bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Theory of Micellization Kinetics
Authors: Nyrkova Irina A. , Semenov Alexander N. 
Published: November 2005

AbstractSummary: We consider certain general features of aggre‐ gation (micellization) processes in solutions of amphiphilic molecules, in particular, block‐copolymers. We demonstrate that non‐equilibrium effects can be very important for micellization. In particular, we show that micelle formation at the conventional (equilibrium) critical micelle concentration (CMC, $c_c$) can be inhibited by high activation energy barriers. This is likely to be the case when the micelles are large. In this case an aggregation actually occurs at higher concentrations, above an apparent CMC, $c_{\rm a}$. The concentration $c_{\rm a}$ can be much higher than the equilibrium CMC. Hence significant hysteresis effects are inherent in amphiphilic systems since micelle formation and dissociation are activation processes. To further clarify this idea we consider relaxation of a micellar system after a temperature jump (or a jump of another essential parameter) and discuss qualitatively different relaxation times corresponding to the relaxations of the micellar sizes and of the total number of micelles. We also discuss different kinetic pathways of micelle formation and relaxation and show that in certain cases the ideal‐gas (combinatorial) contribution to the micelle free energy is significant for the kinetics.Micelle association and dissociation times vs. reduced concentration.magnified imageMicelle association and dissociation times vs. reduced concentration.
Breaking Water Waves: Unsteady 2D Free‐Surface Computations
Authors: Cooker Mark J. 
Published: November 2005

AbstractSome numerical methods for the full Euler equations in two space dimensions are reviewed. Efficient computations can be carried out using a boundary‐integral method described, (originally due to J. W. Dold and D. H. Peregrine) which is able to track the unsteady evolution of the free surface of overturning waves. The method is fifth‐order in time and tenth order in space. It has been used to compute violent water motions when a wave collides with a vertical wall, for which high accelerations and large pressure gradients are found. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Lepskij–type Stopping‐Rule for Newton‐type Methods with Random Noise
Authors: Bauer Frank , Hohage Thorsten 
Published: November 2005

AbstractRegularized Newton methods are one of the most popular approaches for the solution of inverse problems in differential equations. Since these problems are usually ill‐posed, an appropriate stopping rule is an essential ingredient of such methods. In this paper we suggest an a‐posteriori stopping rule of Lepskij‐type which is appropriate for data perturbed by random noise. The numerical results for this look promising. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupling Techniques for Thermal and Mechanical Fluid‐Structure‐Interactions in Aeronautics
Authors: Haupt Matthias , Niesner Reinhold , Unger Ralf , Horst Peter 
Published: November 2005

AbstractFor the coupled thermal and mechanical analysis of spacecraft structures a simulation environment was developed containing the necessary coupling techniques. The numerical concept uses the weak form of the interface conditions on the coupling surface. The iterative solution of the coupled equations is based on the classical Dirichlet‐Neumann approach. Transient problems are handled with iterative staggered schemes. A flexible component‐based software environment combines existing fluid and structural analysis codes. Aspects of the architecture and its implementation are described. Finally an application to a spacecraft structure is shown. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of lower‐bound direct method to large‐scale problems
Authors: Hachemi Abdelkader , Mouhtamid Said , Weichert Dieter 
Published: November 2005

AbstractIn this paper, a lower‐bound direct method is presented for the large‐scale problems. This method is based on the statical shakedown analysis and nonlinear mathematical programming. Here, the interior point method combined with the method of difference of convex functions (IPDCA) is used to solve large‐scale problems. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuum Biomechanics Applied to the Human Intervertebral Disc
Authors: Ehlers W. , Karajan N. , Markert B. , Acartürk A. 
Published: November 2005

AbstractBiomechanical problems are of growing importance for our society with respect to both the ongoing aging of people and the improvement of surgery techniques. As a result, there is an increasing interest in scientific biomechanics in order to understand and to describe the complex electro‐chemomechanical behaviour of biological tissues. In the present contribution, the methods of continuum biomechanics are applied to the human intervertebral disc (IVD) as one of the major load‐carrying mechanisms of the human spine.As a naturally grown material, the IVD belongs to the class of soft avascular cartilaginous tissues consisting of mostly ionized water (interstitial fluid) and collagen of type I and II embedded in an extracellular meshwork of charged protein compounds. More precisely, the type I collagen is organized in fiber bundles building a fiber‐reinforced ring, the anulus fibrosus (AF), which encloses a highly charged gelatinous core, the nucleus pulposus (NP). Following this, the principle loadbearing mechanism of the disc emerges directly. Under compression, interstitial fluid pressure develops inside the NP forcing a lateral bulging, which is prevented by the AF with its collagen fibers under tension.In the framework of continuum biomechanics, the IVD is modelled on the basis of the established Theory of Porous Media (TPM), which allows for the description of multicomponent continua with internal interactions and is proven to yield stable implementations within the mixed finite element method (FEM). Following this, one succeeds in describing the physiological behaviour of charged hydrated tissues. This includes the electro‐chemomechanical couplings as well as the viscoelastic and anisotropic properties of the extracellular matrix. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pore structures: Measurement, characterization and relevance for flow and transport in soils
Authors: Lehmann Peter 
Published: November 2005

AbstractThe geometry of the pore space determines the flow and transport properties of a soil under water saturated and unsaturated conditions. The spatial arrangement of the pores can be mapped using the appropriate tomographic technique. To understand the effect of the pore space on flow and transport, the complex pore structures must be quantified. To reveal the importance of various geometrical properties, porous media with well defined geometrical properties were numerically generated and were compared with a sand medium containing sphere‐like particles with sizes ranging from 80 to 1.250 µm. The spatial distribution of water and air was calculated for the optimized media and the sand packing to quantify the relevance of the geometric properties. In a first test, the sand packing was compared with a generated medium with identical Minkowski functionals. The resulting pores of the generated media were too large and the water retention was underestimated. In a second test, a medium with an optimized chord length distribution was generated and a good agreement with respect to water distribution was found. The chord length distribution is a more relevant property, because it takes into account the correlation of the system over large spatial distances. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of Discrete‐Continuous Dynamic Systems Based on Disjunctive Programming
Authors: Oldenburg Jan , Marquardt Wolfgang 
Published: November 2005

AbstractIn this contribution, a novel approach for the modeling and optimization of discrete‐continuous dynamic systems based on a disjunctive problem formulation is proposed. It will be shown that a disjunctive model representation, which constitutes an alternative to mixed‐integer model formulations, provides a very flexible and intuitive way to formulate discrete‐continuous dynamic optimization problems. Moreover, the structure and properties of the disjunctive process models can be exploited for an efficient and robust numerical solution by applying generalized disjunctive programming techniques. The proposed modeling and optimization approach will be illustrated by means of an optimal control problem that embeds a linear discretecontinuous dynamic system. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a trust region method without exact Jacobian matrices
Authors: Walther Andrea 
Published: November 2005

AbstractAutomatic differentiation (AD) provides a possibility to evaluate exact derivative information within working accuracy. Here, we present an approach for equality constrained optimization that is based essentially on AD by computing only direct sensitivities and adjoints of first and second order. Employing this information, we generate approximations of the required derivative matrices using the STR1 update instead of computing the full constraint Jacobian or the full Lagrangian Hessian at each iteration explicitly. Hence, this approach avoids the forming and factoring of the exact constraint Jacobian that is often required in each iteration step.In order to globalize this provable local convergent method, the algorithm was embedded in a trust‐region framework. We apply a composite‐step method similar to the Byrd‐Omojokun approach that is well suited for the available information from the approximated matrices. For that purpose, the normal step is given by the dogleg method whereas a generalized CG‐iteration is applied to compute the tangential step. Here, the fact that only inexact information of the constraint Jacobian is available forms the main difference to other existing algorithms, where often a factorization of the exact Jacobian is used.Numerical results are shown for an equality constrained problem of the CUTE set and a PDE‐based optimization problem. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation Based Determination of Piezoelectric Material Parameters
Authors: Lahmer Tom , Kaltenbacher Barbara , Mohr Marcus 
Published: November 2005

AbstractThe exact numerical simulation of piezoelectric transducers needs the knowledge of all material tensors that occur in the piezoelectric constitutive relations. The determination of these tensors is achieved by a simulation based algorithm which adjusts the 3D ‐ FEM simulated data with electrical measurements of a piezoelectric transducer. Its advantage compared to the standards (see [1], [2]) lies in the fact that a determination of the complete set of material parameters from one arbitrarily shaped specimen with a high precision is possible. The reconstruction of the material tensors is formulated as a parameter identification problem for a system of PDEs. Since unique solvability of this inverse problem may hardly be verified, the system of equations we have to solve for recovering the material tensor entries can be rank deficient and therefore requires application of appropriate regularization strategies. For this purpose, we use inexact Newton methods. The material parameters are assumed to be complex‐valued which allows to account for mechanical, dielectric and piezoelectric losses. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new update procedure for internal variables in an ALE‐description of rolling contact
Authors: Ziefle M. , Nackenhorst U. 
Published: November 2005

AbstractIn FEM analysis of rolling contact problems Arbitrary Lagrangian‐Eulerian (ALE) methods are the state of the art. These methods allow mesh refinements concentrated to the contact region and offer a time independent formulation of stationary elastic rolling. The relative‐kinematic description of rolling leads to a relative motion between the finite element mesh and the material points. Thus in the case of inelastic material behavior history dependent constitutive equations contain convective terms. The handling of these convective terms is performed by a so called fractional step method. A material step is followed by a convection step. In the first step the nonlinear solid contact problem is resolved by neglecting the convective terms. In the following step the internal variables are transported on the streamlines of the material particles by solving the advection equation via a time‐discontinuous Galerkin method. This update procedure is demonstrated on a typical FEM‐tire model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cosserat continuum modelling of grain size effects in metal polycrystals
Authors: Zeghadi Asmahana , Forest Samuel , Gourgues Anne‐Françoise , Bouaziz Olivier 
Published: November 2005

AbstractThe global response of polycrystalline aggregates is investigated, in order to simulate grain size effects in IF ferritic steels. The mechanics of generalized continua is used to describe the studied phenomena. The polycrystal is regarded as a heterogeneous Cosserat medium, and the overall properties are estimated using a specific homogenization technique. To illustrate the capabilities of the model, some simple bidimensionnal computations are presented for different grain sizes. Afterwards tridimensionnal computations are shown in order to extract the global effect on the mechanical behaviour for grain sizes ranging from 5 µm to 120 µm. The finite element response is harder for the smallest grain size, but the model still underestimate the grain size effect on the tensile response. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synergy Between N and O Atom Action and Substrate Surface Temperature in a Sterilization Process Using a Flowing N2‐O2 Microwave Post Discharge
Authors: Villeger Sandrine , Sarrette Jean Philippe , Ricard André 
Published: November 2005

AbstractSummary: It is demonstrated here that the sterilization process using a flowing N2‐O2 post discharge reactor involves a specific heating of the bacteria metal holder produced by heterogeneous O and N atoms recombination. Such heating increases with N and O‐atom concentrations, which can be varied with the microwave discharge power. It also depends on the metallic material of the holder: a brass support can reach a maximum surface temperature of 120 °C while the surface temperature of the stainless steel holder increases to 60–70 °C after 40 min of exposure to a N2‐5% O2 post discharge at 0.6 kPa (5 Torr), 1 Ln · min−1 and 100 W. It is demonstrated that the E. coli destruction efficiency increases with N and O atom density at a constant temperature (60 °C) of the stainless steel support and with the support temperature (up to 60 °C) at constant N and O atom densities. A cumulative effect was also found with increasing N and O atom density and of the support temperature.Bacteria survivor number versus the exposure time to a N2‐5% O2 post discharge.magnified imageBacteria survivor number versus the exposure time to a N2‐5% O2 post discharge.
Physical, chemical and environmental properties of selected chemical alternatives for the pre‐plant use of methyl bromide as soil fumigant
Authors: Ruzo Luis O 
Published: November 2005

AbstractProduction and use of methyl bromide, a soil fumigant, are being restricted because of this chemical's deleterious effects on stratospheric ozone concentrations. Several products, some of which are currently used as soil fumigants, are being considered as possible replacements for methyl bromide, alone and in various combinations. Among these, 1,3‐dichloropropene, methyl isothiocyanate generators such as metam‐sodium, and chloropicrin are currently registered, while others such as methyl iodide and sodium azide are at different stages of the registration process. This review examines physicochemical properties, environmental fate, and metabolism of the various potential methyl bromide replacement products. Copyright © 2005 Society of Chemical Industry
Selectivity of pesticides used on cotton (Gossypium hirsutum) to Trichogramma pretiosum reared on two laboratory‐reared hosts
Authors: Bastos Cristina S , de Almeida Raul P , Suinaga Fábio A 
Published: November 2005

AbstractThe side‐effects of pesticides (insecticides, fungicides, herbicides and plant growth regulators) used on cotton were tested on adults and pupae of Trichogramma pretiosum Riley reared in the laboratory on two different hosts, the Angoumois grain moth (Sitotroga cerealella Olivier) and the Mediterranean flour moth (Ephestia kuehniella (Zeller)). The eggs of the host enclosing the parasitoid pupae received direct pesticide sprays, while the adults of the parasitoid were exposed to the pesticides through contact with residues on sprayed eggs offered to parasitism. Alpha‐cypermethrin, carbosulfan, deltamethrin, endosulfan, profenofos and zeta‐cypermethrin were highly noxious to the parasitoid, significantly reducing the percentage of emergence and parasitism of T. pretiosum developing in E. kuehniella or S. cerealella eggs. However, the pupal stage of the parasitoid developing in S. cerealella eggs was less susceptible to alpha‐cypermethrin and deltamethrin. Lufenuron and metamidophos greatly reduced the percentage of adult emergence from eggs of both hosts, while novaluron only interfered on this variable when the wasps were developing in E. kuehniella eggs. However, lufenuron and monocrotophos had no effect on the parasitoid pupae of T. pretiosum developing in E. kuehniella eggs. Chlorfluazuron, diafenthiuron, diflubenzuron, fentin hydroxide, mepiquat chloride, novaluron, thiacloprid and triflumuron did not affect T. pretiosum emergence when eggs of S. cerealella enclosing pupae of the wasps were surface treated. The pesticides azoxystrobin, carbendazin + thiram, mepiquat chloride and novaluron had no effect on the ability of the wasps to parasitise E. kuehniella eggs. However, only mepiquat chloride did not affect the percentage of F1 wasps emerging from E. kuehniella eggs. The remaining pesticides moderately reduced the percentage of emergence and parasitism of the wasps when they had contact with the chemicals during their pupal or adult stage. Thus there were differences in pesticide toxicity according to the host used for parasitoid development. These differences were hypothesised to occur because of differences in egg morphology and parasitoid performance. Copyright © 2005 Society of Chemical Industry
Long‐term persistence and efficacy of spinosad against Rhyzopertha dominica (Coleoptera: Bostrychidae) in wheat
Authors: Daglish Gregory J , Nayak Manoj K 
Published: November 2005

AbstractA laboratory study was undertaken to determine the persistence and efficacy of spinosad against Rhyzopertha dominica (F.) in wheat stored for 9 months at 30 °C and 55 and 70% relative humidity. The aim was to investigate the potential of spinosad for protecting wheat from R. dominica during long‐term storage in warm climates. Wheat was treated with spinosad at 0.1, 0.5 and 1 mg kg−1 grain and sampled after 0, 1.5, 3, 4.5, 6, 7.5 and 9 months of storage for bioassays and residue analyses. Residues were estimated to have declined by 30% during 9 months of storage at 30 °C and there was no effect of relative humidity. Spinosad applied at 0.5 or 1 mg kg−1 was completely effective for 9 months, with 100% adult mortality after 14 days of exposure and no live F1 adults produced. Adult mortality was <100% in some samples of wheat treated with 0.1 mg kg−1 of spinosad, and live progeny were produced in all samples treated at this level. The results show that spinosad is likely to be an effective grain protectant against R. dominica in wheat stored in warm climates. Copyright © 2005 Society of Chemical Industry
Space, time and the vulnerable witness: exploring the tensions between policy and personal perspectives on witness intimidation
Authors: Fyfe Nicholas R. 
Published: November 2005

AbstractFocusing on a specific vulnerable group (witnesses to crimes who have experienced or fear intimidation from offenders and their associates), this paper examines attempts by policy‐makers to address their anxieties and fears, and the impact of experiencing intimidation on the witnesses themselves. The first section traces the ‘discovery’ by policy‐makers of vulnerable witnesses in Britain in the mid‐1990s and how this led to the introduction of a range of spatial tactics and strategies aimed at reducing the vulnerability of witnesses to intimidation. This policy response has, however, been founded on a particular reading of the geography of witness vulnerability, narrowly focused around the courtroom during the trial period. Using interviews with witnesses who have experienced intimidation, the second section examines how the spatial and temporal coordinates of witnesses' fears are more complex than current policy measures allow for. The third section of the paper then juxtaposes policy and personal discourses around intimidation, focusing on the different understandings of the social, spatial and temporal contexts of intimidation and the differences between situational and social approaches to addressing witnesses' concerns. Many of the issues raised in this section concerning the dangers of relocating risk as a result of adopting situational approaches to witness vulnerability, and the tendency to address symptoms rather than causes, intersect with wider concerns that geographers have in relation to vulnerability research; these are discussed in the conclusion. Copyright © 2005 John Wiley & Sons, Ltd.
Towards an interdisciplinary conceptualisation of vulnerability
Authors: Hogan Daniel Joseph , Marandola Eduardo 
Published: November 2005

AbstractEach discipline uses uncertainty in different ways. This paper reviews the range of definitions and methodologies used by researchers to approach vulnerability in the search for an interdisciplinary conceptualisation. Two themes (poverty, exclusion and marginalisation on the one hand, and society–environment interactions on the other) are used to explore the authors' conceptualisation of vulnerability. The paper points towards possible convergences of these approaches. Copyright © 2005 John Wiley & Sons, Ltd.
Quantum fluctuations of ultracold atom–molecule mixtures
Authors: Domański T. 
Published: November 2005

AbstractWe investigate the evolution of quantum coherence in an ultracold mixture of fermionic atoms and bosonic dimer molecules. Interactions are experimentally controlled via tuning the external magnetic field. Consequently, the fermionic atoms and their bosonic counterparts can be driven to a behavior resembling the usual BCS to BEC crossover. We analyze in some detail how this quantum coherence evolves with respect to time upon a smooth and abrupt sweep across the Feshbach resonance inducing the atom–molecule quantum fluctuations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two dimensional model for correlated eg electrons in doped nickelates
Authors: Rościszewski Krzysztof , Oleś Andrzej M. 
Published: November 2005

AbstractWe investigate the magnetic, orbital and charge instabilities in eg band for the average filling by n = 2 – x electrons per site, as in La2–x Srx NiO4. The calculations were performed on 8 × 8 clusters, with electron correlations included within the local ansatz method. The C ‐type antiferromagnetic phase was found in a broad range of doping, but distinct stripe phases could not be identified. The nonuniform orbital order is present for some dopings and couples to charge and spin order. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)