A pilot program for selecting, editing, and disseminating engineering and scientific educational subject matter from NASA technical reports Quarterly report, Mar. 1 - May 31, 1968

Statistics on NASA program of disseminating educational monographs and visual briefs to industries and universitie

Ellipsoidal-mirror reflectometer accurately measures infrared reflectance of materials

Reflectometer accurately measures the reflectance of specimens in the infrared beyond 2.5 microns and under geometric conditions approximating normal irradiation and hemispherical viewing. It includes an ellipsoidal mirror, a specially coated averaging sphere associated with a detector for minimizing spatial and angular sensitivity, and an incident flux chopper

Use of a computer model in the understanding of erythropoietic control mechanisms

During an eight-week visit approximately 200 simulations using the computer model for the regulation of erythopoiesis were carries out in four general areas: with the human model simulating hypoxia and dehydration, evaluation of the simulation of dehydration using the mouse model. The experiments led to two considerations for the models. Firstly, a direct relationship between erythropoietin concentration and bone marrow sensitivity to the hormone and, secondly, a partial correction of tissue hypoxia prior to compensation by an increased hematocrit. This latter change in particular produced a better simuation of the effects of hypoxia on plasma erythropoietin concentrations

Observation of a cascaded process in intracavity terahertz optical parametric oscillators based on lithium niobate

Cascaded difference frequency generation has been observed in intracavity optical parametric oscillators based on bulk lithium niobate and producing nanosecond pulses of terahertz radiation. Two idler waves are generated, namely: the primary idler wave associated with the parametric down conversion process itself; and a secondary idler wave, due to difference frequency generation. Experimental investigations of the frequency, temporal evolution, propagation direction, intensity, phase matching and oscillation threshold of the generated down-converted waves are reported. The overall generation efficiency for the terahertz radiation is enhanced, thereby overcoming the Manley-Rowe limit. Advantages of the present approach over schemes based on periodically poled lithium niobate are identified.Publisher PDFPeer reviewe

Dual turbopump liquid hydrogen feed system experience

Design and development of dual turbopump liquid hydrogen feed syste

Multi-channel GaAs-based planar gunn diodes

We present a multi-channel GaAs-based planar Gunn diode. By introducing extra channels, the output RF power has been significantly improved compared to single-channel GaAsbased planar Gunn diodes. For a 1.14 μm length and 60 μm wide device, the highest power achieved was approximately -4 dBm operating in fundamental mode at 109 GHz, and -26.6 dBm at its second-harmonic at 218 GHz