Investigation of the turbulent structure in a flame and the effect of small infrasonic exposure on it using IR thermography methods

Abstract This paper shows a specific approach based on infrared (IR) thermography to face the challenging aspects of thermal measurement, mapping, and failure analysis on AlGaN/GaN high electron-mobility transistors (HEMTs) and MMICs. In the first part of this paper, IR thermography is used for the temperature measurement. Results are compared with 3D thermal simulations (ANSYS) to validate the thermal model of an 8x125pm AIGaN/GaN HEMT on SiC substrate. Measurements at different baseplate temperature are also performed to highlight the non-linearity of the thermal properties of materials. Then, correlations between the junction temperature and the life time are also discussed. In the second part, IR thermography is used for hot spot detection. The interest of the system for defect localization on AIGaN/GaN HEMT technology is presented through two case studies: a high temperature operating life test and a temperature humidity bias test.

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Influence of Wall Strain Rate, Polymer Concentration and Channel Height upon Drag Reduction and Turbulent Structure

10.21236/ada215378 ◽

1989 ◽

Cited By ~ 2

Author(s):

Kenneth J. Harder ◽

William G. Tiederman

Keyword(s):

Drag Reduction ◽

Strain Rate ◽

Polymer Concentration ◽

Turbulent Structure ◽

Channel Height

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Subsurface imaging for panel paintings inspection: A comparative study of the ultraviolet, the visible, the infrared and the terahertz spectra

Opto-Electronics Review ◽

10.1515/oere-2015-0013 ◽

2015 ◽

Vol 23 (1) ◽

Cited By ~ 25

Author(s):

A. Bendada ◽

S. Sfarra ◽

C. Ibarra−Castanedo ◽

M. Akhloufi ◽

J.−P. Caumes ◽

...

Keyword(s):

Subsurface Imaging ◽

Wide Spread ◽

Ir Thermography ◽

Complementary Information ◽

Ir Sensors ◽

The World ◽

Panel Paintings ◽

Temperature Maps ◽

Illumination Source ◽

Ir Reflectography

AbstractInfrared (IR) reflectography has been used for many years for the detection of underdrawings on panel paintings. Advances in the fields of IR sensors and optics have impelled the wide spread use of IR reflectography by several recognized Art Museums and specialized laboratories around the World. The transparency or opacity of a painting is the result of a complex combination of the optical properties of the painting pigments and the underdrawing material, as well as the type of illumination source and the sensor characteristics. For this reason, recent researches have been directed towards the study of multispectral approaches that could provide simultaneous and complementary information of an artwork. The present work relies on non−simultaneous multispectral inspection using a set of detectors covering from the ultraviolet to the terahertz spectra. It is observed that underdrawings contrast increases with wavelength up to 1700 nm and, then, gradually decreases. In addition, it is shown that IR thermography, i.e., temperature maps or thermograms, could be used simultaneously as an alternative technique for the detection of underdrawings besides the detection of subsurface defects.

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Impact of solar radiation and environmental temperature on Art Nouveau glass windows

Heritage Science ◽

10.1186/s40494-019-0325-3 ◽

2019 ◽

Vol 7 (1) ◽

Cited By ~ 8

Author(s):

Teresa Palomar ◽

Miguel Silva ◽

Marcia Vilarigues ◽

Isabel Pombo Cardoso ◽

David Giovannacci

Keyword(s):

Chemical Composition ◽

Solar Radiation ◽

Surface Temperature ◽

Environmental Temperature ◽

Summer Solstice ◽

Art Nouveau ◽

Ir Thermography ◽

Hot Air ◽

Near Ir ◽

Air Pocket

Abstract This work presents the results of the evaluation of two Art Nouveau glass windows from the Casa-Museu Dr. Anastácio Gonçalves (Lisbon, Portugal) with IR-thermography during the summer solstice. According to the measurements, the surface temperature of glass depended on the outdoor environmental temperature and, mainly, on the direct solar radiation. Colored glasses presented a higher surface temperature due to the absorption of their chromophores at near-IR wavelengths. Enamels and grisailles showed higher surface temperatures than their support glasses due to both their chemical composition and color. The protective glazing, with small slits in one of the window panels, induced a hot-air pocket in its upper part due to the insufficient ventilation.

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