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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Using a Commerical off the Shelf Data Acquisition System for the Space Shuttle Solid Rocket Booster Program

The space shuttle solid rocket boosters (SRBs) experience a severe environment during their brief flight. During the last few years several SRB's have sustained noticeable structural damage. The environmental characteristics (vibration, structure, and thermal) encountered by the SRB's during ascent, descent and water impact are in most cases unknown. A developmental flight instrumentation (DFI) system collected data from the SRBs' first four flights in the early 1980's, and after the first three flights during the shuttle return-to-flight phase after the Challenger accident. However, the DFI data collected are of low fidelity and do not correlate well with cases of observed structural damage. The DFI system was evaluated for reuse, but the cost to fly it was prohibitive. The space shuttle is presently scheduled to fly until 2030. To support the shuttle flight schedule, avionics on the SRB's will be upgraded. The environments on the different sections of the SRB will need to be defined more completely to properly qualify the avionics for multiple flights. The DFI data previously gathered do not provide enough information to properly qualify the avionics. Marshall Space Flight Center's (MSFC) SRB Project Office requested the Science and Engineering (S&E) Directorate to develop a stand-alone data acquisition system that could collect data from any area of the booster. In answer to this requirement, S&E developed the Enhanced Data Acquisition System (EDAS). To minimize development time and cost, the development team used state-of-the-art commercial off the shelf (COTS) equipment. The first two flights of this system occurred on shuttle mission STS-91 in June 1998 and STS-95 in October 1998. Twenty-one measurements were successfully recorded on the STS-91 right hand booster, providing new accelerometer, strain, temperature, and heating rate data to analysts. Twenty-four measurements were successfully recorded on the STS-95 left hand booster, providing data from the booster and the external tank. This paper summarizes the effort to develop, test, qualify and fly the EDAS to meet SRB flight and data collection requirements.

Crawford, Kevin↗
NASA NTRS1998

Development of a Low Cost Data Acquisition System for the Solid Rocket Booster Program

The Space Transportation System's (STS) Solid Rocket Boosters (SRBs) experience a severe environment during their brief flight. During the last few years several SRB's have sustained noticeable structural damage. The environmental characteristics (vibration, structure, and thermal) encountered by the SRB's during ascent, descent and water impact are in most cases unknown. A developmental flight instrumentation (DFI) system collected data from the SRB's first four flights in the early 1980's, and after the first three flights during the shuttle return-to-flight phase after the Challenger accident. However, the DFI data collected are of low fidelity and do not correlate well with the observed structural damage. The DFI system was evaluated for reuse, but the cost to fly it was prohibitive. The STS is presently scheduled to fly until 2030. To support the STS schedule the avionics on SRB's will be upgraded. The environments on the different sections of the SRB will need to be defined to properly qualify the avionics for multiple flights. The DFI data previously gathered does not provide enough information to properly qualify the avionics. Marshall Space Flight Centers (MSFC) SRB Project Office requested the Science and Engineering Directorate to develop a self contained data acquisition system that could collect data from any area of the booster. This paper summarizes the effort to develop, test, qualify and fly an Enhanced Data Acquisition System (EDAS) using state-of-the-art commercial off the shelf (COTS) equipment. The first flight of this system occurred on shuttle mission STS-91 in June 1998.

Crawford, Kevin↗
NASA NTRS1990

Propagation characteristics of optical fiber structures with arbitrary shape and index variation

The application of the scalar wave-fast Fourier transform (SW-FFT) technique to the computation of the propagation characteristics of some complex optical fiber structures is presented. The SW-FFT technique is based on the numerical solution of the scalar wave equation by a forward-marching fast Fourier transform method. This solution yields the spatial configuration of the fields as well as its modal characteristics in and around the guiding structure. The following are treated by the SW-FFT method: analysis of coupled optical fibers and computation of their odd and even modes and coupling length; the solution of tapered optical waveguides (transitions) and the study of the effect of the slope of the taper on mode conversion; and the analysis of branching optical fibers and demonstration of their mode-filtering and/or power-dividing properties.

Manshadi, F.↗
DOE OSTI2023

Watersheds and stream networks viewed longitudinally: Example insights from novel spatial portrayals of watershed characteristics

Abstract Longitudinal depictions of watershed structure and characteristics, including topography, stream networks, wetlands, ground water levels, and land use, can provide watershed knowledge and understanding unavailable from standard plan view maps. Three case studies provide examples of knowledge gained by applying longitudinal views of stream networks, watershed hydrologic behavior, and land use distributions. Longitudinal views of mountain stream networks show extreme variability in the slope‐area relationships of low Strahler order streams, large discontinuities in drainage area (large parts of drainage area space are absent in networks), and large variations in network curvature. Longitudinal views of a groundwater‐dominated headwater watershed increase the inference available from limited groundwater observations and clearly reveal how groundwater connections affect the permanence of surface water features and the distribution of vadose zone storage in the landscape. Plotting land uses longitudinally illuminates and allows a quantitative analysis of how land uses are distributed relative to topographic position. Viewing watersheds and stream networks longitudinally can provide new insights into watershed forms and processes and motivate new questions and research.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1977

Some design considerations for large space structures

Physical characteristics of large skeletal frameworks for space applications are investigated by analyzing one concept: the tetrahedral truss, which is idealized as a sandwich plate with isotropic faces. Appropriate analytical relations are presented in terms of the truss column-element properties, which for calculations were taken as slender graphite/epoxy tubes. Column loads, resulting from gravity-gradient control and orbital transfer, are found to be small for the class structure investigated. Fundamental frequencies of large truss structures are shown to be an order of magnitude lower than large earth-based structures. Permissible loads are shown to result in small lateral deflections of the truss due to low strain at Euler buckling of the slender graphite/epoxy truss column elements. Lateral thermal deflections are found to be a fraction of the truss depth using graphite/epoxy columns.

Bush, H. G.↗
NASA NTRS1993

Impulse damping control of an experimental structure

The characteristics associated with the fuel optimal control of a harmonic oscillator are extended to develop a near minimum fuel control algorithm for the vibration suppression of spacecraft. The operation of single level thrusters is regulated by recursive calculations of the standard deviations of displacement and velocity resulting in a bang-off-bang controller. A vertically suspended 16 ft cantilevered beam was used in the experiment. Results show that the structure's response was easily manipulated by minor alterations in the control law and the control system performance was not seriously degraded in the presence of multiple actuator failures.

Redmond, J.↗
NASA NTRS1973

Active damping of unidimensional structures

The vibration characteristics of an unidimensional structure are discussed. The cases considered are: (1) a rigid pipe in which a wave propagates, (2) an infinite string along which a transverse wave propagates, (3) a rod along which longitudinal or torsional columns propagate, and (4) generally a unidimensional propagation of some one mode of vibrations which is nondegenerating with distance. Mathematical models are developed to show the performance of the mechanical devices under various damping conditions.

Tartakovskiy, B. D.↗
DOE OSTI2022

Adsorption of methylene blue by bismuth impregnated biochar of different biomass materials: pore structure and surface chemistry characteristics

Abstract In this study, three different types of biochar (biomass materials were beech wood, corncob, and bamboo) were loaded with bismuth to form bismuth impregnated biochars (named respectively as Bi@WBC, Bi@CBC, and Bi@BBC) to investigate their properties (pore structure and surface chemistry characteristics) on methylene blue (MB) removal capacities. Three bismuth impregnated biochars made from different biomass materials were ranked for their adsorption capacity of MB as follows: Bi@WBC > Bi@CBC > Bi@BBC, in which Bi@WBC showed the largest Langmuir adsorption capacity of 178.59 mg g −1 . While the specific surface area (SSA) and pore volume of Bi@WBC were the largest (accounting for 477.74 m 2 g −1 and 0.15 cm 3 g −1 , respectively), according to the FTIR and XPS results, Bi@WBC (72.3%) exhibited a higher proportion of BiO bonds than the Bi@CBC (52.3%) and Bi@BBC (48.4%) did. Conclusively, the rich porous structure and surface functional groups of Bi@WBC affected the adsorption capacity of MB, and the chemical adsorption provided the main contribution. © 2022 Society of Chemical Industry (SCI).

Li, Peiyi↗
NASA NTRS1982

Sintered plaque characteristics

The structural transformations occurring during sintering, the fabrication of a slurry produced sintered plaque, are detailed. Degradation of the positive electrode in performance in cycling in a nickel hydrogen battery were traced to the quality of the sintered plaque. Electrode degradation was found to be a limiting factor in the battery cycle life. Details of microstructural characterization and distribution of pores, examination of plastic flow during shrinkage, and observations of the rounding of nickel powder particles during the slurry process are presented.

Vaidyanathan, H.↗
DOE OSTI2024

Structure, bonding and electronic characteristics of amorphous Se

Ovonic threshold switching (OTS) selector can effectively improve the storage density and suppress the leakage current of advanced phase-change memory. As a prototypical OTS material, amorphous GeSe is widely investigated. But the attentions paid to amorphous Se (i.e., the functional constituent in amorphous GeSe) is very limited up to now. Here, in this work, we have explored the structure, bonding and electronic characteristics of amorphous Se using ab initio molecular dynamics simulations. The results reveal that the Se atoms in amorphous Se tend to form the 2-coordinated configurations, and they connect with each other to form the long chains. The fraction of vibrational density of state located in high frequency range is relatively large, and the formation energy of Se-Se bond is as large as 4.44 eV, hinting that the Se-Se bonds in chains possess a high stability. In addition, the mid-gap state related to the OTS behavior is also found in the amorphous Se despite of the small proportion. Our findings enrich the knowledge of the amorphous Se, which contributes to the applications of Se-based OTS selectors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1987

Dynamic and attitude control characteristics of an International Space Station

The structural dynamic characteristics of the International Space Station (ISS), the interim reference configuration established for NASA's Space Station developmental program, are discussed, and a finite element model is described. Modes and frequencies of the station below 2.0 Hz are derived, and the dynamic response of the station is simulated for an external impulse load corresponding to a failed shuttle-docking maneuver. A three-axis attitude control system regulates the ISS orientation, with control moment gyros responding to attitude and attitude rate signals. No instabilities were found in the attitude control system.

Sutter, Thomas R.↗
NASA NTRS1991

Structural and thermal interface characteristics of Stirling cycle cryocoolers for space applications

Integration of a Stirling cycle cryocooler into a flight system will require careful attention to the thermal, structural, and electrical interfaces between the cryocooler, the instrument and the spacecraft. These issues are currently under investigation by National Aeronautics and Space Administration/Goddard Space Flight Center personnel in laboratory tests of representative longlife cryocoolers. An 80 K cryocooler has been instrumented as a testbed for vibration control systems characterization. Initial vibration data using a new six-DOF force dynamometer is presented in this report.

Boyle, R.↗
NASA NTRS1981

The overall structure and evolution of active regions

The evolutionary characteristics and structure of the magnetic fields and atmospheric phenomena associated with the development of a solar magnetic region are discussed. Bipolar magnetic regions are introduced as the source of all solar magnetic fields, formed as bundles of magnetic flux rise to and break through the solar surface and spread throughout the photosphere, chromosphere and corona. The photospheric magnetic region is shown to be characterized by bipolar flux regions of various sizes emerging rapidly for a few days, then expanding and decreasing in flux for several months and fragmenting. Sunspots and faculae are considered as tracers of the magnetic regions in the upper photosphere or lower chromosphere, while chromospheric tracers include arch filaments, field transition arches, long chromospheric threads, disk filaments and dark fibrils in chromospheric lines. The transition region and lower corona exhibit a multithermal plasma distribution, with low-temperature plasmas confined to the footprints and legs of magnetic field lines and high-temperature plasmas originating in loops or systems of unresolved loops. The bipolar magnetic region is also shown to interact with its surroundings to produce an interconnected field line pattern.

Sheeley, N. R., Jr.↗
DOE OSTI2024

Generalized representative structures for atomistic systems

A new method is presented to generate atomic structures that reproduce the essential characteristics of arbitrary material systems, phases, or ensembles. Previous methods allow one to reproduce the essential characteristics (e.g. the chemical disorder) of a large random alloy within a small crystal structure. The ability to generate small representations of random alloys, along with the restriction to crystal systems, results from using the fixed-lattice cluster correlations to describe structural characteristics. A more general description of the structural characteristics of atomic systems is obtained using complete sets of atomic environment descriptors. These are used within for generating representative atomic structures without restriction to fixed lattices. A general data-driven approach is provided here utilizing the atomic cluster expansion (ACE) basis. The N-body ACE descriptors are a complete set of atomic environment descriptors that span both chemical and spatial degrees of freedom and are used within for describing atomic structures. The generalized representative structure (GRS) method presented within generates small atomic structures that reproduce ACE descriptor distributions corresponding to arbitrary structural and chemical complexity. It is shown that systematically improvable representations of crystalline systems on fixed parent lattices, amorphous materials, liquids, and ensembles of atomic structures may be produced efficiently through optimization algorithms. With the GRS method, we highlight reduced representations of atomistic machine-learning training datasets that contain similar amounts of information and small 40–72 atom representations of liquid phases. The ability to use GRS methodology as a driver for informed novel structure generation is also demonstrated. The advantages over other data-driven methods and state-of-the-art methods restricted to high-symmetry systems are highlighted.

atomic cluster expansion↗