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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Study of supersonic intersection flowfield at modified wing-body junctions

The problem of supersonic flow control using fillets and sweep for a wing-body junction has been investigated numerically using a three-dimensional Navier-Stokes code, which employs the MacCormack's time-split finite volume technique. An elliptic grid generation technique with direct control over spacing has been developed for constructing the grid at a filleted wing-body junction. The computed results for pressure distribution, particle paths, and limiting streamlines on the flat plate and fin surface for a swept fin show a decrease in the peak pressure on the fin leading edge and in the extent of the separated flow region. Moreover, the results for filleted juncture clearly show that the flow streamline patterns lose much of their vortical character with proper filleting. It has been demonstrated that fillets with a radius of three-and-one-half times the fin leading-edge diameter are required to weaken the vorticity in the horseshoe vortex by a factor of three for the Mach number and Reynolds number considered in the present study.

Lakshmanan, B.↗
NASA NTRS1995

The orbital characteristics of debris particle rings as derived from IDE observations of multiple orbit intersections with LDEF

During the first 346 days of the LDEF's almost 6 year stay in space, the metal oxide silicon detectors of the Interplanetary Dust Experiment (IDE) recorded over 15,000 impacts, most of which were separated in time by integer multiples of the LDEF orbital period (called multiple orbit event sequences, or MOES). Simple celestial mechanics provides ample reason to expect that a good deal of information about the orbits of the impacting debris particles can be extracted from these MOES, and so a procedure, based on the work of Greenberg, has been developed and applied to one of these events, the so-called 'May swarm'. This technique, the 'Method of Differential Precession,' allows for the determination of the geometrical elements of a particle orbit from the change in the position of the impact point with time. The application of this approach to the May swarm gave the following orbital elements for the orbit of the particles striking LDEF during this MOES: a = 6746.5 km; 0.0165 less than e less than 0.025; i = 66.55 deg; Omega(sub 0) = 179.0 deg plus or minus 0.2 deg; omega = 178.1 deg plus or minus 0.2 deg.

Cooke, William J.↗
NASA NTRS2002

Small Objects in Low-Earth Intersecting Ground-Based Laser Radar Operational Envelopes

NASA/Marshall Space Flight Center, in collaboration with the Air Force Research Laboratory/Directed Energy Directorate, is considering a series of experiments to demonstrate small object tracking capability. One such experiment involves a microsatellite, about 25 cm in diameter, which will be deployed from a Space Shuttle Hitchhiker canister or from an Air Force vehicle. The High Performance CO2 Ladar Surveillance Sensor (HI-CLASS) and the Advanced Electro-Optics System (AEOS) will be used to detect the micro-satellite. The goal of this paper is to determine the number of times per day that a micro-satellite orbiting at a known altitude and inclination will be visible to the laser radar, and the length of time that the micro-satellite will be visible on each pass.

Dona V. Boccio↗
NASA NTRS2003

Field Effect Flow Control in a Polymer T-Intersection Microfluidic Network

We present a study of induced pressure pumping in a polymer microchannel due to differential electroosmotic flow @OF) rates via field-effect flow control (FEFC). The experimental results demonstrate that the induced pressure pumping is dependent on the distance of the FEFC gate from the cathodic gate. A proposed flow model based on a linearly-decaying zeta potential profile is found to successfully predict experimental trends.

Sniadecki, Nathan J.↗
NASA NTRS1995

At the intersection of automation and culture

The crash of an automated passenger jet at Nagoya, Japan, in 1995, is used as an example of crew error in using automatic systems. Automation provides pilots with the ability to perform tasks in various ways. National culture is cited as a factor that affects how a pilot and crew interact with each other and equipment.

NASA Discipline Space Human Factors↗
NASA NTRS1996

The intersection of risk assessment and neurobehavioral toxicity

Neurobehavioral toxicology is now established as a core discipline of the environmental health sciences. Despite its recognized scientific prowess, stemming from its deep roots in psychology and neuroscience and its acknowledged successes, it faces additional demands and challenges. The latter, in fact, are a product of its achievements because success at one level leads to new and higher expectations. Now the discipline is counted upon to provide more definitive and extensive risk assessments than in the past. These new demands are the basis for the appraisals presented in the SGOMSEC 11 workshop. They extend beyond what would be offered in a primer of methodology. Instead, these appraisals are framed as issues into which what are usually construed as methodologies have been embedded.

NASA Discipline Environmental Health↗
NASA NTRS2008

Evidence for Intersections of Coupled g-Mode Sets as a Source of High Frequency Oscillations in Sunspot Occurrence

We show that sunspots tend to appear at longitudes where coupled sets of g-mode oscillations are depositing the most energy. Since the g-mode sets rotate at predictable rates slower than the Sun, the same predictability should eventually apply to the location and strength of sunspots and other solar activity. When fully developed, this model would provide long term safety warnings for astronauts. In this paper, the rotation rates and initial longitudes of eleven g-mode sets are tested against observations. The paper concludes that the time series of sunspot numbers for the last century has oscillatory components with the same frequencies and temporal phases as the eleven g-mode sets.

Juckett, David A.↗
NASA NTRS2010

Composite intersection reinforcement

An assembly and method for manufacturing a composite reinforcement for unitizing a structure are provided. According to one embodiment, the assembly includes a base having a plurality of pins extending outwardly therefrom to define a structure about which a composite fiber is wound to define a composite reinforcement preform. The assembly also includes a plurality of mandrels positioned adjacent to the base and at least a portion of the composite reinforcement preform, and a cap that is positioned over at least a portion of the plurality of mandrels. The cap is configured to engage each of the mandrels to support the mandrels and the composite reinforcement preform during a curing process to form the composite reinforcement.

Misciagna, David T.↗
NASA NTRS2011

Portable Runway Intersection Display and Monitoring System

Systems, methods and apparatus are provided through which an apparatus located on an airfield provides information to pilots in aircraft on the ground and simultaneously gathers information on the motion and position of the aircraft for controllers.

Dabney, Richard W.↗
NASA NTRS2013

Composite Intersection Reinforcement

An assembly and method for manufacturing a composite reinforcement for unitizing a structure are provided. According to one embodiment, the assembly includes a base having a plurality of pins extending outwardly therefrom to define a structure about which a composite fiber is wound to define a composite reinforcement preform. The assembly also includes a plurality of mandrels positioned adjacent to the base and at least a portion of the composite reinforcement preform, and a cap that is positioned over at least a portion of the plurality of mandrels. The cap is configured to engage each of the mandrels to support the mandrels and the composite reinforcement preform during a curing process to form the composite reinforcement.

Misciagna, David T.↗
NASA NTRS2017

The Velocity and Density Distribution of Earth-Intersecting Meteoroids: Implications for Environment Models

Meteoroids are known to damage spacecraft: they can crater or puncture components, disturb a spacecraft's attitude, and potentially create secondary electrical effects. Because the damage done depends on the speed, size, density, and direction of the impactor, accurate environment models are critical for mitigating meteoroid-related risks. Yet because meteoroid properties are derived from indirect observations such as meteors and impact craters, many characteristics of the meteoroid environment are uncertain. In this work, we present recent improvements to the meteoroid speed and density distributions. Our speed distribution is derived from observations made by the Canadian Meteor Orbit Radar. These observations are de-biased using modern descriptions of the ionization efficiency. Our approach yields a slower meteoroid population than previous analyses (see Fig. 1 for an example) and we compute the uncertainties associated with our derived distribution. We adopt a higher fidelity density distribution than that used by many older models. In our distribution, meteoroids with TJ less than 2 are assigned to a low-density population, while those with TJ greater than 2 have higher densities (see Fig. 2). This division and the distributions themselves are derived from the densities reported by Kikwaya et al. These changes have implications for the environment: for instance, the helion/antihelion sporadic sources have lower speeds than the apex and toroidal sources and originate from high-T(sub J) parent bodies. Our on-average slower and denser distributions thus imply that the helion and antihelion sources dominate the meteoroid environment even more completely than previously thought. Finally, for a given near-Earth meteoroid cratering rate, a slower meteoroid population produces a comparatively higher rate of satellite attitude disturbances.

Moorhead, A. V.↗