4,426 research outputs found
Pseudogap and incommensurate magnetic fluctuations in YBa_2Cu_3O_{6. 6}
Unpolarized inelastic neutron scattering is used to study the temperature and
wave vector dependence of the dynamical magnetic susceptibility,
, of a well characterized single crystal
( K). We find that a pseudogap opens in the spin fluctuation spectrum
at temperatures well above . We speculate that the appearance of the low
frequency incommensurate fluctuations is associated with the opening of the
pseudogap. To within the error of the measurements, a gap in the spin
fluctuation spectrum is found in the superconducting state.Comment: 6 pages, 3 ps figs, Proceedings of ICNS, Physica B, to be publishe
Macro- and micro-strain in GaN nanowires on Si(111)
We analyze the strain state of GaN nanowire ensembles by x-ray diffraction.
The nanowires are grown by molecular beam epitaxy on a Si(111) substrate in a
self-organized manner. On a macroscopic scale, the nanowires are found to be
free of strain. However, coalescence of the nanowires results in micro-strain
with a magnitude from +-0.015% to +-0.03%.This micro-strain contributes to the
linewidth observed in low-temperature photoluminescence spectra
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Error resilient video transcoding for robust inter-network communications using GPRS
A novel fully comprehensive mobile video communications
system is proposed in this paper. This system exploits
the useful rate management features of the video transcoders and
combines them with error resilience for transmissions of coded
video streams over general packet radio service (GPRS) mobileaccess
networks. The error-resilient video transcoding operation
takes place at a centralized point, referred to as a video proxy,
which provides the necessary output transmission rates with the
required amount of robustness. With the use of this proposed
algorithm, error resilience can be added to an already compressed
video stream at an intermediate stage at the edge of two or more
different networks through two resilience schemes, namely the
adaptive intra refresh (AIR) and feedback control signaling (FCS)
methods. Both resilience tools impose an output rate increase
which can also be prevented with the proposed novel technique in
this paper. Thus, an error-resilient video transcoding scheme is
presented to give robust video outputs at near target transmission
rates that only require the same number of GPRS timeslots as
the nonresilient schemes. Moreover, an ultimate robustness is
also accomplished with the combination of the two resilience
algorithms at the video proxy. Extensive computer simulations
demonstrate the effectiveness of the proposed system
Preparation and characterization of photochromic effect for ceramic tiles
Ceramic tile industry is developing due to the technological researches in scientific area and new tiles which are not only a
traditional ceramic also have many multiple functionalities have been marketed nowadays. These tiles like photocatalytic,
photovoltaic, antibacterial and etc. improve the quality of life and provide lots of benefits such as self cleaning, energy
production, climate control. The goal of this study was to enhance the photochromic function on ceramic tiles which is the
attitude of changing color in a reversible way by electromagnetic radiation and widely used in many areas because of its
aesthetic and also functional properties. High response time of photochromic features of ceramic tiles have been achieved by
employing of polymeric gel with additives of photoactive dye onto the ceramic surface. Photochromic layer with a thickness
of approximately 45- 50 ÎĽm was performed by using spray coating technique which provided homogeneous deposition
on surface. Photochromic ceramic tiles with high photochromic activity such as reversibly color change between ΔE= 0.29
and 26.31 were obtained successfully. The photochromic performance properties and coloring-bleaching mechanisms were
analyzed by spectrophotometer. The microstructures of coatings were investigated both by stereo microscopy and scanning
electron microscopy (SEM).Peer reviewe
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