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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Inelastic Deformation of Metal Matrix Composites: Plasticity and Damage Mechanisms - Part 1

The deformation mechanisms of a Ti 15-3/SCS6 (SiC fiber) metal matrix composite (MMC) were investigated using a combination of mechanical measurements and microstructural analysis. The objectives were to evaluate the contributions of plasticity and damage to the overall inelastic response, and to confirm the mechanisms by rigorous microstructural evaluations. The results of room temperature experiments performed on 0 degree and 90 degree systems primarily are reported in this report. Results of experiments performed on other laminate systems and at high temperatures will be provided in a forthcoming report. Inelastic deformation of the 0 degree MMC (fibers parallel to load direction) was dominated by the plasticity of the matrix. In contrast, inelastic deformations of the 90 degree composite (fibers perpendicular to loading direction) occurred by both damage and plasticity. The predictions of a continuum elastic plastic model were compared with experimental data. The model was adequate for predicting the 0 degree response; however, it was inadequate for predicting the 90 degree response largely because it neglected damage. The importance of validating constitutive models using a combination of mechanical measurements and microstructural analysis is pointed out. The deformation mechanisms, and the likely sequence of events associated with the inelastic deformation of MMCs, are indicated in this paper.

Majumdar, B. S.↗
NASA NTRS1994

Parallel DSMC Solution of Three-Dimensional Flow Over a Finite Flat Plate

This paper describes a parallel implementation of the direct simulation Monte Carlo (DSMC) method. Runtime library support is used for scheduling and execution of communication between nodes, and domain decomposition is performed dynamically to maintain a good load balance. Performance tests are conducted using the code to evaluate various remapping and remapping-interval policies, and it is shown that a one-dimensional chain-partitioning method works best for the problems considered. The parallel code is then used to simulate the Mach 20 nitrogen flow over a finite-thickness flat plate. It is shown that the parallel algorithm produces results which compare well with experimental data. Moreover, it yields significantly faster execution times than the scalar code, as well as very good load-balance characteristics.

Nance, Robert P.↗
NASA NTRS2019

Tuning the Performance of a Computational Persistent Homology Package

In recent years, persistent homology has become an attractive method for data analysis. It captures topological features, such as connected components, holes, and voids from point cloud data and summarizes the way in which these features appear and disappear in a filtration sequence. In this project, we focus on improving the performanceof Eirene, a computational package for persistent homology. Eirene is a 5000-line open-source software library implemented in the dynamic programming language Julia. We use the Julia profiling tools to identify performance bottlenecks and develop novel methods to manage them, including the parallelization of some time-consuming functions on multicore/manycore hardware. Empirical results show that performance can be greatly improved.

Persistent Homology↗
NASA NTRSDate not supplied

Sub-kW Class Hall-Effect Thruster Power Processing Unit for Wide Output Range Applications

The National Aeronautics and Space Administration (NASA) Small Spacecraft Electric Propulsion (SSEP) project is maturing high-propellant throughput sub-kilowatt Hall-effect thruster technologies to enable small spacecraft deep space science and exploration missions with high delta-v requirements. In support of this effort, development of a power processing unit (PPU) capable of providing discharge power of up to 1 kW continues to be pursued at the NASA Glenn Research Center (GRC). Previous reported work included a successful integrated test of a scalable, modular breadboard discharge power supply with the NASA-H64M laboratory model Hall-effect thruster and presentation of notional designs for the various auxiliary power supplies needed for thruster operation. Since that time, auxiliary power supply designs have been completed and fabricated, with the cathode heater and keeper power supplies being successfully tested with a hollow cathode assembly (HCA) in the NASA GRC Vacuum Facility 56 (VF-56). The desire for a lower mass, higher efficiency, and more versatile PPU to maximize performance of power and mass-limited small spacecraft has led to the exploration of a discharge power supply based on a series-parallel (LCC) resonant topology. This topology has enabled the discharge power supply to operate over a wider output range at switching frequencies 4-5 times higher than previous design iterations. Simulation models of the topology have been developed and a breadboard of the topology has been fabricated and evaluated on both resistive loads and an integrated Hall thruster test. This paper will present collected performance and integrated test data from both the fabricated auxiliary and resonant discharge power supplies. Advantages of the resonant converter architecture over more traditional pulse-width modulated (PWM) techniques in Hall-effect thruster discharge power supply applications will also be described.

electric propulsion↗
NASA NTRSDate not supplied

Sub-kW Class Hall-Effect Thruster Power Processing Unit for Wide Output Range Applications

The National Aeronautics and Space Administration (NASA) Small Spacecraft Electric Propulsion (SSEP) project is maturing high-propellant throughput sub-kilowatt Hall-effect thruster technologies to enable small spacecraft deep space science and exploration missions with high delta-v requirements. In support of this effort, development of a power processing unit (PPU) capable of providing discharge power of up to 1 kW continues to be pursued at the NASA Glenn Research Center (GRC). Previous reported work included a successful integrated test of a scalable, modular breadboard discharge power supply with the NASA-H64M laboratory model Hall-effect thruster and presentation of notional designs for the various auxiliary power supplies needed for thruster operation. Since that time, auxiliary power supply designs have been completed and fabricated, with the cathode heater and keeper power supplies being successfully tested with a hollow cathode assembly (HCA) in the NASA GRC Vacuum Facility 56 (VF-56). The desire for a lower mass, higher efficiency, and more versatile PPU to maximize performance of power and mass-limited small spacecraft has led to the exploration of a discharge power supply based on a series-parallel (LCC) resonant topology. This topology has enabled the discharge power supply to operate over a wider output range at switching frequencies 4-5 times higher than previous design iterations. Simulation models of the topology have been developed and a breadboard of the topology has been fabricated and evaluated on both resistive loads and an integrated Hall thruster test. This paper will present collected performance and integrated test data from both the fabricated auxiliary and resonant discharge power supplies. Advantages of the resonant converter architecture over more traditional pulse-width modulated (PWM) techniques in Hall-effect thruster discharge power supply applications will also be described.

electric propulsion↗
NASA NTRS2021

NASA SpaceCube Edge TPU SmallSat Card for Autonomous Operations and Onboard Science-Data Analysis

Using state-of-the-art artificial intelligence (AI)frameworks onboard spacecraft is challenging because common spacecraft processors cannot provide comparable performance to datacenters with server-grade CPUs and GPUs available for terrestrial applications and advanced deep-learning networks. This limitation makes small, lo w-p o we r AI microchip architectures, such as the Google Coral Edge Tensor Processing Unit (TPU), attractive for space missions where the application-specific design enables both high-performance and power-efficient computing for AI applications. To address these challenging considerations for space deployment, this research introduces the design and capabilities of a CubeSat-sized Edge TPU-based co-processor card, known as the SpaceCube Low-power Ed g e Artificial Intelligence Resilient Node (SC-LEARN). This design conforms to NASA’s CubeSat Card Specification (CS2) for integration into next-generation SmallSat and CubeSat systems. This paper describes the overarching architecture and design of the SC-LEARN, as well as, the supporting test card designed for rapid prototyping and evaluation. The SC-LEARN was developed with three operational modes: (1) a high-performance parallel-processing mode,(2)a fault-tolerant mode for onboard resilience, and (3) a power-saving mode with cold spares. Importantly, this research also elaborates on both training and quantization of Tensor Flow models for the SC-LEARN for use onboard with representative, open-source datasets. Lastly, we describe future research plans, including radiation-beam testing and flight demonstration.

Advanced avionics↗
DOE OSTI2025

Bayesian Optimized Deep Ensemble for Uncertainty Quantification of Deep Neural Networks: a System Safety Case Study on Sodium Fast Reactor Thermal Stratification Modeling

Deep neural networks (DNNs) are increasingly important to scientific computing and engineering system simulations. Accurate uncertainty quantification (UQ) for DNNs is critical in safety-sensitive engineering domains. Traditional Deep Ensemble (DE) methods, while easy to implement, frequently suffer from poorly calibrated uncertainty estimates and limited predictive accuracy due to reliance on fixed architectures with varied weight initializations. To address these issues, we introduce a workflow that combines Bayesian Optimization (BO) and DE. The workflow is modular, scalable, and integrates parallel BO initialized with Sobol sequences to individually optimize the hyperparameters of each ensemble member. This method enhances ensemble diversity, improves predictive accuracy, and provides reliable uncertainty estimates. We evaluate the proposed BODE approach in a sodium fast reactor thermal stratification modeling case study, where we used a densely connected convolutional neural network to predict turbulent viscosity during the reactor transient with consideration of data noise. We benchmark its performance against several optimization approaches, including baseline deep ensemble, evolutionary algorithm-optimized ensemble, ensemble formed via random search combined with greedy selection, and a BO ensemble using random initialization. Here, our results demonstrate superior performance of the developed BODE approach. In noise-free scenarios, BODE notably reduces incorrect aleatoric uncertainty and significantly enhances predictive accuracy. Under conditions of 5% and 10% Gaussian noise, BODE adaptively quantifies uncertainty proportional to data noise, achieving up to an 80% reduction in root mean square error compared to baseline methods and producing well-calibrated prediction intervals.

Bayesian optimization↗
DOE OSTI2025

Lowering and Runtime Support for Fortran’s Multi-Image Parallel Features using LLVM Flang, PRIF, and Caffeine

This paper provides an overview of the multi-image parallel features in Fortran 2023 and their implementation in the LLVM flang compiler and the Caffeine parallel runtime library. The features of interest support a Single-Program, Multiple-Data (SPMD) programming model based on executing multiple “images”, each of which is a program instance. The features also support a Partitioned Global Address Space (PGAS) in the form of “coarray” distributed data structures. The paper discusses the lowering of multi-image features to the Parallel Runtime Interface for Fortran (PRIF) and the implementation of PRIF in the Caffeine parallel runtime library. This paper also provides an early view into the design of a new multi-image dialect of the LLVM Multi-Level Intermediate Representation (MLIR). We describe validation and testing of the resulting software stack, and demonstrate that performance compares favorably to another open-source compiler and runtime library: GNU Compiler Collection (GCC) gfortran and OpenCoarrays, respectively.

Bonachea, Dan↗
NASA NTRS1974

An evaluation of machine processing techniques of ERTS-1 data for user applications

A broad study is described to evaluate a set of machine analysis and processing techniques applied to ERTS-1 data. Based on the analysis results in urban land use analysis and soil association mapping together with previously reported results in general earth surface feature identification and crop species classification, a profile of general applicability of this procedure is beginning to emerge. Put in the hands of a user who knows well the information needed from the data and also is familiar with the region to be analyzed it appears that significantly useful information can be generated by these methods. When supported by preprocessing techniques such as the geometric correction and temporal registration capabilities, final products readily useable by user agencies appear possible. In parallel with application, through further research, there is much potential for further development of these techniques both with regard to providing higher performance and in new situations not yet studied.

Landgrebe, D.↗
NASA NTRS1988

PC-CUBE: A Personal Computer Based Hypercube

PC-CUBE is an ensemble of IBM PCs or close compatibles connected in the hypercube topology with ordinary computer cables. Communication occurs at the rate of 115.2 K-band via the RS-232 serial links. Available for PC-CUBE is the Crystalline Operating System III (CrOS III), Mercury Operating System, CUBIX and PLOTIX which are parallel I/O and graphics libraries. A CrOS performance monitor was developed to facilitate the measurement of communication and computation time of a program and their effects on performance. Also available are CXLISP, a parallel version of the XLISP interpreter; GRAFIX, some graphics routines for the EGA and CGA; and a general execution profiler for determining execution time spent by program subroutines. PC-CUBE provides a programming environment similar to all hypercube systems running CrOS III, Mercury and CUBIX. In addition, every node (personal computer) has its own graphics display monitor and storage devices. These allow data to be displayed or stored at every processor, which has much instructional value and enables easier debugging of applications. Some application programs which are taken from the book Solving Problems on Concurrent Processors (Fox 88) were implemented with graphics enhancement on PC-CUBE. The applications range from solving the Mandelbrot set, Laplace equation, wave equation, long range force interaction, to WaTor, an ecological simulation.

Ho, Alex↗
NASA NTRS1994

A second generation 50 Mbps VLSI level zero processing system prototype

Level Zero Processing (LZP) generally refers to telemetry data processing functions performed at ground facilities to remove all communication artifacts from instrument data. These functions typically include frame synchronization, error detection and correction, packet reassembly and sorting, playback reversal, merging, time-ordering, overlap deletion, and production of annotated data sets. The Data Systems Technologies Division (DSTD) at Goddard Space Flight Center (GSFC) has been developing high-performance Very Large Scale Integration Level Zero Processing Systems (VLSI LZPS) since 1989. The first VLSI LZPS prototype demonstrated 20 Megabits per second (Mbp's) capability in 1992. With a new generation of high-density Application-specific Integrated Circuits (ASIC) and a Mass Storage System (MSS) based on the High-performance Parallel Peripheral Interface (HiPPI), a second prototype has been built that achieves full 50 Mbp's performance. This paper describes the second generation LZPS prototype based upon VLSI technologies.

Harris, Jonathan C.↗
NASA NTRS2011

First Lunar Wake Passage of ARTEMIS: Discrimination of Wake Effects and Solar Wind Fluctuations by 3D Hybrid Simulations

The spacecraft P1 of the new ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) mission passed the lunar wake for the first time on February 13, 2010. We present magnetic field and plasma data of this event and results of 3D hybrid simulations. As the solar wind magnetic field was highly dynamic during the passage, a simulation with stationary solar wind input cannot distinguish whether distortions were caused by these solar wind variations or by the lunar wake; therefore, a dynamic real-time simulation of the flyby has been performed. The input values of this simulation are taken from NASA OMNI data and adapted to the P1 data, resulting in a good agreement between simulation and measurements. Combined with the stationary simulation showing non-transient lunar wake structures, a separation of solar wind and wake effects is achieved. An anisotropy in the magnitude of the plasma bulk flow velocity caused by a non-vanishing magnetic field component parallel to the solar wind flow and perturbations created by counterstreaming ions in the lunar wake are observed in data and simulations. The simulations help to interpret the data granting us the opportunity to examine the entire lunar plasma environment and, thus, extending the possibilities of measurements alone: A comparison of a simulation cross section to theoretical predictions of MHD wave propagation shows that all three basic MHD modes are present in the lunar wake and that their expansion governs the lunar wake refilling process.

Wiehle, S.↗
NASA NTRS2012

The Development of Models for Carbon Dioxide Reduction Technologies for Spacecraft Air Revitalization

Through the respiration process, humans consume oxygen (O2) while producing carbon dioxide (CO2) and water (H2O) as byproducts. For long term space exploration, CO2 concentration in the atmosphere must be managed to prevent hypercapnia. Moreover, CO2 can be used as a source of oxygen through chemical reduction serving to minimize the amount of oxygen required at launch. Reduction can be achieved through a number of techniques. NASA is currently exploring the Sabatier reaction, the Bosch reaction, and co- electrolysis of CO2 and H2O for this process. Proof-of-concept experiments and prototype units for all three processes have proven capable of returning useful commodities for space exploration. All three techniques have demonstrated the capacity to reduce CO2 in the laboratory, yet there is interest in understanding how all three techniques would perform at a system level within a spacecraft. Consequently, there is an impetus to develop predictive models for these processes that can be readily rescaled and integrated into larger system models. Such analysis tools provide the ability to evaluate each technique on a comparable basis with respect to processing rates. This manuscript describes the current models for the carbon dioxide reduction processes under parallel developmental efforts. Comparison to experimental data is provided were available for verification purposes.

Swickrath, Michael J.↗
NASA NTRSDate not supplied

From Here to There - Bird's Eye Perspective on Grant Lifecycle and Administration

“What gets measured gets done ”or “measure it to manage it”. The statements have become matter of fact. However, measurement (and even metrics) alone cannot fully communicate an organization’s story without the point of accountability. As a dynamic org, we must measure what is necessary, using the appropriate lenses to analyze the most relevant information that allows robust decision-making. A key function of Program Planning and Control (PP&C) is to assist HRP in the development of such strategy that ensures the proper execution of program research goals. With introspection of the Technical Officer role as defined by 2 CFR(i.e., Part 200, Part 1800)and subsequent governance under the NASA Grant and Cooperative Agreement Manual (GCAM), we’ve realized an obvious disconnect among Principal Investigator’s (PI),technical communication with the elements and some of the administrative/fiduciary requirements that should run parallel to the science work. This find has introduced new program risks as evidenced through incomplete deliverables or other less-than-successful requirements through the lifecycle for work we fund. One solution the Grants Technical Officer proposes is for PP&C to share in the communication with stakeholders of grants administration much earlier in the award process in attempt to reduce programmatic risks; particularly in data, reporting and performance management. As such, the planned IWS 2022 session will focus on(plenary) topics that include (1) definition of the grant lifecycle, (2) anatomy of a grant(NF1687 the award document), and (3)performance measurement/post-award monitoring. As HH&P pursues its strategic objectives to evolve the directorate into a data rich and knowledge rich organization, it has become increasingly important to develop the multiple levels of insight across the program to ensure data and other reporting(qualitative/quantitative), alongside proper administration. And the desired outcome is to make certain HRP meets/exceeds the accountability standard that our research information is received, maintained and accessible in posterity.

Lucy D Barnes-Moten↗
DOE OSTI2025

Genetic algorithm optimization of nuclear criticality experiment for reduction of intermediate-energy 239 Pu nuclear data uncertainties

Nuclear criticality experiments are conducted to investigate specific nuclear data important for safe handling and storage of fissile materials, reactor design and operation, and the validation of radiation transport codes. Incorrect or uncertain nuclear data can prohibitively impact operational safety limits, reactor licensing, and predictive simulation capability; therefore, integral measurements from criticality experiments are necessary and should be performed frequently. To maximize the impact of the integral measurements, it is important to consider experiment geometry, material selection, and component dimensions. When taking these considerations into account, the experiment design process becomes iterative and very time intensive. This work utilizes a genetic algorithm to efficiently explore potential nuclear criticality experiment designs for the Laboratory Directed Research & Development project PARADIGM (PARallel Approach of Differential and InteGral Measurements) at Los Alamos National Laboratory. In this paper, the building blocks of the genetic algorithm are discussed in detail, the genetic algorithm methodology is verified, and the genetic algorithm is used to produce three candidate experiment models for the final PARADIGM design. The three candidate models produced by the genetic algorithm consist of copper-reflected assemblies containing 14 repeating units of alumina, graphite, boron, and plutonium plates. Furthermore, in addition to the optimization results, final design considerations are also discussed for designs with a height and/or weight very close to or slightly above assembly machine operational limits.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

Control And Optimization Modular Modeling Application For Nuclear Deployment

The purpose of the COMMAND code is to provide a flexible, scalable tool for use in developing, integrating, and testing the technologies necessary for achieving autonomous operations of advanced nuclear reactors. The code enables users to efficiently implement custom simulations and experiments by combining key methods from different software modules. These modules are focused on: modeling and simulation tools, such as nuclear simulation tools used for high-fidelity modeling (e.g., Reactor Excursion and Leak Analysis Program [RELAP5-3D] and Monte Carlo N-Particle [MCNP]); machine learning and optimization tools (e.g., anomaly detection and data-driven modeling techniques); advanced control in its digital, high-performance, and supervisory control forms (e.g., proportional integral derivative (PID) control and model predictive control (MPC); and integration with hardware through industrial communication protocols. To ensure flexibility and scalability, COMMAND was designed to be both modular—the software “pieces” all inherit from generic building blocks and can be combined and connected to create complicated simulations—and high performing—designed for parallel processing, enabling simulations and experiments to take advantage of multi-core computers, servers, and nodes. The code is written in the Python programming language due to the language's popularity, active community, and open-source and cross-platform nature. Maintaining consistency with other simulation tools used within the nuclear energy community, users implement simulations and experiments through text input files, which define components, parameters, connections, etc., through lines of text. Given that COMMAND is written in Python, these input files are native Python scripts, and so use the standard Python structure and formatting. This also enables users to take advantage of Python's extensive package library to develop custom capabilities for their specific use cases.

Faber, Jacob [Idaho National Laboratory (INL), Ida↗
NASA NTRS1991

Effects of space environment on space-based radar phased-array antenna: Status and preliminary observations

The overall objective is to evaluate the effect of the space environment on Kapton films considered for the Grumman space based radar (SBR) phased-array antenna. The most striking result is the overall good condition of the Kapton antenna planes and Kapton tensile specimens. This is largely attributable to the orientation of the Kapton (parallel and flush on the space end) and the stability of the LDEF in orbit. Results on elongation and mechanical properties of the plain and fiberglass reinforced Kapton will be described. Stress-dependent permanent deformation and some reductions in strain to failure were observed. Physical property testing of the materials is in progress. Electronic data acquisition and memory systems appeared to operate correctly, but functional tests were not yet performed. An evaluation of the high voltage-plasma interaction data is underway. Some minor systems anomalies (e.g., fastener sheared during removal, strong odor inside electronics container) were noted. Other observations such as radiation, contamination, impacts, and orientation features of atomic oxygen erosion are reported.

Whiteside, J. B.↗
NASA NTRS1999

177-207 GHz Radiometer Front End: Single Sideband Measurements

Twenty years of progress in 200 GHz receivers for spaceborne remote sensing has yielded a 180-220 GHz technology with maturing characteristics, as evident by increasing availability of relevant hardware, paralleled by further refinement in receiver performance requirements at this spectrum band. The 177-207 GHz superheterodyne receiver, for the Earth observing system (EOS) microwave limb sounder (MLS), effectively illustrates such technology developments. This MLS receiver simultaneously detects six different signals, located at sidebands below and above its 191.95 GHZ local-oscillator (LO). The paper describes the MLS 177-207 GHz receiver front-end (RFE), and provides measured data for its lower and upper sidebands. Sideband ratio data is provided as a function of IF frequency, at different LO power drive, and for variation in the ambient temperature.

Galin, I.↗