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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Communications and control for electric power systems: Power flow classification for static security assessment

This report investigates the classification of power system states using an artificial neural network model, Kohonen's self-organizing feature map. The ultimate goal of this classification is to assess power system static security in real-time. Kohonen's self-organizing feature map is an unsupervised neural network which maps N-dimensional input vectors to an array of M neurons. After learning, the synaptic weight vectors exhibit a topological organization which represents the relationship between the vectors of the training set. This learning is unsupervised, which means that the number and size of the classes are not specified beforehand. In the application developed in this report, the input vectors used as the training set are generated by off-line load-flow simulations. The learning algorithm and the results of the organization are discussed.

Niebur, D.↗
NASA NTRS1978

Water electrolysis system - H2 and O2 generation

An oxygen generation system design based on the static feed water electrolysis concept is described. The system is designed to generate 4.20 kg/d of oxygen to satisfy the metabolic needs of a three-person crew, to compensate for spacecraft leakage, and to provide the oxygen required by the electrochemical depolarized CO2 concentrator. The system has a fixed hardware weight of 75 kg, occupies a volume of 0.11 cu m, and requires only 1.1 kw of electrical power. The static feed electrolysis concept is discussed, and experimental data on the high-performance electrode are presented.

Schubert, F. H.↗
NASA NTRS1972

Surface atmospheric extremes (Launch and transportation areas)

The effects of extreme values of surface and low altitude atmospheric parameters on space vehicle design, tests, and operations are discussed. Atmospheric extremes from the surface to 150 meters for geographic locations of interest to NASA are given. Thermal parameters (temperature and solar radiation), humidity, pressure, and atmospheric electricity (lighting and static) are presented. Weather charts and tables are included.

Source record↗
NASA NTRS1971

Magnetic tape recorder for long operating life in space.

Magnetic tape recorders have long been used on satellites and spacecraft for onboard storage of large quantities of data. As satellites enter into commercial service, long operating life at high reliability becomes important. Also, the presently planned long-duration space flights to the outer planets require long-life tape recorders. Past satellite tape recorders have achieved a less than satisfactory performance record and the operating life of other spacecraft tape recorders has been relatively short and unpredictable. Most failures have resulted from malfunctions of the mechanical tape transport. Recent advances in electric motors and static memories have allowed the development of a new tape recorder which uses a very simple tape transport with few possible failure modes. It consists only of two brushless dc motors, two tape guides, and the recording heads. Relatively low tape tension, wide torque capability, and precise speed control facilitate design for mechanical reliability to match that of tape-recorder electronics.

Bahm, E. J.↗
NASA NTRS1974

Surface atmospheric extremes (launch and transportation areas)

Criteria are provided on atmospheric extremes from the surface to 150 meters for geographical locations of interest to NASA. Thermal parameters (temperature and solar radiation), humidity, precipitation, pressure, and atmospheric electricity (lightning and static) are presented. Available data are also provided for the entire continental United States for use in future space programs.

Source record↗
NASA NTRS1985

Tethers Open New Space Options

The fundamentals of tether action are discussed with focus on the forces acting on tethered masses and a tethered satellite system being developed for deployment from the space shuttle is examined. The static, dynamic, and electric properties of the tether can be exploited for use in the long term observation of phenomena of the lower troposphere; as a space based wind tunnel; to generate high electrodynamic power; to provide desirable gravity for the space station; to dock orbit transfer vehicles with the space station; and to form a constellation of space platforms tied to the space station. Italy is responsible for building and integrating the satellite. NASA is involved in building the deployer and integrating the tethered satellite system with the space shuttle.

Bekey, I.↗
NASA NTRS1992

Calculation of the quasi-energies and resonances behavior of the hydrogen Lyman-alpha problem

Recently, Bakshi and Kalman presented numerical results for the quasi-energies of the n = 2 multiplet in the hydrogen Lyman-alpha transition for a plasma in which both strong static and oscillating electric fields are present. Recent work on related magnetic and optical resonance problems provides a simplified mathematical treatment, as well as greater insight into the complex resonance behavior of this interaction.

Ruyten, Wilhelmus M.↗
NASA NTRS2014

Evaluation of Dielectric-Barrier-Discharge Actuator Substrate Materials

A key, enabling element of a dielectric barrier discharge (DBD) actuator is the dielectric substrate material. While various investigators have studied the performance of different homogeneous materials, most often in the context of related DBD experiments, fundamental studies focused solely on the dielectric materials have received less attention. The purpose of this study was to conduct an experimental assessment of the body-force-generating performance of a wide range of dielectric materials in search of opportunities to improve DBD actuator performance. Materials studied included commonly available plastics and glasses as well as a custom-fabricated polyimide aerogel. Diagnostics included static induced thrust, electrical circuit parameters for 2D surface discharges and 1D volume discharges, and dielectric material properties. Lumped-parameter circuit simulations for the 1D case were conducted showing good correspondence to experimental data provided that stray capacitances are included. The effect of atmospheric humidity on DBD performance was studied showing a large influence on thrust. The main conclusion is that for homogeneous, dielectric materials at forcing voltages less than that required for streamer formation, the material chemical composition appears to have no effect on body force generation when actuator impedance is properly accounted for.

Wilkinson, Stephen P.↗
NASA NTRS1992

Palladium-chromium static strain gages for high temperatures

An electrical resistance strain gage that can provide accurate static strain measurement to a temperature of 1500 F or above is being developed both in fine wire and thin film forms. The gage is designed to be temperature compensated on any substrate material. It has a dual element: the gage element is a special alloy, palladium-13wt percent chromium (PdCr), and the compensator element is platinum (Pt). Earlier results of a PdCr based wire gage indicated that the apparent strain of this gage can be minimized and the repeatability of the apparent strain can be improved by prestabilizing the gage on the substrate for a long period of time. However, this kind of prestabilization is not practical in many applications and therefore the development of a wire gage which is prestabilized before installation on the substrate is desirable. This paper will present our recent progress in the development of a prestabilized wire gage which can provide meaningful strain data for the first thermal cycle. A weldable PdCr gage is also being developed for field testing where conventional flame-spraying installation can not be applied. This weldable gage is narrower than a previously reported gage, thereby allowing the gage to be more resistant to buckling under compressive loads. Some preliminary results of a prestabilized wire gage flame-sprayed directly on IN100, an engine material, and a weldable gage spot-welded on IN100 and SCS-6/(beta)21-S Titanium Matrix Composite (TMC), a National Aero-Space Plane (NASP) structure material, will be reported. Progress on the development of a weldable thin film gage will also be addressed. The measurement technique and procedures and the lead wire effect will be discussed.

Lei, Jih-Fen↗
NASA NTRS1984

Portable pallet weighing apparatus

An assembly for use with several like units in weighing the mass of a loaded cargo pallet supported by its trunnions has a bridge frame for positioning the assembly on a transportation frame carrying the pallet while straddling one trunnion of the pallet and its trunnion lock, and a cradle assembly for incrementally raising the trunnion. The mass at the trunnion is carried as a static load by a slidable bracket mounted upon the bridge frame for supporting the cradle assembly. The bracket applies the static loading to an electrical load cell symmetrically positioned between the bridge frame and the bracket. The static loading compresses the load cell, causing a slight deformation and a potential difference at load cell terminals which is proportional in amplitude to the mass of the pallet at the trunnion.

Day, R. M.↗
NASA NTRS1991

Palladium-chromium static strain gage for high temperature propulsion systems

The present electrical strain gage for high temperature static strain measurements is in its fine-wire and thin-film forms designed to be temperature-compensated on any substrate material. The gage element is of Pd-Cr alloy, while the compensator is of Pt. Because the thermally-induced apparent strain of this compensated wire strain gage is sufficiently small, with good reproducibility between thermal cycles to 800 C, output figures can be corrected within a reasonable margin of error.

Lei, Jih-Fen↗
NASA NTRS1985

High temperature static strain gage alloy development program

The literature, applicable theory and finally an experimental program were used to identify new candidate alloy systems for use as the electrical resistance elements in static strain gages up to 1250K. The program goals were 50 hours of use in the environment of a test stand gas turbine engine with measurement accuracies equal to or better than 10 percent of full scale for strains up to + or - 2000 microstrain. As part of this effort, a computerized electrical resistance measurement system was constructed for use at temperatures between 300K and 1250K and heating and cooling rates of 250K/min and 10K/min. The two best alloys were an iron-chromium-aluminum alloy and a palladium base alloy. Although significant progress was made, it was concluded that a considerable additional effort would be needed to fully optimize and evaluate these candidate systems.

Hulse, C. O.↗
NASA NTRS1988

New theoretical results for the Lehmann effect in cholesteric liquid crystals

The Lehmann effect arising in a cholesteric liquid crystal drop when a temperature gradient is applied parallel to its helical axis is investigated theoretically using a local approach. A pseudoscalar quantity is introduced to allow for cross couplings which are absent in nematic liquid crystals, and the statics and dissipative dynamics are analyzed in detail. It is shown that the Lehmann effect is purely dynamic for the case of an external electric field and purely static for an external density gradient, but includes both dynamic and static coupling contributions for the cases of external temperature or concentration gradients.

Brand, Helmut R.↗