Silicon strain sensors enable pressure measurement at cryogenic temperatures

Miniature pressure transducers with diffused, heavily doped silicon strain-gage sensor elements, operates over a wide temperature range. Small thermal mass combined with close coupling between a metallic diaphragm and sensor elements minimizes sensitivity to temperature transients

Nuclear waste disposal in space

Work on nuclear waste disposal in space conducted by the George C. Marshall Space Flight Center, National Aeronautics and Space Administration, and contractors are reported. From the aggregate studies, it is concluded that space disposal of nuclear waste is technically feasible

Flap noise and aerodynamic results for model QCSEE over-the-wing configurations

Noise spectra in three dimensions and aerodynamic data were measured for a model of the NASA quiet clean short-haul experimental engine (QCSEE) over-the-wing configuration. The effects of flap length, nozzle exhaust velocity, and nozzle geometry were determined using a single nozzle and wing-flap segment. The scaled-up model data is representative of full scale flap noise with the QCSEE engine

Ablative resin Patent

Ablative resins used for retarding regression in ablative materia

Thermally stable laminating resins Final report

Polyimide resin and resin reinforced composite

Automated weld torch guidance control system

A device for automatically controlling the movement of a welding torch while welding an elongated joint is described. A charge injection television camera is carried on a movable support. The camera includes a matrix of individual light sensing video elements which generate voltages responsive to light reflected off of the joint and surrounding areas of the work piece. The voltages produced by the pixels are converted to digital words which are fed to a microprocessor for generating an error signal. This error signal is fed to a digital motor which is used to drive a movable support upon which the television camera is carried

Finite momentum condensation in a pumped microcavity

We calculate the absorption spectra of a semiconductor microcavity into which a non-equilibrium exciton population has been pumped. We predict strong peaks in the spectrum corresponding to collective modes analogous to the Cooper modes in superconductors and fermionic atomic gases. These modes can become unstable, leading to the formation of off-equilibrium quantum condensates. We calculate a phase diagram for condensation, and show that the dominant instabilities can be at a finite momentum. Thus we predict the formation of inhomogeneous condensates, similar to Fulde-Ferrel-Larkin-Ovchinnikov states.Comment: 7 pages, 4 figures, updated to accepted versio

Automatic weld torch guidance control system

A highly reliable, fully digital, closed circuit television optical, type automatic weld seam tracking control system was developed. This automatic tracking equipment is used to reduce weld tooling costs and increase overall automatic welding reliability. The system utilizes a charge injection device digital camera which as 60,512 inidividual pixels as the light sensing elements. Through conventional scanning means, each pixel in the focal plane is sequentially scanned, the light level signal digitized, and an 8-bit word transmitted to scratch pad memory. From memory, the microprocessor performs an analysis of the digital signal and computes the tracking error. Lastly, the corrective signal is transmitted to a cross seam actuator digital drive motor controller to complete the closed loop, feedback, tracking system. This weld seam tracking control system is capable of a tracking accuracy of + or - 0.2 mm, or better. As configured, the system is applicable to square butt, V-groove, and lap joint weldments

Reinforced structural plastics

Reinforced polyimide structures are described. Reinforcing materials are impregnated with a suspension of polyimide prepolymer and bonded together by heat and pressure to form a cured, hard-reinforced, polyimide structure

New rapid-curing, stable polyimide polymers with high-temperature strength and thermal stability

Additive-type polymerization reaction forms thermally stable polyimide polymers, thereby eliminating the volatile matter attendant with the condensation reaction. It is based on the utilization of reactive alicyclic rings positioned on the ends of polyimide prepolymers having relatively low molecular weights