7,962 research outputs found
Subjective Quality Assessment of the Impact of Buffer Size in Fine-Grain Parallel Video Encoding
Fine-Grain parallelism is essential for real-time video encoding performance. This usually implies setting a fixed buffer size for each encoded block. The choice of this parameter is critical for both performance and hardware cost. In this paper we analyze the impact of buffer size on image subjective quality, and its relation with other encoding parameters. We explore the consequences on visual quality, when minimizing buffer size to the point of causing the discard of quantized coefficients for highest frequencies. Finally, we propose some guidelines for the choice of buffer size, that has proven to be heavily dependent, in addition to other parameters, on the type of sequence being encoded. These guidelines are useful for the design of efficient realtime encoders, both hardware and software
Complex Scalar DM in a B-L Model
In this work, we implement a complex scalar Dark Matter (DM) candidate in a
gauge extension of the Standard Model. The model contains three
right handed neutrinos with different quantum numbers and a rich scalar sector,
with extra doublets and singlets. In principle, these extra scalars can have
VEVs ( and for the extra doublets and singlets,
respectively) belonging to different energy scales. In the context of
, which allows to obtain naturally
light active neutrino masses and mixing compatible with neutrino experiments,
the DM candidate arises by imposing a symmetry on a given complex
singlet, , in order to make it stable. After doing a study of the
scalar potential and the gauge sector, we obtain all the DM dominant processes
concerning the relic abundance and direct detection. Then, for a representative
set of parameters, we found that a complex DM with mass around GeV, for
example, is compatible with the current experimental constraints without
resorting to resonances. However, additional compatible solutions with heavier
masses can be found in vicinities of resonances. Finally, we address the issue
of having a light CP-odd scalar in the model showing that it is safe concerning
the Higgs and the boson invisible decay widths, and also the energy
loss in stars astrophysical constraints.Comment: 20 pages, 3 figure
Coordination des actions impliquees dans le reboisement forestier pour obtenir la maximum de'efficacite et d'economie d'ensembre dans les trabaux
International Union of Forest Research Organizations . World Congress 17o . 1981 . Japon)Depto. de Estadística e Investigación OperativaFac. de Ciencias MatemáticasTRUEpu
A 300 GHz "Always-in-Focus" Focusing System for Target Detection
A focusing system for a 300 GHz radar with 5 m target distance and 10 mm diameter spot size resolution is proposed. The focusing system is based on a Gaussian telescope scheme and its main parameters have been de¬signed using Gaussian beam quasi-optical propagation theory with an in-house developed MATLAB® based analysis tool. Then, this approach has been applied to a real focusing system based on two elliptical mirrors in order to reduce the distortion and cross-polar level and a plane mirror to provide scanning capabilities. The over¬all system has been simulated with a full-wave electromag¬netic simulator and its behavior is presented. With this approach, the focusing system always works "in-focus" since the only mirror that is rotated when scanning is the output plane mirror, so the beam is almost not distorted. The design process, although based in the well-known Gaussian beam quasi-optical propagation theory, provides a fast and accurate method and minimizes the overall size of the mirrors. As a consequence, the size of the focusing system is also reduced
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A study to evaluate a program for the assessment of career, personal, and study skills of North Shore Community College students.
Volatility and dividend risk in perpetual American options
American options are financial instruments that can be exercised at any time
before expiration. In this paper we study the problem of pricing this kind of
derivatives within a framework in which some of the properties --volatility and
dividend policy-- of the underlaying stock can change at a random instant of
time, but in such a way that we can forecast their final values. Under this
assumption we can model actual market conditions because some of the most
relevant facts that may potentially affect a firm will entail sharp predictable
effects. We will analyse the consequences of this potential risk on perpetual
American derivatives, a topic connected with a wide class of recurrent problems
in physics: holders of American options must look for the fair price and the
optimal exercise strategy at once, a typical question of free absorbing
boundaries. We present explicit solutions to the most common contract
specifications and derive analytical expressions concerning the mean and higher
moments of the exercise time.Comment: 21 pages, 5 figures, iopart, submitted for publication; deep
revision, two new appendice
The dependence of halo bias on age, concentration and spin
Halo bias is the main link between the matter distribution and dark matter
halos. In its simplest form, halo bias is determined by halo mass, but there
are known additional dependencies on other halo properties which are of
consequence for accurate modeling of galaxy clustering. Here we present the
most precise measurement of these secondary-bias dependencies on halo age,
concentration, and spin, for a wide range of halo masses spanning from
10 to 10 M. At the high-mass end, we find
no strong evidence of assembly bias for masses above M
M. Secondary bias exists, however, for halo concentration
and spin, up to cluster-size halos, in agreement with previous findings. For
halo spin, we report, for the first time, two different regimes: above
M10 M, halos with larger values of spin
have larger bias, at fixed mass, with the effect reaching almost a factor 2.
This trend reverses below this characteristic mass. In addition to these
results, we test, for the first time, the performance of a multi-tracer method
for the determination of the relative bias between different subsets of halos.
We show that this method increases significantly the signal-to-noise of the
secondary-bias measurement as compared to a traditional approach. This analysis
serves as the basis for follow-up applications of our multi-tracer method to
real data.Comment: 11 pages, 6 figures, submitted to MNRA
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