bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Vibrations During Crystallization on Mechanical Properties and Porosity of EN AC-AlSi17 Alloy
Authors: Ciućka T. 
Published: April 2013

Abstract
Today’s industry aims at such situation, where number of defective products, so called defects shall approach to zero. Therefore, one introduces a various changes in technology of production, introduces improvements which would help in accomplishment of this objective. Another important factor is introduction of different type of testing, which shall help in assessment which factor has significant effect on quantity of rejects, and which one could be neglected. Existence of casting rejects is unavoidable; therefore a new ideas, technologies and innovations are necessary in the entire widely understood foundry branch, in order to minimize such adverse effect. Performance of tests aimed at unequivocal determination of an effect of vibrations during crystallization on mechanical properties and porosity of the EN ACAlSi17 alloy was the objective of the present work. To do this, there were produced 36 castings from EN AC-AlSi17 alloy. All the castings underwent machining operations. Half of the casting was destined to strength tests, the other half served to determination of an effect of vibrations on porosity of the alloy. The specimens were divided into 12 groups, depending on amplitude of vibrations and tilt angle of metal mould during pouring operation.
Test Bench for Analyzing the Lost Foam Process
Authors: Kaczorowski R. , Just P. , Pacyniak T. 
Published: April 2013

Abstract
The current work presents and describes the test bench for analyzing the lost foam process, especially measuring of the pressure of gases in the gas gap and continuous measuring of the rate of rise of the bath level when pouring the liquid metal into the mould. A series of preliminary research was carried out on the bench which was aimed at determining the influence of the basic parameters of the process, i.e. the density of the styrofoam pattern, thickness of the refractory coating applied on the pattern, kind of the alloy and the temperature of pouring on the mould cavity by the liquid metal and the pressure of gases in the gas gap.
Investigations of the Influence of the Matrix Recycling on Properties of the Moulding Sand with Geopol 618 Binder
Authors: Kamińska J. 
Published: April 2013

Abstract
Self-hardening moulding sands with water-glass hardened by liquid esters are applied in several foundry plants for making moulds for the production of heavy iron and steel castings. The main good point of this process is a low cost of sands. However, on account of a low susceptibility of this moulding sand for the matrix reclamation the fraction of sands originated from the reclamation is limited. The investigations presented in this work were aimed at the determination of the addition of the reclaimed material, obtained in the dry mechanical reclamation, on properties of the moulding sand with the Geopol 618 binder, which is water-glass modified by polymers and hardened by esters.
New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings
Authors: Myszka D. 
Published: April 2013

Abstract
The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found that the traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to mention only detonation spraying, carbonitriding, CVD methods, etc.
Modeling of Two-Stage Solidification: Part II Computational Verification of the Model
Authors: Wodo O. , Gawrońska E. 
Published: April 2013

Abstract
In Part I of this article, two-stage solidification model was presented. In this part we use our model to simulate solidification of the Al 7% Si alloy for two cooling rates -2 deg/s and -20 deg/s . Simulations have been performed for two eutectic transformation modes, typical for modified and unmodified alloys. Obtained cooling curves are qualitatively consistent with the typical cooling curves for modified and unmodified alloys. Moreover, evolution of cooling-curve characteristics is compared with the analytical model and found to be in close agreement.
Character and structural evolution of the Mała Łąka Fault in the Tatra Mts., Carpathians, Poland
Authors: Dąbrowska Magdalena , Jurewicz Edyta 
Published: April 2013

63
Abstract Dąbrowska, M. and Jurewicz, E. 2013. Character and structural evolution of the Mała Łąka Fault in the Tatra Mts., Carpathians, Poland. Acta Geologica Polonica, (1), 137-151. Warszawa. The Mała Łąka Fault in the Tatra Mts. is a synsedimentary normal fault responsible for the variable thickness of Eocene deposits in the area. Its main activity took place in the interval from the sedimentation of red conglomerates to the appearance of nummulitic limestones. The estimated throw is up to 350 m. Near the northern margin of the Tatra Mts., the trend of the fault changes from N-S to NE-SW. This part of the fault could have been activated during the Neogene uplift of the Tatra Mts. and rejuvenated as a sinistral fault. In the upper reach of the Mała Łąka Stream, the fault trend does not follow the course of the Mała Łąka Valley. Here, the flowing stream waters used extensional fractures within a damage zone associated with the Mała Łąka Fault rather than the lithological boundary at the tectonic contact between the Triassic dolomites and the Eocene conglomerates. The fault has a hingelike character; its hinge was located in the present-day Kościeliska Valley, c. 2.5 km west of the Mała Łąka Valley.
Cytogenetic Findings in Mentally Retarded Iranian Patients
Authors: Nasiri F. , Mahjoubi F. , Manouchehry F. , Razazian F. , Mortezapour F. , Rahnama M. 
Published: April 2013

ABSTRACT
We conducted a cytogenetic study on 865 individuals with idiopathic mental retardation (MR) who were admitted to the Cytogenetics Department of the Iran Blood Transfusion Organisation (IBTO) Research Centre, Tehran, Iran; these were performed on blood samples using conventional staining methods. Chromosome anomalies were identified in 205 of the patients (23.6%). The majority were Down’s syndrome cases (n = 138). In 33 males, a positive fragile X anomaly was found .The remainder (n = 34) had other chromosomal abnormalities including structural chromosome aberrations (n = 23), marker chromosomes with an unknown origin (n = 3), sex chromosome aneuploidy (n = 6) and trisomy 18 (n = 2). The contribution of chromosome aberrations to the cause of MR in this group of patients is discussed.
Optimization of a Compact Model for the Compliant Humanoid Robot COMAN Using Reinforcement Learning
Authors: Colasanto Luca , Kormushev Petar , Tsagarakis Nikolaos , Caldwell Darwin G. 
Published: April 2013

Abstract
COMAN is a compliant humanoid robot. The introduction of passive compliance in some of its joints affects the dynamics of the whole system. Unlike traditional stiff robots, there is a deflection of the joint angle with respect to the desired one whenever an external torque is applied. Following a bottom up approach, the dynamic equations of the joints are defined first. Then, a new model which combines the inverted pendulum approach with a three-dimensional (Cartesian) compliant model at the level of the center of mass is proposed. This compact model is based on some assumptions that reduce the complexity but at the same time affect the precision. To address this problem, additional parameters are inserted in the model equation and an optimization procedure is performed using reinforcement learning. The optimized model is experimentally validated on the COMAN robot using several ZMP-based walking gaits.
Sinus – A Semantic Technology Enhanced Environment For Learning In Humanities
Authors: Agre Gennady 
Published: April 2013

Abstract
The paper describes a semantic technology based environment intended for developing technology enhanced learning applications in humanitarian problem domains. The environment consists of three layers: the storage layer contains heterogeneous repositories storing domain and pedagogical knowledge; the tool level contains a set of tools for processing different types of knowledge and the middleware layer is implemented as an extended search engine carrying out all necessary communications between the tools and the repositories. Some implementation issues are discussed and a preliminary evaluation of the environment based on an exploitation is presented.
Experimental Study of Lyapunov Equation Solution Bounds for Power Systems Models
Authors: Savov Svetoslav , Popchev Ivan 
Published: April 2013

Abstract
This research work investigates the applicability of some lower and upper, matrix and scalar bounds for the solution of the Continuous Algebraic Lyapunov Equation (CALE), when the coefficient matrices are the state matrices of real data models. The bounds are illustrated for two different models describing the dynamic behavior of power systems - a two-area power system and an interconnected power system. Some important conclusions referring to the accuracy of the respective estimates are made, as well.
Codes Correcting Limited Patterns of Random Errors Using S-K Metric
Authors: Sharma Bhu Dev , Gaur Ankita 
Published: April 2013

Abstract
Coding is essential in all communications and in all multi-operation devices, and errors do occur. For error control, the method in vogue is to use code words with redundant digits. The number of redundant digits is determined based on two things − the number of messages and the kind of errors that need to be controlled. For efficient coding the redundant digits have to be kept to the minimum.
In this paper we introduce the idea of limited error patters while using the code alphabet {0,1, 2,..., 1},mod , q Z = q − q when q > 3. We define limitations of the errors in a position by substitution of the character there by a specified number of other characters, rather than by any other character. This is not possible through Hamming approach, because there a character in an error could be substituted by any other of the q-1 characters. The firm mathematical base is provided by use of a metric from the class of S-K metrics, Hamming metric being one of these.
The paper gives upper bounds on the codeword lengths for various kinds of “random limited error patterns”. Examples and discussion bring out the tremendous improvement and generalization of Rao Hamming bound.
High-degree Precision Decomposition Method for an Evolution Problem
Authors: Gegechkori Z. , Rogava J. , Tsiklauri M. 
Published: April 2013

AbstractIn the present work, a symmetrized sequential-parallel decomposition
method of the third degree of precision for solving Cauchy abstract problem is suggested.
The third degree of precision is reached by introducing the complex coefficient
α=1/2±i/(2√3)s. For the scheme considered, explicit a priori estimation is obtained.
An Analytical Approach for Quasi-Linear Equation in Second Order
Authors: Perepelkin E.E. , Zhidkov E.P. 
Published: April 2013

AbstractThis paper is devoted to the studies of the properties of the solutions
of non-linear partial differential equation, being basic ones in
differential formulation of the magnetostatic problem of finding the magnetic field dis-
tribution. The question of the existence of solutions, possessing an unlimited gradient,
for this equation is of particular interest. Previous works dealt with the linear
equation type, and also a boundary value problem was con-
sidered for certain requirements for the µ function, as well as a more general non-linear
case was studied. It was shown that such solutions exist, and their properties will be
investigated. The difference scheme for the boundary value problem was built in the
domain with corner and numerical calculations were given.
Amrvac: a Multidimensional Grid-adaptive Magnetofluid Dynamics Code
Authors: Nool Margreet , Keppens Rony 
Published: April 2013

Abstract We present the results obtained with AMRVAC, a software package
designed for solution-adaptive time-accurate (magneto)hydrodynamic simulations. In
any dimensionality, the grid adjusts to capture shocks and other sharp flow features
accurately following an automated Adaptive Mesh Refinement [AMR] strategy. This
grid adaptation algorithm is incorporated with the Versatile Advection Code [VAC],
so that it can be used to time-advance sets of conservation laws with options for the
spatial discretization employed. We demonstrate and evaluate the efficiency achievable
by AMR for 1D, 2D, and 3D test problems and describe the employed data structures.
Numerical Solutions of Fuzzy Differential Equations by Taylor Method
Authors: Abbasbandy Saeid , Viranloo Tofigh Allah 
Published: April 2013

Abstract In this paper, numerical algorithms for solving “fuzzy ordinary differential
equations” are considered. A scheme based on the Taylor method of order p is
discussed in detail and this is followed by a complete error analysis. The algorithm is
illustrated by solving some linear and nonlinear fuzzy Cauchy problems.
Solution of the Stokes Problem as an Inverse Problem
Authors: Agoshkov V. , Bardos C. , Buleev S. 
Published: April 2013

AbstractIn this study, we examine one of the approaches to the investigation and
solution of the Stokes equations: an original problem is regarded as an inverse problem
and then reduced to a problem of optimal control. Iteration algorithms are suggested
and results of numerical experiments are presented.
Solution of the Multi-interface Stefan Problem by the Method of Dynamic Adaptation
Authors: Mazhukin Vladimir , Chuiko Michail 
Published: April 2013

AbstractThe application of the dynamic adaptation method to the numerical
solution of multidimensional Stefan problems with explicit tracking of interfaces is
considered. The dynamic adaptation method is based on the idea of transition to
any non-stationary coordinate system. The results of the numerical experiment on
modelling the pulsed action of high-energy fluxes on metals are presented.
On Superconvergence of a Gradient for Finite Element Methods for an Elliptic Equation with the Nonsmooth Right–hand Side
Authors: Zlotnik Alexander 
Published: April 2013

AbstractThe elliptic equation under the nonhomogeneous Dirichlet boundary
condition in 2D and 3D cases is solved. A rectangular nonuniform partition of a
domain and polylinear finite elements are taken. For the interpolant of the exact
solution u, a priori error estimates are proved provided that u possesses a weakened smoothness.
Next error estimates are in terms of data. An estimate is established for the right–hand side f
of the equation having a generalized smoothness. Error estimates are derived in the case
of f which is not compatible with the boundary function. The proofs are based on some propositions
from the theory of functions. The corresponding lower error estimates are also included;
they justify the sharpness of the estimates without the logarithmic multipliers. Finally,
we prove similar results in the case of 2D linear finite elements and a uniform partition.
Spectrally Consistent Approximations to the Matrix Exponent and Their Applications to Boundary Layer Problem
Authors: Bobkov Vladimir V. 
Published: April 2013

AbstractIn an attempt to show maximum-norm stability and smoothing estimates for finite element discretizations of parabolic problems on nonquasi-uniform triangulations
we consider the lumped mass method with piecewise linear finite elements in one and two space dimensions. By an energy argument we derive resolvent estimate for the
associated discrete Laplacian, which is then a finite difference operator on an irregular mesh, which show that this generates an analytic semigroup in l_p for p‹∞
uniformly in the mesh, assuming in the two-dimensional case that the triangulations are of Delaunay type, and with a logarithmic bound for p=∞.
By a different argument based on a weighted norm estimate for a discrete Green's function this is improved to hold without a logarithmic factor for p=∞
in one dimension under a weak mesh-ratio condition. Our estimates are applied to show stability also for time stepping methods.
Applications of Primal-dual Interior Methods in Structural Optimization
Authors: Hoppe Ronald H. W. , Petrova Svetozara I. 
Published: April 2013

AbstractWe are concerned with structural optimization problems for technological processes in material science that are described by partial differential equations. In particular, we consider the topology optimization of conductive media in high-power electronic devices described by Maxwell equations and the optimal design of composite ceramic materials by homogenization modeling. All these tasks lead to constrained nonconvex minimization problems with both equality and inequality constraints on
the state variables and design parameters. After discretization by finite elements, we solve the discretized optimization problems by a primal-dual Newton interior-point
method. Within a line-search approach, transforming iterations are applied with respect to the null space decomposition of the condensed primal-dual system to find the
search direction. Some numerical experiments for the two applications are presented.
Analysis of a New Mixed Finite Volume Method
Authors: Mishev Ilya D. 
Published: April 2013

AbstractA new mixed finite volume method for elliptic equations with tensor coefficients on rectangular meshes (2 and 3-D) is presented. The implementation of
the discretization as a finite volume method for the scalar variable (“pressure”) is derived. The scheme is well suited for heterogeneous and anisotropic media because
of the generalized harmonic averaging. It is shown that the method is stable and well posed. First-order error estimates are derived. The theoretical results are confirmed
by the presented numerical experiments.
Resolvent Estimate in L_p for Discretisations of Second Order Ordinary Differential Operators on Variable Grids
Authors: Grigorieff R. D. 
Published: April 2013

Abstract In this paper, a resolvent estimate is proved for discretisations of second
order ordinary differential operators subject to Dirichlet boundary conditions on a finite
or infinite interval. As a discretisation method, a fully discrete Galerkin method using
continuous splines of order r > 2 on a locally quasi-uniform grid is considered. As a
byproduct, an a priori estimate for the discretised differential operator is obtained.
D-gap Functions for a Class of Equilibrium Problems in Banach Spaces
Authors: Konnov I. V. , Pinyagina O. V. 
Published: April 2013

AbstractWe consider rather a general class of equilibrium problems in a real Banach space, which involve nonsmooth convex functions. We apply the D-gap function
approach to these problems and show that, under certain additional assumptions, they can be converted into a problem of finding a stationary point of a differentiable function.
Based on this property, we suggest a descent type algorithm to find a solution to the initial problem. An example of applications to nonlinearly constrained equilibrium
problems is also given.
On Conditioning of a Schwarz Method for Singularly Perturbed Convection–diffusion Equations in the Case of Disturbances in the Data of the Boundary-value Problem
Authors: Shishkin Gregorii I. 
Published: April 2013

AbstractIn this paper we discuss conditioning of a discrete Schwarz method on piecewise–uniform meshes with an example of a one-dimensional singularly perturbed
boundary-value problem. We consider a Dirichlet problem for singularly perturbed ordinary differential equations with convection terms and a small perturbation parameter
ε. To solve the problem numerically we use an ε-uniformly convergent (in the maximum norm) difference scheme on special piecewise–uniform meshes. For this base scheme
we construct a decomposition scheme based on a Schwarz technique with overlapping subdomains, which converges ε-uniformly with respect to both the number of mesh
points and the number of iterations. The step-size of such special meshes is extremely small in the neighborhood of the layer and changes sharply on its boundary, that (as
was shown by A.A. Samarskii) can generally lead to a loss of well-conditioning of the above schemes. For the decomposition scheme we study the conditioning of the system
(difference scheme) and the conditioning of the system matrix (difference operator), and also the influence of perturbations in the data of the boundary-value problem on
disturbances of its numerical solutions. We derive estimates for the disturbances of the numerical solutions (in the maximum norm) depending on the subdomain in which
the disturbance of the data appears. It is shown that the condition number of the difference operator associated with the Schwarz method, just as for the base scheme,
is not ε-uniformly bounded. However, these difference schemes are well-conditioned ε-uniformly (with the ε-uniform estimate for the condition number being the same as
for the schemes on uniform meshes for regular problems) when the right-hand side of the discrete equations is considered in a “natural” norm, i.e., in the maximum norm
with a special weight multiplier. In the case
of the boundary-value problem with perturbed data we give conditions under which the solution of the iterative scheme based on the overlapping Schwarz method is convergent
ε-uniformly to the solution of this Dirichlet problem as the number of mesh points and the number of iterations increase.
Solution of Linear Equation Systems with a Dominant Skew-symmetric Part Using the Product Triangular Iterative Method
Authors: Chikina L. G. , Krukier B. L. 
Published: April 2013

AbstractA new product triangular iterative methods for solving nonsymmetric linear systems of equations with positive real coefficient matrices based on the skewsymmetric part of the initial matrix are proposed. The convergence analysis for the new methods is presented.
Methods for Numerical Modeling of Two-Dimensional Capillary Surfaces
Authors: Polevikov Victor K. 
Published: April 2013

Abstract Certain methods for numerical solving plane and axially symmetric
problems on equilibrium shapes of a capillary surface are presented. The methods
possess a high order of approximation on a nonuniform grid. They are easy to realize,
fairly universal and suitable for constructing not only simply connected but also doubly connected and disconnected surfaces, including strongly curved ones. It is shown
that the iterative algorithms constructed are absolutely stable at each iteration. The
condition for convergence of iterations is obtained within the framework of a linear
theory. To describe peak-shaped configurations of a magnetic
uid in a high magnetic field, an algorithm of generation of adaptive grid nodes in accordance with the surface
curvature is proposed. The methods have been tested for the well-known problems
of capillary hydrostatics on equilibrium shapes of a drop adjacent to the horizontal
rotating plate under gravity, and of an isolated magneticuid drop in a high uniform
magnetic field. It has been established that they adequately respond to the physical
phenomenon of a crisis of equilibrium shapes, i.e., they can be adopted to investigate
the stability of equilibrium states of a capillary surface.
A New Estimate of the Sing Method for Linear Parabolic Problems Including the Initial Point
Authors: Gavrilyuk Ivan , Makarov Vladimir L. , Vasylyk Vitaliy 
Published: April 2013

Abstract
For two new effcient methods for solving initial value problems in a Hilbert or Banach spaces based on a Sinc quadrature for an
improper Dunford-Cauchy integrals over a path enveloping the spectrum of the operator
we give a new unified estimate in the case of a Hilbert space.