bluuebunny/crossref_metadata_2025_split huggingface dataset:
Image Processing for Technological Diagnostics of Metallurgical Facilities
Authors: Doukovska Lyubka , Petkov Venko , Mihailov Emil , Vassileva Svetla 
Published: April 2013

Abstract
The paper presents an overview of the image-processing techniques. The set of basic theoretical instruments includes methods of mathematical analysis, linear algebra, probability theory and mathematical statistics, theory of digital processing of one-dimensional and multidimensional signals, wavelet-transforms and theory of information. This paper describes a methodology that aims to detect and diagnose faults, using thermographs approaches for the digital image processing technique.
Escape-on-Sight: An Efficient and Scalable Mechanism for Escaping DDoS Attacks in Cloud Computing Environment
Authors: Jeyanthi N. , Iyengar N. Ch. S. N. 
Published: April 2013

Abstract
Availability is one of the primary security issues in Cloud computing environment. The existing solutions that address the availability related issues can be applied in cloud computing environment, but because of their unique characteristics, such as on-demand self service, rapid elasticity, etc., there is a need to develop a detection mechanism that must satisfy the characteristics and an optimal profit for the Cloud Service Provider (CSP). A solution named Escape-on- Sight (EoS) algorithm is proposed in this paper that helps in detecting the attacker’s characteristics by analyzing traffic conditions stage by stage and protects the Data Center (DC) from malicious traffic. The profit analysis shows that the proposed approach has a reasonable chance of deploying EoS mechanism at DCs that are prone to DDoS attacks.
Shadow Detection and Removal from a Single Image Using LAB Color Space
Authors: Murali Saritha , Govindan V. K. 
Published: April 2013

Abstract
A shadow appears on an area when the light from a source cannot reach the area due to obstruction by an object. The shadows are sometimes helpful for providing useful information about objects. However, they cause problems in computer vision applications, such as segmentation, object detection and object counting. Thus shadow detection and removal is a pre-processing task in many computer vision applications. This paper proposes a simple method to detect and remove shadows from a single RGB image. A shadow detection method is selected on the basis of the mean value of RGB image in A and B planes of LAB equivalent of the image. The shadow removal is done by multiplying the shadow region by a constant. Shadow edge correction is done to reduce the errors due to diffusion in the shadow boundary.
Solution of Time-dependent Advection-Diffusion Problems with the Sparse-grid Combination Technique and a Rosenbrock Solver
Authors: Lastdrager Boris , Koren Barry , Verwer Jan 
Published: April 2013

Abstract In the current paper the efficiency of the sparse-grid combination tech-
nique applied to time-dependent advection-diffusion problems is investigated. For the
time-integration we employ a third-order Rosenbrock scheme implemented with adap-
tive step-size control and approximate matrix factorization. Two model problems are
considered, a scalar 2D linear, constant-coe±cient problem and a system of 2D non-
linear Burgers' equations. In short, the combination technique proved more efficient
than a single grid approach for the simpler linear problem. For the Burgers' equations
this gain in efficiency was only observed if one of the two solution components was set
to zero, which makes the problem more grid-aligned.
Three-Level Difference Schemes on Non-Uniform in Time Grids
Authors: Matus Piotr , Zyuzina Elena 
Published: April 2013

Abstract In this work, a stability of three-level operator-difference schemes on
nonuniform in time grids in Hilbert spaces is studied. A priori estimates of a long
time stability (for t → ∞) in the sense of the initial data and the right-hand side
are obtained in different energy norms without demanding the quasiuniformity of the
grid. New difference schemes of the second order of local approximation on nonuniform
grids both in time and space on standard stencils for parabolic and wave equations are
adduced.
Approximation of Singularly Perturbed Parabolic Reaction-Diffusion Equations with Nonsmooth Data
Authors: Shishkin Grigorii 
Published: April 2013

AbstractIn this paper we consider the Dirichlet problem on a rectangle for
singularly perturbed parabolic equations of reaction-diffusion type. The reduced (for
ε = 0) equation is an ordinary differential equation with respect to the time variable;
the singular perturbation parameter ε may take arbitrary values from the half-interval
(0,1]. Assume that sufficiently weak conditions are imposed upon the coefficients and
the right-hand side of the equation, and also the boundary function. More precisely,
the data satisfy the Hölder continuity condition with a small exponent α and α/2 with
respect to the space and time variables. To solve the problem, we use the known
ε-uniform numerical method which was developed previously for
problems with sufficiently smooth and compatible data. It is shown that the numerical
solution converges ε-uniformly. We discuss also the behavior of local accuracy of the scheme in
the case where the data of the boundary-value problem are smoother on a part of the
domain of definition.
Exponentially Convergent Parallel Discretization Methods for the First Order Evolution Equations
Authors: Gavrilyuk Ivan , Makarov Vladimir L. 
Published: April 2013

AbstractWe propose a new discretization of an initial value problem for differen-
tial equations of the first order in a Banach space with a strongly P-positive operator
coefficient. Using the strong positiveness, we represent the solution as a Dunford-
Cauchy integral along a parabola in the right half of the complex plane, then transform
it into real integrals over (−∞,∞), and finally apply an exponentially convergent Sinc
quadrature formula to this integral. The integrand values are the solutions of a finite
set of elliptic problems with complex coefficients, which are independent and may be
solved in parallel.
A High-Order Difference Scheme for a Nonlocal Boundary-Value Problem for the Heat Equation
Authors: Sun Zhi-Zhong 
Published: April 2013

Abstract This paper is concerned with a high order difference scheme for a non-
local boundary-value problem of parabolic equation. The integrals in the boundary
equations are approximated by the composite Simpson rule. The unconditional solv-
ability and L_∞ convergence of the difference scheme is proved by the energy method.
The convergence rate of the difference scheme is second order in time and fourth order
in space. Some numerical examples are provided to illustrate the convergence.
Iterative Methods for Solving Convection-diffusion Problem
Authors: Vabishchevich Petr N. 
Published: April 2013

AbstractTo obtain an approximate solution of the steady-state convectiondiffusion
problem, it is necessary to solve the corresponding system of linear algebraic
equations. The basic peculiarity of these LA systems is connected with the fact that
they have non-symmetric matrices. We discuss the questions of approximate solution
of 2D convection-diffusion problems on the basis of two- and three-level iterative methods.
The general theory of iterative methods of solving grid equations is used to present
the material of the paper. The basic problems of constructing grid approximations for
steady-state convection-diffusion problems are considered. We start with the consideration
of the Dirichlet problem for the differential equation with a convective term in
the divergent, nondivergent, and skew-symmetric forms. Next, the corresponding grid
problems are constructed. And, finally, iterative methods are used to solve approximately
the above grid problems. Primary consideration is given to the study of the
dependence of the number of iteration on the Peclet number, which is the ratio of the
convective transport to the diffusive one.
Convergence of Finite Fifference Method for Parabolic Problem
Authors: Bojović Dejan 
Published: April 2013

Abstract In this paper we consider the first initial boundary-value problem for the
heat equation with variable coefficients in a domain (0; 1)x(0; 1)x(0; T]. We assume that the
solution of the problem and the coefficients of the equation belong to the corresponding
anisotropic Sobolev spaces. Convergence rate estimate which is consistent with the
smoothness of the data is obtained.
A Schwarz Preconditioner for a Hybridized Mixed Method
Authors: Gopalakrishnan Jayadeep 
Published: April 2013

AbstractIn this paper, we provide a Schwarz preconditioner for the hybridized versions of the Raviart-Thomas and Brezzi-Douglas-Marini mixed methods. The preconditioner
is for the linear equation for Lagrange multipliers arrived at by eliminating the flux as well as the primal variable. We also prove a condition number estimate
for this equation when no preconditioner is used. Although preconditioners for the lowest-order case of the Raviart-Thomas method have been constructed previously by
exploiting its connection with a nonconforming method, our approach is different in that we use a new variational characterization of the Lagrange multiplier equation.
This allows us to precondition even the higher-order cases of these methods.
On the Rate of Convergence of Difference Schemes for the Poisson Equation with Dynamic Interface Conditions
Authors: Jovanovič Boško , Vulkov Lubin G. 
Published: April 2013

AbstractThe convergence of difference schemes for the two–dimensional weakly
parabolic equation (elliptic equation with a dynamic interface condition) is studied.
Estimates for the rate of convergence “almost” (except for the logarithmic factor)
compatible with the smoothness of the differential problem solution in special discrete
Sobolev norms are obtained.
Stability of Difference Schemes for Nonlinear Time-dependent Problems
Authors: Matus Piter 
Published: April 2013

AbstractIn the present paper, a priori estimates of the stability in the sense of the initial data of the difference schemes approximating quasilinear parabolic equations and
nonlinear transfer equation have been obtained. The basic point is connected with the necessity of estimating all derivatives entering into the nonlinear part of the difference
equations. These estimates have been proved without any assumptions about the properties of the differential equations and depend only on the behavior of the initial
and boundary conditions. As distinct from linear problems, the obtained estimates of stability in the general case exist only for the finite instant of time t 6 t0 connected with
the fact that the solution of the Riccati equation becomes infinite.
is already associated with the behavior of the second derivative of the initial function and coincides with the time of the exact solution destruction (heat localization in
the peaking regime). A close relation between the stability and convergence of the difference scheme solution is given. Thus, not only a priori estimates for stability
have been established, but it is also shown that the obtained conditions permit exact determination of the time of destruction of the solution of the initial boundary value
problem for the original nonlinear differential equation in partial derivatives. In the present paper, concrete examples confirming the theoretical conclusions are given.
The Sdfem for a Convection-diffusion Problem with Two Small Parameters
Authors: Roos Hans-Görg , Uzelac Zorica 
Published: April 2013

AbstractA singularly perturbed convection-diffusion problem with two small parameters is considered. The problem is solved using the streamline-diffusion finite element method on a Shishkin mesh. We prove that the method is convergent independently of the perturbation parameters. Numerical experiments support these theoretical results.
On Fast Domain Decomposition Solving Procedures for hp-Discretizations of 3-D Elliptic Problems
Authors: Korneev V. , Langer U. , Xanthis L. S. 
Published: April 2013

AbstractA DD (domain decomposition) preconditioner of almost optimal in p arithmetical complexity is presented for the hierarchical hp discretizations of 3-d second
order elliptic equations. We adapt the wire basket substructuring technique to the hierarchical hp discretization, obtain a fast preconditioner-solver for faces by Kinterpolation
technique and show that a secondary iterative process may be efficiently used for prolongations from faces. The fast solver for local Dirichlet problems on subdomains
of decomposition is based on our earlier derived finite-difference like preconditioner for the internal stiffness matrices of p-finite elements and fast solution procedures
for systems with this preconditioner, which appeared recently.
A Numerical Model for the Radial Flow Through Porous and Deformable Shells
Authors: Gaspar Francisco J. , Lisbona Francisco J. , Vabishchevich Petr N. 
Published: April 2013

AbstractEnergy estimates and convergence analysis of finite difference methods
for Biot's consolidation model are presented for several types of radial
ow. The model
is written by a system of partial differential equations which depend on an integer
parameter (n = 0; 1; 2) corresponding to the one-dimensional
ow through a deformable
slab and the radial
ow through an elastic cylindrical or spherical shell respectively.
The finite difference discretization is performed on staggered grids using separated
points for the approximation of pressure and displacements. Numerical results are
given to illustrate the obtained theoretical results.
A Discreate Calculus with Applications of High-Order Discretizations to Boundary-Value Problems
Authors: Steinberg Stanly 
Published: April 2013

AbstractWe develop a discrete analog of the differential calculus and use this
to develop arbitrarily high-order approximations to Sturm–Liouville boundary-value
problems with general mixed boundary conditions. An important feature of the method
is that we obtain a discrete exact analog of the energy inequality for the continuum
boundary-value problem. As a consequence, the discrete and continuum problems
have exactly the same solvability conditions. We call such discretizations mimetic.
Numerical test conﬁrm the accuracy of the discretization.
We prove the solvability and convergence for the discrete boundary-value problem
modulo the invertibility of a matrix that appears in the discretization being positive
deﬁnite. Numerical experiments indicate that the spectrum of this matrix is real,
greater than one, and bounded above by a number smaller than three.
An Almost Sixth-Order Finite-Difference Method for Semilinear Singular Perturbation Problems
Authors: Vulanović Relja 
Published: April 2013

AbstractThe discretization meshes of the Shishkin type are more suitable for high-
order finite-difference schemes than Bakhvalov-type meshes. This point is illustrated
by the construction of a hybrid scheme for a class of semilinear singularly perturbed
reaction-diffusion problems. A sixth-order five-point equidistant scheme is used at most
of the mesh points inside the boundary layers, whereas lower-order three-point schemes
are used elsewhere. It is proved under certain conditions that this combined scheme is
almost sixth-order accurate and that its error does not increase when the perturbation
parameter tends to zero.
Unsteady Flow of a Two-Layer Blood Stream Past a Tapered Flexible Artery under Stenotic Conditions
Authors: Chakravarty Santabrata ,   Sarifuddin, Mandal Prashanta Kumar 
Published: April 2013

Abstract The mechanics of the blood flow in a flexible tapered artery with stenosis
is studied from the viewpoint of a mathematical model. The flowing blood is represented
by a two-fluid model, consisting of a core region of suspension of all erythrocytes
assumed to be characterized by a Casson fluid and a peripheral plasma layer free from
cells of any kind as a Newtonian fluid. The moving wall of the artery is treated as an
anisotropic, linear viscoelastic incompressible circular cylindrical membrane cell. The
effect of the surrounding connective tissues on the motion of the artery wall is also
given due attention. The unsteady flow mechanism, subjected to a pulsatile pressure
gradient has been solved using the finite difference scheme by exploiting the appropriate
physically realistic prescribed conditions. The present model is also employed
to study the effect of taper angle, the wall deformation, the severity of the stenonis,
the viscosity of the peripheral layer, and the non-Newtonian rheology of streaming
blood on the dynamic flow field. Finally, the numerical illustration presented at the
end of the paper provides an effective quantitative measure of the flux, the resistive
impedance and the wall shear stress through their graphical representations and also
a few comparisons with the existing results have been made in order to validate the
applicability of the present model.
Numerical Blow-up for the p-Aplacian Equation with a Source
Authors: Ferreira Raŭl , De Pablo Arturo 
Published: April 2013

AbstractWe study numerical approximations of nonnegative solutions of the
p-Laplacian equation with a nonlinear source. We describe when solutions of a semidiscretization in space exist globally in time and when they blow up in a finite time. We also find the blow-up rates and the blow-up sets by means of the discrete self-similar profiles.
Explicit FV Scheme for the Perona-Malik Equation
Authors: Krivă Zuzana 
Published: April 2013

AbstractThe Perona|Malik equation for nonlinear di®usion is the well-known equation widely used in image processing. This equation can be applied with great success for selective smoothing of images, where the noise is represented by small gradients and the spurious edges are represented by the large ones. For a numerical solution of this equation we use the ¯nite volume method. We analyze convergence of a corresponding explicit finite volume scheme to its weak solution and show some numerical experiments. We suggest also some modi¯cations of this scheme to obtain better CPU time performance of the algorithm.
Exact Difference Schemes for Time-dependent Problems
Authors: Matus P , Irkhin U. , Lapinska-Chrzczonowicz M. 
Published: April 2013

AbstractFor one-dimensional and multidimensional semilinear transport equations of quite a general form with given initial data and boundary
conditions the exact difference schemes (EDSs) are constructed. In the case of constant coe±cients, such numerical methods can be created on rectangular grids, while in the
case of variable coefficients - on moving grids only. The questions of developing difference schemes of arbitrary order for quasi-linear transport equations with a nonlinear
right-hand side are discussed. In this paper, the EDSs are constructed also for certain classes of linear and quasilinear parabolic equations, for convection-diffusion problems with a small parameter,
as well as inhomogeneous wave equations with constant coe±cients.
Degenerate Time-dependent Variational Inequalities with Applications to Traffic Equilibrium Problems
Authors: Barbagallo A. 
Published: April 2013

Abstract The aim of this paper is to study the continuity of the solutions to
degenerate time-dependent variational inequalities. In order to obtain the continuity
of the solution, a previous continuity result for strongly monotone variational
inequalities and an appropriate use of the convergence set in Mosco’s sense play an
important role. The continuity result allows us to provide a discretization procedure
for the calculation of the solution to the variational inequality which expresses the
time-dependent traffic network equilibrium problem.
Domain Decomposition Approach for Automatic Parallel Generation of Tetrahedral Grids
Authors: Ivanov E.G. , Andrä H. , Kudryavtsev A.N. 
Published: April 2013

AbstractThe desire to simulate even more geometrical and physical features of
technical structures and the availability of parallel computers and parallel numerical
solvers which can exploit the power of these machines have led to a steady increase
in the number of the grid elements used. Memory requirements and computational
time are too large for usual serial PCs. An a priori partitioning algorithm for the
parallel generation of 3D non-overlapping compatible unstructured meshes based on a
CAD surface description is presented in this paper. Emphasis is placed on practical
issues and implementation rather than on theoretical complexity. In order to achieve
robustness of the algorithm with respect to the geometrical shape of the structure, the
authors propose that there should be several or many but relatively simple algorithmic
steps. The geometrical domain decomposition approach has been applied. It allows
us to use standard 2D and 3D high-quality Delaunay mesh generators for independent
and simultaneous volume meshing. Different aspects of load balancing methods are
also explored in the paper. The MPI library and SPMD model are used for parallel
grid generator implementation. Several 3D examples are given.
Structured Rank-(r1, . . . , rd) Decomposition of Function-related Tensors in R_D
Authors: Khoromskij B.N. 
Published: April 2013

AbstractThe structured tensor-product approximation of multidimensional nonlocal
operators by a two-level rank-(r1, . . . , rd) decomposition of related higher-order
tensors is proposed and analysed. In this approach, the construction of the desired
approximant to a target tensor is a reminiscence of the Tucker-type model, where the
canonical components are represented in a fixed (uniform) basis, while the core tensor
is given in the canonical format. As an alternative, the multilevel nested canonical
decomposition is presented. The complexity analysis of the corresponding multilinear
algebra shows an almost linear cost in the one-dimensional problem size. The existence
of a low Kronecker rank two-level representation is proven for a class of function-related
tensors.
Numerical Algorithms of Optimal Complexity for Weakly Singular Volterra Integral Equations
Authors: Tynda A.N. 
Published: April 2013

AbstractIn this paper we construct complexity order optimal numerical methods
for Volterra integral equations with different types of weakly singular kernels. We
show that for Volterra equations (in contrast to Fredholm integral equations) using the
”block-by-block” technique it is not necessary to employ the additional iterations to
construct complexity optimal methods.
ANALYTIC ITERATIVE PROCESSES AND NUMERICAL ALGORITHMS FOR STIFF PROBLEMS
Authors: FALEICHIK B.V. 
Published: April 2013

AbstractThe goal of the research is to construct practicable numerical algorithms for stiff systems of ordinary differential equations which let you increase the accuracy of the approximate solution without decreasing the length of the time interval. To achieve this goal, we have constructed a family of new iterative analytic processes generalising the Picard process. For a basic representative of this family, we demon-strate its better convergence properties on a scalar linear problem in comparison with the classical Picard process. For the general form of such iterative processes, we discuss their connection with existing methods for operator equations and propose a method for choosing their parameters. The efficiency of this parameter determination method is justified with a numerical experiment. In conclusion we propose a general approach to the construction of numerical algorithms which is based on the discretisation of the constructed iterative analytic processes.