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2258 KiB

Open AccessArticle

Computer Assisted Examination of Infrared and Near Infrared Spectra to Assess Structural and Molecular Changes in Biological Samples Exposed to Pollutants: A Case of Study

by Mauro Mecozzi and Elena Sturchio

J. Imaging 2017, 3(1), 11; https://doi.org/10.3390/jimaging3010011 - 16 Feb 2017

Cited by 36 | Viewed by 6630

Abstract

We present a computer assisted method for the examination of the structural changes present in the probe organism Vicia faba exposed to inorganic arsenic, detected by means of Fourier transform infrared (FTIR) and Fourier transform near infrared (FTNIR) spectroscopy. Like the common ecotoxicological [...] Read more.

We present a computer assisted method for the examination of the structural changes present in the probe organism Vicia faba exposed to inorganic arsenic, detected by means of Fourier transform infrared (FTIR) and Fourier transform near infrared (FTNIR) spectroscopy. Like the common ecotoxicological tests, the method is based on the comparison among control and exposed sample spectra of the organisms to detect structural changes caused by pollutants. Using FTIR spectroscopy, we measured and plotted the spectral changes related to the unsaturated to saturated lipid ratio changes (USL), the lipid to protein ratio changes (LPR), fatty and ester fatty acid content changes (FA), protein oxidation (PO) and denaturation, and DNA and RNA changes (DNA-RNA). Using FTNIR spectroscopy, we measured two spectral ranges that belonged to hydrogen bond interactions and aliphatic lipid chains called IntHCONH and Met1overt, respectively. The FTIR results showed that As modified the DNA-RNA ratio and also caused partial protein denaturation in the Vicia faba samples. The FTNIR results supported the FTIR results. The main advantage of the proposed computational method is that it does not require a skilled infrared or near infrared operator, lending support to conventional studies performed by toxicological testing. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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11351 KiB

Open AccessArticle

An Excursus on Infrared Thermography Imaging

by Carosena Meola, Simone Boccardi and Giovanni Maria Carlomagno

J. Imaging 2016, 2(4), 36; https://doi.org/10.3390/jimaging2040036 - 18 Dec 2016

Cited by 3 | Viewed by 6544

Abstract

This work represents an overview of some of the applications of infrared thermography that have been carried out at the University of Naples Federico II over the years. The focus is on four topics: thermo-fluid-dynamics, materials inspection, cultural heritage and preventative maintenance. For [...] Read more.

This work represents an overview of some of the applications of infrared thermography that have been carried out at the University of Naples Federico II over the years. The focus is on four topics: thermo-fluid-dynamics, materials inspection, cultural heritage and preventative maintenance. For each topic, some results are presented as thermal, and/or phase, images with the attention being essentially devoted to the capacity of these images to communicate information. For more details on test apparatuses, procedures and data analyses, the reader is referred to the previous published work, available in the literature. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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1851 KiB

Open AccessArticle

Active Infrared Thermography for Seal Contamination Detection in Heat-Sealed Food Packaging

by Karlien D’huys, Wouter Saeys and Bart De Ketelaere

J. Imaging 2016, 2(4), 33; https://doi.org/10.3390/jimaging2040033 - 16 Nov 2016

Cited by 13 | Viewed by 8019

Abstract

Packaging protects food products from environmental influences, assuring quality and safety throughout shelf life if properly performed. Packaging quality depends on the quality of the packaging material and of the closure or seal. A common problem possibly jeopardizing seal quality is the presence [...] Read more.

Packaging protects food products from environmental influences, assuring quality and safety throughout shelf life if properly performed. Packaging quality depends on the quality of the packaging material and of the closure or seal. A common problem possibly jeopardizing seal quality is the presence of seal contamination, which can cause a decreased seal strength, an increased packaging failure risk and leak formation. Therefore, early detection and removal of seal contaminated packages from the production chain is crucial. In this work, a pulsed-type active thermography method using the heated seal bars as an excitation source was studied for detecting seal contamination. Thermal image sequences of contaminated seals were recorded shortly after sealing. The detection performances of six thermal image processing methods, based on a single frame, a fit of the cooling profiles, thermal signal reconstruction, pulsed phase thermography, principal component thermography and a matched filter, were compared. High resolution digital images served as a reference to quantify seal contamination, and processed thermal images were mapped to these references. The lowest detection limit (equivalent diameter 0.60 mm) was obtained for the method based on a fit of the cooling profiles. Moreover, the detection performance of this method did not depend strongly on the time after sealing at which recording of the thermal images was started, making it a robust and generally applicable method. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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9493 KiB

Open AccessArticle

Mechanical Behaviour of Stainless Steels under Dynamic Loading: An Investigation with Thermal Methods

by Rosa De Finis, Davide Palumbo and Umberto Galietti

J. Imaging 2016, 2(4), 32; https://doi.org/10.3390/jimaging2040032 - 8 Nov 2016

Cited by 21 | Viewed by 5356

Abstract

Stainless steels are the most exploited materials due to their high mechanical strength and versatility in producing different alloys. Although there is great interest in these materials, mechanical characterisation, in particular fatigue characterisation, requires the application of several standardised procedures involving expensive and [...] Read more.

Stainless steels are the most exploited materials due to their high mechanical strength and versatility in producing different alloys. Although there is great interest in these materials, mechanical characterisation, in particular fatigue characterisation, requires the application of several standardised procedures involving expensive and time-consuming experimental campaigns. As a matter of fact, the use of Standard Test Methods does not rely on a physical approach, since they are based on a statistical evaluation of the fatigue limit with a fixed probabilistic confidence. In this regard, Infra-Red thermography, the well-known, non-destructive technique, allows for the development of an approach based on evaluation of dissipative sources. In this work, an approach based on a simple analysis of a single thermographic sequence has been presented, which is capable of providing two indices of the damage processes occurring in material: the phase shift of thermoelastic signal φ and the amplitude of thermal signal at twice the loading frequency, S2. These thermal indices can provide synergetic information about the mechanical (fatigue and fracture) behaviour of austenitic AISI 316L and martensitic X4 Cr Ni Mo 16-5-1; since they are related to different thermal effects that produce damage phenomena. In particular, the use of φ and S2 allows for estimation of the fatigue limit of stainless steels at loading ratio R = 0.5 in agreement with the applied Standard methods. Within Fracture Mechanics tests, both indices demonstrate the capacity to localize the plastic zone and determine the position of the crack tip. Finally, it will be shown that the value of the thermoelastic phase signal can be correlated with the mechanical behaviour of the specific material (austenitic or martensitic). Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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3279 KiB

Open AccessArticle

Transient Heat Transfer in Radiant Floors: A Comparative Analysis between the Lumped Capacitance Method and Infrared Thermography Measurements

by Giorgio Baldinelli, Francesco Bianchi, Antonella Rotili and Andrea Presciutti

J. Imaging 2016, 2(3), 22; https://doi.org/10.3390/jimaging2030022 - 19 Jul 2016

Cited by 6 | Viewed by 5984

Abstract

The paper presents a simplified mathematical model to describe the transient heat transfer of a radiant floor heating system. A purpose-built test room has been realized to investigate the actual thermal response of a concrete radiant floor in unsteady-state conditions. Beyond the temperature [...] Read more.

The paper presents a simplified mathematical model to describe the transient heat transfer of a radiant floor heating system. A purpose-built test room has been realized to investigate the actual thermal response of a concrete radiant floor in unsteady-state conditions. Beyond the temperature sensors needed for the standard thermal analysis of the heat transfer inside the chamber, the floor temperature was retrieved by means of an infrared thermography camera, in order to validate more precisely the proposed analytical model. The infrared thermography analysis gives interesting information on the floor temperature distribution during the transient, highlighting the pipes’ layout and, if present, inhomogeneous floor zones. The thermal images have been elaborated in order to set and tune the colour map. A portion of the image has been defined for measuring the surface floor temperatures with a previous evaluation of the parameters dealing with the thermographic technique, in order to perform the quantitative survey. The comparison results show that the calculated air and floor temperatures substantially agree with the temperatures measured by infrared thermography and thermocouples, provided that the boundary conditions obtained by the field measurements are strictly reproduced in the lumped capacitance mathematical model. The difference between the two approaches results in values lower than 4 °C during the entire monitoring period: a satisfactory outcome, considering the approximations of the analytical method. The proposed model and its infrared thermography measurements validation represent a useful tool to understand at first sight the floor radiant panels behaviour in the start-up and switch off period, at the aim of gather useful information for the difficult task of their regulation. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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3083 KiB

Open AccessArticle

Assessing Consistency in Radiated Thermal Output of Beef Steers by Infrared Thermography

by Nigel Cook, Edouard Timsit, Jeff Colyn, Brady Chabot, Tong Liu, Barbara Wolfger and Allan Schaefer

J. Imaging 2016, 2(3), 21; https://doi.org/10.3390/jimaging2030021 - 11 Jul 2016

Cited by 10 | Viewed by 5634

Abstract

Measurements of radiated thermal output are claimed to reflect the metabolic efficiency of mammals. This is important in food-producing animals because a measure of metabolic efficiency may translate to desirable characteristics, such as growth efficiency or residual feed intake, and permit the grouping [...] Read more.

Measurements of radiated thermal output are claimed to reflect the metabolic efficiency of mammals. This is important in food-producing animals because a measure of metabolic efficiency may translate to desirable characteristics, such as growth efficiency or residual feed intake, and permit the grouping of animals by metabolic characteristics that can be more precisely managed. This study addresses the question of whether radiated thermal parameters are characteristic of individual animals under normal and metabolically-challenging conditions. Consistency in radiated thermal output was demonstrated over a period of four weeks on condition that a sufficiently representative sample of measurements could be made on individual animals. The study provided evidence that infrared thermography could be used as an automated, rapid, and reliable tool for assessing thermoregulatory processes. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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4443 KiB

Open AccessArticle

Detection by Infrared Thermography of the Effect of Local Cryotherapy Exposure on Thermal Spreadin Skin

by Matthieu Vellard and Ahlem Arfaoui

J. Imaging 2016, 2(2), 20; https://doi.org/10.3390/jimaging2020020 - 13 Jun 2016

Cited by 6 | Viewed by 5478

Abstract

The aim of the study is to evaluate the impact of the exposure duration of local cryotherapy on the skin temperature of the thigh and of the knee. Ten subjects performed a low-intensity exercise, rested for 20 min without ice, and then rested [...] Read more.

The aim of the study is to evaluate the impact of the exposure duration of local cryotherapy on the skin temperature of the thigh and of the knee. Ten subjects performed a low-intensity exercise, rested for 20 min without ice, and then rested for 5 min and 10 min with ice under the right knee. The skin temperatures were measured by infrared thermography to assess the thermal spread. The results of the statistical analysis reveal an increase of skin temperature of the knee after an exposure of 5 min to the cryotherapy (p < 0.05). There are also differences inthermal regulation between the 10-min exposure and the absence of ice pack. The exposure time variation of local cryotherapy gives different physiological responses which vary in intensity and in location. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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7439 KiB

Open AccessArticle

Mapping of the Indoor Conditions by Infrared Thermography

by Frank Billy Djupkep Dizeu, Xavier Maldague and Abdelhakim Bendada

J. Imaging 2016, 2(2), 10; https://doi.org/10.3390/jimaging2020010 - 7 Apr 2016

Cited by 8 | Viewed by 8763

Abstract

We present an instrumentation devoted to the mapping of indoor ambient conditions by an infrared camera. In addition to a measurement grid composed of several spherical sensors, an infrared camera is used to visualize and quantify the spatial distribution of the air temperature, [...] Read more.

We present an instrumentation devoted to the mapping of indoor ambient conditions by an infrared camera. In addition to a measurement grid composed of several spherical sensors, an infrared camera is used to visualize and quantify the spatial distribution of the air temperature, the air speed, and the mean radiant temperature. A suitable procedure is developed so that from its temperature history recorded by the infrared camera, each sensor can measure, after solving an inverse heat transfer problem, all the three cited parameters. As the sensors are all imaged at the same time by the camera, an interpolation is done with the values they provide; the 2D distribution of each parameter is then obtained. By using a pair of stereoscopic cameras, it is possible to determine the 3D coordinates of each sensor of the measurement grid; consequently, the 3D mapping of the indoor ambient conditions is possible. Two steps are followed and allow us to achieve our goal: the validation of the performance of the sensor in terms of accuracy and reliability, and the validation of the complete experimental procedure which relies on digital image processing and on inverse heat transfer. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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8841 KiB

Open AccessArticle

Detection and Characterization of Defects in Isotropic and Anisotropic Structures Using Lockin Thermography

by Christiane Maierhofer, Philipp Myrach, Rainer Krankenhagen, Mathias Röllig and Henrik Steinfurth

J. Imaging 2015, 1(1), 220-248; https://doi.org/10.3390/jimaging1010220 - 21 Dec 2015

Cited by 24 | Viewed by 5756

Abstract

Lockin thermography is a well-suited method for the characterization of structures made of both metal and fiber reinforced plastic. In most cases, only phase images are analyzed, although the amplitude images might contain useful information as well. Thus, systematic studies of lockin thermography [...] Read more.

Lockin thermography is a well-suited method for the characterization of structures made of both metal and fiber reinforced plastic. In most cases, only phase images are analyzed, although the amplitude images might contain useful information as well. Thus, systematic studies of lockin thermography are presented, assessing amplitude and phase images for the detection and quantification of defects in isotropic (steel) and anisotropic (carbon fiber reinforced plastic) materials. Characterized defects are flat bottom holes with different diameters and various remaining wall thicknesses as well as crossed notches at different depths. The excitation frequency was varied while keeping the number of analyzed excitation periods nearly constant for each material. The data analysis was focused on the detectability of the defects both in the amplitude and phase images, including the determination of the signal-to-noise ratio and of the spatial resolution. As a result, the limits of defect detectability and spatial resolution are given for each material. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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Review

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3693 KiB

Open AccessReview

An Overview of Infrared Remote Sensing of Volcanic Activity

by Matthew Blackett

J. Imaging 2017, 3(2), 13; https://doi.org/10.3390/jimaging3020013 - 12 Apr 2017

Cited by 65 | Viewed by 12281

Abstract

Volcanic activity consists of the transfer of heat from the interior of the Earth to the surface. The characteristics of the heat emitted relate directly to the geological processes underway and can be observed from space, using the thermal sensors present on many [...] Read more.

Volcanic activity consists of the transfer of heat from the interior of the Earth to the surface. The characteristics of the heat emitted relate directly to the geological processes underway and can be observed from space, using the thermal sensors present on many Earth-orbiting satellites. For over 50 years, scientists have utilised such sensors and are now able to determine the sort of volcanic activity being displayed without hazardous and costly field expeditions. This review will describe the theoretical basis of the discipline and then discuss the sensors available and the history of their use. Challenges and opportunities for future developments are then discussed. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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1079 KiB

Open AccessReview

The Herschel Heritage to Medical Thermography

by Francis Ring

J. Imaging 2016, 2(2), 13; https://doi.org/10.3390/jimaging2020013 - 14 Apr 2016

Cited by 7 | Viewed by 10905

Abstract

The discovery of infrared radiation by William Herschel in 1800 led to John Herschel’s study of solar radiation that he imaged by evaporography. This he termed a thermogram. The measurement of temperature in medicine advanced with Dr Carl Wunderlich, who showed the significance [...] Read more.

The discovery of infrared radiation by William Herschel in 1800 led to John Herschel’s study of solar radiation that he imaged by evaporography. This he termed a thermogram. The measurement of temperature in medicine advanced with Dr Carl Wunderlich, who showed the significance of the use of temperature measurements for diagnosis of fever and for monitoring the course of temperature in relation to disease. It was William and John Herschel’s discovery of infrared radiation that has ultimately opened up many applications for thermal imaging. Radiometric determination of human body (skin) temperature is now achievable. Remote sensing of infrared radiation first developed in the 1940s and has continued to develop steadily since 1960. Modern high speed and high resolution camera systems have now reached a dramatic level of performance at more modest costs, which medicine can now employ for non-invasive and quantifiable imaging. This has applications in many areas of medicine both for diagnostics and monitoring treatment. In recent years the acute threat of pandemic infection has increased, heightened by today’s ever expanding world travel. Special interest has been shown in the potential of thermal imaging for airport and travel screening. This is in effect where Dr Wunderlich’s studies began, and it has yet to be proven that the technique can be responsibly employed for efficient screening of large numbers of the travelling public. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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9127 KiB

Open AccessReview

Review of Active IR Thermography for Detection and Characterization of Defects in Reinforced Concrete

by Bojan Milovanović and Ivana Banjad Pečur

J. Imaging 2016, 2(2), 11; https://doi.org/10.3390/jimaging2020011 - 7 Apr 2016

Cited by 87 | Viewed by 16229

Abstract

Active thermography methods enable structural investigations of reinforced concrete elements taking into account many different testing problems. The goal of this review is to provide an overview on the state-of-the-art regarding the use of active infrared thermography (IRT) for detection and characterization of [...] Read more.

Active thermography methods enable structural investigations of reinforced concrete elements taking into account many different testing problems. The goal of this review is to provide an overview on the state-of-the-art regarding the use of active infrared thermography (IRT) for detection and characterization of defects in reinforced concrete. The paper will provide the physical background, equipment being used, as well as post-processing methods that are used to analyse sequences of thermograms. This work also presents the fields of applicability of IRT with a focus on the aspects related to reinforced concrete structures, as well as the advantages, limitations and potential sources of errors of IRT employment. Additionally previous non-destructive testing (NDT) studies that employed thermography techniques with natural excitation are briefly presented. A review of the future trends of thermal imaging are also included in this work. It can be concluded that while IRT is a useful tool for the characterisation of defects in the building sector, there is great prospect for the development of more advanced, effective and accurate approaches that will employ a combination of thermography approaches. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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12535 KiB

Open AccessReview

Thermal Imaging of Electrochemical Power Systems: A Review

by James B. Robinson, Paul R. Shearing and Daniel J. L. Brett

J. Imaging 2016, 2(1), 2; https://doi.org/10.3390/jimaging2010002 - 6 Jan 2016

Cited by 34 | Viewed by 10342

Abstract

The performance and durability of electrochemical power systems are determined by a complex interdependency of many complex and interrelated factors, temperature and heat transfer being particularly important. This has led to an increasing interest in the use of thermal imaging to understand both [...] Read more.

The performance and durability of electrochemical power systems are determined by a complex interdependency of many complex and interrelated factors, temperature and heat transfer being particularly important. This has led to an increasing interest in the use of thermal imaging to understand both the fundamental phenomena and effects of operation on the temperature distribution and dynamics in these systems. This review describes the application thermal imaging and related techniques to the study of electrochemical power systems with the primary focus on fuel cells and batteries. Potential opportunities and directions for future research are also highlighted, indicating the wide scope for further insights to be gleaned using infrared thermal imaging techniques. Full article

(This article belongs to the Special Issue The World in Infrared Imaging)

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