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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 1,027 records · Page 57

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NASA NTRS2014

Lunar Polar Environmental Testing: Regolith Simulant Conditioning

As ISRU system development approaches flight fidelity, there is a need to test hardware in relevant environments. Extensive laboratory and field testing have involved relevant soil (lunar regolith simulants), but the current design iterations necessitate relevant pressure and temperature conditions. Including significant quantities of lunar regolith simulant in a thermal vacuum chamber poses unique challenges. These include facility operational challenges (dust tolerant hardware) and difficulty maintaining a pre-prepared soil state during pump down (consolidation state, moisture retention).For ISRU purposes, the regolith at the lunar poles will be of most interest due to the elevated water content. To test at polar conditions, the regolith simulant must be doped with water to an appropriate percentage and then chilled to cryogenic temperatures while exposed to vacuum conditions. A 1m tall, 28cm diameter bin of simulant was developed for testing these simulant preparation and drilling operations. The bin itself was wrapped with liquid nitrogen cooling loops (100K) so that the simulant bed reached an average temperature of 140K at vacuum. Post-test sampling was used to determine desiccation of the bed due to vacuum exposure. Depth dependent moisture data is presented from frozen and thawed soil samples.Following simulant only evacuation tests, drill hardware was incorporated into the vacuum chamber to test auguring techniques in the frozen soil at thermal vacuum conditions. The focus of this testing was to produce cuttings piles for a newly developed spectrometer to evaluate. This instrument, which is part of the RESOLVE program science hardware, detects water signatures from surface regolith. The drill performance, behavior of simulant during drilling, and characteristics of the cuttings piles will be offered.

lunar regolith↗

NASA NTRS2014

Lunar Polar Environmental Testing: Regolith Simulant Conditioning

in situ resource utilization↗

NASA NTRSDate not supplied

SERFE Water Quality Results

NASA has been developing a new spacesuit, called the Exploration Extravehicular Mobility Unit (xEMU) for over a decade. This spacesuit is underdevelopment to support missions to the International Space Station (ISS) and also to the Moon. Improvements in the life and robustness of the Portable Life Support System (PLSS) has been a major objective of these efforts. Water quality, and how that impacts the performance of the life support system hardware, are areas where improvements could greatly help to achieve these goals. The Suit Water Membrane Evaporator (SWME) was chosen as the technology to provide cooling to the xEMU and has undergone several iterations of development over this period. An ISS flight experiment centered around the SWME and other thermal loop technologies was developed and has been under test in an ISS EXpedite PRocessing of Experiments to the Space Station (EXPRESS) rack since November of 2020. In addition to the SWME, The SWME EXPRESS Rack Flight Experiment (SERFE) contains several technology demonstrations from the xEMU project and has been demonstrating their performance in micro-gravity and over an extended duration. This paper will summarize the results of the water quality analysis performed to date throughout the SERFE testing program. Special care was taken to select materials, process hardware, and control the quality of the feedwater used in SERFE testing so that it would be representative of a thermal control system that could be used on a spacesuit for a lunar mission. In addition, the testing schedule, including periods of quiescence in between tests, was also selected to simulate a real mission profile in ways that would be critical to water quality. Results include data and analysis on microbial activity, biocidal iodine, metals, organic carbon, and several other customary indicators of water quality in an operational system. Testing spans over a year and a half of wetted life of the SERFE Flight Unit and the SERFE Ground Unit.

Colin Campbell↗

DOE OSTI2023

SLAC microresonator RF(SMuRF) electronics: A tone-tracking readout system for superconducting microwave resonator arrays

Here, we describe the newest generation of the SLAC Microresonator RF (SMuRF) electronics, a warm digital control and readout system for microwave-frequency resonator-based cryogenic detector and multiplexer systems, such as microwave superconducting quantum interference device multiplexers (μmux) or microwave kinetic inductance detectors. Ultra-sensitive measurements in particle physics and astronomy increasingly rely on large arrays of cryogenic sensors, which in turn necessitate highly multiplexed readout and accompanying room-temperature electronics. Microwave-frequency resonators are a popular tool for cryogenic multiplexing, with the potential to multiplex thousands of detector channels on one readout line. The SMuRF system provides the capability for reading out up to 3328 channels across a 4–8 GHz bandwidth. Notably, the SMuRF system is unique in its implementation of a closed-loop tone-tracking algorithm that minimizes RF power transmitted to the cold amplifier, substantially relaxing system linearity requirements and effective noise from intermodulation products. Here, we present a description of the hardware, firmware, and software systems of the SMuRF electronics, comparing achieved performance with science-driven design requirements. In particular, we focus on the case of large-channel-count, low-bandwidth applications, but the system has been easily reconfigured for high-bandwidth applications. The system described here has been successfully deployed in lab settings and field sites around the world and is baselined for use on upcoming large-scale observatories.

47 OTHER INSTRUMENTATION↗

DOE OSTI2022

On Stability of PQ-Controlled Grid-Following and Droop-Control Grid-Forming Inverters

In this paper, the nonlinearity impacts of PQ-control schemes and LCL filter parameter variations on the stability of grid-interactive inverters are studied under weak grid conditions. This work demonstrates that the control nonlinearity and parameter variations can cause unexpected instability at low power levels. This instability issue in the nominal operating range may occur under specific control parameters due to the shift of the low-frequency eigenvalues of PQ-controlled inverters. A full-order small-signal model for PQ-controlled inverters is applied to analyze this instability issue. Furthermore, the impacts of the droop coefficients on the stability of the droop-controlled grid-forming inverter are also investigated using the closed-loop inverter model. The findings are experimentally verified using a small-scale two-level 208 V, 5 kVA inverter feeding a 12 kW NHR 9410 power grid emulator and a hardware setup of a microgrid fed by two 5 kVA 208V inverters.

Hossen, Tareq↗

DOE OSTI2020

Low Size, Weight, and Power Neuromorphic Computing to Improve Combustion Engine Efficiency

Neuromorphic computing offers one path forward for AI at the edge. However, accessing and effectively utilizing a neuromorphic hardware platform is non-trivial. In this work, we present a complete pipeline for neuromorphic computing at the edge, including a small, inexpensive, low-power, FPGA-based neuromorphic hardware platform, a training algorithm for designing spiking neural networks for neuromorphic hardware, and a software framework for connecting those components. We demonstrate this pipeline on a real-world application, engine control for a spark-ignition internal combustion engine. We illustrate how we connect engine simulations with neuromorphic hardware simulations and training software to produce hardware-compatible spiking neural networks that perform engine control to improve fuel efficiency. We present initial results on the performance of these spiking neural networks and illustrate that they outperform open-loop engine control. We also give size, weight, and power estimates for a deployed solution of this type.

Schuman, Catherine↗

NASA NTRS2013

Improved Spacecraft Tracking and Navigation Using a Portable Radio Science Receiver

The Portable Radio Science Receiver (PRSR) is a suitcase-sized open-loop digital receiver designed to be small and easy to transport so that it can be deployed quickly and easily anywhere in the world. The PRSR digitizes, downconverts, and filters using custom hardware, firmware, and software. Up to 16 channels can be independently configured and recorded with a total data rate of up to 256 Mbps. The design and implementation of the system's hardware, firmware, and software is described. To minimize costs and time to deployment, our design leveraged elements of the hardware, firmware, and software designs from the existing full-sized operational (non-portable) Radio Science Receivers (RSR) and Wideband VLBI Science Receivers (WVSR), which have successfully supported flagship NASA deep space missions at all Deep Space Network (DSN) sites. We discuss a demonstration of the PRSR using VLBI, with one part per billion angular resolution: 1 nano-radian / 200 ?as synthesized beam. This is the highest resolution astronomical instrument ever operated solely from the Southern Hemisphere. Preliminary results from two sites are presented, including the European Space Agency (ESA) sites at Cebreros, Spain and Malargue, Argentina. Malargue's South American location is of special interest because it greatly improves the geometric coverage for spacecraft navigation in the Southern Hemisphere and will for the first time provide coverage to the 1/4 of the range of declination that has been excluded from reference frame work at Ka-band.

Delta Differential One-Way (DOR)↗

NASA NTRS1985

Hardware math for the 6502 microprocessor

A floating-point arithmetic unit is described which is being used in the Ground Facility of Large Space Structures Control Verification (GF/LSSCV). The experiment uses two complete inertial measurement units and a set of three gimbal torquers in a closed loop to control the structural vibrations in a flexible test article (beam). A 6502 (8-bit) microprocessor controls four AMD 9511A floating-point arithmetic units to do all the computation in 20 milliseconds.

Kissel, R.↗

DOE OSTI2020

Real-time optimization of multi-cell industrial evaporative cooling towers using machine learning and particle swarm optimization

Existing electrical generating stations must operate with greater flexibility due to increasing renewable energy penetration on the electrical grid, and many coal-fired power stations have transitioned away from baseload operation to load-following operation to aid in grid stability. In cases where multiple independently controlled cooling tower cells are used in parallel for the cooling purposes of such stations, there is an opportunity to increase plant efficiency through data-driven optimization across their full load ranges. This work presents a novel application of real-time optimization using machine learning and particle swarm optimization on a multi-cell induced-draft cooling tower servicing a coal-fired power station under variable load. This is the first work to demonstrate simultaneous optimization of a multi-cell cooling tower, in addition to using machine learning for closed-loop control on a cooling tower. A novel control configuration is presented that ensures original control logic is not adversely affected and that the overall plant process is not disrupted using only existing hardware and operational data. To verify this methodology, the 12 independent cooling tower cells are simulated in parallel using historic operating data to demonstrate the effectiveness of real-time optimization compared to current practice. An artificial neural network is trained to predict overall cooling tower power consumption using only operational data and ambient conditions with an R2 value of greater than 0.96. The real-time optimization using particle swarm yields 6.7% annual energy usage savings compared to current practices, although the extent of the real-time savings varies greatly with both plant load and environmental conditions. This is particularly significant for a variable load situation because frequent ramping typically results in reduced overall efficiency. Furthermore, this proposed AI-based solution presents an opportunity to improve the overall heat rate of a load-following coal-fired power plant without the need to perform extensive first-principles modeling or add additional hardware to the cooling tower, resulting in more resources conserved and less overall emissions per unit of electricity generated.

42 ENGINEERING↗

NASA NTRS1982

Serial MSK modem for the Advanced Communications Satellite Program

The design and test results of the 550-Mb/s, 110-Mb/s, and 27.5-Mb/s modems for the Advanced Communication Satellite Program are described. The TDMA/FDMA satellite environmental constraints have resulted in several unique features which include total acquisition times of 100 bit times and modem degradation of less than 1.5 dB at 10 to the -6th Pe. Key to the serial implementation of MSK is the resulting hardware simplicity and degradation insensitivity relative to conventionally implemented MSK and QPSK modems. The 110/27.5-Mb/s modems use an integrated circuit specifically developed for the program to perform the key carrier and clock-loop functions.

Stilwell, J. H.↗

NASA NTRS1988

The Mark III stellar interferometer

The Mark III interferometer is an operational long baseline stellar interferometer on Mt. Wilson with four-possible baseline configurations from 9m NE-SW to 20m N-S. The interferometer was designed to be a highly automated astronomical instrument to measure stellar positions and diameters to a magnitude limit of seven. Initial fringe observations were made in September 1986 with a 12-m N-S baseline. In the following months, semi-automated astrometric and stellar diameter measurements were also made. This paper describes the hardware and software components of the instrument and its operational characteristics. The interferometer has several novel features. One is the use of optimal estimation and control algorithms (e.g. Kalman filters) in the control loops. Another is the ability to operate both as a closed-loop phased interferometer and eventually as an open-loop or absolute coherent interferometer. High thermal stability and mechanical accuracy should permit the instrument to point blind at an astronomical object and maintain optical path equality to within the limits set by the atmosphere. In this absolute interferometric mode of operation, it should be possible to observe faint astronomical objects that are too dim for phase tracking. In theory, measurements of amplitude, group delay, and closure phase will be possible to 14 mag.

Shao, M.↗

NASA NTRS1988

A hardware implementation of a relaxation algorithm to segment images

Relaxation labelling is a mathematical technique frequently applied in image processing algorithms. In particular, it is extensively used for the purpose of segmenting images. The paper presents a hardware implementation of a segmentation algorithm, for images consisting of two regions, based on relaxation labelling. The algorithm determines, for each pixel, the probability that it should be labelled as belonging to a particular region, for all regions in the image. The label probabilities (labellings) of every pixel are iteratively updated, based on those of the pixel's neighbors, until they converge. The pixel is then assigned to the region correspondent to the maximum label probability. The system consists of a control unit and of a pipeline of segmentation stages. Each segmentation stage emulates in the hardware an iteration of the relaxation algorithm. The design of the segmentation stage is based on commercially available digital signal processing integrated circuits. Multiple iterations are accomplished by stringing stages together or by looping the output of a stage, or string of stages, to its input. The system interfaces with a generic host computer. Given the modularity of the architecture, performance can be enhanced by merely adding segmentation stages.

Loda, Antonio G.↗

NASA NTRS1993

The constant current loop: A new paradigm for resistance signal conditioning

A practical, single, constant-current loop circuit for the signal conditioning of variable-resistance transducers was synthesized, analyzed, and demonstrated. The strain gage and the resistance temperature device are examples of variable-resistance sensors. Lead wires connect variable-resistance sensors to remotely located signal-conditioning hardware. The presence of lead wires in the conventional Wheatstone bridge signal-conditioning circuit introduces undesired effects that reduce the quality of the data from the remote sensors. A practical approach is presented for suppressing essentially all lead wire resistance effects while indicating only the change in resistance value. Theoretical predictions supported by laboratory testing confirm the following features of the approach: (1) the dc response; (2) the electrical output is unaffected by extremely large variations in the resistance of any or all lead wires; (3) the electrical output remains zero for no change in gage resistance; (4) the electrical output is inherently linear with respect to gage resistance change; (5) the sensitivity is double that of a Wheatstone bridge circuit; and (6) the same excitation and sense wires can serve multiple independent gages. An adaptation of the current loop circuit is presented that simultaneously provides an output signal voltage directly proportional to transducer resistance change and provides temperature information that is unaffected by transducer and lead wire resistance variations. These innovations are the subject of NASA patent applications.

Anderson, Karl F.↗

NASA NTRS1994

The constant current loop: A new paradigm for resistance signal conditioning

A practical single constant current loop circuit for the signal conditioning of variable-resistance transducers has been synthesized, analyzed, and demonstrated. The strain gage and the resistance temperature detector are examples of variable-resistance sensors. Lead wires connect variable-resistance sensors to remotely located signal-conditioning hardware. The presence of lead wires in the conventional Wheatstone bridge signal-conditioning circuit introduces undesired effects that reduce the quality of the data from the remote sensors. A practical approach is presented for suppressing essentially all lead wire resistance effects while indicating only the change in resistance value. Theoretical predictions supported by laboratory testing confirm the following features of the approach: (1) dc response; (2) the electrical output is unaffected by extremely large variation in the resistance of any or all lead wires; (3) the electrical output remains zero for no change in gage resistance; (4) the electrical output is inherently linear with respect to gage resistance change; (5) the sensitivity is double that of a Wheatstone bridge circuit; and (6) the same excitation wires can serve multiple independent gages. An adaptation of current loop circuit is presented that simultaneously provides an output signal voltage directly proportional to transducer resistance change and provides temperature information that is unaffected by transducer and lead wire resistance variations. These innovations are the subject of NASA patent applications.

Anderson, Karl F.↗

NASA NTRS1962

RENDEZVOUS AND DOCKING TECHNIQUES

To implement the primary space mission of this decade – manned lunar exploration -- the operational assistance of rendezvous and docking is being considered as an alternative to possible problems in obtaining a boost vehicle capable of direct flight. This paper concentrates on the mechanization of the rendezvous and docking phase of such a lunar mission. As indicated in previous papers, rendezvous can take place in either an earth or lunar orbit (or on the lunar surface); it can involve the mating of stages, transfer of fuel, or the return of a shuttle to a “mother” ship; direct ascent or parking orbits can be used; the orbits can be circular or more general ellipses; finally, either or both of the spacecraft can participate in the rendezvous maneuvers. Since there is no intent here to discuss the pros and cons of each approach or to cover all possible mission profiles, guidance schemes and hardware configurations, one particular profile has been selected to display the significant features of most rendezvous missions. In many respects, rendezvous is less difficult than aircraft interception since the target is friendly and there is no severe time constraint. The latter feature allows considerable freedom of design especially with the great versatility of a human in the loop. This remains true even for a purely automatic mode. Perhaps the largest design problem concerns the selection of the mission to be implemented followed by the optimization or systems engineering of a mechanization from the multitude of possible schemes and techniques. A most important factor in the optimization is that of reliability and the redundancy, alternate or backup modes, etc., associated with the approach. While a primary system can be rather easily mechanized with modest equipment requirements, reliability considerations will result in additional hardware, tighter specifications and more safety factors (e. g., propellant margin). This is a very complex area and will only briefly be mentioned in the following discussion.

Rendezvous↗

DOE OSTI2025

Hardware-Based Demonstration of Temperature Control Functions for Reactor Systems

Establishing autonomy in reactor control systems has become essential for the expansion of nuclear technologies. Thermal regulation in particular remains crucial for maintaining stable operation and ensuring the integrity of fuel. To alleviate public skepticism of the safety of nuclear reactors, demonstrating control over this key factor is pivotal. Utilizing electric heat pads to simulate the heat released in a reactor core, thermocouples for temperature monitoring, and an Arduino micro programmable logic controller (PLC) for control, a hardware-based demonstration of a reactor heating system validates the efficacy of reactor control over this key parameter. To improve precision, a proportional-integral-derivative (PID) algorithm was implemented in the heating control loop to ensure meticulous control of reactor functions. In addition, the integration of this physical system with a digital simulator tool such as RELAP5-3D establishes a foundation for a comprehensive testing environment. This allows for a refinement of temperature control under various simulated reactor conditions, bringing another layer of reliability to the operation of the system. By facilitating a physical demonstration of reactor thermal management and control strategies, this project provides a foundation for expanded testing and educational outreach. Ultimately, this system advances the broader goal of demonstrating the safety and viability of autonomous reactor operations, contributing to public trust and future reactor deployment.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

NASA NTRS1992

A digitally implemented modem - Theory and emulation results

Theory and hardware emulation results are presented for a very flexible digitally implemented modem whose technology is useful over a broad class of terrestrial and in-flight satellite communications applications. The interdependent detection and tracking loop architectures based on the 'joint estimator-detector' approach is shown to perform well for various modulation techniques. The analysis is accurate in setting the loop parameters, and also predicting their transient behavior.

Poklemba, John J.↗

NASA NTRS1981

Solar Power Satellite antenna phase control system hardware simulation, phase 4. Volume 2: Analytical simulation of SPS system performance

The pilot signal parameter optimization and power transponder analyses are presented. The SPS antenna phase control system is modeled and the hardware simulation study described. Ionospheric and system phase error effects and the effects of high power amplifier phase and amplitude jitters are considered. Parameter optimization of the spread spectrum receiver, consisting of the carrier tracking loop and the code tracking loop, is described.

Lindsey, W. C.↗