Search NASA⌕ Search

SEARCH · Search NASA

Results for “ANC”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

32 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Observation of Stepwise Ultrafast Crystallization Kinetics of Donor–Acceptor Conjugated Polymers and Correlation with Field Effect Mobility

The semicrystalline microstructures of donor-acceptor conjugated polymers strongly impact their optoelectronic properties. The control of the microstructure relies on the understandings of the crystallization processes in these polymers, from packing structures to crystallization kinetics. How fast these conjugated polymer chains crystallize and how their chemical structures and pre-existing microstructure history influence their crystallization have so far remained unclear, due to the fast crystallization rate caused by chain rigid structures and strong interactions. Here, ultrafast scanning calorimetry (FSC) is employed to reveal the crystallization behaviors of high perform- ance diketopyrrolopyrrole (DPP)-based conjugated polymers with scanning rates up to 500 000 K/s. Through elaborately designed nonisothermal and isothermal crystallization studies, we probed the fast crystallization kinetics and extracted the two-step crystallization process of these polymers quantitatively. We found that both the rigidity of the chain backbones and the preinduced crystalline microstructures can influence the crystallization rate over an order of magnitude at the same degree of undercooling. We further demonstrated the manipulated crystallization kinetics in the DPP-based polymer films with different amounts of preinduced crystallites and correlate it to the polymers’ charge transport mobility.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Indirect Measurement of the 23 Na(p, γ) 24 Mg Direct Capture Reaction Rate via ( 3 He,d) Spectroscopy

The cross section of the $^{23}\text{Na}(p,γ)^{24}\text{Mg}$ reaction is dominated by direct capture at low energies relevant for stellar burning. Such cross sections can be constrained using spectroscopic factors($C^2S$) or asymptotic normalization coefficients(ANCs) from transfer reactions. In this work, the $^{23}\text{Na}(^3\text{He},d)^{24}\text{Mg}$ reaction was measured at $E_{lab}=21$ MeV to extract spectroscopic factors for $^{24}\text{Mg}$ states with excitation energies in $E_x=7 - 12$ MeV using the Enge split-pole spectrograph at the Triangle Universities Nuclear Laboratory. A new non-resonant astrophysical S factor and the direct capture reaction rate for the $^{23}\text{Na}(p,γ)$ reaction are calculated and presented based on this measurement. The new rate at $T<0.04$ GK is 43$\%$ smaller than in previous studies. Rigorous treatments of uncertainties are presented using a Bayesian Markov Chain Monte Carlo (MCMC) method. Finally, sources of uncertainties for computing the direct capture cross section are also discussed in detail.

electromagnetic moments↗
DOE OSTI2022

Development of fast-running eighth core nodal solution

A fast-running, eighth-core solution technique has been developed for the quick core calculations in ANC, the Westinghouse core analysis code based on the nodal expansion method, and the BEACON{sup TM} Core Monitoring System (BEACON). This technique, referred to as 'Fast Eighth' (Fast8), enables users to obtain satisfactory macroscopic core calculation results such as reactivity, axial offset and assembly power much more quickly than calculations performed in the standard full-core or quarter-core geometry. Fast8 uses three techniques: folding the radial geometry into eighth-core geometry, reducing the axial geometry into a coarse axial mesh geometry, and smearing the spacer grids into nodes on-the-fly after the first calculation in the standard geometry. These geometry adjustments in Fast8 contribute to the reduction of the number of neutronic and material nodes while maintaining the reaction rates in each node. The axial mesh condition dependency in Fast8 is investigated in a xenon transient calculation in single assembly geometry, and the Fast8 maximum axial mesh size is determined based on these results. Fast8 is then applied to the load swing calculation, and the results are compared with the reference, full-core geometry, solution. The critical boron concentration and axial offset of Fast8 show good agreement with the reference solutions, and that Fast8 is a good technique for obtaining macroscopic core calculation results in significantly shorter time. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

Community-Scale Solar Deployment in the Northwest Arctic

NANA Regional Corporation (NRC, or NANA) was formed as an Alaska Native Corporation (ANC) pursuant to the Alaska Native Claims Settlement Act of 1971. Our lands cover 39,000 square miles of the Northwest Arctic region of Alaska. We partner closely with the Northwest Arctic Borough (NAB) and our 11 remote communities on numerous projects and activities, especially around clean energy initiatives that improve quality of life and help to reduce extremely high energy costs experienced by the communities in our region. Collectively, the regional partnership has developed numerous successful solar, wind, biomass, and energy storage, distribution upgrade, and efficiency projects. To further progress, we created the Northwest Arctic Energy Steering Committee to share and replicate these benefits across the region. NANA’s mission is to provide economic opportunities for our more than 13,500 Iñupiat shareholders and to protect and enhance NANA lands.

14 SOLAR ENERGY↗
DOE OSTI2023

Verification Testing of Body Forces due to a Prescribed Angular Velocity in DYNA3D/Paradyn

This report documents the verification testing and regression testing done on a new feature in DYNA3D/Paradyn, which allows users to prescribe body force loads based upon an angular velocity. This feature is unique in that the direction of the angular velocity vector follows the unit vector formed by two coordinate points associated with two nodes or the average coordinates of two separate small collection of nodes. The angular velocity direction will follow the directional vector defined by these nodes while the angular velocity magnitude is defined by a load curve. A simple single element verification test was performed to determine the correct implementation of this feature, and two separate regression tests were added to the DYNA3D Software Quality Assur ance test suite. The nodal positions, velocities, and accelerations from the solution of the single element verification test compare well to analytically derived values of those nodal quantities. The regression tests serve as good examples of this new feature’s use case and were consequently added to the SQA test suite to ensure that further modifications of the DYNA3D source code do not unintentionally change the generated baseline answers.

42 ENGINEERING↗
DOE OSTI2023

TRACER-VOC: Speciated Volatile Organic Compounds at the Tracking Aerosol Convection Interactions Experiment Field Campaign Report

Formation of secondary organic aerosol (SOA) is responsible for the growth of particles into cloud condensation nuclei (CCN)-relevant sizes and accounts for a substantial fraction of aerosol mass in the troposphere. Despite its wide abundance and importance, capturing SOA in regional and climate models is still challenging due to complex chemical transformations involved in production of SOA. Oxidation products of biogenic hydrocarbons, such as isoprene, monoterpenes, and sesquiterpenes account for the largest fraction of SOA mass over the continents. As such, biogenic SOA is an important source of continental CCN, and has been recently shown to nucleate ice in the deposition mode. To better account for the processes involved in SOA formation in global and regional climate models, we need better measurements of sources and transformations of volatile organic compounds (VOCs), the precursors to SOA formation in the atmosphere. Understanding aerosol-deep convection interactions is an important science driver of the Tracking Aerosol Convection Interactions Experiment (TRACER), requiring a characterization of the critical controls on aerosol properties and processes, and how those properties and processes vary spatially and temporally in the Houston area. In that environment, the atmospheric photo-oxidative chemistry that drives the evolution and transformation of aerosol properties and processes is strongly impacted by the emission of VOCs, which have both anthropogenic (e.g., industrial, urban, transportation, biomass burning) and biogenic (e.g., marine) sources in the region. Understanding (and disentangling) the complex role of VOCs in such a heterogenous region requires high-time-resolution, speciated VOC measurements that are spatially resolved. To meet these measurement requirements, the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility’s time-of-flight proton transfer reaction-mass spectrometer (ToF-PTR-MS) was deployed during the TRACER intensive operational period (IOP) from June to September, 2022 at the ancillary site (ANC), which was sited to provide a characterization of the rural atmospheric environment in contrast to the main site.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Akiachak Energy Efficiency Retrofit Project (Final Technical Report)

The Akiachak Native Community (ANC), a federally recognized Yup'ik Tribe, undertook this energy efficiency initiative to enhance energy performance in key community buildings, including the Tribal IRA Office, Laundry, Police Station, Clinic, and Daycare. Through energy audits and upgrades, the project focused on high-impact improvements like air sealing, LED lighting, and programmable thermostats, primarily in the Tribal Office due to funding constraints. The initiative aims to reduce energy waste, lower heating and electricity costs, and improve facility comfort and longevity. The project aims to generate long-term savings for further improvements by decreasing reliance on imported fuel oil. This initiative aligns with the Tribe's vision for responsible energy use, addressing the challenges of high fuel prices in a remote community, and serves as a model for similar efforts in Akiachak and other Alaska Native villages pursuing energy self-reliance.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Annual Solar Irradiance Anomaly Features Over the USA During 1998-2017 Using NSRDB V3: Preprint

Annual solar irradiance anomalies (or departures from the long-term mean annual value) have a direct effect on various phases of solar energy projects, from prefeasibility to deploy-ment. Anomalies can happen because of normal climate varia-bility or exceptional weather patterns. This study investigates such anomalies for both global horizontal irradiance (GHI) and direct normal irradiance (DNI) using Version 3 of the National Solar Radiation Database (NSRDB V3) and surface irradiance measurements at eight U.S. locations. At each site, the annual anomaly is analyzed here by evaluating the irradi-ance deviation from the long-term average for each specific year during 1998–2017. A positive anomaly indicates that the solar resource was higher than the long-term average during that specific year, and vice versa in the case of a negative anomaly. The results show that, in most cases, the anomaly is within ±5% for GHI and ±10% for DNI, using either ground-based irradiance measurements or modeled data from the NSRDB.

41 EE - Solar Energy Technologies Office (EE-4S)↗
DOE OSTI2026

Test cavity and Iris-to-Coax transition for tuning and high-power verification of SNS DTL iris couplers

The Spallation Neutron Source (SNS) Drift Tube Linac (DTL) employs iris couplers to efficiently deliver RF power into the accelerating structure. To support the development, tuning, and high‑power conditioning of these couplers prior to installation in the actual DTLs, a dedicated test cavity and an iris‑to‑coaxial transition structure have been designed. This work presents the electromagnetic design, simulation, and optimization of the test setup, enabling precise characterization of the iris coupler’s performance. The transition structure allows for tuning of the iris opening dimensions without requiring a waveguide taper or full‑size waveguide transitions, while maintaining impedance matching between the coaxial feed and the iris geometry to minimize reflection and power loss. During low‑power tests, the iris opening di-mensions can be evaluated using the iris‑to‑coax transi-tion attached to the test cavity. For high‑power condi-tioning, full‑size waveguides with ceramic vacuum win-dows are connected to the test cavity to replicate opera-tional conditions. Key design parameters were optimized using computer-aided simulation, and sensitivity studies were conducted to assess the impact of mechanical toler-ances on RF performance. The resulting test platform provides a reliable and efficient means for tuning and validating iris couplers, contributing to improved opera-tional stability in the SNS DTL.

Lee, Sung-Woo [ORNL] (ORCID:000000030915835X)↗
DOE OSTI2023

Plasma proteomics of SARS-CoV-2 infection and severity reveals impact on Alzheimer’s and coronary disease pathways

Identification of proteins dysregulated by COVID-19 infection is critically important for better understanding of its pathophysiology, building prognostic models, and identifying new targets. Plasma proteomic profiling of 4,301 proteins was performed in two independent datasets and tested for the association for three COVID-19 outcomes (infection, ventilation, and death). We identified 1,449 proteins consistently associated in both datasets with any of these three outcomes. We subsequently created highly accurate models that distinctively predict infection, ventilation, and death. These proteins were enriched in specific biological processes including cytokine signaling, Alzheimer’s disease, and coronary artery disease. Mendelian randomization and gene network analyses identified eight causal proteins and 141 highly connected hub proteins including 35 with known drug targets. Our findings provide distinctive prognostic biomarkers for two severe COVID-19 outcomes, reveal their relationship to Alzheimer’s disease and coronary artery disease, and identify potential therapeutic targets for COVID-19 outcomes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Tangent functional connectomes uncover more unique phenotypic traits

Functional connectomes (FCs) containing pairwise estimations of functional couplings between pairs of brain regions are commonly represented by correlation matrices. As symmetric positive definite matrices, FCs can be transformed via tangent space projections, resulting into tangent-FCs. Tangent-FCs have led to more accurate models predicting brain conditions or aging. Motivated by the fact that tangent-FCs seem to be better biomarkers than FCs, we hypothesized that tangent-FCs have also a higher fingerprint. We explored the effects of six factors: fMRI condition, scan length, parcellation granularity, reference matrix, main-diagonal regularization, and distance metric. Our results showed that identification rates are systematically higher when using tangent-FCs across the “fingerprint gradient” (here including test-retest, monozygotic and dizygotic twins). Highest identification rates were achieved when minimally (0.01) regularizing FCs while performing tangent space projection using Riemann reference matrix and using correlation distance to compare the resulting tangent-FCs. Such configuration was validated in a second dataset (resting-state).

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Synthesis of High-Quality Mg-MOF-74 Thin Films via Vapor-Assisted Crystallization

The unique features of metal-organic frameworks (MOFs), such as their large surface areas and diversity of structures, makes them suitable to a broad range of applications. One of the most critical enabling technologies for implementing MOF films is the preparation of dense and continuous films that would maximize the performance of the configurations. While formation of crystalline Mg-MOF-74 thin films presents significant challenges, demonstrating large-scale coatings of the MOF, which exhibits the highest CO2 uptake among MOFs at 1 bar and 25 °C, would be particularly beneficial for CO2- related sensing applications. In this work, we demonstrate for the first time high-quality Mg-MOF-74 films synthesized via a vapor-assisted crystallization (VAC) process. The VAC process described herein produces dense and highly crystalline layers of Mg-MOF-74 with a low coefficient of variation (COV) of film thickness below 7%. We first optimized a precursor solution for the VAC process, and then investigated the effects of synthesis temperature, time and droplet volume on the growth, crystallinity and thickness of Mg-MOF-74 films. The porosity of the film was assessed by measuring the CO2 uptake at room temperature and 1 bar. The obtained Mg-MOF-74 films possess a well-defined microporosity, as deduced from CO2 adsorption studies via quartz crystal microbalance (QCM) and comparison with bulk Mg MOF-74 reference data. Furthermore, CO2 cyclic adsorption-desorption experiments on the Mg-MOF-74

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Charged-Particle Bound States in Periodic Boxes

We consider the binding energy of a two-body system with a repulsive Coulomb interaction in a finite periodic volume. We define the finite-volume Coulomb potential as the usual Coulomb potential, except that the distance is defined the shortest separation between the two bodies in the periodic volume. We investigate this problem in one and three-dimensional periodic boxes and derive the asymptotic behavior of the volume dependence for bound states with zero angular momentum in terms of Whittaker functions. We benchmark our results against numerical calculations and show how the method can be used to extract asymptotic normalization coefficients for charged-particle bound states. Furthermore, the results we derive here have immediate applications for calculations of atomic nuclei in finite periodic volumes for the case where the leading finite-volume correction is associated with two charged clusters.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗