Search

Showing total 2 results
Start Over Search Limiters Peer Reviewed Topic emissivity Language english
2 results

1. Analysis of Fatigue Difference between Paper and Displays-Measurements of Near Point Distance.

Author

Inoue, Sonomi and Omodani, Makoto

Subjects
EMISSIVITY, EYESTRAIN, LIQUID crystal displays, ELECTRONIC paper, ELECTRONIC book readers
Abstract

Abstract Emissive screens are generally believed to be the main reason for eye fatigue when reading text on displays. This study examines the impact on eye fatigue of the reading style and medium: reflective or emissive. We test three media: paper, LCD (liquid crystal display with backlight), and electronic paper (book reader using electrophoretic reflective display). Eye fatigue levels in a reading task are evaluated under two reading styles (free condition and fixed condition) for the three media by measuring the increment in near point distances after each reading task. Subjects were requested to read a novel for 180 min using the three media. The fixed reading condition yielded a statistically significant increase of the near point distance on the three media, while the free condition showed no such increment, regardless of the medium. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

2. Infrared Emittance of Paper : Method Development, Measurements and Application

Author

Hyll, Caroline

Subjects
Paper, Mid-wavelength infrared, Absorptance, Sheet, Emissivity, LWIR, Reflectance, MWIR, Materials Engineering, Paper mechanics, Material properties, Long-wavelength infrared, Emittance, Thermography, Materialteknik, Papermaking, Transmittance, Angle-resolved, Physics::Accelerator Physics, Infrared, Directional, Moisture
Abstract

Thermography is a non-destructive technique which uses infrared radiation to obtain the temperature distribution of an object. The technique is increasingly used in the pulp and paper industry. To convert the detected infrared radiation to a temperature, the emittance of the material must be known. For several influencing parameters the emittance of paper and board has not previously been studied in detail. This is partly due to the lack of emittance measurement methods that allow for studying the influence of these parameters. An angle-resolved goniometric method for measuring the infrared emittance of a material was developed in this thesis. The method is based on the reference emitter methodology, and uses commercial infrared cameras to determine the emittance. The method was applied to study the dependence on wavelength range, temperature, observation angle, moisture ratio, sample composition, and sample structure of the emittance of paper and board samples. It was found that the emittance varied significantly with wavelength range, observation angle and moisture ratio. The emittance was significantly higher in the LWIR (Long-Wavelength Infrared) range than in the MWIR (Mid-Wavelength Infrared) range. The emittance was approximately constant up to an observation angle of 60° in the MWIR range and 70° in the LWIR range, respectively. After that it started to decrease. The emittance of moist samples was significantly higher than that of dry samples. The influence of moisture ratio on the emittance could be estimated based on the moisture ratio of the sample, and the emittance of pure water and dry material, respectively. The applicability of measured emittance values was demonstrated in an investigation of the mechanical properties of sack paper samples. An infrared camera was applied to monitor the generation of heat during a tensile test of a paper sample. It was found that the observed increase in thermal energy at the time of rupture corresponded well to the value of the elastic energy stored in the sample just prior to rupture. The measured emittance value provided an increased accuracy in the thermal energy calculation based on the infrared images. QC 20121121

Published
2012