Análise do controle droop em uma microrrede monofásica isolada com geração fotovoltaica

Dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáA estratégia de controle por decaimento, também denominada de controle droop, é uma das mais estudadas quando o assunto é Microrredes (MRs). Esta técnica possui algumas vantagens, destacando-se o efetivo compartilhamento de potência e a ausência de links de comunicação entre os inversores. Desse modo, reduz-se a complexidade, melhora-se a flexibilidade e a redundância do sistema, além de facilitar a expansão da capacidade da MR devido à característica plug-and-play. O objetivo geral deste trabalho consiste em analisar o controle droop em uma MR isolada, em Corrente Alternada (CA) monofásica, com geração solar fotovoltaica, na ferramenta computacional Simulink do software MATLAB®. A MR modelada neste estudo integra três inversores monofásicos em paralelo, os quais trabalham em conjunto compartilhando as cargas da MR. Dois desses inversores possuem baterias como fontes de energia, nos quais é aplicado o controle droop. Por sua vez, o terceiro possui como fonte de energia uma fileira de módulos fotovoltaicos, com a função de injetar potência na MR. Nesse sentido, o terceiro inversor não participa da estratégia de controle droop, apenas mantém a sua topologia de controle usual. A MR modelada e simulada no MATLAB® corresponde a um sistema monofásico com tensão eficaz 230 V e frequência 50 Hz. As baterias utilizadas são de 400 V e a fileira é composta de 5 módulos fotovoltaicos de 220 Wp cada. O controle droop é projetado para que a frequência angular na MR varie no máximo 2% do valor nominal e a magnitude de tensão varie no máximo 5% do valor nominal. Com objetivo de validar o controle proposto, a MR foi simulada considerando diferentes configurações de carga e produção. Foram testadas cargas resistivas, capacitivas e indutivas, além da variação da produção dos módulos fotovoltaicos, com a alteração da irradiância e temperatura. Também foi possível analisar a injeção de potência reativa pelo inversor fotovoltaico. O controle droop desenvolvido mostrou-se eficaz para os cenários simulados, mantendo os níveis de frequência angular e magnitude de tensão na MR próximos aos desejados. Ocorreu um compartilhamento eficiente de potência ativa e reativa pelos inversores, independentemente da condição de carga e produção.The strategy of droop control is one of the most studied when the subject is microgrids. This technique has some advantages, notably the effective power sharing and the absence of communication links between the inverters. This reduces complexity, improves system flexibility and redundancy, and facilitates expansion of microgrid capacity due to the plug-and-play feature. The general objective of this work is to analyze the droop control in an isolated microgrid, in single phase AC, with photovoltaic solar generation, in the Simulink computational tool of the MATLAB® software. The microgrid modeled in this study consists of three single-phase parallel inverters, which work together sharing the microgrid loads. Two inverters have batteries as power sources, to which droop control is applied. In turn, the third inverter has as its power source a row of photovoltaic modules, with the function of injecting power into the microgrid. In this sense, the third inverter does not participate in the droop control strategy, only maintains its usual control topology. The MATLAB® modeled and simulated microgrid corresponds to a system with effective voltage 230 V and frequency 50 Hz. The batteries used are 400 V and the row consists of 5 photovoltaic modules of 220 Wp each. The droop control is designed so that the angular frequency in the microgrid varies a maximum of 2% of the nominal value and the voltage magnitude varies a maximum of 5% of the nominal value. In order to validate the proposed control, the microgrid was simulated considering different load and production configurations. Resistive, capacitive and inductive loads were tested, as well as the photovoltaic modules production variation, with the irradiance and temperature changes. It was also possible to analyze the reactive power injection by the photovoltaic inverter. The developed droop control was effective for the simulated scenarios, keeping the angular frequency levels and voltage magnitude in the microgrid close to the desired ones. An efficient sharing of active and reactive power occurred by the inverters, regardless of the load and production condition

Evaluation of the maxillary premolar roots dissociation using radiographic holders with conventional and digital radiography

This in vivo study evaluated the dissociation quality of maxillary premolar roots combining variations of vertical and horizontal angulations by using X-ray holders (Rinn -XCP), and made a comparison between two types of intraoral radiography systems - conventional film (Kodak Insight, Rochester, USA) and digital radiography (Kodak RVG 6100, Kodak, Rochester, USA). The study sample was comprised of 20 patients with a total of 20 maxillary premolars that were radiographed, using the paralleling angle technique (GP), with a 20º variation of the horizontal angle (GM) and 25º variation of the horizontal angle combined with 15º vertical angle (GMV). Each image was independently analyzed by two experienced examiners. These examiners assigned a score to the diagnostic capability of root dissociation and the measurement of the distance between the apexes. Statistical data was derived using the Wilcoxon Signed Rank test, Friedman and T test. The means of the measured distances between buccal and lingual root apexes were greater for the GMV, which ranged from 2.3 mm to 3.3 mm. A statistically significant difference was found between GM and GMV when compared to GP with p < 0.01. An established best diagnostic dissociation roots image was found in the GMV. These results support the use of the anterior X-ray holders which offer a better combined deviation (GMV) to dissociate maxillary premolar roots in both radiography systems

The logistics management in the sizing of the fleet of containers per ships in dedicated route - The use of computer simulation: A Brazilian shipping company case

The aim of this paper is provide the use of the simulation in the  to manage one important point in the logistics systems to shipping companies that is the imbalance of containers, movement of empty containers from surplus ports to deficit ports.From a survey of data from a shipping company operating in Brazil, at various ports, it was possible to model and simulate the needs in six major domestic ports of empty and full containers and seek to meet demand in the shipping market, reducing storage of containers and maintaining the level of excellence in service.Based on the discrete event simulation it was possible to analyze the problem of empty and full containers at the ports in the maritime transportation system. It was possible study the imbalance situation in the ports e provide one tool the companies to manage yours service.The data are confined to one company located in São Paulo and operating in Brazil at maritime transportation.The research shows that the imbalance problem between full and empty containers is a real case to all companies in the maritime transportation and can have effective solutions using discrete event simulation.To have excellent supply chain management it is important to have also one effective transportation system. This paper contributes to research in the inbound and outbound part of the supply chain management

VENTILAÇÃO DE ALTA FREQUÊNCIA OSCILATÓRIA EM RECÉM-NASCIDOS PREMATUROS

Introduction: Premature newborns with respiratory dysfunctions are often submitted to mechanical ventilation, which is essential in the management of these patients, but can induce pulmonary lesions. To reduce this risk, High Frequency Oscillatory Mechanical Ventilation (HFOV) has been used as a safer ventilatory strategy when compared to conventional modes. Method: Integrative review of randomized clinical trials with the main outcome analysis of the effects of HFOV in comparison with conventional ventilatory modes in preterm infants born before 37 weeks. Results: The 23 articles included in this study suggest that HFOV decreases the risk of lung injury and exogenous surfactant use, increases oxygenation area, presents faster improvement of hypoxemia, and reduces the time patients are on mechanical ventilation and oxygen therapy. Conclusion: The main limitation lies in the small sample size of most studies, although it is possible to assume that HFOV is a safe and effective mode, which presents favorable results when compared to other ventilatory modes. For a more specific analysis, further studies on the incidence of intracranial hemorrhage and its use in newborns with congenital heart disease would be needed.Introducción: Los recién nacidos prematuros con disfunciones respiratorias suelen ser sometidos a ventilación mecánica, que es esencial en el manejo de estos pacientes, pero puede inducir lesiones pulmonares. Para reducir este riesgo, se ha utilizado la ventilación mecánica oscilatoria de alta frecuencia (VOAF) como una estrategia ventilatoria más segura en comparación con los modos convencionales. Método: Revisión integradora de ensayos clínicos aleatorizados con el análisis de los resultados principales de los efectos de la VOAF en comparación con los modos ventilatorios convencionales en recién nacidos prematuros antes de las 37 semanas. Resultados: Los 23 artículos incluidos en este estudio sugieren que la VOAF disminuye el riesgo de lesión pulmonar y el uso de surfactantes exógenos, aumenta el área de oxigenación, presenta una mejoría más rápida de la hipoxemia y reduce el tiempo que los pacientes están en ventilación mecánica y oxigenoterapia. Conclusión: La principal limitación radica en el pequeño tamaño muestral de la mayoría de los estudios, aunque es posible suponer que la VOAF es un modo seguro y eficaz, que presenta resultados favorables en comparación con otros modos ventilatorios. Para un análisis más específico, se necesitarían más estudios sobre la incidencia de hemorragia intracraneal y su uso en recién nacidos con cardiopatías congénitas.Recém-nascidos prematuros com disfunções respiratórias frequentemente são submetidos a ventilação mecânica, esse recurso é essencial no manejo desses pacientes, mas pode induzir lesões pulmonares. Para diminuir esse risco, a Ventilação Mecânica de Alta Frequência Oscilatória (HFOV) vem sendo utilizada como uma estratégia ventilatória mais segura quando comparada aos modos convencionais. Método: Revisão integrativa de ensaios clínicos randomizados com desfecho principal a análise dos efeitos da HFOV em comparação aos modos ventilatórios convencionais em prematuros nascidos antes das 37 semanas. Resultados: Os 23 artigos incluídos nesse estudo, sugerem que o HFOV diminui o risco de lesões pulmonares e uso de surfactante exógeno, aumenta área de oxigenação, apresenta melhora mais rápida da hipoxemia, diminuindo o tempo dos pacientes em ventilação mecânica e oxigenoterapia. Conclusão: A principal limitação encontra-se no tamanho amostral pequeno de grande parte dos estudos, apesar disso, é possível assumir que o HFOV é um modo seguro e eficaz, que apresenta resultados favoráveis quando comparado a outros modos ventilatórios. Para uma análise mais específica, seriam necessários mais estudos sobre a incidência de hemorragia intracraniana e sua utilização em recém-nascidos com cardiopatia congênita.Introdução: Recém-nascidos prematuros com disfunções respiratórias frequentemente são submetidos a ventilação mecânica, esse recurso é essencial no manejo desses pacientes, mas pode induzir lesões pulmonares. Para diminuir esse risco, a Ventilação Mecânica de Alta Frequência Oscilatória (HFOV) vem sendo utilizada como uma estratégia ventilatória mais segura quando comparada aos modos convencionais. Método: Revisão integrativa de ensaios clínicos randomizados com desfecho principal a análise dos efeitos da HFOV em comparação aos modos ventilatórios convencionais em prematuros nascidos antes das 37 semanas. Resultados: Os 23 artigos incluídos nesse estudo, sugerem que o HFOV diminui o risco de lesões pulmonares e uso de surfactante exógeno, aumenta área de oxigenação, apresenta melhora mais rápida da hipoxemia, diminuindo o tempo dos pacientes em ventilação mecânica e oxigenoterapia. Conclusão: A principal limitação encontra-se no tamanho amostral pequeno de grande parte dos estudos, apesar disso, é possível assumir que o HFOV é um modo seguro e eficaz, que apresenta resultados favoráveis quando comparado a outros modos ventilatórios. Para uma análise mais específica, seriam necessários mais estudos sobre a incidência de hemorragia intracraniana e sua utilização em recém-nascidos com cardiopatia congênita

Ex vivo analysis of root canal cleaning using Endo-PTC associated to NaOCl and different irrigant solutions

The aim of this study was to assess qualitatively, by means of SEM images, the cleaning of the dentin walls of root canals after chemical-surgical preparation using Endo-PTC cream with 0.5% and 1% sodium hypochlorite and different final irrigating solutions. Seventy-two single-rooted human teeth were divided into eight groups and prepared using Endo-PTC cream with sodium hypochlorite (NaOCl) at different concentrations, and irrigated with NaOCl at different concentrations. Final irrigation was performed with either EDTA-T or EDTA-C. The best results were obtained with Group 1, followed by Groups 5, 2, 7, 8, 3, 6 and 4. We can conclude that the use of 0.5% NaOCl during instrumentation and final flush of the root canals was more efficient in cleaning than was 1% sodium hypochlorite. EDTA-T was more efficient in removing smear layer than EDTA-C, and the cervical third presented better cleaning of the root canal walls than did the middle third, which showed cleaner dentin walls than the apical third

Physicochemical properties and filling capacity of an experimental iodoform-based paste in primary teeth

In this study, we evaluated the physicochemical properties (PCP; radiopacity, flow, pH, and solubility) and the quality of root canal filling provided by an experimental industrialized paste (EP), with the same active ingredients as those of the Guedes Pinto paste, compared with the Vitapex® paste. PCP were analyzed according to the ANSI/ADA laboratory testing methods for endodontic filling and sealing materials. To analyze filling capacity, 120 artificial primary teeth (60 maxillary incisors [MIs] and 60 mandibulary molars [MMs]) were endodontically treated. The teeth were divided into eight groups based on the dental group (MIs or MMs), filling material (Vitapex® or EP), and insertion method (syringe or lentulo). The Image J® software was used to analyze the initial an final digital radiographies of each tooth, measuring and comparing root canal and void areas. The percentage of filling failure areas was obtained. Data were submitted to ANOVA and Tukey test of mean comparison. Regarding PCP, both pastes presented results according the ANSI/ADA standards. Flow capacity: Vitapex: 19.6 mm, EP: 25 mm (p 0.05). Regarding filling capacity analysis, EP demonstrated 12.5% of failure against 31.5% of Vitapex (p < 0.01). Compared to Vitapex, EP presented statistically significantly better results in flow, radiopacity, pH, and filling capacity. Molars presented more filling failures than incisors. The insertion method using a syringe and a thin tip was significantly better than that using Lentulo spiral carriers.info:eu-repo/semantics/publishedVersio

Coumestrol has neuroprotective effects before and after global cerebral ischemia in female rats

AbstractGlobal ischemia arising during cardiac arrest or cardiac surgery causes highly selective, delayed death of hippocampal CA1 neurons. Phytoestrogens are naturally occurring plant-derived compounds that are present in the human diet and are considered selective estrogen receptor (ER) modulators. The phytoestrogen coumestrol is a potent isoflavonoid, with binding affinities for both ER-α and ER-β that are comparable to those of 17b-estradiol. The present study examined the hypothesis that coumestrol protects hippocampal neurons in ovariectomized rats in a model of cerebral global ischemia. Ovariectomized rats were subjected to global ischemia (10min) or sham surgery and received a single intracerebroventricular or peripheral infusion of 20μg of coumestrol, 20μg of estradiol or vehicle 1h before ischemia or 0h, 3h, 6h or 24h after reperfusion. Estradiol and coumestrol afforded significant neuroprotection in all times of administration, with the exception of estradiol given 24h after the ischemic insult. Animals received icv infusion of the broad-spectrum ER antagonist ICI 182,780 (50μg) or vehicle into the lateral ventricle just before the E2 or coumestrol administration. The ER antagonist abolished estradiol protection, consistent with a role of classical ERs. In contrast, ICI 182,780 effected only partial reversal of the neuroprotective actions of coumestrol, suggesting that other cellular mediators in addition to classical ERs may be important. Additional research is needed to determine the molecular targets mediating the neuroprotective action of coumestrol and the therapeutic potential of this phytoestrogen in the mature nervous system