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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS2023

Leveraging Automated Fiber Placement Computer Aided Process Planning Framework for Defect Validation and Dynamic Layup Strategies

Process planning represents an essential stage of the Automated Fiber Placement (AFP) workflow. It develops useful and efficient machine processes based upon the working material, composite design, and manufacturing resources. The current state of process planning requires a high degree of interaction from the process planner and could greatly benefit from increased automation. Therefore, a list of key steps and functions are created to identify the more difficult and time-consuming phases of process planning. Additionally, a set of metrics must exist by which to evaluate the effectiveness of the manufactured laminate from the machine code created during the Process Planning stage. Layup strategies, in addition to dog ears, stagger shifts, steering constraints, and starting points, represented the group of functions labeled as process optimization and ranked the highest in terms of priority for automation. The laminates resulting from the selected parameters are evaluated through the occurrences of principal defect metrics such as fiber gaps, overlaps, angle deviation and steering violations. This document presents an automated software solution to the layup strategy and starting point selection phase of process planning. A series of ply scenarios are generated with variations of these ply parameters and evaluated according to a set of metrics entered by the Process Planner. These metrics are generated through use of the Analytical Hierarchy Process (AHP), where relative importance between each of the fiber features are defined. The ply scenarios are selected which reduce the overall fiber feature scores based on the defects the Process Planner wishes to minimize.

HiCAM↗
NASA NTRSDate not supplied

On the Notional Impact of Background Noise on the Human Response to UAVs

Proponents of UAV-based industries would like to think that their aircraft will be incapable of causing annoyance (among other negative responses) in the communities that they serve due to the noise of their vehicles simply not being heard over the existing soundscape. No measures of noise that are in wide use today for aviation take background sound into consideration, and thus would not predict this outcome. This work is an attempt to bridge this gap by looking at past results from psychoacoustic research in which background sounds appear to play a significant role (not just for aviation sources). It includes information on the problem of human auditory detection in general – what is the transductive mechanism of the ear, how does one quantify detectability, etc., and it attempts to make the connection between detectability and annoyance. A notional schematic version of how measures/predictions of these two aspects may be incorporated into a single assessment of noise is given. Overall, detectability is shown to be very complex to predict relative to conventional noise metrics that are used to correlate with human response. Given this, the outlook for the use of measures of detectability in scientific, industrial, and regulatory applications is discussed.

UAV↗
NASA NTRSDate not supplied

Bone Conduction Headphone Research and Human-in-the-Loop Test Results

The new space suit being developed for exploration EVAs on the surface of the Moon and in microgravity environments is called xEMU. A government reference model had been developed and had undergone testing. This suit contains new upgrades from the current EMU on ISS, such as integrated speakers and microphones, eliminating the need for astronauts to wear a Communications Carrier Assembly (CCA) on their head during spacewalks. However, upon testing, it was noticed that this feature causes acoustic coupling, that results in communications echo and feedback. A proposed solution to this issue is to have the astronaut wear a bone conduction headset for audio capabilities while on EVA to receive incoming voice communications from Mission Control and other EVA or IVA crew members. This would eliminate the acoustic coupling and echo effect while being more ergonomically sound than the current CCA and leave the ear open to suit ambient sound for situational awareness. A human-in-the-loop evaluation was performed, comparing five commercially available bone conduction headsets, to evaluate comfort, fit, and adjustability for long-duration wear. Five engineering test subjects with different head sizes were utilized to wear the headsets for six hours and provide succinct feedback and score the headsets on a variety of factors, to help determine which of the headsets performed the best and could advance to future bone conduction audio testing. Three of the headsets were well-received among the diverse group of subjects, and at least one of these will advance to further testing to be considered for future use under the xEMU helmet for exploration EVAs. Rating results and evaluation methods for this bone conduction headset evaluation will be presented.

Bridget M Cavanaugh↗
NASA NTRSDate not supplied

xEMU Suit Integrated Audio Communications System: Ambient and EVA Pressure Testing System Performance

Testing across several airlock and EVA thermal and pressure scenarios has demonstrated that the Integrated Audio System of NASA’s Exploration Extravehicular Mobility Unit (xEMU) spacesuits transmits and receives intelligible audio communications without the use of a commcap or similar worn device. The xEMU audio system consists of internal loudspeakers and digital microphones (Integrated Communications System –ICS) combined with an adaptive Acoustic Echo Canceller (AEC), outbound voice operated transmission (VOX), and automatic gain control (AGC). Transducers are mounted in an “exploded commcap” configuration with helmet-attached speakers near the ears and three microphones positioned at the collar. The AGC removes inbound audio signals (e.g.,suit, Mission Control, Lander, C&W tones) from the outbound comms stream, reducing echo and feedback (squeal) in low-noise suit environments. The reduction of worn communication equipment increases crewmember comfort, range of movement, and situational awareness. However, test results also highlight the need for proper fan, duct, pump, and gas flow integration with suit acoustics and audio. Ductwork may serve as waveguides for various component and structure-borne noise. Sharply angled ducts can generate turbulent-flow noise. Gas flow from inlets above the crewmember’s head can generate noise when cascading over the faceplate and collar (or commcap) microphones. Sufficient acoustic noise levels (1) require increased gain to boost inbound audio, and (2) may distort signals resulting in AEC disruption or artifacts. Suit-noise levels decline with reduced pressure (density), but then elevated speech and audio effort/power become necessary. Whether the Integrated Audio System, commcap, or other device is used, suit acoustic noise can mask speech in outbound comms. This reduces intelligibility and requires other AECs/devices to suppress comms noise. Yet, adjusting a few components may yield significant improvement. We discuss xEMU audio functionality, demonstrate how acoustical treatment combined with inbound signal conditioning improved clarity during tests, and discuss future modifications.

xEMU↗
NASA NTRS2024

Bone Conduction Headphone Research and Testing for xEMU Communications Applications

The new space suit being developed for exploration EVAs on the surface of the Moon and in microgravity environments is referred to as xEMU. A government reference model had been developed and has undergone extensive functional and environmental testing. This suit contains new upgrades from the current EMU on ISS, such as integrated speakers and microphones, eliminating the need for astronauts to wear a Communications Carrier Assembly (CCA) on their heads during spacewalks. However, this design approach results in speaker-to-microphone acoustic coupling and communications echo and feedback. A proposed solution to this issue is to replace the integrated open speakers with an astronaut worn bone conduction headset for audio capabilities while on EVA to receive incoming voice communications from Mission Control and other EVA or IVA crew members. This would eliminate the acoustic coupling and echo effect while being more ergonomically sound than the current CCA and leave the ear open to suit-ambient sound for situational awareness. A human-in-the-loop evaluation was performed, comparing five commercially available bone conduction headsets, to evaluate comfort, fit, and adjustability for long-duration wear. Five engineering test subjects with different head sizes were utilized to wear the headsets for six hours and provide succinct feedback and score the headsets on a variety of factors, to help determine which of the headsets performed the best and could advance to future bone conduction audio testing. Three of the headsets were well-received among the diverse group of subjects, and at least one of these will advance to further testing to be considered for future use under the xEMU helmet for exploration EVAs. Rating results and evaluation methods for this bone conduction headset evaluation will be presented.

Bridget Cavanaugh↗
NASA NTRSDate not supplied

xEMU Suit Integrated Audio Communications System: Ambient and EVA Pressure Testing System Performance

Testing across several airlock and EVA thermal and pressure scenarios has demonstrated that the Integrated Audio System of NASA’s Exploration Extravehicular Mobility Unit (xEMU) spacesuits transmits and receives intelligible audio communications without the use of a commcap or similar worn device. The xEMU audio system consists of internal loudspeakers and digital microphones (Integrated Communications System –ICS) combined with an adaptive Acoustic Echo Canceller (AEC), outbound voice operated transmission (VOX), and automatic gain control (AGC). Transducers are mounted in an “exploded commcap” configuration with helmet-attached speakers near the ears and three microphones positioned at the collar. The AGC removes inbound audio signals (e.g.,suit, Mission Control, Lander, C&W tones) from the outbound comms stream, reducing echo and feedback (squeal) in low-noise suit environments. The reduction of worn communication equipment increases crewmember comfort, range of movement, and situational awareness. However, test results also highlight the need for proper fan, duct, pump, and gas flow integration with suit acoustics and audio. Ductwork may serve as waveguides for various component and structure-borne noise. Sharply angled ducts can generate turbulent-flow noise. Gas flow from inlets above the crewmember’s head can generate noise when cascading over the faceplate and collar (or commcap) microphones. Sufficient acoustic noise levels (1) require increased gain to boost inbound audio, and (2) may distort signals resulting in AEC disruption or artifacts. Suit-noise levels decline with reduced pressure (density), but then elevated speech and audio effort/power become necessary. Whether the Integrated Audio System, commcap, or other device is used, suit acoustic noise can mask speech in outbound comms. This reduces intelligibility and requires other AECs/devices to suppress comms noise. Yet, adjusting a few components may yield significant improvement. We discuss xEMU audio functionality, demonstrate how acoustical treatment combined with inbound signal conditioning improved clarity during tests, and discuss future modifications.

xEMU↗
NASA NTRS2024

Infrascope: Full-Spectrum Phonocardiography With Automated Signal Analysis Report

Physicians have used the stethoscope to listen to heart sounds for over 150 years. During this time the stethoscope has remained nearly unchanged. While the device is inexpensive, simple and easy to use, it has shortcomings as a diagnostic tool. It is dependent on human hearing to detect the complex sounds made by the heart, and human memory to analyze them. There also has been a significant decline in the use of stethoscope, at least in part because of the availability of technologies such as the echocardiogram, which can provide imaging and blood flow through the heart chambers. However, echocardiography can be complex, costly and time consuming and requires the need for a specialist, all of which delay the diagnosis and increase the cost of patient evaluation. Even with the availability of echocardiogram devices such as the handheld pocket ultrasound, diagnosing heart problems can still be difficult. The Infrascope is a new device that resembles a traditional stethoscope and is simple to use. In addition, the Infrascope offers greater sensitivity and a wider range of frequencies heard by the human ear, <20Hz than a traditional stethoscope can detect. Through automated analysis of the full spectrum of heart sounds, it has the potential to improve diagnostic accuracy while reducing the need for referrals, allowing primary care physicians to practice better medicine at the bedside.

Infrasounds↗
DOE OSTI2021

Using Qualified On-Site Nuclear Power Plant Simulators in Human Factors Validations of Control Room Upgrades

Existing commercial nuclear power plants (NPPs) are valuable assets in the infrastructure portfolio of the United States (U.S.) because they safely and reliably generate about 1/5th of all the electricity used. The instrumentation and control (I&C) systems in commercial NPPs are the ‘eyes and ears' of the operator, allowing operators to maintain situation awareness, thereby allowing the plant to operate safely and efficiently for all phases of operation. Because the I&C systems in NPPs are still mostly based on analog technologies, which are reliable but not especially cost-effective, upgrading the existing I&C in com-mercial NPPs to new digital I&C is very important. Furthermore, simulators and simulation are critical human factors engineering tools for this I&C modernization work. NPP control room simulators are essential test beds to simulate normal, abnormal, and emergency operations that allow human factors researchers to safely and realistically evaluate early design phase prototypes of the upgraded digital I&C, and validate final as-built digital I&C systems that have been modernized deployed in NPPs. This paper describes research performed using qualified on-site NPP simulators to perform human factors validations of digital I&C control room upgrades.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2023

Probabilidad de que los murcielagos sufran barotraumatismo cerca de palas de aerogeneradores en movimiento (Spanish)

In October 2018, the International Energy Agency Wind Task 34 - Working Together to Resolve the Environmental Effects of Wind Energy (WREN) - organized a virtual forum to discuss the likelihood of bats experiencing barotrauma when flying near moving wind turbine blades. The forum included experts in bat biology and physiology, bat and wind turbine interactions, wind turbine technology, and atmospheric sciences. This educational brief summarizes the discussion during the forum and written comments from those who could not attend. Relevant literature was used to provide additional context when needed. Possible explanations regarding the direct cause of bat mortality at operating wind turbines are (1) blunt force trauma caused by turbine blades striking individual bats, often referred to as collisions, and (2) barotrauma, resulting from exposure to pressure changes located near the surface of moving wind turbine blades. While collision- related mortality is easily understood, the mechanism causing barotrauma is more complex. Fast-moving wind turbine blades create regions of high- and low-pressure variations along the blade surfaces. If bats fly within these regions, the rapid change in pressure may cause internal bleeding, damage to lungs or other organs, and damage to the inner ear. However, sufficient data demonstrating barotrauma as a common cause of bat mortality at wind turbines are lacking. Moreover, the pressure variation necessary to cause barotrauma in bats is so close to the surface of turbine blades that there is a higher probability of direct contact with the blades than of solely experiencing barotrauma. Regardless of the cause, bats are interacting with fast-moving wind turbine blades, and these interactions are resulting in fatalities. Resolving this issue will require a better understanding of bat behavior and cost-effective measures to reduce interactions between bats and wind turbines. This is the Spanish translation of NREL/FS-5000-84749, "The Likelihood of Bats Experiencing Barotrauma Near Moving Wind Turbine Blades."

barotrauma↗
DOE OSTI2025

A Brief Survey on High Performance Computing Systems Power Management

This paper provides a survey of software-based power management techniques in High Performance Computing (HPC) systems. Seven existing power management and monitoring tools and frameworks are discussed. These are: Variorum, dynamic energy-performance optimizer (DEPO), Powersched, Bull Dynamic Power Optimizer (BDPO), Energy Aware Runtime (EAR), Global Extensible Open Power Manager (GEOPM), and PoLiMEr. Each of these tools is evaluated based on hardware abstraction, optimization methods, usability, and experimental validation. This survey highlights the diversity of approaches in managing energy efficiency, from vendor-neutral APIs to algorithm-driven power capping, and dynamic frequency adjustments. Given that energy requirements for large computational systems is increasing quickly, the importance of integrating these tools into existing HPC environments and the need for further research in this rapidly evolving field is also discussed.

97 - MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Morphology and composition of Goldeye (Hiodontidae; Hiodon alosoides) otoliths

In this work, we provide up-todate morphological and compositional data on otoliths of the osteoglossomorph Goldeye (Hiodon alosoides). Using computed tomography (CT) X-ray, we documented the location of each of the three pairs of otoliths (lapilli, sagittae, and asterisci) in relation to the swim bladder, which extended forward in close proximity to the sagittae and asterisci. The lappili were the largest otoliths in terms of surface area and volume, but the sagittae were highly modified, appearing spiral in shape when viewed dorsally, with a surface area to volume ratio more than double that of the lapilli. Using scanning electron microscopy, the surface of each otolith was viewable in great detail, and small otoconia (~10.5 μm diameter) were observed on each, but were most numerous on the sagittae. Additionally, on scanning electron micrographs, the sagittae appeared to be bi-lobed, with asymmetrical lobes each oriented in the same general direction. Using neutron and X-ray diffraction methods, we found three polymorphs of calcium carbonate crystals (aragonite, vaterite, and calcite), sometimes all within the same otolith. However, in general, lapilli and sagittae were composed predominately of aragonite whereas asterisci were composed chiefly of vaterite. With these results, we provide information on a unique species, whose inclusion in future studies would benefit our understanding of fish hearing, fish evolution, and fisheries ecology.

59 BASIC BIOLOGICAL SCIENCES↗