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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Avaliação da influência de variáveis na produção de batentes de painel EGP de Pinus taeda / Evaluation of the influence of variables in the production of door frame of Edge Glued Wood Panel of Pinus taeda

Dias, Romulo Rezende [UNESP] 19 February 2016 (has links)
Submitted by Romulo Rezende Dias null (romulordias@yahoo.com.br) on 2016-03-17T20:12:40Z No. of bitstreams: 1 Dissertação Romulo Rezende Dias corrigida.pdf: 4489690 bytes, checksum: 9af841b8b53dd7ecfeee3773848e7168 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-03-21T18:27:40Z (GMT) No. of bitstreams: 1 dias_rr_me_guara.pdf: 4489690 bytes, checksum: 9af841b8b53dd7ecfeee3773848e7168 (MD5) / Made available in DSpace on 2016-03-21T18:27:40Z (GMT). No. of bitstreams: 1 dias_rr_me_guara.pdf: 4489690 bytes, checksum: 9af841b8b53dd7ecfeee3773848e7168 (MD5) Previous issue date: 2016-02-19 / O uso de madeira de pinus na construção civil é cada vez maior e saber trabalhar suas características, vantagens e desvantagens é essencial para o sucesso do produto. O presente trabalho tem por objetivo estudar a influência da largura das lamelas e do arranjo físico dos anéis de crescimento em painéis de madeira de Pinus taeda coladas lateralmente (EGP) utilizados na fabricação de batentes, seguindo as exigências da ABNT-NBR 15.930 (2011), a fim de determinar a melhor combinação para o melhor desempenho físico do produto. Para tanto, trabalhou-se com o fatorial completo para dois fatores e quatro níveis, sendo i. largura das lamelas de 32 mm, 56 mm, 75 mm e 112mm; e ii. arranjo dos anéis: lamelas radias, lamelas tangenciais, lamelas cruzadas e lamelas com emendas de topo tipo finger joint. Os 48 corpos de prova (03 para cada combinação) de batente de EGP com 2120 x 220 x 32mm, com teor de umidade entre 8% e 12% e densidade aparente entre 400 kg.m-3 e 600 kg.m-3 foram produzidos numa indústria madeireira da cidade de Sengés/PR. Utilizou-se a análise estatística de variância (ANOVA) para investigar a influência dos fatores e suas interações nas seguintes respostas: aspecto visual, variação da umidade, variação da densidade, variações dimensionais de largura e espessura e desvios de forma (empenamento: encurvamento, arqueamento e encanoamento). Os resultados mostraram que os dois fatores e suas interações exerceram influência com nível de significância de 1% sobre os desvios de forma. Os melhores resultados foram para painéis produzidos com lamelas de 32 mm e 56 mm, com arranjo cruzado ou radial. As demais respostas não foram influenciadas de forma significativa pelos fatores e suas interações. / The use of pine wood is increasing and for the success of its products it is essential to have the know-how to work its features, advantages and disadvantages. The objective of this study is to evaluate the influence of batten widths and the physical arrangement of growth rings in Edge Glued Panel of Pinus taeda used in the manufacture of door frames, according the requirements of ABNT-NBR 15.930 (2011) to determine the best combination for better physical performance of the door frame. Experimental tests considered the full factorial method using two factors and four levels, with batten widths of 32mm, 56mm, 75mm and 112mm; and arrangement of the growth rings: radial, tangential, crossed and plates with top amendments type finger joint. The 48 samples (03 from each combination), with 2120 x 220 x 32 mm, with a moisture content between 8% and 12% and an apparent density between 400 kg.m-3 and 600 kg.m-3 were produced in a wood factory in Sengés/PR/Brasil. The statistical analysis of variance (ANOVA) was used to investigate the influence of the factors and their interactions in the following responses: visual appearance, moisture content variations, density variations, dimensional variations in width and thickness and deviations in shape (warping: bending, curving and curling). The results showed that both factors and their interactions exerted influence with a significance level of 1% on the deviations of form. The best results were to EGP produced with batten widths of 32 mm and 56 mm, with radial or crossed arrangement. The factors and their interactions did not significantly influence the other answers.
2

Engineering Multicomponent Nanostructures for MOSFET, Photonic Detector and Hybrid Solar Cell Applications

Jamshidi Zavaraki, Asghar January 2015 (has links)
Silicon technologyhas been seekingfor a monolithic solution for a chip where data processing and data communication is performed in the CMOS part and the photonic component, respectively. Traditionally, silicon has been widely considered for electronic applications but not for photonic applications due to its indirect bandgap nature. However, band structure engineering and manipulation through alloying Si with Ge and Sn has opened new possibilities. Theoretical calculations show that it is possible to achieve direct transitions from Ge ifit is alloyed with Sn. Therefore, a GeSn system is a choice to get a direct bandgap. Extending to ternary GeSnSi and quaternary GeSnSiCstructures grown on Si wafers not only makes the bandgap engineering possible but also allowsgrowing lattice matched systems with different strain and bandgaps located in the infrared region. Different heterostructures can be designed and fabricated for detecting lightas photonic sensing oremitting the light as lasers. Alloying not only makes engineering possible but it also induces strain which plays an important role for electronic applications. Theoretical and experimental works show that tensile strain could increase the mobility, which is promising for electronic devices where high mobility channels for high performance MOSFETs is needed to speed up the switching rate. On the other hand, high n-doping in tensile strains in p-i-n structures makesΓ band transitions most probable which is promising for detection and emission of the light. As another benefit of tensile strain, the direct bandgap part shrinks faster than the indirect one if the strain amount is increased. To get both electronic and photonic applications of GeSn-based structures, two heterostructures (Ge/GeSn(Si)/GeSi/Ge/Si and Ge/GeSn/Si systems), including relaxed and compressive strained layers used to produce tensile strained layers, were designed in this thesis. The low temperature growth is of key importance in this work because the synthesis of GeSn-based hetrostructures on Si wafers requires low thermal conditions due tothe large lattice mismatch which makes them metastable. RPCVD was used to synthesize theseheterostructures because not only it offers a low temperature growth but also because it is compatible with CMOS technology. For utilization of these structures in devices, n-type and p-type doping of relaxed and compressive strained layers were developed. HRRLMs, HRTEM, RBS, SIMS, and FPP techniques were employed to evaluatestrain, quality, Sn content and composition profile of the heterostructures. The application of GeSn-based heterostructures is not restricted to electronics and photonics. Another application investigated in this work is photovoltaics. In competition with Si-based solar cells, which have, or areexpected to have,high stability and efficiency, thirdgeneration solar cells offer the use of low cost materials and production and can therefore be an alternative for future light energy conversion technology. Particularly, quantum dot sensitized solar cells are associated with favorable properties such as high extrinsic coefficients, size dependent bandgaps and multiple exciton generation and with a theoretical efficiencyof 44%. In this work, two categories of QDs, Cd-free and Cd-based QDs were employed as sensitizers in quantum dot sensitized solar cells (QDSSCs). Cd-based QDs have attracted large interest due to high quantum yield,however, toxicityremains still totheir disadvantage. Mn doping as a bandgap engineering tool for Cd-based type IIZnSe/CdS QDs wasemployed to boostthe solar cell efficiency. Theoretical and experimental investigations show that compared to single coreQDSSCs,typeII core-shells offer higher electron-hole separation due to efficient band alignment where the photogenerated electrons and holes are located in the conduction band of the shell and valence band of the core, respectively. This electron-hole separation suppresses recombination and by carefully designing the band alignment in the deviceit can increase the electron injection and consequently the power conversion efficiency of the device. Considering eco-friendly and commercialization aspects, three different “green” colloidal nanostructures having special band alignments, which are compatible for sensitized solar cells, were designed and fabricated by the hot injection method. Cu2GeS3-InP QDs not only can harvest light energy up to the infraredregion but can also be usedastypeII QDs. ZnS-coating was employed as a strategy to passivate the surface of InP QDs from interaction with air and electrolyte. In addition, ZnS-coating and hybrid passivation was applied for CuInS2QDs to eliminate surface traps. / <p>QC 20151125</p>

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