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At least 19 records

Comparisons of luminaires: Efficacies and system design

Lighting designs for architectural (aesthetic) purposes, vision and safety, and plant growth have many features in common but several crucial ones that are not. The human eye is very sensitive to the color (wavelength) of light, whereas plants are less so. There are morphological reactions, particularly to the red and blue portions of the light spectrum but, in general, plants appear to accept and use light for photosynthesis everywhere over the PAR region of the spectrum. In contrast, the human eye interprets light intensity on a logarithmic scale, making people insensitive to significant differences of light intensity. As a rough rule, light intensity must change by 30 to 50% for the human eye to recognize the difference. Plants respond much more linearly to light energy, at least at intensities below photosynthetic saturation. Thus, intensity differences not noticeable to the human eye can have significant effects on total plant growth and yield, and crop timing. These factors make luminaire selection and lighting system design particularly important when designing supplemental lighting systems for plant growth. Supplemental lighting for plant growth on the scale of commercial greenhouses is a relatively expensive undertaking. Light intensities are often much higher than required for task (vision) lighting, which increases both installation and operating costs. However, and especially in the northern regions of the United States (and Canada, Europe, etc.), supplemental lighting during winter may be necessary to produce certain crops (e.g., tomatoes) and very useful to achieve full plant growth potential and crop timing with most other greenhouse crops. Operating costs over the life of a luminaire typically will exceed the initial investment, making lighting efficacy a major consideration. This report reviews tests completed to evaluate the efficiencies of various commercially-available High-Pressure Sodium luminaires, and then describes the results of using a commercial lighting design computer program, Lumen-Micro, to explore how to place luminaires within greenhouses and plant growth chambers to achieve light (PAR) uniformity and relatively high lighting efficacies. Several suggestions are presented which could encourage systematic design of plant lighting systems.

Albright, L. D.↗

Exploration Systems Exterior Lighting Design Guidance

Humans are returning to the Moon — this time, to stay. NASA has selected a location that maximizes line-of-sight communication with Earth, solar visibility, and access to water ice: the Lunar South Pole (LSP). While the Sun is more consistently in the lunar sky at the poles, it never rises more than 7° above the horizon in the target landing regions. This harsh lighting environment--never experienced during the Apollo missions or in human spaceflight--presents an engineering challenge: Support and protect functional vision. The human vision system, which despite having a high-dynamic range, cannot see well into bright light and cannot adapt quickly from bright to dark or vice versa. The design of helmets, windows, and lighting solutions must work in a complementary fashion to achieve a system of lighting and functional vision support that enables crews to see into darkness while their eyes are light-adapted and see in bright light while still dark-adapted that protects their eyes from injury. This report brings together information and identifies gaps related to LSP Natural environment (topology, regolith, temperature, lighting, and so forth), NASA historical experience exploring the Moon, human vision capabilities and needs, exploration operations, simulation capabilities and needs (for design verification, training, mission planning, and so forth) and existing engineering, safety, medical and performance requirements related to support human exploration.

Simulation↗

Security-by-Design: Light Water Small Modular Reactor

The growing demand for nuclear power is increasing pressure to find solutions to cost prohibitive requirements of both construction and security. Offsite response has been proposed as an option to reduce costs associated with training and maintaining an onsite response force. A previous report explored this option and revealed that security could be provided at the required level, but cost savings was not a result of this methodology. An offsite response strategy required costly active and passive delay barriers to provide sufficient time for responders to muster and deploy to a site in time to interrupt a determined and well-equipped adversary. Also, contrary to the hypothesis, the number of responders required for this strategy exceeded that needed for an onsite response force, as the adversaries could avail themselves of advantageous positions within the facility to repel arriving responders. This report builds upon the previous evaluation by using the same hypothetical light water small modular reactor (LWSMR) facility model, but this time an onsite response strategy was assessed. The goal of this analysis was to show that an onsite response strategy could be implemented effectively at a cost point that removes barriers within the industry at this critical time of growth and development. The assessment of the facility design and response strategy was completed through modeling using Scribe3D© and subsequent scenario analysis over the course of a two-day tabletop exercise. Subject matter experts in nuclear security, nuclear facility design, and response strategy and tactics contributed to the effort to ensure accurate representation of hypothetical scenarios. Several adaptations were made to the layout of the LWSMR based on lessons learned during the first day of scenario analysis. The subsequent design evaluated on the second day proved to provide a robust response posture against a large and well-trained adversary force. This report details the process of the analysis and compares the cost of the final facility design with that of the LWSMR model used for evaluation of offsite response. Ultimately, the results of this effort indicate that, when implemented correctly, an onsite response strategy is the best option from a security and cost perspective.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Light-trap design using multiple reflections and solid-angle attenuation - Application to a spaceborne electron spectrometer

The design and performance of a new light trap for a spaceborne electron spectrometer are described. The light trap has a measured photon-rejection ratio of 2 x 10 exp -11, allowing only one in 5 x 10 exp 10 incident photons to reach the sensitive area of the instrument. This rejection is more than sufficient because the ambient UV in earth orbit requires a rejection no better than 10 exp -8 to maintain the photon interference to less than 10 count/s. The light trap uses triple reflections to keep most of the light passing through the entrance slit away from the sensitive area of the spectrometer. It is shown that the average reflectance of all the internal surfaces must be less than 0.006, which is consistent with the data on the black coating applied to all surfaces. The analysis makes it possible to compare the photon contributions of each of the internal reflecting areas and to estimate the effective scattering width of the metallic electrode edge.

Herrero, Federico A.↗

Human-Building Collaboration: Toward lighting enabled collaborative system design

The profession of lighting design is evolving as contemporary lighting systems increasingly rely on cutting-edge computational technologies, sensors, and IOT systems. This trend requires designers to incorporate ideas of automation, dynamic controls, and user-system interaction into their design logic. However, real-time lighting simulations are constrained by inherent limitations arising from the reductive assumptions inevitably introduced in simulated lighting environments. This raises the question of how can designers account for the discrepancies between simulated and real lighting environments, and how can collaboration between humans and autonomous lighting systems bridge this gap. To address this question, we propose a protocol for designing collaborative interactions between humans and systems. Furthermore, this protocol builds on the Human-Lighting System Interaction Framework and demonstrates how human and system intelligence can be combined to fine-tune lighting qualities in a given space. Our paper shows how interactive lighting systems can customize lighting based on user preferences in real-time and how global lighting configurations can be adjusted over time. Specifically, we demonstrate: a) Human-system collaboration assumptions and goals, as well as how the protocol can be integrated into digitally programmable lighting systems. b) Implementations of collaboration that reveal how system autonomy, performance, and user experience are improved over short and long-term timeframes. c) How lighting design can be enhanced beyond simulation-driven design optimization capacities. The associated affordances and limitations are discussed with respect to existing lighting simulation design frameworks.

autonomous systems↗

Design of light- and chemically responsive protein assemblies through host-guest interactions

Host-guest (HG) interactions have been widely used to build responsive materials and molecular machines owing to their inherently dynamic nature, interaction specificity, and responsiveness to diverse stimuli. Here, in this work, we have set out to exploit these advantages of HG chemistry in the design of dynamic protein assemblies, using a C 4 symmetric protein, C98 RhuA, as a building block. We show that a C98 RhuA variant individually modified with β-cyclodextrin (βCD) (host) or azobenzene (guest) functionalities can specifically pair with each other to form highly ordered 1D and 2D assemblies. Association and dissociation of βCD RhuA- azo RhuA assemblies can be controlled by UV and visible light as well as by small-molecule modulators of βCD-azobenzene interactions. Kinetics analyses reveal that βCD RhuA- azo RhuA nanotubes assemble without a nucleation barrier, a highly unusual occurrence for helical supramolecular systems. Taken together, our findings provide a compelling example for achieving complex structural and dynamic outcomes in protein assembly through simple chemical design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Light Weight Design Nickel-Alkaline Cells Using Fiber Electrodes

Using fiber electrode technology, currently produced by Bekaert Corporation (Bekaert), Electro Energy, Inc., (EEI) Mobile Energy Products Group (formerly, Eagle-Picher Technologies, LLC., Power Systems Department) in Colorado Springs, CO has demonstrated that it is feasible to manufacture flight weight nickel-hydrogen cells having about twice the specific energy (80 vs. 40 watt-hr/kg) as state-of-the-art nickel-hydrogen cells that are flown on geosynchronous communications satellites. Although lithium-ion battery technology has made large in-roads to replace the nickel-alkaline technology (nickel-cadmium, nickel-metal hydride), the technology offered here competes with lithium-ion weight and offers alternatives not present in the lithium-ion chemistry such as ability to undergo continuous overcharge, reversal on discharge and sustain rate capability sufficient to start automotive and aircraft engines at subzero temperatures. In development to date seven 50 ampere-hour nickel-hydrogen have been constructed, acceptance tested and briefly tested in a low earth orbit (LEO) cycle regime. The effort was jointly funded by Electro Energy, Inc. and NASA Glenn Research Center, Cleveland, OH. Five of the seven cells have been shipped to NASA GRC for further cycle testing. Two of the cells experienced failure due to internal short circuits during initial cycle testing at EEL Destructive Physical Analysis (DPA) of one of the cells has shown the failure mode to be due to inadequate hydrogen catalyst electrodes that were not capacity balanced with the higher energy density nickel oxide electrodes. In the investigators opinion, rebuild of the cells using proper electrode balance would result in cells that could sustain over 30,000 cycles at moderate depths-of-discharge in a LEO regime or endure over 20 years of geosynchronous orbit (GEO) cycling while realizing a two-fold increase in specific energy for the battery or a 1.1 kg weight savings per 50 ampere-hour cell. Additional information is included in the original extended abstract.

Pickett, David F.↗

An Efficient and Effective Light Gas Gun Design for Millimeter-Scale Hypervelocity Testing

This paper serves to document a design for a light gas gun that was used for 3 decades at NASA’s Langley Research Center. By adapting readily-available equipment and supplies, this apparatus was capable of accelerating projectiles at up to 9 kilometers per second. The lack of a projectile-carrying sabot sacrifices some adaptability in projectile size, but results in a design that can be cleaned and cycled with far less labor input. Overall limitation on the projectile impact energies attainable effectively limit the applications to assessing the relatively thin shields employed for robotic spacecraft (as opposed to manned missions). The original gun has been decommissioned, but it is believed that this design has application for robotic spacecraft shield testing in the modern world, allowing cost-effective generation of larger sample sizes than with conventional sabot-based light gas guns.

Hypervelocity↗

An Efficient and Effective Light Gas Gun Design for Millimeter-scale Hypervelocity Testing

This paper serves to document a design for a light gas gun that was used for 3 decades at NASA’s Langley Research Center. By adapting readily-available equipment and supplies, this apparatus was capable of accelerating projectiles at up to 9 kilometers per second. The lack of a projectile-carrying sabot sacrifices some adaptability in projectile size, but results in a design that can be cleaned and cycled with far less labor input. Overall limitation on the projectile impact energies attainable effectively limit the applications to assessing the relatively thin shields employed for robotic spacecraft (as opposed to manned missions). The original gun has been decommissioned, but it is believed that this design has application for robotic spacecraft shield testing in the modern world, allowing cost-effective generation of larger sample sizes than with conventional sabot-based light gas guns.

Hypervelocity↗

An Efficient and Effective Light Gas Gun Design for Millimeter-Scale Hypervelocity Testing

This paper serves to document a design for a light gas gun that was used for 3 decades at NASA’s Langley Research Center. By adapting readily-available equipment and supplies, this apparatus was capable of accelerating projectiles at up to 9 kilometers per second. The lack of a projectile-carrying sabot sacrifices some adaptability in projectile size, but results in a design that can be cleaned and cycled with far less labor input. Overall limitation on the projectile impact energies attainable effectively limit the applications to assessing the relatively thin shields employed for robotic spacecraft (less useful for those used for manned missions). The original gun has been decommissioned, but it is believed that this design has application for robotic spacecraft shield testing in the modern world, allowing cost-effective generation of larger sample sizes than with conventional sabot-based light gas guns.

Scott Hull↗