oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

3 ( 1 )

2018 ( 1 )

2016 ( 3 )

2015 ( 7 )

Custom range...

Search Results: 1 - 10 of 674 matches for " Delia Mitrea "
All listed articles are free for downloading (OA Articles)
Page 1 /674
Display every page Item
Iterative Methods for Obtaining Energy-Minimizing Parametric Snakes with Applications to Medical Imaging
Alexandru Ioan Mitrea,Radu Badea,Delia Mitrea,Sergiu Nedevschi,Paulina Mitrea,Dumitru Mircea Ivan,Octavian Mircia Gurz u
Computational and Mathematical Methods in Medicine , 2012, DOI: 10.1155/2012/918510
Abstract: After a brief survey on the parametric deformable models, we develop an iterative method based on the finite difference schemes in order to obtain energy-minimizing snakes. We estimate the approximation error, the residue, and the truncature error related to the corresponding algorithm, then we discuss its convergence, consistency, and stability. Some aspects regarding the prosthetic sugical methods that implement the above numerical methods are also pointed out.
Abdominal Tumor Characterization and Recognition Using Superior-Order Cooccurrence Matrices, Based on Ultrasound Images
Delia Mitrea,Paulina Mitrea,Sergiu Nedevschi,Radu Badea,Monica Lupsor,Mihai Socaciu,Adela Golea,Claudia Hagiu,Lidia Ciobanu
Computational and Mathematical Methods in Medicine , 2012, DOI: 10.1155/2012/348135
Abstract: The noninvasive diagnosis of the malignant tumors is an important issue in research nowadays. Our purpose is to elaborate computerized, texture-based methods for performing computer-aided characterization and automatic diagnosis of these tumors, using only the information from ultrasound images. In this paper, we considered some of the most frequent abdominal malignant tumors: the hepatocellular carcinoma and the colonic tumors. We compared these structures with the benign tumors and with other visually similar diseases. Besides the textural features that proved in our previous research to be useful in the characterization and recognition of the malignant tumors, we improved our method by using the grey level cooccurrence matrix and the edge orientation cooccurrence matrix of superior order. As resulted from our experiments, the new textural features increased the malignant tumor classification performance, also revealing visual and physical properties of these structures that emphasized the complex, chaotic structure of the corresponding tissue.
COALA DE VAR N ECONOMIE SOCIAL
Geta Mitrea
Revista de Economie Sociala , 2013,
Abstract:
THE SUMMER SCHOOL IN SOCIAL ECONOMY
Geta Mitrea
Revista de Economie Sociala , 2013,
Abstract:
The Six-Point Circle Theorem
Adrian Mitrea
Mathematics , 2010,
Abstract: Given $\Delta ABC$ and angles $\alpha,\beta,\gamma\in(0,\pi)$ with $\alpha+\beta+\gamma=\pi$, we study the properties of the triangle $DEF$ which satisfies: (i) $D\in BC$, $E\in AC$, $F\in AB$, (ii) $\aangle D=\alpha$, $\aangle E=\beta$, $\aangle F=\gamma$, (iii) $\Delta DEF$ has the minimal area in the class of triangles satisfying (i) and (ii). In particular, we show that minimizer $\Delta DEF$, exists, is unique and is a pedal triangle, corresponding to a certain pedal point $P$. Permuting the roles played by the angles $\alpha,\beta,\gamma$ in (ii), yields a total of six such area-minimizing triangles, which are pedal relative to six pedal points, say, $P_1,....,P_6$. The main result of the paper is the fact that there exists a circle which contains all six points.
On the Area of Pedal and Antipedal Triangles
Adrian Mitrea
Mathematics , 2010,
Abstract: We give a new proof of the formula expressing the area of the triangle whose vertices are the projections of an arbitrary point in the plane onto the sides of a given triangle, in terms of the geometry of the given triangle and the location of the projection point. Other related geometrical constructions and formulas are also presented.
Extending Sobolev Functions with Partially Vanishing Traces from Locally (epsilon,delta)-Domains and Applications to Mixed Boundary Problems
Kevin Brewster,Dorina Mitrea,Irina Mitrea,Marius Mitrea
Mathematics , 2012,
Abstract: We prove that given any positive integer $k$, for each open set $\Omega$ and any closed subset $D$ of its closure such that $\Omega$ is locally an (epsilon,delta)-domain near points in the boundary of $\Omega$ not contained in $D$ there exists a linear and bounded extension operator $E$ mapping, for each $p\in[1,\infty]$, the space $W^{k,p}_D(\Omega)$ into $W^{k,p}_D({\mathbb{R}}^n)$. Here, with $O$ denoting either $\Omega$ or the entire ambient, the space $W^{k,p}_D(O)$ is defined as the completion in the classical Sobolev space $W^{k,p}(O)$ of compactly supported smooth functions whose supports are disjoint from $D$. In turn, this result is used to develop a functional analytic theory for the class $W^{k,p}_D(\Omega)$ (including intrinsic characterizations, boundary traces and extensions results, interpolation theorems, among other things) which is then employed in the treatment of mixed boundary value problems formulated in locally (epsilon,delta)-domains.
On the $L^p$-Poisson semigroup associated with elliptic systems
José María Martell,Dorina Mitrea,Irina Mitrea,Marius Mitrea
Mathematics , 2014,
Abstract: We study the infinitesimal generator of the Poisson semigroup in $L^p$ associated with homogeneous, second-order, strongly elliptic systems with constant complex coefficients in the upper-half space, which is proved to be the Dirichlet-to-Normal mapping in this setting. Also, its domain is identified as the linear subspace of the $L^p$-based Sobolev space of order one on the boundary of the upper-half space consisting of functions for which the Regularity problem is solvable. Moreover, for a class of systems containing the Lam\'e system, as well as all second-order, scalar elliptic operators, with constant complex coefficients, the action of the infinitesimal generator is explicitly described in terms of singular integral operators whose kernels involve first-order derivatives of the canonical fundamental solution of the given system. Furthermore, arbitrary powers of the infinitesimal generator of the said Poisson semigroup are also described in terms of higher order Sobolev spaces and a higher order Regularity problem for the system in question. Finally, we indicate how our techniques may adapted to treat the case of higher order systems in graph Lipschitz domains.
The higher order regularity Dirichlet problem for elliptic systems in the upper-half space
José María Martell,Dorina Mitrea,Irina Mitrea,Marius Mitrea
Mathematics , 2014, DOI: 10.1090/conm/612/12228
Abstract: We identify a large class of constant (complex) coefficient, second order elliptic systems for which the Dirichlet problem in the upper-half space with data in $L^p$-based Sobolev spaces, $1
The Dirichlet problem for elliptic systems with data in K?the function spaces
José María Martell,Dorina Mitrea,Irina Mitrea,Marius Mitrea
Mathematics , 2014,
Abstract: We show that the boundedness of the Hardy-Littlewood maximal operator on a K\"othe function space ${\mathbb{X}}$ and on its K\"othe dual ${\mathbb{X}}'$ is equivalent to the well-posedness of the $\mathbb{X}$-Dirichlet and $\mathbb{X}'$-Dirichlet problems in $\mathbb{R}^{n}_{+}$ in the class of all second-order, homogeneous, elliptic systems, with constant complex coefficients. As a consequence, we obtain that the Dirichlet problem for such systems is well-posed for boundary data in Lebesgue spaces, variable exponent Lebesgue spaces, Lorentz spaces, Zygmund spaces, as well as their weighted versions. We also discuss a version of the aforementioned result which contains, as a particular case, the Dirichlet problem for elliptic systems with data in the classical Hardy space $H^1$, and the Beurling-Hardy space ${\rm HA}^p$ for $p\in(1,\infty)$. Based on the well-posedness of the $L^p$-Dirichlet problem we then prove the uniqueness of the Poisson kernel associated with such systems, as well as the fact that they generate a strongly continuous semigroup in natural settings. Finally, we establish a general Fatou type theorem guaranteeing the existence of the pointwise nontangential boundary trace for null-solutions of such systems.
Page 1 /674
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.