bluuebunny/crossref_metadata_2025 huggingface dataset:
A Class of Singularly Perturbed Convection-Diffusion Problems with a Moving Interior Layer. An a Posteriori Adaptive Mesh Technique
Authors: Shishkin Grigory I. , Shishkina Lidia P. , Hemker Pieter W.
Published: April 2013

We study numerical approximations for a class of singularly perturbed
convection-diffusion type problems with a moving interior layer. In a domain (segment)
with a moving interface between two subdomains, we consider an initial boundary value
problem for a singularly perturbed parabolic convection-diffusion equation. Convection
ﬂuxes on the subdomains are directed towards the interface. The solution of this
problem has a moving transition layer in the neighbourhood of the interface. Unlike
problems with a stationary layer, the solution exhibits singular behaviour also with
respect to the time variable. Well-known upwind ﬁnite difference schemes for such
problems do not converge ε-uniformly in the uniform norm. In the case of rectangular meshes
which are (a priori or a posteriori ) locally condensed in the transition layer. However, the condition for convergence can be considerably weakened
if we take the geometry of the layer into account, i.e., if we introduce a new coordinate
system which captures the interface. For the problem in such a coordinate system,
one can use either an a priori, or an a posteriori adaptive mesh technique. Here we
construct a scheme on a posteriori adaptive meshes (based on the solution gradient),
whose solution converges ‘almost ε-uniformly’.
Iterative Solutions of a Mixed Hybrid Finite Element Scheme for the Signorini Problem
Authors: Ignatieva Marina A. , Lapin Alexander V.
Published: April 2013

A mixed hybrid ﬁnite element method of the lowest order is studied
for the Signorini problem. An iterative method with a preconditioner being a classical
ﬁnite element approximation of the Laplace operator is constructed. A multistage
iterative procedure for the mixed hybrid ﬁnite element scheme is constructed, the rate
of convergence and the complexity of this method are analysed.
On the Generation of a Hexagonal Collision Model for the Boltzmann equation
Authors: Andallan Laek S.
Published: April 2013

In this article we prove the existence of two different classes of regular
hexagons in the hexagonal grid. We develop a generalized layer-wise construction of a hexagonal
discrete velocity model and derive general
formulae to identify all regular hexagons belonging to the grid. We also present some
numerical results based on the hexagonal grid.
Solution of a Wave Equation by a Mixed Finite Element - Fictitious Domain Method
Authors: Glowinski Roland , Lapin Serguei
Published: April 2013

The main goal of this article is to investigate the capability of fictitious
domain methods to simulate the scattering of linear waves by an obstacle whose shape
does not fit the mesh. The space-time discretization relies on a combination of a mixed
finite element method µa la Raviart-Thomas with a fairly standard finite difference
scheme for the time discretization. The numerical results described in the article point
to a good performance of the numerical method investigated here.
Space Mapping and Defect Correction
Authors: Echeverrĭa D. , Hemker P. W.
Published: April 2013

In this paper we show that space-mapping optimization can be understood in the framework of defect correction. Then, space-mapping algorithms can be seen as special cases of defect correction iteration. In order to analyze the properties of space mapping and the space-mapping function, we introduce the new concept of flexibility of the underlying models. The best space-mapping results are obtained for so-called equally flexible models. By introducing an a±ne operator as a left preconditioner, two models can be made equally flexible, at least in the neighborhood of a solution. This motivates an improved space-mapping (or manifold-mapping) algorithm. The left preconditioner complements traditional space mapping where only a right preconditioner is used. In the last section a few simple examples illustrate some of the phenomena analyzed in this paper.
Incompressible Fluid Flow Computation in an Arbitrary Two-dimensional Region on Nonstaggered Grids
Authors: Chuiko Mikhail , Lapanik Andrei , Nochetto Ricardo H.
Published: April 2013

A numerical algorithm for solving the Navier-Stokes equations for incom-
pressible viscous fluid in an arbitrary two-dimensional region on nonstaggered grids is
presented. The idea of the transition to a general curvilinear coordinate system, trans-
forming the physical region into a parametrical square is used. For the discrete solution
an unconditional a priory estimate has been obtained. The results of the benchmark
computations for a driven skewed cavity flow and the results of the fluid flow modeling
in a cavity of an arbitrary shape are given.
A Finite Volume Method for the Two-dimensional Stationary Navier — Stokes System
Authors: Djadel K. , Nicaise S.
Published: April 2013

In 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

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

A 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

We 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

The 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.
Error Estimates For The Lax — Friedrichs Scheme For Balance Laws
Authors: JOVANOVIC V.
Published: April 2013

We first derive the general error estimate for one – dimensional balance laws and afterwards we apply it to the elastodynamics system with source and to the isentropic Euler system with damping.
Approximate Solution Of A Singular Integral Equation With A Multiplicative Cauchy Kernel In The Half-Plane
Authors: KARCZMAREK P.
Published: April 2013

In this paper, Jacobi and trigonometric polynomials are used to con-struct the approximate solution of a singular integral equation with multiplicative Cauchy kernel in the half-plane.
Dynamic Adaptation In Convection — Diffusion Equations
Authors: MAZHUKIN A.V.
Published: April 2013

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

A 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

Iterative 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

We 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

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

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

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

We 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

The 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

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

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

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

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

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.
Effect of Yellow-Tinted Lenses on Visual Attributes Related to Sports Activities
Authors: Kohmura Yoshimitsu , Murakami Shigeki , Aoki Kazuhiro
Published: April 2013

The purpose of this study was to clarify the effect of colored lenses on visual attributes related to sports activities. The subjects were 24 students (11 females, 13 males; average age 21.0 ±1.2 years) attending a sports university. Lenses of 5 colors were used: colorless, light yellow, dark yellow, light gray, and dark gray. For each lens, measurements were performed in a fixed order: contrast sensitivity, dynamic visual acuity, depth perception, hand-eye coordination and visual acuity and low-contrast visual acuity. The conditions for the measurements of visual acuity and low-contrast visual acuity were in the order of Evening, Evening+Glare, Day, and Day+Glare. There were no significant differences among lenses in dynamic visual acuity and depth perception. For hand-eye coordination, time was significantly shorter with colorless than dark gray lenses. Contrast sensitivity was significantly higher with colorless, light yellow, and light gray lenses than with dark yellow and dark gray lenses. The low-contrast visual acuity test in the Day+Glare condition showed no significant difference among the lenses. In the Evening condition, lowcontrast visual acuity was significantly higher with colorless and light yellow lenses than with dark gray lenses, and in the Evening+Glare condition, low-contrast visual acuity was significantly higher with colorless lenses than with the other colors except light yellow. Under early evening conditions and during sports activities, light yellow lenses do not appear to have an adverse effect on visual attributes.
Raman Spectroscopy as a New Biochemical Diagnostic Tool
Authors: Uskoković-Marković Snežana , Jelikić-Stankov Milena , Holclajtner-Antunović Ivanka , Đurđević Predrag
Published: April 2013

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

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

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

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

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.
Two-Temperature Green and Naghdi Model on Thermoelastc Interaction in an Infinite Fibre-Reinforced Anisotropic Plate Containing a Circular Hole
Authors: Abbas Ibrahim A.
Published: April 2013

The present work is aimed at the study of thermoelastic interactions in an infinite fibre-reinforced anisotropic plate containing a circular hole in the context of a theory of generalized thermoelasticity in which the theory of heat conduction in deformable bodies depends on two different temperatures - conductive temperature and dynamic temperature. The two-temperature generalized thermoelastic model and one-temperature generalized thermoelastic model are formulated on the basis of Green and Naghdi theory of type II (2TGNII). The circular hole surface is assumed to be stress free and is subjected to a thermal shock. The problem is solved numerically using a finite element method. The effects of the presence and absence of reinforcement on the conductive temperature, the dynamical temperature, the stresses and the displacement distributions are studied. A comparison is made with the results predicted by the two theories. Results carried out in this paper can be used to design various fibre-reinforced anisotropic elements under thermal load to meet special engineering requirements.
Structure Preserving Simulation of Monopedal Jumping
Authors: Koch Michael W. , Leyendecker Sigrid
Published: April 2013

The human environment consists of a large variety of mechanical and biomechanical systems in which different types of contact can occur. In this work, we consider a monopedal jumper modelled as a three-dimensional rigid multibody system with contact and simulate its dynamics using a structure preserving method. The applied mechanical integrator is based on a constrained version of the Lagranged’Alembert principle. The resulting variational integrator preserves the symplecticity and momentum maps of the multibody dynamics. To ensure the structure preservation and the geometric correctness, we solve the non-smooth problem including the computation of the contact configuration, time and force instead of relying on a smooth approximation of the contact problem via a penalty potential. In addition to the formulation of non-smooth problems in forward dynamic simulations, we are interested in the optimal control of the monopedal high jump. The optimal control problem is solved using a direct transcription method transforming it into a constrained optimisation problem, see [14].
Comparative Study of Codes for Seismic Design of Structures
Authors: Hampshire De C. Santos Sergio , Zanaica Luca , Bucur Carmen , De Souza Lima Silvio
Published: April 2013

This paper presents a comparative evaluation among some international, European and American, seismic design standards. The study considers the criteria for the analysis of conventional (residential and commercial) buildings. The study is focused on some critical topics: definition of the recurrence periods for establishing the seismic input; definition of the seismic zonation and shape of the design response spectra; consideration of local soil conditions; definition of the seismic force-resisting systems and respective response modification coefficients; definition of the allowable procedures for the seismic analysis. A model for a standard reinforced concrete building (“Model Building”) has been developed to permit the comparison among codes. This building has been modelled with two different computer programs, SAP2000 and SOFiSTiK and subjected to seismic input according to the several seismic codes. The obtained results compared are leading to some important conclusions.
Unconditional Security by the Laws of Classical Physics
Authors: Mingesz Robert , Bela Kish Laszlo , Gingl Zoltan , Granqvist Claes-Göran , Wen He , Peper Ferdinand , Eubanks Travis , Schmera Gabor
Published: April 2013

There is an ongoing debate about the fundamental security of existing quantum key exchange schemes. This debate indicates not only that there is a problem with security but also that the meanings of perfect, imperfect, conditional and unconditional (information theoretic) security in physically secure key exchange schemes are often misunderstood. It has been shown recently that the use of two pairs of resistors with enhanced Johnsonnoise and a Kirchhoff-loop ‒ i.e., a Kirchhoff-Law-Johnson-Noise (KLJN) protocol ‒ for secure key distribution leads to information theoretic security levels superior to those of today’s quantum key distribution. This issue is becoming particularly timely because of the recent full cracks of practical quantum communicators, as shown in numerous peer-reviewed publications. The KLJN system is briefly surveyed here with discussions about the essential questions such as (i) perfect and imperfect security characteristics of the key distribution, and (ii) how these two types of securities can be unconditional (or information theoretical).
State Estimation Based on Generalized Gaussian Distributions
Authors: Li Xifeng , Xie Yongle
Published: April 2013

This paper presents a novel strategy of particle filtering for state estimation based on Generalized Gaussian distributions (GGDs). The proposed strategy is implemented with the Gaussian particle pilter (GPF), which has been proved to be a powerful approach for state estimation of nonlinear systems with high accuracy and low computational cost. In our investigations, the distribution which gives the complete statistical characterization of the given data is obtained by exponent parameter estimation for GGDs, which has been solved by many methods. Based on GGDs, an extension of GPF is proposed and the simulation results show that the extension of GPF has higher estimation accuracy and nearly equal computational cost compared with the GPF which is based on Gaussian distribution assumption.
An Empirical Review On Supply Chain Integration
Authors: Maleki Meysam , Cruz-Machado Virgilio
Published: April 2013

The purpose of this research is to review a sample of literature in the area of supply chain integration. Considering the extensive amount of literature on supply chain integration, it appears that it is still in its infancy. This study reviews a sample of 152 articles and in doing so throw light on different aspects of supply chain integration namely: vertical integration, functional integration, integration models .It discusses and criticizes the current state of literature on this context so that future researches find directions to contribute to missing points and remove obstacles. The scope of this review is limited to a cross-section of the literature in this area. As such, it cannot, and does not, attempt to be an examination of the full range of the literature, but a sampling of important and influential works.
Measurement and Analysis of Current Signals for Gearbox Fault Recognition of Wind Turbine
Authors: Lin Deng-Fa , Chen Po-Hung , Williams Mike
Published: April 2013

This paper presents a novel solution method based on measurement and analysis of current signals for gearbox fault recognition of wind turbine. A gearbox with typical oil-leakage fault is purposely made. The oil-leakage gearbox and a normal gearbox are used as experimental models to measure and analyze the current signals of generator. This work employs wavelet transform (WT), empirical mode decomposition (EMD) and fast Fourier transform (FFT) to analyze the current signals for both the oil-leakage and the normal gearboxes. K-nearest neighbors (KNN) is used on automatic fault recognition. First, the normal gearbox and the oilleakage gearbox are separately applied to practical power platform experiments. Second, empirical mode decomposition is applied on analyzing the intrinsic mode function (IMF) of the current signals, and fast Fourier transform is used to get the intrinsic mode function spectrum. Finally, the features of the spectrum are extracted, and K-nearest neighbors is used on gearbox fault recognition of wind turbine. Experimental results indicate that the proposed solution method can effectively recognize the oilleakage fault of gearboxes.
On the ship course-keeping control system design by using robust feedback linearization
Authors: Zwierzewicz Zenon
Published: April 2013

In the paper the problem of ship autopilot design based on feedback linearization method combined with the robust control approach, is considered. At first the nonlinear ship model (of Norrbin type) is linearized with the use of the simple system nonlinearity cancellation. Next, bearing in mind that exact values of the model parameters are not known, the ensuing inaccuracies are taken as disturbances acting on the system. Thereby is obtained a linear system with an extra term representing the uncertainty which can be treated by using robust, H∞ optimal control techniques. The performed simulations of ship course-changing process confirmed a high performance of the proposed controller despite the assumed significant errors of its parameters.
Possibilities for Motorways of the Sea development in the eastern part of the Adriatic Sea
Authors: Beškovnik Bojan
Published: April 2013

This article presents a wider perspective on possibilities of Motorways of the Sea development in the Adriatic Sea, with a special emphasis on the eastern coast of the Adriatic Sea. A complete overview of Motorways of the Sea development has been presented, and key elements influencing the development of Motorways of the Sea were analysed. It has been ascertained that there exist a lot of bottlenecks in the connection to the transport infrastructure in South East Europe. Superannuated port infrastructure, unsuitable inland connections, and nonexistent IT tools for electronic data exchange between all participators in the logistics chain hinder dynamic development of Motorways of the Sea. All these elements were thoroughly analysed, and a proposal for a macro transport strategy suitable for South East Europe has been exposed. It has been accentuated that there is a future for Motorways of the Sea introduction but all described bottlenecks have to be further analysed and removed in a short period of time, to stimulate private sector for financial investments.
The Design of Eman, an Experiment Manager
Authors: Bojar Ondřej , Tamchyna Aleš
Published: April 2013

We present eman, a tool for managing large numbers of computational experiments. Over
the years of our research in machine translation (MT), we have collected a couple of ideas for
efficient experimenting. We believe these ideas are generally applicable in (computational)
research of any field. We incorporated them into eman in order to make them available in a
command-line Unix environment.
The aim of this article is to highlight the core of the many ideas. We hope the text can serve
as a collection of experiment management tips and tricks for anyone, regardless their field of
study or computer platform they use. The specific examples we provide in eman’s current syntax
are less important but they allow us to use concrete terms. The article thus also fills the gap in
eman documentation by providing some high-level overview.
Minimally invasive CT guided treatment of intraspinal synovial cyst
Authors: Kozar Sergeja , Jeromel Miran
Published: April 2013

Background. Intraspinal synovial cysts of vertebral facet joints are uncommon cause of radicular pain as well as neurological deficits. They can be managed both conservatively and surgically.

Case report. A 77-year old polymorbid patient presented with bilateral low back pain which worsened during the course of time and did not respond to the conservative treatment. A diagnosis of intraspinal synovial cyst was made using the magnetic resonance imaging (MRI). Percutaneous computed tomography (CT) guided injection with installation of local anesthetic together with corticosteroid and rupture of the cyst was successfully used. A month after the procedure his pain improved, the usage of analgesics diminished and his over-all quality of life improved.

Conclusions. Percutaneous CT guided lumbar synovial cyst treatment is safe and reliable alternative to the surgical treatment in polymorbid patients with radiculopathy who are not able to tolerate general anesthesia and operation.
Histopathological Study of Cutaneous Lesions in Gout
Authors: Orzan Olguţa Anca , Simion George , Tudose Irina , Costache Mariana , Giurcăneanu Călin
Published: April 2013

Aim: To document the spectrum of histological changes of cutaneous lesions found in patients with gout. Material and methods: Thirteen cutaneous biopsies were studied. The biopsies were fixed in formalin solution and stained with hematoxyline and eosin. Results: A common feature in all 13 cases was the presence of deposits of basophilic material with needle-like clefts. The main histological reaction pattern was palisading granuloma. In 7 cases the deposits were subcutaneously located and in 6 cases intradermal and subcutaneously. The inflammatory infiltrate contained mainly epithelioid histiocytes and multinucleate giant cells. In 5 cases it also contained neutrophils and in one case foam cells. Secondary changes were found in 6 cases. Conclusion: When the clinical findings are atypical, cutaneous biopsy remains an important tool to establish the diagnosis of tophi, even in those cases with no possibility to exam alcohol fixed specimens under polarized light. In our study the preliminary clinical diagnosis was consistent with the histological findings in only 3 cases. The key feature that allowed the correct diagnosis was the presence of basophilic material with needle-like clefts surrounded by a palisading histiocytic infiltrate.
Multifactorial Analysis of a Group of Prediabetes Patients in Terms of Cardiovascular Risk
Authors: Adamescu Eduard , Niculescu Cătălina , Dobjanschi Carmen
Published: April 2013

Background and Aims: “Prediabetes” is defined by Impaired Fasting Glucose (IFG) or Impaired Glucose Tolerance (IGT), both states associated with increased risk for diabetes and high cardiovascular (CV) risk. The aim of our study was to investigate a population with prediabetes compared to a group from the general population in respect with the risk for progression to diabetes and CV risk parameters. Materials and Methods: We investigated 124 ambulatory patients with prediabetes and 98 persons without any known metabolic disorders (control group), for CV risk parameters and risk of developing diabetes. Results: We found statistically significant differences (p <0.05) for average weight, waist, BMI and lipids between the two groups. We also found a double risk score of developing diabetes in prediabetes patients compared to the control group. No significant differences were found in terms of anthropometric parameters, lipid values, cardiovascular disease and diabetes risk score for the IFG, IGT and IFG + IGT subgroups. Conclusions: People with prediabetes have features that differentiate them from the general population, both in terms of the history, anthropometric and biochemical characteristics. Increased risk for progression to diabetes, but also highly increased CV risk makes very useful the prevention efforts focused on this population group.
It’s Time for New Treatments in Pancreatic Cancer Pathology
Authors: Crişan Ramona , Aldea Mihaela , Kacso Gabriel
Published: April 2013

Background and aims: The objective of this study was to conclude if there are enough scientific evidences to consider metformin as a potential treatment for pancreatic cancer. Material and Method: We performed a systematic search using PubMed and MedlinePlus up to September 2012. Reference list of relevant peer reviewed literature were hand searched. Ultimately 15 articles were included. Results: Epidemiological studies had revealed that therapy with metformin was associated with 21% reduced risk for all types of malignancies, 31% reduction in overall summary relative risk, the median survival was longer: 16.6 vs. 11.5 months and the risk of death has decreased with 33%. In vitro it was proven that low doses of metformin block the stimulation of DNA synthesis and the growth of human pancreatic cancer cells. Prospective randomized clinical trials to confirm these data were already launched. Conclusions: These results raise the possibility that metformin could improve the poor prognostic of patients suffering from pancreatic cancer. Other clinical trials should confirm this hypothesis.
Challenges in vitamin D analysis / Izazovi u analizi vitamina D
Authors: Serteser Mustafa , Coskun Abdurrahman , Inal Tamer C , Unsal Ibrahim
Published: April 2013

Vitamin D is an important determinant for the regulation of calcium and phosphorus levels and mineralization of the bone. The most reliable indicator of vitamin D status is the measurement of plasma or serum 25OH-D concentration. Several studies reported discrepancies between the results of assays. These high variabilities in 25OH-D measurements are due to used assay technologies and lack of standardization against the reference materials. Different assays have been employed for the measurement of 25OHD levels: Competitive Protein Binding Assays, immunoassays, direct detection methods. Choosing an assay platform is important both for clinical laboratory professionals and researchers, and several factors affect this process. Recently, liquid chromatography and tandem mass spectrometry is an alternative method to traditional assays and provides higher specificity and sensitivity than many assays; therefore, it has been suggested as a candidate reference method for circulating 25OH-D3. Standardization of methods for the quantification of 25OH-D by using the human-based samples would reduce the inter-method variability. The best way for laboratories to demonstrate the accuracy of their results is by participating in the external quality assessment scheme. Standardization of the assays is also required to provide clinicians with the accurate tools to diagnose hypovitaminosis. In addition, assay-specific decision limits are needed to define appropriate thresholds of treatment.