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U and Th bearing carbides, EuB6 and YB6 were studied to determine how these materials would react in the thermal and chemical environments associated with thermionic applications. Some of the data obtained includes: Thermal shock resistance of the U bearing carbides is, very probably, inadequate for applications which require that the fuel emitter retain structural integrity under thermal cycling and/or severe temperature gradient conditions. Thermophysical properties, thermal conductivity, electrical resistivity, and emissivresponding oxide materials and approach properties exhibited by metallic materials. Vapor pressure properties of the rare earth borides indicate an upper temperature limit in the neighborhood of 1400 C. Work functions of bulk carbides generally fall slightly below that of W. Cs compatibility tests showed the very marked sensitivity of carbon-rich carbide materials to Cs attack in time periods less than 500 hours. TY OF CARBIDE MATERIALS ARE SUPERIOR TO CORRESPONDING OXIDE MATERIALS AND APPROACH PROPERTIES EXHIBITED BY METALLIC MATERIALS. Vapor pressure properties of the rare earth borides indicate an upper temperature limit in the neighborhood of 1400 C. Work functions of bulk carbides generally fall slightly below that of W. Cs compatibility tests showed the very marked sensitivity of carbon-rich carbide materials to Cs attack in time periods less than 500 hours. Boride materials, on the other hand, appear resistant to Cs attack.

Each service's material probably will be carried by rail, truck, ship or airplane from factory to the ultimate consumer. Despite similarity of total vibration environment, at least seven different vibration tests are prescribed. Emphasis is on developing a theoretical basis for a laboratory test since theory will define the numerical values of the shipping environment which should be collected. A modern statistical theory (theory of random vibration) is indicated. Equations show content mean square response in terms of suspension natural frequency and damping ratio and the environmental characteristics of acceleration spectral density and bandwidths. Linear fatigue accumulation concepts are used as a basis for realistically shortening test times. Two expressions equate sinusoidal test response amplitude and time with field time and the field response amplitude previously derived. The equations show that it is sufficient, when evaluating the suspension, to vibrate at a single frequency, preferably the lowest resonant.

Cloud Puff III was a joint-services research effort in cold cumulus seeding. AFCRL participants placed primary emphasis on searching out and testing new methods appropriate to aircraft-oriented field research in cloud modification. Under separate contract each of the various procedural aspects involved in the preparation, execution, and postoperational phases of the Cloud Puff III project has been examined in detail. A field data laboratory has been designed and equipped, and computer programs have been written for each of the aircraft mission functions., Errata sheet inserted.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.