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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Differing Air Traffic Controller Responses to Similar Trajectory Prediction Errors: An Interrupted Time-Series Analysis of Controller Behavior

A Human-In-The-Loop simulation was conducted in January of 2013 in the Airspace Operations Laboratory at NASAs Ames Research Center. The simulation airspace included two en route sectors feeding the northwest corner of Atlantas Terminal Radar Approach Control. The focus of this paper is on how uncertainties in the studys trajectory predictions impacted the controllers ability to perform their duties. Of particular interest is how the controllers interacted with the delay information displayed in the meter list and data block while managing the arrival flows. Due to wind forecasts with 20-knot over-predictions and 20-knot under-predictions, delay value computations included errors of similar magnitude, albeit in opposite directions. However, when performing their duties in the presence of these errors, did the controllers issue clearances of similar magnitude, albeit in opposite directions?

human-automation interaction↗
NASA NTRS2019

Summary of the High Ice Water Content (HIWC) RADAR Flight Campaigns

NASA and the FAA conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding and develop onboard weather radar processing to detect regions of high ice water content ahead of an aircraft and enable tactical avoidance of the potentially hazardous conditions. Both High Ice Water Content (HIWC) RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory which was equipped with a Honeywell RDR-4000 weather radar and icing instruments to characterize the ice crystals clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results.

Aircraft icing↗
NASA NTRS2019

Radar Detection of High Concentrations of Ice Particles - Methodology and Preliminary Flight Test Results

High Ice Water Content (HIWC) has been identified as a primary causal factor in numerous engine events over the past two decades. Previous attempts to develop a remote detection process utilizing modern commercial radars have failed to produce reliable results. This paper discusses the reasons for previous failures and describes a new technique that has shown very encouraging accuracy and range performance without the need for any hardware modifications to industry’s current radar designs. The performance of this new process was evaluated during the joint NASA/FAA HIWC RADAR II Flight Campaign in August of 2018. Results from that evaluation are discussed, along with the potential for commercial application, and development of minimum operational performance standards for a future commercial radar product.

Harrah, Steven D.↗
NASA NTRS2020

Summary of the High Ice Water Content (HIWC) RADAR Flight Campaigns

NASA and the FAA conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding and develop onboard weather radar processing to detect regions of high ice water content ahead of an aircraft and enable tactical avoidance of the potentially hazardous conditions. Both High Ice Water Content (HIWC) RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory which was equipped with a Honeywell RDR-4000 weather radar and icing instruments to characterize the ice crystal clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results.

Airborne Radar↗
NASA NTRSDate not supplied

High Ice Water Content in Tropical Cyclones During NASA/FAA Radar Flight Campaigns with Comparison to Numerical Simulations

Results from two recent flight campaigns into High Ice Water Content (HIWC) are summarized. HIWC was detected with airborne radar and measured via microphysical probes mounted on NASA’s DC-8. Results from the campaign demonstrate detectability of HIWC using airborne radar. In the cases examined, tropical storms are more proficient at producing large areas of HIWC than hurricanes. Three-dimensional, numerical simulations of tropical cyclones encountered during the campaign are also presented and are compared to measurements in order to understand conditions associated with HIWC. Within Hurricane Lane (2018), the highest ice water contents were found in regenerating thermal plumes located in the eye wall and in feeder bands. Within Tropical Storm Danny (2015), large areas of ice water content greater than 1 g/cu. m were fed by broad-areas of convection occurring downshear from the center of circulation.

Fred H. Proctor↗
NASA NTRS2019

Using Computational Flow Imaging to Optimize Filtered Rayleigh Scattering Measurements of an Isolator Shock Train

Filtered Rayleigh scattering (FRS) is a laser diagnostic where the intensity of elastically scattered light is measured after it passes through a molecular absorption filter. The filter removes background interference that overwhelms the relatively weak scattering from the gas molecules. However, with a filter, the measured light intensity depends on many of the scattering gas properties, including pressure, density, temperature, and velocity. In this work, CFD simulations of an isolator shock train flow field are input into a physics-based model to predict the values of FRS intensity measurements in a proposed experiment. The goal is to evaluate if a simplistic FRS setup (that utilizes one camera, laser, and absorption filter) can be used to accurately quantify number density despite the fact that the scattered light intensity also depends on other gas properties. It is found that the experimental setup can be optimized such that a linear relationship describes the number density with an average prediction error of 2%. The vast majority of the flow exhibits prediction errors of less than 3%, but small regions of the flow reach up to 11% error. A sensitivity analysis shows that the prediction error increases with the central wavelength of the incident laser light and decreases with the angle between the camera and laser propagation directions. The optimal experimental parameters are chosen based on a compromise between the prediction error, spatial resolution, and the amount of unfiltered light. In the future, the proposed FRS setup will be implemented to acquire new and valuable information on an isolator shock train, a flow field that has been traditionally studied using wall static pressure measurements and path-integrated visualization techniques, such as schlieren and shadowgraphy.

Hunt, Robin L.↗
NASA NTRS2020

Quiet Supersonic Flights 2018 (QSF18) Test: Galveston, Texas Risk Reduction for Future Community Testing with a Low-Boom Flight Demonstration Vehicle

The Quiet Supersonic Flights 2018 (QSF18) Program was designed to develop tools and methods for demonstration of overland supersonic flight with an acceptable sonic boom, and collect a large dataset of responses from a representative sample of the population. Phase 1 provided the basis for a low amplitude sonic boom testing in six different climate regions that will enable international regulatory agencies to draft a noise-based standard for certifying civilian supersonic overland flight. Phase 2 successfully executed a large scale test in Galveston, Texas, developed well documented data sets, calculated dose response relationships, yielded lessons, and identified future risk reduction activities.

Galveston↗
NASA NTRS2020

Quiet Supersonic Flights 2018 (QSF18) Test: Galveston, Texas Risk Reduction for Future Community Testing with a Low-Boom Flight Demonstration Vehicle

The Quiet Supersonic Flights 2018 (QSF18) Program was designed to develop tools and methods for demonstration of overland supersonic flight with an acceptable sonic boom, and collect a large dataset of responses from a representative sample of the population. Phase 1 provided the basis for a low amplitude sonic boom testing in six different climate regions that will enable international regulatory agencies to draft a noise-based standard for certifying civilian supersonic overland flight. Phase 2 successfully executed a large scale test in Galveston, Texas, developed well documented data sets, calculated dose response relationships, yielded lessons, and identified future risk reduction activities.

Galveston↗
NASA NTRS2018

TPSAS-NF1676L-32008-DND

Thermosphere climate is controlled in part by cooling to space driven by infrared radiation, primarily from nitric oxide (NO, 5.3μm) and carbon dioxide (CO2, 15μm). The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite has been measuring the vertical distribution of infrared radiation emitted by these species (and others) for nearly 17 years-–more than 6000 days. This data set spans much of Solar Cycle (SC) 23 and all of SC 24 to date. A thermosphere climate index (TCI) has been derived by noting the correlation between 60-day running averages of NO cooling power and three long-term solar and geomagnetic indexes: F10.7 cm solar radio flux, the Ap index of geoeffective solar activity, and the disturbance storm time (Dst) index. A multiple linear regression (MLR) fit of these three parameters to the NO cooling rate over the SABER mission has a better than 0.98 correlation. Applying the MLR constant and coefficients from that fit provides a good estimate of thermospheric cooling back to 1947, the extent of the data available for all three indexes. We examined the percentile distribution of the TCI in quintiles over the five complete solar cycles, and assigned.

Linda Hunt↗
NASA NTRSDate not supplied

TPSAS-NF1676L-30539-DND

The climate of the thermosphere is controlled in part by cooling to space driven by infrared radiation, primarily from nitric oxide (NO, 5.3μm)and carbon dioxide (CO2, 15μm). The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the ThermosphereIonosphere-Mesosphere Energetics and Dynamics (TIMED) satellite measures the vertical distribution of infrared radiation emitted by these species (and others).

Linda Hunt↗
NASA NTRSDate not supplied

TPSAS-NF1676L-17909-DND

Infrared radiative cooling of the thermosphere by carbon dioxide and nitric oxide has been observed continuously since January 2002 by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. SABER has documented dramatic variability in the radiative cooling on timescales ranging from days to longer than the nominal 11-year solar cycle. SABER radiance measurements from emission by CO2 (at 15 um) and NO (at 5.3 um) are used to calculate global daily emitted thermosphere power. This unique dataset shows the direct effects of solar variability on the temperature (via CO2 emission) and composition (from NO emission) for nearly twelve years. The deep solar minimum between solar cycles 23 and 24 is evident in the low values of global mean radiative cooling that occur in the 2008-2009 period. Since then radiative cooling has been observed to increase in response to the transition into solar cycle 24. To more clearly identify extrema in the time series of radiative cooling, NO and CO2 cooling rates are deseasonalized to remove effects of the spacecraft yaw cycle. The deseasonalized data show a clear peak of radiative cooling in NO and CO2 occurring in December 2011. This peak in cooling corresponds to similar peaks in the ultraviolet flux emitted from the Sun measured by the SORCE and SEE instruments. These results show that a maximum in solar activity has clearly occurred. This may be a local maximum in time, depending on the future activity of the Sun in solar cycle 24. Reprocessing of version 2.0 of the SABER dataset is nearly complete and results from this new release will be presented. The SABER thermosphere power dataset will be continuously updated as new data are acquired to monitor the occurrence of solar maximum from the perspective of atmospheric cooling.

L A Hunt↗
NASA NTRSDate not supplied

TPSAS-NF1676L-22888-DND

The climate of the thermosphere is controlled in part by cooling to space driven by infrared radiation from carbon dioxide (CO2, 15μm), nitric oxide (NO, 5.3μm), and atomic oxygen (O, 63μm). The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite has been measuring infrared cooling from CO2 and NO in the thermosphere since January 2002. These data provide integral constraints on the energy budget and climate of the atmosphere above 100 km. Physically, changes in NO emission are due to changes in temperature, atomic oxygen, and the NO density. These physical changes, however, are driven by changes in solar irradiance and changes in geomagnetic conditions.

Linda Hunt↗