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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

A statistical study of Pc 1-2 magnetic pulsations in the equatorial magnetosphere. I - Equatorial occurrence distributions. II - Wave properties

AMPTE CCE magnetic field data from a period spanning a complete local time revolution of the satellite orbit major axis are used to examine the occurrence distribution of transverse narrowband Pc 1-2 emissions in the equatorial magnetosphere from L = 3.5 to L = 9 at all local times. Three examples are presented to illustrate the properties of events occurring at dawn, noon, and dusk. The early afternoon outer magnetosphere is found to be the dominant site for electromagnetic ion cyclotron wave occurrence. Pc 1-2 exhibited a radial structure with a gap between high- and low-L events. The example intervals indicate that a significant local time variation of wave properties may exist. Distributions are presented of narrowband Pc 1-2 frequency, ellipticity, normalized frequency and spectral power vs local time, L, and magnetic latitude, using the data base of more than 9000 events obtained from AMPTE CCE magnetometer data. Events occurring in the region 0300-0900 MLT, L greater than 7 are distinctly different from the remainder of Pc 1-2. The unique features of this population are linear polarization at all latitudes and high normalized frequency, 0.4 to 0.5 on average.

Anderson, B. J.↗
NASA NTRS1992

OCEAN-PC and a distributed network for ocean data

The Intergovernmental Oceanographic Commission (IOC) wishes to develop an integrated software package for oceanographic data entry and access in developing countries. The software, called 'OCEAN-PC', would run on low cost PC microcomputers and would encourage and standardize: (1) entry of local ocean observations; (2) quality control of the local data; (3) merging local data with historical data; (4) improved display and analysis of the merged data; and (5) international data exchange. OCEAN-PC will link existing MS-DOS oceanographic programs and data sets with table-driven format conversions. Since many ocean data sets are now being distributed on optical discs (Compact Discs - Read Only Memory, CD-ROM, Mass et al. 1987), OCEAN-PC will emphasize access to CD-ROMs.

Mclain, Douglas R.↗
NASA NTRS2004

Practical Pocket PC Application w/Biometric Security

I work in the Flight Software Engineering Branch, where we provide design and development of embedded real-time software applications for flight and supporting ground systems to support the NASA Aeronautics and Space Programs. In addition, this branch evaluates, develops and implements new technologies for embedded real-time systems, and maintains a laboratory for applications of embedded technology. The majority of microchips that are used in modern society have been programmed using embedded technology. These small chips can be found in microwaves, calculators, home security systems, cell phones and more. My assignment this summer entails working with an iPAQ HP 5500 Pocket PC. This top-of-the-line hand-held device is one of the first mobile PC's to introduce biometric security capabilities. Biometric security, in this case a fingerprint authentication system, is on the edge of technology as far as securing information. The benefits of fingerprint authentication are enormous. The most significant of them are that it is extremely difficult to reproduce someone else's fingerprint, and it is equally difficult to lose or forget your own fingerprint as opposed to a password or pin number. One of my goals for this summer is to integrate this technology with another Pocket PC application. The second task for the summer is to develop a simple application that provides an Astronaut EVA (Extravehicular Activity) Log Book capability. The Astronaut EVA Log Book is what an astronaut would use to report the status of field missions, crew physical health, successes, future plans, etc. My goal is to develop a user interface into which these data fields can be entered and stored. The applications that I am developing are created using eMbedded Visual C++ 4.0 with the Pocket PC 2003 Software Development Kit provided by Microsoft.

Logan, Julian↗
NASA NTRS2016

Operational Implementation of a Pc Uncertainty Construct for Conjunction Assessment Risk Analysis

Earlier this year the NASA Conjunction Assessment and Risk Analysis (CARA) project presented the theoretical and algorithmic aspects of a method to include the uncertainties in the calculation inputs when computing the probability of collision (Pc) between two space objects, principally uncertainties in the covariances and the hard-body radius. The output of this calculation approach is to produce rather than a single Pc value an entire probability density function that will represent the range of possible Pc values given the uncertainties in the inputs and bring CA risk analysis methodologies more in line with modern risk management theory. The present study provides results from the exercise of this method against an extended dataset of satellite conjunctions in order to determine the effect of its use on the evaluation of conjunction assessment (CA) event risk posture. The effects are found to be considerable: a good number of events are downgraded from or upgraded to a serious risk designation on the basis of consideration of the Pc uncertainty. The findings counsel the integration of the developed methods into NASA CA operations.

assessment↗
NASA NTRS2016

Development of a MEMS Preconcentrator (PC) - Gas Chromatograph (GC) for the Spacecraft Atmosphere Monitor for ISS and Orion

In this paper, we report a MEMS preconcentrator (PC) - gas chromatograph (GC) that is a crucial part of the Spacecraft Atmosphere Monitor (S.A.M.). The S.A.M. is a highly miniature gas chromatograph - mass spectrometer (GC-MS) for monitoring the atmosphere of crewed spacecraft for both trace organic compounds and the major constituents of the cabin air. The S.A.M. instrument is the next generation of GC-MS, based on JPL’s Vehicle Cabin Air Monitor (VCAM), which was launched to the International Space Station (ISS) in April 2010 and successfully operated for two years [1, 2]. The S.A.M. employs a unique MEMS PC-GC technology that replaces the macro PC-GC unit in the VCAM. We report herein the current progress of the MEMS PC-GC for the S.A.M. instrument.

Bae, Byunghoon↗
DOE OSTI2024

Conversion of Site-Specific Meteorological Data for use in CAP-88 PC

CAP-88 PC is a commonly used radiological atmospheric dispersion model. This US EPA-approved model is used to demonstrate compliance with atmospheric emission regulations for radionuclides. While the model includes a large library of meteorological data for use across the United States, there are applications when users may wish to use onsite meteorological data as an input to the CAP-88 PC model. Here, in this work, we present a work-around process for preparing and converting onsite data for use in CAP-88 PC. However, the use of local data should provide a more realistic estimate of doses to members of the public in the immediate vicinity of a facility, although the regulatory agency having jurisdiction may not accept the use of local data for compliance. Additionally, the historical meteorological records from 20+ years ago (at a site many kilometers away) might not be representative of current local weather patterns, highlighting another benefit of using local meteorological data.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1974

Midday Pc 1-2 pulsations observed at a subcleft location

A class of unstructured Pc 1-2 pulsation activity, as identified on Bar I (70.2 N) records taken during 1968-1972, is found to be present in midday hours on about half of the days in summer months. The events have some tendency to occur in the later part of the ring current recovery phase, especially at times of moderate AE when the cleft lines are just poleward of Bar I. The source lines of the Pc 1-2 are found to lie essentially outside the plasmapause. In terms of the proton cyclotron resonance instability the most likely source regions of the Bar I Pc 1-2 are the detached plasma regions convecting sunward on the dayside and the portion of the cleft plasma on the last closed field lines.

Heacock, R. R.↗
NASA NTRS1976

Simultaneous Pc 1 observations by the synchronous satellite ATS-1 and ground stations - Implications concerning IPDP generation mechanisms

Results are presented for an experimental study designed to examine the properties of Pc 1 activity observed simultaneously at ATS 1 and two Canadian ground stations. The Pc 1 activity is found to follow substorm expansion phase onsets and to occur most frequently at dusk. Dynamic spectra waves at both ground stations are that of IPDP (Intervals of Pulsations Diminishing by Period) type Pc 1. A previously proposed mechanism to explain IPDP generation, which required a rapid increase in the equatorial magnetic field to produce IPDP, is inconsistent with the dynamic spectra and magnetic field observations. Either purely azimuthal or a combination of azimuthal and radial inward drift of energetic resonant protons is an equally plausible mechanism to explain IPDP generation.

Bossen, M.↗
NASA NTRS1977

A contribution to ULF activity in the Pc 3-4 range correlated with IMF radial orientation

The paper describes an experiment to determine whether the radial orientation of the interplanetary magnetic field (IMF) is associated with ULF activity in the Pc 3-4 range. Data are obtained from base levels, undisturbed intervals, IMF and disturbance selection, and trigonometric correlation. The results obtained are discussed, noting particularly that for low Kp, the probability of enhanced amplitude noise rises as IMF orientation with respect to the nominal solar wind flow decreases in both Pc 3 and Pc 4 channels.

Greenstadt, E. W.↗
NASA NTRS1979

Pc 3 magnetic pulsations and precipitation of energetic electrons

The synchronous altitude satellite ATS 1 data and near-conjugate measurements of bremsstrahlung X-rays and ground magnetic variations were used to analyze an event of modulated auroral zone electron precipitation and magnetic pulsations in the Pc range. Transverse, azimuthal, nearly linearly polarized waves observed at ATS 1, ground magnetic pulsations at College, Alaska, and intervals of modulated electron precipitation centered on local magnetic moon, and noted in the X-ray data from Fort Yukon, Alaska, are discussed, noting that the origin of the Pc 3 waves is attributed to local field line resonances induced by Kelvin-Helmholtz instability at the magnetopause. The wave resonance model can explain observed differences in the pulsation activity at the ground, balloon, and satellite if account is taken of the spatial sensitivities of the techniques and the location of observing sites with respect to the probable location of resonant field lines. The data suggest that electron precipitation pulsations will correlate with Pc 3 magnetic pulsations when substorm injections coupled with azimuthal drift provide enhanced energetic particle fluxes with dayside resonance regions.

Arthur, C. W.↗
NASA NTRS1981

Factors controlling the occurrence of Pc 3 magnetic pulsations at synchronous orbit

The reported investigation has the purpose to extend the study of Pc 3 pulsations at synchronous orbit conducted by Arthur and McPherron (1977). A large data set is used with the goal of finding the factors related to the occurrence of Pc 3 pulsations at synchronous orbit. The results are compared with ground-based observations. The study demonstrates that the diurnal occurrence pattern has a maximum at a prenoon local time and shows a seasonal shift. Among the solar wind parameters, solar wind velocity and the direction of the IMF are found to be dominant factors. Attention is given to the analysis procedure, examples of 2-hour spectra, diurnal occurrence pattern, the correlation between solar wind parameters, and the solar wind stream structure and Pc 3 occurrence.

Takahashi, K.↗
NASA NTRS1983

A reexamination of ATS 6 magnetometer data for radially polarized Pc 3 magnetic pulsations

The polarization of Pc 3 (22-100 MHz) magnetic pulsations measured by the ATS 6 fluxgate magnetometer at synchronous orbit has been examined by using dynamic autospectral analysis. In contrast to the result obtained by Arthur et al. (1977) using the same data set, very few cases of radially polarized Pc 3 pulsations are found. It is suggested that satellite noise in the radial component, which depends on frequency f as 0.015/f (nT-squared/Hz), is responsible for this disagreement. In the presence of this type of noise, diagonalization of the spectral matrix can produce an erroneous major axis of polarization. Most Pc 3 pulsations classified as radially polarized by Arthur et al. appear to be a consequence of small amplitude azimuthal pulsations contaminated by satellite noise.

Takahashi, K.↗
NASA NTRS1988

The IBM PC at NASA Ames

Like many large companies, Ames relies very much on its computing power to get work done. And, like many other large companies, finding the IBM PC a reliable tool, Ames uses it for many of the same types of functions as other companies. Presentation and clarification needs demand much of graphics packages. Programming and text editing needs require simpler, more-powerful packages. The storage space needed by NASA's scientists and users for the monumental amounts of data that Ames needs to keep demand the best database packages that are large and easy to use. Availability to the Micom Switching Network combines the powers of the IBM PC with the capabilities of other computers and mainframes and allows users to communicate electronically. These four primary capabilities of the PC are vital to the needs of NASA's users and help to continue and support the vast amounts of work done by the NASA employees.

Peredo, James P.↗
NASA NTRS1990

Calculation of Weibull strength parameters, Batdorf flaw density constants and related statistical quantities using PC-CARES

This manual describes the operation and theory of the PC-CARES (Personal Computer-Ceramic Analysis and Reliability Evaluation of Structures) computer program for the IBM PC and compatibles running PC-DOS/MS-DOR OR IBM/MS-OS/2 (version 1.1 or higher) operating systems. The primary purpose of this code is to estimate Weibull material strength parameters, the Batdorf crack density coefficient, and other related statistical quantities. Included in the manual is the description of the calculation of shape and scale parameters of the two-parameter Weibull distribution using the least-squares analysis and maximum likelihood methods for volume- and surface-flaw-induced fracture in ceramics with complete and censored samples. The methods for detecting outliers and for calculating the Kolmogorov-Smirnov and the Anderson-Darling goodness-of-fit statistics and 90 percent confidence bands about the Weibull line, as well as the techniques for calculating the Batdorf flaw-density constants are also described.

Szatmary, Steven A.↗
NASA NTRS1991

GaAs solar cell photoresponse modeling using PC-1D V2.1

Photoresponse data of high efficiency GaAs solar cells were analyzed using PC-1D V2.1. The approach required to use PC-1D for photoresponse data analysis, and the physical insights gained from performing the analysis are discussed. In particular, the effect of Al(x)Ga(1-x)As heteroface quality was modeled. Photoresponse or spectral quantum efficiency is an important tool in characterizing material quality and predicting cell performance. The strength of the photoresponse measurement lies in the ability to precisely fit the experimental data with a physical model. PC-1D provides a flexible platform for calculations based on these physical models.

Huber, D. A.↗
NASA NTRS1991

A PC-based multispectral scanner data evaluation workstation: Application to Daedalus scanners

In late 1989, a personal computer (PC)-based data evaluation workstation was developed to support post flight processing of Multispectral Atmospheric Mapping Sensor (MAMS) data. The MAMS Quick View System (QVS) is an image analysis and display system designed to provide the capability to evaluate Daedalus scanner data immediately after an aircraft flight. Even in its original form, the QVS offered the portability of a personal computer with the advanced analysis and display features of a mainframe image analysis system. It was recognized, however, that the original QVS had its limitations, both in speed and processing of MAMS data. Recent efforts are presented that focus on overcoming earlier limitations and adapting the system to a new data tape structure. In doing so, the enhanced Quick View System (QVS2) will accommodate data from any of the four spectrometers used with the Daedalus scanner on the NASA ER2 platform. The QVS2 is designed around the AST 486/33 MHz CPU personal computer and comes with 10 EISA expansion slots, keyboard, and 4.0 mbytes of memory. Specialized PC-McIDAS software provides the main image analysis and display capability for the system. Image analysis and display of the digital scanner data is accomplished with PC-McIDAS software.

Jedlovec, Gary J.↗
NASA NTRS1991

PC 1247 + 3406 - An optically selected quasar with a redshift of 4.897

Observations of PC 1247 + 3406, a quasar with a redshift of 4.897 + or - 0.011, is described on the basis of a four-filter CCD survey designed to detect quasars with redshifts between 4.0 and 5.5. The quasar was found to be about the same brightness as PC 1158 + 4635, a quasar with a 20th-magnitude redshift of 4.733 discovered in 1989. The properties of PC 1247 + 3406 are similar to other quasars with redshifts above 3, although the absorption due to intervening neutral hydrogen is about 20 percent less than expected. The flux in the spectrum abruptly drops at a wavelength of about 910 A in the quasar's rest frame. This quick encounter with a Lyman-limit system is frequently seen in other quasars with redshifts above 4.3.

Schneider, Donald P.↗
NASA NTRS1992

Excitation of Pc 5 pulsations in the morning sector by a local injection of particles in the magnetosphere

A characteristic of Pc 5 pulsation in the morning sector is determined by use of ground magnetometer and riometer data, in conjunction with data acquired with satellites which include the magnetic fields above the ionosphere and electron fluxes at geosynchronous orbit. It is found that the onset of a flux increase in energetic electrons of 30 keV to 200 keV at geosynchronous orbit almost coincides with the onset of Pc 5 pulsation activity and riometer absorption on the ground. It is confirmed when the Pc 5 pulsation occurs on the ground, the large-scale Birkeland current system observed at ionospheric altitude splits into a number of small-scale Birkeland current pairs. It is inferred that the electron flux enhancement, presumably supplied from the tail plasma sheet associated with the substorm onset, provides stress to cause the background large-scale plasma vortex to split into the small-scale vortices. It is suggested that the field-aligned currents in the small-scale vortices propagate along the field lines and sustain the standing Alfvenic oscillations at several different, but neighboring shells of the field lines.

Saka, O.↗