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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Predetection telemetry analog recording and playback for Pioneer Venus 1978

Prediction telemetry recording and playback capability was implemented in the DSN to meet PV-78 mission requirements. Test data, along with theoretical considerations, gives assurance that the data degradation commitment of 1.5 db will be met, and it is anticipated that in actual performance the design goal of 1.0 db will be met. The major technical problems requiring solution were elimination of image in the OLR and the reduction of analog recorder instabilities. These were solved through the use of single-sideband mixing techniques and the use of newer generation analog recorders.

Kent, S. S.↗
NASA NTRS1978

Measurement of control system response using an analog operational circuit

Ten basic steps are established for an analog method that measures control system response parameters. An example shows how these steps were used on a speed control portion of an auxiliary power unit. The equations and calculations necessary to describe this subsystem are given. The mechanization schematic and simulation diagram for obtaining the measured response parameters of the control system using an analog circuit are explained. Methods for investigating the various effects of the control parameters are described. It is concluded that the optimum system should be underdamped enough to be slightly oscillatory during transients.

Lalli, V. R.↗
NASA NTRS1977

Infrared spectra of lunar soil analogs

The infrared spectra of analogs of lunar soils were investigated to further the development of methodology for interpretation of remotely measured infrared spectra of the lunar surface. The optical constants of dunite, bytownite, augite, ilmenite, and a mare glass analog were obtained. The infrared emittance spectra of powdered minerals were measured and compared with spectra calculated by the reflectance theory using a catalog of optical constants. The results indicate that the predictions of the theory closely simulate the experimental measurements if the optical constants are properly derived.

Aronson, J. R.↗
NASA NTRS1978

Mid infrared spectra of lunar and analog soils

The mid infrared emittance spectrum contains compositional information about lunar soils. In order to be able to properly interpret remotely obtained data, it was necessary to develop a theoretical model of the emittance of particulate minerals. This theory was shown to simulate the spectra of analog lunar soils satisfactorily provided that good values of the optical constants of the component minerals were available. Optical constants have been obtained for dunite, bytownite, augite, ilmenite, and a mare glass analog during this work. Our first measurements on lunar soils indicated that 67711 is very immature (high contrast) and is dominated by feldspar; that 10084 shows very low contrast with some evidence of pyroxene and feldspar bands. 71061 is intermediate between the other two having a gross similarity to 10084 but with considerably more contrast.

Aronson, J. R.↗
NASA NTRS1980

Digital multiplexing of analog data in a microprocessor controlled data acquisition system

The purpose of the paper is to explore the ramifications of doing the multiplexing function in the digital domain and of using the microprocessor to replace the hardwired control logic which resides in the typical analog to digital converter. Two types of conversion (one working in parallel inputs, and one in sequential order) strategies are discussed where the microprocessor is in full control of the conversion. One advantage of using a digital multiplexor is that, contrary to an analog multiplexor, it does not degrade the fidelity of the conversion process.

Cliff, R. A.↗
NASA NTRS1980

A quadratic analog-to-digital converter

An analog-to-digital converter with a square root transfer function has been developed for use with a pair of CCD imaging detectors in the White Light Coronagraph/X-ray XUV Telescope experiment to be flown as part of the Internal Solar Polar Mission. It is shown that in background-noise-limited instrumentation systems a quadratic analog-to-digital converter will allow a maximum dynamic range with a fixed number of data bits. Low power dissipation, moderately fast conversion time, and reliability are achieved in the proposed design using standard components and avoiding nonlinear elements.

Harrison, D. C.↗
NASA NTRS1981

Altered basaltic glass - A terrestrial analog to the soil of Mars

In order to understand the nature of weathering processes and the formation of clay-like substances on Mars, analogous terrestrial processes and materials have been examined including sideromelane and palagonite. It is shown that palagonite is a good analog to the soil of Mars to the level of precision available from Viking and ground-based telescopic spectral measurements. Points of resemblance between the two materials include bulk chemical composition, particle size, reflectance spectra, and magnetic properties. A mechanism for the formation of Martian soil, based on a palagonite model, is proposed.

Allen, C. C.↗
NASA NTRS1982

Resonant electrodynamic heating of stellar coronal loops - An LRC circuit analog

The problem of electrodynamic coupling of stellar coronal loops where beta is less than 1 to underlying velocity fields where beta is greater than approximately 1 is treated. A rigorous analysis reveals that the physics can be represented by a simple yet equivalent LRC circuit analog. This derived analog suggests the existence of global structure oscillations which resonantly excite internal field line oscillations at a spatial resonance within the coronal loop. Even though the width of this spatial resonance, as well as the induced currents and coronal velocity field, within the resonance region explicitly depends on viscosity and resistivity, the resonant form of the generalized electrodynamic heating functions is virtually independent of irreversibilities. This is a classic feature of high-quality resonators that are driven externally by a broad-band source of spectral power.

Ionson, J. A.↗
NASA NTRS1984

Data and results of a laboratory investigation of microprocessor upset caused by simulated lightning-induced analog transients

A methodology was developed a assess the upset susceptibility/reliability of a computer system onboard an aircraft flying through a lightning environment. Upset error modes in a general purpose microprocessor were studied. The upset tests involved the random input of analog transients which model lightning induced signals onto interface lines of an 8080 based microcomputer from which upset error data was recorded. The program code on the microprocessor during tests is designed to exercise all of the machine cycles and memory addressing techniques implemented in the 8080 central processing unit. A statistical analysis is presented in which possible correlations are established between the probability of upset occurrence and transient signal inputs during specific processing states and operations. A stochastic upset susceptibility model for the 8080 microprocessor is presented. The susceptibility of this microprocessor to upset, once analog transients have entered the system, is determined analytically by calculating the state probabilities of the stochastic model.

Belcastro, C. M.↗
NASA NTRS1985

Experimental methods for quenching structures in lunar-analog silicate melts: Variations as a function of quench media and composition

Compositions analogous to lunar green, organge, and brown glasses were synthesized under consistent conditions, then quenched into a variety of different media when the samples were removed from the furnace. Iron valence and coordination are a direct function of quench media used, spanning the range from brine/ice (most effective quench), water, butyl phthalate, silicone oil, liquid nitrogen, highly reducing CO-CO2 gas, to air (least efficient quench). In the green and brown glasses, Fe(3+) in four-fold and six-fold coordination is observed in the slowest-quenched samples; Fe(2+) coordination varies directly with quench efficiency. Less pronounced changes were observed in the Ti-rich orange glass. Therefore the remote-sensed spectrum of a glass-bearing regolith on the Moon may be influenced by the process by which the glass cooled, and extreme caution must be used when comparing spectra of synthetic glass analogs with real lunar glasses.

Dyar, M. D.↗
NASA NTRS1985

Catastrophic-flood Features in Swedish Lapland as a Terrestrial Analog for Martian Channel Flows

Catastrophic flooding associated with deglaciation created unusual landscapes in several areas of northern Sweden. These areas in Swedish Lapland are distinguished by the large grain-size material that forms them. The presence of boulders at both Viking landing sites suggests the relevance of this analog. The Baldakatj area of Swedish Lapland offers terrestrial analogs for erosional remnants on Mars. Although the Baldakatj features are an order of magnitude or more smaller than the Martian forms, they created in boulder-rich till that may be a good approximation of the near-surface material on Mars. The Baldakatj area also includes other landforms that could reasonably be expected to occur with the Martian outflow channels, including boulder deltas, large transported blocks, and large-scale bedforms.

Rossbacher, L. A.↗
NASA NTRS1984

Experimental methods for quenching structures in lunar-analog silicate melts - Variations as a function of quench media and composition

Compositions analogous to lunar green, orange, and brown glasses were synthesized under consistent conditions, then quenched into a variety of different media when the samples were removed from the furnace. Iron valence and coordination are a direct function of quench media used, spanning the range from brine/ice (most effective quench), water, butyl phthalate, silicone oil, liquid nitrogen, highly reducing CO-CO2 gas, to air (least efficient quench). In the green and brown glasses, Fe(3+) in four-fold and six-fold coordination is observed in the slowest-quenched samples; Fe(2+) coordination varies directly with quench efficiency. Less pronounced changes were observed in the Ti-rich orange glass. Therefore the remote-sensed spectrum of a glass-bearing regolith on the moon may be influenced by the process by which the glass cooled, and extreme caution must be used when comparing spectra of synthetic glass analogs with real lunar glasses.

Dyar, M. D.↗
NASA NTRS1985

The use of analogs in the innovation process - A software engineering protocol analysis

A human information processing account of how experienced practitioners utilize analogs in the innovation process is presented. The protocols of several practitioners are collected and analyzed. The problem behavior graphs, knowledge elements utilized, and operator elements applied are described, and a descriptive model of the innovation process is assembled. Implications for a production system, deviations from other models of the innovation process, and extensions to other models of the analogy procedure are explored.

Silverman, B. G.↗
NASA NTRS1986

Pseudolog Digital-to-Analog Converter

Sensitivity decreases by 10 at beginning of each input decade. Method conceived to convert binary-coded data to suitable linear form for stripchart recording. Strip-chart recordings obtained from typical pressure readings in a vacuum system during pumpdown. In reading curve, BCD digital vacuum-gage output processed by analog-to-digital converter in such way that only reading digits (but not range) appear in output. In range and reading, range also converted to analog and placed as most significant digit.

Gooder, S. T.↗
NASA NTRS1986

Analog Video Image-Enhancing Device

Inexpensive system yields pseudo-three-dimensional effect. Includes video camera with lens, connected to video monitor for analog video enhancement. Video signal obtained from monitor at point beyond where synchronization signals are detected, eliminating need to regenerate composite video signal. Analog video image-enhancing device improves appearance of technical photographs by selectively compressing overall dynamic ranges while accentuating edges or small details of greatest interest.

Weinstein, L. M.↗
NASA NTRS1986

Extensions of the concept of suction analogy to prediction of vortex lift effect

Flow field data for a double delta wing at low speed were used to determine the location of a vortex action point. The result was found to be consistent with what was determined for a delta wing. In supersonic flow, the action point location was determined empirically. For a wing with rounded leading edges, an assumption for initial vortex separation was shown to be equivalent to initial leading edge bubble separation for airfoils. A theoretical formulation by the section analogy to determine the delayed vortex separation on a cambered wing with rounded leading edges was presented. The method of suction analogy was further shown to be applicable to predicting the body vortex lift.

Lan, C. E.↗
NASA NTRS1985

Turbulent Reynolds analogy factors for nonplanar surface microgeometries

Direct measurements of turbulent Reynolds analogy factors are presented for 15 nonplanar surface microgeometries (including riblets, oscillating transverse curvature, wavy walls, and micro air bearings) for momentum thickness Reynolds numbers of 1638-2631. It is shown that certain types of nonplanar surface microgeometries will increase turbulent Reynolds analogy factors significantly above flat-plate levels. In several cases, the observed elevated heat-transfer efficiencies represent the combined effects of both heat-transfer increases and drag decreases. Generally, the results suggest that decreases of the order of 20 percent are possible in heat exchanger volume, cost, and weight for designs with extensive planar surfaces.

Lindemann, A. M.↗