8,018 research outputs found
Sobolev, Besov and Triebel-Lizorkin spaces on quantum tori
This paper gives a systematic study of Sobolev, Besov and Triebel-Lizorkin
spaces on a noncommutative -torus (with a
skew symmetric real -matrix). These spaces share many properties
with their classical counterparts. We prove, among other basic properties, the
lifting theorem for all these spaces and a Poincar\'e type inequality for
Sobolev spaces. We also show that the Sobolev space
coincides with the Lipschitz space of order
, already studied by Weaver in the case . We establish the embedding
inequalities of all these spaces, including the Besov and Sobolev embedding
theorems. We obtain Littlewood-Paley type characterizations for Besov and
Triebel-Lizorkin spaces in a general way, as well as the concrete ones in terms
of the Poisson, heat semigroups and differences. Some of them are new even in
the commutative case, for instance, our Poisson semigroup characterizations
improve the classical ones. As a consequence of the characterization of the
Besov spaces by differences, we extend to the quantum setting the recent
results of Bourgain-Br\'ezis -Mironescu and Maz'ya-Shaposhnikova on the limits
of Besov norms. The same characterization implies that the Besov space
for is the quantum
analogue of the usual Zygmund class of order . We investigate the
interpolation of all these spaces, in particular, determine explicitly the
K-functional of the couple , which is the quantum analogue of a classical
result due to Johnen and Scherer. Finally, we show that the completely bounded
Fourier multipliers on all these spaces do not depend on the matrix ,
so coincide with those on the corresponding spaces on the usual -torus
Radar-on-Lidar: metric radar localization on prior lidar maps
Radar and lidar, provided by two different range sensors, each has pros and
cons of various perception tasks on mobile robots or autonomous driving. In
this paper, a Monte Carlo system is used to localize the robot with a rotating
radar sensor on 2D lidar maps. We first train a conditional generative
adversarial network to transfer raw radar data to lidar data, and achieve
reliable radar points from generator. Then an efficient radar odometry is
included in the Monte Carlo system. Combining the initial guess from odometry,
a measurement model is proposed to match the radar data and prior lidar maps
for final 2D positioning. We demonstrate the effectiveness of the proposed
localization framework on the public multi-session dataset. The experimental
results show that our system can achieve high accuracy for long-term
localization in outdoor scenes
Sparse Recovery via Differential Inclusions
In this paper, we recover sparse signals from their noisy linear measurements
by solving nonlinear differential inclusions, which is based on the notion of
inverse scale space (ISS) developed in applied mathematics. Our goal here is to
bring this idea to address a challenging problem in statistics, \emph{i.e.}
finding the oracle estimator which is unbiased and sign-consistent using
dynamics. We call our dynamics \emph{Bregman ISS} and \emph{Linearized Bregman
ISS}. A well-known shortcoming of LASSO and any convex regularization
approaches lies in the bias of estimators. However, we show that under proper
conditions, there exists a bias-free and sign-consistent point on the solution
paths of such dynamics, which corresponds to a signal that is the unbiased
estimate of the true signal and whose entries have the same signs as those of
the true signs, \emph{i.e.} the oracle estimator. Therefore, their solution
paths are regularization paths better than the LASSO regularization path, since
the points on the latter path are biased when sign-consistency is reached. We
also show how to efficiently compute their solution paths in both continuous
and discretized settings: the full solution paths can be exactly computed piece
by piece, and a discretization leads to \emph{Linearized Bregman iteration},
which is a simple iterative thresholding rule and easy to parallelize.
Theoretical guarantees such as sign-consistency and minimax optimal -error
bounds are established in both continuous and discrete settings for specific
points on the paths. Early-stopping rules for identifying these points are
given. The key treatment relies on the development of differential inequalities
for differential inclusions and their discretizations, which extends the
previous results and leads to exponentially fast recovering of sparse signals
before selecting wrong ones.Comment: In Applied and Computational Harmonic Analysis, 201
LocNet: Global localization in 3D point clouds for mobile vehicles
Global localization in 3D point clouds is a challenging problem of estimating
the pose of vehicles without any prior knowledge. In this paper, a solution to
this problem is presented by achieving place recognition and metric pose
estimation in the global prior map. Specifically, we present a semi-handcrafted
representation learning method for LiDAR point clouds using siamese LocNets,
which states the place recognition problem to a similarity modeling problem.
With the final learned representations by LocNet, a global localization
framework with range-only observations is proposed. To demonstrate the
performance and effectiveness of our global localization system, KITTI dataset
is employed for comparison with other algorithms, and also on our long-time
multi-session datasets for evaluation. The result shows that our system can
achieve high accuracy.Comment: 6 pages, IV 2018 accepte
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