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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Developing Accelerated Test Protocols and Tuning Microstructures of the Common Materials to Improve Robustness, Reliability, and Endurance of SOFC Cells

This work is built on our prior work where we found that phase transformation in praseodymium nickelates, e.g. Pr 2 NiO 4 (PNO) and (Pr 1-x Nd x ) 2 NiO 4 (PNNO), can be electrochemically driven, and is substantially faster when compared to thermal annealing studies. The first task aims at an attempt to further accelerate the phase transformation in the oxygen electrode by alternating the current input in the cells, which lead to the development of accelerated test protocols (ATPs). ATPs showed up to 60x faster phase transformation and up to 10x faster performance degradation in (Pr 0.50 Nd 0.50 ) 2 NiO 4 electrodes, when compared to long-term operation under constant current density. Furthermore, the phase stable Nd 2 NiO 4 and (La 0.6 Sr 0.4 )(Co 0.8 Fe 0.2 )O 3 (LSCF6482) electrodes were tested in full cells under ATPs, and showed up to 10x faster performance degradation within 1,100 hours in a comparison with long-term thermal annealing studies and electrochemical operation under constant current density. The second task aims at the quantification of the contributions of cell components to the total impedance of a solid oxide fuel cell (SOFC) using electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT). Specifically, the role of gas composition at both anode and cathode was systematically studied, aiming at deconvoluting, identifying and quantifying the contributions of different electrode processes. This was achieved by first tuning the partial pressure of H 2 at the anode and subsequently varying the partial pressure of O 2 at the cathode. The results suggest that, while DRT offers a viable way of deconvoluting different times distributions, additional attention is needed before assigning a peak to a specific electrode process due to the significant overlap of the contributions from the cathode and the anode. Density function theory studies show that both Pr-vacancies and O-defects play a key role on the activity and stability for nickelates towards oxygen reduction reaction. The resident O-interstitials and oxygen ions in the PrO layer form peroxide (O 2 2- ) nearby Pr vacancies. The O 2 2- limits oxygen-ion transport due to the required additional energy to break its O-O bond. We further calculated the formation and segregation energies for different Ln ions (La, Pr, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) in PNO and CeO 2 (111) surfaces. In addition to Nd, Pm and La are suggested as potential dopants in PNO to enhance it stability without decomposition due to their more negative formation energies, lower diffusion energies, and positive separation energies.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2026

Human Factors and Technologies Design to Improve User Acceptance of Pooled Rideshare for Increasing Transportation System Energy Efficiency

This multi-year project delivered a comprehensive, human-factors-driven framework to understand, model, and improve pooled rideshare (PR) adoption in the United States. Through three large-scale national survey studies involving more than 16,000 participants across multiple cities and demographic groups, the research established one of the most extensive datasets to date on user perceptions, behavioral barriers, and service expectations related to pooled rideshare. These data revealed key human factors barriers of user acceptance of PR and suggested potential actionable experience optimizations that could lead to increased PR usage. This foundational knowledge guided the development of novel human-factors models and behavioral choice models that quantify how psychological, demographic, and trip-level factors influence willingness to pool. Building on these empirical insights, the project developed advanced behavioral modeling tools, including mixed logit and integrated choice and latent variable models, to capture both observable and latent influences on PR adoption. These models significantly improved the ability to predict riders’ acceptance of pooled trips, explaining choice heterogeneity through latent constructs such as safety, service experience, privacy concerns, time sensitivity, and environmental attitudes. Together, these models provide a robust analytical foundation for designing PR systems that more effectively meet user needs. The project translated human-factors insights and behavioral models into actionable technology innovations by extending POLARIS—an agent-based, activity-based travel simulation platform—into a fully functional pooled rideshare simulation environment. New PR modules, acceptance models, and regional scenarios were implemented for Greenville, SC and Austin, TX, enabling high-fidelity validation of algorithmic strategies under realistic demand and traffic conditions. The simulation platform supported the development and evaluation of adaptive discount-based assignment algorithms, enhanced willingness-to-pay formulations, demographic-aware incentive mechanisms, and a proactive joint assignment and repositioning strategy. Simulation results demonstrated substantial gains in pooling uptake, average vehicle occupancy, energy efficiency, and fleet profitability. In Greenville, pooling adoption more than doubled, while reductions in vehicle-miles traveled and energy consumption were significant. In Austin, pooling improvements were achieved with minimal service-quality trade-offs, and profitability increased across all fleet sizes. Through this research, we developed a comprehensive understanding of the human factors barriers that limit user acceptance of pooled rideshare services. These insights enabled the design of human-factors-aware pooled rideshare technologies that more effectively address user concerns and improve adoption rates. By integrating these models into an advanced agent-based simulation framework, we demonstrated that higher adoption of pooled rideshare can lead to measurable improvements in energy efficiency and system performance. Together, these contributions establish a validated pathway from human-centered analysis to technology development and energy-saving outcomes, supporting national goals for more sustainable and efficient mobility systems.

Jia, Yunyi↗
NASA NTRS2000

A Texture-Polarization Method for Estimating Convective/Stratiform Precipitation Area Coverage from Passive Microwave Radiometer Data

Observational and modeling studies have described the relationships between convective/stratiform rain proportion and the vertical distributions of vertical motion, latent heating, and moistening in mesoscale convective systems. Therefore, remote sensing techniques which can quantify the relative areal proportion of convective and stratiform, rainfall can provide useful information regarding the dynamic and thermodynamic processes in these systems. In the present study, two methods for deducing the convective/stratiform areal extent of precipitation from satellite passive microwave radiometer measurements are combined to yield an improved method. If sufficient microwave scattering by ice-phase precipitating hydrometeors is detected, the method relies mainly on the degree of polarization in oblique-view, 85.5 GHz radiances to estimate the area fraction of convective rain within the radiometer footprint. In situations where ice scattering is minimal, the method draws mostly on texture information in radiometer imagery at lower microwave frequencies to estimate the convective area fraction. Based upon observations of ten convective systems over ocean and nine systems over land, instantaneous 0.5 degree resolution estimates of convective area fraction from the Tropical Rainfall Measuring Mission Microwave Imager (TRMM TMI) are compared to nearly coincident estimates from the TRMM Precipitation Radar (TRMM PR). The TMI convective area fraction estimates are slightly low-biased with respect to the PR, with TMI-PR correlations of 0.78 and 0.84 over ocean and land backgrounds, respectively. TMI monthly-average convective area percentages in the tropics and subtropics from February 1998 exhibit the greatest values along the ITCZ and in continental regions of the summer (southern) hemisphere. Although convective area percentages. from the TMI are systematically lower than those from the PR, monthly rain patterns derived from the TMI and PR rain algorithms are very similar. TMI rain depths are significantly higher than corresponding rain depths from the PR in the ITCZ, but are similar in magnitude elsewhere.

Olson, William S.↗
NASA NTRS2002

A Method to Retrieve Rainfall Rate over Land from TRMM Observations

Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) observations over mesoscale convective systems (MCSs) reveal that there are localized maxima in the rain rate with a scale of about 10 to 20 km that represent thunderstorms (Cbs). Some of these Cbs are developing or intense, while others are decaying or weak. These Cbs constitute only about 20 % of the rain area of a given MCS. Outside of Cbs, the average rain rate is much weaker than that within Cbs. From an analysis of the PR data, we find that the spatial distribution of rain and its character, convective or stratiform, is highly inhomogeneous. This complex nature of rain exists on a scale comparable to that of a Cb. The 85 GHz brightness temperature, T85, observations of the TRMM Microwave Imager (TMI) radiometer taken over an MCS reflect closely the PR rain rate pattern over land. Local maxima in rain rate shown by PR are observed as local minima in T85. Where there are no minima in T85, PR observations indicate there is light rain. However, the TMI brightness temperature measurements (Tbs) have poor ability to discriminate convective rain from stratiform rain. For this reason, a TMI rain retrieval procedure that depends primarily on the magnitude of Tbs performs poorly. In order to retrieve rain rate from TMI data on land one has to include the spatial distribution information deduced from the T85 data in the retrieval method. Then, quantitative estimation of rain rate can be accomplished. A TMI rain retrieval method developed along these lines can yield estimates of rain rate and its frequency distribution which agree closely with that given by PR. We find the current TRMM project TMI (Version 5) rain retrieval algorithm on land could be improved with the retrieval scheme developed here. To support the conceptual frame work of the rain retrieval method developed here, a theoretical analysis of the TMI brightness temperatures in convective and stratiform regions is presented.

Prabhakara, C.↗
NASA NTRS2006

TRMM On-Orbit Performance Reassessed After Control Change

The Tropical Rainfall Measuring Mission (TRMM) spacecraft, a joint mission between the U.S. and Japan, launched onboard an H-I1 rocket on November 27, 1997, and transitioned in August, 2001, from an average operating altitude of 350 kilometers to 402.5 kilometers. Due to problems using the Earth Sensor Assembly (ESA) at the higher altitude, TRMM switched to a backup attitude control mode. Prior to the orbit boost TRMM controlled pitch and roll to the local vertical using ESA measurements while using gyro data to propagate yaw attitude between yaw updates from the Sun sensors. After the orbit boost, a Kalman filter used 3-axis gyro data with Sun sensor and magnetometers to estimate onboard attitude. While originally intended to meet a degraded attitude accuracy of 0.7 degrees, the new control mode met the original 0.2 degree attitude accuracy requirement after improving onboard ephemeris prediction and adjusting the magnetometer calibration onboard. Independent roll attitude checks using a science instrument, the Precipitation Radar (PR) which was built in Japan, provided a novel insight into the pointing performance. The PR data helped identify the pointing errors after the orbit boost, track the performance improvements, and show subtle effects from ephemeris errors and gyro bias errors. It also helped identify average bias trends throughout the mission. Roll errors tracked by the PR from sample orbits pre-boost and post-boost are shown in Figure 1. Prior to the orbit boost, the largest attitude errors were due to occasional interference in the ESA. These errors were sometime larger than 0.2 degrees in pitch and roll, but usually less, as estimated from a comprehensive review of the attitude excursions using gyro data. Sudden jumps in the onboard roll show up as spikes in the reported attitude since the control responds within tens of seconds to null the pointing error. The PR estimated roll tracks well with an estimate of the roll history propagated using gyro data. After the orbit boost, the attitude errors shown by the PR roll have a smooth sine-wave type signal because of the way that attitude errors propagate with the use of gyro data. Yaw errors couple at orbit period to roll with 1/4 orbit lag. By tracking the amplitude, phase, and bias of the sinusoidal PR roll error signal, it was shown that the average pitch rotation axis tends to be offset from orbit normal in a direction perpendicular to the Sun direction, as shown in Figure 2 for a 200 day period following the orbit boost. This is a result of the higher accuracy and stability of the Sun sensor measurements relative to the magnetometer measurements used in the Kalman filter. In November, 2001 a magnetometer calibration adjustment was uploaded which improved the pointing performance, keeping the roll and yaw amplitudes within about 0.1 degrees.

Bilanow, Stephen↗
DOE OSTI2020

Materials Data on Pr3AlC by Materials Project

Pr3AlC is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pr is bonded in a linear geometry to four equivalent Al and two equivalent C atoms. All Pr–Al bond lengths are 3.63 Å. Both Pr–C bond lengths are 2.57 Å. Al is bonded to twelve equivalent Pr atoms to form AlPr12 cuboctahedra that share corners with twelve equivalent AlPr12 cuboctahedra, faces with six equivalent AlPr12 cuboctahedra, and faces with eight equivalent CPr6 octahedra. C is bonded to six equivalent Pr atoms to form CPr6 octahedra that share corners with six equivalent CPr6 octahedra and faces with eight equivalent AlPr12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrPPd by Materials Project

PrPdP is hexagonal omega structure-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Pr is bonded to six equivalent Pd and six equivalent P atoms to form a mixture of edge and face-sharing PrP6Pd6 cuboctahedra. All Pr–Pd bond lengths are 3.16 Å. All Pr–P bond lengths are 3.16 Å. Pd is bonded in a 9-coordinate geometry to six equivalent Pr and three equivalent P atoms. All Pd–P bond lengths are 2.46 Å. P is bonded in a 9-coordinate geometry to six equivalent Pr and three equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrAl2Ni3 by Materials Project

PrNi3Al2 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to twelve equivalent Ni and six equivalent Al atoms. All Pr–Ni bond lengths are 3.28 Å. All Pr–Al bond lengths are 3.07 Å. Ni is bonded to four equivalent Pr and four equivalent Al atoms to form a mixture of distorted corner, edge, and face-sharing NiPr4Al4 cuboctahedra. All Ni–Al bond lengths are 2.45 Å. Al is bonded in a 9-coordinate geometry to three equivalent Pr and six equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrAl7Au3 by Materials Project

PrAu3Al7 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to six equivalent Au and twelve equivalent Al atoms. All Pr–Au bond lengths are 3.30 Å. There are six shorter (3.34 Å) and six longer (3.41 Å) Pr–Al bond lengths. Au is bonded in a 9-coordinate geometry to two equivalent Pr and seven Al atoms. There are a spread of Au–Al bond distances ranging from 2.61–2.69 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a distorted trigonal planar geometry to two equivalent Pr and three equivalent Au atoms. In the second Al site, Al is bonded in a trigonal planar geometry to three equivalent Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrMg2Ag by Materials Project

Mg2PrAg is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to four equivalent Pr and four equivalent Ag atoms. All Mg–Pr bond lengths are 3.12 Å. All Mg–Ag bond lengths are 3.12 Å. Pr is bonded in a distorted body-centered cubic geometry to eight equivalent Mg and six equivalent Ag atoms. All Pr–Ag bond lengths are 3.61 Å. Ag is bonded in a distorted body-centered cubic geometry to eight equivalent Mg and six equivalent Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr2CdNi2 by Materials Project

Pr2Ni2Cd crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to six equivalent Ni and four equivalent Cd atoms. There are two shorter (2.93 Å) and four longer (2.98 Å) Pr–Ni bond lengths. All Pr–Cd bond lengths are 3.39 Å. Ni is bonded in a 9-coordinate geometry to six equivalent Pr, one Ni, and two equivalent Cd atoms. The Ni–Ni bond length is 2.48 Å. Both Ni–Cd bond lengths are 3.03 Å. Cd is bonded to eight equivalent Pr and four equivalent Ni atoms to form a mixture of face and corner-sharing CdPr8Ni4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrB4 by Materials Project

PrB4 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Pr is bonded in a 8-coordinate geometry to eighteen B atoms. There are a spread of Pr–B bond distances ranging from 2.79–3.14 Å. There are three inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to four equivalent Pr and five B atoms. There is one shorter (1.70 Å) and four longer (1.78 Å) B–B bond length. In the second B site, B is bonded in a 9-coordinate geometry to four equivalent Pr and five B atoms. There is one shorter (1.77 Å) and two longer (1.83 Å) B–B bond length. In the third B site, B is bonded in a distorted trigonal planar geometry to six equivalent Pr and three B atoms. The B–B bond length is 1.81 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiPrSn by Materials Project

LiPrSn is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Li is bonded in a body-centered cubic geometry to four equivalent Pr and four equivalent Sn atoms. All Li–Pr bond lengths are 2.94 Å. All Li–Sn bond lengths are 2.94 Å. Pr is bonded in a 10-coordinate geometry to four equivalent Li and six equivalent Sn atoms. All Pr–Sn bond lengths are 3.39 Å. Sn is bonded to four equivalent Li and six equivalent Pr atoms to form a mixture of distorted corner and face-sharing SnLi4Pr6 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr2CdPd2 by Materials Project

Pr2Pd2Cd crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to six equivalent Pd and four equivalent Cd atoms. There are two shorter (2.97 Å) and four longer (3.12 Å) Pr–Pd bond lengths. All Pr–Cd bond lengths are 3.52 Å. Pd is bonded in a 9-coordinate geometry to six equivalent Pr, one Pd, and two equivalent Cd atoms. The Pd–Pd bond length is 2.83 Å. Both Pd–Cd bond lengths are 3.10 Å. Cd is bonded to eight equivalent Pr and four equivalent Pd atoms to form a mixture of face and corner-sharing CdPr8Pd4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrMg2Cu9 by Materials Project

Mg2PrCu9 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mg is bonded in a 12-coordinate geometry to twelve Cu atoms. There are a spread of Mg–Cu bond distances ranging from 2.87–2.97 Å. Pr is bonded in a distorted hexagonal planar geometry to eighteen Cu atoms. There are six shorter (2.92 Å) and twelve longer (3.27 Å) Pr–Cu bond lengths. There are four inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to three equivalent Pr and nine Cu atoms. There are six shorter (2.53 Å) and three longer (2.92 Å) Cu–Cu bond lengths. In the second Cu site, Cu is bonded to three equivalent Mg, two equivalent Pr, and seven Cu atoms to form a mixture of face, edge, and corner-sharing CuPr2Mg3Cu7 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.46–2.55 Å. In the third Cu site, Cu is bonded in a 12-coordinate geometry to three equivalent Pr and nine Cu atoms. In the fourth Cu site, Cu is bonded to six equivalent Mg and six equivalent Cu atoms to form CuMg6Cu6 cuboctahedra that share corners with twelve equivalent CuPr2Mg3Cu7 cuboctahedra, edges with six equivalent CuMg6Cu6 cuboctahedra, and faces with eighteen equivalent CuPr2Mg3Cu7 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrMgNi4 by Materials Project

PrMgNi4 is Hexagonal Laves-derived structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded in a 12-coordinate geometry to four equivalent Pr and twelve equivalent Ni atoms. All Mg–Pr bond lengths are 3.10 Å. All Mg–Ni bond lengths are 2.96 Å. Pr is bonded in a 12-coordinate geometry to four equivalent Mg and twelve equivalent Ni atoms. All Pr–Ni bond lengths are 2.97 Å. Ni is bonded to three equivalent Mg, three equivalent Pr, and six equivalent Ni atoms to form a mixture of face, edge, and corner-sharing NiPr3Mg3Ni6 cuboctahedra. There are three shorter (2.49 Å) and three longer (2.56 Å) Ni–Ni bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrAgPb by Materials Project

PrAgPb crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to six equivalent Ag and six equivalent Pb atoms. There are three shorter (3.21 Å) and three longer (3.72 Å) Pr–Ag bond lengths. There are three shorter (3.32 Å) and three longer (3.58 Å) Pr–Pb bond lengths. Ag is bonded in a 10-coordinate geometry to six equivalent Pr and four equivalent Pb atoms. There are three shorter (2.92 Å) and one longer (3.21 Å) Ag–Pb bond lengths. Pb is bonded in a 10-coordinate geometry to six equivalent Pr and four equivalent Ag atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr2InGe2 by Materials Project

Pr2Ge2In crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to four equivalent In and six equivalent Ge atoms. All Pr–In bond lengths are 3.56 Å. There are two shorter (3.09 Å) and four longer (3.20 Å) Pr–Ge bond lengths. In is bonded to eight equivalent Pr and four equivalent Ge atoms to form a mixture of corner and face-sharing InPr8Ge4 cuboctahedra. All In–Ge bond lengths are 3.04 Å. Ge is bonded in a 9-coordinate geometry to six equivalent Pr, two equivalent In, and one Ge atom. The Ge–Ge bond length is 2.55 Å.

36 MATERIALS SCIENCE↗