bluuebunny/crossref_metadata_2025_split huggingface dataset:
Singularities for dynamical arrest in disordered systems
Authors: Sperl Matthias 
Published: December 2008

AbstractIt will be shown how attraction and repulsion among interacting particles can lead to rich dynamical scenarios including glass transitions, gel transitions, and glass‐glass transitions. The transition diagram is explained by the topologically stable singularities of the Aℓ hierarchy. These singularities arise from the microscopic equations of motion and allow for asymptotic solutions. Close to glass‐glass transitions asymptotic solutions are identified in results from computer simulation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fatigue life investigation using non‐destructive testing methods
Authors: Stanković Z. , Bruhns O.T. 
Published: December 2008

AbstractExperimental investigations of the fatigue life prediction of two different specimen forms made from steel 42CrMo4 are described. The fatigue load is defined as a cyclic loading with constant and non constant amplitudes in tension range and with different stress ratios. This loading range leads to a high cyclic fatigue behaviour of both specimens. During the test, the growth of the fatigue crack is monitored using two different non‐destructive methods, namely acoustic emission and the electric resistance. The acoustic emission is used for detecting sound waves as a result of dissipation of elastic energy during microcracks and cracks growth, as well as for the detection of the place of crack initiation. The electric resistance is used for the monitoring and quantitative investigation of the crack growth. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some Bregman distances between financial diffusion processes
Authors: Stummer Wolfgang 
Published: December 2008

AbstractWe introduce Bregman distances between general probability measures, and discuss some link with Csiszar divergences. From this, we derive bounds on particular Bregman distances between non–lognormally distributed financial diffusion processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exact solution for a Stefan problem with convective boundary condition and density jump
Authors: Tarzia Domingo A. 
Published: December 2008

AbstractWe consider the solidification of a semi‐infinite material which is initially at its liquid phase at a uniform temperature Ti. Suddenly at time t > 0 the fixed face x = 0 is submitted to a convective cooling condition with a time‐dependent heat transfer coefficient of the type H (t) = ht–1/2 (h > 0) The bulk temperature of the liquid at a large distance from the solid‐liquid interface is T∞, a constant temperature such that T∞ < Tf < Ti where Tf is the freezing temperature. We also consider the density jump between the two phases. We obtain that the corresponding phase‐change (solidification) process has an explicit solution of a similarity type for the temperature of both phases and the solid‐liquid interface, if and only if the coefficient h is large enough, that is where kl and αl are the conductivity and diffusion coefficients of the initial liquid phase. Moreover, when h ≤ h0 we only have a heat conduction problem for the initial liquid phase and the corresponding change of phase does not occur. We do the mathematical analysis of a problem which was presented in S.M. Zubair – M.A. Chaudhry, Wärme‐und‐Stoffübertragung, 30 (1994), 77‐81 and we generalized the results obtained in D.A. Tarzia, MAT‐Serie A, 8 (2004), 21‐27 when the density jump between the two phases was neglected. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some remarks on index of matrix singular integral operators in non‐smooth domains
Authors: Vasilyev V.B. 
Published: December 2008

AbstractOn manifolds with non‐smooth boundaries the Mikhlin‐Calderon‐Zygmund operators with a matrix symbol are considered. The Noetherian property conditions (wave factorization) and reduction to Atiyah‐Singer theorem are described. These results were obtained through joint work with I.V. Scherbenko. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lattice‐Boltzmann model for dissolution phenomena
Authors: Verhaeghe Frederik , Arnout Sander , Blanpain Bart , Wollants Patrick 
Published: December 2008

AbstractWe briefly review the modelling of complex dissolution phenomena using a lattice Boltzmann formulation. The model can describe both diffusion‐ and reaction‐controlled dissolution of arbitrarily shaped solid phases, possibly giving rise to thermosolutal natural convection. Applications of the model are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weak solutions and attractors for motion equations for an objective model of viscoelastic medium
Authors: Vorotnikov Dmitry , Zvyagin Victor 
Published: December 2008

AbstractWe study the boundary value problem for the equations of motion of incompressible viscoelastic medium with an objective constitutive law of Jeffreys kind. We show existence of global weak solutions for any initial data and construct their minimal uniform trajectory attractor and uniform global attractor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On gradient methods for maximum entropy regularizing retrieval of atmospheric aerosol particle size distribution function
Authors: Wang Yanfei , Kuenzer Claudia 
Published: December 2008

AbstractThe determination of the aerosol particle size distribution function using the particle spectrum extinction equation is an ill‐posed integral equation of the first kind, since as is known, we are often faced with limited or insufficient observations in remote sensing and the observations are contaminated. Physically, the particle size distribution is always nonnegative, and we are often faced with incomplete data. Therefore, the concept of maximum entropy from information theory and statistic mechanics can be used to counteract this problem of missing or erroneous data. Therefore, in this paper, we study the maximum entropy based regularization model and gradient methods for solving the corresponding optimization problem. Numerical tests are made for synthetic aerosol data to show the efficiency and feasibility of the proposed algorithms. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Invariant tori in perturbed three vortex motion
Authors: Blackmore Denis , Ting Lu , Knio Omar 
Published: December 2008

AbstractThe motion of three point vortices in an ideal fluid in a plane comprises a Hamiltonian dynamical system – one that is completely integrable, so it exhibits numerous periodic orbits, and quasiperiodic orbits on invariant tori. Certain perturbations of three vortex dynamics, such as three vortex motion in a half‐plane, are also Hamiltonian, but not completely integrable. Yet these perturbed systems may still have periodic trajectories and invariant tori close to those for the unperturbed dynamics.Extending recent work by the authors [4], invariant 2‐tori approximating those for the unperturbed system are located and analyzed using a combination of classical analysis, asymptotics, and Hamiltonian methods. It is shown that the results and approximation methods used are applicable to several perturbations of three vortex dynamics such as three vortices in a half‐plane, the restricted four vortex problem in the plane, and three coaxial vortex rings in 3‐space. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decision diagrams for the approximate analysis of Markov models
Authors: Ciardo Gianfranco 
Published: December 2008

AbstractDecision diagrams of various types can be used to encode the exact state space and transition rate matrix of large Markov models. However, the exact solution of such models still requires to store at least one real vector with one entry per reachable state, a formidable limitation to the practical use of these encodings. Thus, we discuss automatic techniques for the approximate computation of performance measures when the Markov model can be compactly encoded but not exactly solved. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear programming approaches in the multidisciplinary design optimization of a sailing yacht keel fin
Authors: Campana Emilio F. , Fasano Giovanni , Peri Daniele , Pinto Antonio 
Published: December 2008

AbstractWe consider the use of global optimization techniques for the minimization of a nonconvex function, arising from a Multidisciplinary Design Optimization problem of a ship. In ship design different disciplines must be often coupled, encompassing hydrodynamic and structural problems. This scenario requires the use of specific multidisciplinary formulations, where standard mathematical programming methods could be unsuitable. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Topological and dynamical properties of genetic and social networks
Authors: Liò Pietro 
Published: December 2008

AbstractTheoretical investigations of complex systems have provided statistical methodologies for the analysis of topological and dynamical properties of biological networks. We have compared the topology and cluster structures of the genes in plasmids and of the transcriptional network from three different studies on S. pombe cell cycle. The topology of the plasmid genes provides insights into the ecology of gene diffusion among bacterial species. We have used a phase and a clustering related parameters to gauge the level of inter‐connectivity around nodes in a transcriptional network. The analysis reveals genetic relationships at the boundaries of different cell cycle events. In human networks topological changes occur because of risk awareness, trust estimation i.e. the perception of the state of the other individuals (nodes). We found that this effect introduces a much richer dynamics. We show that for finite average network connectivity, there is always a value of risk perception that stops the epidemics. For scale‐free networks with diverging input connectivity, a linear perception cannot stop the epidemics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanics of complex bodies: comments on the unified modeling of active substructures
Authors: Mariano Paolo Maria 
Published: December 2008

AbstractBasic issues of the general model‐building framework of the mechanics of complex bodies are discussed. Attention is focused on the representation of the material elements, the conditions for the existence of ground states of elastic complex bodies and their consequences on the interpretation of the nature of the various balance laws occurring. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On dispersive stability of Hamiltonian systems on lattices
Authors: Patz Carsten 
Published: December 2008

AbstractWe study the long‐time dynamics of oscillations in lattices of infinitely many particles interacting via certain non‐linear potentials. The aim is to proof dispersive stability of such Hamiltonian systems analogously to results known for PDEs. To do so we first recapitulate the dynamics of linear Hamiltonian systems on an infinite chain and give optimal decay rates based on the dispersion relation. Based on this we proof that if the non‐linearity is weak enough, the non‐linear system shows a similar behaviour like its linearization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analytical modeling of active structural acoustic control
Authors: Ringwelski Stefan , Gabbert Ulrich 
Published: December 2008

AbstractSince the reduction of disturbing noise is highly important in industrial and civil engineering, much research and development has been done in this field over the past decades. The application of smart structures provides a way to reduce unwanted noise radiation. A smart structure is an integrated system consisting of the passive base structure attached with actuators and sensors. Piezoelectric ceramics are widely used as sensors and actuators, because they can easily be bonded on or imbedded into conventional structures. An often used concept for noise reduction is active structural acoustic control (ASAC). This concept means that the noise radiation will be reduced by minimizing or changing the vibrational behavior of a structure using additional actuator forces. The development and industrial use of smart structures for ASAC requires efficient and reliable simulation and design tools. Usually the design process of smart structures is based on numerical methods. In order to verify numerical techniques, the paper presents an analytical reference solution for an ASAC system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Returns of Eastern European financial markets:α ‐stable distributions, measures of risk
Authors: Serbinenko Anna , Emmenegger Jean‐François 
Published: December 2008

AbstractThe daily returns of financial market indices of nineteen Eastern European countries are modelled, linear trend or ARMA(p, q) for the levels and GARCH(p ′, q ′) for the residuals. For the non Gaussian residuals ‐stable distributions are proposed. Then, risk measures, like the STARR and the R‐ratio are used to analyse the risk in the cases of Gaussian and ‐stable distribution models of the residuals. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The equilibrium shape of an elastic developable Möbius strip
Authors: Starostin E.L. , van der Heijden G.H.M. 
Published: December 2008

AbstractA variational geometrical approach is applied to find the characteristic shape of the Möbius strip made of an inextensible rectangular sheet. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite element discretization of parabolic‐elliptic interface problems
Authors: Stiemer Marcus 
Published: December 2008

AbstractWe consider mixed boundary value problems for partial differential equations which are parabolic in one part of the underlying domain and elliptic in another part. Such problems arise in eddy current simulations in electromagnetics. A fully discrete scheme for the numerical solution of such problems is presented. Particularly, adaptivity in space and time is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boundary integral equations and maximum modulus estimates for the Stokes system
Authors: Varnhorn Werner 
Published: December 2008

AbstractA maximum modulus estimate for the Stokes system in bounded domains of ℝn (n ≥ 2) is established via methods of hydrodynamical potential theory. The method is based on the unique solvability of the boundary integral equations' system resulting from the double layer potential ansatz together with a projection onto the normal field on the boundary. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bearing of geometric and material properties to bone strength in bending
Authors: Winter Werner 
Published: December 2008

AbstractOsteoporosis is characterized by decreasing of bone mass and bone strength with advanced age. For characterization of material properties of bone the volumetric bone mineral density is one of the most important contributing factors to bone strength. Often bending tests of whole bone are used to get information about the state of osteoporosis. From an uniaxial test of a bone specimen it is assumed that an elastic region exists up to initial yield stress and a following hardening region. In bending tests beside material properties geometric properties like shape and cortical thickness appropriate the non‐linear moment‐curvature curve. The aim of this contribution is to show how an elastic‐plastic material law including tensile damage influences the global bending behavior. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic stall measurements on airfoils
Authors: Wolken‐Möhlmann Gerrit , Barth Stephan , Peinke Joachim 
Published: December 2008

AbstractWe present a new method for measuring the lift forces acting on an airfoil segment under dynamic stall conditions. Thereby the pressure distribution over the wind tunnel walls is detected by an adequate number of pressure sensors. The airfoil is rotated by a stepping motor with angular velocities up to 300°/s. Measurements with Reynolds number up to Re = 700 000 can be performed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy‐momentum conserving integration of parallel manipulators
Authors: Uhlar Stefan , Betsch Peter 
Published: December 2008

AbstractIn the framework of a rotationless formulation for multibody systems, we present an investigation of multibody mechanisms. The benefit of this kind of formulation is the design of energy‐momentum conserving integration schemes, which facilitate a stable numerical integration of differential algebraic equations governing the motion of open‐loop and closed‐loop systems.We introduce a coordinate augmentation technique for the incorporation of rotational degrees of freedom and subsequently perform a size‐reduction to lower the computational costs and to improve the numerical conditioning [1]. Furthermore the treatment of nonholonomic constraints is addressed [3]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chebyshev expansion for the component functions of the almost‐Mathieu operator
Authors: Marrero Jesús C. Abderramán 
Published: December 2008

AbstractThe component functions {Ψn (ε)} (n 2 Z+) from difference Schrödinger operators, can be formulated in a second order linear difference equation. Then the Harper equation, associated to almost‐Mathieu operator, is a prototypical example. Its spectral behavior is amazing. Here, due the cosine coefficient in Harper equation, the component functions are expanded in a Chebyshev series of first kind, Tn (cos 2πθ). It permits us a particular method for the θ variable separation. Thus, component functions can be expressed as an inner product,
equation image
(cos 2πθ) ·
equation image
. A matrix block transference method is applied for the calculation of the vector
equation image
. When θ is integer, {Ψn (ε) is the sum of component from
equation image
. The complete family of Chebyshev Polynomials can be generated, with fit initial conditions. The continuous spectrum is one band with Lebesgue measure equal to 4. When θ is not integer the inner product Ψn can be seen as a perturbation of vector
equation image
on the sum of components from the vector
equation image
. When
equation image
, with p and q coprime, periodic perturbation appears, the connected band from the integer case degenerates in q sub‐bands. When θ is irrational, ergodic perturbation produces that one band spectrum from integer case degenerates to a Cantor set. Lebesgue measure is Lσ = 4(1 – |λ|), 0 < |λ| ≤ 1. In this situation, the series solution becomes critical. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flow of viscoplastic materials through converging channels
Authors: Alexandrov Sergei , Lyamina Elena , Mishuris Gennady 
Published: December 2008

AbstractMany classical rigid perfectly/plastic solutions cannot be extended to more complicated rigid plastic materials, such as rigid plastic hardening materials and rigid viscoplastic materials. The present paper reveals sources of this difficulty in the case of flow of rigid viscoplastic material through infinite converging rough wedge‐shaped and axisymmetric channels. Two types of viscoplastic models without strain hardening are considered, with and with no saturation stress. The maximum friction law is adopted at the friction surface. Qualitative features of the solutions are compared to those occurring in compression of a rigid plastic layer between rough, parallel plates. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of pressure work on free convection flow along a vertical circular cone with suction and variable surface temperature
Authors: Alim M. A. , Alam Md. M. 
Published: December 2008

AbstractFree convection laminar flow from a vertical circular cone maintained a variable surface temperature with suction and pressure work effects has been investigated. The governing boundary layer equations are transformed into a non‐dimensional form and the resulting nonlinear system of partial differential equations are reduced to local non‐similarity equations. The governing non‐similarity equations are then solved numerically by implicit finite difference method together with Keller box scheme. Numerical results are presented in terms of velocity and temperature profiles of the fluid as well as the local skin‐friction coefficients and the local heat transfer rate for different values of Prandtl number Pr, suction parameter ξ, temperature gradient parameter n and the pressure work parameter ∈. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strong convergence for large bodies in micromagnetics
Authors: Carstensen Carsten , Praetorius Dirk , Boiger Wolfgang 
Published: December 2008

AbstractThe convexified Landau‐Lifshitz minimisation problem in micromagnetics leads to a degenerate variational problem. Therefore strong convergence of finite element approximations cannot be expected in general. This paper introduces a stabilised finite element discretisation which allows for the strong convergence of the discrete magnetisation fields with reduced convergence order for a uniaxial model problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applications of RBF collocation method to elliptic PDEs in an arbitrary domain by fictitious domain extensions
Authors: Chen Jiahn‐Horng 
Published: December 2008

AbstractA fictitious domain extension approach is introduced to study elliptic PDE's defined in arbitrary domains by the radial basis function (RBF) collocation method. In this approach, arbitrary physical geometries are extended to domains which are topologically rectangular. The solution domain is also extended to the fictitious area and assumed to satisfy the same governing equation in it and on its extended boundaries. The boundary conditions are still specified on the boundaries of the original physical domain. The problem in the extended domain becomes ill‐posed. However, it can be easily circumvented by the collocation method. We demonstrate that the solution can be directly obtained without domain decompositions and iterations. The new approach is simple, efficient and accurate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multimodel control approach for electrohydraulic servo systems
Authors: Hancu Olimpiu , Maties Vistrian , Balan Radu 
Published: December 2008

AbstractThe paper proposes a control design approach based on a multipoint linearization method for linear electro‐hydraulic servo systems. The nonlinear model of servo system is linearized around of operational points and Matlab environment is used to adjust the points distribution based on an errors estimation. These models are used to design an optimal controller which online modifies the feedback control parameters. Simulation and experimental results are provided to show the effectiveness of approach. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cardiac arrhythmias: dynamics and geometry
Authors: Holden Arun. V. , Benson Alan P. , Halley Graeme 
Published: December 2008

AbstractCardiac arrhythmia have been modelled by non‐linear wave process in excitable media. Here we explain the effect of size, geometry and heterogeneity in the heart. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)