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Fundamentals of Ocean Optics
Published in Victor Raizer, Optical Remote Sensing of Ocean Hydrodynamics, 2019
In photometry— Luminous energy (Joule—J = Ws): photometrically weighted radiant energy (energy of light).Luminous energy density (J/m3): photometrically weighted radiant flux density.Luminous flux (lumen—lm): radiant flux evaluated in terms of a standardized visual response.Luminous intensity (candela—cd): luminous flux per unit solid angle in a certain direction.Luminous exitance (lm/m2): total luminous flux given out per unit area.Luminance (cd/m2): photometrically weighted radiance (brightness perception).Illuminance (lux—lx): luminous flux incident on a surface, per unit area.
The Environment
Published in Céline McKeown, Office Ergonomics and Human Factors, 2018
When the subject of lighting is discussed, a number of terms are commonly used and these include luminance, illuminance, luminous intensity, and luminous flux. Luminance refers to the light emitted, or bounced back, by a surface toward the eye. This is measured in cd/m2, cd being an abbreviation for candela. Illuminance relates to the amount of light falling on a surface, usually horizontal surfaces, and this is measured in lux. High levels of illuminance may cause glare and result in ‘washing out’ of items being viewed. Reflectance is an indicator of the ratio of luminance to illuminance. When an organisation specifies the level of illuminance required in an office, it should also specify the corresponding reflectance of surfaces in the office, as this is more likely to result in a balance of surface luminance. Luminous intensity, which is measured in candela, relates to the amount of light emitted from a source, and luminous flux indicates the flow rate of the luminous energy. The luminance distribution within the visual field should ensure that it is well-balanced, tasks can be completed unimpaired, glare is avoided, visual communication is heightened, and safety is uncompromised.
The Environment
Published in Céline McKeown, Office Ergonomics, 2007
When the subject of lighting is discussed, a number of terms are commonly used and these include luminance, illuminance, luminous intensity and luminous flux. Luminance refers to the light emitted or bounced back by a surface toward the eye. This is measured in cd/m2, cd being an abbreviation for candela. Illuminance relates to the amount of light falling on a surface, usually horizontal surfaces, and this is measured in lux. High levels of illuminance may cause glare and result in “washing out” of items being viewed. Reflectance is an indicator of the ratio of luminance to illuminance. When an organization specifies the level of illuminance required in an office, it should also specify the corresponding reflectances of surfaces in the office, as this is more likely to result in a balance of surface luminances. Luminous intensity, which is measured in candela, relates to the amount of light emitted from a source, and luminous flux indicates the flow rate of the luminous energy. The luminance distribution within the visual field should ensure that it is well balanced, tasks can be completed unimpaired, glare is avoided, visual communication is heightened and safety is uncompromised.
Study on Gasoline-Air Mixture Deflagration Flame with Different Equivalence Ratios in a Closed Vessel
Published in Combustion Science and Technology, 2018
Sheng Qi, Yang Du, Peili Zhang, Jianjun Liang, Shimao Wang, Yangchao Li
The discharge of luminous energy, which occurs due to the drastic redox reaction, is a remarkable feature of a flame. Therefore, the instantaneous flame illuminance might serve as a quantitative representation of the flame intensity. Experimental observations show that the recorded illuminance-time curves under different equivalence ratios exhibit similar behavior (as shown in Figure 6); after the mixture gas is ignited, the illuminance remains stable at its original value for a short period (particularly noticeable when = 1.64), then the illuminance increases sharply to a very high value, fluctuates before (or after) reaching its peak value, and then begins to decrease because of the end of combustion and the energy dissipation. For a wrinkled spherical flame ( = 0.97, 1.14), the flame illuminance fluctuates before reaching its peak value; this is mainly because the flame lights refract under the influence of the Richtmyer–Meshkov instability in the flame front. For curling flocculent flames ( = 1.40, 1.64), the flame illuminance fluctuates after reaching its peak value, which indicates the flame distortion shown in Figure 4.
A Review of Human Physiological Responses to Light: Implications for the Development of Integrative Lighting Solutions
Published in LEUKOS, 2022
Céline Vetter, P. Morgan Pattison, Kevin Houser, Michael Herf, Andrew J. K. Phillips, Kenneth P. Wright, Debra J. Skene, George C. Brainard, Diane B. Boivin, Gena Glickman
The approach to measuring and reporting light by Lucas and colleagues was echoed by the Commission Internationale de l’Éclairage (CIE) in a technical note (2015), which was revised and formalized via an internationally-balloted consensus within CIE S 026/E:2018 CIE System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light (CIE 2018). This international standard represents a significant step in providing guidance to the broader lighting and scientific communities as to how best to quantify light exposure. For clarification purposes, the 10 nm differential between the aforementioned 480 nm peak spectral sensitivity for melanopsin and the 490 nm peak described in the CIE technical note is contextual, as the former is a function of photon flux whereas the latter accounts for pre-receptoral filtering and stimulus energy. When incident flux density is most relevant, photic stimuli for nonvisual physiological responses should not be quantified using illuminance measures in photopic lux, but rather as melanopic equivalent daylight illuminance, abbreviated as melanopic EDI or , also in units of lux. The “photometric equivalent” concept can be applied to quantities other than illuminance, such as the luminous energy (lm-s), luminous intensity (cd or lm/sr) and luminance (cd/m2 or lm/sr-m2). Translating previously reported lux values into melanopic EDI (or another photometric equivalent illuminance) is often hampered by incomplete information about the spectral composition of the light sources employed, which limits replication and comparison across studies.
Numerical and experimental investigation of solar chimney power plant system performance
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Ali Serkan Avcı, Hakan Karakaya, Aydın Durmuş
RTE is integrated into each wavelength range as well as is concluded by bearing equations for the luminous energy amount in wavelength band. Accordingly, total density in each of the senses in and positions is calculated as follows: