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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Fission matrix-based Monte Carlo criticality analysis of fuel storage pools

Standard Monte Carlo transport procedures experience difficulties in solving criticality problems in fuel storage pools. Because of the strong neutron absorption between fuel assemblies, source convergence can be very slow, leading to incorrect estimates of the eigenvalue and the eigenfunction. This study examines an alternative fission matrix-based Monte Carlo transport method that takes advantage of the geometry of a storage pool to overcome this difficulty. The method uses Monte Carlo transport to build (essentially) a fission matrix, which is then used to calculate the criticality and the critical flux. This method was tested using a test code on a simple problem containing 8 assemblies in a square pool. The standard Monte Carlo method gave the expected eigenfunction in 5 cases out of 10, while the fission matrix method gave the expected eigenfunction in all 10 cases. In addition, the fission matrix method provides an estimate of the error in the eigenvalue and the eigenfunction, and it allows the user to control this error by running an adequate number of cycles. Because of these advantages, the fission matrix method yields a higher confidence in the results than standard Monte Carlo. We also discuss potential improvements of the method, including the potential for variance reduction techniques. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Building a Clean Energy Workforce: Best Practices for State Energy Offices

As federal investments into the clean energy economy are underway, State Energy Offices (SEOs) are engaging in efforts to grow the workforce through the creation and/or funding of workforce initiatives that recruit, train and support pathways into energy efficiency and clean energy jobs. This report provides a summary of clean energy workforce development best practices, supplemented by case studies and lessons learned from several SEOs that showcase these strategies in practice. SEOs can reference this resource as they implement, manage, oversee, and/or evaluate efforts their offices are undertaking through various federally funded programs.

clean energy↗
DOE OSTI2021

Learning from many collider events at once

There have been a number of recent proposals to enhance the performance of machine learning strategies for collider physics by combining many distinct events into a single ensemble feature. To evaluate the efficacy of these proposals, we study the connection between single-event classifiers and multievent classifiers under the assumption that collider events are independent and identically distributed. We show how one can build optimal multievent classifiers from single-event classifiers, and we also show how to construct multievent classifiers such that they produce optimal single-event classifiers. This is illustrated for a Gaussian example as well as for classification tasks relevant for searches and measurements at the Large Hadron Collider. We extend our discussion to regression tasks by showing how they can be phrased in terms of parametrized classifiers. Empirically, we find that training a single-event (per-instance) classifier is more effective than training a multievent (per-ensemble) classifier, as least for the cases we studied, and we relate this fact to properties of the loss function gradient in the two cases. While we did not identify a clear benefit from using multievent classifiers in the collider context, we speculate on the potential value of these methods in cases involving only approximate independence, as relevant for jet substructure studies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1990

A case study of cumulus formation beneath a stratocumulus sheet: Its structure and effect on boundary layer budgets

On several occasions during the FIRE Marine Stratocumulus IFO off the California coast, small cumulus were observed to form during the morning beneath the main stratocumulus (Sc) deck. This occurs in the type of situation described by Turton and Nicholls (1987) in which there is insufficient generation of turbulent kinetic energy (TKE) from the cloudtop or the surface to sustain mixing throughout the layer, and a separation of the surface and cloud layers occurs. The build up of humidity in the surface layer allows cumuli to form, and the more energetic of these may penetrate back into the Sc deck, reconnecting the layers. The results presented were collected by the UKMO C-130 aircraft flying in a region where these small cumulus had grown to the extent that they had penetrated into the main Sc deck above. The structure of these penetrative cumulus are examined and their implications on the layer flux and radiation budget discussed.

Barlow, Roy W.↗
DOE OSTI2023

Build-to-Replace: A New Paradigm for Reducing Advanced Reactor O&M Costs

Nuclear energy is a carbon free source of reliable, resilient, and dispatchable energy that has the potential to feature prominently in a future energy mix. To this end, many new reactor designs are being developed to help reduce cost and improve safety. Operating and maintenance (O&M) costs can make up a significant portion of lifecycle costs. Traditional approaches for nuclear plant design O&M is to perform significant inspections and testing of plant equipment to extend the life of equipment as long as possible. This is contrasted with approaches used in other industries where equipment is replaced when it is no longer functional in lieu of spending time and resources on maintenance. This research investigated the “build-to-replace” approach for new nuclear power plants. A methodology was developed to evaluate the effectiveness of the “build-to-replace” approach. Several scenarios were developed and analyzed using the approach. Modest reductions in O&M costs were obtained in some cases.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2014

Bridging the gap between LCA, LCC and CBA as sustainability assessment tools

Increasing interest in sustainability has led to the development of sustainability assessment tools such as Life Cycle Analysis (LCA), Life Cycle Costing (LCC) and Cost–Benefit Analysis (CBA). Due to methodological disparity of these three tools, conflicting assessment results generate confusion for many policy and business decisions. In order to interpret and integrate assessment results, the paper provides a framework that clarifies the connections and coherence between the included assessment methodologies. Building on this framework, the paper further focuses on key aspects to adapt any of the methodologies to full sustainability assessments. Aspects dealt with in the review are for example the reported metrics, the scope, data requirements, discounting, product- or project-related and approaches with respect to scarcity and labor requirements. In addition to these key aspects, the review shows that important connections exist: (i) the three tools can cope with social inequality, (ii) processes such as valuation techniques for LCC and CBA are common, (iii) Environmental Impact Assessment (EIA) is used as input in both LCA and CBA and (iv) LCA can be used in parallel with LCC. Furthermore, the most integrated sustainability approach combines elements of LCA and LCC to achieve the Life Cycle Sustainability Assessment (LCSA). The key aspects and the connections referred to in the review are illustrated with a case study on the treatment of end-of-life automotive glass. - Highlights: • Proliferation of assessment tools creates ambiguity and confusion. • The developed assessment framework clarifies connections between assessment tools. • Broadening LCA, key aspects are metric and data requirements. • Broadening LCC, key aspects are scope, time frame and discounting. • Broadening CBA, focus point, timespan, references, labor and scarcity are key.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes

A periodically poled lithium niobate (PPLN) crystal with multiple poling periods is used to generate tunable narrow-bandwidth THz pulses for injection seeding a quantum cascade laser (QCL). We demonstrate that longitudinal modes of the quantum cascade laser close to the gain maximum can be selected or suppressed according to the seed spectrum. The QCL emission spectra obtained by electro-optic sampling from the quantum cascade laser, in the most favorable case, shows high selectivity and amplification of the longitudinal modes that overlap the frequency of the narrow-band seed. Proper selection of the narrow-band THz seed from the PPLN crystal discretely tunes the longitudinal mode emission of the quantum cascade laser. Moreover, the THz wave build-up within the laser cavity is studied as a function of the round-trip time. When the seed frequency is outside the maximum of the gain spectrum the laser emission shifts to the preferential longitudinal mode.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2012

Earthquake Damage Assessment Using Objective Image Segmentation: A Case Study of 2010 Haiti Earthquake

In this study, we perform a case study on imagery from the Haiti earthquake that evaluates a novel object-based approach for characterizing earthquake induced surface effects of liquefaction against a traditional pixel based change technique. Our technique, which combines object-oriented change detection with discriminant/categorical functions, shows the power of distinguishing earthquake-induced surface effects from changes in buildings using the object properties concavity, convexity, orthogonality and rectangularity. Our results suggest that object-based analysis holds promise in automatically extracting earthquake-induced damages from high-resolution aerial/satellite imagery.

image segmentation↗
DOE OSTI2020

Energy Master Planning for Resilient Public Communities—Best Practices from U.S. Military Installations

Until recently, most planners at military installations addressed energy systems for new facilities on an individual facility basis without consideration of community-wide goals relevant to energy sources, renewables, storage, or future energy generation needs. Building retrofits of public buildings typically do not address energy needs beyond the minimum code requirements making it difficult, if not impossible, to achieve community-level targets on a building-by-building basis. Planning on the basis of cost and general reliability may also fail to deliver community-level resilience. For example, many building code requirements focus on hardening to specific threats, but in a multi-building community, only a few of these buildings may be mission-critical. Over the past two decades, the frequency and duration of regional power outages and water utility disruptions from weather, man-made events, and aging infrastructure have increased. Major disruptions of electric and thermal energy have degraded critical mission capabilities and caused significant economic impacts. In 2016, the U.S. Department of Defense issued guidance that each Service (Army, Navy, Air Force, Marines) complete comprehensive energy plans for the installations that consumed 75% of total building energy. Guidance was updated in 2017 to include metrics for energy resilience, and in some cases, water. This paper describes how community level quantitative and qualitative resilience analysis and metrics have been incorporated into community energy and water planning best practices for military installations in three geographically diverse locations. It is based on research performed under the International Energy Agency’s “Energy in Buildings and Communities Program Annex 73,” focusing on development of guidelines and tools that support the planning of Net Zero Energy Resilient Public Communities as well as research performed under the Department of Defense Environmental Security Technology Certification Program project EW18-D1- 5281, “Technologies Integration to Achieve Resilient, Low- Energy Military Installations.” The first case study reviews progress made on an energy and water planning study conducted at Fort Bliss, Texas. The second and third describes planning conducted at Fort Bragg, North Carolina and the Joint Region Marianas, Guam, respectively, under the updated guidance from 2017 regarding energy and water resilience. Analysis methods, key metrics, and key infrastructure and operational constraints are described, as well as technical, economic and business concepts used during the planning process.

Urban, Angela B.↗
DOE OSTI2013

DOE Zero Energy Ready Home Case Study: Garbett Homes, Herriman, Utah

As the first net zero-energy production home certified in Utah, this house incorporates two 94% efficient tankless water heaters and two roof-mounted solar panels that preheat the home's water supply. This home won a 2013 Housing Innovation Award in the production builder category.

advanced framing↗
DOE OSTI2016

Simplified Space Conditioning in Low-Load Homes

TO3 2.1.6: Simplified Space Conditioning IBACOS anticipates that houses achieving 50% whole-house source energy savings with respect to the Building America 2010 Benchmark (Hendron and Engebrecht 2010a) will be considered "low load." Low load is defined by IBACOS as a house with a thermal enclosure that yields a maximum space heating and cooling load of less than 10 Btu/h/ft2 of conditioned floor area (31.5 W/m2 [1,200 ft2 /ton]). These small loads can be met by systems other than today's typical ducted forced-air systems. For example, distributed fan coils with minimized ducts, terminal fan coil units, or point source units with buoyant force or ventilation-driven distribution may provide sufficient occupant comfort in a low-load home. These systems, which can have lower total installed costs than traditional ducted forced-air systems (Stecher 2011), allow the thermal enclosure characteristics of low-load houses to provide first-cost savings in addition to operational cost savings. The purpose of this study is to help determine cost-effective solutions for heating and cooling houses that are designed to be energy efficient. This is done by testing the occupant comfort performance of some concepts that may already exist on the market but are not in use by production homebuilders. In some cases, the products are market available, but their use in housing may be a new application. The standards used to assess the performance of the systems in this study are Air Conditioning Contractors of America (ACCA) Manual RS (Rutkowski 1997) and ASHRAE Standard 55-2010 (ASHRAE 2010a).

ACCA Manual RS↗
NASA NTRSDate not supplied

Statistical Engineering

This webinar provides an overview of the International Statistical Engineering Association (ISEA), and it illustrates the practice of statistical engineering at NASA. ISEA was formed to promote the study of how successful data-based problem-solving methods are leveraged to realize innovative opportunities and solve problems sustainably. ISEA is comprised of statisticians, engineers, scientists, and other professionals that exchange ideas and experiences in the development and application of statistical engineering theories. ISEA is building the body of knowledge of the statistical engineering discipline with a particular focus on improving academic preparation for tackling complex problems. Over the past 15 years, the practice of statistical engineering has gained recognition within NASA by spurring innovation and efficiency, and it has demonstrated significant impact. Aerospace research and development benefits from an application-focused statistical engineering perspective to accelerate learning, maximize knowledge, ensure strategic resource investment, and inform data-driven decisions. The second portion of this presentation provides an overview of infusing statistical engineering at NASA through pioneering case studies in aeronautics, space exploration, and atmospheric science.

Peter A Parker↗
DOE OSTI2026

Alchemy: A Model-Based Approach for 2D to 3D Autonomous Nuclear System Design

Engineering design of nuclear power plant (NPP) piping and equipment systems frequently bypasses crucial 2D system planning, instead moving straight to 3D modeling. This often leads to designs that exceed building envelope constraints, forcing expensive and time-consuming redesigns. When 2D modeling is employed, it typically involves labor-intensive manual workflows that convert 2D drawings into 3D models, resulting in inefficiencies and errors across design iterations. These workflows further suffer from poor software interoperability and dependence on proprietary software ecosystems, thereby contributing to schedule delays and cost overruns. This paper presents Alchemy, an autonomous framework that transforms 2D system definitions into Industry Foundation Classes (IFC)-compliant 3D building information models (BIMs) for expediting nuclear facility design at the conceptual preliminary phase. Using a model-based approach, the framework treats the 2D system diagram as the central reference model employed to automatically generate all subsequent outputs, ensuring consistency between the system definition and the resulting physical design. A web-based interface enables engineers to define hierarchical system topologies including associated equipment, geometric properties, and connectivity requirements. A two-phase equipment layout optimization algorithm automatically computes collision-free spatial configurations within predefined building envelopes. An artificial intelligence (AI)-assisted pipe routing module then generates orthogonal, collision-free routing paths, allowing the user to select either an A* search-based method or an Ant Colony Optimization (ACO)-based method. All outputs are authored natively in IFC format, relying on open-source technologies and standardized formats in order to ensure extensibility and eliminate proprietary software dependencies. The proposed framework is validated on two representative pressurized-water reactor (PWR)-based case studies, for which it autonomously generates IFC-compliant 3D models in minutes, drastically reducing workflows that typically require hours of manual effort. The generated model demonstrates topologically correct equipment placement, physically plausible spatial relationships, and collision-free pipe routing consistent with known PWR loop configurations. This work represents a foundational step toward digital engineering for nuclear facility preliminary design, with future ongoing development targeting design code compliance and expanded system complexity.

97 - MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Collaborative Proposal: Improving understanding of the internal structure and dynamics of deep convection using ARM observations and large eddy simulations

Recent observational and large eddy simulation (LES) modeling studies have nearly unanimously supported the view of deep cumulus convection being composed of a series of quasi-spherical bubbles of buoyant air, known as moist thermals. Despite the prevalence of moist thermals in deep convection, a comprehensive theory for the dynamics of these structures is lacking. Most current conceptual models for cumulus convection are based on canonical scaling theories for dry thermals or plumes; however, there is considerable evidence that the behavior of moist thermals differs markedly from these theories. Furthermore, the theoretical basis for most cumulus parameterizations originates from the plume conceptual model, and therefore these parameterizations are inconsistent with the real structure of moist convection. Motivated by the aforementioned knowledge gaps, this “end-to-end” research effort use theory, observations, numerical simulations, and direct improvements to the Zhang-McFarlane (ZM) convection scheme in the global climate Community Atmosphere Model (CAM) to address the following research questions: What key environmental parameters determine whether or not shallow convection will transition into deep convection, in the context of thermal-like updrafts? What factors regulate the size of thermals within cumulus updrafts? How does vertical wind shear influence thermal behavior, and as a consequence, vertical velocity and mass flux profiles and the shallow-to-deep convective transition? What are the critical processes that determine updraft vertical velocities and their connection to the vertical mass flux profile for thermal-like updrafts? Idealized LES modeling will be used in conjunction with theoretical models for the core properties of thermal-like updrafts to better understand key processes that regulate thermal ascent rates and entrainment properties. Thermal-tracking procedures will be used to characterize the behavior of thermals within the LES, and recently developed direct measures of entrainment and detrainment will be used to quantify entrainment/detrainment rates. Building from these results, we will analyze the structure of moist thermals from hemispheric range-height indicator scans taken during the Atmospheric Radiation Measurement Cloud, Aerosol, and Complex Terrain Interactions (CACTI) field campaign, and from “real case” LES of CACTI events. This combined modeling and observational analysis will provide essential validation for the existing body of research on moist thermal dynamics, which is based primarily on modeling studies. With the insight gained from the aforementioned activities, we will modify the Zhang-McFarlane convection scheme to improve its representation of updraft vertical velocity and entrainment rate profiles. These process-level changes will be tested in the Community Atmosphere Model to assess the impact on global climate simulations.

54 ENVIRONMENTAL SCIENCES↗