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 49 for “"Light-emitting diode (LED)"”.
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Study of the Effect of Light Emitting Diode (LED) on the Optimum Window-to-Wall Ratio and Whole-Building Energy Consumption in Open Offices
Daylight harvesting is an essential strategy that is often used to enhance both the design and performance of an architectural project. Windows, as crucial architectural elements, not only admit natural light into spaces but also provide the occupants with visual connections. However, the excessive …
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High Efficiency SEPIC Converter For High Brightness Light Emitting Diodes (LEDs) System
… the characteristics of and driving methods for light emitting diode (LED) lamp system. A comprehensive overview on the lighting development is proposed. The characteristic of the light emitting diode (LED) lamp is described and the requirements of the ballast for the light emitting diode (LED) …
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An automotive interior lighting application using white light-emitting diodes
In this thesis the commercially available white light-emitting diode (LED) with its inherent efficiency, longevity and mechanical strength, is used to show, that success in energy efficiency can be obtained. Two cases are used to illustrate the need for efficient demand-side technology: the …
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White light emitting diode as liquid crystal display backlight
The discovery of high brightness (white) light emitting diode (LED) is considered as a real threat to the current lighting industry in various applications. One of the most promising sectors would be using white LED to replace the current Cold Cathode Fluorescent Light (CCFL) technology as the …
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Is LED use in traffic signals viable in the Texas Department of Transportation, Houston District?
Light Emitting Diode (LED) is used in traffic signals and highway illumination in the Texas Department of Transportation, Houston District (TxDOT). The thesis focuses on the cost of maintenance of the LED for signals on the highway system in the Houston District. This LED cost includes human and …
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An optical C.C.D. convolver
… a new method of implementing a charge-coupled device (CCD) transversal filter using optical input. The basic principle involves shining light from a signal-modulated light-emitting diode (LED) onto an optical mask which controls the amount of light reaching the various CCD electrodes. Some …
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Best practices for the sustainable scaleup of lighting technologies in bottom of the pyramid communities
… set of best practices for sustainably scaling up lighting technologies in developing countries with a focus on Bottom-of-the-Pyramid (BOP) communities, whose annual incomes are US $3000 or less (in local purchasing power parity). The best practices are derived from a comparative analysis of two …
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A strategy for the use of light emitting diodes by autonomous underwater vehicles
Light Emitting Diode (LED) technology has advanced dramatically in a few short years. An expensive and difficult to manufacture LED array containing nearly 100 individual LEDs and measuring at least 5 cm² can now be replaced by a single 5 Watt LED smaller than a quarter. As the light output for a …
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Electroluminescence characterization of organometallic perovskite solar cells
… these devices exhibit low voltage light emitting diode (LED) operation with thermally activated sub-bandgap voltage turn on and efficiency roll-off occuring before the bandgap voltage. with a maximum electroluminescence quantum efficiency (LED-EQE) of appoximately 14%, with an …
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Photonic crystal enhanced LED for electroluminescence cooling
An light-emitting diode (LED) consumes low-entropy electrical power and emits incoherent photons. In this process, the lattice heat also contributes to the output power if the LED operates at voltages below the photon energy (qV < h[omega]). Therefore, an LED can potentially cool itself, and the …
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Orthodontic bracket bond strength and resin composite adhesive degree of conversion associated with type of curing unit and total energy
This study examined the effect of light curing sources on shear bond strength and degree of conversion of orthodontic resin composite adhesive as function of type of curing unit and total energy, as well as evaluated the correlation between shear bond strength and degree of conversion. Curing units …
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Oxidation barrier and light protective packaging properties for controlling light induced oxidation in milk
Fluorescent light exposure has well documented negative effects on fluid milk through oxidation reactions. A shift to light-emitting diode (LED) lights in retail dairy cases has occurred due to increased energy efficiency, but the effects of LED light on fluid milk are not known. The objective was …
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Novel integrated paired emitter-detector diode flow analysis system
… on the concept of a Paired Emitter-Detector Diode (PEDD) LED optical sensor as a generic optical sensor platform for colorimetric analysis as developed within the research group. This research was funded by Science Foundation Ireland (SFI). This novel optical sensor employs two LEDs, …
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Structural and optical properties of phase transition cubic phase gallium nitride for photonic devices
… compounds (AlGaInN) have transformed the visible light emitting diode (LED) industry thanks to their direct bandgap across the entire visible spectrum and ultra violet. Despite its success, the conventional hexagonal-phase GaN has fundamental deficits that hinders performance. These include: …
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Microscale Energy Transport in Lead Halide Perovskites
… can be achieved when nonradiative lifetimes and light-emitting diode (LED) electroluminescence efficiencies exceed 2 μs and 10%, respectively. Next, we demonstrate that processes such as nonlinear recombination and photon recycling can have a significant impact on measured …
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Effects of Emergency Vehicle Warning Lighting System Characteristics on Driver Perception and Behavior
… medical service providers. The introduction of light emitting diode (LED) sources and advanced lighting control systems, provides a wide range of options for emergency lighting configurations. This study investigated the impact of lighting color, intensity, modulation, and flash rate on driver …
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Cubic phase gallium nitride photonics integrated on silicon(100) for next-generation solid state lighting
… compounds (AlInGaN) have transformed the visible light emitting diode (LED) industry thanks to their direct bandgap across the entire visible and ultraviolet spectra. Despite its success, the conventional hexagonal-phase GaN has fundamental disadvantages in performance and cost that hinder market …
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Two-dimensional crystals : spectroscopy and electronic applications
… (2D) crystals, starting with graphene, has unveiled new possibilities for next generation of ultrafast and ubiquitous electronics. One critical distinction between 2D crystals and 3D crystals is that 2D crystals are all-surface materials. Therefore, it is essential to understand how 2D materials …
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Integration of real time oxygen measurements with a 3D perfused tissue culture system
… optical fiber using a stochastic signal from a light emitting diode (LED). The response is then measured on a photodiode. System identification techniques are used to determine the relevant time constants which are subsequently converted to oxygen measurements. Application to real time …
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Evaluation of multiple and single emission peak light emitting diode light curing units effect on the degree of conversion and microhardness of resin-based pit and fissure sealant
… objective was to assess a multiple emission peak light-emitting-diode (LED) light-curing unit (LCU) by measuring the polymerization efficiency through the degree of conversion (DC) and Knoop microhardness (KHN) of a resin-based pit and fissure sealant at various light curing times and two …
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