bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial biomass in arable soils of Germany during the growth period of annual crops
Authors: Nieder Rolf , Harden Torsten , Martens Rainer , Kumar Benbi Dinesh
Published: August 2008

Results from several field studies involving numerous measurements were used to describe the change of soil microbial biomass C (Cmic) and N (Nmic) during the growth period of annual crops (years 1988–1992, 1994, 1995) under the temperate climatic conditions of central Europe. The data were taken from our own investigations as well as from the literature. Only studies with at least eight measurements on one plot during the growth period were used. The total number of farms (cash crop–production farms) was 7, that of experimental plots was 15. The evaluation of these results through regression analysis demonstrated that Cmic and Nmic from the beginning of a year increased only slightly until summer and subsequently decreased until autumn to their initial levels. This increase on an average corresponded to a C assimilation of approx. 100 kg ha–1 and an N immobilization of approx. 20 kg ha–1 (30 cm)–1. The increase in Nmic alone could not explain N immobilization rates frequently observed in different studies using 15N‐labeled fertilizers. Most of the labeled N that was immobilized (>50 kg N ha–1) might have accumulated in the matrix of soil organic matter (SOM). Therefore, the changes in microbial biomass may be of less importance for changes in soil N storage as frequently assumed.
Dendronized Polymers via Macromonomer Route in Supercritical Carbon Dioxide
Authors: Costa Liborio Ivano , Kasëmi Edis , Storti Giuseppe , Morbidelli Massimo , Walde Peter , Schlüter A. Dieter
Published: August 2008

Radical polymerizations from third to fifth generation macromonomers were conducted in supercritical carbon dioxide (scCO2). It was found that all monomers were not soluble in such a medium, and reactions occurred in the CO2‐swollen monomer matrices. Despite the expected severe diffusion limitations, very high conversions and molecular weights were obtained. It is believed that the plasticization effect induced by the CO2 plays a key role in these surprising findings. Scanning force microscopical analyses confirmed that mainly linear dendronized polymers were obtained and therefore chain transfer to polymer is virtually irrelevant.

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Polymer Crystallization Influenced by Initial Orientation of Cylindrical Diblock Copolymers in Thin Films
Authors: Yang Ping , Han Yanchun
Published: August 2008

The effect of the initial states (disordered perpendicular cylinder structure vs. parallel cylinder structure) on the crystallization of polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) thin films during cyclohexane annealing was investigated. The cylindrical domains perpendicular or parallel to the surface were obtained by controlling the film thickness. During solvent annealing, for the film with the perpendicular cylinders, the ordering degree of cylinders was increased. The enthalpic increase is large enough for the forming of square‐shaped crystals, and subsequently the square‐shaped single crystals surrounded by the ordered hexagonally packed perpendicular cylinders evolved to the dendrite ones. For the film with the parallel cylinders, the parallel cylinders were translated to the perpendicular ones. The increased enthalpy was not large enough for the formation of square‐shaped single crystals. Instead, the dendrite‐like crystals started at the edge of terraces.

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Salvage of amputated thumbs by temporary ectopic implantation
Authors: Li Jing , Ni Guo‐Hua , Guo Zhen , Fan Hong‐Bin , Cong Rui , Wang Zhen , Li Ming‐Quan
Published: August 2008

Purpose: To determine the indications and benefits of ectopic implantation in the salvage of amputated thumb. Basic procedures: Two cases of avulsed amputated thumbs were temporarily ectopically implanted onto the forearm and foot, with microvascular anastomoses. When the stump condition allowed, and the soft‐tissue defects were repaired, the ectopic implanted thumbs were replanted to their anatomic positions. Results: Both thumbs survived the temporary ectopic implantation and second‐stage replantation. The length of the thumbs was maintained, and the thumbs regained their function in 16‐ and 10‐week follow‐ups. Conclusions: Temporary ectopic implantation of amputated parts provides an innovative procedure for the salvage of amputated thumbs under special circumstances. Although this procedure is very demanding, it does deserve special consideration in reconstructive microsurgery, since it offers the possibility to salvage amputated thumbs with extensive soft tissue loss of the hand, by preserving the anatomy and restoring the function of severely injured hands. © 2008 Wiley‐Liss, Inc. Microsurgery, 2008.
Higher ordermixed finite element approximation of subsurface water flow
Authors: Bause Markus
Published: August 2008

This paper focuses on the reliable and efficient numerical approximation of subsurface water flows. The locally mass conservative Brezzi‐Douglas‐Marini (BDM1) mixed finite element method is considered and compared to a lowest order Raviart–Thomas (RT0) mixed finite element approach and a Multi Point Flux Approximation. Appreciable advantage of the BDM1 element is that it yields a formally second order accurate flux approximation whereas the RT0 and MPFA approach are of first order accuracy only. The problem to be analyzed in this work is whether a superiority of the BDM1 element can also be observed in reservoir simulation where discontinuous and full permeability tensors on non‐uniform grids arise and the fluxes lack the regularity that is assumed customarily in optimal order error analyses. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear time‐series modeling and prediction using correlation analysis
Authors: Dydyński Andrzej , Arabas Jaroslaw
Published: August 2008

We present a novel way for time series prediction. The method is based on the correlation analysis and allows for handling nonlinearities of different type and character. The presented approach results in an approximation model that combines nonlinear units taken from radial basis functions (RBF) and from multilayer perceptrons (MLP). The approach leads to a low mean error of the approximation with a number of parameters significantly smaller when compared to RBF and MLP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotic behaviour and optimal word size for exact and approximate word matches between random sequences
Authors: Forêt Sylvain , Burden Conrad J. , Wilson Susan R.
Published: August 2008

The present work is concerned with a fast and accurate sequence comparison method: the count of the number of words of length k letters shared by two sequences, also known as the D2 statistic. We link recent theoretical advances in the characterization of D2 asymptotic distributions with applications to biological sequences. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coarsening dynamics of polymer droplets for a lubrication model with large slippage
Authors: Kitavtsev G. , Recke L. , Wagner B.
Published: August 2008

We analyze the final stages of the dewetting process of nanoscopic thin polymer films on hydrophobized substrates using a lubrication model that captures the large slippage at the liquid‐substrate interface. The final stages of this process are characterized by the slow‐time coarsening dynamics of the remaining droplets. For this situation we derive a reduced system of equations from the lubrication model, using singular perturbation analysis. Such reduced models allow for an efficient numerical simulation of the coarsening process. The reduced model extends results of [2] for no‐slip lubrication model. Apart from collapse and collision, we identify here some new coarsening dynamics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A global approach of electromagnetism dedicated to further long‐term planning
Authors: Mazauric Vincent , Maïzi Nadia
Published: August 2008

In 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

Thawing 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

Given 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

In 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

A 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

Instantaneous 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

We 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

We 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

The 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)
The evolution of a viscous two‐fluid flow down an inclined plane
Authors: Socolowsky Jürgen
Published: August 2008

An evolutionary problem on the viscous (isothermal) flow of two connected fluids down an inclined plane is investigated. (© 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

We 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

Recently, 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

This 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

Air 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

Current 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

This 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

The 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

For 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

The 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

The 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

Monte 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

(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

Expressions 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

Axial 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

Variational 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

For 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

In 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)
Investigating spontaneous capillarity‐controlled events via the level set method
Authors: Prodanović Maša , Bryant Steven L.
Published: August 2008

An accurate description of the mechanics of pore level displacement of immiscible fluids could significantly improve the macroscopic parameter predictions in real porous media. Assuming quasi‐static displacement, we describe a simple but robust model based on the level set method for determining fluid interface position for both drainage and imbibition. The method arrives at geometrically correct interfaces while robustly handling topology changes and is independent of the pore space complexity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An option pricing model based on jump telegraph processes
Authors: Ratanov Nikita
Published: August 2008

A new class of financial market models is developed. These models are based on generalized telegraph processes: Markov random flows with alternating velocities and jumps occurring when the velocities are switching. While such markets may admit an arbitrage opportunity, the model under consideration is arbitrage‐free and complete if directions of jumps in stock prices are in a certain correspondence with their velocity and interest rate behaviour. An analog of the Black‐Scholes fundamental differential equation is derived, but, in contrast with the Black‐Scholes model, this equation is hyperbolic. Explicit formulas for prices of European options are obtained using perfect and quantile hedging. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extension of the EJIIM to stationary two‐phase Stokes equations
Authors: Rutka Vita
Published: August 2008

We extend the Explicit Jump Immersed InterfaceMethod (EJIIM) to stationary two phase Stokes equations with discontinuous viscosity. As the underlying finite difference method the discretization in velocity and pressure variables is used on a staggered grid. The resulting algorithm converges with second order in velocity and first in pressure. The iteration count for solving the resulting linear system remains practically constant under grid refinement and is independent of the viscosity contrast. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling, simulation and control of a doubly‐fed induction machine
Authors: Batlle Carles , Dòria‐Cerezo Arnau , Fossas Enric
Published: August 2008

The Hamiltonian model and control of a doubly‐fed induction machine is discussed. The geometric properties of the Hamiltonian formalism allow us to develop control algorithms which assure stability and good performance. Experimental results in good accordance with the control goals are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A model of breast carcinogenesis and recurrence after radiotherapy
Authors: Enderling Heiko , Anderson Alexander R.A. , Chaplain Mark A.J.
Published: August 2008

Breast conserving surgery and adjuvant radiotherapy are the standard treatment of early stage breast cancer. We present simulations of a mathematical model of breast carcinogenesis and identify fields of mutated cells in the breast (formed during puberty or pregnancy) as a potential source of local recurrence after treatment with radiotherapy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strategic trade policy and signaling costs with differentiated goods
Authors: Ferreira Fernanda A. , Moreira Humberto A. , Pinto Alberto A.
Published: August 2008

We consider a trade policy model, where the costs of the home firm are private information but can be signaled through the output levels of the firm to a foreign competitor and a home policymaker. We compute the separating equilibrium and the Bayesian Nash equilibrium, and we compare the subsidies, firms' expected profits and home government's welfare in both equilibria, for different values of the own price effect parameter. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational sensitivity analysis and changes in the material configuration
Authors: Materna Daniel , Barthold Franz‐Joseph
Published: August 2008

This contribution is concerned with some aspects of variational design sensitivity analysis in the physical and material configuration. Sensitivity analysis is a branch of structural optimization, e.g. shape or topology optimization. In these disciplines we consider variations of the material configuration and we are interested in the change of the state variables and the objective functional due to these variations. In the context of structural optimization this is termed as design sensitivity analysis. The sensitivities are required in order to solve the corresponding Lagrangian equation within standard nonlinear programming algorithms. In many engineering applications, the energy functional of the problem is used as the objective functional. In this paper, we consider variations of the energy with respect to the state and the design and we investigate sensitivity relations for the physical and material problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Octopus‐shaped instabilities of evaporating drops
Authors: Murisic N. , Kondic L.
Published: August 2008

We report on instabilities during spreading of volatile liquids, with emphasis on the novel instability observed when isopropyl alcohol (IPA) is deposited on a monocrystaline Si wafer. This instability is characterized by emission of drops ahead of the expanding front, with each drop followed by smaller, satellite droplets, forming the structures which we nickname ‘octopi’ due to their appearance. A less volatile liquid, or a substrate of larger heat conductivity, suppress this instability. We have formulated a theoretical model that reproduces the main features of the experiment. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symbolic‐numeric algorithms for analysis of stochastic systems with different forms of aftereffect
Authors: Poloskov I.E.
Published: August 2008

Problems concerned with an analysis of stochastic differential equations with delays are considered. The main idea of study consists of an extension of the phase space. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interior‐point methods applied to the AC active‐reactive optimal power‐flow problem using cartesian coordinates
Authors: Probst Roy , Oliveira Aurelio , Soares Secundino , Thomaz Adriano
Published: August 2008

The primal dual interior point methods are developed to the AC active and reactive optimal power flow problem. The representation of the tensions through cartesian coordinates is adopted, once the Hessian is constant and the Taylor expansion is accurate for the second order term. The advantage of working with polar coordinates, that easily model the tension magnitudes, lose importance due to the efficient treatment of inequalities proportionated by the interior point methods. Before the application of the method, the number of variables of the problem is reduced through the elimination of free dual variables. This elimination does not modify the sparse pattern of the problem. The linear system obtained can be further reduced to the dimension of twice the number of buses also with minor changes in the sparse structure of the matrices involved. Moreover, the final matrix is symmetric in structure. This feature can be exploited reducing the computational effort per iteration. Computational experiments for IEEE system problems are presented for several starting point strategies showing the advantages of the proposed approach. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Option pricing using multivariate Lévy processes
Authors: Winter Christoph , Reich Nils
Published: August 2008

For d ‐dimensional Lévy models we provide a method for Finite Element‐based asset pricing. We derive the partial integrodifferential pricing equation and prove that the corresponding variational problem is well‐posed. Hereto, an explicit characterization of the domain of the bilinear form is given. For the numerical implementation the problem is discretized by sparse tensor product Finite Element spaces. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large‐scale simulation of arterial walls: mechanical modeling
Authors: Balzani Daniel , Brands Dominik , Klawonn Axel , Rheinbach Oliver
Published: August 2008

Biological soft tissues appearing in arterial walls are characterized by a nearly incompressible, anisotropic hyperelastic material behavior in the physiological range of deformations. For the representation of such materials we apply a polyconvex strain energy function in order to ensure the existence of minimizers and in order to satisfy the Legendre‐Hadamard condition automatically. When arteries are overstretched, discontinuous damage is observed. For the modeling of this effect we apply a damage model, which basically assumes that the damage occurs mainly in fiber direction. For the numerical simulation we consider an atherosclerotic artery and apply a high internal pressure which is comparable to the pressure applied during a balloon‐angioplasty. The 3D‐discretization results in a large system of equations, therefore, a parallel algorithm using FETI‐DP is applied to solve the boundary value problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A multiobjective decomposition‐coordination framework with an application to vehicle layout and configuration design
Authors: Engau Alexander , Fadel Georges M. , Wiecek Margaret M.
Published: August 2008

This short paper addresses both researchers in multiobjective optimization as well as industrial practitioners and decision makers in need of solving optimization and decision problems with multiple criteria. To enhance the solution and decision process, a multiobjective decomposition‐coordination framework is presented that initially decomposes the original problem into a collection of smaller‐sized subproblems that can be solved for their individual solution sets. A common solution for all decomposed and, thus, the original problem is then achieved through a subsequent coordination mechanism that uses the concept of epsilon‐efficiency to integrate decisions on the desired tradeoffs between these individual solutions. An application to a problem from vehicle configuration design is selected for further illustration of the results in this paper and suggests that the proposed method is an effective and promising new solution technique for multicriteria decision making and optimization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel class of thermodynamically consistent isotropic hardening rules for some damage models at finite strains
Authors: Fell Christian , Eidel Bernhard
Published: August 2008

This paper proposes isotropic hardening rules for plasticity damage models which satisfy the 2nd law of thermodynamics. Here, the Gurson ‐model modified by Tvergaard/Needleman is used as a prototype model for finite strains to discuss main properties of the novel hardening rules. Additionally it is shown that thermodynamically consistent rules are suitable to fit experimental data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symmetry analysis for a thin film equation
Authors: Gandarias M.L. , Bruzón M.S.
Published: August 2008

In this work we give a complete group classification of the thin film equation ut = –(f (u)xxx )x – kg (u)x . By using Lie classical method the corresponding reductions are performed and some solutions are characterized. Some nonclassical symmetries for an associated potential system are derived. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlocal boundary value problem for a system of singular differential equations and applications to cusped prismatic shells
Authors: Jaiani George
Published: August 2008

The paper deals with a system of singular partial differential equations of the first and second order arising in the zero approximation of I.Vekua's hierarchical models of prismatic shells, when the thickness of the shell varies as a power function of one argument and vanishes at the cusped edge of the shell. For this system of special type a nonlocal boundary value problem in a half‐plane is solved in the explicit form. The boundary value problem under consideration corresponds to stress‐strain state of the cusped prismatic shell [1,2] under the action of concentrated forces and moments. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free‐surface film flow over topography under electric fields
Authors: Tseluiko D. , Blyth M. G. , Papageorgiou D. T. , Vanden‐Broeck J.‐M.
Published: August 2008

We study a gravity‐driven flow of a liquid down an inclined uneven wall in the presence of a normal electric field. We derive an evolution equation for the free‐surface, and analyse steady‐state solutions for flows into a rectangular trench and over a rectangular mound. The results are corroborated by boundary‐element calculations for Stokes flow. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiplexed glycoproteomic analysis of glycosylation disorders by sequential yolk immunoglobulins immunoseparation and MALDI‐TOF MS
Authors: Sturiale Luisa , Barone Rita , Palmigiano Angelo , Ndosimao Célestin Nsibu , Briones Paz , Adamowicz Maciej , Jaeken Jaak , Garozzo Domenico
Published: August 2008

This study applied yolk immunoglobulins immunoaffinity separation and MALDI‐TOF MS for clinical proteomics of congenital disorders of glycosylation (CDG) and secondary glycosylation disorders [galactosemia and hereditary fructose intolerance (HFI)]. Serum transferrin (Tf) and α1‐antitrypsin (AAT) that are markers for CDG, were purified sequentially to obtain high‐quality MALDI mass spectra to differentiate single glycoforms of the native intact glycoproteins. The procedure was found feasible for the investigation of protein macroheterogeneity due to glycosylation site underoccupancy then ensuing the characterization of patients with CDG group I (N‐glycan assembly disorders). Following PNGase F digestion of the purified glycoprotein, the characterization of protein microheterogeneity by N‐glycan MS analysis was performed in a patient with CDG group II (processing disorders). CDG‐Ia patients showed a typical profile of underglycosylation where the fully glycosylated glycoforms are always the most abundant present in plasma with lesser amounts of partially and unglycosylated glycoforms in this order. Galactosemia and HFI are potentially fatal diseases, which benefit from early diagnosis and prompt therapeutic intervention. In symptomatic patients with galactosemia and in those with HFI, MALDI MS of Tf and AAT depicts a hypoglycosylation profile with a significant increase of underglycosylated glycoforms that reverses by dietary treatment, representing a clue for diagnosis and treatment monitoring.
A study of the Candida albicans cell wall proteome
Authors: Castillo Luis , Calvo Enrique , Martínez Ana I. , Ruiz‐Herrera José , Valentín Eulogio , Lopez Juan A. , Sentandreu Rafael
Published: August 2008

Considering the importance of proteins in the structure and function of the cell wall of Candida albicans, we analyzed the cell wall subproteome of this important human pathogen by LC coupled to MS (LC‐MS) using different protein extraction procedures. The analyzed samples included material extracted by hydrogen fluoride‐pyridine (HF‐pyridine), and whole SDS‐extracted cell walls. The use of this latter innovative procedure gave similar data as compared to the analysis of HF‐pyridine extracted proteins. A total of 21 cell wall proteins predicted to contain a signal peptide were identified, together with a high content of potentially glycosylated Ser/Thr residues, and the presence of a GPI motif in 19 of them. We also identified 66 “atypical” cell wall proteins that lack the above‐mentioned characteristics. After tryptic removal of the most accessible proteins in the cell wall, several of the same expected GPI proteins and the most commonly found “atypical” wall proteins were identified. This result suggests that proteins are located not only at the cell wall surface, but are embedded within the cell wall itself. These results, which include new identified cell wall proteins, and comparison of proteins in blastospore and mycelial walls, will help to elucidate the C. albicans cell wall architecture.