671 research outputs found

    Multi-agent Electricity Markets and Smart Grids Simulation with Connection to Real Physical Resources

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    The increasing penetration of distributed energy sources, mainly based on renewable generation, calls for an urgent emergence of novel advanced methods to deal with the associated problems. The consensus behind smart grids (SGs) as one of the most promising solutions for the massive integration of renewable energy sources in power systems has led to the development of several prototypes that aim at testing and validating SG methodologies. The urgent need to accommodate such resources require alternative solutions. This chapter presents a multi-agent based SG simulation platform connected to physical resources, so that realistic scenarios can be simulated. The SG simulator is also connected to the Multi-Agent Simulator of Competitive Electricity Markets, which provides a solid framework for the simulation of electricity markets. The cooperation between the two simulation platforms provides huge studying opportunities under different perspectives, resulting in an important contribution to the fields of transactive energy, electricity markets, and SGs. A case study is presented, showing the potentialities for interaction between players of the two ecosystems: a SG operator, which manages the internal resources of a SG, is able to participate in electricity market negotiations to trade the necessary amounts of power to fulfill the needs of SG consumers.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement N. 641794 (project DREAM-GO). It has also received FEDER Funds through the COMPETE program and National Funds through FCT under the project UID/EEA/00760/2013. The authors gratefully acknowledge the valuable contribution of Bruno Canizes, Daniel Paiva, Gabriel Santos and Marco Silva to the work presented in the chapter.info:eu-repo/semantics/publishedVersio

    A general treatment of geometric phases and dynamical invariants

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    Based only on the parallel transport condition, we present a general method to compute Abelian or non-Abelian geometric phases acquired by the basis states of pure or mixed density operators, which also holds for nonadiabatic and noncyclic evolution. Two interesting features of the non-Abelian geometric phase obtained by our method stand out: i) it is a generalization of Wilczek and Zee's non-Abelian holonomy, in that it describes nonadiabatic evolution where the basis states are parallelly transported between distinct degenerate subspaces, and ii) the non-Abelian character of our geometric phase relies on the transitional evolution of the basis states, even in the nondegenerate case. We apply our formalism to a two-level system evolving nonadiabatically under spontaneous decay to emphasize the non-Abelian nature of the geometric phase induced by the reservoir. We also show, through the generalized invariant theory, that our general approach encompasses previous results in the literature

    Cartilage tissue engineering using electrospun PCL nanofiber meshes and MSCs

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    Mesenchymal stem cells (MSCs) have been recognized for their ability to differentiate into cells of different tissues such as bone, cartilage, or adipose tissue, and therefore are of great interest for potential therapeutic strategies. Adherent, colony-forming, fibroblastic cells were isolated from human bone marrow aspirates, from patients undergoing knee arthroplasties, and the MSCs phenotype characterized by flow cytometry. Afterward, cells were seeded onto electrospun polycaprolactone nanofiber meshes and cultured in a multichamber flow perfusion bioreactor to determine their ability to produce cartilagineous extracellular matrix. Results indicate that the flow perfusion bioreactor increased the chondrogenic differentiation of hBM-MSCs, as confirmed either by morphological and RT-PCR analysis. Cartilage-related genes such as aggrecan, collagen type II, and Sox9 were expressed. ECM deposition was also detected by histological procedures. Collagen type II was present in the samples, as well as collagen type I. Despite no statistically significant values being obtained for gene expression, the other results support the choice of the bioreactor for this type of culture.M. Alves da Silva would like to acknowledge the Portuguese Foundation for Science and Technology (FCT) for her grant (SFRH/BD/28708/2006). The authors would like to acknowledge the patients of Hospital de S. Marcos, Braga, Portugal, for the donation of the biological samples, as well to its medical staff. The authors would also like to thank the Institute for Health and Life Sciences (ICVS), University of Minho, Braga, Portugal, for allowing the use of their research facilities. Authors would like specially to acknowledge Luis Martins for his valuable help with the histological procedures and Goreti Pinto for the aid in the microscopy. We thank Ana M. Frias for the important help with the FACS procedure. Finally, we would like to acknowledge the European NoE EXPERTISSUES (NMP3-CT-2004-500283). This work was partially supported by the European FP7 Project Find and Bind (NMP4-SL-2009-229292)

    Growth Characteristics of Kikuyu Grass with Different Sources and Doses of Phosphorus

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    Growth is defined as the increase in size, volume and mass as a function of time. Growth analysis allows evaluating the final growth of the plant as a whole and the contribution of the different organs in total growth (Benincasa, 1988). The experiment had as objective to evaluate specific leaf area (SLA), leaf area per unit of leaf DM, leaf area ratio (LAR), leaf area per unit of whole plant DM, leaf weight ratio (LWR), leaf weight per unit of plant weight, leaf area index (LAI), leaf area per unit of soil area, leaf/stem ratio (LSR), leaf weight per unit stem weight, of 35 days old kikuyu grass with different sources and doses of P

    Seasonality of Forage Production of Coastcross-1 with Different Sources and Applications of Phosphorus

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    Brazil presents high potential for meat production from pastures. However, the feeding of ruminants depends on the conditions and the climate. Approximately 80% of the annual production of dry matter (DM) occurs in the period October to March (spring - summer). In the autumn and winter production is low associated with high humidity and low temperatures in the south and low rainfall in the tropical north. The situation is exacerbated by inadequate management practices and low soil fertility, particularly low levels of phosphorus (P). The objective of this experiment was to evaluate the seasonality of production of DM of coastcross-1 (Cynodon dactylon) with different sources and applications of P for two consecutive years

    Cultivo de melão orgânico: fosfatos naturais como fontes alternativas de fósforo.

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    Com o objetivo de avaliar o efeito de fosfatos naturais no cultivo irrigado de melão orgânico, foram conduzidos dois ensaios em Petrolina?PE, sendo um em Argissolo Amarelo (PA) e outro num Argissolo Acinzentado (PAC). Foram avaliados os seguintes tratamentos: 1- testemunha (sem P); 2- 50 kg ha-1 de P2O5 na forma de superfosfato triplo (ST); 3- 100 kg ha-1 de P2O5 na forma de ST; 4- 150 kg ha-1 de P2O5 na forma de ST; 5- 100 kg ha-1 de P2O5 na forma de termofosfato; 6- 100 kg ha-1 de P2O5 na forma de fosfato natural de Gafsa, e 7- 100 kg ha-1 de P2O5 na forma de fosfato natural Fosbahia. O melão apresentou resposta semelhante às doses de P nos dois solos, cujas produtividades máximas de 26,00 t ha-1 e 25,46 t ha-1 foram obtidas com 107,6 kg ha-1 e 118,6 kg ha-1 de P2O5 no PA e PAC, respectivamente. A eficiência do termofosfato, fosfato de Gafsa e Fosbahia em relação ao ST assumiu a sequência de 86,2%, 77,1% e 71,9% no PA e 101,5%, 72,3% e 67,3% no PAC, demonstrando que o termofosfato é a fonte de fósforo mais indicada para ser usada no cultivo orgânico do melão. São necessários 843,12 kg de termofosfato para produzir 25.000 kg ha-1 de melão, o que representa 3,4% do custo de produção
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