13,704 research outputs found
StorySpinner: Controlling Narrative Pace in Hyperfiction
This paper describes the StorySpinner system, a sculptural hypertext reader used as a test bed for experimenting with the authoring of narrative flow in automatically generated stories. An overview of the system is presented along with discussion and conclusions arising from initial user trials
Performance analysis of the ascent propulsion system of the Apollo spacecraft
Activities involved in the performance analysis of the Apollo lunar module ascent propulsion system are discussed. A description of the ascent propulsion system, including hardware, instrumentation, and system characteristics, is included. The methods used to predict the inflight performance and to establish performance uncertainties of the ascent propulsion system are discussed. The techniques of processing the telemetered flight data and performing postflight performance reconstruction to determine actual inflight performance are discussed. Problems that have been encountered and results from the analysis of the ascent propulsion system performance during the Apollo 9, 10, and 11 missions are presented
Linking Locations: Storytelling with Pervasive Technology
With online location-aware smart phones in more and more pockets, storytelling is moving to the streets. Simultaneously, an increasing abundance of Linked Data is being made available, complete with geographical information. In this paper, we review the state of the art and suggest approaches to, and issues with, a storytelling system that combines these two technologies
On wild ramification in quaternion extensions
Quaternion extensions are often the smallest extensions to exhibit special
properties. In the setting of the Hasse-Arf Theorem, for instance, quaternion
extensions are used to illustrate the fact that upper ramification numbers need
not be integers. These extensions play a similar role in Galois module
structure. To better understand these examples, we catalog the ramification
filtrations that are possible in totally ramified extensions of dyadic number
fields. Interestingly, we find that the catalog depends, for sharp lower
bounds, upon the refined ramification filtration, which is associated with the
biquatratic subfield. Moreover these examples, as counter-examples to the
conclusion of Hasse-Arf, occur only when the refined filtration is, in two
different ways, extreme.Comment: 19 pages. This is an extensive revision of the earlier draf
Dark Matter Subhalos In the Fermi First Source Catalog
The Milky Way's dark matter halo is thought to contain large numbers of
smaller subhalos. These objects can contain very high densities of dark matter,
and produce potentially observable fluxes of gamma rays. In this article, we
study the gamma ray sources in the Fermi Gamma Ray Space Telescope's recently
published First Source Catalog, and attempt to determine whether this catalog
might contain a population of dark matter subhalos. We find that, while
approximately 20-60 of the catalog's unidentified sources could plausibly be
dark matter subhalos, such a population cannot be clearly identified as such at
this time. From the properties of the sources in the First Source Catalog, we
derive limits on the dark matter's annihilation cross section that are
comparably stringent to those derived from recent observations of dwarf
spheroidal galaxies.Comment: 11 pages, 9 figures V2: Minor errors in Figure 3 correcte
Metered oxygen supply aids treatment of domestic sewage
Microbiological fixed-bed process was developed in which supplementary oxygen required by microbial species is supplied by electrochemical device. Rate of addition of oxygen to waste treatment process is controlled to maintain aerobic metabolism and prevent anaerobic metabolisms which produce odorous or toxic products
Local delamination in laminates with angle ply matrix cracks. Part 1: Tension tests and stress analysis
Quasi-static tension tests were conducted on AS4/3501-6 graphite epoxy laminates. Dye penetrant enhanced x-radiography was used to document the onset of matrix cracking and the onset of local delaminations at the intersection of the matrix cracks and the free edge. Edge micrographs taken after the onset of damage were used to verify the location of the matrix cracks and local delamination through the laminate thickness. A quasi-3D finite element analysis was conducted to calculate the stresses responsible for matrix cracking in the off-axis plies. Laminated plate theory indicated that the transverse normal stresses were compressive. However, the finite element analysis yielded tensile transverse normal stresses near the free edge. Matrix cracks formed in the off-axis plies near the free edge where in-plane transverse stresses were tensile and had their greatest magnitude. The influence of the matrix crack on interlaminar stresses is also discussed
Active rendezvous between a low-earth orbit user spacecraft and the Space Transportation System (STS) shuttle
Active rendezvous of an unmanned spacecraft with the Space Transportation System (STS) Shuttle is considered. The various operational constraints facing both the maneuvering spacecraft and the Shuttle during such a rendezvous sequence are discussed. Specifically, the actively rendezvousing user spacecraft must arrive in the generic Shuttle control box at a specified time after Shuttle launch. In so doing it must at no point violate Shuttle separation requirements. In addition, the spacecraft must be able to initiate the transfer sequence from any point in its orbit. The four-burn rendezvous sequence incorporating two Hohmann transfers and an intermediate phasing orbit as a low-energy solution satisfying the above requirements are discussed. The general characteristics of the four-burn sequence are discussed, with emphasis placed on phase orbit altitude and delta-velocity requirements. The planning and execution of such a sequence in the operational environment are then considered. Factor crucial in maintaining the safety of both spacecraft, such as spacecraft separation and contingency analysis, are considered in detail
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