Effect of perspiration on skin temperature measurements by infrared thermography and contact thermometry during aerobic cycling

The aim of the present study was to compare infrared thermography and thermal contact sensors for measuring skin temperature during cycling in a moderate environment. Fourteen cyclists performed a 45-min cycling test at 50% of peak power output. Skin temperatures were simultaneously recorded by infrared thermography and thermal contact sensors before and immediately after cycling activity as well as after 10 min cooling-down, representing different skin wetness and blood perfusion states. Additionally, surface temperature during well controlled dry and wet heat exchange (avoiding thermoregulatory responses) using a hot plate system was assessed by infrared thermography and thermal contact sensors. In human trials, the inter-method correlation coefficient was high when measured before cycling (r = 0.92) whereas it was reduced immediately after the cycling (r = 0.82) and after the cooling-down phase (r = 0.59). Immediately after cycling, infrared thermography provided lower temperature values than thermal contact sensors whereas it presented higher temperatures after the cooling-down phase. Comparable results as in human trials were observed for hot plate tests in dry and wet states. Results support the application of infrared thermography for measuring skin temperature in exercise scenarios where perspiration does not form a water film.     

Improvement of building wall surface temperature measurements by infrared thermography

By using quantitative thermal scanning of building surface structures, it is possible to access the temperature field. For further calculation of the heat flux exchanged by these structures with the environment, one must quantify as finely as possible the temperature field on the bodies surfaces. For this purpose we have to take into account that real bodies are not black, which implies that a part of the ambient radiation received by the infrared camera detectors is reflected radiation. In this paper, we present a method to quantify the reflected flux by using an infrared mirror, which allows large surface temperature measurements by infrared thermography under near-ambient conditions with improved accuracy. In order to validate the method, an experimental study was carried out on a multi-layer wall, which simulated an insulation default. A good agreement was noticed between the thermocouple temperatures and the infrared corrected ones. Then, the method is applied to outdoor measurements.     

Thermal diffusivity of electrodeposited Ni and Co nanowires using infrared thermography

One-dimensional nanostructures such as Ni and Co nanowires (NWs) show anisotropic thermal properties in a direction parallel and perpendicular to the NW axis. Thermal diffusivity of Ni and Co NWs embedded in a 100-nm pore anodic alumina (AAO) template has been measured in a direction perpendicular to the NW axis, using an infrared thermography-based non-contact approach. The measured thermal diffusivity values in the radial direction are 0.728×10⁻⁶ and 0.732×10⁻⁶ m²s⁻¹, respectively, for the Ni and Co nanocomposites. The changes in the thermal diffusivity of the synthesized NWs alone were estimated using a first-order lower bound model (FOLBM). A nearly seven- and sixfold reduction, respectively, of thermal diffusivity in a direction perpendicular to the NW axis is estimated for the synthesized Ni and Co NWs.     

Measurement of annular air-gap using active infrared thermography

The paper discusses an infrared thermography (IRT) based procedure for quantification of annular air-gap in cylindrical geometries. Different annular air-gaps are simulated using aluminum hollow cylinders and solid stainless steel inserts of varying diameters. The specimens are externally heated using a hot air-gun and the temperature of the specimens are monitored during cooling using an infrared camera. The temperature decay during the cooling cycle follows an exponential profile in all the cases where the decay constant is air-gap dependent. The rate of temperature decay is fastest for the empty cases (without inserts) and lower for smaller air-gaps. The system is analyzed using a lumped system model by measuring the temperature over a time scale significantly higher than the transition time of the lumped system. It is observed that the Biot number of the system is less than unity, allowing analysis of the system in terms of a single time constant, neglecting internal temperature transients. It is observed that the time constant of temperature decay increases with decreasing annular air-gap. An empirical relation between the inverse of time constant of temperature decay and annular air-gaps is established. Using this calibration curve, unknown air-gaps up to 20 μm could be measured with good accuracy. Applications of this newly developed technique include detection of misalignment of concentric machineries and determination of fuel-to-clad gap of nuclear reactor fuels.     

Measurement of thermal parameters of a heat insulating material using infrared thermography

The article presents results of research developing methods for determining thermal parameters of a thermal insulating material. This method applies periodic heating as an excitation and an infrared camera is used to measure the temperature distribution on the surface of the tested material. The usefulness of known analytical solution of the inverse problem was examined in simulation study, using a three-dimensional model of the heat diffusion phenomenon in the sample of the material under test. To solve the coefficient inverse problem an approach using an artificial neural network is proposed. The measurements were performed on an experimental setup equipped with a ThermaCAM PM 595 infrared camera and a frame grabber. The experiment allowed verification of the chosen 3-D model of the heat diffusion phenomenon and proved suitability of the proposed test method.     

红外热像法研究屋顶绿化对热环境的影响

该研究应用红外热像法测量绿化屋顶的表面温度,进而分析屋顶绿化对热环境的影响。通过采集斜坡屋顶绿化、轻型屋顶绿化和蓄水覆土屋顶绿化在阴天、雨后一天、晴天三种天气条件下的红外热像图,分析对比三种绿化屋顶在同一天内及三种不同天气条件下的温度变化。结果表明绿化屋顶表面温度的变化主要受太阳辐射和气温的影响,而蓄水覆土绿化屋顶的表面温度还受到其含水量的影响;屋顶绿化在夏季天气条件下可有效降低屋顶的表面温度、减小温度波动幅度,有利于改善城市热环境。     

Surface temperature measurement of the plasma facing components with the multi-spectral infrared thermography diagnostics in tokamaks

For the long-pulse high-confinement discharges in tokamaks, the equilibrium of plasma requires a contact with the first wall materials. The heat flux resulting from this interaction is of the order of 10 MW/m² for steady state conditions and up to 20 MW/m² for transient phases. The monitoring on surface temperatures of the plasma facing components (PFCs) is a major concern to ensure safe operation and to optimize performances of experimental operations on large fusion facilities. Furthermore, this measurement is also required to study the physics associated to the plasma material interactions and the heat flux deposition process. In tokamaks, infrared (IR) thermography systems are routinely used to monitor the surface temperature of the PFCs. This measurement requires an accurate knowledge of the surface emissivity. However, and particularly for metallic materials such as tungsten, this emissivity value can vary over a wide range with both the surface condition and the temperature itself, which makes instantaneous measurement challenging. In this context, the multi-spectral infrared method appears as a very promising alternative solution. Indeed, the system has the advantage to carry out a non-intrusive measurement on thermal radiation while evaluating surface temperature without requiring a mandatory surface emissivity measurement.In this paper, a conceptual design for the multi-spectral infrared thermography is proposed. The numerical study of the multi-channel system based on the Levenberg-Marquardt (LM) nonlinear curve fitting is applied. The numerical results presented in this paper demonstrate the design allows for measurements over a large temperature range with a relative error of less than 10%. Furthermore, laboratory experiments have been performed from 200 °C to 740 °C to confirm the feasibility for temperature measurements on stainless steel and tungsten. In these experiments, the unfolding results from the multi-channel detection provide good performance on temperature measurement, which supports our numerical evaluation and demonstrates the potential feasibility for metallic surface high temperature measurement with this method.     

Simultaneous assessment of Lagrangian strain and temperature fields by improved IR-DIC strategy

This paper focuses on the development of a novel digital image correlation strategy based on infrared imaging (IR-DIC) for realizing simultaneous assessment of Lagrangian strain and temperature fields. A major difficulty in the IR-DIC is the evolution of the thermal field during deformation that is unexpected in the image correlation. Two solutions are proposed to tackle this difficulty. The first solution is to utilize a high-pass filter to eliminate the variation part of the thermal signal, and the second solution is to employ an advanced metric, the mutual information, as the correlation criterion. Both methods are verified through a tensile test performed on a notched specimen. The estimated displacement and strain fields demonstrate well the desirable performance of the proposed methods. Thanks to the kinematic field assessment, the obtained thermal fields can be described in the Lagrangian coordinate system, thus the temperature evolution of the material points during deformation can be followed effectively.     

On the proposal of quantitative temperature measurement by using three-color technique combined with several infrared sensors having different detection wavelength bands

We developed the previous infrared sensing technique, the two-color technique, to establish further a more general technique to measure the temperature quantitatively under near-ambient conditions. The quantitative temperature measurement, three-color technique, was newly proposed by combining three kinds of infrared radiometers having different detection wavelength bands. The measurement can also be done by adding three infrared filters to one infrared radiometer. The radiometers have a selective detection wavelength band of several μm in width which is in the range of 2–13 μm. The method was confirmed using numerical simulation to allow a parametric study of how the result varies for different values of emissivity corresponding to the respective infrared radiometers. An experimental investigation was also performed to evaluate the measurement error and the adaptability of the technique. As this technique has a feature that can perform quantitative temperature measurement for objective surfaces at each picture element without presuming any emissivity, reflectivity and ambient conditions, there is a possibility that the technique will be useful for various medical or engineering disciplines.     

Simultaneous microscopic measurements of thermal and spectroscopic fields of a phase change material

In this paper, simultaneous microscopic measurements of thermal and spectroscopic fields of a paraffin wax n-alkane phase change material are reported. Measurements collected using an original set-up are presented and discussed with emphasis on the ability to perform simultaneous characterization of the system when the proposed imaging process is used. Finally, this work reveals that the infrared wavelength contains two sets of important information. Furthermore, this versatile and flexible technique is well adapted to characterize many systems in which the mass and heat transfers effects are coupled.     

Thermal imaging during infrared final cooking of semi-processed cylindrical meat product

The temperature measurements during the infrared cooking of the semi-cooked cylindrical minced beef product (koefte) were taken by both contact (thermocouples) and non-contact (thermal imaging) techniques. The meat product was semi-cooked till its core temperature reached up to 75 °C by ohmic heating applied at 15.26 V/cm voltage gradient. Then, infrared cooking was applied as a final cooking method at different combinations of heat fluxes (3.7, 5.7 and 8.5 kW/m²), applied distances (10.5, 13.5 and 16.5 cm) and applied durations (4, 8 and 12 min). The average surface temperature increased as the heat flux and the applied duration increased but the applied distance decreased. The temperature distribution of the surface during infrared cooking was determined successfully by non-contact measurements. The temperature homogeneity varied between 0.77 and 0.86. The process condition of 8.5 kW/m² for 8 min resulted in core temperature greater than 75 °C, which was essential for safe production of ready-to-eat (RTE) meat products. Thermal imaging was much more convenient method for minimizing the point measurement mistakes and determining temperature distribution images more clear and visual.     

The use of thermal imaging to monitoring skin temperature during cryotherapy: A systematic review

Cryotherapy has been applied on clinical injuries and as a method for exercise recovery. It is aimed to reduce edema, nervous conduction velocity, and tissue metabolism, as well as to accelerate the recovery process of the muscle injury induced by exercise. Objective: This review aim to investigate the applicability of thermal imaging as a method for monitoring skin temperature during cryotherapy. Method: Search the Web of Science database using the terms “Cryotherapy”, “Thermography”, “Thermal Image” and “Cooling”. Results: Nineteen studies met the inclusion criteria and pass the PEDro scale quality evaluation. Evidence support the use of thermal imaging as a method for monitoring the skin temperature during cryotherapy, and it is superior to other contact methods and subjective methods of assessing skin temperature. Conclusion: Thermography seems to be an efficient, trustworthy and secure method in order to monitoring skin temperature during cryotherapy application. Evidence supports the use of thermography in detriment of contact methods as well as other subjective ones.     

基于多信号温度模型的机载电子板卡故障检测研究

在利用红外热像仪进行机载电子板卡故障检测中,针对电子板卡结构复杂,解析建模困难的特点,提出了一种基于多信号温度模型的分析诊断方法。通过将机载电子板卡正常工作时的红外温度图像与故障时的进行对比,建立了系统的多信号温度模型,针对多信号温度模型的缺点,提出一种基于贝叶斯网络的测试性建模方法,并给出贝叶斯网络模型的测试性分析方法与指标计算方法,得到模型相关矩阵并进一步进行故障诊断分析,为检测电子元器件故障及老化程度提供了一种有效途径。     

滴状冷凝过程液滴自由表面温度场分析

对于滴状冷凝过程及其传热强化机理, 一般通过分析冷凝壁面上液滴分布和运动规律进行研究, 并且将单个液滴视为稳定的个体, 很少涉及液滴内部运动特征. 本文通过红外热像仪观测了纯蒸气滴状冷凝过程中, 液滴运动时自由表面温度场的演化过程. 发现在疏水壁面上, 液滴由于合并或脱落而发生移动过程中, 其自由表面温度先降低, 而后升高并高于移动前温度. 通过分析疏水表面上液滴移动过程的物理模型, 认为液滴移动时表面液膜发生履带式滚动现象, 或者发生液滴内部与自由表面附近的液体间形成对流和掺混现象. 对液滴运动时表面温度演变规律的分析表明: 触发液滴表面发生持续冷凝可能需要克服一个临界过冷度, 当气液间温差超过该临界值时才诱发冷凝; 液滴合并或脱落等整体运动过程, 导致了液滴内部的运动特征, 并促进了较大尺寸液滴表面发生直接冷凝, 这为强化冷凝传热的研究提供新的思路.     

Automatic metal parts inspection: Use of thermographic images and anomaly detection algorithms

A fully-automatic approach based on the use of induction thermography and detection algorithms is proposed to inspect industrial metallic parts containing different surface and sub-surface anomalies such as open cracks, open and closed notches with different sizes and depths. A practical experimental setup is developed, where lock-in and pulsed thermography (LT and PT, respectively) techniques are used to establish a dataset of thermal images for three different mockups. Data cubes are constructed by stacking up the temporal sequence of thermogram images. After the reduction of the data space dimension by means of denoising and dimensionality reduction methods; anomaly detection algorithms are applied on the reduced data cubes. The dimensions of the reduced data spaces are automatically calculated with arbitrary criterion. The results show that, when reduced data cubes are used, the anomaly detection algorithms originally developed for hyperspectral data, the well-known Reed and Xiaoli Yu detector (RX) and the regularized adaptive RX (RARX), give good detection performances for both surface and sub-surface defects in a non-supervised way.     

Correlation between skin temperature and heart rate during exercise and recovery,and the influence of body position in these variables in untrained women

It was known that the thermal response varies according to some variables. Until now, there are no studies that have investigated the relationship of skin temperature and heart rate during and after the workout, either the thermal behavior during postural changes. Objective: the aim of this study was to evaluate the behavior of skin temperature and heart rate, during exercise and up to an hour of recovery (with postural change), performed in two different intensities sessions (70% and 85% of 10 repetitions maximum) and observe the correlation between them. Method: This was a short longitudinal study, carried out with women aged from 18 to 30 years. A sample of 31 untrained women, aged 18 and 30 was used. The volunteers were randomized into two groups: Biceps Group (BG), with 15 women, and Quadriceps Group (QG) with 16 women. Results: During and after completion of the exercise session, there was a significant reduction in skin temperature on the active muscles in both groups (BG and QG), with similar thermal responses for the two intensities studied (70% and 85%) to the minute 15 (which marks the end of the recovery in the standing position). From minute 15 to minute 20–60, the skin temperature increases abruptly and significantly, returning to levels close to those observed before exercise. Conclusion: There were no statistical differences in thermal response to exercises in 70% or 85% of 10RM. There is a negative correlation between heart rate and skin temperature when untrained women perform anaerobic exercise. It was observed that after a change of posture (from a standing position to a sitting posture) skin temperature increased abruptly and significantly.     

Analysis of the configuration and the location of thermographic equipment for the inspection in photovoltaic systems

The infrared (IR) thermography is a non-destructive technique (NDT) which is used to carry out maintenance quickly and easily in photovoltaic (PV) systems. IR imaging with thermographic cameras under steady state conditions is a usual method for quality control of PV modules and plants in operation. For the proper IR inspection which determines the severity or the importance of the detected findings, it is necessary to consider different aspects of the configuration and the location of the thermographic equipment which allow reducing measuring errors. This paper considers some elements which contribute to the accurate configuration of the thermographic equipment. The influence of the reflected apparent temperature in outdoor IR inspections is analysed and it is proposed a simple method for obtaining it. Besides, the importance of the emissivity in IR thermography is analysed. For that, the value of the emissivity in PV modules of various types both front and rear shape is determined experimentally. It is also studied the proper location of the thermographic equipment in order to minimize reflections of the sun and the sky. For this objective, it is studied the ideal and minimum height of inspection according to the layout of the PV system. In a particular case, it is also analysed the influence of the horizontal angle of thermographic inspection and the reflected radiation.     

Infrared intensity analysis of CH2Cl2 and CD2Cl2 in vapour and liquid states

In the infrared spectra of molecules with more than one C-H bond the symmetric and antisymmetric stretching bonds often overlap, causing uncertainty in the intensity analysis. For CH₂Cl₂ and CD₂Cl₂ in the vapour state, the two bands overlap to such an extent that Straley who takes it as one band attributes it to antisymmetric stretching while Saekiet al assign it to the symmetric stretching. Following the method of analysis initiated in this laboratory, we have solved this problem by ultimately obtaining intensities separately forA ₁ andB ₂ species. The band is mostly due to the symmetric stretching, 0.06 out of the total of 0.31 contributing toB ₂. Thus, this gives a method of separating the intensities of bands which are highly overlapping. Presented at the Symposium on Crystallography and Crystal Physics, Osmania University, Hyderabad held on 5–7, December 1977.