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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

The Impact of Surface Boundary Forcing on Simulation of the 1998 Summer Drought Over the US Midwest Using Factor Separation Technique

The factor separation (FS) technique has been utilized to evaluate quantitatively the impact of surface boundary forcings on simulation of the 1988 summer drought over the Midwestern part of the U.S. The four surface boundary forcings used are: (1)Sea Surface Temperature (SST), (2) soil moisture, (3) snow cover, and (4) sea ice. The Goddard Earth Observing System(GEOS) General Circulation Model (GCM) is used to simulate the 1988 U.S. drought. A series of sixteen simulations are performed with climatological and real 1988 surface boundary conditions. The major single and mutual synergistic factors/impacts are analyzed. The results show that SST and soil moisture are the major single pro-drought factors. The couple synergistic effect of SST and soil moisture is the major anti-drought factor. The triple synergistic impact of SST, soil moisture, and snow cover is the strongest pro-drought impact and is, therefore, the main contributor to the generation of the drought. The impact of the snow cover and sea ice anomalies for June 1988 on the drought is significant only when combined with the SST and soil moisture anomalies.

Stein, Uri↗
NASA NTRS2003

CO2 Acquisition Membrane (CAM)

The objective of CAM is to develop, test, and analyze thin film membrane materials for separation and purification of carbon dioxide (CO2) from mixtures of gases, such as those found in the Martian atmosphere. The membranes are targeted toward In Situ Resource Utilization (ISRU) applications that will operate in extraterrestrial environments and support future unmanned and human space missions. A primary application is the Sabatier Electrolysis process that uses Mars atmosphere CO2 as raw material for producing water, oxygen, and methane for rocket fuel and habitat support. Other applications include use as an inlet filter to collect and concentrate Mars atmospheric argon and nitrogen gases for habitat pressurization, and to remove CO2 from breathing gases in Closed Environment Life Support Systems (CELSS). CAM membrane materials include crystalline faujasite (FAU) zeolite and rubbery polymers such as silicone rubber (PDMS) that have been shown in the literature and via molecular simulation to favor adsorption and permeation of CO2 over nitrogen and argon. Pure gas permeation tests using commercial PDMS membranes have shown that both CO2 permeance and the separation factor relative to other gases increase as the temperature decreases, and low (Delta)P(Sub CO2) favors higher separation factors. The ideal CO2/N2 separation factor increases from 7.5 to 17.5 as temperature decreases from 22 C to -30 C. For gas mixtures containing CO2, N2, and Ar, plasticization decreased the separation factors from 4.5 to 6 over the same temperature range. We currently synthesize and test our own Na(+) FAU zeolite membranes using standard formulations and secondary growth methods on porous alumina. Preliminary tests with a Na(+) FAU membrane at 22 C show a He/SF6 ideal separation factor of 62, exceeding the Knudsen diffusion selectivity by an order of magnitude. This shows that the membrane is relatively free from large defects and associated non-selective (viscous flow) transport mechanisms. The Membrane Test Facility (MTF) has been developed to measure membrane permeance over a wide range of temperature and pressure. The facility uses two volume compartments separated by the membrane that are instrumented to measure temperature, delta pressure across the membrane, and gas composition. A thermal shroud supports and encloses the membrane, and provides temperature control. Methods were developed to determine membrane permeance using the first order decay of the pressure difference between the sealed compartments, using the total pressure for pure gases, and partial pressure of each species in gas mixtures. The technique provides an end-to-end measurement of gas permeance that includes concentration polarization effects. Experiments have shown that in addition to membrane permeance properties, the geometry and design of associated structures play an important role in how membrane systems will function on Mars.

Mason, Larry W.↗
NASA NTRS1983

Ion exchange selectivity for cross-linked polyacrylic acid

The ion separation factors for 21 common metal ions with cross-linked polyacrylic acid were determined as a function of pH and the percent of the cross-linked polyacrylic acid neutralized. The calcium ion was used as a reference. At a pH of 5 the decreasing order of affinity of the ions for the cross-linked polyacrylic acid was found to be: Hg++, Fe+++, Pb++, Cr+++, Cu++, Cd++, Al+++, Ag+, Zn++, Ni++, Mn++, Co++, Ca++, Sr++, Ba++, Mg++, K+, Rb+, Cs+, Na+, and Li+. Members of a chemical family exhibited similar selectivities. The Hg++ ion appeared to be about a million times more strongly bound than the alkali metal ions. The relative binding of most of the metal ions varied with pH; the very tightly and very weakly bound ions showed the largest variations with pH. The calcium ion-hydrogen ion equilibrium was perturbed very little by the presence of the other ions. The separation factors and selectivity coefficients are discussed in terms of equilibrium and thermodynamic significance.

May, C. E.↗
NASA NTRS2021

Multi-Variate Factorisation of Numerical Simulations

Factorisation (also known as “factor separation”) is widely used in the analysis of numerical simulations. It allows changes in properties of a system to be attributed to changes in multiple variables associated with that system. There are many possible factorisation methods; here we discuss three previously proposed factorisations that have been applied in the field of climate modelling: the linear factorisation, the Stein and Alpert (1993) factorisation, and the Lunt et al. (2012) factorisation. We show that, when more than two variables are being considered, none of these three methods possess all four properties of “uniqueness”, “symmetry”, “completeness”, and “purity”. Here, we extend each of these factorisations so that they do possess these properties for any number of variables, resulting in three factorisations – the “linear-sum” factorisation, the “shared-interaction” factorisation, and the “scaled-residual” factorisation. We show that the linear-sum factorisation and the shared-interaction factorisation reduce to be identical in the case of four or fewer variables, and we conjecture that this holds for any number of variables. We present the results of the factorisations in the context of three past studies that used the previously proposed factorisations.

Numerical simulations↗
NASA NTRS2017

Aerosol Optical Depth Changes in Version 4 CALIPSO Level 2 Product

The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) version 4.10 (V4) products were released in November 2016 with substantial enhancements. There have been improvements in the V4 CALIOP level 2 aerosol optical depth (AOD) compared to V3 (version 3) due to various factors. AOD change from V3 to V4 is investigated by separating factors. CALIOP AOD was compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) and Aerosol Robotic Network (AERONET) for both V3 and V4.

Kim, Man-Hae↗
NASA NTRS1984

Future Direction of Research in Wear and Wear Resistant Materials. Status of Understanding

The adhesion of materials is one of the most popular interactions occuring between mating solid surfaces in contact, and was regarded as a key factor in wear process. However, because the adhesion is not a separation factor but a joining factor for mating materials, it is not easy to show a general plot of the formation process of wear particle through adhesion. A new idea on the mechanism of formation of wear particles in adhesive wear is shown. The wear particles are not separated from their mother surfaces directly as their final form, but minute adhered fragments are assembled and piled up to form a big particle which should be called as a wear particle after it is removed out of the rubbing system. From this proposed mechanism many other phenomena related to wear are interpreted.

Sasada, T.↗
NASA NTRS1985

A factored implicit scheme for numerical weather prediction

An implicit method is proposed to factor the nonlinear partial differential equations governing fast and slow modes of dynamic motion in numerical weather prediction schemes. The method permits separate factorization of the slow and fast modes of the implicit operator. A simple two-dimensional version of the system of three-dimensional equations governing atmospheric dynamics over shallow water was analyzed to assess the accuracy of the proposed method. It is shown that the method has a small error which is comparable to other discretization errors in the overall scheme.

Augenbaum, J. M.↗
NASA NTRS2019

The Cognition and Fine Motor Skills Test Batteries: Normative Data and Interdependencies

Space mission success and safety relies upon astronaut functional state. Since spaceflight stressors affect cognitive processing and fine motor skills, NASA requires that measures of performance of these things remain within clinically accepted values (NASA STD 3001). NASA is in the process of developing two test batteries for the assessment of crew cognitive and fine motor skills before, during and after spaceflight. Toward that goal, the current project collected normative scores in 91 “astronaut-like” military and civilian pilots. The Cognition Test Battery (CTB) contains ten sub-tests that measure a range of cognitive abilities. For five of the ten CTB sub-tests, we propose scores to improve the battery’s sensitivity. Among the ten sub-tests, response times were more highly correlated than accuracy scores. Principle component analysis of the correlations revealed that the first response time factor could explain over 40% of the total variance and appeared to represent the tendency of observers to try to respond more quickly. The first accuracy factor (explaining only 20%) gave a high weight to the higher level cognitive sub-tests and a negative weight to tasks associated with motor and lower level cognitive processing. The Fine Motor Skills (FMS) test battery contains four sub-tests (Tracking, Pointing, Tracing, Rotating) performed on an Apple iPad tablet computer. Principle component analysis on the sub-test response time correlations revealed that the first two factors accounted for ~80% of the variance in performance. The first component captured overall speed on all four of the sub-tests. The second factor separated the sub-tasks into two groups (Drag-Point vs Trace-Rotate). Previous work found the first group response times correlated with that of a standard peg board task, while those of the other group did not. Correlations were computed between the first FMS factor and the response time and accuracy scores from each CTB sub-task. Performing fine motor behaviors rapidly was significantly correlated with the ability to perform many of the CTB sub-tests rapidly. This ability cannot be simple motor speed since scores on the Psychomotor Vigilance Test (PVT) subtask did not correlate with the ability to perform the other tasks rapidly. Speed on fine motor skills correlated significantly with accuracy on the short-term-memory sub-test. We hypothesize that eye movements, which can be regarded as a fine motor skill, may explain this relationship.

cognition↗
NASA NTRS2004

Vestibular and Non-vestibular Contributions to Eye Movements that Compensate for Head Rotations during Viewing of Near Targets

We studied horizontal eye movements induced by en-bloc yaw rotation, over a frequency range 0.2 - 2.8 Hz, in 10 normal human subjects as th ey monocularly viewed a target located at their near point of focus. We measured gain and phase relationships between eye-in-head velocity and head velocity when the near target was either earth-fixed or head-fixed. During viewing of the earth-fixed near target,median gain was 1.49 (range 1.24 - 1.87) at 0.2 Hz for the group of subjects, but decl ined at higher frequencies, so that at 2.8 Hz median gain was 1.08 (r ange 0.68 - 1.67). During viewing of the head-fixed near target, median gain was 0.03 (range 0.01 - 0.10) at 0.2 Hz for the group of subjec ts, but increased at higher frequencies, so that at 2.8 Hz median gai n was 0.71 (range 0.28 - 0.94). We estimated the vestibular contribution to these responses (vestibulo-ocular reflex gain, Gvor) by applyin g transient head perturbations (peak acceleration> 1,000 deg's(exp 2) ) during sinusoidal rotation under the two viewing conditions. Median Gvor, estimated < 70m after the onset of head perturbation, was 0.98 (range 0.39 - 1.42) while viewing the earth-fixed near target, and 0. 97 (range 0.37 - 1.33) while viewing the head-fixed near target. For the group of subjects, 9 out of 10 subjects showed no sigificant diff erence of Gvor between the two viewing conditions ( p > 0.053 ) at all test frequencies. Since Gvor accounted for only approximately 73% of the overall response gain during viewing of the earth-fixed target, we investigated the relative contributions of non-vestibular factors. When subjects viewed the earth-fixed target under strobe illumination , to eliminate retinal image slip information, the gain of compensato ry eye movements declined compared with viewing in ambient room light . During sum-of-sine head rotations, while viewing the earth-fixed target, to minimize contributions from predictive mechanisms, gain also declined Nonetheless, simple superposition of smooth-pursuit tracking of sinusoidal target motion could not fully account for the overall r esponse at higher frequencies, suggesting other non-vestibular contributions. During binocular viewing conditions when vergence angle was s ignificantly greater than monocular viewing (p < 0.001), this gain of compensatory eye movements did not show proportional change; indeed, gain could not be correlated with vergence angle during monocular or binocular viewing. We conclude that several separate factors contribute to generate eye rotations during sinusoidal yaw head rotations whi le viewing a near target; these include the VOR, visual-tracking eye movements that utilize retinal image motion, predictive eye movements and, possibly, other unidentified nonvestibular factors. For these experiments, vergence was not an important determinant of response gain .

Han, Yanning H.↗
NASA NTRS2006

Vestibular and Non-vestibular Contributions to Eye Movements that Compensate for Head Rotations during Viewing of Near Targets

We studied horizontal eye movements induced by en-bloc yaw rotation, over a frequency range 0.2 - 2.8 Hz, in 10 normal human subjects as they monocularly viewed a target located at their near point of focus. We measured gain and phase relationships between eye-in-head velocity and head velocity when the near target was either earth-fixed or head-fixed. During viewing of the earth-fixed near target, median gain was 1.49 (range 1.24 - 1.87) at 0.2 Hz for the group of subjects, but declined at higher frequencies, so that at 2.8 Hz median gain was 1.08 (range 0.68 - 1.67). During viewing of the head-fixed near target , median gain was 0.03 (range 0.01 - 0.10) at 0.2 Hz for the group of subjects, but increased at higher frequencies, so that at 2.8 Hz median gain was 0.71 (range 0.28 - 0.94). We estimated the vestibular contribution to these responses vestibulo-ocular reflex gain (Gvor) by applying transient head perturbations (peak acceleration> 1,000 deg/s(exp 2)) during sinusoidal rotation under the two viewing conditions. Median Gvor, estimated < 70ms after the onset of head perturbation, was 0.98 (range 0.39 - 1.42) while viewing the earth-fixed near target, and 0.97 (range 0.37 - 1.33) while viewing the head-fixed near target. For the group of subjects, 9 out of 10 subjects showed no significant difference of Gvor between the two viewing conditions ( p > 0.053 ) at all test frequencies. Since Gvor accounted for only -73% of the overall response gain during viewing of the earth-fixed target, we investigated the relative contributions of non-vestibular factors. When subjects viewed the earth-fixed target under strobe illumination, to eliminate retinal image slip information, the gain of compensatory eye movements declined compared with viewing in ambient room light. During sum-of-sine head rotations, while viewing the earth-fixed target, to Han et al./VOR during near-viewing minimize contributions from predictive mechanisms, gain also declined Nonetheless, simple superposition of smooth-pursuit tracking of sinusoidal target motion could not fully account for the overall response at higher frequencies, suggesting other nonvestibular contributions. During binocular viewing conditions when vergence angle was significantly greater than monocular viewing (p < 0.00l), the gain of compensatory eye movements did not show proportional change; indeed, gain could not be correlated with vergence angle during monocular or binocular viewing. We conclude that several separate factors contribute to generate eye rotations during sinusoidal yaw head rotations while viewing a near target; these include the VOR, visual-tracking eye movements that utilize retinal image motion, predictive eye movements and, possibly, other unidentified non-vestibular factors. For these experiments, vergence was not an important determinant of response gam.

Han, Yanning H.↗
NASA NTRS1976

The relation of metal composition to rock type for clasts in Apollo 16 soils

The moderately magnetic fractions of soils from a bright ray of South Ray Crater and from the continuous ejecta of North Ray Crater are described. The clasts in these fractions are classified as agglutinate, ANT melt rocks, glassy melt rocks, and ANT hornfels/breccia. Determinations are made of the Ni-Co and P contents of single-phase metal grains in the clasts. It is found that most of these grains have compositions in the meteoritic range and that the compositions tend to cluster at about 6% Ni. A significant amount of Fe-rich metal is also detected in some clasts along with a clear P-enrichment in metal from one soil sample. Meteoritic contamination of lunar metal having compositions in or close to the meteoritic range is considered. A model involving nine separate factors is proposed as an explanation of the observed metal compositions.

Hewins, R. H.↗
NASA NTRS1979

Alternative Beam Efficiency Calculations for a Large-aperture Multiple-frequency Microwave Radiometer (LAMMR)

The fundamental definition of beam efficiency, given in terms of a far field radiation pattern, was used to develop alternative definitions which improve accuracy, reduce the amount of calculation required, and isolate the separate factors composing beam efficiency. Well-known definitions of aperture efficiency were introduced successively to simplify the denominator of the fundamental definition. The superposition of complex vector spillover and backscattered fields was examined, and beam efficiency analysis in terms of power patterns was carried out. An extension from single to dual reflector geometries was included. It is noted that the alternative definitions are advantageous in the mathematical simulation of a radiometer system, and are not intended for the measurements discipline where fields have merged and therefore lost their identity.

Schmidt, R. F.↗
NASA NTRS1986

Spaceborne optical disk controller development

The current status and potential applications of an optical-disk buffer (ODB) memory system being developed by an interagency consortium including NASA and the USAF are reviewed. The design goals for the ODB include usable capacity 1 Tb, maximum data rate 1.6 Gb/s, read error rate less than 10 to the -12th, time to initial access less than 100 ms, and unlimited read/write cycles. Present efforts focus on a brassboard ODB which employs 12 14-inch magnetooptic disks and 24 nine-diode read/write heads. A typical space application of an optical disk mass memory system (ODMMS) is discussed: as communications buffer, temporary storage, and/or multiuser I/O buffer for data management on the Space Station Earth Observing System. Environmental, operational, system-architecture, and functional-separation factors; critical design issues; and standardization questions for spaceborne ODMMSs are examined in detail.

Shull, Thomas A.↗
NASA NTRS1999

Mesoscale Simulations of a Florida Sea Breeze Using the PLACE Land Surface Model Coupled to a 1.5-Order Turbulence Parameterization

A sophisticated land-surface model, PLACE, the Parameterization for Land Atmospheric Convective Exchange, has been coupled to a 1.5-order turbulent kinetic energy (TKE) turbulence sub-model. Both have been incorporated into the Penn State/National Center for Atmospheric Research (PSU/NCAR) mesoscale model MM5. Such model improvements should have their greatest effect in conditions where surface contrasts dominate over dynamic processes, such as the simulation of warm-season, convective events. A validation study used the newly coupled model, MM5 TKE-PLACE, to simulate the evolution of Florida sea-breeze moist convection during the Convection and Precipitation Electrification Experiment (CaPE). Overall, eight simulations tested the sensitivity of the MM5 model to combinations of the new and default model physics, and initialization of soil moisture and temperature. The TKE-PLACE model produced more realistic surface sensible heat flux, lower biases for surface variables, more realistic rainfall, and cloud cover than the default model. Of the 8 simulations with different factors (i.e., model physics or initialization), TKE-PLACE compared very well when each simulation was ranked in terms of biases of the surface variables and rainfall, and percent and root mean square of cloud cover. A factor separation analysis showed that a successful simulation required the inclusion of a multi-layered, land surface soil vegetation model, realistic initial soil moisture, and higher order closure of the planetary boundary layer (PBL). These were needed to realistically model the effect of individual, joint, and synergistic contributions from the land surface and PBL on the CAPE sea-breeze, Lake Okeechobee lake breeze, and moist convection.

Lynn, Barry H.↗
NASA NTRS1998

The Influence of Soil Moisture and Wind on Rainfall Distribution and Intensity in Florida

Land surface processes play a key role in water and energy budgets of the hydrological cycle. For example, the distribution of soil moisture will affect sensible and latent heat fluxes, which in turn may dramatically influence the location and intensity of precipitation. However, mean wind conditions also strongly influence the distribution of precipitation. The relative importance of soil moisture and wind on rainfall location and intensity remains uncertain. Here, we examine the influence of soil moisture distribution and wind distribution on precipitation in the Florida peninsula using the 3-D Goddard Cumulus Ensemble (GCE) cloud model Coupled with the Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) land surface model. This study utilizes data collected on 27 July 1991 in central Florida during the Convection and Precipitation Electrification Experiment (CaPE). The idealized numerical experiments consider a block of land (the Florida peninsula) bordered on the east and on the west by ocean. The initial soil moisture distribution is derived from an offline PLACE simulation, and the initial environmental wind profile is determined from the CaPE sounding network. Using the factor separation technique, the precise contribution of soil moisture and wind to rainfall distribution and intensity is determined.

Baker, R. David↗
NASA NTRS1944

An Experimental Investigation of the Flow of Air in a Flat Broadening Channel

The wide use of diffusers, in various fields of technology, has resulted in several experimental projects to study the action and design of diffusers. Most of the projects dealt with steam (steam turbine nozzles). But diffusers have other applications - that is, ventilators, smoke ducts, air coolers, refrigeration, drying, and so forth. At present there is another application for diffusers in wind-tunnel design. Because of higher requirements and increased power of such installations more attention must be paid to the correctness of work and the decrease in losses due to every section of the tunnel. A diffuser, being one of the component parts of a tunnel , can in the event of faulty construction introduce considerable losses. Therefore, in the design of the new CAHI wind tunnel, it was suggested that an experimental study of diffusers be made, with a view to applying the results to wind tunnels. The experiments conducted by K. K. Baulin in the laboratories of CAHI upon models of diffusers of different cross sections, lengths, and angles of divergence, were a valuable source of experimental data. They were of no help, however, in reaching any conclusion regarding the optimum shape because of the complexity and diversity of the factors which all appeared simultaneously, thereby precluding the.study of the effects of any one factor separately. On the suggestion of the director of the CAHI,Prof. B. N. Ureff, it was decided to experiment on a two-dimensional diffuser model and determine the effect, of the angle of divergence. The author is acquainted with two experimental projects of like nature: the first was conducted with water, the other with air. The first of these works, although containing a wealth of experimental data, does not indicate the nature of flow or its relation to the angle of divergence. The second work is limited to four angles - that is, 12 deg, 24 deg, 45 deg, 90 deg. The study of this diffuser did not supply any information about the effect of smaller angles which, because of their advantages, are more commonly used, The author was able to acquaint himself with the second work only after the experiments were started. For these reasons, as well as because on the basis of those works no conclusion can be reached regarding the nature of flow distribution, of eddies, and so forth, experimental work was continued. The need for determining flow patterns follows from the fact that from them are determined methods of measurement - that is, the determination of velocities by means of the pitot tube, which, as is well known, gives correct indications only when placed with its axis parallel to the axis of flow. The data contained in this report were obtained from experiments conducted by the Aerodynamical Laboratories of the CAHI. The solutions to some. of the mathematical problems connected with the experiments are due to Prof. S. A, Chapligin.

Vedernikoff, A. N.↗