Imaging Process Control for Mining and Cominution of Construction Materials
Extraterrestrial mining activities will at first be concerned with the production of construction materials. Rock and earth materials can provide the strongest and most cost effective solutions. Scarce resources (energy, human intervention) in extraterrestrial mining operations, will limit many types of activities. At the same time, construction materials need to be processed, including blasting, crushing, screening, and milling, to exact specifications. Automation is the key to minimizing resource utilization, and optical sizing is crucial for these tasks, enabling automated process control without requiring excessive human quality control strategies.
WipFrag image based granulometry system
Quick and accurate measurements of size distribution are essential to managing fragmented rock and other materials. WipFrag is an automated image based granulometry system that uses digital image analysis of rock photographs and video tape images to determine grain size distributions. WipFrag images can be digitized from fixed video cameras in the field, or using roving camcorders. Photographic images can be digitized from slides, prints or negatives, using a desktop copy stand. Digital images in a variety of formats, delivered on disk or over electronic networks, can be used. WipFrag uses powerful image analysis techniques to isolate the individual fragment boundaries. Edge detection is optimized by setting Edge Detection Variables (EDV). Manual editing can be used to improve the fidelity of edge detection. WipFrag has the facilities for zoom-merge analysis, where the combined analysis of images taken at different scales of observation can be used to overcome the size limitations inherent with a single image. Alternatively, an empirical calibration mode is available.
Mottle on computed radiographs of the chest in pediatric patients.
PURPOSE
To investigate the relationship between radiation exposure and perceived mottle at bedside pediatric chest examinations performed with screen-film and computed radiographic techniques.


MATERIALS AND METHODS
In a pediatric intensive care unit, chest radiographs were obtained with both computed radiography (60 radiographs) and a 600-speed screen-film system (14 radiographs). The relative radiation exposure was estimated by using the sensitivity value obtained in the processing of each computed radiograph. Five radiologists assessed the mottle present in the computed radiographs and screen-film images.


RESULTS
For computed radiographs, the perceived level of mottle was inversely related to radiation exposure. For the same radiation exposure, the perceived mottle on computed radiographs was significantly higher than that on screen-film images (P < .001 for small cassettes; P < .01 for large cassettes).


CONCLUSION
Pediatric computed radiography of the chest requires approximately twice the exposure of a 600-speed screen-film system to attain the same level of mottle.