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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

NASA Tech Briefs, March 2006

Topics covered include: Medical Signal-Conditioning and Data-Interface System; Instruments for Reading Direct-Marked Data-Matrix Symbols; Processing EOS MLS Level-2 Data; Ground Processing of Data From the Mars Exploration Rovers; Estimating Total Electron Content Using 1,000+ GPS Receivers; NASA Solar Array Demonstrates Commercial Potential; Improved Control of Charging Voltage for Li-Ion Battery; Programmable Pulse-Position-Modulation Encoder; Wavelength-Agile External-Cavity Diode Laser for DWDM; Pattern-Recognition Processor Using Holographic Photopolymer; Submicrosecond Power-Switching Test Circuit; Three-Function Logic Gate Controlled by Analog Voltage; Integrated System for Autonomous Science; Montage Version 3.0; Utilizing AI in Temporal, Spatial, and Resource Scheduling; Satellite Image Mosaic Engine; Architecture for Control of the K9 Rover; HFGMC Enhancement of MAC/GMC; Automated Activation and Deactivation of a System Under Test; Cleaning Carbon Nanotubes by Use of Mild Oxygen Plasmas; Generating Aromatics From CO2 on Mars or Natural Gas on Earth; Attaching Thermocouples by Peening or Crimping; Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates; Generating Breathable Air Through Dissociation of N2O; High-Performance Scanning Acousto-Ultrasonic System; Correction for Thermal EMFs in Thermocouple Feedthroughs; Using Quasiparticle Poisoning To Detect Photons; Estimating Resolution Lengths of Hybrid Turbulence Models; Education and Training Module in Alertness Management; Cargo-Positioning System for Next-Generation Spacecraft; Micro-Imagers for Spaceborne Cell-Growth Experiments; Holographic Solar Photon Thrusters; Plasma-Based Detector of Outer-Space Dust Particles; and Generation of Data-Rate Profiles of Ka-Band Deep-Space Links.

Source record↗
NASA NTRS2012

High fidelity, radiation tolerant analog-to-digital converters

Techniques for an analog-to-digital converter (ADC) using pipeline architecture includes a linearization technique for a spurious-free dynamic range (SFDR) over 80 deciBels. In some embodiments, sampling rates exceed a megahertz. According to a second approach, a switched-capacitor circuit is configured for correct operation in a high radiation environment. In one embodiment, the combination yields high fidelity ADC (>88 deciBel SFDR) while sampling at 5 megahertz sampling rates and consuming <60 milliWatts. Furthermore, even though it is manufactured in a commercial 0.25-.mu.m CMOS technology (1 .mu.m=12.sup.-6 meters), it maintains this performance in harsh radiation environments. Specifically, the stated performance is sustained through a highest tested 2 megarad(Si) total dose, and the ADC displays no latchup up to a highest tested linear energy transfer of 63 million electron Volts square centimeters per milligram at elevated temperature (131 degrees C.) and supply (2.7 Volts, versus 2.5 Volts nominal).

Wang, Charles Chang-I↗
DOE OSTI2025

Development and Testing of a new Current-Regulated Arc Modulator for the LINAC

In this study, the performance of a current-regulated arc modulator was investigated with a focus on its role in initiating and sustaining plasma discharge within the Magnetron Body of the LINAC system. The analysis centered on how switching components, circuit topology, and feedback loop architecture influence critical factors such as energy efficiency, discharge stability, and long-term plasma containment. Particular attention was given to variations in pulse termination behavior, as observed through oscilloscope traces, which revealed inconsistencies affecting the duty factor and cathode temperature. These fluctuations have downstream effects on the cesium-coated cathode surface, thereby impacting H⁻ ion production and beam reliability. Simulation-based testing in LTspice was used to evaluate noise suppression techniques and arc current regulation schemes, revealing how optimized snubber networks, improved pulse shaping, and feedback stability can mitigate modulator-induced noise. The results identified hardware level parameters that significantly enhance discharge repeatability and improve overall plasma performance under operational conditions.

Campos, Nathan [Unlisted, US; Fermilab]↗
NASA NTRSDate not supplied

Passive PCB Mounted Thermal Switch

A printed circuit board (PCB) generates heat during operation. In a vacuum this heat can only be rejected by conduction and radiation. To reject heat effectively and avoid overheating, the PCB needs to be thermally conductive to the electronics enclosure. However, if the system rejects too much heat, or not enough heat, either can result in system failure. The thermal switch will be able to regulate the amount of heat the system rejects to stay within the operational temperature range.

Jarret Bone↗
NASA NTRSDate not supplied

Passive PCB Mounted Thermal Switch

A printed circuit board (PCB) generates heat during operation. In a vacuum this heat can only be rejected by conduction and radiation. In order to reject heat effectively the PCB needs to be thermally conductive to the electronics enclosure. However, when the enclosure temperature gets too low, too much heat is rejected from the PCB and it can fail. This thermal switch has been designed to allow for heat rejection when the PCB is sufficiently warm but then greatly reduce heat rejection when the temperature gets low enough.

Jarret Bone↗
DOE OSTI2020

Integrative Circuit-Host Modeling of a Genetic Switch in Varying Environments

Synthetic biology is advancing into a new phase where real-world applications are emphasized. There is hence an urgent need for mathematical modeling that can quantitatively describe the behaviors of genetic devices in natural, fluctuating environments. We utilize an integrative circuit-host modeling framework to examine the dynamics of a genetic switch and its host cell in varying environments. For both steady-state and transient cases, we find increasing nutrient reduces the bistability region of the phase space and eventually drives the switch from bistability to monostability. In response, cellular growth and proteome partitioning experience the same transition. Antibiotic perturbations cause the similar circuit and host responses as nutrient variations. However, one difference is the trend of growth rate, which augments with nutrient but declines with antibiotic levels. The framework provides a mechanistic scheme to account for both the dynamic and static characteristics of the circuit-host system upon environmental perturbations, underscoring the intimacy of gene circuits and their hosts and elucidating the complexity of circuit behaviors arising from environmental variations.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

A nonlinear interface integrated lever mechanism for piezoelectric footstep energy harvesting

Harnessing footstep energy allows for a unique method of power generation from a largely untapped resource, with applications such as instantly charging mobile and wearable electronic devices. This letter presents an easily integrated heel charger to efficiently convert kinematic walking energy into electricity. The heel charger uses a multilayered levered piezoelectric (L-Pie) mechanism associated with a nonlinear mechanical-synchronized switching on inductor circuit (M-SSHI) interface. It tactfully switches on when the foot contacts the ground, and switches off when the foot is lifted. This design takes full advantage of the user's weight, and amplifies footstep displacement by utilizing the lever mechanism to gain maximum deformation of multilayer piezoelectric patches. The experimental results show that the fabricated two-level multilayer L-pie has a top performance of 13.60 mW of AC RMS, a mechanical to AC power conversion efficiency of 7.87%, and a DC RMS power of 6.13 mW, an AC to DC power conversion efficiency of 45.07%, under a harmonic excitation of 2.3 Hz (mimicking fast walking speed: 6.2 km/h for men, 5.55 km/h for women). With an optimal load of 210 kΩ, the two-level L-pie using the M-SSHI has an improvement of 206.45% in DC RMS power compared to a standard 4-diode bridge energy harvesting circuit. Finally, the L-pie design works more efficiently under large force excitation, even with small displacement, which makes this technology optimal for footstep energy harvesting.

42 ENGINEERING↗
DOE OSTI2015

Method and apparatus for sub-hysteresis discrimination

Embodiments of comparator circuits are disclosed. A comparator circuit may include a differential input circuit, an output circuit, a positive feedback circuit operably coupled between the differential input circuit and the output circuit, and a hysteresis control circuit operably coupled with the positive feedback circuit. The hysteresis control circuit includes a switching device and a transistor. The comparator circuit provides sub-hysteresis discrimination and high speed discrimination.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1990

Preventing Simultaneous Conduction In Switching Transistors

High voltage spikes and electromagnetic interference suppressed. Power-supply circuit including two switching transistors easily modified to prevent simultaneous conduction by both transistors during switching intervals. Diode connected between collector of each transistor and driving circuit for opposite transistor suppresses driving signal to transistor being turned on until transistor being turned off ceases to carry current.

Mclyman, William T.↗
NASA NTRS2013

A Nanostructured Composites Thermal Switch Controls Internal and External Short Circuit in Lithium Ion Batteries

A document discusses a thin layer of composite material, made from nano scale particles of nickel and Teflon, placed within a battery cell as a layer within the anode and/or the cathode. There it conducts electrons at room temperature, then switches to an insulator at an elevated temperature to prevent thermal runaway caused by internal short circuits. The material layer controls excess currents from metal-to-metal or metal-to-carbon shorts that might result from cell crush or a manufacturing defect

McDonald, Robert C.↗
DOE OSTI2019

Efficient IGBT switching

Embodiments of the invention provide IGBT circuit modules with increased efficiencies. These efficiencies can be realized in a number of ways. In some embodiments, the gate resistance and/or voltage can be minimized. In some embodiments, the IGBT circuit module can be switched using an isolated receiver such as a fiber optic receiver. In some embodiments, a single driver can drive a single IGBT. And in some embodiments, a current bypass circuit can be included. Various other embodiments of the invention are disclosed.

42 ENGINEERING↗
DOE OSTI2021

Efficient IGBT switching

Embodiments of the invention provide IGBT circuit modules with increased efficiencies. These efficiencies can be realized in a number of ways. In some embodiments, the gate resistance and/or voltage can be minimized. In some embodiments, the IGBT circuit module can be switched using an isolated receiver such as a fiber optic receiver. In some embodiments, a single driver can drive a single IGBT. And in some embodiments, a current bypass circuit can be included. Various other embodiments of the invention are disclosed.

Ziemba, Timothy↗
DOE OSTI2024

Efficient IGBT switching

Embodiments of the invention provide IGBT circuit modules with increased efficiencies. These efficiencies can be realized in a number of ways. In some embodiments, the gate resistance and/or voltage can be minimized. In some embodiments, the IGBT circuit module can be switched using an isolated receiver such as a fiber optic receiver. In some embodiments, a single driver can drive a single IGBT. And in some embodiments, a current bypass circuit can be included. Various other embodiments of the invention are disclosed.

Ziemba, Timothy↗
NASA NTRS1992

Method of characterizing residual stress in ferromagnetic materials using a pulse histogram of acoustic emission signals

The invention is a method and apparatus for characterizing residual uniaxial stress in a ferromagnetic test member by distinguishing between residual stresses resulting from positive (tension) forces and negative (compression) forces by using the distinct and known magnetoacoustic (MAC) and a magnetoacoustic emission (MAE) measurement circuit means. A switch permits the selective operation of the respective circuit means.

Namkung, Min↗
DOE OSTI2019

In-situ active impedance characterization of scanned array antennas

Various embodiments presented herein relate to determining mutual coupling between a pair of antennas in an array antenna. Various operations presented herein enable comparison between a magnitude and phase of a signal transmitted from a first feed network (via a first antenna) and a magnitude and phase of a portion of the signal received at a second feed network (via a second antenna). Electrical effects engendered by any of the first feed network, a first switch, a first local circuit, the second feed network, a second switch, and a second local circuit can also be determined and their effects mathematically removed. Based upon the foregoing, a mutual coupling between the pair of antenna is determined.

42 ENGINEERING↗