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At least 73 records · Page 4

UV-LED Project

UV-LED is part of a small satellite technologydemonstration mission that willdemonstrate non-contacting charge controlof an isolated or floating mass usingnew solid-state ultra-violet light emittingdiodes (UV-LEDs). Integrated tothe Saudisat-4 spacecraft and launchedonboard the Dnepr in June 19, 2014,the project is a collaboration betweenthe NASA Ames Research Center (ARC),Stanford University, and King AbdulazizCity for Science and Technology(KACST). This technology demonstrationwill validate a novel method of chargecontrol that will improve the performanceof drag-free spacecraft allowingfor concurrent science collection duringcharge management operations as wellas reduce the mass, power and volumerequired while increasing lifetime and reliabilityof a charge management subsystem.These improvements are crucial tothe success of ground breaking missionssuch as LISA and BBO, and demonstratethe ability of low cost small satellite missionsto provide technological advancesthat far exceed mission cost.

Soulage, Michael

Proton damage in LEDs with wavelengths above the silicon wavelength cutoff

This paper has examined the effects of proton damage on two types of LEDs in the wavelength region above the silicon bandgap limit. Unlike AlGaAs LEDs, the optical power linearity in both types of devices changes significantly after irradiation. This may be caused by the lower heterojunction barriers associated with these materials.

Johnston, Allan H.

The influence of ambient light spectrum (LED, INC, CFL, Xenon…) on the efficiency of perovskite indoor photovoltaic solar cells for Internet of Things (IoT) applications

This record provides a numerical investigation of a MAGeI₃-based perovskite solar cell with the structure FTO/TiO₂/MAGeI₃/Spiro-OMeTAD, evaluated for both outdoor and indoor light-harvesting applications using the SCAPS-1D simulator. Device performance is analyzed under AM 1.5G sunlight and several artificial light sources, including LED, incandescent, compact fluorescent lamp (CFL), flashlight, and xenon illumination. The study reports initial and optimized power conversion efficiencies and examines the influence of absorber layer thickness and bandgap on device performance under different lighting conditions. The results highlight the potential of MAGeI₃-based perovskite solar cells for indoor energy harvesting and low-power Internet of Things (IoT) applications.

14 SOLAR ENERGY

End-Use Savings Shapes Upgrade Package Documentation: LED Lighting, HP-RTU and ASHP-Boiler

Building on the successfully completed effort to calibrate and validate the U.S. Department of Energy's ResStock and ComStock models over the past 3 years, the objective of this work is to produce national data sets that empower analysts working for federal, state, utility, city, and manufacturer stakeholders to answer a broad range of analysis questions. The goal of this work is to develop energy efficiency, electrification, and demand flexibility end-use load shapes (electricity, gas, propane, or fuel oil) that cover a majority of the high-impact, market-ready (or nearly market-ready) upgrade measures, or upgrades. "Measures" refers to energy efficiency variables that can be applied to buildings during modeling. An end-use savings shape is the difference in energy consumption between a baseline building and a building with an energy efficiency, electrification, or demand flexibility upgrade applied. It results in a time-series profile that is broken down by end use and fuel (electricity or on-site gas, propane, or fuel oil use) at each time step. ComStock is a highly granular, bottom-up model that uses multiple data sources, statistical sampling methods, and advanced building energy simulations to estimate the annual subhourly energy consumption of the commercial building stock across the United States. The baseline model intends to represent the U.S. commercial building stock as it existed in 2018. The methodology and results of the baseline model are discussed in the final technical report of the End-Use Load Profiles project. This documentation focuses on an upgrade package of three end-use savings shapes upgrades - Light Emitting Diode (LED) Lighting, Heat Pump Rooftop Unit (RTU) (HP-RTU), and Air-Source Heat Pump (ASHP) Boiler, which we will refer to collectively as the "Interior Lighting and Heat Pump" package. More details on the individual upgrades can be found on the ComStock Measures Documentation page. An upgrade package applies two or more EUSS upgrades to a single building model simulation. Since ComStock is a bottom-up physics-based model, an upgrade package will go beyond aggregating or summing the individual upgrade results and produce novel results by simulating interactions between the upgrades. For example, pairing an envelope upgrade with an electrification upgrade would likely result in higher savings results than the sum of these upgrades individually, and the size of the heating, ventilating, and air conditioning (HVAC) equipment may be reduced if the envelope upgrade reduces the loads significantly.

29 ENERGY PLANNING, POLICY, AND ECONOMY

Half-ice, half-fire-driven ultranarrow phase crossover in one-dimensional decorated 𝑞-state Potts ferrimagnets: An AI-co-led exploration

OpenAI’s reasoning model o3-mini-high was used to carry out an exact analytic study of one-dimensional ferrimagnetic site- and bond-decorated 𝑞-state Potts models. We demonstrate that the finite-temperature ultranarrow phase crossover (UNPC), driven by a hidden “half-ice, half-fire” state recently discovered in the 𝑞=2 case (Ising model), persists for 𝑞>2. Moreover, we identify unique features for 𝑞>2, including the dome structure in the field-temperature phase diagram, and for large 𝑞 a secondary high-temperature UNPC to the fully disordered paramagnetic state. As the UNPC quickly approaches a genuine transition by enhancing 𝐽, the interaction between the backbone spins, two distinct behaviors emerge: In the site-decorated Potts model, 𝑇 0 is independent of 𝐽 and thus remains unchanged (Type-I UNPC), and in the bond-decorated Potts model with 𝑞>2, 𝑇 0 depends on 𝐽 and quickly shifts toward a finite temperature as 𝐽 increases (Type-II UNPC). These results establish a versatile framework for engineering controlled fast state-flipping switches in low-dimensional systems. Our nine-dan artificial intelligence (AI)-contribution framework assigns AI the meritorious status of AI-co-led discovery in this work.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND

Project Report: School Retrofit Demonstration of Lighting and Outlet Controls with LED Upgrades

A technology demonstration project funded by the U.S. Department of Energy (DOE) was hosted by Boston Public Schools (BPS). This project evaluated wireless controls technology for lighting systems and plug loads (energy consumed by devices plugged into electrical outlets), implemented along with LED lighting retrofits in two classrooms. This study assesses technology readiness and effectiveness to determine the deployment potential of the technology in schools.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI

Modification to the MED and LED source-encoding circuitry for the IMP H and J spacecraft

The circuitry and fabrication changes made on the MED and LED electronics cards for the IMP H and J are reported. Except for the noted changes, the circuitry and module-matrix arrangement is essentially the same as the IMP-1 electronics cards described. In addition, analysis of the IMP-1 transmitted data indicated the desirability of incorporating additional coincident-event threshold detection levels to further discriminate between received particles.

Garrahan, N. M.

LED pumped Nd:YAG laser development program

The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

Farmer, G. I.

Light pipes for LED measurements

Light pipe directly couples LED optical output to single detector. Small area detector measures total optical output of diode. Technique eliminates thermal measurement problems and channels optical output to remote detector.

Floyd, S. R.

Determination of radiative current in LED's

Directly measureable quantity of radiative output in LED's is total forward current. When applied forward voltage is below 1.05 V the forward current is primarily nonradiative and varies with forward voltage as exp(qV/2kT), when q is the charge, V is applied voltage, K is Boltzmann's constant, and T is operating temperature.

Thomas, E. F.

Scandium oxide antireflection coatings for superluminescent LEDs

For an employment of laser diodes as superluminescent LEDs (SLDs) or amplifiers, the facets of the diodes must be coated with antireflection films. In the work reported, scandium oxide was evaporated from an e-beam source onto Supersil II fused silica substrates. The obtained samples were used for measurements of absorption and reflectivity. Results of index measurements on e-beam evaporated films are presented. It is shown that excellent coatings with reflectivities of 0.00025 can be obtained using these films. Attention is given to the refractive indices for scandium oxide films as a function of wavelength, the power output vs current for laser before coating and after coating with Sc2O3.

Ladany, I.

HEAO-1 analysis of Low Energy Detectors (LED)

The activities at Penn State University are described. During the period Oct. 1990 to Dec. 1991 work on HEAO-1 analysis of the Low Energy Detectors (LED) concentrated on using the improved detector spectral simulation model and fitting diffuse x-ray background spectral data. Spectral fitting results, x-ray point sources, and diffuse x-ray sources are described.

Nousek, John A.

Increased Efficiency LED

In an LED a large portion of the light produced is lost due to total internal reflection at the air-semiconductor interface. A reverse taper of the semiconductor is used to change the angle at which light strikes the interface so that a greater portion of the light is transmitted.

Egalon, Claudio O.

2nd Generation Reusable Launch Vehicle NASA Led Propulsion Tasks

Design, development and test of a 2nd generation Reusable Launch Vehicle (RLV) is presented. This current paper discusses the following: 2nd Generation RLV Propulsion Project, Overview of NASA Led Tasks in Propulsion, Gen2 Turbo Machinery Technology Demonstrator, and Combustion Devices Test Bed, GRCop-84 Sheet For Combustion Chambers, Nozzles and Large Actively Cooled Structures

Richards, Steve