300 research outputs found
Proceedings: Computer Science and Data Systems Technical Symposium, volume 2
Progress reports and technical updates of programs being performed by NASA centers are covered. Presentations in viewgraph form, along with abstracts, are included for topics in three catagories: computer science, data systems, and space station applications
Proceedings: Computer Science and Data Systems Technical Symposium, volume 1
Progress reports and technical updates of programs being performed by NASA centers are covered. Presentations in viewgraph form are included for topics in three categories: computer science, data systems and space station applications
Architecture of autonomous systems
Automation of Space Station functions and activities, particularly those involving robotic capabilities with interactive or supervisory human control, is a complex, multi-disciplinary systems design problem. A wide variety of applications using autonomous control can be found in the literature, but none of them seem to address the problem in general. All of them are designed with a specific application in mind. In this report, an abstract model is described which unifies the key concepts underlying the design of automated systems such as those studied by the aerospace contractors. The model has been kept as general as possible. The attempt is to capture all the key components of autonomous systems. With a little effort, it should be possible to map the functions of any specific autonomous system application to the model presented here
Bibliometrics Seminar
On 22 May 2014, the University Library System, University of Pittsburgh, held a Bibliometrics Seminar, a program detailing several research library service models for support of research evaluation and assessment. Three of the featured speakers--from academic libraries in the USA (Mayo), the UK (Rowlands), and Australia (Thomas)--discuss the development and operation of such services in their organizations, noting the drivers for development, the process of setting up the service, and the impact of the service on both the library and the institution. A faculty colleague (Larsen) talks about his needs for research assessment as both a senior researcher and university manager. Presentation 1: "Providing a Library Metrics Service: a perspective from an academic library within an Australian University" by Dr. Amberyn Thomas, Manager, Scholarly Publications, University of Queensland, Australia. Presentation 2: "Library Research Services at the University of Leicester, UK" by Ian Rowlands, Research Services Manager and University Bibliometrician, University of Leicester. Presentation 3: "Research Connection: Expertise to Advance Your Success" by Alexa Mayo, MLS AHIP, Health Sciences and Human Services Library, University of Maryland, Baltimore. Presentation 4: "Bibliometric Research Services - an iSchool Dean's Perspective" by Ronald L. Larsen, Dean and Professor, School of Information Sciences, University of Pittsburgh. The program for the event and a recording of the presentations are also included
Probability Density Functions of Observed Rainfall in Montana
The question of whether a rain rate probability density function (PDF) can vary uniformly between precipitation events is examined. Image analysis on large samples of radar echoes is possible because of advances in technology. The data provided by such an analysis easily allow development of radar reflectivity factors (and by extension rain rate) distribution. Finding a PDF becomes a matter of finding a function that describes the curve approximating the resulting distributions. Ideally, one PDF would exist for all cases; or many PDF's that have the same functional form with only systematic variations in parameters (such as size or shape) exist. Satisfying either of theses cases will, validate the theoretical basis of the Area Time Integral (ATI). Using the method of moments and Elderton's curve selection criteria, the Pearson Type 1 equation was identified as a potential fit for 89 percent of the observed distributions. Further analysis indicates that the Type 1 curve does approximate the shape of the distributions but quantitatively does not produce a great fit. Using the method of moments and Elderton's curve selection criteria, the Pearson Type 1 equation was identified as a potential fit for 89% of the observed distributions. Further analysis indicates that the Type 1 curve does approximate the shape of the distributions but quantitatively does not produce a great fit
AD (Attacker Defender) Game
Information Dynamics is a framework for agent-based systems that gives
a central position to the role of information, time, and the value of
information.
We illustrate system design in the Information Dynamics Framework by
developing an intelligence game called AD involving attackers,
defenders and targets operating in some space of locations.
The goal of the attackers is to destroy all targets.
Target destruction takes place when the number of attackers in
the target's neighborhood exceeds the number of defenders in this
neighborhood by a value WINNING_DIFFERENCE.
The goal of defenders is to prevent attackers from achieving their goal.
(Also UMIACS-TR-2001-45
Broadband UBVRI Photometry of Horizontal-Branch and Metal-Poor Candidates from the HK and Hamburg/ESO Surveys. I
We report broadband UBV and/or BVRI CCD photometry for a total of 1857 stars
in the thick-disk and halo populations of the Galaxy. The majority of our
targets were selected as candidate field horizontal-branch or other A-type
stars (FHB/A, N = 576), or candidate low-metallicity stars (N = 1221), from the
HK and Hamburg/ESO objective-prism surveys. Similar data for a small number of
additional stars from other samples are also reported.
These data are being used for several purposes. In the case of the FHB/A
candidates they are used to accurately separate the lower-gravity FHB stars
from various higher-gravity A-type stars, a subsample that includes the
so-called Blue Metal Poor stars, halo and thick-disk blue stragglers,
main-sequence A-type dwarfs, and Am and Ap stars. These data are also being
used to derive photometric distance estimates to high-velocity hydrogen clouds
in the Galaxy and for improved measurements of the mass of the Galaxy.
Photometric data for the metal-poor candidates are being used to refine
estimates of stellar metallicity for objects with available medium-resolution
spectroscopy, to obtain distance estimates for kinematic analyses, and to
establish initial estimates of effective temperature for analysis of
high-resolution spectroscopy of the stars for which this information now
exists.Comment: 22 pages, including 3 figures, 5 tables, and two ascii files of full
data, accepted for publication in the Astrophysical Journal (Supplements
The Century Survey Galactic Halo Project III: A Complete 4300 deg^2 Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo
We present a complete spectroscopic survey of 2414 2MASS-selected blue
horizontal branch (BHB) candidates selected over 4300 deg^2 of the sky. We
identify 655 BHB stars in this non-kinematically selected sample. We calculate
the luminosity function of field BHB stars and find evidence for very few hot
BHB stars in the field. The BHB stars located at a distance from the Galactic
plane |Z|<4 kpc trace what is clearly a metal-weak thick disk population, with
a mean metallicity of [Fe/H]= -1.7, a rotation velocity gradient of
dv_{rot}/d|Z|= -28+-3.4 km/s in the region |Z|<6 kpc, and a density scale
height of h_Z= 1.26+-0.1 kpc. The BHB stars located at 5<|Z|<9 kpc are a
predominantly inner-halo population, with a mean metallicity of [Fe/H]= -2.0
and a mean Galactic rotation of -4+-31 km/s. We infer the density of halo and
thick disk BHB stars is 104+-37 kpc^-3 near the Sun, and the relative
normalization of halo to thick-disk BHB stars is 4+-1% near the Sun.Comment: 12 pages in emulateapj format, accepted for publication in February
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