bluuebunny/crossref_metadata_2025_split huggingface dataset:
Knotted linear force‐free magnetic fields‐topological aspects
Authors: Kotiuga P. Robert 
Published: December 2008

AbstractThe problem of computing linear force‐free magnetic fields on a knotted multiply‐connected domain is considered. The domain is the support of the current distribution, and the linear force‐free fieldproblem reduces to finding an eigenfield of a self‐adjoint curl operator. In this context, the GKN Theorem is reformulated in terms of symplectic geometry in order to characterize the self‐adjoint extensions of the curl operator restricted to solenoidal vector fields. When further restricted to the isotopy invariant boundary conditions, the self‐adjoint extensions are parametrized by the Lagrangian subspaces of the symplectic form on the first homology group of the boundary. This paper discusses some of the topological aspects and gives some pointers for the associated finite element discretization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational splines for the numerical solution of singular differential equations
Authors: Gorbunov Vladimir , Lutoshkin Igor , Martynenko Yuliya 
Published: December 2008

AbstractThe numerical parametrization method (PM), originally created for optimal control problems, is specificated for classical calculus of variation problems that arise in connection with singular implicit (IDEs) and differential‐algebraic equations (DAEs). The PM for IDEs is based on representation of the required solution as a spline with moving knots and on minimization of the discrepancy functional with respect to the spline parameters. Such splines are named variational splines. For DAEs only finite entering functions can be represented by splines, and the functional under minimization is the discrepancy of the algebraic subsystem. The first and the second derivatives of the functionals are calculated in two ways – for DAEs with the help of adjoint variables, and for IDE directly. The PM does not use the notion of differentiation index, and it is applicable to any singular equation having a solution. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mathematical and physical modelling of seismic faults (Poster Presentation)
Authors: Diosdado A. Muñoz 
Published: December 2008

AbstractModelling of seismic faults by using spring block systems on a frictional surface, requires to solve coupled differential equation systems with a great number of equations, in order to avoid this problem, the spring‐block model is mapped into a continuous, non‐conservative cellular automaton. Every time the automaton is calculated a synthetic earthquake is obtained. We obtained catalogues of synthetic earthquake magnitude, which we can represent as a time series. Such series exhibit power law behavior so much for the magnitudes (Gutenberg‐Richter law) as for the duration times. The analysis of these time series with methods of non‐linear dynamics provides interesting results; for example, the time series show multifractality for large values of the conservation level. We present the correlation analysis of three kinds of time series: recurrence times, jumps or distance between consecutive earthquakes and magnitude for different thresholds. We obtained long correlations in recurrence times as it has been observed in real seismicity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiparametric frequency‐domain criteria for stability of distributed systems with multiple equilibria (Poster Presentation)
Authors: Smirnova V.B. , Perkin A.A. 
Published: December 2008

AbstractFor integral Volterra equations with periodic nonlinear functions and nonlinear functions satisfying the sector condition, new frequency domain criteria for gradient‐like behavior are obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A short overview of some behavioural scenarios for derivative pricing in incomplete markets
Authors: Pinheiro D. , Pinto A. A. , Xanthopoulos S. Z. , Yannacopoulos A. N. 
Published: December 2008

AbstractWe shortly describe three different but related scenarios for determination of asset prices in an incomplete market: one scenario uses a market game approach whereas the other two are based on risk sharing or regret minimizing considerations. Furthermore, we point out some new dynamical schemes modeling the convergence of the buyer's and of the seller's prices of a given asset to a unique price. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab‐initio study of transition temperature of Mn‐doped GaN diluted magnetic semiconductor (Poster Presentation)
Authors: Rufinus J. 
Published: December 2008

AbstractWe study the effect of clustering and random metal atoms distribution on the transition temperature of Mn‐doped GaN Diluted Magnetic Semiconductors. To calculate the exchange coefficients between the Mn atoms, a Density functional theory‐based Locally Self Consistent Multiple Scattering (LSMS) method has been used. Here we present the results of our calculations, which show that random metal distribution increases the calculated transition temperature of the material while the clustering decreases it. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupled cell networks: minimality
Authors: Aguiar Manuela A. D. , Dias Ana Paula S. 
Published: December 2008

AbstractNon‐isomorphic coupled cell networks with the same number of cells and with equivalent dynamics are said to be ODE‐equivalent. Moreover, they are all related by a linear algebra condition involving their graph adjacency matrices. A network in an ODE‐class is said to be minimal if it has a minimum number of edges among all the networks of the class. In this short paper we review the characterization of the minimal networks of an ODE‐equivalence class and we present an example for the case of non‐homogeneous networks. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diffusion of nonstationary stirred fields
Authors: Arnaut L. R. 
Published: December 2008

AbstractRapid perturbations of the boundaries of an overmoded cavity for acoustic or electromagnetic fields cause nonstationary effects of the stochastic properties of the field. The associated Langevin–Itô and Fokker–Planck equations for the energy density and field amplitude are derived. Analytic solutions for the field magnitude and energy density are obtained, showing that the field dynamics can be characterized as a generalized diffusion process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
General solutions of the Oseen equations
Authors: Padmavati B. Sri 
Published: December 2008

AbstractA new general solution of Oseen [3] equations has been suggested [4]. A necessary and sufficient condition for a divergence‐free vector to represent the velocity in an Oseen flow is given. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On characteristics of investment projects efficiency
Authors: Bronshtein Efim 
Published: December 2008

AbstractThe class of investment projects (named correct projects) and its efficiency characteristic (named limited profitability) is defined. Some properties of limited profitability showing its practical advantage are established. It is proved that limited profitability coincides with Arrow‐Levhari characteristic. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On selective harvesting of an inshore‐offshore fishery: a bioeconomic model
Authors: Chaudhuri Kripasindhu 
Published: December 2008

AbstractIn the present paper, a bioeconomic model is developed for the selective harvesting of a single species, inshore‐offshore fishery, assuming that the growth of the species is governed by the Gompertz law. The dynamical system governing the fishery is studied in depth; the local and global stability of its non‐trivial steady state are examined. Existence of a bionomic equilibrium is established under different parametric considerations. The optimal harvest policy is discussed by invoking Pontryagin's Maximum Principle. Lastly, the results are illustrated with the help of a numerical example. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of precipitates on the evolution of a martensitic phase boundary
Authors: Dondl Patrick W. , Bhattacharya Kaushik 
Published: December 2008

AbstractIn this article, we study the role of defects in the quasistatic evolution of a martensitic phase boundary. The formulation of the model gives rise to a nonlocal free boundary problem, for which we present an implicit finite‐time discretization. For an approximate model, assuming a nearly flat interface, we show that the phase boundary exhibits a sick‐slip behavior in the presence of a heterogeneous environment, thus leading to a transition from viscous kinetics to rate‐independent behavior. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some exact controllability results for the linear KdV equation and uniform controllability in the zero‐dispersion limit
Authors: Glass Olivier , Guerrero Sergio 
Published: December 2008

AbstractIn this paper, we deal with controllability properties of linear and nonlinear Korteweg‐de Vries equations in a bounded interval. The main part of this paper is a result of uniform controllability of a linear KdV equation in the limit of zero‐dispersion. Moreover, we establish a result of null controllability for the linear equation via the left Dirichlet boundary condition, and of exact controllability via both Dirichlet boundary conditions. As a consequence, we obtain some local exact controllability results for the nonlinear KdV equation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the choice of initial conditions of difference schemes for parabolic equations
Authors: Berikelashvili Givi , Gupta Murli M. , Muskhelishvili N. 
Published: December 2008

AbstractWe study finite difference schemes to approximate the first initial‐boundary value problem for linear second order parabolic equations and obtain some convergence rate estimates. When difference schemes are constructed for such problems, in the process of obtaining convergence rate estimates compatible with smoothness of the solution, various authors assume that the solution of the problem can be extended to the exterior of the domain of integration, preserving the Sobolev class. Our investigations show that this restriction can be removed if, instead of using the exact initial condition, we use certain approximations of the initial conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The stopping and starting problem in the model with jumps
Authors: Hamadene S. , Hdhiri I. 
Published: December 2008

AbstractWe consider the problem of optimal two modes switching in finite horizon in the model with jumps. We first give a verification theorem to shape the problem and later we show that it is satisfied. Finally when randomness comes from a diffusion process we study the the associated PDI variational inequalities with inter‐connected obstacles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling the viscoelasticity of cell shape changes
Authors: Hosking Roger J. , Husain Saiful A. 
Published: December 2008

AbstractIn the theory of linear viscoelasticity, creep and relaxation functions are the important delay kernels in the stress‐strain relations. Quite recently, a creep function power law has been obtained experimentally for an isolated living cell (on the scale of the cell). The corresponding form of the relaxation function is derived using the interconversion formula. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulations of flows in an elastic cylinder with two chambers
Authors: Lee Sunmi , Jung Eunok 
Published: December 2008

AbstractWe present a mathematical model of valveless pumping in a tube with two elastic chambers, which are motivated by the Liebau's two‐tank model. The tube consists of partially soft and partially (almost) rigid. We employ a two‐dimensional model using the immersed boundary method. In this new model, we have showed the important features of valveless pumping as the previous experiments and mathematical models have been discovered. For instance, we have observed that the direction and the amount of a net flow are sensitively dependent on the pumping frequency. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carr's randomization for American options in regime‐switching models
Authors: Boyarchenko S. , Levendorskiĭ S. 
Published: December 2008

AbstractIn the paper, we solve the pricing problem for American put‐like options in Markov‐modulated Lévy models. The early exercise boundaries and prices are calculated using a generalization of Carr's randomization for regime‐switching models. An efficient iteration pricing procedure is developed. The computational time is of order m2, where m is the number of states, and of order m, if the parallel computations are allowed. The payoffs, riskless rates and class of Lévy processes may depend on a state. Special cases are stochastic volatility models and models with stochastic interest rate; both must be modelled as finite‐state Markov chains. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fitting TAR(1) models to Sheperd data
Authors: Lindström Torsten 
Published: December 2008

AbstractA number of results that will be reported in detail elsewhere are outlined. The fundamental results are that typical models fitted to data of nonlinear mechanistic models possess non‐standard bifurcation routes and they in essential cases fit repellers to attractors of the true mechanistic map. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal design and optimal damping set for a hyperbolic problem (Poster Presentation)
Authors: Maestre Faustino , Münch Arnaud , Pedregal Pablo 
Published: December 2008

AbstractIn this work we analyze a 2D optimal design problem governed by a linear damped 1D wave equation. In this we would like to find simultaneously the spatio‐temporal layout of two isotropic materials of constants α and β (0 < α < β) and the static position of a damping set in order to minimize certain functional ([5]). By means of the gradient Young measures, we compute a full relaxation of the problem which is justified by the presence of microstructures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On conditions of flutter onset for elongated plate in supersonic gas flow
Authors: Loginov Boris , Makeev Oleg 
Published: December 2008

AbstractThe scheme developed in [1] of the investigation of Poincaré–Andronov‐Hopf bifurcation on the base of the Lyapounov‐Schmidt method is applied to two boundary value problems for nonlinear ordinary differential equation describing the oscillations of an elongated plate in supersonic gas flow. Necessary conditions for the existence of periodic solutions are obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluating the impact of average cost based contracts on the industrial sector in the European emission trading scheme
Authors: Oggioni Giorgia , Smeers Yves 
Published: December 2008

AbstractThe degradation of the competitiveness of part of the European industry is progressively emerging as one of the possible consequences of the combination of the European Emission Trading Scheme (EU‐ETS) and the restructuring of the electricity sector. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal trajectories which are tangent to an affine distribution
Authors: Popescu Mihai , Pelletier Fernand 
Published: December 2008

AbstractIn this work we study the trajectories which are tangent to an affine sub‐bundle in the tangent bundle of a manifold and which minimize the “total energy”.We give some characterizations of such “regular” trajectories in terms of control theory and geometrical theory. We also build some sufficient conditions of existence for such curves. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cournot Duopoly with competition in the R&D expenditures
Authors: Pinto Alberto A. , Ferreira Fernanda A. , Ferreira Miguel , Oliveira Bruno M.P.M. 
Published: December 2008

AbstractWe present a new R&D investment in a Cournot Duopoly model and we analyze the different possible types of Nash R&D investments. We observe that the new production costs region can be decomposed in three economical regions, depending on the Nash R&D investment, showing the relevance of the use of patents in new technologies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A second‐order accurate method for solving the eikonal equation
Authors: Schwartz Peter , Colella Phil 
Published: December 2008

AbstractWe present a numerical method for computing the signed distance to a piecewise‐smooth surface defined as the zero set of a function. It is based on a marching method by Kim and a hybrid discretization of first‐ and second‐order discretizations of the eikonal equation. If the solution is smooth at a point and at all of the points in the domain of dependence of that point, the solution is second‐order accurate; otherwise, the method is first‐order accurate, and computes the computes the correct entropy solution in the presence of kinks in the initial surface. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational approach to the cost analysis of dual machine interference model with general arrival distribution
Authors: Mishra S.S. 
Published: December 2008

AbstractIn this paper, a fresh attempt has been made to apply a computational approach to obtain the optimal total cost of the system as an important performance measure for the machine interference model with general arrival distribution. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On portfolio optimization using fuzzy decisions
Authors: Sudradjat Supian , Preda Vasile 
Published: December 2008

AbstractWe consider stochastic optimization problems involving stochastic dominance constraints. We develop portfolio optimization model involving stochastic dominance constrains using fuzzy decisions and we concentrate on fuzzy linear programming problems with only fuzzy technological coefficients and aplication/implementation of modified subgradient method to fuzy linear programming problems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bifurcation of the positive solutions to Henon equation
Authors: Yang Zhonghua , Li Zhaoxiang 
Published: December 2008

AbstractThree algorithms based on the bifurcation method is applied to solving the D4 symmetric positive solutions to the boundary value problem of = Henon equation. Taking r in Henon equation as a bifurcation parameter, the D4 – ∑d (D4 – ∑1, D4 – ∑2) symmetry‐breaking bifurcation point on the branch of the D4 symmetric positive solutions is found via the extended systems. Finally, ∑d (∑1, ∑2) symmetric positive solutions = are computed by the branch switching method based on the Liapunov‐Schmidt reduction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Receptivity of the boundary layer with separation bubble to external sound waves
Authors: Zametaev V.B. , Kravtsova M.A. 
Published: December 2008

AbstractThe receptivity problem of laminar separated two‐dimensional boundary‐layer under influence of external acoustic waves is considered. Basic features of this theory were formulated by Ruban (1984) and then Goldstein (1985), but these investigations were limited by small perturbations of steady parallel flow only. The current paper takes into account essentially nonparallel regimes of base flow, including attached flows, flow with separated bubbles and the base flow at marginal value of parameter. The steady flow near a corner point of profile is of considerable interest and a question naturally arises about the sensitivity of separation bubble inside the boundary layer to external disturbances such as sound waves. Another question arises about the sensitivity of near critical base flow, namely if corner is concave there is a marginal angle which limits existence of such base flow. This fact usually is linked with sudden reconstruction of full flow pattern past a profile. Development of perturbations inside the interaction region may give some answers about the appearance of turbulence. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Work‐roll surface degradation due to spalling of oxide layer
Authors: Zhang Wenge , Krempaszky Christian , Werner Ewald 
Published: December 2008

AbstractSurface damage of work‐rolls in hot strip rolling mills is often associated with the local removal of the oxide layer developing in service. A simple thermomechanical stress analysis in combination with an estimated buckling stress shows that the size of oxide free spots on the roll surface is roughly the same as the lateral distance between the cracks in the observed crack pattern. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large‐Eddy simulation of film cooling: treatment of inlet boundary conditions for the isobaric plenum and instantaneous vortex structures
Authors: Ziefle Jörg , Kleiser Leonhard 
Published: December 2008

AbstractWe present large‐eddy simulation (LES) results of a jet‐in‐crossflow configuration that was previously investigated in the experiments of Sinha et al. (J. Turbomach., Vol. 113, 1991). In this film‐cooling setup, relatively cool air is ejected from a large isobaric plenum through an oblique round nozzle into a hotter turbulent boundary layer. In accordance with typical film‐cooling conditions, the jet‐to‐crossflow velocity and temperature ratios were chosen as 0.25 and 0.5, respectively (defined with bulk quantities for the jet and freestream quantities for the boundary layer). The numerical simulations are performed with the compressible finite‐volume flow solver for structured multi‐block grids NSMB. The approximate‐deconvolution subgrid‐scale model (ADM) accounts for the non‐resolved scales. The problem of the unknown plenum pressure is handled by a combination of a sponge region with a non‐reflecting boundary condition at the plenum inlet. For computational economy, the turbulent boundary layer of the experiment is replaced by a steady mean turbulent inflow profile. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse homogenization with diagonal Padé approximants
Authors: Cherkaev Elena 
Published: December 2008

AbstractThe paper formulates inverse homogenization problem as a problem of recovery of Markov function using diagonal Padé approximants. Inverse homogenization or de‐homogenization problem is a problem of deriving information about the micro‐geometry of composite material from its effective properties. The approach is based on reconstruction of the spectral measure in the analytic Stieltjes representation of the effective tensor of two‐component composite. This representation relates the n‐point correlation functions of the microstructure to the moments of the spectral measure, which contains all information about the microgeometry. The problem of identification of the spectral function from effective measurements in an interval of frequency has a unique solution. The problem is formulated as an optimization problem which results in diagonal Padé approximation and exact formulas for the moments of the measure. The reconstructed spectral function can be used to evaluate geometric parameters of the structure and to compute other effective parameters of the same composite; this gives solution to the problem of coupling of different effective properties of a two‐component composite material with random microstructure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)