SEARCH · Engineering Papers

Results for “Differential Experiments”

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.

SourceResearch connectionFrom yearThrough year

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

At least 127 records · Page 7

All sources NASA NTRS DOE OSTI

NASA NTRS1997

The Effect of Micro-Gravity on in vitro Calcification

The experiment focuses on mineral deposition or calcification of cartilage. The experiments were used to compare the mineral formed in the microgravity of space with that formed on earth. Results of these experiments were anticipated to provide direct insight into how calcification in cartridge and bone may be controlled in space. In the C-2 experiment (STS 66), we found that mineralization started later in the cartridges (both on the ground and in hypo-gravity) than in plastic, and that mineralization appeared to be retarded in hypo-gravity. The flight experiments also showed that the cells differentiated normally, but more slowly than the ground controls, and that the matrix produced was not different from that made on the ground. The purpose of the C-5 experiment was to confirm these findings. The C-5 experiment was flown on STS-72. Because of a computer problem, cells received no gases and no nutrition. The C-7 was flown on STS-77. Ground controls were repeated a week later, however, because there was a problem with the temperature control during the flight, the concurrent ground controls were performed at a different temperature. Despite these problems, the results of the C-2 experiment were confirmed. The cells in the flight cultures did not mature, formed few cartilage nodules, and showed no evidence of mineral deposition up to a culture age of 28 days. Ground controls showed the presence of mineral (based on chemical, spectroscopic, and histochemical analyses) by 21 days. The mineral in these cultures was analogous to that found in calcifying cartilage of young chicks.

Boskey↗

NASA NTRS1978

Model potentials for electron scattering - Converged close coupling calculations for the differential cross section for e/-/N2 at 30-50 eV

A calculation has been made of the elastic scattering and rotational excitation cross sections for e(-)-N2 scattering at 30 and 50 eV using quantum chemical techniques specially designed to be applicable to elastic and inelastic electron scattering by general polyatomic molecules. The angle dependence of the sum of the elastic and rotational excitation differential cross sections is in good agreement with experiment at all scattering angles at both energies, but at 50 eV the difference from experiment exceeds the experimental uncertainty at small scattering angles and near the minimum of the differential cross section. At large scattering angles the rotational excitation cross sections are predicted to exceed the elastic scattering cross sections. The absolute cross sections agree with experiment at some angles but at other angles are as much as 51% (30 eV) or 90% (50 eV) higher; this may be due at least in part to the difficulty of putting the experimental results on an absolute scale.

Onda, K.↗

NASA NTRS1992

Investigation of the effects of Extra Vehicular Activity (EVA) and Launch and Entry (LES) gloves on performance

Human capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective and a multipurpose tool. This is especially true for unknown environments such as the EVA environment. In the microgravity environment interfaces, procedures, and activities are too complex, diverse, and defy advance definition. Under these conditions the hand becomes the primary means of locomotion, restraint, and material handling. Facilitation of these activities, with simultaneous protection from the cruel EVA environment are the two, often conflicting, objectives of glove design. The objectives of this study was (1) to assess the effects of EVA gloves at different pressures on human hand capabilities, (2) to devise a protocol for evaluating EVA gloves, (3) to develop force time relations for a number of EVA glove pressure combinations, and (4) to evaluate two types of launch and entry suit gloves. The objectives were achieved through three experiments. The experiments for achieving objectives 1, 2, and 3 were performed in the glove box in building 34. In experiment 1 three types of EVA gloves were tested at five pressure differentials. A number of performance measures were recorded. In experiment 2 the same gloves as in experiment 1 were evaluated in a reduced number of pressure conditions. The performance measure was endurance time. Six subjects participated in both the experiments. In experiment 3 two types of launch and entry suit gloves were evaluated using a paradigm similar to experiment 1. Currently the data is being analyzed. However for this report some summary analyses have been performed. The results indicate that a) With EVA gloves strength is reduced by nearly 50 percent, b) performance decrements increase with increasing pressure differential, c) TMG effects are not consistent across the three gloves tested, d) some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand, and e) differences in performance exist between partial pressure suit glove and full pressure suit glove, especially in the unpressurized condition.

Bishu, Ram R.↗

NASA NTRS1980

Zonal and meridional circulation of the lower atmosphere of Venus determined by radio interferometry

The results of the Pioneer Venus differential long-baseline interferometry experiment are presented. The velocity component of the Pioneer probes as they fell to the surface of Venus was calculated from the Doppler shift of the received signal, and the other two orthogonal components were determined by long-baseline interferometry. The ambient wind velocity was about 1 m/s or less near the surface of the planet and about 100 m/s at an altitude of about 65 km at all four probe locations. Strata of high wind shear were found at altitudes of 15, 45, and 60 km. The wind velocity was always directed within a few degrees of due west except at a few km above the surface. The dominant motion of the lower atmosphere seems to be a retrograde zonal rotation, and eddies appear to account for most of the instantaneous meridional velocity. The data suggest that, within the clouds, a thermally driven mean meridional circulation is superimposed upon the much more rapid zonal rotation.

Counselman, C. C., III↗

NASA NTRS1981

Cosmic ray detector for high energy iron nuclei

An experiment to directly measure the differential energy spectra of nuclei with charge between 15-28 inclusive with a balloon borne instrument is presented. A High Energy Gas Cerenkov Spectrometer (HEGCS) is described, and consists of a 3 m diam drum 4.5 m tall containing three light diffusion chambers. A hodoscopic array of scintillators emit light into the top and bottom light chambers which serve for track recordings of the trajectory and charge of incident cosmic rays. A center chamber pressure vessel, the HEGCS, has a 4.0 m sr and a threshold of 50 GeV/amu. The hexagonal array scintillators have 24 elements/array feeding photomultiplier tubes at the vertices between the scintillators, with other PMTs located around the top and bottom chambers to capture escaped scintillator light. The HEGCS is filled with freon-12, with reflective paint on the inner surface to convert UV Cerenkov photons into visible photons near 425 nm.

Streitmatter, R. E.↗

NASA NTRS1983

Investigation of superelastic electron scattering by laser-excited Ba - Experimental procedures and results

Differential (in angle) electron scattering experiments on laser-excited Ba-138 1P were carried out at 30- and 100-eV impact energies. The laser light was linearly polarized and located in the scattering plane. The superelastic scattering signal was measured as a function of polarization direction of the laser light with respect to the scattering plane. It was found at low electron scattering angles that the superelastic scattering signal was asymmetric to reflection of the polarization vector with respect to the scattering plane. This is in contradiction with theoretical predictions. An attempt was made to pinpoint the reason for this observation, and a detailed investigation of the influence of experimental conditions on the superelastic scattering was undertaken. No explanation for the asymmetry has as yet been found.

NASA NTRS1986

Linewidth characteristics of Raman-shifted dye laser output at 720 and 940 nm

A compact and simple simultaneous multi-wavelength dye laser cavity was developed for a differential absorption technique. Dielectric multilayer interference filters were inserted inside the cavities as tuning elements, and two types of a DIAL system were constucted by using the dye laser tuned with dielectric multilayer filters to measure NO2 concentration. The usefulness of this dye laser was clarified for the differential absoroption technique in outdoor experiments. Some basic designs of the laser cavity with these filters to get simultaneously multi-wavelength output are summarized.

Grossmann, B. E.↗

NASA NTRS1987

Airborne intercomparisons of carbon monoxide measurement techniques

Results from an airborne intercomparison of techniques to measure tropospheric levels of carbon monoxide (CO) are discussed. The intercomparison was conducted as part of the National Aeronautics and Space Administration's Global Tropospheric Experiment and included a laser differential absorption method and two grab sample/gas chromatograph methods. Measurements were obtained during approximately 90 flight hours, during which the CO mixing ratios ranged from about 60 to 140 ppbv. The level of agreement observed for the ensemble of measurements was well within the overall accuracy stated for each instrument. The correlation observed between the measurements from the respective pairs of instruments ranged from 0.85 to 0.98, with no evidence for the presence of either a constant or proportional bias between any of the instruments.

Hoell, James M., Jr.↗

NASA NTRS1991

Characterizing water/rock interaction in simulated comet nuclei via calorimetry: Tool for in-situ science, laboratory analysis, and sample preservation

Although results from the Giotto and Vega spacecraft flybys of comet P/Halley indicate a complex chemistry for both the ices and dust in the nucleus, carbonaceous chondrite meteorites are still regarded as useful analogs for the rocky components. Carbonaceous chondrites mixed with water enable simulation of water/rock interactions which may occur in cometary nuclei. Three general types of interactions can be expected between water and minerals at sub-freezing temperatures: heterogeneous nucleation of ice by insoluble minerals; adsorption of water vapor by hygroscopic phases; and freezing and melting point depression of liquid water sustained by soluble minerals. Two series of experiments were performed in a differential scanning calorimeter (DSC) with homogenized powders of the following whole-rock meteorites and comparison samples: Allende (CV3), Murchison (CM2), Orgueil (CI), Holbrook (L6), and Pasamonte (eucrite) meteorites as well as on peridotite (PCC-1, USGS), saponite (Sap-Ca-1, CMS), montmorillonite (STx-1, CMS), and serpentine (Franciscan Formation, California). Results are briefly discussed.

Allton, Judith H.↗

NASA NTRS1992

High-pressure melting of carbonaceous chondrite

Phase equilibria experiments investigating the melting and differentiation of the primordial Earth require a realistic 'initial' chemical composition. Carbonaceous chondrites are good analogues for the initial bulk chemical composition of an accreting early Earth because they contain approximately solar abundances of the non-volatile elements and are the most primitive objects yet sampled in the solar system.

Agee, Carl B.↗

NASA NTRS1998

Remote Sensing Measurements of Vertical and Horizontal Moisture Variations from Aircraft Instruments

The research in this paper focuses on describing vertical and horizontal of water vapor variability using two remote sensing aircraft instruments. To achieve this goal we will compare precipitable water and upper level humidity estimates derived from the each of the instruments. The Multispectral Atmospheric Mapping Sensor (MAMS) is a visible and infrared radiometer with similar channels to that of the GOES imager. MAMS has flown aboard the NASA ER-2 numerous times. It has been used to validate features observed with the previous series of GOES satellites. MAMS data has been used to study precipitable water and upper level water vapor as well as other geophysical parameters. MAMS provides the opportunity to obtain water vapor Imagery at 6.7 mm. Upper tropospheric humidity can be computed using this channel in a similar fashion to that of Soden and Bretherton. In addition to the water vapor channel, MAMS records data In 3 other Infrared channels and 8 visible and near Infrared bands at high spatial resolution (I 00 Abstract: m). The 1 1 and 12 mm infrared channels allow for the application of a split technique to derive total precipitable water. The Udar Atmospheric Sensing Experiment (LASE) which uses the Differential Absorption Udar (DIAL) technique for obtaining simultaneous water vapor and aerosol profiles through the entire troposphere. LASE operates In the 81 5 nm wavelength region and uses a double pulsed Ti:sapphire laser that is locked onto a water vapor line. LASE has good horizontal (IO km) and excellent vertical (300 m) resolution. MAMS and LASE collected data simultaneously on several ER-2 flights in September 1995. LASE mixing ratio profiles will be Integrated for comparison with MAMS precipitable water estimates and the upper tropospheric humidity will be computed for the layer observed by the MAMS 6.7 mm channel for comparison for this time period. Results show a significant correlation between the measurements of the two Instruments. Regions of high/low upper tropospheric humidity are apparent In measurements from both instruments. Also changes in boundary layer moisture depicted by LASE are reflected in the total precipitable water measured by MAMS.

Atkinson, R. J.↗

NASA NTRS2000

Investigation of Mesoscale Variability in Convective Boundary Layer Development Using LASE

Throughout this research effort we have analyzed data collected from the Southern Great Plains 1997 (SGP) experiment to evaluate terms in the budget of water vapor in the atmospheric boundary layer (ABL). The analysis is centered on using data obtained from the Lidar Atmospheric Sensing Experiment (LASE) downward-looking differential absorption lidar (DIAL) that was flown on the NASA-P3 aircraft. The DIAL is able to measure vertical profiles of water vapor, as well as aerosol backscatter, throughout the ABL. Initial work on using the DIAL is summarized in the attached meeting preprint, which discusses results from a segment of the 12 July 1997 flight. Additional analysis has been carried out using both the DIAL data and in situ measurements to obtain more complete and detailed estimates of terms in the ABL water vapor budget. This includes data from the Canadian National Research Council Twin Otter aircraft, as well as from a spectrum of surface-based instruments. This work is expected to lead to a refereed article planned for submission to the Journal.

Lenschow, Donald H.↗

NASA NTRS2013

Experiments with a Parallel Multi-Objective Evolutionary Algorithm for Scheduling

Evolutionary multi-objective algorithms have great potential for scheduling in those situations where tradeoffs among competing objectives represent a key requirement. One challenge, however, is runtime performance, as a consequence of evolving not just a single schedule, but an entire population, while attempting to sample the Pareto frontier as accurately and uniformly as possible. The growing availability of multi-core processors in end user workstations, and even laptops, has raised the question of the extent to which such hardware can be used to speed up evolutionary algorithms. In this paper we report on early experiments in parallelizing a Generalized Differential Evolution (GDE) algorithm for scheduling long-range activities on NASA's Deep Space Network. Initial results show that significant speedups can be achieved, but that performance does not necessarily improve as more cores are utilized. We describe our preliminary results and some initial suggestions from parallelizing the GDE algorithm. Directions for future work are outlined.

scheduling↗

NASA NTRS2016

Spaceborne Remote Sensing of Aerosol Type: Global Distribution, Model Evaluation and Translation into Chemical Speciation

It is essential to evaluate and refine aerosol classification methods applied to passive satellite remote sensing. We have developed an aerosol classification algorithm (called Specified Clustering and Mahalanobis Classification, SCMC) that assigns an aerosol type to multi-parameter retrievals by spaceborne, airborne or ground-based passive remote sensing instruments [1]. The aerosol types identified by our scheme are pure dust, polluted dust, urban-industrialdeveloped economy, urban-industrialdeveloping economy, dark biomass smoke, light biomass smoke and pure marine. We apply the SCMC method to inversions from the ground-based AErosol RObotic NETwork (AERONET [2]) and retrievals from the space-borne Polarization and Directionality of Earths Reflectances instrument (POLDER, [3]). The POLDER retrievals that we use differ from the standard POLDER retrievals [4] as they make full use of multi-angle, multispectral polarimetric data [5]. We analyze agreement in the aerosol types inferred from both AERONET and POLDER and evaluate GEOS-Chem [6] simulations over the globe. Finally, we use in-situ observations from the SEAC4RS airborne field experiment to bridge the gap between remote sensing-inferred qualitative SCMC aerosol types and their corresponding quantitative chemical speciation. We apply the SCMC method to airborne in-situ observations from the NASA Langley Aerosol Research Group Experiment (LARGE, [7]) and the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP, [8]) instruments; we then relate each coarsely defined SCMC type to a sum of percentage of individual aerosol species, using in-situ observations from the Particle Analysis by Laser Mass Spectrometry (PALMS, [9]), the Soluble Acidic Gases and Aerosol (SAGA, [10]), and the High - Resolution Time - of - Flight Aerosol Mass Spectrometer (HR ToF AMS, [11]).

airborne↗

NASA NTRS1990

Microgravity laboratory simulations of planetary and stellar circulations

This paper summarizes experiments on thermal convection in a rotating differentially heated spherical shell of liquid that were carried out in the microgravity laboratory of Spacelab III. In these experiments, dielectric polarization forces were used to generate a radially-directed buoyancy force. This enabled the simulation of a number of geophysically and astrophysically important situations in which sphericity and rotation both impose strong constraints on the global scale fluid dynamics. Recent theoretical and numerical interpretations of the original data are discussed. Further laboratory experiments in the areas of geophysical and g-jitter fluid dynamics are suggested.

Hart, John E.↗

NASA NTRS1971

Frog egg growth, experiment S003

The objective of experiment was to determine the effect of weightlessness on the ability of a fertilized frog egg to divide normally and to differentiate and form a normal embryo. This experiment was first attempted on the Gemini 8 mission and was completed only partially because of the early termination of that mission.

Young, R. S.↗

NASA NTRS1981

Experiments on the abiotic amplification of optical activity

Experiments concerning the physical mechanisms for the abiotic generation and chemical mechanisms for the amplification of optical activity in biological compounds are reviewed. Attention is given to experiments involving the determination of the differential adsorption of racemic amino acids on d- and l-quartz, the asymmetric photolysis of racemic amino acids by circularly polarized light, and the asymmetric radiolysis of solid amino acids by longitudinally polarized electrons, and the enantiomeric enrichments thus obtained are noted. Further experiments on the amplification of the chirality in the polymerization of D, L-amino acid mixtures and the hydrolysis of D-, L-, and D, L-polypeptides are discussed. It is suggested that a repetitive cycle of partial polymerization-hydrolyses may account for the abiotic genesis of optically enriched polypeptides on the primitive earth.

Bonner, W. A.↗

NASA NTRS2012

Photospheric Magnetic Flux Transport - Supergranules Rule

Observations of the transport of magnetic flux in the Sun's photosphere show that active region magnetic flux is carried far from its origin by a combination of flows. These flows have previously been identified and modeled as separate axisymmetric processes: differential rotation, meridional flow, and supergranule diffusion. Experiments with a surface convective flow model reveal that the true nature of this transport is advection by the non-axisymmetric cellular flows themselves - supergranules. Magnetic elements are transported to the boundaries of the cells and then follow the evolving boundaries. The convective flows in supergranules have peak velocities near 500 m/s. These flows completely overpower the superimposed 20 m/s meridional flow and 100 m/s differential rotation. The magnetic elements remain pinned at the supergranule boundaries. Experiments with and without the superimposed axisymmetric photospheric flows show that the axisymmetric transport of magnetic flux is controlled by the advection of the cellular pattern by underlying flows representative of deeper layers. The magnetic elements follow the differential rotation and meridional flow associated with the convection cells themselves -- supergranules rule!

Hathaway, David H.↗