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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Development of a high capacity bubble domain memory element and related epitaxial garnet materials for application in spacecraft data recorders. Item 1: Development of a high capacity memory element

Several versions of the 100K bit chip, which is configured as a single serial loop, were designed, fabricated and evaluated. Design and process modifications were introduced into each succeeding version to increase device performance and yield. At an intrinsic field rate of 150 KHz the final design operates from -10 C to +60 C with typical bias margins of 12 and 8 percent, respectively, for continuous operation. Asynchronous operation with first bit detection on start-up produces essentially the same margins over the temperature range. Cost projections made from fabrication yield runs on the 100K bit devices indicate that the memory element cost will be less than 10 millicents/bit in volume production.

Besser, P. J.↗
NASA NTRSDate not supplied

Formalization of the Bellman-Ford Algorithm for Airspace Applications

This paper describes the formal verification of one of the most well-known algorithms for finding the shortest path between all vertices in a directed graph, namely the Bellman-Ford algorithm. This formal verification, performed in the Prototype Verification System (PVS), is motivated by two applications in the aerospace domain which use the algorithm for path planning. The first is a pre-flight calculation that uses an adapted version of Bellman-Ford to find a route intended to maximize GNSS availability throughout the flight. The second is a more traditional application intended to find the shortest path between an autonomous aircraft's current position and a goal waypoint, while avoiding regions of space specified by geofences. A novel aspect of this formal verification effort is the inclusion of two distinct models of computation for the algorithm, one being a traditional serial computation, and the other being an explicitly parallel computation. The ability to use parallel computation in the Bellman-Ford algorithm is in fact why it was chosen over other traditionally more performant algorithms, especially for the GNSS application, where the size of the graph makes a purely serial computation infeasible.

formal verification↗
NASA NTRS2024

Autonomy to Enable NASA Missions from Aeronautics to Space

2024 ASCEND Call for Sessions Session Format: Panel Session Topic: Space Exploration and Infrastructure: Exploring, Living, and Working in Space (The panel must map to one of six Session Topics - https://www.ascend.events/presenters/call-for-sessions/#sessiontopics) Title: Autonomy to Enable NASA Missions from Aeronautics to Space Short Session Description: In this panel discussion the National Aeronautics and Space Administration (NASA) will discuss the role that autonomy and Artificial Intelligence (AI) will play as humanity moves off-world. Recent advances in general autonomy tools are changing the way NASA and its partners leverage autonomy for its air and space initiatives, including Advanced Air Mobility (AAM) concepts and potential lunar and Martian operations. The panelists will consist of autonomy subject matter experts familiar with the current state of the art for autonomy across both aeronautical and space domains. They will discuss how those technologies could evolve as operations become more complex and which autonomy technologies can be used in both the space and aeronautical domains. For example, perhaps autonomy work originally developed for terrestrial applications, like Advanced Air Mobility (AAM), could be applied to off-world lunar and Martian applications and vice versa. Additionally, the panel will address common misconceptions of these technologies, obstacles to implementation, and possible solutions for overcoming those obstacles. Join NASA in exploring how research activities can align to streamline autonomy development efforts, advancing NASA's goals to expand humanity's reach beyond Earth for the benefit of all. Contact Information: • Dr. Adam Yingling • Office of Technology, Policy, and Strategy (OTPS) • Adam.j.yingling@nasa.gov, 703-416-9129 Session Length: 1.25 hours, 75 minutes Extended Description: Moderator: Dr. Adam Yingling, NASA, Office of Technology, Policy, and Strategy Panel Speakers: • Autonomy Forum Principals o Dr. Charles Norton, Deputy Chief Technologist, Jet Propulsion Laboratory (JPL) o Dr. Carolyn Mercer, Chief Technologist, Space Mission Directorate (SMD) o Dr. Parimal Kopardekar (PK), Advanced Air Mobility (AAM) Integration Manager o Danette Alan, NASA, Senior Leader for Autonomous Systems, Space Technology Mission Directorate (STMD) o Duane Armstrong, Intelligent Systems Lead, Autonomous Systems Laboratory (ASL) Panel Format: • Introduction (10 min): The panel moderator will provide a 10-minute session introduction that will include an overview NASA’s Moon to Mars architecture, AAM autonomy research, and an introduction of the principals as panel speakers. • Moderated Session Part 1 (30 min): There will be a 30-minute moderated session among the moderator and the five autonomy principals to discuss the current state of art for autonomy and how work developed in one domain may be applicable to other domains; including the merits and challenges for implementing those technologies. • Moderated Session Part 2 (25 min): The moderator will then ask the principals to consider how technologies developed across all the domains might be able to address the most salient challenges identified in the previous session. • Q&A (10 min): The session will conclude with 10-minutes of audience Q&A. Session Goals and Outcomes: The session goals are 1) to communicate the importance of autonomy for both aeronautical and space mission, 2) Investigate potential synergies across autonomy research efforts that will enable scalable operations, and 3) to receive community feedback as NASA leverages autonomy to evolve aviation on Earth and enable humanity to live and work off-world.

Aerospace↗
NASA NTRS1997

Efficient Multidisciplinary Analysis Procedure Using Multi-Level Parallelization Approach

Multidisciplinary applications are suitable for parallel computing environment by adopting the domain decomposition method. Immediately, a multidisciplinary application can be parallelized by solving each discipline separately. In order to perform coupled multidisciplinary analysis, coupling of each discipline can be accomplished by exchanging boundary data at the interfaces. This is regarded as discipline-level parallelization. Next level could be a "coarse-grain" parallelization of each discipline, which mainly depends on the physical geometry and nature of each discipline. For example, it is almost impossible for structured-grid based computational fluid dynamics codes to do flow analysis of an aircraft by using a single grid because of the complexity of its configuration. Thus, multi-block grid is commonly used to describe the details of complex geometry. Similarly, in structural analysis, the structure is frequently subdivided into substructures. Thus, the computation of each subdomain can be easily parallelized since each subdomain is solved separately independent of other domains. The parallelization is accomplished by solving each subdomain separately on a separate processor and exchanging the boundary conditions at domain interfaces periodically. However, the physical decomposition of the domain introduces explicit boundary conditions at the domain interfaces. This is not desirable for critical areas such as those containing shock waves or flow separations. Thus, a "fine-grain" parallelization is introduced to overcome this problem. The "fine-grain" parallelization is one that solves exactly the same system of equations of a subdomain by using more than one processors without introducing any explicit boundary conditions. An efficient multidisciplinary analysis procedure can be accomplished by successfully combining the above multi-level parallelism. A multidisciplinary analysis code, ENSAERO developed at NASA Ames Research Center is used in this study to implement the proposed approach. The communication data structure required for the proposed approach will be studied in detail. This work will demonstrate the feasibility of using multi-level parallelization approach in multidisciplinary analysis applications.

Byun, Chansup↗
NASA NTRS1988

Data dependent systems methodology for lumped mass modeling of structures

Limitations of the frequency domain methods in analyzing structura1 vibrations has created an awareness of the comparative merits of the time domain methods. Although time domain methods would be ideal for modeling large precisions space systems, the popular methods based on fitting theoretical response to actual data by least squares are too sensitive to noise and require too much data to be suitable for orbiting space crafts. This paper briefly reviews the theory and illustrative applications of a time domain methodology called Data Dependent Systems (DDS) that eliminates these limitations. Simulation results are presented to demonstrate a better than 4-place accuracy in the identifications of all system parameters, both modal (frequencies, damping ratios, and mode shapes) and physical (mass, stiffness, and damping matrices).

Pandit, Sudhakar M.↗
NASA NTRS1992

Generic domain models in software engineering

This paper outlines three research directions related to domain-specific software development: (1) reuse of generic models for domain-specific software development; (2) empirical evidence to determine these generic models, namely elicitation of mental knowledge schema possessed by expert software developers; and (3) exploitation of generic domain models to assist modelling of specific applications. It focuses on knowledge acquisition for domain-specific software development, with emphasis on tool support for the most important phases of software development.

Maiden, Neil↗
NASA NTRS1991

Time domain scattering and radar cross section calculations for a thin, coated perfectly conducting plate

Radar cross section (RCS) calculations for flat, perfectly conducting plates are readily available through the use of conventional frequency domain techniques such as the Method of Moments (MOM). However, if the plate is covered with a dielectric material that is relatively thick in comparison with the wavelength in the material, these frequency domain techniques become increasingly difficult to apply. We present the application of the Finite Difference Time Domain (FDTD) Technique to the problem of electromagnetic scattering and RCS calculations from a thin, perfectly conducting plate that is coated with a thick layer of lossless dielectric material. Both time domain and RCS calculations are presented and disclosed.

Luebbers, Raymond J.↗
NASA NTRS1993

Evaluation of Waveform Mapping as a Signal Processing Tool for Quantitative Ultrasonic NDE

The mapping of one pulsed waveform into another, more desirable waveform by the application of a time-domain filter has been employed in a number of NDE situations. The primary goal of these applications has been to improve the range resolution of an ultrasonic signal for detection of echoes arising from particular interfaces masked by the response of the transducer. The work presented here addresses the use of this technique for resolution enhancement in imaging situations and in mapping signals from different transducers to a common target waveform, allowing maintenance of quantitative calibration of ultrasonic systems. We also describe the use of this technique in terms of the frequency analysis of the resulting waveforms.

Johnston, Patrick H.↗
NASA NTRS2003

Safe Grid

The biggest users of GRID technologies came from the science and technology communities. These consist of government, industry and academia (national and international). The NASA GRID is moving into a higher technology readiness level (TRL) today; and as a joint effort among these leaders within government, academia, and industry, the NASA GRID plans to extend availability to enable scientists and engineers across these geographical boundaries collaborate to solve important problems facing the world in the 21 st century. In order to enable NASA programs and missions to use IPG resources for program and mission design, the IPG capabilities needs to be accessible from inside the NASA center networks. However, because different NASA centers maintain different security domains, the GRID penetration across different firewalls is a concern for center security people. This is the reason why some IPG resources are been separated from the NASA center network. Also, because of the center network security and ITAR concerns, the NASA IPG resource owner may not have full control over who can access remotely from outside the NASA center. In order to obtain organizational approval for secured remote access, the IPG infrastructure needs to be adapted to work with the NASA business process. Improvements need to be made before the IPG can be used for NASA program and mission development. The Secured Advanced Federated Environment (SAFE) technology is designed to provide federated security across NASA center and NASA partner's security domains. Instead of one giant center firewall which can be difficult to modify for different GRID applications, the SAFE "micro security domain" provide large number of professionally managed "micro firewalls" that can allow NASA centers to accept remote IPG access without the worry of damaging other center resources. The SAFE policy-driven capability-based federated security mechanism can enable joint organizational and resource owner approved remote access from outside of NASA centers. A SAFE enabled IPG can enable IPG capabilities to be available to NASA mission design teams across different NASA center and partner company firewalls. This paper will first discuss some of the potential security issues for IPG to work across NASA center firewalls. We will then present the SAFE federated security model. Finally we will present the concept of the architecture of a SAFE enabled IPG and how it can benefit NASA mission development.

Chow, Edward T.↗
NASA NTRS1978

Modal confidence factor in vibration testing

The theory and applications of a time domain modal test technique are presented. The method uses free decay of random responses from a structure under test to identify its modal characteristics namely, natural frequencies, damping factors, and mode shapes. The method can identify multimodal (highly coupled) systems and modes that have very small contribution in the responses. A method is presented to decrease the effects of high levels of noise in the data and thus improve the accuracy of identified parameters. This is accomplished using an oversized mathematical model. The concept of modal confidence factor (MCF) is developed. The MCF is a number calculated for every identified mode for a structure under test. The MCF varies from 0.000 for a distorted, nonlinear, or noise mode to 100.0 for a pure structural mode. The theory of the MCF is based on the correlation that exits between the modal deflection at a certain station and the modal deflection at the same station delayed in time. The theory and application of the MCF is illustrated by two experiments. The first experiment deals with simulated responses from a two degree of freedom system with 20 percent, 40 percent, and 100 percent noise added. The second experiment was run on a generalized payload model. The free decay response from the payload model contained about 22 percent noise.

Ibrahim, S. R.↗
NASA NTRS1988

Robust controller synthesis for large flexible space structures

The application of a multivariable frequency domain method for the attitude control and vibration suppression of large flexible space structures is discussed. Results of application of the linear-quadratic-Gaussian/loop transfer recovery method to the cases of a hop/column antenna, a wrap-rib antenna, and the Spacecraft Control Laboratory Experiment are presented. Controller order reduction is implemented using the balanced realization method, a Hankel-norm-based method, and a method based on stable factorization.

Joshi, S. M.↗
NASA NTRSDate not supplied

Open Source Application of Fusing Aerosol Products from GEO and LEO Satellites

Retrieving aerosol optical depths (AODs) from sun-synchronous polar orbiting (aka low earth orbit, LEO) satellites, such as MODISs, and VIIRSs, OMI, TROPOMI, etc, has become well-established as a tool for extracting information on particulate matter (PM) and related processes in the atmosphere. However, with recently launched geostationary satellites (GEO), such as GOES-16/17/18, and Himawari-8/9, and Meteosat Third Generation (MTG) they provide a much higher temporal resolution (order of 10 minutes), typically an image once or more per hour during daylight compared to LEO once per day. By combining these observations, we may be able to characterize the diurnal cycle of global AOD at the local, regional and global scale. While the science community is still exploring the new data from GEO observations, we have been thinking about how to properly combine/merge/fuse those data considering differences in their spatial and temporal resolutions. However, this poses a “Big Data” challenge. The big data challenge is not just about data storage, but also about data discoverability, and accessibility, and even more, about data migration/mirroring in the cloud-computing environment. This paper is merely showing some of the efforts and approaches we have attempted in fusing six satellites’ Level 2 aerosol data (three are from GEO (GOES-16/17 and Himawari-8), and the other three are from LEO (TERRA/MODIS, AQUA/MODIS, SNPP-VIIRS) from Dark Target (DT) aerosol retrieval algorithm. Having the on-demand capability of fusing remote sensing products onto the desired temporal and spatial domain enables researchers and application practitioners to better manipulate and work with satellite and sensor data. It is our hopeWe hope that by making such an open-source package, and the accompanying functionality, the scientific community will be granted easier access to aerosol data processing resources. The MEaSUREs Program (Making Earth System Data Records for Use in Research Environments) expands our understanding of the Earth's current system through atmospheric and surface measurements. In an effort to aid the scientific research component and improve open source methods, this project developed Python code for fusing six satellite Level 2 aerosol data (three are from geostationary satellites (GEO), and the other three are from low earth orbital satellites (LEO)) from Dark Target Aerosol Retrieval Algorithm.

Jennifer Wei↗
NASA NTRS2008

SHINE Virtual Machine Model for In-flight Updates of Critical Mission Software

This software is a new target for the Spacecraft Health Inference Engine (SHINE) knowledge base that compiles a knowledge base to a language called Tiny C - an interpreted version of C that can be embedded on flight processors. This new target allows portions of a running SHINE knowledge base to be updated on a "live" system without needing to halt and restart the containing SHINE application. This enhancement will directly provide this capability without the risk of software validation problems and can also enable complete integration of BEAM and SHINE into a single application. This innovation enables SHINE deployment in domains where autonomy is used during flight-critical applications that require updates. This capability eliminates the need for halting the application and performing potentially serious total system uploads before resuming the application with the loss of system integrity. This software enables additional applications at JPL (microsensors, embedded mission hardware) and increases the marketability of these applications outside of JPL.

Plesea, Lucian↗
NASA NTRS1973

Surface electrical properties experiment study phase, volume 2

The choice of an antenna for a subsurface radio sounding experiment is discussed. The radiation properties of the antennas as placed on the surface of the medium is examined. The objective of the lunar surface electrical properties experiment is described. A numerical analysis of the dielectric permittivity and magnetic permeability of a subsurface domain is developed. The application of electromagnetic field measurements between one or more transmitting antennas and a roving receiving station is explained.

Source record↗
NASA NTRS1974

A synopsis of Seasat-A scientific contributions

SEASAT-A satellite data processing and modelling capabilities address scientific and applications problems in the domains of oceanic, atmospheric, and solid earth geophysics studies by the use of active radar, and passive microwave and infrared instruments. A data flow map depicts the interrelationship between SEASAT-A instruments and other sources of information and the geophysical parameters to be determined.

Apel, J. R.↗
NASA NTRS1980

Numerical methods for large-scale time-dependent partial differential equations

The factors that influence the choice of a numerical solution scheme for large-scale time-dependent partial differential equations are examined with emphasis on the treatment of boundaries. Consideration is given to standard boundary treatments, moving boundaries, and artificial boundaries simulating an infinite domain. Implicit methods and applications to specific problems are discussed with special attention to shocks and steady state solutions.

Turkel, E.↗
NASA NTRS1982

Fracture mechanics in fiber reinforced composite materials, taking as examples B/A1 and CRFP

The validity of linear elastic fracture mechanics and other fracture criteria was investigated with laminates of boron fiber reinforced aluminum (R/A1) and of carbon fiber reinforced epoxide (CFRP). Cracks are assessed by fracture strength Kc or Kmax (critical or maximum value of the stress intensity factor). The Whitney and Nuismer point stress criterion and average stress criterion often show that Kmax of fiber composite materials increases with increasing crack length; however, for R/A1 and CFRP the curve showing fracture strength as a function of crack length is only applicable in a small domain. For R/A1, the reason is clearly the extension of the plastic zone (or the damage zone n the case of CFRP) which cannot be described with a stress intensity factor.

Peters, P. W. M.↗
NASA NTRS1987

Intelligent tutoring systems as tools for investigating individual differences in learning

The ultimate goal of this research is to build an improved model-based selection and classification system for the United States Air Force. Researchers are developing innovative approaches to ability testing. The Learning Abilities Measurement Program (LAMP) examines individual differences in learning abilities, seeking answers to the questions of why some people learn more and better than others and whether there are basic cognitive processes applicable across tasks and domains that are predictive of successful performance (or whether there are more complex problem solving behaviors involved).

Shute, Valerie J.↗