The scattering of polarized light by polydisperse systems of irregular particles
Polarized light scattering angle relationship with Mueller matrix elements for polydisperse systems of irregular randomly oriented particles
Gagne, G.↗
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Optical alignment device
A patent application was presented for an invention whose principal objective is the provision of an improved alignment device for observing the degree of coalignment of a pair of objects. The device includes a beamsplitter to be interposed between a pair of objects for observing the degree of coalignment. Light from one of the objects is reflected from the beamsplitter into a retroreflector which reflects the light back through the beamsplitter into an imaging system. Light from the other object is reflected from the beamsplitter into the same imaging system. The amount of displacement of the two images is inversely related to the degree of coalignment of the two objects. The optical alignment device is useful for aligning a mirror with an object, two objects or two mirrors.
Thomas, N. L.↗
Ocular input for human melatonin regulation: relevance to breast cancer
The impact of breast cancer on women across the world has been extensive and severe. As prevalence of breast cancer is greatest in industrialized regions, exposure to light at night has been proposed as a potential risk factor. This theory is supported by the epidemiological observations of decreased breast cancer in blind women and increased breast cancer in women who do shift-work. In addition, human, animal and in vitro studies which have investigated the melatonin-cancer dynamic indicate an apparent relationship between light, melatonin and cancer, albeit complex. Recent developments in understanding melatonin regulation by light in humans are examined, with particular attention to factors that contribute to the sensitivity of the light-induced melatonin suppression response. Specifically, the role of spectral characteristics of light is addressed, and recent relevant action spectrum studies in humans and other mammalian species are discussed. Across five action spectra for circadian and other non-visual responses, a peak sensitivity between 446-484 nm was identified. Under highly controlled exposure circumstances, less than 1 lux of monochromatic light elicited a significant suppression of nocturnal melatonin. In view of the possible link between light exposure, melatonin suppression and cancer risk, it is important to continue to identify the basic related ocular physiology. Visual performance, rather than circadian function, has been the primary focus of architectural lighting systems. It is now necessary to reevaluate lighting strategies, with consideration of circadian influences, in an effort to maximize physiological homeostasis and health.
Review↗
Fiber optic systems for mobile platforms III; Proceedings of the Meeting, Boston, MA, Sept. 7, 8, 1989
Various papers on fiber optic systems for mobile platforms are presented. Individual topics addressed include: architecture for fiber optic sensors and actuators in aircraft propulsion systems, fiber optic sensor system readiness for aircraft, microphone headset compatible with power by light, wavelength-division-multiplexed fiber optic sensors for aircraft applications, development of fly-by-light systems, fiber-optic-based inertial measurement unit, fault-tolerant architecture for a fly-by-light flight control computer, optically powered sensors for EMI-immune aviation sensing systems, infrared fiber optic fire sensors for space station applications. Papers on shipboard and automotive applications of fiber optic systems are also included.
Lewis, Norris E.↗
Gust alleviation system to improve ride comfort of light airplanes
System consists of movable auxiliary aerodynamic sensors mounted on fuselage and connected to trailing-edge flaps by rigid mechanical linkages. System achieves alleviation by reducing lift-curve slope of airplane to such a small value that gust-induced angles of attack will result in small changes in lift.
Stewart, E. C.↗
Universal Parameterization of Absorption Cross Sections
Our prior nuclear absorption cross sections model is extended for light systems (A less than or equal to 4) where either both projectile and target are light particles or one is a light particle and the other is a medium or heavy nucleus. The agreement with experiment is excellent for these cases as well. Present work in combination with our original model provides a comprehensive picture of absorption cross sections for light, medium, and heavy systems, a very valuable input for radiation protection studies.
Tripathi, R. K.↗
The scattering of polarized light by polydisperse systems of irregular particles
Scattering of polarized light by polydisperse systems of irregular particles
Holland, A. C.↗
The Demonstration of a Light Extinction Tomography System at the NASA Glenn Research Center's Icing Research Tunnel
A prototype light extinction tomography system has been developed for acquiring real-time in-situ icing cloud uniformity and density measurements in the NASA Glenn Research Center's Icing Research Tunnel (IRT). These measurements are currently obtained through periodic manual calibrations of the IRT. These calibrations are time consuming and assume that cloud uniformity and density does not greatly vary between the periodic calibrations. It is envisioned that the new light extinction tomography system will provide the means to make these measurements in-situ in real-time and minimize the need for these manual calibrations. This new system uses the principle of light extinction tomography to measure the spray density and distribution in the test section. The prototype system was installed and successfully demonstrated in the Icing Research Tunnel in early 2018. Data sets were acquired for several standard spray and simulated fault conditions to assess system capability and sensitivity. This paper will describe the prototype light extinction system, the theory behind it, and the results of the demonstration test that was conducted in the IRT.
Test Facility↗
The Demonstration of a Light Extinction Tomography System at the NASA Glenn Research Center's Icing Research Tunnel
A prototype light extinction tomography system has been developed for acquiring real-time in-situ icing cloud uniformity and density measurements in the NASA Glenn Research Center's Icing Research Tunnel (IRT). These measurements are currently obtained through periodic manual calibrations of the IRT. These calibrations are time consuming and assume that cloud uniformity and density does not greatly vary between the periodic calibrations. It is envisioned that the new light extinction tomography system will provide the means to make these measurements in-situ in real-time and minimize the need for these manual calibrations. This new system uses the principle of light extinction tomography to measure the spray density and distribution in the test section. The prototype system was installed and successfully demonstrated in the Icing Research Tunnel in early 2018. Data sets were acquired for several standard spray and simulated fault conditions to assess system capability and sensitivity. This paper will describe the prototype light extinction system, the theory behind it, and the results of the demonstration test that was conducted in the IRT.
Tomography↗
Space Age Archaeology
In 1985, the Egyptian Antiques Organization (EAO) asked Dr. Farouk El-Baz whether it would be possible to examine and sample the second chamber of the subterranean chamber carved in the bedrock near the Great Pyramid of Khufu in Giza, Egypt, without admitting people, air or contaminants. He felt it could by applying space technology to the task. The initial contact led to a two year project which he organized and headed a team, co-sponsored by EAO and the National Geographic Society (NGS), to apply space technology in an effort to examine and photograph the Giza Chamber. The NGS photographic division modified and tested a remotely controlled video system and a 35-millimeter camera, and developed a lighting system that would not elevate the chamber temperature. Still needed was a drill to cut through the limestone cap without using lubricants or cooling fluids that might contaminate the chamber, and an airlock that would admit the drill shaft and photo equipment but not the air. Bob Moores from Black & Decker Corporation tailored a new drill to the Giza exploration. The drill bit broke through into the chamber at a depth of 63 inches, a stainless steel tube was lowered through the airlock to take samples of the chamber air at several levels. The video camera sent images from the chamber revealing that there was a disassembled royal boat that had been there.
Source record↗
Evidence-Based Recommendations for Optimizing Light in Day-to-Day Spaceflight Operations
NASA Behavioral Health and Performance Element (BHP) personnel have previously reported on efforts to transition evidence‐based recommendations for a flexible lighting system on the International Space Station (ISS). Based on these recommendations, beginning in 2016 the ISS will replace the current fluorescent‐based lights with an LED‐based system to optimize visual performance, facilitate circadian alignment, promote sleep, and hasten schedule shifting. Additional efforts related to lighting countermeasures in spaceflight operations have also been underway. As an example, a recent BHP research study led by investigators at Harvard Medical School and Brigham and Women's Hospital, evaluated the acceptability, feasibility, and effectiveness of blue‐enriched light exposure during exercise breaks for flight controllers working the overnight shift in the Mission Control Center (MCC) at NASA Johnson Space Center. This effort, along with published laboratory studies that have demonstrated the effectiveness of appropriately timed light for promoting alertness, served as an impetus for new light options, and educational protocols for flight controllers. In addition, a separate set of guidelines related to the light emitted from electronic devices, were provided to the Astronaut Office this past year. These guidelines were based on an assessment led by NASA's Lighting Environment Test Facility that included measuring the spectral power distribution, irradiance, and radiance of light emitted from ISS‐grade laptops and I‐Pads, as well as Android devices. Evaluations were conducted with and without the use of off‐the‐shelf screen filters as well as a software application that touts minimizing the short‐wave length of the visible light spectrum. This presentation will focus on the transition for operations process related to lighting countermeasures in the MCC, as well as the evidence to support recommendations for optimal use of laptops, I‐Pads, and Android devices during all phases of spaceflight operations.
Whitmire, Alexandra↗
A stroboscopic technique for using CCD cameras in flow visualization systems for continuous viewing and stop action photography
A technique for synchronizing a pulse light source to charge coupled device cameras is presented. The technique permits the use of pulse light sources for continuous as well as stop action flow visualization. The technique has eliminated the need to provide separate lighting systems at facilities requiring continuous and stop action viewing or photography.
Franke, John M.↗
The Effect of Luminance Pattern on Nighttime Discomfort Glare Response - CRADA 653 (Abstract)
Light Emitting Diode (LED) adoption is critical for widespread energy savings from commercial outdoor lighting systems. A complaint from the public, concerns glare from LED light fixtures especially those with exposed LED arrays. This human factor study will examine luminance uniformity of the fixture aperture to identify parameters related to this response. The outcome will inform optical design by lighting manufacturers, retaining LED energy efficiency while mitigating glare. The results may also lead to improved industry standard glare metrics for lighting. Pacific Northwest National Laboratory’s (PNNL) Lighting Science and Technology Lab in Portland OR has a purpose-built apparatus with exposed LED arrays that have been used for prior work. It can easily be adapted for use in this experiment. Interchangeable templates will allow changing patterns for the stimulus. Glare ratings from the recruited subjects will be analyzed and reported in a peer-reviewed journal for application by luminaire manufacturers for improved products. The McClung Foundation’s interest is to better understand human perception of lighting, leading to more comfortable and effective visual environments. Members of the Foundation’s Technical Review Committee will be instrumental in reviewing the experimental design, analysis, and the final report. They will also help disseminate information about the results within the lighting community.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
SADE: A space experiment to demonstrate structural assembly
The Structural Assembly and Demonstration Experiment (SADE) demonstrates that the Shuttle is a suitable base for space construction; this includes a test of the Shuttle's control system to determine its performance when a long attached truss or beam is extended from the bay. Examples of Shuttle-related systems that will receive special attention are the RMS, the lighting system, and the crew assembly capabilities. A second purpose is to determine the extent to which the assembly results from the Neutral Buoyancy Simulator can be used to forecast the results of space assembly is determined. Finally, the SADE truss design will be validated by measuring the performance of the deployment, the special connectors, and the assembly methods.
Harrison, J. K.↗
Green-light supplementation for enhanced lettuce growth under red- and blue-light-emitting diodes
Plants will be an important component of future long-term space missions. Lighting systems for growing plants will need to be lightweight, reliable, and durable, and light-emitting diodes (LEDs) have these characteristics. Previous studies demonstrated that the combination of red and blue light was an effective light source for several crops. Yet the appearance of plants under red and blue lighting is purplish gray making visual assessment of any problems difficult. The addition of green light would make the plant leave appear green and normal similar to a natural setting under white light and may also offer a psychological benefit to the crew. Green supplemental lighting could also offer benefits, since green light can better penetrate the plant canopy and potentially increase plant growth by increasing photosynthesis from the leaves in the lower canopy. In this study, four light sources were tested: 1) red and blue LEDs (RB), 2) red and blue LEDs with green fluorescent lamps (RGB), 3) green fluorescent lamps (GF), and 4) cool-white fluorescent lamps (CWF), that provided 0%, 24%, 86%, and 51% of the total PPF in the green region of the spectrum, respectively. The addition of 24% green light (500 to 600 nm) to red and blue LEDs (RGB treatment) enhanced plant growth. The RGB treatment plants produced more biomass than the plants grown under the cool-white fluorescent lamps (CWF treatment), a commonly tested light source used as a broad-spectrum control.
Non-NASA Center↗
Perturbation analysis of internal balancing for lightly damped mechanical systems with gyroscopic and circulatory forces
Approximate expressions are developed for internally balanced singular values corresponding to the modes of mechanical systems with gyroscopic forces, light damping, and small circulatory forces. A brief overview is first given of the balanced realization model reduction method, including a discussion of recent work. The models considered are defined, and a perturbation analysis is used to show that the modal representation becomes asymptotically balanced as damping reduces to zero. The approximate balanced singular values are calculated, and a simple example of a flexible, dual-spin spacecraft is given as an illustration of the results.
Blelloch, P. A.↗
UV observations of x ray binaries
IUE (International Ultraviolet Explorer) has observed both high and low mass x ray binaries throughout its life. The UV spectra of high mass systems reveal the nature of the massive companion star and the effects of the x ray illumination of the stellar wind. In loss mass systems, the x ray illuminated disk or companion star dominates the UV light. System parameters and the characteristics of the accretion disk can be inferred.
Raymond, John C.↗
Brewer Recreational Facility Energy Modernization Project (Final Technical Report)
The project replaced a thirty-four-year-old metal halide lighting system on the City's primary athletic field with new energy efficient LED lighting, significantly reducing operating and maintenance cost while providing a safer environment, additional recreational opportunities, improved energy efficiency, and reduced light spillover.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗