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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

A model for the spatial and energy distributions of energetic neutral atoms produced within the Saturn/Titan plasma system

A model for the production of energetic neutral atoms (ENAs) in the Saturn/Titan system, that takes into account existing data on the spatial distribution of the background neutral density, the energy and spatial distributions of the energetic ions, and the energy dependence of the charge-exchange cross sections, is presented. Hydrogen production via H(+), H is presented in detail. The extended Saturn/Titan system is 'imaged' in energetic neutral H at 66 R(s) and 25-deg latitude. From this vantage point, the energetic H flux is 6 + or - 1 H/sq cm per sec between 10 and 100 keV. Comparing the predicted H spectrum with that observed by Kirsch et al. (1981), the production of neutral O is estimated, and it is concluded that O(+), H charge exchange in the inner magnetosphere is sufficient to account for all the ENA O production.

Hsieh, K. C.↗
NASA NTRS1988

The Karskiy craters are the probable records of catastrophe at the Cretaceous-Tertiary boundary

In order to corroborate the hypothesis of Alvarez and others about the connection of mass mortality and meteorite or cometary impact at the Cretaceous-Tertiary boundary, it is necessary to find a meteorite crater which was formed at the same time. Masaitiss suggested that the Karskiy craters (USSR) are suitable, but previous K/Ar data from other laboratories are very different (from 47 to 82 million years). Impact glasses were gathered from the Karskiy and Ust-Karskiy craters K/Ar age analyses were performed. The glasses cooled very rapidly and had the youngest model ages from 65.8 to 67.6 million years. The slower cooling crypto-crystalline aggregates had more ancient model ages, from 70.5 to 73.9 my as had tagamite because they captured excess argon during crystallization. Least squares analysis showed that with probability of 99 percent the findings on crypto-crystalline aggregates, tagamite and quartz glasses from the Karskiy and Ust-Karskiy craters lie on an isochron which has an age of 65.8 + or - 1.1 million years and a content of excess argon. For the two glasses with identical composition which have different quantities of secondary non-potassium minerals, an independent method determined the content of excess argon. Taking into account these data a more exact slope of the first isochron of 66.4 + or - 1.0 million years was observed and the second glass isochron with age 66.5 + or - 1.1 million years was constructed.

Kolesnikov, E. M.↗
DOE OSTI2025

Advanced Analysis of X-ray Fluorescence Measurements of the Interfacial Density of Eu Ions at Liquid–Liquid Interfaces for Solvent Back-Extraction

X-ray fluorescence near total reflection (XFNTR) is the primary technique used to measure the element-specific interfacial density of ions at liquid−liquid interfaces. Fluorescence from ions in the bulk liquids can complicate the determination of the interfacial density; consequently, measurements have been previously limited to samples without ions in the upper phase and with concentrations on the order of 10 μM or less in the lower phase. We modify the analysis of XFNTR data to account for ions in both bulk phases, then demonstrate its use in the context of rare-earth separations processes. In a model of ion stripping (i.e., back-extraction), dodecane solutions of di(2-ethylhexyl)- phosphoric acid (HDEHP) loaded with Eu(III) at the 1 mM level are placed in contact with either pure water or aqueous solutions of nitric or citric acid at pH 3. XFNTR measurements of equilibrated, quiescent samples reveal that citric acid solutions produce a disproportionately large depletion of ions from the interface compared to that from the bulk organic solution, whereas stripping by pure water or nitric acid solutions is negligible. As a result, this advance in the methodology of XFNTR may have broad applicability to the investigation of metal ions in chemical and biological processes at liquid−liquid interfaces.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Identifying Bayesian optimal experiments for uncertain biochemical pathway models

Abstract Pharmacodynamic (PD) models are mathematical models of cellular reaction networks that include drug mechanisms of action. These models are useful for studying predictive therapeutic outcomes of novel drug therapies in silico. However, PD models are known to possess significant uncertainty with respect to constituent parameter data, leading to uncertainty in the model predictions. Furthermore, experimental data to calibrate these models is often limited or unavailable for novel pathways. In this study, we present a Bayesian optimal experimental design approach for improving PD model prediction accuracy. We then apply our method using simulated experimental data to account for uncertainty in hypothetical laboratory measurements. This leads to a probabilistic prediction of drug performance and a quantitative measure of which prospective laboratory experiment will optimally reduce prediction uncertainty in the PD model. The methods proposed here provide a way forward for uncertainty quantification and guided experimental design for models of novel biological pathways.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Machine learning approaches for influenza A virus risk assessment identifies predictive correlates using ferret model in vivo data

In vivo assessments of influenza A virus (IAV) pathogenicity and transmissibility in ferrets represent a crucial component of many pandemic risk assessment rubrics, but few systematic efforts to identify which data from in vivo experimentation are most useful for predicting pathogenesis and transmission outcomes have been conducted. To this aim, we aggregated viral and molecular data from 125 contemporary IAV (H1, H2, H3, H5, H7, and H9 subtypes) evaluated in ferrets under a consistent protocol. Three overarching predictive classification outcomes (lethality, morbidity, transmissibility) were constructed using machine learning (ML) techniques, employing datasets emphasizing virological and clinical parameters from inoculated ferrets, limited to viral sequence-based information, or combining both data types. Among 11 different ML algorithms tested and assessed, gradient boosting machines and random forest algorithms yielded the highest performance, with models for lethality and transmission consistently better performing than models predicting morbidity. Comparisons of feature selection among models was performed, and highest performing models were validated with results from external risk assessment studies. Our findings show that ML algorithms can be used to summarize complex in vivo experimental work into succinct summaries that inform and enhance risk assessment criteria for pandemic preparedness that take in vivo data into account.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Western Interconnection Baseline Study

The purpose of the baseline study is to evaluate the degree to which current industry planning processes meet the national 2035 decarbonization goals for the Western Interconnection. This analysis serves as a comparative baseline for the scenario analysis conducted in the NTP Study using a Western Interconnection dataset that is readily available to industry. This baseline analysis differs from the production cost modeling analysis and power flow analysis in the main NTP Study report (forthcoming). In particular, the analysis presented in this report reflects a business-as-usual future with an optimistic build out of specific planned transmission projects and foreseeable generation. In contrast, the NTP Study models a future generation and transmission expansion based on optimization from a capacity expansion model. The analysis presented herein also reflects a 2030 timeframe, whereas the main NTP Study production cost modeling analysis and power flow analysis reflect a 2035 time frame. This baseline analysis utilizes industry’s most reliable data to account for future transmission projects across various stages of development, with a particular focus on those in the permitting stage. Additionally, it incorporates projections for changes in generation capacity (both additions and retirements). This baseline analysis outlines a probable trajectory, given current process and practice, for the future of the bulk power system with a horizon extending to 2030.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2026

The ARM Precipitation Best Estimate (PrecipBE) Value-Added Product Report

The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) User Facility’s Precipitation Best-Estimate (PrecipBE) Value-Added Product integrates multiple precipitation datastreams, accounting for data quality and instrument limitations, to deliver comprehensive per-precipitation event properties alongside ancillary ARM data set data. PrecipBE bundles all valid surface rainfall samples into artificial intelligence (AI)-ready tabular and time-series formats, reporting bundle means and uncertainty ranges. This per-event structure provides an insightful and easy-to-use resource for researchers analyzing precipitation characteristics.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Contextualizing Non-Powered Dam Site Selection for Archimedes Screw Turbines: A Methodology for Responsible Archimedes Screw Turbine Conversion at Existing Dams

Non-powered dams represent 97% of dams in the United States and their energy generation potential has not been fully realized. The use of an Archimedes screw turbine to generate power at non-powered dams offers a dual benefit; producing electricity, and acting as downstream fish passage, helping to reconnect previously separated ecosystems. In this study, we assess the technical, environmental, social, and economic feasibility of generating power at non-powered U.S. dam sites using Archimedes screw turbines by integrating mechanical constraints, social impact metrics, proximity to infrastructure, and environmental sensitivity data. Results account for future precipitation predictions and show, between 2024 and 2050, the number of sites where Archimedes screw turbines are viable decreases by one site, but overall generation capacity increases due to increased flow rates across persisting locations. Our analysis identified 82 non-powered dam sites with a mean generation capacity of 49 kW that meet the mechanical requirements for Archimedes screw turbine technology in 2024. Our analysis presents a framework for considering social, environmental, and economic impacts of specific turbine technologies to convert non-powered dams to generate power.

Archimedes screw turbine↗
DOE OSTI2026

The Role of Magnetic Reconnection in Energizing Protons and Heavier Ions at the Heliospheric Current Sheet

During near-Sun crossings of the heliospheric current sheet (HCS), Parker Solar Probe (PSP) observed populations of high-energy protons and heavier ions, indicating possible energization by magnetic reconnection up to 10 s–100 s keV nucleon −1 . Here we study ion acceleration by magnetic reconnection at the HCS. To estimate ion energization, we solve the Parker transport equation coupled to a large-scale 2D MHD reconnection simulation. We find that multiple ion species develop power-law distributions with both spectral index and high-energy cutoff E max consistent with in situ data. By accounting for the injection physics determined by kinetic simulations, we confirm that the charge-to-mass ratio scales as E max ∝ (Q/M) α with α ∼ 0.8–1.1, approximately consistent with PSP measurements in the broader range α ∼ 0.6–1.7. In the limit where ions are injected at the same energy per nucleon, α can be as low as ∼0.3. These findings further support the role of magnetic reconnection in producing high-energy heavy ions at the HCS.

Murtas, Giulia [West Virginia Univ., Morgantown, W↗
NASA NTRS1972

Exhaust flow and propulsion characteristics of a pulsed MPD arc thruster

An experimental investigation of the near-field megawatt, single-shot exhaust is presented for the self-field and auxiliary field cases (0-2 T). Plasma impact pressure and number density are correlated to provide velocity profiles (30,000 to 70,000 m/sec), thrust (10 to 120 N), impulse (3 to 16 N-sec) and mass accounting. The data agree with Hugel's self-field theory for the case where thrust is produced entirely by electromagnetic force. The data show that the thrust monotonically increases with auxiliary field.

Michels, C. J.↗
NASA NTRS1972

Predictions of vehicle encountered electron and proton fluxes for the UK-4 spacecraft

Updated radiation data were obtained for the UK-4 satellite by performing orbital flux integrations for protons and electrons along a specified flight path, using current field and environment models. In this process, adjustments were made to the electron data to account for temporal variations. The final results are presented in tabular and graphical form.

Stassinopoulos, E. G.↗
NASA NTRS1972

Exhaust flow and propulsion characteristics of a pulsed MPD arc thruster.

Experimental investigation of the near-field, megawatt, single-shot exhaust for the self-field and auxiliary field cases (0 to 2 tesla) for a pulsed MPD arc thrustor. Plasma impact pressure and number density are correlated to provide velocity profiles (30,000 to 70,000 m/sec), thrust (10 to 120 N), impulse (3 to 16 N-sec) and mass accounting. The data agree with Hugel's self-field theory for the case where thrust is produced entirely by electromagnetic force. The data show that the thrust monotonically increases with auxiliary field.

Michels, C. J.↗
NASA NTRS1973

The Nimbus 5 data catalog. Volume 1: Data orbits 104 through 693, 19 December 1972 - 31 January 1973

Nimbus 5 was successfully launched from the Western Test Range at Vandenburg AFB, California, into a near circular orbit (1089 km x 1102 km) at 07 hr 56 min 00 sec GMT on 11 December 1972. All experiments and subsystems were successfully turned on. Satellite operations from launch (11 December) through orbit 103 (18 December) consisted of engineering evaluation of all spacecraft systems. As a result of that effort, data reception, accountability, and processing were intermittent during that period. Therefore, this catalog reflects documentation from orbit 104 (19 December 1972) through orbit 693 (31 January 1973). The pitch bias history, surface composition mapping radiometer, and infrared temperature profile radiometer are discussed.

Source record↗
NASA NTRS1974

Coronal density structures in regions of type III activity

The density of the corona over the active regions generating the type III exciters are examined, taking into account radio data together with daily white light coronal observations obtained with a K-coronameter. The intensity profiles and the synoptic maps derived from the K-corona data make it possible to distinguish between dense structures and low intensity regions. A deconvolution technique developed by Leblanc et al. (1970) is applied to calculate the electron density of these structures. For the low intensity regions van de Hulst's (1950) method has been used to compute the electron density of models.

Leblanc, Y.↗
NASA NTRS1974

Scout launch vehicle, phases 4 and 5

The historical data of the Scout launch vehicle program for Phases IV and V (vehicles 138 through 177) is presented for the FY 1966 through FY 1971 time period. Technical data and accounting information are detailed to provide a total picture of the program.

Mccracken, D. C.↗
NASA NTRS1976

Computation of wave drag for transonic flow

The paper develops a method for calculating wave drag for two-dimensional transonic flow, with particular application to the prediction of the drag rise Mach number of a supercritical wing section. The method is based on a transonic similarity model which is defined by a normalized small perturbation equation and represents shock waves by the addition of an artificial viscosity term in the region of supersonic flow to the partial differential equation. The drag formula obtained allows the computer simulation of transonic wind tunnel data taking account of boundary layer and wall effects.

Garabedian, P. R.↗
NASA NTRS1978

Low cycle fatigue in turbines

Behavior of certain components at low-cycle fatigue is a parameter related to the conditions of use of turbines, to the technology of engine production and to the precision of its regulation. The laboratory takes this into account using data from sophisticated tests and rigorous analyses. The production plan includes careful examination of possible causes of premature rupture. This parameter has motivated the metallurgy industry to develop new materials and new technology.

Brun, M.↗