Identification of Thermal Response of Mesoscopic Liquids under Mechanical Excitation: From Harmonic to Nonharmonic Thermal Wave

2021 ◽  
Author(s):  
Eni Kume ◽  
Laurence Noirez
Keyword(s):  
Thermal Wave ◽  
Thermal Response ◽  
Mechanical Excitation

On the influence of thin absorber layers in thermal-wave applications

1986 ◽  
Vol 64 (9) ◽  
pp. 1287-1290 ◽  
Author(s):  
R. Tilgner ◽  
J. Baumann ◽  
M. Beyfuss
Keyword(s):  
Thermal Diffusion ◽  
Thermal Wave ◽  
Thermal Response ◽  
Absorber Layer ◽  
Thermal Waves ◽  
Wave Approach ◽  
Quantitative Results ◽  
Complex Temperature

The influence on the thermal response of a sample under photothermal investigation is analyzed when real absorbing layers are used as a source of thermal waves. Experiments with glass and copper samples covered by various absorbing layers are described using a thermal-wave approach. It is demonstrated that matching the effusivities of absorber and substrate is essential for obtaining quantitative results even for absorber layers much thinner than their thermal-diffusion lengths; otherwise one has to determine very carefully the particular nonneglectable influence of the absorber layer on the measured complex temperature.

scholarly journals Vibro-Thermal Wave Radar: Application of Barker Coded Amplitude Modulation for Enhanced Low-Power Vibrothermographic Inspection of Composites

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2436
Author(s):  
Saeid Hedayatrasa ◽  
Joost Segers ◽  
Gaétan Poelman ◽  
Wim Van Paepegem ◽  
Mathias Kersemans
Keyword(s):  
Low Power ◽  
Amplitude Modulation ◽  
Thermal Wave ◽  
Pulse Compression ◽  
Impact Damage ◽  
Vibrational Excitation ◽  
Thermal Response ◽  
Input Power ◽  
Local Defect ◽  
Wave Radar

This paper proposes an efficient non-destructive testing technique for composite materials. The proposed vibro-thermal wave radar (VTWR) technique couples the thermal wave radar imaging approach to low-power vibrothermography. The VTWR is implemented by means of a binary phase modulation of the vibrational excitation, using a 5 bit Barker coded waveform, followed by matched filtering of the thermal response. A 1D analytical formulation framework demonstrates the high depth resolvability and increased sensitivity of the VTWR. The obtained results reveal that the proposed VTWR technique outperforms the widely used classical lock-in vibrothermography. Furthermore, the VTWR technique is experimentally demonstrated on a 5.5 mm thick carbon fiber reinforced polymer coupon with barely visible impact damage. A local defect resonance frequency of a backside delamination is selected as the vibrational carrier frequency. This allows for implementing VTWR in the low-power regime (input power < 1 W). It is experimentally shown that the Barker coded amplitude modulation and the resultant pulse compression efficiency lead to an increased probing depth, and can fully resolve the deep backside delamination.

Thermal wave imaging of microelectronics

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Miguel Goni ◽  
Aaron J. Schmidt
Keyword(s):  
Thermal Properties ◽  
Surface Temperature ◽  
Thermal Wave ◽  
High Frequency ◽  
Low Frequency ◽  
Thermal Response ◽  
Glass Layer ◽  
Thermal Waves ◽  
Frequency Wave ◽  
Thermal Penetration Depth

Thermal waves can reveal thermal properties of different layers forming a multilayer structure. If the thickness of each layer is known, specific ranges of thermal wave frequencies can be implemented to study the thermal response of a specific number of layers and eventually extract the thermal properties of individual layers. As a first approach this idea can be simplified by means of the thermal penetration depth parameter, δ. The thermal penetration depth is defined as, δ=k/πCf, where k and C are respectively the thermal conductivity and volumetric heat capacity of the material carrying the thermal wave and f is the frequency of the thermal wave. From this expression it can be seen how it is possible to constrain the material thermal response to a desired depth by controlling the frequency. Thus, using high enough frequencies, the top layer properties would be measured first. Decreasing the thermal wave frequency by an appropriate amount would include the next layer in the thermal response. Since the properties of the first layer are now known, it would be possible to extract the properties of the current layer. The measurement would continue in a similar fashion for the remaining layers. Frequency domain thermoreflectance (FDTR) can be used to generate thermal waves. In this technique, a periodically modulated continuous wave laser (red pump beam) provides the periodic heat flux input into the material while a second laser (green probe beam) monitors the surface temperature through a proportional change of the surface reflectivity. The measured value is the phase lag (degrees) between the incoming thermal wave and the surface temperature response. In this study, an FDTR system was used in conjunction with a piezo stage to obtain thermal images of two different multilayer structures. The first one consisted of a CPU chip formed mainly by layers of SiO2 and Cu. The second case consisted of a TFT LCD screen from a mobile device. Regarding the CPU chip, the low frequency thermal wave travelled well past the second layer of Cu wires and provided thermal information about the bottom layers of the chip. In contrast, the high frequency wave could not penetrate through the second layer, which resulted in a more sensitive response upon the Cu wires close to the surface. A similar phenomenon occurred with the LCD screen. In this case the top layer was a glass layer used to sandwich the liquid crystal and the second layer is composed of the ITO electrodes that provide the electric field. It can be observed how the high frequency wave did not penetrate through the top glass layer providing no thermal information about the bottom layer as opposed to the low frequency wave, which clearly shows the ITO electrodes. The estimated thermal penetration depths displayed on top of each image were calculated using the equation provided before with known thermal properties of SiO2, Cu and ITO.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

THERMAL WAVE IMAGING OF CRACKS IN METALS

1983 ◽  
Vol 44 (C6) ◽  
pp. C6-519-C6-524
Author(s):  
K. R. Grice ◽  
L. J. Inglehart ◽  
L. D. Favro ◽  
P. K. Kuo ◽  
R. L. Thomas
Keyword(s):  
Thermal Wave ◽  
Wave Imaging ◽  
Thermal Wave Imaging

Numerical simulation of the tree higro-thermal response in forest fire environment

2020 ◽  
pp. 57-65
Author(s):  
Eusébio Conceiçã ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Jorge Raposo ◽  
Domingos Xavier Viegas ◽  
...  
Keyword(s):  
Forest Fire ◽  
Numerical Study ◽  
Thermal Response ◽  
View Factor ◽  
Tree Model ◽  
Pine Tree ◽  
Surface Temperatures ◽  
Fire Environment ◽  
Fire Front ◽  
Heat Exchanges

This paper refers to a numerical study of the hypo-thermal behaviour of a pine tree in a forest fire environment. The pine tree thermal response numerical model is based on energy balance integral equations for the tree elements and mass balance integral equation for the water in the tree. The simulation performed considers the heat conduction through the tree elements, heat exchanges by convection between the external tree surfaces and the environment, heat exchanges by radiation between the flame and the external tree surfaces and water heat loss by evaporation from the tree to the environment. The virtual three-dimensional tree model has a height of 7.5 m and is constituted by 8863 cylindrical elements representative of its trunks, branches and leaves. The fire front has 10 m long and a 2 m high. The study was conducted taking into account that the pine tree is located 5, 10 or 15 m from the fire front. For these three analyzed distances, the numerical results obtained regarding to the distribution of the view factors, mean radiant temperature and surface temperatures of the pine tree are presented. As main conclusion, it can be stated that the values of the view factor, MRT and surface temperatures of the pine tree decrease with increasing distance from the pine tree in front of fire.

A New Scanning Thermal Microprobe

1997 ◽  
Vol 503 ◽  
Author(s):  
Yongxia Zhang ◽  
Yanwei Zhang ◽  
Juliana Blaser ◽  
T. S. Sriiram ◽  
R. B. Marcus
Keyword(s):  
Thin Film ◽  
High Resolution ◽  
Thermal Response ◽  
Temperature Sensing ◽  
Thermal Sensor ◽  
Atomic Force ◽  
Thin Film Thermocouple ◽  
Processing Steps ◽  
Thermocouple Junction

ABSTRACTA thermal microprobe has been designed and built for high resolution temperature sensing. The thermal sensor is a thin-film thermocouple junction at the tip of an Atomic Force Microprobe (AFM) silicon probe needle. Only wafer-stage processing steps are used for the fabrication. The thermal response over the range 25–s 4.5–rovolts per degree C and is linear.

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