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Provozní vlastnosti LED a jejich modelování / Operational Parameters of LED and their ModellingPavelka, Tomáš January 2017 (has links)
Doctoral thesis deals with parameters of LED light sources and their static and dynamic changes due to variable operational conditions. Firstly there is briefly described the history of light emitting diodes, that brought LED from unintentional observation of luminescence to light source, which is generally used through the whole area of lighting techniques. Thesis focuses on light parameters analysis, which are specific for semiconductor light sources and their mutual relations. These relations in compliance with understanding the principles of light emission in semiconductor light sources enable establishing of basic connections and effects usable for LED behaviour model. Mutual relations of LED parameters and influencing factors are verified by measurement of chosen testing samples. For deeper understanding of diode parameter influencing mechanisms there are analysed current degradation models including degradation of partial components. On the basis of these facts there is created a model of LED luminaire operating with LED parameters together with cooling system that represent the integral part of the luminaire. Impact of supply drivers is also studied, because they are necessary for LED operation. Designed model supports the area of static changes of light parameters, as well as the dynamic changes of output parameters. Presented model is verified by testing measurements at basic operational states and partially outside of the common operational limits. There are also presented the possibilities of real use of the model that involve the evaluation of designed luminaire for specific light sources, searching for optimal operational limits, optimization of luminaire heatsink or using public lighting systems for regulation of electricity grid load fluctuations.
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Construcción de la memoria a partir de la ficción: La hora final (2017) / Construction of memory from fiction: The Capture of the Century (1996) and The final hour (2017)Carranza Martínez, Rubí Clara 02 August 2021 (has links)
Este trabajo de investigación se centra en un análisis descriptivo de la narrativa audiovisual cinematográfica de una película a partir de hechos reales relacionados con el Conflicto Armado Interno que vivió el Perú entre los años 80 y 90, que dejó cerca de 69 mil muertos. El nombre del largometraje es el siguiente: “La hora final” (2017), el cual aborda el proceso de investigación policial y captura del líder de Sendero Luminoso, Abimael Guzmán. El eje central de investigación del trabajo es la identificación y análisis de los elementos de la película en cuestión en términos narrativos para determinar la forma en que se construye a partir de la ficción la memoria de hechos históricos relevantes para la historia del Perú. El presente trabajo propone un estudio cualitativo desde el paradigma interpretativo, se aplicará una guía de análisis de contenido a 9 escenas que han sido seleccionadas por su aporte a la narrativa del largometraje. / This research work focuses on a descriptive analysis of the cinematographic audiovisual narrative of a film based on real events related to the Internal Armed Conflict that Peru experienced between the 80s and 90s, which left about 69 thousand dead. The substitute for the feature film is the following: “La hora final” (2017), which deals with the processes of police investigation and capture of the Shining Path leader, Abimael Guzmán. The central research axis of the work is the identification and analysis of the elements of the film in question in narrative terms to determine the way in which the memory of historical events relevant to the history of Peru is constructed from fiction. The qualitative approach study proposes a qualitative study from the interpretive paradigm, a content analysis guide will be applied to 9 scenes that have been selected for their contribution to the narrative of the feature film. / Trabajo de investigación
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Colloidal Semiconductor Nanocrystals as Optoelectronic Materials: the Role of Ligands in Synthesis, Assembly and StabilityJiang, Guocan 12 June 2024 (has links)
Featuring size-tunable electrical and optical properties, semiconductor nanocrystals (NCs) attract intensive interest in developing promising functional materials for optoelectronic appli-cations. The surface ligands not only play an important role in the synthesis and colloidal sta-bility of NCs, but also significantly affect their photophysical and electrochemical properties. In this dissertation, I am dealing with the surface ligand engineering of NCs (including both perovskite and metal chalcogenide families) for optical and photocatalytic applications.
Polymer ligands are regarded to enable better colloidal stability, durability and processability of fluorescent NCs, which is especially important for perovskite NCs. However, the current wide-used polymer ligands fail to provide sufficient surface passivation for the NCs, which is unfavorable for their luminescence. To address this issue, a dual-ligand system based on par-tially hydrolyzed poly(methyl methacrylate) (h-PMMA) and highly branched polyethyl-enimine (PEI) was designed to stabilize perovskite NCs. The hydrophobic polymer of h-PMMA imparts excellent film-forming properties and durability to the resulting NC-polymer composite. The PEI forms an amino-rich, strongly binding ligand layer on the surface of the NCs being responsible for the significant improvement of the photoluminescence quantum yield and the stability of the resulting material. These superior properties allowed us to fabri-cate a proof-of-concept thin film organic light-emitting diode (OLED) with h-PMMA/PEI-stabilized perovskite NCs. A further insight into the roles of double polymer ligands (h-PMMA and PEI) during the mechanosynthesis of perovskites nanoparticles (NPs) was pro-vided. The h-PMMA can form micelles in the grinding solvent of dichloromethane to act as size-regulating templates for the growth of NPs. The PEI with large amounts of amino groups induced enrichment of PbBr2 in the reaction mixture, which in turn caused the formation of heterostructured CsPbBr3-CsPb2Br5-mPbBr2 and CsPbBr3-Cs4PbBr6-nCsBr NPs.
Not only polymer, but also inorganic ligands can be extremely attractive for capping of NCs. In the frame of this thesis, a two-step surface modification strategy was developed to control-lably destabilize the colloidal NCs, which in turn facilitated their 3D assembly into aerogels. Specifically, the long-chain oleic acid ligands were exchanged to the ultra-short-chain inorganic (NH4)2S ligands. These new ligands were further protonated by changing the dispersing solvent, which caused desired colloidal destabilization. The as-prepared CdSe NC aerogels with highly porous and self-supporting structure were found to be attractive for solid-state photocatalysis in a gas phase. Indeed, the (NH4)2S ligand is favourable for the adsorption and activation of substrate molecules (i.e., H2O and CO2) on the large open surface of NC gel, thereby promoting the progress of CO2 photoreduction. As a result, the photocatalytic activity for CO2 reduction of CdSe NC aerogels created in this work is 12-fold higher than that of the pristine non-assembled NC-precipitates.:Abstract 1
Contents 3
Abbreviations 6
List of Figures and Tables 8
1. Colloidal Semiconductor Nanocrystals and their Ligand Shell 13
1.1. Colloidal Semiconductor Nanocrystals 14
1.1.1. Inorganic Core of NCs 15
1.1.1.1. Metal Chalcogenide NCs 16
1.1.1.2. Metal Pnictide NCs 16
1.1.1.3. Halide Perovskites NCs 17
1.1.2. The Surface Ligands for NCs 18
1.1.2.1. The Classification of Surface Ligands based on Head-Groups 18
1.1.2.2. The Classification of Surface Ligands based on Tail-Groups 19
1.2. The Role of Ligands 20
1.2.1. The Role of Ligands in the Synthesis of NCs 20
1.2.2. The Role of Ligand in Colloidal NCs Dispersion and Stability 22
1.2.3. The Role of Ligand in the Light-Matter Interactions as Applied to NCs 24
1.3. The Surface Ligand Engineering of NCs 26
1.3.1. Introducing Ligands during the Synthesis 26
1.3.2. Introducing the Ligands during Post-Synthesis Process 27
1.4. Challenges to be Addressed in this Dissertation 29
2. Polymer Ligands Enhance the Stability and Fluorescence of Perovskite for Optical Application 31
2.1. Background and Motivation 32
2.2. Results and Discussion 34
2.2.1. Spectral Characterization 34
2.2.2. Morphological Characterization 40
2.2.3. Surface Composition 41
2.2.4. Processability, Stability and Durability 43
2.2.5. Green-LED 46
2.3. Conclusions 48
3. Polymer Ligands Assist Mechanosynthesis of Perovskite Nanoparticles 49
3.1. Background and Motivation 50
3.2. Results and Discussion 50
3.2.1 Morphology and Composition 51
3.2.2 Formation and Phase Conversion of the Nanoparticles 53
3.2.3. Spectral Characterization 58
3.3. Conclusions 60
4. Ligand Protonation Promote 3D Assembly of CdSe Nanocrystals for CO2 Photoreduction 62
4.1. Background and Motivation 63
4.2. Results and Discussion 64
4.2.1. The Gelation Method 64
4.2.2. Surface Composition of the NC Aerogels 67
4.2.3. Performance of CdSe-S Aerogels in Photoreduction of CO2 68
4.2.4. Photocatalytic Mechanism of the CdSe-S/Ni Aerogel 70
4.3. Conclusion 73
5. Conclusions and Perspectives 75
Appendix. Experimental Section 78
A.1. Reagents 78
A.2. NCs synthesis 78
A.2.1 Mechanosynthesis of Polymer-Coordinated Perovskite NCs 78
A.2.2 Oil Phase Synthesis of Colloidal CdSe NCs 79
A.2.3 Ligand Protonation-Promoted Assembly of CdSe-S NCs into Gel 79
A.3. Optical and Photocatalytic Applications of NCs 80
A.3.1 Optical Applications of Polymer-Stabilized Perovskite NCs 80
A.3.2 Photocatalytic Applications of CdSe-S Aerogels 80
A.4. Characterization Methods 81
A.4.1 Morphology Characterization 81
A.4.2.Element Characterization 81
A.4.3 Diffraction Characterization 82
A.4.4 Spectroscopy Characterization 82
A.4.5 Gas adsorption Measurement 82
A.4.6 Electrochemical Measurements 83
A.4.7 Other Characterizations 83
A.5. Additional Data 84
Bibliography 87
List of Publications 96
Acknowledgements 98
Erklärung 100
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Avalia??o da efici?ncia energ?tica de l?mpadas LED / Evaluation of the energy efficiency of LED lampsMiyashiro, Mauro Massanori 09 February 2017 (has links)
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Previous issue date: 2017-02-09 / Light Emmiting Diode ? LED. Efici?ncia energ?tica. Portaria n? 144/2015. INMETRO. Fator de pot?ncia. Fluxo luminoso. Efici?ncia energ?tica.
The objective of this study was to evaluate the energy efficiency of LED light bulbs (Light Emitting Diode) commercialized in the Brazilian market in the period of 2015/2016 and the development of a low cost test system to measure the mains voltage, current, consumption and power factor of LED lamp. For the evaluation of the LED lamps, the equipment available in the laboratories of the Eldorado Research Institute was used, and as a reference, the requirements established by Ordinance No. 144/2015 of the Instituto Nacional de Metrologia, Qualidade e Tecnologia - INMETRO, published on March 13, 2015. This Ordinance made it mandatory for manufacturers and importers to certify LED bulbs as of February 26, 2016. In order to carry out this work, a set of LED lamps from different manufacturers was acquired in the retail market to be subjected to functional tests of consumption of energy (watts), power factor (PF), luminous flux (lumens) and luminous efficiency (lumens/watt). The data obtained were compared with the nominal values declared by the manufacturers, as specified in the INMETRO ordinance. The results show that 11% of the samples failed in the energy consumption test and 83% failed in the power factor test. The developed test system was validated comparing its measurements with the results obtained in the tests carried out in INMETRO certified laboratory. Through this work it was possible to have an overview of the energy efficiency of LED bulbs currently commercialized in the country. / O presente trabalho teve como objetivo avaliar a efici?ncia energ?tica de l?mpadas com tecnologia LED (Light Emitting Diode) comercializadas no mercado brasileiro no per?odo de 2015/2016 e o desenvolvimento de um sistema de teste de baixo custo para medir a tens?o da rede el?trica, a corrente, o consumo e o fator de pot?ncia de l?mpada LED. Para a avalia??o das l?mpadas LED foram utilizados os equipamentos dispon?veis nos laborat?rios do Instituto de Pesquisas Eldorado e como refer?ncia os requisitos estabelecidos pela Portaria n? 144/2015 do Instituto Nacional de Metrologia, Qualidade e Tecnologia - INMETRO, publicada em 13 de mar?o de 2015. Esta Portaria tornou obrigat?ria para fabricantes e importadores a certifica??o das l?mpadas LED a partir de 26 de fevereiro de 2016. Para a realiza??o deste trabalho foi adquirido no mercado de varejo um conjunto de l?mpadas LED de diferentes fabricantes para serem submetidos a testes funcionais de consumo de energia (watts), fator de pot?ncia (FP), fluxo luminoso (lumens) e efici?ncia luminosa (lumens/watt). Os dados obtidos foram comparados com os valores nominais declarados pelos fabricantes conforme especificado na portaria do INMETRO. Os resultados demonstram que 11% das amostras falharam no teste de consumo de energia e 83% falharam no teste de fator de pot?ncia. O sistema de teste desenvolvido foi validado comparando suas medi??es com os resultados obtidos nos testes realizados em laborat?rio certificado pelo INMETRO. Atrav?s deste trabalho foi poss?vel ter um panorama amostral da efici?ncia energ?tica das l?mpadas LED comercializadas atualmente no pa?s.
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Fotometrie a spektroradiometrie zapouzdřených LED čipů / Photometry and spectroradiometry of LEDsVysoudil, Martin January 2012 (has links)
This thesis deals with the processing of light technical parameters and performance of key LED chips for their applications in lighting systems. The aim is to create a laboratory model for measuring the qualitative and quantitative parameters of highly luminous light LED emitted depending on the angle, using a spherical integrator 0.3 m, goniometer and fiber spektroradiometr /luxmeters. Goniometer is designed using modular optomechanical parts company Thorlabs. Due to the current passing through the LED chips heat up considerably. To light LED chip parameters tested were not affected by heat from the chip is required to pay the heat generated by a passive radiator. Another part of this thesis is the reconstruction of an older model spherical integrator. Reconstruction must be undertaken so as to ensure sufficient cooling again tested LEDs. Light scattered in the ball of the integrator is led by the optical cable to the spektroradiometr that are subsequently recorded its parameters. The second element used to measure the light produced by the LED source is photocell. Spherical integrator must be appropriately modified to indicate the two measuring elements and also meet the standards of determining the correctness of measurement. At the end of the measurement results will be compared with catalog values provided by the manufacturer.
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Marcas não tradicionais: mapeamento, problemática e experiência internacionalBarbas, Leandro Moreira Valente 05 August 2015 (has links)
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Previous issue date: 2015-08-05 / Fundo Mackenzie de Pesquisa / The scenario of tough competition, typical of any market economy, stimulates the creativity of its players when building brand identities. The search for signs that separate from the traditional model based on a visual static mark, classified as a sole design, word or mixed mark is increasingly common. Law cannot remain idle in witnessing this scenario, since those new distinctive signs have their own particularities that are not contemplated by the Brazilian Industrial Property Law. The protection of the consumer market, of free competition and even of the owners private property of the signs themselves depend necessarily on having clear answers from the Law regarding the issue. Otherwise, the trademark system may become unstable. Therefore, this work aims at defining basic concepts regarding the theme and analyzing the main legal issues related to nontraditional marks, having international experiences on the matter as a basis. / O cenário de acirrada competição típico de qualquer economia de mercado estimula a atividade criativa de seus participantes quando da construção de identidades marcárias. É cada vez mais constante e comum a busca por sinais que fogem ao modelo tradicional de marca visual estática, figurativa, mista ou nominativa. Estes sinais recebem o nome geral de marcas não tradicionais . O Direito não pode aí quedar-se inerte, uma vez que estes novos sinais distintivos têm peculiaridades próprias que fogem, em boa medida, à sistemática determinada pela Lei de Propriedade Industrial. Logo, a proteção do mercado consumidor, da livre concorrência e mesmo da propriedade privada dos titulares dos sinais passam necessariamente por uma obtenção de respostas claras do Direito neste tema, sob pena de instabilizar-se o sistema marcário. Esta obra tem o objetivo de delinear conceitos básicos sobre o tema das marcas não tradicionais e analisar as principais problemáticas jurídicas envolvidas, baseando-se em experiências internacionais na matéria.
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