SEARCH · Engineering Papers

Results for “Location Of Events”

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.

SourceResearch connectionFrom yearThrough year

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

At least 721 records · Page 40

All sources NASA NTRS DOE OSTI

NASA NTRS1986

Detection of emetic activity in the cat by monitoring venous pressure and audio signals

To investigate the use of audio signals as a simple, noninvasive measure of emetic activity, the relationship between the somatic events and sounds associated with retching and vomiting was studied. Thoracic venous pressure obtained from an implanted external jugular catheter was shown to provide a precise measure of the somatic events associated with retching and vomiting. Changes in thoracic venous pressure monitored through an indwelling external jugular catheter with audio signals, obtained from a microphone located above the animal in a test chamber, were compared. In addition, two independent observers visually monitored emetic episodes. Retching and vomiting were induced by injection of xylazine (0.66mg/kg s.c.), or by motion. A unique audio signal at a frequency of approximately 250 Hz is produced at the time of the negative thoracic venous pressure change associated with retching. Sounds with higher frequencies (around 2500 Hz) occur in conjunction with the positive pressure changes associated with vomiting. These specific signals could be discriminated reliably by individuals reviewing the audio recordings of the sessions. Retching and those emetic episodes associated with positive venous pressure changes were detected accurately by audio monitoring, with 90 percent of retches and 100 percent of emetic episodes correctly identified. Retching was detected more accurately (p is less than .05) by audio monitoring than by direct visual observation. However, with visual observation a few incidents in which stomach contents were expelled in the absence of positive pressure changes or detectable sounds were identified. These data suggest that in emetic situations, the expulsion of stomach contents may be accomplished by more than one neuromuscular system and that audio signals can be used to detect emetic episodes associated with thoracic venous pressure changes.

A Nagahara↗

NASA NTRS1999

Jet Mixing Enhancement by Feedback Control

The objective of this work has been to produce methodologies for high speed jet noise reduction based on natural mechanisms and enhanced feedback control to affect frequencies and structures in a prescribed manner. In this effort the two-point hot wire measurements obtained in the Langley jet facility by Ukeiley were used in conjuction with linear stochastic estimation (LSE) to implement the LSE component of the complementary technique. This method combines the Proper Orthogonal Decomposition (POD) and LSE to provide an experimental low dimensional time dependent description of the flow field. From such a description it should be possible to identify short time high strain rate events in the jet which contribute to the noise. The main task completed for this effort is summarized: LSE experiments were performed at the downstream locations where the two point hot wire measurements have been obtained by Ukeiley. These experiments involved sampling simultaneously hot wire signals from a relatively course spatial grid in gamma and theta. From this simultaneous data, coupled with the two-point measurements of Ukeiley via the LSE components of the complementary technique, an experimental low dimensional description of the jet at 4, 5, 6, 7 and 8 diameters downstream was obtained for Mach numbers of 0.3 and 0.6. We first present an overview of the theory involved. We finish up with a statement of the work performed and finally provide charts from a 1999 APS talk which summarizes the results.

Glauser, Mark↗

NASA NTRS2004

Major and Trace Element Variations in Impact Crater Clay from Chicxulub, Lonar, and Mistastin, Implications for the Martian Soil

The catastrophic Chicxulub event should have generated a large hydrothermal system with volatile element mobilization, producing interesting alteration materials and clays. The Yaxcopoil-1 (YAX) drill hole is located in the annular trough, about 70 km southwest of the crater center, in an area where the impactite layers are relatively thin (approx. 100 m thick). We have analyzed samples from the YAX drill core and from other impact craters including Mistastin and Lonar to determine the nature of alteration and trace element mobilization.

Newsom, H. E.↗

NASA NTRS2004

The Use of LS-DYNA in the Columbia Accident Investigation and Return to Flight Activities

During the launch of the Space Shuttle Columbia on January 16, 2003, foam originating from the external tank impacted the shuttle's left wing 81 seconds after lift-off. Then on February 1st, Space Shuttle Columbia broke-up during re-entry. In the weeks that followed, the Columbia Accident Investigation Board had formed various teams to investigate every aspect of the tragedy. One of these teams was the Impact Analysis Team, which was asked to investigate the foam impact on the wing leading edge. This paper will describe the approach and methodology used by the team to support the accident investigation, and more specifically the use of LS-DYNA for analyzing the foam impact event. Due to the success of the analytical predictions, the impact analysis team has also been asked to support Return to Flight activities. These activities will analyze a far broader range of impact events, but not with just foam and not only on the wing leading edge. The debris list has expanded and so have the possible impact locations. This paper will discuss the Return to Flight activities and the use of LS-DYNA to support them.

Gabrys, Jonathan↗

NASA NTRS2003

IGP Services

The goal is location-independent computing. Implementing a set of services to satisfy this goal, build upon the GLOBUS toolkit services, and implementing with OGSA. Current status includes: Event service, Job manager, Resource selector and Broker, Next versions in development.Development includes: Monitoring and testing, Portability manager, Performance prediction, Dynamic accounting, and MDS evaluation.

Smith, Warren↗

NASA NTRS2006

A Probable Taurid Impact on the Moon

On November 7, 2005, at 23:41:52 UT, observers located at the Marshall Space Flight Center captured the flash produced by a kilogram-size meteoroid striking the lunar surface. Photometric analysis of the event video, combined with the plausible assumptions of a luminous efficiency of 2x10" and that the meteoroid was a member of the Taurid meteoroid stream, yield a striking power of approximately 640 lbs of TNT and a mass of approximately 3.8 kg. Even though no confirming independent observations are known to exist, there is high confidence in the impact origin of the flash; reasonable attempts have been made to eliminate other possibilities, such as cosmic ray hits on the CCD and glints from satellites that may have crossed the lunar disk near the impact time.

Cooke, William J.↗

NASA NTRS2015

When the Sky Falls: Performing Initial Assessments of Bright Atmospheric Events

The 2013 Chelyabinsk super bolide was the first "significant" impact event to occur in the age of social media and 24 hour news. Scientists, used to taking many days or weeks to analyze fireball events, were hard pressed to meet the immediate demands (within hours) for answers from the media, general public, and government officials. Fulfilling these requests forced many researchers to exploit information available from various Internet sources - videos were downloaded from sites like Youtube, geolocated via Google Street View, and quickly analyzed with improvised software; Twitter and Facebook were scoured for eyewitness accounts of the fireball and reports of meteorites. These data, combined with infrasound analyses, enabled a fairly accurate description of the Chelyabinsk event to be formed within a few hours; in particular, any relationship to 2012 DA14 (which passed near Earth later that same day) was eliminated. Results of these analyses were quickly disseminated to members of the NEO community for press conferences and media interviews. Despite a few minor glitches, the rapid initial assessment of Chelyabinsk was a triumph, permitting the timely conveyance of accurate information to the public and the incorporation of social media into fireball analyses. Beginning in 2008, the NASA Meteoroid Environments Office, working in cooperation with Western's Meteor Physics Group, developed processes and software that permit quick characterization - mass, trajectory, and orbital properties - of fireball events. These tools include automated monitoring of Twitter to establish the time of events (the first tweet is usually no more than a few seconds after the fireball), mining of Youtube and all sky camera web archives to locate videos suitable for analyses, use of Google Earth and Street View to geolocate the video locations, and software to determine the fireball trajectory and object orbital parameters, including generation of animations suitable for popular media and presentations. This presentation will give a short description of the characterization procedure and show applications of the tools, which have become vital to answering the question of "What was that bright light in the sky?" in the post-Chelyabinsk, 24/7 news world.

Cooke, William J.↗

NASA NTRS1993

(abstract) The Impactor Flux in the Pluto-Charon System

The impactor flux on Pluto and Charon consists of long-period comets from the Oort cloud passing through the region, and intermediate-period comets evolving inward to (or outward from) short-period orbits. The source of the intermediate-period comets is likely an extended disk of remnant planetesimals beyond the orbit of Neptune, commonly referred to as the Kuiper belt, though the Oort cloud may be an additional source of some short-period comets. The Pluto-Charon system actually circulates within the Kuiper belt, and with an aphelion of 49.3 AU, moves through a region where remnant planetesimal orbits would likely be stable over the age of the solar system. The recent discovery of two objects at Kuiper belt distances, 1992 QB 1 and 1993 FW, and the fact that the orbit determined for 1992 QB 1 is likely of low eccentricity and low inclination, have provided strong observational evidence for the Kuiper belt. Weisman et al (1989) showed that, for the expected number of objects in the Kuiper belt necessary to provide the short-period comet flux, cometary cratering on Pluto and Charon is dominated by Kuiper belt comets. We will provide updated estimates of the numbers, based on an improved understanding of Oort cloud and Kuiper belt dynamics since 1989, and on improved estimates for the radii and masses for Pluto and Charon. Because Pluto and Charon actually penetrate the stable region of the Kuiper belt beyond 40 AU, expected cratering rates for the pair are substantially higher than for Triton, which is located at the inner edge of the Kuiper belt. However, the Pluto-Charon system is tidally evolved and this may have led to resurfacing events at various times in its history. Thus, detailed predictions of the integrated crater density or comparisons with Triton are not very meaningful without a knowledge of that history. Differences in the suspected compositions of Pluto and Charon may also lead to different surface rheologies and thus, different retention times for cratered surfaces.

Pluto↗

NASA NTRS1998

SGR 1627-41

BATSE has detected repeated soft gamma-ray bursts consistent with the same (previously unknown) location. We recorded three bursts on June 15.109, 15.296, 15.411 UT (BATSE triggers 6825, 6826, 6827, respectively) with an average duration of about 200 milliseconds. Preliminary spectral analysis of the data indicates that the events are very soft, with power law spectral indices varying between -3.0 and -7.0. BATSE triggered 5 more times, on June 17.873,17.901, 18.004, 18.035, and 18.071 UT (BATSE trigger numbers 6833, 6834, 6835, 6836 and 6837, respectively). The last trigger had a peak count rate of over 300000 counts/sec above background (integrated over 4 detectors between 20-1000 keV, in 1 second interval) and a duration of about 3 seconds. Due to Rs very high peak intensity, deadtime effects prevent us from using it for localization, until we receive more data types. The weighted location of the 7 remaining triggers is centered on R.A. = 16h27ml2.0s and dec = -41 d06.0' with an error radius of about 2 degrees. This location does not correspond to any previously known SGR source; we conclude that we have discovered a new source, SGR1627-41. We have initiated an RXTE ToO and we strongly encourage wide field observations at other wavelengths.

Kouveliotou, Chryssa↗

NASA NTRS2004

Extravehicular Mobility Unit Training Suit Symptom Study Report

The purpose of this study was to characterize the symptoms and injuries experienced by NASA astronauts during extravehicular activity (space walk) spacesuit training at the Neutral Buoyancy Laboratory at Ellington Field, Houston, Texas. We identified the frequency and incidence rates of symptoms by each general body location and characterized mechanisms of injury and effective countermeasures. Based on these findings a comprehensive list of recommendations was made to improve training, test preparation, and current spacesuit components, and to design the next -generation spacesuit. At completion of each test event a comprehensive questionnaire was produced that documented suit symptom comments, identified mechanisms of injury, and recommended countermeasures. As we completed our study we found that most extravehicular mobility unit suit symptoms were mild, self-limited, and controlled by available countermeasures. Some symptoms represented the potential for significant injury with short- and long-term consequences regarding astronaut health and interference with mission objectives. The location of symptoms and injuries that were most clinically significant was in the hands, shoulders, and feet. Correction of suit symptoms issues will require a multidisciplinary approach to improve prevention, early medical intervention, astronaut training, test planning, and suit engineering.

Strauss, Samuel↗

NASA NTRS2010

Sun-Earth Day - Teaching Heliophysics Through Education Technology

Sun-Earth Day (SED) is an Education and Outreach program supported by the U.S, National Aeronautics and Space Administration (NASA). The intent of the program is to teach students and the general public about Heliophysics (the science of the study of the Sun, how it varies, and how solar dynamics affect the rest of the solar system, especially the Earth). The program was begun ten years ago. Each year since that time a particular day has been designated as "Sun-Earth Day ,,. Usually the day of the spring equinox (March 20 or 21) is Sun-Earth Day, but other days have been used as well. Each year a theme is chosen relating to Heliophysics and events reflecting that theme are planned not only for Sun-Earth Day, but for the entire year. From the very beginning educational technology was emphasized in the events in order to effectively reach wide audiences with the SED message. The main approach has been to have a "webcast" related to each year's theme, often from a location that supports the theme as well. For example, a webcast took place from the Mayan pyramids at Chichen Itza, Mexico to highlight the theme of "Ancient Observatories, Timeless Knowledge". Webcasts were not the only technology employed, however. Many of the themes centered on the dynamic nature of the Sun and the effects that solar storms can have on interplanetary space and in our day-to-day life on Earth. Activities for tracking when solar storms happen and how they affect the Earth were developed and brought together in an educational package called Space Weather Action Centers. This project is explained in more detail in another presentation in this session being given by Norma Teresinha Oliveira Reis. Recent Sun-Earth Days have utilized "social networking" technologies to reach widespread groups on the internet. Podcasts, Vodcasts, Facebook, Twitter, and Second Life are the types of network technologies being employed now. The NASA Distance learning Network is another method for bringing Sun-Earth Day events and training to widespread educators and classrooms in order to magnify the reach of Sun-Earth Day. Examples of the technologies will be shown along with an assessment of their effectiveness.

Thieman, J.↗

NASA NTRS2012

Persistent, Widespread Pulsating Aurora: A Case Study

Observations of a pulsating aurora event occurring on February 11, 2008, using the THEMIS all-sky imager array, indicate a spatially and temporally continuous event with a duration of greater than 15 hours and covering a region with a maximum size of greater than 9 hours MLT. The optical pulsations are at times locally interrupted or drowned out by auroral substorm activity, but are observed in the same location once the discrete aurora recedes. The pulsations following the auroral breakup appear to be brighter and have a larger patch size than pre-substorm. This suggests that, while the onset of pulsating aurora is not necessarily dependent upon a substorm precursor, the pulsations are affected and possibly enhanced by the substorm process. The long duration of such pulsating aurora events, enduring for several hours without interruption, is far longer than the expected recovery phase of a substorm, suggesting that pulsating aurora is not strictly a recovery phase phenomenon.

Jones, S. L.↗

NASA NTRS1984

A comparative study of aerosol extinction measurements made by the SAM II and SAGE satellite experiments

SAM II and SAGE are two satellite experiments designed to measure stratospheric aerosol extinction using the technique of solar occultation or limb extinction. Although each sensor is mounted aboard a different satellite, there are occasions when their measurement locations are nearly coincident, thereby providing opportunities for a measurement comparison. In this paper, the aerosol extinction profiles and daily contour plots for some of these events in 1979 are reported. The comparisons shown in this paper demonstrate that SAM II and SAGE are producing similar aerosol extinction profiles within their measurement errors and that since SAM II has been previously validated, these results show the validity of the SAGE aerosol measurements.

Yue, G. K.↗

NASA NTRS1985

A summary of whistlers observed by Voyager 1 at Jupiter

We summarize the Voyager 1 observations of whistlers at Jupiter in order to provide a basis for further analyses of the density profile of the Io plasma torus as well as to support studies of atmospheric lightning at Jupiter. All the whistlers detected by Voyager 1 fell into three general regions in the torus at radial distances ranging beteen 5 and 6 R sub J. An analysis of the broadband wave amplitudes measured by the Voyayer 1 plasma wave instrument and estimates of the peak whistler amplitudes imply the grouping of whistlers was due to variations in the sensitivity of the receiver to whistlers and not to variations in the source or propagation paths of the whistlers. The whistler dispersions are presented in statistical form for each of the three groups of events and analyzed in view of the structure of the Io plasma torus as determined by plasma probe measurements. The results of these analyses give source locations for the whistlers at the foot of the magnetic field lines threading the torus in both hemispheres and over a range of longitudes.

Kurth, W. S.↗

NASA NTRS1985

On-orbit attitude control of the Cosmic Background Explorer (COBE)

The way in which COBE (launched by the SS in late 1982) performs its attitude control is described, along with the design of its on-orbit system. COBE, to be situated in a 900 km high, sun-synchronous orbit, contains two unique control features: (1) the orientation of the spinning satellite is controlled to a sun-normal attitude in the sun/local vertical plane; and (2) pitch and roll control is maintained by a unique triaxial arrangement of reaction wheels, magnetic torque bars and sensors, located in the body's tranverse plane. Inherent in this triaxial configuration concept is a built-in redundancy that will maintain attitude control in the event of any single-point sensor/actuator component failure. Each of the three control drive electronics operates independently and directly of a system of dedicated sensors. This system functions independently of a computer or an ephemeris communication link, leading to greater reliability.

Bramberg, B.↗

NASA NTRS1988

Interaction between high-velocity pulsar in CTB80 and an infrared emission shell

During a survey of infrared emission detected by IRAS from shock-heated dust associated with Galactic SNRs, a roughly 1 deg diameter supernova remnant shell centered 30 arcmin east of SNR CTB80's core was discovered. The pulsar's projected location inside this infrared emission shell, together with similar distance and age estimates, suggest that both the shell and pulsar were produced by the same supernova event. It is proposed that the interaction between the pulsar's energetic particle emission and the shell's compressed interstellar magnetic field can explain CTB80's remarkable radio structure, and the implications of such pulsar/SNR interactions are discussed.

Fesen, Robert A.↗

NASA NTRS1992

Mechanical properties of glasses impacted by debris or micrometeorites

Mechanical strength measurements on five glasses and one glass ceramic exposed on the Long Duration Exposure Facility (LDEF) have revealed no damage exceeding experimental limits of error after exposure. The measurement technique subjected less than 5 percent of the sample surface area to stresses above 90 percent of the failure strength. Seven micrometeorite or space debris impacts occurred at locations which were not in that portion of the sample subjected to greater than 90 percent of the applied stress. In consequence of this, the impact events on the sample were not detected in mechanical strength measurements. The physical form and structure of the impact sites was carefully examined to determine the influence of those events upon stress concentration associated with the impact and the resulting mechanical strength influence. The size of the impact site insofar as it determines flaw size for fracture purposes was examined. Surface topography of the impacts reveals that six of the seven sites display impact melting. The classical melt crater structure is surrounded by a zone of fractured glass. Residual stresses arising from shock compression and from cooling of the impact fused zone cannot be included in fracture mechanics analyses based on simple flaw size analyses. Strategies for refining estimates of mechanical strength degradation by impact events are presented.

Kinser, Donald L.↗

NASA NTRS1991

Post-asymptotic giant branch nonradial instability strips

Stability analyses are performed for nonradial g(+)-mode pulsations of postasymptotic AGB stellar models to determine the location of their pulsational instability strips in the Hertzsprung-Russell diagram. Stellar models are analyzed that are assumed to have undergone a major mass loss event either near the tip of the AGB or shortly thereafter and, therefore, consist of a 50-percent carbon 50-percent oxygen core. Their mass is 0.6 solar mass, which is in good agreement with the peak of the observed distribution of white dwarf masses. The results are compared both to the observed planetary nebula nuclei variables and the hot pulsating DO variables. An analysis is also presented of the stability of DB white dwarfs, which have much deeper and stronger convection zones, and an instability strip is found between about 18,000 and 26,000 K approximately as observed for the known variable stars.

Stanghellini, Letizia↗