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At least 145 records · Page 8

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NASA NTRS2000

Transient cardio-respiratory responses to visually induced tilt illusions

Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

NASA Center JSC↗

DOE OSTI2022

Feasibility Study of Millimeter Wave Radars For Safeguards Applications

Containment and surveillance are fundamental measures in nuclear safeguards. Techniques such as video surveillance and laser curtain for containment provide effective monitoring in areas where maintaining continuity of knowledge is required. These systems, however, can be susceptible to loss of monitoring capabilities under certain environmental conditions such as poor visibility (i.e. low light conditions, smoke, fog, etc.) or extended power loss past the duration that the backup power system is designed for. Brookhaven National Laboratory has been investigating the feasibility of millimeter waves (mmWave) as a new perimeter seal in which radio frequency waves in the range of 60-64 GHz are used to detect and monitor objects of interest. Signals in this frequency range are not susceptible to environmental conditions. For proof-of-concept tests, mmWave sensors from Texas Instruments (TI), specificallyIWR6843, are used in a test bed at BNL's Waste Management facility to simulate the operations at nuclear facilities. The unique design of TI mmWave sensors requires less memory and power consumption compared to counterpart systems. These devices are capable of exporting 3D point-cloud data, which is visualized graphically and compared to videos recorded at the same time to validate the performance of the mmWave sensor. A set of experiments were planned to test the feasibility of the mmWave in this application, including monitoring static containers in a storage area and detecting intrusions at the boundaries of the area. In addition, the experiments also identify potential blind spots relative to sensor position and utilize multiple operating sensors simultaneously to reduce or eliminate such blind spots. The optimal positioning of multiple sensors was determined for the experimental room configuration. In this paper, we will discuss the details of this novel perimeter sealing concept and present the test results.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

NASA NTRS1990

Comparison of water production rates from UV spectroscopy and visual magnitudes for some recent comets

IUE data on the UV and visible coma emissions of the comets Bradfield, P/Tempel 2, Wilson, and P/Halley, are presently compared with the visual lightcurves from magnitudes reported in the IAU circulars to consider the temporal evolution of these comets. While the water-production rates obtainable from visual magnitudes on the basis of Newburn's (1984) method are consistent with OH-derived rates to first order, they are sometimes either displaced or unable to exhibit the same pre/postperihelion asymmetry. The best agreement is obtained for the relatively dust-free Comet P/Tempel 2. IUE Fine Error Sensor lightcurves are generally in agreement with curves based on total visual magnitude.

Roettger, E. E.↗

NASA NTRS2018

A Numerical and Experimental Investigation of Flow Separation Control over a Wall-Mounted Hump Model

Numerical simulations and wind tunnel experiments were performed to investigate flow separation and its control over a wall-mounted hump model. Three-dimensional, unsteady fluid dynamic simulations were used to capture the relevant flow physics of unsteady flow separation and its control via active and passive flow control methods. Surface pressure measurements and surface oilflow visualization were obtained in the experiments. Current measurements documented a considerably thinner incoming boundary layer, but similar pressure distribution, compared to the reference data reported in the CFD (Computational Fluid Dynamics) Validation (CFDVAL 2004) Experiments. Consistent with the data available in the literature, numerical simulations predicted a longer separation bubble, which manifested itself as a shift in the pressure distributions. Streamwise vortices generated by passive vortex generators increased the suction pressure and provided substantial pressure recovery. Numerical simulations of vortex generators qualitatively predicted the effects of control, and revealed patterns of attached/separated flow regions. On the other hand, active flow control using steady discrete jets reduced, but was not able to eliminate, flow separation for the tested configuration. Although the major disagreement between the numerical and experimental results was in the pressure recovery region due to the inaccurate prediction of separation bubbles, the relative pressure recoveries from the baselines were comparable. Surface oilflow visualization and simulated surface streamlines were qualitatively in good agreement revealing the key flow features.

Koklu, Mehti↗

NASA NTRS1981

Low-visibility visual simulation with real fog

An environmental fog simulation (EFS) attachment was developed to aid in the study of natural low-visibility visual cues and subsequently used to examine the realism effect upon the aircraft simulator visual scene. A review of the basic fog equations indicated that two major factors must be accounted for in the simulation of low visibility - one due to atmospheric attenuation and one due to veiling luminance. These factors are compared systematically by (1) comparing actual measurements to those computed from the fog equations, and (2) comparing runway-visual-range-related visual-scene contrast values with the calculated values. These values are also compared with the simulated equivalent equations and with contrast measurements obtained from a current electronic fog synthesizer to help identify areas in which improvements are needed. These differences in technique, the measured values, the features of both systems, a pilot opinion survey of the EFS fog, and improvements (by combining features of both systems) that are expected to significantly increase the potential as well as flexibility for producing a very high-fidelity low-visibility visual simulation are discussed.

Chase, W. D.↗

NASA NTRS1982

Low-Visibility Visual Simulation with Real Fog

An environmental fog simulation (EFS) attachment was developed to aid in the study of natural low-visibility visual cues and subsequently used to examine the realism effect upon the aircraft simulator visual scene. A review of the basic fog equations indicated that the two major factors must be accounted for in the simulation of low visibility-one due to atmospheric attenuation and one due to veiling luminance. These factors are compared systematically by: comparing actual measurements lo those computed from the Fog equations, and comparing runway-visual-range-related visual-scene contrast values with the calculated values. These values are also compared with the simulated equivalent equations and with contrast measurements obtained from a current electronic fog synthesizer to help identify areas in which improvements are needed. These differences in technique, the measured values, the Features of both systems, a pilot opinion survey of the EFS fog, and improvements (by combining features of both systems) that are expected to significantly increase the potential as well as flexibility for producing a very high-fidelity, low-visibility visual simulation are discussed.

Chase, Wendell D.↗

NASA NTRS1988

Cockpit data management

This study is a continuation of an FAA effort to alleviate the growing problems of assimilating and managing the flow of data and flight related information in the air transport flight deck. The nature and extent of known pilot interface problems arising from new NAS data management programs were determined by a comparative timeline analysis of crew tasking requirements. A baseline of crew tasking requirements was established for conventional and advanced flight decks operating in the current NAS environment and then compared to the requirements for operation in a future NAS environment emphasizing Mode-S data link and TCAS. Results showed that a CDU-based pilot interface for Mode-S data link substantially increased crew visual activity as compared to the baseline. It was concluded that alternative means of crew interface should be available during high visual workload phases of flight. Results for TCAS implementation showed substantial visual and motor tasking increases, and that there was little available time between crew tasks during a TCAS encounter. It was concluded that additional research should be undertaken to address issues of ATC coordination and the relative benefit of high workload TCAS features.

Groce, J. L.↗

NASA NTRS2000

Experimental Study of the Structure of a Wingtip Vortex

A complete look at the near-field development and subsequent role-up of a wingtip vortex from a NACA 0015 wing section is investigated. Two separate but equally important surveys of the vortex structure in the region adjacent to the wingtip and approximately one chord length downstream of the trailing edge are performed. The two surveys provide qualitative flow-visualization an quantitative velocity measurement data. The near-field development and subsequent role-up of the vortex structures is strongly influenced by the angle-of-attack and the end-cap treatment of the wing section. The velocity field near the wingtip of the NACA 0015 wing section was measured with a triple-sensor hot wire probe and compared to flow visualization images produced with titanium tetrachloride smoke injection and laser illumination. The flat end-cap results indicate the formation of multiple, relatively strong vortex structures as opposed to the formation of a single vortex produced with the round end-cap. The multiple vortices generated by the flat end-cap are seen to rotate around a common ce te in a helical pattern until they eventually merge into a single vortex. Compared to a non-dimensional loading parameter, the results of the velocity and flow visualization data shows a "jetlike" axial velocity profile for loading parameter values on the order of 0.1 and a "wakelike" profile for much lower loading parameter values.

Anderson, Elgin A.↗

NASA NTRS1991

IRAS asteroid families

The Infrared Astronomical Satellite (IRAS) sampled the entire asteroid population at wavelengths from 12 to 100 microns during its 1983 all sky survey. The IRAS Minor Planet Survey (IMPS) includes updated results for more recently numbered as well as other additional asteroids with reliable orbital elements. Albedos and diameters were derived from the observed thermal emission and assumed absolute visual magnitudes and then entered into the IMPS database at the Infrared Processing and Analysis Center (IPAC) for members of the Themis, Eos, Koronis and Maria asteroid families and compared with their visual colors. The IMPS results for the small (down to about 20 km) asteroids within these major families confirm trends previously noted for their larger members. Each of these dynamical families which are defined by their similar proper elements appears to have homogeneous physical properties.

Veeder, G. J.↗

DOE OSTI2018

Failure Analysis and Magnetic Evaluation of Tertiary Superheater Tube Used in Gas-Fired Boiler

Failure analysis was carried out on a prematurely failed tertiary superheater tube used in gas-fired boiler. The analysis includes a comparative study of visual examination, chemical composition, hardness and microstructure at failed region, adjacent and far to failure as well as on fresh tube. The chemistry was found matching to the standard specification, whereas the hardness was low in failed tube compared to the fish mouth opening region and the fresh tube. Microscopic examination of failed sample revealed the presence of spheroidal carbides of Cr and Mo predominantly along the grain boundaries. The primary cause of failure is found to be localized heating. Magnetic hysteresis loop (MHL) measurements were carried out to correlate the magnetic parameters with microstructure and mechanical properties to establish a possible non-destructive evaluation (NDE) for health monitoring of the tubes. The coercivity of the MHL showed a very good correlation with microstructure and mechanical properties deterioration enabling a possible NDE technique for the health monitoring of the tubes.

36 MATERIALS SCIENCE↗

NASA NTRS2007

Visual Acuity Using Head-fixed Displays During Passive Self and Surround Motion

The ability to read head-fixed displays on various motion platforms requires the suppression of vestibulo-ocular reflexes. This study examined dynamic visual acuity while viewing a head-fixed display during different self and surround rotation conditions. Twelve healthy subjects were asked to report the orientation of Landolt C optotypes presented on a micro-display fixed to a rotating chair at 50 cm distance. Acuity thresholds were determined by the lowest size at which the subjects correctly identified 3 of 5 optotype orientations at peak velocity. Visual acuity was compared across four different conditions, each tested at 0.05 and 0.4 Hz (peak amplitude of 57 deg/s). The four conditions included: subject rotated in semi-darkness (i.e., limited to background illumination of the display), subject stationary while visual scene rotated, subject rotated around a stationary visual background, and both subject and visual scene rotated together. Visual acuity performance was greatest when the subject rotated around a stationary visual background; i.e., when both vestibular and visual inputs provided concordant information about the motion. Visual acuity performance was most reduced when the subject and visual scene rotated together; i.e., when the visual scene provided discordant information about the motion. Ranges of 4-5 logMAR step sizes across the conditions indicated the acuity task was sufficient to discriminate visual performance levels. The background visual scene can influence the ability to read head-fixed displays during passive motion disturbances. Dynamic visual acuity using head-fixed displays can provide an operationally relevant screening tool for visual performance during exposure to novel acceleration environments.

Wood, Scott J.↗

NASA NTRS1998

Analysis of Ceramic Color by Special Reflectance

Radiometric and visual techniques are compared as quantitative methods for determining pottery color. An analysis of fifty-two prehistoric sherds selected at random from a multicomponent site indicates that there is an increase in the accuracy and efficiency in determining color using a spectroradiometer over subjective visual observations. Further, radiometric data can be transformed to CIE chromacity coordinates and Munsell color from spectral reflectance curves and analysed directly to access quantitative accuracy.

Giardino, Marco↗

DOE OSTI2020

A new flow pattern map for flow boiling of R410A in horizontal micro-fin tubes considering the effect of the helix angle

This paper presents an improved flow pattern map for flow boiling in horizontal micro-fin tubes considering the effect of helix angle. The proposed map is modified from the one developed for horizontal smooth tubes by Wojtan et al. (2005) and takes the early transition to annular flow due to micro-fin geometry into account. Visualization of R410A flow boiling is carried out through the transparent smooth and micro-fin tubes with 0°, 10° and 18° helix angle and plotted on the proposed map for comparison. The result shows that the flow pattern map for micro-fin tube with 0° helix angle is generally similar to that for the smooth tube. For the tube with 10° and 18° helix angle, the annular flow occurs at lower vapor quality and lower mass flux. The proposed map shows good agreements when compared with the visualization and reflects the downward shift (to lower mass flux and vapor quality conditions) of the SW-WA transition with the increase of the helix angle. In order to further validate the proposed model, the flow pattern transitions calculated from the equations are also compared with the experimental data of the micro-fin tube in literature. The results show that the modified map increase the prediction accuracy of the flow patterns in the micro-fin tube.

42 ENGINEERING↗

DOE OSTI2018

IMG/M v.5.0: an integrated data management and comparative analysis system for microbial genomes and microbiomes

The Integrated Microbial Genomes & Microbiomes system v.5.0 (IMG/M: https://img.jgi.doe.gov/m/) contains annotated datasets categorized into: archaea, bacteria, eukarya, plasmids, viruses, genome fragments, metagenomes, cell enrichments, single particle sorts, and metatranscriptomes. Source datasets include those generated by the DOE's Joint Genome Institute (JGI), submitted by external scientists, or collected from public sequence data archives such as NCBI. All submissions are typically processed through the IMG annotation pipeline and then loaded into the IMG data warehouse. IMG's web user interface provides a variety of analytical and visualization tools for comparative analysis of isolate genomes and metagenomes in IMG. IMG/M allows open access to all public genomes in the IMG data warehouse, while its expert review (ER) system (IMG/MER: https://img.jgi.doe.gov/mer/) enabled registered users to access their private genomes and to store their private datasets in workspace for sharing and for further analysis. IMG/M data content has increased by 60% since the last report published in the 2017 NAR Database Issue. IMG/M v.5.0 has a new and more powerful genome search feature, new statistical tools, and supports metagenome binning.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS1987

High resolution thermal infrared mapping of Martian channels

Viking Infrared Thermal Mapper (IRTM) high resolution (2 to 5 km) data were compiled and compared to Viking Visual Imaging Subsystem (VIS) data and available 1:5M geologic maps for several Martian channels including Dao, Harmakhis, Mangala, Shalbatana, and Simud Valles in an effort to determine the surface characteristics and the processes active during and after the formation of these channels. Results show a dominance of aeolian processes active in and around the channels. These processes have left materials thick enough to mask any genuine channel deposits. Results also indicate that very comparable Martian channels and their surrounding terrain are blanketed by deposits which are homogeneous in their thermal inertia values. However, optimum IRTM data does not cover the entire Martian surface and because local deposits of high thermal inertia material may not be large enough in areal extent or may be in an unfavorable location on the planet, a high resolution data track may not always occur over these deposits. Therefore, aeolian processes may be even more active than the IRTM data tracts can always show.

Craddock, R. A.↗

NASA NTRS1997

Superimposition, symbology, visual attention, and the head-up display

In two experiments we examined a number of related factors postulated to influence head-up display (HUD) performance. We addressed the benefit of reduced scanning and the cost of increasing the number of elements in the visual field by comparing a superimposed HUD with an identical display in a head-down position in varying visibility conditions. We explored the extent to which the characteristics of HUD symbology support a division of attention by contrasting conformal symbology (which links elements of the display image to elements of the far domain) with traditional instrument landing system (ILS) symbology. Together the two experiments provide strong evidence that minimizing scanning between flight instruments and the far domain contributes substantially to the observed HUD performance advantage. Experiment 1 provides little evidence for a performance cost attributable to visual clutter. In Experiment 2 the pattern of differences in lateral tracking error between conformal and traditional ILS symbology supports the hypothesis that, to the extent that the symbology forms an object with the far domain, attention may be divided between the superimposed image and its counterpart in the far domain.

Attention↗

DOE OSTI2014

Electrodynamics of a ring-shaped spiral resonator

We present analytical, numerical, and experimental investigations of electromagnetic resonant modes of a compact monofilar Archimedean spiral resonator shaped in a ring, with no central part. Planar spiral resonators are interesting as components of metamaterials for their compact deep-subwavelength size. Such resonators couple primarily to the magnetic field component of the incident electromagnetic wave, offering properties suitable for magnetic meta-atoms. Surprisingly, the relative frequencies of the resonant modes follow the sequence of the odd numbers as f{sub 1}:f{sub 2}:f{sub 3}:f{sub 4}… = 1:3:5:7…, despite the nearly identical boundary conditions for electromagnetic fields at the extremities of the resonator. In order to explain the observed spectrum of resonant modes, we show that the current distribution inside the spiral satisfies a particular Carleman type singular integral equation. By solving this equation, we obtain a set of resonant frequencies. The analytically calculated resonance frequencies and the current distributions are in good agreement with experimental data and the results of numerical simulations. By using low-temperature laser scanning microscopy of a superconducting spiral resonator, we compare the experimentally visualized ac current distributions over the spiral with the calculated ones. Theory and experiment agree well with each other. Our analytical model allows for calculation of a detailed three-dimensional magnetic field structure of the resonators.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2020

Evaluation of camera-based freehand SPECT in preoperative sentinel lymph node mapping for melanoma patients

Assessment of lymphatic status via sentinel lymph node (SLN) biopsy is an integral and crucial part of melanoma surgical oncology. The most common technique for sentinel node mapping is preoperative planar scintigraphy of an injected gamma-emitting lymphatic tracer followed by intraoperative node localization using a non-imaging gamma probe with auditory feedback. In recent years, intraoperative visualization of SLNs in 3D has become possible by coupling the probe to an external system capable of tracking its location and orientation as it is read out, thereby enabling computation of the 3D distribution of the tracer (freehand SPECT). In this project, the non-imaging probe of the fhSPECT system was replaced by a unique handheld gamma camera containing an array of sodium iodide crystals optically coupled to an array of silicon photomultipliers (SiPMs). A feasibility study was performed in which preoperative SLN mapping was performed using camera fhSPECT and the number of detected nodes was compared to that visualized by lymphoscintigraphy, probe fhSPECT, and to the number ultimately excised under non-imaging probe guidance. Among five subjects, SLNs were detected in nine lymphatic basins, with one to five SLNs detected per basin. A basin-by-basin comparison showed that the number of SLNs detected using camera fhSPECT exceeded that using lymphoscintigraphy and probe fhSPECT in seven of nine basins and five of five basins, respectively. (Probe fhSPECT scans were not performed for four basins.) It exceeded the number excised under non-imaging probe guidance for seven of nine basins and equaled the number excised for the other two basins. Freehand SPECT using a prototype SiPM-based gamma camera demonstrates high sensitivity for detection of SLNs in a preoperative setting. Camera fhSPECT is a potential means for efficiently obtaining real-time 3D activity distribution maps in applications such as image-guided percutaneous biopsy, and surgical SLN biopsy or radioguided tumor excision.

60 APPLIED LIFE SCIENCES↗