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The Physics of Human Thermography
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
The term “emissivity” in thermal imaging refers to the ability of a surface to emit or absorb radiation within 9–10-μm infrared range. The range of emissivity runs from 1.0 (the ideal emitter/absorber) to 0.0 (the ideal reflector). In physics, a blackbody is an object that has an emissivity of 1.0. None of the incident radiation is reflected from or passes through a perfect blackbody. Thus, a blackbody completely absorbs all radiant energy reaching it, and simultaneously emits radiant energy. If not otherwise heated or cooled, it eventually attains a temperature equal to its environment and then maintains that energy balance.
Thermal Imaging for Arthritis Evaluation in a Small Animal Model
Published in U. Snekhalatha, K. Palani Thanaraj, Kurt Ammer, Artificial Intelligence-Based Infrared Thermal Image Processing and Its Applications, 2023
U. Snekhalatha, K. Palani Thanaraj, Kurt Ammer
The FLIR ONE camera used in their study had a temperature span of −20–120°C and can detect temperature changes as tiny as 0.1°C. A standardization check was carried out using boiling water, melting ice, and a person’s tear duct with known temperature to test the instrument’s performance before usage. To determine the device’s precision in the temperature span of 35–40°C, it was tested against a black reference material with established emissivity at different temperatures. The coefficient of determination (R2) was used to prove that the linear regression connecting the black body and IR temperature data explained the fluctuation. The temperature reading was taken three times and the mean SD was calculated. From a 20 cm distance, the camera was set horizontally parallel to the ground, focussing on hot water and melting ice. The distance and, as a result, the field of view (FOV) were retained persistent (approximately 20 cm) while focussing the attention toward the object and limiting the surroundings to picture the tear duct and black material.
Modeling and investigating the effect of parasol installation on solar radiant temperature reduction using COMSOL Multiphysics
Published in International Journal of Occupational Safety and Ergonomics, 2023
Farideh Golbabaei, Esmaeil Karami, Majid Shahi, Zahra Safari, Kaykāvus Azrah
The total diffuse outgoing radiative flux at any point is called radiosity (J). This radiosity is the sum of diffusively reflected and emitted radiation: ϵ = surface emissivity (unit: 1), a dimensionless number in the range 0 ≤ ϵ ≤ 1 (the diffuse-gray surface hypothesis corresponds to surfaces where ϵ is independent of the radiation wavelength); eb(T) = blackbody hemispherical total emissive power (W/m2), which according to the Stefan–Boltzmann law is the power radiated across all wavelengths and depends on the fourth power of the temperature; T = surface temperature (K); ρd =reflectivity fractions of body; G = incoming radiative heat flux, or irradiation (W/m2).
Hygro-thermo-mechanical performance of wheelchair cushion technologies in the prevention of pressure ulcers and moisture-associated skin damages
Published in Assistive Technology, 2023
Fabien Bogard, Guillaume Polidori, Sébastien Murer, Chadi Maalouf, Yannick Blancheteau, Hervé Quinart, Fabien Beaumont
In order to determine the role played by each type of cushion in heat evacuation, an experimental methodology has been developed. Regarding the acquisition of thermal mappings, emissivity variations were avoided and constant environmental reflection was ensured by capturing all infrared images perpendicularly to the seat. The “thermally thin” properties of the wheelchair seat material were initially assessed. This hypothesis consists in assuming that the thickness of the fabric is small enough to consider that the thermal field is identical on both faces of the seat. Once verified, all further infrared thermography images, whether with or without cushions, were captured on the top surface of the seat material after the participant had seated for 45 minutes. The cushion was then quickly removed, ensuring immediate image acquisition. This procedure is mandatory, due to the “thermally thin” characteristics of the seat material: the thermal field may evolve within seconds once the heat source (i.e., human body) is removed. Two states were therefore defined. The first state, called reference state, consists in positioning the subject directly on the seat fabric and calculating the heat flux
Infrared thermography as control of handheld IPL device for home-use
Published in Journal of Cosmetic and Laser Therapy, 2018
Hrvoje Glavaš, Marko Vukobratović, Tomislav Keser
Specific measurement spot where the skin temperature is close to the body core temperature is in the corner of the eyes where the lacrimal or tear duct comes to the surface (23). Infrared thermal camera does not measure temperature, in fact, it just records thermal radiation from surface. Software embedded in camera presents apparent temperature according to the input parameters and most important parameter in that process is emissivity. FLIR emissivity tables recommend value of 0.98 for skin. The emissivity of human skin, according to data from 1973, is constant value of 0.98 for very dark skin and 0.97 for light skin between wavelengths of 2 and 14 µm. For forehead skin emissivity of 0.98 should be used according to (24).