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Influence of Background Spectral Distribution on Perceptions of Discomfort Glare

Rensselaer Polytechnic Institute-Rohan M. Nagare, John D. Bullough
  • Technical Paper
  • 2020-01-0637
To be published on 2020-04-14 by SAE International in United States
The advent of light-emitting diode (LED) technology for automotive lighting allows flexibility of the spectral distribution of forward headlighting systems, while meeting current requirements for "white" illumination. As vehicle headlights have become whiter (with more short-wavelength light output) over the past several decades, their potential impacts on visual discomfort for oncoming and preceding drivers have been hotly debated. It is known that a greater proportion of short-wavelength energy increases discomfort glare, and that increasing the background light level (e.g., through roadway lighting) will decrease perceptions of discomfort. More recently it has been demonstrated that the visual system exhibits enhanced short-wavelength sensitivity for perceptions of scene brightness. As a result, roads illuminated by light sources with higher correlated color temperatures (CCTs) will be judged as appearing to be brighter than those illuminated to the same light level by sources with lower CCTs. The present laboratory study was conducted to identify whether the increased scene brightness of a road illuminated with greater short-wavelength light helps to mitigate discomfort glare more than the same scene illuminated to the…
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Virtual Switches and Indicators in Automotive Displays

General Motors LLC-Scott Rush
  • Technical Paper
  • 2020-01-1362
To be published on 2020-04-14 by SAE International in United States
Over the last decade, graphical and touch displays have become commonplace in automobile cockpits. Such displays have been used mainly for convenience functions such as navigation, radio, driver information, and vehicle settings. Automakers are now using these displays to generate “virtual” indicators that replace regulated and/or safety-critical physical indicators, such as gear position indication or the Malfunction Indicator Light [MIL]. Automakers are also replacing physical switches and controls, such as heating, ventilation, and air conditioning [HVAC] controls, with “virtual” controls rendered on the cockpit touch-screen. Many of these indicators and controls have regulatory and/or functional safety requirements that have been met using such methods as redundant terminals in a safety-critical switch, or by monitoring the electrical State-of-Health [SOH] of discrete LED indicators. Meeting these requirements with “virtual” graphical elements requires new electronic hardware and software technologies. This paper discusses recent advances in electronic hardware and System-on-Chip [SoC] solutions, operating systems, and supporting software architecture implementation of regulatory and/or functional safety graphics within cockpit displays. Application of the ISO 26262 standard, particularly section 5, and considerations…
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Unsteady Flow Analysis Method for Automobile LED Headlamp based on Massively Parallel CFD considering the External Environment

Hiroshima University-Takuji Nakashima
Kobe University-ChungGang Li, Makoto Tsubokura
  • Technical Paper
  • 2020-01-0636
To be published on 2020-04-14 by SAE International in United States
The aim of this study is to understand the mechanism of dew condensation and try to prevent it on automobile headlamp. In this case, it is necessary to accurately reproduce the complicated shape of the headlamp as the computational model. In addition, the simulation framework for predicting the turbulent flow field accompanied by the high heat source and the wall heat transfer with high accuracy in the vehicle running environment is required. Moreover, using CFD to understand the mechanism of the flow field inside the light emitting diode (LED) headlamp with a rotating fan to cool the light sources, is a challenging task because of the complicated internal structures and significant heat transfer. In this paper, we report that we tried constructing the simulation method of compressible turbulence based on hierarchical Cartesian grid using the HPC (High Performance Computing) environment. At first, we clarified the ventilation phenomenon through the vent holes in the uniform flow, and succeeded in obtaining the knowledge of ventilation control by changing the position and number of the vent holes. The…
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Fiber Optic Sensors for Aerospace Applications

AS-3 Fiber Optics and Applied Photonics Committee
  • Aerospace Standard
  • AIR6258
  • Current
Published 2020-01-30 by SAE International in United States
This document is intended to describe technologies available, application needs, and operational requirements relating to the use of fiber optic sensing systems on aerospace platforms: a To define standard terminology used in describing fiber optic sensing systems and their performance. b To identify current interfaces used for fiber optic sensing systems. c To define environmental, reliability, and maintainability capabilities of fiber optic sensing system components. d To describe the fiber optic sensor and instrumentation technologies that forms the current state of the art. e To describe current and future unmet needs of the aerospace industry for measurements using fiber optic sensors.
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Daytime visibility aspects under alternative use of headlamps

ARTEB-Carlos Alberto Leite de Moura
PRIME ONE-Paulo Victor S. Pingueiro
  • Technical Paper
  • 2019-36-0072
Published 2020-01-13 by SAE International in United States
Daytime visibility represents one of the most important themes in automotive safety. Some accidents, especially frontal collisions, used to occur as a result of a bad recognition of vehicle presence. In order to keep vehicles more visible during the day, there is a luminous device called Daytime Running Lamp (DRL). Nowadays DRL is not mandatory in Brazil, but it will be in 2021 for new vehicles. As with any situation that involves technological transitions, some questions appear, among them: how to equalize the market, in terms of daytime visibility, considering newer and older vehicles together? How to improve visibility in older vehicles that were not designed with DRL? The answer maybe lies in the alternative usage of automotive headlamps. Among other facts, one luminous device for two functions can result in safety improvements without unexpected investments. Therefore, how can this technically be achieved? By CONTRAN 667, that has adopted North America references, including luminous devices according to FMVSS, it is possible to use a low beam or a high beam dimmed to a maximum 7000…
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Effect of pressure cycling on gas exchange in a transparent fuel injector

Sandia National Laboratories, 7011 East Ave, 94550 Livermore-Paul M. Abers, Emre Cenker, Koji Yasutomi, Joonsik Hwang, Lyle M. Pickett
  • Technical Paper
  • 2019-01-2280
Published 2019-12-19 by SAE International in United States
Gas ingested into the sac of a fuel injector after the injector needle valve closes is known to have crucial impacts on initial spray formation and plume growth in a following injection cycle. Yet little research has been attempted to understand the fate sac gases during pressure expansion and compression typical of an engine. This study investigated cavitation and bubble processes in the sac including the effect of chamber pressure decrease and increase consistent with an engine cycle. A single axial-hole transparent nozzle based on the Engine Combustion Network (ECN) Spray D nozzle geometry was mounted in a vessel filled with nitrogen, and the nitrogen gas pressure was cycled after the end of injection. Interior nozzle phenomena were visualized by high-speed longdistance microscopy with a nanosecond pulsed LED back-illumination. Experimental results showed that the volume of gas in the sac after the needle closes depends upon the vessel gas pressure. Higher back pressure results in less cavitation and a smaller volume of non-condensable gas in the sac. But a pressure decrease mimicking the expansion stroke…
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Enhancing Flight Path Separation to Reduce Bird Strikes with Ultraviolet Radiation

SAE International Journal of Aerospace

Lite Enterprises, USA-Donald J. Ronning
  • Journal Article
  • 01-12-02-0005
Published 2019-10-29 by SAE International in United States
In the autumn of 2018, a pilot study using a prototype (PAR46 size) landing light that incorporated ultraviolet light emitting diodes (UVLEDs) was attached on a one-quarter scale remote controlled (RC) plane. The plane was flown in the direction of birds to measure their behavioral response to the approaching plane with landing lights either turned ON or OFF. Data were collected from multiple sources including cameras on the plane and the ground and a bird radar unit to measure the flight path separation between the plane and the birds. The purpose of this study was to determine the effectiveness of using UVLEDs integrated into a PAR46 landing light to trigger bird avoidance behavioral responses that would increase flight path separation to reduce the incidence of bird strikes. The findings showed the mean distance of the avoidance response was statistically significantly greater when the PAR46 landing light with UVLEDs was turned ON versus OFF. Field test data were used to create a three-variable model based upon recent neuroscience research corresponding to visual image capture, retinal neural…
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Vision Based Surface Roughness Characterization of Flat Surfaces Machined with EDM

BSA Crescent Institute of Science & Technology-Mahashar Ali, Siddhi Jailani, Mangalnath Anandan, Vignesh Pavithran
Vellore Institute of Technology-Murugan Mariappan
Published 2019-10-11 by SAE International in United States
Surface roughness measurement is an important one in any manufacturing next to dimensions. In this investigation, a vision system and image processing tools were used to develop reliable surface roughness characterization technique for Electrical Discharge Machined surfaces. A CMOS camera with red LED light source were used for capturing images of EDMed surfaces. A separate signal vector generated for all the images from its image pixel intensity matrices. The mean, skewness and kurtosis were obtained from the signal vector. The mean, skewness and kurtosis of the images signal vector correlates very well with the stylus measured hybrid roughness parameters Rda and Rdq. Hence the technique may be preferred for online surface roughness characterization of Electrical Discharge Machined (EDMed) surfaces.
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How to Use Rotary Encoders to Quickly Convert Mechanical Rotation into Digital Signals

  • Magazine Article
  • TBMG-35291
Published 2019-10-01 by Tech Briefs Media Group in United States

In the digital age, the measurement of rotation of a mechanical shaft on a motor or a rotating instrument knob needs to be done quickly and efficiently. Analog methods such as potentiometers and rotating switches are being replaced by rotary encoders that directly digitize rotary movement, but designers need to be able to appreciate the differences among various encoder types and accurately interpret their digital outputs.

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Photometric and Colorimetric Measurement Procedures for Airborne Electronic Flat Panel Displays

A-20A Crew Station Lighting
  • Aerospace Standard
  • ARP4260B
  • Current
Published 2019-09-17 by SAE International in United States
This SAE Aerospace Recommended Practice (ARP) contains methods used to measure the optical performance of airborne electronic flat panel display (FPD) systems. The methods described are specific to the direct view, liquid crystal matrix (x-y addressable) display technology used on aircraft flight decks. The focus of this document is on active matrix, liquid crystal displays (LCD). The majority of the procedures can be applied to other display technologies, however, it is cautioned that some techniques need to be tailored to different display technologies. The document covers monochrome and color LCD operation in the transmissive mode within the visual spectrum (the wavelength range of 380 to 780 nm). These procedures are adaptable to reflective and transflective displays paying special attention to the source illumination geometry. Photometric and colorimetric measurement procedures for airborne direct view CRT (cathode ray tube) displays are found in ARP1782. Optical measurement procedures for airborne head up displays (HUDs) can be found in ARP5287. Generally, the procedures describe manual single point measurements. The individual procedures may be readily incorporated into automated testing equipment…
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