نتایج جستجو برای: localization operator

تعداد نتایج: 231995  

2005
Elena Cordero Karlheinz Gröchenig

We provide examples of the product of two localization operators. As a special case, we study the composition of Gabor multipliers. The results highlight the instability of this product and underline the necessity of expressing it in terms of asymptotic expansions. We study the problem of calculating or estimating the product of two localization operators. The motivation comes either from signa...

Journal: :journal of medical signals and sensors 0
vahid mohammadi saffarzadeh alireza osareh bita shadgar

detecting blood vessels is an important task in retinal image analysis.  the task is more challenging with the presence of bright and dark lesions in retinal images. here, a method is proposed to detect vessels in both normal and abnormal retinal fundus images based on their linear features. first, the negative impact of bright lesions is reduced by using k-means segmentation in a perceptive sp...

Journal: :Journal of Functional Analysis 2022

We study a version of the fractal uncertainty principle in joint time-frequency representation. Namely, we consider Daubechies' localization operator projecting onto spherically symmetric n-iterate Cantor sets with an arbitrary base M>1 and alphabet A. derive upper bound asymptote up to multiplicative constant for norm terms M size |A| set. For any fixed size, show that there are such is optima...

2001
Simone Fiori Pietro Burrascano

The aim of this paper is to present an electromagnetic source localization technique based on independentcomponent analysis (ICA). Two ICA algorithms known from the literature, allowing to process complex-valued signals, are used to estimate the mixing operator from electromagnetic data; as the mixing operator contains important information about the source complex structure and about the elect...

2016
Tian Chen Xiangdong Zhang

We study the localization of probability distribution in a discrete quantum random walk on an infinite chain. With a phase defect introduced in any position of the quantum random walk (QRW), we have found that the localization of the probability distribution in the QRW emerges. Different localized behaviors of the probability distribution in the QRW are presented when the defect occupies differ...

Journal: :Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine 2009
Pierre Mozer Michael Baumann Grégoire Chevreau Alexandre Moreau-Gaudry Stéphane Bart Raphaële Renard-Penna Eva Comperat Pierre Conort Marc-Olivier Bitker Emmanuel Chartier-Kastler Francois Richard Jocelyne Troccaz

OBJECTIVE Mapping of transrectal ultrasonographic (TRUS) prostate biopsies is of fundamental importance for either diagnostic purposes or the management and treatment of prostate cancer, but the localization of the cores seems inaccurate. Our objective was to evaluate the capacities of an operator to plan transrectal prostate biopsies under 2-dimensional TRUS guidance using a registration algor...

1996
Alexander Figotin

We consider classical acoustic waves in a medium described by a position dependent mass density %(x). We assume that %(x) is a random perturbation of a periodic function % 0 (x) and that the periodic acoustic operator A 0 = ?r 1 % 0 (x) r has a gap in the spectrum. We prove the existence of localized waves, i.e., nite energy solutions of the acoustic equations with the property that almost all ...

2005
CHRISTOPH THIELE

We prove L estimates (Theorem 1.3) for the Bi-Carleson operator defined below. The methods used are essentially based on the treatment of the Walsh analogue of the operator in the prequel [11] of this paper, but with additional technicalities due to the fact that in the Fourier model one cannot obtain perfect localization in both space and frequency.

2014
Dénes Ákos Nagy Tamás Haidegger Ziv Yaniv

Fiducial localization in volumetric images is a common task performed by image-guided navigation and augmented reality systems. These systems often rely on fiducials for image-space to physical-space registration, or as easily identifiable structures for registration validation purposes. Automated methods for fiducial localization in volumetric images are available. Unfortunately, these methods...

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