Eighteen profile lines from Fort Story south to the Virginia-North Carolina State line were surveyed monthly for 27 months (Sep 74 to Dec 76). Net volume changes were moderate, with maximum rates of accretion at the north and south ends of the study area. A statistical analysis using earlier surveys going back to Nov 56 confirms the pattern of accretion in the north and south separated by erosion in the ...
A piezoelectric material produces an electrical signal when subjected to a mechanical stress. Traditional examples of this effect have been demonstrated by certain ceramic materials and inorganic crystals. Recently, certain organic polymers, when properly treated (by both orientation and polarization), have exhibited this phenomenon. The purpose of our research in piezoelectric polymers is to prepare and characterize organic films for evaluation as transducer elements in devices, such as microphones, accelerometers, ...
A program on the mechanical and dynamic properties of rubber toughened acrylic polymers has led to advanced materials. Improvements were achieved through the modification of polymethylmethacrylate (PMMA) by inclusion of rubber particles in the polymeric matrix. In the investigation a series of rubber modified acrylics was examined over a range of rubber contents from zero to 16 percent with marked improvements in the ballistic resistance being obtained. (Author)
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