520 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
Deformation resistance and structure-forming processes of iron aluminides in hot rolling
We have developed simple mathematical models of mean equivalent stress dependence on temperature and strain for selected iron aluminides. Four similar melts with 16.5-19.2 wt.% of Al, 4 wt.% of Cr and with various contents of Ti and B were studied and compared. Flat specimens graded by thickness were hot rolled. Deformation resistance was calculated from the roll force values obtained using a laboratory mill Tandem. Postdynamic structure-forming processes of the tested aluminides, as well as their cracking susceptibility, were investigated by metallography. The differences in the deformation behavior and formability of the tested aluminides were described.Разработаны простые математические модели зависимости среднего эквивалентного напряжения от температуры и деформации для выбранных алюминидов железа. Были изучены и сравнены четыре одинаковые плавки, содержащие 16,5...19,2 вес.% Al, и 4 вес.% Сг и различное количество титана и бора. Плоские образцы, рассортированные по толщине, подвергались горячей прокатке. Сопротивление деформированию рассчитывали по величине усилия на валки, определенной с использованием лабораторного прокатного стана Тандем. Процессы структурообразования испытанных алюминидов после динамического воздействия и их склонность к трещинообразованию исследовали с использованием металлографии. Описаны наблюдавшиеся различия в поведении испытанных алюминидов при деформировании и в способности к формоизменению
Compressive creep of Fe3Al-type iron aluminide with Zr additions
High-temperature creep ofa Fe3Al-type iron aluminide alloyed by zirconium was studied in the temperature range 873-1073 K. The alloy contained (wt.%) 31.5% Al, 3.5% Cr, 0.25% Zr, 0.19% C (Fe balance). It was tested in two states: (i) as received after hot rolling and (ii) heat treated (1423 K/ 2 h/air). Creep tests were performed in compression at constant load with stepwise loading: in each step, the load was changed to a new value after steady state creep rate had been established. Stress exponent and activation energy of the creep rate were determined and possible creep mechanisms were discussed in terms ofthe threshold stress concept. A rapidfall ofthe stress exponent and ofthe threshold stress with the increasing temperature indicates that creep is impeded by the presence of precipitates only at temperature 873 K. The results were compared with the results oflong-term creep tests in tension performed recently on the same alloy.
Изучена высокотемпературная ползучестьИзучена высокотемпературная ползучесть алюминида железа типа Fe3Al, легированного цирконием в диапазоне температур 873...1073 К. Сплав содержал (ат.%) 31,5 Al, 3,5 Сг, 0,25 Zг, 0,19 С (остальное Fе). Испытания проводили в двух состояниях: в состоянии поставки после горячей прокатки и после термообработки (1423 К/2 ч/воздух). Испытания на ползучесть выполняли при постоянной сжимающей нагрузке при ступенчатом нагружении: на каждой ступени использовали нагрузку другой величины после того, как наступала стадия установившейся скорости ползучести. Определена экспонента напряжения и энергия активации для скорости ползучести, обсуждены возможные механизмы ползучести с позиций концепции порогового напряжения. Резкое уменьшение экспоненты напряжения и порогового напряжения при увеличении температуры свидетельствует о том, что наличие вторичных фаз снижает скорость ползучести только при температуре 873 К. Полученные результаты сравнивали с данными длительных испытаний на ползучесть при растяжении, выполненных на том же сплаве
Probing Cosmology with Weak Lensing Minkowski Functionals
In this paper, we show that Minkowski Functionals (MFs) of weak gravitational
lensing (WL) convergence maps contain significant non-Gaussian,
cosmology-dependent information. To do this, we use a large suite of
cosmological ray-tracing N-body simulations to create mock WL convergence maps,
and study the cosmological information content of MFs derived from these maps.
Our suite consists of 80 independent 512^3 N-body runs, covering seven
different cosmologies, varying three cosmological parameters Omega_m, w, and
sigma_8 one at a time, around a fiducial LambdaCDM model. In each cosmology, we
use ray-tracing to create a thousand pseudo-independent 12 deg^2 convergence
maps, and use these in a Monte Carlo procedure to estimate the joint confidence
contours on the above three parameters. We include redshift tomography at three
different source redshifts z_s=1, 1.5, 2, explore five different smoothing
scales theta_G=1, 2, 3, 5, 10 arcmin, and explicitly compare and combine the
MFs with the WL power spectrum. We find that the MFs capture a substantial
amount of information from non-Gaussian features of convergence maps, i.e.
beyond the power spectrum. The MFs are particularly well suited to break
degeneracies and to constrain the dark energy equation of state parameter w (by
a factor of ~ three better than from the power spectrum alone). The
non-Gaussian information derives partly from the one-point function of the
convergence (through V_0, the "area" MF), and partly through non-linear spatial
information (through combining different smoothing scales for V_0, and through
V_1 and V_2, the boundary length and genus MFs, respectively). In contrast to
the power spectrum, the best constraints from the MFs are obtained only when
multiple smoothing scales are combined.Comment: 19 pages, 9 figures, 5 table
Definitions of terms relating to individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers (IUPAC Recommendations 2014)
This document defines terms relating to the properties of individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers. In the section on polymer solutions and amorphous bulk polymers, general and thermodynamic terms, dilute solutions, phase behaviour, transport properties, scattering methods, and separation methods are considered. The recommendations are a revision and expansion of the IUPAC terminology published in 1989 dealing with individual macromolecules, macromolecular assemblies, and dilute polymer solutions. New terms covering the principal theoretical and experimental developments that have occurred over the intervening years have been introduced. Polyelectrolytes are not included.△1143Ysciescopu
Black hole production in tachyonic preheating
We present fully non-linear simulations of a self-interacting scalar field in
the early universe undergoing tachyonic preheating. We find that density
perturbations on sub-horizon scales which are amplified by tachyonic
instability maintain long range correlations even during the succeeding
parametric resonance, in contrast to the standard models of preheating
dominated by parametric resonance. As a result the final spectrum exhibits
memory and is not universal in shape. We find that throughout the subsequent
era of parametric resonance the equation of state of the universe is almost
dust-like, hence the Jeans wavelength is much smaller than the horizon scale.
If our 2D simulations are accurate reflections of the situation in 3D, then
there are wide regions of parameter space ruled out by over-production of black
holes. It is likely however that realistic parameter values, consistent with
COBE/WMAP normalisation, are safetly outside this black hole over-production
region.Comment: 6pages, 7figures, figures correcte
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