Dimensionamento optimizado de sistemas adutores elevatórios de água : uma ferramenta essencial para o planeamento e gestão dos sistemas de abastecimento de água

Neste trabalho divulga-se um algoritmo para a concepção e dimensionamento de sistemas de abastecimento de água que incorpora ferramentas de optimização. São caracterizados os elementos base, designadamente descreve-se o procedimento para calcular os custos de investimento e os encargos de exploração. Concebe-se a tarefa de dimensionamento como um procedimento de optimização. Apresenta-se a formulação matemática do problema. O objectivo consiste em determinar o diâmetro da adutora que maximiza os resultados e que respeite as restrições técnicas. A equação resultante para a função objectivo e as restrições são não-lineares. Referem-se os algoritmos de optimização que poderão ser usados para o cálculo diâmetro óptimo. Descreve-se a metodologia desenvolvida. O interesse da formulação proposta é demonstrado com exemplos de aplicação. Emprega-se a metodologia na definição de fórmulas de pré-dimensionamento e no estabelecimento de funções de custo que quantifiquem os investimentos e os encargos de exploração em função do caudal de projecto. Estes resultados são elementos indispensáveis para modelos de optimização que definam a implantação e as políticas de exploração de origens de abastecimento de água, ou seja para o planeamento e gestão de recursos hídricos

Density perturbations in Kaluza--Klein theories during a de Sitter phase

In the context of Kaluza-Klein theories, we consider a model in which the universe is filled with a perfect fluid described by a barotropic equation of state. An analysis of density perturbations employing the synchronous gauge shows that there are cases where these perturbations have an exponential growth during a de Sitter phase evolution in the external space.Comment: LaTex file, 10 pages. To be published in Classical and Quantum Gravit

Sobolev homeomorphisms are dense in volume preserving automorphisms

In this paper we prove a Lusin theorem for the space of Sobolev-(1,p) volume preserving homeomorphism on closed and connected n-dimensional manifolds, n >= 3, for pn this result is not true.The authors would like to thank the anonymous referee for the careful reading of the manuscript and for giving very helpful comments and suggestions. AA and MJT were partially supported by the Research Centre of Mathematics of the University of Minho with the Portuguese Funds from the “Fundação para a Ciência e a Tecnologia”, through the Project UID/MAT/ 00013/2013. MB was partially supported by FCT - ‘Fundação para a Ciência e a Tecnologia’, through Centro de Matemática e Aplicações (CMA-UBI), Universidade da Beira Interior, project UID/MAT/00212/2013

Quantum cosmology of scalar-tensor theories and self-adjointness

In this paper, the problem of the self-adjointness for the case of a quantum minisuperspace Hamiltonian retrieved from a Brans-Dicke (BD) action is investigated. Our matter content is presented in terms of a perfect fluid, onto which the Schutz's formalism will be applied. We use the von Neumann theorem and the similarity with the Laplacian operator in one of the variables to determine the cases where the Hamiltonian is self-adjoint and if it admits self-adjoint extensions. For the latter, we study which extension is physically more suitable.Comment: Latex file, 12 pages. Small changes made in the paper, and a a new appendix adde

Numerical tests of the large charge expansion

We perform Monte-Carlo measurements of two and three point functions of charged operators in the critical O(2) model in 3 dimensions. Our results are compatible with the predictions of the large charge superfluid effective field theory. To obtain reliable measurements for large values of the charge, we improved the Worm algorithm and devised a measurement scheme which mitigates the uncertainties due to lattice and finite size effects.Comment: 16 pages, 12 figures. v2: Improved finite size scaling. v3: Added comparison between Monte Carlo update

KINANTHROPOMETRIC PROFILE OF PORTUGUESE WATER POLO PLAYERS

Our purpose was to describe physical and training background characteristics of Water Polo players and compare them according to their specialized playing positions. The International Working Group of Kinanthropometry guidelines were followed. A one-way unvaried measure ANOVA with Bonferroni post hoc was used to develop a multiple comparisons procedure between the specialized playing positions (α=0.05). It was concluded that the center players presented tendency for the highest values in 8 of the 10 parameters studied. Center backs are older than the drivers and center forwards have a higher BMI than the wingers and the goalkeepers. The somatotype is balanced mesomorph. Center forwards and Drivers tend to get closer endomorphy when compared with the remaining positions

An analysis of cosmological perturbations in hydrodynamical and field representations

Density fluctuations of fluids with negative pressure exhibit decreasing time behaviour in the long wavelength limit, but are strongly unstable in the small wavelength limit when a hydrodynamical approach is used. On the other hand, the corresponding gravitational waves are well behaved. We verify that the instabilities present in density fluctuations are due essentially to the hydrodynamical representation; if we turn to a field representation that lead to the same background behaviour, the instabilities are no more present. In the long wavelength limit, both approachs give the same results. We show also that this inequivalence between background and perturbative level is a feature of negative pressure fluid. When the fluid has positive pressure, the hydrodynamical representation leads to the same behaviour as the field representation both at the background and perturbative levels.Comment: Latex file, 18 page

Redução de altura de plantas de sorgo forrageiro com uso de regulador de crescimento.

O trabalho teve como objetivo avaliar o efeito de aplicação do regulador de crescimento Moddus (Trinexapaque-etílico), em três cultivares de sorgo silageiro, e sua influência sobre o desenvolvimento da planta em dois anos agrícolas

Cultura em substratos orgânicos de Gerberas

O cultivo sem solo de Gerbera (Gerbera jamesonii) tem-se revelado uma técnica adequada, permitindo ultrapassar alguns dos problemas surgidos na cultura tradicional, em solo. No âmbito do Projecto Agro no197 “Cultura sem solo com reutilização do efluente, em estufa com controle ambiental melhorado”, desenvolvido pela Direcçao Regional de Agricultura do Algarve, pelo Cento de Hidroponia e Utilidades Hortofrutícolas e pela Universidade do Algarve testou-se o cultivo de gerbera em substratos alternativos, no Centro de Experimentação Hortofrutícola do Patacão. Cultivaram-se quatro cultivares de gerbera: Monika, Junkfrau, Venice e Lady, em substratos preparados à base de resíduos orgânicos: casca de pinho e bagaço de uva, durante dois anos consecutivos. Os resultados obtidos sugerem que os substratos testados apresentam características adequadas à cultura da gerbera, tendo-se obtido as produções mais elevadas com o bagaço de uva compostado e a casca de pinho não compostada. Das cv. em estudo, no 1o ano a Venice apresentou o maior número de flores comercializáveis, seguida da Lady com mais flores na classe Extra. No 2o ano, a produção foi mais equilibrada entre as cultivares, sendo de registar o aumento da produção em duas cv., Junkfrau e Monica

Sliding mode control of an innovative single-switch three-level active rectifier

This paper presents the sliding mode control (SMC) applied to an innovative active rectifier. This proposed active rectifier is constituted by a single-switch, and operates with three voltage levels, evidencing a set of advantages when compared with conventional approaches of power factor correction topologies. Taking into account the diversity of applications for this type of power converter, the SMC is used in order to obtain a robust current tracking. Since the active rectifier is controlled according to the ac grid-side current, the error between such current and its reference is determined, and by employing the SMC, this error is minimized during each sampling period with the objective of selecting the state of the single-switch. A comprehensive description about the SMC implementation, supported by the overall operation of the active rectifier, is presented throughout the paper. The obtained computational results for a set of different operating conditions, comprising significant power ranges and sudden variations, confirm the accurate application of the SMC when applied to the proposed single-switch three-level active rectifier. A comparison is also established with other current control, allowing to confirm the precise application of the SMC strategy.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019. This work has been supported by FCT Project newERA4GRIDs PTDC/EEI-EEE/30283/2017, and by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FCT