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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Adiabatic light guide with S-shaped strips

A light guide is an essential part of many scintillator counters and light collection systems. Our main interest is a light guide for a thin, wide scintillator that has high light transmission while converting the area of the light source to the shape of a photo-detector. Here, we propose a variation of the light guide that avoids a 90° twist of the strips, reduces the length of the light pipe, and reduces the complexity of production. Detailed Monte Carlo simulation studies have been performed for a three-strip S-shaped light-guide system.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Quadrupolar density structures in driven magnetic reconnection experiments with a guide field

Magnetic reconnection is a ubiquitous process in plasma physics, driving rapid and energetic events such as coronal mass ejections. Reconnection between magnetic fields with arbitrary shear can be decomposed into an anti-parallel reconnecting component and a non-reconnecting guide-field component, which is parallel to the reconnecting electric field. This guide field modifies the structure of the reconnection layer and the reconnection rate. We present results from experiments on the MAIZE pulsed-power generator (500 kA peak current, 200 ns rise time), which use two exploding wire arrays, tilted in opposite directions, to embed a guide field in the plasma flows with a relative strength b≡B g /B rec =0, 0.4, or 1. The reconnection layers in these experiments have widths that are less than the ion skin depth, d i =c/ω pi , indicating the importance of the Hall term, which generates a distinctive quadrupolar magnetic field structure along the separatrices of the reconnection layer. Using laser imaging interferometry, we observe quadrupolar structures in the line-integrated electron density, consistent with the interaction of the embedded guide field with the quadrupolar Hall field. Our measurements extend over much larger length scales (40d i ) at higher β (∼1) than previous experiments, providing an insight into the global structure of the reconnection layer.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Knowledge-guided learning with curated prior genetic biomarkers for robust model interpretation

Abstract Motivation Knowledge-guided learning offers effective and robust model training strategies in data-scarce settings by incorporating established domain knowledge, thereby enhancing generalization, robustness, and interpretability. By contrast, conventional deep learning approaches rely purely on data-driven learning, which can limit robust model interpretability, particularly in high-dimensional settings with limited size samples. In computational biology, knowledge-guided learning has primarily leveraged network- and structural-based knowledge, leading to biologically interpretable representations and enhanced predictive performance compared to conventional approaches. However, curated biomarkers, one of the most accessible forms of biological knowledge, remain largely unexplored within knowledge-guided paradigms. Results In this study, we propose a model-agnostic training paradigm, Biomarker-driven Explainable Prior-guided Learning (BioExPL), that can be applied to any neural networks that incorporates curated prior knowledge. BioExPL enforces neural networks to reflect curated biomarker priors in their latent representations through a novel knowledge-alignment loss. BioExPL consistently demonstrated significantly improved predictive performance and enhanced model interpretability with minimized computational overhead in simulation studies and intensive experiments on multiple cancer datasets. BioExPL not only integrates prior curated knowledge into the model but also accurately identifies unknown associated signals additionally. BioExPL is model-agnostic and domain-independent, enabling its integration into diverse neural network architectures. Availability and implementation The open-source is publicly available at: https://github.com/datax-lab/BioExPL.

Baek, Beomsu [Department of Computer Science, Univ↗
DOE OSTI2024

MAPIT User's Guide: v1.4.6-beta

The purpose of this guide is to serve as an introduction to practical usage of MAPIT and it’s underlying principles. This guide is not intended to be an comprehensive guide to safeguards or material accountancy. The reader is encouraged to review suggestions for additional reading in the theory guide for further understanding.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Threat Hunt Guide for BESS Environments

The rapid digitalization of the electric grid - driven by the integration of inverter-based resources (IBRs), battery energy storage systems (BESS), and advanced grid control platforms - has significantly enhanced grid efficiency, visibility, and flexibility. However, this evolution also introduces new cybersecurity risks, particularly through supply chain dependencies and operational blind spots at the grid edge. To address these challenges, Idaho National Laboratory (INL), through the Department of Energy (DOE) Office of Cybersecurity, Energy Security, and Emergency Response (CESER) Rapid Risk initiative, conducted a series of rapid risk assessment engagements with energy organizations across the United States. Drawing on lessons learned from these engagements, INL developed the following threat hunting guide for asset owners and operators (AOOs) to enhance their cybersecurity visibility within BESS and IBR systems. The guide demonstrates how to use passive network monitoring to baseline device behavior, detect adversarial activity, and investigate anomalies without disrupting operations. By implementing these practices, energy sector stakeholders can improve coordination between cybersecurity and operations teams and strengthen the resilience of distributed energy resources (DERs) within the modern power grid. Prior to implementing any network monitoring, packet capture, or threat hunting activity described in this guide, AOOs are strongly advised to review applicable governance frameworks, legal requirements, and organizational policies. This guide is intended for informational and educational purposes only. It does not replace compliance with any federal, state, or local cybersecurity mandates or industry standards. Implementation of described configurations, technologies, or analytic workflows is performed at the discretion and responsibility of the asset owner and operator.

25 - ENERGY STORAGE↗
NASA NTRS1981

Effect of a part-span variable inlet guide vane on the performance of a high-bypass turbofan engine

The ability of a part-span variable inlet guide vane to modulate the thrust of a high bypass turbofan engine was evaluated at altitude/Mach number conditions of 4572 m/0.6 and 9144 m/0.93. Fan-tip, gas generator and supercharger performance were also determined, both on operating lines and during fan duct throttling. The evaluation was repeated with the bypass splitter extended forward to near the fan blade trailing edge. Gross thrust attenuation of over 50% was achieved with 50 deg variable inlet guide vane closure at 100% corrected fan speed. Gas generator supercharger performance fell off with variable inlet guide vane closure but this loss was reduced when a splitter extension was added. The effect of variable inlet guide vane closure on gas generator performance was minimal.

Bobula, G. A.↗
NASA NTRS1950

Investigation of Power Requirements for Ice Prevention and Cyclical De-Icing of Inlet Guide Vanes with Internal Electric Heaters

An investigation was conducted to determine the electric power requirements necessary for ice protection of inlet guide vanes by continuous heating and by cyclical de-icing. Data are presented to show the effect of ambient-air temperature, liquid-water content, air velocity, heat-on period, and cycle times on the power requirements for these two methods of ice protection. The results showed that for a hypothetical engine using 28 inlet guide vanes under similar icing conditions, cyclical de-icing can provide a total power saving as high as 79 percent over that required for continuous heating. Heat-on periods in the order of 10 seconds with a cycle ratio of about 1:7 resulted in the best over-all performance with respect to total power requirements and aerodynamic losses during the heat-off period. Power requirements reported herein may be reduced by as much as 25 percent by achieving a more uniform surface-temperature distribution. A parameter in terms of engine mass flow, vane size, vane surface temperature, and the icing conditions ahead of the inlet guide vanes.was developed by which an extension of the experimental data to icing conditions and inlet guide vanes, other than those investigated was possible.

VonGlahn, Uwe↗
NASA NTRS1987

Design, implementation and investigation of an image guide-based optical flip-flop array

Presented is the design for an image guide-based optical flip-flop array created using a Hughes liquid crystal light valve and a flexible image guide in a feedback loop. This design is used to investigate the application of image guides as a communication mechanism in numerical optical computers. It is shown that image guides can be used successfully in this manner but mismatch match between the input and output fiber arrays is extremely limiting.

Griffith, P. C.↗
NASA NTRS1987

Numerical study of laminar and turbulent flows inside a turnaround duct with and without guide vanes

The purpose of this study is to examine in detail incompressible laminar and turbulent flows inside a turnaround duct with and without guide vanes and to investigate the effects of vanes on the flow characteristics. To perform this study, an implicit finite difference code cast in general curvilinear coordinates is further developed. The code is based on the method of pseudo-compressibility and utilize ADI or implicit approximate factorization algorithm to achieve computational efficiency. Method of segmental sweeping is developed to overcome the multiple-zone problem due to imposition of guide vanes. In the present study, several test cases have been computed. These test cases include laminar and turbulent flows inside a turnaround duct without and with two or three guide vanes. The study reveals that: (1) there exists large recirculation zones inside the duct if no vanes are present; (2) properly shaped and positional guide vanes are effective in eliminating flow separation; and (3) laminar and turbulent flows have similar flow features. But turbulent flow has less total pressure drop.

Lin, S.-J.↗
NASA NTRS1992

Reliable vision-guided grasping

Automated assembly of truss structures in space requires vision-guided servoing for grasping a strut when its position and orientation are uncertain. This paper presents a methodology for efficient and robust vision-guided robot grasping alignment. The vision-guided grasping problem is related to vision-guided 'docking' problems. It differs from other hand-in-eye visual servoing problems, such as tracking, in that the distance from the target is a relevant servo parameter. The methodology described in this paper is hierarchy of levels in which the vision/robot interface is decreasingly 'intelligent,' and increasingly fast. Speed is achieved primarily by information reduction. This reduction exploits the use of region-of-interest windows in the image plane and feature motion prediction. These reductions invariably require stringent assumptions about the image. Therefore, at a higher level, these assumptions are verified using slower, more reliable methods. This hierarchy provides for robust error recovery in that when a lower-level routine fails, the next-higher routine will be called and so on. A working system is described which visually aligns a robot to grasp a cylindrical strut. The system uses a single camera mounted on the end effector of a robot and requires only crude calibration parameters. The grasping procedure is fast and reliable, with a multi-level error recovery system.

Nicewarner, Keith E.↗
NASA NTRS1992

Reliable vision-guided grasping

Automated assembly of truss structures in space requires vision-guided servoing for grasping a strut when its position and orientation are uncertain. This paper presents a methodology for efficient and robust vision-guided robot grasping alignment. The vision-guided grasping problem is related to vision-guided 'docking' problems. It differs from other hand-in-eye visual servoing problems such as tracking in that the distance from the target is a relevant servo parameter. The methodology described in this paper is a hierarchy of levels in which the vision/robot interface is decreasingly 'intelligent', and increasingly fast. Speed is achieved primarily by information reduction. This reduction exploits the use of region-of-interest windows in the image plane and feature motion prediction. These reductions invariably require stringent assumptions about the image. Therefore, at a higher level, these assumptions are verified using slower, more reliable methods. This hierarchy provides for robust error recovery in that when a lower-level routine fails, the next-higher routine will be called and so on. A working system is described which visually aligns a robot to grasp a cylindrical strut. The system uses a single camera mounted on the end effector of a robot and requires only crude calibration parameters. The grasping procedure is fast and reliable, with a multi-level error recovery system.

Nicewarner, Keith E.↗
NASA NTRS1993

Permanent change of station: The NASA employee's guide to an easier move

This guide is for the NASA employee preparing to make a permanent change of station. Whether a transferee or a new appointee, this guide contains information that will help a Government-authorized move go more smoothly from start to finish. The guide outlines the allowances and expense reimbursements one is entitled to under Federal Travel Regulations (FTR). It provides samples of forms one may need to fill out to start the transfer rolling and to claim reimbursements. However, it is important to note that this guide is not a copy of the FTR. Information in the FTR and the NASA Travel Regulations, FMM 9760, is far more detailed and is always updated and correct.

Source record↗
NASA NTRS1994

TRENDS: A flight test relational database user's guide and reference manual

This report is designed to be a user's guide and reference manual for users intending to access rotocraft test data via TRENDS, the relational database system which was developed as a tool for the aeronautical engineer with no programming background. This report has been written to assist novice and experienced TRENDS users. TRENDS is a complete system for retrieving, searching, and analyzing both numerical and narrative data, and for displaying time history and statistical data in graphical and numerical formats. This manual provides a 'guided tour' and a 'user's guide' for the new and intermediate-skilled users. Examples for the use of each menu item within TRENDS is provided in the Menu Reference section of the manual, including full coverage for TIMEHIST, one of the key tools. This manual is written around the XV-15 Tilt Rotor database, but does include an appendix on the UH-60 Blackhawk database. This user's guide and reference manual establishes a referrable source for the research community and augments NASA TM-101025, TRENDS: The Aeronautical Post-Test, Database Management System, Jan. 1990, written by the same authors.

Bondi, M. J.↗
NASA NTRS1998

Spread Spectrum Receiver Electromagnetic Interference (EMI) Test Guide

The objective of this test guide is to document appropriate unit level test methods and techniques for the performance of EMI testing of Direct Sequence (DS) spread spectrum receivers. Consideration of EMI test methods tailored for spread spectrum receivers utilizing frequency spreading, techniques other than direct sequence (such as frequency hopping, frequency chirping, and various hybrid methods) is beyond the scope of this test guide development program and is not addressed as part of this document EMI test requirements for NASA programs are primarily developed based on the requirements contained in MIL-STD-46 1 D (or earlier revisions of MIL-STD-46 1). The corresponding test method guidelines for the MIL-STD-461 D tests are provided in MIL-STD-462D. These test methods are well documented with the exception of the receiver antenna port susceptibility tests (intermodulation, cross modulation, and rejection of undesired signals) which must be tailored to the specific type of receiver that is being tested. Thus, test methods addressed in this guide consist only of antenna port tests designed to evaluate receiver susceptibility characteristics. MIL-STD-462D should be referred for guidance pertaining to test methods for EMI tests other than the antenna port tests. The scope of this test guide includes: (1) a discussion of generic DS receiver performance characteristics; (2) a summary of S-band TDRSS receiver operation; (3) a discussion of DS receiver EMI susceptibility mechanisms and characteristics; (4) a summary of military standard test guidelines; (5) recommended test approach and methods; and (6) general conclusions and recommendations for future studies in the area of spread spectrum receiver testing.

Wheeler, M. L.↗
NASA NTRS2001

Aerodynamic Performance of Scale-Model Turbofan Outlet Guide Vanes Designed for Low Noise

The design of effective new technologies to reduce aircraft propulsion noise is dependent on an understanding of the noise sources and noise generation mechanisms in the modern turbofan engine. In order to more fully understand the physics of noise in a turbofan engine, a comprehensive aeroacoustic wind tunnel test programs was conducted called the 'Source Diagnostic Test.' The text was cooperative effort between NASA and General Electric Aircraft Engines, as part of the NASA Advanced Subsonic Technology Noise Reduction Program. A 1/5-scale model simulator representing the bypass stage of a current technology high bypass ratio turbofan engine was used in the test. The test article consisted of the bypass fan and outlet guide vanes in a flight-type nacelle. The fan used was a medium pressure ratio design with 22 individual, wide chord blades. Three outlet guide vane design configurations were investigated, representing a 54-vane radial Baseline configuration, a 26-vane radial, wide chord Low Count configuration and a 26-vane, wide chord Low Noise configuration with 30 deg of aft sweep. The test was conducted in the NASA Glenn Research Center 9 by 15-Foot Low Speed Wind Tunnel at velocities simulating the takeoff and approach phases of the aircraft flight envelope. The Source Diagnostic Test had several acoustic and aerodynamic technical objectives: (1) establish the performance of a scale model fan selected to represent the current technology turbofan product; (2) assess the performance of the fan stage with each of the three distinct outlet guide vane designs; (3) determine the effect of the outlet guide vane configuration on the fan baseline performance; and (4) conduct detailed flowfield diagnostic surveys, both acoustic and aerodynamic, to characterize and understand the noise generation mechanisms in a turbofan engine. This paper addresses the fan and stage aerodynamic performance results from the Source Diagnostic Test.

Hughes, Christopher E.↗
NASA NTRS2013

3D Guided Wave Motion Analysis on Laminated Composites

Ultrasonic guided waves have proved useful for structural health monitoring (SHM) and nondestructive evaluation (NDE) due to their ability to propagate long distances with less energy loss compared to bulk waves and due to their sensitivity to small defects in the structure. Analysis of actively transmitted ultrasonic signals has long been used to detect and assess damage. However, there remain many challenging tasks for guided wave based SHM due to the complexity involved with propagating guided waves, especially in the case of composite materials. The multimodal nature of the ultrasonic guided waves complicates the related damage analysis. This paper presents results from parallel 3D elastodynamic finite integration technique (EFIT) simulations used to acquire 3D wave motion in the subject laminated carbon fiber reinforced polymer composites. The acquired 3D wave motion is then analyzed by frequency-wavenumber analysis to study the wave propagation and interaction in the composite laminate. The frequency-wavenumber analysis enables the study of individual modes and visualization of mode conversion. Delamination damage has been incorporated into the EFIT model to generate "damaged" data. The potential for damage detection in laminated composites is discussed in the end.

Tian, Zhenhua↗
NASA NTRS2016

Phased Array Beamforming and Imaging in Composite Laminates Using Guided Waves

This paper presents the phased array beamforming and imaging using guided waves in anisotropic composite laminates. A generic phased array beamforming formula is presented, based on the classic delay-and-sum principle. The generic formula considers direction-dependent guided wave properties induced by the anisotropic material properties of composites. Moreover, the array beamforming and imaging are performed in frequency domain where the guided wave dispersion effect has been considered. The presented phased array method is implemented with a non-contact scanning laser Doppler vibrometer (SLDV) to detect multiple defects at different locations in an anisotropic composite plate. The array is constructed of scan points in a small area rapidly scanned by the SLDV. Using the phased array method, multiple defects at different locations are successfully detected. Our study shows that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

Tian, Zhenhua↗
NASA NTRSDate not supplied

Co-developing a SAR for Disasters Reference Guide for the International Applications Community

Synthetic Aperture Radar (SAR) data are widely applicable for disaster monitoring, especially in Central and South America where atmospheric effects are a frequent obstacle for disaster monitoring. There is a growing interest in the application of SAR data to diverse disasters, ranging from landslides to volcanic eruptions and floods. With this interest comes a growing need for user-friendly guides that facilitate the integration of SAR into existing workflows. A joint effort between AmeriGEO, university networks in the Americas, NASA SERVIR’s Science Coordination Office (SCO), and the NASA Earth Science Disasters Program, culminated in the “SAR for Disasters” Guide. The guide is modeled after the one-page informational sheets created for SERVIR’s SAR Handbook, with the aim to succinctly communicate the key considerations needed to apply relevant analyses using SAR. Developed with contributors from diverse backgrounds, this guide is designed to be a useful reference for experienced technical users and beginners alike.

SAR↗