Projeto preliminar de estatorreator a parafina sólida com ancorador-injetor de chama integrados

Trabalho de Conclusão de Curso (graduação) — Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2020.Os sistemas de propulsão a jato denominados Ramjets têm sido objeto de estudo de diversos pesquisadores desde a sua primeira proposição em 1913, pelo francês René Lorin. Os Ramjets chamam bastante a atenção por conta de sua simplicidade mecânica, velocidades elevadas de voo (regime supersônico) e baixo custo, quando comparados a sistemas similares. Têm sido utilizados em aplicações militares, como exemplos, o míssil Brahmos e a peça de artilharia Nammo. No Brasil, é noticiado o desenvolvimento do míssil tático AV-TM 300, pelo Exército, que irá operar em regime subsônico, como um dos objetivos a serem alcançados pelo projeto estratégico Astros 2020. Contudo, é desconhecido que haja estudos no Brasil acerca do desenvolvimento de sistemas de propulsão supersônica. Com base nisso, a Universidade de Brasília se propõe a realizar o estudo sobre Ramjets a combustível sólido, utilizando a parafina como combustível, bem como, buscar alternativas para melhoria na eficiência desses sistemas, seja introduzindo novos elementos ou experimentando novas configurações. A parafina é escolhida por se mostrar um combustível bastante promissor, com elevada taxa de regressão e baixo custo operacional. Em suma, o trabalho terá como objetivo a busca por alternativas que proporcionem melhoria na eficiência dos sistemas Ramjets.Jet propulsion systems known as Ramjets have been the subject of study by many researchers since their first proposition in 1913 by the French René Lorin. Ramjets draw a lot of attention because of their mechanical simplicity, high flight speeds (supersonic regimes) and low cost when compared to similar systems. It has been used in military applications, such as the Brahmos missile and the Nammo artillery piece. In Brazil, the army’s development of the tactical missile AV-TM 300, which will operate in subsonic mode, is reported as one of the objectives to be achieved by the Astros 2020 strategic project. However, it is unknown that there are studies in Brazil on the development of supersonic propulsion systems. Based on this, the University of Brasilia proposes to conduct the study of solid fuel Ramjets, using paraffin as propellant, as well as, to search alternatives for improve efficiency of this systems experimenting new configurations. Paraffin is chosen because it is a very promising fuel, with high regression rate and low operating cost. The work will aim to find alternatives that improve the systems Ramjets efficiency

Fire behaviour of wood and wood-based composite panels towards the development of fire-resistant multilayer systems

The use of sustainable natural resources has been practiced by the construction sector as a means to reduce energy demand and increase the efficiency of buildings. In this sense, wood and wood-based materials are alternative and renewable material sources that can be effectively used in building elements, such as doors and partition walls, which are required to provide adequate thermal, acoustic, and fire resistance performance. Such elements play an important role in the fire compartmentation of buildings. Appropriate selection of materials with a reduced potential of ignition and enhanced fire behaviour may reduce the heat flux, and the passage of hot gases and smoke, thus minimizing fire hazards. In the case of wood products, the combustibility of wood usually limits its use in fire-resistant components. However, the fire performance of wooden assemblies can be improved by using engineered wood products and insulation materials, which can be assembled into multilayer systems. This work investigates the performance of wood and wood-based multilayer panels exposed to ISO 834 standard fire curve to improve the knowledge about their fire resistance in terms of insulation (I) and integrity (E) criteria. The study considers pinewood, OSB (oriented strand board), and moisture-resistant MDF (medium-density fibreboard) of different thicknesses.info:eu-repo/semantics/publishedVersio

Fire behaviour of wood and wood-based composite panels towards the development of fire-resistant multilayer systems

The use of sustainable natural resources has been practiced by the construction sector as a means to reduce energy demand and increase the efficiency of buildings. In this sense, wood and wood-based materials are alternative and renewable material sources that can be effectively used in building elements, such as doors and partition walls, which are required to provide adequate thermal, acoustic, and fire resistance performance. Such elements play an important role in the fire compartmentation of buildings. Appropriate selection of materials with a reduced potential of ignition and enhanced fire behaviour may reduce the heat flux, and the passage of hot gases and smoke, thus minimizing fire hazards. In the case of wood products, the combustibility of wood usually limits its use in fire-resistant components. However, the fire performance of wooden assemblies can be improved by using engineered wood products and insulation materials, which can be assembled into multilayer systems. This work investigates the performance of wood and wood-based multilayer panels exposed to ISO 834 standard fire curve to improve the knowledge about their fire resistance in terms of insulation (I) and integrity (E) criteria. The study considers pinewood, OSB (oriented strand board), and moistureresistant MDF (medium-density fibreboard) of different thicknesses. Rockwool with a thickness of 27 mm was also used as a core material. The multilayer systems have a dimension of 580×580 mm, fixed to a wood frame and mounted to a wall made of refractory bricks and mortar. The composite panels were tested in a small-scale furnace. During each test, temperatures were measured using type k thermocouples attached between layers and to the panel’s surfaces and wood frame. The specimens were considered to have failed when the insulation and integrity criteria were met according to EN 1363-1. The results showed that a 1-hour insulation fire resistance was achieved when using 16 mm-thick MDF panels on both sides and rockwool as a core material. Similar assemblies using 6 mm-thick and 10 mm-thick MDF panels reached 30 min., and 40 min., respectively. The specimen with 20 mm-thick pinewood on both sides and rockwool core had an insulation fire resistance of 41 min. but had one of the highest superficial masses and highest total thickness amongst tested specimens. Pinewood has been tested as a core material sandwiched between two 10 mm- thick MDF panels, and its insulation fire resistance was 30 min. The assembly with 15 mm-thick OSB placed between two 10 mm-thick MDF boards had the smallest insulation fire resistance of around 27 min. The fall-off of the exposed panel and warping of the edges of the panels greatly influenced the integrity behaviour of the samples. The insulation performance was mostly affected by the type of material and its thickness, as well as by the relative position of the layer in the composite assembly. The results provide important data regarding heat transmission effects and integrity issues related to the exposure of wood and wood-based composite multilayer systems under fire.This work was developed within the scope of the project NORTE-01-0247-FEDER-072225, supported by North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).info:eu-repo/semantics/publishedVersio

Penhora de Quotas por Dívida Particular de Sócio: Evolução Histórico-Legislativa e Jurisprudencial

Historical analysis of the legal treatment of the seizure of shares due to shareholder’s personal debt and the impacts of such measure on the affectio societatis. In order to do so, with the usage of the deductive method of research, hereby it will be presenting two different views on the issue: a first one based solemnly on the rules and principles the are commonly accepted and a second based on logical arguments. Afterwards, the two premises are going to be confronted in order achieve the best answers. Moreover, with the usage of bibliographical and documental research, this work intends to demonstrate how the seizure of shares has evolved from an impossibility, under the terms of the article 292 of the Commercial Code, to a reality, whereas the seizure is now possible even on those cases where the article of association lacks the regulation on the issue. Análise histórica do tratamento legislativo da penhora de quotas por dívidas de sócio e repercussão na affectio societatis. Utiliza-se o método dedutivo partindo-se de regras e princípios reconhecidos como verdadeiros e estabelecer relações com uma segunda proposição para, a partir de raciocínio lógico, chegar à verdade daquilo que propõe. Com base na pesquisa bibliográfica e documental, pretende-se demonstrar como a possibilidade de penhora das quotas do sócio, não autorizada pelo art. 292 do Código Comercial, evoluiu com as sociedades por quotas de responsabilidade limitada, a ponto de a legislação hodierna admitir a penhora das quotas independente de permissivo contratual.

Fire performance of wood and wood-based panels towards the development of wood fire doors

Fires in buildings continue to be responsible for high human and economic losses. The increasing demand for legal requirements in the fire safety sector has been complemented by performance criteria of construction products, increasing the requirements of their essential technical characteristics, such as thermal, acoustic, and fire behaviour, as prescribed in the European Construction Products Regulation (CPR). This work addresses the development of an innovative system for the production of wood fire doors based on solid wood, wood-based panels, and lightweight materials with enhanced fire performance, aiming at improving the integrity and insulation (EI) fire resistance time. For this purpose, the fire behaviour of different solid woods and wood-based panels were analysed in a cone calorimeter, under the action of a 75 [kW/m2] radiative heat flux. The study considers pine wood (Pinus pinaster), tulip tree wood (Liriodendron tulipifera), plywood panels, and Medium-Density Fibreboard (MDF) of different thicknesses. During each test, the heat release rate, total heat release, and sample mass loss were measured and evaluated for comparison. Using a set of thermocouples type k placed on the exposed face and non-exposed faces, and in the sample interior at different depths, the temperature evolution was measured over time, allowing to determine the through-thickness heating rate. Results show a mass loss rate that changes with the MDF thickness, resulting in a reduction of 50% mass loss after 3.73 [min] and 11.57 [min] exposure, for 10 [mm] and 22 [mm] boards, respectively. Similarly, the peak heat release rate is higher for thinner boards. Plywood boards have higher heat release rates compared to MDF boards, with the same thickness, due to the resin used between each layer. For the same exposure time, the pine wood samples release more heat compared to the tulip wood, having the latter a higher mass loss rate. The temperature distribution measured across the thickness allowed the estimation of the charring rate and evaluate the insulation performance of each sample.info:eu-repo/semantics/publishedVersio

Ozone saturation in a column containing peanut kernels and the effect on quality

Objetivou-se com este trabalho avaliar o processo de saturação do ozônio em coluna contendo amendoim e o efeito na qualidade de produto. Utilizaram-se grãos com teor de umidade em torno de 6,8% (b.u.), acondicionados em recipientes cilíndricos de PVC, com 1,10 m de altura e 15 cm de diâmetro. O gás, nas concentrações de 1,59 e 2,78 mg L–1, foi injetado na base da coluna e os valores adotados de altura da coluna de grãos foram de 0,25, 0,50 e 0,75 m. Determinaram-se os tempos e as concentrações de saturação e avaliou-se a qualidade dos grãos ozonizados. Para os grãos ozonizados na concentração de 1,59 mg L–1, obteve-se tempo de saturação na faixa entre 222 e 449 min. No que tange à relação CSat/C0, obtiveram-se valores entre 0,32 e 0,48. Com relação aos grãos submetidos à ozonização na concentração de 2,78 mg L–1, obteve-se tempo de saturação na faixa entre 78 e 251 min. No que se refere à relação CSat/C0, para a concentração inicial de 2,78 mg L–1, os valores permaneceram entre 0,46 e 0,81. É possível concluir, a partir dos resultados obtidos, que, à medida que se aumenta a altura da coluna de grãos de amendoim, há aumento do tempo de saturação e decréscimo da concentração de saturação. Não houve alteração na qualidade do produto durante o processo de ozonização.The objective of this study was to evaluate the ozone saturation process in a column containing peanuts and the effect on product quality. Peanuts with a moisture content of about 6.8% (w.b.) were used, packed in cylindrical PVC containers with 1.10 m in height and 15 cm in diameter. Ozone was injected into the base of the cylindrical column and the corresponding values adopted for the heights of the grain columns were 0.25, 0.50 and 0.75 m. The peanuts were ozonized at concentrations of 1.59 and 2.78 mg L–1, a temperature of 25 °C and a gas flow rate of 5.0 L min–1. The ozone saturation times and concentrations were determined and also the quality of the ozonized peanuts. For peanut kernels ozonated at a concentration of 1.59 mg L–1, saturation times ranging between 222 and 449 min were obtained. Regarding the CSat/C0 ratio, values ​​between 0.32 and 0.48 were obtained. For peanut kernels ozonated at a concentration of 2.78 mg L–1, saturation times between 78 and 251 min were obtained, and the CSat/C0 ratio for an initial concentration of 2.78 mg L-1 was between 0.46 and 0.81. It was concluded from the results that an increase in height of the peanut kernel column resulted in an increased saturation time and decreased saturation concentration. There was no change in product quality during the ozonation process

DOES THE FILM FORMED BY THE BORDEAUX MIXTURE ON THE LEAF SURFACE OF FIG TREES AFFECT PHOTOCHEMICAL PROCESSES?

The objective of this work was to evaluate if the layer formed by the Bordeaux mixture on the leaf surface alters the characteristics of gas exchange, as well as the Fluorescence of chlorophyll A, when applied to combat rust. The experimental design used was entirely randomized with 2 treatments (with and without Bordeaux mixture) with leaves in 3 distinct parts of the plant branch (apical, median and basal), with 5 evaluations in 4 repetitions. The gas exchange evaluations were related to: carbon variation between the external environment and the analysis chamber, leaf temperature, transpiration rate, stomatal conductance and net photosynthesis rate. The chlorophyll A fluorescence evaluations were: maximum quantum yield of the photosystem, effective quantum yield of the photosystem, electron transport rate and photochemical and non-photochemical dissipation. In addition to the leaf area. The film formed by the Bordeaux mixture application did not interfere in the photochemical stages of photosynthesis and the fluorescence of chlorophyll A. The internal CO2 concentration, and net CO2 assimilation are gas exchange variables influenced by the position of the leaf on the branch over time. The leaves in the middle part of the branch showed the largest area, to the detriment of the apical and basal parts of the branch.ABSTRACT: This work aimed to evaluate changes in gas exchanges and chlorophyll a fluorescence in fig plants due to the film formed on the leaf surface by Bordeaux mixture applied to control rust. The experiment was conducted in an orchard with 7-month-old fig trees of the cultivar Roxo de Valinhos, in April 2020. A completely randomized experimental design with four replications was used, consisting of two treatments (with and without application of Bordeaux mixture), evaluating leaves in three different parts of the branch (apical, middle, and basal) in five evaluations. The evaluated gas exchange parameters were: carbon, leaf temperature, transpiration, stomatal conductance, and photosynthesis. The evaluated chlorophyll fluorescence parameters were: maximum and effective quantum yield of the photosystem, electron transport rate, photochemical and non-photochemical quenching, and leaf area. The film formed by Bordeaux mixture application did not affect the photochemical phases of photosynthesis and chlorophyll a fluorescence. The leaf position on the branch affected internal CO2 concentration and net CO2 assimilation over time. Leaves in the middle part of the branch presented larger leaf areas than those in the apical and basal parts. Keywords: Ficus Carica L.; chlorophyll a; rust; leaf area.   A película formada pela calda bordalesa na superfície foliar das figueiras interfere nos processos fotoquímicos?   RESUMO: O objetivo desse trabalho foi avaliar se a camada formada pela solução da calda bordalesa na superfície foliar altera as características das trocas gasosas, bem como a Fluorescência da clorofila A, quando aplicada no combate a ferrugem. O delineamento experimental utilizado foi o inteiramente casualizado com 2 tratamentos (com e sem calda bordalesa) com folhas em 3 partes distintas do ramo da figueira (apical, mediana e basal), sendo feitas 5 avaliações, com 4 repetições, em um pomar de 7 meses de idade da cultivar Roxo de Valinhos, no mês de abril de 2020. As avaliações das trocas gasosas foram referentes a: variação do carbono, temperatura da folha, transpiração, condutância estomática e fotossíntese. As avaliações da fluorescência da clorofila A, foram referentes a: rendimento quântico máximo e efetivo do fotossistema, taxa de transporte de elétrons, dissipação fotoquímica e não fotoquímica e área foliar. A película formada pela aplicação da calda bordalesa não interferiu nas etapas fotoquímicas da fotossíntese e na fluorescência da clorofila A. A Concentração interna, e a assimilação líquida do CO2 foram influenciadas pela posição da folha no ramo ao longo do tempo. As folhas da parte mediana do ramo apresentam a maior área, em detrimento das partes apical e basal. Palavras-chave: Ficus Carica L.; clorofila A; ferrugem; área foliar