Requirements for VLA systems
The effectiveness of visual landing aid (VLA) systems during the approach and landing flight phase of V/STOL aircraft is examined. Baseline requirements for VLA systems are determined.
Flynn, N. S.↗
SEARCH · Engineering Papers
Results for “Visual Examination”
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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Nitric oxide formation in gas turbine engines: A theoretical and experimental study
A modified Zeldovich kinetic scheme was used to predict nitric oxide formation in the burned gases. Nonuniformities in fuel-air ratio in the primary zone were accounted for by a distribution of fuel-air ratios. This was followed by one or more dilution zones in which a Monte Carlo calculation was employed to follow the mixing and dilution processes. Predictions of NOX emissions were compared with various available experimental data, and satisfactory agreement was achieved. In particular, the model is applied to the NASA swirl-can modular combustor. The operating characteristics of this combustor which can be inferred from the modeling predictions are described. Parametric studies are presented which examine the influence of the modeling parameters on the NOX emission level. A series of flow visualization experiments demonstrates the fuel droplet breakup and turbulent recirculation processes. A tracer experiment quantitatively follows the jets from the swirler as they move downstream and entrain surrounding gases. Techniques were developed for calculating both fuel-air ratio and degree of nonuniformity from measurements of CO2, CO, O2, and hydrocarbons. A burning experiment made use of these techniques to map out the flow field in terms of local equivalence ratio and mixture nonuniformity.
Mikus, T.↗
An in-flight investigation of pilot-induced oscillation suppression filters during the fighter approach and landing task
An investigation of pilot-induced oscillation suppression (PIOS) filters was performed using the USAF/Flight Dynamics Laboratory variable stability NT-33 aircraft, modified and operated by Calspan. This program examined the effects of PIOS filtering on the longitudinal flying qualities of fighter aircraft during the visual approach and landing task. Forty evaluations were flown to test the effects of different PIOS filters. Although detailed analyses were not undertaken, the results indicate that PIOS filtering can improve the flying qualities of an otherwise unacceptable aircraft configuration (Level 3 flying qualities). However, the ability of the filters to suppress pilot-induced oscillations appears to be dependent upon the aircraft configuration characteristics. Further, the data show that the filters can adversely affect landing flying qualities if improperly designed. The data provide an excellent foundation from which detail analyses can be performed.
Bailey, R. E.↗
An in-flight investigation of pilot-induced oscillation suppression filters during the fighter approach and landing task
An investigation of pilot-induced oscillation suppression (PIOS) filters was performed using the USAF/Flight Dynamics Laboratory variable stability NT-33 aircraft, modified and operated by Calspan. This program examined the effects of PIOS filtering on the longitudinal flying qualities of fighter aircraft during the visual approach and landing task. Forty evaluations were flown to test the effects of different PIOS filters. Although detailed analyses were not undertaken, the results indicate that PIOS filtering can improve the flying qualities of an otherwise unacceptable aircraft configuration (Level 3 flying qualities). However, the ability of the filters to suppress pilot-induced oscillations appears to be dependent upon the aircraft configuration characteristics. Further, the data show that the filters can adversely affect landing flying qualities if improperly designed. The data provide an excellent foundation from which detail analyses can be performed.
Bailey, R. E.↗
Perceived change in orientation from optic flow in the central visual field
The effects of internal depth within a simulation display on perceived changes in orientation have been studied. Subjects monocularly viewed displays simulating observer motion within a volume of randomly positioned points through a window which limited the field of view to 15 deg. Changes in perceived spatial orientation were measured by changes in posture. The extent of internal depth within the display, the presence or absence of visual information specifying change in orientation, and the frequency of motion supplied by the display were examined. It was found that increased sway occurred at frequencies equal to or below 0.375 Hz when motion at these frequencies was displayed. The extent of internal depth had no effect on the perception of changing orientation.
Dyre, Brian P.↗
Display formatting techniques for improving situation awareness in the aircraft cockpit
Possible modifications of primary flight instruments for attitude control and navigation were examined including a display perspective, frames of reference, and the incorporation of directional color to enhance visual momentum. A low-fidelity fixed-wing flight simulation was evaluated. It is concluded that situation awareness measured by flight performance and recovery from disorientation events, was best maintained with the planar outside-in display, whereas color coding improved the performance on the planar inside-out display.
Andre, Anthony D.↗
Depth Cue Integration in an Active Control Paradigm
Numerous models of depth cue integration have been proposed. Of particular interest is how the visual system processes discrepent cues, as might arise when viewing synthetic displays. A powerful paradigm for examining this integration process can be adapted from manual control research. This methodology introduces independent disturbances in the candidate cues, then performs spectral analysis of subjects' resulting motoric responses (e.g., depth matching). We will describe this technique and present initial findings.
Kaiser, Mary K.↗
Effects of characteristics of image quality in an immersive environment
Image quality issues such as field of view (FOV) and resolution are important for evaluating "presence" and simulator sickness (SS) in virtual environments (VEs). This research examined effects on postural stability of varying FOV, image resolution, and scene content in an immersive visual display. Two different scenes (a photograph of a fountain and a simple radial pattern) at two different resolutions were tested using six FOVs (30, 60, 90, 120, 150, and 180 deg.). Both postural stability, recorded by force plates, and subjective difficulty ratings varied as a function of FOV, scene content, and image resolution. Subjects exhibited more balance disturbance and reported more difficulty in maintaining posture in the wide-FOV, high-resolution, and natural scene conditions.
Non-NASA Center↗
Structure from Motion Photogrammetry and Micro X-Ray Computed Tomography 3-D Reconstruction Data Fusion for Non-Destructive Conservation Documentation of Lunar Samples
Our team is developing a modern, cross-disciplinary approach to documentation and preservation of astromaterials, specifically lunar and meteorite samples stored at the Johnson Space Center (JSC) Lunar Sample Laboratory Facility. Apollo Lunar Sample 60639, collected as part of rake sample 60610 during the 3rd Extra-Vehicular Activity of the Apollo 16 mission in 1972, served as the first NASA-preserved lunar sample to be examined by our team in the development of a novel approach to internal and external sample visualization. Apollo Sample 60639 is classified as a breccia with a glass-coated side and pristine mare basalt and anorthosite clasts. The aim was to accurately register a 3-dimensional Micro X-Ray Computed Tomography (XCT)-derived internal composition data set and a Structure-From-Motion (SFM) Photogrammetry-derived high-fidelity, textured external polygonal model of Apollo Sample 60639. The developed process provided the means for accurate, comprehensive, non-destructive visualization of NASA's heritage lunar samples. The data products, to be ultimately served via an end-user web interface, will allow researchers and the public to interact with the unique heritage samples, providing a platform to "slice through" a photo-realistic rendering of a sample to analyze both its external visual and internal composition simultaneously.
Beaulieu, K. R.↗
Fluid Shifts Before, During, and After Prolonged Space Flight and their Association with Intracranial Pressure and Visual Impairment
With the conclusion of the Space Shuttle program, NASA is focusing on long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed in Space Shuttle crewmembers after their short-duration missions were largely transient, but more than 30% of ISS astronauts experience more profound changes in vision, some with objective structural and functional findings such as papilledema and choroidal folds on ophthalmologic examination. Globe flattening, optic nerve sheath dilatation, optic nerve tortuosity, and other findings have been noted in imaging studies. This pattern is referred to as visual impairment and intracranial pressure (VIIP) syndrome. The VIIP signs and symptoms, as well as postflight lumbar puncture data, suggest that elevated intracranial pressure (ICP) is associated with the space flight-induced cephalad fluid shifts, but this hypothesis has not been systematically tested. The purpose of this study is to objectively characterize the fluid distribution and compartmentalization associated with long-duration space flight, and to correlate the findings with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during space flight, as well as the VIIP-related effects of those shifts, can be predicted by crewmember baseline data and responses to acute hemodynamic manipulations (such as head-down tilt tests) obtained before flight. Lastly, we will evaluate the patterns of fluid distribution in astronaut subjects on the ISS during the use of lower body negative pressure (LBNP) and respiratory maneuvers to characterize and explain general and individual responses during space flight.
Stenger, M.↗
Post-Irradiation Examination to Quantify Irradiation-Induced Bowing of SiGA® Silicon Carbide Composite Structures (Final CRADA Report – NFE-23-09937)
As part of the SiC-based material development at General Atomics Electromagnetic Systems (GA-EMS), this project involved the first-of-a-kind experimental post-irradiation examination of the irradiation-induced bowing response in SiC composite structures under a neutron flux gradient. The SiC composite miniature channel specimen was provided by GA-EMS for the irradiation experiment. To quantify the irradiation-induced bowing of the channel specimen, a series of visual and dimensional inspections were conducted using the unique capabilities at Oak Ridge National Laboratory (ORNL), including a custom profilometry rig. The post-irradiation examination results of this project will assist GA-EMS in validating their fuel performance model for SiC-based core structures in neutron irradiation environments.
36 MATERIALS SCIENCE↗
Comparison of Active and Passive Head Impulse Testing of the Horizontal Vestibulo-Ocular Reflex: Exploring the Feasibility of Different Approaches for Spaceflight
INTRODUCTION: Astronauts experience a wide variety of sensorimotor disturbances primarily due to microgravity-induced vestibular adaptations during spaceflight. Head Impulse Testing (HIT) will be conducted during the Complement of Integrated Protocols for Human Exploration Research program(CIPHER) Vestibular Health study to examine changes in the horizontal vestibulo-ocular reflex in response to high-velocity head movements to detect changes in peripheral vestibular function [1,2]. However, correct interpretation will require consideration of potential artifacts and the constraints of conducting this test across different phases of the mission. Therefore, the aims of our study were to (1) examine reliability across different test operators, and (2) compare results of active (aHIT) versus passive (pHIT) approaches to evaluate the feasibility of self-administered versus operator-assisted approaches. A comparison of responses with visual viewing of a wall target (default condition) versus vision occluded evaluated the influence of other oculomotor control influence across conditions, and comparison with computer-generated rotator head impulse tests (rHIT) examined the variability associated with the ocular responses independent of the variability in executing the head movements themselves. METHODS: Seventeen non-astronaut volunteers (male n=12, age=22.9 ± 3.0; female n=5, age=27.0 ± 6.0, mean ± std) completed HIT testing using video-oculography (VOG) goggles and a high-torque rotator system. The test order was counterbalanced across conditions: (1) passive head-on-torso (pHIT, default condition for flight study) using two operators (Op1 and Op2), (2) active head-on-torso (aHIT, subject initiated), and (3) passive head and torso using rotary chair (rHIT). Eye and head movement data were processed to obtain gain in each direction. The main outcome measures were average gain and asymmetry [1], as well as the percentage of acceptable trials not excluded due to insufficient head amplitude or recording artifacts. RESULTS: While the pHIT gains were similar with vision (1.032 ± 0.043) and vision occluded (1.029 ± 0.038) conditions, the percentage of acceptable trials was greater with vision (Op1 = 93.0%, Op2 = 93.2%) versus occluded (Op1 = 70.7%, Op2 = 67.6%). The reliability between operators was greater for pHIT gain (Intraclass Correlation, ICC = 0.66, p = 0.001) than for pHIT asymmetry (ICC = 0.57, p = 0.01). The percentage of acceptable trials reduced by ~20% during the self-administered aHITs for both visual conditions and tended to be lower than computer-generated rHITs (76% versus 83%). While the aHIT gains were not significantly different than pHIT gains for vision or vision occluded conditions, these measures were poorly correlated. Both aHIT and pHIT gains were significantly greater than the rHIT gains, presumably due to the reduced velocities from the rotator. The asymmetry measures were poorly correlated across pHIT, aHIT, and rHIT conditions, although none of the subjects had asymmetries greater than 16%. DISCUSSION: Our findings support the feasibility of using the standard pHIT methodology for spaceflight. Similarities between visual conditions reflect that these responses are mediated by the peripheral lateral canals rather than other oculomotor mechanisms. The inter-tester reliability was acceptable despite differences in the tester training. In addition to concerns of non-vestibular mechanisms introduced during self-administered aHITs [2], operator-assisted pHITs resulted in higher percentage of acceptable trials and should result in more efficient and reliable measures during spaceflight.
M R Ehrenburg↗
New versions of old flow visualization systems
A small, modified Mach-Zehnder interferometer placed in series with a much larger schlieren optical system spanning the test section is examined. In one arm of the interferometer, light from the schlieren is focused through a pinhole and recollimating lens to produce a reference beam which interferes with the remaining object beam from the other arm. The object and reference beams are separated only over a small interval following the test section, and differential vibrations are greatly reduced. Color schlieren has technical, as well as aesthetic, advantages over black-and-white schlieren. Since each color is associated with a specific amount of refraction, quantitative evaluation of certain refractive-index fields becomes possible using very simple equations derived from ray trace theory. Rainbow schlieren of an acetylene flame, and the evaluated refractive index distribution are shown. Root-mean-square refractive index fluctuations in homogeneous, isotropic turbulence were determined using the rainbow schlieren, since these fluctuations determine the root-mean-square refraction, which is indicated by the overall color of the image.
Howes, W. L.↗
Sustainable Immersive Visualization: A Tale of Two Visualization Labs
For large-scale immersive installations, sustainability is a challenge. This talk presents a comparative analysis of two immersive visualization laboratories, each following distinct trajectories. At the core of this discussion lies the question of what has made the NREL ESIF Insight Center a sustainable success for the last decade. Our examination encompasses three pivotal ingredients: the right funding model, the right usage model, and demonstrating added value.
funding model↗
Combining Deep Learning With Physics Based Features in Explosion-Earthquake Discrimination
This paper combines the power of deep-learning with the generalizability of physics-based features, to present an advanced method for seismic discrimination between earthquakes and explosions. The proposed method contains two branches: a deep learning branch operating directly on seismic waveforms or spectrograms, and a second branch operating on physics-based parametric features. These features are high-frequency P/S amplitude ratios and the difference between local magnitude (ML) and coda duration magnitude (MC). The combination achieves better generalization performance when applied to new regions than models that are developed solely with deep learning. Further, we also examined which parts of the waveform data dominate deep learning decisions (i.e., via Grad-CAM). Such visualization provides a window into the black-box nature of the machine-learning models and offers new insight into how the deep learning derived models use data to make decisions.
58 GEOSCIENCES↗
Galaxy morphological classification catalogue of the Dark Energy Survey Year 3 data with convolutional neural networks
ABSTRACT We present in this paper one of the largest galaxy morphological classification catalogues to date, including over 20 million galaxies, using the Dark Energy Survey (DES) Year 3 data based on convolutional neural networks (CNNs). Monochromatic i-band DES images with linear, logarithmic, and gradient scales, matched with debiased visual classifications from the Galaxy Zoo 1 (GZ1) catalogue, are used to train our CNN models. With a training set including bright galaxies (16 ≤ i < 18) at low redshift (z < 0.25), we furthermore investigate the limit of the accuracy of our predictions applied to galaxies at fainter magnitude and at higher redshifts. Our final catalogue covers magnitudes 16 ≤ i < 21, and redshifts z < 1.0, and provides predicted probabilities to two galaxy types – ellipticals and spirals (disc galaxies). Our CNN classifications reveal an accuracy of over 99 per cent for bright galaxies when comparing with the GZ1 classifications (i < 18). For fainter galaxies, the visual classification carried out by three of the co-authors shows that the CNN classifier correctly categorizes discy galaxies with rounder and blurred features, which humans often incorrectly visually classify as ellipticals. As a part of the validation, we carry out one of the largest examinations of non-parametric methods, including ∼100 ,000 galaxies with the same coverage of magnitude and redshift as the training set from our catalogue. We find that the Gini coefficient is the best single parameter discriminator between ellipticals and spirals for this data set.
79 ASTRONOMY AND ASTROPHYSICS↗
Remote sensing and urban public health
The applicability of remote sensing in the form of aerial photography to urban public health problems is examined. Environmental characteristics are analyzed to determine if health differences among areas could be predicted from the visual expression of remote sensing data. The analysis is carried out on a socioeconomic cross-sectional sample of census block groups. Six morbidity and mortality rates are the independent variables while environmental measures from aerial photographs and from the census constitute the two independent variable sets. It is found that environmental data collected by remote sensing are as good as census data in evaluating rates of health outcomes.
Rush, M.↗
High energy X-ray results from HEAO-1: X-ray pulsars, and the all sky survey
Results of the sky survey performed with the high energy X-ray detectors of the A-4 experiment onboard the HEAO 1 spacecraft are presented. The data presented cover the energy range from 13 to 80 keV. Strong sources are identified by visual inspection and azimuthal superpositions are performed in order to find weak sources. Time variability is also examined. Results of studies of X-ray pulsars are given including a brief description of an X-ray pulsar in terms of current theory.
Levine, A.↗