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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Sandwiched structural panel having a bi-directional core structure

A structural panel assembly has a bi-directional core structure sandwiched between and secured to a pair of outer side wall members. The core structure is formed from first and second perpendicular series of elongated strip members having crenelated configurations. The strip members in the first series thereof are transversely interwoven with the strip members in the second series thereof in a manner such that crest portions of the strip members in the first series overlie and oppose trough portions of the strip members in the second series, and trough portions of the strip members in the first series underlie and oppose crest portions of the strip members in the second series. The crest portions of all of the strip members lie generally in a first plane and are secured to the inner side of one of the panel assembly outer side walls, and the trough portions of all of the strip members lie generally in a second plane and are secured to the inner side of the other panel assembly outer side wall.

Weddendorf, Bruce↗
NASA NTRS1994

Structural Qualifications of SIR-C Antenna Core Structure

A 2-bay SIR-C Antenna Core Structure(ACS) has been utilized to verify the strength of the SIR-C structural design. Five loading configurations were applied to assure that many SIR-C ACS members were loaded up to more than 1.25 times the predicted flight limit loads.

antenna↗
NASA NTRS1987

CCD photometry of globular cluster core structure. I - NGC 6388, NGC 6624, and M15: One flat core and two cusps

The first results of a major survey of globular cluster core structure are reported. Surface brightness profiles for three clusters are presented: one with a normal flat core profile (NGC 6388), and two with central cusps (NGC 6624 and M15). The profiles are fitted with both seeing-convolved King models and seeing-convolved power laws. A King model provides a reasonable fit to the entire profile of NGC 6388, but there are no acceptable King profiles for NGC 6624 and M15. For these two clusters, a seeing-convolved power law provides a good fit to the inner part of the profile, while a King model gives a good fit to the outer part of the profile. The interpretation of the measured power-law slopes of the central surface brightness cusps of NGC 6624 and M15 are discussed in terms of models for core collapse in a multicomponent cluster.

Lugger, Phyllis M.↗
NASA NTRS1985

Extremely high energy hadron and gamma-ray families(3). Core structure of the halo of superfamily

The study of the core structure seen in the halo of Mini-Andromeda 3(M.A.3), which was observed in the Chacaltaya emulsion chamber, is presented. On the assumption that lateral distribution of darkness of the core is exponential type, i.e., D=D0exp(-R/r0), subtraction of D from halo darkness is performed until the cores are gone. The same quantity on cores obtained by this way are summarized. The analysis is preliminary and is going to be developed.

Yamashita, S.↗
NASA NTRS1990

An enhanced sine dwell method as applied to the Galileo core structure modal survey

An incremental modal survey performed in 1988 on the core structure of the Galileo spacecraft with its adapters with the purpose of assessing the dynamics of the new portions of the structure is considered. Emphasis is placed on the enhancements of the sine dwell method employed in the test. For each mode, response data is acquired at 32 frequencies in a narrow band enclosing the resonance, utilizing the SWIFT technique. It is pointed out that due to the simplicity of the data processing involved, the diagnostic and modal-parameter data is available within several minutes after data acquisition; however, compared with straight curve-fitting approaches, the method requires more time for data acquisition.

Smith, Kenneth S.↗
NASA NTRS1985

Vortex-dominated flow with viscous core structure

Recent theoretical studies of vortex-dominated flows are reviewed with special emphasis on those for which the viscous core structures play an important role. The problems to be described are: The interaction and merging of two-dimensional vortices and of curved vortex filaments, the roll-up and decay of trailing far wakes, and the initiation of vortex breakdown. The analysis utilizes finite-difference solutions of the Navier-Stokes equations complemented by asymptotic expansion techniques.

Liu, C. H.↗
NASA NTRS1995

CCD photometry of globular cluster core structure. 2: U-band profiles for 15 candidate collapsed-core clusters

We present U-band CCD surface brightness profiles for 15 of the 21 globular clusters that have been identified as having collapsed cores by Djorgovski & King (1986). Fourteen of the clusters were observed with the Cerro Tololo 4 m telescope; NGC 7078 was observed with the Canada-France-Hawaii 3.6 m telescope (CFHT). We have fitted the profiles with seeing-convolved power laws, both with and without cores, to assess the evidence for central power-law structure and to place upper limits on core radius r(sub c). We find nine of the clusters (NGC 5946, NGC 6284, NGC 6293, NGC 6325, NGC 6342, NGC 6558, NGC 6624, NGC 6681, and NGC 7078) to have unresolved cores, with upper limits r(sub c) less than or = 1.9 arcsecs. Three of the clusters (NGC 6453, NGC 6522, and NGC 7099) have marginally resolved cores, with upper limits in the range 2.7 arcsecs less than or = r(sub c) less than or = 3.4 arcsecs. The remaining three clusters (NGC 6355, NGC 6397, and NGC 6752) have resolved cores. Of the latter three clusters, NGC 6355 and NGC 6752 are consistent with single-mass King model structure. The median cluster distances are 9.2 kpc for those with unresolved cores, 7.2 kpc for those with marginally resolved cores, and 4.1 kpc for those with resolved cores. The 13 clusters that do not resemble single-mass King models have central power-law structure with surface brightness slopes in the range of d ln S/d ln r = -0.6 to -0.8. These slopes are consistent with the models of Grabhorn et al. (1992) for clusters evolving beyond core collapse. The models include a centrally concentrated population of nonluminous remnants with masses in the range 1.2-1.4 solar mass, thus providing evidence for significant neutron star populations in most of our cluster sample. This finding is consistent with the observation of centrally concentrated low-mass X-ray binary and millisecond pulsar populations in several clusters.

Lugger, Phyllis M.↗
NASA NTRSDate not supplied

Asteroseismic Inversions of Mixed Acoustic-Gravity Modes to Probe the Stellar Core Structure

The discovery of mixed acoustic-gravity modes of oscillations of moderate mass stars opens a unique opportunity to infer the structure of the inner energy-generating cores and thus test the stellar evolution theory. The mixed modes have properties of internal gravity waves (g-modes) in the convectively stable helium core and properties of acoustic modes outside the core. We select several sets of the oscillation mode frequencies in the mass range from about 1.3 to 1.6 solar masses from the Kepler Legacy database, and apply the optimally localized averaging inversion technique previously developed for low-degree helioseismology. The inversion technique takes into account the uncertainties in the determination of the mass and radius of the stars, as well as the surface effects. The methodology provides sensitivity kernels for various structure properties, including the sound speed, density, and Ledoux parameter of convective stability, and, thus, the direct relationship between the stellar properties and the deviation of observed frequencies from the reference models. The inversion results reveal significant deviations in the core structure from the reference models calculated using the MESA evolutionary code for the stellar parameters obtained by the asteroseismic model grid fitting. Our analysis shows that the best resolution of the inner helium core and surrounding shell is achieved in inversions for the Ledoux parameter.

SMD↗
NASA NTRS2021

Evidence of Warm Core Structure Maintenance Over Land: A Case Study Analysis of Cyclone Kelvin

Cyclone Kelvin made landfall in northwest Australia as a category 1 storm on 18 February 2018. After landfall, tropical cyclones typically weaken due to the exhaustion of a moisture supply. Cyclone Kelvin continued to intensify with winds gusting to 100 knots and significant flooding well inland. A distinct eye feature also formed well after landfall. An analysis of meteorological satellite, MERRA2reanalysis, and Global Data Assimilation System (GDAS) data was employedin a case study of Cyclone Kelvin. Using a cyclone phase diagram, it is confirmed that a warm core structure was maintained as Cyclone Kelvin continued to move inland, even through a period of brief inland intensification.

Cyclone Kelvin↗
NASA NTRS1966

Design of thick honeycomb core structures

The demand for weight reduction in flight vehicles suggests the use of lightweight sandwich structures. Several factors must be considered to obtain minimum-weight sandwich constructions. High-strength thin facings combined with lightweight thick core can offer a highly efficient structure when careful consideration is given to practical proportions between facings and core, edge design details, and manufacturing techniques. This paper discusses design approaches to relatively thick-core sandwich constructions. 'A large cylindrical structure subjected to axial compression loading and panel-type structures requiring low deflection under transverse loads are briefly analyzed. The selection of structural adhesives for thick-core structures and manufacturing considerations also are discussed.

SANDWICH CONSTRUCTION↗
NASA NTRS2018

3D Printed Structural Core with MMOD Protection

Deep space exploration requires large habitats for both orbital and surface missions. The weight of a habitat is driven largely by its structure and future vehicles require lighter weight structures to minimize launch mass and cost. Unlike honeycomb core materials used in the past, a 3D printed core can be analyzed and optimized for specific load environments, further cutting down mass of the vehicle. Multi-functional structures can integrate features into the primary structure that are traditionally added mass. MMOD (Micro Meteor and Orbital Debris) protection, for example, can be integrated directly into the primary structure of a habitat. This minimizes the mass of the structure and eliminates the need for additional MMOD layers and attachment hardware. This project seeks to develop 3D printed structural core that can be optimized for flights loads and provide integrated MMOD protection.

Hagen, Richard↗
NASA NTRS1966

Aluminum core structures brazed without use of flux

Aluminum alloy face sheets are brazed to aluminum alloy honeycomb cores without using corrosive flux by means of one or three methods. The completed brazed structure has the high-strength characteristics of heat treated aluminum alloys.

Source record↗
NASA NTRS2003

Warm Core Structure of Hurricane Erin Diagnosed from High Altitude Dropsondes during CAMEX-4

A combination multi-aircraft and several satellite sensors were used to examine the core of Hurricane Erin on September 10, 2001, as part of the CAMEX4 program. During the first set of aircraft passes, around 1700 UTC, Erin was still at its maximum intensity with a central pressure of 969 hpa and windspeed of 105 kts (54 m/s). The storm was moving slowly northwestward at 4 m/s, over an increasingly colder sea surface. Three instrumented aircraft, the NOAA P3 with radar, the NASA ER- 2 at 19 km, newly equipped with GPS dropwindsondes, and the NASA DC-8 with dropwindsondes flew in formation across the eye at about 1700 UTC and again 2.5 hrs later around 1930 UTC. The storm had weakened by 13 m/s between the first and second eye penetrations. The warm core had a maximum temperature anomaly of only 11 C, located at 500 hpa, much weaker and lower than active hurricanes. The core appeared to slant rearward above 400 hpa. Even on the first penetration, airborne radar showed that the eye wall cloud towers were dying. The tops fell short of reaching 15 km and a melting band was found throughout. The tropopause had a bulge to 15.8 km elevation (environment approx. 14.4 km) above the dying convection. A feature of Erin at this timt was a pronounced wave-number-one convective asymmetry with all convective activity being confined to the forward quadrants on the left side of the shear vector as calculated from analyses. This is similar to that predicted by the mesoscale numerical models, which also predict that such small amounts of shear would not affect the storm intensity. In Erin, it is remarkable that relatively small shear produced such a pronounced asymmetry in the convection. In addition, horizontal asymmetries in the low-level warm core were identified. Almost certainly, the colder ocean would kill the tall convective towers feeding the warm core, even if wind shear were absent.

Halverson, J. B.↗
NASA NTRS1977

Design of single-winding energy-storage reactors for dc-to-dc converters using air-gapped magnetic-core structures

A procedure is presented for designing air-gapped energy-storage reactors for nine different dc-to-dc converters resulting from combinations of three single-winding power stages for voltage stepup, current stepup and voltage stepup/current stepup and three controllers with control laws that impose constant-frequency, constant transistor on-time and constant transistor off-time operation. The analysis, based on the energy-transfer requirement of the reactor, leads to a simple relationship for the required minimum volume of the air gap. Determination of this minimum air gap volume then permits the selection of either an air gap or a cross-sectional core area. Having picked one parameter, the minimum value of the other immediately leads to selection of the physical magnetic structure. Other analytically derived equations are used to obtain values for the required turns, the inductance, and the maximum rms winding current. The design procedure is applicable to a wide range of magnetic material characteristics and physical configurations for the air-gapped magnetic structure.

Ohri, A. K.↗
NASA NTRS1989

Rain core structure statistics derived from radar and disdrometer measurements in the mid-Atlantic coast of the US

During a period spanning more than 5 years, low elevation radar measurements of rain were systematically obtained in the mid-Atlantic coast of the U.S. Drop size distribution measurements with a disdrometer were also acquired on the same rain days. The drop size data were utilized to convert the radar reflectivity factors to estimated rain rates for the respective rain days of operation. Applying high level algorithms to the rain data, core values of rain intensities were identified (peak rain rates), and families of rain rate isopleths analyzed. In particular, equicircle diameters of the family of isopleths enveloping peak rain intensities were statistically characterized. The presented results represents the analysis of two rain days, 12 radar scans, corresponding to 430 culled rain rate isopleths from an available data base of 22,000 contours, approximately 100 scans encompassing 17 rain days. The results presented show trends of the average rain rate vs. contour scale dimensions, and cumulative distributions of rain cell dimensions which belong to core families of precipitation.

Goldhirsh, Julius↗
NASA NTRS1985

Core structure of EAS in 10(15) to 10(17) eV

With the use of Akeno calorimeter, the attenuation of particles in concrete is analyzed as the function of the shower size of 10 to the 5th power to 10 to the 7th power. The attenuation length does not depend much on the shower size but depends a little on the shower age. The average value is approx. 150 g/sq cm for s = 0.5 to 0.85 and approx. 40 g/sq cm for s = 0.85 to 1.15. These values and their fluctuations are consistent with the equi-intensity curves of extensive air showers (EAS).

Hara, T.↗