This PDF file contains the front matter associated with SPIE Proceedings Volume 7299, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Thermal imagers are often used under ambient conditions, which differ significantly from the calibration conditions. In this paper a method for characterization of thermal imagers under various ambient conditions is described in the ambient temperature range from -10 °C to +23 °C. A flat-plate blackbody source attached to a climatic chamber has been used to simulate the measurement conditions corresponding to the use of the imagers in thermography of buildings. The lower temperature limit has been selected based on typical field measurement conditions in the Nordic regions while the upper limit is a typical laboratory temperature during the calibration of the instruments. Correction factors of more than 1 K relative to the calibration at the laboratory conditions have been observed at lower temperatures with a high-quality imager under test. Analysis of the measurement results with corresponding uncertainty estimation is described. The expanded uncertainty (k = 2) of the correction factor has been estimated to be 0.4 K.

Scene-Based Non-Uniformity Correction (SBNUC) is an attractive alternative to radiometric calibration for infrared sensors because it does not rely on specialized hardware. The best known approach is Constant Statistics (CS) but it is highly dependant on scene content and the amount of motion present, often introducing a "ghosting" artifact. In this paper, we present a novel approach which applies a variation on CS to both the spatial and frequency domains of the image. The result is a solution which effectively eliminates fixed pattern noise without ghosting and is much less dependant scene content and scene motion than traditional CS.

The proton beam passing through the wall area of a liquid metal (LM) target container, called entrance window, is causing deposition of maximum high heat flux amount 140 W/cm².Previous experimental thermo-hydraulics investigations for the MEGAPIE LM-target at the SINQ facility of Heat- Transfer-Coefficient (HTC) using InfraRed-Thermography (IRT) have been presented at Thermosense 2006 and 2007 [1], [2] and references therein. During these investigations the IRT active sensors with applied heat fluxes of the small and low range from 2.5 to 15.2 W/cm² are used. The heating shell foil of the sensor has been connected to steel dish enclosing LM target container by using electrical insulation ceramic glue. A higher, then achieved 15 W/cm², heat flux has lead to delaminating of the heater. Because of interest to determinate the HTC-chart under real heat flux conditions and investigate some positive effect of heat flux buoyancy on cooling, the idea for the High Heat Flux (HHF) IRT Sensors, using of the Low Pressure Plasma Spraying - Thin Film (LPPS-TF) technology of the Sulzer Metco Company has been created. The paper presents the idea of multilayer thermal sprayed construction of HHF-IRT-Sensor, few realizations and some results of the first pre-test performed at the PSI LBE Double Pump Loop using the new sensor and the 2DD IRT methodology presented in [1].

Smoking is the most significant source of preventable morbidity and premature mortality worldwide (WHO-2008). One of the many effects of nicotine is vasoconstriction which is triggered by the autonomic nervous system. The constriction of blood vessels e.g. of the skin's vascular bed is responsible for a decrease of the supply with oxygen and nutrients and a lowering of the skin temperature. We used infrared imaging to quantify temperature decreases caused by cigarette smoking in the extremities of smokers and also monitored heart rate as well as blood pressure. The results - including thermograms showing "temporary amputations" of the fingertips due to a significant temperature drop - can help increase the awareness of the dangers of smoking and the success of withdrawal programs. Surprisingly, in our control persons (3 brave non-smoking volunteers who smoked a cigarette) we also found temperature increases suggesting that vasodilation (widening of blood vessels) was provoked by cigarettes. To verify this unexpected finding and eliminate effects from the 4000 chemical compounds in the smoke, we repeated the experiment following a stringent protocol ruling out physiological and psychological influences with 9 habitual smokers and 17 nonsmokers who all chew gums with 2 mg of nicotine. Task-optimized digital image processing techniques (target detection, image-registration and -segmentation) were applied to the acquired infrared image sequences to automatically yield temperature plots of the fingers and palm. In this paper we present the results of our study in detail and show that smokers and non-smokers respond differently to the administration of nicotine.

This paper studies the use of a combination of Haar-like features and a cascade of boosted tree classifiers embedded in a widely used OpenCV for face detection in thermal images. With 2013 positive and 2020 negative 320×240-pixel thermal images for 20 training stages on three window sizes of 20×20, 24×24, and 30×30 pixels, our experiment shows that these three windows offer similar hit and false alarm rates at the end of the training section. Larger windows also spend much more time to train. During our testing, the 30×30-pixel window provides measured best hit and false rejection/acceptation rates of 93.4% and 6.6%, respectively, with a measured slowest detection speed of 19.6 ms. A 5-ms improvement in the measured detection speed with a slightly lower hit rate of 92.1% is accomplished by using the 24×24-pixel window. These results verify that the combination of Haar-like features and a cascade of boosted tree classifiers is a promising technique for face detection application in thermal images.

EPBD-directive has taken into the use in European Union Countries. In Finland, in connection with the directive and with harmonization of building codes, the building codes dealing with insulation and energy use has been renewed. At the first time there is a requirement of energy efficiency calculations. Energy efficiency is connected with energy labeling. Also first time there are now prerequisites for air tightness of buildings. These new challenges have created a boom of increased quality control needs in construction companies, including different verification methods. The use of thermography and air-tightness test (blower door tests) has been exploited by increasing speed. The interpretation of result will be a growing problem, even lot of work has been done e.g. in certification procedure of building thermographers. In this presentation some results of multi-storey apartment houses and other targets will be presented, and discussion about the problems which may occur in the future.

Determining the internal temperature of a mechanical draft cooling tower (MDCT) from remotely-sensed thermal imagery is important for many applications that provide input to energy-related process models. The problem of determining the temperature of a MDCT is unique due to the geometry of the tower and due to the exhausted water vapor plume. The radiance leaving the tower is dependent on the optical and thermal properties of the tower materials (i.e., emissivity, BRDF, temperature, etc.) and also the internal geometry of the tower. The tower radiance is then propagated through the exhaust plume and through the atmosphere to arrive at the sensor. The expelled effluent from the tower consists of a warm plume with a higher water vapor concentration than the ambient atmosphere. Given that a thermal image has been atmospherically compensated, the remaining sources of error in extracted tower temperature due to the exhausted plume and the tower geometry must be accounted for. A temperature correction factor due to these error sources will be derived through the use of three-dimensional radiometric modeling. A range of values for each important parameter are modeled to create a target space (i.e., look-up table) that predicts the internal MDCT temperature for every combination of parameter values. This LUT, along with user knowledge of the scene, provides a means to convert the imagederived apparent temperature into the estimated absolute temperature of a MDCT. Preliminary results indicate that temperature error corrections of approximately 1 - 9 Kelvin can be achieved with the range of MDCT parameters encompassed by the LUT.

The Savannah River National Laboratory (SRNL) collected thermal imagery and ground truth data at two commercial power plant cooling lakes to investigate the applicability of laboratory empirical correlations between surface heat flux and wind speed, and statistics derived from thermal imagery. SRNL demonstrated in a previous paper [1] that a linear relationship exists between the standard deviation of image temperature and surface heat flux. In this paper, SRNL will show that the skewness of the temperature distribution derived from cooling lake thermal images correlates with instantaneous wind speed measured at the same location. SRNL collected thermal imagery, surface meteorology and water temperatures from helicopters and boats at the Comanche Peak and H. B. Robinson nuclear power plant cooling lakes. SRNL found that decreasing skewness correlated with increasing wind speed, as was the case for the laboratory experiments. Simple linear and orthogonal regression models both explained about 50% of the variance in the skewness - wind speed plots. A nonlinear (logistic) regression model produced a better fit to the data, apparently because the thermal convection and resulting skewness are related to wind speed in a highly nonlinear way in nearly calm and in windy conditions.

The effectiveness of a power generation site's cooling pond has a significant impact on the overall efficiency of a power plant. The ability to monitor a cooling pond using thermal remote sensing, coupled with hydrodynamic models, is a valuable tool for determining the driving characteristics of a cooling system. However, the thermodynamic analysis of a cooling lake can become significantly more complex when a power generation site is located in a northern climate. The heated effluent from a power plant entering a cooling lake is often not enough to keep a lake from freezing during winter months. Once the lake is partially or fully frozen, the predictive capabilities of the hydrodynamic model are weakened due to an insulating surface layer of ice and snow. Thermal imagery of a cooling pond was collected over a period of approximately 16 weeks in tandem with high-density thermal measurements both in open water and embedded in ice, meteorological data, and snow layer characterization data. The proposed research presents a method to employ thermal imagery to improve the performance of a 3-D hydrodynamic model of a power plant cooling pond in the presence of ice and snow.

Conservation of buildings in areas at seismic risk must take prevention into account. The safeguard architectonic heritage is an ambitious objective, but a priority for planning programmes at varying levels of decision making. Preservation and restoration activities must be optimized to cover a vast and widespread historical and architectonic heritage present in many countries. Masonry buildings requires an adequate level of knowledge based on the importance of structural geometry, which may include the damage, details of construction and properties of materials. For identification and classification of masonry is necessary to find shape, type and size of the elements, texture, size of mortar joints, assemblage. The recognition can be done through a visual inspection of the surface of walls, which can be examined, where is not visible, removing a layer of plaster. Thermography is an excellent tool for a fast survey and collection of vital information for this purpose, but it is extremely important define a precise procedure in the development of more efficient monitoring tools. Thermography is a non-destructive method that allows recognizing the structural damage below plaster, detecting the presence of discontinuity in masonry, for added storeys, cavity, filled openings, and repairs. Furthermore, the fast identification of subsurface state allows to select areas where other methods either more penetrating or partially destructive have to be applied. The paper reports experimental results achieved in the mainframe of the European project RECES Modiquus. The main aim of the project is to improve methods, techniques and instruments for facing antiseismic options. Both passive and active thermographic techniques have been applied in different weather conditions and time schemes. A dedicated algorithm has been developed to enhance the visibility of wall bonding.

A novel dual-band infrared computed tomography method is described. It applies thermal inertia imaging to detect temporal heat flows from naturally-heated underground or faulty structures. The added values over earlier methods are the use of a temperature simulation model and clutter removal algorithms. They save time, clarify interpretation and specify the subsurface object location, orientation, depth, height (or thickness) and volume. Previous methods incorporated in the methodology successfully viewed a 6-60 m deep aquifer, a 1/10 m³ bridge-deck rut and a 1-15 m deep rock-covered drain. Temporal heat flows were viewed from mobile platforms 3 m to 3 km above ground. Emissivity-corrected thermal survey data agreed with 1-2 m deep thermal-probe and 6-60 m deep thermal-gradient data.

To reduce the size of electronic equipment, multi-layer printed circuit board structures have become popular in recent years. As a result, the inspection of hidden solder joints between layers of boards has become increasingly difficult. Xray machines have been used for ball grid array (BGA) and hidden solder joint inspection; however, the equipment is costly and the inspection process is time consuming. In this paper, we investigate an active thermography approach to probing solder joint geometry. A set of boards having the same number of solder joints and amount of solder paste (0.061 g) was fabricated. Each solder joint had a different geometry. A semi-automated system was built to heat and then transfer each board to a chamber where an infrared camera was used to scan the board as it was cooling down. Two-thirds of the data set was used for model development and one-third was used for model evaluation. Both artificial neural network (ANN) and binary logistic regression models were constructed. Results suggest that solder joints with more surface area cool much faster than those with less surface area. In addition, both modeling approaches are consistent in predicting solder geometry; ANN had 85% accuracy and the regression model had 80%. This approach can potentially be used to test for cold solder joints prior to BGA assembly, since cold solder joints may have air gaps between the joint and the board and air is a poor heat conductor. Therefore, a cold solder joint may have a slower cooling rate than a normal one.

This paper presents the current state of our efforts to increase efficiency of petrochemical plant with using spectral-band dynamic IR radiation thermometry. Depending on the type of investigations i.e. studying tubes' temperature, what is the most typical and important case or studying energetic and dynamic features of the flames and flue gases, different narrow-band optical filters and research procedures have to be applied. To perform both type of these measurements we modernized commercial PtSi FPA camera and software to process various sequences of thermal images. Two of results are highlighted: possibilities to increase tube' temperature measurements confident and reliability due to minimization of errors going from mostly fluctuating reflections of surrounding heat sources and self-emissions of heating medium between tube and camera, as well as a new diagnostic potential of the images of chosen gases features, for comparative investigations in particular. Case histories, some challenges and limitations during elaborated method application have also been addressed.

There are many error sources when using infrared radiation thermography to measure the temperature distribution of the tool, workpiece, and chip during metal cutting. It is important to understand how these error sources affect the measurement uncertainty. Some are familiar to anyone performing thermography measurements, such as uncertainties in the basic camera calibration. However, metal cutting presents unique measurement challenges due to factors such as the high magnification required, high surface speeds, polarization effects, micro-blackbody effects, and changing emissivity as chips form. This paper presents highlights of the current state of efforts at NIST to catalog and characterize error sources and the resulting uncertainties.

We aim to identify humans in multimodal imagery by predicting the human long-wave infrared (LWIR) signature in a variety of scenarios. By adapting Tanabe's thermocomfort model, we simulate human body heat flow both between tissue layers (core, muscle, fat and skin) and between body segments (head, chest, upper arm, etc.). To assess the validity of our implementation, we simulated the conditions described in actual human subject studies, and compared our results to values reported in the literature. Inputs to the model include age, height, weight, clothing, physical activity and ambient conditions, including temperature, humidity and wind velocity. Iteration of heat transport equations and a thermoregulatory component yields temporal data of segment surface temperature. Our model was found to be in close agreement with experimentally collected data, with a maximum deviation from literature values of approximately 0.80%. By comparing the predicted human thermal signature to deblurred LWIR images and then fusing this information at the feature level with high-resolution electro-optical image data, we can facilitate identity detection of objects in a scene acquired under different conditions. Ultimately, our goal is to differentiate humans from their surroundings and label non-human objects as thermal clutter.

At ThermoSense XXX, a series of presentations and subsequent discussions reviewed the status of professionalism and certification among Infrared Thermographers. Since then the Internet has grown rapidly in formation and operation of social networks and several informal, virtual groups of Thermographers have appeared, notably on the social network Linkedin.com. It seems feasible, then, to now consider formation of an International Virtual Professional Association of Thermographers based on Social Networking technologies available on the World Wide Web at very modest cost. This presentation will review some of the benefits and advantages to Thermographers of such technologies and a virtual organization. Access to the free discussions available on this subject at a web log, or Blog, begun in January 2009, www.iThermographer.info, will also be presented.

IR thermography is joined to a simplified thermal model for evaluating thermal performance of insulated containers. The method is illustrated with experimental results obtained into a test tunnel working under controlled environmental conditions. Insulated vehicles are tested in parallel according to the accepted standard "Agreement on the international carriage of perishable foodstuff" (ATP) and the thermographic method. A thermographic apparatus is used to map the temperature of the external walls of the insulated box. Defective zones are identified and the local heat flux mapped basing on a heat flux meter measurement in a reference point and on the thermographic temperature maps. The proposed thermographic method allows also determining thermal bridges magnitude and air leakages location. These results are important in order to enhance manufacture. Some experimental data are presented in order to compare K-values measured along ATP rules and calculated by the thermographic inspection. The comparison allows verifying the accuracy. Such a quality test is particularly useful for periodic control of insulation ageing.

It is known from theory that growing oxide layers on metal surfaces effect interferences of the spectral emissivities. These interferences can strongly change with increasing thickness of the oxide layer, because their maximum and minimum values shift to longer wavelengths and their intensities become larger or smaller. The changes of spectral emissivities also lead to changes of the band-emissivities used as values for emissivity correction of pyrometers or IRcameras. Primarily, these effects depend only on emissivity and can occur without changes of metal's temperature. For the working ranges of the optical temperature instruments follows, that the values of band-emissivities may change constantly with growing oxide layers. This will result in problems for an accurate temperature measurement. At the University of Duisburg-Essen it is now possible to carry out in-situ measurements of the spectral emissivities of growing oxide layers on metals. These investigations can be done under technically relevant conditions of heating time, and temperature. Low alloyed steel with a growing oxide layer was investigated. The steel sample was heated up to 1150°C within a period of 2 minutes and, further, tempered for 1 minute more at this temperature. During this period, the oxide layer was steadily growing and the changes of spectral emissivities were measured at several increments of time. It was found, that the theoretically predicted interference effects, their changes and shifts in the spectral properties are readily seen and could be measured. Results will be presented of the spectral emissivities from 0.7 to 25 μm and of based on it calculated band-emissivities between 0.7 to 4.5 μm, which are in correlation with the working ranges of three chosen pyrometers. Strong and relatively fast changes of the spectral emissivities can be achieved with values between 0.6 and 0.9. Therefore, during the growth of the oxide layer accurate temperature measurements with optical instruments make no sense because of the permanent change in the values of band-emissivities. An exact determination of the temperature under these circumstances is not possible. Only weak influence on the values of band-emissivities were found when correlated with the spectral response functions of the chosen pyrometers.

Fiber-reinforced polymer (FRP) composites are widely used to increase the flexural and shear capacity of reinforced concrete (RC) elements. One potential disadvantage is that strengthened surfaces are no longer visible and cracks or delaminations that result from excessive loading or fatigue may go undetected. This research investigated thermal imaging techniques for monitoring and evaluating load-induced delamination of FRP composites applied to small scale RC beams. Two beams (3.5 in x 4.5 in x 58 in) were loaded monotonically to failure. Infrared thermography (IRT) inspections were performed at various load levels through failure using a composite phase imaging technique. Two similar beams were tested in fatigue and periodic IRT inspections were performed at 50,000-cycle intervals. Individual phase values for each pixel were designated as "well-bonded", "suspect" or "unbonded" to indicate the quality of FRP bond. Suspect areas included regions of excess thickened-epoxy tack-coat and smaller installation defects in the unloaded specimens. The long-term objective of this research is to develop a practical framework for conducting quantitative IRT inspections of FRP composites applied to RC and incorporating these results into acceptance criteria for new installations and predictions for the remaining service life of in-service FRP systems. This method may also offer insight into the necessity for repairs to in-service systems.

The application of a noncontact air coupled acoustic heating technique is investigated for the inspection of advanced honeycomb composite structures. A weakness in the out of plane stiffness of the structure, caused by a delamination or core damage, allows for the coupling of acoustic energy and thus this area will have a higher temperature than the surrounding area. Air coupled acoustic thermography (ACAT) measurements were made on composite sandwich structures with damage and were compared to conventional flash thermography. A vibrating plate model is presented to predict the optimal acoustic source frequency. Improvements to the measurement technique are also discussed.

Although active thermography has traditionally been regarded as a qualitative NDT method, its potential for quantitative measurement of thermophysical properties including wall thickness, flaw size and depth, thermal diffusivity or effusivity has been the subject of numerous investigations. Enabled by improvements in IR camera technology and fast, abundant and inexpensive computing power for advanced signal processing, measurement results have been reported using a variety of excitation and signal processing schemes. Results are often presented as a correlation between thermography data and nominal properties or independent measurements by another "validated" method. However, given the diffusion mechanism that underlies thermography, and the quantization and sampling conditions implicit in using an IR camera as a temperature sensor, there are definite limits to what can be achieved in a thermography measurement. While many benefits can be achieved with improved instrumentation, efficient energy insertion or optimized signal processing, ultimately, the limits imposed by diffusion and instrumentation take precedence, and cannot be circumvented. In this paper, the effects of camera frame rate and sensitivity on measurement of the thickness of a slab are examined, using basic 1-dimensional diffusion approximations.

The automatic detection of subsurface defects has become a desired goal in the application of non-destructive testing and evaluation techniques. In this paper, an algorithm based on the fourth order standardised statistic moment, i.e. kurtosis, is proposed for detection and/or characterization of subsurface defects having a thermal diffusivity either higher or lower than the host material. The analysis of thermographic data for the detection of defects can be reduced to the temporal statistics of the thermographic sequence. The final result provided by this algorithm is an image showing the different defects without the necessity of establishing other evaluating parameters such as the delayed time of the first image or the acquisition frequency in the analysis, which are required in other processing techniques. All the information is contained in a single image allowing to discriminate between the defect types (high o low thermal diffusivity). Synthetic data from Thermocalc® and experimental works using a Plexiglas^TM specimen were performed showing good agreement. Processed results using synthetic and experimental data with other methods used in the field of thermography for defect detection and/or characterization are provided as well for comparison.

Super-resolution techniques were applied to infrared thermographic temperature measurement for the improvement of spatial resolution of the infrared image with limited number of imaging pixels. In the proposed super-resolution technique, a high resolution image was produced from plural low resolution images with sub-pixel displacements. The super-resolution scheme was developed based on the displacement analyses in the sub-pixel level for low resolution images based on the image correlation and subsequent interpolative reassignment of the pixel values from low resolution images to the high resolution image. The practicability of the developed super-resolution infrared thermography was experimentally demonstrated.

The modified DAC version with thermal quadrupoles can be considered an interesting alternative to thermal contrast computations since it provides an automated tool for depth retrieval and eliminates the need of selecting a non-defective area. In practice it is important to have heat stimulus with complex shapes and long durations (several seconds) in order to cover larger inspection areas, enhance thermal contrast between defective and sound areas and increase the depth of inspection inside the material. In this work we present a heat stimulus correction by using the thermal quadrupoles theory and its validation with several heat stimulus shapes and durations.

Thermo-inductive investigations can be well used for the detection of surface cracks in metallic materials. The workpiece is heated by a short inductive pulse and an infrared camera is recording the temperature distribution of the surface. Irregularities and failures in the surface cause anomalies in the temperature distribution, making the failures visible and detectable in the infrared images. Results of experiments show that magnetic and non-magnetic materials have very different behavior: surface cracks in magnetic materials are heated stronger than the failure-free surface. On the other hand, in non-magnetic materials cracks are less heated than the surface itself and become visible through lower temperature values. These different behaviors can be well explained by the different penetration depth of the eddy current, mainly influenced by the magnetic permeability of the material. Model calculations have been carried out in order to describe the distribution of the eddy current around a surface crack and to calculate the resulting temperature profile around it. The time-dependent evaluation of the temperature changes provides results which are independent of the emissivity differences and therefore shows also very well-defined results in the case of grinded or scratched surfaces. This technique has been used for a couple of different work-pieces presenting its advantages. The experimental and calculated results are compared, showing a very good agreement.

Penetrated water in the composite sandwich structures has caused problems in aircraft structures. Flight surfaces have been lost during the flights, because moisture corrodes the honeycomb and further reduces the strength of the adhesive. Water can also cause additional defects during the composite repairs, which have resulted because of the expansion of the moisture (in closed cavity), hence causing skin blow core phenomena during the curing cycle (heating) of the repair. Thermographic investigation is done to find a suitable procedure to find penetrated water from the composite aircraft structures by cooling the whole structure, or separated parts of the aircraft, under freezing conditions. Thermographic inspection based on the phase transition of water exploits the phase transition energy that is needed for the water defrosting (melting). Advantage of this method is that no additional excitation source is needed for the tests. Method based on phase transition can be especially exploited during the long period of arctic weather conditions in Finland and other cold areas. Aircraft can be either inspected right after a flight, or it can be left outside in freezing conditions overnight and inspected when it has been brought in to the maintenance hall to warm conditions.

Infrared thermal imaging method was applied for the development of a non-destructive inspection technique to determine the quality of resistance spot welds. The current work is an initial feasibility study based on post-mortem inspection. First, resistance spot welds were fabricated on dual phase steel sheets (DP 590 steel) with carefullycontrolled welding parameters. It created welds with desirable and undesirable qualities in terms of nugget size, indentation depth, and voids and cracks. Second, five different heating and cooling methods were evaluated. The heating or cooling source was applied on one side of the weld stack while the surface temperature change on the other side of the weld was recorded using an infrared camera. Correlation between the weld quality and the "thermal signature" of each weld was established. Finally, a simplified thermal finite element analysis was developed to simulate the heat flow during inspection. The thermal model provided insight into the effect of the nugget size and indentation depth on the peak temperature and heating rate. The results reported in this work indicate that the IR thermography technique is feasible for weld quality inspection due to the distinguish temperature profiles for different welds and the repeatability and consistency in measurement.