Two Systems for Direct Radiographic Miniaturization
The direct miniaturization of radiographic images is discussed, and two systems are analyzed in detail. The performance and relative advantages of a large, high-performance X-ray image intensifier (¿18-in or 46-cm diameter) and an optically coupled radiographic intensifier are presented. These systems are estimated to have comparable performance and costs. The X-ray image intensifier system is superior in quantum efficiency and gain, while the radiographic intensifier is superior in contrast. While, as expected, the resolution, contrast, and sensitivity of these systems are not as good as a conventional screen-film cassette system under all circumstances, their performance may be adequate for all but the most demanding radiologic applications.
X-ray exposure reduction using rare-earth oxysulfide intensifying screens.
Abstract The characteristics of terbium-activated gadolinium oxysulfide and lanthanum oxysulfide are compared with those of calcium tungstate. The new rare-earth phosphors have higher x-ray absorption in the 38 to 70 keV region relative to calcium tungstate. They also exhibit a larger x-ray-to-visible light energy conversion efficiency. Rare-earth phosphors, however, emit primarily in the green spectral region and thus poorly match the spectral response of blue-sensitive x-ray film. Despite this disadvantage, gadolinium oxysulfide screens allow a significant x-ray exposure reduction relative to calcium tungstate screens providing equivalent resolution. An additional exposure reduction is anticipated when faster green-sensitive x-ray film becomes available.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.