523 research outputs found
Trust and Reputation Modelling for Tourism Recommendations Supported by Crowdsourcing
Tourism crowdsourcing platforms have a profound influence
on the tourist behaviour particularly in terms of travel planning. Not
only they hold the opinions shared by other tourists concerning tourism
resources, but, with the help of recommendation engines, are the pillar
of personalised resource recommendation. However, since prospective
tourists are unaware of the trustworthiness or reputation of crowd publishers,
they are in fact taking a leap of faith when then rely on the
crowd wisdom. In this paper, we argue that modelling publisher Trust &
Reputation improves the quality of the tourism recommendations supported
by crowdsourced information. Therefore, we present a tourism
recommendation system which integrates: (i) user profiling using the
multi-criteria ratings; (ii) k-Nearest Neighbours (k-NN) prediction of the
user ratings; (iii) Trust & Reputation modelling; and (iv) incremental
model update, i.e., providing near real-time recommendations. In terms
of contributions, this paper provides two different Trust & Reputation
approaches: (i) general reputation employing the pairwise trust values
using all users; and (ii) neighbour-based reputation employing the pairwise
trust values of the common neighbours. The proposed method was
experimented using crowdsourced datasets from Expedia and TripAdvisor
platforms.info:eu-repo/semantics/publishedVersio
Measurement of the branching ratio of the decay
From the 2002 data taking with a neutral kaon beam extracted from the
CERN-SPS, the NA48/1 experiment observed 97 candidates with a background contamination of events.
From this sample, the BR() is measured to be
Observation of the rare decay K_S -> pi^0mu^+mu^-
A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1
Collaboration at the CERN SPS accelerator. The data were collected during 2002
with a high-intensity K_S beam. Six events were found with a background
expectation of 0.22^+0.18_-0.11 event. Using a vector matrix element and unit
form factor, the measured branching ratio is B(K_S ->
pi^0mu^+mu^-)=[2.9^+1.5_-1.2(stat)+/-0.2(syst)]x10^{-9}.Comment: 19 pages, 8 figures, 4 tables. To be published in Physics Letters
A precision measurement of direct CP violation in the decay of neutral kaons into two pions
The direct CP violation parameter Re(epsilon'/epsilon) has been measured from
the decay rates of neutral kaons into two pions using the NA48 detector at the
CERN SPS. The 2001 running period was devoted to collecting additional data
under varied conditions compared to earlier years (1997-99). The new data yield
the result: Re(epsilon'/epsilon) = (13.7 +/- 3.1) times 10^{-4}. Combining this
result with that published from the 1997, 98 and 99 data, an overall value of
Re(epsilon'/epsilon) = (14.7 +/- 2.2) times 10^{-4} is obtained from the NA48
experiment.Comment: 19 pages, 5 figures, to be published in Physics Letters
Measurement of the branching ratios of the decays Xi0 --> Sigma+ e- nubar and anti-Xi0 --> anti-Sigma+ e+ nu
From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Xi0
--> Sigma+ e- nubar candidates (with the subsequent Sigma+ --> p pi0 decay) and
555 anti-Xi0 --> anti-Sigma+ e+ nu candidates with background contamination of
215+-44 and 136+-8 events, respectively. From these samples, the branching
ratios BR(Xi0 --> Sigma+ e- nubar)= (2.51+-0.03stat+-0.09syst)E(-4) and
BR(anti-Xi0 --> anti-Sigma+ e+ nu)= (2.55+-0.14stat+-0.10syst)E(-4) were
measured allowing the determination of the CKM matrix element |Vus| =
0.209+0.023-0.028. Using the Particle Data Group average for |Vus| obtained in
semileptonic kaon decays, we measured the ratio g1/f1 = 1.20+-0.05 of the
axial-vector to vector form factors.Comment: 16 pages, 11 figures Submitted to Phys.Lett.
First Observation and Measurement of the Decay K+- -> pi+- e+ e- gamma
Using the full data set of the NA48/2 experiment, the decay K+- -> pi+- e+ e-
gamma is observed for the first time, selecting 120 candidates with 7.3 +- 1.7
estimated background events. With K+- -> pi+- pi0D as normalisation channel,
the branching ratio is determined in a model-independent way to be Br(K+- ->
pi+- e+ e- gamma, m_eegamma > 260 MeV/c^2) = (1.19 +- 0.12_stat +- 0.04_syst) x
10^-8. This measured value and the spectrum of the e+ e- gamma invariant mass
allow a comparison with predictions of Chiral Perturbation Theory.Comment: 13 pages, 3 figures. Accepted for publication in Phys.Lett.
Search for CP violation in K0 -> 3 pi0 decays
Using data taken during the year 2000 with the NA48 detector at the CERN SPS,
a search for the CP violating decay K_S -> 3 pi0 has been performed. From a fit
to the lifetime distribution of about 4.9 million reconstructed K0/K0bar -> 3
pi0 decays, the CP violating amplitude eta_000 = A(K_S -> 3 pi0)/A(K_L -> 3
pi0) has been found to be Re(eta_000) = -0.002 +- 0.011 +- 0.015 and
Im(eta_000) = -0.003 +- 0.013 +- 0.017. This corresponds to an upper limit on
the branching fraction of Br(K_S -> 3 pi0) < 7.4 x 10^-7 at 90% confidence
level. The result is used to improve knowledge of Re(epsilon) and the CPT
violating quantity Im(delta) via the Bell-Steinberger relation.Comment: 18 pages, 7 figures, submitted to Phys. Lett.
Measurement of the branching ratio of the decay KL -> pi e nu and extraction of the CKM parameter |Vus|
We present a new measurement of the branching ratio R of the decay KL -> pi e
nu (Ke3), relative to all charged KL decays with two tracks, based on data
taken with the NA48 detector at the CERN SPS. We measure R = 0.4978 +- 0.0035.
From this we derive the Ke3 branching fraction and the weak coupling
parameter |Vus| in the CKM matrix. We obtain |Vus|f+(0) = 0.2146 +- 0.0016,
where f+(0) is the vector form factor in the Ke3 decay.Comment: 18 pages, 8 figures. accepted by Phys Lett.
A new measurement of direct CP violation in two pion decays of the neutral kaon
The NA48 experiment at CERN has performed a new measurement of direct CP
violation, based on data taken in 1997 by simultaneously collecting K_L and K_S
decays into pi0pi0 and pi+pi-. The result for the CP violating parameter
Re(epsilon'/epsilon) is (18.5 +/- 4.5(stat)} +/- 5.8 (syst))x10^{-4}.Comment: 18 pages, 6 figure
Empirical parameterization of the K+- -> pi+- pi0 pi0 decay Dalitz plot
As first observed by the NA48/2 experiment at the CERN SPS, the \p0p0
invariant mass (M00) distribution from \kcnn decay shows a cusp-like anomaly
at M00=2m+, where m+ is the charged pion mass. An analysis to extract the pi pi
scattering lengths in the isospin I=0 and I=2 states, a0 and a2, respectively,
has been recently reported. In the present work the Dalitz plot of this decay
is fitted to a new empirical parameterization suitable for practical purposes,
such as Monte Carlo simulations of K+- -> pi+- pi0 pi0 decays.Comment: 9 pages, 3 figures
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