Chemical Lasers
The laser, an acronym for light amplification by stimulated emission of radiation, is a source of nearly monochromatic, coherent, electromagnetic radiation that propagates as a beam. The chemical laser is a type of laser system that is driven by the release of energy during a chemical reaction. Chemical lasers are usually large, high power devices that integrate chemical delivery systems, a supersonic flow apparatus, and an optical resonator.
Role of mixing in the chemical oxygen-iodine laser reactions
The thin shear-layer equations are solved for a two-dimensional parallel jet of molecular iodine I 2 , in an electronically excited, singlet-delta oxygen freestream, O 2 ( 1 Δ), in an effort to better understand the influence of mixing on the dissociation of I 2 . Comparisons of one-dimensional premixed cases with corresponding two-dimensional let-mixed cases of varying jet velocity ratios (and therefore mixing rates) indicate that, counter to common belief, imperfect mixing, which results in initial regions of high I 2 concentrations, can lead to faster dissociation
In search of optimum chest radiography techniques.
A nation-wide study of chest radiography in Sweden had previously revealed a large variation in the physical and technical factors involved, in particular the radiation dose. In this study the image quality could not be assessed unambiguously. The aim of the present study was to try to establish a correlation between visual grading of radiographs and physical and technical factors in order to find the optimum chest X-ray system. The physical and technical performance of 24 chest units was evaluated. Radiographs were taken of an anthropomorphic chest phantom supplied with test structures simulating various pathologies. Image quality was assessed by visual grading analysis of the radiographs. The physical and technical parameters of the units rated best were used to exemplify good radiographic practice. The results were in agreement with the recommendations issued by the Commission of the European Communities (CEC). It was also shown that low radiation dose is compatible with high-quality radiographic imaging of the chest.