The intermittent characteristics of microgrids (MGs) have motivated the development of energy management systems (EMSs) in order to optimize the use of distributed energy resources. In current studies, the implementation of an EMS followed by experimental-based analyses for both grid-tied and stand-alone MG operation modes is often neglected. Additionally, the design of a management strategy that is capable of preserving the storage device lifetime in battery-based MGs using a power gradient approach is hardly seen in the literature. In this context, this work presents the application of an EMS for battery-based MGs which is suitable for both grid-tied and stand-alone operation modes. The proposed EMS is formulated as an optimal power flow (OPF) problem using the-constraint method which is responsible for computing the current references used by the EMS to control the MG sources. In the optimization problem, the total generation cost is minimized such that the active power losses are kept within pre-established boundaries, and a battery management strategy based on power gradient limitation is included. Finally, the effectiveness of the proposed EMS is evaluated by two scenarios which enable detailed analyses and validation. The first considers a dispatchable and a non-dispatchable source, whereas the second a dispatchable source and a storage device. The experimental results showed that the proposed EMS is efficient in both operation modes and is also capable of smoothing the state of charge (SoC) behavior of the storage device. INDEX TERMS Battery power gradient, distributed generation, energy management system, microgrid, optimal power flow, storage device.
In Brazil new varieties of citrus were selected along the years, but none sensory analysis is usually made to verify the acceptance as one of the bottleneck for fresh citrus juice industry and before the commercial release. We have evaluated the response of consumers (n=62) for eight new hybrids of the crossing between sweet orange and mandarin in five sensory attributes and used analysis of variance Tukey's procedure (HSD) and internal preference mapping for the data processing. The results were compared in relation to their standard physical-chemical characteristics and with commercial varieties: Murcott tangor (Citrus sinensis (L.) Osbeck x Citrus reticulata Blanco), Pera sweet orange (Citrus sinensis (L.) Osbeck, Cravo mandarin (Citrus reticulata Blanco). Hybrids TM x LP 222 and TC x LP 5 are candidates to become variety and TM x LP 94 was chosen for new sensory analysis. Flavor featured as the most important parameter for orange juice and some hybrids with adequate physical-chemical parameters presented low acceptance, while others with inadequate parameters showed good acceptability, what suggests a new way to fruit selection.
Considering that the root-knot nematode Meloidogyne exigua has caused great yield losses to coffee production in Brazil, this study aimed to determine whether the penetration and the reproduction events of this nematode on the roots of plants from two coffee cultivars with different levels of basal resistance to this nematode could be affected by silicon (Si). Coffee plants from the cultivars Catuaí and IAPAR 59, which are susceptible and resistant, respectively, to M. exigua, were grown in pots containing Si-deficient soil that was amended with either calcium silicate (+Si) or calcium carbonate (-Si). The Si concentration on the root tissue significantly increased by 159 and 97% for the +Si plants from the cultivars Catuaí and IAPAR 59, respectively, compared to the -Si plants of these cultivars. The population of M. exigua, the number of galls and the number of eggs were significantly reduced on the roots of the +Si plants of the cultivars Catuaí and IAPAR 59 compared to the -Si plants of these cultivars. It was concluded that the development and reproduction events of M. exigua were negatively impacted on the roots of coffee plants supplied with Si.
Formerly in the literature, a new interleaved-based boost converter was devised for multiple input voltage sources purposes. Nevertheless, when only a single input voltage source is connected to the 2-phase version of this converter, it can be seen as a compact interleaved boost with voltage multiplier (cIBVM). A brief description of cIBVM operation as well as the ideal modeling are already discussed in the literature for one specific range of duty-cycle. In this paper, we provide further analysis by considering the conduction and dynamic losses on the analytical model with a single voltage source. Moreover, we also obtained the analytical model considering the entire duty-cycle range showing that the converter can perform either a quadratic, a double or even a symmetric voltage gain depending solely on the switching strategy adopted. The analytical model was obtained using state-space representation and both its accuracy and the effectiveness of the results were validated from a Simulink-based cross validation and a complete sequence of experimental tests. INDEX TERMS DC-DC converters, high step-up conversion ratio, multiple operation modes.
A B S T R A C TConsidering the relevant importance of guava (Psidium guajava) in Northeastern Brazil along with the benefits of neem cake amendments on soil characteristics, this work evaluated the effects of neem cake on chemical attributes of a Regosol under irrigated guava orchard in an alluvial valley of Pernambuco semi-arid region. Evaluations were carried out in two areas (area 1 -with neem cake; area 2 -without neem cake) at three periods: before the first application of neem cake, 90 days after the first application and 90 days after the second application. A regular 8 × 6-point grid was designed in each area and the soil was sampled for total organic carbon, pH, soluble salts (Na + , K + , Ca 2+ and Mg 2+ ) and total nitrogen contents, as well as soil C-CO 2 evolution rate in soil. Geostatistical analysis pointed out the spherical model as the best fit to the studied variables, followed by the Gaussian model, with ranges from 12 to 60.5 m. Neem cake incorporation increased spatial variability and the contents of the evaluated soil chemical attributes.Variabilidade espacial de atributos químicos em Neossolo no manejo da goiabeira com nim no semiárido R E S U M O Considerando a importância do cultivo de goiabeiras (Psidium guajava) para o nordeste do Brasil e os benefícios da aplicação da torta de nim nas características do solo, avaliou-se o efeito da aplicação de torta de nim nos atributos químicos de um Neossolo Regolítico cultivado com goiabeiras irrigadas no semiárido de Pernambuco. Para as avaliações foram usadas duas áreas (área 1 -com nim; área 2 -sem nim) e três períodos, antes da aplicação do nim, 90 dias após a primeira aplicação e 90 dias após a segunda aplicação; assim, 96 amostras de solo foram coletadas em duas malhas regulares de 8 × 6 pontos amostrais e realizadas análises do teor de carbono orgânico total, pH, teores de sais solúveis (Na + , K + , Ca 2+ e Mg 2+ ), nitrogênio total e taxa de evolução C-CO 2 do solo. O modelo esférico foi o que melhor se ajustou às variáveis estudadas seguido pelo gaussiano, com alcances que variaram de 12 a 60,5 m. A incorporação da torta de nim aumentou a variabilidade espacial e a oferta dos atributos de solo estudados.
La ﬂora nativa posee un enorme potencial paisajístico que ha sido poco explorado. En el presente trabajo se han estudiado aspectos relacionados con las semillas y comportamiento germinativo de tres especies vegetales nativas del centro - norte santafesino con potencial ornamental priorizadas para su introducción a la producción en viveros en el marco de las acciones del Programa de Documentación, Conservación y Valoración de la Flora Nativa (PRODOCOVA). Las especies en estudio corresponden a “Sangre drago” Croton urucurana Baill., “Horquetero” Tabernaemontana catharinensis A. DC. y “Ojo de muñeca” Paullinia elegans Cambess. Para C. urucurana se halló una temperatura óptima a temperaturas alternantes de 20-30 °C, mientras que para P. elegans y T. catharinensis, temperatura constante a 25 °C determinó el mayor porcentaje de germinación. Se identiﬁcaron para todas las especies el momento para el recuento inicial y ﬁnal del porcentaje de germinación. Adicionalmente se observó que semillas de P. elegans son recalcitrantes. Estos resultados son de gran utilidad para la introducción a cultivo de las especies en estudio.
One of the key technologies in a high power microwave system is the Pulsed Power Conditioning System (PPCS). For a system driven by an explosive flux compression generator, the PPCS may consist of an energy storage inductor, a fuse type opening switch and a sharpening spark gap. This paper presents the investigation of a PPCS with a pulse transformer. Before the construction of a prototype, the behavior of the PPCS has been simulated using the PSpice circuit simulation code. A transformer with a primary inductance L,=3.5 pH, secondary inductance L,=85 pH, and a coupling coefficient K=0.75, was designed and used in our experiments. The transformer was designed with two coaxial windings. Simulation results as well as experimental waveforms are shown. I. EXPERIMENTAL SETUPFigure 1 shows a drawing of the experimental setup. The system consists of a primary storage capacitor (Maxwell 16.5 pF, 45 kV), a triggered closing switch, the pulse transformer, a fuse, a peaking gap and a 13 R resistive load.For all of the results reported here, the peaking gap was closed, in order to observe the heating phase of the fuse. The fuse section, consisting of the lower fuse-T and the upper fuse cylinder, as well as the enclosure of the peaking gap were filled with an SFs -Air mixture. The coaxial enclosure of the load resistor was filled with transformer oil. The fuse was constructed of a filament of thin copper wires. The fuse wires and the support structure were embedded in fine sand used for sandblasting (Potters Industries, 2W580) to aid in the suppression of the arc after the explosion of the fuse.To analyze the performance of the system, we measured the voltage on the output of the triggered closing switch located directly behind the primary storage capacitor. We also measured the currents at three positions in the system using Pearson current monitors. A Pearson monitor model 1423 was used to measure the current on the input of the primary of the transformer. The currents in the fuse and in the load were measured with Pearson monitors model 4418 and 4997, respectively.Figure 1. Drawing of the Complete Pulse Forming System.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.