4,734 research outputs found
Interaction between high-level and low-level image analysis for semantic video object extraction
Authors of articles published in EURASIP Journal on Advances in Signal Processing are the copyright holders of their articles and have granted to any third party, in advance and in perpetuity, the right to use, reproduce or disseminate the article, according to the SpringerOpen copyright and license agreement (http://www.springeropen.com/authors/license)
Free Rota-Baxter algebras and rooted trees
A Rota-Baxter algebra, also known as a Baxter algebra, is an algebra with a
linear operator satisfying a relation, called the Rota-Baxter relation, that
generalizes the integration by parts formula. Most of the studies on
Rota-Baxter algebras have been for commutative algebras. Two constructions of
free commutative Rota-Baxter algebras were obtained by Rota and Cartier in the
1970s and a third one by Keigher and one of the authors in the 1990s in terms
of mixable shuffles. Recently, noncommutative Rota-Baxter algebras have
appeared both in physics in connection with the work of Connes and Kreimer on
renormalization in perturbative quantum field theory, and in mathematics
related to the work of Loday and Ronco on dendriform dialgebras and
trialgebras.
This paper uses rooted trees and forests to give explicit constructions of
free noncommutative Rota--Baxter algebras on modules and sets. This highlights
the combinatorial nature of Rota--Baxter algebras and facilitates their further
study. As an application, we obtain the unitarization of Rota-Baxter algebras.Comment: 23 page
Combinatorics of renormalization as matrix calculus
We give a simple presentation of the combinatorics of renormalization in
perturbative quantum field theory in terms of triangular matrices. The
prescription, that may be of calculational value, is derived from first
principles, to wit, the ``Birkhoff decomposition'' in the Hopf-algebraic
description of renormalization by Connes and Kreimer.Comment: 10 pages, revised version, typos corrected, to appear in Phys. Lett.
Tuning electronic properties and contact type in van der Waals heterostructures of bilayer SnS and graphene
Using first-principles calculations, we study the structural and electronic
properties of the bilayer SnS/graphene, bilayer SnS/bilayer graphene
(AA-stacked), bilayer SnS/bilayer graphene (AB-stacked) and monolayer
SnS/graphene/monolayer SnS van der Waals (vdW) heterostructures. Electronic
properties of all components of the vdW heterostructures are well preserved,
which reflects the weakness of the vdW interaction. In the cases of bilayer
SnS/graphene and bilayer SnS/bilayer graphene (AA-stacked), an Ohmic contact is
formed which can be turned first into p-type and then into n-type Schottky
contacts via application of an external electric field. Calculations show that
an Ohmic contact is also formed at the interface of bilayer SnS/bilayer
graphene (AB-stacked) heterostructure, but interestingly, by applying the
perpendicular electric field a transition from semimetal/semiconductor contact
to semiconductor/semiconductor one occurs which can enhance its optical
properties. Alternatively, in the monolayer SnS/graphene/monolayer SnS vdW
heterosructure, a p-type Schottky contact is established that changes into
Ohmic contact under an applied electric field. Our results clearly indicate
that the electronic properties of the vdW heterostructures can be tuned
efficiently by external electric field, which is important in designing of new
nanoelectronic devices.Comment: 12 pages, 11 figure
Effect of Sintering Atmosphere on Phase Evolution of Hydroxyapatite Nanocomposite Powders
In the present work, pure hydroxyapatite, hydroxyapatite-20 wt% alumina and hydroxyapatite-20 wt%
titanium mixtures were pressed and sintered in air, moist, and reduction atmospheres at 1200 C for 2 h.
XRD investigations of sintered samples showed that, pure hydroxyapatite is stable in all three
atmospheres. But, moist and reduction atmospheres were preferred to suppress the hydroxyapatite
decomposition in hydroxyapatite -alumina and hydroxyapatite – titanium nanocomposites, respectively.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3494
Lipids, Lipoproteins, and Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly. While excellent treatment has emerged for neovascular disease, treatment for early AMD is lacking due to an incomplete understanding of the early molecular events. A prominent age-related change is the accumulation of neutral lipid in normal Bruch's membrane (BrM) throughout adulthood and also disease-related BrM accumulations called basal deposits and drusen. AMD lesion formation has thus been conceptualized as sharing mechanisms with atherosclerotic plaque formation, where low-density lipoprotein (LDL) retention within the arterial wall initiates a cascade of pathologic events. However, we do not yet understand how lipoproteins contribute to AMD. This paper explores how systemic and local production of lipoproteins might contribute to the pathogenesis of AMD
MPEG-4 video verification model: A video encoding/decoding algorithm based on content representation
Cast Shadow Recognition in Color Images
Shadows are often integral parts of natural scenes and their identification is an important task in image analysis. In this paper, we propose an algorithm for recognition of shadows cast by objects on the scene's background. The proposed approach is based on the use of color information by means of photometric invariant color transformations. The method is divided into two levels: first, object and shadow edges are extracted from the RGB components and only object edges from the invariant features; then, edges are filled and the obtained masks are combined to extract shadow regions. Simulation results show that the proposed algorithm is robust and efficient in detecting shadows within a set of assumptions on the scene that makes the method's applicability wider than that of state-of-the-art methods
Error-Resilient Video Coding Performance Analysis of Motion JPEG 2000 and MPEG-4
The new Motion JPEG 2000 standard is providing with some compelling features. It is based on an intra-frame wavelet coding, which makes it very well suited for wireless applications. Indeed, the state-of-the-art wavelet coding scheme achieves very high coding efficiency. In addition, Motion JPEG 2000 is very resilient to transmission errors as frames are coded independently (intra coding). Furthermore, it requires low complexity and introduces minimal coding delay. Finally, it supports very efficient scalability. In this paper, we analyze the performance of Motion JPEG 2000 in error-prone transmission. We compare it to the well-known MPEG-4 video coding scheme, in terms of coding efficiency, error resilience and complexity. We present experimental results which show that Motion JPEG 2000 outperforms MPEG-4 in the presence of transmission errors
Visual Data Compression for Multimedia Applications
The compression of visual information in the framework of multimedia applications is discussed. To this end, major approaches to compress still as well as moving pictures are reviewed. The most important objective in any compression algorithm is that of compression efficiency. High-compression coding of still pictures can be split into three categories: waveform, second-generation, and fractal coding techniques. Each coding approach introduces a different artifact at the target bit rates. The primary objective of most ongoing research in this field is to mask these artifacts as much as possible to the human visual system. Video-compression techniques have to deal with data enriched by one more component, namely, the temporal coordinate. Either compression techniques developed for still images can be generalized for three-dimensional signals (space and time) or a hybrid approach can be defined based on motion compensation. The video compression techniques can then be classified into the following four classes: waveform, object-based, model-based, and fractal coding techniques. This paper provides the reader with a tutorial on major visual data-compression techniques and a list of references for further information as the details of each metho
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