54,289 research outputs found
Quickest Sequence Phase Detection
A phase detection sequence is a length- cyclic sequence, such that the
location of any length- contiguous subsequence can be determined from a
noisy observation of that subsequence. In this paper, we derive bounds on the
minimal possible in the limit of , and describe some sequence
constructions. We further consider multiple phase detection sequences, where
the location of any length- contiguous subsequence of each sequence can be
determined simultaneously from a noisy mixture of those subsequences. We study
the optimal trade-offs between the lengths of the sequences, and describe some
sequence constructions. We compare these phase detection problems to their
natural channel coding counterparts, and show a strict separation between the
fundamental limits in the multiple sequence case. Both adversarial and
probabilistic noise models are addressed.Comment: To appear in the IEEE Transactions on Information Theor
Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop
Evaporating liquid droplets are omnipresent in nature and technology, such as
in inkjet printing, coating, deposition of materials, medical diagnostics,
agriculture, food industry, cosmetics, or spills of liquids. While the
evaporation of pure liquids, liquids with dispersed particles, or even liquid
mixtures has intensively been studied over the last two decades, the
evaporation of ternary mixtures of liquids with different volatilities and
mutual solubilities has not yet been explored. Here we show that the
evaporation of such ternary mixtures can trigger a phase transition and the
nucleation of microdroplets of one of the components of the mixture. As model
system we pick a sessile Ouzo droplet (as known from daily life - a transparent
mixture of water, ethanol, and anise oil) and reveal and theoretically explain
its four life phases: In phase I, the spherical cap-shaped droplet remains
transparent, while the more volatile ethanol is evaporating, preferentially at
the rim of the drop due to the singularity there. This leads to a local ethanol
concentration reduction and correspondingly to oil droplet nucleation there.
This is the beginning of phase II, in which oil microdroplets quickly nucleate
in the whole drop, leading to its milky color which typifies the so-called
'Ouzo-effect'. Once all ethanol has evaporated, the drop, which now has a
characteristic non-spherical-cap shape, has become clear again, with a water
drop sitting on an oil-ring (phase III), finalizing the phase inversion.
Finally, in phase IV, also all water has evaporated, leaving behind a tiny
spherical cap-shaped oil drop.Comment: 40 pages, 12 figure
Single integrated device for optical CDMA code processing in dual-code environment
We report on the design, fabrication and performance of a matching integrated optical CDMA encoder-decoder pair based on holographic Bragg reflector technology. Simultaneous encoding/decoding operation of two multiple wavelength-hopping time-spreading codes was successfully demonstrated and shown to support two error-free OCDMA links at OC-24. A double-pass scheme was employed in the devices to enable the use of longer code length
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