Syftet med studien är att undersöka hur kommunikationen ser ut mellan pedagog och barn när barn undersöker materials egenskaper i vatten. Studien bygger på observationer av strukturerad karaktär. Den genomförs som en planerad aktivitet på en förskola, där barnen i små grupper fritt undersöker några materials egenskaper i vatten. Resultatet visar på att förskollärarna ställer frågor för att uppmärksamma barnens handlande. De ställer ofta produktiva frågor för att få barnen att fortsätta undersöka det de upplever. Förskollärarna följer upp responsen från barnen genom att bekräfta dem. Svaret är inte det viktiga, utan vägen dit. Responsen följs ibland av förskollärarens egna svar på frågan, då de haft en tanke med vad barnen ska erfara. Studien visar på att barn är nyfikna på att undersöka materials egenskaper i vattnet och förskollärares frågor uppmärksammar barnens utforskande. Barnen utmanas i sitt handlande när de får sätta ord på sina tankar och görs delaktiga i sin egna lärprocess. Barnen får feedback på de frågor de har och utforskandet kan på så sätt fortsätta. / The purpose of the study is to examine communication between preschool teacher and children while exploring properties of different kind of materials. The study is based on observations of structured nature. It is a planned activity at a preschool. In small groups the children are testing how different materials behaves in water. In the result the teachers are often asking questions to pay attention to the children’s activity. They are often using productive questions to encourage continues exploring. The preschool teacher follows up the response by confirming the children. With the purpose of not asking for the right answer but leading them to find it themselves. The response is sometimes followed by the preschool teachers own answers to the question, when they had a thought about what the children should experience. The study shows that children are curious to examine how different materials behaves in water. Questions from the preschool teachers help the children to pay attention to their exploration. Children who are guided to express their reflections in terms and words are challenged and included to participate in their learning process. The children get feedback on their questions and research continue.

A presente dissertação trata de um estudo teórico-experimental sobre escoamento monofásico e bifásico em um dissipador de calor baseado em microcanais. Este tipo de dissipador de calor tem sido usado para a intensificação da troca de calor em sistemas compactos e de alto desempenho. A intensificação da troca de calor promovida pelo escoamento em microcanais é acompanhada de um incremento na perda de pressão, portanto o estudo destes dois parâmetros é essencial para o entendimento dos fenômenos relacionados e fundamental para o desenvolvimento de ferramentas de projeto para dissipadores de calor baseados em microcanais. Inicialmente, um levantamento bibliográfico extenso sobre a ebulição convectiva em microcanais de reduzido diâmetro foi realizado. Este estudo da literatura trata de critérios de transição entre micro- e macro-escala, padrões de escoamento, métodos de previsão do coeficiente de transferência de calor e perda de pressão. Atenção específica foi dada a estudos de dissipadores de calor baseados em microcanais. Com base nesta análise da literatura, uma bancada experimental foi confeccionada para que dados experimentais de transferência de calor e perda de pressão pudessem ser levantados a partir de um dissipador de calor de microcanais. O dissipador de calor fabricado para este estudo é constituído de 50 microcanais retangulares dispostos paralelamente com 15 mm de comprimento, 100 µm de largura, 500 µm de profundidade e espaçados entre si de 200 µm. Experimentos foram executados para o R134a, velocidades mássicas de 400 a 1500 kg/m²s, título de vapor máximo de 0,35 e fluxos de calor de até 310 kW/m². Como conclusão deste trabalho observa-se perda de pressão elevada em relação aos valores fornecidos pelos métodos de previsão da literatura e um coeficiente de transferência de calor próximo ao estimado pelo modelo de três zonas proposto por Thome et al. (2004). / This study presents a theoretical and experimental investigation on single and two-phase flows in a microchannel based heat sink. Multi-microchannel heat sinks are able of dissipating extremely high heat fluxes under confined conditions. Such characteristics have attracted the attention of academia and industry and actually several studies are being carried out in order to evaluate and optimize such devices. Initially, an extensive investigation of the literature concerning convective boiling in micro-scale channels was performed. This literature review covers transitional criteria between micro- and macro-scale flow boiling, two phase flow patterns, heat transfer coefficient and pressure drop during convective boiling. Special attention was given to studies concerning microchannels based heat sinks. Based on this investigation, an experimental facility was built for performing heat transfer and pressure drop measurements during single-phase flow and flow boiling in microchannel based heat sinks. For this study, a microchannel based heat sink was also manufactured. The heat sink contains 50 rectangular parallel microchannels, 15 mm long, 100 µm wide by 500 µm deep and separated by 200 µm walls. Experiments were performed for R134a, mass velocity of 400-1500 kg/m²s, maximum vapor quality of 0,35 and heat fluxes up to 310 kW/m². The database obtained in the present study was compared against pressure drop and heat transfer coefficient prediction methods from the literature. It was found that no one method is accurate in predicting heat sink pressure drop while heat transfer coefficient results were accurately predicted by the 3-zone model proposed by Thome et al. (2004).

Orientador: Elaine Maria Cardoso / Resumo: A energia solar pode ser aproveitada como fonte de energia térmica para aquecimento de água, por exemplo, em coletores solares ou como fonte de energia elétrica usando sistemas de células fotovoltaicas. Entretanto, as células fotovoltaicas, geralmente, de custos relativamente altos, têm algumas restrições relacionadas a altas temperaturas de operação e distribuições de temperatura não homogêneas levando a redução da vida útil e eficiência elétrica de tais sistemas. Essas limitações têm sido o foco de pesquisas, a fim de melhorar as eficiências elétricas, regular as temperaturas de operação e reduzir os materiais necessários para fabricação das células. Assim, este projeto de pesquisa tem como objetivo avaliar o desempenho de um dissipador de calor, baseado em microcanais retangulares paralelos, no resfriamento de uma célula fotovoltaica de alta concentração (HCPV-High Concentration Photovoltaic Cell), utilizando-se de análise teórica (modelo térmico), simulação numérica (usando o software comercial CFD ANSYS® Fluent v15) e de uma bancada experimental. Neste trabalho, foram consideradas as condições de máxima radiação (denominado de pior cenário, quando a célula não gera eletricidade e todo o calor deve ser dissipado) e de radiação média ao longo do período considerado. Os dados climatológicos foram obtidos do site Canal Clima - UNESP, com dados historicos do clima na região noroeste paulista. Foi realizada uma revisão do estado da arte a fim de compreender como os sistemas de... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Solar energy can be used as a source of thermal energy in solar collectors, for example, or as a source of electricity using photovoltaic cell systems. However, photovoltaic cells requires high investments having some restrictions related to high operating temperatures and nonhomogeneous temperature distributions, leading to a reduction in the useful life and electrical efficiency. These limitations have been the focus of researches in order to improve electrical efficiencies, to regulate operating temperatures, and to reduce required materials in the cells. Thus, this research project aims to evaluate the performance of a heat sink based on parallel rectangular microchannels for cooling of a high concentration photovoltaic cell (HCPV), using theoretical analysis (thermal model), numerical simulation (using commercial software CFD ANSYS® Fluent v15) and an experimental bench. In this work, it was considered the conditions of maximum radiation (named worst scenario, when the cell does not generate electricity and all the heat must be dissipated) and the average radiation over the period considered. These climatological data were obtained from the Canal Clima – UNESP site, in the northwestern region of São Paulo state. A review on the subject was carried out in order to understand how solar photovoltaic systems can be optimized using solar concentrators and more efficient materials (multiple-junction cells). The influence of temperature and cooling systems were analyzed. An exp... (Complete abstract click electronic access below) / Mestre

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-04-07T00:24:20Z No. of bitstreams: 1 Posicionamento de Multiplos Sinks em RSSF com Priorizacao.pdf: 1718384 bytes, checksum: e4372e2075ce58446664e4be89f2676f (MD5) / Made available in DSpace on 2016-04-07T00:24:20Z (GMT). No. of bitstreams: 1 Posicionamento de Multiplos Sinks em RSSF com Priorizacao.pdf: 1718384 bytes, checksum: e4372e2075ce58446664e4be89f2676f (MD5) Previous issue date: 2015-12-15 / Wireless Sensor Networks can be used for environment monitoring, which may be in indoor scenarios such as in industries, warehouses and buildings, or in outdoor scenarios, just like forests, vulcanos and cities. Due to its energy supply limitations, researchers have been developing several approaches to reduce energy consumption in sensors and extend their lifetime. One of the ways to improve energy usage in a Wireless Sensor Network is by using multiple mobile sinks. In this work, a method to position multiple sinks in a relevance-based Wireless Sensor Network is proposed. After several simulations, it was observed that in applications where sensors have di erent importance levels, the network lifetime can be extended by using this approach. / Redes de Sensores Sem Fios podem ser utilizadas para o monitoramento de ambientes, sejam eles internos como ind ?strias, galp?es, constru??ess, ou externos como florestas, vulc?es, cidades, entre outros. Devido a sua limita ??o no fornecimento de energia, pesquisadores tem desenvolvido diversas abordagens para reduzir o consumo energ?tico nos sensores e prolongar seu tempo de vida. Uma das formas de melhorar o consumo de energia em uma Rede de Sensores Sem Fios e atrav?s do uso de m ?ltiplos sinks m oveis. Neste trabalho, e proposto um m ?todo para posicionamento de m ?ltiplos sinks em uma Rede de Sensores Sem Fios baseada em relev?ncias. Ap ?s diversas simula ??es, foi observado que em aplica ??es onde sensores possuem diferentes ni veis de import?ncia, o uso dessa abordagem aumenta o tempo de vida da rede.

The purpose of the study is find out what understanding the children at the age of 3 and 5 have of the physical phenomenon float and sink and to investigate whether a practical activity contributes to a deeper understanding of the phenomenon. Children at two departments at two different preschools participated in the study. Piaget’s stage theory was used to study how the children of different ages acted and expressed themselves during the activity. The investigations started with an initial discussion about the concepts of float and sink, which then turned into a practical exercise where the children had to make hypotheses and investigate the buoyancy of different objects. The activity ended with a discussion about what they had experienced through the pracitical activity. Sound recordings and field notes from the four groups’ implementation of the activity were complied and analyzed qualitatively. The results show that the practical activity contributed to the children creating a better understanding of the concepts of float and sink and that they began to use concepts relating to density. The practical activity helped to create curiosity and good communication, where the children themselves got to try it out practically. The three-year-olds created an understanding of where an artifact is in the water when it floats or sinks during the practical activity. The children began to use some concepts related to density, such as size, shape and weight. The survey showed that the 5-year-olds had an understanding of floating and sinking, but the practical activity contributed to them also them also starting to use concepts related to density concepts, and to a greater extent that the 3-year-olds. / Syftet med studien är att ta reda på vilken förståelse barnen i 3-årsåldern respektive 5-årsåldern har för det fysikaliska fenomenet flyta och sjunka samt att undersöka om ett praktiskt inslag bidrar till en fördjupad förståelse för fenomenet. I studien deltog barn från två avdelningar på två olika förskolor. Piagets stadieteori användes, för att studera hur barnen i de olika åldrarna agerade och uttryckte sig under aktiviteten. Undersökningarna startade med en inledande diskussion kring begreppen flyta och sjunka, som därefter övergick till en praktisk övning där barnen fick ställa hypoteser och undersöka olika föremåls flytförmåga. Aktiviteten avslutades med en diskussion om vad de har upplevt genom det praktiska inslaget. Ljudupptagning och fältanteckningar från de fyra gruppernas genomförande av aktiviteten sammanställdes och analyserades kvalitativt. Resultatet visar på att det praktiska inslaget bidrog till att barnen skapade en bättre förståelse för begreppen flyta och sjunka samt att de började använda sig av begrepp relaterade till densitet. Den praktiska aktiviteten bidrog till att skapa nyfikenhet och en god kommunikation, där barnen själva fick testa praktiskt. Treåringarna skapade en förståelse för var en artefakt befinner sig i vattnet när den flyter eller sjunker och under den praktiska aktiviteten började barnen använda några begrepp som relaterar till densitet som storlek, form och tyngd. Undersökningen visade att 5-åringarna hade en förståelse för flyta och sjunka men den praktiska aktiviteten bidrog till att de också började använda sig av densitets-begrepp, så även i högre grad än 3-åringarna.

Thesis submits concept of the sink fabrication technology where circular sink is made from rustproof austenitic steel 1.4301 (X5CrNi 18-10) using technology of conventional deep drawing without reducing wall’s thickness. Hydraulic press YL32 - 400 with nominal force 400 kN has been chosen as the production machine. Drawing tool with holder was designed to be used for this technology and its drawing documentation had been enclosed in this thesis. Size of the production series was set for 20 000 products annually. Control simulation of the drawing process has proven that designed component can be made and that computations are correct. Economic and technological estimation was performed which resulted in price being set for 555 czech crowns per piece. After manufacturing first 7 447 products the manufacturing process will become economically profitable.

The biodiversity value of a wetland is linked not only to its position in the landscape relative to other wetlands, but also to its habitat characteristics. I monitored amphibian species richness among 12 small, isolated, and undisturbed wetlands (which occur on lands permitted for phosphate mining) in central Florida during the 2005 and 2006 breeding seasons. I used seven habitat and landscape variables to characterize the environments of the wetlands and generalized linear models to determine which of these variables had the greatest influence on the occurrence of seven amphibian species (Anaxyrus terrestris, Gastrophryne carolinensis, Hyla gratiosa, Lithobates capito, L. catesbeianus, L. grylio, and Pseudacris nigrita verrucosa). Significant models for each species incorporated six of the seven habitat and landscape variables: distance to permanent water (2 spp.), distance to nearest wetland (3 spp.), vegetation heterogeneity (2 spp.), hydroperiod (2 spp.), presence/absence of fish (1 sp.), and distance to canopy cover (1 sp.). I suggest that source/sink metapopulation and patchy population dynamics in a given year are affected in part by environmental variables of ephemeral wetlands as they affect individual amphibian species. I suggest that a diversity of environmental conditions among wetlands produces the greatest amphibian biodiversity in this system, and that conservation and restoration efforts should emphasize environmental heterogeneity.

Objectives of the study were 1) To investigate patterns of career development of two successful Indian football through media analysis. 2) To identify factors of career success in male v/s female Indian football players. Methodology: This is a career development narrative study where media analysis was used. Two famous Indian football players (Aditi Chauhan and Sunil Chhetri) were chosen based on he/she had represented India at National and International level and had an extensive career of 15-20 years. As the players were not available to be interviewed, several types of media data were retrieved and analysed.Narrative thematic analysis and Holistic form structural analysis was performed for the stories of the players. Findings: within first analysis, seven career development themes were identified; how their interest got developed in sports, their entry into Indian football, their settlement into their football positions, international level exposures received by each, barriers experienced & sacrifices made by each, career difficulties v/s career incline, and their journey towards transition v/s retirement in their careers. Underlining the career stories, three factors (athletic, psychological, and psychosocial) were identified followed by five themes(planning & goal setting, routine, mindset of the player, motivation, and support system) and six subthemes (fitness & diet, growth, internal motivation, parents, and family) of perceived factors of career success of the footballers. Within second analysis, types of narratives were identified. For Aditi it was sink or swim narrative and for Sunil it was performance narrative. Discussion: Both stories reflected the positive side and negative side of sports. From the whole person and whole career approach three major athletic career stages came up for the athletes’ stories which was initiation, development, and discontinuation stages. Media data focussed on whole athlete and whole career approach where training, competitions, and personal life events got covered. Thus, suggested that perceived factors of success played a key role in career development of Indian football players.

Wood is often perceived as a flawed material. When painted, technologically treated or sealed, in a pursuit to make it more predictable and durable, some of its most important qualities are mislaid. This project explores the aesthetic, material and constructional possibilities of wood, and suggests the possibility of a wood brutalism architecture. The project includes a written manifesto for the benefits of wood in the human habitat, proposes a CO₂ based economic strategy for our built environment and promotes massive wood buildings as our carbon savings account. To find out what a wood brutalism of today might be, the project includes an analysis of the relationship between the material concrete, Betón-brut and the zeitgeist of the 60´s and 70´s. In the application of the manifesto and Bois-brut on a case study housing project in Östberga, Stockholm, the Trellick tower has acted as a brutalist mirror reference. Vernacular timber buildings have provided clues in the search for the essence of wood.

Future defense, aerospace and automotive technologies involve electronic systems that release high pulsed waste heat like during high power microwave and laser diode applications in tactical and combat aircraft, and electrical and electronic systems in hybrid electric vehicles, which will require the development of an efficient thermal management system. A key design issue is the need for fast charging so as not to overheat the key components. The goal of this work is to study the fabrication and technology implementation feasibility of a novel high energy storage, high heat flux passive heat sink. Key focus is to verify by theory and experiments, the practicability of using phase change materials as a temporary storage of waste heat for heat sink applications. The reason for storing the high heat fluxes temporarily is to be able to reject the heat at the average level when the heat source is off. Accordingly, a concept of a dual latent heat sink intended for moderate to low thermal duty cycle electronic heat sink applications is presented. This heat sink design combines the features of a vapor chamber with rapid thermal energy storage employing graphite foam inside the heat storage facility along with phase change materials and is attractive owing to its passive operation unlike some of the current thermal management techniques for cooling of electronics employing forced air circulation or external heat exchangers. In addition to the concept, end-application dependent criteria to select an optimized design for this dual latent heat sink are presented. A thermal resistance concept based design tool/model has been developed to analyze and optimize the design for experiments. The model showed that it is possible to have a dual latent heat sink design capable of handling 7 MJ of thermal load at a heat flux of 500 W/cm2 (over an area of 100 cm2) with a volume of 0.072 m3 and weighing about 57.5 kg. It was also found that with such high heat flux absorption capability, the proposed conceptual design could have a vapor-to-condenser temperature difference of less than 10 0C with a volume storage density of 97 MJ/m3 and a mass storage density of 0.122 MJ/kg. The effectiveness of this heat sink depends on the rapidness of the heat storage facility in the design during the pulse heat generation period of the duty cycle. Heat storage in this heat sink involves transient simultaneous laminar film condensation of vapor and melting of an encapsulated phase change material in graphite foam. Therefore, this conjugate heat transfer problem including the wall inertia effect is numerically analyzed and the effectiveness of the heat storage mechanism of the heat sink is verified. An effective heat capacity formulation is employed for modeling the phase change problem and is solved using finite element method. The results of the developed model showed that the concept is effective in preventing undue temperature rise of the heat source. Experiments are performed to investigate the fabrication and implementation feasibility and heat transfer performance for validating the objectives of the design i.e., to show that the VCTES heat sink is practicable and using PCM helps in arresting the vapor temperature rise in the heat sink. For this purpose, a prototype version of the VCTES heat sink is fabricated and tested for thermal performance. The volume foot-print of the vapor chamber is about 6"X5"X2.5". A custom fabricated thermal energy storage setup is incorporated inside this vapor chamber. A heat flux of 40 W/cm2 is applied at the source as a pulse and convection cooling is used on the condenser surface. Experiments are done with and without using PCM in the thermal energy storage setup. It is found that using PCM as a second latent system in the setup helps in lowering the undue temperature rise of the heat sink system. It is also found that the thermal resistance between the vapor chamber and the thermal energy storage setup, the pool boiling resistance at the heat source in the vapor chamber, the condenser resistance during heat discharging were key parameters that affect the thermal performance. Some suggestions for future improvements in the design to ease its implementation and enhance the heat transfer of this novel heat sink are also presented.