<p>An active optical shutter for infrared light (3-5 μm) has been designed, exploiting the phase transition in thermochromic vanadium dioxide (VO₂). A spin coating processing route for VO₂ films has been adapted to manufacture reproducible depositions onto sapphire (Al₂O₃) substrates. The VO₂ films have been characterized by X-ray powder diffraction (XRPD) and infrared spectroscopy (FTIR), showing 55 % transmittance in the open mode and 0.1 % in the closed mode.</p><p>The VO₂ film temperature determines the operating mode of the shutter, and a resistive circuit of gold was deposited on top of the film for heating purposes. Switching times from the open to the closed mode down to 15 ms have been measured.</p><p>This work is a part of a comprehensive project at the Swedish Defence Research Agency (FOI), aiming to improve active components for protection against lasers. The shutter within this work is at this stage an early prototype, and needs further development and complementary systems such as a control unit to be implemented in an optical system.</p>

In modern gas turbines parts of combustion chamber and turbine section are under heavy heat load, for example, the rotor inlet temperature is far higher than the melting point of the rotor blade material. These high temperatures causes thermal stresses in the material, therefore it is very important to cool the components for safe operation and to achieve desired component life. But on the other hand the cooling reduces the turbine efficiency, for that reason it is vital to understand and optimize the cooling technique. In this project Thermochromic Liquid Crystals (TLCs) are used to measure distribution of heat transfer coefficient over a scaled up combustor liner section. TLCs change their color with the variation of temperature in a particular temperature range. The color-temperature change relation of a TLC is sharp and precise; therefore TLCs are used to measure surface temperature by painting the TLC over a test surface. This method is called Liquid Crystal Thermography (LCT). LCT is getting popular in industry due to its high-resolution results, repeatability and ease of use. Test model in present study consists of two plates, target plate and impingement plate. Cooling of the target plate is achieved by impingement of air coming through holes in the impingement plate. The downstream surface of the impingement plate is then cooled by cross flow and re-impingement of the coolant air. Heat transfer on the target plate is not uniform; areas under the jet which are called stagnation points have high heat transfer as compare to the areas away from the center of jet. It is almost the same situation for the impingement plate but the location of stagnation point is different. A transient technique is used to measure this non-uniform heat transfer distribution. It is assumed that the plates are semi-infinitely thick and there is no lateral heat transfer in the plates. To fulfill the assumptions a calculated time limit is followed and the test plates are made of Plexiglas which has very low thermal conductivity. The transient technique requires a step-change in the mainstream temperature of the test section. However, in practical a delayed increase in mainstream temperature is attained. This issue is dealt by applying Duhamel’s theorem on the step-change heat transfer equation. MATLAB is used to get the Hue data of the recorded video frames and calculate the time taken for each pixel to reach a predefined surface temperature. Having all temperatures and time values the heat transfer equation is iteratively solved to get the value of heat transfer coefficient of each and every pixel of the test surface. In total fifteen tests are conducted with different Reynolds number and different jet-to-target plate distances. It is concluded that for both the target and impingement plates, a high Reynolds number provides better overall heat transfer and increase in jet-to-target distance decreases the overall heat transfer.

An active optical shutter for infrared light (3-5 μm) has been designed, exploiting the phase transition in thermochromic vanadium dioxide (VO2). A spin coating processing route for VO2 films has been adapted to manufacture reproducible depositions onto sapphire (Al2O3) substrates. The VO2 films have been characterized by X-ray powder diffraction (XRPD) and infrared spectroscopy (FTIR), showing 55 % transmittance in the open mode and 0.1 % in the closed mode. The VO2 film temperature determines the operating mode of the shutter, and a resistive circuit of gold was deposited on top of the film for heating purposes. Switching times from the open to the closed mode down to 15 ms have been measured. This work is a part of a comprehensive project at the Swedish Defence Research Agency (FOI), aiming to improve active components for protection against lasers. The shutter within this work is at this stage an early prototype, and needs further development and complementary systems such as a control unit to be implemented in an optical system.

Abstract This investigate is designated to the viewpoint that arrangement array of multichip modules are both staggered and in-line. Moreover, here we will discuss and compare the effects and differences of the relevantparameters caused by change Reynolds number (Re) in the experiment.In this experiment, I adopt ¡§transient heat transfer method with thermochromic liquid crystal¡¨ to research multichip modules array change to 3 ¡Ñ 5 and in-line or staggered multichip modules array to probe into the effects of over high density electronic multichip array space to length ratio to heat transfer effects when over high density electronic multichip array space to length ratio are S/L= 4/20,6/20,8/20 in the 8mm¡B12m¡B16mm respectively. The conditions are as following when every row center of chip convection heat transfer coefficient are measured: standard height to length ratio is H/L=10/20 and the height is 20mm. By observing the relationship of the varying parameters, as we can see in the analyze multichip of the experiment Re range form 1394 to 5025, we are able to improve thermal management. The experimentresule: (1) At higher values of Re the heat transfer effects are gain more,atteribute main flow field separation and reattachment is form behind the downstream modules. (2) In over high density multichip array 12S (S/L=6/20) proper are use for Re higher 4135 more than, at 8S (S/L=4/20)the lower Re can be thermocumulate in chip center. (3)When Re is 4135~5025,the heat transfer effects from staggered array is superior to in-line array. If Re range is 1394~3210,the thermal conduction is opposite. Therefore, Re is still the key that decides the efficacy of over high density electronic multichip array heat transfer effects.

O estudo busca esclarecer pontos essenciais sobre o emprego da termocromia em têxteis por meio de sua aplicação em estampas em camisetas, respondendo questões sobre o poder expressivo destas e do uso da termocromia como recurso de qualificação em projetos de Design de Superfície. A pesquisa traz dados históricos da camiseta como objeto de design e moda. Nesse contexto verificou-se a relevância dos esclarecimentos técnicos sobre o funcionamento da tinta termocrômica, assim como apresenta-se no estudo uma gama de produtos que se utilizaram da aplicação desta técnica, além de estudos acadêmicos considerados inovadores nessa área de conhecimento. O objetivo principal do estudo é explorar novos conhecimentos sobre os sistemas e técnicas em relação à aplicabilidade da termocromia em estampas de camisetas, bem como mostrar as capacidades subjetivas de comunicação/expressão e de interatividade em produtos com essa tecnologia, que podem servir como auxílio para os designers em projetos inovadores. Neste sentido, foram propostos estudos experimentais de aplicação de estampas com tinta termocrômica em camisetas, que deram o sentido fundamental a esta dissertação, acrescentando conhecimento e abrindo espaço para novas pesquisas no âmbito interdisciplinar. Neste estudo de caso exploratório, foi possível concluir, que os métodos mostrados aqui são fatores importantes de inovação para o setor têxtil e de moda e que os testes produzidos provaram a necessidade de rigor técnico contido nas especificações técnicas do fornecedor. / This study aims to clarify some fundamental questions related to textile thermochromism in the application of t-shirt printing, namely the expressive power of prints and the use of thermochromism as a resource in surface design. The investigation brings historical data regarding the t-shirt as an object of design and fashion. In this context, the importance of technical clarification related to the performance of thermochromic ink is verified and a range of products utilized in this technique are presented. A number of innovative academic studies in this area are also presented. The main objectives of this study are to investigate new knowledge about the applicability of systems and techniques utilized in thermochromic t-shirt graphics and to demonstrate the subjective capacity of expression and interaction of products that utilize this technology, which can serve as an aid to designers in innovative projects. From this perspective, experimental tests in the application of thermochromic t-shirt printing were proposed, providing significance to this thesis, enhancing the knowledge in this field and promoting further interdisciplinary research. In this exploratory case study it was possible to conclude that the methods shown here represent important innovations in the textile and fashion sectors and that the tests demonstrated the necessity of technical rigor regarding manufacturers’ technical specifications.

O estudo busca esclarecer pontos essenciais sobre o emprego da termocromia em têxteis por meio de sua aplicação em estampas em camisetas, respondendo questões sobre o poder expressivo destas e do uso da termocromia como recurso de qualificação em projetos de Design de Superfície. A pesquisa traz dados históricos da camiseta como objeto de design e moda. Nesse contexto verificou-se a relevância dos esclarecimentos técnicos sobre o funcionamento da tinta termocrômica, assim como apresenta-se no estudo uma gama de produtos que se utilizaram da aplicação desta técnica, além de estudos acadêmicos considerados inovadores nessa área de conhecimento. O objetivo principal do estudo é explorar novos conhecimentos sobre os sistemas e técnicas em relação à aplicabilidade da termocromia em estampas de camisetas, bem como mostrar as capacidades subjetivas de comunicação/expressão e de interatividade em produtos com essa tecnologia, que podem servir como auxílio para os designers em projetos inovadores. Neste sentido, foram propostos estudos experimentais de aplicação de estampas com tinta termocrômica em camisetas, que deram o sentido fundamental a esta dissertação, acrescentando conhecimento e abrindo espaço para novas pesquisas no âmbito interdisciplinar. Neste estudo de caso exploratório, foi possível concluir, que os métodos mostrados aqui são fatores importantes de inovação para o setor têxtil e de moda e que os testes produzidos provaram a necessidade de rigor técnico contido nas especificações técnicas do fornecedor. / This study aims to clarify some fundamental questions related to textile thermochromism in the application of t-shirt printing, namely the expressive power of prints and the use of thermochromism as a resource in surface design. The investigation brings historical data regarding the t-shirt as an object of design and fashion. In this context, the importance of technical clarification related to the performance of thermochromic ink is verified and a range of products utilized in this technique are presented. A number of innovative academic studies in this area are also presented. The main objectives of this study are to investigate new knowledge about the applicability of systems and techniques utilized in thermochromic t-shirt graphics and to demonstrate the subjective capacity of expression and interaction of products that utilize this technology, which can serve as an aid to designers in innovative projects. From this perspective, experimental tests in the application of thermochromic t-shirt printing were proposed, providing significance to this thesis, enhancing the knowledge in this field and promoting further interdisciplinary research. In this exploratory case study it was possible to conclude that the methods shown here represent important innovations in the textile and fashion sectors and that the tests demonstrated the necessity of technical rigor regarding manufacturers’ technical specifications.

O estudo busca esclarecer pontos essenciais sobre o emprego da termocromia em têxteis por meio de sua aplicação em estampas em camisetas, respondendo questões sobre o poder expressivo destas e do uso da termocromia como recurso de qualificação em projetos de Design de Superfície. A pesquisa traz dados históricos da camiseta como objeto de design e moda. Nesse contexto verificou-se a relevância dos esclarecimentos técnicos sobre o funcionamento da tinta termocrômica, assim como apresenta-se no estudo uma gama de produtos que se utilizaram da aplicação desta técnica, além de estudos acadêmicos considerados inovadores nessa área de conhecimento. O objetivo principal do estudo é explorar novos conhecimentos sobre os sistemas e técnicas em relação à aplicabilidade da termocromia em estampas de camisetas, bem como mostrar as capacidades subjetivas de comunicação/expressão e de interatividade em produtos com essa tecnologia, que podem servir como auxílio para os designers em projetos inovadores. Neste sentido, foram propostos estudos experimentais de aplicação de estampas com tinta termocrômica em camisetas, que deram o sentido fundamental a esta dissertação, acrescentando conhecimento e abrindo espaço para novas pesquisas no âmbito interdisciplinar. Neste estudo de caso exploratório, foi possível concluir, que os métodos mostrados aqui são fatores importantes de inovação para o setor têxtil e de moda e que os testes produzidos provaram a necessidade de rigor técnico contido nas especificações técnicas do fornecedor. / This study aims to clarify some fundamental questions related to textile thermochromism in the application of t-shirt printing, namely the expressive power of prints and the use of thermochromism as a resource in surface design. The investigation brings historical data regarding the t-shirt as an object of design and fashion. In this context, the importance of technical clarification related to the performance of thermochromic ink is verified and a range of products utilized in this technique are presented. A number of innovative academic studies in this area are also presented. The main objectives of this study are to investigate new knowledge about the applicability of systems and techniques utilized in thermochromic t-shirt graphics and to demonstrate the subjective capacity of expression and interaction of products that utilize this technology, which can serve as an aid to designers in innovative projects. From this perspective, experimental tests in the application of thermochromic t-shirt printing were proposed, providing significance to this thesis, enhancing the knowledge in this field and promoting further interdisciplinary research. In this exploratory case study it was possible to conclude that the methods shown here represent important innovations in the textile and fashion sectors and that the tests demonstrated the necessity of technical rigor regarding manufacturers’ technical specifications.

Philosophiae Doctor - PhD / Very few systems allow the study of the relationship between structural changes and physical properties in such a clear way as rare earth nickelate ReNi03 perovskites (Re (rare earth) = Pr, Nd, Sm and Gd). Synthesized for the first time by Demazeau et al [1] in 1971 and completely forgotten for almost twenty years, these compounds have regained interest since the discovery of high-temperature superconductivity and giant magnetoresistive effects in other perovskite-related systems. Due to its Metal-Insulator Transition (MIT) and thermochromic properties, the rare earth nickelate perovskite ReNi03 has received a great deal of attention for the past ten years in their thin films form [12]. Such unusual electronic and optical features are all the more interesting since the metal-insulator transition temperature (TMn) can be tuned by changing the Re cation: LaNi03 is metallic. No minimum of the metallic conductivity of Sm0 . ssNd 0.45Ni03, as observed by Gire et al [12] (entropic effect), was reported by Ambrosini and Hamet [11]. It has been suggested by Obradors et al. [13] that changing the rare earth cation in the ReNi03 system, acts as internal chemical pressure (increasing internal pressure by substituting the rare earth cation with another one of larger ionic radius) which can lead, as for the isostatic pressure experiment, to a tunability of the metal-insulator transition temperature [14, 15]. Obradors et al [13] reported on a decrease of T MIT upon increasing isostatic pressure but with remaining metallic properties of PrNi03 and NdNi03 (same magnitude and thermal dependence of the electrical resistivity)

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