Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Data exploration”

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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

The influence of IMF B(y) on the high-latitude thermospheric circulation during northward IMF

This paper uses the Dynamics Explorer data set, together with a sufficient quantity of corresponding IMF data, to establish correlations among the observed relationships between the IMF B(y) and the high-latitude thermospheric circulation during periods of northward IMF. Statistical evidence is presented that illustrates a relationship between the respective magnitudes of the B(z) and B(y) components of the IMF and the occurrence of sunward winds in the polar cap. The ion-neutral coupling processes responsible for the observed effects are discussed together with the general implications of the results.

Mccormac, F. G.↗
NASA NTRS1992

Dynamics Explorer measurements of particles, fields, and plasma drifts over a horse-collar auroral pattern

As shown from ground-based measurements and satellite-borne imagers, one type of global auroral pattern characteristic of quiet (usually northward IMF) intervals is that of a contracted but thickened emission region of a pattern referred to as 'horse-collar' aurora (Hones et al., 1989). In this report we use the Dynamics Explorer data set to examine a case in which this horse-collar pattern was observed by the DE-1 auroral imager, while at the same time DE-2, at lower altitude, measured precipitating particles, electric and magnetic fields, and plasma drifts. Our analysis shows that, in general, there is close agreement between the optical signatures and the particle precipitation patterns. In many instances, over scales ranging from tens to a few hundred kilometers, electron precipitation features and upward field-aligned currents are observed at locations where the plasma flow gradients indicate negative V-average x E. The particle, plasma, and field measurements made along the satellite track and the 2D perspective of the imager provide a means of determining the configuration of convective flows in the high-latitude ionosphere during this interval of northward IMF. Recent mapping studies are used to relate the low-altitude observations to possible magnetospheric source regions.

Sharber, J. R.↗
NASA NTRS1995

Comparisions of modeled N(+), O(+), H(+) and He(+) in the midlatitude ionospherewith mean densities and temperatures from Atmosphere Explorer

In this study, Atmosphere Explorer data and model results for the ion and electron temperature and the density of N(+), O(+), H(+), and He(+) between 120 and 1400 km altitude are compared for two midlatitude ranges (L=2 and L=4), noon and midnight local time, winter and summer, at solar minimum. The data for the heavy atomic ions (O(+) and N(+)) show that their densities are greater at noon than at midnight for a given season and greater in summer than winter for a given local time. There is only a weak latitudinal variation in the density of these ions. The data show that the light ion (H(+) and He(+)) densities are greater at midnight than at noon and are generally greater in winter than summer. There is a strong latitudinal variation of the light ion densities, with the densities decreasing with increasing latitude. The model densities are in good agreement with the AE densities for N(+), O(+), and H(+). Model He(+) densities are lower, by a factor of 2 or more, than the measured densities. Model ion and electron temperatures agree well with the measured temperatures with only a modest increase in plasmapheric heating.

Craven, P. D.↗
NASA NTRS1998

Results of Two-Stage Light-Gas Gun Development Efforts and Hypervelocity Impact Tests of Advanced Thermal Protection Materials

Gun development efforts to increase the launching capabilities of the NASA Ames 0.5-inch two-stage light-gas gun have been investigated. A gun performance simulation code was used to guide initial parametric variations and hardware modifications, in order to increase the projectile impact velocity capability to 8 km/s, while maintaining acceptable levels of gun barrel erosion and gun component stresses. Concurrent with this facility development effort, a hypervelocity impact testing series in support of the X-33/RLV program was performed in collaboration with Rockwell International. Specifically, advanced thermal protection system materials were impacted with aluminum spheres to simulate impacts with on-orbit space debris. Materials tested included AETB-8, AETB-12, AETB-20, and SIRCA-25 tiles, tailorable advanced blanket insulation (TABI), and high temperature AFRSI (HTA). The ballistic limit for several Thermal Protection System (TPS) configurations was investigated to determine particle sizes which cause threshold TPS/structure penetration. Crater depth in tiles was measured as a function of impact particle size. The relationship between coating type and crater morphology was also explored. Data obtained during this test series was used to perform a preliminary analysis of the risks to a typical orbital vehicle from the meteoroid and space debris environment.

Cornelison, C. J.↗
NASA NTRS1998

Next Generation User Support Tools

One of the manually intensive efforts of Hubble Space Telescope (HST) observing is the specification and validation of the detailed proposals for scientists observing with the telescope. In order to meet the operational cost objectives for the Next Generation Space Telescope (NGST), this process needs to be dramatically less time consuming and less costly. We have prototyped a new proposal development system, the Scientist's Expert Assistant (SEA), using a combination of artificial intelligence and user interface techniques to reduce the time and effort involved for both scientists and the telescope operations staff. The Advanced Architectures and Automation Branch of NASA's Goddard Space Flight Center is working with the Space Telescope Science Institute (ST ScI) to explore SEA alternatives. We are testing the usefulness of rule-based expert systems to painlessly guide a scientist to his or her desired observation specification. We are also examining several potential user interface paradigms and exploring data visualization schemes to see which techniques are more intuitive. Our prototypes will be validated using HST's Advanced Camera for Surveys (ACS) instrument (scheduled for installation in 1999) as a live test instrument. Having an operational test-bed will ensure the most realistic feedback possible for the prototyping cycle. In addition, once the NGST instruments are better defined, the SEA will already be a proven platform that simply needs adapting to NGST-specific instruments.

Jones, Jeremy E.↗
NASA NTRS1997

Multiwaveband Monitoring of the Bright, Violently Variable Quasar 3C454.3

The RXTE (Rossi X Ray Timing Explorer) data of the quasar 3C 454.3 were analyzed by the PI (Principle Investigator) and his graduate students. The resulting light curve is shown. Substantial variations are seen. These, however, are not correlated with variations at either optical or radio wavelengths. For this reason, the PI decided that more observations were needed and that the project should be continued. These observations have taken place or are scheduled for Cycles 2 and 3 of RXTE. Because the project is continuing, no publications have yet resulted. The PI plans to submit a paper to the Astrophysical Journal at the conclusion of the multi-year monitoring project.

Marscher, Alan P.↗
NASA NTRS2001

Discovery of a Second High-Frequency Quasi-Periodic Oscillation from the Microquasar GRS 1915+105

We report the discovery in archival Rossi X-Ray Timing Explorer data of a approx. 40 Hz quasi-periodic oscillation QPO) in the hard X-ray flux from the Galactic microquasar GRS 1915+105. The QPO is detected only in the hard X-ray band above approx. 13 keV and was discovered in observations in which the previously known 67 Hz QPO is present. The 40 Hz QPO has a typical rms amplitude of approx. 2% in the 13-27 keV band and a width of approx. 5.5 Hz (FWHM). We show that the 67 and 40 Hz QPOs are detected in the same observations in 1997 July and November. However, the QPO is not detected in observations from 1996 April, May, and June in which the 67 Hz QPO was first discovered. The frequency of the 67 Hz QPO is significantly higher in the 1997 observations by about 5% compared with the 1996 data. The identification of the 40 Hz QPO makes GRS 1915 + 105 the second black hole binary to show a pair of simultaneous high-frequency QPOs (the other being GRO J1655-40). The similarities between the properties of the 67 Hz QPO in GRS 1915+105 and the recently discovered 450 Hz QPO in GRO J1655-40 suggest that the pairs of frequencies in these systems may be produced by the same physical mechanism, with the frequency differences between the two being likely due to different black hole masses in the two systems. We discuss the implications of our result for the mass and spin of GRS 1915+105 as well as for models of X-ray variability in black holes and neutron stars.

Strohmayer, Tod E.↗
NASA NTRS2002

Effects of Resonance in Quasi-Periodic Oscillators of Neutron Star Binaries

Using a large quantity of Rossi X-Ray Timing Explorer data presented in the literature, I offer a detailed investigation into the accuracy of the quasi-periodic oscillation (QPO) frequency determination. The QPO phenomenon seen in X-ray binaries is possibly a result of the resonance of the intrinsic (eigen) oscillations and harmonic driving forces of the system. I show that the resonances, in the presence of the damping of oscillations, occur at frequencies that are systematically and randomly shifted with respect to the eigenfrequencies of the system. The shift value strongly depends on the damping rate that is measured by the half-width of the QPO feature. Taking into account this effect, I analyze the QPO data for four Z sources, Scorpius X-I, GX 340+0, GX 5-1, and GX 17+2, and two atoll sources, 4U 1728-34 and 4U 0614+09. The transition-layer model (TLM) predicts the existence of the invariant quantity delta, an inclination angle of the magnetospheric axis with respect to the normal to the disk. I calculate delta and the error bars of delta using the resonance shift, and I find that the inferred delta-values are consistent with constants for these four Z sources, in which horizontal-branch oscillation and kilohertz frequencies have been detected and correctly identified. It is shown that the inferred delta are in the range between 5.5 deg and 6.5 deg. I conclude that the TLM seems to be compatible with the data.

Titarchuk, Lev↗
NASA NTRS2002

Alternative Metrics for Evaluating the Resilence of Advanced Life Support Systems

Ensuring the safety of the crew is a key performance requirement of a life support system. However, a number of conceptual and practical difficulties arise when devising metrics to concretely measure the ability of a life support system to maintain critical functions in the presence of anticipated and unanticipated faults. Resilience is a dynamic property of a life support system that depends on the complex interactions between faults, controls and system hardware. We review some of the approaches to understanding the robustness or resilience of complex systems being developed in diverse fields such as ecology, software engineering and cell biology and discuss their applicability to regenerative life support systems. We also consider how approaches to measuring resilience vary depending on system design choices such as the definition and choice of the nominal operating regime. Finally, we explore data collection and implementation issues such as the key differences between the instantaneous or conditional and average or overall measures of resilience. Extensive simulation of a hybrid computational model of a water revitalization subsystem (WRS) with probabilistic, component-level faults provides data about off-nominal behavior of the system. The data are used to consider alternative measures of resilience as predictors of the system's ability to recover from component-level faults.

Bell, Ann Maria↗
NASA NTRS2010

Eight Year Climatologies from Observational (AIRS) and Model (MERRA) Data

We examine climatologies derived from eight years of temperature, water vapor, cloud, and trace gas observations made by the Atmospheric Infrared Sounder (AIRS) instrument flying on the Aqua satellite and compare them to similar climatologies constructed with data from a global assimilation model, the Modern Era Retrospective-Analysis for Research and Applications (MERRA). We use the AIRS climatologies to examine anomalies and trends in the AIRS data record. Since sampling can be an issue for infrared satellites in low earth orbit, we also use the MERRA data to examine the AIRS sampling biases. By sampling the MERRA data at the AIRS space-time locations both with and without the AIRS quality control we estimate the sampling bias of the AIRS climatology and the atmospheric conditions where AIRS has a lower sampling rate. While the AIRS temperature and water vapor sampling biases are small at low latitudes, they can be more than a few degrees in temperature or 10 percent in water vapor at higher latitudes. The largest sampling biases are over desert. The AIRS and MERRA data are available from the Goddard Earth Sciences Data and Information Services Center (GES DISC). The AIRS climatologies we used are available for analysis with the GIOVANNI data exploration tool. (see, http://disc.gsfc.nasa.gov).

Hearty, Thomas↗
NASA NTRS2011

Science Hybrid Orbiter and Lunar Relay (SCHOLR) Architecture and Design

Considered both a stepping-stone to deep space and a key to unlocking the mysteries of planetary formation, the Moon offers a unique opportunity for scientific study. Robotic precursor missions are being developed to improve technology and enable new approaches to exploration. Robots, lunar landers, and satellites play significant roles in advancing science and technologies, offering close range and in-situ observations. Science and exploration data gathered from these nodes and a lunar science satellite is intended to support future human expeditions and facilitate future utilization of lunar resources. To attain a global view of lunar science, the nodes will be distributed over the lunar surface, including locations on the far side of the Moon. Given that nodes on the lunar far side do not have direct line-of-sight for Earth communications, the planned presence of such nodes creates the need for a lunar communications relay satellite. Since the communications relay capability would only be required for a small portion of the satellite s orbit, it may be possible to include communication relay components on a science spacecraft. Furthermore, an integrated satellite has the potential to reduce lunar surface mission costs. A SCience Hybrid Orbiter and Lunar Relay (SCHOLR) is proposed to accomplish scientific goals while also supporting the communications needs of landers on the far side of the Moon. User needs and design drivers for the system were derived from the anticipated needs of future robotic and lander missions. Based on these drivers and user requirements, accommodations for communications payload aboard a science spacecraft were developed. A team of interns identified and compared possible SCHOLR architectures. The final SCHOLR architecture was analyzed in terms of orbiter lifetime, lunar surface coverage, size, mass, power, and communications data rates. This paper presents the driving requirements, operational concept, and architecture views for SCHOLR within a lunar surface nodal network. Orbital and bidirectional link analysis, between lunar nodes, orbiter, and Earth, as well as a conceptual design for the spacecraft are also presented

Trase, Kathryn K.↗
NASA NTRS2013

Sensors Enable Plants to Text Message Farmers

Long-term human spaceflight means long-term menu planning. Since every pound of cargo comes with a steep price tag, NASA has long researched technologies and techniques to allow astronauts to grow their own food, both on the journey and in some cases at their destination. Sustainable food technologies designed for space have resulted in spinoffs that improve the nutrition, safety, and durability of food on Earth. There are of course tradeoffs involved in making astronauts part-time farmers. Any time spent tending plants is time that can t be spent elsewhere: collecting data, exploring, performing routine maintenance, or sleeping. And as scarce as time is for astronauts, resources are even more limited. It is highly practical, therefore, to ensure that farming in space is as automated and precise as possible.

Source record↗
NASA NTRS2013

New Brown Dwarf Discs in Upper Scorpius Observed with WISE

We present a census of the disc population for UKIDSS selected brown dwarfs in the 5-10 Myr old Upper Scorpius OB association. For 116 objects originally identified in UKIDSS, the majority of them not studied in previous publications, we obtain photometry from the Wide-Field Infrared Survey Explorer data base. The resulting colour magnitude and colour colour plots clearly show two separate populations of objects, interpreted as brown dwarfs with discs (class II) and without discs (class III). We identify 27 class II brown dwarfs, 14 of them not previously known. This disc fraction (27 out of 116, or 23%) among brown dwarfs was found to be similar to results for K/M stars in Upper Scorpius, suggesting that the lifetimes of discs are independent of the mass of the central object for low-mass stars and brown dwarfs. 5 out of 27 discs (19 per cent) lack excess at 3.4 and 4.6 microns and are potential transition discs (i.e. are in transition from class II to class III). The transition disc fraction is comparable to low-mass stars.We estimate that the time-scale for a typical transition from class II to class III is less than 0.4 Myr for brown dwarfs. These results suggest that the evolution of brown dwarf discs mirrors the behaviour of discs around low-mass stars, with disc lifetimes of the order of 5 10 Myr and a disc clearing time-scale significantly shorter than 1 Myr.

Dawson, P.↗
NASA NTRS2012

An Fe XXIV Absorption Line in the Persistent Spectrum of the Dipping Low-Mass X-Ray Binary 1A 1744-361

We report on Chandra X-ray Observatory (Chandra) High Energy Transmission Grating spectra of the dipping low-mass X-ray binary 1A 1744−361 during its 2008 July outburst. We find that its persistent emission is well modeled by a blackbody (kT approx. 1.0 keV) plus power law (Gamma approx. 1.7) with an absorption edge. In the residuals of the combined spectrum, we find a significant absorption line at 6.961 +/- 0.002 keV, consistent with the Fe xxvi (hydrogen-like Fe) 2-1 transition.We place an upper limit on the velocity of a redshifted flow of nu < 221 km/s. We find an equivalent width for the line of 27+2/−3 eV, from which we determine a column density of (7 +/- 1)×10(exp 17) /sq. cm via a curve-of-growth analysis. Using XSTAR simulations, we place a lower limit on the ionization parameter of >103.6 erg cm/s. We discuss what implications the feature has on the system and its geometry. We also present Rossi X-ray Timing Explorer data accumulated during this latest outburst and, via an updated color-color diagram, clearly show that 1A 1744−361 is an "atoll" source

stars↗
NASA NTRS2013

Performance Evaluation of Individual Aircraft Based Advisory Concept for Surface Management

Surface operations at airports in the US are based on tactical operations, where departure aircraft primarily queue up and wait at the departure runways. NASA's Spot And Runway Departure Advisor (SARDA) tool was developed to address these inefficiencies through Air Traffic Control Tower advisories. The SARDA system is being updated to include collaborative gate hold, either tactically or strategically. This paper presents the results of the human-in-the-loop evaluation of the tactical gate hold version of SARDA in a 360 degree simulated tower setting. The simulations were conducted for the east side of the Dallas/Fort Worth airport. The new system provides gate hold, ground controller and local controller advisories based on a single scheduler. Simulations were conducted with SARDA on and off, the off case reflecting current day operations with no gate hold. Scenarios based on medium (1.2x current levels) and heavy (1.5x current levels) traffic were explored. Data collected from the simulation was analyzed for runway usage, delay for departures and arrivals, and fuel consumption. Further, Traffic Management Initiatives were introduced for a subset of the aircraft. Results indicated that runway usage did not change with the use of SARDA, i.e., there was no loss in runway throughput as compared to baseline. Taxiing delay was significantly reduced with the use of advisory by 45% in medium scenarios and 60% in heavy. Arrival delay was unaffected by the use of advisory. Total fuel consumption was also reduced by 23% in medium traffic and 33% in heavy. TMI compliance appeared unaffected by the advisory

departure metering↗
NASA NTRS2016

Performance Evaluation of SARDA: An Individual Aircraft-Based Advisory Concept for Surface Management

Surface operations at airports in the US are based on tactical operations, where departure aircraft primarily queue up and wait at the departure runways. NASAs Spot And Runway Departure Advisor (SARDA) tool was developed to address these inefficiencies through Air Traffic Control Tower advisories. The SARDA system is being updated to include collaborative gate hold, either tactically or strategically. This paper presents the results of the human-in-the-loop evaluation of the tactical gate hold version of SARDA in a 360 degree simulated tower setting. The simulations were conducted for the east side of the Dallas-Fort Worth airport. The new system provides gate hold, ground controller and local controller advisories based on a single scheduler. Simulations were conducted with SARDA on and off, the off case reflecting current day operations with no gate hold. Scenarios based on medium (1.2x current levels) and heavy (1.5x current levels) traffic were explored. Data collected from the simulation was analyzed for runway usage, delay for departures and arrivals, and fuel consumption. Further, Traffic Management Initiatives were introduced for a subset of the aircraft. Results indicated that runway usage did not change with the use of SARDA, i.e., there was no loss in runway throughput as compared to baseline. Taxiing delay was significantly reduced with the use of advisory by 45 in medium scenarios and 60 in heavy. Arrival delay was unaffected by the use of advisory. Total fuel consumption was also reduced by 23 in medium traffic and 33 in heavy. TMI compliance appeared unaffected by the advisory.

Yoon Jung↗
NASA NTRS2016

Human Exploration System Test-Bed for Integration and Advancement (HESTIA) Support of Future NASA Deep-Space Missions

The Engineering Directorate at the NASA - Johnson Space Center is outfitting a 20-Foot diameter hypobaric chamber in Building 7 to support future deep-space Environmental Control & Life Support System (ECLSS) research as part of the Human Exploration System Test-bed for Integration and Advancement (HESTIA) Project. This human-rated chamber is the only NASA facility that has the unique experience, chamber geometry, infrastructure, and support systems capable of conducting this research. The chamber was used to support Gemini, Apollo, and SkyLab Missions. More recently, it was used to conduct 30-, 60-, and 90-day human ECLSS closed-loop testing in the 1990s to support the International Space Station and life support technology development. NASA studies show that both planetary surface and deep-space transit crew habitats will be 3-4 story cylindrical structures driven by human occupancy volumetric needs and launch vehicle constraints. The HESTIA facility offers a 3-story, 20-foot diameter habitat consistent with the studies' recommendations. HESTIA operations follow stringent processes by a certified test team that including human testing. Project management, analysis, design, acquisition, fabrication, assembly and certification of facility build-ups are available to support this research. HESTIA offers close proximity to key stakeholders including astronauts, Human Research Program (who direct space human research for the agency), Mission Operations, Safety & Mission Assurance, and Engineering Directorate. The HESTIA chamber can operate at reduced pressure and elevated oxygen environments including those proposed for deep-space exploration. Data acquisition, power, fluids and other facility resources are available to support a wide range of research. Recently completed HESTIA research consisted of unmanned testing of ECLSS technologies. Eventually, the HESTIA research will include humans for extended durations at reduced pressure and elevated oxygen to demonstrate very high reliability of critical ECLSS and other technologies.

Marmolejo, Jose↗
NASA NTRS2018

Future of Big Earth Data Analytics

The state of the art of Big Earth Data Analytics can be expected to evolve rapidly in the coming years. The forces driving evolution come from both growth in the data and advancement in the field of data analytics. In the data area, advances in sensor instrumentation and platform miniaturization are increasing both data resolution and coverage, resulting in enormous growth in data Volume. Increases in temporal resolution in particular also generate demands for higher data Velocity. At the same time, the proliferation of instruments and the platforms on which they reside is increasing the Variety of datasets. The Variety increase in turn leads to questions about the Veracity of the data. In the algorithm area, powerful machine learning methods are coming to the fore, particularly Deep Neural Networks. These are powerful at detecting interesting features in the data, integrating many different measurements (i.e., data fusion), and classification problems. However, they are still challenging when seeking explanations of how natural or socio-economic phenomena work using Earth Observations. Thus, classical analysis techniques will remain relevant when the emphasis is on forming or testing explanations, as well as to support interactive data exploration.

Lynnes, Christopher↗