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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Low modulation index 3-phase solid state transformer

A solid-state transformer (SST) comprises a transformer core, a primary winding, a secondary winding, a primary-side switch bank, and a secondary-side switch bank. Each of the switch banks includes six 4-quadrant switches. The twelve 4-quadrant switches are toggled on and off over six clock cycles in a repetitive sequence with a period that is a function of a desired operating frequency of the transformer. The sequence is configured such that at any given time, 2 of 3 input and output phases are connected to the primary and secondary windings. The SST further includes L-C filter circuits that are configured to filter high-frequency components of current and voltage waveforms such that these components are not back-fed to the electrical mains or delivered to a load. The SST includes a primary-side filter circuit and a secondary-side filter circuit that can each include respective L-C filters for three input or output phases.

Koplow, Jeffrey P.↗
DOE OSTI2024

Material Characterization Study of Magnetite Nanocrystals for RF Sensing

Magnetite nanocrystals show promise for electrically small gigahertz frequency applications, which could lead to miniaturizing transformer cores and new sensing technologies. This work presents a rigorous radiofrequency characterization of these nanocrystals using vector network analyzer (VNA) ferromagnetic resonance (FMR) measurements. For the first time, two different average diameters of Fe 3 O 4 nanocrystals are investigated (7.3 and 20.2 nm). When the VNA–FMR results were compared to micromagnetic simulations, the magnetic anisotropy (K 1 ) deviated from the ideal mean orientation value of K 1 /2 to K 1 /80 for the 7.3 nm nanocrystal. In contrast, the obtained magnetic anisotropy in 20.2 nm nanocrystals slightly deviated to K 1 /11 due to less structural deformations. These findings resulted in a newly proposed methodology for an approximate simulation based on VNA–FMR measurements. In addition, this work estimates the approximate amount of nanocrystals needed to measure a useful VNA–FMR spectrum.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Adding multiple electrons to helicenes: how they respond?

An overview of structural responses of helicenes with increasing dimensions and complexity to stepwise electron addition reveals charge- and topology-dependent outcomes ranging from reversible to irreversible core transformations and site-specific reactivity.

Chemistry↗
DOE OSTI2024

Toward a Holistic Performance Evaluation of Large Language Models Across Diverse AI Accelerators

Artificial intelligence (AI) methods have become critical in scientific applications to help accelerate scientific discovery. Large language models (LLMs) are being considered a promising approach to address some challenging problems because of their superior generalization capabilities across domains. The effectiveness of the models and the accuracy of the applications are contingent upon their efficient execution on the underlying hardware infrastructure. Specialized Al accelerator hardware systems have recently become available for accelerating Al applications. However, the comparative performance of these AI accelerators on large language models has not been previously studied. In this paper, we systematically study LLMs on multiple AI accelerators and GPUs and evaluate their performance characteristics for these models. We evaluate these systems with (i) a micro-benchmark using a core transformer block, (ii) a GPT-2 model, and (iii) an 1,I,M-driven science use case, GenSLM. We present our findings and analyses of the models' performance to better understand the intrinsic capabilities of AI accelerators. Furthermore, our analysis takes into account key factors such as sequence lengths, scaling behavior, and sensitivity to gradient accumulation steps.

Emani, Murali↗
DOE OSTI2021

Progress in development of pulsed resonant charging power supply for the Spallation Neutron Source extraction kicker PFN system

A conceptual design of the pulsed resonant charging power supply (RCPS) for the beam extraction system of the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) was previously reported at the 2019 IEEE Pulsed Power & Plasma Science Conference (PPPS 2019) [1]. Development and testing of the prototype supply continued through the year to finalize the design ahead of the Proton Power Upgrade (PPU). Testing revealed reliability issues with the original resonant charging scheme related to the step-up transformer core. Additional components were incorporated into the system, and some of the original prototype components were replaced to improve performance and reliability of the power supply. This paper describes the changes in the resonant charging scheme, presents the results of testing of the improved prototype at full power level, and shows the final design of the RCPS.

Peplov, Vladimir↗
DOE OSTI2022

Adrian Portales Coop Internship Report

Using the thesis of W.R. Nolan (cite) as a guide, Cobalt Iron (CoFe) powders were reacted with 0.1 wt.% and 0.2 wt.% phosphoric acid in a 20:1 ratio of acetone to phosphoric acid. The powders were then dried at room temperature. The resulting phosphate coated CoFe was then mixed with 0.75 wt.% of the lubricant N,N' ethylene bis-stearamide (trade name: Acrawax C) and hot pressed to form a consolidated soft magnetic material referred to as CoFeP. With an avenue of synthesis for CoFeP determined, a proper amount of stock was synthesized for continuous “brick” production. While under current optimization, these 1x1 mm magnetic bricks will ultimately be placed and secured along the inside wall of each MK Magnetics transformer core by an appropriate CoFeP dispersed epoxy. As of now each brick has been produced though a pressing and annealing process via square 2x2 cm die. Before a brick is made a pressure calculation is run to ensure the dies maximum operating pressure is not exceeded. Figure 1. ensures the user’s safety by showing that the tons-on-ram required for a 2x2 cm square die to reach 760 MPa is below the point of die failure.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Pulsed Sphere Time of Flight Neutron Spectrum Measurements: Blank Run and 1.8 Mean-Free-Path thick Polyethylene Moderating Sphere

From the late 1960s to 1985, Lawrence Livermore National Laboratory (LLNL) undertook a series of ‘pulsed sphere’ experiments for 32 materials involving 148 different experiments using 75 different spheres to measure the neutron leakage spectra for different materials from 14-MeV neutrons generated by 3 H(d, n) 4 He reactions induced by an incident D+ beam from the Insulated Core Transformer (ICT) accelerator at LLNL. This deuteron beam was focused to impinge on tritium loaded onto a titanium substrate within a low mass target assembly placed within the center of a spherical shell constructed from the material of interest. The neutron time of flight was measured at a detector outside a collimator. The program was intended to be comprehensive with numerous targets of various thicknesses spanning the periodic table from H to 239 Pu. Five different neutron detectors were utilized to avoid possible systematic errors due to differences in detector responses. Further, these measurements were designed with the aim that the simple geometry of the measurements could be easily simulated to validate Monte Carlo transport codes and nuclear data libraries. As a result, these benchmarks have been extensively used in the validation of ENDL, ENDF and other libraries. Two experiments selected as benchmark cases in this evaluation are: 1) target assembly without material sphere (blank run), and 2) target assembly with a hollow polyethylene sphere, 1.8 mean free path (mfp) or 16.56 cm thick.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1970

Apparatus for simultaneous ion counting and current recording in mass spectrometry

Ion counting system is coupled to the last dynode of an Allen-type electron multiplier on the mass analyzer of a double focusing mass spectrometer. This leaves the anode available for an electrometer, making possible simultaneous measurements. Coupling is achieved by a ferrite core transformer and associated circuitry.

Kohl, F. J.↗
NASA NTRS1969

Apparatus for measuring current flow Patent

Electric current measuring apparatus design including saturable core transformer and energy storage device to avoid magnetizing current errors from transformer output winding

Paulkovich, J.↗
NASA NTRS1971

Regulated dc-to-dc converter for voltage step-up or step-down with input-output isolation.

A dc-to-dc regulated-converter circuit employing duty-cycle control with variable on and variable off time has been presented. A unique feature of this converter is the method by which the bistable-comparator output controls the duty cycle of the power switching transistor through the action of the encoder. The utilization of minor-loop flux excursions of a saturable-core transformer in the encoder makes it feasible to extend the converter switching frequency considerably higher than would normally be possible. With this converter circuit, high and very-high frequency converter operations were explored.

Feng, S. Y. M.↗
NASA NTRS1976

Methods for testing high voltage connectors in vacuum, measurements of thermal stresses in encapsulated assemblies, and measurement of dielectric strength of electrodes in encapsulants versus radius of curvature

Internal embedment stress measurements were performed, using tiny ferrite core transformers, whose voltage output was calibrated versus pressure by the manufacturer. Comparative internal strain measurements were made by attaching conventional strain gages to the same type of resistors and encapsulating these in various potting compounds. Both types of determinations were carried out while temperature cycling from 77 C to -50 C.

Bever, R. S.↗
NASA NTRS1980

Fixture for winding transformers

Bench-mounted fixture assists operator in winding toroid-shaped transformer cores. Toroid is rigidly held in place as wires are looped around. Arrangement frees both hands for rapid winding and untangling of wires that occurs when core is hand held.

Mclyman, M. T.↗
NASA NTRS1979

Harmonics of 60 Hz in power systems caused by geomagnetic disturbances

Simultaneous VLF/ULF observations carried out near Winnipeg, Manitoba show that geomagnetic disturbances control the behavior of harmonics of 60 Hz man-made electric power. The harmonics of 60 Hz detected by the VLF receiver are at multiples of 180 Hz, indicating that they originated from a 3 phase ac power system. Under geomagnetically quiet conditions, only odd harmonics of 70 Hz were detected. In disturbed conditions, both odd and even harmonics were excited. The strength of each harmonic changed concurrently with geomagnetic pulsation (ULF) activity. These findings seem to indicate that a portion of telluric currents shunted into the power line system through the neutrals of the Y-connected transformers give rise to a dc bias to the transformer core materials and that it distorts their hysteresis loops, activating harmonics of 60 Hz power. A mathematical proof is given that a hysteresis loop having a point of symmetry generates odd harmonics only, whereas loops lacking in point-symmetry generally give rise to both odd and even harmonics. A general formula was obtained to calculate the strength of each harmonic based on the shape of the hysteresis loop.

Hayashi, K.↗
NASA NTRS1982

Simple Magnetometer for Autopilots

Simple, low-cost magnetometer is suitable for heading-reference applications in autopilots and other directional control systems. Sensing element utilizes commercially available transformer core; and supporting electronics consist of one transistor, two readily-available integrated-circuit chips, and associated resistors and capacitors.

Garner, H. D.↗
NASA NTRS1990

Small, Lightweight Welding-Current Indicator

Welding-current indicator made of surface-mounted components on flexible circuit board. Holds variety of components on surface. After assembly, flexible circuit wrapped to fit around transformer core. Surface-mounted devices make it unnecessary to drill holes in circuit board to accommodate component leads. Use of small surface-mounted devices result in lightweight, compact indicator circuit.

Huston, Steven W.↗
NASA NTRS2002

Driving a quadrupole mass spectrometer via an isolating stage

Driving a quadrupole mass spectrometer includes obtaining an air core transformer with a primary and a secondary, matching the secondary to the mass spectrometer, and driving the primary based on first and second voltage levels. Driving of the primary is via an isolating stage that minimizes low level drive signal coupling.

Chutjian, Ara↗
NASA NTRS2003

Quadrupole mass spectrometer driver with higher signal levels

Driving a quadrapole mass spectrometer includes obtaining an air core transformer with a primary and a secondary, matching the secondary to the mass spectrometer, and driving the primary based on first and second voltage levels. Driving of the primary is via an isolating stage that minimizes low level drive signal coupling.

Chutjian, Ara↗
NASA NTRS2004

NASA Tech Briefs, May 2004

Topics include: Embedded Heaters for Joining or Separating Plastic Parts; Curing Composite Materials Using Lower-Energy Electron Beams; Aluminum-Alloy-Matrix/Alumina-Reinforcement Composites; Fibrous-Ceramic/Aerogel Composite Insulating Tiles; Urethane/Silicone Adhesives for Bonding Flexing Metal Parts; Scalable Architecture for Multihop Wireless ad Hoc Networks; Improved Thermoplastic/Iron-Particle Transformer Cores; Cooperative Lander-Surface/Aerial Microflyer Missions for Mars Exploration Dual-Frequency Airborne Scanning Rain Radar Antenna System Eight-Channel Continuous Timer Reduction of Phase Ambiguity in an Offset-QPSK Receiver Ambient-Light-Canceling Camera Using Subtraction of Frames Lightweight, Flexible, Thin, Integrated Solar-Power Packs Windows(Registered Trademark)-Based Software Models Cyclic Oxidation Behavior Software for Analyzing Sequences of Flow-Related Images Improved Ball-and-Socket Docking Mechanism Two-Stage Solenoid Ordered Nanostructures Made Using Chaperonin Polypeptides Low-Temperature Plasma Functionalization of Carbon Nanotubes Improved Cryostat for Cooling a Wide Panel Current Pulses Momentarily Enhance Thermoelectric Cooling Hand-Held Color Meters Based on Interference Filters Calculating Mass Diffusion in High-Pressure Binary Fluids Fresnel Lenses for Wide-Aperture Optical Receivers Increasing Accuracy in Computed Inviscid Boundary Conditions Higher-Order Finite Elements for Computing Thermal Radiation Radar for Monitoring Hurricanes from Geostationary Orbit Time-Transfer System for Two Orbiting Spacecraft

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