In 1960, the Frankford Arsenal began a new program in dynamic photo-elasticity using low modulus photoelastic materials subjected to either mechanical or explosive loads. High-speed photographic techniques were used to obtain full-image dynamic stress patterns at approximately 7500 pictures per second and exposures of 1.3p sec. Recently, a special polariscope was designed for obtaining simultaneous views of a specimen at normal and oblique incidence. This paper reviews the techniques developed for this work, discusses the results of fundamental studies in stress distributions under dynamic conditions, and outlines future plans.
Utilizing a ring shaped transducer with a 7 inch clear-through center hole this new Microgon shaft encoding system has achieved a standard deviation accuracy of 0.26 seconds of arc when operated at a resolution of 221 or 2,097,152 counts per turn. The ring-type transducer is suitable for radar on-axis installations with waveguides passing through the center. Other applications include rate tables and tracking instrument mounts. This Micro gon system comprised of a transducer, transducer controls, dual preamplifiers, and one box of transistorized electronics has been developed for natural binary or 8, 4, 2, 1 coded decimal outputs of digit and complement with visual displays. Two of these systems are in use on ADVENT radar antennas.
Many people believe it has only been recently that government and science, have been associated. It is true that the degree of the association has increased since World War II, but our government and governors have, since the beginning, had a deep interest in science. Washington was an engineer, Jefferson is known for his scientific knowledge - in fact we can mark off in the early days and down through the years a number of actions demonstrating a government concern with science and scientific activities. In the first year that Washington took office, 1790, the Patent Office was created, and in 1832 a grant for experimental research was made to the Franklin Institute. The Smithsonian Institute came into being in 1846. These are only indications of the types of activities that occurred from the beginning until now.
There are three image displacements inherent in aerial panoramic photogz-raphy which are not present in the more conventional frame and strip record. They are: 1) panora"mic distortion arising from the cylindrical format, 2) sweep motion displacement due to the movement of the aircraft and 3) image motion compensation displacements caused by the changing positions of the lens relative to the film during sweep. This paper presents a derivation of the latter two displacements, and in addition derives the necessary image motion compensation (IMC) velocity or blur distance for cameras with no IMC. The case considered is the panoramic camera intentionally tilted in the direction of flight. For the vertical panoramic camera the derivation of these displace-ments has previously been published in "Photogrammetric Engineering" and is therefore not included.