bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Alternating Potential-Based Approach To The Cauchy Problem For The Laplace Equation In A Planar Domain With A Cut
Authors: CHAPKO R. , JOHANSSON B.T. 
Published: April 2013

Abstract We consider a Cauchy problem for the Laplace equation in a bounded region containing a cut, where the region is formed by removing a sufficiently smooth arc (the cut) from a bounded simply connected domain D. The aim is to reconstruct the solution on the cut from the values of the solution and its normal derivative on the boundary of the domain D. We propose an alternating iterative method which involves solving direct mixed problems for the Laplace operator in the same region. These mixed problems have either a Dirichlet or a Neumann boundary condition imposed on the cut and are solved by a potential approach. Each of these mixed problems is reduced to a system of integral equations of the first kind with logarithmic and hypersingular kernels and at most a square root singularity in the densities at the endpoints of the cut. The full discretization of the direct problems is realized by a trigonometric quadrature method which has super-algebraic convergence. The numerical examples presented illustrate the feasibility of the proposed method.
The Determinant Method for Nonselfadjoint Singular Sturm — Liouville Problems
Authors: Boumenir A. 
Published: April 2013

AbstractWe are concerned with the computation of eigenvalues of singular nonselfadjoint
Sturm — Liouville problems by the method of determinants. The representation
of a differential operator by an infinite matrix allows the use of Lidskii’s theorem
to define its determinant. The finite section is then used to compute eigenvalues in a
simple way. This direct method borrows stable methods from numerical linear algebra
to compute a large number of eigenvalues with high precision. Numerical examples
with nondifferentiable and complex valued coefficients are treated at the end.
Numerical Method for Finding Bifurcation Points of the Linear Two-parameter Eigenvalue Problem
Authors: Khlobystov V. V. , Podlevskyi B. M. 
Published: April 2013

AbstractThe iteration algorithm of finding bifurcation points of simple eigenvalue
curves of the linear algebraic two-parameter eigenvalue problem is considered. The
algorithm is based on the efficient numerical procedure of calculation of the derivative
of matrix determinant. Numerical results are given.
A Posteriori Error Estimators Based on Equilibrated Fluxes
Authors: Cochez-Dhondt Sarah , Nicaise Serge 
Published: April 2013

Abstract We consider the conforming of finite element approximations of reactiondiffusion
problems. We propose new a posteriori error estimators based on H(div)-
conforming finite elements and equilibrated fluxes. It is shown that these estimators
give rise to an upper bound where the constant is one in front of the indicator, up to
higher order terms. Lower bounds can also be established with constants depending on
the shape regularity of the mesh and the local variation of the coefficients. We further
analyze the convergence of an adaptive algorithm. The reliability and efficiency of the
proposed estimators are confirmed by various numerical tests.
Diffeomorphic Matching and Dynamic Deformable Surfaces in 3d Medical Imaging
Authors: Azencott R. , Glowinski R. , He J. , Jajoo A. , Li Y. , Martynenko A. , Hoppe R.H.W. , Benzekry S. , Little S.H. 
Published: April 2013

AbstractWe consider optimal matching of submanifolds such as curves and
surfaces by a variational approach based on Hilbert spaces of diffeomorphic transformations.
In an abstract setting, the optimal matching is formulated as a minimization
problem involving actions of diffeomorphisms on regular Borel measures considered as
supporting measures of the reference and the target submanifolds. The objective functional
consists of two parts measuring the elastic energy of the dynamically deformed
surfaces and the quality of the matching. To make the problem computationally accessible,
we use reproducing kernel Hilbert spaces with radial kernels and weighted
sums of Dirac measures which gives rise to diffeomorphic point matching and amounts
to the solution of a finite dimensional minimization problem. We present a matching
algorithm based on the first order necessary optimality conditions which include an
initial-value problem for a dynamical system in the trajectories describing the deformation
of the surfaces and a final-time problem associated with the adjoint equations.
The performance of the algorithm is illustrated by numerical results for examples from
medical image analysis.
A Natural Adaptive Nonconforming FEM Of Quasi-Optimal Complexity
Authors: Rabus H. 
Published: April 2013

AbstractIn recent years, the question on the convergence and optimality in the
context of adaptive finite element methods has been the subject of intensive studies.
However, for nonstandard FEMs such as mixed or nonconforming ones, the lack of
Galerkin's orthogonality requires new mathematical arguments. The presented adap-
tive algorithm for the Crouzeix-Raviart finite element method and the Poisson model
problem is of quasi-optimal complexity. Furthermore it is natural in the sense that
collective marking rather than a separate marking is applied or the estimated error
and the volume term.
Quasi-optimality of an Adaptive Finite Element Method for an Optimal Control Problem
Authors: Becker Roland , Mao Shipeng 
Published: April 2013

Abstract We prove quasi-optimality of an adaptive finite element algorithm for a model problem
of optimal control including control constraints. The quasi-optimility expresses the fact
that the decrease of error with respect to the number of mesh cells is optimal up to a
constant. The considered algorithm is based on an adaptive marking strategy which compares
a standard residualtype a posteriori error estimator with a data approximation term in each
step of the algorithm in order to adapt the marking of cells.
Energy Principles and Finite Element Methods for Pure Traction Linear Elasticity
Authors: Bochev Pavel , Lehoucq Richard 
Published: April 2013

AbstractA conforming finite element discretization of the pure traction elasticity boundary value
problem results in a singular linear system of equations. The singularity of the linear
system is removed through various approaches. In this report, we consider an alternative
approach in which discrete finite element formulations are derived directly from the principle
of minimum potential energy. This point of view turns out to be particularly well suited to
handle the rigid body modes, which are the source of the singularity in the finite element
linear system. Our approach allows us to formulate a regularized potential energy principle
and show that the associated weak problem is coercive in H1(Ω). This guarantees nonsingular
problems, enables simplified solution algorithms and leads to more efficient and robust
preconditioners for the iterative solution linear equations.
Adaptive Finite Element Methods For Optimal Control Of Second Order Hyperbolic Equations
Authors: Kröner Axel 
Published: April 2013

Abstract In this paper we consider a posteriori error estimates for space-time finite element
discretizations for optimal control of hyperbolic partial dierential equations of second
order. It is an extension of Meidner and Vexler (2007), where optimal control problems of
parabolic equations are analyzed. The state equation is formulated as a first order system
in time and a posteriori error estimates are derived separating the in uences of time, space,
and control discretization. Using this information the accuracy of the solution is improved
by local mesh refinement. Numerical examples are presented. Finally, we analyze the
conservation of energy of the homogeneous wave equation with respect to dynamically in time
changing spatial meshes.
Preface to the special issue, CMAM 2011, no. 3.
Authors: Gavrilyuk Ivan , Khoromskij Boris , Tyrtyshnikov Eugene 
Published: April 2013

Abstract In the recent years, multidimensional numerical simulations with tensor-structured data formats have been
recognized as the basic concept for breaking the "curse of dimensionality".
Modern applications of tensor methods include the challenging high-dimensional
problems of material sciences, bio-science, stochastic modeling, signal processing,
machine learning, and data mining, financial mathematics, etc.
The guiding principle of the tensor methods
is an approximation of multivariate functions and operators
with some separation of variables to keep the computational process in
a low parametric tensor-structured manifold.
Tensors structures had been wildly used as models of data and
discussed in the contexts of differential geometry, mechanics,
algebraic geometry, data analysis etc. before tensor methods recently
have penetrated into numerical computations. On the one hand, the existing tensor
representation formats remained to be of a limited use in many high-dimensional problems
because of lack of sufficiently reliable and fast software.
On the other hand, for moderate dimensional problems (e.g. in
"ab-initio" quantum chemistry) as well as for selected model problems
of very high dimensions, the application of traditional canonical
and Tucker formats in combination with the ideas of multilevel methods
has led to the new efficient algorithms.
The recent progress in tensor numerical methods is achieved with new
representation formats now known as "tensor-train representations"
and "hierarchical Tucker representations". Note that the formats themselves could have
been picked up earlier in the literature on the modeling of quantum systems.
Until 2009 they lived in a closed world of those
quantum theory publications and never trespassed the territory of
numerical analysis. The tremendous progress
during the very recent years shows the new tensor tools in various
applications and in the development of these tools and study of
their approximation and algebraic properties.
This special issue treats tensors as a base for efficient
numerical algorithms in various modern applications and with special
emphases on the new representation formats.
Quality Aspects of Fruit and Vegetables Dried Convectively with Osmotic Pretreatment
Authors: Kowalski Stefan J. , Łechtańska Joanna M. , Szadzińska Justyna 
Published: April 2013

Abstract
This article presents a quality analysis of convectively dried fruits and vegetables with preliminary osmotic dehydration. Tests were carried out on banana fruit and red beetroot samples. Hypertonic solutions of fructose for the banana and those of sucrose for the red beetroot were used, each one at three different concentrations. After osmotic dewatering treatment conducted at different time intervals and after osmotic dehydration the samples were dried convectively until an equilibrium with the surroundings was attained. Osmotic dehydration and convective drying curves were determined. The values of Solids Gain (SG), Water Loss (WL) and Weight Reduction (WR) were measured and changes in the samples’ colour and shape after convective drying with and without osmotic pretreatment were assessed.
Modelling the Dynamics of Flexible and Rigid Fibres
Authors: Kondora Grzegorz , Asendrych Dariusz 
Published: April 2013

Abstract
A particle-level simulation technique has been developed for modelling fibre suspension flow in a converging channel of a papermachine headbox. The fibre model is represented by a chain of elements connected together. The model was verified by the simulation of rigid fibre dynamics in a simple shear flow. The period of rotation was found to be in a very good agreement with theory and reference data. The model was then employed to simulate fibre motion in a converging channel of a papermachine headbox. Fibre suspension motion was resolved using two-step procedure. Velocity field was calculated by means of a commercial CFD code ANSYS Fluent with RSM turbulence model applied and used as an input to the in-house code allowing to simulate fibre dynamics. Results of the calculations were used to construct the fibre orientation probability distribution (FOPD) which was found to be consistent with available experimental data.
Dew Point of the Flue Gas of Boilers Co-Firing Biomass with Coal
Authors: Ciukaj Szymon , Pronobis Marek 
Published: April 2013

Abstract
The paper deals with the impact of co-firing biomass with coal in boilers on the dew point of the flue gas. Co-firing of biomass may have twofold implications on corrosion and fouling, which are the processes that determine the lowest acceptable flue gas outlet temperature and as a result, boiler efficiency. Both phenomena may be reduced by co-firing of usually low sulphur biomasses or enhanced due to increased moisture content of biomass leading to increased water dew point. The present study concerns the problem of low-temperature corrosion in utility boilers. The paper gives (in the form of diagrams and equations) a relationship between water dew point and moisture content of fuel mixture when co-firing coal and various biomasses. The regression analysis shows that despite significant differences in the characteristics of coals and these of additional fuels, which are planned for co-firing in large-scale power boilers, the water dew point can be described by a function given with the accuracy, which shall be satisfactory for engineering purposes. The discussion of the properties of biofuels indicates that the acid dew point surplus over the water dew point (Δtr = tr - twr) is not likely to exceed 10 K when co-firing biomass. The concluding remarks give recommendations for the appropriate operation of boilers in order to reduce risks associated with biomass co-combustion.
Research on Thermal Decomposition of Waste PE/PP
Authors: Kuźnia Monika , Magdziarz Aneta 
Published: April 2013

Abstract
The most important and the most frequently used plastics are polyethylene (PE) and polypropylene (PP). They are characterised with high heating values (approximately 40 MJ/kg). Moreover, their chemical composition, based mainly on carbon and hydrogen, allows to use them in industrial processes. One of the methods of utilisation of plastic waste can be its use in the metallurgical industry. This paper presents results of thermal decomposition of waste PE/PP. Chemical and thermal analysis (TG) of studied wastes was carried out. Evolved gaseous products from the decomposition of wastes were indentified using mass spectrometry (TG-MS). This paper also presents an application of plastic wastes as supplemental fuel in blast furnace processes (as a substitute for coke) and as an addition in processes of coking coal.
FIR Filter Design Using Distributed Maximal Flatness Method
Authors: Blok Marek 
Published: April 2013

Abstract
In the paper a novel method for filter design based on the distributed maximal flatness method is presented. The proposed approach is based on the method used to design the most common FIR fractional delay filter - the maximally flat filter. The MF filter demonstrates excellent performance but only in a relatively narrow frequency range around zero frequency but its magnitude response is no greater than one. This ,,passiveness” is the reason why despite of its narrow band of accurate approximation, the maximally flat filter is widely used in applications in which the adjustable delay is required in feedback loop. In the proposed method the maximal flatness conditions forced in standard approach at zero frequency are spread over the desired band of interest. In the result FIR filters are designed with width of the approximation band adjusted according to needs of the designer. Moreover a weighting function can be applied to the error function allowing for designs differing in error characteristics. Apart from the design of fractional delay filters the method is presented on the example of differentiator, raised cosine and square root raised cosine FIR filters. Additionally, the proposed method can be readily adapted for variable fractional delay filter design regardless of the filter type.
On Some DOA Algorithms for Tri-axial Geophone
Authors: Mazur Jan , Świętach Zbigniew 
Published: April 2013

Abstract
In this paper a short study of some basic methods of DOA of a seismic wave using so called tri-axial geophone has been presented. The proposed methods exploit the properties of Rayleigh surface plane wave to find DOA of an incoming seismic wave using inner products of appropriately filtered signals recorded by geophones. The advantage of the proposed method is its simplicity and ease of implementation in small DSP or application processors still retaining pretty good accuracy. A number of example results for real data have been given.
Obstacle Avoidance Procedure and Lee Algorithm Based Path Replanner for Autonomous Mobile Platforms
Authors: Polańczyk Maciej , Strzelecki Michał , Ślot Krzysztof 
Published: April 2013

Abstract
The paper proposes solution for two important issues connected to navigation of independent mobile platforms in an unknown environment. First issue relates to obstacle map, estimated based on stereovision images. It provides a basis for further platform path-planning. The main problem that has to be solved in obstacle map derivation is elimination of artifacts resulting from depth estimation. Thus a two-step artifact filtering procedure is proposed, which exploits both within-frame spatial correlations as well as temporal, between-frame correlations to do this task. Second procedure, based on well-known Lees algorithm is designed for obtaining vehicle collisionless path. Such routes need to be updated on-the-fly to take into account moving obstacles or newly detected objects. The main idea of the proposed approach is to identify regions where environment has changed and to execute a procedure of selective path updates. As a result, an optimal path can be derived at a computational expense comparable to the heuristic Lifelong A* search. Experiment results demonstrate efficiency of the two discussed approaches for platform operation control in real environments, where both static and moving obstacles are present.
Characteristic and diagnostic features of the most frequently occurring species of the Thripidae family (Insecta, Thysanoptera) in crown canopies of Central European forests
Authors: Kucharczyk Halina , Kucharczyk Marek 
Published: April 2013

Abstract
The paper presents characteristic and morphological diagnostic features of females and second larval instar of six terebrantian species: Oxythrips ajugae Uzel 1895, O. bicolor (O. M. Reuter 1879), Taeniothrips inconsequens (Uzel 1895), Thrips calcaratus Uzel 1895, T. minutissimus Linnaeus 1758 and T. pini (Uzel 1895). The species are the most numerously and frequently caught in traps in the canopy layer of various Central European forests. Both adults and larvae of Oxythrips spp. may be easily recognized by features present at the end of their abdomen: the former by length of the abdominal segment X; the latter by differences in the length and position of spines. Adults of other the species mentioned above differ in the following features: number of antennal segments, number of setae in the distal part of their first pair of wings, presence or absence of additional setae on abdominal sternites and pleurites, presence or absence of a tooth on the tarsus of the first pair of legs. The main features differentiating larvae of these species (besides T. pini larva which have been hitherto undescribed) are body sclerotisation and length, and shape of the comb surrounding the IXth abdominal segment.
Stand damage when harvesting timber using a tractor for extraction
Authors: Karaszewski Zbigniew , Giefing Dieter F. , Mederski Piotr S. , Bembenek Mariusz , Dobek Anita , Stergiadou Anastasia 
Published: April 2013

Abstract
Damage to the remaining stand is an unavoidable consequence of thinning operations. The different machines used for timber extraction differ in the level of damage of trees they cause, mainly through wounds to the bark and cambium which can make a substantial impact on the remaining trees. Three different methods of timber harvesting with a chainsaw were analyzed: the short wood system (SWS), the long wood system (LWS) and the full tree system (FTS) in which an agricultural tractor is used for timber extracting. All systems were analyzed in stands containing three different age classes: 2nd (21-40 years), 3rd (41-60 years) and 4th (61-80 years). The level of damage to the remaining stand was assessed considering the percentage of trees exhibiting wounds (scratched bark and/or damage to the cambium) to calculate an index of stand damage (WDI) which incorporated the volume of harvested timber per hectare. The SWS produced the lowest damage to trees in stands of all age classes: average 5%, with the less damage in the oldest stand. After using the LWS, 9% of trees were wounded; in this method there was no statistical difference in frequency of wounding across all the analyzed stands. The highest level of damage was incurred after the FTS, causing 11% of trees to be injured. In stands of the 2nd age class, the method of timber harvesting had no statistically significant effect on the amount of wounding endured. The WDI was lowest in SWS: 0.08, higher in LWS: 0.15 and the highest, 0.23, when FTS was applied.
Correlation between geology and concentration-volume fractal models: significance for Cu and Mo mineralized zones separation in the Kahang porphyry deposit (Central Iran)
Authors: Yasrebi Amir Bijan , Afzal Peyman , Wetherelt Andy , Foster Patrick , Esfahanipour Reza 
Published: April 2013

Abstract
This study identifies the major mineralized zones including supergene enrichment and hypogene enrichment in the Kahang Cu-Mo porphyry deposit which is located in Central Iran based on subsurface data and utilization of the concentration-volume (C-V) fractal model. Additionally, a correlation between results achieved from a C-V fractal model and geological models consisting of zonation, mineralography and alteration have been conducted in order to have an accurate recognition and modification of the main mineralized zones. Log-log plots indicate five geochemical populations for Cu and Mo in the deposit which means that mineralization commences with 0.075 % and 13 ppm for Cu and Mo (as the first thresholds) respectively. The main mineralization began for Cu ≥ 0.42 % and Mo ≥ 100 ppm and also enriched mineralization containing Cu ≥1.8 % and Mo ≥ 645 ppm which is located in the central part of the deposit. According to the C-V model, the main Cu-Mo mineralized zones occur in the hypogene zone, especially in the central, NW and NE parts of the Kahang deposit. The supergene enrichment zone derived via the C-V model is smaller than that in the geological model and is located in the central and eastern parts of the deposit. Results analysed by the C-V fractal model certify that the interpreted zones based on the fractal model are accurate. To certify this, a logratio matrix has been employed to validate the C-V fractal model for the Cu and Mo main mineralized zones
Fault contact of the Pieniny Klippen Belt with the Central Carpathian Paleogene Basin (Western Carpathians): new data from a unique temporary exposure in L̓utina village (Eastern Slovakia)
Authors: Plašienka Dušan , Józsa Štefan , Gedl Przemysław , Madzin Jozef 
Published: April 2013

Abstract
An exceptional, briefly exposed section across the boundary between the Pieniny Klippen Belt (PKB) and the Central Carpathian Paleogene Basin (CCPB) in Eastern Slovakia showed that the contact is formed by a single, subvertical fault plane. Whereas the Oligocene CCPB deposits exhibit only weak deformation with S-verging fold-and-thrust structures, the Cretaceous PKB sediments are internally strongly sheared with scaly fabric and numerous calcite veins. It is inferred that the PKB suffered strong thrusting- and wrenching-related deformation in pre-Oligocene times, while the Early Miocene oblique backthrusting resulted in exhumation of the PKB and formation of its steep fault boundaries