- Email: [email protected]
The NDT reference standard
inverse problem has been fonnulated. The method is suitable for on-line automated quality-control measurements.
39909 Bushlin. Y.; Notea. A. Sizing of slits by digital radiography
39466 Fry. DA.; Pearsall. C.R.; Guu. A.C. Design considerations for an industrial diode array digital radiographic system
NDT International, Vol. 21, No.6, pp. 397-402 (Dec. 1988) A method for the sizing of cracks from radiographic images is presented. Interpretation is based on a description of the radiographic image generation by theoretical models and characteristics functions detennined from experimental results. The crack was simulated by a rectangular slit The inclination of the crack was expressed by a suitable locally dependent operator, while blurring effects were expressed by a convolutable function. The method has been successfully applied to digitized radiographs of a lucite block containing slits less than I mm wide. The influence of slit size and inclination on the probability of detection has been analysed. The method is suitable for real-time radiographic systems.
Transactions of the American Nuclear Society, Vol. 56, Supplement No.3, p. 70-72 (Conference on Industrial and Radioisotope Measurement Applications, Pinehurst, North Carolina, 7-9 Sep. 1988) Work in the U.S.A. on the evaluation of line-scan diode array radiography (DADR) for a wide variety of industrial applications (welds, castings and electronic assemblies) is described. The advantages of digital overfilm radiography are discussed. Two prototype DADR systems have been constructed and evaluated and a computer model has been developed for perfonnance prediction. This paper concentrates on the inspection of steel welds. The DADR system is described and results given. Image quality and scan rates will be improved in the future.
39908 V.K.
39465 Gentle. D.J.; Spyrou, N.M.; Dhani. A.; Hutchinson. I.G.; Huddleston. J.
Bespalov. V.I.; Zaitsev. A.K.; Kononov. M.Y.; Kuleshov.
Inherent unsbarpness in a gas-discharge converter operating with high- energy X rays Soviet Journal of Nondestructive Testing, Vol. 24, No. I, pp. 59-64 (Jan. 1988) Monte Carlo simulation has been applied to electron and photon transport in calculating absorbed-energy radial distributions in gasdischarge converters in order to estimate the inherent unsharpness for x-ray beams having maximum energies of 6 and 30 Me V. The unsharpness is related to the thickness and material in the front electrode, the gas pressure, and the distance between electrodes. Calculations for 6 MeV are compared with measurements.
39628 Heut. J.; Pauton. M.; Thomas. G.; Casagrande. J.M.; Lagnier. P.; Glasser. F.
The industrial X-ray tomography study of high resolution analyzers Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 3, pp. 2133-2141. Pergamon Press, 3173 pp. (1988) In conjunction with the CEA Company, the INTERCONTROLE Company has made two models of 420 kV X-ray scanners. The characteristics of these machines, some recent results and the high X-ray energy development are presented.
39476
Brase. J.M.; Waltjen. K.E.; Martz. H.E.
Research in computed tomography Lawrence Livermore National Laboratory, UCRL-53868-87 (Thrust Area Report FY87), Section 9, pp. 14-19 (Apr. 1988) The use of computed tomography (Cn imaging has been researched for evaluating materials of interest at LLNL. A microfocus CT system has been demonstrated aimed at high-resolution applications, as well as a pencilbeam cr system for quantitative material evaluation. Given a model of the x-ray imaging system, algorithms have been developed for enhancing the resolution of images. A new reconstruction algorithm has been developed that can easily incorporate a priori knowledge of the specimen being imaged. Reconstruction programs have been used on several systems to compare their performance and have begun to develop an algorithm for the SPRINT architecture.
39475
Christian. J.M.; Mueller. K. Jr.; Schwalbe. L.
High-energy nash radiography of two axisymmetric copper explosively formed penetrators International Advances in Nondestructive Testing, Vol. 13, pp. 365-396 (1987). Edited by W,J. McGonnagle. Gordon and Breach Science Publishers. In-flight radiographic data is presented from two explosively fonned penetrators (EFPs) of copper. The data were obtained with Ector, a high-energy, pulsed x-ray source operating at effective mean energies selectable in the range 0.5-1.5 MeV. The Ector-produced radiation has enough energy and intensity to penetrate several centimeters of copper, and the 50-ns pulse is short enough that motion blur is negligible from objects traveling at 2-3 mm/microsec. The radiographs were first digitized and then subjected to numerical analyses. The results of this work include tomographic reconstructions and accurate detenninations of the internal and external contours of the EFPs, as well as their masses and center-of-mass coordinates. Along with the experimental data, the original design specifications of the two warheads has been made available. The combined information allows detailed comparisons with the results of design code simulations. The data should serve as useful tests for theoretical models of material strength, fracture, and equations of state.
NOT & E International Volume 25 Number 4/5 1992
Scattering and attenuation corrections in emission tomography in nuclear industry applications Transactions of the American Nuclear Society, Vol. 56, Supplement No.3, p. 81-82 (Conference on Industrial and Radioisotope Measurement Applications, Pinehurst, North Carolina, 7-9 Sep. 1988) This prototype scanning rig for use in the nuclear industry will use scattering and attenuation corrections in emission tomography for examining nuclear materials such as fuel rods or radionuclides in waste containers. The rig, which works essentially as a simulator, is controlled by a BBC microcomputer and data is acquired in a single or multichannel analyzers. Image reconstruction is performed using a filtered backprojection program on the micro-computer and on a main frame which provides image processing facilities. Results using the high purity Gennanium detector are superior to those using the sodium iodide detector. The reasons for this are explored.
39464
Sheppard. G A.
Development of a high-resolution inert high-explosives tomography phantom Transactions of the American Nuclear Society, Vol. 56, Supplement No.3, p. 82 (Conference on Industrial and Radioisotope Measurement Applications, Pinehurst, North Carolina, 7·9 Sep. 1988) Work is being carried out in the U.S.A. which aims to use X ray computerised tomography to characterise the density uniformity of chemical high explosives (HE). Safety considerations preclude the actual use of these materials during the system's development, so inert calibration phantoms (test objects for calibration and reference purposes) are also being developed. Density and mass attenuation must both be similar to the HE materials they mimic. Equipment and procedures are described. A suitable phantom density calibration standard called Viton A has been identified and further experiments concerned with radial placement within the sample are planned.
39386
Morgner. W.; Tutzschky. G.
Assessment of defect detectability by statistical models Proceedings of the 4th European conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 844-852. Pergamon Press, 3173 pp. (1988) It is lightweight construction and the role of materials economy with ever rising demands on materials which compel the designer to make increasing use of the safety reserves of materials. In this light there is an enhancing impetus on the reliability of nondestructive inspection methods. It can be appraised by characterising the equivalent flaw size as a random variable and studying its distribution function. Analyzing the patterns of the latter usually reveals markedly asymmetrical distributions which are induced by two components. viz. frequency of the actual flaw size and defect detectability by the particular inspection method. Adopting the probability theory for assessing the outcome of weld inspection by radiography as well as magnetic and potential drop crack testing along with light and electron microscopy, it is demonstrated for definite examples how the reliability of actual test results can be assessed.
38942
Cox. L.D.; Hammer. K.W.
The NDT reference standard Materials Evaluation. Vol. 46, No.6, pp. 702-704 (May 1988) The design, manufacture and use of reference standards in nondestructive testing for ultrasound, radiography and other methods is re-examined critically in this paper.
239
38521
Segal, Y.; Ingman, D.; Bushlin, Y.
Noise and granularity in radiographs Materials Evaluation, Vol. 46, No.4, pp. 513-517 (Mar. 1988) A model handling the noise and granularity in radiographs is presented. The calculated noise level versus film density is compared with experimental results for Agfa Gevaert D4 and D7 films. The agreement is quite good.
38511
Segal, Y.; Triehter, F.
programs were realised by the Monto Carlo method. The following results were obtained: spatial, energy and angle distribution of transmitted photons and spatial distribution of exposure on the detection plane. Analytical relations for determination of spatial distribution of photon energy fl uence and exposure on the detection plane were obtained using the Point Kernel technique. Comparison of these results with experimental results (obtained for several sources and samples), was carried out.
37096 Jacobs, A.M.
Limitations in gap width measurements by X-ray radiography
Compton profile radiography
NDT International, Vol. 21, No. I, pp. 11-16 (Feb. 1988)
International Advances in Nondestructive Testing, Vol. 12, pp. 17-52 (1986)
The use of radiography as a quantitative tool for determining the width and depth of cracks is discussed. It is shown that in most cases the extraction of dimensional information from radiographs may lead to erroneous results. The effects of oblique geometry and a blurring line spread function are modelled. The calculated results are compared with experimental findings.
37600
Najjar, W.S.
The development and application of neutron radiography to study concrete, with emphasis on microcracking Dissertation Abstracts International, Vol. 48, No. I, p. 211 (Jul. 1987) Neutron radiography has been successfully developed and used as a testing method for studying microcracking in concrete. The microcracks in a polished concrete specimen are partially impregnated with a "contrast agent" and subsequently exposed to a neutron flux. The contrast agent is a material with a relatively high neutron attenuation capacity compared to concrete. Gadolinium has been used as the neutron-attenuating contrast agent, which is applied to a polished concrete surface in the form of an aqueous solution of gadolinium nitrate. When a neutron flux is passed through the specimen, neutrons are readily attenuated by the gadolinium in the cracks, which results in a sharp difference in the flux emanating from the cracked and uncracked areas. The resulting radiographs show cracks which are not visible to the unaided eye when directly observing the concrete specimens themselves. Air voids are also identified due to their partial impregnation with the contrast agent. The method is evaluated by comparing it with the more conventional X-ray radiography technique. Neutron radiography appears to be more effective than X-radiography for the identification and study of microcracking in concrete. An analytical model is developed which supports the experimental results. Neutron radiography is successfully applied to study and measure the incidence of microcracking in concrete cylinders as a function of load.
37102
Vujie, J.; Boreli, P.M.; /lie, R.D.
Optimization of radiation defectoscopy parameters by Monte Carlo and Point Kernel technique lIth World Conference on Nondestructive Testing, Las Vegas, Nevada (United States), 3-8 Nov. 1985. Vol. I, pp. 470 -477. Taylor Publishing Co., Dallas (1985). The aim of this work was optimization of radiographic parameters using three parallel methods: Monte Carlo, Point Kernel technique and experimental samples exposing. A mathematical model of spatial photons transport through material with defects, as well as corresponding computer
The detection of Compton scattered photons (one of the significant image noise sources in conventional radiography) can be effectively interpreted to yield density and atomic composition images. There are several unresolved non-destructive (or, in fact, noninvasive) examination situations where such Compton scatter imaging provides a possible solution. The particular technique of Compton profile radiography is described in detail including the methods of reduction of detected photon energy spectra to spatial images of the object. The measurement of two-phase spatial distribution in contained optically opaque fluids is described as a relevant application example. Results of initial simulation experiments are presented and discussed.
36599
Barnea, G.; Dick, C.E.
Coupled electron/photon Monte Carlo calculations of X-ray scattering with application to industrial radiography NDT International, Vol. 20, No.2, pp. 111-115 (Apr. 1987) Monte Carlo transport methods are used to simulate the scattering of Xrays in polystyrene and iron slabs. The calculations are made with monoenergetic X-ray sources in the energy region from 30 keV (100 keV for iron) to 20 MeV. This energy range includes the energy regions for diagnostic radiology (0.003-0.15 MeV), nuclear medicine (0.1-2.0 MeV) and industrial radiography (0.2-20 MeV). The slab thicknesses for polystyrene were 53, 100, and 210 mm and for iron 7 and 14 mm. The present calculations include the effects of secondary electron/positron radiation which become quite important at high energies. As a function of the incident photon energy, the ratio of the scattered to the total radiation (scatter fraction) was found to have a characteristic 'N' shape. Increasing the atomic nun umber of the scattering media has the effect of 'squeezing the N'.
36589
Daum, W.; Rose, P.; Heidt, H.; Builtjes, J.H.
Automatic recognition of weld defects in x-ray inspection British Journal of Nondestructive Testing, Vol. 29, No.2, pp. 79-81 (Mat. 1987) The main basis for automatic image analysis in X-ray inspection of welds is a segmentation algorithm which detects and marks the defects reliably in the radiograph. The problem for the defect segmentation is that in many cases, the defect representation is superimposed on other image structures due to the shape of the welding seam. By a sophisticated background modelling technique it is nevertheless possible to achieve automatic defect recognition. A comparison between a visual and an automatic evaluation shows the efficiency of this method.
Each entry in NDT Abstracts consists of the serial number in the National NDT Centre Information Store for identification purposes; the title of the paper, book or report; the name of the author; the name of the source journal or document and the abstracts. Where necessary, author's names and the title offoreignjournals have been transliterated into the Latin alphabet according to British Standard BS 2979: 1958.
Information Service, US Department of Commerce, Springfield, Virginia 22151, USA. British and foreign standards can be obtained from Sales Department, British Standards Institution, 101 Pentonville Road, London Nl 9ND; and British and foreign patents from the Patents Office Sales Branch, Block C, Station Square House, St Mary Cray, Orpington, Kent BR5 3RD.
Availability of Publications
Information-retrieval Service
Most papers listed may be obtained as loans or copies via local library or direct from Loans Department, British Library Document Supply Centre, Boston Spa, Wetherby, Yorkshire LS23 7BQ. Details of the British Lending Library's UK and International Services may be obtained from The Director, British Library Lending Division. Technical reports are also available from the Loans Department of the British Lending Library and in the USA from the National Technical
240
All entries are indexed in a computerized retrieval system, located at Harwell, which allows rapid searching of information relevant to any particular inspection problem. This service is available to both UK and overseas organizations through the National NDT Centre's Qualtis Subscription Scheme - further details are available from Phil Lawrence on Abingdon (0235) 433391.
©
1992 United Kingdom Atomic Energy Authority
N DT & E International Volume 25 Number 4/5 1992
39909 Bushlin. Y.; Notea. A. Sizing of slits by digital radiography
39466 Fry. DA.; Pearsall. C.R.; Guu. A.C. Design considerations for an industrial diode array digital radiographic system
NDT International, Vol. 21, No.6, pp. 397-402 (Dec. 1988) A method for the sizing of cracks from radiographic images is presented. Interpretation is based on a description of the radiographic image generation by theoretical models and characteristics functions detennined from experimental results. The crack was simulated by a rectangular slit The inclination of the crack was expressed by a suitable locally dependent operator, while blurring effects were expressed by a convolutable function. The method has been successfully applied to digitized radiographs of a lucite block containing slits less than I mm wide. The influence of slit size and inclination on the probability of detection has been analysed. The method is suitable for real-time radiographic systems.
Transactions of the American Nuclear Society, Vol. 56, Supplement No.3, p. 70-72 (Conference on Industrial and Radioisotope Measurement Applications, Pinehurst, North Carolina, 7-9 Sep. 1988) Work in the U.S.A. on the evaluation of line-scan diode array radiography (DADR) for a wide variety of industrial applications (welds, castings and electronic assemblies) is described. The advantages of digital overfilm radiography are discussed. Two prototype DADR systems have been constructed and evaluated and a computer model has been developed for perfonnance prediction. This paper concentrates on the inspection of steel welds. The DADR system is described and results given. Image quality and scan rates will be improved in the future.
39908 V.K.
39465 Gentle. D.J.; Spyrou, N.M.; Dhani. A.; Hutchinson. I.G.; Huddleston. J.
Bespalov. V.I.; Zaitsev. A.K.; Kononov. M.Y.; Kuleshov.
Inherent unsbarpness in a gas-discharge converter operating with high- energy X rays Soviet Journal of Nondestructive Testing, Vol. 24, No. I, pp. 59-64 (Jan. 1988) Monte Carlo simulation has been applied to electron and photon transport in calculating absorbed-energy radial distributions in gasdischarge converters in order to estimate the inherent unsharpness for x-ray beams having maximum energies of 6 and 30 Me V. The unsharpness is related to the thickness and material in the front electrode, the gas pressure, and the distance between electrodes. Calculations for 6 MeV are compared with measurements.
39628 Heut. J.; Pauton. M.; Thomas. G.; Casagrande. J.M.; Lagnier. P.; Glasser. F.
The industrial X-ray tomography study of high resolution analyzers Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 3, pp. 2133-2141. Pergamon Press, 3173 pp. (1988) In conjunction with the CEA Company, the INTERCONTROLE Company has made two models of 420 kV X-ray scanners. The characteristics of these machines, some recent results and the high X-ray energy development are presented.
39476
Brase. J.M.; Waltjen. K.E.; Martz. H.E.
Research in computed tomography Lawrence Livermore National Laboratory, UCRL-53868-87 (Thrust Area Report FY87), Section 9, pp. 14-19 (Apr. 1988) The use of computed tomography (Cn imaging has been researched for evaluating materials of interest at LLNL. A microfocus CT system has been demonstrated aimed at high-resolution applications, as well as a pencilbeam cr system for quantitative material evaluation. Given a model of the x-ray imaging system, algorithms have been developed for enhancing the resolution of images. A new reconstruction algorithm has been developed that can easily incorporate a priori knowledge of the specimen being imaged. Reconstruction programs have been used on several systems to compare their performance and have begun to develop an algorithm for the SPRINT architecture.
39475
Christian. J.M.; Mueller. K. Jr.; Schwalbe. L.
High-energy nash radiography of two axisymmetric copper explosively formed penetrators International Advances in Nondestructive Testing, Vol. 13, pp. 365-396 (1987). Edited by W,J. McGonnagle. Gordon and Breach Science Publishers. In-flight radiographic data is presented from two explosively fonned penetrators (EFPs) of copper. The data were obtained with Ector, a high-energy, pulsed x-ray source operating at effective mean energies selectable in the range 0.5-1.5 MeV. The Ector-produced radiation has enough energy and intensity to penetrate several centimeters of copper, and the 50-ns pulse is short enough that motion blur is negligible from objects traveling at 2-3 mm/microsec. The radiographs were first digitized and then subjected to numerical analyses. The results of this work include tomographic reconstructions and accurate detenninations of the internal and external contours of the EFPs, as well as their masses and center-of-mass coordinates. Along with the experimental data, the original design specifications of the two warheads has been made available. The combined information allows detailed comparisons with the results of design code simulations. The data should serve as useful tests for theoretical models of material strength, fracture, and equations of state.
NOT & E International Volume 25 Number 4/5 1992
Scattering and attenuation corrections in emission tomography in nuclear industry applications Transactions of the American Nuclear Society, Vol. 56, Supplement No.3, p. 81-82 (Conference on Industrial and Radioisotope Measurement Applications, Pinehurst, North Carolina, 7-9 Sep. 1988) This prototype scanning rig for use in the nuclear industry will use scattering and attenuation corrections in emission tomography for examining nuclear materials such as fuel rods or radionuclides in waste containers. The rig, which works essentially as a simulator, is controlled by a BBC microcomputer and data is acquired in a single or multichannel analyzers. Image reconstruction is performed using a filtered backprojection program on the micro-computer and on a main frame which provides image processing facilities. Results using the high purity Gennanium detector are superior to those using the sodium iodide detector. The reasons for this are explored.
39464
Sheppard. G A.
Development of a high-resolution inert high-explosives tomography phantom Transactions of the American Nuclear Society, Vol. 56, Supplement No.3, p. 82 (Conference on Industrial and Radioisotope Measurement Applications, Pinehurst, North Carolina, 7·9 Sep. 1988) Work is being carried out in the U.S.A. which aims to use X ray computerised tomography to characterise the density uniformity of chemical high explosives (HE). Safety considerations preclude the actual use of these materials during the system's development, so inert calibration phantoms (test objects for calibration and reference purposes) are also being developed. Density and mass attenuation must both be similar to the HE materials they mimic. Equipment and procedures are described. A suitable phantom density calibration standard called Viton A has been identified and further experiments concerned with radial placement within the sample are planned.
39386
Morgner. W.; Tutzschky. G.
Assessment of defect detectability by statistical models Proceedings of the 4th European conference on Non-Destructive Testing, London (United Kingdom), 13-17 Sep. 1987. Vol. 2, pp. 844-852. Pergamon Press, 3173 pp. (1988) It is lightweight construction and the role of materials economy with ever rising demands on materials which compel the designer to make increasing use of the safety reserves of materials. In this light there is an enhancing impetus on the reliability of nondestructive inspection methods. It can be appraised by characterising the equivalent flaw size as a random variable and studying its distribution function. Analyzing the patterns of the latter usually reveals markedly asymmetrical distributions which are induced by two components. viz. frequency of the actual flaw size and defect detectability by the particular inspection method. Adopting the probability theory for assessing the outcome of weld inspection by radiography as well as magnetic and potential drop crack testing along with light and electron microscopy, it is demonstrated for definite examples how the reliability of actual test results can be assessed.
38942
Cox. L.D.; Hammer. K.W.
The NDT reference standard Materials Evaluation. Vol. 46, No.6, pp. 702-704 (May 1988) The design, manufacture and use of reference standards in nondestructive testing for ultrasound, radiography and other methods is re-examined critically in this paper.
239
38521
Segal, Y.; Ingman, D.; Bushlin, Y.
Noise and granularity in radiographs Materials Evaluation, Vol. 46, No.4, pp. 513-517 (Mar. 1988) A model handling the noise and granularity in radiographs is presented. The calculated noise level versus film density is compared with experimental results for Agfa Gevaert D4 and D7 films. The agreement is quite good.
38511
Segal, Y.; Triehter, F.
programs were realised by the Monto Carlo method. The following results were obtained: spatial, energy and angle distribution of transmitted photons and spatial distribution of exposure on the detection plane. Analytical relations for determination of spatial distribution of photon energy fl uence and exposure on the detection plane were obtained using the Point Kernel technique. Comparison of these results with experimental results (obtained for several sources and samples), was carried out.
37096 Jacobs, A.M.
Limitations in gap width measurements by X-ray radiography
Compton profile radiography
NDT International, Vol. 21, No. I, pp. 11-16 (Feb. 1988)
International Advances in Nondestructive Testing, Vol. 12, pp. 17-52 (1986)
The use of radiography as a quantitative tool for determining the width and depth of cracks is discussed. It is shown that in most cases the extraction of dimensional information from radiographs may lead to erroneous results. The effects of oblique geometry and a blurring line spread function are modelled. The calculated results are compared with experimental findings.
37600
Najjar, W.S.
The development and application of neutron radiography to study concrete, with emphasis on microcracking Dissertation Abstracts International, Vol. 48, No. I, p. 211 (Jul. 1987) Neutron radiography has been successfully developed and used as a testing method for studying microcracking in concrete. The microcracks in a polished concrete specimen are partially impregnated with a "contrast agent" and subsequently exposed to a neutron flux. The contrast agent is a material with a relatively high neutron attenuation capacity compared to concrete. Gadolinium has been used as the neutron-attenuating contrast agent, which is applied to a polished concrete surface in the form of an aqueous solution of gadolinium nitrate. When a neutron flux is passed through the specimen, neutrons are readily attenuated by the gadolinium in the cracks, which results in a sharp difference in the flux emanating from the cracked and uncracked areas. The resulting radiographs show cracks which are not visible to the unaided eye when directly observing the concrete specimens themselves. Air voids are also identified due to their partial impregnation with the contrast agent. The method is evaluated by comparing it with the more conventional X-ray radiography technique. Neutron radiography appears to be more effective than X-radiography for the identification and study of microcracking in concrete. An analytical model is developed which supports the experimental results. Neutron radiography is successfully applied to study and measure the incidence of microcracking in concrete cylinders as a function of load.
37102
Vujie, J.; Boreli, P.M.; /lie, R.D.
Optimization of radiation defectoscopy parameters by Monte Carlo and Point Kernel technique lIth World Conference on Nondestructive Testing, Las Vegas, Nevada (United States), 3-8 Nov. 1985. Vol. I, pp. 470 -477. Taylor Publishing Co., Dallas (1985). The aim of this work was optimization of radiographic parameters using three parallel methods: Monte Carlo, Point Kernel technique and experimental samples exposing. A mathematical model of spatial photons transport through material with defects, as well as corresponding computer
The detection of Compton scattered photons (one of the significant image noise sources in conventional radiography) can be effectively interpreted to yield density and atomic composition images. There are several unresolved non-destructive (or, in fact, noninvasive) examination situations where such Compton scatter imaging provides a possible solution. The particular technique of Compton profile radiography is described in detail including the methods of reduction of detected photon energy spectra to spatial images of the object. The measurement of two-phase spatial distribution in contained optically opaque fluids is described as a relevant application example. Results of initial simulation experiments are presented and discussed.
36599
Barnea, G.; Dick, C.E.
Coupled electron/photon Monte Carlo calculations of X-ray scattering with application to industrial radiography NDT International, Vol. 20, No.2, pp. 111-115 (Apr. 1987) Monte Carlo transport methods are used to simulate the scattering of Xrays in polystyrene and iron slabs. The calculations are made with monoenergetic X-ray sources in the energy region from 30 keV (100 keV for iron) to 20 MeV. This energy range includes the energy regions for diagnostic radiology (0.003-0.15 MeV), nuclear medicine (0.1-2.0 MeV) and industrial radiography (0.2-20 MeV). The slab thicknesses for polystyrene were 53, 100, and 210 mm and for iron 7 and 14 mm. The present calculations include the effects of secondary electron/positron radiation which become quite important at high energies. As a function of the incident photon energy, the ratio of the scattered to the total radiation (scatter fraction) was found to have a characteristic 'N' shape. Increasing the atomic nun umber of the scattering media has the effect of 'squeezing the N'.
36589
Daum, W.; Rose, P.; Heidt, H.; Builtjes, J.H.
Automatic recognition of weld defects in x-ray inspection British Journal of Nondestructive Testing, Vol. 29, No.2, pp. 79-81 (Mat. 1987) The main basis for automatic image analysis in X-ray inspection of welds is a segmentation algorithm which detects and marks the defects reliably in the radiograph. The problem for the defect segmentation is that in many cases, the defect representation is superimposed on other image structures due to the shape of the welding seam. By a sophisticated background modelling technique it is nevertheless possible to achieve automatic defect recognition. A comparison between a visual and an automatic evaluation shows the efficiency of this method.
Each entry in NDT Abstracts consists of the serial number in the National NDT Centre Information Store for identification purposes; the title of the paper, book or report; the name of the author; the name of the source journal or document and the abstracts. Where necessary, author's names and the title offoreignjournals have been transliterated into the Latin alphabet according to British Standard BS 2979: 1958.
Information Service, US Department of Commerce, Springfield, Virginia 22151, USA. British and foreign standards can be obtained from Sales Department, British Standards Institution, 101 Pentonville Road, London Nl 9ND; and British and foreign patents from the Patents Office Sales Branch, Block C, Station Square House, St Mary Cray, Orpington, Kent BR5 3RD.
Availability of Publications
Information-retrieval Service
Most papers listed may be obtained as loans or copies via local library or direct from Loans Department, British Library Document Supply Centre, Boston Spa, Wetherby, Yorkshire LS23 7BQ. Details of the British Lending Library's UK and International Services may be obtained from The Director, British Library Lending Division. Technical reports are also available from the Loans Department of the British Lending Library and in the USA from the National Technical
240
All entries are indexed in a computerized retrieval system, located at Harwell, which allows rapid searching of information relevant to any particular inspection problem. This service is available to both UK and overseas organizations through the National NDT Centre's Qualtis Subscription Scheme - further details are available from Phil Lawrence on Abingdon (0235) 433391.
©
1992 United Kingdom Atomic Energy Authority
N DT & E International Volume 25 Number 4/5 1992