The DART is a new telescope architecture consisting of a single aperture formed from two cylindrical parabolic reflectors. The system is ideally suited to using tensioned membranes for the reflective surfaces, owing to the zero Gaussian curvature of a cylindrical parabola. In this paper, we present experimental measurements for shaping the membranes by using curved boundary elements to achieve coarse shaping, and a pair of precision rails shaped by moments and forces at the ends, and lightly pushed into the surface, to provide flne shape control. An experimental testbed has been constructed to demonstrate the ideas using a 70cm by 80cm membrane reflector. A highly adjustable and precise membrane surface is achievable on the testbed through the use of precision mechanical design practices. Results from measuring the membranes using a scanning profilometer and from center of curvature testing are presented. * Corresponding author. gregory.s.agnes@jpl.nasa.gov, AIAA t AIAA Senior Member Senior MemberAIAA
This small-plot trial evaluated efficacy of granular insecticides in a commercial production field near Beardsley, Minn. Plots of 1 row (30-inch spacing) by 50 ft were arranged in a randomized complete block design with 4 replicates. Granular insecticides were applied to whorl stage corn 8 Jul when temperatures were 70-75°F and there were light variable winds. A one-row, electrically driven Gandy granular insecticide applicator was used to apply all treatments. Insecticide performance was evaluated 9 Aug by dissecting 10 infested plants/plot and counting the tunnels.
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