One-dimensional solidification of supercooled melts

In this paper a one-phase supercooled Stefan problem, with a nonlinear relation between the phase change temperature and front velocity, is analysed. The model with the standard linear approximation, valid for small supercooling, is first examined asymptotically. The nonlinear case is more difficult to analyse and only two simple asymptotic results are found. Then, we apply an accurate heat balance integral method to make further progress. Finally, we compare the results found against numerical solutions. The results show that for large supercooling the linear model may be highly inaccurate and even qualitatively incorrect. Similarly as the Stefan number β → 1&sup&+&/sup& the classic Neumann solution which exists down to β =1 is far from the linear and nonlinear supercooled solutions and can significantly overpredict the solidification rate.

Resolución de problemas de Física y Química : trabajo de innovación educativa para la Enseñanza Secundaria.

Conseguir un aprendizaje significativo de los procesos de resolución de problemas al implicar al estudiante en la comprensión de la tarea que esta realizando y en la revisión personal de sus estrategias de trabajo. 10 grupos desde el curso de segundo de BUP a COU. Este trabajo se limita a la resolución de problemas-ejercicios de corte convencional y por consiguiente cerrados. El problema utilizado de Física y Química. Se resuelve previamente en su forma más tradicional y, posteriormente, se analiza el proceso seguido, en forma de esquema similar a un diagrama de flujo que representa cada uno de los pasos que han sido necesarios para la resolución. Estos pasos pueden ser operativos, de transformación de unidades, aplicaciones de leyes y fórmulas. Por otra parte, se analizan en el problema ya resuelto, los conocimientos teóricos que han sido necesarios a lo largo de todo el proceso y cuya ignorancia y olvido puede imposibilitar la resolución total o parcial del problema. La resolución de un problema-ejercicio supone para muchos alumnos la realización de una serie de operaciones a menudo mecánicas que han aprendido por repetición. Desde el punto de vista del aprendizaje, la realización del esquema de resolución del problema ayuda al alumno a: reflexionar sobre sus procesos de pensamiento, comprender la importancia de los conocimientos teóricos y sus relaciones, para su aplicación a los problemas, diferenciar la importancia de las dificultades a las que ha de enfrentarse, comprensión del enunciado, necesidad de conocimientos sobre el tema, etc., conocer los errores cometidos, para evaluar su trabajo con mayor objetividad. Referido a la enseñanza ofrece ayuda al profesor para: analizar el grado de dificultad de los problemas que propone, situar la importancia de la enseñanza de los problemas en la comprensión de procesos, establecer con facilidad la similitud del proceso de resolución en problemas con enunciados muy diferentes, simplificar a la vez que hacer más rigurosa la corrección, detectar los errores más frecuentes cometidos por los alumnos.

Avaliação física do tomate de mesa 'Romana' durante manuseio na pós-colheita

Tomato postharvest losses are very high in Brazil and the goal of this research was to evaluate the effect of handling and the transport of tomato fruits, cultivar Romana on the steps of harvesting, weight and transportation to the packinghouse, pointing some critical points. Tomatoes were harvested at plastic boxes, weighted and shipped to a packinghouse. Fruits taken directly from the plant were determined as reference. The parameters evaluated were weight loss and mechanical injury and tomato physical quality after storage during 21 days. It was observed an increasing on the weight loss, external damage, and postharvest losses, after storage. Handling and transportation were the cause of an increase in 6.6% in external damage and 1.93% of weight loss after storage, when comparing harvested fruits and fruits evaluated on the packing-house. The main reason for postharvest losses was due to mechanical injury caused during transportation mainly due to the compressure force among fruits and against the plastic boxes.

Caracterização física e mecânica de argamassas à base de cimento Portland e cinza de casca de arroz residual

Rice husk, employed as an energy source at milling industries in Brazil generates, after burning, a dark ash. This residue is not yet conveniently disposed, being currently dumped on large areas, causing environmental problems. This research intended to evaluate the applications of residual rice husk ashes (RHA) as a partial replacement of cement for mortar production. Rice husk ash was chemically characterized through X-ray fluorescence, determination of carbon content, X-ray diffraction, and laser granulometric analysis. Mortar specimens were submitted to two different exposure conditions: internal and external environments at a maximum period of five months. Physical-mechanical testing were compressive strength and ultrasonic pulse velocity (UPV). Although presenting good mechanical performance, the mortar based on ash (RHA) did not present pozolanicity but it can be employed in cement matrices as inert material (filler).

Pesquisa qualitativa em Educação Física: possibilidades de construção de conhecimento a partir do referencial cultural

This work indicates presuppositions for the qualitative research in Physical Education, starting with a literature review based on the cultural frame of reference. Firstly, we introduce the debate concerning the natural and the human sciences and implications for the Physical Education; we then use a cultural axis as a ground basis for the research in the area, proposing the 'dense description' as a possibility for knowledge building; finally, we bring up examples of studies conducted with such an approach. This theoretical methodological approach allows the study of the human being as a cultural being, thus opposed to the naturalised view of a human - predominant in Physical Education.

Influência da atividade física na qualidade de vida e auto-imagem de mulheres incontinentes

Our aim was to verify the influence of a physical activities proposal in the quality of life and self image of incontinent women. This study was comparative and exploratory and was developed in 16 weeks. Thirty-seven women with and without urinary incontinence (IU) participated in the study. After the study, significant improvement in general health perception (p < 0.001), UI impact (p = 0.035), physical limitations (p = 0.015), personal relations, (p = 0.048), sleep and disposition (p = 0.012) and concerned with the gravity measurements (p = 0.011) was observed. Concerning self image, alterations in appearance were not observed; however, concerning body satisfaction, the women felt less satisfied with their bodies (p = 0.007). There was a reduction in the number of regions where they felt pain (p = 0.0003) and that they did not like (p = 0.0017). In conclusion, the Physical Education professionals using a systematized and integrated physical activities program can lead the women with IU to significant improvement in the perception of their quality of life and health concerning their self image with improvement of the IU symptoms and reduction of frequency and amount of urinary loss.

Qualidade de vida de portadores de Diabetes Mellitus tipo II frente às oscilações no nível de atividade física, aspectos socioeconômicos e presença de comorbidades

Universidade Estadual de Campinas . Faculdade de Educação Física

A dança na formação docente em educação física

Universidade Estadual de Campinas . Faculdade de Educação Física

A Educação Física no contexto da nova estrutura do ensino fundamental : uma proposta para o primeiro ano

Universidade Estadual de Campinas . Faculdade de Educação Física

O brincar no contexto escolar : significados das brincadeiras realizadas em aulas de educação física e no recreio

Universidade Estadual de Campinas . Faculdade de Educação Física

Auto-eficácia docente e motivação para a realização do(a) professor(a) de Educação Física Adaptada

Universidade Estadual de Campinas . Faculdade de Educação Física

Realidade da olimpíada colegial do estado de São Paulo (OCESP) em relação ao discurso presente na educação física acerca da competição escolar : estudo da região leste de Campinas

Universidade Estadual de Campinas . Faculdade de Educação Física

A educação física na educação infantil e as relações de gênero : educando crianças ou meninos e meninas?

Universidade Estadual de Campinas . Faculdade de Educação Física

Atividade motora adaptada : o conhecimento produzido nos programas Stricto Sensu em Educação Física no Brasil

Universidade Estadual de Campinas . Faculdade de Educação Física

Uma analise das alterações nas variáveis fisiológicas e aptidão física (teste da FIFA) e suas prováveis interferências no desempenho do arbitro durante a partida

Universidade Estadual de Campinas. Faculdade de Educação Física