Search NASA⌕ Search

SEARCH · Search NASA

Results for “phase analysis”

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 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

STAT7 v2.0 User Guide

The STAT7 software was developed to perform steady-state, single-phase thermal hydraulics analysis of plate-fueled reactors based on statistical propagation of uncertainties. Application of the software includes non-power research and test reactor analysis, and it has been used for the conversion to low- enriched uranium fuel of U.S. High Performance Research Reactors such as the Massachusetts Institute of Technology Research Reactor. Since it can be necessary to repeat reactor safety analysis, such as during fuel reloading, STAT7 accommodates flexibility in analyzing many practical aspects of reactor fuel management. STAT7 uses a Monte Carlo approach to model uncertainty in common fuel fabrication parameters and other key reactor operating parameters required for reactor thermal hydraulics analysis. These safety calculations are ultimately intended to protect against high fuel plate temperatures due to critical heat flux, or onset of flow instability. STAT7 supports water properties based on the IAPWS-IF97 functions (The International Association for the Properties of Water and Steam Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam) in addition to fitted functions. STAT7 predicts axial profiles of fuel, cladding, and coolant temperature along a lateral stripe that runs the full length of the fuel plate from the bottom to the top. STAT7 can simultaneously analyze every axial node in each lateral stripe of all fuel plates and coolant channels in every fuel element of an entire reactor core. Power splits are calculated for each axial node of each plate to determine how much of the power goes out each face of the plate. In a single execution, STAT7 can be used to perform full core analysis by analyzing the margin to onset of nucleate boiling and onset of flow instability for each axial node of each stripe of each plate of each fuel element in the core.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Material Characterization Report of FFTF MFF 5 Fuel Element

This report was written as part of the TerraPower Cooperative Research and Development Agreement No. 11-CR-19 with Idaho National Laboratory. TerraPower provided the funding. An as-fabricated fuel element from the Fast Flux Test Facility MFF-5 experiment was sectioned and analyzed for material properties. Results reported include phase characterization, microstructural analysis, density, microhardness, and chemical composition.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

THE SHORT ROTATION PERIOD OF HI’IAKA, HAUMEA’S LARGEST SATELLITE

Hi’iaka is the larger outer satellite of the dwarf planet Haumea. Using relative photometry from the Hubble Space Telescope and Magellan and a phase dispersion minimization analysis, we have identified the rotation period of Hi’iaka to be ∼9.8 hr (double peaked). This is ∼120 times faster than its orbital period, creating new questions about the formation of this system and possible tidal evolution. The rapid rotation suggests that Hi’iaka could have a significant obliquity and spin precession that could be visible in light curves within a few years. We then turn to an investigation of what we learn about the (currently unclear) formation of the Haumea system and family based on this unexpectedly rapid rotation rate. We explore the importance of the initial semimajor axis and rotation period in tidal evolution theory and find that they strongly influence the time required to despin to synchronous rotation, relevant to understanding a wide variety of satellite and binary systems. We find that despinning tides do not necessarily lead to synchronous spin periods for Hi’iaka, even if it formed near the Roche limit. Therefore, the short rotation period of Hi’iaka does not rule out significant tidal evolution. Hi’iaka’s spin period is also consistent with formation near its current location and spin-up due to Haumea-centric impactors.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

On the role of the ΩΓ limit in the formation of population III massive stars

We explore the role of the modified Eddington limit due to rapid rotation (the so-called ΩΓ limit) in the formation of Population III stars. We performed one-dimensional stellar evolution simulations of zero-metallicity protostars accreting mass at a very high rate ( M-dot ∼10{sup −3} M{sub ⊙} yr{sup −1}) and dealt with stellar rotation as a separate post-process. The protostar would reach the Keplerian rotation very soon after the onset of mass accretion, but mass accretion would continue as stellar angular momentum is transferred outward to the accretion disk by viscous stress. The envelope of the protostar expands rapidly when the stellar mass reaches ∼5–7 M{sub ⊙} and the Eddington factor increases sharply. This makes the protostar rotate critically at a rate that is significantly below the Keplerian value (i.e., the ΩΓ limit). The resultant positive gradient of the angular velocity in the boundary layer between the protostar and the Keplerian disk prohibits angular momentum transport from the star to the disk, and consequently further rapid mass accretion. This would prevent the protostar from growing significantly beyond 20–40 M{sub ⊙}. Another important consequence of the ΩΓ limit is that the protostar can remain fairly compact (R ≲ 50 R{sub ⊙}) and avoid a fluffy structure (R ≳ 500 R{sub ⊙}) that is usually found with a very high rate of mass accretion. This effect would make the protostar less prone to binary interactions during the protostar phase. Although our analysis is based on Population III protostar models, this role of the ΩΓ limit would be universal in the formation process of massive stars, regardless of metallicity.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

An investigation of the landing characteristics of the NASA-MSC August 1969 baseline orbiter configuration in ground effect

A 0.05 scale model of the NASA-MSC August 1969 baseline shuttle craft was tested in Texas A&M University's 7- x 10-foot low speed wind tunnel facility. The purpose of the test was to determine the landing aerodynamic characteristics of the shuttle craft vehicle in ground effect and to evaluate control surface hinge moments experienced in the cruise and landing operational phases of flight. Analysis of the final data will allow evaluation of vehicle flight stability in ground effect and estimation of vehicle control surface power system requirements.

Chambliss, E. B.↗
NASA NTRS1972

A model following variable stability system for the NASA ARC X-14B.

A description of the basic design concept, hardware design, and flight evaluation of a Variable Stability System (VSS) installed on the NASA ARC X-14B is presented. The NASA ARC X-14B is a twin-engine, single-seated VTOL aircraft. The VSS is unique in that it employs a general purpose airborne digital computer as an integral part of the hybrid model following flight control system. The system design, analysis and testing phases are discussed in the paper from the application of optimal control techniques in the preliminary design of the system, through the flight demonstration of the VSS hardware.

Gallagher, J. T.↗
NASA NTRS1973

Unified Approach to the Biomechanics of Dental Implantology

The human need for safe and effective dental implants is well-recognized. Although many implant designs have been tested and are in use today, a large number have resulted in clinical failure. These failures appear to be due to biomechanical effects, as well as biocompatibility and surgical factors. A unified approach is proposed using multidisciplinary systems technology, for the study of the biomechanical interactions between dental implants and host tissues. The approach progresses from biomechanical modeling and analysis, supported by experimental investigations, through implant design development, clinical verification, and education of the dental practitioner. The result of the biomechanical modeling, analysis, and experimental phases would be the development of scientific design criteria for implants. Implant designs meeting these criteria would be generated, fabricated, and tested in animals. After design acceptance, these implants would be tested in humans, using efficient and safe surgical and restorative procedures. Finally, educational media and instructional courses would be developed for training dental practitioners in the use of the resulting implants.

Grenoble, D. E.↗
NASA NTRS1974

Development of a fused slurry silicide coating for the protection of tantalum alloys

Results are reported of a research program to develop a reliable high-performance, fused slurry silicide protective coating for a tantalum-10 tungsten alloy for use at 1427 to 1538 C at 0.1 to 10 torr air pressure under cyclic temperature conditions. A review of silicide coating performance under these conditions indicated that the primary wear-out mode is associated with widening of hairline fissures in the coating. Consideration has been given to modifying the oxidation products that form on the coating surface to provide a seal for these fissures and to minimize their widening. On the basis of an analysis of the phase relationships between silica and various other oxides, a coating having the slurry composition 2.5Mn-33Ti-64.5Si was developed that is effective in the pressure range from 1 to 10 torr.

Packer, C. M.↗
NASA NTRS1975

Possible radio emission from Uranus at 0.5 MHz

Radio emission from the direction of Uranus was detected in data from the radio astronomy experiment on the IMP-6 spacecraft. Previously, emission from the direction of Jupiter and Saturn was observed by the IMP-6 at a number of frequencies near 1 MHz during the period April 1971 to October 1972. These radio bursts were identified in the IMP-6 data through an analysis of the phase of the observed modulated signal detected from the spinning dipole antenna. This technique was applied to the direction of the planet Uranus with possible positive results. Over the approximately 500 days of data, three to six bursts with unique spectral characteristics were found. Identification with Uranus is confused by the likely presence of low level terrestrial and solar emission. The observed events persisted less than three minutes and are strongest in intensity near 0.5 MHz.

Brown, L. W.↗
NASA NTRS1975

Snow cover monitoring by machine processing of multitemporal LANDSAT MSS data

LANDSAT frames were geometrically corrected and data sets from six different dates were overlaid to produce a 24 channel (six dates and four wavelength bands) data tape. Changes in the extent of the snowpack could be accurately and easily determined using a change detection technique on data which had previously been classified by the LARSYS software system. A second phase of the analysis involved determination of the relationship between spatial resolution or data sampling frequency and accuracy of measuring the area of the snowpack.

Luther, S. G.↗
NASA NTRS1976

Possible radio emission from Uranus at 0.5 MHz

Radio emission from the direction of Uranus has been detected in data from the Goddard radio astronomy experiment on the IMP-6 spacecraft. Previously, emission from the direction of Jupiter and Saturn had been observed by IMP-6 at a number of frequencies near 1 MHz and were identified through an analysis of the phase of the observed modulated signal detected from the spinning dipole antenna. This technique was applied to the direction of Uranus with possible positive results. Over the approximately 500 days of data, three to six bursts with unique spectral characteristics have been found. The events persisted less than 3 minutes and are strongest in intensity near 0.5 MHz. Identification with Uranus is confused by the likely presence of low-level terrestrial and solar emission. Because of the unfavorable angular separation of earth and Uranus, there is a possibility that the bursts are atypical terrestrial magnetospheric phenomena, although the uniqueness of the set of events indicates the probable detection of radiation from Uranus.

Brown, L. W.↗