Abstract: An underwater acoustic reflector and method for making an acoustic underwater reflector is described herein whereby electrodes are immersed in an aqueous electrolyte solution and thereafter connected to a supply of electrical current. The electrodes are selected such that bubbles form on at least one of the electrodes, providing a layer of acoustic reflective bubbles. Control of the reflectivity properties according to the intensity of the electrolyzing current is also described.

Abstract: This invention relates to a dynamic photoelasticimeter with a rotating birefringent element. It comprises a laser, a birefringent plate rotatable at a constant speed, a model to be studied, a circular analyzer and a photodetector supplying signals at its output having frequency components of 2.omega. and 4.omega.. The ratio of the amplitudes of these signals supplies an indication of the phase shift .phi. (t) contributed by the model, and the phase of the signal of the frequency 4.omega. contributes information as to the orientation .theta. of the axes of the model at the point in question.The present invention provides a particularly simple and accurate dynamic photoelasticimeter.

Abstract: This disclosure relates to an automatic firearms having a rotatable drum with helical grooves therein so arranged as to cause a follower guided by said grooves to reciprocate at a speed proportional to the rotational speed of the drum. The reciprocation of the follower causes the breech mechanism to reciprocate between loading and firing positions. The drum is driven by means independent of the propulsion energy of the projectiles fired, and therefore, may be operated at varying speeds by means such as an electric motor or even by hand.

Abstract: Di or polyfunctional macromolecular compounds having a terminal functional group at each end of the molecule are produced by selectively cleaving the carbon-carbon double bonds of an unsaturated polymer by the oxidizing action of a ruthenium tetroxide oxidizing system. The compounds are useful as components in crosslinked plastics materials, in binders for rocket fuels, and as components in tri or polysequential copolymers.