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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Development and Execution of a Large-scale DDT Tube Test for IHE Material Qualification

Insensitive High Explosive (IHE) Materials are defined in Chapter IX of the DOE Explosive Safety Standard (DOE-STD-1212-2012) as being materials that are massdetonable explosives that are so insensitive that the probability of accidental initiation or transition from burning to detonation is negligible1. There are currently a number of tests included in the standard that are required to qualify a material as IHE, however, none of the tests directly evaluate for the transition from burning to detonation (aka deflagration-to-detonation transition, DDT). Currently, there is a DOE complex-wide effort to revisit the IHE definition in DOE-STD-1212-2012 and change the qualification requirements. The proposal lays out a new approach, requiring fewer, but more appropriate tests, for IHE Material qualification. One of these new tests is the Deflagration-to-Detonation Test. According to the redefinition proposal, the purpose of the new deflagration-todetonation test is “to demonstrate that an IHE material will not undergo deflagration-to-detonation under stockpile relevant conditions of scale, confinement, and material condition. Inherent in this test design is the assumption that ignition does occur, with onset of deflagration. The test design will incorporate large margins and replicates to account for the stochastic nature of DDT events.” In short, the philosophy behind this approach is that if a material fails to undergo DDT in a significant over-test, then it is extremely unlikely to do so in realistic conditions. This effort will be valuable for the B61 LEP to satisfy their need qualify the new production lots of PBX 9502. The work described in this report is intended as a preliminary investigation to support the proposed design of an overly conservative, easily fielded DDT test for updated IHE Material Qualification standard. Specifically, we evaluated the aspects of confinement, geometry, material morphology and temperature. We also developed and tested a thermally robust igniter system.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Verification Problems for Parameterized Load Curves in DYNA3D

Two verification problems are presented which test a set of newly implemented load curve features in the explicit finite element program DYNA3D. Each test consists of a single element, with the velocity of each node specified via a different load curve type. The first test covers initialization and run-time execution of these new features, while the second test covers redefinition of load curves upon restart. The proposed problems may be easily extended to test additional load curve features.

42 ENGINEERING↗
DOE OSTI2018

Post Moore's Law Report

Moore's law is driving an information revolution, worldwide economic growth, and is a tool for national security. This report explains how dire proclamations that "Moore's law is ending" are due to a natural redefinition of the phrase, but computing remains positioned to both drive economic growth and support national security. The computer industry used to be led by the semiconductor companies that made ever faster microprocessors with larger memories. However, control is shifting to new ways of designing computers, notably based on 3D chips and new analog and digital architectures. While artificial intelligence and quantum computing research have become mainstream pursuits, these latter two areas seem destined split off from Moore's law rather than become a part of it. We include a discussion of recent developments and opportunities in optical communications and computing.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Verification Problems for Smooth Step Amplitude Load Curves in DYNA3D/Paradyn

This report documents the addition of three new verification tests in the LOADCURVE directory of the DYNA3D/Paradyn Software Quality Assurance test suite. Each test consists of a single element, where the velocities of each node are specified by either the newly added smooth step tabular load curve or another load curve option. The first test assesses the initialization and interpolation of the newly inputted load curve option through tabulated abscissa-ordinate pairs of data. The second test uses the same set of abscissa-ordinate data points and applies offset and scaling parameters available within the load curve definition. The third test defines the smooth step load curve in an original input deck, and assesses its correct redefinition using a restart file. The simulation velocities are compared to their true values at discrete points in time, and each test is verified up to numerical precision. These results confirm that the smooth step load curve option is functioning correctly and as intended.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Terra-Populus v0.1: A Python Library for LandScan High-Definition Population Analysis and Modeling

The terra-populus library is designed for use by the LandScan HD technical team, offering a streamlined set of tools for generating and updating LandScan HD datasets from foundational building-level data, referred to as 'molecules,' provided by the building-level attribution team. This document serves as the primary technical documentation for terra-populus. Version 0.1 of the library includes the core modeling components necessary for LandScan HD production. It enables the generation of the LandScan HD Baseline dataset as well as corresponding confidence measures for the occupancy rates used. Parameters have been included for incorporating damaged building indicators and changes in population, to faciliate the creation of rapid updates for LandScan HD. Future iterations of terra-populus will introduce tools for creating a confidence index, and quantifying and propagating uncertainty, facilitating the creation of probabilistic LandScan HD outputs. This report provides an overview of the tools available in the library and the corresponding code implementations. One of the key advancements implemented in terra-populus is a redefinition of the atomic modeling unit for LandScan HD. Traditionally, the LandScan HD vector analytical framework has generated population estimates at the building sub-component (molecule) level. However, terra-populus adopts a building-level modeling approach. This shift is an operational decision aimed at aligning LandScan HD outputs with confidence measures, which are computed and validated at the building level (confidence measures are not included in this version of terra-populus, aside from those associated with the occupancy rates). Additional advancements to the LandScan HD modeling, as implemented by terra-populus, include a minimum population value parameter and an auto assignment of building floor counts. The population minimum value was implemented to prevent buildings and subsequent LandScan HD pixels that contained small values that may not rasterize in production. An 'auto' value has been included as a method for dealing with buildings lacking floor count information, where it is the average floor count of all other buildings with a residential building use type tag. The logic behind this is to remain consistent with the current logic employed for dealing with building use type null instances, where a null use type is defaulted to residential since it is the most common building type. The auto logic is intended to apply the most common building floor count of the most common type of buildings. The tools provided in terra-populus represent a significant step forward in improving the efficiency, reproducibility, and transparency of the LandScan HD modeling process. As the library evolves, it will continue to serve as a foundational resource for high-resolution population modeling.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
NASA NTRS1973

Digital flight control design using implicit model following.

A design procedure for determining the control gains of a discrete-time ('digital') control system is presented. The method is separable into four distinct steps: (1) the definition of closed-loop response criteria, (2) the choice of a discrete-time model which provides the desired response, (3) the determination of control gains which implicitly force the actual system to follow the desired response, and (4) the reduction of the measurement state by the introduction of an 'observer' (a form of integral-differential compensation). It is shown that a single desired response does not completely define the 'ideal' system. The response criterion generally leaves some parameters of the model unspecified, allowing two courses for improving the model: (1) definition of additional response criteria, or (2) redefinition of the discrete-time model for improved implicit model-following with the actual closed-loop system.

Stengel, R. F.↗
NASA NTRS1973

Revised tables of airspeed, altitude, and Mach number presented in the International system of units

Because inception of a national program to implement the International System of Units (SI) appears to be inevitable and imminent, the tables of airspeed, altitude, and Mach number prepared by Livingston and Gracey to serve for airspeed meter and altimeter calibrations and for the conversion of flight measurements of these quantities to related parameters - Mach number, true airspeed, equivalent airspeed, etc. - have been revised to the SI. Tables of airspeed in knots are also included because of the significance of this quantity in navigation. In addition, the data in the altitude tables have been revised to the U.S. Standard Atmosphere of 1962. The latter data reflect increased knowledge of the higher atmosphere and more precise determination of basic quantities, including the redefinition of the absolute thermodynamic temperature scale by the Tenth General Conference on Weights and Measures in 1954. The U.S. Standard Atmosphere, 1962, corresponds to the International Civil Aviation Organization (ICAO) Standard Atmosphere up to 20 kilometers (geopotential altitude). A table of conversion factors for various pressure units is presented in SI Units.

Benner, M. S.↗
NASA NTRS1973

Volatile trace elements and the characterization of the Cayley Formation and the primitive lunar crust

Two types of highland terrain appear to be present at the Apollo 16 landing site. The Plains Formation called Cayley is ubiquitous and blankets even those regions that were presumably a part of the mountainous Descartes Formation. The second type of terrain is that associated with the ejectae from North and South Ray craters. The stratigraphy sampled by the ejectae underlays the Cayley layer as characterized above and may permit a redefinition of Descartes Formation as that which underlays the smooth Plains deposits. These conclusions are based on the concentrations and chemical coherence between elements such as Cl-F-P2O5 and Ru-Os. The primitive lunar crust may be characterized by the type of feldspathic rocks which are enriched in trace elements, such as Cl, Br, U, Te, Ru, and Os, as found in 'rusty' rock 66095 and in 61016; other feldspathic rocks are depleted and may be of secondary origin.

Jovanovic, S.↗
NASA NTRS1977

The NTF as a national facility

Activities which led to the definition of the National Transonic Facility and the general agreements reached regarding its use and operations are reviewed. Topics discussed include: redefinition of test requirements, development of low cost options, consideration of a single transonic facility using existing hardware if feasible, facility concept recommendations, and acquisition schedule proposals.

Nicks, O. W.↗
NASA NTRS1978

The Apollo spacecraft: A chronology volume 4, 21 January 1966 - 13 July 1974

This final volume of the chronology is divided into three parts: (1) preparation for flight, the accident, and investigation; (2) recovery, spacecraft redefinition, and the first manned flight; and (3) man circles the moon, the Eagle lands, and manned space exploration. Congressional documents, official correspondence, government and contractor reports, memoranda, working papers, and minutes of meetings were used as primary sources. A relatively few entries are based on press releases and newspaper and magazine articles.

Ertel, I. D.↗
NASA NTRS1982

Hybrid optimization of truss structures with strength and buckling constraints

An efficient scheme utilizing standard nonlinear programming methodology is presented for the optimal design of elastic, redundant structures with strength and buckling constraints. Numerical examples are given which demonstrate how this method, involving a constraint redefinition, can successfully overcome certain problems typical to such structures. The scheme is applied to the design of a cantilever truss with strength and buckling constraints, in which optimal nonuniform cross section columns are used for all elements critical in buckling. It is found that permitting node movement and adding redundancies can lower the weight of the structure for the prescribed design constraints. In addition, the node excursions in this configuration are shown to be relatively small.

Hajela, P.↗
NASA NTRS1983

The HEAO experience - design through operations

The design process and performance of the NASA High Energy Astronomy Observatories (HEAO-1, 2, and 3) are surveyed from the initiation of the program in 1968 through the end of HEAO-3 operation in May, 1981, with a focus on the attitude control and determination subsystem (ACDS). The science objectives, original and revised overall design concepts, final design for each spacecraft, and details of the ACDS designs are discussed, and the stages of the ACDS design process, including redefinition to achieve 50 percent cost reduction, detailed design of common and mission-unique hardware and software, unit qualification, subsystem integration, and observatory-level testing, are described. Overall and ACDS performance is evaluated for each mission and found to meet or exceed design requirements despite some difficulties arising from errors in startracker-ACDS-interface coordination and from gyroscope failures. These difficulties were resolved by using the flexibility of the software design. The implicationns of the HEAO experience for the design process of future spacecraft are suggested.

Hoffman, D. P.↗
NASA NTRS1985

Observational studies of the symbiotic stars. III High-dispersion IUE and H-alpha observations of EG Andromedae

High-dispersion IUE and optical spectra are presented for the symbiotic star EG Andromedae (HD 4174). Remarkable emission-line strength and profile variations are confirmed for the S IV, O IV, C IV, and He II ultraviolet lines as well as H-alpha. Accurate cross-correlation absorption-line velocities determined from Ti I, Ca I, and Fe I features convincingly demonstrate that EG And is a single-lined spectroscopic binary. The velocity curve suggests that the photometric ephemeris reported by Smith in 1980 should be revised by a redefinition of zero phase by about 0.08 of a period. The primary of the system may be similar to the central star of a planetary nebula embedded in a dense nebula with a mild stellar wind. The behavior of the emission lines is interpreted to indicate that the primary and its surrounding nebula suffer a partial eclipse by the cool giant secondary.

Oliversen, N. A.↗
NASA NTRS1985

Multiple-scale turbulence closure modeling of confined recirculating flows

A multiple-scale turbulence closure scheme is developed for the numerical predictions of confined recirculating flows. This model is based on the multiple-time-scale concepts of Hanjalic et al. (1980) and takes into account the non-equilibrium spectra energy transfer mechanism. Problems concerning new formulation of energy transfer rate equations and subsequent model coefficient redefinition and energy spectrum partition are discussed. Comparisons are made with several experiments of internal recirculating flows for the purpose of model validation. Numerical results using the present model show significant improvement of predictive capability over that obtained with the single-scale k-epsilon model and show promising potential for complex turbulent flow predictions.

Chen, C. P.↗
NASA NTRS1986

Lens collimation and testing using a Twyman-Green interferometer with a self-pumped phase-conjugating mirror

Ordinarily Twyman-Green interferometers are employed testing optical elements. In a modification of the basic configuration, the ordinary mirror in the test arm is replaced with a self-pumped phase-conjugating mirror using a barium titanate crystal. It is shown that, with a redefinition of components, the new configuration permits retention and improvement of the optical element testing function while simultaneously serving as a sensitive test for collimation. The optical path difference resulting from the double pass in the original Twyman-Green interferometer approximately equals that of the single pass and phase conjugation in the modification.

Howes, W. L.↗
NASA NTRS1985

Notes and comments on computational elastoplasticity - Some new models and their numerical implementation

The following topics are discussed in this paper: (1) the basic interactive nature of classical elasto-plasticity and a redefinition of elastic and plastic processes that facilitates numerical calculations, (2) generalized mid-point or end-point algorithms to determine the stress increment in an elastic-plastic solid from a given strain increment, (3) an endochronic (internal time) rate theory of time-independent plasticity which encompasses various multiple-yield-surface theories and nonlinear kinematic hardening theories as its specializations, and (4) comments on finite element and boundary element methods for solving boundary value problems in elasto-plasticity.

Atluri, S. N.↗
NASA NTRS1988

External tank program productivity and quality enhancements - A case study

The optimization of the Manned Space Systems productivity and quality enhancement program is described. The guidelines and standards of the program and the roles played in it by various employee groups are addressed. Aspects of the program involving job/organization redefinition, production and planning in automation, and artificial intelligence and robotics are examined.

Locke, S. R.↗
NASA NTRS1988

An intelligent interface for satellite operations: Your Orbit Determination Assistant (YODA)

An intelligent interface is often characterized by the ability to adapt evaluation criteria as the environment and user goals change. Some factors that impact these adaptations are redefinition of task goals and, hence, user requirements; time criticality; and system status. To implement adaptations affected by these factors, a new set of capabilities must be incorporated into the human-computer interface design. These capabilities include: (1) dynamic update and removal of control states based on user inputs, (2) generation and removal of logical dependencies as change occurs, (3) uniform and smooth interfacing to numerous processes, databases, and expert systems, and (4) unobtrusive on-line assistance to users of concepts were applied and incorporated into a human-computer interface using artificial intelligence techniques to create a prototype expert system, Your Orbit Determination Assistant (YODA). YODA is a smart interface that supports, in real teime, orbit analysts who must determine the location of a satellite during the station acquisition phase of a mission. Also described is the integration of four knowledge sources required to support the orbit determination assistant: orbital mechanics, spacecraft specifications, characteristics of the mission support software, and orbit analyst experience. This initial effort is continuing with expansion of YODA's capabilities, including evaluation of results of the orbit determination task.

Schur, Anne↗