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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Processing of DMSP magnetic data: Handbook of programs, tapes, and datasets

The DMSP F-7 satellite was an operational Air Force meteorological satellite which carried a magnetometer for geophysical measurements. The magnetometer was located within the body of the spacecraft in the presence of large spacecraft fields. In addition to stray magnetic fields, the data have inherent position and time inaccuracies. Algorithms were developed to identify and remove time varying magnetic field noise from the data. These algorithms are embodied in an automated procedure which fits a smooth curve through the data and then identifies outliers and which filters the predominant Fourier component of noise from the data. Techniques developed for Magsat were then modified and used to attempt determination of the spacecraft fields, of any rotation between the magnetometer axes and the spacecraft axes, and of any scale changes within the magnetometer itself. Software setup and usage are documented and program listings are included in the Appendix. The initial and resulting data are archived on magnetic cartridge and the formats are documented.

Langel, R. A.↗
NASA NTRS1992

Radio and optical interferometric imaging

Since diffraction-limited imaging with a single aperture yields angular resolution approx. lambda/D, the attainment of high angular resolution with single apertures requires the construction of correspondingly large monolithic apertures, the whole surface of which must be figured to much less than a wavelength. At the longer wavelengths, it is impossible to build a sufficiently large single aperture: for example, at lambda 21 cm, arcsec resolution requires an aperture of diameter approx. 50 km. At the shorter wavelengths, the atmosphere imposes a natural limit in resolution of about one arcsec. However, another route is possible; that is, using synthetic apertures to image the sky. Synthetic apertures are now in use in many fields, e.g., radio interferometry, radar imaging, and magnetic-resonance imaging. Radio-interferometric techniques developed in radio astronomy over the past 40 years are now being applied to optical and IR astronomical imaging by a number of groups. Furthermore, the problem of figuring synthetic apertures is considerably simpler, and can be implemented in a computer: new 'self-calibration' techniques allow imaging even in the presence of phase errors due to the atmosphere.

Cornwell, Tim J.↗
DOE OSTI2023

Annihilation-gamma-based diagnostic techniques for magnetically confined electron–positron pair plasma

Efforts are underway to magnetically confine electron–positron pair plasmas to study their unique behaviour, which is characterized by significant changes in plasma time and length scales, supported waves and unstable modes. However, use of conventional plasma diagnostics presents challenges with these low-density and annihilating matter–antimatter plasmas. To address this problem, we propose to develop techniques based on the distinct emission provided by annihilation. This emission exhibits two spatial correlations: the distance attenuation of isotropic sources and the back-to-back propagation of momentum-preserving 2 $\gamma$ annihilation. We present the results of our analysis of the $\gamma$ emission rate and the spatial profile of the annihilation in a magnetized pair plasma from direct pair collisions, from the formation and decay of positronium as well as from transport processes. In order to demonstrate the effectiveness of annihilation-based techniques, we tested them on annular $\gamma$ emission profiles produced by a $\beta ^+$ radioisotope on a rotating turntable. Direct and positronium-mediated annihilation result in overlapping volumetric $\gamma$ sources, and the 2 $\gamma$ emission from these volumetric sources can be tomographically reconstructed from coincident counts in multiple detectors. Transport processes result in localized annihilation where field lines intersect walls, limiters or internal magnets. These localized sources can be identified by the fractional $\gamma$ counts on spatially distributed detectors.

Physics↗
NASA NTRS1979

Analysis of body form using biostereometrics

The general objective of the research was to provide the space and life sciences directorate with an improved biostereometric measurement capability. This objective was determined from the usefulness of stereophotogrametric techniques developed during the Apollo and Skylab Missions to measure body conformation, surface area, volume and relative density of astronauts. These noninvasive anthropometric measurements provided invaluable data concerning the physiological, biochemical and nutritional effects of the space environment upon the human body. The indirect nature of the technique has many advantages over other methods, and has a potential for many other applications. The stereophotographs contain an enormous amount of data which can be later reexamined should the need arise.

Source record↗
NASA NTRS1983

Halogen Occultation Experiment (HALOE) gas cell life test program

The Halogen Occultation Experiment (HALOE) will use gas filter correlation radiometry to measure the atmospheric concentration profiles of HCl, HF, NO, and CH4 from the Upper Atmosphere Research Satellite. The need to contain the gases for the gas filter measurements has resulted in the development of gas cells and the need for a life test program to demonstrate that the gas cells will perform their functions for extended periods (several years) of time. This report describes the tests in the life test program, the test apparatus used, and the analysis techniques developed. The report also presents data obtained during the first 14 months of the test program.

Sullivan, E. M.↗
NASA NTRS1983

Apparatus for continuous, fast, and precise measurements of position and velocity of a small spherical particle

The position and velocity of optically levitated glass spheres (radii 10-20 microns) movng in a gas are measured accurately, rapidly, and continuously using a high-speed rotating polygon mirror. The experimental technique developed here has repeatable position accuracies better than 20 microns. Each measurement takes less than 1 microsec and can be repeated every 100 microsec. The position of the levitated glass spheres can be manipulated accurately by modulating the laser power with an acoustic optic modulator. The technique provides a fast and accurate method to study general particle dynamics in a fluid.

Venkataraman, T. S.↗
NASA NTRS1988

Whisker-reinforced ceramic composites for heat engine components

Much work was undertaken to develop techniques of incorporating SiC whiskers into either a Si3N4 or SiC matrix. The result was the fabrication of ceramic composites with ever-increasing fracture toughness and strength. To complement this research effort, the fracture behavior of whisker-reinforced ceramics is studied so as to develop methodologies for the analysis of structural components fabricated from this toughened material. The results, outlined herein, focus on the following areas: the use of micromechanics to predict thermoelastic properties, theoretical aspects of fracture behavior, and reliability analysis.

Duffy, Stephen F.↗
DOE OSTI2017

Baryon Acoustic Oscillations reconstruction with pixels

Gravitational non-linear evolution induces a shift in the position of the baryon acoustic oscillations (BAO) peak together with a damping and broadening of its shape that bias and degrades the accuracy with which the position of the peak can be determined. BAO reconstruction is a technique developed to undo part of the effect of non-linearities. We present and analyse a reconstruction method that consists of displacing pixels instead of galaxies and whose implementation is easier than the standard reconstruction method. We show that this method is equivalent to the standard reconstruction technique in the limit where the number of pixels becomes very large. This method is particularly useful in surveys where individual galaxies are not resolved, as in 21cm intensity mapping observations. We validate this method by reconstructing mock pixelated maps, that we build from the distribution of matter and halos in real- and redshift-space, from a large set of numerical simulations. We find that this method is able to decrease the uncertainty in the BAO peak position by 30-50% over the typical angular resolution scales of 21 cm intensity mapping experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1971

Digital automatic data reduction techniques used in a 1000-flight biomedical study

Techniques developed to automatically process a large quantity of physiological data obtained during a 1000-flight study are described. To reduce this data reliably, a study program was conducted using physiological data from X-15 flights as a data source for experimenting with signal enhancement and noise elimination techniques. The techniques include an automatic means for counting heart rates, averaging electrocardiogram waveforms, plotting histograms of heart rate versus frequency, and counting respiration rates. These techniques were used to reduce more than 2000 hours of physiological data recorded in flight.

Carpenter, R.↗
NASA NTRS1988

Automatic Detection of Electric Power Troubles (ADEPT)

ADEPT is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system, and is designed for two modes of operation: real-time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a Laser printer. This system consists of a simulated Space Station power module using direct-current power supplies for Solar arrays on three power busses. For tests of the system's ability to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three busses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modelling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base. A load scheduler and a fault recovery system are currently under development to support both modes of operation.

Wang, Caroline↗
NASA NTRS1988

Automatic Detection of Electric Power Troubles (ADEPT)

Automatic Detection of Electric Power Troubles (A DEPT) is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system. It is designed for two modes of operation: real time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a laser printer. This system consists of a simulated space station power module using direct-current power supplies for solar arrays on three power buses. For tests of the system's ablilty to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three buses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modeling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base.

Wang, Caroline↗
NASA NTRS2000

Preliminary Analysis of Photoreading

The purpose of this project was to provide a preliminary analysis of a reading strategy called PhotoReading. PhotoReading is a technique developed by Paul Scheele that claims to increase reading rate to 25,000 words per minute (Scheele, 1993). PhotoReading itself involves entering a "relaxed state" and looking at, but not reading, each page of a text for a brief moment (about I to 2 seconds). While this technique has received attention in the popular press, there had been no objective examinations of the technique's validity. To examine the effectiveness of PhotoReading, the principal investigator (i.e., trainee) participated in a PhotoReading workshop to learn the technique. Parallel versions of two standardized and three experimenter-created reading comprehension tests were administered to the trainee and an expert user of the PhotoReading technique to compare the use of normal reading strategies and the PhotoReading technique by both readers. The results for all measures yielded no benefits of using the PhotoReading technique. The extremely rapid reading rates claimed by PhotoReaders were not observed; indeed, the reading rates were generally comparable to those for normal reading. Moreover, the PhotoReading expert generally showed an increase in reading time when using the PhotoReading technique in comparison to when using normal reading strategies to process text. This increase in reading time when PhotoReading was accompanied by a decrease in text comprehension.

McNamara, Danielle S.↗
NASA NTRS2000

Towards Solving the Mixing Problem in the Decomposition of Geophysical Time Series by Independent Component Analysis

The use of the Principal Component Analysis technique for the analysis of geophysical time series has been questioned in particular for its tendency to extract components that mix several physical phenomena even when the signal is just their linear sum. We demonstrate with a data simulation experiment that the Independent Component Analysis, a recently developed technique, is able to solve this problem. This new technique requires the statistical independence of components, a stronger constraint, that uses higher-order statistics, instead of the classical decorrelation a weaker constraint, that uses only second-order statistics. Furthermore, ICA does not require additional a priori information such as the localization constraint used in Rotational Techniques.

Aires, Filipe↗
NASA NTRS2005

Spatial Predictive Modeling and Remote Sensing of Land Use Change in the Chesapeake Bay Watershed

This project was focused on modeling the processes by which increasing demand for developed land uses, brought about by changes in the regional economy and the socio-demographics of the region, are translated into a changing spatial pattern of land use. Our study focused on a portion of the Chesapeake Bay Watershed where the spatial patterns of sprawl represent a set of conditions generally prevalent in much of the U.S. Working in the region permitted us access to (i) a time-series of multi-scale and multi-temporal (including historical) satellite imagery and (ii) an established network of collaborating partners and agencies willing to share resources and to utilize developed techniques and model results. In addition, a unique parcel-level tax assessment database and linked parcel boundary maps exists for two counties in the Maryland portion of this region that made it possible to establish a historical cross-section time-series database of parcel level development decisions. Scenario analyses of future land use dynamics provided critical quantitative insight into the impact of alternative land management and policy decisions. These also have been specifically aimed at addressing growth control policies aimed at curbing exurban (sprawl) development. Our initial technical approach included three components: (i) spatial econometric modeling of the development decision, (ii) remote sensing of suburban change and residential land use density, including comparisons of past change from Landsat analyses and more traditional sources, and (iii) linkages between the two through variable initialization and supplementation of parcel level data. To these we added a fourth component, (iv) cellular automata modeling of urbanization, which proved to be a valuable addition to the project. This project has generated both remote sensing and spatially explicit socio-economic data to estimate and calibrate the parameters for two different types of land use change models and has undertaken analyses of these models. One (the CA model) is driven largely by observations on past patterns of land use change, while the other (the EC model) is driven by mechanisms of the land use change decision at the parcel level. Our project may be the first serious attempt at developing both types of models for the same area, using as much common data as possible. We have identified the strengths and weaknesses of the two approaches and plan to continue to revise each model in the light of new data and new lessons learned through continued collaboration. Questions, approaches, findings, publication and presentation lists concerning the research are also presented.

Goetz, Scott J.↗
NASA NTRS2006

Space-Proven Medical Monitor: The Total Patient-Care Package

The primary objective of the Gemini Program was to develop techniques that would allow for advanced, long-duration space travel, a prerequisite of the ensuing Apollo Program that would put man safely on the Moon before the end of the decade. In order to carry out this objective, NASA worked with a variety of innovative companies to develop propulsion systems, onboard computers, and docking capabilities that were critical to the health of Gemini spacecraft, as well as life-support systems and physiological-monitoring devices that were critical to the health of Gemini astronauts. One of these companies was Spacelabs Medical, Inc., the pioneer of what is commonly known today as medical telemetry. Spacelabs Medical helped NASA better understand man s reaction to space through a series of bioinstrumentation devices that, for the first time ever, were capable of monitoring orbiting astronauts physical conditions in real time, from Earth. The company went on to further expand its knowledge of monitoring and maintaining health in space, and then brought it down to Earth, to dramatically change the course of patient monitoring in the field of health care.

Source record↗
DOE OSTI2017

Non-Destructive Evaluation of the Bondline Interface between Carbon Fiber Reinforced Laminated Composites and Metal Materials via Ultrasonic Inspection Methods

Woven fiber, laminated composites allow the design engineer to create high strength parts, but the effectiveness of the final processed part is greatly diminished through weak or nonexistent bonds between the composite and the substrate to which it is bonded. Additionally, these layered laminates are commonly made by curing the resin infused carbon fiber fabrics in predefined layers and then bonding them to another composite or a metallic structure using either a pre-cure or a co-cure method. The focus of this study is the identification of the defect caused by a disbond or a delamination located at the interface between a composite laminate stack and the substrate to which it is bonded. We present a nondestructive approach using various ultrasonic methods to identify the existence of the bond between composite and composite-to-metal interface. This paper explores contact and immersion ultrasound methods using pulse-echo for evaluating the composite material and adhesive bondline and the signal attenuation undergone by the wave as it propagates through the composite. Finally, a summary of the detection and analysis techniques developed to identify disbonds, including Fast Fourier Transform analysis of the immersion data, is presented. Lastly, each of the methods evaluated in this study is able to detect the transition from bonded to unbonded sections at the bondline from either side of the bonded part, with the immersion technique providing a significantly higher resolution of the edge of the bondline.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Flight testing techniques for the evaluation of light aircraft stability derivatives: A review and analysis

Techniques quoted in the literature for the extraction of stability derivative information from flight test records are reviewed. A recent technique developed at NASA's Langley Research Center was regarded as the most productive yet developed. Results of tests of the sensitivity of this procedure to various types of data noise and to the accuracy of the estimated values of the derivatives are reported. Computer programs for providing these initial estimates are given. The literature review also includes a discussion of flight test measuring techniques, instrumentation, and piloting techniques.

Smetana, F. O.↗
NASA NTRS1994

Matrix Failure Modes and Effects Analysis as a Knowledge Base for a Real Time Automated Diagnosis Expert System

Failure Modes and Effects Analysis contain a wealth of information that can be used to create the knowledge base required for building automated diagnostic Expert systems. A real time monitoring and diagnosis expert system based on an actual NASA project's matrix failure modes and effects analysis was developed. This Expert system Was developed at NASA Ames Research Center. This system was first used as a case study to monitor the Research Animal Holding Facility (RAHF), a Space Shuttle payload that is used to house and monitor animals in orbit so the effects of space flight and microgravity can be studied. The techniques developed for the RAHF monitoring and diagnosis Expert system are general enough to be used for monitoring and diagnosis of a variety of other systems that undergo a Matrix FMEA. This automated diagnosis system was successfully used on-line and validated on the Space Shuttle flight STS-58, mission SLS-2 in October 1993.

Herrin, Stephanie↗