2,645 research outputs found

    A multistage stochastic approach for the optimal bidding of variable renewable energy in the day-ahead, intraday and balancing markets

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    ABSTRACT: Market agents with renewable resources face amplified uncertainty when forecasting energy production to securely place bids in electricity markets. To deal with uncertainties, stochastic modelling has been applied to optimize the bidding strategy of these market agents. However, studies found in the literature usually focus on day-ahead and balancing markets, leaving aside intraday markets that could be used to correct bidding positions as uncertainty gets resolved. This paper proposes a multistage stochastic decision-aid algorithm based on linear programming to optimize the bidding strategy of market agents in three different electricity markets -day-ahead, intraday, and balance markets. The market agent represents a Virtual Power Plant with wind, solar PV, and storage technologies, and its participation in three electricity markets was compared to the participation in DA and BM markets only. Results show that participating in all three markets increased the profit achieved by the VPP agent by 10.1% while also decreasing the incurred imbalances by 63.8%. The results demonstrate that having accurate tools to deal with the multi-settlement framework of electricity markets while considering the uncertainties of daily operations is key to a successful integration of renewable energy resources into electricity markets and power systems.info:eu-repo/semantics/publishedVersio

    First records of Ostreopsis heptagona, O. cf. siamensis and O. cf. ovata – in the Azores archipelago, Portugal

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    Copyright © 2010 IOC HAB Programme.During summer 2008, surveys were carried out around São Miguel island in the Azores archipelago (36–39ºN, 25–31ºW). [...]. Species of Ostreopsis were morphologically characterized with an Olympus BX50 equipped with epifluorescence, following Penna et al. [...].Governo Regional dos Açores

    Execution time as a key parameter in the waste collection problem

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    Proper waste management has been recognized as a tool for the green transition towards a more sustainable economy. For instance, most studies dealing with municipal solid wastes in the literature focus on environmental aspects, proposing new routes for recycling, composting and landfilling. However, there are other aspects to be improved in the systems that deal with municipal solid waste, especially in the transportation sector. Scholars have been exploring alternatives to improve the performance in waste collection tasks since the late 50s, for example, considering the waste collection problem as static. The transition from a static approach to a dynamic is necessary to increase the feasibility of the solution, requiring faster algorithms. Here we explore the improvement in the performance of the guided local search metaheuristic available in OR-Tools upon different execution times lower than 10 seconds to solve the capacitated waste collection problem. We show that increasing the execution time from 1 to 10 seconds can overcome savings of up to 1.5 km in the proposed system. Considering application in dynamic scenarios, the 9 s increase in execution time (from 1 to 10 s) would not hinder the algorithm’s feasibility. Additionally, the assessment of the relation between performance in different execution times with the dataset’s tightness revealed a correlation to be explored in more detail in future studies. The work done here is the first step towards a shift of paradigm from static scenarios in waste collection to dynamic route planning, with the execution time established according to the conclusions achieved in this study.This work has been supported by FCT—Fundação para a Ciência e a Tecnologia within the R&D Units Project Scope: UIDB/05757/2020, UIDP/05757/2020, UIDB/00690/2020, UIDB/50020/2020, and LA/P/0007/2021. Adriano Silva was supported by FCT-MIT Portugal Ph.D. grant SFRH/BD/151346/2021.info:eu-repo/semantics/publishedVersio

    Environmental risk assessment in a contaminated estuary: an integrated weight of evidence approach as a decision support tool

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    Environmental risk assessment of complex ecosystems such as estuaries is a challenge, where innovative and integrated approaches are needed. The present work aimed at developing an innovative integrative methodology to evaluate in an impacted estuary (the Sado, in Portugal, was taken as case study), the adverse effects onto both ecosystem and human health. For the purpose, new standardized lines of evidence based on multiple quantitative data were integrated into a weight of evidence according to a best expert judgment approach. The best professional judgment for a weight of evidence approach in the present study was based on the following lines of evidence: i) human contamination pathways; ii) human health effects: chronic disease; iii) human health effects: reproductive health; iv) human health effects: health care; v) human exposure through consumption of local agriculture produce; vi) exposure to contaminated of water wells and agriculture soils; vii) contamination of the estuarine sedimentary environment (metal and organic contaminants); viii) effects on benthic organisms with commercial value; and ix) genotoxic potential of sediments. Each line of evidence was then ordinally ranked by levels of ecological or human health risk, according to a tabular decision matrix and expert judgment. Fifteen experts scored two fishing areas of the Sado estuary and a control estuarine area, in a scale of increasing environmental risk and management actions to be taken. The integrated assessment allowed concluding that the estuary should not be regarded as impacted by a specific toxicant, such as metals and organic compounds hitherto measured, but by the cumulative risk of a complex mixture of contaminants. The proven adverse effects on species with commercial value may be used to witness the environmental quality of the estuarine ecosystem. This method argues in favor of expert judgment and qualitative assessment as a decision support tool to the integrative management of estuaries. Namely it allows communicating environmental risk and proposing mitigation measures to local authorities and population under a holistic perspective as an alternative to narrow single line of evidence approaches, which is mandatory to understand cause and effect relationships in complex areas like estuaries.info:eu-repo/semantics/publishedVersio

    Optimized routing for people with permanent or temporary mobility disability: a case study in Viana do Castelo

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    Nowadays, it is already common to have apps to assist citizens in their mobility within a city. However, apps are usually designed for the general citizen and do not include the specificity of people with reduced mobility, temporarily or permanently, such as visually impaired people, autistic people, people in wheelchairs, among others segments. This paper illustrates a case study carried out in the city of Viana do Castelo, in Portugal, where the streets of the historic center of the city were classified in a Geographic Information System (GIS) by the City Council together with the institutions that represent each one of the considered segments. Based on this classification, the Viana+Acessivel app was developed, which is about to be made available free of charge to all citizens, and which recommends to each user the optimum route from a source to a destination, taking into account his segment. For example, visually impaired people should avoid streets where emergency vehicles can circulate and autistic people should preferably avoid streets with loud noises, among other conditions. The A -Star Algorithm and Dijkstra Algorithm were used in the app to identify the optimum route. A comparative study was made concluding that both strategies identify the optimum route and A -Star method obtains the optimum solution in a faster time. An evaluation of the app was also made in terms of its effectiveness and usability.info:eu-repo/semantics/publishedVersio

    Adverse reactions and dietary supplements

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    Over the last years, the use of dietary supplements has increased substantially. Although these products are considered as safe and can be beneficial, there are risks associated with some. Manufacturers are not required to demonstrate their safety and efficacy, so it is essential that consumers have good knowledge about dietary supplements. The attribution of injury to a specific supplement can be challenging, especially because of the multiple ingredients, the variability in quality and content, as well as the vast underreporting of adverse reactions.info:eu-repo/semantics/publishedVersio

    Collective bargaining and technological innovation in the EU15: An analysis at establishment level

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    In this paper, we study the relationship between unionisation and workplace innovation in a cross-country and multisectoral approach. This is an important and controversial issue in the industrial relation literature; however, the empirical literature on the links between innovation and unionism is rather scarce and results are mixed and ambiguous, both in theory and in empirical practice. The European Company Survey (Eurofound), with data for establishments in 15 European Union countries, is used employing a probit model. Our results contribute to the debate by showing that the adoption of technology not only increases when the company performs collective bargaining but also when the relationship between wage bargaining and innovation adoption is not linear, being more significant in cases where bargaining occurs at the regional/national levelFunding for this publication provided by the 4th edition of the Program of the Fundación Universidad Autónoma de Madrid, and co-founded by Fundación Anastasio de Graci

    Mineralogia dos filões aplito-pegmatíticos litiníferos da região de Segura

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    Na região de Segura, os filões aplito-pegmatíticos litiníferos Variscos intruíram o Complexo Xisto-Grauváquico, Câmbrico. Osfilões pegmatíticos são do tipo REL-Li e incluem-se na família dos pegmatitos LCT. A ocorrência de lepidolite, montebrasite, microlite, cassiterite e minerais do grupo da columbite primários sugerem um elevado grau de diferenciação nestes filões. A montebrasite primária é heterogénea e a lacroixite secundária ocorre nas suas zonas enriquecidas em Na. A cassietrite é zonada com alternância de zonas escuras e zonas claras e possui Mn > Fe, o que é raro. As zonas escuras são fortemente pleocróicas, com zonamento oscilatório, e possuem teores mais elevados de Nb e Ta do que as zonas claras. As inclusões de moscovite, apatite, ferrotapiolite, ixiolite e microlite foram encontradas em ambas as zonas de cassiterite, mas as exsoluções de ferrocolumbite, ferrocolumbite manganífera e manganocolumbite ocorrem nas zonas escuras

    Mesenchymal stromal cells induce regulatory T cells via epigenetic conversion of human conventional CD4 T cells in vitro

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    © 2020 The Authors. S TEM CELLS published by Wiley Periodicals LLC on behalf of AlphaMed Press. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.Regulatory T cells (Treg) play a critical role in immune tolerance. The scarcity of Treg therapy clinical trials in humans has been largely due to the difficulty in obtaining sufficient Treg numbers. We performed a preclinical investigation on the potential of mesenchymal stromal cells (MSCs) to expand Treg in vitro to support future clinical trials. Human peripheral blood mononuclear cells from healthy donors were cocultured with allogeneic bone marrow-derived MSCs expanded under xenogeneic-free conditions. Our data show an increase in the counts and frequency of CD4+ CD25high Foxp3+ CD127low Treg cells (4- and 6-fold, respectively) after a 14-day coculture. However, natural Treg do not proliferate in coculture with MSCs. When purified conventional CD4 T cells (Tcon) are cocultured with MSCs, only cells that acquire a Treg-like phenotype proliferate. These MSC-induced Treg-like cells also resemble Treg functionally, since they suppress autologous Tcon proliferation. Importantly, the DNA methylation profile of MSC-induced Treg-like cells more closely resembles that of natural Treg than of Tcon, indicating that this population is stable. The expression of PD-1 is higher in Treg-like cells than in Tcon, whereas the frequency of PDL-1 increases in MSCs after coculture. TGF-β levels are also significantly increased MSC cocultures. Overall, our data suggest that Treg enrichment by MSCs results from Tcon conversion into Treg-like cells, rather than to expansion of natural Treg, possibly through mechanisms involving TGF-β and/or PD-1/PDL-1 expression. This MSC-induced Treg population closely resembles natural Treg in terms of phenotype, suppressive ability, and methylation profile.This project received funding from: Fundação para a Ciência e Tecnologia, Portugal, under the Harvard Medical School-Portugal Program project Induction of Immune Tolerance in Human Allogeneic Hematopoietic Stem Cell Transplantation (HMSP-ICT/0001/2011) and UID/BIM/50005/2019, project funded by Fundação para a Ciência e a Tecnologia (FCT)/Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) through Fundos do Orçamento de Estado. We also acknowledge the funding received from POR Lisboa 2020 through the project PRECISE – Accelerating progress toward the new era of precision medicine (project no. 16394).info:eu-repo/semantics/publishedVersio

    In-service teacher training in Portugal: objectives, organization and impact on teacher's career

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    This paper presents a short overview of teacher´s training as considered by the Portuguese legislation: (i) initial teacher education (ITE), (ii) specialized training and (iii) in-service teacher training. A particular emphasis will be given to in-service teacher training. Nowadays, ITE corresponds to level 7 of the European Qualifications Framework (master degree). It is a career-long professional development, where research-based and in context practice are important features. Specialized training is intended to provide qualification in complementary educational functions, such as special education, school administration and inspection activities, socio-cultural animation and basic education for adults. In-service training or continuous training allows teachers to complement, deepen and update their knowledge and professional competences. Its accreditation, in what concerns involved institutions, training actions and evaluation process is centralized in the “Conselho Científico-Pedagógico da Formação Contínua” (Scientific and Pedagogical Council of in-service training) and has a direct impact in teacher’s careers, being one of the factors considered to access mobility and progression
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