Preliminary insight into age and growth of the Iberian chub (Leuciscus pyrenaicus) in the sorraia system

An investigation of age and growth in the Iberian chub Leuciscus pyrenaicus Gunther, 1868 revealed a seasonal growth pattern, with annulus formation restricted to a short period of the year (May/June). Maximum ages were 6+ for both sexes. During and after the third year females grew at faster rates than males, and the most important decrease in growth rates occurred between age I! and Ill in males and between age Ill and IV in females. Mean back-calculated standard lengths of III and IV age classes were significantly higher in the River Sorraia. Mean weights of I and II age classes were higher in Sor stream whereas the individuals from III ad IV age classes were heavier in the River Sorraia. Shifts in growth rates arc discussed in relation to seasonal and spatial variations in the environmental conditions as well as to sexual maturity

Vanadium Redox Flow Battery Modelling and PV Self-Consumption Management Strategy Optimization

This work aims to maximize the photovoltaic solar electricity’s self-consumption, through the development and validation of an equivalent electric model of a vanadium redox flow battery and its implementation in an energy management strategy. The first phase of the work presents the modelling of the 5.0 kW/60 kWh VRFB integrated in a solar photovoltaic microgrid - 3.5 kWp monocrystalline plus 3.2 kWp polycrystalline technology - at the University of Évora. The model is based in the equivalent electric circuit model built upon the consulted bibliographic references allowing to calculate the battery parameters on the desired power. It considers the auxiliary power consumption and operational parameters and despite its simplicity attains for a good match with experimental results. Upon its validation, the model is further enhanced as to better describe the VRFB real response in its regular operating conditions. Assessment of the enhanced model is based on key performance indicators such as selfconsumption rate, rate of battery usage or electric grid independence. In this work an approach to best fit the battery modelling and simultaneously the energy management strategy for a PV+VRFB system is presented, based on actual operating conditions and on a prescribed EMS goal

An approach to implement PV Self-Consumption and Ramp-Rate Control Algorithm using a Day-to-Day Forecast battery charging, with a Vanadium Redox Flow Battery

The variability of the solar resource is mainly caused by cloud passing, causing rapid power fluctuations on the output of photovoltaic (PV) systems. The fluctuations can negatively impact the electric grid, and smoothing techniques can be used as attempts to correct it. However, the integration of a PV+storage to deal with the extreme power ramps at a domestic/services scale is not explored in the literature, neither its effective combination with other energy management strategies (EMSs). This work is focused on using a battery energy storage unit to control the power output of the PV system, maintaining the ramp rate (RR) within a non-violation limit and within a battery state of charge (SoC) range, appropriate to perform this RR management at the domestic/services scale. For this purpose, the authors explore the vanadium redox flow battery (VRFB) technology. Based on model simulation, key-performance indicators (KPI) are studied and improved, and finally, experimental validation is carried out. A comparison among three EMSs is made: a self-consumption maximization (SCM), a SCM with ramp-rate control (SCM+RR), and the last strategy performing also night battery charging based on the day ahead weather forecast (SCM+RR+WF). The weather forecast allowed the battery SoC control, preparing it to carry out the RR control the next day. The results show that SCM+RR+WF, especially in wintertime, is an excellent approach to manage PV+battery systems. This strategy successfully controlled 100 % of the violating power ramps, obtaining also a self-consumption ratio (SCR) of 59 %, and a grid-relief factor (GRF) of 61 %.Comment: Keywords: PV solar energy; energy storage; self-consumption; ramp rate; VRF

Economic and Energetic Assessment of a Hybrid Vanadium Redox Flow and Lithium-ion batteries considering different Energy Management Strategies

Hybrid energy storage systems (HESS) combine different energy storage technologies aiming at overall system performance and lifetime improvement compared to a single technology system. In this work, control combinations for a vanadium redox flow battery (VRFB, 5/60 kW/kWh) and a lithium-ion battery (LIB, 3.3/9.8 kW/kWh) are investigated for the design of a HESS. Four real-time energy management/power allocation scenarios are considered for the operation of the hybrid storage solution through a 15-year economic and energetic analysis. The results obtained for each scenario are compared with a single technology battery performance. In the definition of the scenarios, real electricity generation is considered from two solar photovoltaic installations (3.2 kWp and 6.7 kWp) and an estimated representative load of a services building. HESS performance is evaluated through specific energy and economic key performance indicators. The results obtained indicate that the use of customized energy management strategies (EMSs) renders the VRFB and LIB characteristics complementary, besides enhancing the competitiveness of VRFB, as a single technology. Moreover, the HESS management impacts the seasonality factor, contributing to the overall electric system smart management.Comment: 19 pages, 7 figures, research pape

Temporal variation of bacterial population and response to physical and chemical parameters along a petrochemical industry wastewater treatment plant

The petrochemical industry has played a considerable role in generation and release of waste in the environment. Activated sludge and facultative lagoons are commonly used for domestic and industrial wastewater treatment due to their low-cost and minimal need for operational requirements. Microorganisms present in wastewater treatment plant (WWTP) are responsible for most nutrient removal. In this study, microbiological and physicochemical parameters were used to estimate changes in bacterial community in a petrochemical industrial WWTP. The activated sludge was the place with higher heterotrophic bacterial quantification. Denitrifying bacteria was reduced at least 5.3 times throughout all collections samples. We observe a decrease in the total Kjeldahl nitrogen, oxygen demand and phosphate throughout the WWTP. In this work, we also use Matrix-Assisted Laser Desorption Ionisation-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for bacteria isolates identification comparing with 16S rDNA sequencing. The MALDITOF MS allowed the identification of 93% of the isolates and only 5% show different results from 16S rDNA sequencing showing that the MALDI-TOF MS can be a tool for identifying environmental bacteria. The observation of microbial community dynamics in the WWTP is important in order to understand the functioning of the ecological structure formed in a specific environment

A influência da origem social na probabilidade de concluir os diferentes cursos de ensino superior

The article analyzes the impact of parental schooling and family income on students’ chances of obtaining a college degree, considering variation in the economic return of undergraduate degrees. We rely on data from Enade to estimate logistic regression models. The results show that, in general, students with more educated parents have a greater likelihood of obtaining a degree. However, in public institutions, parental schooling has no effect on the odds of finishing tertiary education.  Furthermore, parents’ schooling exerts greater influence on the odds of conclusion of those degrees providing greater economic rewards in the job market. Family income increases students’ chances of obtaining a degree in both private and public institutions. Also, we find that the effect of family income is the same, regardless of the economic returns of students’ degree.O artigo analisa a influência da escolaridade do pai e da renda familiar nas chances de conclusão do ensino superior no Brasil, considerando as diferenças no retorno econômico dos cursos de graduação. Para realizar a análise, utilizamos microdados do Enade e calculamos modelos logísticos. Os resultados principais mostram que, no geral, ter pais com escolaridade mais alta aumenta as chances de conclusão dos cursos. No entanto, no setor público, a escolaridade do pai não tem efeito sobre a probabilidade de concluir o ensino superior. Além disso, a escolaridade do pai exerce maior influência nas chances de conclusão dos cursos de alto retorno econômico. A renda familiar aumenta as chances de conclusão do curso, tanto no setor público quanto no setor privado da educação. Também encontramos efeitos similares para a renda familiar independente do retorno econômico dos curso

The influence of social origin on the probability of obtaining a college degree

O artigo analisa a influência da escolaridade do pai e da renda familiar nas chances de conclusão do ensino superior no Brasil, considerando as diferenças no retorno econômico dos cursos de graduação. Para realizar a análise, utilizamos microdados do Exame Nacional de Desempenho de Estudantes (Enade) e calculamos modelos logísticos. Os resultados principais mostram que, no geral, ter pais com escolaridade mais alta aumenta as oportunidades de conclusão dos cursos. No entanto, no setor público, a escolaridade do pai não tem efeito sobre a probabilidade de concluir o ensino superior. Além disso, a escolaridade do pai exerce maior influência nas chances de conclusão dos cursos de alto retorno econômico. A renda familiar aumenta as probabilidades de conclusão do curso, tanto no setor público como no setor privado da educação. Também encontramos efeitos similares para a renda familiar, independente do retorno econômico dos cursos.The article analyzes the impact of parental schooling and family income on students’ chances of obtaining a college degree, considering variation in the economic return of undergraduate degrees. We rely on data from National Student Performance Exam (Enade) to estimate logistic regression models. The results show that, in general, students with more educated parents have a greater likelihood of obtaining a degree. However, in public institutions, parental schooling has no effect on the odds of finishing tertiary education. Furthermore, parents’ schooling exerts greater influence on the odds of conclusion of those degrees providing greater economic rewards in the job market. Family income increases students’ chances of obtaining a degree in both private and public institutions. Also, we find that the effect of family income is the same, regardless of the economic returns of students’ degree

Feeding behaviour of Barbus Bocagei assessed under a spatio-temporal approach

The feeding behaviour of Barbus bocagei was assessed in a lowland system by a two years survey Of two contrasting sites also talking into account, for the first time diurnal changes of fish diet and benthos availability

Techno-economic evaluation of the Portuguese PV and energy storage residential applications

In the residential sector, energy micro-generation and its intelligent management have been creating novel energy market models, considering new concepts of energy usage and distribution, in which the prosumer has an active role in the energy generation and its self-consumption. The configuration of a solar photovoltaic system integrating energy storage in Portugal is yet unclear in the technical, energetic and economic point of view. The energy management jointly with the battery operation have great influence in the system configuration’s profitability value. The present work evaluates different photovoltaic system configurations with and without batteries for the normal low voltage Portuguese consumer profile with 3.45 kVA contracted power. This study presents the systems’ cost-effectiveness, within the Portuguese legislation, which promotes and enables policies for self-generation and self-consumption. The analysis is done in three different representative locations of the country, considering distinct electric tariffs. This work shows that despite the solar photovoltaic system without electricity storage is already economically viable, its integration with storage is not in most of the assessed configurations. However, it is shown that it is already possible to find profitable PV + battery configurations, even potentially improving these positive scenarios if a good energy management strategy is considered