753 research outputs found

    Um modelo de caracterização e avaliação ecológica para o planeamento e gestão

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    Decorrem actualmente na Universidade de Évora diversos projectos de investigação visando o desenvolvimento de metodologias de caracterização e avaliação ecológica com vista ao planeamento e gestão do território. Tais projectos, desenvolvidos a escalas complementares (1:10 000; 1:25 000 e 1:100 000), pretendem via a constituir um quadro metodológico inovador integrando num único plano de caracterização e avaliação, o plano dos sistemas de uso e o plano dos sistemas ecológicos espaciais. A necessidade de um tal sistema integrado justifica-se pela carência de um referencial de caracterização e avaliação do território com vista à articulação od sprocesos de gestão e à promoção dos objectivos de Conservação da Natureza. Com efeito, a necessidade de assegurar a preservação da biodiversidade da globalidade do território impõe uma abordagem à gestaõ do uso deste que assegure que o nível de fragmentação, de conectividade residual, e de complementaridade funcional asseguram as condições para a sustentação viável de meta-populações das espécie-objectivo. Para atingir tal objectivo importa conhecer e conseguir articular nos processos de simulação e gestão, as necessidades, processos e funções dos diferentes usos antrópicos de uma dada região e as necessidades processos, funções e condicionantes espaciais dos diferentes sistemas ecológicos susceptiveis de ocorrerem nessa região ou locais. Interessa igualmente identificat a forma como essa articulação se processa e a sua hierarquização escalar e funcional

    PATs Behavior in Pressurized Irrigation Hydrants towards Sustainability

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    [EN] Sustainability and efficiency in irrigation are essential in the management of the water- energy-food nexus to reach the Sustainable Development Goals in 2030. In irrigation systems, the reduction of energy consumption is required to improve the system efficiency and consequently the sustainability indicators of the water network. The use of pumps working as turbines (PATs) has been a feasible solution to recover the excess of energy where pressure reduction valves are installed. This research demonstrates the use of PATs under steady and unsteady conditions by analyzing the application in a real irrigation networks located in Vallada (Valencia, Spain). The study shows the possibility of recovering 44 MWh/year using PATs installed upstream of the irrigation hydrants. The real behavior of the PAT operation in a stand¿alone recovery energy solution allowed analysis of the flow, head and efficiency variation as a function of the rotational speed, as well as the minimum capacitance to self-excite the generator and the resistive load of the electrical circuit. The PAT limit is examined in terms of the overpressure induced by a fast closure manoeuvre of hydrants, and the runaway conditions due to the disconnection from the electrical load.This work was supported by FCT-Foundation for Science and Technology, through CERIS, IP, and IDMEC, under LAETA, project UIDB/50022/2020. This research is also supported by the Program to support the academic career of the faculty of the Universitat Politècnica de València 2019/2020 in the project A STEP AHEAD IN SUSTAINABILITY OF WATER SYSTEMS FOR THE ENERGY TRANSITION IN COMMUNITIES of the Modesto Pérez- Sánchez. The authors wish to thank the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA Fluids PROGRAMME 2014-2020 and CERIS, the Hydraulic Laboratory, for the support in the conceptual developments and the experiments on PATs.Pérez-Sánchez, M.; Fernandes, JF.; Costa Branco, P.; López Jiménez, PA.; Ramos, HM. (2021). PATs Behavior in Pressurized Irrigation Hydrants towards Sustainability. Water. 13(10):1-17. https://doi.org/10.3390/w13101359S117131

    Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning

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    [EN] The use of pump working as turbine (PAT) was identified by many researchers as a way to improve the energy efficiency in the water systems. However, the majority of the researches consider the hydraulic machine connected to the electrical grid, which may not fit best when these recovery systems are located in rural or remote areas. To improve the efficiency in these recovery systems for rural areas, this research contributes for a further study and optimization of the off-grid PAT systems with induction generators. The current manuscript proposes a methodology to obtain the best efficiency of the PAT-SEIG (Self-Excited Induction Generator) system when operating under different speeds and loads. For these systems, the selection of capacitors for the SEIG is critical to maximizing the energy efficiency. A methodology is proposed to estimate and select the correct SEIG model parameters and, thus, compute the best capacitor values to improve the PAT-SEIG energy efficiency. Special attention is given to the impact the SEIG parameters have in the efficiency of the recovery system. The accuracy of the analytical model improved, reducing the error between analytical and experimental results from 50.8% (for a model with constant parameters) to 13.2% (with parameters changing according to the operating point of the system). These results showed an increase of the overall PAT system efficiency from 26% to 40% for the analyzed case study.This work was supported by FCT, through IDMEC, under LAETA, project UID/EMS/50022/2019 and the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA PROGRAMME 2014-2020 and CERIS (CEHIDRO-IST), the Hydraulic Laboratory, for experiments on PATs.Fernandes, JF.; Pérez-Sánchez, M.; Ferreira, F.; López Jiménez, PA.; Ramos, HM.; Costa Branco, P. (2019). Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning. Energy Conversion and Management. 183:391-405. https://doi.org/10.1016/j.enconman.2019.01.016S39140518

    Congener patterns of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls as a useful aid to source identification during a contamination incident in the food chain

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    Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) are still considered among the most important groups of contaminants in the food chain. Self-control by food producers and official control by authorities are important activities that allow contaminant sources to be traced and promote further reduction in food and feed levels. Strict but feasible maximum levels were set by the EU Commission for food and feed to support this strategy, as well as action levels and thresholds. When products exceed these levels, it is important to trace the source of contamination and take measures to remove it. Congener patterns of PCDD/Fs and PCBs differ between sources and are important tools for source identification. Therefore, patterns associated with different sources and incidents relating to various feed matrices and certain agricultural chemicals were collated from published scientific papers, with additional ones available from some laboratories. The collection was evaluated for completeness by presentations at workshops and conferences. Primary sources appear to derive from 5 categories, i) by-products from production of organochlorine chemicals (e.g. PCBs, chlorophenols, chlorinated pesticides, polyvinyl chloride (PVC)), ii) the result of combustion of certain materials and accidental fires, iii) the use of inorganic chlorine, iv) recycling/production of certain minerals, and v) certain naturally occurring clays (ball clay, kaolinite). A decision tree was developed to assist in the identification of the source

    Long-term efficacy and safety of erenumab results from 64 weeks of the LIBERTY study

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    ObjectiveTo report the efficacy and safety of erenumab among patients with episodic migraine (EM) whowere unsuccessful on 2 to 4 preventive treatments observed at week 64 of the open-label extension phase (OLEP) of A Study Evaluating the Effectiveness of AMG 334 Injection in Preventing Migraines in Adults Having Failed Other Therapies (LIBERTY) study (ClinicalTrials.gov NCT03096834).MethodsTheOLEP, evaluatingmonthly erenumab 140 mg for 3 years, enrolled 240 patients who completed the double-blind treatment phase (DBTP) of 12 weeks during which they received placebo or erenumab 140 mg subcutaneous injections every 4 weeks as monotherapy. Efficacy outcomes were evaluated through the initial 52weeks ofOLEP (fromDBTP baseline to total 64weeks) in the overall population, patients receiving erenumab in DBTP, and patients from the DBTP placebo arm who switched to erenumab in OLEP. Endpoints included reduction of >= 50% in monthly migraine days (MMD) from DBTP baseline and change inMMDfrom DBTP baseline, Headache Impact Test score, and Migraine Physical Function Impact Diary score (Physical Impairment and Everyday Activities).ResultsAltogether, the week 52 visit of theOLEP was completed by 204 of 240 (85.0%) patients. Among patients continuing erenumab, the 50% responder rate increased from 29.9% at weeks 9 to 12 to 44.3% at weeks 61 to 64. The 50% responder rate in patientswho initiated erenumab in theOLEP remained higher in the OLEP (50.0% at week 61-64) than during DBTP (14.2% at weeks 9-12) compared to patients in continuous erenumab arm. In the OLEP, the 50% responder rate for the overall population increased from weeks 13 to 16 until weeks 37 to 40 and then remained stable through weeks 61 to 64. Patients treated with erenumab in DBTP showed sustained effects on all efficacy outcomes; those initiating erenumab in theOLEP demonstrated continued improvement from week 13 onward. Adverse events (AEs) were reported, considering both treatment groups, by approximate to 80.8% (serious AEs by 6.7%), 76.3% (5.9%) in the continuing erenumab arm, and 85.2% (7.4%) in those starting erenumab in OLEP. No deaths were reported.ConclusionsIn patients with EM who were unsuccessful on 2 to 4 prior preventive treatments, the LIBERTY study demonstrated sustained efficacy on erenumab monotherapy treatment through 64 weeks in both treatment arms. Safety of erenumab was consistent with that observed in previous clinical trials.Paroxysmal Cerebral Disorder

    The Fueling and Evolution of AGN: Internal and External Triggers

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    In this chapter, I review the fueling and evolution of active galactic nuclei (AGN) under the influence of internal and external triggers, namely intrinsic properties of host galaxies (morphological or Hubble type, color, presence of bars and other non-axisymmetric features, etc) and external factors such as environment and interactions. The most daunting challenge in fueling AGN is arguably the angular momentum problem as even matter located at a radius of a few hundred pc must lose more than 99.99 % of its specific angular momentum before it is fit for consumption by a BH. I review mass accretion rates, angular momentum requirements, the effectiveness of different fueling mechanisms, and the growth and mass density of black BHs at different epochs. I discuss connections between the nuclear and larger-scale properties of AGN, both locally and at intermediate redshifts, outlining some recent results from the GEMS and GOODS HST surveys.Comment: Invited Review Chapter to appear in LNP Volume on "AGN Physics on All Scales", Chapter 6, in press. 40 pages, 12 figures. Typo in Eq 5 correcte
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