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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Visual field information in Nap-of-the-Earth flight by teleoperated Helmet-Mounted displays

The human ability to derive Control-Oriented Visual Field Information from teleoperated Helmet-Mounted displays in Nap-of-the-Earth flight, is investigated. The visual field with these types of displays originates from a Forward Looking Infrared Radiation Camera, gimbal-mounted at the front of the aircraft and slaved to the pilot's line-of-sight, to obtain wide-angle visual coverage. Although these displays are proved to be effective in Apache and Cobra helicopter night operations, they demand very high pilot proficiency and work load. Experimental work presented in the paper has shown that part of the difficulties encountered in vehicular control by means of these displays can be attributed to the narrow viewing aperture and head/camera slaving system phase lags. Both these shortcomings will impair visuo-vestibular coordination, when voluntary head rotation is present. This might result in errors in estimating the Control-Oriented Visual Field Information vital in vehicular control, such as the vehicle yaw rate or the anticipated flight path, or might even lead to visuo-vestibular conflicts (motion sickness). Since, under these conditions, the pilot will tend to minimize head rotation, the full wide-angle coverage of the Helmet-Mounted Display, provided by the line-of-sight slaving system, is not always fully utilized.

Grunwald, Arthur J.↗
NASA NTRS1988

Orbital analysis for atmospheric trace molecule spectroscopy (ATMOS) Shuttle missions

An orbital analysis was carried out to define the geographical coverage capabilities of an ATMOS solar occultation experiment on Space Shuttle/Spacelab missions. Particular attention was given to the effects of launch time, orbit inclination, altitude, and season on latitude-longitude coverage. It is shown that the widest band of latitude coverage in the tropics and temperate zones can be achieved with a midinclined orbit and a midmorning or late-night launch time. The use of ATMOS Shuttle underflights to provide coincident measurements with a solar occultation experiment on the Upper Atmospheric Research Satellite is also examined.

Harrison, Edwin F.↗
NASA NTRS2010

Aerosol-Induced Changes of Convective Cloud Anvils Produce Strong Climate Warming

The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm(exp-2) . Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing. We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvi1 clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming) at top-of-atmosphere. Furthermore we introduce the cloud optical depth (r), cloud height (Z) forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene. Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds; increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

Koren, I.↗
NASA NTRS1994

Planning and scheduling the Hubble Space Telescope: Practical application of advanced techniques

NASA's Hubble Space Telescope (HST) is a major astronomical facility that was launched in April, 1990. In late 1993, the first of several planned servicing missions refurbished the telescope, including corrections for a manufacturing flaw in the primary mirror. Orbiting above the distorting effects of the Earth's atmosphere, the HST provides an unrivaled combination of sensitivity, spectral coverage and angular resolution. The HST is arguably the most complex scientific observatory ever constructed and effective use of this valuable resource required novel approaches to astronomical observation and the development of advanced software systems including techniques to represent scheduling preferences and constraints, a constraint satisfaction problem (CSP) based scheduler and a rule based planning system. This paper presents a discussion of these systems and the lessons learned from operational experience.

Miller, Glenn E.↗
DOE OSTI2024

Catalytic Resonance Theory: Turnover Efficiency and the Resonance Frequency

Programmable catalysts exhibiting forced oscillation in the free energy of reacting surface species were simulated to understand the general mechanisms leading to efficient use of the input energy. Catalytic ratchets with either positive or negative adsorbate scaling exhibited oscillation conditions of both high and low turnover efficiency, yielding catalytic turnover frequencies either close to or significantly lower than the applied catalyst oscillation frequency, respectively. The “effective rate”, defined as the product of the catalytic turnover frequency and the turnover efficiency (ηTOE), was limited via two catalytic mechanisms: a leaky catalytic ratchet existed when molecules repeatedly traversed backward through the catalytic transition state upon catalyst oscillation, while a catalytic ratchet with low surface participation exhibited reduced formation of a gas-phase final product due to low surface product coverage. Furthermore, a single applied frequency yielding a maximum effective catalytic rate defined as the “resonance frequency” provided maximum combined benefit for catalytic rate and efficiency.

25 ENERGY STORAGE↗
DOE OSTI2026

Minimized aging of isocyanurate-based rigid cellular foams for buildings through tailored barrier facers and optimized formulation

The thermal resistivity (h·ft 2 ·°F/Btu/in.) of closed-cell rigid foam insulation materials significantly decreases over time. Diffusion-tight facers are designed to significantly enhance initial thermal resistivity and long-term thermal performance by preventing gas diffusion into the foam cells and inhibiting the escape of low thermal conductivity blowing agents. In addition to the gas diffusion property of the facer film, adhesion between the foam and the facer is crucial for achieving diffusion-tight bonding. Here, this study addresses the challenge of thermal aging by investigating how facer film properties and foam formulation influence the durability of thermal performance. A systematic evaluation was conducted to understand the effects of polymeric barrier films, surface treatments, facer coverage, and foam matrix rigidity on thermal resistivity over time. Key findings reveal that diffusion-tight facers, particularly those with metallized layers and compatible heat seal layers, significantly reduce gas exchange and improve foam-facer adhesion. The optimized system, incorporating barrier facers and a tailored polyisocyanurate foam formulation, achieved initial and aged thermal resistivity values after 200 days of approximately 8.3 and 7.4 h ft 2 ·°F/Btu/in., respectively representing only a 10 % reduction compared to a 17 % reduction observed in control samples without facers. Notably, polyurethane spray foams with facers exhibited only a 4 % reduction in thermal resistivity, compared to a 23 % decrease in control samples, demonstrating nearly six times better retention of thermal performance. This innovative facer technology presents a promising solution for reducing energy costs and represents a significant advancement in optimizing energy management for building envelopes in future technologies. This technology can also be adapted for other applications that necessitate the preservation of long-term thermal performance.

Wanasinghe, Shiwanka Vidarshi [Oak Ridge National ↗
NASA NTRS1973

Further study of the theta component of the interplanetary magnetic field.

Measurements of the interplanetary magnetic field taken with Imp 3, Pioneer 6, and Explorer 34 constitute a large portion of the data available at low and moderate solar activity and provide nearly continuous coverage from mid-1965 through 1966 without radial effects. Study of these observations provides further evidence for the following B sub theta effect initially discovered with Mariners 2, 4, and 5. At low or moderate solar activity, the mean value of B sub theta is negative (approximately northward in the observations) above the solar equatorial plane and positive below it for an interplanetary field directed outward from the sun, and vice versa for an inward field. Thus, for an outward field, the r-theta component of a line of magnetic force above or below the equatorial plane was skewed relative to the average value of r in the direction away from the equatorial plane. Comparisons between different spacecraft are discussed.

Rosenberg, R. L.↗
NASA NTRS1974

Study of recreational land and open space using Skylab imagery

The author has identified the following significant results. Sl90B color photography has adequate resolution to detect or identify many natural and cultural features which are significant for the evaluation of recreational land and open space. The effectiveness of the interpretation could be improved if coverage were obtained at two or three different seasons so that indicators such as seasonal changes in vegetation cover or snow enhancement could aid the interpretation of land use and land cover. The degree of detail which can be observed from Sl90B photography makes it useful for the following purposes: (1) Photography can be used to obtain general familiarity with a large regional area, and to study interrelationships of major natural and cultural features within the area. (2) Existing recreational facilities such as golf courses, parks, stadiums, race tracks, and marinas can be detected and identified. (3) The photography can be used for initial selection of recreation sites. (4) It would also indicate trends in population growth, which constitute one type of information needed in estimating the growth of recreation demand. The photography has only limited use for planning individual site planning of parks, golf courses, and other recreation facilities.

Sattinger, I. J.↗
NASA NTRS1981

A numerical evaluation of TIROS-N and NOAA-6 analyses in a high resolution limited area model

Vertical temperature profiles derived from TIROS-N and NOAA-6 radiance measurements were used to create separate analyses for the period 0000 GMT 6 January to 0000 GMT 7 January 1980. The 0000 GMT 6 January satellite analyses and a conventional analysis were used to initialize and run the University of Wisconsin's version of the Australian Region Primitive Equations model. Forecasts based on conventional analyses were used to evaluate the forecasts based only on satellite upper air data. The forecasts based only on TIROS-N or NOAA-6 data did reasonably well in locating the main trough and ridge positions. The satellite initial analyses and forecasts revealed errors correlated to the synoptic situation. The trough in both TIROS-N and NOAA-6 forecasts which was initially too warm remained too warm as it propagated eastward during the forecast period. Thus, it is unlikely that the operational satellite data will improve forecasts in a data dense region. However, in regions of poor data coverage, the satellite data should have a beneficial effect on numerical forecasts.

Derber, J. C.↗
NASA NTRS1984

Non-local Origin of a Substantial Portion of the Soft X-ray Background

Comparison of the SAS-3 soft X-ray sky survey with the 21-cm neutral hydrogen survey confirms the well-known anticorrelation between the counting rates in the C-band (0.10-0.28 keV) and the column density of neutral hydrogen, and demonstrates that this anticorrelation is significant on all angular scales ranging from that of the general trend from the galactic equator to the poles down to the angular resolution of the detector (2.07 FWHM). Numerous instances of what appear to be soft X-ray shadows of nearly (100-300 pc) 21-cm features, and several bright X-ray regions coincident with holes in the interstellar medium are included in this general correlation. The final set of selected data has an exposure of 2.2 x 10 to the 4th power/sq cm s sr, a sky coverage of 80%, and is free of spurious effects due to charged particles and solar radiations. The validity of the two-component model of the X-ray background, introduced by Davidsen et al. (1977) is examined. In this model the C-band intensity in a given direction is represented as a sum of a constant term, I sub 1, due to unattenuated emission from a local hot bubble in which the solar system is immersed, and a term, I sub 2 exp (N sub H sub th) , due to emission from a diffuse source beyond the neutral hydrogen 2.g., the galactic corona).

Clark, G. W.↗
NASA NTRS1985

Origin of the difference of the coverage-dependent vibrational shift for S on Ni(100) and O on Ni(100)

The p(2 x 2) and c(2 x 2) coverages of S on Ni(100) are studied with a cluster model. Consistent with a recent lattice-dynamics study, the chemical contribution (rigid Ni lattice) to the coverage-dependent shift of the S vibrational energy is of opposite sign to that for O. Analysis of the cluster wave functions suggests that S becomes less negatively charged with coverage, while O becomes more ionic; however, this effect is small.

Bauschlicher, C. W., Jr.↗
NASA NTRS1988

A fault injection experiment using the AIRLAB Diagnostic Emulation Facility

The preparation for, conduct of, and results of a simulation based fault injection experiment conducted using the AIRLAB Diagnostic Emulation facilities is described. An objective of this experiment was to determine the effectiveness of the diagnostic self-test sequences used to uncover latent faults in a logic network providing the key fault tolerance features for a flight control computer. Another objective was to develop methods, tools, and techniques for conducting the experiment. More than 1600 faults were injected into a logic gate level model of the Data Communicator/Interstage (C/I). For each fault injected, diagnostic self-test sequences consisting of over 300 test vectors were supplied to the C/I model as inputs. For each test vector within a test sequence, the outputs from the C/I model were compared to the outputs of a fault free C/I. If the outputs differed, the fault was considered detectable for the given test vector. These results were then analyzed to determine the effectiveness of some test sequences. The results established coverage of selt-test diagnostics, identified areas in the C/I logic where the tests did not locate faults, and suggest fault latency reduction opportunities.

Baker, Robert↗
NASA NTRS2005

NASA Land Information System (LIS) Water Availability to Support Reclamation ET Estimation

The U.S. Bureau of Reclamation identified the remote sensing of evapotranspiration (ET) as an important water flux for study and designated a test site in the Lower Colorado River basin. A consortium of groups will work together with the goal to develop more accurate and cost effective techniques using the enhanced spatial and temporal coverage afforded by remote sensing. ET is a critical water loss flux where improved estimation should lead to better management of Reclamation responsibilities. There are several areas where NASA satellite and modeling data may be useful to meet Reclamation's objectives for improved ET estimation. In this paper we outline one possible contribution to use NASA's data integration capability of the Land Information System (LIS) to provide a merger of observational (in situ and satellite) with physical process models to provide estimates of ET and other water availability outputs (e.g., runoff, soil moisture) retrospectively, in near real-time, and also providing short-term predictions.

Toll, David↗
NASA NTRS2013

Creating a Satellite-Based Record of Tropospheric Ozone

The TES retrieval algorithm has been applied to IASI radiances. We compare the retrieved ozone profiles with ozone sonde profiles for mid-latitudes for the year 2008. We find a positive bias in the IASI ozone profiles in the UTLS region of up to 22 %. The spatial coverage of the IASI instrument allows sampling of effectively the same air mass with several IASI scenes simultaneously. Comparisons of the root-mean-square of an ensemble of IASI profiles to theoretical errors indicate that the measurement noise and the interference of temperature and water vapour on the retrieval together mostly explain the empirically derived random errors. The total degrees of freedom for signal of the retrieval for ozone are 3.1 +/- 0.2 and the tropospheric degrees of freedom are 1.0 +/- 0.2 for the described cases. IASI ozone profiles agree within the error bars with coincident ozone profiles derived from a TES stare sequence for the ozone sonde station at Bratt's Lake (50.2 deg N, 104.7 deg W).

pollutant↗
NASA NTRS1993

New mission requirements methodologies for services provided by the Office of Space Communications

The Office of Space Communications, NASA Headquarters, has recently revised its methodology for receiving, accepting and responding to customer requests for use of that office's tracking and communications capabilities. This revision is the result of a process which has become over-burdened by the size of the currently active and proposed missions set, requirements reviews that focus on single missions rather than on mission sets, and negotiations most often not completed early enough to effect needed additions to capacity or capability prior to launch. The requirements-coverage methodology described is more responsive to project/program needs and provides integrated input into the NASA budget process early enough to effect change, and describes the mechanisms and tools in place to insure a value-added process which will benefit both NASA and its customers. Key features of the requirements methodology include the establishment of a mechanism for early identification of and systems trades with new customers, and delegates the review and approval of requirements documents to NASA centers in lieu of Headquarters, thus empowering the system design teams to establish and negotiate the detailed requirements with the user. A Mission Requirements Request (MRR) is introduced to facilitate early customer interaction. The expected result is that the time to achieve an approved set of implementation requirements which meet the customer's needs can be greatly reduced. Finally, by increasing the discipline in requirements management, through the use of base lining procedures, a tighter coupling between customer requirements and the budget is provided. A twice-yearly projection of customer requirements accommodation, designated as the Capacity Projection Plan (CPP), provides customer feedback allowing the entire mission set to be serviced.

Holmes, Dwight P.↗
NASA NTRS2004

Human-Induced Climate Variations Linked to Urbanization: From Observations to Modeling

The goal of this session is to bring together scientists from interdisciplinary backgrounds to discuss the data, scientific approaches and recent results focusing on the impact of urbanization on the climate. The discussion will highlight current observational and modeling capabilities being employed for investigating the urban environment and its linkage to the change in the Earth's climate system. The goal of the session is to identify our current stand and the future direction on the topic. Urbanization is one of the extreme cases of land use change. Most of population of the world has moved to urban areas. By 1995, more than 70% of population of North America and Europe were living in cities. By 2025, the United Nations estimates that 60% of the worlds population will live in cities. Although currently only 1.2% of the land is urban, better understanding of how the atmosphere-ocean-land-biosphere components interact as a coupled system and the influence of human activities on this system is critical. Our understanding of urbanization effect is incomplete, partly because human activities induce new changes on climate in addition to the original natural variations, and partly because previously few data available for study urban effect globally. Urban construction changes surface roughness, albedo, heat capacity and vegetation coverage. Traffic and industry increase atmospheric aerosol. It is suggested that urbanization may modify rainfall processes through aerosol-cloud interactions or dynamic feedbacks. Because urbanization effect on climate is determined by many factors including land cover, the city's microscale features, population density, and human lifestyle patterns, it is necessary to study urban areas over globe.

Shepherd, J. Marshall↗
NASA NTRS1996

Model-based sensor location selection for helicopter gearbox monitoring

A new methodology is introduced to quantify the significance of accelerometer locations for fault diagnosis of helicopter gearboxes. The basis for this methodology is an influence model which represents the effect of various component faults on accelerometer readings. Based on this model, a set of selection indices are defined to characterize the diagnosability of each component, the coverage of each accelerometer, and the relative redundancy between the accelerometers. The effectiveness of these indices is evaluated experimentally by measurement-fault data obtained from an OH-58A main rotor gearbox. These data are used to obtain a ranking of individual accelerometers according to their significance in diagnosis. Comparison between the experimentally obtained rankings and those obtained from the selection indices indicates that the proposed methodology offers a systematic means for accelerometer location selection.

Jammu, Vinay B.↗
NASA NTRS1979

Mission analysis for earth atmospheric measurements using solar occultation experiments on Shuttle Spacelabs

The maximum geographical coverage of solar occultation experiments for various Shuttle-Spacelab mission concepts is defined and an analysis that includes trade-offs between parameters such as launch time, season, orbital inclination and altitude is presented as well as the mission design data for the Spacelab-3 flight. The effects of orbital ranges from 220 to 600 km on geographical coverage are examined with inclinations up to 97 deg for sun-synchronous orbit. Results show that the widest band of latitude coverage in the tropics and the temperate zones can be achieved with a mid-inclined (i.e., 57 deg) orbit and a mid-morning or late-night launch time.

Harrison, E. F.↗