107,122 research outputs found
QoS impact on user perception and understanding of multimedia video clips
The widespread and increasing advent of multimedia technologies means that there must be a departure from the viewpoint that users expect a Quality of Service (QoS) which will only satisfy them perceptually. What should be expected of multimedia clips is that the QoS with which they are shown is such that it will enable the users to assimilate and understand the informational content of such clips. In this paper we present experimental results Iinking users’ understanding andperception of multimedia clips with the presentation QoS. Results show that the quality of video clips can be severely degraded without the user having to perceive any
significant loss of informational content
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Quality of perception: User quality of service in multimedia presentations
We define quality of perception (QoP) as representing the user side of the more technical and traditional quality of service. QoP encompasses not only a user’s satisfaction with the quality of multimedia presentations,
but also his/her ability to analyze, synthesise and assimilate the informational content of multimedia displays.We found that significant reductions in frame rate and color depth does not result in a significant QoP degradation
Utilization of VAS satellite data in the initialization of an oceanic-cyclogenesis simulation
A series of experiments was performed to test various method of incorporating Visible Infrared Spin Scan Radiometer Atmospheric Sounder (VAS)-sounding data into the initial conditions of the Penn State University/National Center for Atmospheric mesoscale model. The VAS data for this ocean-cyclogenesis case consist of 110 irregularly distributed temperature and humidity soundings located over the North Pacific Ocean and apply at approximately 1200 GMT 10 November 1981. Various methods of utilizing VAS data in the initial condition of a mesoscale model were evaluated
Scale hierarchy in Horava-Lifshitz gravity: a strong constraint from synchrotron radiation in the Crab nebula
Horava-Lifshitz gravity models contain higher order operators suppressed by a
characteristic scale, which is required to be parametrically smaller than the
Planck scale. We show that recomputed synchrotron radiation constraints from
the Crab nebula suffice to exclude the possibility that this scale is of the
same order of magnitude as the Lorentz breaking scale in the matter sector.
This highlights the need for a mechanism that suppresses the percolation of
Lorentz violation in the matter sector and is effective for higher order
operators as well.Comment: 4 page, 2 figures; v2: minor changes to match published versio
Assessment of the environmental toxicity and carcinogenicity of tungsten-based shot.
The toxicity of elemental tungsten released from discharged shot was assessed against previous studies that established a 1% toxic threshold for soil organisms. Extremely heavy theoretical shot loadings of 69,000 shot/ha were used to generate estimated environmental concentrations (EEC) for two brands of tungsten-based shot containing 51% and 95% tungsten. The corresponding tungsten EEC values were 6.5–13.5 mg W/kg soil, far below the 1% toxic threshold. The same shot loading in water produced tungsten EEC values of 2.1–4.4 mg W/L, levels that are not toxic under experimental conditions. Pure tungsten has not been shown to exhibit carcinogenic properties when ingested or embedded in animal tissues, but nickel, with which it is often alloyed, has known carcinogenicity. Given the large number of waterfowl that carry shot embedded in their body, it is advisable to screen lead shot substitutes for their carcinogenic potential through intra-muscular implantation
The unbiased frequency of planetary signatures around single and binary white dwarfs using and
This paper presents combined IRAC and COS
results for a double-blind survey of 195 single and 22 wide binary white dwarfs
for infrared excesses and atmospheric metals. The selection criteria include
cooling ages in the range 9 to 300 Myr, and hydrogen-rich atmospheres so that
the presence of atmospheric metals can be confidently linked to ongoing
accretion from a circumstellar disc. The entire sample has infrared photometry,
whereas 168 targets have corresponding ultraviolet spectra. Three stars with
infrared excesses due to debris discs are recovered, yielding a nominal
frequency of per cent, while in stark contrast, the
fraction of stars with atmospheric metals is per cent. Thus, only one
out of 30 polluted white dwarfs exhibits an infrared excess at 3-4 m in
IRAC photometry, which reinforces the fact that atmospheric metal pollution is
the most sensitive tracer of white dwarf planetary systems. The corresponding
fraction of infrared excesses around white dwarfs with wide binary companions
is consistent with zero, using both the infrared survey data and an independent
assessment of potential binarity for well-established dusty and polluted stars.
In contrast, the frequency of atmospheric pollution among the targets in wide
binaries is indistinct from apparently single stars, and moreover the
multiplicity of polluted white dwarfs in a complete and volume-limited sample
is the same as for field stars. Therefore, it appears that the delivery of
planetesimal material onto white dwarfs is ultimately not driven by stellar
companions, but by the dynamics of planetary bodies.Comment: 15 pages, 6 figures, 3 tables; accepted for publication in MNRA
Adjunct hexagonal array token Petri nets and hexagonal picture languages
Adjunct Hexagonal Array Token Petri Net Structures (AHPN) are re-
cently introduced hexagonal picture generating devices which extended the Hexag- onal Array Token Petri Net Structures . In this paper we consider AHPN model along with a control feature called inhibitor arcs and compare it with some ex- pressive hexagonal picture generating and recognizing models with respect to the
generating power
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