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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Normal modes for electromagnetically induced transparency in a lambda system of degenerate energy levels

This paper presents an analytical study of the formation of normal modes of probe light for electromagnetically induced transparency in a lambda system of quantum transitions between {sup 3}P{sub 0}, and {sup 3}P{sub 2} levels in the case of an elliptically polarised control field and inhomogeneous broadening. The normal modes are elliptically polarised waves with identical polarisation ellipse eccentricities but different electric vector rotation directions. The mode eccentricities are only determined by the control field polarisation ellipse eccentricity. The major axis of the polarisation ellipse of one of the normal modes is parallel to the major axis of the control light polarisation ellipse, whereas the major axis of the polarisation ellipse of the other normal mode is perpendicular to it. The former type of mode has a higher group velocity than does the latter type of mode, and both velocities depend on control light polarisation ellipse eccentricity and intensity. Probe light with an arbitrary elliptical polarisation is the sum of normal modes which propagate independently of each other. Since the modes differ in group velocity, a probe pulse entering the medium splits into two components, each of which is a normal mode. The fraction of energy in each normal mode depends only on polarisation characteristics of coupled fields and is independent of their intensity. The bibliography includes 27 references. (nonlinear optical phenomena)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Integrated Controls Package for High Performance Interior Retrofit [Slides]

For the last few years, networked lighting control (NLCs) have promised significant energy savings beyond what is achieved through a basic light-emitting diode (LED) lighting retrofit. At the same time, NLCs can substantially increase the cost and complexity of the lighting retrofit. And as lighting system wattage declines because of the increasing efficiency of LEDs, advanced controls have less lighting energy to save and the cost-effectiveness of the NLC investment decreases. But NLCs can be leveraged to achieve significant energy savings and value by enhancing control of other building systems.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Characterizing Connected Lighting Systems

In the context of evaluating a lighting control system, characterization refers to the identification and description of key attributes and distinctive features of that system. NGLS has to date characterized both the form and function of 14 lighting control systems installed in the Living Lab at Parsons School of Design in New York City. The goal of NGLS characterizations in the Living Lab has been to achieve a broad understanding of “these types of systems” as a class, rather than a detailed description of any individual system.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS2010

Analysis and Design of Phase Change Thermal Control for Light Emitting Diode (LED) Spacesuit Helmet Lights

LED Helmet Extravehicular Activity Helmet Interchangeable Portable (LEHIP) lights for the Extravehicular Mobility Unit (EMU) have been built and tested and are currently being used on the International Space Station. A design is presented of the passive thermal control system consisting of a chamber filled with aluminum foam and wax. A thermal math model of LEHIP was built and correlated by test to show that the thermal design maintains electronic components within hot and cold limits for a 7 hour spacewalk in the most extreme EVA average environments, and do not pose a hazard to the crew or to components of the EMU.

Bue, Grant C.↗
DOE OSTI2019

The Value Proposition for Cost-Effective, Demand Responsive-Enabling, Nonresidential Lighting System Retrofits in California Buildings

Commercial lighting represents a significant potential source of demand response (DR) for the electrical grid, via traditional load shedding and rapid-dispatch (fast-DR) ancillary services when DR is enabled by networked lighting controls (NLCs). However, despite the significant opportunity and a regulatory push, DR-enabled lighting is installed in relatively few buildings because most building owners do not recognize its strong value proposition. Although NLCs can reduce energy bills, optimize facilities, and increase revenue, these co-benefits are not well quantified. This project analyzed lighting DR resources and energy-related co-benefits for commercial buildings in California. Using more than 100,000 individual hourly load profiles, the team forecasted the potential DR resources likely available from commercial lighting in 2025 and estimated revenues available from participation of these DR resources in energy markets. Combining these results with field-study estimates for NLC installation costs and energy savings provided a detailed accounting of site-level cost and energy-related co-benefits by building type from NLC’s DR enablement. In many cases, energy savings alone can deliver significant net value, justifying NLC DR-enabled adoption. Additionally, the study considers the sometimes-larger non-energy benefits (NEBs).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1988

Overview of NASA research in fiber optics for aircraft controls

The challenge of those involved in aircraft control system hardware development is to accommodate an ever-increasing complexity in aircraft control, while limiting the size and weight of the components and improving system reliability. A technology that displays promise towards this end is fiber optics. The primary advantages of employing optical fibers, passive optical sensors and optically controlled actuators are weight/volume reduction, immunity from electromagnetic effects, high bandwidth capabilities and freedom from short circuits/sparking contacts. Since 1975, NASA Lewis has been performing in-house, contract and grant research in fiber optic sensors, high temperature electro-optic switches and fly-by-light control system architecture. Passive optical sensor development is an essential yet challenging area of work and has therefore received much attention during this period. A major effort to develop fly-by-light control system technology, known as the Fiber Optic Control System Integration (FOCSI) program, was initiated in 1985 as a cooperative effort between NASA and DOD. Phase 1 of FOCSI, completed in 1986, was aimed at the design of a fiber optic integrated propulsion/flight control system. Phase 2 will provide subcomponent and system development and system testing. In addition to a summary of the benefits of fiber optics, the FOCSI program, sensor advances, and future directions in the NASA Lewis program are discussed.

Seng, Gary T.↗
DOE OSTI2015

April Burn-in Testing Report for Genentech B35, South San Francisco Campus

Genentech and Webcor reserved a thirty-day “burn-in” period after completion of the commissioning phase to conduct a detailed evaluation of all systems in the new HTA B35 building prior to occupancy. During this period, LBNL evaluated the automated shading and dimmable indoor lighting control systems to determine whether the systems were working according to design intent. LBNL also evaluated lighting energy use and visual and thermal comfort in the perimeter zones. LBNL conducted the monitored evaluation in four perimeter zones on the 7th floor from March 25th to May 7th, 2015. The daylight and tuning control functions of the dimmable LED direct-indirect lighting control system were evaluated and then adjusted in collaboration with the electrical contractor (Redwood Electric) during the first three weeks of the evaluation. The lighting controls were then considered to be operating as expected after April 20th and a detailed evaluation of control performance and energy use was conducted thereafter. The automated shading system was assessed over a limited period (April 15-30) on both the 6th and 7th floors to determine whether the controls raised the shade when discomfort glare was imperceptible. After a few days of analysis, changes were made to the settings to admit more daylight by changing both the glare sensor threshold and by increasing the depth of direct sun ingress from 36” to 48” from the façade on all orientations except the east.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Control of light polarization using optically spin-injected vertical external cavity surface emitting lasers

We fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well Vertical External Cavity Surface Emitting Laser (VECSEL). The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the electromagnetic field polarization using optical spin injection in the active medium of the VECSEL. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This result witnesses an efficient spin-injection in the active medium of the LASER.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Elliptically polarised normal modes under conditions of nonstationary electromagnetically induced transparency

We report the results of numerical simulation of the evolution of a weak elliptically polarised input probe pulse in the case of electromagnetically induced transparency in the field of elliptically polarised control light. It is shown that the electric field strength of any input probe pulse can be represented as a sum of the electric field strengths of two subpulses whose polarisation ellipses have the same constant eccentricities and mutually perpendicular directions of the major axes, one of these axes being parallel to the major axis of the polarisation ellipse of the control light. The directions of rotation of the electric field strength vectors of subpulses are mutually opposite. Subpulses move with different velocities in a medium, which leads to their spatial separation. In the propagation of subpulses, their polarisation characteristics (eccentricities and directions of major axes of polarisation ellipses) remain unchanged. At any stage of evolution, including the instants of significant spatial overlapping of subpulses, the intensity of the probe light in the medium is the sum of their intensities. Consequently, these subpulses are nonstationary mutually orthogonal elliptically polarised normal modes of the probe field whose existence is related to the medium anisotropy caused by the control field. The simulation is carried out for a scheme of degenerate quantum transitions between {sup 3}P{sub 0}, {sup 3}P{sup 0}{sub 1} and {sup 3}P{sub 2} levels of the 208Pb isotope, taking into account the Doppler broadening of the spectral lines under the assumption that the probe field has a higher frequency than the control field. (nonlinear optical phenomena)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Evaluation of an LED Retrofit Project at Princeton University's Carl Icahn Laboratory

At Princeton University’s Carl Icahn Laboratory, DOE’s Commercial Buildings Integration Program documented the implementation of LED retrofit products for recessed troffers, linear cove lighting, and downlights – as part of Princeton’s first building-wide interior LED project. The conversion to LED enables more extensive use of lighting controls to tailor the lighting to the task and limit the operating hours based on occupancy, and the estimated energy savings including controls is 62% compared to the incumbent system.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS2020

Landsat 9 Mission Update and Status

Landsat 9 is currently undergoing testing at the integrated observatory level in preparation for launch from Vandenberg Air Force Base in 2021. Landsat 9 will replace Landsat 7 in orbit, 8 days out of phase with Landsat 8. Landsat 9 is largely a copy of Landsat 8 in terms of instrumentation, with an Operational Land Imager (OLI), model #2 and a Thermal Infrared Sensor (TIRS), model #2. The TIRS-2 is more significantly changed from TIRS with increased redundancy, as well as changes to the telescope baffling to improve stray light control and a revised scene select mirror encoder mechanism. Data quality of the Landsat 9 instruments is comparable to, or better than the Landsat 8 ones, with an increase to 14 bits of data transmitted and more detailed pre-launch characterization for OLI-2, and with more detailed characterization of the TIRS-2 pre-launch, in addition to the improved stray light control. The performance of the two instruments is summarized and compared to that of the Landsat 8 instruments.

Brian Markham↗
DOE OSTI2020

Method for dynamic control of light emission from phosphors with heat excitations

An optically emissive material and, in particular, materials for use in single photon generation technologies, have multiple excited energy states that have different decay rates and can emit photons with different properties. A primary excitation radiation source is configured to apply primary radiation to an optically emissive material to excite the optically emissive material into a primary excited state. A secondary excitation radiation source is configured to apply secondary radiation to a thermal contribution material to generate thermal energy in the thermal contribution material. The thermal contribution material is physically configured to transfer thermal energy to the optically emissive material and excite the optically emissive material from the primary excited state to a secondary excited state for dynamic control of the emission rate, or emitted photon properties, of the optically emissive material.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Light-dependent controlled synthesis and photocatalytic properties of stable Ag{sub 3} nanocrystals

The silver phosphate (Ag{sub 3}PO{sub 4}) is applied in organic matter photodegradation as a novel catalyst materials, however, its instability reduces the photocatalytic life and limits its further applications. In this work, a series of Ag{sub 3}PO{sub 4} crystalline nanoparticle clusters have been synthesized by a photocontrol method. By comparing their sunlight photocatalytic properties, the Ag{sub 3}PO{sub 4} nanoparticles with dominant (2 2 0) facets have a lower surface energy (1.05 J m{sup −2}) than existing Ag{sub 3}PO{sub 4} crystals which can offer a longer catalyst service life. The photodegradation rate of the Ag{sub 3}PO{sub 4} nanoparticles is about 3 times that of common Ag{sub 3}PO{sub 4} bulk materials and the sunlight is used as the power source instead of high cost artificial visible light sources in this catalytic system. An effective continuous photodegradation reactor using Ag{sub 3}PO{sub 4} nanoparticles is successfully fabricated to degrade rhodamine B solution. At the same time, this work provides an example for how oxidation photocatalyst works without extra adding sacrificial reagent.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Integrated optical and electrical modeling of plasmon-enhanced thin film photovoltaics: A case-study on organic devices

The nanoscale light control for absorption enhancement of organic photovoltaic (OPV) devices inevitably produces strongly non-uniform optical fields. These non-uniformities due to the localized optical modes are a primary route toward absorption enhancement in OPV devices. Therefore, a rigorous modeling tool taking into account the spatial distribution of optical field and carrier generation is necessary. Presented here is a comprehensive numerical model to describe the coupled optical and electrical behavior of plasmon-enhanced polymer:fullerene bulk heterojunction (BHJ) solar cells. In this model, a position-dependent electron-hole pair generation rate that could become highly non-uniform due to photonic nanostructures is directly calculated from the optical simulations. By considering the absorption and plasmonic properties of nanophotonic gratings included in two different popular device architectures, and applying the Poisson, current continuity, and drift/diffusion equations, the model predicts quantum efficiency, short-circuit current density, and desired carrier mobility ratios for bulk heterojunction devices incorporating nanostructures for light management. In particular, the model predicts a significant degradation of device performance when the carrier species with lower mobility are generated far from the collecting electrode. Consequently, an inverted device architecture is preferred for materials with low hole mobility. This is especially true for devices that include plasmonic nanostructures. Additionally, due to the incorporation of a plasmonic nanostructure, we use simulations to theoretically predict absorption band broadening of a BHJ into energies below the band gap, resulting in a 4.8% increase in generated photocurrent.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2007

Guaranteeing Pointing Performance of the SDO Sun-Pointing Controllers in Light of Nonlinear Effects

The Solar Dynamics Observatory (SDO) mission is the first Space Weather Research Network mission, part of NASA s Living With a Star program.1 This program seeks to understand the changing Sun and its effects on the Solar System, life, and society. To this end, the SDO spacecraft will carry three Sun-observing instruments to geosynchronous orbit: Helioseismic and Magnetic Imager (HMI), led by Stanford University; Atmospheric Imaging Assembly (AIA), led by Lockheed Martin Space and Astrophysics Laboratory; and Extreme Ultraviolet Variability Experiment (EVE), led by the University of Colorado. Links describing the instruments in detail may be found through the SDO web site.2 The basic mission goals are to observe the Sun for a very high percentage of the 5-year mission (10-year goal) with long stretches of uninterrupted observations and with constant, high-data-rate transmission to a dedicated ground station. These goals guided the design of the spacecraft bus that will carry and service the three-instrument payload. At the time of this publication, the SDO spacecraft bus is well into the integration and testing phase at the NASA Goddard Space Flight Center (GSFC). A three-axis stabilized attitude control system (ACS) is needed both to point at the Sun accurately and to keep the roll about the Sun vector correctly positioned. The ACS has four reaction wheel modes and 2 thruster actuated modes. More details about the ACS in general and the control modes in particular can be found in Refs. [3-6]. All four of SDO s wheel-actuated control modes involve Sun-pointing controllers, as might be expected from such a mission. Science mode, during which most science data is collected, uses specialized guide telescopes to point accurately at the Sun. Inertial mode has two sub-modes, one tracks a Sun-referenced target orientation, and another maintains an absolute (star-referenced) target orientation, that both employ a Kalman filter to process data from a digital Sun sensor and two star trackers. However, this paper is concerned only with the other two modes: Safe Hold (SH) and Sun Acquisition (SA).

Starin, Scott R.↗