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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Vestibular and Non-vestibular Contributions to Eye Movements that Compensate for Head Rotations during Viewing of Near Targets

We studied horizontal eye movements induced by en-bloc yaw rotation, over a frequency range 0.2 - 2.8 Hz, in 10 normal human subjects as th ey monocularly viewed a target located at their near point of focus. We measured gain and phase relationships between eye-in-head velocity and head velocity when the near target was either earth-fixed or head-fixed. During viewing of the earth-fixed near target,median gain was 1.49 (range 1.24 - 1.87) at 0.2 Hz for the group of subjects, but decl ined at higher frequencies, so that at 2.8 Hz median gain was 1.08 (r ange 0.68 - 1.67). During viewing of the head-fixed near target, median gain was 0.03 (range 0.01 - 0.10) at 0.2 Hz for the group of subjec ts, but increased at higher frequencies, so that at 2.8 Hz median gai n was 0.71 (range 0.28 - 0.94). We estimated the vestibular contribution to these responses (vestibulo-ocular reflex gain, Gvor) by applyin g transient head perturbations (peak acceleration> 1,000 deg's(exp 2) ) during sinusoidal rotation under the two viewing conditions. Median Gvor, estimated < 70m after the onset of head perturbation, was 0.98 (range 0.39 - 1.42) while viewing the earth-fixed near target, and 0. 97 (range 0.37 - 1.33) while viewing the head-fixed near target. For the group of subjects, 9 out of 10 subjects showed no sigificant diff erence of Gvor between the two viewing conditions ( p > 0.053 ) at all test frequencies. Since Gvor accounted for only approximately 73% of the overall response gain during viewing of the earth-fixed target, we investigated the relative contributions of non-vestibular factors. When subjects viewed the earth-fixed target under strobe illumination , to eliminate retinal image slip information, the gain of compensato ry eye movements declined compared with viewing in ambient room light . During sum-of-sine head rotations, while viewing the earth-fixed target, to minimize contributions from predictive mechanisms, gain also declined Nonetheless, simple superposition of smooth-pursuit tracking of sinusoidal target motion could not fully account for the overall r esponse at higher frequencies, suggesting other non-vestibular contributions. During binocular viewing conditions when vergence angle was s ignificantly greater than monocular viewing (p < 0.001), this gain of compensatory eye movements did not show proportional change; indeed, gain could not be correlated with vergence angle during monocular or binocular viewing. We conclude that several separate factors contribute to generate eye rotations during sinusoidal yaw head rotations whi le viewing a near target; these include the VOR, visual-tracking eye movements that utilize retinal image motion, predictive eye movements and, possibly, other unidentified nonvestibular factors. For these experiments, vergence was not an important determinant of response gain .

Han, Yanning H.↗
NASA NTRS1980

Simulation study of a geometric shape factor technique for estimating earth-emitted radiant flux densities from wide-field-of-view radiation measurements

Geometric shape factors were computed and applied to satellite simulated irradiance measurements to estimate Earth emitted flux densities for global and zonal scales and for areas smaller than the detector field of view (FOV). Wide field of view flat plate detectors were emphasized, but spherical detectors were also studied. The radiation field was modeled after data from the Nimbus 2 and 3 satellites. At a satellite altitude of 600 km, zonal estimates were in error 1.0 to 1.2 percent and global estimates were in error less than 0.2 percent. Estimates with unrestricted field of view (UFOV) detectors were about the same for Lambertian and limb darkening radiation models. The opposite was found for restricted field of view detectors. The UFOV detectors are found to be poor estimators of flux density from the total FOV and are shown to be much better as estimators of flux density from a circle centered at the FOV with an area significantly smaller than that for the total FOV.

Weaver, W. L.↗
NASA NTRS1994

Integrating human factors knowledge into certification: The point of view of the Internatioanal Civil Aviation Organization (ICAO)

It is appropriate here to repeat the analogy described in the introduction to this paper which is that: The consideration of human factors requirements during the design stage of advanced, new technology systems may be seen as resting over a three-legged stool. The first leg, the equipment that a system will utilize to achieve its goals, has traditionally attracted ergonomic considerations associated with equipment design, usually centered around 'knobs and dials.' Lately, this view has expanded to include the so-called other important aspect of Human Factor's study which deals with the cognitive, behaviorial and social processes of the human operators. Study in this area must be furthered. The second leg of the stool, the procedures to operate the equipment, however, has been largely unaddressed. Procedures are not inherent to equipment, but must be developed. The importance of proper human factors consideration in the design of procedures can not be overstated. Lastly, the third leg of the stool, the certification of personnel who will operate the equipment, is very much underway, but far from being complete. The real quest now, however, is to integrate these three legs into an indivisible one. Finally, and most importantly, this workshop and its topic are extremely timely in that we are at the dawn of the most ambitious development ever undertaken in international civil aviation. This would allow us the rather unique opportunity to put theory into practice in the near future by ensuring that the concepts developed and furthered by this workshop and the follow-up are implemented in the design and certification of the ICAO future CNS/ATM systems described earlier in this paper. Now is the time to incorporate human factors requirements during the certification processes of these systems. This might act as a test to the feasibility of these ideas. Such endeavors represent a challenge for the research, engineering, training, operational and regulatory communities. But there is certainly more to be gained by attempting to meet the challenge rather than refraining from progress by decrying the difficulties involved.

Maurino, Daniel↗
NASA NTRS1993

Research in image management and access

Presently, the problem of over-all library system design has been compounded by the accretion of both function and structure to a basic framework of requirements. While more device power has led to increased functionality, opportunities for reducing system complexity at the user interface level have not always been pursued with equal zeal. The purpose of this book is therefore to set forth and examine these opportunities, within the general framework of human factors research in man-machine interfaces. Human factors may be viewed as a series of trade-off decisions among four polarized objectives: machine resources and user specifications; functionality and user requirements. In the past, a limiting factor was the availability of systems. However, in the last two years, over one hundred libraries supported by many different software configurations have been added to the Internet. This document includes a statistical analysis of human responses to five Internet library systems by key features, development of the ideal online catalog system, and ideal online catalog systems for libraries and information centers.

Vondran, Raymond F.↗
NASA NTRS1989

High resolution decoding techniques and single-chip decoders for multi-anode microchannel arrays

While the pixel size in a standard multianode microchannel array (MAMA) photon-counting detector is determined by the spacing of the anode array, the factor most fundamentally limiting pixel resolution is the spacing of the channels in the microchannel plate. Detector resolution can be improved by means of digitization followed by a centroiding procedure. The decoding hardware and the techniques for enhanced pixel resolution are presently discussed with a view to the factors of speed and complexity. A single-chip CMOS gate-array implementation of the decoder is devised and compared with existing multichip decoders' performance.

Kasle, David B.↗
NASA NTRS1987

Studies of the scattering/absorption of minerals

Reflectance spectra were computed for water ice and ammonia ice mixtures as functions of weight fraction, grain size, and viewing geometry to simulate possible outer solar system satellite surfaces. Reflectance spectra of planetary surfaces are most affected by the weight fraction and grain sizes of the minerals in the surface. The reflectance can range from 1.0 to about 0.01 by changing the grain size or weight fraction, a factor of 100. Viewing geometry changes the reflectance by about 25 percent or less.

Clark, Roger N.↗
NASA NTRS2010

Human Factors Research for Space Exploration: Measurement, Modeling, and Mitigation

As part of NASA's Human Research Program, the Space Human Factors Engineering Project serves as the bridge between Human Factors research and Human Spaceflight applications. Our goal is to be responsive to the operational community while addressing issues at a sufficient level of abstraction to ensure that our tools and solutions generalize beyond the point design. In this panel, representatives from four of our research domains will discuss the challenges they face in solving current problems while also enabling future capabilities. Historically, engineering-dominated organizations have tended to view good Human Factors (HF) as a desire rather than a requirement in system design and development. Our field has made significant gains in the past decade, however; the Department of Defense, for example, now recognizes Human-System Integration (HSI), of which HF is a component, as an integral part of their divisions hardware acquisition processes. And our own agency was far more accepting of HF/HSI requirements during the most recent vehicle systems definition than in any prior cycle. Nonetheless, HF subject matter experts at NASA often find themselves in catch up mode... coping with legacy systems (hardware and software) and procedures that were designed with little regard for the human element, and too often with an attitude of we can deal with any operator issues during training. Our challenge, then, is to segregate the true knowledge gaps in Space Human Factors from the prior failures to incorporate best (or even good) HF design principles. Further, we strive to extract the overarching core HF issues from the point-design-specific concerns that capture the operators (and managers) attention. Generally, our approach embraces a 3M approach to Human Factors: Measurement, Modeling, and Mitigation. Our first step is to measure human performance, to move from subjective anecdotes to objective, quantified data. Next we model the phenomenon, using appropriate methods in our field, modifying them to suit the unique aspects of the space environment. Finally, we develop technologies, tools, and procedures to mitigate the decrements in human performance and capabilities that occur in space environments. When successful, we decrease risks to crew safety and to mission success. When extremely successful (or lucky), we devise generalizable solutions that advance the state of our practice. Our panel is composed of researchers from diverse domains of our project... from different boxes, if you will, of the Human Factors Analysis and Classification System (HFACS).

Kaiser, Mary K.↗
NASA NTRS1993

Analysis and Simulation for a Spotlight-Mode Aircraft SAR in Circular Flight Path

A wide azimuth beam SAR can offer higher resolution or wider azimuth viewing angle; two factors that help better characterize the backscattering property of targets for various science applications. One disadvantage of wide beam SAR is that a much higher pulse repetition frequency (PRF) is usually required since PRF is proportional to the radar beam angle. This problem can be resolved using a spotlight-mode concept: steering a narrow beam SAR to a fixed spot on the ground. The drawback of a spotlight-mode SAR is its limited coverage. A conventional spotlight-mode SAR operates along a straight line path as shown in Figure 1. It can be shown that spotlight-mode SAR that follows a straight line path has difficulty in achieving the ultimate resolution of lambda/4. It also cannot utilize the full 180 degree of azimuth viewing angle that can be attained only when the synthetic aperture length approaches infinity.

Jin, Michael Y.↗
NASA NTRS1978

Helicopter Acoustics

Exterior and interior noise problems are addressed both from the physics and engineering as well as the human factors point of view. The role of technology in closing the gap between what the customers and regulating agencies would like to have and what is available is explored. Noise regulation concepts, design, operations and testing for noise control, helicopter noise prediction, and research tools and measurements are among the topics covered.

Source record↗
NASA NTRS1978

Summary report of the Human Factors Committee

Reduced visibility as a human factors problem was studied in terms of the number of lives lost and cost of aircraft accidents and incidents. Human factors in flight through turbulence in detection and avoidance techniques, pilot and crew procedures for handling workloads and distractions caused by turbulence, and aircraft handling techniques for safe flights through turbulence are investigated. Education and training were reviewed in icing problems on aircraft. Pilots failure to recognize and detect wind shear in severe storms is examined. The pilots avoidance of lightning is discussed from the human factors point of view.

Cooper, G. E.↗
NASA NTRS1983

Impact of digital systems technology on man-vehicle systems research

The present study, based on a NASA technology assessment, examines the effect of new technologies on trends in crew-systems design and their implications from the vantage point of man-vehicle systems research. Those technologies that are most relevant to future trends in crew-systems design are considered along with problems associated with the introduction of rapidly changing technologies and systems concepts from a human-factors point of view. The technologies discussed include information processing, displays and controls, flight and propulsion control, flight and systems management, air traffic control, training and simulation, and flight and resource management. The historical evolution of cockpit systems design is used to illustrate past and possible future trends in man-vehicle systems research.

Bretoi, R. N.↗
NASA NTRS1987

Space station architectural elements model study

The worksphere, a user controlled computer workstation enclosure, was expanded in scope to an engineering workstation suitable for use on the Space Station as a crewmember desk in orbit. The concept was also explored as a module control station capable of enclosing enough equipment to control the station from each module. The concept has commercial potential for the Space Station and surface workstation applications. The central triangular beam interior configuration was expanded and refined to seven different beam configurations. These included triangular on center, triangular off center, square, hexagonal small, hexagonal medium, hexagonal large and the H beam. Each was explored with some considerations as to the utilities and a suggested evaluation factor methodology was presented. Scale models of each concept were made. The models were helpful in researching the seven beam configurations and determining the negative residual (unused) volume of each configuration. A flexible hardware evaluation factor concept is proposed which could be helpful in evaluating interior space volumes from a human factors point of view. A magnetic version with all the graphics is available from the author or the technical monitor.

Taylor, T. C.↗
NASA NTRS1991

Transient modeling/analysis of hyperbolic heat conduction problems employing mixed implicit-explicit alpha method

This paper describes the evaluation of mixed implicit-explicit finite element formulations for hyperbolic heat conduction problems involving non-Fourier effects. In particular, mixed implicit-explicit formulations employing the alpha method proposed by Hughes et al. (1987, 1990) are described for the numerical simulation of hyperbolic heat conduction models, which involves time-dependent relaxation effects. Existing analytical approaches for modeling/analysis of such models involve complex mathematical formulations for obtaining closed-form solutions, while in certain numerical formulations the difficulties include severe oscillatory solution behavior (which often disguises the true response) in the vicinity of the thermal disturbances, which propagate with finite velocities. In view of these factors, the alpha method is evaluated to assess the control of the amount of numerical dissipation for predicting the transient propagating thermal disturbances. Numerical test models are presented, and pertinent conclusions are drawn for the mixed-time integration simulation of hyperbolic heat conduction models involving non-Fourier effects.

Tamma, Kumar K.↗
NASA NTRS2002

The Gas Production Rate and Coma Structure of Comet C/1995 01 (Hale-Bopp)

The University of Wisconsin-Madison and NASA-Goddard conducted a comprehensive multi-wavelength observing campaign of coma emissions from comet Hale-Bopp, including OH 3080 A, [O I] 6300 A, H2O(+) 6158 A, H Balmer-alpha 6563 A, NH2 6330 A, [C I] 9850 A CN 3879 A, C2 5141 A, C3 4062 A, C I 1657 A, and the UV and optical continua. In this work, we concentrate on the results of the H2O daughter studies. Our wide-field OH 3080 A measured flux agrees with other, similar observations and the expected value calculated from published water production rates using standard H2O and OH photochemistry. However, the total [O I] 6300 A flux determined spectroscopically over a similar field-of-view was a factor of 3 - 4 higher than expected. Narrow-band [O I] images show this excess came from beyond the H2O scale length, suggesting either a previously unknown source of [O I] or an error in the standard OH + upsilon to O((sup I)D) + H branching ratio. The Hale-Bopp OH and [O I] distributions, both of which were imaged to cometocentric distances greater than 1 x 10(exp 6) km, were more spatially extended than those of comet Halley (after correcting for brightness differences), suggesting a higher bulk outflow velocity. Evidence of the driving mechanism for this outflow is found in the H(alpha) line profile, which was narrower than in comet Halley (though likely because of opacity effects, not as narrow as predicted by Monte-Carlo models). This is consistent with greater collisional coupling between the suprathermal H photodissociation products and Hale-Bopp's dense coma. Presumably because of mass loading of the solar wind by ions and ions by the neutrals, the measured acceleration of H2O(+) down the ion tail was much smaller than in comet Halley. Tailward extensions in the azimuthal distributions of OH 3080 A, [O I], and [C I], as well as a Doppler asymmetry in the [O I] line profile, suggest ion-neutral coupling. While the tailward extension in the OH can be explained by increased neutral acceleration, the [O I] 6300 A and [C I] 9850 A emissions show 13% and less than 200% excesses in this direction (respectively), suggesting a non-negligible contribution from dissociative recombination of CO(+) and/or electron collisional excitation. Thus, models including the effects of photo-and collisional chemistry are necessary for the full interpretation of these data.

Morgenthaler, Jeffrey P.↗
NASA NTRSDate not supplied

Progress Towards a Common CERES Cloud Mask Algorithm for MODIS and VIIRS: Evaluation using CALIOP Data

For over two decades The Clouds and the Earth’s Radiant Energy System (CERES) project has endeavored to produce a long-term global climate data record for detecting changes in the Earth’s radiation budget and to improve understanding of how clouds contribute to those changes. CERES incorporates cloud information derived from passive narrowband satellite imaging radiometers, and over the course of the project different instruments have contributed to this effort, namely the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometer Suite (VIIRS).Cloud properties have been derived from MODIS on the Aqua satellite for CERES since 2002,and VIIRS on the NOAA-20 satellite launched in 2017 will continue the cloud record once Aqua-MODIS reaches the end of its operational lifetime. However, MODIS and VIIRS have different spectral capabilities and characteristics which complicates our ability to seamlessly transition the record from MODIS to VIIRS. This study evaluates some of the recent algorithm modifications incorporated by the CERES Cloud Working Group towards developing a unified cloud mask algorithm for MODIS and VIIRS that utilizes a set of spectral bands common to both instruments. Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data products are used to evaluate MODIS and VIIRS regional cloud fraction estimates and identify areas where improvements can be made. The cloud mask algorithm relies on computed estimates of cloud-free top-of-atmosphere radiances to differentiate cloudy and cloud-free imager pixels. The unified cloud mask algorithm currently under development uses a reduced number of spectral bands common to both MODIS and VIIRS and so relies on the accuracy of these simulated cloud-free radiances more heavily than predecessor algorithms, i.e., the CERES Edition 4 cloud mask, which use as much spectral information as available on each imager with less consideration for cross-platform consistency. Our validation strategy using CALIOP data is also described. The CALIOP observations are critical for assessing cloud detection accuracies and for independently confirming cloud-free conditions which enables a more robust evaluation of the simulated cloud-free radiances for biases due to factors such as view angle and the spectral dependence of water vapor absorption. These effects are known to differ for the two satellite instruments. Comparisons of MODIS and VIIRS cloud fractions are presented in context with estimates from CALIOP and from the CERES Edition 4 cloud mask algorithm to gauge current progress in developing accurate and consistent MODIS and VIIRS cloud properties for CERES.

CERES↗
NASA NTRS1980

Simulation study of geometric shape factor approach to estimating earth emitted flux densities from wide field-of-view radiation measurements

A study was performed on the use of geometric shape factors to estimate earth-emitted flux densities from radiation measurements with wide field-of-view flat-plate radiometers on satellites. Sets of simulated irradiance measurements were computed for unrestricted and restricted field-of-view detectors. In these simulations, the earth radiation field was modeled using data from Nimbus 2 and 3. Geometric shape factors were derived and applied to these data to estimate flux densities on global and zonal scales. For measurements at a satellite altitude of 600 km, estimates of zonal flux density were in error 1.0 to 1.2%, and global flux density errors were less than 0.2%. Estimates with unrestricted field-of-view detectors were about the same for Lambertian and non-Lambertian radiation models, but were affected by satellite altitude. The opposite was found for the restricted field-of-view detectors.

Weaver, W. L.↗
NASA NTRS2021

Positional Dependence of SNPP VIIRS Solar Diffuser BRDF Change Factor: An Empirical Approach

The Earth-observing Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership satellite regularly performs on-orbit radiometric calibration of its reflective solar bands (RSBs), primarily through observations of an onboard sunlit solar diffuser (SD). The on-orbit change of the SD bidirectional reflectance distribution function (BRDF) value, quantified by a numerical factor called the H-factor, is determined by the onboard SD stability monitor. Our previous study showed that the H-factor is solar angle and view direction dependent. In this study, we determine the dependence of the H-factor on the detector SD view footprint location. We fit an empirical model to the NASA Collection 1 SNPP VIIRS Level 1B (L1B) spectral reflectance difference across the detectors in an RSB over uniform Earth scenes of the Libya 4 desert and deep convective clouds. We apply the model predicted SD positional dependent H-factor to calibrate the RSBs. Under this new calibration scheme, the original unreal striping is removed from the homogeneous Libya 4 desert and the deep convective cloud images, as well as the original unreal striping from the Dunhuang desert image. The SD positional dependent H-factor has been used to calculate the SNPP VIIRS RSB radiometric correction factor for the NASA Collection 2.0 SNPP VIIRS L1B products.

SNPP VIIRS↗
NASA NTRS1990

Bidirectional measurements of surface reflectance for view angle corrections of oblique imagery

An apparatus for acquiring bidirectional reflectance-factor data was constructed and used over four surface types. Data sets were obtained over a headed wheat canopy, bare soil having several different roughness conditions, playa (dry lake bed), and gypsum sand. Results are presented in terms of relative bidirectional reflectance factors (BRFs) as a function of view angle at a number of solar zenith angles, nadir BRFs as a function of solar zenith angles, and, for wheat, vegetation indices as related to view and solar zenith angles. The wheat canopy exhibited the largest BRF changes with view angle. BRFs for the red and the NIR bands measured over wheat did not have the same relationship with view angle. NIR/Red ratios calculated from nadir BRFs changed by nearly a factor of 2 when the solar zenith angle changed from 20 to 50 degs. BRF versus view angle relationships were similar for soils having smooth and intermediate rough surfaces but were considerably different for the roughest surface. Nadir BRF versus solar-zenith angle relationships were distinctly different for the three soil roughness levels. Of the various surfaces, BRFs for gypsum sand changed the least with view angle (10 percent at 30 degs).

Jackson, R. D.↗