Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “experience report”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Experiment MA-028 crystal growth

A crystal growth experiment is reported on orbital space flights. The experiment was performed during the Apollo-Soyuz Test Project. The Crystal Growth Experiment assessed a novel process for growing single crystals of insoluble substances by allowing two or more reactant solutions to diffuse toward each other through a region of pure solvent in zero gravity. The experiment was entirely successful and yielded crystals of about the expected size, quality, and number.

Lind, D. M.↗
NASA NTRS1984

Lubricant Rheology in Concentrated Contacts

A revue of experimental investigations of lubricant behaviour in highly stressed situations shows that a Newtonian model for lubricant rheology is insufficient for explanation of traction behaviour. The oil film build-up, on the other hand, is fairly well predicted using a Newtonian lubricant model except at high slide to roll ratios and at very high loads, where the non-Newtonian behaviour starts to be important already outside the Hertzian contact area. Two main types of experiments are reported: static and dynamic. In static experiments the pressure is typically applied to the lubricant more than a million times longer than in an EHD contact. Depending on the pressure-temperature history of the experiment the lubricant will become a crystallized or amorphous solid at high pressures. In dynamic experiments, where the pressure is applied as short time as in real EHD contacts, the oil is in an amorphous solid state. Depending on the viscosity, time-scale, elasticity of the oil and the bearing surfaces, the oil film pressure, shear strain rate and the type of lubricant, different properties of the oil are important for prediction of shear stresses in the oil. This can be seen from the different proposed models for the lubricant, where it is described as being for instance a Newtonian liquid, an elastic liquid, a plastic liquid and an elastic-plastic solid.

Bo O Jacobson↗
NASA NTRS1992

Role of dielectric constant in electrohydrodynamics of conducting fluids

Electrohydrodynamic (EHD) flows are driven by the interaction of an electric field with variations in electric conductivity or dielectric constant. In reported EHD experiments on the deformation of drops of immiscible dielectric fluids, the role of conductivity has tended to overshadow the role of dielectric constant. Often, large conductivity contrasts were convenient because the conductivities of the dielectric fluid were relatively uncertain. As a result, the observed effects were always qualitatively the same as if there had been no contrast in dielectric constant. Our early experiments studying the EHC deformations of cylindrical streams readily showed the conductivity effect but the dielectric constant effect was not discernible. We have modified our flow chamber and improved our method of observation and can now see an unequivocal dielectric constant effect which is in agreement with the prior theory. In this paper we first give a brief description of the physics of charge buildup at the interface of an immersed spherical drop or flowing cylindrical sample stream and then show how these charge distributions lead to interface distortions and accompanying viscous flows which constitute EHD. We next review theory and experiment describing the deformation of spherical drops. We show that in the reported drop deformation experiments, the contrast in dielectric constant was never sufficient to reverse the deformation due to the conductivity contrast. We review our work describing the deformation of a cylindrical stream of one fluid flowing in a parallel flow of another, and we compare the deformation equations with those for spherical drops. Finally, we show a definite experimental dielectric constant effect for cylindrical stream of aqueous polystyrene latex suspension. The dielectric constant varies with the frequency of the imposed electric field, and the associated EHD flow change is very apparent.

Rhodes, Percy H.↗
NASA NTRS2012

Crystallization of Yamato 980459 at 0.5 GPA: Are Residual Liquids Like QUE 94201?

The Martian basaltic meteorites Y980459 and QUE94201 (henceforth referred to as Y98 and QUE respectively) are thought to represent magmatic liquid compositions, rather than being products of protracted crystallization and accumulation like the majority of other martian meteorites. Both meteorite compositions have been experimentally crystallized at 1 bar, and liquidus phases were found to match corresponding mineral core compositions in the meteorites, consistent with the notion that these meteorites represent bona fide melts. They also represent the most primitive and most evolved basaltic martian samples, respectively. Y98 has Mg# (molar Mg/Mg+Fe) approximates 65, and lacks plagioclase; whereas QUE has Mg# approximates 40, and lacks olivine. However they share important geochemical characteristics (e.g. superchondritic CaO/Al2O3, very high epsilon(sub Nd) and low Sr-87/Sr-87) that suggest they sample a similar highly depleted mantle reservoir. As such, they represent likely endmembers of martian magmatic liquid compositions, and it is natural to seek petrogenetic linkages between the two. We make no claim that the actual meteorites themselves share a genetic link (the respective ages rule that out); we are exploring only in general whether primitive martian liquids like Y98 could evolve to liquids resembling QUE. Both experimental and computational efforts have been made to determine if there is indeed such a link. Recent petrological models at 1 bar generated using MELTS suggest that a QUE-like melt can be derived from a parental melt with a Y98 composition. However, experimental studies at 1 bar have been less successful at replicating this progression. Previous experimental crystallization studies of Y98 by our group at 0.5 GPa have produced melt compositions approaching that of QUE, although these results were complicated by the presence of small, variable amounts of H2O in some of the runs owing to the use of talc/pyrex experimental assemblies. Therefore we have repeated the four experiments, augmented with additional runs, all using BaCO3 cell assemblies, which are devoid of water, and these new experiments supersede those reported earlier. Here we report results of experiments simulating equilibrium crystallization; fractional crystallization experiments are currently underway.

Rapp, J. F.↗
NASA NTRS1976

Large Area Crop Inventory Experiment (LACIE). Phase 1: Evaluation report

It appears that the Large Area Crop Inventory Experiment over the Great Plains, can with a reasonable expectation, be a satisfactory component of a 90/90 production estimator. The area estimator produced more accurate area estimates for the total winter wheat region than for the mixed spring and winter wheat region of the northern Great Plains. The accuracy does appear to degrade somewhat in regions of marginal agriculture where there are small fields and abundant confusion crops. However, it would appear that these regions tend also to be marginal with respect to wheat production and thus increased area estimation errors do not greatly influence the overall production estimation accuracy in the United States. The loss of segments resulting from cloud cover appears to be a random phenomenon that introduces no significant bias into the estimates. This loss does increase the variance of the estimates.

Source record↗
NASA NTRS1991

Experiments In Multivariable Adaptive Control Of A Flexible Structure

Report describes experiments in use of six-input/six-output multivariable adaptive control system to suppress vibrations in complicated flexible structure. Represents significant upgrade relative to two-input/two-output system, yielding significant improvement in spatial controllability and effective damping of largest set of modes. Structure exhibits low modal frequencies and complicated dynamics like those of large structures in outer space. Conclusions drawn from research relevant to such applications as active suppression of wind and earthquake vibrations in tall buildings and other large terrestrial structures.

Ih, Che-Hang C.↗
NASA NTRS1984

NASA thunderstorm overflight program: Atmospheric electricity research. An overview report on the optical lightning detection experiment for spring and summer 1983

This report presents an overview of the NASA Thunderstorm Overflight Program (TOP)/Optical Lightning Experiment (OLDE) being conducted by the Marshall Space Flight Center and university researchers in atmospheric electricity. Discussed in this report are the various instruments flown on the NASA U-2 aircraft, as well as the ground instrumentation used in 1983 to collect optical and electronic signatures from the lightning events. Samples of some of the photographic and electronic signatures are presented. Approximately 4132 electronic data samples of optical pulses were collected and are being analyzed by the NASA and university researchers. A number of research reports are being prepared for future publication. These reports will provide more detailed data analysis and results from the 1983 spring and summer program.

Vaughan, O. H., Jr.↗
NASA NTRS1976

Operational plans for life science payloads - From experiment selection through postflight reporting

Key features of operational plans developed in a study of the Space Shuttle era life science payloads program are presented. The data describes the overall acquisition, staging, and integration of payload elements, as well as program implementation methods and mission support requirements. Five configurations were selected as representative payloads: (a) carry-on laboratories - medical emphasis experiments, (b) mini-laboratories - medical/biology experiments, (c) seven-day dedicated laboratories - medical/biology experiments, (d) 30-day dedicated laboratories - Regenerative Life Support Evaluation (RLSE) with selected life science experiments, and (e) Biomedical Experiments Scientific Satellite (BESS) - extended duration primate (Type I) and small vertebrate (Type II) missions. The recommended operational methods described in the paper are compared to the fundamental data which has been developed in the life science Spacelab Mission Simulation (SMS) test series. Areas assessed include crew training, experiment development and integration, testing, data-dissemination, organization interfaces, and principal investigator working relationships.

Mccollum, G. W.↗
NASA NTRS1973

Experiments on confined turbulent jets in cross flow.

Results are reported of experiments on the effects of an opposite wall on the characteristics of turbulent jets injected into a cross flow, for unheated and heated jets. Longitudinal and transverse distributions of velocity and temperature are presented for single and multiple circular jets, and trajectories are presented for two-domensional jets. The opposite wall has relatively little effect on a single jet unless the ratio of jet to cross flow momentum flux is large enough for the jet to impinge on the opposite wall. For a row of jets aligned perpendicularly to the cross flow, the opposite wall exerts progressively larger influence as the spacing between jets decreases. Much of the effect of jet and wall proximity can be understood by considering the interaction of the vortex flow which is the major feature of the structure of a single jet in a cross flow. Smoke photographs are shown to elucidate some of the interaction patterns.

Kamotani, Y.↗
NASA NTRS1974

Experiments on confined turbulent jets in cross flow

Results are reported of experiments on the effects of an opposite wall on the characteristics of turbulent jets injected into a cross flow, for unheated and heated jets. Longitudinal and transverse distributions of velocity and temperature are presented for single and multiple circular jets, and trajectories are presented for two-dimensional jets. The opposite wall has relatively little effect on a single jet unless the ratio of jet to cross flow momentum flux is large enough for the jet to impinge on the opposite wall. For a row of jets aligned perpendicularly to the cross flow, the opposite wall exerts progressively larger influence as the spacing between jets decreases. Much of the effect of jet and wall proximity can be understood by considering the interaction of the vortex flow which is the major feature of the structure of a single jet in a cross flow. Smoke photographs are shown to elucidate some of the interaction patterns.

Kamotani, Y.↗
NASA NTRS1978

Orbit determination accuracies using satellite-to-satellite tracking

The results of the ATS-6/GEOS-3 and the ATS-6/NIMBUS-6 satellite-to-satellite tracking orbit determination experiments are reported. The tracking systems used in these experiments differ from the Tracking and Data Relay Satellite System (TDRSS), primarily in the use of one rather than two synchronous relay satellites. However, the simulations mentioned indicate that the insights gained from the experiments with regard to proper data reduction techniques and expected results are applicable to the TDRSS.

Vonbun, F. O.↗
NASA NTRS1986

An empirical study of flight control software reliability

The results of a laboratory experiment in flight control software reliability are reported. The experiment tests a small sample of implementations of a pitch axis control law for a PA28 aircraft with over 14 million pitch commands with varying levels of additive input and feedback noise. The testing which uses the method of n-version programming for error detection surfaced four software faults in one implementation of the control law. The small number of detected faults precluded the conduct of the error burst analyses. The pitch axis problem provides data for use in constructing a model in the prediction of the reliability of software in systems with feedback. The study is undertaken to find means to perform reliability evaluations of flight control software.

Dunham, J. R.↗
NASA NTRS1977

Communications Link Characterization Experiment (CLCE) technical data report, volume 2

The results are presented of the long term rain rate statistical analysis and the investigation of determining the worst month statistical from the measured attenuation data caused by precipitation. The rain rate statistics cover a period of 11 months from July of 1974 to May of 1975 for measurements taken at the NASA, Rosman station. The rain rate statistical analysis is a continuation of the analysis of the rain rate data accumulated for the ATS-6 Millimeter Wave Progation Experiment. The statistical characteristics of the rain rate data through December of 1974 is also presented for the above experiment.

Source record↗
NASA NTRS1977

Large Area Crop Inventory Experiment (LACIE). Phase 2 evaluation report

Documentation of the activities of the Large Area Crop Inventory Experiment during the 1976 Northern Hemisphere crop year is presented. A brief overview of the experiment is included as well as phase two area, yield, and production estimates for the United States Great Plains, Canada, and the Union of Soviet Socialist Republics spring winter wheat regions. The accuracies of these estimates are compared with independent government estimates. Accuracy assessment of the United States Great Plains yardstick region based on a through blind sight analysis is given, and reasons for variations in estimating performance are discussed. Other phase two technical activities including operations, exploratory analysis, reporting, methods of assessment, phase three and advanced system design, technical issues, and developmental activities are also included.

Source record↗