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The emissivities of different new steel grades for reactor use were determined. Numerical models for optimizing of the radiation heat transfer need total emissivities. For idealized bright metals the calculation of emissivities is possible, but not for different thermally treated surfaces. The emissivity of technical surfaces depends on numerous factors and cannot be calculated exactly based on theoretical relations. Therefore the emissivities of different pretreated steel samples have to be determined experimentally. The emissivity properties of two new steel qualities with and without
different pre-treatments were investigated in the wavelength range between approx. 1.5 μm and 24 μm and the temperature range 200°C and 700°C. The results will be shown as spectral emissivities. Differences in the emissivities caused by pre-treatments will be discussed. The University of Duisburg-Essen has a measuring device for spectral emissivities. With these values temperature dependent total- and band-emissivities for use in heat transfer calculations and non-contact temperature measurements can be determined.
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New uniform camera electronics were developed for different stationary line and 2D infrared cameras for non-contact temperature measurement. The 16bit analog/digital converter used enables a maximum pixel rate of 10 MHz. The electronics are based on a System Of Programmable Chip (SOPC) solution using a PLD with an embedded processor. The ability to reprogram the PLD allows an inexpensive adaptation to different sensor types and various industrial applications. The embedded processor executes the signal processing, including the necessary signal corrections. In addition, the embedded processor controls and monitors the camera head, monitors the operation of the chopper/shutter motor and internal temperature sensors, and can be used to control a number of functions such as triggering or frame rate. The PC communicates with the micro-controller via an asynchronous interface. The other essential components of the digital signal-processing unit include a serializer, a flash memory and an SRAM. The new 16bit camera electronics have been incorporated into the following 2D infrared cameras PYROVIEW 256 with a pyroelectric array (256 x 128 pixel)
PYROVIEW 320 with a microbolometer array (320 x 240 pixel)
The paper will describe technical properties and typical applications in industrial applications for both devices as well as the advantages and disadvantages of pyroelectric vs. microbolometer arrays. In addition, since the newly developed 16bit camera electronics also provide the basis for faster line cameras (PYROLINE with pyroelectric arrays of 128 x 1 and 256 x 1 and an InGaAs line array with 256 x 1), selected applications of these cameras will also be discussed.
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The use of infrared tympanic thermometers within the medical community (and more generically in the public domain) has recently grown rapidly, displacing more traditional forms of thermometry such as mercury-in-glass. Besides the obvious health concerns over mercury the increase in the use of tympanic thermometers is related to a number of factors such as their speed and relatively non-invasive method of operation. The calibration and testing of such devices is covered by a number of international standards (ASTM1, prEN2, JIS3) which specify the design of calibration blackbodies. However these calibration sources are impractical for day-to-day in-situ validation purposes. In addition several studies (e.g. Modell et al4, Craig et al5) have thrown doubt on the accuracy of tympanic thermometers in clinical use. With this in mind the NPL is developing a practical, portable and robust primary reference fixed point source for tympanic thermometer validation. The aim of this simple device is to give the clinician a rapid way of validating the performance of their tympanic thermometer, enabling the detection of mal-functioning thermometers and giving confidence in the measurement to the clinician (and patient!) at point of use. The reference fixed point operates at a temperature of 36.3 °C (97.3 °F) with a repeatability of approximately ± 20 mK. The fixed-point design has taken into consideration the optical characteristics of tympanic thermometers enabling wide-angled field of view devices to be successfully tested. The overall uncertainty of the device is estimated to be is less than 0.1°C. The paper gives a description of the fixed point, its design and construction as well as the results to date of validation tests.
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The impact of thermal radiation and its associated radiance temperature on nearly all facets of technology and society is tremendous. Reliable temperature measurements are in that context of vital importance in many areas in science, technology, industry and environmental protection. This implies the use of a sound traceability framework, involving accurate reference standards to begin with and a calibration procedure for radiation thermometers that incorporates all sources of measurement errors (uncertainties). Latter procedure should be two-fold; first a traceable comparison is made against a blackbody radiator, then the instrument is evaluated and/or calibrated in its application. In this paper all three traceability steps will be addressed, that is, the dissemination of the international temperature scale of 1990 (ITS-90) and the initial and on-site calibration of radiation thermometers. First two steps were investigated in detail and improved on European level in the TRIRAT program that was funded by the European Community. This included international intercomparisons for radiation thermometer calibrations and recommendations for the standardization and testing of infrared radiation thermometers as transfer standards. An other project, ILART, bridges the gap in traceability between initial calibrated radiation thermometers and their industrial application. It involves realization of a portable calibration facility, intrinsically insensitive for surface emissivity and reflection error using active two-color thermometry.
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The Multispectral Thermal Imager (MTI) is a research and development satellite sponsored by the Department of Energy (DOE) for accurate water surace temperature retrieval. MTI uses five thermal spectral bands to retrieve ground temperatures. The application of MTI for land-based temperature and emissivity retrieval has been limited. Savannah River Technology Center conducted several ground truth campaigns at Ivanpah Playa to measure reflectance, temperature and emissivity. The results of MTI temperature and emissivity retrievals and material identification will be discussed in context with the ground truth data.
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The need for standardization in infrared radiation thermometry has never been more significant than now, particularly in the US Steel industry. The situation must be similar to that faced by thermocouple users and makers in the last century. The technology is mature and the applications well understood by pyrometry and instrumentation specialists. Yet, neither is well understood by the majority of mill engineers. Selection of optimum devices for various mill applications requires specialized knowledge. The steel companies have trimmed staff to the point that vendors are becoming the default technology specialists. Yet the companies have no means to evaluate the competence of competing vendors and their devices. They thus default to devices & practices believed adequate instead of proven optimums. One solution is to develop a comprehensive set of standards, similar to those for thermocouples. These would include terminology, used in device specifications, along with recommended practices for use of certain device types in specific mill conditions and finally recommended practices for ancillary equipment & utilities, installation, commissioning, maintenance and periodic calibration verification.
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Wall plays an important role in building fire. It can be used to block the fire and prevent its propagation. It restricts free air entrainment, heat transfer and radiation from the wall side of fire. In other cases the wall will accelerate fire to spread to ceiling. Experiment research was carried out to study the influence of wall on the shape of flame and temperature distribution. An array of thermocouple is applied to study the temperature distribution along the wall. A large caliber laser Moiré Deflectometry was used to display the flow procedure during the interaction of wall and flame, especially the changing of buoyant plum along the wall. Five cases, in which the plain wall was settled at 0, 5, 10, -5, and -10 degree with the axis of flame respectively, were studied. The distance between wall and flame was also changed in these five cases. The inclination effect of wall exerting on flame was clearly displayed. Influence of wall on the flame persistent zone height is calculated from experiment data in each case.
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The object of this research is to develop a procedure using IRT to detect critical levels of moisture content in wood. Passive and active approaches are compared to define the most reliable procedure to map the moisture diffusion and to evaluate the moisture content of the surfaces. Laboratory research reported in the scientific literature has determined that the water content in porous materials is more related to the evaporative speed of the surfaces and the presence of soluble salts than to their absorption capability. Moreover, evaporative fluxes were studied at different environmental conditions and water content in order to determine a correlation between moisture content, evaporation and boundary conditions.
The thermal characteristics of timber are different those of porous materials such as brick and stone and mortar, particularly in that the thermal capacity of wood is lower. Nevertheless, because of the lower heat capacity of wood, the presence of water greatly affects the wood thermal capacity. Therefore, the active procedure guarantees the best results. Lab tests and a study case (Knight House, Kirtland OH) show the advantages and the limits of IRT techniques, and the results obtained demonstrate the sensitivity of the method in oak and pine wood species.
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The number of thermal imagers in the active use in Finland for building thermography is relatively high. The problem is lack of valid instructions or requirements for building thermographers thermography. In this paper the actual use of thermography has been presented. Also some new guidelines for interpretation for results are intoduced.
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Frequently, on outdoor thermographic surveys long wavelength infrared-thermal imaging systems are employed. When such systems are cooled, that are ideal for outdoor measurements, since they eliminate the effects of similar reflections and enhance the accuracy of the measurement. In this research study, long wavelength infrared thermography was used in the assessment of historic porous stones' masonries, either consolidated or untreated, in the Medieval City of Rhodes, in Greece. Due to the difference between the thermal diffusivities of consolidated and untreated stones or even of moist and dry stones, infrared thermography was capable of imaging large areas, displaying qualitative variations in penetration depth (i.e., consolidation) and/or respiration behavior (i.e. moisture impact), appearing as surface temperature fluctuations in the thermal image(s). The obtained thermal images provided significant information in the assessment of materials concerning moisture and consolidation treatments: monitoring of the physicochemical behavior of porous materials. Conclusively, thermography ought to be considered as a powerful nondestructive assessment tool on the investigation of historic structures.
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A wide field of view Gas Filter Correlation Radiometer (GFCR) has been developed to make solar occultation measurements of the vertical methane distribution in the stratosphere from a sounding rocket platform. The GFCR has demonstrated a 50° solar acceptance angle that allows for a GFCR measurement during every rotation of the payload without active orientation control. The flat surface of a plano-convex ZnSe lens was etched to diffuse the projected image of the sun. By diffusing the incident solar radiation through a wide angle, sufficient radiation could be directed to the collimating GFCR optics even when the optical axis points as far as ± 25° away from the Sun. The system can be configured to measure other gaseous species with spectral bands in the 2 - 6 μm region by simply changing the bandpass filter and the correlation gas. In a laboratory calibration, the optical density of methane in a test cell was varied from 10^-4 to 10-2 atm·m as the GFCR correlation cell optical density was held at 2.5×10-3 atm-m. The process showed that measurements with a signal to noise ratio > 30:1 can be expected when the system operates in altitudes from 25 to 40 km. The GFCR performed with a correlation of 99.7% to the prediction of a theoretical model created with the HITRAN database. Sensitivity to gas distributions at other altitudes can be optimized by changing the gas pressure in the correlation cell. The payload featuring the GFCR is scheduled to be launched on an Enhanced Orion sub-orbital sounding rocket from NASA Wallops Flight Facility in April 2003. Future applications include validation and truthing for space-born remote sensing systems.
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An Orion sounding rocket will be launched from Wallops Flight Facility and will carry a University of Virginia payload to an altitude of 65.7 km to measure the distribution of methane in the Earth’s upper atmosphere and record images and quantitative measurements of the distribution of chlorophyll in the Metompkin Inlet, Virginia. This new payload launch will be UVa’s second launch as a result of a five-year undergraduate design project by a multi-disciplinary student group. As part of a new multi-year design course, undergraduate students designed, built, tested, and will participate in the launch of a suborbital platform from which atmospheric remote sensors and other scientific experiments can operate. The first launch included a simplified atmospheric measurement system intended to demonstrate full system operation and remote sensing capabilities during suborbital flight. The second and upcoming launch includes a methane GFCR system intended for upper atmospheric measurements, a photodiode/camera system intended for the remote sensing of chlorophyll distribution and concentration in the Metompkin Inlet due to confined animal runoff pollution. Two thermoelectrically cooled HgCdTe infrared detectors, with peak sensitivity at 3 mm, were designed to measure the methane distribution in the upper atmosphere, by having infrared radiation filtered through a methane cell and a nitrogen reference cell. A small camera with a green band-pass filter will be aligned with five photodiodes, each covered by a narrow bandpass filter that matches the filters in the SeaWiFS system, to provide cross-referencing for the remote sensing of the chlorophyll in the Metompkin Inlet and to enhance the chlorophyll distribution. This payload will serve as a platform for future atmospheric sensing experiments. Currently, the GFCR has been tested and calibrated, the chlorophyll measurement system is being calibrated, and the components and mounts are being gathered, calibrated, tested and fabricated. In the next few months, the payload will be integrated and the data reduction models will be constructed.
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Water mist is used as an efficient extinguishing media instead of banned halogen-based fire extinguishing agent. Experiment was conducted to study the interaction of fine water mist and a small-scale fire. This fine water mist serves as candidate agent of fire protection system for electronic equipment fire. The characteristics of the fine water mist was obtained by three-dimensional laser Doppler velocimetry (LDV) / adaptive phase velocimetry (APV). Two kinds of fine water mist with equal mean droplet size, different velocity and caliber of mist jet were used to suppress a small-scale fire. A temperature measurement system based on micro-thermocouples was used to record temperature variation of the fire during exertion of fine water mist. A laser Moire deflectometry system displayed the flame pattern. Serial photographs of fire suppression process were present in this paper. The result shows fine water mist offers an enhanced cooling performance on the surrounding of fire flame.
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Infrared thermal sensing and imaging instruments, promoted by military interests as early as World War I, had evolved into serious industrial and energy conservation tools in the US by the late 1960s. The 'energy crunch' of the 1970s focused national attention on methods for saving energy. ThermoSense I, the 'First National Conference on the Capabilities and Limitations of Thermal Infrared Sensing Technology in Energy Conservation Programs' was held in 1978, sponsored by the American Society of Photogrammetry (ASP), the US Department of Energy (DOE) and the Tennessee Valley Authority (TVA). As applications for these new and exciting photonics instruments broadened into new fields such as predictive maintenance, process control, materials testing and remote sensing, the conference broadened and expanded under the sponsorship of SPIE. In the year 2003 the ThermoSense conference is being held for the 25th time. This paper traces 25 years of evolution of the applications for infrared thermal sensors and imagers as well as the improvements, innovations and refinements to the instruments themselves. Finally, some projections are made for current and near future developments in the capabilities and markets for the technology.
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Using a high speed IR camera for temperature sensor is a powerful new tool for thermal analysis in the cell scale biomaterials. In this study, we propose a new type of two-dimensional thermal analysis by means of a high speed IR camera with a microscopic lens, and applied it to the analysis of freezing of plant and animal cells. The latent heat on the freezing of super cooled onion epidermal cell was randomly observed by a unit cell size, one by one, under a cooling rate of 80degC/min with a spatial resolution of 7.5m. The freezing front of ice formation and the thermal diffusion behavior of generated latent heat were analyzed. As a result it was possible to determine simultaneously the intercellular/intracellular temperature distribution, the growing speed of freezing front in a single cell, and the thermal diffusion in the freezing process of living tissue. A new measuring system presented here will be significant in a transient process of biomaterials. A newly developed temperature wave methods for the measurement of in-plane thermal diffusivity was also applied to the cell systems.
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Infrared technology has seen little use at the level of the family farm, mostly due to the prohibitive high cost relative to the typically modest profit margins. Where farming exists as a hobby or secondary activity, an individual with access to the technology can uncover some of the many applications waiting to be discovered in this field. As technology improves, and the price of cameras decreases, the viability of infrared as a farming tool improves.
This paper outlines a number of examples where an individual with access to infrared technology has utilized it in a family farm setting to highlight some of the potential uses which may someday become normal farming practice. These examples are augmented by research of work being done at land-grant universities and larger agricultural businesses that further show the viability of the technology in farming.
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In the field of dynamic engineering and biomechanics, the digital video recorder (DVR) is widely applied to visualize two- and three-dimensional images of moving machineries and human beings using several visual markers on the body surface. On the other hand, high-speed infrared radiometers (IR) are often used to visualize and analyze the dynamic image of moving body as well as their temperature distributions. IR radiometric systems are mainly applied to detect external and internal flaws of dynamic components and etiological causes of human beings in the field of industry and medicine, as remote-sensing non-destructive and diagnostic methods. Simultaneous visual studies of dynamic motion and temperature distribution of the moving body are very little to apply industrial and biological engineering systems. Quantitative analysis using the high-speed IR system was carried out to visualize and motion and thermal images of the moving bodies simultaneously. In this study, the high-speed IR system measures the dynamic and thermal images of the moving bodies using passive and artificial thermal markers and friction marks of the moving interface boundary. Dynamic motion characteristics of measured images by digital video recorder DVR and IR were quantitatively compared. Characteristics of single- and multi-flash imaging methods were measured and analyzed using the triggered motion coder. The IR radiometric systems are quite useful in the visualization and analysis of the motion and thermal distribution of the moving mechanical components, human bodies and their supporting components. These characteristics are well related to motion physiology, human welfare, health management etc.
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At the moment foreign substances in food are detected mainly by using
mechanical and optical methods as well as ultrasonic technique and than they are removed from the further process. These techniques detect a large portion of the foreign substances due to their different mass (mechanical sieving), their different colour (optical method) and their different surface density (ultrasonic detection). Despite the numerous different methods a considerable portion of the foreign substances remain undetected. In order to recognise materials still undetected, a complementary detection method would be desirable removing the foreign substances not registered by the a.m. methods from the production process. In a project with 13 partner from the food industry, the Fraunhofer - Institut für Holzforschung (WKI) and the Technische Unsiversität are trying to adapt thermography for the detection of foreign bodies in the food industry. After the initial tests turned out to be very promising for the differentiation of food stuffs and foreign substances, more and detailed investigation were carried out to develop suitable algorithms for automatic detection of foreign bodies. In order to achieve -besides the mere visual detection of foreign substances- also an automatic detection under production conditions, numerous experiences in image processing and pattern recognition are exploited. Results for the detection of foreign bodies will be presented at the conference showing the different advantages and disadvantages of using grey - level, statistical and morphological image processing techniques.
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Industrial and commercial building equipment maintenance has not historically been targeted for implementation of PdM programs. The focus instead has been on manufacturing, aerospace and energy industries where production interruption has significant cost implications. As cost-effectiveness becomes more pervasive in corporate culture, even office space and labor activities housed in large facilities are being scrutinized for cost-cutting measures. When the maintenance costs for these facilities are reviewed, PdM can be considered for improving the reliability of the building temperature regulation, and reduction of maintenance repair costs. An optimized program to direct maintenance resources toward a cost effective and pro-active management of the facility can result in reduced operating budgets, and greater occupant satisfaction.
A large majority of the significant rotating machinery in a large building environment are belt-driven air handling units. These machines are often poorly designed or utilized within the facility. As a result, the maintenance staff typically find themselves scrambling to replace belts and bearings, going from one failure to another. Instead of the reactive-mode maintenance, some progressive and critical institutions are adopting predictive and proactive technologies of infrared thermography and vibration analysis. Together, these technologies can be used to identify design and installation problems, that when corrected, significantly reduce maintenance and increase reliability. For critical building use, such as laboratories, research facilities, and other high value non-industrial settings, the cost-benefits of more reliable machinery can contribute significantly to the operational success.
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Continuous monitoring of plant and processes is widely practised but the use of thermal imagers in such systems has always been restricted by camera cost. A radiometric thermal imager can be regarded as equivalent to multiple single point radiometers or a matrix of thermocouples but with the advantages of far denser coverage, non-contact measurement, simpler installation and data processing; in addition several of the advantages of conventional machine vision systems such as shape and position recognition can be provided. IRISYS has developed a multipoint radiometer utilising its low-cost infrared array technology. This unit provides continuous real-time temperature monitoring of 256 data points at an affordable price; it is housed in a small, light-weight, sealed and robust metal case and generates RS232 or Ethernet data output. This paper reviews the radiometer technology and its application to single and multi-camera systems.
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Glass production processes cover a wide range of temperatures, from room temperature to over 1600°C. Non-contact thermal imaging is well suited to gather temperature information about these processes, especially where contact temperature methods will disturb the process or will not survive the harsh environment. For a given process, the type of information gathered depends strongly on the infrared wavelengths used in the detector. With hot glass, shorter IR wavelengths (NIR and SWIR) typically reveal information about the interior temperatures of the glass, while longer wavelengths (MWIR and LWIR) reveal information about the surface temperatures. For molds, plungers, and other glass-forming equipment, shorter wavelengths reveal surface temperatures, while longer wavelengths tell more about reflectivity and wear of the surfaces. Combining information from different parts of the IR spectrum gives us a more complete picture of heat transfer during glass production. This, in turn, allows us to understand and solve more complex production problems.
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Infrared Thermography has been found to be a very valuable tool in the petroleum industry. It has had focus in surveying all the types of equipment in its asset base. This includes electrical distribution systems, pumping systems, piping systems, exchangers, flares, process fired heaters and many other types of equipment. The petroleum industry is divided into three basic operating areas; Upstream, Midstream and Downstream. Upstream operation covers the exploration, drilling and production of natural gas and crude oil. Midstream operation in the petroleum industry is the distribution and storage system between the Upstream to the Downstream systems. Downstream operations make the finished energy product and are the refineries and chemical plants. As in other industries, the petroleum industry has mechanical equipment, electrical equipment, pressure-containing equipment, and fixed structures. In addition to this equipment, there is some specialty equipment which includes items such as fired heaters and specialty process vessels. The industry has put in place infrared programs as a predictive maintenance tool in many of their operating areas. Using infrared to monitor the operating integrity on equipment is one of the synergies now being better developed. The opportunity is to define measurable thermal patterns that can be used to define defects and predict failures. Infrared technology is a mature reliability work process and been around for many years. The first commercial infrared camera was available in the '70's. These radiometric cameras and the support equipment have had many improvements since then. The use of the technology has also been improved with synergies incorporated from many type of industries, including the military. Infrared is a technology that has been added to the predictive & preventative maintenance toolbox of the petroleum industry reliability focus. An important part of any reliability work process is to have predictive tools to define equipment defects as early as possible. Early detection of a defect allows for better failure analysis to improve the equipment’s service life performance. It also assists in identifying the true problem rather than a symptom of the problem. In many cases, what we see as the failed component is a symptom of what the true cause of the failure was. Infrared can assist us with seeing the true cause. It is seen as a predictive tool that supports other predictive technologies, such as vibration analysis and compression analysis.
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The Principal of using infrared (IR) viewing ports has been well established for many years. IR thermography is a proven, well tested, safe and efficient method of checking the serviceability of electrical components, and because it is a non-contact measurement it allows the test to be completed live, that is of course if the risk assessment score allows us to. We do at times have to remove fixed covers when possible, to allow access to the components that require inspection, as we can only measure the temperature of components that we can see. This can cause problems when the components that you want to inspect are behind covers that cannot be removed or require the power to be shut off, due to switched interlocks, etc, this may be impossible to do during the inspection as we will very rarely be able to isolate a panel due to the power loss to the systems being fed.
Currently we check the temperature measurement of such panels by monitoring the surface temperature and cable temperatures from the panel, this is an indirect measurement and will show that there are issues within the panel being inspected, but does not give any indication to the actual problem and temperature of the failed component within the panel By using IR viewing ports we are able to see the component and take direct temperature measurements to check the serviceability of the component live and safely without having to remove the cover, this then makes the inspection of your electrical systems faster, safer and removes the manpower requirement for the removal of covers during the inspection, thus making it less expensive to carry out your thermographic inspections.
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Thermography is widely used for inspecting electrical systems where costly problems are often preceded by telltale thermal signatures. Many thermographers, or their customers, however, mistakenly rely on radiometric temperature data to prioritize these findings. Due to the inherent limitations of radiometry and the complexities of heat transfer in the components being inspected, the data is all too often either inaccurate or misunderstood. Routinely, however, thermographers proceed as if nothing is amiss. This is due to an understandable, but misguided, attempt to simplify the decision-making process regarding repair priorities. The result is that predictions of repair priorities are not as accurate as they could be. On the one hand failures still occur while on the other repairs are often made inappropriately. In this paper we discuss the problems encountered when collecting and interpreting radiometric data. We will also outline a simple, effective system that thermographers are using to dramatically improve the predictive value of the technology. Improved results are achieved first separating the often intertwined questions of 'when will the component fail?' and 'what will be the consequences of failure?' The second improvement comes from incorporating all relevant data in the decision making process and weighing the impact each has. The system described, which can easily be adapted to diverse needs, is being used successfully and with repeatable results that have been shown to improve with usage.
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A thermal imaging technique has been developed to measure electromagnetic (EM) fields. This technique is applied in this paper to measure the EM fields radiated by phased array antennas. This thermal technique is based on infrared (IR) measurements of the heat patterns produced in a thin, lossy detector screen placed near the antenna in the plane over which the field is to be measured. A low-loss, planar detector screen was made from a carbon loaded polyimide film to measure the intensity distribution of the electric field radiated from the antenna. The Joule (conductive) heating in the screen causes the temperature of the screen to rise in proportion to the intensity of the wave incident on the screen. The temperature distribution on the surface of the film is captured with an IR imaging camera. The magnitude of the radiated field at each location in the detector screen (on a pixel by pixel basis) is determined directly from the temperature distribution in the IR thermogram of the field. The temperature rise in the screen material (over the ambient background temperature of the screen) was measured at NIST/Boulder when the screen was irradiated by a plane wave of known intensity. A calibration table of measured temperature rise versus expected field intensity was obtained for the detector screen. This thermal imaging technique has the advantages of simplicity, speed, and portability over existing hard-wired probe methods and produces a 2D picture (a pseudo-color image) of the field. In general, these images can be used for field diagnostics of the antenna (near-field or far-field patterns) and/or to evaluate the aperture excitation of the array. In particular, the source distribution in the aperture plane of the antenna was measured. This distribution can be compared to a standard 'test pattern', e.g., full power, equal-phase, broadside illumination, to determine the operational state of each individual element of the array, which controls the radiation pattern of the antenna. Phase shifters and/or attenuators which produce incorrect element phase magnitudes or phase shifts can be identified with this technique. Faulty elements, once located, can be repaired.
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In this work, a new experimental method based on IR thermography, has been developed to improve the precision of mass measurements in order to obtain as well as possible the influence magnitudes that distort the real mass of the mass standards when the balance is used. With this method it is possible to quantify the drag-froces values present on surroundings of the measure. The work reveals that the drag-forces are important and it is necessary to take them in account in the mass real determination. Depending on the shape, material, environmental conditions but the drag forces change not all the variables contribute in the same order of magnitude.
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The work begins a short presentation of laser ablation method, together with exemplary results of artwork cleaning. Next parts show the application of dynamic infrared thermography for study thermal phenomenon induced by pulse laser radiation of various fluency and time duration. These investigations focused only on the results of irradiation, as both too short time and complexity of the ablation phenomena had made unable all measurements of pure ablation properties. Thermal data about pre- and post-ablation state were delivered by infrared thermographic system in the form of sequences of thermograms. Information of interest occurred on small parts of these images only, and study of thermal movies or typical graphs showed to be inconvenient. The paper presents applied transformation of every sequence to single synthesized images: temporal-spatial thermograms of the isolate fields only. Numerous examples of these images, named as field dynamic thermograms, presented for various laser ablation experiments prove the great informing potential of modern thermography and in particular - signal processing for research and cleaning procedures optimizing works. Mentioned method of extracting useful information for dynamic of thermal distributions visualization can be of interest for other applications.
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Integrated Circuit (IC) chips constantly undergo different types of stress in the field, such as thermal, humidity, and electrical stress. Existing work has concentrated on humidity and thermal stress; there has been relatively little emphasis on high-voltage stress level prediction. The objectives of this investigation were to 1) explore the impact of high-voltage stress on IC functionality, (2) observe heating rate changes in chips under high-voltage stress over time, and (3) predict stress levels using artificial neural network models. Three different kinds of IC chips-namely, LM348N Operational Amplifier, LM386N-1 Power Amplifier, and LM555CN Timer Oscillator-were studied. Each chip was taken from a different printed circuit board. An artificial neural network model with a 3-2-1 topology was constructed to predict stress level given heating rate over time. Results indicate (1) high-voltage stress shortens the lifecycle of IC chips, (2) heating rate increases are relatively great in the first few minutes, then reach a steady state, and (3) neural network models can predict stress level with good accuracy. The detection rates for the Amplifier chips (LM348N and LM386N) were 97% and 91%, respectively. The detection rate for the LM555CN chip was around 75%; however those results may be improved with more samples for training and evaluation. In addition, the trainRP learning function resulted in a lower error rate (for the LM348N chip) with the original experimental data than other learning functions such as trainGD and trainCGP. Future directions include the expansion of the study to other types of IC chips, such as memory and microprocessor chips.
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There are increasing demands for information to avoid accident in automobile traffic increase. We will discuss that an infrared camera can identify three conditions (dry, aquaplane, frozen) of the road surface. Principles of this method are; 1.We have found 3-color infrared camera can distinguish those conditions using proper data processing 2.The emissivity of the materials on the road surface (conclete, water, ice) differs in three wavelength regions.
3.The sky's temperature is lower than the road's. The emissivity of the road depends on the road surface conditions. Therefore, 3-color infrared camera measure the energy reflected from the sky on the road surface and self radiation of road surface. The road condition can be distinguished by processing the energy pattern measured in three wavelength regions. We were able to collect the experimental results that the emissivity of conclete is differ from water. The infrared camera whose NETD (Noise Equivalent Temperature Difference) at each 3-wavelength is 1.0C or less can distinguish the road conditions by using emissivity difference.
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Since the modeling of machining processes relies on high-strain-rate, high-temperature material properties, NIST has built a split-Hopkinson (or Kolsky) bar to determine the stress-strain behavior of rapidly heated materials at high temperatures. Our Kolsky bar has been constructed in the NIST high current pulse-heating facility, which enables electrically heating the samples within ~ 100 milliseconds time duration, immediately before the mechanical impact in the bar. Due to the rapid heating, we avoid possible structural changes in the sample, and a stress-strain relationship can be determined at different temperatures for various test materials. We describe the design and the development of the resistively-heated Kolsky-bar apparatus. The incident and the transmitted bars are constructed of 1.5 m long, 15 mm diameter maraging steel, and a typical sample is a 4 mm-diameter, 2 mm-long cylinder of 1045 steel. The sample is placed between the bars and held by friction. The current is transmitted through the graphite-sleeve bushings of the two bars. The non-contact temperatures are measured using an InGaAs near-infrared micro-pyrometer (NIMPY) and an InSb focal-plane (320 by 256) array (thermal camera). The NIMPY and the thermal camera are both calibrated using a variable-temperature blackbody, and the thermodynamic temperature of the metal is determined using the emissivity determined from the measured infrared spectral reflectance of the metal. Thermal videos of the electrically-heated and the room-temperature impacts will be shown with 1 kHz frame rates, and the changes in the stress-strain curves with the temperature of the samples will be discussed.
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The heat generated in frictional organs like brakes and clutches induces thermal distortions which may lead to localized contact areas and hot spots developments. Hot spots are high thermal gradients on the rubbing surface. They count among the most dangerous phenomena in frictional organs leading to damage, early failure and unacceptable braking performances such as brake fade or undesirable low frequency vibrations called hot judder. In this paper, an experimental study of hot spots occurrence in railway disc brakes is reported on. The aim of this study was to better classify and to explain the thermal gradients appearance on the surface of the disc. Thermograph measurements with an infrared camera have been carried out on the rubbing surface of brake discs on a full-scale test bench. The infrared system was set to take temperature readings in snap shot mode precisely synchronized with the rotation of the disc. Very short integration time allows reducing drastically haziness of thermal images. Based on thermographs, a classification of hot-spots observed in disc brakes is proposed. A detailed investigation of the most damaging thermal gradients, called macroscopic hot spots (MHS) is given. From these experimental researches, a scenario of hot spots occurrence is suggested step by step. Thanks to infrared measurements at high frequency with high resolution, observations give new highlights on the conditions of hot spots appearance. Comparison of the experimental observations with the theoretical approaches is finally discussed.
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In this contribution a novel technique for computing complex
motion involving heat transport processes will be presented. The
proposed technique is a local gradient based approach, combining
transport models with motion analysis. It allows for the
simultaneous estimation of both motion and parameter of an
underlying transport model. Since the analysis is based on thermal
image sequences, estimates are computed to a high temporal and
spatial resolution, limited only by the resolution and frame rate
of the employed IR camera. This novel technique was utilized on
exchange processes at the atmosphere/ocean boundary, where
significant parameters of heat transfer could be measured and a
transport model verified. Using the presented algorithms, surface
flows as well as convergences and divergences on air-water
interfaces can be measured accurately. Apart from applications in
oceanography and botany, relevant benefits of the proposed
technique to NDT will be presented. It is possible to compensate
for motion to reach accuracies much better than 1/10th of a pixel.
Through the direct estimation of locally resolved diffusivities in
materials, insights can be gained about defects present. By
estimating not only isotropic diffusion but also the whole matrix
of anisotropic diffusion, the technique is highly relevant to
measurements of composite materials.
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As far as power generation is concerned, coating technologies find the main and more advanced applications. Nowadays, superalloys available for manufacturing hot path components in gas turbine like combustion liners, blades and vanes can not sustain temperatures up to 1100°C. In order to guarantee a significative temperature drop ceramic thermal barrier coatings are deposited onto the metallic core. The thickness of thermal barrier coatings (TBC) ranges from a few hundreds microns up to 1 millimetre or more, depending on component and deposition technique (mainly Air Plasma Spray or Electron Beam Physical Vapour Deposition). The structural integrity of both the substrate and the coating and their mutual adhesion is a key point because any loss of the protective layer exposes the bulk material to an extremely aggressive environment in terms of oxidation and temperature. Therefore, TBC must be tested for detecting of defects during both quality control and periodic in-service inspections. Because of the key role played by thickness and low thermal diffusivity of TBC in the decreasing of the substrate material temperature, both delaminations and thickness variation must be detected and classified. Pulsed Thermography has been successfully applied to this application field. Nevertheless, the procedure gives ambiguous results when thickness or thermal properties change in a continuous way within the thermal barrier. In this paper, a specific study on the detection performances of NDE techniques is presented, even when a non-uniform TBC thickness is superimposed to the disbonding defect. Tests performed at workshop on real and specifically manufactured components are reported. Dedicated processing algorithms improving the test reliability and effectiveness are presented as well. Tests on real components on the field are also reported.
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Even in the best of economic times, funding for infrastructure maintenance, repair and rehabilitation is never adequate. As infrastructure in the United States continues to age, the funding deficit to simply maintain the existing bridges will continue to soar. Due to the inadequacy of capital allocated for infrastructure repair and rehabilitation, new, more durable construction materials with potentially longer service lives are being explored as a means of narrowing the financial deficit. One such material is fiber reinforced polymer matrix composites (FRP). By replacing conventional bridge component structural materials (i.e.; reinforced concrete and steel) with FRP, which has a higher strength to weight ratio, bridges can achieve a significant reduction in dead load weight. Bridges that have experienced substructure and superstructure deterioration can undergo a superstructure replacement with FRP rather than be subjected to the traditional load posting (vehicular load restrictions). Through reducing the bridge dead load without compromising bridge strength, original design live loads can be maintained. In order for these new bridge superstructure components to be readily accepted as viable construction materials, quick and effective means of monitoring them for degradation and overall structural health must be established and standardized. One of the most promising methods of achieving this is through the use of thermal infrared (TIR). A slight increase in temperature above ambient will allow for adequate inspection of large sections of bridge decking for detection of debonded areas between FRP components. This paper illustrates the successes and challenges of using TIR for this purpose, both in the laboratory and in field investigations. Areas for future work and improvements will be suggested.
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In Japan it happens that building parts made of concrete suddenly collapse to create obstacles to the traffic in tunnels, on highways and bridges. Thus, the safety issue has become a serious social problem. Therefore, the detection of hidden defects in concrete building constructions in order to prevent an accidental damage is the important application area for nondestructive testing (NDT) techniques. Until now, the inspection is typically performed by using a hammer that is subjective and takes too much time. Infrared thermography is a promising NDT technique that might help in the fast detection of invisible (hidden) defects. Transient, or active, thermal NDT requires external thermal stimulation of the defects under test by warming up or cooling down the defect surface. However, low-power and long heating is significantly affected by environmental conditions.
Recent Japanese research in this area has been rather qualitative, i.e. without putting the accent on evaluating parameters of hidden defects. In this study, the experimental results are modeled and processed by using the thermal NDT package developed at the Tomsk Institute of Introscopy. This has allowed not only optimizing test parameters but also obtaining reasonable estimates of defect parameters for air-filled voids and inclusions in concrete. It is shown that MRTD values experimented by us are of a little help while evaluating detection limits.
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A lot of structural key elements of many modern civilian and military airplanes, such as flaps, keel, etc., are made of honeycomb structures. Honeycombs involve a combination of some materials including aluminum, Nomex, glass and graphite epoxy composites. During exploitation, atmosphere water could penetrate these structures due to possible imperfections in various junctions, and, thus, deteriorate airplane durability. In Russia, water in honeycombs is typically detected by using the X ray and ultrasonic technique. However, the X ray equipment is hardly accepted by commercial airlines because of the safety reason, and the point-by-point ultrasonic inspection is low-productive. Since 2002, we develop the IR thermographic method of detecting water by thermally stimulating aviation panels under test. Unlike the technique accepted by Airbus Industry, Inc., that uses 'a warm blanket', we use a powerful optical heater assembled with an IR camera into a single set. The first stage of research included modeling the detection process and optimizing the experimental procedure. As a result, we have demonstrated that, due to the high heat capacity of water, a temperature signal over moist areas evolves in time during a relatively long period that relaxes the requirements to the test protocol. Thus, even aluminum panels can be thermally stimulated during few seconds with a delay time being also in a few second range. A similar protocol can be applied to the inspection of composite honeycombs where the image quality resembles that obtained by X rays. The paper will describe all stages of the research starting from modeling and finishing with the preliminary experimental results obtained in situ on civilian airplanes.
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Transient thermography was employed in the inspection of two repaired aircraft composite panels in the laboratory. The investigated panels were aluminium alloy panels under boron composite patching. The defects were placed between or under the plies of the composite patches and were assessed using firstly a simple heat excitation source with an IR camera and secondly an integrated pulsed thermographic system. In both situations, the defects were artificially created. After detecting the defects, the thermal images obtained from the transient thermographic inspection underwent an image processing quantitative analysis approach, in order for the qualitative images to be translated into quantitative results. Finally, mathematical - thermal modelling was also attempted in order to obtain information about the defects in space and in time.
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The determination of the depth and size of delaminations is important for assessing their impact on structural integrity. A common technique for depth determination from thermal responses relies on a calibration of the technique based on flat bottom hole in a NDE standard. This assumes a delamination will effectively block all the heat diffusion from the region above the delamination to the region below the delamination. For graphite fiber reinforced composites, where a thin delamination has a contact resistance, which is comparable with the thermal resistance of the layer above it, this assumption is inaccurate. This paper discusses thermographic depth profiling based on an analytical model for heat diffusion representing two layers connected by a contact resistance. The model is shown to accurately represent the thermal response obtained for flash heating of composite specimens with known delaminations. Using the model to fit the thermal responses enables an estimation of the depth of the delamination. The accuracy of the technique is determined from measurements on composite specimens with delaminations at known depths.
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Thermography involves the application of heat to a structure and observation of surface temperature anomalies to reveal subsurface defects. Detection of subsurface defects can be greatly enhanced by the real time capture of a series of thermal images in time and the subsequent analysis of these images using various image processing algorithms. By applying image-processing algorithms, defects not readily observable can be detected and quantitatively characterized. The focus of this work is to investigate several of the numerous data reduction algorithms for thermal nondestructive evaluation by comparing results on a set of test samples. Some new types of data reduction algorithms have been recently developed with advantages such as noise reduction, file size compression, and material property measurements. By comparing various algorithms on factors such as computational speed, simplicity of use, robustness to noise, quantitative information, and optimum defect detection the most efficient algorithm may be chosen based on the user’s needs.
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Ultrasound excited thermography allows for defect selective imaging using thermal waves that are generated by elastic waves. The mechanism involved is local friction or hysteresis which turns a dynamically loaded defect into a heat source which is identified by a thermography system. If the excitation frequency matches to a resonance of the vibrating system, temperature patterns can occur that are caused by standing elastic waves. This undesirable patterns can affect the detection of damages in a negative way. We describe a technique how the defect detectability of ultrasound activated thermography can be improved. With the objective of a preferably diffuse distributed sonic field we applied frequency modulated ultrasound to the material. That way the standing waves can be eliminated or reduced and the detectability is improved.
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Recently we proposed a modification of the classical flash thermography method for diffusivity measurement: by putting a mask having a periodic pattern of apertures between the flash lamp and the orthotropic material to be tested, one can obtain simultaneously the out-of-plane diffusivity and the in-plane diffusivity of the material. Here we present two examples where the measurement of the thermal properties is made at a local level: the experiment is performed with a large grid mask, however the parameter identification is made on a sliding window whose width corresponds to one-period of the mask. By this way, one can get a profile for each diffusivity. By applying this procedure, one can expect detecting localised variations of the thermal properties, as well as cracks.
We controlled by this way a series of C/C-SiC dog-bone samples during a tensile test. We systematically observed a rather uniform and linear decrease of about 0.1%/MPa for the in-plane diffusivity. This behaviour is related with the fact that a stress increase induces a gradual increase of the microcracks density. The second example deals with carbon disk brakes control. By using a circular mask, one can get in about two minutes the circumferential profile of both in-plane and out of plane diffusivities of the composite piece.
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Analysis and processing of thermographic NDT data has been primarily based on either visual analysis of single images acquired during the cooling sequence, or examination of a contrast curve based on comparison to a defect free reference region. Analysis of the sequence is complicated by the fact that the surface temperature of the sample decreases monotonically over a large dynamic range, yet the temperature differences generated by subsurface features may be small by comparison. A simple linearization operation can be performed on the entire sequence so that the time history of each pixel behaves in a manner similar to that of the contrast curve. The linearized data allows visualization of the entire sequence in a fixed dynamic range that is small enough to allow visualization of weak features, as well as presentation of the data in a line slice manner similar to an ultrasonic b-scan.
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Work is presented which begins to define the envelope of applicability for the sonic IR NDE technique. Detection limits define the faintest flaw signal that can be perceived, which is a function of flaw size and depth, excitation strength and duration, and the detector limits (spatial, temporal, thermal). A unique contribution of the present work is a model to predict the dynamic frictional heating of a crack, and this is combined with a transient heat transfer analysis to define the detection limits. Damage limits consider the risk of damage to a part from the application of the dynamic excitation. Experience has shown that the dynamic excitation can damage parts, notably for brittle materials such as ceramics with existing flaws. Since sonic IR is intended to be nondestructive it is important to test parts in a manner consistent with preserving the part integrity. The evaluation of damage limits assumes that additional part damage during testing is a fatigue process that propagates existing cracks. Paris' law for fatigue damage is employed to provide an estimate of fatigue crack propagation during the dynamic forcing. Both detection limits and damage limits are combined to create an envelope of applicability for sonic IR. Further experimental effort is required to tune and validate the analytical tools presented herein. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
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Work is presented which allows flaw characteristics to be quantified from the transient IR NDE signature. The goal of this effort was to accurately determine the type, size and depth of flaws revealed with IR NDE, using sonic IR as the example IR NDE technique. Typically an IR NDE experiment will result in a positive qualitative indication of a flaw such as a cold or hot spot in the image, but will not provide quantitative data thereby leaving the practitioner to make educated guesses as to the source of the signal. The technique presented here relies on comparing the transient IR signature to exact heat transfer analytical results for prototypical flaws, using the flaw characteristics as unknown fitting parameters. A nonlinear least squares algorithm is used to evaluate the fitting parameters, which then provide a direct measure of the flaw characteristics that can be mapped to the imaged surface for visual reference. The method uses temperature data for the heat transfer analysis, so radiometric calibration of the IR signal is required. The method provides quantitative data with a single thermal event (e.g. acoustic pulse or flash), as compared to phase-lock techniques that require many events. The work has been tested with numerical data but remains to be validated by experimental data, and that effort is underway. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
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Lead chalcogenides are successfully applied at sensors of infrared radiation, thermoelectrical devices, thermogenerator, photoresistances, photodiodes, lasers, tensometers etc. Under high pressures above 2.5 - 6 GPa lead chaclogenides are known to suffer phase transitions, but up to now the thermoelectric properties of these materials at high pressure were unknown. In recent papers it was shown that heterophase state of material, which is being forming in the vicinity of semiconductor-metal phase transformations may be considered as a model of layer fabricated systems. As the most properties being dependent on the concentration and configuration of phases inclusions these materials may be used in engineering. For example, semiconductor-metal phase transitions induced by nanosecond heating and cooling of small regions of the memory cell are known to be using for nonvolatile memory develop. Recently the new technique of thermomagnetic measurements allowing to test a micro-samples of semiconductors have been developed at high pressure up to 30 GPa. The technique was applied for determination of scattering mechanisms and mobilities of charge carriers of direct-gap semiconductors Te, Se at ultrahigh pressure up to 30 GPa. The above measurements seems to be perspective for implementation to microelectronic manufacturing and MEMS technologies, for example, in modeling, quality control or testing of integrated circuit (IC). In present paper the thermo- and galvanomagnetic properties of micro-samples ~ 200×200×20 mkm of lead chalcogenides (PbS, PbSe, PbTe) at high pressure are investigated. The data of transverse magnetoresistance (MR) and also transverse and longitudinal Nernst-Ettingshausen (N-E) effects of lead chalcogenides both for initial and new phases, and also for heterophase states in the vicinity of phase transformations at high pressure are presented. One may suppose that the effects observed will find an interesting applications in thermosense industry. The work is supported by the Russian Foundation for Basic Research, Gr. No. 01-02-17203.
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The purpose of this continued study is to model correctly the concentration of carbon monoxide (CO) in the troposphere of Harrisonburg, VA using an atmospheric modeling software program coupled with an experimental technique. In previous years, multiple raw data sets were collected using a technique known as gas filter correlation radiometry (GFCR) developed at NASA Langley Research Center. This technique utilizes the infrared (IR) radiance of the full moon and combines a ground-based IR data collection system with a blackbody calibration to yield a power value of the radiant stream. The raw data are processed by differencing a radiance stream obtained from the moon as passed through an evacuated cell against a cell containing a fixed concentration of CO. This power value is then compared with those simulated by the atmospheric modeling software HITRAN-PC. HITRAN-PC can simulate the atmosphere of Harrisonburg with a few key changes of input. It can then model the transmittance of the atmosphere, and by applying an algorithm developed in-house, we can correlate this transmission to a corresponding power value. The modeling is performed multiple times with various estimated values of CO, simulating clean and polluted conditions. Once the power value from the data and the power value from the modeling converge, the CO concentration is determined.
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A dual-waveband, fiber-optic/infrared (F-O/IR) temperature measurement system was enhanced with incorporated optical chopping and applied to measure the surface temperature of a coated (aluminized) Kapton HN sample. The F-O/IR system provides a non-contact means for accurate membrane temperature measurement without distorting surface contour. An FTIR spectrometer was used to measure the absorptance and reflectance properties of the Kapton HN sample. A long-wave IR scanner was used to validate and enhance results obtained from the spectrometer and predict temperature dependence of optical properties. Data are presented that demonstrate the feasibility to apply the F-O/IR system for non-contact temperature measurement of highly reflective surfaces at low temperatures.
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This paper presents a summary of recent research activities carried out at our laboratory in the field of Infrared Thermography for Nondestructive Evaluation (TNDE). First, we explore the latest developments in signal improvement. We describe three approaches: multiple pulse stimulation; the use of Synthetic Data for de-noising of the signal; and a new approach derived from the Fourier diffusion equation called the Differentiated Absolute Contrast method (DAC). Secondly, we examine the advances carried out in inverse solutions. We describe the use of the Wavelet Transform to manage pulsed thermographic data, and we present a summary on Neural Networks for TNDE. Finally, we look at the problem of complex geometry inspection. In this case, due to surface shape, heat variations might be incorrectly identified as flaws. We describe the Shape-from-Heating approach and we propose some potential research avenues to deal with this problem.
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Fine water mist can be used to restrain thermal hazard in some special situations, such as information center and telephone exchange center. A set of experiment was conducted to study the interaction of fine water mist with hot objects of different shape. An adjuster was designed to control the surface temperature of them avoiding over-heated. These objects were chosen to simulate the shape of cable and box used in electric equipment. Change of thermal field around these hot objects was measured before and after exertion of fine water mist. The flow procedure of fine water mist on the objects was displayed by an optical system. Vaporization height of fine water mist above different hot object was also measured. The restrain efficiency of fine water mist with different flux but same droplet size is compared. The experiment results serve as reference to engineering application of fine water mist to restrain thermal hazard of electric apparatus.
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In today's life, remote environmental sensing via distributed and remote telemetry stations is a vital demand for pollution control and wildlife protection. However the high cost of sensors and their environmental ruggedness, engineering and equipments' cost, and the complex signal processing are restricting the spread of such technology. This paper is introducing the design and modelling of a compact size environmental telemetry station (CETS) based on passive optical sensors and Fuzzy logic control. Here, the cost reduction and size problems are solved by using the fiber Bragg gratings sensors that are able to detect a wide variety of environmental variables such as temperature, humidity, toxic gases, odours, chemical pollution, water dissolved toxins, level, pressure and many more. Also the complex signal processing problem is solved by using an array of fiber Bragg gratings sensors that coexist on a single fiber core, where their signals are multiplexed and processed in the optical domain without the need to analogue-to-digital conversion. The control and encoding problem is solved by using a Fuzzy logic control algorithm within an imbedded system fitted with a CCD sensor spectrometer.
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A cubic-phase distribution is applied in the design of inexpensive lenses for passive infrared motion sensors. The resulting lenses have the ability to distinguish the presence of humans from pets by the employment of the so-called wavefront coding method. The cubic-phase distribution used in the design can also reduce the optical aberrations present on the system. This aberration control allows a low tolerance in the fabrication of the lenses and in the alignment errors of the sensor.
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The paper will describe the parameters of the IR systems used for inspecting the quality of thermal insulation in rotating kilns used in cement production. The systems are provided with a laser targeting device and a remote radio control device. They include: an 'Introcon-05' IR scanner, a laptop PC, an adapter of the communication line, a synchro-unit and a 'Thermoinspector' software. The latter one allows data filtering and thresholding in order to indicate defect zones. The built-in defect characterization algorithm enables estimates of a residual thickness of the thermal insulation layer. The systems are being used by several Russian producers of cement.
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This paper presents possible hardware solutions for fast, real-time thermal image acquisition, based on PCI with high-speed memory buffering using SDRAMs. A thermographic head equipped with 16 detectors were built to monitor thermal processes with the rate of 1MSample/s. A few application for textiles, glass industry and 3D scene reconstruction show the potentialities of the system.
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This paper presents a study the possibilities of evaluation of thermal parameters for single and multilayer structures using dynamic thermography. Potentialities of both lock-in and pulse thermography is discussed. Simulation for periodic excitation and multilayer composite material is presented. Practically, the described methods are applied for microelectronic multilayer components as well as for nonwovens manufactured from hemp fibers, chemical fibers and with an addition of electrically conducting fibers.
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By using the evaporation of working fluid in the capillary it is possible to design and build cooling device, with high cooling effectiveness. This paper presents a preliminary cooling system integrated with electronic device., which is supported by evaporation and capillarity effects. A simplified modeling of conjugate heat transfer including evaporation using FLUENT package is discussed. The experiments for open and close loop capillary pomp are shown to compare and verify the measurements and simulation results.
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Modern thermal imaging radiometers are infrared systems usually endowed with some means of making surface temperature measurements of objects, as well as providing an image. These devices have evolved considerably over the past few decades, and are continuing to do so at an accelerating rate. Changes are not confined to merely camera size and user interface, but also include critical parameters, such as sensitivity, accuracy, dynamic range, spectral response, capture rates, storage media, and numerous other features, options, and accessories. Familiarity with this changing technology is much more than an academic topic. A misunderstanding or false assumption concerning system differences, could lead to misinterpretation of data, inaccurate temperature measurements, or disappointing, ambiguous results. Marketing demands have had considerable influence in the design and operation of these systems. In the past, many thermographers were scientists, engineers and researchers. Today, however, the majorities of people using these instruments work in the industrial sector and are involved in highly technical skilled trades. This change of operating personnel has effectively changed the status of these devices from a 'scientific instrument', to an 'essential tool'. Manufacturers have recognized this trend and responded accordingly, as seen in their product designs.
This paper explores the history of commercial infrared imaging systems and accessories. Emphasis is placed on, but not confined to, real time systems with video output, capable of temperature measurements.
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