bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Finite Volume Method for the Two-dimensional Stationary Navier — Stokes System
Authors: Djadel K. , Nicaise S. 
Published: April 2013

AbstractIn this paper we extend to the stationary incompressible Navier — Stokes system in dimension
two the results obtained in [14, 26] for a cell-centered finite volume method applied to the
stationary incompressible Stokes system. Here the nonlinear term is discretized as in [15].
We prove that the energy error norm is bounded by h, where h is the mesh size, under the
standard assumption that the datum is small enough with respect to the viscosity parameter.
Numerical tests on examples with analytic solutions and on standard benchmark problems
from fluid mechanics are presented and confirm the theoretical results.
Kronrod Extensions of Gaussian Quadratures with Multiple Nodes
Authors: Milovanović G.V. , Spalević M.M. , Galjak L.J. 
Published: April 2013

Abstract In this paper, general real Kronrod extensions of Gaussian quadrature
formulas with multiple nodes are introduced. A proof of their existence and uniqueness
is given. In some cases, the explicit expressions of polynomials, whose zeros are the
nodes of the considered quadratures, are determined. Very effective error bounds of
the Gauss — Turán — Kronrod quadrature formulas, with Gori — Micchelli weight
functions, for functions analytic on confocal ellipses, are derived.
Modeling of the Eigenfield of a Prestressed Hyperelastic Membrane Encapsulating a Liquid
Authors: Gavrilyuk Ivan. P. , Hermann M. , Timokha A. , Trotsenko V. 
Published: April 2013

AbstractA spectral boundary problem on the eigenfield of an inflated/deflated
stretched circular membrane, which is clamped to a circular cylindrical cavity filled with
a liquid, is examined. The paper presents an operator formulation of the problem and
proposes a new semi-analytical approximate method. The method captures singular
behavior of the solution in the pole and at the fastening contour of the membrane.
Exponentially Convergent Approximation to the Elliptic Solution Operator
Authors: Gavrilyuk Ivan. P. , Makarov V.L. , Vasylyk V.B. 
Published: April 2013

AbstractWe develop an accurate approximation of the normalized hyperbolic
operator sine family generated by a strongly positive operator
A in a Banach space X which represents the solution operator for the elliptic boundary
value problem. The solution of the corresponding inhomogeneous boundary value problem is found
through the solution operator and the Green function. Starting with the Dunford —
Cauchy representation for the normalized hyperbolic operator sine family and for the
Green function, we then discretize the integrals involved by the exponentially convergent
Sinc quadratures involving a short sum of resolvents of A. Our algorithm inherits
a two-level parallelism with respect to both the computation of resolvents and the
treatment of different values of the spatial variable x ∈ [0, 1].
Supraconvergence and Supercloseness of a Discretisation for Elliptic Third-kind Boundary-value Problems on Polygonal Domains
Authors: Emmrich E. 
Published: April 2013

AbstractThe third-kind boundary-value problem for a second-order elliptic equation
on a polygonal domain with variable coefficients, mixed derivatives, and first-order
terms is approximated by a linear finite element method with first-order accurate
quadrature. The corresponding bilinear form does not need to be strongly positive.
The discretisation is equivalent to a finite difference scheme.
Although the discretisation is in general only first-order consistent, supraconvergence,
i.e., convergence of higher order, is shown to take place even on nonuniform grids.
If neither oblique boundary sections nor mixed derivatives
occur, then the optimal order s is achieved. The supraconvergence result is equivalent
to the supercloseness of the gradient.
Dynamic Adaptation In Convection — Diffusion Equations
Authors: MAZHUKIN A.V. 
Published: April 2013

Abstract With the example of solving some known modeling problems the fea-tures of constructing grids adapted to the solution of parabolic equations are consid-ered. Convection-diffusion problems are described by nonlinear Burgers and Buckley — Leverette equations. A detailed analysis of the differential approximations and numerical results shows that the idea of using an arbitrary time-dependent system of coordinates for adapted grid generation in combination with the principle of quasi-stationarity makes the dy-namic adaptation method universal, effective, and algorithmically simple. Universality is achieved due to the use of an arbitrary time-dependent system of co-ordinates that moves at a velocity determined by the unknown solution. This universal approach makes it possible to generate adapted grids for time-dependent problems of mathematical physics with various mathematical features. Among these features are large gradients, and propagation of weak and strong discontinuities in known nonlinear transfer problems. The efficiency is determined by automatically fitting the velocity of the moving nodes to the dynamics of the solution. The close relationship between the adaptation mechanism and the structure of parabolic equations allows one to automatically control nodes motion of nodes so that their trajectories do not intersect. The simplicity of the algorithm is achieved due to the general approach to the adaptive grid generation that is independent of the form and type of the differential equations.
Singularly Perturbed Convection — Diffusion Problems in One Dimension: Bounds on Derivatives
Authors: Naughton A. , Stynes M. 
Published: April 2013

AbstractA convection-dominated singularly perturbed two-point boundary problem
is considered. For the numerical analysis of such problems, it is necessary to prove
certain a priori bounds on the derivatives of its solution. This paper provides a survey
of the ways in which such bounds can be proved, while assessing the feasibility of
extending such proofs to convection-dominated partial differential equations, and also
introduces a new proof based on a classical finite-difference argument of Brandt.
On the Iterative Solution Methods for Finite-Dimensional Inclusions with Applications to Optimal Control Problems
Authors: Laitinen E. , Lapin A. , Lapin S. 
Published: April 2013

AbstractIterative methods for finite-dimensional inclusions which arise in applying
a finite-element or a finite-difference method to approximate state-constrained optimal
control problems have been investigated. Specifically, problems of control on the right-
hand side of linear elliptic boundary value problems and observation in the entire
domain have been considered. The convergence and the rate of convergence for the
iterative algorithms based on the finding of the control function or Lagrange multipliers
are proved.
Super Exponentially Convergent Approximation to the Solution of the Schrödinger Equation in Abstract Setting
Authors: Gavrilyuk I.P. 
Published: April 2013

AbstractWe have developed an approximation to the solution of the Schrödinger
equation in abstract setting. The accuracy of our approximation depends on the
smoothness of this solution. We show that for the analytical initial vectors our approximation
possesses a super exponential convergence rate.
Well-Posedness and Blow Up for IBVP for Semilinear Parabolic Equations and Numerical Methods
Authors: Matus P. , Lemeshevsky S. , Kandratsiuk A. 
Published: April 2013

Abstract
We have studied the stability of finite-difference schemes approximating
boundary value problems for parabolic equations with a nonlinear and nonmonotonic
source of the power type. We have obtained simple sufficient input data conditions, in
which the solution of the differential problem is globally stable for all 0 ≤ t ≤ +∞. It is
shown that if these conditions fail, then the solution can blow up (go to infinity) in finite
time. The lower bound of the blow up time has been determined. The stability of the
solution of BVP for the nonlinear convection-diffusion equation has been investigated.
In all cases, we used the method of energy inequalities based on the application of
the Chaplygin comparison theorem for nonlinear differential equations, Bihari-type
inequalities and their discrete analogs.
A Discrete Vector Calculus in Tensor Grids
Authors: Robidoux Nicolas , Steinberg Stanly 
Published: April 2013

Abstract Mimetic discretization methods for the numerical solution of continuum mechanics
problems directly use vector calculus and differential forms identities for their
derivation and analysis. Fully mimetic discretizations satisfy discrete analogs of
the continuum theory results used to derive energy inequalities. Consequently,
continuum arguments carry over and can be used to show that discrete problems
are well-posed and discrete solutions converge. A fully mimetic discrete vector
calculus on three dimensional tensor product grids is derived and its key properties
proven. Opinions regarding the future of the field are stated.
On the Uniqueness and Reconstruction of Rough and Complex Obstacles from Acoustic Scattering Data
Authors: Sini Mourad 
Published: April 2013

Abstract We deal with the inverse scattering problem by an obstacle at a fixed frequency.
The obstacle is characterized by its shape, the type of boundary conditions on its
surface and the eventual coefficients distributed on this surface. In this paper,
we assume that the surface ∂D of the obstacle D is Lipschitz and the surface impedance,
λ, is given by a complex valued, measurable and bounded function. We prove uniqueness
of (∂D,λ) from the far field map under these regularity conditions. The usual proof of
uniqueness for obstacles, based on the use of singular solutions, is divided into two steps.
The first one consists of the use of Rellich type lemma to go from the far fields to the
near fields and then use the singularities of the singular solutions, via orthogonality
relations, to show uniqueness of ∂D. The second step is to use the boundary conditions
to prove uniqueness of λ on ∂D via the unique continuation property. This last step requires
the surface impedance to be continuous. We propose an approach using layer potentials to
transform the inverse problem to the invertibility of integral equations of second kind
involving the unknowns ∂D and λ. This enables us to weaken the required regularity
conditions by assuming ∂D to be Lipschitz and λ to be only bounded. The procedure of
the proof is reconstructive and provides a method to compute the complex valued and bounded
surface impedance λ on ∂D by inverting an invertible integral equation. In addition, assuming
∂D to be C^2 regular and λ to be of class C^{0,α}, with α>0, we give a direct and stable
formula as another method to reconstruct the surface impedance on ∂D.
Extended Variational Formulation for Heterogeneous Partial Differential Equations
Authors: Blanco Pablo , Gervasio Paola , Quarteroni Alfio 
Published: April 2013

AbstractWe address the coupling of an advection equation with a diffusion-advection equation,
for solutions featuring boundary layers. We consider non-overlapping domain decompositions
and we face up the heterogeneous problem using an extended variational formulation. We will
prove the equivalence between the latter formulation and a treatment based on a singular
perturbation theory. An exhaustive comparison in terms of solution and computational
efficiency between these formulations is carried out.
Sparse Discrete Ordinates Method in Radiative Transfer
Authors: Grella Konstantin , Schwab Christoph 
Published: April 2013

AbstractThe stationary monochromatic radiative transfer equation (RTE) is a partial differential
transport equation stated on a five-dimensional phase space, the Cartesian product of
physical and angular domain. We solve the RTE with a Galerkin FEM in physical space and
collocation in angle, corresponding to a discrete ordinates method (DOM). To reduce the
complexity of the problem and to avoid the "curse of dimension", we adapt the sparse grid
combination technique to the solution space of the RTE and show that we obtain a sparse DOM
which uses essentially only as many degrees of freedom as required for a purely spatial
transport problem. For smooth solutions, the convergence rates deteriorate only by a
logarithmic factor. We compare the sparse DOM to the standard full DOM and a sparse tensor
product approach developed earlier with Galerkin FEM in physical space and a spectral method
in angle. Numerical experiments confirm our findings.
Effective Tax Rates in the Moravian-Silesian Region
Authors: Janíčková Lenka 
Published: April 2013

Abstract
The aim of this work is to evaluate the effective corporate tax rate in the Moravian-Silesian Region in the Czech Republic on the basis of a backward-looking micro view. The results obtained are then compared with other methods of measuring the tax burden, especially with the corporate tax quota and effective corporate tax rate based on a backward-looking macro view and its components. The tax burden will be evaluated for the period 2007-2010 in order to capture the effects of the economic crisis. It is clear that the effective tax rate computed according to the backward-looking micro view and corporate tax quota confirms the results of a number of empirical studies because, in comparison to an effective marginal tax rate based on the macro view, they reflect fluctuations in business cycles.
Novel Ideas for Lossless Audio Coding
Authors: Ulacha Grzegorz , Stasiński Ryszard 
Published: April 2013

Abstract
Novel ideas for lossless audio coding analyzed in the paper are linked with forward predictor adaptation, and concern optimization of predictors on the basis of zero-order entropy and MMAE criterions, and context sound coding. Direct use of the former criterion is linked with exponential growth of optimization procedure, hence, a suboptimal algorithm having polynomial complexity is proposed. It is shown that on average the new types of predictors are better than those obtained by MMSE technique, while two- and three context systems are on average better than a single predictor one. It also appears that 7-bit PARCOR coefficients in the MPEG-4 ALS standard have insufficient precision for some predictor length, and that for very long frames coding results improve with the predictor rank practically in unlimited way.
Producing Random Bits with Delay-Line-Based Ring Oscillators
Authors: Jessa Mieczysław , Matuszewski Łukasz 
Published: April 2013

Abstract
One of the sources of randomness for a random bit generator (RBG) is jitter present in rectangular signals produced by ring oscillators (ROs). This paper presents a novel approach for the design of delays used in these oscillators. We suggest using delay elements made on carry4 primitives instead of series of inverters or latches considered in the literature. It enables the construction of many high frequency ring oscillators with different nominal frequencies in the same field programmable gate array (FPGA). To assess the unpredictability of bits produced by RO-based RBG, the restarts mechanism, proposed in earlier papers, was used. The output sequences pass all NIST 800-22 statistical tests for smaller number of ring oscillators than the constructions described in the literature. Due to the number of ROs with different nominal frequencies and the method of construction of carry4 primitives, it is expected that the proposed RBG is more robust to cryptographic attacks than RBGs using inverters or latches as delay element.
Influence of Drift on Efficiency of Optimal Analog Adaptive Communication Systems with Feedback and Its Compensation
Authors: Jędrzejewski Konrad 
Published: April 2013

Abstract
Results of analysis of drift influence on operation and efficiency of optimal analog adaptive communication systems with feedback and a new approach to drift compensation in these systems are presented in the paper. The proposed approach is based on application of the extended multidimensional adaptive algorithm that estimates simultaneously the value of a transmitted sample and the value of an unknown drift rate. The knowledge of the drift rate enables drift compensation and improves transmission efficiency of systems suffering problems related to drifts.
Seasonal changes in the understorey biomass of an oak-hornbeam forest Galio sylvatici-Carpinetum betuli
Authors: Jagodziński Andrzej M. , Pietrusiak Katarzyna , Rawlik Mateusz , Janyszek Sławomir 
Published: April 2013

Abstract
We studied seasonal changes in the understorey biomass of an oak-hornbeam forest association Galiosylvatici-Carpinetum betuli. Samples were collected weekly during the most dynamic period of herbaceous layer development (April-May 2010), and every two weeks for the remainder of the growing season (June-October). Samples were collected from 10 randomly selected localities of 0.36 m2 within the plant community. The plants harvested were separated by species, then oven-dried and weighed. There were statistically significant differences in aboveground understorey biomass during the time between harvests. For example, the lowest plant biomass (produced in 2010 and previous years) was found on April 3rd (37.2 kg/ha), whereas the two highest were on May 1st (308.1 kg/ha) and June 12th (337.6 kg/ha). The lowest biomass of plants produced in 2010 was on April 3rd (13.0 kg/ha) and the highest was on May 1st (259.8 kg/ha). When biomass of particular herbaceous plant species were analyzed, there was no one clearly dominant species. For example, from March 20th to May 22nd the biomass of Ficaria verna was the highest at ca. 36% of the total herbaceous layer plant biomass (range: 14.5-51.0%). During the next harvesting period (June-October), there were a few dominant herbaceous plant species, e.g. Geranium robertianum, Stachys sylvatica, Impatiens parviflora, Dryopteris dilatata, Dryopteris carthusiana, Dryopteris filix-mas, and Maianthemum bifolium.
Raman Spectroscopy as a New Biochemical Diagnostic Tool
Authors: Uskoković-Marković Snežana , Jelikić-Stankov Milena , Holclajtner-Antunović Ivanka , Đurđević Predrag 
Published: April 2013

Summary
In this review, Raman spectroscopy is described as a new and potentially powerful diagnostic tool in comparison to routine biochemical tests. Advanced instrumentation and new Raman spectroscopy techniques enable rapid and simultaneous identification and/or determination of several biochemical parameters, such as glucose, acetone, creatinine, urea, lipid profile, uric acid, total protein, etc, with a very low limit of detection. Raman spectroscopy could also be applied in molecule and cell characterization, as well as diagnostics of atherosclerosis in its early stage. Raman spectroscopy is nondestructive and could be applied to all kinds of samples, which simplifies the diagnostics of numerous diseases and pathologic states. Special attention is paid to literature data illustrating the application of Raman spectroscopy for transdermal glucose monitoring and cancer diagnostics.
From neoliberal policy to neoliberal pedagogy: Racializing and historicizing classroom management
Authors: Casey Zachary A. , Lozenski Brian D. , McManimon Shannon K. 
Published: April 2013

Abstract
In this article we first trace the history of “management,” particularly in the United States, from the plantation to the factory to the corporation, with the intention of understanding and contextualizing “classroom management” in today‘s educational lexicon. To do so, we look at the intertwining history of racial knowledge and the management of enslaved persons; the subsequent development of scientific management; social efficiency educators‘ application of scientific management to education; and conceptions of classroom management in today‘s neoliberal environment, in which education is increasingly positioned as a consumer good subject to individual choice and competitive markets. We further look to examples from post- -colonial Africa to demonstrate the ways in which neocolonial forms of scientific management comingle and entwine with neoliberal policies and procedures. The global phenomenon of scientific management, rife with neoliberalism and racism, is finally examined in the context of (so-called) Culturally Responsive Classroom Management, a neoliberal project that claims to advocate social justice through the process of managing bodies in classrooms.
Child- centered pedagogies, curriculum reforms and neoliberalism. Many causes for concern, some reasons for hope
Authors: Rodríguez Encarna 
Published: April 2013

Abstract
This article maps some of the ways in which neoliberalism, pedagogy, and curriculum are closely interconnected. Looking at the Spanish curriculum reform during the first Socialist administration in the late 1980s and early 1990s, it explicitly identifies child-centered pedagogies as an important tool in articulating the neoliberal agenda in curriculum reforms around the world. It explores the way Spain uncritically embraced these curriculum reforms with a notion of the individual not defined by the educational needs of the country but by the neoliberal rationality dominating Spain’s political and economic transition at the time. Based on this analysis and on the way child-centered pedagogies have been implemented in education reforms around the world, this article considers the question of whether such pedagogies can really work toward the democratic ideals they claim to serve. The article concludes by offering some reflections on this question and by calling for a larger and interdisciplinary conversation on the ideological possibilities of these pedagogies.
Software for Graphical Investigation of Planar and Spatial Closed Kinematic Chains for Robots and Manipulators
Authors: Zhelev Grigor 
Published: April 2013

Abstract
The aim of this paper is to present a developed computational program for computer graphical modelling of planar and spatial robots and manipulators closed kinematic chains. In order to demonstrate the functionality of the program two types of 5-bars and two types of 8-bars closed manipulators are used for simulation of the kinematic models. The basic mathematical calculations for visual representation of kinematic models are made, as well as calculations and visualisation of the manipulators zone of reachability frame by frame. The presented program can be used for analyzing closed kinematic chains, solving tasks from the real practice or for students training.
Heat Transfer Process Computer Simulation and Microstructure Prediction During Crystallization of Metal Alloys
Authors: Georgiev Georgi Evt. , Popov Sasho , Manolov Valentin , Dimitrova Rositsa , Kuzmanov Pavel 
Published: April 2013

Abstract
Processes of crystallization during casting formation from aluminum alloys, steel and cast iron have been studied using 3-D com- puter simulation. Temperature fields of castings have been obtained and the microstructure distribution of these castings has been predicted. A comparison between numerical results and experimental measurement has been performed. It is proved, that the proposed approach is suitable for investigation and analysis of casting technologies.