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  • 1
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    TWOBODY - IMPROVED IMPLEMENTATION OF LAGRANGE MULTIPLIER (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The Lagrange multiplier method has been used for many years by engineers to develop equations of motion in multibody problems. Use of the Lagrange multiplier has an advantage over some other formulations in that it preserves the original simple form of the equations of motion for each body. However, in typical time-varying dynamics simulations that use the Lagrange multiplier, computational instability can occur because integration error causes the two (or more) attached bodies to drift apart and violate the constraints. The computational instability usually happens suddenly, and the computed values "blow up" within a few time steps. TWOBODY utilizes a new programming technique which eliminates computational instability in multibody simulations that use the Lagrange multiplier. This new technique uses the constraint equations, instead of integration, to determine the coordinates that are not independent. TWOBODY employs a simple model, consisting of a solid rocket booster and a parachute connected by a frictionless swivel, to illustrate the new technique. TWOBODY is written in FORTRAN 77 for IBM PC series and compatible computers running MS-DOS. It requires 100K of RAM for execution. A sample executable is included with the distribution media. The standard distribution medium for this program is one 5.25 inch 360K MS-DOS format diskette. The program was developed on a 486/D33 workstation with lpi FORTRAN in 1992.
    Keywords: NUMERICAL ANALYSIS
    Type: MFS-28774
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  • 2
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    Ultrahigh resolution photographic films for X-ray/EUV/FUV astronomy (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The quest for ultrahigh resolution full-disk images of the sun at soft X-ray/EUV/FUV wavelengths has increased the demand for photographic films with broad spectral sensitivity, high spatial resolution, and wide dynamic range. These requirements were made more stringent by the recent development of multilayer telescopes and coronagraphs capable of operating at normal incidence at soft X-ray/EUV wavelengths. Photographic films are the only detectors now available with the information storage capacity and dynamic range such as is required for recording images of the solar disk and corona simultaneously with sub arc second spatial resolution. During the Stanford/MSFC/LLNL Rocket X-Ray Spectroheliograph and Multi-Spectral Solar Telescope Array (MSSTA) programs, we utilized photographic films to obtain high resolution full-disk images of the sun at selected soft X-ray/EUV/FUV wavelengths. In order to calibrate our instrumentation for quantitative analysis of our solar data and to select the best emulsions and processing conditions for the MSSTA reflight, we recently tested several photographic films. These studies were carried out at the NIST SURF II synchrotron and the Stanford Synchrotron Radiation Laboratory. In this paper, we provide the results of those investigations.
    Keywords: OPTICS
    Type: In: Multilayer and grazing incidence X-ray(EUV optics for astronomy and projection lithography; Proceedings of the Meeting, San Diego, CA, July 19-22, 1992 (A93-39601 15-74); p. 549-561.
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  • 3
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    Data acquisition and analysis on a Macintosh (1991)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The introduction of inexpensive analog-to-digital boards for the Macintosh opens the way for its use in areas that have previously been filled by either specialized, dedicated or more expensive mainframe based systems. Two such Macintosh-based systems are the Acoustic Laboratory Data Acquisition System (ALDAS) and the Jet Calibration and Hover Test Facility (JCAHT) data acquisition system. ALDAS provides an inexpensive, transportable means to digitize four channels at up to 50,000 samples per second and analyze this data. The ALDAS software package was written for use with rotorcraft acoustics and performs automatic acoustic calibration of channels, data display, and various types of data analysis. The program can use data obtained either from internal analog-to-digital conversion or discrete external data imported in ASCII format. All aspects of ALDAS can be improved as new hardware becomes available and new features are introduced into the code. The JCAHT data acquisition system was built as not only an analysis program but also to act as the online safety monitoring system. This paper will provide an overview of these systems.
    Keywords: COMPUTER SYSTEMS
    Type: In: AHS and Royal Aeronautical Society, Technical Specialists' Meeting on Rotorcraft Acoustics(Fluid Dynamics, Philadelphia, PA, Oct. 15-17, 1991, Proceedings (A93-29401 10-71); 21 p.
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  • 4
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    Prediction of LDEF exposure to the ionizing radiation environment (1996)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Predictions of the LDEF mission's trapped proton and electron and galactic cosmic ray proton exposures have been made using the currently accepted models with improved resolution near mission end and better modeling of solar cycle effects. An extension of previous calculations, to provide a more definitive description of the LDEF exposure to ionizing radiation, is represented by trapped proton and electron flux as a function of mission time, presented considering altitude and solar activity variation during the mission and the change in galactic cosmic ray proton flux over the mission. Modifications of the AP8MAX and AP8MIN fluence led to a reduction of fluence by 20%. A modified interpolation model developed by Daly and Evans resulted in 30% higher dose and activation levels, which better agreed with measured values than results predicted using the Vette model.
    Keywords: Life Sciences (General)
    Type: Radiation measurements (ISSN 1350-4487); Volume 26; 6; 893-9
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  • 5
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    The space radiation environment in low altitude and low inclination orbits (1970)
    In:  CASI
    Details
    Publication Date: 2005-11-27
    Description: Charged particle dose rates for men and radiation sensitive materials during long-duration flights in low orbit
    Keywords: SPACE RADIATION
    Type: OPT. TELESCOPE TECHNOL. 1970; P 495-499
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  • 6
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    Plane isotropic buildup factors for bremsstrahlung calculations (1968)
    In:  CASI
    Details
    Publication Date: 2006-02-13
    Description: Monte Carlo generation of plane isotropic buildup factors for bremsstrahlung calculations
    Keywords: SPACE RADIATION
    Type: PROTECT. AGAINST SPACE RADIATION 1968; P 517-527
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  • 7
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    The calculation of electron and bremsstrahlung dose rates (1968)
    In:  CASI
    Details
    Publication Date: 2006-02-13
    Description: Electron and bremsstrahlung dose rate calculations from Monte Carlo energy transfer method and bremsstrahlung production method
    Keywords: SPACE RADIATION
    Type: PROTECT. AGAINST SPACE RADIATION 1968; P 529-538
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  • 8
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    Spectra, composition, and interactions of nuclei with magnet interaction chambers (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Emulsion chambers will be flown in the Astromag Facility to measure the cosmic ray composition and spectra to 10 exp 15 eV total energy and to definitively study the characteristics of nucleus-nucleus interactions above 10 exp 12 eV/n. Two configurations of emulsion chambers will be flown in the SCIN/MAGIC experiment. One chamber has an emulsion target and a calorimeter similar to those recently flown on balloons for composition and spectra measurements. The other has an identical calorimeter and a low-density target section optimized for performing rigidity measurements on charged particles produced in interactions. The transverse momenta of charged and neutral mesons, direct hadronic pairs from resonance decays and interference effects, and possible charge clustering in high-density states of matter will be studied.
    Keywords: SPACE RADIATION
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  • 9
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    Radiation dose from reentrant electrons (2001)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: In estimating the crew exposures during an extra vehicular activity (EVA), the contribution of reentrant electrons has always been neglected. Although the flux of these electrons is small compared to the flux of trapped electrons, their energy spectrum extends to several GeV compared to about 7 MeV for trapped electrons. This is also true of splash electrons. Using the measured reentrant electron energy spectra, it is shown that the dose contribution of these electrons to the blood forming organs (BFO) is more that 10 times greater than that from the trapped electrons. The calculations also show that the dose-depth response is a very slowly changing function of depth, and thus adding reasonable amounts of additional shielding would not significantly lower the dose to BFO. Published by Elsevier Science Ltd.
    Keywords: Life Sciences (General)
    Type: Radiation measurements (ISSN 1350-4487); Volume 33; 3; 369-72
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  • 10
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    Approximate angular distribution and spectra for geomagnetically trapped protons in low-earth orbit (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The highly anisotropic nature of the radiation in the low-earth orbit has been ignored for most spacecraft shielding calculations made to date because the standard environmental models describe the omnidirectional flux only, because the varying attitude of the spacecraft in the environment is assumed to average out the effect and because of the added complexity of the calculation. The Space Station is planned to be stabilized with respect to the velocity vector and local vertical. Thus it will pass through the South Atlantic Anomaly where most of the radiation flux is encountered in much the same attitude on each pass. Any calculation including a complex shielding geometry should thus consider the angular distributuon of the incident radiation. An approximate trapped proton angular distribution is presented which includes both the 'pan caked' distribution relative to the magnetic field direction and the east-west effect which is energy dependent. This distribution is then used with a planar shielding geometry to obtain an estimate of the effect of the anisotropy on radiation dose rates in spacecraft.
    Keywords: SPACE RADIATION
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