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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Housing-Performance Atlas of Baltimore Row Homes: Archetype-Based Multi-Hazard Baseline of Energy, Heat, Survivability, and Durability

Baltimore’s historic row-home neighborhoods face escalating risks to energy, heat, and durability under intensifying climate stress. This study develops a Housing-Performance Atlas that quantifies multi-hazard performance for eight representative archetypes using DesignBuilder/EnergyPlus Version 7.3.1.003, under Baltimore TMY3 boundary conditions. Performance is evaluated across the following four adaptation domains: energy use intensity, passive survivability during 72 h outage events, roof overheating exposure (>150 °F exceedance hours), and material service life derived from ISO 15686 and synthesized into Lean and Full Deficit Indices for comparative resilience ranking. Results show that EUI ranged from 46.7 to 67.6 kBtu ft −2 ·yr −1 , survivability from 0 to 23 h, and roof temperatures exceeded 150 °F for 150–210 h, shortening roof service life by up to 10 years. Composite Lean and Full Deficit Indices ranged 7.8–92.4, ranking Model 5 (end-unit, flat roof, two-story with basement) as the most resilient configuration and Model 8 (end-unit, pitched roof, three-story above-grade) as the least resilient due to compounded overheating and energy losses. Heat-related domains accounted for nearly 70% of overall resilience deficits, confirming thermal safety and roof reflectivity as retrofit priorities. The Housing-Performance Atlas establishes a reproducible diagnostic framework linking simulation, service life, and resilience metrics to guide cost-effective, climate-responsive retrofits in Baltimore’s aging urban housing stock.

Housing-Performance atlas↗
DOE OSTI2024

Leveraging Optimal Sparse Sensor Placement to Aggregate a Network of Digital Twins for Nuclear Subsystems

Nuclear power plants (NPPs) require continuous monitoring of various systems, structures, and components to ensure safe and efficient operations. The critical safety testing of new fuel compositions and the analysis of the effects of power transients on core temperatures can be achieved through modeling and simulations. They capture the dynamics of the physical phenomenon associated with failure modes and facilitate the creation of digital twins (DTs). Accurate reconstruction of fields of interest (e.g., temperature, pressure, velocity) from sensor measurements is crucial to establish a two-way communication between physical experiments and models. Sensor placement is highly constrained in most nuclear subsystems due to challenging operating conditions and inherent spatial limitations. This study develops optimized data-driven sensor placements for full-field reconstruction within reactor and steam generator subsystems of NPPs. Optimized constrained sensors reconstruct field of interest within a tri-structural isotropic (TRISO) fuel irradiation experiment, a lumped parameter model of a nuclear fuel test rod and a steam generator. The optimization procedure leverages reduced-order models of flow physics to provide a highly accurate full-field reconstruction of responses of interest, noise-induced uncertainty quantification and physically feasible sensor locations. Accurate sensor-based reconstructions establish a foundation for the digital twinning of subsystems, culminating in a comprehensive DT aggregate of an NPP.

42 ENGINEERING↗
DOE OSTI2024

A system identification approach for non-intrusive reduced order modeling of radiation-induced photocurrents

In this study, development of compact photocurrent models is currently dominated by analytical techniques that rely on physical assumptions to render the governing equations solvable in a closed form. Violation of these assumptions can reduce the accuracy of the models and/or limit their scope. In this paper we show that system identification of nonlinear state-space systems can serve as an alternative numerical basis for non-intrusive reduced order modeling of photocurrent effects. To that end we develop a compact gray box photocurrent model (GBPM) by using a state-space representation with a low-dimensional latent state equation that mimics a mathematical model for the response of an idealized class of devices to ionizing radiation. In so doing we obtain a model that learns the dynamics of a quantity of interest directly from its measurements without requiring snapshots of the internal device state or its discretized model, and can be inferred from very small data sets. To demonstrate the approach we train the GBPM using a small experimental data set for a Z5236 Zener diode and a small synthetic data set obtained by simulating a synthetic pn-junction device. We then compare the GBPMs with black box models trained on the same data and show that performance of the latter is limited by the size of the data set, while the former are able to achieve excellent performance in both the reproductive and the predictive regimes.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Fuel Consumption Sensitivity of Conventional and Hybrid Electric Light-Duty Gasoline Vehicles to Driving Style

Aggressive driving is a very important topic for many reasons, one of which is higher energy used per unit distance traveled, potentially accompanied by an elevated production of greenhouse gases and other pollutants. Examining a large data set of self-reported fuel economy (FE) values revealed that the dispersion of FE values is quite large and is larger for hybrid electric vehicles (HEVs) than for conventional gasoline vehicles. This occurred despite the fact that the city and highway FE ratings for HEVs are generally much closer in value than for conventional gasoline vehicles. A study was undertaken to better understand this and better quantify the effects of aggressive driving, including reviewing past aggressive driving studies, developing and exercising a new vehicle energy model, and conducting a related experimental investigation. The vehicle energy model focused on the limitations of regenerative braking in combination with varying levels of driving-style aggressiveness to show that this could account for greater FE variation in an HEV compared to a similar conventional vehicle. A closely matched pair of gasoline-fueled sedans, one an HEV and the other having a conventional powertrain, was chosen for both modeling and chassis dynamometer experimental comparisons. Results indicate that the regenerative braking limitations could be a main contributor to the greater HEV FE variation under the range of drive cycles considered. Finally, the complete body of results gives insight into the range of fuel use penalties that results from aggressive driving and why the variation can be larger on a percent basis for an HEV compared to a similar conventional vehicle, while the absolute fuel use penalty for aggressive driving is generally larger for conventional vehicles than HEVs.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2021

Fast and accurate learned multiresolution dynamical downscaling for precipitation

Abstract. This study develops a neural-network-based approach for emulating high-resolution modeled precipitation data with comparable statistical properties but at greatly reduced computational cost. The key idea is to use combination of low- and high-resolution simulations (that differ not only in spatial resolution but also in geospatial patterns) to train a neural network to map from the former to the latter. Specifically, we define two types of CNNs, one that stacks variables directly and one that encodes each variable before stacking, and we train each CNN type both with a conventional loss function, such as mean square error (MSE), and with a conditional generative adversarial network (CGAN), for a total of four CNN variants. We compare the four new CNN-derived high-resolution precipitation results with precipitation generated from original high-resolution simulations, a bilinear interpolater and the state-of-the-art CNN-based super-resolution (SR) technique. Results show that the SR technique produces results similar to those of the bilinear interpolator with smoother spatial and temporal distributions and smaller data variabilities and extremes than the original high-resolution simulations. While the new CNNs trained by MSE generate better results over some regions than the interpolator and SR technique do, their predictions are still biased from the original high-resolution simulations. The CNNs trained by CGAN generate more realistic and physically reasonable results, better capturing not only data variability in time and space but also extremes such as intense and long-lasting storms. The new proposed CNN-based downscaling approach can downscale precipitation from 50 to 12 km in 14 min for 30 years once the network is trained (training takes 4 h using 1 GPU), while the conventional dynamical downscaling would take 1 month using 600 CPU cores to generate simulations at the resolution of 12 km over the contiguous United States.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

DSGAN

This study develops a neural network-based approach for emulating high-resolution modeled precipitation data with comparable statistical properties but at greatly reduced computational cost. The key idea is to use combination of low-and high- resolution simulations to train a neural network to map from the former to the latter. Specifically, we define two types of CNNs, one that stacks variables directly and one that encodes each variable before stacking, and we train each CNN type both with a conventional loss function, such as mean square error (MSE), and with a conditional generative adversarial network (CGAN), for a total of four CNN variants. We compare the four new CNN-derived high-resolution precipitation results with precipitation generated from original high resolution simulations, a bilinear interpolater and the state-of-the-art CNN-based super-resolution (SR) technique. Results show that the SR technique produces results similar to those of the bilinear interpolator with smoother spatial and temporal distributions and smaller data variabilities and extremes than the original high resolution simulations. While the new CNNs trained by MSE generate better results over some regions than the interpolator and SR technique do, their predictions are still not as close as the original high resolution simulations. The CNNs trained by CGAN generate more realistic and physically reasonable results, better capturing not only data variability in time and space but also extremes such as intense and long-lasting storms. The new proposed CNN-based downscaling approach can downscale precipitation from 50~km to 12~km in 14~min for 30~years

LIU, ZHENGCHUN↗
DOE OSTI2025

Virtual Refrigerant Charge Sensing Method for Next-Generation Refrigerant in Residential Heat Pumps

The charge level of refrigerant in heat pump systems significantly affects their operational performance. Virtual refrigerant charge (VRC) sensing technology has been well-established for traditional refrigerants (HFCs and HCFCs) for its low cost compared to physical sensors. However, other than traditional refrigerants, HFOs are increasingly used in next-generation heat pumps; whether these conventional VRC sensing methods remain applicable for heat pump systems utilizing next-generation refrigerants requires further investigation. To address these issues, this study develops a low-cost VRC sensing method for next-generation refrigerant heat pumps used in residential buildings. The developed algorithm is evaluated by using simulation models to evaluate the accuracy, considering an R454B heat pump with a nominal heating capacity of 51K Btu/hr (14.95 kW) as an example, and compared with those of the two reference VRC sensing algorithms. Though the developed VRC sensing algorithm and the two reference methods can accurately predict the charge level for the R454B heat pump system (with mean absolute percentage error for various cooling and heating conditions less than 7%), the developed VRC sensing algorithm uses fewer sensors and improves the overall accuracy for heating conditions by 7.1%, and the accuracy for undercharge cooling conditions 14.2%, compared with a mainstream algorithm. This technology will complement physical leakage detectors, and promote the adoption of next-generation heat pump systems, along with reducing wasted energy and maintenance costs.

Liang, Chenjiyu↗
NASA NTRS1964

High Energy Propellants: A Continuing Bibliography

Through its Continuing Bibliography Program, NASA will prepare and distribute a series of bibliographies devoted to specific subjects in the aerospace field. The subjects have been selected because of their significant relationship to current developments in the space program, and because of a clearly established interest in them on the part of aerospace specialists. In order to assure that future information will become available in an orderly manner, each Continuing Bibliography will be updated periodically in the form of supplements which can be appended to the original edition. High Energy Propellants , NASA-SP-7002, is the first publication to appear under this program. It presents a selection of annotated references to unclassified reports and journal articles announced in Technical Publications Announcements (TPA) , Scientific and Technical Aerospace Reports (STAR) , and International Aerospace Abstracts (IAA) . Prime emphasis is given to those references which are concerned with research and development studies on solid, liquid, and hybrid propellants and oxidizers, but the bibliography also provides extensive coverage of such related topics as propellant handling and storage, combustion characteristics, toxicity, and hazards and safety measures. Each entry in the bibliography consists of a citation and an abstract. The listing of entries is arranged in two major groups: all report literature references are contained in the first group and are subdivided according to their date of announcement in TPA and STAR ; the second group includes all published literature references subdivided according to their date of announcement in IAA . All reports and articles cited were introduced into the NASA Information System during the period January 1962-March, 1964.

Bibliography↗
NASA NTRS1972

Techniques for improving reliability of computers

Modular design techniques improve methods of error detection, diagnosis, and recovery. Theoretical computer (MARCS (Modular Architecture for Reliable Computer Systems)) study deals with postulated and modeled technology indigenous to 1975-1980. Study developments are discussed.

Cater, W. C.↗
NASA NTRS1972

NASA-EPA automotive thermal reactor technology program

The status of the NASA-EPA automotive thermal reactor technology program is summarized. This program is concerned primarily with materials evaluation, reactor design, and combustion kinetics. From engine dynamometer tests of candidate metals and coatings, two ferritic iron alloys (GE 1541 and Armco 18-SR) and a nickel-base alloy (Inconel 601) offer promise for reactor use. None of the coatings evaluated warrant further consideration. Development studies on a ceramic thermal reactor appear promising based on initial vehicle road tests. A chemical kinetic study has shown that gas temperatures of at least 900 K to 1000 K are required for the effective cleanup of carbon monoxide and hydrocarbons, but that higher temperatures require shorter combustion times and thus may permit smaller reactors.

Blankenship, C. P.↗
NASA NTRS1970

Study of optimum propellant production facilities for launch of space shuttle vehicles

An integrated propellant manufacturing plant and distribution system located at Kennedy Space Center is studied. The initial planned propellant and pressurant production amounted to 160 tons/day (TPD) LH2, 10 TPD GH2, 800 TPD LO2, 400 TPD LN2, and 120 TPD GN2. This was based on a shuttle launch frequency of 104 per year. During the study, developments occurred which may lower cryogen requirements. A variety of plant and processing equipment sizes and costs are considered for redundancy and supply level considerations. Steam reforming is compared to partial oxidation as a means of generating hydrogen. Electric motors, steam turbines, and gas turbines are evaluated for driving compression equipment. Various sites on and off Government property are considered to determine tradeoffs between costs and problems directly associated with the site, product delivery and storage costs, raw material costs, and energy costs. Coproduction of other products such as deuterium, methanol, and ammonia are considered. Legal questions are discussed concerning a private company's liabilities and its rights to market commercial products under Government tax and cost shelters.

Laclair, L. M.↗
NASA NTRS1972

Summary of 1971 water remote sensing investigations

The Earth Resources Laboratory sea remote sensing program has concentrated on project planning, data acquisition procedures, and data preparation techniques to establish a firm procedural basis for the program. Most of these procedural elements were established and proven during the three missions conducted in 1971. It is anticipated that the program in 1972 will see the analysis completed on the Mississippi Sound series and the first series of Eastern Gulf experiments allowing increased emphasis to be given to more intensive technique development studies, the interrelationship of parameters for the measurement and prediction of water circulation, and the demonstration of the application of these techniques.

Tilton, E. L., III↗
NASA NTRS1972

Advanced design concepts for shuttle airframe structure

The development of weight-saving advanced design concepts for shuttle airframe structure is presented. Design concepts under investigation employ selective composite reinforcement and/or efficient geometric arrangements. An effort to develop metallic panel designs which exploit the relaxation of smooth external-surface requirements for skin structure is reviewed. Available highlights from research and development studies which investigate the application of composite reinforcement to the design of two types of fuselage panels, a shear web, a large fuselage frame, and a landing-gear-door assembly are presented. Preliminary results from these studies suggest weight savings of 25 percent can be obtained.

Card, M. F.↗
NASA NTRS1973

Space science plans for the shuttle era.

Three separate and distinct modes of using the space shuttle system have been identified. These modes include the boost of a spacecraft plus one or more propulsion stages into earth orbit or parking orbit, the establishment and maintenance of automated observatories in space, and the support of exploratory research and instrument development. Studies show that approximately 60% of all planned NASA missions require a shuttle third stage. Illustrations are presented to show how the largest spacecraft, Viking, and its propulsion system, Centaur, and a communications satellite, with an Agena stage to place it into a geostationary orbit, would fit into the shuttle. Results of the NASA Shuttle Sortie Workshop studies are discussed together with prospects of European cooperation in future workshop experiments.

Naugle, J. E.↗
NASA NTRS1975

In-orbit servicing

A concept called the low-cost modular spacecraft, in which the subsystems would be contained in replaceable modules and which would be capable of various applications, is under engineering development. Studies have shown that servicing of such a spacecraft on orbit by the Space Shuttle over an extended lifetime is more economical than three other alternatives: launching replacement satellites on conventional boosters as existing satellites fail, launching replacements by Shuttle, or launching replacement satellites and retrieving malfunctioning satellites by Shuttle. For on-orbit servicing, the Shuttle would use its Remote Manipulator system (RMS) to bring the malfunctioning satellite into its cargo bay. The Flight Support System (FSS) on the Orbiter used for servicing the satellite would include an appendage storage frame, a retention cradle, a positioning platform, a Module Exchange Mechanism (MEM), and a storage magazine. Ground simulations are under way with the Orbiter mockup.

Cepollina, F. J.↗
NASA NTRS1975

Investigation of time-sharing of rebalance electronics for sensors in strapdown navigation platforms

This article reports the results of an investigation on time-sharing of a rebalance electronics among several sensors used in a strapdown navigation platform. Various concepts are given. The merits and demerits of the time-sharing for a typical situation are discussed in detail. A possible hardware realization is proposed. In addition, this study develops a general approach, applicable to other systems, for evaluating the use of time-sharing concept.

Coffman, D. E.↗
NASA NTRS1977

A field study of wind over a simulated block building

A full-scale field study of the wind over a simulated two-dimensional building is reported. The study develops an experiment to investigate the structure and magnitude of the wind fields. A description of the experimental arrangement, the type and expected accuracy of the data, and the range of the data are given. The data are expected to provide a fundamental understanding of mean wind and turbulence structure of the wind field around the bluff body. Preliminary analysis of the data demonstrates the reliability and completeness of the data in this regard.

Frost, W.↗