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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 19 records

All sources NASA NTRS DOE OSTI

NASA NTRS2016

Interface Management for a NASA Flight Project Using Model-Based Systems Engineering (MBSE)

The goal of interface management is to identify, define, control, and verify interfaces; ensure compatibility; provide an efficient system development; be on time and within budget; while meeting stakeholder requirements. This paper will present a successful seven-step approach to interface management used in several NASA flight projects. The seven-step approach using Model Based Systems Engineering will be illustrated by interface examples from the Materials International Space Station Experiment-X (MISSE-X) project. The MISSE-X was being developed as an International Space Station (ISS) external platform for space environmental studies, designed to advance the technology readiness of materials and devices critical for future space exploration. Emphasis will be given to best practices covering key areas such as interface definition, writing good interface requirements, utilizing interface working groups, developing and controlling interface documents, handling interface agreements, the use of shadow documents, the importance of interface requirement ownership, interface verification, and product transition.

Vipavetz, Kevin↗

DOE OSTI2022

Mesoscale simulations of pressure-shear loading of granular tungsten carbide

Numerical simulations of pressure-shear loading of a granular material are performed using the shock physics code CTH. A simple mesoscale model for the granular material is used that consists of a randomly packed arrangement of solid circular or spherical grains of uniform size separated by vacuum. The grain material is described by a simple shock equation of state, elastic perfectly plastic strength model, and fracture model with baseline parameters for WC taken from previous mesoscale modeling work. Simulations using the baseline material parameters are performed at the same initial conditions of pressure-shear experiments on dry WC powders. Except for some localized flow regions appearing in simulations with an approximate treatment of sliding interfaces among grains, the samples respond elastically during shear, which is in contrast to experimental observations. By extending the simulations to higher shear wave amplitudes, macroscopic shear failure of the simulated samples is observed with the shear strength increasing with increasing stress confinement. The shear strength is also found to be strongly dependent on the grain interface treatment and on the fracture stress of the grains, though the variation in shear strength due to fracture stress decreases with increasing stress confinement. At partial compactions, the transverse velocity histories show strain-hardening behavior followed by formation of a shear interface that extends through the transverse dimensions of the sample. Near full compaction, no strain hardening is observed and, instead, the sample transitions sharply from an elastic response to formation of an internal shear interface. Agreement with experiment is shown to worsen with increasing confinement stress with simulations overpredicting the shear strengths measured in experiment. The source of the disagreement can be ultimately attributed to the Eulerian nature of the simulations, which do not treat contact and fracture realistically.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Energy Services Interface: Architecture, Requirements, and Agreements

This report continues and extends the development of the Energy Services Interface (ESI) that recently has been led by the U.S. Department of Energy’s Grid Modernization Laboratory Consortium. The ESI is intended to facilitate the coordination of multiple, flexible energy resources that work in tandem to satisfy grid objectives by using performance attributes encoded within an ESI Service Template. The ESI relies on a pair of interfaces, representing the service requestor (the consumer of a service) and a service provider (who manages its resources per the agreed performance attributes) to achieve what is commonly known as a “grid service”. Due to its performance-driven approach, the ESI is hypothesized to be able to satisfy all common grid needs via only six common ESI service types. This report first reviews the status of ESI development, including its fundamental tenets. The report makes three important contributions to ESI development: First, it recognizes the similarity between service level agreements and the contract-like agreements that would be needed between energy service requestors and providers and recommends that ESI service agreements be modeled after the web services agreement specification. Second, whereas prior development efforts had focused on a flat, five-stage lifecycle, this report asserts that the ESI should have three behavioral layers in its architecture—the discovery, agreement, and service layers. Finally, this report offers concrete requirements that should be useful toward the development of the service requestors’ and service providers’ respective communications interfaces.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2018

Nonequilibrium Thermodynamics of Hydrate Growth on a Gas-Liquid Interface

We develop a continuum-scale phase-field model to study gas-liquid-hydrate systems far from thermodynamic equilibrium. We design a Gibbs free energy functional for methane-water mixtures that recovers the isobaric temperature-composition phase diagram under thermodynamic equilibrium conditions. The proposed free energy is incorporated into a phase-field model to study the dynamics of hydrate formation on a gas-liquid interface. We elucidate the role of initial aqueous concentration in determining the direction of hydrate growth at the interface, in agreement with experimental observations. Our model also reveals two stages of hydrate growth at an interface—controlled by a crossover in how methane is supplied from the gas and liquid phases—which could explain the persistence of gas conduits in hydratebearing sediments and other nonequilibrium phenomena commonly observed in natural methane hydrate systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS2012

Principles to Products: Toward Realizing MOS 2.0

This is a report on the Operations Revitalization Initiative, part of the ongoing NASA-funded Advanced Multi-Mission Operations Systems (AMMOS) program. We are implementing products that significantly improve efficiency and effectiveness of Mission Operations Systems (MOS) for deep-space missions. We take a multi-mission approach, in keeping with our organization's charter to "provide multi-mission tools and services that enable mission customers to operate at a lower total cost to NASA." Focusing first on architectural fundamentals of the MOS, we review the effort's progress. In particular, we note the use of stakeholder interactions and consideration of past lessons learned to motivate a set of Principles that guide the evolution of the AMMOS. Thus guided, we have created essential patterns and connections (detailed in companion papers) that are explicitly modeled and support elaboration at multiple levels of detail (system, sub-system, element...) throughout a MOS. This architecture is realized in design and implementation products that provide lifecycle support to a Mission at the system and subsystem level. The products include adaptable multi-mission engineering documentation that describes essentials such as operational concepts and scenarios, requirements, interfaces and agreements, information models, and mission operations processes. Because we have adopted a model-based system engineering method, these documents and their contents are meaningfully related to one another and to the system model. This means they are both more rigorous and reusable (from mission to mission) than standard system engineering products. The use of models also enables detailed, early (e.g., formulation phase) insight into the impact of changes (e.g., to interfaces or to software) that is rigorous and complete, allowing better decisions on cost or technical trades. Finally, our work provides clear and rigorous specification of operations needs to software developers, further enabling significant gains in productivity.

AMMOS↗

DOE OSTI2017

Gallium-Doped Poly-Si:Ga/SiO 2 Passivated Emitters to n-Cz Wafers With iV oc >730 mV

Here, we form gallium-doped poly-Si:Ga/SiO 2 passivated contacts on n-type Czochralski (n-Cz) wafers using ion implantation of Ga and Ga-containing spin-on dopants. After annealing and passivation with Al 2 O 3 , the contacts exhibit i Voc values of >730 mV with corresponding Joe values of <5 fA/cm 2 . These are among the best-reported values for p-type poly-Si/SiO 2 contacts. Secondary ion mass spectroscopic depth profile data show that, in contrast to B, Ga does not pileup at the SiO 2 interface in agreement with its known high diffusivity in SiO 2 . This lack of Ga pileup may imply fewer dopant-related defects in the SiO 2 , compared with B dopants, and account for the excellent passivation.

14 SOLAR ENERGY↗

DOE OSTI2018

A Numerical Study of Two-Phase Flow and Interfacial Mass Transfer in a Wetted Wall Column for Counter-Current Gas Absorption

We present a numerical study to investigate the effects of surface waves of falling films on the mass transfer from flowing gas phase into the liquid film. The model employs the volume of fluid method to explicitly track the gas-liquid phase interface and a one-fluid formulation to model the multiphase flow coupled with mass transfer between the two phases. The surface waves are generated by the time-varying injection rate of the falling film. The effects of surface wave frequencies and amplitudes on the overall mass transfer also are investigated for a counter-current gas-liquid flow of oxygen and water. Because of the solubility difference in the two phases, the model can capture the concentration discontinuity across the liquid-gas interface. Good agreement is obtained between the numerical results and experimental data reported in the literature. By systematically varying the frequencies and amplitudes of flow rate for the falling film, the surface waves generated on the film surface enhance mass transfer in general. Here, the model prediction shows a proportional increase in mass transfer for small frequencies of surface waves, but saturation at higher frequencies.

42 ENGINEERING↗

DOE OSTI2017

Connected Equipment Maturity Model Version 1.0

The Connected Equipment Maturity Model (CEMM) evaluates the high-level functionality and characteristics that enable equipment to provide the four categories of energy-related services through communication with other entities (e.g., equipment, third parties, utilities, and users). The CEMM will help the U.S. Department of Energy, industry, energy efficiency organizations, and research institutions benchmark the current state of connected equipment and identify capabilities that may be attained to reach a more advanced, future state.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2017

Connected Equipment Maturity Model (V.1.0)

42 ENGINEERING↗

DOE OSTI2022

Binary-level Software Compatibility Tool Agreement

Application Binary Interface (ABI) compatibility is essential for system or software updates to ensure that libraries continue to function. Tools that can assess a binary or library ABI can thus be used to make predictions about compatibility, and predict downstream bugs by informing developers and users about issues. In this work, we are interested in describing a set of well-known tools for assessing ABI, and testing them in a controlled set experiments to assess tool agreement. We run 7660 smaller experiments across tools (N=30,640 total results) to evaluate not only predictions, but also each tool’s ability to provide detail about underlying issues. In this paper, along with highlighting the problem of assessing ABI compatibility and critiquing the pros and cons of currently available tools, we provide guidance to developers interested to test ABI based on our empirical results and suggestions for future work.

ABI↗

NASA NTRS2003

A Comprehension Based Analysis of Autoflight System Interfaces

This cooperative agreement supported Dr. Peter Polson's participation in two interrelated research programs. The first was the development of the Situation-Goal-Behavior (SGB) Model that is both a formal description of an avionics system's logic and behavior and a representation of a system that can be understood by avionics designers, pilots, and training developers. The second was the development of a usability inspection method based on an approximate model, RAFIV, of pilot interactions with the Flight Management System (FMS). The main purpose of this report is to integrate the two models and provide a context in order to better characterize the accomplishments of this research program. A major focus of both the previous and this Cooperative Agreement was the development of usability evaluation methods that can be effectively utilized during all phases of the design, development, and certification process of modern avionics systems. The current efforts to validate these methods have involved showing that they generate useful analyses of known operational and training problems with the current generation of avionics systems in modern commercial airliners. This report is organized into seven sections. Following the overview, the second section describes the Goal-Situation-Behavior model and its applications. The next section summarizes the foundations of the RAFIV model and describes the model in some detail. The contents of both these sections are derived from previous reports referenced in footnotes. The fourth section integrates these two models into a complete design evaluation and training development framework. The fifth section contains conclusions and possible future directions for research. References are in Section 6. Section 7 contains the titles and abstracts of the papers paper describing in more detail the results of this research program.

Palmer, Everett↗

DOE OSTI2025

Development of a Transferable Density-Functional Tight-Binding Model for Organic Molecules at the Water/Platinum Interface

A computationally efficient and transferable approach for modeling reactions at metal/water interfaces could significantly accelerate our understanding and ultimately the development of new catalytic transformations, particularly in the context of the emerging field of biomass conversion. Here, we present a parametrization of Pt–X (X = H, O, C) density-functional tight-binding (DFTB) for addressing this need. We first constructed Pt–H, Pt–O, and Pt–C repulsive potential splines. These pairwise parameters were then augmented to include many-body interactions using the Chebyshev Interaction Model for Efficient Simulation (ChIMES). We compare the geometrical and energetic performances of both DFTB and DFTB/ChIMES methods with DFT reference data across a variety of organic molecules at the platinum surface from nanoparticles to single-crystal surfaces. DFTB shows limited transferability between extended crystal surfaces and small nanoparticles. This transferability is significantly improved through the introduction of three-body interactions with Pt in DFTB/ChIMES, which provides consistent results across various systems, with reductions in the RMSD from around 30 kcal/mol in DFTB to around 10 kcal/mol. We demonstrate the stability and reliability of the obtained parameters by performing metadynamic simulations for the adsorption of phenol on Pt(111). We observe that DFTB itself is undersolvating the surface, leading to only one or two chemisorbed water molecules in a c(4 × 6) unit cell. In contrast, DFTB/ChIMES leads to a coverage of about 0.5 ML and successfully captures the chemisorbed mode of phenol at both the solid/liquid and the solid/gas interfaces. Furthermore, in agreement with experimental measurements, the adsorption at the solid/liquid interface is significantly weaker than that at the solid/gas interface. As a result, we highlight that even with DFTB, where we can accumulate dynamics for more than 1 ns for a given system, the simulations are not fully converged.

Adsorption↗

DOE OSTI2022

The effect of metal–insulator interface interactions on electrical transport in granular metals

Here, we present an in-depth study of metal–insulator interfaces within granular metal (GM) films and correlate their interfacial interactions with structural and electrical transport properties. Nominally 100 nm thick GM films of Co and Mo dispersed within yttria-stabilized zirconia (YSZ), with volumetric metal fractions (φ) from 0.2–0.8, were grown by radio frequency co-sputtering from individual metal and YSZ targets. Scanning transmission electron microscopy and DC transport measurements find that the resulting metal islands are well-defined with 1.7–2.6 nm average diameters and percolation thresholds between φ = 0.4–0.5. The room temperature conductivities for the φ = 0.2 samples are several orders of magnitude larger than previously-reported for GMs. X-ray photoemission spectroscopy indicates both oxygen vacancy formation within the YSZ and band-bending at metal–insulator interfaces. The higher-than-predicted conductivity is largely attributed to these interface interactions. In agreement with recent theory, interactions that reduce the change in conductivity across the metal–insulator interface are seen to prevent sharp conductivity drops when the metal concentration decreases below the percolation threshold. These interface interactions help interpret the broad range of conductivities reported throughout the literature and can be used to tune the conductivities of future GMs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1988

Spatially resolved ballistic electron spectroscopy of subsurface interfaces

Buried interfaces have traditionally been inaccessible to direct investigation by surface-sensitive techniques. A unique and novel electronic probe, which is sensitive to subsurface electronic structure, has been utilized to probe Schottky barrier interfaces. The method, ballistic electron emission microscopy (BEEM), is based on scanning tunnelling microscopy (STM) techniques. A theoretical treatment has been developed to describe the ballistic electron spectra obtained by BEEM and this treatment is applied to data obtained on the Au-Si Schottky barrier interface system. Excellent agreement between experiment and theory is obtained. In addition, the treatment predicts nanometer spatial resolution for interface imaging by BEEM.

Bell, L. D.↗

DOE OSTI2019

Theory of the spatial transfer of interface-nucleated changes of dynamical constraints and its consequences in glass-forming films

We formulate a new theory for how caging constraints in glass-forming liquids at a surface or interface are modified and then spatially transferred, in a layer-by-layer bootstrapped manner, into the film interior in the context of the dynamic free energy concept of the Nonlinear Langevin Equation (NLE) theory approach. The dynamic free energy at any mean location (cage center) involves contributions from two adjacent layers where confining forces are not the same. At the most fundamental level of the theory, the caging component of the dynamic free energy varies essentially exponentially with distance from the interface, saturating deep enough into the film with a correlation length of modest size and weak sensitivity to the thermodynamic state. This imparts a roughly exponential spatial variation of all the key features of the dynamic free energy required to compute gradients of dynamical quantities including the localization length, jump distance, cage barrier, collective elastic barrier, and alpha relaxation time. The spatial gradients are entirely of dynamical, not structural or thermodynamic, origin. The theory is implemented for the hard sphere fluid and diverse interfaces which can be a vapor, a rough pinned particle solid, a vibrating (softened) pinned particle solid, or a smooth hard wall. Their basic description at the level of the spatially heterogeneous dynamic free energy is identical, with the crucial difference arising from the first layer where dynamical constraints can be weakened, softened, or hardly changed depending on the specific interface. Numerical calculations establish the spatial dependence and fluid volume fraction sensitivity of the key dynamical property gradients for five different model interfaces. A comparison of the theoretical predictions for the dynamic localization length and glassy modulus with simulations and experiments for systems with a vapor interface reveals good agreement. Finally, the present advance sets the stage for using the Elastically Collective NLE theory to make quantitative predictions for the alpha relaxation time gradient, decoupling phenomena, T g gradient, and many film-averaged properties of both model and experimental (colloids, molecules, and polymers) systems with diverse interfaces and chemical makeup.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Peculiarities of planar shockwave interaction with air–water interface and solid target

We present the results of the research on underwater electrical explosion of planar copper wire arrays, accompanied by the generation of a planar shock, using the synchrotron-based phase-contrast radiography imaging capabilities of the ID19 beamline at the European Synchrotron Radiation Facility. It is shown that the interaction of a strong shock with an air–water interface leads to additional acceleration of the wire expansion due to a rarefaction wave along with the emergence of micro-jets. In the case of a target placed above the array, we observed the formation of a cavity between the array and the target due to the interaction of two rarefaction waves. Furthermore, the results of two-dimensional hydrodynamic simulations of the wire explosion and the interaction of the generated shock with the water–air and water-target interfaces showed good agreement with experimental results.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2024

Milestone 49 Report: Batched Sparse LA Phase 5 Implementation

Batched sparse linear algebra operations in general, and solvers in particular, have become the major algorithmic development activity and foremost performance engineering effort in the numerical software libraries work on modern hardware with accelerators such as GPUs. Many applications, ECP and non-ECP alike, require simultaneous solutions of many small linear systems of equations that are structurally sparse in one form or another. In order to move towards high hardware utilization levels, it is important to provide these applications with appropriate interface designs to be both functionally efficient and performance portable and give full access to the appropriate batched sparse solvers running on modern hardware accelerators prevalent across DOE supercomputing sites since the inception of ECP. To this end, we present here a summary of recent advances on the interface designs in use by HPC software libraries supporting batched sparse linear algebra and the development of sparse batched kernel codes for solvers and preconditioners. We also address the potential interoperability opportunities to keep the corresponding software portable between the major hardware accelerators from AMD, Intel, and NVIDIA, while maintaining the appropriate disclosure levels conforming to the active NDA agreements. The presented interface specifications include a mix of batched band, sparse iterative, and sparse direct solvers with their accompanying functionality that is already required by the application codes or we anticipated to be needed in the near future. This report summarizes progress in Kokkos Kernels and the xSDK libraries MAGMA, Ginkgo, hypre, PETSc, and SuperLU.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS1991

Effect of thermal convection on the shape of a solid-liquid interface

The effect of thermal convection on the shape of solid-liquid interface was investigated in experiments conducted in a transparent Bridgman-type directional solidification furnace. The relationship was numerically modeled using a standard 2D finite-difference approach, with the solid-liquid deformable interface approximated by a blocking-off technique. The directional solidification furnace was used with pure succinonitrile (which is also transparent) contained in a long square ampoule made of borosilicate glass. With the furnace in the vertical configuration, a flat interface was observed, in agreement with the model. On the other hand, a highly distorted interface was obtained in the horizontal configuration; the numerical results showed a strong recirculating cell in front of the interface due to natural thermal convection. The results indicate that thermal convection is responsible for the interface distortion.

Mennetrier, C.↗