira, desenvolveu-se uma análise formal usando o teorema de amostragem proposto por Nyquist-Shannon, provando que IMFs (Intrinsic Mode Functions) extraídas pelo método EMD (Empirical Mode Decomposition) podem ser combinadas de acordo com suas intensidades de frequência para formar os componentes estocásticos e determinísticos. Considerando essa prova, duas abordagens de decomposição de séries foram desenvolvidas e avaliadas em aplicações sintéticas e reais. Resultados experimentais confirmaram a importância de decompor séries temporais e modelar seus componentes estocásticos e determinísticos, provando a segunda parte da hipótese. Além disso, notou-se que a análise individual desses componentes possibilita detectar padrões e extrair importantes informações implícitas em séries temporais. Essa tese apresenta ainda duas novas medidas. A primeira é usada para avaliar a acurácia de modelos utilizados para predizer observações. A principal vantagem dessa medida em relação às existentes é a possibilidade de avaliar os valores individuais de predição e o comportamento global entre as observações preditas e experadas. A segunda medida permite avaliar a influência dos componentes estocásticos e determinísticos sobre as séries temporais. Finalmente, essa tese apresenta ainda resultados obtidos por meio de uma revisão sistemática da literatura, a qual coletou importantes trabalhos relacionados, e dois novos métodos para geração de dados substitutos, permitindo investigar a presença de processos Gaussianos lineares e não-lineares, independente da influência de comportamento não-estacionário

O planejamento da operação energética de sistemas hidrotérmicos de potência tem como objetivo determinar a participação de usinas termoelétricas e hidrelétricas de forma a garantir o suprimento desta energia ao menor custo operacional possível, dentro de restrições técnicas. Alguns fatores tornam a solução desse problema bastante complexa destacando a não linearidade, presente na equação de geração hidráulica; a não separabilidade espacial, devido ao fato da decisão de quanto gerar em uma usina interferir em outra usina do sistema; a separabilidade temporal aditiva, devido a interferência de uma decisão atual em uma decisão futura e, como no caso brasileiro, de grande porte. O objetivo deste trabalho é apresentar uma nova abordagem para o planejamento da operação de sistemas hidrotérmicos de potência, com Programação Dinâmica, de forma que as usinas hidrelétricas possam ser representadas e otimizadas individualmente, completamente desacopladas. Essa aplicação é possível através da utilização de uma função objetivo modificada, considerando-se não apenas os custos, mas também os dados de afluências das usinas imediatamente a jusante. O modelo proposto, como função objetivo modificada, foi aplicado em cascatas de usinas hidrelétricas brasileiras, cujos resultados puderam ser comparados com os comportamentos ótimos obtidos de forma direta, ou seja, com a otimização de todo o sistema em conjunto. Com base nos resultados obtidos, pôde-se observar o bom comportamento do modelo implementado. / The energetic operation planning in hydrothermal power systems aims to determine the participation of hydroelectric power plants and thermoelectric power plants to ensure the supply of electricity at the lowest operating cost possible, between technical constraints. Some factors make the solution of this problem quite complex highlighting the nonlinearity, present in the equation of hydraulic generation, non-spatial separability, due the fact that the decision of the amount of energy generated in a plant interfere in another plants of the system, the additive time separability, because of the interference from an actual decision on a future decision and, as in the Brazilian case, large. The proposal of this work is to present a new approach to hydrothermal power systems, with Dynamic Programming, so that hydroelectric power plants can be represented and optimized individually, completely decoupled. This application is possible through the use of a modified objective function, considering not only costs but also the inflow data immediately on the downstream plants. The proposed model was applied in a Brazilian cascade of hydroelectric plants, comparing the optimal behavior obtained directly, by optimizing the whole system together and the new technique behavior. Based on the results obtained, we can observe the good results of the implemented model.

O teste de programas concorrentes é uma atividade custosa devido principalmente à quantidade de sequências de sincronização que devem ser testadas para validar tais programas. Uma das técnicas mais utilizadas para testar a comunicação e sincronização de programas concorrentes é a geração automática de diferentes pares de sincronização ou, em outras palavras, a geração de variantes de disputa (race variant). Nesta técnica as variantes de disputa são geradas a partir de arquivos de rastro de uma execução não-determinística e algoritmos de execução determinística são utilizados para forçar que diferentes sincronizações sejam cobertas. Este trabalho aborda de maneira abrangente este problema, cujo objetivo principal é reduzir o tempo de resposta da atividade de teste estrutural de programas concorrentes quando diferentes variantes de disputa são executadas. Há três principais contribuições neste trabalho: (1) geração de arquivos de rastro e execução determinística total/parcial, (2) geração automática de variantes e (3) paralelização da execução das variantes. Diferentemente de outros trabalhos disponíveis na literatura, os algoritmos propostos consideram programas concorrentes que interagem simultaneamente com passagem de mensagens e memória compartilhada. Foram consideradas seis primitivas com semânticas distintas: ponto-a-ponto bloqueante/não bloqueante, coletivas um-para-todos/todos-para-um/todos-para-todos e semáforos. Os algoritmos foram desenvolvidos no nível de aplicação em Java, são ortogonais à linguagem de programação utilizada e não requerem privilégios de sistema para serem executados. Estas três contribuições são descritas, detalhando seus algoritmos. Também são apresentados os resultados obtidos com os experimentos feitos durante as fases de validação e avaliação de cada contribuição. Os resultados demonstram que os objetivos propostos foram atingidos com sucesso para cada contribuição e, do ponto de vista do testador, o tempo de resposta da atividade de teste estrutural de programas concorrentes foi reduzido enquanto a cobertura de programas concorrentes com ambos os paradigmas aumentou com procedimentos automatizados e transparentes. Os experimentos mostram speedups próximos ao linear, quando comparadas as versões sequencial e paralela dos algoritmos. / The testing of concurrent programs is an expensive task, mainly because it needs to test a high number of synchronization sequences, in order to validate such programs. One of the most used techniques to test communication and synchronization of concurrent programs is the automatic generation of different synchronizations pairs (or generation of race variants). Race variants are generated from the trace files of a nondeterministic execution, and the deterministic executions force the coverage of different synchronizations. This work approaches this problem in a more general way. It reduces the response time of the structural testing of concurrent programs when different variants are required. There are three main contributions in this work: the generation of trace files and the total or partial deterministic execution, the automatic generation of race variants and the parallelization of execution of race variants. The proposed algorithms take into account concurrent programs that interact simultaneously with message passing and shared memory, including six primitives with distinct semantics: blocking and non-blocking point-to-point, all-to-all/one-to-all/all-toone collectives and shared memory. The algorithms have been implemented in Java in the application level, they are language independent and do not need system privileges to execute. Results obtained during the validation and evaluation phase are also presented and they show that the proposed objectives are reached with success. From the tester viewpoint, the response time of structural testing of concurrent programs was reduced, while the coverage of the concurrent programs with both paradigms increased with automatic and transparent procedures. The experiments showed speedups close to linear, when comparing the sequential and parallel versions.

Montamos um aparato experimental para o estudo de comportamentos complexos na dinâmica de formação de gotas d\'água no bico de uma torneira. Desenvolvemos um sistema hidráulico em circuito fechado, e um sistema de aquisição de dados automatizado, que também controla a abertura da torneira (uma válvula de agulha). Utilizamos como parâmetro de controle a taxa de gotejamento estabelecida pela abertura da torneira. Os dados são séries de tempos {T n} entre gotas sucessivas para cada taxa de gotejamento. Utilizando diagramas de bifurcação, e reconstruções do espaço de fase com mapas de primeiro retomo Tn+1 x Tn , observamos duplicações de período, bifurcação de Hopf, crises interiores e de fronteira, comportamentos intermitentes, e movimentos quase-periódicos. Aplicamos anticontrole de caos, desestabilizando um ponto fixo estável com pulsos de ar comprimido sobre o bico da torneira. Também iniciamos o desenvolvimento de uma técnica para o controle de caos. Verificamos a existência de pontos de sela em vários atratores experimentais e, com a aplicação de dinâmica simbólica, observamos tangências homoclínicas associadas ao aparecimento de atratores de Hénon e bifurcações homoclínicas. Utilizando métodos de caracterização topológica, estabelecemos duas rotas para o caos envolvendo tangências homoclínicas, e mostramos que o súbito desaparecimento de um atrator caótico, em altas taxas de vazão, é devido a uma \"chaotic blue sky catastrophe\", apenas observada anteriormente num modelo de equações usadas por Van der Pol para simular a dinâmica cardíaca. / We assembled an experimental apparatus to study the dynamical complex behavior of water drop formation in a nipple faucet. We developed a closed hydrodynamic circuitry, and an automated acquisition data system, which also controls the faucet (a needle valve) opening. We have used as a control parameter the dripping rate set up by the faucet opening. For each dripping rate, the data are interdrop time series {Tn} between two successive drops. With the help of bifurcation diagrams, and reconstructed phase spaces in first return maps Tn+I x Tn, we were able to observe period doubling, Hopf bifurcation, interior and boundary crises, intermittent behaviors, and quasiperiodic movements. An anti-control of chaos was applied by perturbing a stable fixed point with pulses of compressed air on the nipple faucet. We also started the development of a technique to apply the control of chaos. The occurrence of saddle points was verified in some experimental attractors. By applying symbolic dynamics, we were able to observe homoclinic tangencies associated with the appearence of Hénon-like attractors and homoclinic bifurcations. By means of topological characterization, we established two routes to chaos related to homoclinic tangencies. We also observed, at high dripping rates, a sudden disappearance of a chaotic attractor due to a \"chaotic blue sky catastrophe\", just seen in a Van der Pol model used to simulate cardiac dynamics.

Nessa tese, estudamos o limite hidrodinâmico de um sistema estocástico de neurônios cujas interações são dadas por potenciais de Kac que imitam sinapses elétricas e químicas, e as correntes de vazamento. Esse sistema consiste de $\\ep^$ neurônios imersos em $[0,1)^2$, cada um disparando aleatoriamente de acordo com um processo pontual com taxa que depende tanto do seu potential de membrana como da posição. Quando o neurônio $i$ dispara, seu potential de membrana é resetado para $0$, enquanto que o potencial de membrana do neurônio $j$ é aumentado por um valor positivo $\\ep^2 a(i,j)$, se $i$ influencia $j$. Além disso, entre disparos consecutivos, o sistema segue uma movimento determinístico devido às sinapses elétricas e às correntes de vazamento. As sinapses elétricas estão envolvidas na sincronização do potencial de membrana dos neurônios, enquanto que as correntes de vazamento inibem a atividade de todos os neurônios, atraindo simultaneamente todos os potenciais de membrana para $0$. No principal resultado dessa tese, mostramos que a distribuição empírica dos potenciais de membrana converge, quando o parâmetro $\\ep$ tende à 0 , para uma densidade de probabilidade $ho_t(u,r)$ que satisfaz uma equação diferencial parcial nâo linear do tipo hiperbólica . / We study the hydrodynamic limit of a stochastic system of neurons whose interactions are given by Kac Potentials that mimic chemical and electrical synapses and leak currents. The system consists of $\\ep^$ neurons embedded in $[0,1)^2$, each spiking randomly according to a point process with rate depending on both its membrane potential and position. When neuron $i$ spikes, its membrane potential is reset to $0$ while the membrane potential of $j$ is increased by a positive value $\\ep^2 a(i,j)$, if $i$ influences $j$. Furthermore, between consecutive spikes, the system follows a deterministic motion due both to electrical synapses and leak currents. The electrical synapses are involved in the synchronization of the membrane potentials of the neurons, while the leak currents inhibit the activity of all neurons, attracting simultaneously their membrane potentials to 0. We show that the empirical distribution of the membrane potentials converges, as $\\ep$ vanishes, to a probability density $ho_t(u,r)$ which is proved to obey a nonlinear PDE of Hyperbolic type.

Over the past few decades, wireless local area networks (WLANs) have been widely deployed for data communication in indoor environments such as offices, houses, and airports. In order to fairly and efficiently use the unlicensed frequency band that Wi-Fi devices share, the devices follow a set of channel access rules, which is called a wireless medium access control (MAC) protocol. It is known that wireless devices following the 802.11 standard MAC protocol, i.e. the distributed coordination function (DCF), suffer from packet collisions when multiple nodes simultaneously transmit. This significantly degrades the throughput performance. Recently, several studies have reported access techniques to reduce the number of packet collisions and to achieve a collision free WLAN. Although these studies have shown that the number of collisions can be reduced to zero in a simple way, there have been a couple of remaining issues to solve, such as dynamic parameter adjustment and fairness to legacy DCF nodes in terms of channel access opportunity. Recently, In-Band Full Duplex (IBFD) communication has received much attention, because it has significant potential to improve the communication capacity of a radio band. IBFD means that a node can simultaneously transmit one signal and receive another signal in the same band at the same time. In order to maximize the performance of IBFD communication capability and to fairly share access to the wireless medium among distributed devices in WLANs, a number of IBFD MAC protocols have been proposed. However, little attention has been paid to fairness issues between half duplex nodes (i.e. nodes that can either transmit or receive but not both simultaneously in one time-frequency resource block) and IBFD capable nodes in the presence of the hidden node problem.