Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 28 for “"up-conversion"”.
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A digital up-conversion architecture for future high efficiency wireless base stations
… This research is focused on the modulation and up-conversion circuits for generating the SMPA drive signals. The switched (‘on’/‘off’) nature of the amplifier drive signal creates an opportunity for an all-digital solution removing traditional analog components such as the digital to analog …
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Up-conversion In Rare-earth Doped Micro-particles Applied To New Emissive 2d Dislays
Up-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two …
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Design of optical characteristics of ceria nanoparticles for applications including gas sensing and up-conversion
… applications: dissolved oxygen (DO) sensing and up-conversion. In the first application, ceria doped with either Sm or Nd and ceria doped with aluminum have a strong correlation between the fluorescence quenching with the DO concentration in the aqueous solution in which the ceria nanoparticles …
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Development in utilizing singlet fission and triplet-triplet annihilation to improve solar cell efficiency
… and studied to increase solar cell power conversion efficiency. Singlet fission splits a singlet exciton into two lower energy triplet excitons. This energy down conversion is efficient and have shown near 200% triplet exciton yield. With energy down conversion, thermalization loss in …
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Design of software radio
… like decimation, interpolation, digital up-conversion and digital down conversion are done on reprogrammable Digital Signal Processor or Field Programmable Gate Arrays.Twelve laboratory exercises have been designed to lead the student through the process of using the Universal Software …
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Luminescent Lanthanide Complexes and Nanoparticles for Biological Applications
… sandwich complexes were isolated and explored as up-conversion (UC) emitters. These systems were designed to enable efficient energy transfer and direct excitation processes that enable near-infrared (NIR) excitation to produce emission in the visible region. The isolated complexes exhibited …
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Ruthenium alkynyl-terminated ladder-type oligo(p-phenylene)s
… bioimaging, photodynamic therapy, and frequency up-conversion lasing. In the first part of my PhD work, synthesis of a series of rigidified ladder-type oligo(p-phenylene)s end-functionalized by bis(dppe)-ligated ruthenium alkynyl units. Their optical, electrochemical and spectra electrochemical …
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Ruthenium alkynyl-terminated ladder-type oligo(p-phenylene)s
… bioimaging, photodynamic therapy, and frequency up-conversion lasing. In the first part of my PhD work, synthesis of a series of rigidified ladder-type oligo(p-phenylene)s end-functionalized by bis(dppe)-ligated ruthenium alkynyl units. Their optical, electrochemical and spectra electrochemical …
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Low-Power RF Front-End Design for Wireless Body Area Networks
… on our study, we proposed to adopt a direct conversion transmitter and a low-IF receiver architecture for the RF front-end. An asynchronous wake-up receiver was also proposed, which is composed of a carrier sensing circuit and a serial code detector. Third, we proposed and implemented …
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Zwei-Photonen-angeregte Fluoreszenz im Femtosekunden-Zeitfenster als neues Meßverfahren für die konfokale Mikroskopie
… 900nm möglich. Das Messverfahren beruht auf der Up-Conversion-Technik, die um eine aus dem invertierten zeitkorrelierten Einzelphotonenzählen abgeleitete Methode erweitert ist. Die aus der Reduktion der Rauschsignale resultierende Verbesserung der Messempfindlichkeit ermöglicht Untersuchungen an …
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A Mathematical Model of the Dynamics of an Optically Pumped Codoped Solid State Laser System
… model comprises five first order, nonlinear, coupled, ordinary differential equations which describe the temporal evolution of the dopant electron populations in the laser crystal as well as the photon density in the laser cavity. The analysis of the model is conducted in three parts.</p> …
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The photophysics of fluorescent protein chromophores
… state is probed using ultrafast fluorescence up-conversion with a time resolution of better than 50 fs. The excited states of chromophores decay on the ultrafast timescale. The decay will be probed for both isomers of the GFP chromophore, and the mechanism of decay will be modelled, leading to …
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Ultrafast excited state reaction dynamics in light-driven unidirectional rotary molecular motors and fluorescent protein chromophores
… is selectively probed by ultrafast fluorescence up-conversion with a time resolution better than 50 fs. Molecular motors have biphasic (sub-picosecond and picosecond) fluorescence decays and oscillations attributed to excitation of coherently excited vibrational modes. The fluorescence data were …
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Catalytic Activity of Tungsten-dioxo and Tungsten-diimido Complexes
… oxygen-rich materials will lead to potential up-conversion to carbon chemicals. Homogeneous catalytic deoxygenation processes present an opportunity to access valuable carbon commodity chemicals from biomass derived polyols. This dissertation details the design, development, and synthesis of …
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Powers scaling and nonlinear frequency conversion of single-frequency lasers based
… strategy reduces the effects of energy transfer up-conversion (ETU), which can decrease the lifetime of the upper lasing level and increase the heat generated per unit volume within the laser rod, increasing the effects of detrimental thermally related problems such as thermal lensing, …
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High efficiency resonant dc/dc converter for solar power applications
… and enables large (greater than 1:10) voltage conversion ratios, making the system suitable for large step-up conversion in applications such as distributed photovoltaic converters. Three 200 W prototypes were designed, built and tested. The first prototype was made as a proof of concept and …
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Gain and Noise Performance of Bi/Er Co-Doped Fibre Amplifiers
… amplifiers characteristics, including emission, up-conversion emission, ground state absorption, lifetime, cross section area, net gain and noise figure are introduced. Experiments on Erbium doped fibres (EDFs) and EDFAs under 980nm pump are carried out as a practice to familiarize myself with …
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Multiphase Isolated DC-DC Converters for Low-Voltage High-Power Fuel Cell Applications
… fuel cells must deal with a high voltage step-up conversion ratio and high input currents. Although many dc-dc converters have been proposed, most deal with high input voltage systems that focus on step-down applications, and such dc-dc converters are not suitable for low-voltage, high-power …
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Optical hot carrier solar cell: A general method of spectrum management in photovoltaics
… the thermalization losses during photovoltaic conversion. Such an optically-integrated system has the physical features of both a hot carrier solar cell and a spectrum up/down converter. Therefore, it is a valuable general method to explore spectrum management for solar cells. One goal of this …
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Processos de conversão ascendente de energia entre íons terras-raras em vidros como parte ativa de dispositivos: correlação entre coordenadas de cor e dose de radiação gama
… não lineares de conversão ascendente de energia (up-conversion) do tipo APTE (Adição de Fótons por Transferência de Energia), conhecido como Efeito Auzel, com vistas à exploração em dosímetros de larga faixa dinâmica de sensibilidade, explorando-se o fato de que variações do ambiente químico …
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