Showing papers on "Thermography published in 1978"

Detection of delamination in bridge decks with infrared thermography

Abstract: The use of infrared thermography to define very accurately variations in surface temperatures was evaluated as a means of defining delaminated areas caused by corrosion of reinforcing steel in concrete bridge decks. Differences in the temperatures of the deck surface, shown in various shades or colors on a cathode-ray tube, were photographed to provide a permanent graphic record of the location of the warmer, distressed areas. In a comparative study of infrared thermography and conventional deck evaluation techniques, including the sounding of the surface with a hammer and chain drag and the use of a rolling delamination detector, all were found generally satisfactory in locating severe to medium delaminations. However, the infrared thermography procedure had important advantages in disclosing incipient delaminations, those in which the cracking is confined to the close vicinity of the reinforcing steel, and in providing detailed records of the separated areas. /Author/

Condition monitoring by thermography

Abstract: Thermography techniques are used to monitor both the temperature and the temperature pattern of equipment in operation. This information, together with data on the physical construction of the component and the thermodynamic state of the equipment is used to evaluate the degree of deterioration of an item of process plant. Three successful applications of thermography to different industries are described.

Thermographic Tumor Detection Enhancement Using Microwave Heating

Abstract: Infrared thermography offers a viable alternative to X-ray mammography for early breast cancer detecetion if the inherent Iow sensitivity of the technique can be improved. This paper presents results which indicate that the sensitivity of thermography is increased by irradiating the examined area with microwaves. This arises because of selective absorption characteristics of the particular tumor tissue investigated; specifically, it has been observed that in situ irradiation of transplantable guinea pig hepatoma, using 2450-GHz microwave radiation, results in a tumor temperature rise of 5.5/spl deg/C and a rise of 2.5/spl deg/C in the surrounding healthy tissue. This spatial gradient of 3/spl deg/C compares with the relevant unheated spatial gradient of approximately 0.5/spl deg/C. The microwave-induced increased temperature differential between tumor and healthy tissue is easily observed using a thermovision camera. Data regarding the temporal evolution of spatial temperature distributions associated with tumor tissue before, during, and after microwave irradiation are presented. Additional data are included regarding the heating and cooling rates of microwave-irradiated tumors. The data show conclusively that the specific tumor investigated selectively absorbs microwave energy in situ and exhibits this selective absorption as a thermographically observable increase in local skin surface temperature. The data further show that tumor heating and cooling rates are faster than for healthy tissue.

Experimental observations of coronary blood flow using the thermographic camera.

Abstract: From the Department of Thoracic and Cardiovascular Surgery and the Department of Cardiology, Charlotte Memorial Hospital, Charlotte, North Carolina, and from the Department of Cardiology, University Medical School of Hannover, German Federal Republic. This work was supported with grants from the Heineman Medical Research Center of Charlotte and from the Minna-James-Heineman Stiftung of Germany. At the turn of the century, Sir William Herschel showed that the beam of light split through a prism generates both heat and electromagnetic radiation which is strongest beyond the red end of the visible spectrum. Further studies demonstrated that this infrared band is fairly wide, that the amount of radiation emitted is proportional to the generated heat, and that it is regulated by the same laws that govern the course and behavior of other electromagnetic waves. These observations gave birth to a new branch of physical science: thermography. The word thermography denotes pictorial recording of temperature. It should not be confused with direct infrared photography taken with an ordinary

Measurement of the temperature increases generated in soft tissue by ultrasonic diagnostic Doppler equipment.

Abstract: Temperature increases on the body surface from the use of two different ultrasonic Doppler blood flow meters were determined experimentally. Using a thermographic method it was shown that the temperature increase can be significant. Two continuous wave ultrasonic Doppler blood flow meters induced temperature increases on the body surface of 12.5°C and 2.3°C respectively, after an insonation time of 100 sec. Theoretical estimates and experimental results have shown an approximate agreement in the values of the temperature increase.

Arthritis inflammation monitored by subcutaneous millimeter wave thermography.

Abstract: A new technique for remote, noninvasive mapping of temperature elevations of the human joints is described; it uses the mm wave radiation emitted by the human body. A solid state switched scanner for 68 GHz is described which overcomes the depth limitations of conventional, infrared thermographs and can measure to subcutaneous depths of several mm with a temperature resolution of 0.25 degrees C. Measurements on rheumatoid arthritic knee joints are presented which show little correlation with simultaneously measured skin temperatures. Significant longterm thermographic changes induced by steroid injection indicate a potential for objective patient monitoring and development of new treatment methods.

Quantitative thermography of the knee joint

Abstract: Computer-assisted evaluation of thermography of the knee joints allows diagnosis and quantitation of inflammatory processes. This needs an adequate thermography camera, registration standards and a thermographic index. With the aid of this index normal knee joints and those with inflammatory changes can clearly be differentiated: an index of less than 3.5 is normal, values above 5.0 indicate an inflammation. The author proposes to correct the thermographic index with reference to actual rectal temperature in order to improve inter- and intra-individual comparability of thermograms. Apart from the thermographic index, the formal analysis of the line-scan over the joint space and the maximal temperature of the joint can be used as further diagnostic criteria.

Aerial thermography for energy conservation

Abstract: Thermal infrared scanning from an aircraft is a convenient and commercially available means for determining relative rates of energy loss from building roofs. The need to conserve energy as fuel costs makes the mass survey capability of aerial thermography an attractive adjunct to community energy awareness programs. Background information on principles of aerial thermography is presented. Thermal infrared scanning systems, flight and environmental requirements for data acquisition, preparation of thermographs for display, major users and suppliers of thermography, and suggested specifications for obtaining aerial scanning services were reviewed.

Thermographic thorax diagnostics

Abstract: Among several variants of devices the infra-red thermography has obtained a wide technical perfection allowing to measure the thermal energy emitted from the body surface without contact, quickly and dynamically, and to produce a picture for analysis. Since numerous functional and pathophysiological proceedings are connected with changes of temperature, the use of thermography for diagnosis of processes near the body surface may be recommended. Based on thermic observations in 63 patients and a control experiment in 15 persons, experiences with the thermography in the diagnosis of diseases, which are localized more profoundly in the thoracic cavity, were reported.

Evaluation of distortion in clinical thermography

Abstract: Distortions appearing on the thermograms can depend on a number of factors, including the radiation coefficient, the ambient temperature, the angle between the sighting direction of the thermograph and the normal of the study surface. A quantitative assessment made of distortions conditioned by these factors during registration of thermograms of flat and curvilinear surfaces helped to recommend the most expedient manipulations in conducting thermographic examinations.

Thermography based on thermal activity measurements

Abstract: A thermographic method was proposed, according to which in addition to even heating, the material is simultaneously sounded with transient temperature fields; the recording of these fields contains quantitative information about the coefficient of thermal activity of the material. A study was made of rapid heating of the material on transition through the melting point.