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- Numerical modelling of operational risks for the banking industryPublication . Barreira, Raquel; Pryer, Tristan; Tang, Q.
- Repositório de ferramentas para a gestão de sistemas de distribuição de águaPublication . Carriço, Nelson; Ferreira, Bruno; Antunes, André; Caetano, João; Barreira, Raquel; Covas, DídiaNo presente artigo apresenta-se um conjunto de ferramentas, disponíveis em código aberto, para a gestão de sistemas de distribuição de água, desenvolvidas no âmbito dois projetos de investigação, financiados pela Fundação para a Ciência e Tecnologia (FCT), o projeto DECIdE (https://decide.ips.pt/) e o projeto WISDom (https://wisdom.ips.pt/). No âmbito do projeto DECIdE, foram desenvolvidas ferramentas que permitem importar e tratar dados, através de ficheiros exportados de sistemas de informação geográfica (SIG), em formato shapefile, folhas de cálculo com medições para o cálculo de balanços hídrico e energético e, também, de indicadores de desempenho de sistema, como por exemplo, perdas por quilómetro de conduta. No projeto WISDom, foram desenvolvidas ferramentas para a localização ótima de sensores de pressão, para o processamento de dados de caudal, para identificação de zonas críticas da rede de distribuição e para priorização de condutas para intervenções de reabilitação. Estas ferramentas são úteis para apoiar os técnicos das entidades gestoras na operação dos sistemas e são um passo na direção da transformação digital.
- Cross-Diffusion in Reaction-Diffusion Models:Analysis, Numerics, and ApplicationsPublication . Madzvamuse, Anotida; Barreira, Raquel; Gerisch, Alf
- Processing of high-resolution temporal climate data for daily simulations of a complex agro-ecosystemPublication . Paz, Maria Catarina; Santos, Sónia A.P.; Barreira, RaquelEcosystem services, such as natural pest control, are essential tools to be incorpora ted in future agricultural methodologies. In this paper we focus on the processing of climate data series that feed to a system of computer models simulating daily inte ractions of a pest and its predator, in a dynamic landscape, the olive grove. We filled hourly climate data series and converted them to daily climate series using R langua ge. The methodology used produces acceptable climate data series for the system to run and allows to segregate specific periods of the day while maintaining daily tem poral resolution. We expect this paper can be helpful when dealing with similar data and purpose.
- Exhibiting cross-diffusion-induced patterns for reaction-diffusionsystems on evolving domains and surfacesPublication . Madzvamuse, Anotida; Barreira, RaquelThe aim of this manuscript is to present for the first time the application of the finite element method for solvingreaction-diffusion systems with cross-diffusion on continuously evolving domains and surfaces. Furthermore wepresent pattern formation generated by the reaction-diffusion system with cross-diffusion on evolving domains andsurfaces. A two-component reaction-diffusion system with linear cross-diffusion in bothuandvis presented. Thefinite element method is based on the approximation of the domain or surface by a triangulated domain or surfaceconsisting of a union of triangles. For surfaces, the vertices of the triangulation lie on the continuous surface. Afinite element space of functions is then defined by taking the continuous functions which are linear affine on eachsimplex of the triangulated domain or surface. To demonstrate the role of cross-diffusion to the theory of patternformation, we compute patterns with model kinetic parameter values that belong only to the cross-diffusionparameter space; these do not belong to the standard parameter space for classical reaction-diffusion systems.Numerical results exhibited show the robustness, flexibility, versatility, and generality of our methodology; themethodology can deal with complicated evolution laws of the domain and surface, and these include uniformisotropic and anisotropic growth profiles as well as those profiles driven by chemical concentrations residing inthe domain or on the surface
- A practical approach to model banking risks using Loss Distribution Approach (LDA) in Basel II frameworkPublication . Barreira, Raquel; Pryer, Tristan; Tang, QiIn Basel II Capital Accord, the Advanced Measurement Approaches (AMA) is stated as one of the pillar stone methods for calculating corporate risk reserves. One of the common yet cumbersome methods is the one known as loss distribution approach (cf. [3]). In this article, we present an easy to implement scheme through electronic means and discuss some of the mathematical problems we encountered in the process together with proposed solution methods and further sought on the issues.
- OLIVESIM: Gestão dos serviços de ecossistema no olival utilizando modelos espaciais avançadosPublication . Santos, Sónia A.P.; Pereira, José; Antunes, Rui; Barreira, Raquel; Silva, António; Alves, Joana; Benhadí-Marin, J.; Topping, C.; Sousa, J. P.
- Flowrate time series processing in engineering tools for water distribution networksPublication . Ferreira, Bruno; Carriço, Nelson; Barreira, Raquel; Dias, Tiago; Covas, DídiaThe current paper presents a comprehensive methodology for processing unevenly (and evenly) spaced flowrate time series for subsequent use in engineering tools, such as the calibration of hydraulic models or the detection and location of leaks and bursts. The methodology is a four-step procedure: (a) anomaly identification and removal, (b) short-duration gap reconstruction, (c) time step normalization, and (d) long- duration gap reconstruction. The time step normalization is carried out by a numerical procedure prior to the reconstruction process. This reconstruction process uses a pattern model coupled with regression techniques (i.e., autoregressive integrated moving average and exponential smoothing). The methodology is calibrated using Monte Carlo simulations applied to a water utility flowrate time series and validated with two additional time series from different water utilities. Obtained results demonstrate that the proposed methodology can process flowrate time series from water supply systems with different characteristics (e.g., consumption pattern, data acquisition system, transmission settings) both for normal operating conditions and during the occurrence of abnormal events (e.g., pipe bursts). This methodology is a very useful tool for the daily management of water utilities, preparing the time series to be used in different engineering tools, namely, hydraulic simulation, model calibration or online burst detectio
- Cross-diffusion-driven instability for reaction-diffusion systems: analysis and simulationsPublication . Madzvamuse, Anotida; Ndakwo, Hussaini; Barreira, RaquelBy introducing linear cross-diffusion for a two-component reaction-diffusion system withactivator-depletedreaction kinetics (Gierer and Meinhardt,Kybernetik 12:30–39,1972;PrigogineandLefever,JChemPhys48:1695–1700,1968;Schnakenberg, J Theor Biol 81:389–400,1979), we derivecross-diffusion-driveninstability conditions and show that they are a generalisation of the classical diffusion-driveninstabilityconditionsintheabsenceofcross-diffusion.Ourmostrevealingresultis that, in contrast to the classical reaction-diffusion systems without cross-diffusion,it is no longer necessary to enforce that one of the species diffuse much faster than theother.Furthermore,it is no longer necessary to have an activator–inhibitor mecha-nism as premises for pattern formation, activator–activator,inhibitor–inhibitorreac-tion kinetics as well asshort-range inhibitionandlong-range activationall have thepotential of giving rise to cross-diffusion-driven instability. To support our theoreti-cal findings, we compute cross-diffusion induced parameter spaces and demonstratesimilarities and differences to those obtained using standard reaction-diffusion theory.Finite element numerical simulations on planary square domains are presented to back-up theoretical predictions. For the numerical simulations presented, we choose parameter values from and outside the classical Turing diffusively-driven instability space;outside, these are chosen to belong to cross-diffusively-driven instability parameterspaces. Our numerical experiments validate our theoretical predictions that parameterspaces induced by cross-diffusion in both theuandvcomponents of the reaction-diffusion system are substantially larger and different from those without cross-diffusion. Furthermore, the parameter spaces without cross-diffusion are sub-spacesof the cross-diffusion induced parameter spaces. Our results allow experimentalists tohave a wider range of parameter spaces from which to select reaction kinetic parametervalues that will give rise to spatial patterning in the presence of cross-diffusion.
- Developing a subpopulation-based model for the olive fruit fly Bactrocera oleae (Diptera: Tephritidae): conceptual model out-linePublication . Paz, Maria Catarina; Santos, Sónia A.P.; Barreira, Raquel; Rasko, Mykola; Xiaodong, Duan; Alves, Joana; Silva, António Alves da; Mina, Rúben; Topping, Christopher J.; Sousa, José PauloBactrocera oleae Rossi (olive fruit fly) is a dipteran of the family Tephritidae, considered the key pest of olives in Mediterranean countries, where it causes losses of great economic impact. Nat ural pest control is an important alternative or complement to the use of plant protection products against B. oleae. This is an ecosystem service that can be enhanced if we are able to predict its behav ior, which can be done through computer models simulating interactions between animals, agricul tural management and climate. In this paper we present the conceptual model of a spatially explicit subpopulation-based model being developed for B. oleae in olive groves. In this modelling tech nique, the simulated dynamic landscape is segmented into non-overlapping cells, where the sub populations of B. oleae are represented as separate but interacting entities. Our model is based on the Animal Landscape Man Simulation System (ALMaSS), which comprises a highly detailed and realistic landscape representation, incorporating data on different aspects of farm management, crop development, and climate, and where simulated entities operate. We present the general out line of B. oleae’s life cycle, as well as succinct information on how these organisms interact with their environment. This is a step for the development of the final model and its implementation in AL MaSS.
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