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.
Results
Showing 1 to 20 of 93 for “"Light emitting diodes (LEDs)"”.
-
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) …
-
Towards the efficiency limit of visible light-emitting diodes
… to potentially enhance the efficiency of visible light-emitting diodes (LEDs) for high-power operation. By leveraging this special mode of solid-state lighting by incoherent electroluminescent radiation and with the focus on gallium-nitride (GaN) technologies, we experimentally demonstrate a …
-
Investigation Of A Floating Load Buck Dc-Dc Switching Converter
… designed to be used as a high-voltage off-line light-emitting diodes (LEDs) driver using a Texas Instruments' TPS92001 controller. Finally, the characteristics of this floating load buck converter LED driver were experimentally examined.</p>
-
Aluminum Gallium Arsenide-Indium Gallium Arsenide Crystal Growth, Buried Tunnel Contact Lasers, Wafer Bonding, and Alluminum Gallium Arsenide Oxide-Based VCSELs
… more sophisticated device structures including light-emitting diodes (LEDs) and VCSELs employing buried tunnel contact junctions.
-
A merged two-stage converter for LED lighting applications
Light Emitting Diodes (LEDs) are a very promising technology for developing more efficient lighting. For high-efficiency applications, a switching current regulator is necessary to control the power drawn by an LED string. This thesis investigates a merged two-stage LED driver for lighting …
-
Evaluation of potential applications for templated arrays of heterostructural semiconductor nanowires as light emitting devices
While light emitting devices, such as laser diodes (LDs) and light emitting diodes (LEDs), were first introduced decades ago, they have been the subject of continuing research and improvements due to their relatively poor performance. Evolution has occurred in both the design of light emitting …
-
Single-stage boost integrated asymmetrical half-bridge AC-DC power converter with dual modulation for indoor led lighting
Light emitting diodes (LEDs) for indoor lighting is a promising technology which can lead to major energy saving and cost reductions. The major concerns of improving power factor and regulating the output current ripple with regards to LED drivers has been addressed in this thesis by using dual …
-
Nanoscale optoelectronic properties in traditional and emerging materials for light-emitting diodes
… industry standard for inorganic blue and green light emitting diodes (LEDs), these devices suffer from efficiency droop at high current densities and material quality degradation at longer emission wavelengths. Establishing rational process design principles to address such issues remains …
-
Components, production processes, and recommendations for future research in organic light emitting diodes
Organic Light Emitting Diodes (OLEDs) are small, optoelectronic devices that can be used in the production of energy-efficient, high definition displays in cell phones, computers, and televisions. These devices have great potential to replace light emitting diodes (LEDs) completely because they are …
-
Thermal pumping of light-emitting diodes
… is a study of thermally enhanced injection in light-emitting diodes (LEDs). This effect, which we refer to as "thermal pumping", results from Peltier energy exchange from the lattice to charge carriers when current is injected into an LED. For an applied voltage V such that qV < (hw), where q …
-
Strategies for the future of lighting
… came from years of work in the solid-state lighting industry at Color Kinetics. My role there was mostly technical, but a bit of market understanding was involved. I wanted to gain a better understanding of the market forces at work, yet develop this understanding within a strong technical …
-
Psychophysical evaluations of modulated color rendering for energy performance of LED-based architectural lighting
… within an environment of a highly automated lighting control strategy. Digitally controlled lighting systems equipped with light emitting diodes, LEDs, can produce a range of different qualities of light, adjustable to users' requirements. In this context of unparalleled controllability, a …
-
Test vehicle detector characterization system for the Boeing YAL-1 airborne laser
… the radiant intensity of the gallium arsenide light emitting diodes (LEDs) and the forward current through the LEDs to correlate the expected irradiance with the observed detector counts. Illumination tests of different intensities are performed to characterize each detector's performance over …
-
Printed microscale inorganic light emitting diodes on flexible substrates for display, biomedical, and robotic applications
… to realize the high performance inorganic light emitting diodes (LEDs) on flexible substrate, ranging from bendable, to foldable, and to stretchable formats. In particular, advanced methods in materials growth, processing, mechanics, thermal design, and system manufacturing combine to …
-
Loop mediated isothermal amplification based detection of equine respiratory pathogens using a portable, smartphone-based setup
… that, when excited by appropriately selected light emitting diodes (LEDs) are visualized and automatically analyzed by a software application running on the smartphone microprocessor. The system achieves detection limits comparable to those obtained by laboratory-based methods and instruments. …
-
Design and analysis of fingernail sensors for measurement of fingertip touch fouce and finger posture
… the fingernail is instrumented with miniature light emitting diodes (LEDs) and photodetectors in order to measure changes in the reflection intensity when the fingertip is pressed against a surface or when the finger is bent. The changes in intensity are then used to determine changes in the …
-
Group III-nitride devices and applications
… success in recent years in the solid state lighting (SSL) and power electronics markets. The need for high efficient general lighting applications has driven research into InGaN based blue light emitting diodes (LEDs), and demand for more efficient power electronics for telecommunications …
-
Measurement of Thermal Impedance of Deep Ultraviolet Light Emitting Diodes
<p>Deep ultraviolet (DUV) light emitting diodes (LEDs) based on group III-Nitrides have numerous potential applications in water and air purification, food sterilization, ultraviolet curing, chemical and biological sensors, and medical instrumentation. However, DUV LEDs, with peak emission …
-
The Effect of Polarization and InGaN Quantum Well Shape in Multiple Quantum Well Light Emitting Diode Heterostructures
<p>Previous research in InGaN/GaN light emitting diodes (LEDs) employing semi-classical drift-diffusion models has used reduced polarization constants without much physical explanantion. This paper investigates possible physical explanations for this effective polarization reduction in InGaN LEDs …
-
The Study of the Forward-Voltage to Junction-Temperature Coefficient Degradation in Light-Emitting Diodes
Light-emitting diodes (LEDs) have recently become exceedingly popular in general lighting. As their popularity grows, the demand of more complex and more powerful systems grows as well. While optical characteristics are a crucial component of any lighting product, the main selling point of an LED …
Page 1 of 5