bluuebunny/crossref_metadata_2025_split huggingface dataset:
A global approach of electromagnetism dedicated to further long‐term planning
Authors: Mazauric Vincent , Maïzi Nadia 
Published: August 2008

AbstractIn order to provide a vision of power electrical engineering for future energy‐supply crossroads and challenges, quasi‐static laws of electromagnetism are obtained from variational principles deduced from thermostatistics by assuming a trend for a reversible evolution of the electromagnetic field. The approach provides a multi‐scale framework suitable to derive electrodynamical properties, from scratch to the design level. The actual trend to which obeys the electromagnetic field provides a dynamic representation of the power transmission and gives an insight to introduce the level of reliability in a sustainable planning. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of microwave thawing using a coupled solver approach
Authors: Parrott A. K. , Tilford T. 
Published: August 2008

AbstractThawing of a frozen food product in a domestic microwave oven is numerically simulated using a coupled solver approach. The approach consists of a dedicated electromagnetic FDTD solver and a closely coupled UFVM multi‐physics package. Two overlapping numerical meshes are defined; the food material and container were meshed for heat transfer and phase change solution, whilst the microwave oven cavity and waveguide were meshed for the microwave irradiation. The two solution domains were linked using a cross‐mapping routine. This approach allowed the rotation of the food load to be captured. Power densities obtained on the structured FDTD mesh were interpolated onto the UFVM mesh for each timestep/turntable position. The UFVM solver utilised the power density data to advance the temperature and phase distribution solution. The temperature‐dependant dielectric and thermo‐physical properties of the food load were updated prior to revising the electromagnetic solution. Changes in thermal/electric properties associated with the phase transition were fully accounted for as well as heat losses from product to cavity. Two scenarios were investigated: a centric and eccentric placement on the turntable. Developing temperature fields predicted by the numerical solution are validated against experimentally obtained data. Presented results indicate the feasibility of fully coupled simulations of the microwave heating of a frozen product. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A modified nodal approach to circuit synthesis
Authors: Reis Timo 
Published: August 2008

AbstractGiven is a passive reciprocal descriptor system. The aim is to find an electrical circuit which has the same input‐outputbehaviour as the given descriptor system. A method is presented that leads to circuit equations in modified nodal analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integrated circuit design: dealing with variations
Authors: Schlichtmann Ulf , Graeb Helmut 
Published: August 2008

AbstractIn the following, a practicable methodology to analyze and optimize the yield of an electronic circuit, i.e. the percentage of manufactured circuits that satisfy the circuit specification, is formulated. It is based on a “spec‐wise” partitioning of the problem by considering each circuit specification bound individually, and on a geometric yield approximation. EDA tools following the described approach are available meanwhile. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A nonoverlapping domain decomposition method for nonlinear physical processes
Authors: Siahaan Antony , Lai Choi‐Hong , Pericleous Koulis 
Published: August 2008

AbstractA coupling technique for a nonoverlapping domain decomposition method is investigated in this paper. We test this method on a nonlinear heat conduction process taking place in a multi‐chip module which has many geometrically structured subdomains. The problem of interface condition between two adjacent subdomains is tackled by incorporating a defect equation which is solved iteratively. We evaluate two defect equations on this scheme, i.e. the difference of normal derivative and the residual of the heat conduction equation itself. Both equations lead to systems of nonlinear equations which are solved by means of quasi‐Newton methods with an adaptive alpha rate instead of a Jacobian matrix. The simulation suggests that the second defect equation is much more accurate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aerodynamic optimization of Laval nozzle flow with shocks: Numerical investigation of active/passive shock control via expansion fans
Authors: Al‐Hasan N.S. , Schnerr G.H. 
Published: August 2008

AbstractInstantaneous ignition in the supersonic part of a 3‐D Laval nozzle realized by a well‐defined sudden temperature rise across a normal shock is the focus of the present study. Unfortunately, the divergence of the supersonic nozzle part is necessarily smooth. Therefore, the turbulent boundary layer ahead of the shock is thick and causes substantial shock/boundary layer interactions. The non‐homogeneous temperature increase across the shock, caused by the boundary layer thickening ahead of the shock and the resulting pre‐compression prevents the quasi 1‐D evolution of the flow downstream. Additionally, due to multiple boundary layer interactions the single shock disintegrates into a so called pseudo‐shock system; i.e., into a sequence of periodic weak compression and expansion regions. To avoid this drawback and to establish homogeneous thermodynamic conditions throughout the entire cross section and flow domain downstream of the shock we apply active and passive control techniques in the area of shock boundary layer interaction. The central idea of the control technique described below is compensation of the thickening of the boundary layer by quantitative appropriate inverse effects, i.e. by superimposing negative and positive pressure gradients in the near wall region close to the shock position. In a first approach the additional expansion fan is created by active suction slots in flow direction and through all sidewalls of the 3‐D nozzle. The resulting shock remains straight with exception of the near wall region. Suction creates an effective concave wall curvature. In supersonic flow the resulting local expansion tends to compensate the pre‐compression. Because suction in high temperature environment is difficult to realize, we alter the wall curvature to create a negative bump with the same effect on the effective wall curvature. Under these conditions a normal shock in the channel core could be established without active or passive suction. The paper compares these active/passive control techniques with the unmodified setup. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
p ‐Sparse BEM for weakly singular integral equation with random data
Authors: Chernov Alexey 
Published: August 2008

AbstractWe consider the weakly singular boundary integral equation 𝒱u = g on a randomly perturbed smooth closed surface Γ(ω) with deterministic g or on a deterministic closed surface Γ with stochastic g (ω). The aim is the computation of the centered moments ℳ︁k u, k ⩾ 1, if the corresponding moments of the perturbation are known. The problem on the stochastic surface is reduced to a problem on the nominal deterministic surface Γ with the random perturbation parameter κ (ω).Resulting formulation for the k th moment is posed in the tensor product Sobolev spaces and involve the k ‐fold tensor product operators. The standard full tensor product Galerkin BEM requires 𝒪(Nk) unknowns for the k th moment problem, where N is the number of unknowns needed to discretize the nominal surface Γ. Based on [1], we develop the p ‐sparse grid Galerkin BEM to reduce the number of unknowns to 𝒪(N (log N)k –1) (cf. [2], [3] for the wavelet approach). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Using divergence‐free and curl‐free wavelets for the simulation of turbulent flows
Authors: Deriaz Erwan , Perrier Valérie 
Published: August 2008

AbstractWe present a numerical method based on divergence‐free and curl‐free wavelets to solve the incompressible Navier‐Stokes equations. We introduce a new scheme which uses anisotropic divergence‐free wavelets for the decomposition of the velocity, and which only needs Fast Wavelet Transform algorithms. Numerical results finally show the feasibility of the method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational approach to formation of misoriented microstructures in plastic deformation
Authors: Sedláček Radan , Kratochvíl Jan , Kružík Martin , Nachname Vorname 
Published: August 2008

AbstractThe formation of misoriented microstructures in plastic deformation is explained within the framework of continuum mechanics as a result of the reduction of the energetically costly hardening in multislip by local lattice rotations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Convergence of boundary optimal controls in mixed elliptic problems
Authors: Gariboldi Claudia M. , Tarzia Domingo A. 
Published: August 2008

AbstractWe consider a steady‐state heat conduction problem Pα withmixed boundary conditions for the Poisson equation in a bounded multidimensional domain Ω depending of a positive parameter α which represents the heat transfer coefficient on a portion Γ1 of the boundary of Ω. We consider, for each α > 0, a cost function Jα and we formulate boundary optimal control problems with restrictions over the heat flux q on a complementary portion Γ2 of the boundary of Ω. We obtain that the optimality conditions are given by a complementary free boundary problem in Γ2 in terms of the adjoint state. We prove that the optimal control q and its corresponding system state u and adjoint state p for each α are strongly convergent to qop, u and p in L2(Γ2), H1(Ω), and H1(Ω) respectively when α → ∞. We also prove that these limit functions are respectively the optimal control, the system state and the adjoint state corresponding to another boundary optimal control problem with restrictions for the same Poisson equation with a different boundary condition on the portion Γ1. We use the elliptic variational inequality theory in order to prove all the strong convergences. In this paper, we generalize the convergence result obtained in Ben Belgacem‐El Fekih‐Metoui, ESAIM:M2AN, 37 (2003), 833‐850 by considering boundary optimal control problems with restrictions on the heat flux q defined on Γ2 and the parameter α (which goes to infinity) is defined on Γ1. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Convergence rate for the Bayesian inversion theory
Authors: Neubauer Andreas , Pikkarainen Hanna K. 
Published: August 2008

AbstractRecently, the metrics of Ky Fan and Prokhorov were introduced as a tool for studying convergence of regularization methods for stochastic ill‐posed problems. In this work, we examine the Bayesian approach to linear inverse problems in this new framework. We consider the finite‐dimensional case where the measurements are disturbed by an additive normal noise and the prior distribution is normal. A convergence rate result for the posterior distribution is obtained when the covariance matrices are proportional to the identity matrix. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Minimum integrated altitude for the terminal bunt manoeuvre
Authors: Subchan S. 
Published: August 2008

AbstractThis paper presents trajectory shaping of a surface‐to‐surface missile attacking a fixed target with varying flight‐path angle. The problem is reinterpreted using optimal control theory resulting in the formulation of minimum integrated altitude. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free‐boundary models of sulphation
Authors: Clarelli Fabrizio , Fasano Antonio , Natalini Roberto 
Published: August 2008

AbstractAir pollution is the most serious cause of degradation of carbonate stones, which constitute, as marble, travertine or other limestones, some of the most important monuments and artifacts in the world. Mathematicians have now begun to model the degradation problem to assist people working in protection and restoration of these stones. Here, a free boundary model is presented, which describes the growth of a gypsum crust on the surface of marble monuments under SO2 aggression, and quantifies the influence of environmental factors such as pollutant concentration, humidity and temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The use of hybrid techniques at CERFACS for the solution of large problems on parallel machines
Authors: Duff Iain S. 
Published: August 2008

AbstractCurrent problems in scientific computing often require the solution of sets of sparse linear equations of very large order. Particularly for three dimensional problems, it may to be impractical to solve them using a direct method but equally iterative methods may not converge and often standard preconditioning techniques do not work.We thus propose using a hybrid method by which we mean that either a nearby problem or a subproblem is solved by a direct method with the overall problem being solved by an iterative method. We discuss two applications of this at CERFACS in the solution of large scale problems from industry. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of symbolical kinematics for the efficient solution of force workspace of excavators
Authors: Flores Francisco Geu , Kecskeméthy Andrés , Pöettker Alois 
Published: August 2008

AbstractThis paper describes a method for the efficient determination of maximally allowed shovel forces for a heavy‐load faceshovel excavator through its workspace, based on the concept of “kinematical transformers”. In this concept, each multibody loop is regarded as a transmission element coupled by linear equations with the other multibody loops, allowing an efficient detection of closed‐form kinematical solutions. Additionally, the method uses a graphical optimization approach to find the maximal digging forces for given positions of the shovel. An application‐specific code has been realized using a combination of the object‐oriented multibody library MBILE and symbolical equations. The method is applied to existing heavy‐load excavators, showing that by the use of symbolical kinematics, the computational effort can be reduced substantially. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Material dispersion in dynamic deformation process of solids under impact action
Authors: Glema Adam 
Published: August 2008

AbstractThe dispersion phenomenon is studied to introduce the adequate material model for the advanced states of dynamic deformation processes. The evolution problem is formulated within the frame of theory of thermodynamics and viscoplasticity. Mathematical analysis for elastic, plastic and viscoplastic material evidence the non‐dispersive or dispersive property. Occurrence of dispersion in the analysis problem has the consequences not only for constitutive relation. It influences the whole problem with advantages in formulation and solution. Numerical results of example problems present qualitatively different mechanical response for materials with different dispersion. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Propagation of high intensity light in semiconductors
Authors: Gonzalez L. P. , Guha S. , Sheng Q. 
Published: August 2008

AbstractFor photons of energy below the bandgap energy, semiconductors exhibit high transparency and low irradiance light passes freely through the medium. However, for high irradiances of light, as from a laser, the transmission through the semiconductor becomes nonlinear. As the irradiance of the incident light increases, the transmission through the semiconductor decreases through nonlinear absorption as well as from the generation of free carriers during the laser pulse. The propagation of light through this irradiance dependent medium can be described by a set of coupled, inhomogeneous, partial differential equations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal operational loads for distributed cogeneration power plants
Authors: Maïzi Nadia , Bordier Marc 
Published: August 2008

AbstractThe purpose of this paper is to determine the operating mode of a cogeneration system that minimises its overall cost of operation. The optimisation procedure is achieved in two steps:• First, we consider a single unit and we develop a convex but non differentiable formulation for the operating cost. Furthermore an explicit expression for the optimal operational mode parametrized with heat and power consumer demand and with electricity market price, is obtained;• Then, we express for the distributed cogeneration system the overall operating cost. This objective function is still convex and non differentiable and the optimisation procedure requires subdifferential calculus, via the Moreau‐Rockafellar and the Duboviskii‐Milyutin theorems [1].The final result describing the best operating mode for the overall set of cogeneration units relies on the ordered sequence of marginal costs associated with the different operational modes for each unit. It indicates that the optimal operation of the distributed cogeneration system is achieved through an economic dispatch mode. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the design of low‐thrust transfers through L1 for the ESMO mission
Authors: Novak Daniel , Heiligers Jeannette , Vasile Massimiliano 
Published: August 2008

AbstractThe following paper summarises the mission analysis studies performed for the phase A of the solar electric propulsion option of the European Student Moon Orbiter (ESMO) mission. ESMO is scheduled to be launched in 2011, as an auxiliary payload on board an Ariane 5. Hence the lack of influence on the launch date. Two methods were devised to assess efficiently wide launch windows for the Earth‐Moon transfer, they are presented below. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A remark on the finite number of particles effect in Monte Carlo methods for kinetic equations
Authors: Dimarco Giacomo , Foscari Piero , Pareschi Lorenzo 
Published: August 2008

AbstractMonte Carlo methods are the most popular methods for solving problems in kinetic theory [2, 5]. In this short remark we emphasize some of the side effects due to the use of conservative methods over a finite number of statistical samples (particles) in the simulation. The most relevant aspect is that the steady states of the system are compactly supported and thus they cannot be Maxwellian (or any other non compactly supported statistics) unless the number of particles goes to infinity. These aspects are studied numerically with the help of a simple one‐dimensional space homogeneous kinetic model. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Construction of digital nets based on propagation rules for OOAs
Authors: Schürer Rudolf 
Published: August 2008

Abstract(t,m,s)‐nets are a powerful tool for the generation of low‐discrepancy point sets. We find nets with improved parameters using a coding‐theoretic approach, starting with an orthogonal array (dual of a linear code) and embedding it in a net. The innovation of our approach is that propagation rules for OOAs are applied halfway through the embedding process. To this end many propagation rules have been generalized from the setting of orthogonal arrays to OOAs.According to MinT [1], the online database of (t,m,s)‐net parameters at mint.sbg.ac.at, more than 100 nets with previously unknown parameters have been found using this method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A complete flux scheme for the stationary advection‐diffusion‐reaction equation
Authors: ten Thije Boonkkamp J.H.M. 
Published: August 2008

AbstractExpressions for the numerical flux of a conservation law of advection‐diffusion‐reaction type are derived from a local solution of the entire conservation law, including the source term. The resulting complete flux scheme is given for one‐dimensional (in Cartesian and spherical coordinates) and two‐dimensional model equations. Combined with a finite volume method, the numerical scheme is second order accurate, uniformly in the Peclet numbers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On‐pump modular systemfor automated adjustment and control for axial piston pumps
Authors: Vaida L. , Nascutiu L. , Vaida C. , Pisla D. , Itul T. , Pisla A. 
Published: August 2008

AbstractAxial piston pumps are the most widely used pumps in hydraulic actuation systems. Their technical characteristics make them the best option for most applications starting from industrial machine tools, up to mobile equipments. Thus, the optimization of their functional parameters and their control within the system is of great importance [1], [4]. The paper presents the construction of a modular measuring and control head (developed by the authors) mounted directly on the pump which ensures the automated achievement of any type of control: flow, pressure, power or their combinations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fractional variational principles and their applications
Authors: Baleanu Dumitru 
Published: August 2008

AbstractVariational calculus and fractional calculus have played a significant role in various areas of applied sciences such as, among others, Physics, Engineering and Economics. This topic is deeply connected to the very recent developments in theoretical aspects and especially in the numerical schemes of fractional differential equations. Based on 1+1 field formalism, a new fractional Lagrangian and Hamiltonian formalisms are presented within the Riemann‐Liouville fractional derivatives and the an‐harmonic oscillator is analyzed. This formalism can be applied to analyze the control problems as well as for the fractional quantization procedure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nondegenerate necessary conditions for nonlinear optimal control problems with higher‐index state constraints
Authors: Fontes Fernando A. C. C. , Lopes Sofia O. 
Published: August 2008

AbstractFor some optimal control problems with pathwise state constraints the standard versions of the necessary conditions of optimality are unable to provide useful information to select minimizers. There exist some literature on stronger forms of the maximum principle, the so‐called nondegenerate necessary conditions, that can be informative for those problems. These conditions can be applied when certain constraint qualifications are satisfied. However, when the state constraints have higher index (i.e. their first derivative with respect to time does not depend on the control) these nondegenerate necessary conditions cannot be used. This happens because constraint qualifications assumptions are never satisfied for higher index state constraints.We note that control problems with higher index state constraints arise frequently in practice. An example is a common mechanical systems for which there is a constraint on the position (an obstacle in the path, for example) and the control acts as a second derivative of the position (a force or acceleration) which is a typical case.Here, we provide a nondegenerate form of the necessary conditions that can be applied to nonlinear problems with higher index state constraints. When addressing a problem with a state constraint of indexk, the result described is applicable under a constraint qualification that involves thek‐th derivative of the state constraint, corresponding to the first time when derivative depends explicitly on the control. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Materials with graded coating under transverse loading
Authors: Guz Igor A. , Kashtalyan Maria , Menshykova Maryna 
Published: August 2008

AbstractIn the present paper 3‐D elastic deformation of a material with functionally graded coating subjected to mechanical loading is investigated. Comparative study of graded versus homogeneous coating is conducted to examine the effect of the stiffness gradient in the coating on stress and displacement fields in the material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)