Showing papers on "Thermography published in 2007"
TL;DR: In this paper, the authors evaluated the comfort of some interior floor coatings by comparing thermal images obtained from the sole of a barefoot after having been in contact with different materials, and the results of these experiments are presented in this paper.
219 citations
TL;DR: A review of previous applications of infrared thermography in studies of thermal physiology, veterinary diagnosis of disease or injury and population surveys on domestic and wild mammals can be found in this paper.
Abstract: Infrared thermography (IRT) involves the precise measurement of infrared radiation which allows surface temperature to be determined according to simple physical laws. This review describes previous applications of IRT in studies of thermal physiology, veterinary diagnosis of disease or injury and population surveys on domestic and wild mammals. 2. IRT is a useful technique because it is non-invasive and measurements can be made at distances of 1000 m to count large mammals. Detailed measurements of surface temperature variation can be made where large numbers of temperature sensors would otherwise be required and where conventional solid sensors can give false readings on mammal coats. Studies need to take into account sources of error due to variation in emissivity, evaporative cooling and radiative heating of the coat. 3. Recent advances in thermal imaging technology have produced lightweight, portable systems that store digital images with high temperature and spatial resolution. For these reasons,therearemanyfurtheropportunitiesforIRTinstudiesofcaptiveandwildmammals.
212 citations
TL;DR: In this article, a novel non-invasive imaging technique to image the vein patterns in various parts of the hand for biometric purposes is evaluated, and the results show all the subjects were correctly identified, which indicates vein pattern biometrics with infrared imaging is a potentially useful biometric.
Abstract: A novel non-invasive imaging technique to image the vein patterns in various parts of the hand for biometric purposes is evaluated. Two imaging methods are investigated: far-infrared (FIR) thermography and near-infrared (NIR) imaging. Experiments involving data acquisition from various parts of the hand, including the back of the hand, palm and wrist, were carried out using both imaging techniques. Analysis of the data collected shows that FIR thermography is less successful at capturing veins in the palm and wrist. FIR thermography can capture the large veins in the back of the hand, but it is sensitive to ambient temperature and humidity conditions as well as human body temperature. NIR imaging produces good quality images when capturing veins in the back of the hand, palm and wrist. NIR imaging is also more tolerant to changes in the environment and body condition but faces the problem of pattern corruption because of visible skin features being mistaken for veins. This corruption is not present in FIR imaging. An initial biometric system is investigated to test both FIR and NIR images for biometric purposes. The results show all the subjects were correctly identified, which indicates vein pattern biometrics with infrared imaging is a potentially useful biometric.
186 citations
99 citations
TL;DR: In this article, Monte Carlo FIR simulations combined with convection-diffusion air flow and heat transfer simulations were performed in the CFD code ANSYS CFX5.7 to investigate the suitability of the method for surface decontamination.
84 citations
TL;DR: In this article, the authors used both cw and pulsed laser beam illumination on stainless steel and titanium samples and the technique was found to be successful for determining the location of fatigue cracks, where a surface crack, close to a small, well defined heated spot, impedes lateral heat flow and produces alterations in the shape of the thermal spot image that can be monitored by thermography.
Abstract: A surface crack, close to a small, well-defined heated spot, impedes lateral heat flow and produces alterations in the shape of the thermal spot image that can be monitored by thermography. Spot heating has been achieved using both cw and pulsed laser beam illumination on stainless steel and titanium samples and the technique has been found to be successful for determining the location of fatigue cracks. When using a pulsed laser beam one can also simultaneously generate wideband ultrasonic signals in the sample; this can be used to detect the presence of surface and sub-surface defects in the sample. Results are presented that have been obtained using a fixed camera and cw laser beam position with the sample being moved through the field of view of the camera. Results are also presented using a fixed camera and sample, with a raster scanned cw or pulsed lasers beam moving across the sample. A demonstration of how a non-contact ultrasonic measurement can be performed simultaneously is presented. Thermal i...
83 citations
TL;DR: Eddy current thermography is a new NDT-technique for the detection of cracks in electroconductive materials as discussed by the authors, which combines the well established inspection techniques eddy current testing and thermography.
Abstract: Eddy current thermography is a new NDT-technique for the detection of cracks in electroconductive materials It combines the well established inspection techniques eddy current testing and thermography The advantage of this method is to use the high performance of eddy current testing without the known problem of the edge effect Especially for components of complex geometry this is an important factor which may overcome the increased expense for inspection set-up The principle of this technique and an algorithm to increase the sensitivity for small defects are described Some inspection examples on aero engines parts are presented which show the potential of eddy current thermography
80 citations
TL;DR: In this article, a Focal Plane Array infrared camera was used for non-destructive evaluation of masonry structures with defects of different geometry and nature and located at different depths, and the defects detection was analyzed through a cause/effect relationship between the characteristics of defects and hosting material and the observed defect thermal signature on the hosting material.
76 citations
TL;DR: In this article, a genetic algorithm was used to estimate the location and heat generation rate of the source from these temperature distributions, in order to determine the location of an embedded tumor.
Abstract: Breast cancer is the most common cancer among women. Thermography, also known as thermal or infrared imaging, is a procedure to determine if an abnormality is present in the breast tissue temperature distribution. This abnormality in temperature distribution might indicate the presence of an embedded tumor. Although thermography is currently used to indicate the presence of an abnormality, there are no standard procedures to interpret these and determine the location of an embedded tumor. This research is a first step towards this direction. It explores the relationship between the characteristics (location and power) of an embedded heat source and the resulting temperature distribution on the surface. Experiments were conducted using a resistance heater that was embedded in agar in order to simulate the heat produced by a tumor in the biological tissue. The resulting temperature distribution on the surface was imaged using an infrared camera. In order to estimate the location and heat generation rate of the source from these temperature distributions, a genetic algorithm was used as the estimation method. The genetic algorithm utilizes a finite difference scheme for the direct solution of the Pennes bioheat equation. It was determined that a genetic algorithm based approach is well suited for the estimation problem since both the depth and the heat generation rate of the heat source were accurately predicted.
73 citations
TL;DR: A unique model, based on the logarithmic derivatives of a series solution for the surface temperature of a flash heated plate with adiabatic boundary conditions, provides a template for identifying pixels that deviate from uninterrupted diffusion that is characteristic of a defect-free sample.
Abstract: The use of thermography as a nondestructive testing method has increased significantly in recent years. However, implementation is usually based on visual interpretation of image results by a trained inspector. Although this is accepted practice in the aerospace industry, where thermography is widely used, it is not appropriate for automotive manufacturing, where higher production rates demand higher inspection throughput that can only be accomplished with automated detection. The logarithmic derivatives of flash thermography time histories provide an excellent basis for automated detection. A unique model, based on the logarithmic derivatives of a series solution for the surface temperature of a flash heated plate with adiabatic boundary conditions, provides a template for identifying pixels that deviate from uninterrupted diffusion that is characteristic of a defect-free sample. We demonstrate automated defect detection using this model on a composite sample.
72 citations
TL;DR: This paper presents methodology, results, and validation of a 3-D spatial and temporal ultrasound temperature estimation technique in an alginate-based gel phantom to track the evolution of heat deposition over a treatment volume and demonstrates potential for applicability in image guidance of thermal therapy.
Abstract: Thermal therapies such as radio frequency, heated saline, and high-intensity focused ultrasound ablations are often performed suboptimally due to the inability to monitor the spatial and temporal distribution of delivered heat and the extent of tissue necrosis. Ultrasound-based temperature imaging recently was proposed as a means to measure noninvasively the deposition of heat by tracking the echo arrival time shifts in the ultrasound backscatter caused by changes in speed of sound and tissue thermal expansion. However, the clinical applicability of these techniques has been hampered by the two-dimensional (2-D) nature of traditional ultrasound imaging, and the complexity of the temperature dependence of sound speed for biological tissues. In this paper, we present methodology, results, and validation of a 3-D spatial and temporal ultrasound temperature estimation technique in an alginate-based gel phantom to track the evolution of heat deposition over a treatment volume. The technique was experimentally validated for temperature rises up to ~10degC by comparison with measurements from thermocouples that were embedded in the gel. Good agreement (rms difference=0.12degC, maximum difference=0.24degC) was observed between the noninvasive ultrasound temperature estimates and thermocouple measurements. Based on the results obtained for the temperature range studied in this paper, the technique demonstrates potential for applicability in image guidance of thermal therapy for determining the location of the therapeutic focal spot and assessing the extent of the heated region at subablative intensities.
01 May 2007
TL;DR: Active infrared thermography refers to the group of methods employed to inspect the integrity of materials or systems through the use of an external energy source and an infrared detector as mentioned in this paper, which can be of many forms such as warm or cold air, heat pulses, periodic thermal waves, or mechanical oscillations, e.g. ultrasound.
Abstract: Active infrared thermography refers to the group of methods employed to inspect the integrity of materials or systems through the use of an external energy source and an infrared detector. The external stimulus can be of many forms such as warm or cold air, heat pulses, periodic thermal waves, or mechanical oscillations, e.g. ultrasounds. The way data is captured and processed, as well as the typical applications differ according to the excitation source. This chapter presents a review of three of the most common active techniques in the field of thermography: pulsed thermography, lock-in thermography and vibrothermography.
TL;DR: In this article, the authors provide information on several commonly used thermography techniques in semiconductor and micro-device industry and research today, including thin coating methods, contact mechanical methods, and optical techniques such as infrared microscopy and thermoreflectance.
Abstract: Purpose – The goal of this review paper is to provide information on several commonly used thermography techniques in semiconductor and micro‐device industry and research today.Design/methodology/approach – The temperature imaging or mapping techniques include thin coating methods such as liquid crystal thermography and fluorescence microthermography, contact mechanical methods such as scanning thermal microscopy, and optical techniques such as infrared microscopy and thermoreflectance. Their principles, characteristics and applications are discussed.Findings – Thermal issues play an important part in optimizing the performance and reliability of high‐frequency and high‐packing density electronic circuits. To improve the performance and reliability of microelectronic devices and also to validate thermal models, accurate knowledge of local temperatures and thermal properties is required.Originality/value – The paper provides readers, especially technical engineers in industry, a general knowledge of severa...
TL;DR: In this paper, the authors estimate the weldability of a polymeric material couple according to their thermal and optical properties using Mie theory and Monte Carlo method, and validate the results by infrared thermography.
TL;DR: In this paper, a new approach is proposed for a priori ascertaining the suitability of infrared thermography for the non-destructive evaluation purposes of materials, which regards a cause/effect relationship between the thermal signature perceived by the infrared camera and a dimensionless group, which includes geometrical and thermal characteristics of the defect and host material.
09 Apr 2007
TL;DR: In this article, a comparative study involving three active techniques: pulsed thermography, lock-in thermography and vibrothermography was performed on two typical aerospace parts: honeycomb structures and Glare.
Abstract: Inspection of aerospace components has always been a challenge. Infrared thermography has demonstrated to be a useful tool for this matter. In this paper, we offer a comparative study involving three active techniques: pulsed thermography, lock-in thermography and vibrothermography. Some of these techniques have proven to be more effective than others for a specific type of system. We compare the experimental results from these three techniques as applied to two typical aerospace parts: honeycomb structures and Glare. The later is perhaps the most challenging of all as will be pointed out. Some insights are provided regarding the most suitable technique for a number of typical situations.
TL;DR: Using near-infrared thermography microscopy and a low-cost charge-coupled device (CCD) camera, a system which is able to deliver quantitative submicronic thermal images is designed and a good relationship between a theoretical study and a thermal measurement of a microsample is shown.
Abstract: Using near-infrared thermography microscopy and a low-cost charge-coupled device (CCD) camera, we have designed a system which is able to deliver quantitative submicronic thermal images. Using a theoretical model based on Planck's law and CCD sensor properties allowed us to determine a minimal theoretical detection temperature and an optimal temperature sensitivity of our system. In order to validate this method, we show a good relationship between a theoretical study and a thermal measurement of a microsample.
TL;DR: In this paper, an experimental study using an infrared thermography system is performed using an experimental method using the temperature transient variation of a thin plate (tested fin) in order to obtain detailed quantitative heat transfer coefficients.
TL;DR: In this article, the authors introduced infrared thermography as a noncontact and non-destructive technique that conveniently offers the possibility of evaluating the energy-dissipating ability of soil, generally difficult to be determined using traditional techniques.
TL;DR: In this paper, the authors developed a reliable and precise non-destructive testing technique based on infrared thermography and post processing by means of neural networks for concrete structures strengthened by bonded FRP.
TL;DR: In this paper, the authors describe an approach to the use of thermal data for shaded leaves rather than areas fully exposed to the sun, and make use of infrared thermography as a powerful tool to measure effects of solar radiation on berry temperature.
Abstract: Aims: The objective of this paper was to describe an approach to the use of thermal data for shaded leaves rather than areas fully exposed to the sun. Secondly to make use of infrared thermography as a powerful tool to measure effects of solar radiation on berry temperature.Methods and results: Thermal images were obtained with a long-wave thermal imager. There is often less variability within an image for a shaded portion of the canopy than for a sunlit canopy. The temperature frequency distributions of sunlit leaves displayed a far wider range of temperature variation compared to shaded leaves.Conclusion: With thermal imagers it is feasible to select precisely the leaves for investigation. The remote sensing approach using infrared thermography combined with techniques available for image analysis open up a number of opportunities for comparative studies such as screening activities.Significance and impact of study: Infrared thermography can be implemented as a first line of detection to determine the onset of plant stress due to changes in stomatal aperture. This approach can give reliable and sensitive indications of leaf temperature and hence to calculate stomatal conductance.
TL;DR: In this paper, the use of an imaging IR thermography system was used for monitoring the microclimatic conditions promoting incidence and severity of diseases within wheat fields with a high spatial resolution.
Abstract: Computer-aided diagnosis and prognosis models have been used for management decisions in crop protection. Initial infection rate, temperature and leaf wetness are important parameters in disease epidemiology and for decision support models. So far, in-field variability and variability between fields have not been taken into account for management decisions in disease control. This study aimed at testing the use of an imaging IR thermography system as a tool for monitoring the microclimatic conditions promoting incidence and severity of diseases within wheat fields with a high spatial resolution. Experiments were conducted on the detection and differentiation of leaf wetness on a single leaf scale and a crop canopy scale (1 m2) under controlled conditions. Field studies focused on comparing ground-based and air-borne thermographic data and linking these to ground-truth data.
TL;DR: In this paper, the authors identify glass infrared reflection errors and their consequences when performing outdoor thermographs and propose and experimentally validate a correction method for correcting these errors, and also present a method for estimating a thermographic equivalent sky temperature that can be used in correction procedures for the own outdoor thermographic measurements.
TL;DR: In this article, the effects of wing sweep and other parameters (angle of attack, leading-edge contour, presence/absence of surface roughness) are successfully observed.
Abstract: The study of boundary-layer transition in supersonic flows is conducted employing infrared thermography (IRT). Several models of swept wings are tested in a blow-down facility at Mach number 2.4. The effects of wing sweep and other parameters (angle of attack, leading-edge contour, presence/absence of surface roughness) are successfully observed. The transition front is clearly identified, demonstrating the utility of IRT for this type of study. The technique is particularly indicated for flows that are sensitive to surface alterations (roughness), such as transitional boundary layers, because it does not require interaction with the model or the flow under investigation. The additional advantage of no need for special apparatus, except for the infrared camera, makes IRT well suited for both wind-tunnel and in-flight testing. Practical problems and limitations encountered when dealing with IRT in high-speed flows are also discussed.
Journal Article•
TL;DR: This work aims to study the usability of infrared thermography in swimming for the purpose of quantifying the influence of the swimming style on the cartographies of cutaneous temperatures of a swimmer.
Abstract: This work aims to study the usability of infrared thermography in swimming for the purpose of quantifying the influence of the swimming style on the cartographies of cutaneous temperatures of a swimmer. Only one subject took part in the experimental protocol, who was to accomplish a 4 x 100 m 4 medley. Thermal acquisitions followed by one period of recovery with return to thermal balance were carried out between particular strokes. IR thermography made it possible to discuss the influence of the swimming style on the distributions of cutaneous temperatures in various body zones. This process seems to be completely adaptable to the development of future statistical studies.
TL;DR: In this article, a simple model that takes into account the noise characteristics of the camera, and uses that as a basis for predicting camera response was developed, and the method also predicts minimum detectable flaw diameters as a function of depth, noise and input energy.
Abstract: Flash thermography data is typically interpreted as either a sequence of images, or a collection of pixel time histories acquired after flash heating of the surface. Modelling of the process typically requires a detailed understanding of the thermophysical properties of the sample, as well as the amount of energy used to excite the sample. Often, this information is not available to the NDT practitioner. Furthermore, since flash thermography is often performed with infrared cameras that do not provide absolute temperature data, it may be difficult to correlate modelling predictions to the output of the camera. We have developed a simple model that takes into account the noise characteristics of the camera, and uses that as a basis for predicting camera response. Input energy is expressed as a multiple of noise, and can be measured from the data without the use of additional instrumentation. The method also predicts minimum detectable flaw diameters as a function of depth, noise and input energy, and provi...
TL;DR: In this article, a defect selective "dark field" NDT technique with a high probability of defect detection (PoD) is presented, where only defects produce a signal while other features are suppressed.
Abstract: Ultrasound lock-in thermography ('attenuation mapping') is a defect selective 'dark field' NDT technique with a high probability of defect detection (PoD), since only defects produce a signal while other features are suppressed. The basic contrast mechanism is the enhanced local mechanical loss turning a variably loaded defect into a heat source. The method is being applied for quality maintenance, for example in the aerospace and automotive industry to monitor the integrity of thermal features. A variety of examples will be presented to illustrate how well the method is suited to locate defects and to distinguish their depths.
Journal Article•
TL;DR: Although thermography is often described as a new or emerging NDT method, it has a long history as discussed by the authors, and it has been used in NDT for a long time.
Abstract: Although thermography is often described as a new or emerging NDT method, it has a long history.
28 Mar 2007
TL;DR: In this paper, the location of fatigue cracks was determined by flying spot scanning with a pulsed laser beam using long pulse heating and a flying spot scanner, and the results were compared with a preliminary 2D numerical model.
Abstract: A surface crack, close to a laser heated spot, impedes lateral heat flow and produces alterations in the shape of the laser spot image that can be monitored by thermography. The technique has been found to be successful for determining the location of fatigue cracks. Results are presented that have been obtained using long pulse heating and by flying spot scanning a pulsed laser beam. The results are compared with a preliminary 2D numerical model.