11,664 research outputs found
The integrated periodogram of a dependent extremal event sequence
We investigate the asymptotic properties of the integrated periodogram
calculated from a sequence of indicator functions of dependent extremal events.
An event in Euclidean space is extreme if it occurs far away from the origin.
We use a regular variation condition on the underlying stationary sequence to
make these notions precise. Our main result is a functional central limit
theorem for the integrated periodogram of the indicator functions of dependent
extremal events. The limiting process is a continuous Gaussian process whose
covari- ance structure is in general unfamiliar, but in the iid case a Brownian
bridge appears. In the general case, we propose a stationary bootstrap
procedure for approximating the distribution of the limiting process. The
developed theory can be used to construct classical goodness-of-fit tests such
as the Grenander- Rosenblatt and Cram\'{e}r-von Mises tests which are based
only on the extremes in the sample. We apply the test statistics to simulated
and real-life data
Wavelet Galerkin method for fractional elliptic differential equations
Under the guidance of the general theory developed for classical partial
differential equations (PDEs), we investigate the Riesz bases of wavelets in
the spaces where fractional PDEs usually work, and their applications in
numerically solving fractional elliptic differential equations (FEDEs). The
technique issues are solved and the detailed algorithm descriptions are
provided. Compared with the ordinary Galerkin methods, the wavelet Galerkin
method we propose for FEDEs has the striking benefit of efficiency, since the
condition numbers of the corresponding stiffness matrixes are small and
uniformly bounded; and the Toeplitz structure of the matrix still can be used
to reduce cost. Numerical results and comparison with the ordinary Galerkin
methods are presented to demonstrate the advantages of the wavelet Galerkin
method we provide.Comment: 20 pages, 0 figure
Forward Vehicle Collision Warning Based on Quick Camera Calibration
Forward Vehicle Collision Warning (FCW) is one of the most important
functions for autonomous vehicles. In this procedure, vehicle detection and
distance measurement are core components, requiring accurate localization and
estimation. In this paper, we propose a simple but efficient forward vehicle
collision warning framework by aggregating monocular distance measurement and
precise vehicle detection. In order to obtain forward vehicle distance, a quick
camera calibration method which only needs three physical points to calibrate
related camera parameters is utilized. As for the forward vehicle detection, a
multi-scale detection algorithm that regards the result of calibration as
distance priori is proposed to improve the precision. Intensive experiments are
conducted in our established real scene dataset and the results have
demonstrated the effectiveness of the proposed framework
A Framework on Moment Model Reduction for Kinetic Equation
By a further investigation on the structure of the coefficient matrix of the
globally hyperbolic regularized moment equations for Boltzmann equation in [Z.
Cai, Y. Fan and R. Li, Comm. Math. Sci., 11 (2013), pp. 547-571], we propose a
uniform framework to carry out model reduction to general kinetic equations, to
achieve certain moment system. With this framework, the underlying reason why
the globally hyperbolic regularization in [Z. Cai, Y. Fan and R. Li, Comm.
Math. Sci., 11 (2013), pp. 547-571] works is revealed. The even fascinating
point is, with only routine calculation, existing models are represented and
brand new models are discovered. Even if the study is restricted in the scope
of the classical Grad's 13-moment system, new model with global hyperbolicity
can be deduced.Comment: 22 page
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