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Flow visualization methods and their application in electronic systems
Published in Kaveh Azar, in Electronic Cooling, 2020
The main advantages of a thermography system are the noninvasive nature of the measurement and the continuous nature of the spatial and temporal temperature mapping. A host of computer-assisted post-processing routines have been used in conjunction with the thermographs obtained. The primary disadvantage is the requirement that the surface emissivity be known; however, this mainly affects the absolute value of the temperatures measured rather than the redative differences in temperatures on the surface. Also, while temperatures at free surfaces of liquids may be monitored using this technique, objects submerged in a liquid (as in water-channel tests) are not accessible to mapping by IR thermography. In wind tunnels or in test sections made of acrylic or polycarbonate (which interfere with IR transmission), a cell window made of sodium chloride or potassium bromide should be provided for visualization. These materials are transparent to near- and mid-infrared radiation, which is the range of interest in electronics-cooling applications.
The effect of vehicle dynamics on rail foot flaw detection
Published in Maksym Spiryagin, Timothy Gordon, Colin Cole, Tim McSweeney, The Dynamics of Vehicles on Roads and Tracks, 2018
Chris Bosomworth, Maksym Spiryagin, Sanath Alahakoon, Colin Cole
A common technique in flaw detection for Non Destructive Testing (NDT) is thermography. Thermography is the process of analysing an infrared response from an object and detecting unexpected temperature differentials that may be indicative of a fault. It has been selected as a potential methodology for further research into rail foot flaw detection. However, to use thermography as a detection technique, one must first understand the expected temperature differentials detectable in the rail foot. As the train is a key source of energy excitation in the rail, it is important to understand the role that Vehicle System Dynamics (VSD) plays and its impact on temperatures experienced in the rail foot.
Cleaning, Grading, and Sorting
Published in B. K. Bala, Agro-Product Processing Technology, 2020
When ultrasound and a computer vision system fail to produce the desired image, much larger wavelengths are used for image acquisition. Infrared range (IR) lies from “700 to 1000 nm,” and the approach of generating infrared range is known as thermographic photography. Thermographic imaging is based on the principle that all objects emit a certain amount of thermal radiation as a function of their temperature.
Estimate residual strength of degraded bonded joints by combining analytical models with non-destructive evaluations
Published in The Journal of Adhesion, 2023
Guilherme Garcia Momm, David Fleming
Thermography typically analyzes spatial and temporal changes of surface temperature distributions (thermal patterns) using infrared images (thermograms).[30,41] Pulsed thermography involves actively heating a specimen surface using a powerful pulse of light while collecting numerous images of this surface as it cools down.[30] Despite its simple deployment, pulsed thermography raw signals are commonly polluted with noise and other degradations (e.g., 3D effects, reflections), prompting the need for data processing.[30,41,42] There are several processing techniques available.[30,41] Among them is the Thermographic Signal Reconstruction (TSR) – proposed (and patented) by Shepard et al.[42] – which fits logarithm derivatives with polynomials. Besides reducing noises, TSR also eases mathematical operations (e.g., differentiation, integration) to reconstruct the temporal signal profiles.[30] TSR assumes that the temperature profile at sound regions follows the unidimensional solution (Equation 9)) of the Fourier law of heat diffusion in a semi-infinite, homogeneous, isotropic solid subjected to a Dirac-pulse heat wave[30,42]
Advanced Framework for Effective Denoising the Enhanced Thermal Breast Image
Published in IETE Journal of Research, 2023
A. Arul Edwin Raj, M. Sundaram, T. Jaya
Breast thermography, or breast thermal imaging, is a noninvasive and painless test. The physicians may refer the thermal breast images for early detection of malignancy. It works by identifying increases in temperature of the breast. Thermography does not involve any harmful radiation during image acquisition. Because of using a high-resolution thermal camera to map heat changes of the breast into images, the quality of thermogram is ensured more in the field of medical imaging. This thermal image has to be analyzed to identify breast abnormality by the temperature variation of the breast, it helps in early detection of breast cancer. When a tumor cell develops in an area, the human body will increase the blood flow of the area to rejuvenate the part which makes this area to become warmer. A tumor can be easily identified from the hot spot of the thermogram. The early detection of breast tumor increases the survival probability of the patient.
Thermographic quantitative variables for diabetic foot assessment: preliminary results
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2019
Lucía Carbonell, Jose Ignacio Priego Quesada, Pedro Retorta, María Benimeli, Rosa Mª Cibrián Ortiz De Anda, Rosario Salvador Palmer, Rolando J. González Peña, Carlos Galindo, Laura Pino Almero, Mª Carmen Blasco, M. Fe Mínguez, Cecili Macián-Romero
Skin temperature was measured using an infrared thermography camera with the size of focal plane sensor array being 320 x 240, NETD of 50 mK at 30°C, repeatability of the measurement of ±2% of the overall reading, and a spectral range of 7.5–13 µm (FLIR E-60, Flir Systems Inc., Wilsonville, OR, USA). Infrared thermography is a non-ionising image technique which measures surface temperatures by infrared radiation emitted by the assessed body. This calculation is based on the Stefan-Boltzmann law (Equation 1), which shows the relationship between emitted infrared radiation (Eemitted in Watt/m2) and temperature T in Kelvin. Radiation captured by the camera (Ereceived) is both that emitted from the body and that reflected by the body from the environment (Equation 2). The surrounding ambient temperature is called Treflected (Priego Quesada et al. 2017).