Design considerations and test facilities for accelerated radiation effects testing

Test design parameters for accelerated dose rate radiation effects tests for spacecraft parts and subsystems used in long term mission (years) are detailed. A facility for use in long term accelerated and unaccelerated testing is described

Reliability and effective thermal conductivity of three metallic-ceramic composite insulating coatings on cooled hydrogen-oxygen rockets

An experimental investigation of the structural integrity and effective thermal conductivity of three metallic-ceramic composite coatings was conducted. These coatings were plasma sprayed onto the combustion side of water-cooled, 12.7-centimeter throat diameter, hydrogen-oxygen rocket thrust chambers operating at 2.07 to 4.14 meganewtons per square meter chamber pressure. The metallic-ceramic composites functioned for six to 17 cycles and for as long as 213 seconds of rocket operations and could have probably provided their insulating properties for many additional cycles. The effective thermal conductivity of all the coatings was in the range of 0.7472 to 4.483 w/(m)(K), which makes the coatings a very effective thermal barrier. Photomicrographic studies of cross-sectioned coolant tubes seem to indicate that the effective thermal conductivity of the coatings is controlled by contact resistance between the particles, as a result of the spraying process, and not the thermal conductivity of the bulk materials

Effective thermal conductivities of four metal ceramic composite coatings in hydrogen-oxygen rocket firings

An experimental investigation was conducted to determine the effective conductivities of four plasma-arc-sprayed, metal-ceramic gradated coatings on hydrogen-oxygen thrust chambers. The effective thermal conductivities were not a function of pressure or oxidant-to-fuel ratio. The various materials that made up these composites do not seem to affect the thermal conductivity values as much as the differences in the thermal conductivities of the parent materials would lead one to expect. Contact resistance evolving from the spraying process seems to be the controlling factor. The thermal conductivities of all the composites tested fell in the range of 0.75 to 7.5 watts per meter kelvin

Design considerations for a LORAN-C timing receiver in a hostile signal to noise environment

The environment in which a LORAN-C Timing Receiver may function effectively depends to a large extent on the techniques utilized to insure that interfering signals within the pass band of the unit are neutralized. The baseline performance manually operated timing receivers is discussed and the basic design considerations and necessary parameters for an automatic unit utilizing today's technology are established. Actual performance data is presented comparing the results obtained from a present generation timing receiver against a new generation microprocessor controlled automatic acquisition receiver. The achievements possible in a wide range of signal to noise situations are demonstrated

Archeological Significance Testing at Site 41SR191, Starr County, Texas

The Texas Department of Transportation (TxDOT) conducted archeological significance testing at Site 41SR191, within the right-of-way of proposed improvements to US 83 in Starr County. The site was recorded in 1991 during an archeological survey of additional rights-of-way required for highway improvements. At that time, the site was recorded as a surface scatter of burned rock fragments and lithic debitage in a fallow field, covering an area approximately 50 meters east-west by 150 meters north-south. Although it was thought that the site was unlikely to yield substantial significant information, the site was considered to be one of the two (out of a total of 25 recorded during the survey) most likely to yield significant information. Thus, additional testing was recommended for this site as the project involves federal funding. As the improvements will utilize federal funding, the testing was undertaken under the guidelines of the National Historic Preservation Act of 1966 and its implementing regulations, 36CFR, Part 800, and the National Environmental Policy Act. A total of 120 work-hours was spent on hand-excavation of eight square meters and machine excavation of two trenches, each approximately 40 meters in length and two meters in depth. The testing yielded only five prehistoric biface fragments, none of which was temporally or culturally diagnostic, and relatively small quantities of lithic debitage, all confined within approximately 30 cm of the surface. Historic artifacts were found throughout the same depths of deposit. Thus, it was concluded that the site was extremely disturbed by historic land clearing and cultivation activities, and that the site was unlikely to yield any significant information. It is recommended that no additional cultural resources investigations be carried out at the site, and that the project be allowed to proceed

Physical Acoustics

Contains reports on two research projects.U.S. Navy (Office of Naval Research) under Contract N00014-67-A-0204-001