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  • Astronomy  (243)
  • Computer Programming and Software  (181)
  • 1995-1999  (424)
  • 1935-1939
  • 1999  (424)
  • 1
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    UV irradiation of polycyclic aromatic hydrocarbons in ices: production of alcohols, quinones, and ethers (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1999-02-19
    Description: Polycyclic aromatic hydrocarbons (PAHs) in water ice were exposed to ultraviolet (UV) radiation under astrophysical conditions, and the products were analyzed by infrared spectroscopy and mass spectrometry. Peripheral carbon atoms were oxidized, producing aromatic alcohols, ketones, and ethers, and reduced, producing partially hydrogenated aromatic hydrocarbons, molecules that account for the interstellar 3.4-micrometer emission feature. These classes of compounds are all present in carbonaceous meteorites. Hydrogen and deuterium atoms exchange readily between the PAHs and the ice, which may explain the deuterium enrichments found in certain meteoritic molecules. This work has important implications for extraterrestrial organics in biogenesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bernstein, M P -- Sandford, S A -- Allamandola, L J -- Gillette, J S -- Clemett, S J -- Zare, R N -- New York, N.Y. -- Science. 1999 Feb 19;283(5405):1135-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NASA-Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035-1000, USA. mbernstein@mail.arc.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10024233" target="_blank"〉PubMed〈/a〉
    Keywords: Alcohols/chemistry ; Astronomical Phenomena ; Astronomy ; Deuterium/chemistry ; Ethers/chemistry ; *Evolution, Chemical ; *Exobiology ; Hydrogen/chemistry ; *Ice ; Mass Spectrometry ; Meteoroids ; Origin of Life ; Oxidation-Reduction ; Photolysis ; Polycyclic Hydrocarbons, Aromatic/*chemistry ; Quinones/chemistry ; Spectrophotometry, Infrared ; *Ultraviolet Rays
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    A barely tested hypothesis (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1999-12-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hogg, D W -- New York, N.Y. -- Science. 1999 Nov 26;286(5445):1679.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10610561" target="_blank"〉PubMed〈/a〉
    Keywords: Astronomical Phenomena ; Astronomy ; *Biological Evolution ; Selection, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Molecules on a space odyssey (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1999-03-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ehrenfreund, P -- New York, N.Y. -- Science. 1999 Feb 19;283(5405):1123-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Austrian Academy of Sciences and at Leiden Observatory, Leiden, The Netherlands. pascale@strw.leidenuniv.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10075570" target="_blank"〉PubMed〈/a〉
    Keywords: Astronomical Phenomena ; Astronomy ; *Cosmic Dust ; Deuterium/chemistry ; Earth (Planet) ; *Evolution, Chemical ; *Exobiology ; Hydrogen/chemistry ; Ice ; Meteoroids ; Origin of Life ; Polycyclic Hydrocarbons, Aromatic/*chemistry ; Ultraviolet Rays
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Goddard Geophysical and Astronomical Observatory (1999)
    In:  CASI
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    Publication Date: 2011-09-13
    Description: This report summarizes the technical parameters and the technical staff of the VLBI system at GGAO. It also gives an overview of VLBI activities during the previous year. The outlook lists the tasks planned for 1999.
    Keywords: Astronomy
    Type: International VLBI Service for Geodesy and Astrometry: 1999 Annual Report; 46-48; NASA/TP-1999-209243
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  • 5
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    Logic Design Pathology and Space Flight Electronics (1999)
    In:  CASI
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    Publication Date: 2009-05-04
    Description: This presentation looks at logic design from early in the US Space Program, it examines faults in recent logic designs, and gives some examples from the analysis of new tools and techniques.
    Keywords: Computer Programming and Software
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  • 6
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    The Role of Intelligent Agents in Advanced Information Systems (1999)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: In this presentation we review the current ongoing research within George Mason University's (GMU) Center for Information Systems Integration and Evolution (CISE). We define characteristics of advanced information systems, discuss a family of agents for such systems, and show how GMU's Domain modeling tools and techniques can be used to define a product line Architecture for configuring NASA missions. These concepts can be used to define Advanced Engineering Environments such as those envisioned for NASA's new initiative for intelligent design and synthesis environments.
    Keywords: Computer Programming and Software
    Type: Intelligent Agents and Their Potential for Future Design and Synthesis Environment; 21-38; NASA/CP-1999-208986
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  • 7
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    Using Automatic Code Generation in the Attitude Control Flight Software Engineering Process (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This paper presents an overview of the attitude control subsystem flight software development process, identifies how the process has changed due to automatic code generation, analyzes each software development phase in detail, and concludes with a summary of our lessons learned.
    Keywords: Computer Programming and Software
    Type: Proceedings of the Twenty-Third Annual Software Engineering Workshop; NASA/CP-1999-209236
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  • 8
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    Goddard Space Flight Center IVS Technology Development Center (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The GSFC IVS Technology Development Center (TDC) develops station software including the Field System (FS), scheduling software (SKED), hardware including tools for station timing and meteorology, scheduling algorithms, operational procedures, and provides a pool of individuals to assist with station implementation, check-out, upgrades, and training.
    Keywords: Computer Programming and Software
    Type: International VLBI Service for Geodesy and Astrometry: 1999 Annual Report; 256-258; NASA/TP-1999-209243
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  • 9
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    Intelligent Agents for Design and Synthesis Environments: My Summary (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This presentation gives a summary of intelligent agents for design synthesis environments. We'll start with the conclusions, and work backwards to justify them. First, an important assumption is that agents (whatever they are) are good for software engineering. This is especially true for software that operates in an uncertain, changing environment. The "real world" of physical artifacts is like that: uncertain in what we can measure, changing in that things are always breaking down, and we must interact with non-software entities. The second point is that software engineering techniques can contribute to good design. There may have been a time when we wanted to build simple artifacts containing little or no software. But modern aircraft and spacecraft are complex, and rely on a great deal of software. So better software engineering leads to better designed artifacts, especially when we are designing a series of related artifacts and can amortize the costs of software development. The third point is that agents are especially useful for design tasks, above and beyond their general usefulness for software engineering, and the usefulness of software engineering to design.
    Keywords: Computer Programming and Software
    Type: Intelligent Agents and Their Potential for Future Design and Synthesis Environment; 129-138; NASA/CP-1999-208986
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  • 10
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    The SGI/CRAY T3E: Experiences and Insights (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The focus of the HPCC Earth and Space Sciences (ESS) Project is capability computing - pushing highly scalable computing testbeds to their performance limits. The drivers of this focus are the Grand Challenge problems in Earth and space science: those that could not be addressed in a capacity computing environment where large jobs must continually compete for resources. These Grand Challenge codes require a high degree of communication, large memory, and very large I/O (throughout the duration of the processing, not just in loading initial conditions and saving final results). This set of parameters led to the selection of an SGI/Cray T3E as the current ESS Computing Testbed. The T3E at the Goddard Space Flight Center is a unique computational resource within NASA. As such, it must be managed to effectively support the diverse research efforts across the NASA research community yet still enable the ESS Grand Challenge Investigator teams to achieve their performance milestones, for which the system was intended. To date, all Grand Challenge Investigator teams have achieved the 10 GFLOPS milestone, eight of nine have achieved the 50 GFLOPS milestone, and three have achieved the 100 GFLOPS milestone. In addition, many technical papers have been published highlighting results achieved on the NASA T3E, including some at this Workshop. The successes enabled by the NASA T3E computing environment are best illustrated by the 512 PE upgrade funded by the NASA Earth Science Enterprise earlier this year. Never before has an HPCC computing testbed been so well received by the general NASA science community that it was deemed critical to the success of a core NASA science effort. NASA looks forward to many more success stories before the conclusion of the NASA-SGI/Cray cooperative agreement in June 1999.
    Keywords: Computer Programming and Software
    Type: HPCCP/CAS Workshop Proceedings 1998; 53-58; NASA/CP-1999-208757
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  • 11
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    An Alternative Lunar Ephemeris Model for On-Board Flight Software Use (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: In calculating the position vector of the Moon in on-board flight software, one often begins by using a series expansion to calculate the ecliptic latitude and longitude of the Moon, referred to the mean ecliptic and equinox of date. One then performs a reduction for precession, followed by a rotation of the position vector from the ecliptic plane to the equator, and a transformation from spherical to Cartesian coordinates before finally arriving at the desired result: equatorial J2000 Cartesian components of the lunar position vector. An alternative method is developed here in which the equatorial J2000 Cartesian components of the lunar position vector are calculated directly by a series expansion, saving valuable onboard computer resources.
    Keywords: Astronomy
    Type: 1999 Flight Mechanics Symposium; 175-184; NASA/CP-1999-209235
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  • 12
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    Using Model Checking to Validate AI Planner Domain Models (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This report describes an investigation into using model checking to assist validation of domain models for the HSTS planner. The planner models are specified using a qualitative temporal interval logic with quantitative duration constraints. We conducted several experiments to translate the domain modeling language into the SMV, Spin and Murphi model checkers. This allowed a direct comparison of how the different systems would support specific types of validation tasks. The preliminary results indicate that model checking is useful for finding faults in models that may not be easily identified by generating test plans.
    Keywords: Computer Programming and Software
    Type: Proceedings of the Twenty-Third Annual Software Engineering Workshop; NASA/CP-1999-209236
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  • 13
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    True Concurrent Thermal Engineering Integrating CAD Model Building with Finite Element and Finite Difference Methods (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Thermal engineering has long been left out of the concurrent engineering environment dominated by CAD (computer aided design) and FEM (finite element method) software. Current tools attempt to force the thermal design process into an environment primarily created to support structural analysis, which results in inappropriate thermal models. As a result, many thermal engineers either build models "by hand" or use geometric user interfaces that are separate from and have little useful connection, if any, to CAD and FEM systems. This paper describes the development of a new thermal design environment called the Thermal Desktop. This system, while fully integrated into a neutral, low cost CAD system, and which utilizes both FEM and FD methods, does not compromise the needs of the thermal engineer. Rather, the features needed for concurrent thermal analysis are specifically addressed by combining traditional parametric surface based radiation and FD based conduction modeling with CAD and FEM methods. The use of flexible and familiar temperature solvers such as SINDA/FLUINT (Systems Improved Numerical Differencing Analyzer/Fluid Integrator) is retained.
    Keywords: Computer Programming and Software
    Type: Ninth Thermal and Fluids Analysis Workshop Proceedings; 217-232; NASA/CP-1999-208695
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  • 14
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    Comparison of Integrated Analysis Methods for Two Model Scenarios (1999)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: Integrated analysis methods have the potential to substantially decrease the time required for analysis modeling. Integration with computer aided design (CAD) software can also allow a model to be more accurate by facilitating import of exact design geometry. However, the integrated method utilized must sometimes be tailored to the specific modeling situation, in order to make the process most efficient. Two cases are presented here that illustrate different processes used for thermal analysis on two different models. These examples are used to illustrate how the requirements, available input, expected output, and tools available all affect the process selected by the analyst for the most efficient and effective analysis.
    Keywords: Computer Programming and Software
    Type: Ninth Thermal and Fluids Analysis Workshop Proceedings; 37-48; NASA/CP-1999-208695
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  • 15
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    Improvements to the Unstructured Mesh Generator MESH3D (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The AIRPLANE process starts with an aircraft geometry stored in a CAD system. The surface is modeled with a mesh of triangles and then the flow solver produces pressures at surface points which may be integrated to find forces and moments. The biggest advantage is that the grid generation bottleneck of the CFD process is eliminated when an unstructured tetrahedral mesh is used. MESH3D is the key to turning around the first analysis of a CAD geometry in days instead of weeks. The flow solver part of AIRPLANE has proven to be robust and accurate over a decade of use at NASA. It has been extensively validated with experimental data and compares well with other Euler flow solvers. AIRPLANE has been applied to all the HSR geometries treated at Ames over the course of the HSR program in order to verify the accuracy of other flow solvers. The unstructured approach makes handling complete and complex geometries very simple because only the surface of the aircraft needs to be discretized, i.e. covered with triangles. The volume mesh is created automatically by MESH3D. AIRPLANE runs well on multiple platforms. Vectorization on the Cray Y-MP is reasonable for a code that uses indirect addressing. Massively parallel computers such as the IBM SP2, SGI Origin 2000, and the Cray T3E have been used with an MPI version of the flow solver and the code scales very well on these systems. AIRPLANE can run on a desktop computer as well. AIRPLANE has a future. The unstructured technologies developed as part of the HSR program are now targeting high Reynolds number viscous flow simulation. The pacing item in this effort is Navier-Stokes mesh generation.
    Keywords: Computer Programming and Software
    Type: 1999 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 213-252; NASA/CP-1999-209704/VOL1/PT1
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  • 16
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    Goddard's New Approach to IT (1999)
    In:  CASI
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    Publication Date: 2004-12-03
    Description: A general overview of the Information Systems Center (ISC) at NASA's Goddard Space Flight Center is presented. The background of the center, its reorganization, as well as the applied engineering and technology directorate and its organization are outlined. The ISC's mission and vision as well as a breakdown of the branch are reviewed. Finally, the role of the Software Engineering Laboratory (SEL) within the ISC is reported, it's short and long term goals, and current activities discussed.
    Keywords: Computer Programming and Software
    Type: Proceedings of the Twenty-Third Annual Software Engineering Workshop; NASA/CP-1999-209236
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  • 17
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    Information-Theoretic Assessment of Sample Imaging Systems (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: By rigorously extending modern communication theory to the assessment of sampled imaging systems, we develop the formulations that are required to optimize the performance of these systems within the critical constraints of image gathering, data transmission, and image display. The goal of this optimization is to produce images with the best possible visual quality for the wide range of statistical properties of the radiance field of natural scenes that one normally encounters. Extensive computational results are presented to assess the performance of sampled imaging systems in terms of information rate, theoretical minimum data rate, and fidelity. Comparisons of this assessment with perceptual and measurable performance demonstrate that (1) the information rate that a sampled imaging system conveys from the captured radiance field to the observer is closely correlated with the fidelity, sharpness and clarity with which the observed images can be restored and (2) the associated theoretical minimum data rate is closely correlated with the lowest data rate with which the acquired signal can be encoded for efficient transmission.
    Keywords: Computer Programming and Software
    Type: Optical Engineering (ISSN 0091-3286); Volume 38; No. 5; 742-762
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  • 18
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    The "Water-Fountain Nebula" IRAS 16342-3814: Hubble Space Telescope/Very Large Array Study of a Bipolar Protoplanetary Nebula (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: We present Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 images and VLA OH maser emission-line maps of the cold infrared object IRAS 16342-3814, believed to be a protoplanetary nebula. The HST images show an asymmetrical bipolar nebula, with the lobes separated by a dark equatorial waist. The two bright lobes and the dark waist are simply interpreted as bubble-like reflection nebulae illuminated by starlight escaping through polar holes in a dense, flattened, optically thick cocoon of dust, which completely obscures the central star. A faint halo can be seen surrounding each of the lobes. The bubbles are likely to have been created by a fast outflow (evidenced by H2O emission) plowing into a surrounding dense, more slowly expanding, circumstellar envelope of the progenitor asymptotic giant-branch (AGB) star (evidenced by the halo). The IRAS fluxes indicate a circumstellar mass of about 0.7 solar mass (D/2 kpc) and an AGB mass-loss rate of about 10(exp -4) solar mass/yr (V(sub exp)/15 km/s)(D/2 kpc)(sup 2) (assuming a gas-to-dust ratio of 200). OH features with the largest redshifted and blueshifted velocities are concentrated around the bright eastern and western polar lobes, respectively, whereas intermediate-velocity features generally occur at low latitudes, in the dark waist region. We critically examine evidence for the post-AGB classification of IRAS 16342-3814.
    Keywords: Astronomy
    Type: Astrophysical Journal; No. 2
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  • 19
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    Comets: Very Eccentric Characters (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: Astronomical distances, even within our own solar system, are very difficult for anyone, let alone children, to imagine. In this month's space-program-related activity, students have the opportunity to create a visual and kinesthetic model of the solar system on a scale that may begin to inspire an awed comprehension of how big space is and how small Earth is. In addition, they will learn a little basic geometry in demonstrating for themselves the difference between a circular planetary orbit and an elongated elliptical cometary orbit. As a space exploration first the Jet Propulsion Laboratory (JPL), under contract to the National Aeronautics and Space Administration (NASA), is planning to send a spacecraft to rendezvous with and land on a comet. The Space Technology 4/Champollion mission is part of NASA's New Millennium Program, the primary goal of which is to test new technologies for use in 21st century planetary and earth observing missions.
    Keywords: Astronomy
    Type: The Technology Teacher: The Voice of Technology Education; Volume 58; No. 7
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  • 20
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    Multidisciplinary Design Optimisation (MDO) Methods: Their Synergy with Computer Technology in the Design Process (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: The paper identifies speed, agility, human interface, generation of sensitivity information, task decomposition, and data transmission (including storage) as important attributes for a computer environment to have in order to support engineering design effectively. It is argued that when examined in terms of these attributes the presently available environment can be shown to be inadequate. A radical improvement is needed, and it may be achieved by combining new methods that have recently emerged from multidisciplinary design optimisation (MDO) with massively parallel processing computer technology. The caveat is that, for successful use of that technology in engineering computing, new paradigms for computing will have to be developed - specifically, innovative algorithms that are intrinsically parallel so that their performance scales up linearly with the number of processors. It may be speculated that the idea of simulating a complex behaviour by interaction of a large number of very simple models may be an inspiration for the above algorithms; the cellular automata are an example. Because of the long lead time needed to develop and mature new paradigms, development should begin now, even though the widespread availability of massively parallel processing is still a few years away.
    Keywords: Computer Programming and Software
    Type: Aeronautical Journal of the Royal Aeronautical Society; No. 2451; 373-382
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  • 21
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    The Progenitor of the New COMPTEL/ROSAT Supernova Remnant in Vela (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: We show that (1) the newly discovered supernova remnant (SNR) GROJ0852-4642/RXJ0852.0-4622 was created by a core-collapse supernova of a massive star and (2) the same supernova event that produced the Ti-44 detected by COMPTEL from this source is probably also responsible for a large fraction of the observed Al-26 emission in the Vela region detected by the same instrument. The first conclusion is based on the fact that the remnant is currently expanding too slowly given its young age for it to be caused by a Type la supernova. If the current SNR shell expansion speed is greater than 3000 km/s, a 15 solar mass. Type II supernova with a moderate kinetic energy exploding at about 150 pc away is favored. If the SNR expansion speed is lower than 2000 km/s, as derived naively from X-ray data, a much more energetic supernova is required to have occurred at approximately 250 pc away in a dense environment at the edge of the Gum Nebula. This progenitor has a preferred ejecta mass of less than or equal to 10(Solar Mass), and therefore it is probably a Type Ib or Type Ic supernova. However, the required high ambient density of n(sub H) greater than or equal to 100 cu cm in this scenario is difficult to reconcile with the regional CO data. A combination of our estimates of the age/energetics of the new SNR and the almost perfect positional coincidence of the new SNR with the centroid of the COMPTEL Al-26 emission feature of the Vela region strongly favors a causal connection. If confirmed, this will be the first case in which both Ti-44 and Al-26 are detected from the same young SNR, and together they can be used to select preferred theoretical core-collapse supernova models.
    Keywords: Astronomy
    Type: Astrophysical Journal; Volume 514; 1-4
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  • 22
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    The Astro -E/XRS Calibration Program and Results (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: XRS is the microcalorimeter X-ray detector aboard the US-Japanese ASTRO-E observatory, which is scheduled to be launched in early 2000. XRS is a high resolution spectrometer- with less than 9 eV resolution at 3 keV and better than 14 eV resolution over its bandpass ranging from about 0.3 keV to 15 keV. Here we present the results of our first calibration of the XRS instrument. We describe the methods used to extract detailed information about the detection efficiency and spectral redistribution of the instrument. We also present comparisons of simulations and real data to test our detector models
    Keywords: Astronomy
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  • 23
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    The Low-Mass X-Ray Binary X1832-330 in the Globular Cluster NGC 6652: A Serendipitous ASCA Observation (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Low Mass X-ray Binary (LMXB) X1832-330 in NGC 6652 is one of about 10 bright X-ray sources to have been discovered in Globular Clusters. We report on a serendipitous ASCA observation of this Globular Cluster LMXB, during which a Type I burst was detected and the persistent, non-burst emission of the source was at its brightest level recorded to date. No orbital modulation was detected, which argues against a high inclination for the X1832-330 system. The spectrum of the persistent emission can be fit with a power law plus a partial covering absorber, although other models are not ruled out. Our time-resolved spectral analysis through the burst shows, for the first time, clear evidence for spectral cooling from kT = 2.4 +/- 0.6 keV to kT = 1.0 +/- 0.1 keV during the decay. The measured peak flux during the burst is approximately 10% of the Eddington luminosity for a 1.4 Solar Mass neutron star. These are characteristic of a Type I burst, in the context of the relatively low quiescent luminosity of X1832-330.
    Keywords: Astronomy
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  • 24
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    Direct Measurement of the Supernova Rate in Starburst Galaxies (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short times. Many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (galactic nuclei and starburst regions), dust extintion is especially severe. Thus, determining the supernova rate in the active star forming regions of galaxies, where the supernova rate can be one or two orders of magnitude higher than the average, has proven to be difficult. From observations of SN1987A, we know that the [NiII] 6.63 micron emission line was the strongest line in the infrared spectrum for a period of a year and a half after the explosion. Since dust extintion is much less at 6.63 pm than at visible wavelengths (A(sub 6.63)/A(sub V) = 0.025), the NiII line can be used as a sensitive probe for the detection of recent supernovae. We have observed a sample of starburst galaxies at 6.63 micron using ISOCAM to search for the NiII emission line characteristic of recent supernovae. We did not detect any NiII line emission brighter than a 5sigma limit of 5 mJy. We can set upper limits to the supernova rate in our sample, scaled to the rate in M82, of less than 0.3 per year at the 90% confidence level using Bayesian methods. Assuming that a supernova would have a NiII with the same luminosity as observed in SN1987A, we find less than 0.09 and 0.15 per year at the 50% and 67% confidence levels. These rates are somewhat less if a more normal type II supernovae has a NiII line luminosity greater than the line in SN1987A.
    Keywords: Astronomy
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    A Catalog of Soft X-Ray Shadows, and More Contemplation of the 1/4 KeV Background (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: This paper presents a catalog of shadows in the 1/4 keV soft X-ray diffuse background 4 (SXRB) that were identified by a comparison between ROSAT All-Sky Survey maps and DIRB&corrected IRAS 100 micron maps. These "shadows" are the negative correlations between the surface brightness of the SXRB and the column density of the Galactic interstellar medium (ISIM) over limited angular regions (a few degrees in extent). We have compiled an extensive but not exhaustive set of 378 shadows in the polar regions of the Galaxy (Absolute value (beta) 〉 and approximately equal 20 deg.), and determined their foreground and background X-ray intensities (relative to the absorbing features), and the respective hardness ratios of that emission. The portion of the sky that was examined to find these shadows was restricted in general to regions where the minimum column density is less than and approximately equal to 4 x 10(exp 20) H/square cm, i.e., relatively high Galactic latitudes, and to regions away from distinct extended features in the SXRB such as supernova remnants and superbubbles. The results for the foreground intensities agree well with the recent results of a general analysis of the local 1/4 KeV emission while the background intensities show additional. but not unexpected scatter. The results also confirm the existence of a gradient in the hardness of the local 1/4 keV emission along a Galactic center/ anticenter axis with a temperature that varies from 10(exp 6.13) K to 10(exp 6.02) K, respectively. The average temperature of the foreground component from this analysis is 10(exp 6.08) K, compared to 10(exp 6.06) K in the previous analysis. Likewise, the average temperature for the distant component for the current and previous analyses are 10(exp 6.06) K and 10(exp 6.02) K, respectively. Finally, the results for the 1/4 keV halo emission are compared to the observed fluxes at 3/4 keV, where the lack of correlation suggests that the Galactic halo's 1/4 keV and 3/4 keV fluxes are likely produced by separate emission regions.
    Keywords: Astronomy
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    Bayesian Super-Resolved Surface Reconstruction From Multiple Images (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: Bayesian inference has been wed successfully for many problems where the aim is to infer the parameters of a model of interest. In this paper we formulate the three dimensional reconstruction problem as the problem of inferring the parameters of a surface model from image data, and show how Bayesian methods can be used to estimate the parameters of this model given the image data. Thus we recover the three dimensional description of the scene. This approach also gives great flexibility. We can specify the geometrical properties of the model to suit our purpose, and can also use different models for how the surface reflects the light incident upon it. In common with other Bayesian inference problems, the estimation methodology requires that we can simulate the data that would have been recoded for any values of the model parameters. In this application this means that if we have image data we must be able to render the surface model. However it also means that we can infer the parameters of a model whose resolution can be chosen irrespective of the resolution of the images, and may be super-resolved. We present results of the inference of surface models from simulated aerial photographs for the case of super-resolution, where many surface elements project into a single pixel in the low-resolution images.
    Keywords: Computer Programming and Software
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    Photometric Observations of 6000 Stars in the Cygnus Field (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: A small photometer to detect transits by extrasolar planets has been assembled and is being tested at Lick Observatory on Mt. Hamilton, California. The Vulcan photometer is constructed from a 30 cm focal length, F/2.5 AeroEktar reconnaissance lens and Photometrics PXL16800 CCD camera. A spectral filter is used to confine the pass band from 480 to 763 mn. It simultaneously monitors 6000 stars brighter than 12th magnitude within a single star field in the galactic plane. When the data are folded and phased to discover low amplitude transits, the relative precision of one-hour samples is about 1 part per thousand (10 x l0(exp -3)) for many of the brighter stars. This precision is sufficient to find jovian-size planets orbiting solar-like stars, which have signal amplitudes from 5 to 30 x l0(exp -3) depending on the inflation of the planet and the size of the star. Based on the frequency of giant inner-planets discovered by Doppler-velocity method, one or two planets should be detectable in a rich star field. The goal of the observations is to obtain the sizes of giant extrasolar planets in short-period orbits and to combine these with masses determined from Doppler velocity measurements to determine the densities of these planets. A further goal is to compare the measured planetary diameters with those predicted from theoretical models. From August 10 through September 30 of 1998, a forty nine square degree field in the Cygnus constellation centered at RA and DEC of 19 hr 47 min, +36 deg 55 min was observed. Useful data were obtained on twenty-nine nights. Nearly fifty stars showed some evidence of transits with periods between 0.3 and 8 days. Most had amplitudes too large to be associated with planetary transits. However, several stars showed low amplitude transits. The data for several transits of each of these two stars have been folded and been folded into 30 minute periods. Only Cygl433 shows any evidence of a flattened bottom that is expected when a small object transits a much larger primary. However when high-resolution spectra were obtained for both stars, the stars were found to be double-lined binaries so similar in size as to have indistinguishable transit depths. The low amplitude of the transits is explained if the stellar orbital planes are tipped approximately 5 degrees from the line of sight causing both binaries to show grazing transits. The two absorption lines, due to the H(sub beta) feature in each star, are apparent and indicate the presence of a binary system with similar components.
    Keywords: Astronomy
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    A Survey of Collective Intelligence (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: This chapter presents the science of "COllective INtelligence" (COIN). A COIN is a large multi-agent systems where: i) the agents each run reinforcement learning (RL) algorithms; ii) there is little to no centralized communication or control; iii) there is a provided world utility function that, rates the possible histories of tile full system. Tile conventional approach to designing large distributed systems to optimize a world utility does not use agents running RL algorithms. Rather that approach begins with explicit modeling of the overall system's dynamics, followed by detailed hand-tuning of the interactions between the components to ensure that they "cooperate" as far as the world utility is concerned. This approach is labor-intensive, often results in highly non-robust systems, and usually results in design techniques that, have limited applicability. In contrast, with COINs we wish to solve the system design problems implicitly, via the 'adaptive' character of the RL algorithms of each of the agents. This COIN approach introduces an entirely new, profound design problem: Assuming the RL algorithms are able to achieve high rewards, what reward functions for the individual agents will, when pursued by those agents, result in high world utility? In other words, what reward functions will best ensure that we do not have phenomena like the tragedy of the commons, or Braess's paradox? Although still very young, the science of COINs has already resulted in successes in artificial domains, in particular in packet-routing, the leader-follower problem, and in variants of Arthur's "El Farol bar problem". It is expected that as it matures not only will COIN science expand greatly the range of tasks addressable by human engineers, but it will also provide much insight into already established scientific fields, such as economics, game theory, or population biology.
    Keywords: Computer Programming and Software
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    Implementation of Multispectral Image Classification on a Remote Adaptive Computer (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: As the demand for higher performance computers for the processing of remote sensing science algorithms increases, the need to investigate new computing paradigms its justified. Field Programmable Gate Arrays enable the implementation of algorithms at the hardware gate level, leading to orders of m a,gnitude performance increase over microprocessor based systems. The automatic classification of spaceborne multispectral images is an example of a computation intensive application, that, can benefit from implementation on an FPGA - based custom computing machine (adaptive or reconfigurable computer). A probabilistic neural network is used here to classify pixels of of a multispectral LANDSAT-2 image. The implementation described utilizes Java client/server application programs to access the adaptive computer from a remote site. Results verify that a remote hardware version of the algorithm (implemented on an adaptive computer) is significantly faster than a local software version of the same algorithm implemented on a typical general - purpose computer).
    Keywords: Computer Programming and Software
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    Programmable Logic Application Notes (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: This column will be provided each quarter as a source for reliability, radiation results, NASA capabilities, and other information on programmable logic devices and related applications. This quarter the focus is on some experimental data on low voltage drop out regulators to support mixed 5 and 3.3 volt systems. A discussion of the Small Explorer WIRE spacecraft will also be given. Lastly, we show take a first look at robust state machines in Hardware Description Languages (VHDL) and their use in critical systems. If you have information that you would like to submit or an area you would like discussed or researched, please give me a call or e-mail.
    Keywords: Computer Programming and Software
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    SRAM Based Re-programmable FPGA for Space Applications (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: An SRAM (static random access memory)-based reprogrammable FPGA (field programmable gate array) is investigated for space applications. A new commercial prototype, named the RS family, was used as an example for the investigation. The device is fabricated in a 0.25 micrometers CMOS technology. Its architecture is reviewed to provide a better understanding of the impact of single event upset (SEU) on the device during operation. The SEU effect of different memories available on the device is evaluated. Heavy ion test data and SPICE simulations are used integrally to extract the threshold LET (linear energy transfer). Together with the saturation cross-section measurement from the layout, a rate prediction is done on each memory type. The SEU in the configuration SRAM is identified as the dominant failure mode and is discussed in detail. The single event transient error in combinational logic is also investigated and simulated by SPICE. SEU mitigation by hardening the memories and employing EDAC (error detection and correction) at the device level are presented. For the configuration SRAM (CSRAM) cell, the trade-off between resistor de-coupling and redundancy hardening techniques are investigated with interesting results. Preliminary heavy ion test data show no sign of SEL (single event latch-up). With regard to ionizing radiation effects, the increase in static leakage current (static I(sub CC)) measured indicates a device tolerance of approximately 50krad(Si).
    Keywords: Computer Programming and Software
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    The Effects of Architecture and Process on the Hardness of Programmable Technologies (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: Architecture and process, combined, significantly affect the hardness of programmable technologies. The effects of high energy ions, ferroelectric memory architectures, and shallow trench isolation are investigated. A detailed single event latchup (SEL) study has been performed.
    Keywords: Computer Programming and Software
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    Marooned on Mars: Mind-Spinning Books for Software Engineers (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: Dragonfly - NASA and the Crisis Aboard MIR (New York: HarperCollins Publishers), the story of the Russian-American misadventures on MIR. An expose with almost embarrassing detail about the inner-workings of Johnson Space Center in Houston, this book is best read with the JSC organization chart in hand. Here's the real world of engineering and life in extreme environments. It makes most other accounts of "requirements analysis" appear glib and simplistic. The book vividly portrays the sometimes harrowing experiences of the American astronauts in the web of Russian interpersonal relations and literally in the web of MIR's wiring. Burrough's exposition reveals how handling bureaucratic procedures and bulky facilities is as much a matter of moxie and goodwill as technical capability. Lessons from MIR showed NASA that getting to Mars required a different view of knowledge and improvisation-long-duration missions are not at all like the scripted and pre-engineered flights of Apollo or the Space Shuttle.
    Keywords: Computer Programming and Software
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    A Highly Doppler Blueshifted Fe-K Emission Line in the High-Redshift QSO PKS 2149-306 (1999)
    In:  CASI
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    Publication Date: 2013-08-29
    Description: We report the results from an ASCA observation of the high-luminosity, radioloud quasar PKS 2149-306 (redshift 2.345), covering the approximately 1.7 - 30 keV band in the quasar-frame. We find the source to have a luminosity of approximately 6 x 10(exp 47) ergs/s in the 2 - 10 keV band (quasar frame). We detect an emission line centered at approximately 17 keV in the quasar frame. Line emission at this energy has not been observed in any other active galaxy or quasar to date. We present evidence rejecting the possibility that this line is the result of instrumental artifacts, or a serendipitous source. The most likely explanation is blueshifted Fe-K emission (the equivalent width, is EW approximately 300 +/- 200 eV, quasar frame). Bulk velocities of the order of 0.75c are implied by the data. We show that Fe-K line photons originating in an accretion disk and Compton-scattering off a leptonic jet aligned along the disk axis can account for the emission line. Curiously. if the emission-line feature recently discovered in another quasar (PKS 0637-752, z = 0.654) at 1.6 keV in the quasar frame, is due to blueshifted OVII emission, the Doppler blueshifting factor in both quasars is similar (approximately 2.7 - 2.8).
    Keywords: Astronomy
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    A Flight/Ground/Test Event Logging Facility (1999)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The onboard control software for spacecraft such as Mars Pathfinder and Cassini is composed of many subsystems including executive control, navigation, attitude control, imaging, data management, and telecommunications. The software in all of these subsystems needs to be instrumented for several purposes: to report required telemetry data, to report warning and error events, to verify internal behavior during system testing, and to provide ground operators with detailed data when investigating in-flight anomalies. Events can range in importance from purely informational events to major errors. It is desirable to provide a uniform mechanism for reporting such events and controlling their subsequent processing. Since radiation-hardened flight processors are several years behind the speed and memory of their commercial cousins, and since most subsystems require real-time control, and since downlink rates to earth can be very low from deep space, there are limits to how much of the data can be saved and transmitted. Some kinds of events are more important than others and should therefore be preferentially retained when memory is low. Some faults can cause an event to recur at a high rate, but this must not be allowed to consume the memory pool. Some event occurrences may be of low importance when reported but suddenly become more important when a subsequent error event gets reported. Some events may be so low-level that they need not be saved and reported unless specifically requested by ground operators.
    Keywords: Computer Programming and Software
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    Near-Simultaneous Spectroscopic and Broadband Polarimetric Observations of Be Stars (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: Near simultaneous optical spectroscopic (on four nights) and broadband linear continuum (B, V, R, and I bands) polarimetric (on seven nights) observations of 29 Be stars were carried out during 1993 November-December. The program Be stars displayed wavelength dependence of intrinsic polarizations with no frequency dependence of polarimetric position angles. Some of the Be stars displayed long-term polarization variability. The Be and Be-shell stars could not be distinguished from one another solely on the basis of their polarization values. Full widths at half-maximum of the H.alpha profiles and the intrinsic linear continuum polarizations are closely correlated with the projected rotational velocities of the program stars. Photospheric-absorption-corrected equivalent widths of H.alpha profiles [W(alpha)] and the radii of H.alpha-emitting or -absorbing envelopes (R(sub e) or R(sub a)) are nonlinearly correlated with the intrinsic continuum polarizations of these stars. However, W(alpha) and R(sub e) are linearly correlated. With large uncertainties, there is a trend of spectral dependence of polarization. Detailed discussion of these results is presented in this paper.
    Keywords: Astronomy
    Type: Astronomical Journal; Volume 118; 1061-1072
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    Bright Points and Subflares in Ultraviolet Lines and X-Rays (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: We have analyzed an active region which was observed in H.alpha (Multichannel Subtractive Double Pass Spectrograph), in UV lines (SMM/UVSP), and in X-rays (SMM/HXIS). In this active region there were only a few subflares and many small bright points visible in UV and in X-rays. Using an extrapolation based on the Fourier transform, we have computed magnetic field lines connecting different photospheric magnetic polarities from ground-based magnetograms. Along the magnetic inversion lines we find two different zones: (1) a high-shear region (〉 70 deg) where subflares occur, and (2) a low-shear region along the magnetic inversion line where UV bright points are observed. In these latter regions the magnetic topology is complex with a mixture of polarities. According to the velocity field observed in the Si IV lamda.1402 line and the extrapolation of the magnetic field, we notice that each UV bright point is consistent with emission from low-rising loops with downflows at both ends. We notice some hard X-ray emissions above the bright-point regions with temperatures up to 8 x 10(exp 6) K, which suggests some induced reconnection due to continuous emergence of new flux. This reconnection is also enhanced by neighboring subflares.
    Keywords: Astronomy
    Type: Astrophysical Journal; Volume 510; 474-484
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    An Unusual Supernova in the Error Box of the Gamma-Ray Burst of 25 April 1998 (1999)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: The discovery of afterglows associated with gamma-ray bursts at X-ray, optical and radio wavelengths and the measurement of the redshifts of some of these events has established that gamma-ray bursts lie at extreme distances, making them the most powerful photon-emitters known in the Universe. Here we report the discovery of transient optical emission in the error box of the gamma-ray burst GRB980425, the light curve of which was very different from that of previous optical afterglows associated with gamma-ray bursts. The optical transient is located in a spiral arm of the galaxy ESO 184-GS2, which has a redshift velocity of only 2,550 km/ s. Its optical spectrum and location indicate that it is a very luminous supernova, which has been identified as SN1998bw. If this supernova and GRB980425 are indeed associated, the energy radiated in gamma-rays is at least four orders of magnitude less than in other gamma-ray bursts, although its appearance was otherwise unremarkable: this indicates that very different mechanisms can give rise to gamma-ray bursts. But independent of this association, the supernova is itself unusual, exhibiting an unusual light curve at radio wavelengths that requires that the gas emitting the radio photons be expanding relativistically.
    Keywords: Astronomy
    Type: Nature; Volume 395; 670-672
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    Software Surrogate (1999)
    In:  CASI
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    Publication Date: 2018-06-09
    Description: In 1994, Blackboard Technology received a NASA Phase I SBIR award entitled "A Blackboard-Based Framework for Mixed-Initiative, Crewed- Space-System Applications." This research continued in Phase II at JSC, where a generic architecture was developed in which a software surrogate serves as the operator's representative in the fast-paced realm of nearly autonomous, intelligent systems. This SBIR research effort addressed the need to support human-operator monitoring and intervention with intelligent systems such as those being developed for NASA's crewed space program.
    Keywords: Computer Programming and Software
    Type: Spinoff 1999; 73; NASA/NP-1999-10-254-HQ
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    Probing Europa's Hidden Ocean from Tidal Effects on Orbital Dynamics (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Sulfuric Acid on Europa's Surface and the Radiolytic Sulfur Cycle (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Galileo infrared spectra of Europa's surface show distorted water bands that have been attributed to hydrated evaporite salts (McCord et al., J. Geophys. Res. 104, 11827, 1999) or to the scattering properties of ice (Dalton and Clark, Bull. Am. Astron. Soc. 30, 1081, 1998).
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    The Gravity Field and Interior Structure of Callisto (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Towards an Understanding of the Mid-Infrared Surface Brightness of Normal Galaxies (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We report a mid-infrared color and surface brightness analysis of IC 10, NGC 1313, and NGC 6946, three of the nearby galaxies studied under the Infrared Space Observatory Key Project on Normal Galaxies.
    Keywords: Astronomy
    Type: Astronomical Journal
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    Autonomy and Software Technology on NASA's Deep Space One (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: NASA's Deep Space One (DS1) mission is unprecedented.
    Keywords: Computer Programming and Software
    Type: IEEE Intelligent Systems
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    The Etched Hourglass Nebula MyCn18: I. Hubble Space Telescope (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Astronomical Journal
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    World Reaction to Virtual Space (1999)
    In:  CASI
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    Publication Date: 2018-06-09
    Description: DRaW Computing developed virtual reality software for the International Space Station. Open Worlds, as the software has been named, can be made to support Java scripting and virtual reality hardware devices. Open Worlds permits the use of VRML script nodes to add virtual reality capabilities to the user's applications.
    Keywords: Computer Programming and Software
    Type: Spinoff 1999; 72; NASA/NP-1999-10-254-HQ
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    Markarian 421's Unusual Satellite Galaxy (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We present Hubble Space Telescope (HST) imagery, and ground-based spectroscopy and CCD photometry of the active galaxy Markarian 421 and its companion galaxy 14 arcsec to the ENE.
    Keywords: Astronomy
    Type: Astronomical Journal
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    HST/NICMOS Imaging of Disks and Envelopes Around Very Young Stars (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We present HST/NICMOS observations with ~ 0''.1 = 15 AU resolution of six young stellar objects in the Taurus star-formation region.
    Keywords: Astronomy
    Type: Astronomical Journal
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    Coronal Hole Myth (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: AAS, Bulletin of American Astronomical Society; Chicago, IL; United States
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  • 50
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    Near/Mid Infrared-Wavelength Study of the Interacting Galaxy Pair UGC 12914/5 -- Taffy (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: The system consists of two counter-rotating spirals having suffered a nearly face-on collsion only ~10(sup 7) years ago.
    Keywords: Astronomy
    Type: Astronomical Journal
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    Galileo Software Interface Specification -- Spacecraft Event File (SEF) Phase 2 (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: This Software Interface Specification (SIS) describes the form and syntax of each S/C Event File (SEF) which is a product of the Mission Sequence System (MSS).
    Keywords: Computer Programming and Software
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    Using Artificial Intelligence Planning to Automate Science Image Data Analysis (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: In recent times, improvements in imaging technology have made available an incredible array of information in image format.
    Keywords: Computer Programming and Software
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    A Process for Verifying and Validating Requirements for Fault Tolerant Systems Using Model Checking (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Model checking is shown to be an effective tool in validating the behavior of a fault tolerant embedded spacecraft controller. The case study presented here shows that by judiciously abstracting away extraneous complexity, the state space of the model could be exhaustively searched allowing critical functional requirement to be validated down to the design level.
    Keywords: Computer Programming and Software
    Type: Transactions on Software Engineering
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    The Dark Side of Iapetus and Hyperion: One and the Same? (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padova; Italy
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    C II 158 ??bservations of a Sample of Late-type Galaxies from the Virgo Cluster (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We have observed 19 Virgo cluster spiral galaxies with the Long Wavelength Spectrometer (LWS) onboard ESAs Infrared Space Observatory (ISO) obtaining spectra around the [CII] 157.741 ??ine structure line.
    Keywords: Astronomy
    Type: Monthly Notices of the Royal Astronomical Society
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    ROAMS: Rover Analysis, Modeling and Simulation Software (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: In this paper, we present the development of ROAMS software for real-time simulation of mobile robotic vehicles.
    Keywords: Computer Programming and Software
    Type: i-SAIRAS; Noordwijk; Netherlands
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    A New Estimate of Hubble's Constant From The Gravitational Lens PKS 1830-211 (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: American Astronomical Society - Astronomy; Austin, TX; United States
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    Ground and Space-based Optical & IR Stellar Interferometry (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Japan National Astronomical Observatory; Tokyo; Japan
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    The Etched Hourglass Nebula MyCn18: II A Spatio-Kinematic Model (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We have observed MyCn18, a young Planetary Nebulae with HST/WFPC2 and presented the observational results in an earlier paper. Here we present a detailed spatial/kinematical model of H alpha emission from the nebula.
    Keywords: Astronomy
    Type: Astronomical Journal
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    The Astronomical Low Frequency Array: A Proposed Explorer Mission for Radio Astronomy (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: A radio interferometer array in space providing high dynamic range images with unprecedented angular resolution over the broad frequency range from 0.030 - 30 MHz will open new vistas in solar, terrestial, galactic, and extragalactic astrophysics.
    Keywords: Astronomy
    Type: American Geophysical Union; United States
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    Cryocooler Options for Next Generation Space Telescope (NGST) and Other Space Applications (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We present a summary of cryocoolers that are presently available or in development and would be suitable for support of mid-infrared camera on the Next Generation Space Telescope.
    Keywords: Astronomy
    Type: Publications of the Astronomical Society of the Pacific
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    New VLA Observations for the HH 1-2 Region: Evidence for Density Enhancements Moving Along the Axis of the VLA 1 Radio Jet (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Using the Very Large Array, we have carried out new, sensitive radio continuum observations at 6 and 3.6 cm of the HH 1-2 region. The comparison between the 6 cm maps made from data taken in 1986.2 and 1992.9 indicates that VLA 1, the exciting source of the HH 1-2 flow, has suffered a morphological change that is attributed to the motion of a symmetric pair of knots along the axis of the radio jet.
    Keywords: Astronomy
    Type: Astronomical Journal
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    Microarcsecond Astrometry as a Probe of Circumstellar Structure (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: 195th American Astronomical Society; Atlanta, GA; United States
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    Differential Astrometry of the 61 Cygni System with the Palomar Testbed Interferometer (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: American Astronomical Society; Atlanta, GA; United States
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    Differential Astrometry with the Keck Interferometer (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Among the Keck Interferometer's high priority science programs will be the differential astrometric detection of planetary companions to nearby stars.
    Keywords: Astronomy
    Type: Working on the Fringe Conference; Dana Point, CA; United States
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    Predicting Stellar Angular Sizes (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Reliable prediction of stellar diameters, particularly angular diameters, is a useful and necessary tool for the increasing number of milliarcsecond resolution studies being carried out in the astronomical community.
    Keywords: Astronomy
    Type: Working on the Fringe Conference; Dana Point, CA; United States
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    Ferrate (VI) as a Possible Oxidant on the Martian Surface (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Proceedings of Bio-Astronomy|Bio-Astronomy; United States
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    New Millennium Program: Space Flight Validation of Advanced Technologies for Future Science Missions (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: 31st Annual Meeting of the Division of Planetary Sciences of the American Astronomical Society; Padua; Italy
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    A Three Dimensional Thermal Model of an Irregular Cometary Nucleus (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    The Temporal Activity of IO's Hot Spots: Recent Results From Galileo (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padova; Italy
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    Anticorrelation of 5-mue Brightness and Low Albedo Features in Jovian NEB (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Loki as Observed by the Near-Infrared Mapping Spectrometer (NIMS) (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: The Galileo spacecraft has been observing Io throughout the Prime and Europa missions.
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Probing Europa's Hidden Ocean From Tidal Effects on Orbital Dynamics (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Indirect observations of Eurpoa suggest that the Jovian satellite may have a liquid ocean underneath its ice surface.
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Practical Aspects of Calibration Near-Infrared Interferometer Data: Predicting Stellar Angular Sizes (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Reliable prediction of stellar diameters, particularly angular diameters, is a useful and necessary tool for the increasing number of milliarcsecond resolution studies being carried out in the astronomical community.
    Keywords: Astronomy
    Type: Publications of the Astronomical Society of the Pacific
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    Submillimeter Imaging of the Luminous Infrared Galaxy Pair VV114 (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We report on 450 and 850 mue observations of the interacting galaxy pair, VV114E+W (IC 1623), taken with the SCUBA camera on the James Clerk Maxwell Telescope, and near-infrared observations taken with UFTI on the UK Infrared Telescope.
    Keywords: Astronomy
    Type: Astronomical Journal
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    FoilSim: Basic Aerodynamics Software Created (1999)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: FoilSim is interactive software that simulates the airflow around various shapes of airfoils. The graphical user interface, which looks more like a video game than a learning tool, captures and holds the students interest. The software is a product of NASA Lewis Research Center s Learning Technologies Project, an educational outreach initiative within the High Performance Computing and Communications Program (HPCCP).This airfoil view panel is a simulated view of a wing being tested in a wind tunnel. As students create new wing shapes by moving slider controls that change parameters, the software calculates their lift. FoilSim also displays plots of pressure or airspeed above and below the airfoil surface.
    Keywords: Computer Programming and Software
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Characterization of a Recoverable Flight Control Computer System (1999)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The design and development of a Closed-Loop System to study and evaluate the performance of the Honeywell Recoverable Computer System (RCS) in electromagnetic environments (EME) is presented. The development of a Windows-based software package to handle the time-critical communication of data and commands between the RCS and flight simulation code in real-time while meeting the stringent hard deadlines is also submitted. The performance results of the RCS and characteristics of its upset recovery scheme while exercising flight control laws under ideal conditions as well as in the presence of electromagnetic fields are also discussed.
    Keywords: Computer Programming and Software
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    National Combustion Code, a Multidisciplinary Combustor Design System, Will Be Transferred to the Commercial Sector (1999)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The NASA Lewis Research Center and Flow Parametrics will enter into an agreement to commercialize the National Combustion Code (NCC). This multidisciplinary combustor design system utilizes computer-aided design (CAD) tools for geometry creation, advanced mesh generators for creating solid model representations, a common framework for fluid flow and structural analyses, modern postprocessing tools, and parallel processing. This integrated system can facilitate and enhance various phases of the design and analysis process.
    Keywords: Computer Programming and Software
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    High-Performance, Low-Complexity Codes Researched for Communication Channels (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: NASA Lewis Research Center s Communications Technology Division has an ongoing program in the development of efficient channel coding schemes for satellite communications applications. Through a university grant, as a part of this research, the University of Toledo is investigating the performance of turbocodes, which use parallel concatenation of non-systematic convolutional encoders with an interleaver. The error correcting capacity of these codes is close to the Shannon limit. The research emphasis is on the development of low-complexity, but higher rate (greater than one half), turbocodes and on the iterative decoding of block codes.
    Keywords: Computer Programming and Software
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Cassini Radio Science Experiments on Saturn and Titan Preserved Because of Lewis Analysis (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The Cassini mission to Saturn is an international venture with participation from NASA, the European Space Agency, and the Italian Space Agency. The Cassini spacecraft was launched from Cape Canaveral in October 1997 and is scheduled to arrive at Saturn in July 2004. After arrival, the spacecraft will orbit Saturn about 60 times over a period of 4 years. During this time, the Cassini Radio Science Subsystem will be used to investigate the atmosphere and rings of Saturn and the atmosphere of its largest moon, Titan--which is larger than Mercury and is the only moon in our solar system with a dense atmosphere. A critical component in Cassini s Radio Science Subsystem is a traveling-wave tube (TWT) that was designed at the NASA Lewis Research Center and built by Hughes Electronic Dynamics Division (ref. 1). This TWT will amplify downlink microwave signals at a frequency of 32 GHz for the Deep Space Network and will be involved in a number of experiments. These include occultation experiments in which the microwave signal will be beamed through rings and atmospheres toward Earth. Researchers will analyze the received signals to determine the sizes and distributions of the particles in the rings and the structure and composition of the atmospheres. The Radio Science Subsystem also will also be used to more accurately determine the mass and size of Saturn and its moons, to investigate the solar corona, and to search for gravity waves from outside the solar system.
    Keywords: Astronomy
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    A Phase Shifting and Nulling Interferometer for TPF (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We present an interferometer design that provides a null at the star and a direct measurement of both visibility amplitude and phase of the planets.
    Keywords: Astronomy
    Type: Darwin and Astronomy, The Infrared Space Interferometer; Stockholm; Sweden
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    Amateur-Professional Cooperation: Lessons Learned From the International Halley Watch 1981-1989 (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: The International Halley Watch (IHW) was a focused coordination effort to obtain the most complete collection of data ever asembled on a comet.
    Keywords: Astronomy
    Type: Publications of the Astronomical Society of the Pacific
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    CARES/Life Ceramics Durability Evaluation Software Enhanced for Cyclic Fatigue (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The CARES/Life computer program predicts the probability of a monolithic ceramic component's failure as a function of time in service. The program has many features and options for materials evaluation and component design. It couples commercial finite element programs--which resolve a component's temperature and stress distribution--to reliability evaluation and fracture mechanics routines for modeling strength-limiting defects. The capability, flexibility, and uniqueness of CARES/Life have attracted many users representing a broad range of interests and has resulted in numerous awards for technological achievements and technology transfer. Recent work with CARES/Life was directed at enhancing the program s capabilities with regards to cyclic fatigue. Only in the last few years have ceramics been recognized to be susceptible to enhanced degradation from cyclic loading. To account for cyclic loads, researchers at the NASA Lewis Research Center developed a crack growth model that combines the Power Law (time-dependent) and the Walker Law (cycle-dependent) crack growth models. This combined model has the characteristics of Power Law behavior (decreased damage) at high R ratios (minimum load/maximum load) and of Walker law behavior (increased damage) at low R ratios. In addition, a parameter estimation methodology for constant-amplitude, steady-state cyclic fatigue experiments was developed using nonlinear least squares and a modified Levenberg-Marquardt algorithm. This methodology is used to give best estimates of parameter values from cyclic fatigue specimen rupture data (usually tensile or flexure bar specimens) for a relatively small number of specimens. Methodology to account for runout data (unfailed specimens over the duration of the experiment) was also included.
    Keywords: Computer Programming and Software
    Type: Research and Technology 1998; NASA/TM-1999-208815
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    Panel: Practical Issues in Implementing Software Reliability Measurement (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Many ways of estimating software systems' reliability, or reliability-related quantities, have been developed over the past several years. In this panel, we discuss practical issues to be addressed in implementing software reliabilty measurement techniques in a production development environment.
    Keywords: Computer Programming and Software
    Type: IEEE, International Symposium on Software Reliability Engineering; Boca Raton, FL; United States
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    Modeling Viking Era Water Ice Clouds (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Managing Software Requirements in the Context of Scientific Enterprise (1999)
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    Publication Date: 2018-06-08
    Keywords: Computer Programming and Software
    Type: 2000 IEEE Aerospace Conference; Big Sky, MT; United States
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    Europa's Thermal Emission (1999)
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Scientific Objectives and Capabilities of the DS2 Evolved Water Experiment (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Towards an Understanding of the Globular Cluster Over-abundance Around the Central Giant Elliptical NGC 1399 (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We investigate the kinematics of a combined sample of 74 globular clusters around NGC 1399.
    Keywords: Astronomy
    Type: The Astronomical Journal
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    Astrometry from Mutual Phenomena of the Galilean Satellites in 1990-1991 (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: The first extensive photometric observations of the mutual eclipses and occultations of the Galilean satellites date back to Jupiter's 1973 apparition.
    Keywords: Astronomy
    Type: Astronomical Journal
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    How can Wave Behavior Help Us Find Planets Around Distant Stars? (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Here we will see how waves act in water. We will also see how the same kinds of wave behavior occur in other everday situations.
    Keywords: Astronomy
    Type: International Technolgoy Education Association; United States
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    Timing of Martian Magnetic Anomalies (1999)
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    The Temporal Activity of IO's Hot Spots: Recent Results from Galileo (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Innovative Language-Based & Object-Oriented Structured AMR Using Fortran 90 and OpenMP (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Parallel adaptive mesh refinement (AMR) is an important numerical technique that leads to the efficient solution of many physical and engineering problems. In this paper, we describe how AMR programing can be performed in an object-oreinted way using the modern aspects of Fortran 90 combined with the parallelization features of OpenMP.
    Keywords: Computer Programming and Software
    Type: New Trends in HIgh Performance Computing; Stony Brook, NY; United States
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    A Framework-Based Approach to Science Software Development (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Computer Programming and Software
    Type: 2000 IEEE Aerospace Conference; Big Sky, MT; United States
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    The Deuterium Chemistry in a Protoplanetary Disk (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: International Astronomical Union (IAU) Symposium: 197: Astrochemistry from Molecular Clouds to Planetary Systems; Cheju; South Korea
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    Comet Simulation Experiments at JPL (1999)
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    Publication Date: 2018-06-08
    Keywords: Astronomy
    Type: Division for Planetary Sciences Meeting of the American Astronomical Society; Padua; Italy
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    Issues in Software Engineering for Survivable Systems (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Computer Programming and Software
    Type: IEEE, 21st International Conference on Software; Los Angeles, CA; United States
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    Contour: The Comet Nucleus Tour Mission (1999)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Target Selection: emphasis on diversity and unique objects. Flybys of three comets.
    Keywords: Astronomy
    Type: International Astronomical Union, Impact Workshop; Turin; Italy
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    An X-ray Selected Galaxy Cluster at z = 1.26 (sup 1,2) (1999)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: We report the discovery of an X-ray luminous galaxy cluster at z = 1.26.
    Keywords: Astronomy
    Type: The Astronomical Journal
    Format: text
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