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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Producing Persistent, High-Current, High-Duty-Factor H- Beams for Routine 1 MW Operation of SNS

Since 2009, SNS has been producing neutrons with ion beam powers near 1 MW, which requires the extraction of ~50 mA H- ions from the ion source with a ~5% duty factor. The 50 mA are achieved after an initial dose of ~3 mg of Cs and heating the Cs collar to ~170 C. The 50 mA normally persist for the entire 4-week source service cycles. Fundamental processes are reviewed to elucidate the persistence of the SNS H- beams without a steady feed of Cs and why the Cs collar temperature may have to be kept near 170 C.

Cesium↗
DOE OSTI2016

Column Testing and 1D Reactive Transport Modeling to Evaluate Uranium Plume Persistence Processes

Motivation for Study: Natural flushing of contaminants at various U.S. Department of Energy Office of Legacy Management sites is not proceeding as quickly as predicted (plume persistence) Objectives: Help determine natural flushing rates using column tests. Use 1D reactive transport modeling to better understand the major processes that are creating plume persistence Approach: Core samples from under a former mill tailings area Tailings have been removed. Column leaching using lab-prepared water similar to nearby Gunnison River water. 1D reactive transport modeling to evaluate processes

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

PERSISTENT CURRENT EFFECT IN 15-16 T NB3SN ACCELERATOR DIPOLES AND ITS CORRECTION

Nb3Sn magnets with operating fields of 15-16 T are considered for the LHC Energy Doubler and a future Very High Energy pp Collider. Due to large coil volume, high critical current density and large superconducting (SC) filament size the persistent current effect is very large in Nb3Sn dipoles al low fields. This paper presents the results of analysis of the persistent current effect in the 15 T Nb3Sn dipole demonstrator being developed at FNAL, and describes different possibilities of its correction including passive SC wires, iron shims and coil geometry.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Recombinant cells and organisms having persistent nonstandard amino acid dependence and methods of making them

Recombinant cells and recombinant organisms persistently expressing nonstandard amino acids (NSAAs) are provided. Methods of making recombinant cells and recombinant organisms dependent on persistently expressing NSAAs for survival are also provided. These methods may be used to make safe recombinant cells and recombinant organisms and/or to provide a selective pressure to maintain one or more reassigned codon functions in recombinant cells and recombinant organisms.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Communication device with persistent configuration and verification

The present disclosure pertains to systems and methods for establishing communication with a remote communication device in a software defined network (SDN) during time when an SDN controller is unavailable. In one embodiment, a local communication device may be configured to receive a plurality of data flows from an SDN controller and to store the plurality of data flows in a persistent data memory. The device may generate a unique identifier for the local communication device that is transmitted to a remote communication device. Following a disruption the results in the SDN controller being unavailable, the local communication device may recover into a default configured state based on the plurality of data flows in the persistent data memory. The local communication device may then transmit the unique identifier to the remote communication device after the disruption to begin a process of reestablishing communication with the remote communication device.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Persistent Engagement and the Private Sector

The concepts of “persistent engagement” and “defend forward” signify a shift in how the U.S. employs its military cyber capabilities. These new concepts reorient United States Cyber Command from a reactive, response force to a proactive force with continuous engagement that operates outside U.S. military networks to discover and expose adversary activity as well as execute actions before they harm U.S. national interests. Persistent engagement can form the basis for a whole-of-nation cyber strategy if the private sector is a central player rather than an afterthought.

Monarez, Eduardo D.↗
DOE OSTI2021

Relocation and persistence of named data elements in coordination namespace

An approach is disclosed that relocates a named data element. A request to move a name corresponding to the named data element is received from a first storage area in a Coordination Namespace to a second storage area in the Coordination Namespace. The first storage area has a first level of persistence, and the second storage area has a second level of persistence. The named data element exists in a Coordination Namespace that is allocated in a memory distributed amongst a plurality of nodes that include the local node and one or more remote nodes. The approach then creates a copy of the named data element in the second storage area.

Nair, Ravi↗
NASA NTRSDate not supplied

Effect of Micrometeoroid and Orbital Debris Impact on Modal Response of Persistent Assets

Protecting the infrastructure and payload components of persistent assets (PAs) from damage caused by MicroMeteoroid and/or Orbital Debris (MMOD) impacts is a significant design consideration. The impact resistance to MMOD will need to be provided by the robustness of the structural configuration such that the asset does not suffer loss of function or catastrophic failure. Finite element modelling (FEM) can be used to investigate the effects of MMOD impact on the overall structural behavior of the PA. The models are being used here to investigate the structural response to ‘missing’ truss members, and parametric studies are being performed to identify the worst-case scenario of an impact catastrophically damaging a truss element. These models will be used to determine which truss members are the most critical to the structural performance, and thus, which may require a higher degree of protection or robustness to ensure they can withstand an MMOD impact without causing catastrophic effects on the entire structure. Initial results have been generated indicating a reduction in the global frequency due to missing truss members as a result of MMOD impact.

in-space assembly (ISA)↗
DOE OSTI2017

Persistence of chlorfluazuron in cabbage under different agro-climatic conditions of India and its risk assessment

Here, a multilocational field trial was conducted at 4 locations in India—Rajasthan, Gujarat, Madhya Pradesh, and West Bengal—to determine the persistence in cabbage of chlorfluazuron applied twice at 75 and 150 g active ingredient ha -1 . Cabbage head samples were collected from each replicated plot on 0 (2 h after spraying), 1, 3, 5, 7, 10, and 15 d after final insecticide application, including an untreated control. Chlorfluazuron residue in cabbage and field soil was estimated by high-performance liquid chromatography using a photo diode array detector. The limit of determination and limit of quantification of the method were recorded as 0.05 and 0.10 μg g -1 , respectively. Results revealed that chlorfluazuron dissipated linearly with progress of time, following first-order kinetics. The mean (± standard deviation) half-life value of chlorfluazuron in cabbage was found to be 7.18 ± 0.71 d, considering different locations and treatments. The residue was below the level of quantification in the harvested cabbage and soil samples. Harvesting cabbage in the experimental location, at least on day 7, after 2 applications of chlorfluazuron at the recommended dose, may not pose any ill effect for Indian adults.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Composition and persistence of soil organic matter along eroding and depositional transects in buried vs. modern soil layers: A case of the Brady paleosol at Wauneta, Nebraska

Paleosols form when soils are buried through deposition by aeolian, colluvial, alluvial or other processes. Burial of former topsoil isolates soil organic matter (SOM) from surface conditions, allowing carbon to accumulate and potentially remain stable for millennia. In this study, SOM composition, distribution, and persistence were analyzed in the Brady Soil of Nebraska, USA to compare SOM spatial variability in modern and buried soils, as well as the impact of erosional exposure on SOM stability. The Brady Soil, formed as a surface soil during the Pleistocene-Holocene transition and now a paleosol buried up to 6 m deep (or more) by loess deposition during the Holocene, was sampled along burial (up to 5.8 m depth) and erosional (up to 1.8 m depth) transects to compare SOM dynamics in different geomorphic settings. Fourier Transform Infrared Spectroscopy (FTIR) and Fourier Transform ion cyclotron resonance mass spectrometry (FTICR-MS) were used to analyze SOM composition, while δ 13 C isotope analyses identified SOM sources and radiocarbon values were used to estimate turnover rates. Results confirmed a vegetation shift from C3 to C4 plants after Brady Soil formation, reflecting warming climatic conditions. Increasing SOM age and decreasing δ 13 C and δ 15 N values with depth indicated slowing of decomposition rate in buried soils. Higher pH in the Brady Soil suggested greater base cation content, supporting SOM stabilization through organo-mineral associations and aggregate formation. However, exposure of the Brady Soil due to surface erosion caused faster SOM turnover. This result suggested susceptibility of buried SOM to losses via decomposition upon erosional exposure, possibly accelerated by priming in response to modern SOM inputs. These findings highlight the potential loss of carbon stocks in buried soils under future climate change, as shifts in soil physicochemical properties may destabilize long-preserved SOM.

Environmental sciences↗
DOE OSTI2023

Persistent radicals in irradiated imidazolium ionic liquids probed by EPR spectroscopy

Long-lived radicals were observed in irradiated room temperature ionic liquids (RTILs) composed of the bis(trifluoromethylsulfonyl)imide anion (Tf 2 N - ) with 1-hexyl-3-methylimidazolium (hmim + ) and1-butyl-3-methylimidazolium (bmim+) cations. The EPR signal intensity increases within hours and the spectral pattern changes during the time after irradiation. The kinetics data obtained indicate the existence of at least two distinct radical cations that have different formation and decay rates. We demonstrate that oxygen does not react rapidly with the radical species formed. The bmim + Tf 2 N - was selectively deuterated at various positions which allowed us to suggest possible structures of the stable radicals formed. The first structure is a radical cation containing 2 nitrogens and 6 protons all with ca. 8.2 Gauss hyperfine splittings, and 2 protons with 2.8 Gauss splitting. The structure of the second radical cation is similar, but characterized by an odd number of hydrogens with ca. 8.2 Gauss splitting. Extensive quantum chemistry calculations were performed to attempt to identify the structure of these persistent radicals. The most likely candidates are imidazole radical cations having methyl groups at the nitrogen atoms and substituents in the second position of the imidazole ring.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Can large herbivores enhance ecosystem carbon persistence?

There is growing interest in aligning the wildlife conservation and restoration agenda with climate change mitigation goals. However, the presence of large herbivores tends to reduce aboveground biomass in some open-canopy ecosystems, leading to the possibility that large herbivore restoration may negatively influence ecosystem carbon storage. Furthermore, belowground carbon storage is often ignored in these systems, despite the wide recognition of soils as the largest actively-cycling terrestrial carbon pool. Here, we suggest a shift away from a main focus on vegetation carbon stocks, towards inclusion of whole ecosystem carbon persistence, in future assessments of large herbivore effects on long-term carbon storage. Failure to do so may lead to counterproductive biodiversity and climate impacts of land management actions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Aromatic amino acid metabolism and active transport regulation are implicated in microbial persistence in fractured shale reservoirs

Abstract Hydraulic fracturing has unlocked vast amounts of hydrocarbons trapped within unconventional shale formations. This large-scale engineering approach inadvertently introduces microorganisms into the hydrocarbon reservoir, allowing them to inhabit a new physical space and thrive in the unique biogeochemical resources present in the environment. Advancing our fundamental understanding of microbial growth and physiology in this extreme subsurface environment is critical to improving biofouling control efficacy and maximizing opportunities for beneficial natural resource exploitation. Here, we used metaproteomics and exometabolomics to investigate the biochemical mechanisms underpinning the adaptation of model bacterium Halanaerobium congolense WG10 and mixed microbial consortia enriched from shale-produced fluids to hypersalinity and very low reservoir flow rates (metabolic stress). We also queried the metabolic foundation for biofilm formation in this system, a major impediment to subsurface energy exploration. For the first time, we report that H. congolense WG10 accumulates tyrosine for osmoprotection, an indication of the flexible robustness of stress tolerance that enables its long-term persistence in fractured shale environments. We also identified aromatic amino acid synthesis and cell wall maintenance as critical to biofilm formation. Finally, regulation of transmembrane transport is key to metabolic stress adaptation in shale bacteria under very low well flow rates. These results provide unique insights that enable better management of hydraulically fractured shale systems, for more efficient and sustainable energy extraction.

04 OIL SHALES AND TAR SANDS↗
DOE OSTI2022

HTS Dipole Magnet Model for the Persistent Current Operation

Recent advances in the fabrication of high-temperature superconducting (HTS) coils allow the design of superconducting accelerator magnets that work in a persistent current mode. Many various, rather low-field magnets in particle accelerators operate in the DC current mode. Fermilab designed, fabricated, and tested an HTS dipole magnet model that has 20-mm air gap and a magnetic field up to 0.5 T. The magnet has a primary copper coil that for a short period pumps the energy in the short-circuited secondary HTS coil. Here, the current paper presents the design, fabrication, and testing of this magnet at liquid-nitrogen temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Persistent memory as an effective alternative to random access memory in metagenome assembly

Abstract Background The assembly of metagenomes decomposes members of complex microbe communities and allows the characterization of these genomes without laborious cultivation or single-cell metagenomics. Metagenome assembly is a process that is memory intensive and time consuming. Multi-terabyte sequences can become too large to be assembled on a single computer node, and there is no reliable method to predict the memory requirement due to data-specific memory consumption pattern. Currently, out-of-memory (OOM) is one of the most prevalent factors that causes metagenome assembly failures. Results In this study, we explored the possibility of using Persistent Memory (PMem) as a less expensive substitute for dynamic random access memory (DRAM) to reduce OOM and increase the scalability of metagenome assemblers. We evaluated the execution time and memory usage of three popular metagenome assemblers (MetaSPAdes, MEGAHIT, and MetaHipMer2) in datasets up to one terabase. We found that PMem can enable metagenome assemblers on terabyte-sized datasets by partially or fully substituting DRAM. Depending on the configured DRAM/PMEM ratio, running metagenome assemblies with PMem can achieve a similar speed as DRAM, while in the worst case it showed a roughly two-fold slowdown. In addition, different assemblers displayed distinct memory/speed trade-offs in the same hardware/software environment. Conclusions We demonstrated that PMem is capable of expanding the capacity of DRAM to allow larger metagenome assembly with a potential tradeoff in speed. Because PMem can be used directly without any application-specific code modification, these findings are likely to be generalized to other memory-intensive bioinformatics applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Eastern Seaboard Electric Grid Fragility Maps Supporting Persistent Availability

Persistently available power transmission can be disrupted by weather causing power outages with economic and social consequences. This research investigated the effects on the national power grid from a specific weather event, Hurricane Irene, that caused approximately 5.7 million customer power outages along the Eastern Seaboard in August of 2011. The objective was to describe the geographic differences in the grid s vulnerability to these events. Individual factors, such as wind speed or precipitation, were correlated with the number of outages to determine the greatest mechanism of power failure in hopes of strengthening the future power grid. The resulting fragility maps not only depicted 18 counties that were less robust than the design-standard robustness model and three counties that were more robust, but also drew new damage contours with correlated wind speeds and county features.

Persistent Availability↗
DOE OSTI2026

Analysis of Persistent Soiling Losses: Cooperative Research and Development (Final Report)

The Contractor will analyze data from sensors and equipment provided by Participant in order to provide the basis for understanding of the processes and rates for the formation of 'persistent' soiling (soiling not removed by rain). The resulting, data, technical report, and publications will provide the basis for Participant to improve it's predictive soiling model.

14 SOLAR ENERGY↗
DOE OSTI2021

Persistent Homology Metrics Reveal Quantum Fluctuations and Reactive Atoms in Path Integral Dynamics

Nuclear quantum effects (NQEs) are known to impact a number of features associated with chemical reactivity and physicochemical properties, particularly for light atoms and at low temperatures. In the imaginary time path integral formalism, each atom is mapped onto a “ring polymer” whose spread is related to the quantum mechanical uncertainty in the particle’s position, i.e., its thermal wavelength. A number of metrics have previously been used to investigate and characterize this spread and explain effects arising from quantum delocalization, zero-point energy, and tunneling. Many of these shape metrics consider just the instantaneous structure of the ring polymers. However, given the significant interest in methods such as centroid molecular dynamics and ring polymer molecular dynamics that link the molecular dynamics of these ring polymers to real time properties, there exists significant opportunity to exploit metrics that also allow for the study of the fluctuations of the atom delocalization in time. Here we consider the ring polymer delocalization from the perspective of computational topology, specifically persistent homology, which describes the 3-dimensional arrangement of point cloud data, (i.e. atomic positions). We employ the Betti sequence probability distribution to define the ensemble of shapes adopted by the ring polymer. The Wasserstein distances of Betti sequences adjacent in time are used to characterize fluctuations in shape, where the Fourier transform and associated principal components provides added information differentiating atoms with different NQEs based on their dynamic properties. We demonstrate this methodology on two representative systems, a glassy system consisting of two atom types with dramatically different de Broglie thermal wavelengths, and ab initio molecular dynamics simulation of an aqueous 4 M HCl solution where the H-atoms are differentiated based on their participation in proton transfer reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗