PubMed · 14187264
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R C HAYGOOD, K S TEEL, C P GREENING. 1964. LINK ANALYSIS BY COMPUTER.. https://doi.org/10.1177/001872086400600109
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Radiofrequency countermeasures (i.e., chaff) may be released by fighter jets during tactical countermeasures training. Chaff cartridges, pistons, and endcaps (i.e., chaff dispenser materials), all currently made of styrene, are also released into the environment. Accumulation of chaff dispenser materials in the environment is a concern of the Department of Defense. The US Navy is exploring the possibility of constructing degradable chaff dispenser components made of biodegradable polymers. Five polymers are being considered. Degradability and toxicity tests are two of several criteria being used to evaluate various available biodegradable options. Dissolution products from four of five polymers being considered were toxic to aquatic organisms with LC50s/LOELs ranging between 1.24 and 731.30 mg total organic concentration/L. Supernatant from dissolving a 90:10 polyester amide/polyvinyl alcohol copolymer in water for 24h inhibited shoot growth of Brassica rappa and Lepidium sativum. Since our results were obtained using fractions of saturated degradable polymer solutions (1 or 10 g/L), we conclude that the tested degradable polymers were of low toxicity to the seven aquatic organisms and two terrestrial plant species used in our assays. However, our characterization of the toxicity of these degradable polymers may not be applicable to all species or environmental situations. Information gained from these studies will be used for making decisions on which polymers should be used in the engineering of environmentally friendly chaff dispenser cartridges, pistons, and endcaps.
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In order to investigate the influence of aircraft shielding on the galactic component of cosmic rays, an aircraft mathematical model has been developed by the combinatorial geometry package of the Monte-Carlo transport code FLUKA. The isotropic irradiation of the aircraft in the cosmic ray environment has been simulated. Effective dose and ambient dose equivalent rates have been determined inside the aircraft at several locations along the fuselage, at a typical civil aviation altitude (10 580 m), for vertical cut-off rigidity of 0.4 GV (poles) and 17.6 GV (equator) and deceleration potential of 465 MV. The values of both quantities were generally lower than those in the free atmosphere. They depend, in an intricate manner, on the location within the aircraft, quantity of fuel, number of passengers, etc. The position onboard of crew members should be taken into account when assessing individual doses. Likewise due consideration must be taken when positioning detectors which are used to measure H*(10). Care would be needed to avoid ambiguity when comparing the results of calculation with the experimental data.