Search NASA⌕ Search

SEARCH · Search NASA

Results for “rapid detection”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Analysis of the Mutual Inductance between Two Parallel Plates for the Detection of Surface Flaws

There has recently been much effort behind the development of NDE methods applicable to the detection of surface/subsurface flaws in thin metallic structures with a rapid scan capability. One such method, an electromagnetic technique using a current-sheet parallel to the surface of a specimen in order to induce eddy current flow shows a high potential for satisfying the rapid scan requirement stated above. The technique is based on the detection of flaw-induced magnetic field components normal to the specimen surface by an appropriate detection mechanism positioned above the current-sheet as shown schematically in Fig. 1. As indicated in this figure, the current-sheet separates the source of the normal magnetic field components from the detector in such a way that the electric and magnetic properties of the current-sheet can be a major factor affecting the strength of the detected signals. The purpose of the present study is, therefore, to perform a detailed investigation on the effect of the material properties of the current-sheet on the detected signal strength and to establish a simple theoretical model for the detection mechanism.

Namking, M.↗
NASA NTRS2010

Development of an In Flight Vision Self-Assessment Questionnaire for Long Duration Space Missions

OVERVIEW A NASA Flight Medicine optometrist teamed with a human factors specialist to develop an electronic questionnaire for crewmembers to record their visual acuity test scores and perceived vision assessment. It will be implemented on the International Space Station (ISS) and administered as part of a suite of tools for early detection of potential vision changes. The goal of this effort was to rapidly develop a set of questions to help in early detection of visual (e.g. blurred vision) and/or non-visual (e.g. headaches) symptoms by allowing the ISS crewmembers to think about their own current vision during their spaceflight missions. PROCESS An iterative process began with a Space Shuttle one-page paper questionnaire generated by the optometrist that was updated by applying human factors design principles. It was used as a baseline to establish an electronic questionnaire for ISS missions. Additional questions needed for the ISS missions were included and the information was organized to take advantage of the computer-based file format available. Human factors heuristics were applied to the prototype and then they were reviewed by the optometrist and procedures specialists with rapid-turn around updates that lead to the final questionnaire. CONCLUSIONS With about only a month lead time, a usable tool to collect crewmember assessments was developed through this cross-discipline collaboration. With only a little expenditure of energy, the potential payoff is great. ISS crewmembers will complete the questionnaire at 30 days into the mission, 100 days into the mission and 30 days prior to return to Earth. The systematic layout may also facilitate physicians later data extraction for quick interpretation of the data. The data collected along with other measures (e.g. retinal and ultrasound imaging) at regular intervals could potentially lead to early detection and treatment of related vision problems than using the other measures alone.

Byrne, Vicky E.↗
NASA NTRS1991

Tactile discrimination and representations of texture, shape, and softness

We present here some of the salient results on the tactual discriminabilities of human subjects obtained through psychophysical experiments, and the associated peripheral neural codes obtained through electrophysiological recordings from monkey single nerve fibers. Humans can detect the presence of a 2 micron high single dot on a smooth glass plate stroked on the skin, based on the responses of Meissner type rapidly adapting fibers (RAs). They can also detect a 0.06 micron high grating on the plate, owing to the response of Pacinian corpuscle fibers. Among all the possible representations of the shapes of objects, the surface curvature distribution seems to be the most relevant for tactile sensing. Slowly adapting fibers respond to both the change and rate of change of curvature of the skin surface at the most sensitive spot in their receptive fields, whereas RAs respond only to the rate of change of curvature. Human discriminability of compliance of objects depends on whether the object has a deformable or rigid surface. When the surface is deformable, the spatial pressure distribution within the contact region is dependent on object compliance, and hence information from cutaneous mechanoreceptors is sufficient for discrimination of subtle differences in compliance. When the surface is rigid, kinesthetic information is necessary for discrimination, and the discriminability is much poorer than that for objects with deformable surfaces.

Srinivasan, M. A.↗
NASA NTRS2013

Aquarius RFI Detection and Mitigation Algorithm: Assessment and Examples

Aquarius is an L-band radiometer system designed to map sea surface salinity from space. This is a sensitive measurement, and protection from radio frequency interference (RFI) is important for success. An initial look at the performance of the Aquarius RFI detection and mitigation algorithm is reported together with examples of the global distribution of RFI at the L-band. To protect against RFI, Aquarius employs rapid sampling (10 ms) and a "glitch" detection algorithm that looks for outliers among the samples. Samples identified as RFI are removed, and the remainder is averaged to produce an RFI-free signal for the salinity retrieval algorithm. The RFI detection algorithm appears to work well over the ocean with modest rates for false alarms (5%) and missed detection. The global distribution of RFI coincides well with population centers and is consistent with observations reported by the Soil Moisture and Ocean Salinity mission.

remote sensing↗
NASA NTRS2018

Evolution of H2O Production in Comet C/2012 S1 (ISON) as Inferred from Forbidden Oxygen and OH Emission

We present H2O production rates for comet C/2012 S1 (ISON) derived from observations of [O I] and OH emission during its inbound leg, covering a heliocentric distance range of 1.8–0.44 AU. Our production rates are in agreement with previous measurements using a variety of instruments and techniques and with data from the various observatories greatly differing in their projected fields of view. The consistent results across all data suggest the absence of an extended source of H2O production, for example sublimation of icy grains in the coma, or a source with spatial extent confined to the dimensions of the smallest projected field of view (in this case < 1000 km). We find that ISON had an active area of around 10 sq km for heliocentric distances Rh > 1.2 AU, which then decreased to about half this value from Rh = 1.2–0.9 AU. This was followed by a rapid increase in active area at about Rh = 0.6 AU, corresponding to the first of three major outbursts ISON experienced inside of 1 AU. The combination of a detected outburst in the light curve and rapid increase in active area likely indicates a major nucleus fragmentation event. The 5–10 sq km active area observed outside of Rh = 0.6 AU is consistent with a 50–100% active fraction for the nucleus, larger than typically observed for cometary nuclei. Although the absolute value of the active area is somewhat dependent on the thermal model employed, the changes in active area observed are consistent among models. The conclusion of a 50–100+% active fraction is robust for realistic thermal models of the nucleus. However the possibility of a contribution of a spatially unresolved distribution of icy grains cannot be discounted. As our [OI]-derived H2O production rates are consistent with values derived using other methods, we conclude that the contribution of O2 photodissociation to the observed [O I] emission is at most 5–10% that of the contribution of H2O for ISON. This is consistent with the expected contribution of O2 photodissociation if O2/H2O ∼ 4%, meaning [O I] emission can still be utilized as a reliable proxy for H2O production in comets as long as O2/H2O ≲ 4%, similar to the abundance measured by the ROSINA instrument on Rosetta at comet 67P/Churyumov–Gerasimenko.

Coma↗
NASA NTRS1989

Ecological study of peat landforms in Canada and Alaska

Over 20 percent of the land surface of Canada and Alaska is covered by peatlands, which may be defined as any waterlogged ecosystem with a minimum thickness of 20 cm of organic matter in the soil. Past investigations have demonstrated the value of aerial photographs in identifying the major vegetation types and analyzing the biotic and hydrogeologic processes that control the development of these peatlands. In the present study, LANDSAT TM imagery was used in conjunction with field studies to determine the utility of this satellite sensor for detecting these important processes. Although the vegetation landforms within these major peat basins are visible on aerial photographs, LANDSAT TM imagery provides essential new evidence for their analysis. Spectral data from the LANDSAT TM system provides: (1) synoptic views of the patterns across large portions of these peat basins, indicating important physiographic controls on peatland development, (2) more sensitive detection of the major vegetation types, allowing rapid quantitative estimates to be made of their distribution and aerial extent, (3) discrimination of bog areas with potentially rapid or slow rates of peat accumulation, (4) identification of discharge zones for groundwater, which apparently represents the most important source of alkalinity in these peat basins, and (5) detection of flow patterns in water tracks that appear nearly uniform on standard aerial photographs.

Glaser, Paul H.↗
NASA NTRS1990

Sensor Detects Overheating Of Perishable Material

Experimental temperature sensor changes color rapidly and irreversibly when temperature rises above pre-determined level. Based on reactions of enzymes in paraffins, blended so mixture melts at temperature considered maximum safe value. Similar devices used to detect temperature abuse, whether foods or medicines refrigerated exposed to excessive temperatures during shipment and storage. By viewing sensor, receiving clerk tells immediately whether product maintained at safe temperatures and acceptable.

Dordick, Jonathan S.↗
NASA NTRS1974

Preparation of remotely-sensed image data for land use planning

Preliminary processing operations required before computer compatible tapes (CCT) can be utilized routinely to realize the full potential of ERTS imagery for rapid mensuration, quantitative estimation and for detecting and monitoring changes over time are described. Geographic referencing, geometric manipulations, classification, and association overlays (as of political boundaries) are discussed.

Bond, A. D.↗
NASA NTRS1977

Long-term behavior of MXB 1730-335

The rapid burster MXB 1730-335 was detected on at least two occasions in 1971 and 1972 by Uhuru, and coverage is available from late 1970 to early 1973. Combined with ANS coverage in 1975 and 1976, as well as published SAS-3 and Ariel-5 observations (1976-1977), a unique record of long-term burst activity is now available for this source. There appear to be burst-active states of approximately one to two months' duration that occur with a duty cycle of about 15%. The burst activity appears to be recurrent with a time scale of roughly 0.5 to 1 year. Implications for burster models are discussed.

Grindlay, J. E.↗
NASA NTRS1981

Satellite-observed cloud-top height changes in tornadic thunderstorms

Eleven tornadic storms are evaluated with respect to cloud top temperature changes relative to tornado touchdown. Digital IR data from the SMS/GOES geosynchronous satellites were employed for 10 F2 and one F1 tornadoes. A rapid ascent of the cloud tops 30-45 min before tornado touchdown, a temperature decrease of 0.4 K/min, and an ascent rate of about 3 m/sec were observed. The presence of an operating Doppler radar for three of the sample storms allowed detection of a mesocyclone coincident with the rapid cloud top ascent. The intensification and descent of the vortex to form a tornado is concluded to be due to a weakening of the updraft, the formation of a downdraft, and a shift of the vortex to the updraft-downdraft boundary, leading to dominance of the tilting term in the generation of vorticity.

Adler, R. F.↗
NASA NTRS1981

A search for apsidal motion in 4U0115+63

The measurement of apsidal motion provides one of the few experimental tests of models of stellar interiors. Binary X-ray pulsars are suited for a potentially important application of the apsidal motion test because of their generally close orbits and the precision with which their orbits can often be measured. The orbit of the X-ray pulsar 4U0115+63 was determined by Rappaport et al. (1978). The orbital parameters were determined with sufficient precision to make possible a measurement of apsidal motion if a second observation of the source could be made. However, 4U0115+63 has not been observed to be active since its 1978 outburst. An analysis has, therefore, been conducted of the archival Uhuru data of the first recorded outburst of this source in early 1971. The results of this analysis are combined with the 1978 observations. It is concluded that apsidal motion would have been detectable if the companion were a rapidly rotating star with a mass not less than 30 solar masses.

Kelley, R. L.↗
NASA NTRS1987

Severe winds in the DFW microburst measured from two aircraft

Advanced analytical methods are applied to the digital flight data and Air Traffic Control radar records from two airliners, Delta flight 191 and American flight 539, that penetrated a microburst at the Dallas/Ft. Worth airport on August 2, 1985. The results for Delta 191 (which crashed) show that the aircraft encountered a strong downburst followed by a strong outflow accompanied by large and rapid changes in the vertical wind. The rapid changes in the vertical wind detected near the ground are attributed to vortex-induced turbulence. The next following aircraft, American 539, made a go-around 110 sec after Delta 191 and traversed the microburst at an altitude of about 2500 ft above the ground. The measured winds during this go-around indicate a broad pattern of downflow in the microburst, with regions of upflow at the extreme edges. The combined results indicate a microburst that was increasing in size with vortex-induced turbulence embedded in a strong outflow near the ground. These wind measurements provide a realistic description of the microburst wind environment that can be used in simulator studies and pilot training, and provide a standard of comparison for ongoing experiments and modeling of microbursts involving vortex rings.

Wingrove, R. C.↗
NASA NTRS1990

A novel representation for planning 3-D collision-free paths

A new scheme for the representation of objects, the successive spherical approximation (SSA), facilitates the rapid planning of collision-free paths in a dynamic three-dimensional environment. The hierarchical nature of the SSA allows collisions to be determined efficiently while still providing an exact representation of objects. The rapidity with which collisions can be detected, less than 1 sec per environment object per path, makes it possible to use a generate-and-test path-planning strategy driven by human conceptual knowledge to determine collision-free paths in a matter of seconds on a Sun 3/180 computer. A hierarchy of rules, based on the concept of a free space cell, is used to find heuristically satisfying collision-free paths in a structured environment.

Bonner, Susan↗
NASA NTRS1993

An x ray scatter approach for non-destructive chemical analysis of low atomic numbered elements

A non-destructive x-ray scatter (XRS) approach has been developed, along with a rapid atomic scatter algorithm for the detection and analysis of low atomic-numbered elements in solids, powders, and liquids. The present method of energy dispersive x-ray fluorescence spectroscopy (EDXRF) makes the analysis of light elements (i.e., less than sodium; less than 11) extremely difficult. Detection and measurement become progressively worse as atomic numbers become smaller, due to a competing process called 'Auger Emission', which reduces fluorescent intensity, coupled with the high mass absorption coefficients exhibited by low energy x-rays, the detection and determination of low atomic-numbered elements by x-ray spectrometry is limited. However, an indirect approach based on the intensity ratio of Compton and Rayleigh scattered has been used to define light element components in alloys, plastics and other materials. This XRS technique provides qualitative and quantitative information about the overall constituents of a variety of samples.

Ross, H. Richard↗
NASA NTRS1996

High-Rate Strong-Signal Quantum Cryptography

Several quantum cryptosystems utilizing different kinds of nonclassical lights, which can accommodate high intensity fields and high data rate, are described. However, they are all sensitive to loss and both the high rate and the strong-signal character rapidly disappear. A squeezed light homodyne detection scheme is proposed which, with present-day technology, leads to more than two orders of magnitude data rate improvement over other current experimental systems for moderate loss.

Yuen, Horace P.↗
NASA NTRS2003

Interaction of Comets and the Solar Wind

We had originally planned to analyze UVCS observations of Comet Machholz, but we obtained higher quality observations of Comet Kudo-Fujikawa in January 2003 at its 0.19 AU perihelion. Besides a large and rapidly increasing water outgassing rate, we detected a bright tail in doubly ionized carbon. The amount of carbon was greater than could be accounted for by GO photodissociation, and we attribute the carbon to evaporation of organics from dust. A spectacular disconnection event was apparent in the C III tail, and it coincides within the uncertainties with the position of the heliospheric current sheet. A paper is in press in Science, and it will be the subject of a press release. We are also analyzing two sungrazing comets. Comet C/2001 C2 shows evidence for sub-fragments and for a very long lasting source of neutrals, which we tentatively identify as evaporation of pyroxene dust grains. Comet C/2002 S2 shows a sudden 2 magnitude drop in optical brightness and an equally sudden recovery. UVCS observations during that time show a steadily increasing outgassing rate. We have derived solar wind densities for both comets, but we are still sorting out the ambiguities involving the fragmentation and optical behavior. We are collaborating with Philippe Lamy on the LASCO measurements.

Wagner, William↗
NASA NTRS2004

Interaction of Comets and the Solar Wind

The analysis of Comet Kudo-Fujikawa at perihelion was published and picked up by Der Spiegel. Besides a large and rapidly increasing water outgassing rate, we detected a bright tail in doubly ionized carbon. The amount of carbon was greater than could be accounted for by CO photodissociation, and we attribute it to evaporation of organics from dust. A spectacular disconnection event was apparent in the C III tail, and it coincides within the uncertainties to the position of the heliospheric current sheet. The analysis of the sungrazing comet C2001 C2 is in press. It showed evidence for subfragments and for a very long lasting source of neutrals, which we identify as evaporation of pyroxene dust grains. Results were also presented at COSPAR. We are working on observations of another sungrazer, comet C2002 S2, which shows a sudden 2 magnitude drop in optical brightness and an equally sudden recovery. UVCS observations during that time show a steadily increasing outgassing rate. We have derived solar wind densities for both comets, but we are still sorting out the ambiguities involving the fragmentation and optical behavior.

Wagner, William↗