This PDF file contains the front matter associated with SPIE Proceedings Volume 6541, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

The accuracy of infrared temperature estimation can degrade significant for enclosed objects with reflective surfaces. This paper describes a basic model of the incident radiation on a FPA sensor element considering a target object, surrounding environment, surface temperatures, surface emissivity/reflection and optics. The model is used to characterize the direct (one color method) temperature estimation error as a function of reflection, wavelength, target temperatures and the environment geometry. Temperature estimation errors based on numerical simulations with focus on near infrared are compared in this paper in a variety of scenarios assuming target temperatures between 1000 to 1600 Kelvin. In one scenario is the measured radiation corrected to minimize the error due to reflection.

Visible image mixing function, or image fusion, is the way of combining color thermal image and black and white visible by thermography camera. The visible image mixing function allows you to pinpoint location of hot spot or cold spot on the object. The mixed data are gathered from wide variety of application including R&D, PPM and process monitoring.

Thermographers have always wanted an infrared camera that produces images with both a wide field of view (FOV) and detailed spatial resolution. An infrared-only camera with this combination is prohibitively expensive for most applications. A less expensive way of providing both features in a single camera is to blend a wide FOV visible image with a smaller FOV infrared image. The major benefit of this combination is that thermographers can pinpoint and identify infrared problem areas in a clear visible picture. A commercial camera with this innovative IR/visible fusion technology was introduced in the paper "Commercial Fusion Camera" presented at the ThermoSense XXVIII (Volume 6205, paper 6205-18, 2005) Maintenance technicians now have a direct correlation between a visible picture and an infrared identified problem area. Building inspectors can use this technology to advantage in negotiating and litigating problems. This paper reports progress on applications since the presentation of last year's paper, and illustrates new thermography examples that benefit from this cost-effective approach to thermal image fusion.

Imaging in the Short Wave Infrared (SWIR) provides unique surveillance capabilities, both with passive illumination from the night glow in the atmosphere or with active illumination from covert LED or eye-safe lasers. Spectral effects specific to the 0.9 to 1.7 um wavelength range reveal camouflage and chemical signatures of ordinance. The longer wavelength range also improves image resolution over visible cameras in foggy or dusty environments. Increased military interest in cameras that image all laser range finders and target designators on the battlefield has driven development of a new class of uncooled InGaAs cameras with higher resolution and larger field of view than previously available. Current and upcoming needs include: imaging in all lighting conditions, from direct sunlight to partial starlight while using minimal power; range gating the camera to image through obscurants or beyond unimportant objects; and high speed capture of muzzle flare, projectile tracking, guide star and communications laser-beam tracking and wavefront correction. This paper will present images from new COTS cameras now available to address these needs and discuss the technology roadmap for further improvements.

This paper presents and describes an approach to retrieve concentration of particulate matter of size less than 10- micron (PM10) from Landsat TM data over Penang Island. The objective of this study is test the feasibility of using Landsat TM for PM10 mapping using our proposed developed algorithm. The development of the algorithm was developed base on the aerosol characteristics in the atmosphere. PM10 measurements were collected using a DustTrak Aerosol Monitor 8520 simultaneously with the image acquisition. The station locations of the PM10 measurements were detemined using a hand held GPS. The digital numbers were extracted corresponding to the ground-truth locations for each band and then converted into radiance and reflectance values. The reflectance measured from the satellite [reflectance at the top of atmospheric, ρ(TOA)] was subtracted by the amount given by the surface reflectance to obtain the atmospheric reflectance. Then the atmospheric reflectance was related to the PM10 using regression analysis. The surface reflectance values were created using ACTOR2 image correction software in the PCI Geomatica 9.1.8 image processing software. The proposed developed algorithm produced high accuracy and also showed a good agreement (R =0.8406) between the measured and estimated PM10. This study indicates that it is feasible to use Landsat TM data for mapping PM10 using the proposed algorithm.

In this paper we discuss the thermal properties of water as they relate to the structures, buildings in particular, thermographers routinely inspect. Interestingly, it is the unique thermal properties of water that allow us, under the right conditions, to locate its very presence in a building. Unfortunately, when conditions are less than ideal, water is often all but impossible to detect thermally. It is important then, to understand both the properties and behavior of this common substance as well as the conditions that cause it to be revealed. To this end we will also show examples of the interaction of water and heat and the surrounding materials as we observed them in several controlled situations. We will also apply the lessons learned to a wider variety of real world thermal imaging situations

During the MEGAPIE Integral Test (MIT) of the 1MW liquid metal (LM) target for a spallation neutron source, infrared thermography (IRT) has been used to investigate the liquid lead-bismuth eutectic (LBE) cooling of the proton beam entry window of the target. The IRT investigations have been performed on the real MEGAPIE target on the MIT stand (MITS) at Paul Scherrer Institute (PSI) in Switzerland, few months before of the proton irradiation period of the target. In meantime the target has been successfully irradiated (from August to December 2006) at the PSI Spallation Neutron Source (SINQ) facility; for more details see web page http://megapie.web.psi.ch/. The Goals of the MIT thermo-hydraulics investigations of the liquid LBE "flow in flow" window cooling configuration (ca. 1.25 m/s speedy by-pass jet flow into the ca. 0.33 m/s main flow), have bifocal perspective. On one hand the goal was visualization for an observation of changes of the target cooling field pattern of the by-pass jet flow, i.e. the qualitative investigation of cooling behavior in terms of the sufficient geometrical covering of the proton beam irradiation footprint area. On second hand the goal was determination of local convection heat transfer coefficient (HTC) on the steel wall of the proton beam entry window area of the MEGAPIE target, i.e. the quantitative values and distribution of a cooling. For the qualitative visualization of the real, "in situ", target window cooling we have take advantage of slightly higher temperature of the by-pass jet flow LBE streaming (ca. 4°K) and we have performed so called "MIT-Warm-Jet" experiment series. For the quantitative determination of HTC instead of the real target window we have used specimen sensor dish and performed so called "MIT-KILOPIE" experiment series using the two dimensional and dynamic infrared thermography (2DD-IRT) method, which has been developed and tested in 2005 at PSI; reported during Thermosense XVIII in 2006 [1]. The results of measurements are presented in form of IRT thermograms or thermogram sequences which are extracted from the raw temperature field measurements. The in December 2006 successfully finished irradiation period of MEGAPIE project and the integrity of the whole target have shown and proved the predicted sufficiency of the window cooling.

A method to retrieve the land surface temperature (LST) over Mecca, Saudi Arabia are developed using band 6 of the Landsat TM thermal channel. The objective of this study was to focus on the estimation of the LST from Landsat TM 5 imageries. The data used was captured by Thematic Mapper (TM) sensor onboard the Landsat 5 satellite. Landsat TM has only one thermal band, and therefore the spilt-window algorithm cannot be used for the retrieval of LST. In this study, we are proposed a single channel algorithm for retrieving LST. The land surface emissivity and solar angle values are needed in order to apply these in the proposed algorithm. The surface emissivity values were computed based on the NDVI values. The correlation between the LST and the brightness temperature had increased significantly after the surface emissivity and solar zenith angle were included in the algorithm. The reference values LST were determined using ATCOR2_T in the PCI Geomatica image 9.1 processing software for algorithm calibration. The results indicate that the single channel algorithm was suitable for retrieving LST values from remotely sensed data.

This work discusses the automated application of the micro-bolometric and the photonic cooled infrared arrays, in the context of the automotive assembly operations. Such usages comprise: static thermographic applications as in evaluating the protective coating coverage over steel-fuel tanks. Furthermore, this discussion includes a variety of processing algorithms dedicated for handling the acquired infrared sequences or scans; addressing challenges in emissivity variations, sensor saturation, and surrounding contribution, while introducing possible solution schemes. The physics and detection methodology are presented through modeling and simulation work.

The possibility of reducing defects in the arc welding process has attracted research interest, particularly, in the aerospace and nuclear sectors where the resulting weld quality is a major concern and must be assured by costly, time-consuming, non-destructive testing (NDT) procedures. One possible approach is the analysis of a measurand correlated with the formation of defects, from which a control action is derived. Among others, the thermographic analysis of the weld pool and the heat-affected zone have proven to be a useful technique, since the temperature profile of the material being welded has a clear correlation with the process parameters. In this paper, we propose a control system for the submerged-arc welding (SAW) process, based on thermographic imaging of the back face of the joint being welded. In-lab experiments, with simultaneous infrared and a visible imaging, have been performed. Two image analysis techniques are proposed: tracking of the maximum temperature point of the infrared images, and morphological analysis of the visible images. In-lab welding experiments have demonstrated the feasibility of both techniques. They are able to obtain an estimation of the surface temperature and to detect the occurrence of the perforation defect, what has major application for defect detection and reduction in the joining of shell sections of nuclear steam generators.

This paper reviews applications of infrared thermal profiling techniques to detection of faults and defects in electronics. Issues essential to the successful application of infrared techniques to electronics manufacturing and circuit card maintenance are investigated. These issues include basic know-how such as scanning time interval and screening variables; a description of the types of defects and faults these methods have been used to detect; and a comparison of infrared thermal imaging and other detection means such as X-ray and functional testers. Future directions include design for infrared diagnosis and development of integrated testing technique for detection and root-cause analysis and development of hybrid analysis techniques, such as combining genetic algorithms and neural network techniques for thermal profile pattern recognition.

This work is about three real applications in the steel industry where the infrared technology is used to control the process and to increase safety. All the applications where developed by Ternium-Siderar automation group. The main objectives are to use the infrared thermography in steel plant are to reduce production costs and to prevent mayor damages. The first work is about automatic slag detection during the tapping operation of the Blast Oxygen Furnace (BOF) converters by thermographical image processing. The benefit is to reduce fluxes due to less slag carryover and also to eliminate the ladle recirculation for excessive slag. Additionally, the steel shop process engineers are using the camera information to estimate some other process variables. There is a project to make all the BOF tapping fully automatic, using the camera information. The second work is about on-line ladle hot spot detection. A failure of the ladle refractory bricks may cause damages in the ladle car, mechanical equipment, and cabling in the ladle furnace. To detect these failures, a system of four infrared cameras with an image processing software was developed. Also in future applications, the thermal information is going to be used for data correlation with other process variables. The third one is in the sinter plant, where the camera temperature information is used to optimize the process control. Before the system installation, there was no available information about the sinter material temperature. Nowadays there is an on-line information that is used to close the control loop.

Utilizing imaging radiometers to control process and monitor quality and safety of plant equipment is a reality now more than ever. As with any technology cost is a driving factor as well as return on investment. This paper will discuss a brief history and one specific system and briefly describe several others.

Infrared thermography is a non-contact evaluation technique which allows not only the registration of the temperature distribution on a surface, but also the calculation of the amount of heat flowing through it. Boilers are important for industry and the quantification of the heat losses is beneficial to avoid fuel waste. The present work suggests a methodology to calculate the thermic flow through boiler's isolation surfaces, using thermic images. With this, it is possible to find the flow by using a thermogram taking into consideration: the thermogram's range, knowing the camera's FOV, surface's emmisivity and characteristic length, object-to-camera distance, environmental temperature, and the assigned grey-level calibration curve to determined temperature range. A software tool to upload and process the information was developed. This tool can calculate the surface's average convection coefficient hc by using empiric correlations developed for common geometries and heat transfer equations to calculate the thermic flow. To test the technique functioning, the information given by the software tool was compared to the data given by the heat flow measurement thermal sensor. This comparison showed a 3% error range of relative error. The final validation was made on a waterwall-boiler's home isolated walls and the highest error obtained was close to 15%. Regardless the calibration curve was found under laboratory conditions and the empiric correlations to calculate hc are for isometric surfaces, the methodology presented a good performance. This then is a first step to quantify the global heat losses on boiler's isolation surfaces.

Corrosion of airport pavements is a major problem involved with materials engineering and transportation engineering. Airport pavements frequently start to deteriorate slowly primarily, gradually progressing to failure. Such failure can be expensive in terms of both money and lives, but can also be prevented. For that reason, intelligent techniques should be suggested, with the intention of examining the condition of such engineering structures. IR thermography and ground penetrating radar are two NDT (non-destructive testing) techniques that have the ability to inspect effectively substantial areas, such as airport pavements. In this work, two different airport pavements located at the International Airport of Athens, in Greece, were investigated by the use of the above two mentioned techniques. Successful detection of cracks, voids and other imperfections appearing either from the aging of the materials or due to poor workmanship was attained. Furthermore, this paper describes the problem of deteriorated airport pavements, shows the process and the apparatus used for the in situ tests, and finally presents results obtained from the investigations.

This work deals with the development of an experimental protocol for the diagnostic of multi-layered insulated building walls. First, a test bench is set up in order to measure front and back sides temperatures of standard panels. The panels considered have insulation thicknesses of 2, 6 and 10cm. The front side is heated by two halogen lamps of 500W. A CEDIP Jade Long wave infrared camera and thermocouples are used to carry out temperature measurements. In a second time, a one dimensional model based on thermal quadruples and Laplace transforms was developped under Matlab environment. Also, we developped a three dimensional model based on finite volumes using Fluent computational code. Finally, a method of identification of physical parameters is implemented by performing least square minimization based on Levenberg-Marquardt method. The experimental measurements are compared to theoretical results and by minimization we obtain thermal conductivity and diffusivity as well as thickness of the two layers.

Railroads are close to capacity and there is only so much that can be squeezed through a pipe. The result is insufficient equipment, longer trains, tighter schedules and of course the stretching of personnel. Now, imagine that as one of these freight trains, comprising among other things, chemical tankers and boxcars containing a variety of different materials (including hazardous materials) while crossing a river has the trestle collapse underneath it. Hundreds of thousands of pounds of steel, wood and of course the hazardous chemicals fall into the river, pollute the land and the river, and shut down a port. Farfetched? This paper will reveal the results of a unique thermographic inspection, the findings, the results and the protocols.

The Canadian National Master Construction Specification (NMS) is the most comprehensive master specification available commercially in North America; each section serves as an easy-to-use framework for writing construction project specifications. The NMS Secretariat contracted, through consultations with the building industry and departmental experts in Public Works and Government Services Canada, the development of four new specification sections for commonly implemented infrared thermographic services associated with building construction and maintenance. These include inspection services for building envelopes, roofs, mechanical equipment, and electrical systems. This paper will introduce the four types of inspection services found in these sections and discuss the relevant information that each service provides. Additionally, the paper will highlight the important differences of each type of inspection services, thus explaining the need to develop individual specification sections to correspond for each type of infrared thermographic inspection service. These sections include all aspects of such services and are all encompassing in their scope. The NMS maximizes protection against duplication and errors, while minimizing chances of risk, misunderstanding and liability. It can be edited and adapted for any size and type of construction project, for government or the private sector. Building owners and property managers can integrate these thermographic specifications into their Project Manuals or incorporate them into contractual documents to call up services for building condition studies. Although the NMS was primarily designed for use in the commercial and light industrial building industry, the residential construction industry can benefit as well, by modifying any section for their use. This paper will discuss these differences, and provide suggestions for the development of such a residential specification format.

A Building Commissioning-project (ToVa) was launched in Finland in the year 2003. A comprehensive commissioning procedure, including the building process and operation stage was developed in the project. This procedure will confirm the precise documentation of client's goals, definition of planning goals and the performance of the building. It is rather usual, that within 1-2 years after introduction the users complain about the defects or performance malfunctions of the building. Thermography is one important manual tool in verifying the thermal performance of the building envelope. In this paper the results of one pilot building (a school) will be presented. In surveying the condition and energy efficiency of buildings, various auxiliary means are needed. We can compare the consumption data of the target building with other, same type of buildings by benchmarking. Energy audit helps to localize and determine the energy saving potential. The most general and also most effective auxiliary means in monitoring the thermal performance of building envelopes is an infrared camera. In this presentation some examples of the use of thermography in energy audits are presented.

This research project investigated heat transfer mechanisms that occur during radiant heating of glass/epoxy composites bonded to concrete. The ultimate goal is to develop a field procedure for estimating the thickness of fiber-reinforced polymer (FRP) composites used to strengthen existing reinforced concrete structures. Thickness is an important parameter in the design and implementation of nondestructive testing procedures that evaluate bond in FRP systems. Four concrete samples (15 cm x 30 cm x 5 cm) were constructed with glass/epoxy composite bonded to the surface. The thickness of the composite varied from 1mm to 4mm and thermocouples were placed at 1mm intervals through the depth of the composite. Experimental data was compared with a simple theoretical model that predicts the surface temperature response of a layered system subjected to a uniform heat flux. Two factors were shown to significantly influence the heat transfer mechanism: surface absorptivity of the FRP composite and convective cooling. Additional analytical modeling using the finite element method was performed to account for these affects in an effort to obtain a better estimate of FRP thickness based on experimental data.

NdT methods are highly promoted by an increasing demand of checking the effectiveness of strengthening and repair intervention on structural components, both in buildings and bridges. IR thermography exhibits excellent performances, particularly when innovative materials as CFRP (Carbon Fiber Reinforced Polymer) are used. Non destructive control by the use of thermographic analysis is used to detect adhesion defects or imperfections, which can lead the component to become brittle and collapsing unexpectedly. This paper shows as the geometrical evaluation of delaminated areas is carried out. Laboratory tests both on reduced or full scale are illustrated in order to set up and validate the proposed procedure. An experimental study on samples bonded with FRP and containing defects appropriately applied at the interface, will be presented. A series of beams (10 m long) have been tested under bending loads and strengthened conditions, by placing a pre-impregnated thin carbon (CFRP) laminate at the intrados. Different reinforcement configurations have been adopted in the beams (ordinary steel reinforcement and with addition of pre-stressed strands), using mechanical devices for the anchorage of the supplementary pre-tension of the strips. At local level, the simulation of possible lack of bonding during loading or intrinsic defects and imperfections has been contextually analysed on specifically dimensioned specimens. Different algorithms have been applied at the evaluation stage in order to estimate the defect size and location. Particularly, the extension of the delamination is estimate with a simple and robust algorithm. In facts, standards set the limit for acceptable defects, both in terms of number and size.

The paper describes theoretical and experimental results of the inspection of 5 mm- and 15 mm-thick filament wound CFRP shell samples containing Teflon inserts as defect surrogates. Heating was accomplished with a 30 kW tubular quartz lamp heater which provided up to 14 kW/m2 of absorbed power. Thermal properties of the samples were evaluated including the analysis of diffusivity anisotropy. Both one- and two-sided test procedures were comparatively investigated to illustrate difficulties which appeared in the inspection of thick composites.

Thermal response spectroscopy method was newly developed for quantitative measurement of size and depth of the defects. In this method, sequential thermal response data observed on the surface of objective body under active step heating were processed by lock-in analysis scheme based on the Fourier series expansion, in which Fourier coefficients synchronizing with sine and cosine waves were calculated. Phase and amplitude were calculated using these coefficients for different thermal fluctuation periods and different defect parameters, such as size and depth of the defects. Obtained phase and amplitude were represented in spectroscopic diagram. It was found that plotted phase and amplitude data of certain defect depth obtained for various thermal fluctuation periods showed characteristic curves in the diagram. An inverse analysis method for the thermal response spectroscopy was proposed for quantitative measurement of size and depth of the defects. The least-squares residual inverse analysis scheme was applied to the defect parameter determination based on the Fourier coefficient values in the spectroscopic diagram. It was found that defect depth and size can be quantitatively determined by the inverse analyses.

The Infrared Nondestructive Testing (IRNT) methods based on thermal contrast are strongly affected by non-uniform heating at the surface. Hence, the results obtained from these methods considerably depend on the chosen reference point. One of these methods is Artificial Neural Networks (ANN) that uses thermal contrast curves as input data for training and test in order to detect and estimate defect depth. The Differential Absolute Contrast (DAC) has been successfully used as an alternative thermal contrast to eliminate the need of a reference point by defining the thermal contrast with respect to an ideal sound area. The DAC technique has been proven effective to inspect materials at early times since it is based on the 1D solution of the Fourier equation. A modified DAC version using thermal quadrupoles explicitly includes the sample thickness in the solution, extending in this way the range of validity when the heat front approaches the sample rear face. We propose to use ANN to detect and quantify defects in composite materials using data extracted from the modified DAC with thermal quadrupoles in order to decrease the non-uniform heating and plate shape impact on the inspection.

The paper describes an IR thermographic inspection system used for detecting hidden defects in operating cylindrical kilns widely used in cement production industry. The accent is done on the description of the identification algorithm which is based on the proposed thermal model of kiln operation.

Thermographic data can be used as a supplement to aircraft maintenance operations in both back shop and flight line situations. Aircraft systems such as electrical, propulsion, environmental, pitot static and hydraulic/pneumatic fluid, can be inspected using a thermal infrared (IR) imager. Aircraft systems utilize electro-hydraulic, electro-mechanical, and electro-pneumatic mechanisms, which, if accessible, can be diagnosed for faults using infrared technology. Since thermographs are images of heat, rather than light, the measurement principle is based on the fact that any physical object (radiating energy at infrared wavelengths within the IR portion of the electro-magnetic spectrum), can be imaged with infrared imaging equipment. All aircraft systems being tested with infrared are required to be energized for troubleshooting, so that valuable baseline data from fully operational aircraft can be collected, archived and referenced for future comparisons.

This research investigated low velocity impact damage in fiber-reinforced polymer (FRP) composites. Small-scale glass/epoxy laminates (approximately 210mm x 210mm x 2mm) were subjected to varying degrees of dynamic impact energies ranging from 5 to 20 J and infrared thermography inspections were performed on the damaged specimens. Three distinct damage modes were observed: penetration resulting in highly localized fiber rupture through the thickness of the composite; penetration/delamination in which localized fiber rupture was observed on the impacted surface and additional delamination occurred around the point of impact; and delamination/reverse side fiber rupture in which no visible damage occurred on the impacted surface but fiber rupture and delamination occurred beneath the surface. A modified lock-in thermography procedure was used in the nondestructive evaluation (NDE). Phase images were constructed by applying a least-squares sinusoidal curve fit to a series of thermal images collected over one cycle of sinusoidal heating. This method was shown to increase contrast for subsurface delaminations compared to raw thermal data. Finally, thermography results for FRP composite samples containing simulated damage (back-drilled holes) were compared with thermography results from impact-damaged samples.

For thermo-inductive crack detection, a metallic work-piece is placed in a high frequency magnetic field which induces eddy currents in a very thin layer of the surface. This eddy current heats up the sample and the emitted infrared radiation is viewed by an infrared sensitive camera. An inhomogeneous temperature distribution on the surface corresponds to inhomogeneities and cracks in the material. The main goal of the thermo-inductive crack detection is on the one side to find cracks and on the other side to determine their depths. For this purpose an examination of all parameters affecting the result of the measurements has to be made. In previous publications it has been shown how the thermal quotient Tcrack/Tsurf depends on several parameters (i.e.: time, pulse length, penetration depth of the eddy current and crack depth). All these investigations were made for rectangular shaped cracks. But metallographic cross-sections show that real cracks have different shapes and different angles depending on the circumstances of the origin of the crack. In this paper results of finite element simulations are presented demonstrating what kind of influence the different shapes have to the thermal contrast. It is also shown in which way the crack geometry affects the temperature distribution on the crack near surface. The calculations take into consideration the distribution of the eddy currents around the crack for both magnetic and non-magnetic materials. The simulations are based on coupled modeling of magnetic and thermal phenomena. The calculated results are in very good agreement with the measurements.

While other non-destructive testing methods hardly reveal microscopic open cracks, ultrasound excited vibrothermography provides very promising results by converting mechanical waves into local heat by friction. This phenomenon enhances thermal gradients in temperature maps as compared to conventional techniques. To detect temperature gradients caused by hidden cracks, high temperature and spatial resolution infrared cameras are usually used. Recently, it has been shown that the HVOF (High Velocity Oxy Fuel)-spraying of tungsten carbide or cobalt coatings onto steel substrates, seems to be a suitable alternative to the non-environmentally friendly chromium coating material. However one major issue with these thermal-sprayed coatings is the possibility of the appearance of microscopic cracks when they are submitted to excessive bending loads. If the open cracks spread through the whole coating thickness (typically 100 to 200 ?m), they might also propagate at the coating-substrate interface causing the coating to delaminate in between adjacent open cracks. The latter disbonding phenomenon is therefore strongly dependent on the distance between adjacent open cracks. Therefore, a non destructive technique enabling the detection of cracks and the evolution of their density is critical to preserve the components integrity. The aim of this work is to investigate the ability of ultrasound excited vibrothermography to detect such cracks. To do so, we investigated tungsten carbide coatings where cracks were artificially generated using a controlled bending test. Results on different samples are presented and discussed.

The introduction of arc and laser welding in the aerospace, automotive and nuclear sectors, among others, has led to a great effort in research concerning quality assurance of these processes. Hence, an on-line, real-time welding monitor system able to detect instabilities affecting the welding quality would be of great interest, as it would allow to reduce the use of off-line inspection techniques, some of them by means of destructive-testing evaluation, improving process productivity. Among several different approaches, plasma optical spectroscopy has proved to be a feasible solution for the on-line detection of weld defects. However, the direct interpretation of the results offered by this technique can be difficult. Therefore, Artificial Neural Networks (ANN), due to their ability to handle non-linearity, is a highly suitable solution to identify and detect disturbances along the seam. In this paper plasma spectra captured during welding tests are compressed by means of Principal Component Analysis (PCA) and, then, processed in a back propagation ANN. Experimental tests performed on stainless steel plates show the feasibility of the proposed solution to be implemented as an on-line arc-welding quality monitor system.

This paper highlights the modeling, simulation and detection of deposited scales in boiler tubes by Pulsed Thermography (PT). A novel data analysis method, based on variations of slopes in Temperature-Time profiles approach has been adopted, to estimate subsurface scale thickness and material loss in the tubes. The slopes are obtained for different pixels in the field of view of the captured image sequence during transient heating of the boiler tube. Relative thickness variations due to material loss and the deposited scales of boiler tube have been estimated from the calculated slopes. Experimental results are presented in support.

Infrared thermography is a condition monitoring technique that, from a measurement of the radiant heat pattern emitted by a material, is able to determine regions or points, of increased or reduced heat emission that can indicate the presence of an imperfection in the investigated material. Thermographic approaches, passive and active, are widely used due to the outstanding advantages that offer in a number of applications and particularly for the assessment of materials. Nonetheless, there are limitations; depending upon the approach used, as well as on the materials thermal, optical and physical properties, proper assessment (detection and/or quantification) is feasible. Different applications, employing either passive or transient thermographic testing, concerning the assessment of various materials are presented.

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.

Fatigue damage of unalloyed steels in the high cycle regime is governed by localized cyclic plastic deformations and subsequent crack initiation. The extent of early microplastic deformations depends on the applied stress level, stress concentration at macroscopic notches, surface treatment, residual stresses etc. The onset of a nonlinear material response can be regarded as an early indicator of fatigue damage. During fatigue loading thermoelastic coupling and thermoplastic dissipation cause characteristic temperature variations in tested specimens which have been assessed by a highly sensitive infrared camera. A specialized data processing method in the time domain has been developed which allows to separate the different contributions to the measured temperature signal. In contrast to other methods - as e.g. measuring the rise of mean temperature during fatigue loading - the proposed methodology is based on measurements during the stabilized temperature regimen and offers very high spatial resolution of localized phenomena. Investigations have been made on mildly notched cylindrical and also on welded specimens. The results confirm the close relation between the local temperature signal and typical fatigue phenomena. The new methodology allows for a much better localization and quantification of effects as cyclic plasticity, crack initiation, crack growth etc. The following paper presents considerations and experimental results of an application of thermography to the local assessment of fatigue damage.

The gases accumulated inside the landfill as result of the fermentation of Municipal Solid Waste (MSW) known as biogas, are taking into consideration all possible uses as direct transformation into electricity. The system for collecting, regulating and controlling the biogas must include all the necessary safety features where the biogas leakage presents a high impact. Infrared thermography can be use to detect gas leakages due to the differences in temperature between the gas and the immediate surroundings. This method is able to monitor a wide area of landfill sites, quickly. This technology will not be effective if the differences in temperature are not better than five degrees. This paper describes a field test conducted to study the limitations of the infrared thermography caused by weather conditions and the moment of day or/and season when the thermal images was captured. Pipelines, borders, cells, covers, slopes and leakage (hot spots) are studied and optimum conditions are defined.