bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel quasicontinuum method for the seamless transition from atomistic to continumm length scales and its application to nanoindentation of single‐crystalline materials
Authors: Eidel Bernhard , Stukowski Alex 
Published: August 2008

AbstractWe propose a novel fully nonlocal quasicontinuum (QC) approach which is based on two approximation steps, (i) the coarsegraining via kinematic constraints and (ii) the sampling of the energy in clusters along with summation rules. The present approach is closely related to the framework in [1] where forces instead of the energy is subject to sampling. Here, we show that only energy sampling strictly preserves the symmetry of atomic interactions whereas force sampling generally does not. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic instabilities in biological membranes
Authors: Campelo F. , Hernández‐Machado A. 
Published: August 2008

AbstractA phase‐field model for dealing with the elastic bending energies is studied in the context of dynamic instabilities in membranes. We use it to study curvature‐driven pearling instability in vesicles induced by the anchorage of amphophilic polymers on the membrane. Within this model, we obtain the morphological changes reported in the experimental literature. The formation of a homogeneous pearled structure is achieved by consequent pearling of an initial cylindrical tube from the tip. For high enough concentration of anchors, we show theoretically that the homogeneous pearled shape is energetically less favorable than an inhomogeneous one, with a large sphere connected to an array of smaller spheres. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel two‐factor forecasting model for fuzzy time series
Authors: Li Sheng‐Tun , Lin Su‐Yu , Cheng Yi‐Chung 
Published: August 2008

AbstractThe study of fuzzy time series has increasingly attracted much attention due to its salient capabilities of tackling vague and incomplete data. A variety of forecasting models have devoted to improving forecasting accuracy, however, the issue of partitioning intervals has rarely been investigated. Recently, we proposed a novel deterministic forecasting model to eliminate the major overhead of determining the k‐order issue in high‐order models. This paper presents a continued work with focusing on handling the interval partitioning issue by applying the fuzzy c‐means technology, which can take the distribution of data points into account and produce unequal‐sized intervals. In addition, the forecasting model is extended to allow process twofactor problems. The accuracy superiority of the proposed model is demonstrated by conducting two empirical experiments and comparison to other existing models. The reliability of the forecasting model is further justified by using a Monte Carlo simulation and box plots. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Active control of working machines seat suspension aimed at health protection against vibration
Authors: Maciejewski Igor 
Published: August 2008

AbstractThe paper presents the model and simulation of passive and active earth‐moving machines seat suspension. The object of the simulation is the visco‐elastic passive seat suspension with an air‐spring, hydraulic shock‐absorber and scissors guidance mechanism. Passive seat suspension amplifies the vibration amplitude at low frequency range of excitation signal (the resonance effect). In order to help the working machines operators against vibration, the active system with different control strategies is elaborated. Active system improves significantly the behavior of the seat suspension at low frequency excitation, with the most effectiveness obtained for the resonance frequency. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and simulation of fibrous biological tissues via discrete homogenization methods
Authors: Caillerie Denis , Milišić Vuk , Mourad Ayman , Raoult Annie 
Published: August 2008

AbstractThanks to their geometrical organization at the cell level, soft biological tissues can be modelled from the mechanical point of view as multidimensional networks of elastic bars. The length of the bars is supposed to be small with respect to the size of the macroscopic medium. We introduce a detailed description of the overall structure accounting both for the tensions due to the bars and for the moments between pairs of bars. Using quasi‐periodicity hypotheses, we apply a discrete homogenization technique, [1]. We derive a continuous homogenized mechanical law in the large transformation setting. We describe the basic principles of this approach that was first introduced in the cardiac modelling context in [2]. In a last step we present its implementation in a finite element framework. We comment some aspects of our numerical results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal treatment planning in radiotherapy based on Boltzmann transport calculations
Authors: Schäfer M. , Frank M. , Herty M. 
Published: August 2008

AbstractA Boltzmann transport model for dose calculation in radiation therapy is considered. We formulate an optimal control problem for the desired dose. We prove existence and uniqueness of a minimizer. Based on this model we derive optimality conditions. The PN discretization in angle of the full model is considered. We show that the PN approximation of the optimality system is in fact the optimality system of the PN approximation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Granular materials: Parameter identification and modelling of localisation problems
Authors: Avci O. , Ehlers W. 
Published: August 2008

AbstractThe prediction of landsliding requires an exact knowledge of the mechanical behaviour of granular materials. This kind of materials, e. g., sand, have a very complex deformation behaviour, which depend on the stress state and on the loading history. In this work, the deformation behaviour of the solid skeleton is characterised via homogeneous triaxial tests on dry sand specimens. Additionally, an appropriate elasto‐plastic material law to describe the solid skeleton in the frame of Theory of Porous Media (TPM) is used, which is implemented in the FE tool PANDAS. Furthermore, a single‐surface yield criterion with isotropic hardening, which limits the elastic domain, and a non‐associated plastic flow are employed.The determination of the material parameters of the linear elasticity law as well as the single‐surface yield criterion are based on test data of triaxial experiments. The material parameters are identified using a derivative‐based optimisation method (donlp2), which is coupled with PANDAS. Finally, a simulation of a benchmark test is presented to show shear band localisation effects, where the material behaviour is described by a triphasic porous media model based on the TPM, where the constituents are a deformable solid skeleton and two pore fluids, water and air. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An augmented LDG method for linear diffusion problems
Authors: Barrios Tomás P. , Bustinza Rommel 
Published: August 2008

AbstractIn this note we present a review of a stabilized discontinuous Galerkin method for elliptic problems in the plane with mixed boundary conditions. The stabilized scheme is obtained by adding suitable Galerkin least‐squares terms. The corresponding unique solvability and optimal rates of convergence, with respect to the h –version, are established by applying the wellknown Lax‐Milgram theorem, avoiding therefore the introduction of any lifting operator for the analysis. Furthermore, we include a reliable and efficient (up to high order terms) a posteriori error estimator. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Estimation of material properties of cancellous bone using multiscale FEM
Authors: Ilic S. , Hackl K. , Gilbert R. 
Published: August 2008

AbstractCancellous bone is a spongy type of bone with voids filled by blood marrow. Without much loss of generality it can be modeled as a material with periodic microstructure where overall parameters can be calculated using homogenization methods. Here the multiscale finite element method is applied and the assumed representative volume element (RVE) is a cube with solid frame and fluid core. From the point of view of the finite element method the RVE is a combination of solid and shell elements. As the acoustic excitation is considered, a complex stiffness matrix and complex displacements appear in the solution of the problem. Calculation of overall properties is repeated for different geometries of the solid frame. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the conditional moments method to multi‐layered anisotropic shells
Authors: Müller Wolfgang H. , Nazarenko Lidija , Wille Ralf 
Published: August 2008

AbstractIn this paper the so‐called Conditional Moments Method (CMM) is explained, which allows investigating the stress‐strain state of stochastic composites under externally applied loads. This technique is used to determine effective (homogenized) material properties and, in particular, preparatory measures are taken, which eventually will allow to assess the deformation behavior of tires. The tire shells are modeled as a rubber matrix strengthened by metal or cord fibers. For this reason general CMM results will be specialized to the case of ellipsoidal inclusions of arbitrary aspect ratios in a matrix of various stiffness. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A generalization of Cahn‐Hilliard inpainting for grayvalue images
Authors: Burger Martin , He Lin , Markowich Peter , Schönlieb Carola‐Bibiane 
Published: August 2008

AbstractThe Cahn‐Hilliard equation has its origin in material sciences and serves as a model for phase separation and phase coarsening in binary alloys. A new approach in the class of fourth order inpainting algorithms is inpainting of binary images using the Cahn‐Hilliard equation. We will present a generalization of this fourth order approach for grayvalue images. This is realized by using subgradients of the total variation functional within the flow, which leads to structure inpainting with smooth curvature of level sets. We will present some numerical examples for this approach and analytic results concerning existence and convergence of solutions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A mathematical model for lifetime prediction of lacquer‐paint coatings in sea water
Authors: Shevchuk Victor A. , Shevchuk Pavlo R. 
Published: August 2008

AbstractMain features of the mechanism of lacquer‐paint coatings destruction in sea water have been revealed. On this basis, a mathematical model has been developed and boundary value problems of mathematical physics have been formulated to calculate the determining processes on characteristic stages of coatings in sea water. The theoretical evaluation of coatings longevity depending on physical characteristics of the system has been made. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reliable safety analysis with continuous‐time models
Authors: Lin Youdong , Stadtherr Mark A. 
Published: August 2008

AbstractUsing a recently developed method for the guaranteed solution of interval‐valued ODE problems, we extend the regiontransition approach for process safety analysis to continuous‐time models. This makes it possible to identify, with certainty, regions of operating space that are safe, unsafe, or lead to off‐spec product. The analysis can be done in the presence of uncertain model parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical valuation of options under Kou's model
Authors: Toivanen Jari 
Published: August 2008

AbstractNumerical methods are developed for pricing European and American options under Kou's jump‐diffusion model which assumes the price of the underlying asset to behave like a geometrical Brownian motion with a drift and jumps whose size is log‐double‐exponentially distributed. The price of a European option is given by a partial integro‐differential equation (PIDE) while American options lead to a linear complementarity problem (LCP) with the same operator. Spatial differential operators are discretized using finite differences on nonuniform grids and time stepping is performed using the implicit Rannacher scheme. For the evaluation of the integral term easy to implement recursion formulas are derived which have optimal computational cost. When pricing European options the resulting dense linear systems are solved using a stationary iteration. Also for pricing American options similar iterations can be employed. A numerical experiment demonstrates that the described method is very efficient as accurate option prices can be computed in a few milliseconds on a PC. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On linear programming bounds for nets
Authors: Schmid Wolfgang Ch. , Trinker Horst 
Published: August 2008

AbstractIt is well known that there are close connections between low‐discrepancy point sets and sequences on the one hand, and certain combinatorial and algebraic structures on the other hand. E. g., Niederreiter [1] showed the equivalence between (t, t + 2, s)‐nets and orthogonal arrays of strength 2. Some years later this was generalized and made precise in the work of Lawrence [2] as well as Mullen and Schmid [3] by introducing ordered orthogonal arrays. This large class of combinatorial structures yields both new constructions and bounds for the existence of nets and sequences.The linear programming bound for ordered orthogonal arrays was first derived by Martin and Stinson [4]. As in the case of error‐correcting codes and orthogonal arrays, it yields a very strong bound for ordered orthogonal arrays, and consequently for nets and sequences.Solving linear programming problems in exact arithmetics is very time‐consuming. Using different approaches to reduce the computing time, we have calculated the linear programming bound for a wide parameter range. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Matching and stabilization of discrete mechanical systems
Authors: Bloch Anthony M. , Leok Melvin , Marsden Jerrold E. , Zenkov Dmitry V. 
Published: August 2008

AbstractControlled Lagrangian and matching techniques are developed for the stabilization of equilibria of discrete mechanical systems with symmetry as well as broken symmetry. Interesting new phenomena arise in the controlled Lagrangian approach in the discrete context that are not present in the continuous theory. Specifically, a nonconservative force that is necessary for matching in the discrete setting is introduced. The paper also discusses digital and model predictive controllers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stable deep‐water waves propagating in one and two dimensions
Authors: Henderson Diane , Segur Harvey 
Published: August 2008

AbstractDeep‐water, narrow‐banded wavetrains of uniform amplitude propagating in one horizontal dimension were shown to be unstable to small perturbations with nearly the same frequency and direction about 40 years ago. More recently, interactions of two narrow‐banded wavetrains of uniform amplitude propagating in arbitrary directions were shown to be similarly unstable. In both cases, the instabilities have been described by either a single nonlinear Schrödinger (NLS) equation or by two coupled NLS equations. However, the inclusion in these equations of any amount of damping (of a particular type) stabilizes the instabilities. Experiments show that the evolution of perturbed wavetrains in both cases is more accurately described by the NLS models that include damping when the amplitudes are small or moderate. When the amplitude of either the underlying waves or the perturbations is large, neither the undamped NLS model nor the damped NLS model accurately predicts the observed behaviour, which includes frequency downshifting. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical eigenmode analysis of an acoustic‐duct system by CFD‐OLTF and comparison against experiment
Authors: Neunert Urban , Kopitz Jan , Sattelmayer Thomas , Polifke Wolfgang 
Published: August 2008

AbstractIn this contribution, a novel approach to determine acoustic eigenmodes in duct systems is presented. The approach combines Computational fluid dynamics, classical Network models of duct acoustics and the Nyquist criterion known from control theory, and is therefore called CNN‐method. The method has been applied to a geometrically simple, but aero‐acoustically non‐trivial configuration – i.e. a sudden change in cross‐sectional area connecting two ducts with non‐zero mean flow – and validated against experimental data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal operation for a river fishway
Authors: Alvarez‐Vázquez L.J. , Martínez A. , Vázquez‐Méndez M.E. , Vilar M. 
Published: August 2008

AbstractIn this paper we present an optimal control problem related to the optimal management of a vertical slot fishway. We introduce the mathematical statement of the environmental problem, we derive an optimality condition for characterizing its optimal solutions, and we give an optimization algorithm for their numerical computation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse problems related to ion channels
Authors: Arning Kattrin , Burger Martin , Eisenberg Robert S. , Engl Heinz W. , He Lin 
Published: August 2008

AbstractIon channels are proteins with a hole down theirmiddle that allow ions to move across otherwise impermeable cellmembranes, thereby controlling many important physiological functions. The transport process of the ions can be described using the Poisson‐Nernst‐Plank equations, a system of coupled nonlinear partial differential equations. Based on this model we derive a simplified surrogate model that captures the main features of the associated current‐voltage curves of the ion channel. This surrogate model is then used to identify individual channel parameters based on current data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic spatial price equilibrium problem: regularity results and computational procedure
Authors: Barbagallo Annamaria 
Published: August 2008

AbstractIn this paper we consider the dynamic spatial price equilibrium problem and the associated evolutionary variational inequality. In particular the regularity of equilibrium solutions is studied and a method for solving the dynamic spatial price equilibrium problem is presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Subcritical instability of liquid metal channel flow in the presence of a spanwise magnetic field
Authors: Boeck Thomas , Krasnov Dmitry , Rossi Maurice , Zikanov Oleg 
Published: August 2008

AbstractThe linear and nonlinear evolution of perturbations is investigated in a magnetohydrodynamic channel flow with electrically insulating walls. The applied magnetic field is parallel to the walls and orthogonal to the stream. Linear optimal perturbations and their maximum amplifications over finite time intervals are computed using a scheme based on the direct and adjoint governing equations. It is shown that dominant optimal perturbations are no more the classical streamwise modes and how the flow is two‐dimenzionalized for high enough Hartmann numbers. For fixed Reynolds and Hartmann numbers, direct numerical simulations are applied to investigate how the transition to turbulence is affected by the magnetic field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Existence and multiplicity of solutions for elliptic problems with indefinite discontinuous nonlinearities
Authors: Calahorrano Marco 
Published: August 2008

AbstractIn this paper we study the critical points for a locally Lipschitz functional that in some sense will be solutions of an elliptic problem with indefinite discontinuous nonlinearities. We should mention that our results were inspired by the work of Ambrosetti‐Badiale [3], Arcoya‐Calahorrano [5], Alama‐Tarantello [1] and Chang [8]. For the problem studied in [3] we introduce indefinite nonlinearities as in [1] and [6]. To obtain the existence and multiplicity of solutions we use the critical points theory developed by Chang. Applications for Plasma Physics are considered with nonlinearities that change sign. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptives quadratures and fractional IDEs: Applications in image processing
Authors: Cuesta E. 
Published: August 2008

AbstractIn this paper we show adaptive time discretizations of a fractional integro–differential equation ∂αtu = Δu + f, where A is a linear operator in a complex Banach space X and ∂αt stands for the fractional time derivative, for 1 < α < 2. Some numerical illustrations are provided showing practical applications where the computational cost is one of drawbacks, e.g., some problems related to images processing. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constructive approximations of spherical functions
Authors: Ganesh M. , Mhaskar H. N. 
Published: August 2008

AbstractApproximation of functions on the sphere arises in almost all applications modeling data collected on the surface of the earth and for reconstruction of various processes in spherical coordinates. Constructive approximation of high dimensional spherical functions are useful for approximation of processes of several variables on a compact subset of a Euclidean space by mapping the data onto the unit sphere of a space having one higher dimension, avoiding the boundary effect of the set. Interpolation operators on the circle and periodic domains (based on a class of basis functions and data values) are essential for many high performance simulations. These operators are represented by analytical summation formulas that can be computed very efficiently using the fast Fourier transform. This work is concerned with construction of a similar class of interpolation and quasi‐interpolation operators on the unit sphere in ℝq , for q = 3, 4, 5, · · ·, using a new class of basis functions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐order ADI method for stream‐function vorticity equations
Authors: Karaa Samir 
Published: August 2008

AbstractMany recent works have demonstrated the efficiency of high‐order compact (HOC) difference schemes on the stream‐function and vorticity formulation of 2‐D incompressible Navier‐Stokes equations. HOC discretizations induce cross spatial derivatives which are treated explicitly in most ADI schemes. Recently, Karaa and Zhang proposed a fourth‐order ADImethod for solving convection‐diffusion problems efficiently. In this work, we extend this method to the solution of incompressible Navier‐Stokes equations. The driven flow in a square cavity is used as a model problem and numerical results are compared with other results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel methods of pulse wave diagnostics based on compression of a superficial artery
Authors: Kizilova Natalya 
Published: August 2008

AbstractPulse wave propagation and reflection in the branching systems of viscoelastic tubes and complex resistances as a model of arterial vasculature is considered. Axisymmetric wave motion of a viscous incompressible liquid in the system is investigated in application to the pressure and flow wave propagation in the system. Expression for the input admittance of the system taking into account wave reflection at the end of the tube is obtained. The dependence of the input admittance on the geometrical and mechanical parameters of the system is investigated. It is shown that the parameters of the pressure wave (the modules and phases of different harmonics) at the inlet of the system give information on the state (normal or pathological) of the inner organs. It is shown that after a proper compression (slight or deep) some harmonics can be amplified while the others are attenuated. Based on the theory of resonant harmonics of different inner organs the novel method of pulse wave palpation is proposed. The results are compared to some other methods as separation of the pressure wave into the forward and backward components, estimation of the parameters of the reflected wave and wave‐intensity analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)