5,414 research outputs found
Entity Linking for Queries by Searching Wikipedia Sentences
We present a simple yet effective approach for linking entities in queries.
The key idea is to search sentences similar to a query from Wikipedia articles
and directly use the human-annotated entities in the similar sentences as
candidate entities for the query. Then, we employ a rich set of features, such
as link-probability, context-matching, word embeddings, and relatedness among
candidate entities as well as their related entities, to rank the candidates
under a regression based framework. The advantages of our approach lie in two
aspects, which contribute to the ranking process and final linking result.
First, it can greatly reduce the number of candidate entities by filtering out
irrelevant entities with the words in the query. Second, we can obtain the
query sensitive prior probability in addition to the static link-probability
derived from all Wikipedia articles. We conduct experiments on two benchmark
datasets on entity linking for queries, namely the ERD14 dataset and the GERDAQ
dataset. Experimental results show that our method outperforms state-of-the-art
systems and yields 75.0% in F1 on the ERD14 dataset and 56.9% on the GERDAQ
dataset
Detecting Byzantine Attacks Without Clean Reference
We consider an amplify-and-forward relay network composed of a source, two
relays, and a destination. In this network, the two relays are untrusted in the
sense that they may perform Byzantine attacks by forwarding altered symbols to
the destination. Note that every symbol received by the destination may be
altered, and hence no clean reference observation is available to the
destination. For this network, we identify a large family of Byzantine attacks
that can be detected in the physical layer. We further investigate how the
channel conditions impact the detection against this family of attacks. In
particular, we prove that all Byzantine attacks in this family can be detected
with asymptotically small miss detection and false alarm probabilities by using
a sufficiently large number of channel observations \emph{if and only if} the
network satisfies a non-manipulability condition. No pre-shared secret or
secret transmission is needed for the detection of these attacks, demonstrating
the value of this physical-layer security technique for counteracting Byzantine
attacks.Comment: 16 pages, 7 figures, accepted to appear on IEEE Transactions on
Information Forensics and Security, July 201
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
Evaporation-triggered segregation of sessile binary droplets
Droplet evaporation of multicomponent droplets is essential for various
physiochemical applications, e.g. in inkjet printing, spray cooling and
microfabrication. In this work, we observe and study phase segregation of an
evaporating sessile binary droplet, consisting of a mixture of water and a
surfactant-like liquid (1,2-hexanediol). The phase segregation (i.e., demixing)
leads to a reduced water evaporation rate of the droplet and eventually the
evaporation process ceases due to shielding of the water by the non-volatile
1,2-hexanediol. Visualizations of the flow field by particle image velocimetry
and numerical simulations reveal that the timescale of water evaporation at the
droplet rim is faster than that of the Marangoni flow, which originates from
the surface tension difference between water and 1,2-hexanediol, eventually
leading to segregation
Evaporating pure, binary and ternary droplets: thermal effects and axial symmetry breaking
The Greek aperitif Ouzo is not only famous for its specific anise-flavored
taste, but also for its ability to turn from a transparent miscible liquid to a
milky-white colored emulsion when water is added. Recently, it has been shown
that this so-called Ouzo effect, i.e. the spontaneous emulsification of oil
microdroplets, can also be triggered by the preferential evaporation of ethanol
in an evaporating sessile Ouzo drop, leading to an amazingly rich drying
process with multiple phase transitions [H. Tan et al., Proc. Natl. Acad. Sci.
USA 113(31) (2016) 8642]. Due to the enhanced evaporation near the contact
line, the nucleation of oil droplets starts at the rim which results in an oil
ring encircling the drop. Furthermore, the oil droplets are advected through
the Ouzo drop by a fast solutal Marangoni flow. In this article, we investigate
the evaporation of mixture droplets in more detail, by successively increasing
the mixture complexity from pure water over a binary water-ethanol mixture to
the ternary Ouzo mixture (water, ethanol and anise oil). In particular,
axisymmetric and full three-dimensional finite element method simulations have
been performed on these droplets to discuss thermal effects and the complicated
flow in the droplet driven by an interplay of preferential evaporation,
evaporative cooling and solutal and thermal Marangoni flow. By using image
analysis techniques and micro-PIV measurements, we are able to compare the
numerically predicted volume evolutions and velocity fields with experimental
data. The Ouzo droplet is furthermore investigated by confocal microscopy. It
is shown that the oil ring predominantly emerges due to coalescence
A Numerical Investigation of the Sparkjet Actuator in Multiple-shot Mode
AbstractComputational simulations were performed in multiple-shot mode to investigate the effects of the boundary conditions and the deposition energy on the performance of the Sparkjet actuator. The user define function (UDF) was applied in the source term of the energy equation to imitate the very arc current discharges which produce the synthetic flow. The method of numerical simulation is verified by the existing experimental and analytical data. Two parameters including the integration mass and momentum are defined to evaluate the performance of the Sparkjet actuator. The simulation results show that Sparkjet flow is more affected by the boundary conditions of the external walls of the cavity and its deposition energy. The performance of Sparkjet actuator drops with the increase of operation cycle when the wall of cavity is adiabatic. When the temperature of wall of cavity is constant, the integration mass and momentum during the exhaling stage decrease with the increase of temperature. The performance of actuator decreases with the increase of heat transfer coefficient when the wall of cavity is set to be coupled with effect of radiation and convection. The performance of actuator increases with increase of deposition energy
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