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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 NTRS2023

The Statistical Emulators of GGCMI Phase 2: Responses of Year-to-Year Variation of Crop Yield to CO 2 , Temperature, Water and Nitrogen Perturbations

Understanding the impact of climate change on year-to-year variation of crop yield is critical to global food stability and security. While crop model emulators are believed to be lightweight tools to replace the models, few emulators have been developed to capture such interannual variation of crop yield in response to climate variability. In this study, we developed a statistical emulator with a machine learning algorithm to reproduce the response of year-to-year variation of four crop yields to CO 2 (C), temperature (T), water (W), and nitrogen (N) perturbations defined in the Global Gridded Crop Model Intercomparison Project (GGCMI) phase 2. The emulators were able to explain more than 52 % of the variance of simulated yield and performed well in capturing the year-to-year variation of global average and gridded crop yield over current croplands in the baseline. With the changes in CO 2 –temperature–water–nitrogen (CTWN) perturbations, the emulators could reproduce the year-to-year variation of crop yield well over most current cropland. The variation of R and the mean absolute error was small under the single CTWN perturbations and dual-factor perturbations. These emulators thus provide statistical response surfaces of yield, including both its mean and interannual variability, to climate factors. They could facilitate spatiotemporal downscaling of crop model simulation, projecting the changes in crop yield variability in the future and serving as a lightweight tool for multi-model ensemble simulation. The emulators enhanced the flexibility of crop yield estimates and expanded the application of large-ensemble simulations of crop yield under climate change.

Climate change↗
NASA NTRS1992

Long-term particle flux variability indicated by comparison of Interplanetary Dust Experiment (IDE) timed impacts for LDEF's first year in orbit with impact data for the entire 5.75-year orbital lifetime

The electronic sensors of the Interplanetary Dust Experiment (IDE) recorded precise impact times and approximate directions for submicron to approximately 100-micron size particles on all six primary sides of the spacecraft for the first 346 days of the Long Duration Exposure Facility (LDEF) orbital mission. Previously-reported analyses of the timed impact data have established their spatio-temporal features, including the demonstration that a preponderance of the particles in this regime are orbital debris and that a large fraction of the debris particles are encountered as megameter-size clouds, some of which persist for long times. Short-term fluxes within such clouds can rise several orders of magnitude above the long-term average. These finding are consistent with the results of the first catastrophic hypervelocity laboratory impacts on a real satellite, recently reported in the press. Analysis continues on the geometric and evolutionary characteristics of these clouds, as well as on the isolation and characterization of the natural micrometeoroid component in the IDE data, but the unexpectedly large short-term variations in debris flux raises the question of how representative an indication of the multi-year average flux is given by the nearly one year of timed data. It has, therefore, always been one of the goals of IDE to conduct an optical survey of the craters on the IDE detectors, to obtain full-mission fluxes for comparisons with the timed data. This work is underway, and the results presently in hand are significant. Optical scanning of the ram and wake (East and West) panels is complete, and it is clear that the first year was in some respects not representative of the subsequent years. The 5.75-year average flux on East panel was 90 percent of the value predicted by the average flux recorded during the first year, while it was only 34 percent on West panel. This suggests that western hemisphere spacecraft launches are a major contributor to the long-term flux and that their contribution is primarily in the smaller end of the size distribution. This conclusion follows from the fact that a closely-spaced series of launch failures (Titan, Delta, Ariane, and Challenger) caused a virtual hiatus in launch activity during a large part of the later years of the LDEF mission. We hope to provide a quantification of the particle size distribution function in this case.

Mulholland, J. Derral↗
NASA NTRS1993

Long-term microparticle flux variability indicated by comparison of Interplanetary Dust Experiment (IDE) timed impacts for LDEF's first year in orbit with impact data for the entire 5.77-year orbital lifetime

The electronic sensors of the Interplanetary Dust Experiment (IDE) recorded precise impact times and approximate directions for submicron to approximately 100 micron size particles on all six primary sides of the spacecraft for the first 346 days of the LDEF orbital mission. Previously-reported analyses of the timed impact data have established their spatio-temporal features, including the demonstration that a preponderance of the particles in this regime are orbital debris and that a large fraction of the debris particles are encountered in megameter-size clouds. Short-term fluxes within such clouds can rise several orders of magnitude above the long-term average. These unexpectedly large short-term variations in debris flux raise the question of how representative an indication of the multi-year average flux is given by the nearly one year of timed data. One of the goals of the IDE was to conduct an optical survey of impact sites on detectors that remained active during the entire LDEF mission, to obtain full-mission fluxes. We present here the comparisons and contrasts among the new IDE optical survey impact data, the IDE first-year timed impact data, and impact data from other LDEF micrometeoroid and debris experiments. The following observations are reported: (1) the 5.77 year long-term integrated microparticle impact fluxes recorded by IDE detectors matched the integrated impact fluxes measured by other LDEF investigators for the same period; (2) IDE integrated microparticle impact fluxes varied by factors from 0.5 to 8.3 for LDEF days 1-346, 347-2106 and 1-2106 (5.77 years) on rows 3 (trailing edge, or West), 6 (South side), 12 (North side), and the Earth and Space ends; and (3) IDE integrated microparticle impact fluxes varied less than 3 percent for LDEF days 1-346, 347-2106 and 1-2106 (5.77 years) on row 9 (leading edge, or East). These results give further evidence of the accuracy and internal consistency of the recorded IDE impact data. This leads to the further conclusion that the utility of long-term ratios for impacts on various sides of a stabilized satellite in low Earth orbit (LEO) is extremely limited. These observations and their consequences highlight the need for continuous, real time monitoring of the dynamic microparticle environment in LEO.

Simon, Charles G.↗
NASA NTRS1980

Illustration of year-to-year variation in wheat spectral profile crop growth curves

Data previously compiled on the year to year variability of spectral profile crop growth parameters for spring and winter wheat in Kansas, Oklahoma, and the Dakotas were used with a profile model to develop graphs illustrating spectral profile crop growth curves for a number of years and a number of spring and winter wheat segments. These curves show the apparent variability in spectral profiles for wheat from one year to another within the same segment and from one segment to another within the same year.

Gonzalez, P.↗
NASA NTRS1985

The zonal harmonic and the yearly and half-yearly waves on the Southern Hemisphere in FGGE compared with the mean

The dominant component in the mean annual cycle of sea level pressure in the latitudes north of approx. 40 deg S is the yearly wave, whereas to the south of this latitude a half-yearly wave dominantes. In FGGE, however, the usually small yearly wave was large in the Antarctic, owing to the extraordinarily low pressure there in the winter of 1979. The half-yearly wave's amplitude was appreciably above normal in the center of each ocean in middle latitudes, and below normal at high latitudes. The yearly wave in the zonal geostrophic wind was larger than normal over the Antarctic Ocean. Similar results are obtained at 500 mb. The three month mean stationary waves (zonal harmonic waves) were larger than the mean in FGGE. The intra-annual variation of both amplitude and phase of the monthly mean harmonic waves in FGGE was large, which is not surprising as they contain an appreciable transient component, unlike the long term monthly mean waves.

Vanloon, H.↗
NASA NTRS1988

Dynamical component of seasonal and year-to-year changes in Antarctic and global ozone

The dynamics of the ozone concetration components of the Antarctic ozone hole as related to seasonal and year-to-year temperature changes in August, September, October, and November during the 1979-1985 period is studied using a zonally averaged model in which all transport fields are fixed by input temperature data. The results suggest that, prior to 1984, both the seasonal and year-to year variability of the zonal-mean Antarctic ozone minimum and the surrounding maximum can be accounted for by temperature dynamics without invoking changes in chemical composition (e.g., chlorine content) or special chemistry. The same dynamical mechanism also accounts for the good simulation of the observed seasonal and latitudinal structure of column ozone in other parts of the world. However, chemical depletion of ozone may have become more important after 1984. The model also appears to underpredict the September ozone decline in years, leading to an underprediction of the recent minimum values in the Antarctic ozone hole.

Tung, Ka Kit↗
NASA NTRS2004

Month-to-month and year-to-year reproducibility of high frequency QRS ECG signals

High frequency electrocardiography analyzing the entire QRS complex in the frequency range of 150 to 250 Hz may prove useful in the detection of coronary artery disease, yet the long-term stability of these waveforms has not been fully characterized. Therefore, we prospectively investigated the reproducibility of the root mean squared voltage, kurtosis, and the presence versus absence of reduced amplitude zones in signal averaged 12-lead high frequency QRS recordings acquired in the supine position one month apart in 16 subjects and one year apart in 27 subjects. Reproducibility of root mean squared voltage and kurtosis was excellent over these time intervals in the limb leads, and acceptable in the precordial leads using both the V-lead and CR-lead derivations. The relative error of root mean squared voltage was 12% month-to-month and 16% year-to-year in the serial recordings when averaged over all 12 leads. Reduced amplitude zones were also reproducible up to a rate of 87% and 81%, respectively, for the month-to-month and year-to-year recordings. We conclude that 12-lead high frequency QRS electrocardiograms are sufficiently reproducible for clinical use.

Coronary Disease/diagnosis↗
NASA NTRS2006

Month-to-Month and Year-to-Year Reproducibility of High Frequency QRS ECG signals

High frequency (HF) electrocardiography analyzing the entire QRS complex in the frequency range of 150 to 250 Hz may prove useful in the detection of coronary artery disease, yet the long-term stability of these waveforms has not been fully characterized. We therefore prospectively investigated the reproducibility of the root mean squared (RMS) voltage, kurtosis, and the presence versus absence of reduced amplitude zones (RAzs) in signal averaged 12-lead HF QRS recordings acquired in the supine position one month apart in 16 subjects and one year apart in 27 subjects. Reproducibility of RMS voltage and kurtosis was excellent over these time intervals in the limb leads, and acceptable in the precordial leads using both the V-lead and CR-lead derivations. The relative error of RMS voltage was 12% month-to-month and 16% year-to-year in the serial recordings when averaged over all 12 leads. RAzs were also reproducible at a rate of up to 87% and 8 1 %, respectively, for the month-to-month and year-to-year recordings. We conclude that 12-lead HF QRS electrocardiograms are sufficiently reproducible for clinical use.

Batdorf, Niles↗
NASA NTRS2016

A Year in Space: Early Results and Lessons Learned from the First Year-Long Expedition Aboard the International Space Station

Two ISS crewmembers recently completed the first year-long orbital stay in two decades. International cooperation was central to the success of Mikhail Kornienko from Russia and Scott Kelly from the United States. Their expedition leveraged current mission experience and capitalized on recent advances in health monitoring technology. This unique effort began in 2012 when the program managers of the ISS partner nations adopted two separate goals: greater multilateral cooperation to increase efficiency of inflight research and a year-long expedition to gain familiarity with in-flight durations approaching that required for a Mars mission. These goals were unified when a set of bilateral Russian and American human research investigations was assigned to the year-long mission, augmented by additional investigations from Europe and Japan. For example, Kelly was assigned 18 investigations (twice the complement on standard six-month missions) including two joint U.S.-Russian studies, and two Russian and two Japanese studies. The core set of American investigations was a repetition of six studies Kelly had done on his previous six-month ISS mission, to allow a direct comparison of physiological and behavioral responses of the longer and shorter durations in this single individual. The remainder of his assignments plus those of Kornienko were drawn from currently active national investigations documenting human adaptation to long-duration spaceflight factors or effectiveness of countermeasures against known deleterious adaptations. The two joint U.S.-Russian investigations were the flagship biomedical studies of the year-long expedition. The "Fluid Shifts" study collocated American research equipment alongside a Russian operational stressor device to document the pattern and impacts of the headward fluid shift long known to occur in weightlessness, including its role in ocular changes recently observed in some astronauts. The "Field Test" study investigated the ability of the astronaut and cosmonaut to perform rudimentary tasks requiring sensorimotor coordination immediately after landing to define human capabilities soon after landing on Mars after an extended transit. Both investigations were highly successful in large part to the thorough integration of the implementation processes of the two partners. Kelly's assignment as the one-year crewmember also provided a serendipitous opportunity for the "Twins Study" comparing changes in his body at the genetic level with those occurring on Earth in his identical twin brother Mark Kelly. Data analysis from this expedition will commence in earnest after frozen in-flight samples are delivered to Earth in May aboard a commercial cargo spacecraft. Detailed results are expected in early 2017. Preliminary results and implementation improvements will be reviewed in this presentation.

Charles, J. B.↗
NASA NTRS1995

Twenty years of interplanetary magnetic field variations with periods in the range of 10 days to 3 years

Twenty years of interplanetary magnetic field data collected primarily by the IMP-8 spacecraft near Earth has been analyzed by a dynamic periodogram method in search of significant periodicities in the range of 10 days to 3 years. The method has the advantage of detecting variations with time in the periodicities besides determining the power and phase of the dominant variations. It has been found that the well known periodicities near 1 year and 27 days are strongly modulated by the solar cycle. Both of these periodicities are only detected during solar minimum. During solar maximum. a number of unusual variations are observed. Special emphasis will be placed on the recently reported 1.3 year variation in solar wind parameters besides periods in the interplanetary magnetic field near 51, 73 and 154 days. Correlations with solar wind plasma and solar index variations will also be presented.

Szabo, A.↗
NASA NTRS2013

Crew and Thermal Systems Division Strategic Communications Initiatives in Support of NASA's Strategic Goals: Fiscal Year 2012 Summary and Initial Fiscal Year 2013 Metrics

The NASA strategic plan includes overarching strategies to inspire students through interactions with NASA people and projects, and to expand partnerships with industry and academia around the world. The NASA Johnson Space Center Crew and Thermal Systems Division (CTSD) actively supports these NASA initiatives. At the end of fiscal year 2011, CTSD created a strategic communications team to communicate CTSD capabilities, technologies, and personnel to internal NASA and external technical audiences for collaborative and business development initiatives, and to students, educators, and the general public for education and public outreach efforts. The strategic communications initiatives implemented in fiscal year 2012 resulted in 707 in-reach, outreach, and commercialization events with 39,731 participant interactions. This paper summarizes the CTSD Strategic Communications metrics for fiscal year 2012 and provides metrics for the first nine months of fiscal year 2013.

Paul, Heather L.↗
NASA NTRS1990

Year-to-year instability of the Mars south polar cap

Models of the Mars polar cap energy balance suggest that the south cap has two possible configurations at the current epoch. It can be covered all year by CO2 frost, as was observed by the Viking spacecraft, or the CO2 frost can disappear at midsummer to expose an underlying surface. The difference between the two states depends on the role of energy conducted into the subsurface. If the cap was exposed the previous year, conducted energy will cause less CO2 frost to condense in winter, and the frost will disappear completely in summer. If the cap was covered the previous year, there will be no conducted energy, and it will stay covered again. Subtle effects in the atmosphere can perturb the cap energy balance sufficiently to cause the cap to jump between states. This behavior might provide an explanation for the large southern summer water vapor abundances observed in 1969. It also explains the observed differences between the north and the south residual caps as resulting in part from a difference in the role in the annual energy balance of energy conducted into the subsurface.

Jakosky, Bruce M.↗
NASA NTRS1991

Structural dynamics division research and technology accomplishments for fiscal year 1990 and plans for fiscal year 1991

The research accomplishments of the Structural Dynamics Division for F.Y. 1991 are presented. The work is discussed in terms of highlights of accomplishments during the past year and plans for the current year as they relate to 5-year plans and the objectives of each technical area. Included is research on unsteady aerodynamics, helicopter rotors, computational fluid dynamics, oscillations of leading edge flaps of a delta wing, and aircraft wing loads.

Wynne, Eleanor C.↗
NASA NTRS2001

Variations and Trends in Global and Regional Precipitation Based on the 22-Year GPCP (Global Precipitation Climatology Project) and Three-Year TRMM (Tropical Rainfall Measuring Mission) Data Sets

This paper gives an overview of the analysis of global precipitation over the last few decades and the impact of the new TRMM precipitation observations. The 20+ year, monthly, globally complete precipitation analysis of the World Climate Research Program's (WCRP/GEWEX) Global Precipitation Climatology Project (GPCP) is used to study global and regional variations and trends and is compared to the much shorter TRMM(Tropical Rainfall Measuring Mission) tropical data set. The GPCP data set shows no significant trend in global precipitation over the twenty years, unlike the positive trend in global surface temperatures over the past century. The global trend analysis must be interpreted carefully, however, because the inhomogeneity of the data set makes detecting a small signal very difficult, especially over this relatively short period. The relation of global (and tropical) total precipitation and ENSO events is quantified with no significant signal when land and ocean are combined. Identifying regional trends in precipitation may be more practical. From 1979 to 2000 the tropics have pattern of regional rainfall trends that has an ENSO-like pattern with features of both the El Nino and La Nina. This feature is related to a possible trend in the frequency of ENSO events (either El Nino or La Nina) over the past 20 years. Monthly anomalies of precipitation are related to ENSO variations with clear signals extending into middle and high latitudes of both hemispheres. The El Nino and La Nina mean anomalies are near mirror images of each other and when combined produce an ENSO signal with significant spatial continuity over large distances. A number of the features are shown to extend into high latitudes. Positive anomalies extend in the Southern Hemisphere (S.H.) from the Pacific southeastward across Chile and Argentina into the south Atlantic Ocean. In the Northern Hemisphere (N.H.) the counterpart feature extends across the southern U.S. and Atlantic Ocean into Europe. Further to the west a negative anomaly extends southeastward again from the Maritime Continent across the South Pacific and through the Drake Passage. In the Southern Hemisphere an anomaly feature is shown to spiral into the Antarctica land mass. The extremes of ENSO-related anomalies are also examined and indicate that globally, during both El Nino and La Nina, more extremes of precipitation (both wet and dry) occur than during the "neutral" regime, with the El Nino regime showing larger magnitudes. The distribution is different for the globe as a whole and when the area is restricted to just land. The recent (1998-present) TRMM observations are compared with the similar period of GPCP analyses with very good agreement in terms of pattern and generally good agreement with regard to magnitude. However, there still are differences among the individual TRMM products using passive and active microwave techniques and these need to be resolved before longer-term products such as the GPCP analyses can be validated.

Adler, Robert F.↗
NASA NTRS2003

Fifteen Years of Collaborative Innovation and Achievement: NASA Nebraska Space Grant Consortium 15-Year Program Performance and Results Report

This 15-year evaluation serves as a summary document highlighting the numerous and complete successes of the Nebraska Space Grant Program. Innovation has been highlighted through significant new endeavors during this 5-year period, such as placement of students and faculty at NASA Centers and the expansion of NSGC Native American Outreach Programs. While the last national program evaluation resulted in Nebraska s ranking as the top Capability Enhancement Consortium, and 5th best overall, Nebraska felt there was room for significant growth and development. This has been validated through the recent competitive attainment of Designated Grant status and has allowed for the exploration of new initiatives, as well as the expansion of already successful programs. A comprehensive strategic planning effort has involved all Nebraska representative entities and has guided Nebraska Space Grant through the evaluation period, providing a basis for continual advancement. Nebraska rigorously employs evaluation techniques to ensure that stated outcomes and metrics are achieved and that weaknesses are identified and corrected. With this coordinated approach, Nebraska expects that the next 5 years will yield new opportunities for significant achievement. Nebraska Space Grant will embrace new national endeavors, including the integration of Pender Public Schools -Nebraska s NASA Explorer School, geospatial initiatives, and the National Student Satellite Program.

Schaaf, Michaela M.↗
NASA NTRS2005

[Accomplistments in the Last Year Against the Objectives Laid Out in the Original Proposal; the Current Status of the Research; the Work to go in the Next Year; and Publications]

Below is the annual progress report (through 2005-01-31) on NASA Grant NNG04GF25G. It is organized according to: (I) Accomplishments in the last year against the objectives laid out in the original proposal; (II) The current status of the research; (III) The work to go in the next year; (IV) Publications. Since this program is a continuation of the occultation work supported in a predecessor grant, the "Accomplishments" section lists all the tasks written into the proposal (in June 2003) through the end of the first year of the new grant.

Elliot, James↗
NASA NTRS2009

Geology of the Southern Utopia Planitia Highland-Lowland Boundary Plain: Second Year Results and Third Year Plan

The southern Utopia highland-lowland boundary (HLB) extends >1500 km westward from Hyblaeus Dorsa to the topographic saddle that separates Isidis and Utopia Planitiae. It contains bench-like platforms that contain depressions, pitted cones (some organized into arcuate chains and thumb-print terrain), isolated domes, buried circular depressions, ring fractures, polygonal fractures, and other locally- to regionally-dispersed landforms [1-2]. The objective of this map project is to clarify the geologic evolution of the southern Utopia Planitia HLB by identifying the geologic, structural, and stratigraphic relationships of surface materials in MTMs 10237, 15237, 20237, 10242, 15242, 20242, 10247, 15247, and 20247. The project was originally awarded in April, 2007 and is in its final year of support. Mapping is on-schedule and formal map submission will occur by December, 2009, with finalization anticipated by April, 2010. Herein, we (1) review specifics regarding mapping data and methods, (2) present nomenclature requests that we feel will assist with unit descriptions, (3) describe Year 2 mapping and science accomplishments, and (4) outline Year 3 technical and managerial approaches for finalizing the geologic map.

Skinner, J. A., Jr.↗