13,647 research outputs found
Novel Compact Three-Way Filtering Power Divider Using Net-Type Resonators
In this paper, we present a novel compact three-way power divider with bandpass responses. The proposed power divider utilizes folded net-type resonators to realize dual functions of filtering and power splitting as well as compact size. Equal power ratio with low magnitude imbalance is achieved due to the highly symmetric structure. For demonstration, an experimental three way filtering power divider is implemented. Good filtering and power division characteristics are observed in the measured results of the circuit. The area of the circuits is 14.5 mm x 21.9 mm or 0.16 λg x 0.24 λg, where the λg is the guide wavelength of the center frequency at 2.1 GHz
Field-aware Calibration: A Simple and Empirically Strong Method for Reliable Probabilistic Predictions
It is often observed that the probabilistic predictions given by a machine
learning model can disagree with averaged actual outcomes on specific subsets
of data, which is also known as the issue of miscalibration. It is responsible
for the unreliability of practical machine learning systems. For example, in
online advertising, an ad can receive a click-through rate prediction of 0.1
over some population of users where its actual click rate is 0.15. In such
cases, the probabilistic predictions have to be fixed before the system can be
deployed.
In this paper, we first introduce a new evaluation metric named field-level
calibration error that measures the bias in predictions over the sensitive
input field that the decision-maker concerns. We show that existing post-hoc
calibration methods have limited improvements in the new field-level metric and
other non-calibration metrics such as the AUC score. To this end, we propose
Neural Calibration, a simple yet powerful post-hoc calibration method that
learns to calibrate by making full use of the field-aware information over the
validation set. We present extensive experiments on five large-scale datasets.
The results showed that Neural Calibration significantly improves against
uncalibrated predictions in common metrics such as the negative log-likelihood,
Brier score and AUC, as well as the proposed field-level calibration error.Comment: WWW 202
An inexact linearized proximal algorithm for a class of DC composite optimization problems and applications
This paper is concerned with a class of DC composite optimization problems
which, as an extension of the convex composite optimization problem and the DC
program with nonsmooth components, often arises from robust factorization
models of low-rank matrix recovery. For this class of nonconvex and nonsmooth
problems, we propose an inexact linearized proximal algorithm (iLPA) which in
each step computes an inexact minimizer of a strongly convex majorization
constructed by the partial linearization of their objective functions. The
generated iterate sequence is shown to be convergent under the
Kurdyka-{\L}ojasiewicz (KL) property of a potential function, and the
convergence admits a local R-linear rate if the potential function has the KL
property of exponent at the limit point. For the latter assumption, we
provide a verifiable condition by leveraging the composite structure, and
clarify its relation with the regularity used for the convex composite
optimization. Finally, the proposed iLPA is applied to a robust factorization
model for matrix completions with outliers, DC programs with nonsmooth
components, and -norm exact penalty of DC constrained programs, and
numerical comparison with the existing algorithms confirms the superiority of
our iLPA in computing time and quality of solutions
Searching for lepton portal dark matter with colliders and gravitational waves
We study the lepton portal dark matter (DM) model in which the relic
abundance is determined by the portal coupling among the Majorana fermion DM
candidate , the singlet charged scalar mediator and the Standard
Model (SM) right-handed lepton. The direct and indirect searches are not
sensitive to this model. This article studies the lepton portal coupling as
well as the scalar portal coupling (between and SM Higgs boson), as the
latter is generally allowed in the Lagrangian. The inclusion of scalar portal
coupling not only significantly enhances the LHC reach via the process, but also provides a few novel signal channels, such as the
exotic decays and coupling deviations of the Higgs boson, offering new
opportunities to probe the model. In addition, we also study the Drell-Yan
production of at future lepton colliders, and find out that the
scenario where one is off-shell can be used to measure the lepton
portal coupling directly. In particular, we are interested in the possibility
that the scalar potential triggers a first-order phase transition and hence
provides the stochastic gravitational wave (GW) signals. In this case, the
terrestrial collider experiments and space-based GW detectors serve as
complementary approaches to probe the model.Comment: 23 pages+references, 15 figures. To appear on JHE
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