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At least 253 records · Page 14

Time delays in flight simulator visual displays

It is pointed out that the effects of delays of less than 100 msec in visual displays on pilot dynamic response and system performance are of particular interest at this time because improvements in the latest computer-generated imagery (CGI) systems are expected to reduce CGI displays delays to this range. Attention is given to data which quantify the effects of display delays in the range of 0-100 msec on system stability and performance, and pilot dynamic response for a particular choice of aircraft dynamics, display, controller, and task. The conventional control system design methods are reviewed, the pilot response data presented, and data for long delays, all suggest lead filter compensation of display delay. Pilot-aircraft system crossover frequency information guides compensation filter specification.

Crane, D. F.↗

Soil texture and granulometry at the surface of Mars

Attention is given to a characterization of the physical behavior of the Martian upper surface in its first few decimeters on the basis of mutual relationships between three parameters: the linear polarization of the reflected light, the visual albedo, and the thermal inertia. Polarimetric scans raked a strip covering two contrasting regions, the dark-hued Mare Erythraeum, and the light-hued Thaumasia. Erythraeum is characterized everywhere by a uniform polarization response, despite the large geomorphological diversity of the surface. A ubiquitous coating or mantling with small dark grains of albedo 12.7 percent, with a radius of 10 to 20 microns, is indicated. Thaumasia exhibits a large variety of soil properties. A typical location with albedo of 16.3 percent has a surface covered with orange grains, probably very dispersed in size, for which the largest grains are 20 to 40 microns.

Dollfus, Audouin↗

Capturing, Analyzing, Maintaining, and Disseminating Shape Memory Material Data Between Information Management Systems

With an increased demand on reducing the time, cost, and effort to develop new materials, Integrated Computational Materials Engineering (ICME) has received widespread attention in various engineering disciplines as a catalyst for significantly reducing experimental testing during the material design process. An ICME approach to design can enable ‘fit-for-purpose’ materials to be realized in engineering applications by incorporating well-understood process-property-performance relationships between the various length and time scales in a material’s structure, enabling material optimization. However, such an approach requires validated multiscale models at the various length scales for a material, which in turn requires a large amount of data, a robust means of storing the data, and the ability to link data to developed material models. The NASA Vision 2040 [1] has identified nine key elements to enabling ICME approaches in system level design, with one being “Data, Information, and Visualization”, thus outlining the importance of a robust information management system for ICME. As the relationship between microstructure, properties, and material performance become better understood and incorporated into multiscale models that can be leveraged in application design, the emergence of new materials with application-driven properties can be realized. One such new material class that has seen growing attention are shape memory materials (SMM), in which a material can transition between a deformed and undeformed state via a reversible phase transformation when subject to a thermal, mechanical, or magnetic load [2]. SMMs have been used widely in aerospace and biomedical industries, including applications such as actuators, low-shock mechanisms, medical staples, braces, and stents [3, 4]. These materials exhibit unique behavior due to their ability to transition between phases, and thus the mechanisms that enable this transition must be captured in a data information management system and incorporated into SMM material models. At NASA Glenn Research Center, the Shape Memory Materials Database (SMMD) Tool has been developed to capture the necessary information that governs SMM material behavior and provide users the ability to select and visualize various SMMs for a specific application [5]. The database contains point-wise data for published SMM materials, along with the pedigree metadata for traceability necessary for a robust information management system. The database is also capable of storing in-house test data performed at NASA GRC by interacting with the developed Shape Memory Alloy (SMA) Analytics tool to extract the necessary point-wise values and populate the database. Although the SMMD Tool offers its users a single, authoritative source for SMM material data that is critical for model development and material design, the full material pedigree of the in-house test data for SMMs is not currently captured and is out of the scope for the SMMD tool. In this work, the schema for capturing SMM test data within the larger NASA GRC ICME Schema [6, 7, 8, 9] will be developed and implemented for thermomechanical tests conducted at NASA GRC. The developed schema will not only store the relevant data needed for the SMMD tool, but also the material pedigree (i.e., production of the bulk material, bulk material analysis, sample cut-out diagrams, sample fabrication procedure, etc.), test pedigree (i.e., test equipment used, measurement systems used, raw test data), and analysis pedigree (i.e., how the data in the SMMD tool is calculated). Furthermore, a Python-based framework will be developed to seamlessly interact between the SMA Analytics and SMMD tools, which will write the full dataset and associated metadata to the GRC Information Management System before passing the required point-wise data to the SMMD tool. Data informatics is a key element of the NASA Vision 2040, which requires not only that data is stored and maintained throughout the material lifecycle, but that the data is also accessible and reusable such that material development efforts can be minimized. Therefore, for an ICME design approach to be realized, a centralized information management system that drives the ICME process must be able to communicate with other databases. The work that will be presented in this presentation will therefore not only demonstrate the ability of NASA GRC’s information management system to capture SMM data, but also its ability to interact with pre-existing tools specialized for such materials.

Data management↗

Uncertainty quantification of fireball features extracted from nuclear test films using computer vision

Films from the US’s historic nuclear testing era comprise the only extensive collection of imagery depicting high-yield detonations. These films offer unique insights into the characteristics of flows occurring on scales that are difficult to replicate experimentally, and they are a valuable source of data for the validation of models used to describe nuclear detonations. In recent work, we implemented modern computer vision and machine learning techniques to extract features of the fireball following nuclear detonation. With a training dataset of fireball films, we fine-tuned a You Only Look Once 11 (YOLO11) model to detect and track the fireball. Applied to a video, the outer bounding box produced in each frame by YOLO11 is used as an input prompt to Meta’s Segment Anything Model 2 (SAM2), which is shown to accurately predict the boundary of the fireball over time with high resolution. These state-of-the-art computer vision foundation models exhibit impressive visual accuracy in their results but lack an output of values that robustly quantify uncertainty in scientific applications. In this paper, we develop procedures for uncertainty quantification of extracted fireball features. We outline the application of a parallel attention mechanism to calculate uncertainty ranges that complement and better pose model validation data. This higher quality fireball validation data may serve to improve prognostic models describing nuclear detonations in support of nuclear forensic and emergency response activities.

Khristy, Joel [ORNL] (ORCID:0000000209963060)↗

Field-aligned particle currents near an auroral arc.

A Nike-Tomahawk rocket equipped to measure electric and magnetic fields and charged particles from a few eV to several hundred keV energy was flown into an auroral band on April 11, 1970. The purpose of this flight was to obtain evidence of the low-energy electrons and protons that constitute a field-aligned sheet current, and also to obtain the magnetic signature of such a current and the electric field in and near the auroral-arc electric current system. Particular attention was given to a sudden increase in the field-aligned current associated with a prior sudden increase in the electric field and a sudden change in the magnetic field, all occurring near the edge of a visual auroral arc. Data obtained are discussed and analyzed; they present an important contribution to the problem of mapping of atmospheric auroral phenomena to the magnetospheric equatorial plane.

Choy, L. W.↗

A design for a 1984 Mars rover

A Mars rover is planned for the mid-1980's as a follow-up to the Viking program, and as a prelude to a return-to-earth mission of Martian samples in the late eighties or early nineties. An overall view of the rover's configuration is presented with a summary of basic design parameters. Six subsystems are outlined: computing, with a 10 to the 8th bit bubble memory; mobility, designed for a journey of 100 km in 2 earth years; science sample acquisition, including a soil auger and hard rock drill; power, supplied by an RTG and stored in batteries; telecommunication, with 50 K bit UHF transmission relayed through an orbiter; and visual imaging, employing two television cameras, each with an 800 x 800 pixel charge coupled device. Scientific research goals include information about Martian seismic characteristics, magnetic field, surface heat flow, chemical composition, geology along a transverse, and meteorology. Attention is given to the necessity of rover autonomy from earth commands.

Dobrotin, B. M.↗

Window of visibility - A psychophysical theory of fidelity in time-sampled visual motion displays

A film of an object in motion presents on the screen a sequence of static views, while the human observer sees the object moving smoothly across the screen. Questions related to the perceptual identity of continuous and stroboscopic displays are examined. Time-sampled moving images are considered along with the contrast distribution of continuous motion, the contrast distribution of stroboscopic motion, the frequency spectrum of continuous motion, the frequency spectrum of stroboscopic motion, the approximation of the limits of human visual sensitivity to spatial and temporal frequencies by a window of visibility, the critical sampling frequency, the contrast distribution of staircase motion and the frequency spectrum of this motion, and the spatial dependence of the critical sampling frequency. Attention is given to apparent motion, models of motion, image recording, and computer-generated imagery.

Watson, A. B.↗

A re-analysis of the causes of Boeing 727 'black hole landing' crashes

A review is presented of Kraft and Elworth's (1969) investigation and analysis of night visual approaches; their data is reanalyzed, and the reliability of the visual angle hypothesis is discussed. To increase pilot awareness of the hazardous illusions inherent in black hole landings, it was suggested that pilots should monitor their altimeters more often during night approaches. It was also recommended that greater attention should be given to airport design, so that the effects of black hole conditions could be minimized.

Schwirzke, Martin F. J.↗

Piloted Evaluation of Modernized Limited Authority Control Laws in the NASA-Ames Vertical Motion Simulator (VMS)

The UH-60 BLACK HAWK was designed in the 1970s, when the US Army primarily operated during the day in good visual conditions. Subsequently, the introduction of night-vision goggles increased the BLACK HAWK'S mission effectiveness, but the accident rate also increased. The increased accident rate is strongly tied to increased pilot workload as a result of a degradation in visual cues. Over twenty years of research in helicopter flight control and handling qualities has shown that these degraded handling qualities can be recovered by modifying the response type of the helicopter in low speed flight. Sikorsky Aircraft Corporation initiated a project under the National Rotorcraft Technology Center (NRTC) to develop modern flight control laws while utilizing the existing partial authority Stability Augmentation System (SAS) of the BLACK HAWK. This effort resulted in a set of Modernized Control Laws (MCLAWS) that incorporate rate command and attitude command response types. Sikorsky and the US Army Aeroflightdynamics Directorate (AFDD) conducted a piloted simulation on the NASA-Ames Vertical h4otion Simulator, to assess potential handling qualities and to reduce the risk of subsequent implementation and flight test of these modern control laws on AFDD's EH-60L helicopter. The simulation showed that Attitude Command Attitude Hold control laws in pitch and roll improve handling qualities in the low speed flight regime. These improvements are consistent across a range of mission task elements and for both good and degraded visual environments. The MCLAWS perform better than the baseline UH-60A control laws in the presence of wind and turbulence. Finally, while the improved handling qualities in the pitch and roll axis allow the pilot to pay more attention to the vertical axis and hence altitude performance also improves, it is clear from pilot comments and altitude excursions that the addition of an Altitude Hold function would further reduce workload and improve overall handling qualities of the aircraft.

Sahasrabudhe, Vineet↗

The use of radar and visual observations to characterize the surface structure of the planet Mercury

An analysis is conducted of available topographic profiles and scattering parameters derived from earth-based S- and X-band radar observations of Mercury, in order to determine the nature and origin of regional surface variations and structures that are typical of the planet. Attention is given to the proposal that intercrater plains on Mercury formed from extensive volcanic flooding during bombardment, so that most craters were formed on a partially molten surface and were thus obliterated, together with previously formed tectonic features.

Clark, P. E.↗

Ultraviolet, visual, and infrared studies of galactic extreme emission line objects with very large IR-excess

Some preliminary results of a study of extreme emission line objects (EELOs) are presented. These stars are selected from H alpha emission line stars having a strong IR excess. The study is based on multiwavelength photometric and spectroscopic observations. Special attention is paid to the detailed study of the correlation between spectroscopic and photometric variations, which indicate the activity of the star. The ultraviolet and infrared extinction characteristics of the circumstellar material are given special attention.

Dewinter, D.↗

Medical technology advances from space research.

NASA-sponsored medical R & D programs for space applications are reviewed with particular attention to the benefits of these programs to earthbound medical services and to the general public. Notable among the results of these NASA programs is an integrated medical laboratory equipped with numerous advanced systems such as digital biotelemetry and automatic visual field mapping systems, sponge electrode caps for electroencephalograms, and sophisticated respiratory analysis equipment.

Pool, S. L.↗

Unsteady Aerodynamic Modeling in Roll for the NASA Generic Transport Model

Reducing the impact of loss-of-control conditions on commercial transport aircraft is a primary goal of the NASA Aviation Safety Program. One aspect in developing the supporting technologies is to improve the aerodynamic models that represent these adverse conditions. Aerodynamic models appropriate for loss of control conditions require a more general mathematical representation to predict nonlinear unsteady behaviors. In this paper, a more general mathematical model is proposed for the subscale NASA Generic Transport Model (GTM) that covers both low and high angles of attack. Particular attention is devoted to the stall region where full-scale transports have demonstrated a tendency for roll instability. The complete aerodynamic model was estimated from dynamic wind-tunnel data. Advanced computational methods are used to improve understanding and visualize the flow physics within the region where roll instability is a factor.

Murphy, Patrick C.↗

The Effects of Chronic Sleep Restriction on Multiple Object Tracking

The ability to simultaneously track numerous moving objects in the presence of irrelevant stimuli is essential for carrying out a variety of tasks. Sleep loss has been found to impair neurocognitive functioning and, as a result, attentional processing capacity is reduced. A common form of sleep loss is chronic sleep restriction (CSR), in which an inadequate amount of sleep is obtained over consecutive days. The objective of the current study was to determine if performance on the multiple object tracking (MOT) task was adversely impacted by a week of CSR. Twelve healthy participants (6 males, 6 females) kept a fixed sleep-wake schedule, with a constant waketime, at home for four weeks (activity monitors worn on the participant’s nondominant wrist were used to confirm compliance). Weeks one and three were deemed washout weeks, during which participants maintained a 9-hour sleep-wake schedule. Weeks two and four were deemed experimental weeks, during which participants were randomly assigned a 5-hour (CSR) and 9-hour (sleep satiation) sleep-wake schedule. Following night seven of each experimental week, participants completed a 13-hour laboratory visit under dim light (less than 15 lux) where they maintained a constant posture and were provided with hourly isocaloric snacks. MOT was presented at approximately 6 and 8 hours after waking. Participants were required to track four, five, or six moving targets in the presence of identical distractors (always 12 total objects). It was found that participants slept significantly less during the week of CSR compared to the week of sleep satiation. There was no difference in the overall proportion of correct MOT responses following the CSR and sleep satiation weeks. However, an additional analysis examining only the 6 target condition found that the proportion of correct responses was significantly lower following the week of CSR. These findings suggest that CSR has an adverse impact on tracking performance when the cognitive demand was higher. This has implications for individuals, such as air traffic controllers and truck drivers, who must visually track multiple moving objects under high workload situations, often while chronically sleep deprived.

sleep restriction↗

The effects of task difficulty and resource requirements on attention strategies

The patterns of attention strategies for task difficulty/resource tasks for which experimental results are presented and analyzed support the hypothesis that subjects may adopt an alternating (rather than concurrent one) when compelled to do so by either the size or the complexity of a visual display. According to the multiple resource model, if subjects had been performing the two tasks concurrently, the cost of this strategy would have been shown by a decrement in the spatial format, rather than the verbal format, due to competition for the same resource. Subjects may apply different strategies as a function of task difficulty and/or resource demand.

King, Teresa↗

Marangoni-Benard Convection in a Evaporating Liquid Thin Layer

Marangoni-Benard convection in evaporating liquid thin layers has been investigated through flow visualization and temperature profile measurement. Twelve liquids, namely ethyl alcohol, methanol, chloroform, acetone, cyclohexane, benzine, methylene chloride, carbon tetrachloride, ethyl acetate, n-pentane, silicone oil (0.65 cSt.), and freon-113, were tested and convection patterns in thin layers of these samples were observed. Comparison among these tested samples shows that some liquids are sensitive to surface contamination from aluminum powder but some are not. The latter is excellent to be used for the investigation of surface-tension driven convection through visualization using the tracer. Two sample liquids, alcohol and freon-113 were particularly selected for systematic study. It was found that the wavelength of Benard cells would not change with thickness of the layer when it evaporates at room temperature. Special attention was focused on cases in which a liquid layer was cooled from below, and some interesting results were obtained. Convection patterns were recorded during the evaporation process and the patterns at certain time frame were compared. Benard cells were observed in thin layers with a nonlinear temperature profile and even with a zero or positive temperature gradient. Wavelength of the cells was found to increase as the evaporation progressed.

Chai, An-Ti↗

Workspace visualization and time-delay telerobotic operations

The paper examines the performance of telerobotic tasks where the operator and robot are physically separated, and a comunication time delay of up to several seconds between them exists. This situation is applicable to space robotic servicing-assembly-maintenance operations on low earth or geosynchronous orbits with a ground-based command station. Attention is given to two developments which address advanced time-delay teleoperations for unstructured tasks: (1) the 'phantom robot', a real-time predictive graphics simulator developed to allow teleoperator eye-to-hand coordination or robot free-space kinematics under a time delay of several seconds; and (2) shared compliance control, a modified form of automatic electromechanical impedance control employed in parallel with manual position control to permit soft contact and grasp compliance with workpiece geometry under a time delay of several seconds.

Schenker, P. S.↗

The Sensor Dilemma in Intelligent Transportation Systems

Intelligent Transportation Systems (ITS) are at the forefront in advancing the way we interact and perceive with the transportation network. This revolution is fueled by the significant advancement in sensor perception technologies such as Radar, LiDAR and Video Imaging which are the most popular modalities for ITS. Real-time perception data from these sensors allows intelligent infrastructure side decision making to improve the energy, efficiency and safety at traffic intersections. As traffic departments across the United States are transitioning from traditional loop detectors / emulators and embracing newer technologies, they are often left with a dilemma in choosing a sensor technology for infrastructure-based perception which is reliable, inexpensive, easy to setup and has robust performance in varying weather conditions. However, choosing a sensor which checks all boxes is not straightforward as every sensor type has unique benefits and drawbacks. Radar is excellent at detecting long range vehicles and weather resistance but lacks high resolution. LiDAR is expensive and weather-sensitive, while cameras provide rich visual data at a low cost but are constrained by lighting and visibility. This study examines Radar, LiDAR and camera sensors capabilities to ascertain whether any of these qualifies as the "best" sensor for ITS perception. Through this evaluation, we hope to draw attention to the necessity of National Renewable Energy Laboratory's (NREL) Infrastructure Perception and Control (IPC) framework which presents a multi-sensor track data fusion engine to assimilate multiple data streams in order to provide robust and reliable perception. While no single sensor can meet all the demands of ITS, a hybrid approach combining multiple sensor modalities like Radar, LiDAR and cameras, offers the most robust solution for enhancing the safety and efficiency in intelligent transportation systems.

33 ADVANCED PROPULSION SYSTEMS↗