Prevention of failures in production plants is one of the main objectives of an industry. Cost incurred in maintenance procedures forms a lion share of the expenditures of an industry. So it is essential to reduce this maintenance costs. Preventive maintenance was the key word till the late 1970’s. Today we have the predictive maintenance. With this procedure we are actually predicting a failure before a failure actually occurs. Thermal imaging, which is a technique of producing a thermal graph of the temperature rise caused in plant equipment due to the failures caused mainly due to faulty connections, leaks etc. has now been the most innovative technique for this purpose. Thermal imaging finds vast applications. In this seminars in addition to the procedures for predictive maintenance made in production plant various other applications of thermal imaging are also discussed.
Thermal imaging (Infrared thermography) is a technique that produces a visible graph or thermographic image of thermal energy radiated from objects. The human eye can only see the narrow middle band of visible light that encompasses all the colours of light in the rainbow. Thermography utilizes a portion of the infrared band of the electromagnetic spectrum between approximately 1 and 14 microns. Thermal infrared images translate the energy transmitted in the infrared wavelength into data that can be processed into a visible light spectrum video display. Thermal infrared imagers are detector and lens combinations that give a visual representation of infrared energy emitted by all objects. In other words thermal imagers let you “see” heat.
Depending upon the sophistication used, thermography is capable of providing very detailed images of situations invisible to the naked eye. Thermal imaging thus finds its applications in different fields.
2.1 ELECTROMAGNETIC RADIATION
Electromagnetic radiation is emission of energy from a source, which could be a solid, liquid or gas. This radiation is given off in the form of alternating electric, magnetic waves produced by the acceleration and deceleration of charged electric particles. Although the electromagnetic spectrum is comprised of many different types of electromagnetic radiation there are similarities that must be recognized. As mentioned all electromagnetic radiation is produced by the movement of electric particles. A second point is that all electromagnetic radiation, unhindered by gases, travels at the speed of light. As the intensity of the radiation increases, the wavelength becomes shorter and the frequency becomes higher. On the other hand as the intensity decreases, the wavelength becomes longer and the frequency lower. The main difference between the various classes of electromagnetic radiation is the wavelength and frequency, as well as the way it is produced and the “equipment” used to detect it. The chart below depicts the many classifications of electromagnetic radiation and their relation to one another.
FIG 2.1: ELECTROMAGNETIC SPECTRUM
The amount of energy in light wave is related to its wavelength. Of visible light violet has the most energy red has least. Just next to visible light spectrum is infrared spectrum
Infrared light can be split into 3 different categories:
NEAR Infrared: closest to visible light wavelength range from 0.7-1.3 microns
MID Infrared: has wavelengths ranging from1.3-3 microns, both near IR and mid IR are used by variety of electronic devices, including remote controls.
THERMAL Infrared: occupying in the largest part of infrared spectrum, this has wavelengths ranging from 3microns -over 3microns.
The key difference between thermal IR and other two is that thermal IR is emitted by an object instead of reflected of it. Infrared rays are emitted because of what’s happening at the atomic level.
Atoms are constantly in motion. They continuously vibrate, move and rotate. Even the atoms that make up the chairs that we sit in are moving around. Solids are actually in motion! Atoms can be in different states of excitation. In other words, they can have different energies. If we apply a lot of energy to an atom, it can leave what is called the ground-state energy level and move to an excited level. The level of excitation depends on the amount of energy applied to the atom via heat, light or electricity.
An atom consists of a nucleus (containing the protons and neutrons) and an electron cloud. Think of the electrons in this cloud as circling the nucleus in many different orbits. Although more modern views of the atom do not depict discrete orbits for the electrons, it can be useful to think of these orbits as the different energy levels of the atom. In other words, if we apply some heat to an atom, we might expect that some of the electrons in the lower energy orbitals would transition to higher energy orbitals, moving farther from the nucleus.
FIG 2.2: An atom has a nucleus and an electron cloud.
Once an electron moves to a higher-energy orbit, it eventually wants to return to the ground state. When it does, it releases its energy as a photon -- a particle of light. You see atoms releasing energy as photons all the time. For example, when the heating element in a toaster turns bright red, the red color is caused by atoms excited by heat, releasing red photons. An excited electron has more energy than a relaxed electron, and just as the electron absorbed some amount of energy to reach this excited level, it can release this energy to return to the ground state. This emitted energy is in the form of photons (light energy). The photon emitted has a very specific wavelength (color) that depends on the state of the electron's energy when the photon is released.
Anything that is alive uses energy, and so do many inanimate items such as engines and rockets. Energy consumption generates heat. In turn, heat causes the atoms in an object to fire off photons in the thermal-infrared spectrum. The hotter the object, the shorter the wavelength of the infrared photon it releases. An object that is very hot will even begin to emit photons in the visible spectrum, glowing red and then moving up through orange, yellow, blue and eventually white.
3. WORKING METHOD OF INFRARED THERMOGRAPHY
1. A special lens focuses the infrared light emitted by all of the objects in view.
2. The focused light is scanned by a phased array of infrared-detector elements. The detector elements create a very detailed temperature pattern called a thermo gram. It only takes about one-thirtieth of a second for the detector array to obtain the temperature information to make the thermo gram. This information is obtained from several thousand points in the field of view of the detector array.
3 The thermo gram created by the detector elements is translated into electric impulses.
4 The impulses are sent to a signal-processing unit, a circuit board with a dedicated chip that translates the information from the elements into data for the display.
5. The signal-processing unit sends the information to the display, where it appears as various colors depending on the intensity of the infrared emission. The combination of all the impulses from all of the elements creates the image.
Image courtesy of Infrared, Inc.
FIG 3:The basic components of a thermal-imaging system
The infrared portion of the electromagnetic spectrum is from 1 to 1000 microns. All objects above absolute zero (-273) emit electromagnetic radiation in the form of infrared radiation. This energy is emitted from the first 1/1000of an inch of the surface of an object. Infrared thermographic instruments are non-contact, non-intrusive systems that see only infrared energy from the 1/1000 of most objects. Contrary to common belief they do not see through or into most of the common objects in the world today. In general thermo graphic instruments, known as either short wave (2-6 microns), or long wave (8-14microns) systems can see the emitted energy from objects that are approximately –35 Celsius or higher. These systems are not dependent on reflection of visible light or higher temperatures. As long as there objects above temperature of –35C an infrared thermo graphic system will see as well as in total darkness as it will in full sunlight.
It can see through all kind of impediments, obstructions and barriers; air borne precipitations (rain, snow, flow); darkness (heavy cloud cover, night, power blackouts);liquids (oil, coolants, large bodies of water); and even solid objects.
3.1 BASIC COMPONENTS OF THERMAL IMAGING SYSTEM
Fig: 3.1BASIC COMPONENTS OF THERMAL IMAGING SYSTEM
Electronic instruments used in infrared thermography utilize lens system. The lenses are made of expensive, IR transparent materials, such as germanium, Silicon or Zinc Selinide. These lenses are not transparent to visible light. All infrared systems, from the simple to the complicated, are sensitive to infrared radiated energy only. The photonic infrared energy emitted by objects, is focused by lens on to a specialized detector. The detectors in many systems today are uncooled thermal detectors made from materials such as Vanadium Oxide and Barium Strontium Titan ate. Other detector materials such as Indium Antimonite and Indium Gallium Arsenide are also in use in variety of infrared thermo graphic systems. Most of the newer systems on the market today are Focal Plane Arrays, FPAs. These systems have high resolution compared to the old single element infrared cameras, being comprised of 320 X 240 individual detector elements which produce a display made up of 76,800 picture element s or pixels. High-resolution infrared images are now possible with these commercially available instruments due to fact that the most FPAs use over 75,000 detector elements in the production of each infrared image.
FIG3.1.1: FOCAL PLANE ARRAY
Radiometric FPAs use an onboard computer system to perform a series of complicated functions to calculate scene temperatures. These temperatures are only valid when a trained, experience operator input series of accurate parameters.
Thermal imagers may have any one of the three common detector types, flying spot, scanning and line array
A Flying spot detector is a single point detector scanned to build an image.
A scanning detector is a line detector that scans to produce an image
An array detector is a 2D array of sensors or detectors.
Most infrared detectors must be kept at a constant temperature ranging from -100 °c to -196°c. Therefore they have cooling mechanisms in their design. These may be thermoelectric, liquid nitrogen, active built in cryogenic cooling or detector may not be cooled at all.
The energy that strikes the detector in the cameras is converted to an electrical impulse. These impulses are amplified by a transistor amplifier. The amplified signals are fed to a processor attached to a printed circuit board. The processor to the printed circuited board (PCB) generates a video type image on a CRT or LCD display screen in black & white or a series of selectable color pallets. Each energy level is represented by a different color or grey scale level. This image is viewed by a observer on LCD or a CRT display. The image can be stored digitally or on video, for review, analysis and reporting at a later date.
In general, the higher the temperature of the object or area in the field of view, the brighter the color on the screen. An infrared thermo graphic image is representative of the thermal patterns in the scene and has no relation whatsoever to what our eye sees in the visible. Infrared thermo graphic cameras do not see through glass, plexi-glass or other materials that are transparent in the visible wave lengths. More advanced cameras can also measure this radiated energy and through the use of an onboard computer give calculated temperatures.
These temperatures are only valid if the operator is well trained and can input the proper parameter values. This type of thermo graphic system is called an imaging radiometer or a quantitative infrared system. Infrared thermo graphic systems that do not calculate temperatures but only display an image are simply called images or qualitative devices.
Infrared thermo graphic systems are capable of seeing energy emitted by most objects at a temperature above –35C. Infrared thermo graphic systems do see in the dark. The drawback is that when the humidity is high, the effective range of vision is reduced.
Color or visible light usually does not have anything to do with what an infrared thermo graphic system will ‘see”. The image produced by a thermograhic system is generally a representation of the temperature or thermal patterns of the scene being viewed, not its color or other visual qualities.
3.2 TYPES OF THERMAL IMAGING DEVICES
Most thermal-imaging devices scan at a rate of 30 times per second. They can sense temperatures ranging from -4 degrees Fahrenheit (-20 degrees Celsius) to 3,600 F (2,000 C), and can normally detect changes in temperature of about 0.4 F (0.2 C).
(Fig. 3.2a): It is quite easy to see everything (Fig. 3.2b)...but at night, you can see very during the day... little.
(Fig3.2c):Thermal imaging lets you see again.
There are two common types of thermal-imaging devices:
• Un-cooled - This is the most common type of thermal-imaging device. The infrared-detector elements are contained in a unit that operates at room temperature. This type of system is completely quiet, activates immediately and has the battery built right in.
• Cryogenically cooled - More expensive and more susceptible to damage from rugged use, these systems have the elements sealed inside a container that cools them to below 32 F (zero C). The advantage of such a system is the incredible resolution and sensitivity that result from cooling the elements. Cryogenically-cooled systems can "see" a difference as small as 0.2 F (0.1 C) from more than 1,000 ft (300 m) away, which is enough to tell if a person is holding a gun at that distance.
4. PREDICTIVE MAINTENANCE IN INDUSTRIES
Infra red imaging is a powerful and versatile inspection technique used increasingly in process monitoring, electrical /mechanical preventive maintenance, structural inspection and other manufacturing application that benefit from real time thermal evaluation.
In a manufacturing plant, it is not simple to figure Return on Investment (ROI). If we can detect a problem before it becomes a failure and schedule the repair during a plant shut down, then we can avoid loss of equipment that we purchased. Thermal imaging cameras can detect problems that are not detectable in other inspections.
Large, medium and small operations have an extensive inventory of equipment requiring an uninterrupted power source for operation; an unscheduled shut down is a disaster. Because plants and facilities run around the clock, 365 days a year, downtime is equivalent to lost revenue. To prevent such losses, all electrical components in the plant can be scanned with the thermal infrared imaging camera for suspect hot spots. Some areas that can be thermally scanned are circuit breakers, transformers, fuses, disconnect switches, bus, panels etc. Once the problem has been detected with an infrared imager, proper measures can then be applied for correction. Companies use infrared images and thermographers to detect hotspots in electrical equipment in plants. By scanning substations, distribution lighting panels, an electrical motors. Problems are easily and quickly eliminated before they cause system failure.
The results: avoidance of costly operations downtime.
Fig:4 (a) Everything looks fine on the visible image of the circuit board burned (b)But the thermography clearly shows the overheating ICs radiating infrared energy
By taking a thermograph of site electrical panels, thermographers develop and read a “heat picture” which reveals components that are overloaded or may become faulty. Unlike normal component operating conditions, faulty components exhibit readily detectable temperature increases over the ambient temperature profile. Thermography verifies that electrical connections are properly made and maintained. Thermography also detects hot spots that might be overlooked by visual inspections. Recently, in U.S factory staff quickly interrupted the power supply to an above ground trailer when infrared test equipment detected a hot spot registering 123 degrees over the baseline ambient temperature. A fire could have started, resulting in the probable loss of valuable records and equipment, had the problem not been uncovered.
Most electrical problems within industrial facilities are manifested or are accompanied by temperature changes as an effect prior to failure. For this reason IR thermography has become a integral part of most predictive/preventative maintenance programs . Infrared cameras can pick up small changes in temperature not visible to the human eye. It is non-contact, non-destructive and fairly simple method of detecting impending electrical problems.
4.1 INFRARED THERMOGRAPHY SOFTWARE
ManagIR is an infrared database software program designed to help manage infrared predictive maintenance program. It allows to keep track of the equipment in program, infrared inspections by date, the frequency of inspections anomalies as well as print out a detailed report. The report includes a list of all equipment inspected which has no problems, all equipment in the list that was not inspected for whatever reason, and all equipment inspected which had an anomaly. The fourth part of the report contains images and the detailed information for each image.
A number of specific, detailed reports can be created which allow the user to examine trends and be proactive in your infrared maintenance programs. An equipment list can be easily created to ensure that all of the equipment in a specific list is inspected at the selected frequency
5. APPLICATIONS OF THERMAL IMAGING
5.1 MULTI SPECTRAL THERMAL IMAGER (MTI)
MTI is a satellite used to remotely monitor the production of nuclear and chemical weapons around the globe. Once operating as planned, the 1,305-pound (587-kilogram) satellite peer down on earth with a telescopic eye, “seeing” in 15 spectral bands—ranging from the visible to long wave infrared. The satellite will test the ability to spot from space the telltale signs of weapons production, such as cooling ponds near nuclear reactors and traces of dust associated with the processing of uranium ore. If all goes well, the satellite could spawn future spacecraft that could be used to monitor nonproliferation treaties and keep tabs on weapons production by nations. There are an awful lot of environmental effects that are by proliferate activities. Our hope is through multi-spectral and thermal imaging we can observe those kinds of modest differences. Among the target areas is the Savannah River Site in Aiken, South Carolina, where the government began producing nuclear materials for use in atomic bombs in the 1950s. The site, the source of Plutonium-238 used on NASA’s deep space probes is home to 35 million gallons of high-level radioactive waste. Confirmation that MTI can spy from space what is more identifiable from the ground could then lead to future satellites that could be pressed into the hunt for previously unknown or undisclosed weapons factories across the globe. The satellite will also be able to map chemical spills, vegetation spills, vegetation health and volcanic activity. It can determine with a high degree of precision the brightness of an object. Brightness, the result of either reflected sunlight or emissions, can indicate the presence of dusts associated with ore processing or the large amounts of heat produced by nuclear reactors.
5.2 DETECTION OF FAILURE OF PLASTICS
Thermal wave imaging combined with Stress Pattern Analysis by measurement of Thermal Emission (SPATE) is used to study the failure behavior of a polypropylene(PP) +ethylene propylene diene(EPDM) blend. Images corresponding to a propagating crack in a single edge- notched specimen at three rates of testing: 4mm/min, 8mm/min and 20 mm/min. Conversion to stress values is made through use of a thermo elastic function. It is found that in the 4mm/min tests the crack tip radii blunts rather than propagates with little initiation. Large-scale necking precedes fracture. At 8mm/min, some blunting occurs followed by rapid crack propagation. At 20mm/min, rapid crack propagation occurs. The images are digitized to obtain the values of the temperatures at every point in the sample. Data corresponding to the plane of the propagating crack over the span of the propagating crack over the span of the test are presented.
Byname of EARTH RESOURSES TECHNOLOGY SATELLITE (erts), any of a series of unmanned U.S scientific satellites. The first three Land sat satellites were launched in 1972, 1975 and 1978. These satellites were primarily designed to collect information about the Earths natural resources, including the location of mineral deposits and the conditions of forests and farming regions. They were also equipped to monitor atmospheric and oceanic conditions and to detect variations in pollution level and other ecological changes. All three satellites carried various types of cameras, including those with infrared sensors. Land sat cameras provided images of surface areas 115 miles (184 km) square; each such area could be photographed at 18-day intervals. These pictures were the basis of a far more comprehensive survey than could be made from airplanes. A fourth Land sat satellite was launched in 1982 and a fifth in 1984. The newer models contained two sensors, a multispectral scanner and the thermatic mapper (which provides 100-foot (30-metre) spatial resolution in seven spectral bands). Pollutants such as oils, chemicals and waste matter emit or radiate heat differently than the soil or water around them. Consequently, these pollutants cannot only be seen by an investigator, they can tracked back to their source Airborne emissions from illegal night time burning operations can be traced upstream; and dump sights can be covertly monitored in total darkness, resulting the arrest and conviction of the violators.
5.4STUDY OF ASTRONOMICAL OBJECTS
Study of astronomical objects through observations of the infrared radiation that they emit. Various types of celestial objects –including the planets of the solar system,stars, nebulae, and galaxies—give off energy at wavelengths in the infrared region of the electromagnetic spectrum (i.e. from about one micrometer to one millimeter). The techniques of infrared astronomy enable investigators to examine many such objects that cannot otherwise be seen from the earth because the light of optical wavelengths that they emit is blocked by intervening dust particles. Infrared astronomy originated in the early 1800’s with the work of the British astronomer Sr.William Herschel, who discovered the existence of infrared radiation while studying sunlight. Astronomers have surveyed the sky at the relatively short infrared wavelength of 2.2 micrometers and identified approximately 20000 sources in the northern hemispheric sky alone. Since that time, balloons, rockets and spacecraft have been employed to make observations of infrared wavelengths from 35 to 350 micrometers. Radiation at such wavelengths is absorbed by water vapour in the atmosphere, and so telescopes and spectrographs have to be carried to high altitudes above most of the absorbing molecules.
5.5 ARIAL AND GROUND BASED IR LEAK DETECTION
Although infrared equipment is a valuable diagnostic tool, it merely provides a “map” of radiant energy. It cannot for e.g.: give a definite answer to why a particular area is at a certain temperature or radiating at a certain emissivity, skilled interpretation can be valuable source of advice in this area. High-resolution thermal imaging has proven to be a versatile technique for identifying pipeline (or reservoir) anomalies in rural areas in addition to identifying environmental effects such as discharge into watercourses. The pipeline is flown in a series of tracks, the number of which depend on the pipeline route. Each of these related by an on-screen time stamp to the real time video data. This map is then marked with any thermal anomalies noted and used as the basis for discussions with pipeline management staff who are familiar with possible valid causes for many of the anomalies (such as pipe furniture for e.g.).
This is often provided in parallel with the tabulated list of anomalies, their track number, time/date stamp, classification of priority (high, medium, low) and appropriate commend. Feedback from pipeline teams indicates that the sensitivity is sufficient to detect damp patches smaller than those, which would emanate from a weeping joint. Considerable man-hours are expended in analyzing and tabulating the data. Carrying out an aerial survey of rural trunk water distribution can bring numerous benefits, not only are their immediate engineering benefits, but also the opportunity for positive PR coverage.
5.6 AIR TERMINAL AUTOMATION
Standard terminal automation replacement (STARS) is a high –resolution radar situation display that provides air traffic controllers with bright, crisp penetration of air craft position and flight information. STARS is switching from conventional electro optical systems to a advanced iR imaging. Developed with technology used for Department of Defence programmes, STARS is modernizing and upgrading terminal automation systems nationwide, replacing critical air traffic control software and computers with the next generation of technologies. The system features an open architecture that uses modern workstation computers connected by high speed LANS.
FIG:5.6 (a)Uncooled Image of Car Engine 5.6(b) IR image shows heat in this recently used drill.
Night Drivers infrared thermal imaging system enables Drivers to see up to 5 times further than with headlights alone. Using a camera mounded to acars front grill, the system projects for the driver a real time video image on the wind shield. Warm objects such as people, animals and automobiles are easily detected and displayed. And because its unaffected by ambient light, Night Driver enables drivers to see beyond oncoming headlight glare.
It has also been used in conjunction with other technologies to provide a total perspective of the operating conditions of equipment and processes. Infrared is now being integrated with technologies such as Global Positioning Systems (GPS), to provide much more comprehensive information in both the forest industry and electrical distribution industry.
5.8 BUILDING INSPECTIONS
Building inspections have been an accepted application for thermography since 1970s. Missing insulation, air filtration/ exfiltration, poor window seals etc. can be identified under the right conditions. In a conventional built up flat roof structure, areas of moisture infiltration can be located quickly and accurately by a properly trained thermographer. These areas can be identified by their warm image signatures under certain environmental conditions, often saving the building owner thousands of rupees.
5.9.1 INFILTRATION AND BASE DEFENSE SYSTEM
Infrared sensors on the ground, or in a aircraft or space craft, can detect such hot spots as motor – vehicle engines, missile exhausts, even campfires. They have good location accuracy and high sensitivity to signals, without registering such false targets as sun reflections. In the very near infrared region, infrared imaging detectors use specially sensitized photographic film to reveal forms hidden by camouflage. More important are the detectors used in the far infrared region; objects at room temperature radiate sufficient energy for detection at ranges of several miles. Infrared imagery can have longer range than the image intensifiers and operate without starlight. When the humidity is high, the effective range is reduced.
FIG:5.9 Application in warfare
Growth of insurgency warfare has made necessary the development of a variety of sensors to detect vehicles and the personal in the jungle along trails or on roads. Infrared radar and Doppler radar (radars that detect movement by shift in frequency of received signals) are the sensors. The sensors are connected to processing centers where the progress of an infiltrating column or truck convoy can be monitored. This process eliminates much false detection due to random noise or animals. Because the sensors are widespread and the processing quite sophisticated, the systems have been known as the instrumented battlefield or electronic barrier. Aerial reconnaissance has grown in importance; it now encompasses all phases of warning.
Direct receiving and image recording infrared equipment in night reconnaissance, high resolution radar in bad weather, and conventional photography all contribute to medium and long term warning by observing tactical preparations or discerning new military capabilities. Manned aircraft are used more frequently than other platforms for these sensors. Unmanned air craft, however, flying at high and low altitudes; helicopters, including small unmanned helicopters; and space vehicles were all used for various reconnaissance missions. After the launching of the first soviet satellite, Sputnik 1, in 1957, the potential of observations from space vehicles became obvious and various applications were developed. Infrared imaging from rockets was undertaken in 1966. A model for military Reconnaissance was built in 1972, but by this time photography from airplanes had been shown to be feasible. Satellite platforms can carry a variety of sensors. Cameras in space can collect infrared images, or television – type signals. Radars can be carried aloft for operation at night or through clouds that could otherwise obscure the images. Infrared sensors can be used to detect missiles, or space warnings. Sensors to detect nuclear explosions can also be used to monitor possible violations of the nuclear test treaty. To be useful, the sensors must have high resolution. New system of flash spotting became possible, using infrared sensors to detect the position of a fired gun.
5.9.2 THERMAL PHOTOGRAPHY
Images formed by infrared and heat radiations can recorded directly, on films sensitive to them, or directly, by photographing the image produced by some other system registering infrared radiation. Silver halide emissions can be sensitized to infrared rays with wavelengths up to around 1,200 nanometers (one nanometer is 1/1,000,000 of a millimeter). The usual sensitivity range is 800 to 1,000 nanometers. Direct infrared recording aerial photography shows up ground features of different infrared reflection but similar light reflection (e.g., different types of foliage) and cuts through haze and mist. Special color films with a infrared sensitive layer and processed to colors different from the natural rendering (false co lour films) shows up such differences still more clearly. In forensic photography infrared pictures reveal ink alterations in forgeries, differentiate stains, and help to identify specific textiles and other materials.
5.9.3 IN-FLIGHT TARGETING
A winged surface-to-surface missile, the Tomahawk was first used in Operation Desert Storm in 1991, where it earned its reputation as the “weapon of choice” against heavily defended targets. Launched from surface ships or submarines, the Tomahawk follows a pre- programmed mission and navigates by comparing what it “sees” on the ground to what is stored in its memory. Its see’s using infrared thermal imagers for equity of vision during day and night. It has proven effective against targets up to 1000 miles away.
It is the abbreviation of MISSILE DEFENCE ALARM SYSTEM. It is a series of unmanned U.S military satellites developed to provide warning against surprise attacks by Soviet intercontinental ballistic missiles. Midas was the first such warning system in the world. Launched during the early 1960s, the reconnaissance satellites were equipped with infrared imagers capable of detecting the heat of the ballistic missile’s rocket exhaust shortly after firing. To provide global coverage, The Midas satellites were placed into polar orbits.
• Equine preventative checkup for lameness prevention
• Human medicine
• Verification of soft tissue injury to insurance fraud
In medicine infrared photographs show subcutaneous blood vessels, as the skin is transparent to infrared.
FIG: 5.10 APPLICATIONS IN MEDICINE
With suitable equipment it is possible to convert an infrared image into one visible on a Fluorescent screen, where it can be photographed. In infrared scanner systems a moving mirror scans the object or scene and focuses the radiation onto an infrared sensitive cell. The cell generates electric signals to modulate a light source, which, in turn, scans photographic film or paper synchronously with the mirror. The resulting image records hotter and colder parts of the object as lighter and darker areas and can accurately establish actual temperatures of subject details. This system has been used to record temperature variations in the skin.
The work of a firefighter Warm body in a dark, smoke-filled room can be seen
FIG: 5.10.1 APPLICATIONS IN FIRE FIGHTING
Thermal imaging has now been very effective in reducing the maintenance cost in industries. With this technique it has now been possible to have better idea of the Return on Investment (ROI). Better and more sophisticated thermal imaging cameras has now been developed which has improved the use of these cameras for predictive maintenance.
By introducing thermal imagers into an industrial plant we have the following benefits.
• They establish a baseline measurement for observing the effectiveness of a company’s ergonomics program.
• Assist with the assessment of employees at risk for work-related injuries.
• Help determine the physical capacity of the worker in relation to the physical requirements of the job.
• Identify WMSDs (work-related musculoskeletal disorders) more efficiently.
• Help to reduce worker’s compensation costs.
• Help to reduce indirect costs such as time off and false claims.
• Provide objective findings
• Facilitate better medical management and control.
1) Monochrome and colour television- R.R. GULATI, October 1989
2) Engineering Optics by Brijlal and Subramanian.
5) Engineering heat transfer – SACHDEVA R.C
I express my deep gratitude to almighty, the supreme guide, for bestowing his blessings up on me in my entire endeavor.
I would to like to express my sincere thanks to Dr. T. N. SATHYANESAN Head of Department of Mechanical engineering for all his assistance.
I wish to express my deep sense of gratitude to Lecturer Mr.RENJITH B.S, Department of Mechanical Engineering who guided me throughout the seminars. His overall direction and guidance has been responsible for the successful completion of the seminars.
Finally, I would like to thank all the faculty members of the department of mechanical engineering and my friends for their constant support and encouragement.