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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

A high-resolution OGCM simulation of the Tropical Pacific Ocean during the 1985-1994 TOGA period. Part I: Long equatorial waves

A high resolution oceanic general circulation model of the three topical oceans is used to investigate long equatorial wave activity in the Pacific Ocean during the 1985-1994 TOGA period. Zonal wind stress forcing and simulated dynamic height are interpreted using techniques previously applied to data. Kelvin and first Rossby waves are observed propagating during all the period. A seasonal cycle and interannual anomalies are computed for each long equatorial wave. The east Pacific basin is mainly dominated by seasonal cycle variations while strong interannual anomalies are observed west of the dateline. Long wave interannual anomalies are then compared to wave coefficients simulated by a simple wind-forced model. Our results outline the major role played by wind forcing on interannual time scales in generating long equatorial waves. However, near both eastern and western boundaries, some differences can be attributed to long wave reflections. A comparison to wave coefficients calculated from GEOSAT sea-level data gives some insight of the model behavior.

Long Equatorial Waves↗
NASA NTRS2019

Demonstrating Next Generation High-Altitude, Long Endurance Aircraft for Earth Science

This paper will address NASA activities to monitor and study Earth processes from long-duration unmanned aircraft systems (UAS). NASA is currently supporting both large and small UAS development and demonstration. In a follow-on to previous work, NASA Armstrong Flight Research Center is hosting test flights of a large AeroVironment solar-powered aircraft, while NASA Ames Research Center is supporting the demonstration of a light-weight solar powered aircraft by Swift Engineering. Both are designed for long duration, multi-day flight. NASA Earth Science and Aeronautics researchers have been involved in the development and use of High Altitude Long Endurance (HALE) UAS since the 1990's. The NASA Environmental Research Aircraft Sensor and Technology Program (ERAST) demonstrated the promise of HALE aircraft for providing observations while also proving the importance of triple-redundant avionics to improve system reliability for large unmanned aircraft. Early efforts to develop an operational HALE capability for earth observations languished for nearly two decades owing to insufficient solar panel efficiency, battery power density, and light-weight, yet strong, materials. During this time NASA researchers focused on using the Global Hawk to demonstrate the utility of providing diurnal measurements over severe storms (i.e. HS3) and to track stratospheric water vapor transport (ATTREX). Recent significant commercial investments are now leading to the realization of a long-held goal of week- to month-long sustained observations and measurements from the stratosphere. In addition to a historical review of NASA use and interest in HALE aircraft, this paper will present current concepts for exploiting current and planned HALE aircraft capabilities including in situ characterization of atmospheric composition and dynamics as well as imagery collection and internet connectivity. NASA researchers anticipate HALE will also provide a useful means to test smallsat instruments and components. Observations from HALE-based instruments might also provide useful gap-filler observations to flagship satellite missions where the repeat time doesn't allow for measurements of quickly changing phenomenon. HALE will likely also provide measurements and communications relay to facilitate other aircraft in multi-aircraft campaigns. We will also report on progress towards a NASA-supported flight tests solar electric vehicles planned for 2019. One is the Swift Engineering UAS designed to carry 7kg (15lbs) for 30 days at 20km altitude. The other is the AeroVironment Hawk 30, also designed for multi-day flight.

high-altitude↗
NASA NTRSDate not supplied

Sleep during layovers of different lengths after long-haul flying across multiple time zones in different geographic directions

Introduction: Long-haul pilots experience high levels of fatigue and circadian disruption due to long work hours and trans-meridian travel. The aim of this study was to characterize sleep timing and duration during layovers of different lengths after crossing multiple time zones. Methods: All pilots flying long-haul operations from a single airline were eligible to participate. While following their normal work schedule within airline operations, pilots collected data for ~2 weeks including at least two long-haul rotations, with rest days and layovers. Participants wore an Actiwach (Phillips Respironics) throughout the entire study period and completed a sleep diary (at bedtime and upon waking up). Based on the data, we categorized layovers as follows: layover type 1: 34 h after crossing five time zones in westward direction; layover type 2: of 34 h, no time zone change; layover type 3: 55 h after crossing six time zones in eastward direction. Each flight left the home base at the same time of day (23:00) and the flight duration was between 10.5 and 12 hrs. We calculated descriptive statistics for each category. Results. Forty-four long-haul pilots participated in the study (5 female; mean age 44.25 ± 10.06 yrs; mean flight hours 9834.3 ± 5334.1 hrs). We found that for layover type 1, the mean sleep duration (h) per 24 h was 6.90 (±1.04), mean sleep efficiency (%) was 81.08 (±10.89) and mean Wake After Sleep Onset (WASO, min) was 33.23 (±20.42); for layover type 2, the mean sleep duration (h) per 24 h was 6.91 (±1.06), mean sleep efficiency (%) was 81.71 (±6.80), and mean WASO (min) was 30.10 (±11.00); for layover type 3, the mean sleep duration (h) was 7.07 (±1.32), mean sleep efficiency (%) was 83.93 (±6.04), and mean WAS (min) was 36.94 (±17.95). Conclusion: Our preliminary analyses showed that sleep duration and sleep efficiency were similar for the layovers of same length regardless time zone change. Additional analyses will be conducted to investigate sleep on additional layovers of different lengths and the effects of sleep obtained during layover on the performance and alertness on the return flights.

long-haul↗
DOE OSTI2025

Unveiling Unusual Reactivity of SO 2 and Unusual Type of S–X Long Bonds

A new reactivity of SO 2 to form unusual stable M−X−SO 2 (X = F, Cl, H) complexes is unveiled in this study. Moreover, a new type of S−X long bonds, which are significantly longer than traditional S−X covalent bonds, has been discovered. The P,N-ligated Ni−F complex model 1A can bind a SO 2 molecule through the new F−S long bond (2.207 Å), and a stable Ni−F−SO 2 complex 1B is generated, being exergonic by 2.2 kcal/mol. According to natural localized molecular orbital analysis, the new S−F long bond has a unique p(F) → π*(O=S=O) bonding interaction, which is shown to arise from the long S−F length. In comparison, the strength of the new F−S long bond (−2.2 kcal/mol) is found to be significantly stronger than common noncovalent interactions such as the hydrogen and halogen bond. The substituent modulations suggest that the electron-donating groups can increase the strength of new F−S bonds and enhance binding free energies ΔG bind . The scope of possible M−X complexes was explored, and various metals and X (F, Cl, and H) ligands were found to form stable M−X−SO 2 complexes. Specifically, the anionic M−X complexes display much higher ΔG bind values, ranging from −8 to −10 kcal/mol. The study paves the way for a green, recyclable, and adjustable SO 2 absorption method.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1974

Management and design of long-life systems; Proceedings of the Symposium, Denver, Colo., April 24-26, 1973

The long life of Pioneer interplanetary spacecraft is considered along with a general accelerated methodology for long-life mechanical components, dependable long-lived household appliances, and the design and development philosophy to achieve reliability and long life in large turbine generators. Other topics discussed include an integrated management approach to long life in space, artificial heart reliability factors, and architectural concepts and redundancy techniques in fault-tolerant computers. Individual items are announced in this issue.

Schurmeier, H. M.↗
NASA NTRS1975

Attempt at correlating Italian long lineaments from LANDSAT-1 satellite images with some geological phenomena. Possible use in geothermal energy research

By utilizing the images from the LANDSAT-1, in the spectral band 0.8-1.1 microns (near infrared), a photomosaic was obtained of Italian territory. From this mosaic the field of long lineaments was drawn, corresponding to fractures of the earth crust more than 100 km long. The relationship between lineaments, hot springs, volcanic areas, and earthquake epicenters is verified. There is a clear connection between long lineaments and hot springs: 78% of the springs are located on one or more lineaments, and the existence of hot lineaments was observed. A slightly weaker, but still significant, connection exists between the Pliocene-Quaternary volcanic areas and long lineaments. The relationship between earthquakes and long lineaments can only be verified in some cases. The lineaments which can be related to earthquakes have little or no connection with the other phenomena.

Barbier, E.↗
NASA NTRS1978

Modulation of short waves by long waves

Wave-tank experiments were performed to investigate the cyclic short-wave energy changes, related in phase to an underlying long wave, which occur during active generation of the short-wave field by wind. Measurements of time series of the short-wave slope were made by a laser-optical system, where the basic long-wave parameters were controlled and wind speeds were accurately reproducible. The short-wave slope variances were found to exhibit cyclic variations that are related to the phase of the long wave. The variations result from two combined effects: (1) the short wave frequency is varied by the long-wave orbital velocity; (2) the energy of the short waves is modulated by the actions of aerodynamic and hydrodynamic couplings that operate on the short waves in a manner related to the long-wave phase.

Reece, A. M., Jr.↗
NASA NTRS1982

Investigation of the interference effects of mixed flow long duct nacelles on a DC-10 wing

Wind tunnel test results utilizing a 4.7 percent scale semispan model in the 11 foot transonic wind tunnel are presented. A low drag long duct nacelle installation for the DC-10 jet transport was developed. A long duct nacelle representative of a CF6-50 mixed flow configuration was investigated on the DC-10-30. The results showed that the long duct nacelle installation located in the same position as the current short duct nacelle and with the current production symmetrical pylon is a relatively low risk installation for the DC-10 aircraft. Tuft observations and analytical boundary layer analysis confirmed that the flow on the nacelle afterbody was attached. A small pylon fairing was evaluated and found to reduce channel peak suction pressures, which resulted in a small drag improvement. The test also confirmed that the optimum nacelle incidence angle is the same as for the short duct nacelle, thus the same engine mount as for the production short duct nacelle can be used for the long duct nacelle installation. Comparison of the inboard wing pylon nacelle channel pressure distributions, with flow through and powered long duct nacelles showed that the power effects did not change the flow mechanism; hence, power effects can be considered negligible.

Patel, S. P.↗
NASA NTRS1991

Stirling engine: Available tools for long-life assessment

A review is presented for the durability approaches applicable to long-time life assessment of Stirling engine hot-section components. The crucial elements are experimental techniques for generating long-time materials property data (both monotonic and cyclic flow and failure properties); analytic representations of slow strain rate material stress-strain response characteristics (monotonic and cyclic constitutive relations) at high temperatures and low stresses and strains; analytic creep-fatigue-environmental interaction life prediction methods applicable to long lifetimes at high temperatures and small stresses and strains; and experimental verification of life predictions. Long-lifetime design criteria for materials of interest are woefully lacking. Designing against failures due to creep, creep-rupture, fatigue, environmental attack, and creep-fatigue-environmental interaction will require considerable extrapolation. Viscoplastic constitutive models and time-temperature parameters will have to be calibrated for the hot-section materials of interest. Analysis combined with limited verification testing in a short-time regime will be required to build confidence in long-lifetime durability models.

Halford, Gary R.↗
NASA NTRS1991

Stirling engine - Available tools for long-life assessment

A review is presented for the durability approaches applicable to long-time life assessment of Stirling engine hot-section components. The crucial elements are experimental techniques for generating long-time materials property data (both monotonic and cyclic flow and failure properties); analytic representations of slow strain rate material stress-strain response characteristics (monotonic and cyclic constitutive relations) at high temperatures and low stresses and strains; analytic creep-fatigue-environmental interaction life prediction methods applicable to long lifetimes at high temperatures and small stresses and strains; and experimental verification of life predictions. Long-lifetime design criteria for materials of interest are woefully lacking. Designing against failures due to creep, creep-rupture, fatigue, environmental attack, and creep-failure-environmental interaction will require considerable extrapolation. Viscoplastic constitutive models and time-temperature parameters will have to be calibrated for the hot-section materials of interest. Analysis combined with limited verification testing in a short-time regime will be required to build confidence in long-lifetime durability models.

Halford, Gary R.↗
NASA NTRS1992

Potential of long-baseline infrared interferometry for narrow-angle astrometry

Narrow-angle astrometry has many astrophysical applications, from the measurement of parallaxes to the search for planets around nearby stars. Ground-based long-focus telescopes with photoelectric detectors have achieved accuracies of about 2-3 milliarcsec in 1 h. This accuracy is limited primarily by the atmosphere, and is consistent with models of atmospheric turbulence. However, applying these turbulence models to observations with long-baseline interferometers yields astrometric errors that are far smaller than can be achieved with long-focus telescopes. The predictions for the ultimate accuracy of ground-based narrow-angle astrometry using long-baseline IR (2.2 micron) stellar interferometers are very promising. With the excellent seeing at a high altitude site like Mauna Kea, the atmospheric limit for a 1 h astrometric measurement is expected to be of the order of 10 microarcsec for 1 h of integration. This two-order-of-magnitude improvement over conventional measurements is due to two effects. One is that a long-baseline IR interferometer can find useful reference stars very near an arbitrary target star, so that the atmospherically-induced motions of both stars are highly correlated. The second is that the baseline length can be much larger than the separation of the stellar beams in the turbulent atmosphere, resulting in a reduction in astrometric error with increasing baseline length.

Shao, M.↗
NASA NTRS1994

Possibility to sound the atmospheric ozone by a radiosonde equipped with two temperature sensors, sensitive and non-sensitive to the long wave radiation

The sensitiveness of white coated thermistor sensors and non-sensitiveness of the gold coated over white thermistor sensors (which have been manufactured by a vacuum evaporation process) to long wave radiation were ascertained by some simple experiments in-room and also by analyses of some results of experimental soundings. From results of analyses on the temperature discrepancies caused by long wave radiation, the possibility to sound the atmospheric ozone partial pressure by a radiosonde equipped with two kinds of sensors, sensitive and non-sensitive to the long wave radiation was suggested, and the test results of the newly developed software for the deduction of ozone partial pressure in upper layers was also shown. However, it was found that the following is the necessary condition to realize the purpose. The sounding should be made by a radiosonde equipped with three sensors, instead of two, one being non-sensitive to the long wave radiation perfectly, and the other two also non-sensitive partially to the downward one, with two different angles of exposure upward. It is essential for the realization of the purpose to get two different values of temperature discrepancies simultaneously observed by the three sensors mentioned above and to avoid the troublesome effects of the upward long wave radiation.

Kitaoka, T.↗
NASA NTRS1997

SBUV/2 Long-Term Measurements of Solar Spectral Variability

The NOAA-11 SBUV/2 spectral solar data have been corrected for long-term instrument changes to produce a 5.5 year data record during solar cycle 22 (December 1988 - October 1994). Residual drifts in the data at long wavelengths are +/- 1% or less. At 200-205 nm, where solar variations drive stratospheric photochemistry, these data indicate long-term solar changes of 5-7% from the maximum of Cycle 22 in April 1991 through the end of the NOAA-11 data record. Comparisons of NOAA-11 data with UARS SUSIM and SOLSTICE for the period October 1991 - October 1994, when all 3 instruments were operating simultaneously, show that the observed long-term variations in 200-205 nm irradiance agree to within 2%. This result is consistent with predictions from the Mg-2 proxy index. The SBUV/2 instruments represent a valuable resource for long-term solar UV activity studies because of their overlapping data records. In addition to the NOAA-11 data presented here, the NOAA-9 SBUV/2 instrument began taking data in March 1985 and is still operating, providing a complete record of Cycle 22 behavior from a single instrument. Three additional SBUV/2 instruments are scheduled to be launched between 1997 and 2003, which should permit full coverage of solar cycle 23.

DeLand, Matthew T.↗
NASA NTRS1997

Long-Period Comets and the Oort Cloud

The long-period comets pose a unique problem for the impact hazard problem. Because of their very long orbital] periods and generally large distances from the Sun, they cannot be surveyed and catalogued in the same manner as the near-Earth asteroids and short-period comets. They appear at random, uniformly distributed on the celestial sphere. Current technologies can detect long-period comets at distances of approx. 5 AU, giving somewhat less than a one year warning time for potential Earth impactors. The mean impact probability for a long-period comet crossing the Earth's orbit is 2.2 to 2.5 x 10(exp -9) per perihelion passage. The mean impact velocity is approximately 52 km sec-1 but the most probable impact energy is characterized by a velocity of 56 to 58 km/sec. The estimated current impact rate for cometary nuclei large enough to create 10 km diameter (or larger) craters on the Earth is between 5 x 10(exp -7) and 2.8 x 10(exp -6) per year, with a bed estimated value of 1.0 x 10(exp -6) per year. Nuclei large enough to initiate global climatic disturbances strike the Earth on average every 16 Myr. The impact frequency may be increased substantially for brief periods of time during cometary showers, initiated by major perturbations of the Oort cloud. Improved technologies are needed to detect approaching long-period comets at large heliocentric distances so as to increase the warning time for potential impactors.

Weissman, Paul R.↗
NASA NTRS1999

Demonstration of a Low Cost Cryocooler on a Long Duration Balloon Mission

NASA/GSFC has been evaluating the use of low cost Stirling cycle cryocoolers for aerospace applications since 1994. These include the M77B and M77C cryocoolers built by Sunpower Corporation. To date NASA has tested eight M77B and two M77C cryocoolers, with 8 additional M77C units now under construction. The intent of this work is to determine the flight worthiness of these cryocoolers. The Sunpower M77 coolers are candidate for use on the Ultra Long Duration Balloons presently under development by NASA. The flight on the Long Duration Balloon (LDB) in July 1998 represented an opportunity to test the cryocooler in the high altitude balloon environment in order to gain experience to prepare for possible opportunities on the Ultra Long Duration Balloon (ULDB) missions. The Long Duration Balloon is typically a 10 to 15 day mission. Typical ULDB missions might be as long as 100 days or more, and it is this duration which now forces many science groups to consider the use of cryocoolers in place of stored cryogens. This paper will present the basic design of the cryocooler experiment, and data acquired during the flight. The paper will also include a general perspective on the use of cryocoolers on future ULDB flights.

James, Edward F.↗
NASA NTRS2004

Common Calibration Source for Monitoring Long-term Ozone Trends

Accurate long-term satellite measurements are crucial for monitoring the recovery of the ozone layer. The slow pace of the recovery and limited lifetimes of satellite monitoring instruments demands that datasets from multiple observation systems be combined to provide the long-term accuracy needed. A fundamental component of accurately monitoring long-term trends is the calibration of these various instruments. NASA s Radiometric Calibration and Development Facility at the Goddard Space Flight Center has provided resources to minimize calibration biases between multiple instruments through the use of a common calibration source and standardized procedures traceable to national standards. The Facility s 50 cm barium sulfate integrating sphere has been used as a common calibration source for both US and international satellite instruments, including the Total Ozone Mapping Spectrometer (TOMS), Solar Backscatter Ultraviolet 2 (SBUV/2) instruments, Shuttle SBUV (SSBUV), Ozone Mapping Instrument (OMI), Global Ozone Monitoring Experiment (GOME) (ESA), Scanning Imaging SpectroMeter for Atmospheric ChartographY (SCIAMACHY) (ESA), and others. We will discuss the advantages of using a common calibration source and its effects on long-term ozone data sets. In addition, sphere calibration results from various instruments will be presented to demonstrate the accuracy of the long-term characterization of the source itself.

Kowalewski, Matthew↗
NASA NTRS2001

Psychosocial issues in long-term space flight: overview

Anecdotal evidence of the individual and interpersonal problems that occurred during the Shuttle-Mir Space Program (SMSP) and other long-duration Russian/Soviet missions, and studies of personnel in other isolated and confined extreme (ICE) environments suggest that psychosocial elements of behavior and performance are likely to have a significant impact on the outcome of long-duration missions in space. This impact may range from individual decrements in performance, health and well being, to catastrophic mission failure. This paper reviews our current understanding of the psychosocial issues related to long duration space missions according to three different domains of behavior: the individual domain, the interpersonal domain and the organizational domain. Individual issues include: personality characteristics that predict successful performance, stress due to isolation and confinement and its effect on emotions and cognitive performance, adaptive and maladaptive coping styles and strategies, and requirements for the psychological support of astronauts and their families during the mission. Interpersonal issues include: impact of crew diversity and leadership styles on small group dynamics, adaptive and maladaptive features of ground-crew interactions, and processes of crew cohesion, tension and conflict. Organizational issues include: the influence of organizational culture and mission duration on individual and group performance, and managerial requirements for long duration missions. Improved screening and selection of astronaut candidates, leadership, coping and interpersonal skills training of personnel, and organizational change are key elements in the prevention of performance decrements on long-duration missions.

Review, Tutorial↗
NASA NTRS2002

Long-term (6-wk) hindlimb suspension inhibits spermatogenesis in adult male rats

The International Space Station will allow extended habitation in space and long-term exposure to microgravity (microG). A concern is the impact of long-term microG exposure on the ability of species to reproduce. The model often used to simulate microG is rat hindlimb suspension (HLS), where the hindlimbs are elevated above the cage floor with a tail harness. Experiments described here are the first to examine the effect of long-term HLS on testicular function in adult male rats. Free-roaming (controls), animals with only the tail harnessed but hindlimbs in contact with the cage floor (TO), and HLS animals were tested for 6 wk. Cryptorchidism was prevented in TO and HLS animals by partial constriction of the inguinal canal with sutures. All parameters were compared at the end of the 6-wk experiment. Testicular weights and spermatogenesis were significantly reduced by HLS, such that no spermatogenic cells beyond round spermatids were present and epididymides were devoid of mature sperm. In many tubules, loss of all germ cells, except a few spermatogonia, resulting in histopathology similar to the Sertoli cell, was observed. Spermatogenesis appeared unaffected in control and TO animals. Sertoli and Leydig cell appearance, testosterone, luteinizing hormone, and follicle-stimulating hormone levels, and epididymal and seminal vesicle weight were unchanged by HLS. Cortisone was not elevated by HLS; thus stress may not be a factor. These results demonstrate that spermatogenesis is severely inhibited by long-term HLS, whereas testicular androgen production is not. These results have significant implications regarding serious effects of long-term exposure to microG on the reproductive capability of scrotal mammals, including humans.

NASA Discipline Cell Biology↗