The Low Income Weatherization Assistance Program (W.A.P.) provides weatherization services to low income home owners and tenants throughout the United States to help them reduce domestic energy consumption. During the early years of the program infrared thermography played a small but vital role, primarily as a research and development tool. In the past four years, however, programs in nearly 50% of the states have invested in over 75 units of thermographic equipment and training. This second round of interest in thermography has been prompted by the dual needs of monitoring current work and improving future work through increased training. Although little hard data exists to document the return on this recent investment, this survey of weatherization programs around the country indicates that programs with strong administrative support which also invested in both appropriate equipment and on-going user training are making substantial and cost effective improvements in their programs. It appears thermography will continue to make strong and increasingly greater contributions to improving the quality of the weatherzation program in the years to come.

When using aerial thermography to indicate energy-related conditions of buildings in a large investigation area the question arises how to store and present the final product of classified, energy-related data. A full scale study of 7000 buildings demonstrated the need fur computerbased systems and cartographic methods to store, to arrange and to illustrate thermograpic data. A data base was created including aerial thermograpic data, technical data on the buildings and information on energy consumption of each building. The data base consisted of 100 variables. The key-code for the data base was the real estate name and number. The position of each building was given in terms of coordinates of the real estate. The main purpose of the study was to create an energy-related data base to be used for assigning a priority to measurements within the local energy conservation program. The thermographic data was collected with a longwave airborne infrared line-scanner (3-14 um). The technical data on the buildings and their energy consumption were gathered from existing data bases and from field investigations. Thermograpic data, technical data of the buildings and information on energy consumption was classified and different symbols were used to identify the classes presented on thematic maps. Results from this study implies that computerbased cartography is a favorable method to present and illustrate thermographic information on buildings in large investigation areas. The paper deals mainly with the aspect of carthography for presentation of thermographic and energy-related data.

Public Works Canada carried out a program of tests to record the effects of different stable environmental conditions on a typical light frame wall under laboratory conditions. This test wall had specific built-in defects inherent to this wall type. The operating capabilities of the environmental chamber and the infrared imaging equipment were also checked. Testing took place at a single interior temperature and at seven exterior temperatures ranging from 31oC to -39oC. Three pressure differences (negative 20 Pa, neutral and positive 50 Pa interior to exterior) were produced to accentuate infiltration and exfiltration at each exterior temperature level. Both long wave and short wave infrared imagery were digitally recorded from both the interior and exterior chambers. Imagery obtained indicated light weight frame construction is better viewed from the interior. Temperature differences across the wall greater than 20oC produced the best infrared images. Exterior scanning during temperatures lower than -20oC was not recommended due to equipment operational inconsistencies. Data collected from both interior and exterior chambers indicated that changes in pressurization had the most pronounced effect on infrared imagery. This factor has the most far reaching implications to building science investigators employing infrared imagers as part of their diagnostic analysis of building envelopes. This paper deals with the effects pressure differences have on thermal images of building envelopes and the importance of this factor to building science investigators.

ASTM Standard D4788, "Test Method for Detecting Delaminations in Bridge Decks Using Infrared Thermometry", is a newly approved standard dealing with a unique new application for remote sensing. This paper reviews the standard and describes the major attributes of the ASTM organization.

Within the capital city region of New Jersey are a total of five State office buildings which have undergone infrared thermographic building diagnostics. All of the office buildings were newly constructed for the specific use of the State of New Jersey. The thermographic inspections stem from questions involving the thermal integrity of new construction. The buildings are of various construction materials and techniques including curtain wall, brick face and precast concrete panel. All but one are on the city's district heating system, which serves a number of State buildings in downtown Trenton. The State has found infrared thermographic building diagnostics to be very useful in locating thermal anomalies associated with a building's thermal envelope. Other testing methods, such as calorimeter boxes and heat flow meters, are necessary in order to achieve a complete diagnosis of a building's thermal envelope. In-situ R-values are of great concern for energy efficiency and future design. With the information from the original five infrared thermographic building diagnostic reports, plus other reports of before and after tests, the State has collected a variety of report presentations. By comparing the various styles and information presented, the State of New Jersey has determined a need for better specifications in contracting infra-red thermographic services.

Since November of 1985, FOAM-TECH, INC. has been utilizing an I.S.I. Model 91 Videotherm Camera to quality control the installation of foamed in-place polyurethane and polyisocyanurate insulation. Monitoring the injection of foam into the walls and roofs of new construction and during the the retrofitting of older buildings has become an integral and routine step in daily operations. The Videotherm is also used to monitor the injection of foam into hot water tanks, trailer bodies for refrigeration trucks, and pontoons and buoys for flotation. The camera is also used for the detection of heat loss and air infiltration for conventionally insulated buildings. Appendix A are thermograms of foamed in-place insulation.

Damages on the insulation of roof systems has consequences for the performance of the roof system and the energy cost. An early detection of roof thermal anomalies may greatly reduce long-term maintenance costs. Airborne thermographic methods have for several years with success been applied to detect thermal anomalies of roof systems. For ventilated attics, the surface temperature pattern of the attic insulation can not always be inferred from a measurement of the surface temperature due to the influence of thermal properties of the roof system and to weather conditions. In this paper is presented a calculation of how the surface temperature pattern of the insulation influences the surface temperature pattern of a flat roof when part of the insulation is not functioning properly due to, for example, wettening of the material. The results are presented for various attic geometries, amount of convective heat transfer from the insulation to the attic air for different wind speeds, for various internal-external temperature differences, and for different emissivities of the roofing material.

This paper highlights important applications of thermography, the reasons behind its use, and the limitations and realities in performing the technique. It also defines how its rationale and application in nuclear power stations differ from those outside the industry.

The inclusion of infrared imaging into the Predictive Maintenance Program at the Davis-Besse Nuclear Power Station has led to a program that may assist other nuclear sites in implementing an infrared (IR) program for Predictive Maintenance. The nuclear industry is using various forms of IR technology for troubleshooting and preventive maintenance at many sites. The ease of producing and analyzing a thermogram (from either a video tape or a computer digital file) provides the basis for data trending and documentation to support a predictive program.

Electrical arc events on electrical contacts and electrical faults are of interest to researchers interested in contact design, behavior and safety. Several arc event thermograms were recorded and analyzed. This preliminary research indicates the usefulness of the infrared scanner in assessing arc shape, metal removal and heat transfer from the event.

This work examines automation of fault detection in infrared images of power transmission lines. Several levels of processing for semi- and full automation of the task are proposed and the first processing level is implemented. A global adaptive thresholding technique which adapts to each new tape is used for the real-time detection of potential fault spots in the taped imagery. Timing considerations for fault detection and image saving are discussed and the impact of hot background objects on the system performance is explained.

In this paper we report our experience using infrared imaging systems to monitor temperature variations in aluminum strip during hot rolling. Because of the low emissivity of aluminum surfaces infrared cameras are sensitive not only to temperature variations in the strip, but also to changes in surface characteristics caused by changes in alloy and surface roughness. In the system described in this paper, process information from the mill control computer is used to automatically select emissivity factors from a lookup table. A second technique for adjusting emissivity factors, using reference point temperatures measured by a separate sensor will also be described. Results from tests, comparing temperatures measured by infrared imaging systems with contact temperature probes indicate good agreement between the two techniques at later stages in the hot rolling process, when surface emissivity is uniform. Factors affecting the installation of a thermal imaging system on a production line, in particular the location of the camera and integration with other temperature measurement systems, are also discussed.

This paper describes the development of an adaptive control scheme for automated laser fusion welding applications, based on a software module capable of quickly recognizing weld cavity features indicated by sensor data without need for computation. Sensor data arrives to system in a high bandwidth stream, necessitating a quick recognition method in order to attain real time control. The method achieves speed through rigorous offline work within the actual system development. An iterative training procedure is exeuted in order to produce a software module capable of reliably recognizing prescribed weld puddle conditions within complex sensor data. The system is trained to mimic the classifications made by a metallurgical engineer between infrared sensor status and defect presence. Research will thereby attempt to automate existing metallurgical engineering knowledge relating causal relationships between particular states of sensor parameters and a limited set of defect types. The ability of these relationships to support a viable industrial control scheme will be assessed. Also, the required performance (speed, reliability) of the controllers primary component (the neural network) will be assessed. Research leaves the development of a computed reaction to such assessed condition to other research (some of which has been performed earlier at IITRI)

A passive instrument for on-line measuring hot rolling steel bar has been developed. The instrument uses self emission of the hot steel bar to deside the profile of working piece. The instrument can measure the dimensions of the cross section of the high speed and high temperature steel bar on the production line. It can be used for real-time monitoring, evaluating, and controlling the quality of the products. Compared with other similar instrument, new instrument has following features: - Passive measurement for simplifying the structure; - Simultaneous dimension and position measurement for ensuring high accuracy; - Temperature measurement for compensating thermal error; - Solid state sensor array for raising reliability; - Special structure for running in hostile enviornment; All these features make it possible to realize accurate measurement in high temperature, high humidity, and high dusty circumstance. The paper will present and discuss relative problems in the design and construction of this instrument. A prototype has been made and a series analogue experiments have been carried out in the laboratory. Rolling shop running test approves that the instrument can accurately measure the hot rolling steel bar on the production line. The total error is less than 0.05 mm while the measuring rate is as high as 2000 samples per second.

This paper deals with the application of infrared imaging radiometry as a diagnostic inspection tool for locating a concealed leak in the refrigeration system supplying glycol coolant to the arena floor of an ice skating rink in a municipal coliseum facility. Scanning approximately 10 miles of black iron tubing embedded in the arena floor resulted in locating a leak within the supply/return side of the system. A secondary disclosure was a restriction to normal coolant flow in some delivery loops caused by sludge build-up. Specific inspection procedures were established to enhance temperature differentials suitable for good thermal imaging. One procedure utilized the temperature and pressure of the city water supply; a second the availability of 130F hot water from the facility's boiler system; and a third the building's own internal ambient temperature. Destructive testing and other data collection equipment confirmed the thermographic findings revealing a section of corrosion damaged pipe. Repair and flushing of the system was quickly completed with a minimum of construction costs and inconvenience. No financial losses were incurred due to the interruption of scheduled revenue events. Probable cause for the shutdown condition was attributed to a flawed installation decision made 15 years earlier during the initial construction stage.

The complexity of an average electronic circuit pack in industry today has increased immensely in the last several years. The use of surface-mounted devices (SMD) and multilayer circuit packs are the rule, rather than the exception. This acceleration in circuit pack complexity has driven the need for better circuit pack testing. Improvements in design for test (DFT), built-in self-test (BIST), and in-circuit test (ICT) have all contributed to higher yields of electronic circuit packs at the stage where they are first tested following assembly. The percentage of packs to be analyzed is dropping rapidly. Conversely, the task of locating the fault on the population of circuit packs which do have short circuits at this stage has become correspondingly more difficult. In addition, the density of components on the circuit packs has made it more attractive to troubleshoot rather than junk these circuit packs. A technique utilizing computerized color thermography (CCT) has been adopted to physically locate short circuits on these circuit packs. This paper deals with the practical use of CCT at a facility which manufactures and tests populated electronic circuit packs.

There is little in the way of standards for thermographic maintenance inspections. Quality of resulting data has varied from exceptional to uselessl. This paper outlines the necessary ingredients for useful predictive maintenance inspections.

This paper describes a novel approach for rapid, quantitative measurement of spatially distributed heat flux incident on a plane. The technique utilizes the spatial temperature distribution on an opaque thin film at the location of interest, as measured by an imaging infrared radiometer. Knowledge of film radiative properties, plus quantitative estimates of convection cooling, permit the steady state energy balance at any location on the film sheet to be solved for the incident heat flux. Absolute accuracies on the order of 10-15% have been obtained in tests performed in air. The method is particularly useful for evaluation of spatial heat flux uniformity from distributed heat sources over large areas. It has recently been used in several applications at the Jet Propulsion Laboratory, including flux uniformity measurements from large distributed quartz lamp arrays used during thermal vacuum testing of several spacecraft components, and flux mapping of a low power NdYg laser beam.

IR video images acquired by scanning imaging radiometers are subject to several problems which make measurement of small temperature differences difficult. Among these problems are 1) aliasing, which occurs When events at frequencies higher than the video frame rate are observed, 2) limited temperature resolution imposed by the 3-bit digitization available in existing commercial systems, and 3) susceptibility to noise and background clutter. Bandwidth narrowing devices (e.g. lock-in amplifiers or boxcar averagers) are routinely used to achieve a high degree of signal to noise improvement for time-varying 1-dimensional signals. We will describe techniques which allow similar S/N improvement for 2-dimensional imagery acquired with an off the shelf scanning imaging radiometer system. These techniques are iplemented in near-real-time, utilizing a microcomputer and specially developed hardware and software . We will also discuss the application of the system to feature extraction in cluttered images, and to acquisition of events which vary faster than the frame rate.

An infrared (IR) detection technique is applied to the problem of measuring electric fields both interior and exterior to metallic cylinders under microwave illumination. An IR measurement technique which can be used to detect microwave fields, both continuous wave (CW) and pulsed, is described in this paper. The technique involves placing a thin lossy detection screen material in the region over which the electromagnetic (EM) field is to be mapped. The fields are detected through Joule heating that occurs then EM energy is absorbed by the screen material. The induced temperature distribution, detected by an IR scanning system via emitted thermal radiation, at the surface of the screen corresponds to the EM field intensities in the screen. Thus, the two dimensional field distribution can be seen in nearly real time and is now extended to the interior and exterior problem. The simultaneous observation from a dual band Thermovision System is also being investigated.

A thermal-imaging apparatus is disclosed for the nondestructive detection of subsurface defects in materials which would not usually lend themselves to thermal imaging because of their low emissivity and high susceptibility to background reflection noise. This is accomplished by transferring the thermal image produced by surface temperature perturbation of the workpiece material to a high-emissivity material with which it is continuously brought in contact. The transferred thermal image may be observed by a suitable infrared device resulting in a high-radiance image with minimum reflectivity or variable emissivity noise. Numerical simulations, as well as experimental results, are presented.

A large graphite epoxy filament-wound tank was inspected by thermographic methods. Suspected areas of delamination were verified and mapped. The tank was then cut into pieces and the pieces were inspected ultrasonically; these results were compared to the results of the thermographic tests.

A numerical approximation was used to determine the ability of a thermographic imaging camera to detect defects in a panel of graphite epoxy composite while excitation is provided by a specific, commercially available high-energy pulsed xenon flash lamp capable of repetitive pulses of 600 J each. A three-dimensional mathematical model was developed, which simulated the composite panel. The panel consisted of eight plies and included implanted circular defects. Defects modeled included delaminations, overlaps, and teflon inserts. During the first second of the simulation, six heat pulses of 0.2 msec duration were applied to the front surface of the sample. Temperature variations appear on the rear surface of the sample due to the presence of defects inside the panel, which cause the heat to diffuse through the sample at modified rates. A minimum temperature difference of 0.18 °F (0.1 °C) was detectable by the thermal imaging camera. The purpose of this study was to determine whether the purchase of a xenon flash lamp system was warranted for thermographic nondestructive testing (NDT) on graphite epoxy laminates.

A suitably-calibrated infrared thermogram contains both qualitative information about the temperature distribution and quantitative information about the numerical temperature valhes. A grey-scale rendering shows the temperature distribution well for human interpretation but cannot be used to obtain numerical values. Conversely, a density-sliced pseudocolor rendering permits semi-quantitative interpretation but often obscures fine details of the temperature distribution. A single rendering which provides both would be useful. Color perception includes the three distinct dimensions of brightness, hue, and saturation; these may vary independently. It is thus possible to construct a pseudocolor mapping in which brightness varies continuously but hue and saturation vary stepwise. If applied to a thermogram, the result is a grey-scale image with superimposed color tints organized into contours. The grey-scale image shows the temperature distribution clearly, and the tints correspond to temperature contours for semi-quantitative interpretation. The grey-scale image may be enhanced before temperature contours are applied. Point operations such as contrast stretching or histogram equalization increase visibility of detail but retain a one-to-one correspondence between grey level and temperature. Neighborhood operations such as unsharp masking or gradient filtering are also possible. These operations destroy the one-to-one correspondence so temperature contouring becomes essential to portray even semi-quantitative temperature information.

A method and its theory of measuring the total heat flow of hot equipment by two IR systems are set forth in this paper. One Of the IR systems includes a pyrometer with a hemispherical reflector and the other includes a pyrometer with a hemispherical absorber. These two IR systems are used to measure the surface temperature and emissivity of the hot equipment. Given the temperature of the relatively cold background and the height of the measurement point on the equipment surface, the total heat flow can be figured out easily. The measurement uncertainty of the method is less than 5% if the surface temperature and the emissivity of the hot equipment are greater than 200°C and 0.7 respectively.