O ensino em educação física escolar: reflexões sobre os conhecimentos presentes nos conteúdos de ensino

TCC (Graduação) - Universidade Federal de Santa Catarina. Centro de Desportos. Educação Física Licenciatura.O presente Trabalho de Conclusão de Curso se propõe a discutir a dimensão escolar da Educação Física em sua tarefa de proposição e organização dos conteúdos de ensino. Sendo assim, busca-se argumentar que se faz necessária a discussão em torno dos conteúdos e conhecimentos de ensino, evidenciando a existência de um “emaranhamento” de ideias e concepções nesse campo. Diante disso, o objetivo desta investigação foi interpretar como a proposição e organização dos conteúdos de ensino em Educação Física manifesta o emaranhado de conhecimentos a serem ensinados e aprendidos na Educação Física Escolar. Para isso, foram mobilizadas, em uma pesquisa teórico-bibliográfica, duas fontes de dados, utilizadas como meios para se pensar/escrever sobre o objeto de investigação, sendo elas: i) dados contidos em entrevistas realizadas com professores de Educação Física da rede pública de ensino de Florianópolis e que foram desdobrados de um projeto de pesquisa “guarda-chuva” do grupo NEPEF/GEPPICE; e ii) o documento curricular da Rede Municipal de Ensino de Florianópolis, especificamente em relação ao componente Educação Física. A partir da análise pudemos nos aproximar de considerações transitórias ao sistematizar alguns dos elementos e problemáticas que nos parecem potentes para desemaranhar “fios do novelo” relacionados à atividade de proposição e organização dos conteúdos de ensino em Educação Física. Em primeiro lugar destacamos a identificação e interpretação de "quatro camadas” que compõem aquilo que denominamos “conteúdos de ensino”: a manifestação corporal; os princípios formativos; os conhecimentos correlatos à área; e os conhecimentos formativos específicos da área. Em segundo lugar destacamos algumas interpretações sobre a forma com que a área da Educação Física age/atua com o emaranhado inerente à proposição e organização dos conhecimentos de ensino, evidenciando a existência de pouca clareza ao operar com as “camadas”, suas distinções e relações, o que parece resultar muitas vezes em um ocultamento dos conhecimentos formativos específicos da área. Buscamos, por fim, discutir o quanto a reflexão sobre “os conteúdos de ensino” em Educação Física refere-se a uma problemática viva em nossa área e uma ação permanente da atividade docente na escola, na medida em que exige do professor identificar e organizar as muitas “camadas” de conhecimentos que compõem cada uma das manifestações corporais, cientes de como cada uma delas se relacionam entre si e, ao mesmo tempo, como expressam o projeto formativo que temos com o componente curricular Educação Física.This final paper aims to discuss the schooling dimension of Physical Education in its task of proposing and organizing the subject-matter contents. Therefore, one seeks to argue that the discussion about content and knowledge of teaching is necessary, showing the existence of a “tangle” of ideas and conceptions in this field. Based on this, the goal of this investigation was to interpret how the proposition and organization of subject-matter contents in Physical Education manifest the tangle of knowledge to be taught and learned in school Physical Education. Two sources of data were mobilized within a theoretical-bibliographic research and used as means to think/write about the research object, they are: i) data from interviews with Physical Education teachers from public schools from Florianópolis and that were unfolded from a "umbrella" research project of the NEPEF / GEPPICE group; and ii) the curriculum document of the City hall Education of Florianópolis, specifically in relation to the Physical Education subject-matter. Through the analysis, we were able to approach transient considerations by systematizing some of the elements and problems that seem to be potent to untangle “threads from the ball” related to the activity of proposing and organizing the subject-matter content in Physical Education. Firstly, we highlight the identification and interpretation of “four layers” that compose what we named as “subject-matter contents”: the corporeal practice/ manifestation; the formative principles; the knowledge correlated to the area; and the specific formative knowledge of the area. Secondly, we highlighted some interpretations about the way in which Physical Education area acts with the tangle inherent to the proposition and organization of subject-matter knowledge, showing the existence of poor clarity when operating with the “layers”, their distinctions and relationships, which often seems to result in occulting specific formative knowledge in the field. Finally, we seek to discuss how the reflection on “subject matter content” in Physical Education refers to an alive problematic in our area and a permanent action for teaching activity in school, considering it requires from the teacher to identify and organize the many “layers” of knowledge that constitutes each corporeal practices/ manifestations, being aware of how each one of them is related to each other and, at the same time, how they express the formative project we have within Physical Education in school curriculum

Comparison of surface properties modification by direct and active screen plasma nitriding of an ASTM M2 high-speed steel in a nitrogen rich gas mixture

The active screen plasma nitriding technique has been studied in recent years as a method to optimize surface properties in steel components, avoiding the negative effects caused in the conventional Direct Current plasma treatments. In this study, ASTM M2 high-speed tool steel samples were plasma nitrided with and without the use of the active screen, in order to compare the surface properties developed by each technique. The treatments were carried out at 500 °C, with the gas mixture of 76 vol.% N2 + 24 vol.% H2 , for 4 and 8 h. The active screen used was built with an expanded sheet of 304 stainless steel. The results were evaluated through optical microscopy, X-ray diffraction, and microhardness measurements. The samples were subjected to dry ball-on-flat tribological tests and the wear tracks were verified by 3D optical interferometry. The active screen use provided the formation of thinner layers, however, avoided the formation of brittle phases, resulting in the lowest wear volumes observed, up to 10 times less than the other analyzed conditions (nitrided and non-nitrided samples).A técnica de nitretação com tela ativa vem sendo estudada nos últimos anos como uma maneira de otimizar propriedades superficiais de componentes de aço, evitando os efeitos negativos provocados nos tratamentos a plasma convencionais de corrente contínua. Neste estudo, amostras do aço rápido ASTM M2 foram submetidas a tratamentos de nitretação a plasma com e sem a utilização da tela ativa, a fim de comparar as propriedades superficiais proporcionadas por cada técnica. Os tratamentos foram executados em 500 °C, com a mistura gasosa de 76% N2 + 24% H2 , durante 4 e 8 horas. A tela ativa utilizada foi construída utilizando chapa expandida de aço inoxidável AISI 304. Os resultados foram avaliados através de microscopia ótica, difração de raios-X e medidas de microdureza. As amostras foram submetidas a ensaios tribológicos do tipo esfera-sobre-plano a seco e as trilhas de desgaste foram verificadas por interferometria ótica 3D. A utilização da tela ativa proporcionou a formação de camadas menos profundas, porém, evitou a formação de fases frágeis, resultando nos menores volumes desgastados observados, até 10 vezes menor que as outras condições analisadas (amostras nitretadas e não-nitretada)

New ASPN high efficiency treatment of ASTM M2 steel

Plasma nitriding treatments are applied to achieve excellent surface properties on steel parts and tools. Active screen plasma nitriding (ASPN) does not have the defects presents in direct nitriding plasma treatments (DCPN). However, ASPN require much longer processing times to develop surface layers as deep as those of DCPN. This work presents the development of a biased ASPN treatment system, to investigate the possibility of achieving greater efficiency. The treatments were performed on ASTM M2 steel samples using the same processing parameters in 4 different configurations: DCPN, ASPN and 2 active screen plasma nitriding with biased specimens voltage: one was called "bright bias", because biased voltage is high enough to develop a plasma glow on the samples, and the other "dark bias", where no plasma glow sheath is seen on the samples. The active screen dark biased treatment presented the best results. These results could be understood by the electromagnetic field generated by the bias source promoting the deposition of nitrogen ions on the surface of the part being treated. Therefore, it was demonstrated that the use of dark bias voltage in the active screen treatment in larger reactors is fundamental to achieve good nitriding results in smaller times

Response of a DIN 18MnCrSiMo6-4 continuous cooling bainitic steel to different plasma nitriding gas mixtures

Continuous cooling bainitic steels has been widely used in industrial processes owing to its excellent mechanical properties and toughness. Although the surface properties of them are acceptable for many purposes, for their use in mechanical components like gears, it is necessary to improve their surface properties. Plasma nitriding treatments was carried out of a DIN 18MnCrSiMo6-4 steel at 500 °C, with three different nitrogen gas composition: 76, 24 and 5 vol.% nitrogen in hydrogen, for 3, 6 and 9 hours. The surfaces were characterized concerning the microstructure, microhardness, fracture toughness, nitrogen concentration and carbon composition, phase composition and residual stress states. Based on the results presented, layer growth constants (k) for different nitrogen gas composition was determined. The carbon profiles of samples indicate that there was decarburization during the plasma nitriding. The nitrided samples with thicker compound layers presented a fracture behavior dominated by the formation of Palmqvist cracks. X-ray phase analysis indicated the formation of biphasic compound layer on the surface of all nitrided samples with 76 and 24 vol.% nitrogen, while the nitrided samples with 5 vol.% nitrogen indicated the formation of monophasic compound layer. The diffusion zone presented compressive residual stresses with highest values near the surface

Comparative analysis of the friction and microstructural properties of WC-10Co-4Cr and Cr3C2-25NiCr coatings sprayed by high-velocity oxy-fuel (HVOF)

In this study, coatings WC-10Co-4Cr and Cr3C2-25NiCr were deposited on the AISI H13 steel by oxy-fuel Thermal spraying (HVOF). This coating increases the wear resistance of surfaces subjected to severe conditions, such as: abrasive wear, thermal fatigue and plastic deformation. The coatings microstructure, hardness and wear resistance are investigated through friction and wear tests performed through a pin-on-disc type tribometer following the procedures defined in ASTM G99-04. It was verified that both materials used in the spraying have high resistance to wear, however, in the sample coated with Cr3C2-25NiCr there was a greater removal of material during the test

Acionador automático para irrigar plantas

Despite the massive demand of water for plant irrigation, there are few devices being used in the automation of this process in agriculture. This work evaluates a simple controller to water plants automatically that can be set up with low cost commercial materials, which are large-scale produced. This controller is composed by a ceramic capsule used in common domestic water filters; a plastic tube around 1.5 m long, and a pressostate used in domestic washing machines. The capsule and the pressostate are connected through the tube so that all parts are filled with water. The ceramic capsule is the sensor of the controller and has to be placed into the plant substrate. The pressostate has to be placed below the sensor and the lower it is, the higher is the water tension to start the irrigation, since the lower is the pressostate the higher is the water column above it and, therefore, the higher is the tension inside the ceramic cup to pull up the water column. The controller was evaluated in the control of drip irrigation for small containers filled with commercial organic substrate or soil. Linear regressions explained the relationship between the position of pressostate and the maximum water tension in the commercial substrate (p < 0.0054) and soil (p < 0.0001). Among the positions of the pressostate from 0.30 to 0.90 m below the sensor, the water tension changed from 1 to 8 kPa for commercial substrate and 4 to 13 kPa for the soil. This simple controller can be useful to grow plants, applying water automatically in function of the water tension of the plant substrate.A despeito da enorme demanda por água na irrigação de plantas, existem poucos aparelhos para automação deste processo sendo usados na agricultura. Avaliou-se um acionador automático para irrigação, o qual pode ser confeccionado com materiais comerciais de baixo custo, pois são produzidos em larga escala. Este acionador é composto por uma cápsula cerâmica usada em filtros de água domésticos; um tubo plástico com cerca de um metro e meio de comprimento e um pressostato de máquinas de lavar roupas domésticas. A cápsula e o pressostato são conectados pelo tubo de forma que todo o espaço interno seja preenchido com água. A cápsula é o sensor do acionador e deve ser posicionada dentro do substrato das plantas. O pressostato deve ser posicionado abaixo do sensor e quanto mais baixo ele estiver, maior é a tensão da água que aciona a irrigação, pois quanto mais baixo estiver o pressostato, maior é a coluna de água acima do mesmo e, portanto, maior é a tensão na cápsula cerâmica para puxar para cima a coluna de água. O acionador foi avaliado no controle da irrigação por gotejamento em pequenos potes preenchidos com substrato orgânico comercial ou solo. Regressões lineares explicaram a relação entre a posição do pressostato e a tensão máxima no substrato comercial (p < 0,0054) e no solo (p < 0,0001). Entre as posições do pressostato de 0,30 a 0,90 m abaixo do sensor, a tensão da água variou de 1 a 8 kPa para o substrato comercial e de 4 a 13 kPa para o solo. Este simples acionador pode ser útil para cultivar plantas, aplicando água automaticamente em função da tensão da água no substrato das plantas

Response of a DIN 18MnCrSiMo6-4 continuous cooling bainitic steel to plasma nitriding with a nitrogen rich gas composition

The use of continuous cooling bainitic steels can provide a more energy efficient manufacturing route. However, for their use in mechanical components like gears, it is necessary to improve their surface properties without impacting the core properties to guarantee reliable mechanical performance. The effect of temperature and time on the plasma nitriding response of a DIN 18MnCrSiMo6-4 steel was investigated. The plasma nitriding was performed for 3, 6 and 9 hours, at 400, 450, 500 and 550 °C, using a gas mixture composed of 76 vol.% nitrogen and 24 vol.% hydrogen. Samples were characterized before and after plasma nitriding concerning the microstructure, hardness and microhardness, fracture toughness, phase composition and residual stress states. Based on the results presented, layer growth constants (k) for different temperatures was determined. Moreover, it could be found that 500 °C gave the best results investigated here, as higher temperature took to core and surface hardness decrease. The nitrided samples with thicker compound layers presented a fracture behavior dominated by the formation of Palmqvist cracks. X-ray phase analysis indicated the formation of biphasic compound layer on the surface of all nitrided samples. The diffusion zone presented compressive residual stresses with highest values near the surface

Automatic controller to water plants

Despite the massive demand of water for plant irrigation, there are few devices being used in the automation of this process in agriculture. This work evaluates a simple controller to water plants automatically that can be set up with low cost commercial materials, which are large-scale produced. This controller is composed by a ceramic capsule used in common domestic water filters; a plastic tube around 1.5 m long, and a pressostate used in domestic washing machines. The capsule and the pressostate are connected through the tube so that all parts are filled with water. The ceramic capsule is the sensor of the controller and has to be placed into the plant substrate. The pressostate has to be placed below the sensor and the lower it is, the higher is the water tension to start the irrigation, since the lower is the pressostate the higher is the water column above it and, therefore, the higher is the tension inside the ceramic cup to pull up the water column. The controller was evaluated in the control of drip irrigation for small containers filled with commercial organic substrate or soil. Linear regressions explained the relationship between the position of pressostate and the maximum water tension in the commercial substrate (p < 0.0054) and soil (p < 0.0001). Among the positions of the pressostate from 0.30 to 0.90 m below the sensor, the water tension changed from 1 to 8 kPa for commercial substrate and 4 to 13 kPa for the soil. This simple controller can be useful to grow plants, applying water automatically in function of the water tension of the plant substrate.A despeito da enorme demanda por água na irrigação de plantas, existem poucos aparelhos para automação deste processo sendo usados na agricultura. Avaliou-se um acionador automático para irrigação, o qual pode ser confeccionado com materiais comerciais de baixo custo, pois são produzidos em larga escala. Este acionador é composto por uma cápsula cerâmica usada em filtros de água domésticos; um tubo plástico com cerca de um metro e meio de comprimento e um pressostato de máquinas de lavar roupas domésticas. A cápsula e o pressostato são conectados pelo tubo de forma que todo o espaço interno seja preenchido com água. A cápsula é o sensor do acionador e deve ser posicionada dentro do substrato das plantas. O pressostato deve ser posicionado abaixo do sensor e quanto mais baixo ele estiver, maior é a tensão da água que aciona a irrigação, pois quanto mais baixo estiver o pressostato, maior é a coluna de água acima do mesmo e, portanto, maior é a tensão na cápsula cerâmica para puxar para cima a coluna de água. O acionador foi avaliado no controle da irrigação por gotejamento em pequenos potes preenchidos com substrato orgânico comercial ou solo. Regressões lineares explicaram a relação entre a posição do pressostato e a tensão máxima no substrato comercial (p < 0,0054) e no solo (p < 0,0001). Entre as posições do pressostato de 0,30 a 0,90 m abaixo do sensor, a tensão da água variou de 1 a 8 kPa para o substrato comercial e de 4 a 13 kPa para o solo. Este simples acionador pode ser útil para cultivar plantas, aplicando água automaticamente em função da tensão da água no substrato das plantas

Surface processing to improve the fatigue strength of bainitic steels : an overview

Currently, one of the major challenges for automotive industries is to reduce the weight and energy consumption of vehicles by using stronger and advanced low-cost materials. Conventional solutions using quenched and tempered steels not always fulfill the desired technical, economic and environmental requirements. Modern continuous cooling bainitic steels can provide a good combination of mechanical strength and toughness, being considered an excellent alternative to replace quenched and tempered martensitic steels in the manufacture of forged components. To meet the desired industry standards in highly loaded components, properties like surface hardness, fatigue strength, wear and friction resistance of these steels can be further improved by subsequent mechanical and thermochemical treatments. Therefore, this paper presents the state of the art in the use of continuous cooling bainitic steels for forging and low energy consumption surface improvement techniques such as: deep rolling and plasma nitriding. Finally, case studies are presented, and conclusions drawn on the current trends and reported practices. Surface modification techniques must be carefully controlled and combined with the material of interest to ensure that undesirable characteristics are not introduced during the manufacturing of the components. The development of processes based on the use of forged continuous cooling bainitic steels can be an excellent alternative to replace the conventional quenching and tempering treatment with considerable reduction of the energy consumption

Influence of plasma nitriding with a nitrogen rich gas composition on the reciprocating sliding wear of a DIN 18MnCrSiMo6-4 steel

In this study, the sliding wear of a DIN 18MnCrSiMo6-4 continuous cooling bainitic steel plasma nitrided with a nitrogen rich gas composition was investigated. To evaluate the influence of processing time and temperature on mechanical and microstructural characteristics of nitrided layer, the samples were nitrided at 400, 450, 500 and 550 °C for 3, 6 and 9 h. The produced nitrided layers were characterized concerning the microstructure, phase composition, microhardness and surface roughness. The samples were tested by ball-on-flat reciprocating dry sliding for friction coefficient and wear analysis. The tests were stopped after a given damage criteria involving the rapid growth of the friction coefficients and wear. The correlation of the different treatment parameters and resulting case depths and surface hardness with sliding distance at the time of microcracks formation or delamination of the surface layer was evaluated statistically by the analysis of variance (ANOVA). The plasma nitrided samples at 550 °C showed better wear performances in the ball-on-flat tests than the other groups investigated, since these samples have a thicker compound layer and diffusion zone higher than the other conditions investigated. In general, the beginning wear is slower because of the hardest region of the compound layer