bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of psychiatric diagnoses on hospital length of stay in children with sickle cell anemia
Authors: Myrvik Matthew P. , Campbell Andrew D. , Davis Matthew M. , Butcher Jennifer L.
Published: March 2011

Background

Patients with sickle cell anemia (SCA) experience a broad range of psychiatric disorders, placing them at risk for more complicated and longer hospitalizations for vaso‐occlusive crises (VOC). The current study examined the frequency of psychiatric disorders in SCA patients (ages birth to 20 years) admitted for VOC in a nationally representative sample and the association between psychiatric disorders and hospital length of stay (LOS).

Procedure

Patients with a primary diagnosis of SCA with crisis identified through the nationally representative Kids' Inpatient Database (KID) 2006 from the Agency of Healthcare Research and Quality were included for analysis. Patients with psychiatric disorders listed as secondary diagnoses were categorized under specific psychiatric disorders (mood disorder, anxiety disorder, disruptive behavior disorder, substance use disorder). Non‐parametric and regression analyses were utilized for nationally weighted data, to determine the effect of psychiatric disorders on LOS, while controlling for significant covariates.

Results

For 21,255 hospital discharges for children with SCA with crisis in 2006, the mean LOS was 4.51 days. Approximately 6% of the patients discharged had a psychiatric disorder. After adjusting for significant covariates, mood disorders, anxiety disorders, and any psychiatric disorder were each associated with significantly longer LOS (P < 0.01). Substance and disruptive behavior disorders were not associated with LOS.

Conclusions

Pediatric patients diagnosed with a psychiatric disorder, specifically mood or anxiety disorders, have longer LOS for VOC. These findings suggest that future interventions aimed at managing VOC may need to consider adjunctive psychiatric assessment and intervention. Pediatr Blood Cancer 2012; 58: 239–243. © 2011 Wiley Periodicals, Inc.
Direct quantitation of MHC‐bound peptide epitopes by selected reaction monitoring
Authors: Tan Chor Teck , Croft Nathan P. , Dudek Nadine L. , Williamson Nicholas A. , Purcell Anthony W.
Published: March 2011

We describe a cell‐free approach that employs selected reaction monitoring (SRM) in tandem mass spectrometry to identify and quantitate T‐cell epitopes. This approach utilises multiple epitope‐specific SRM transitions to identify known T‐cell epitopes and an absolute quantitation (AQUA) peptide strategy to afford AQUA. The advantage of a mass spectrometry‐based approach over more traditional cell‐based assays resides in the robustness and transferability of an SRM approach between laboratories and the ability of this strategy to detect multiple peptides simultaneously without the requirement of epitope‐specific reagents such as T‐cell lines. Thus, the SRM strategy for epitope quantitation will find application in studies of antigen density, the link between epitope abundance and immunogenicity, the dynamic range of epitope presentation and the abundance of T‐cell epitopes in disease.
Two novel ficolin‐like proteins act as pattern recognition receptors for invading pathogens in the freshwater crayfish Pacifastacus leniusculus
Authors: Wu Chenglin , Söderhäll Kenneth , Söderhäll Irene
Published: March 2011

To isolate pathogen‐associated molecular patterns (PAMPs)‐binding molecules, the bacterium, Staphylococcus aureus was used as an affinity matrix to find bacteria‐binding proteins in the plasma of the freshwater crayfish, Pacifastacus leniusculus. Two new bacteria‐binding ficolin‐like proteins (FLPs) were identified by 2‐DE and MS analysis. The FLPs have a fibrinogen‐related domain (FReD) in their C‐terminal and a repeat region in their N‐terminal regions with putative structural similarities to the collagen‐like domain of vertebrate ficolins and mannose binding lectins (MBLs). Phylogenetic analysis shows that the newly isolated crayfish FLP1 and FLP2 cluster separately from other FReD‐containing proteins. A tissue distribution study showed that the mRNA expression of FLP occurred mainly in the hematopoietic tissue (Hpt) and in the hepatopancreas. Recombinant FLPs exhibited agglutination activity of Gram‐negative bacteria Escherichia coli and Aeromonas hydrophila in the presence of Ca2+. The FLPs could bind to A. hydrophila, E. coli as well as S. aureus as judged by bacteria adsorption. Moreover, the FLPs may help crayfish to clear Gram‐negative bacteria, but not Gram‐positive bacteria which had been injected into the hemolymph. When Gram‐negative bacteria coated with FLPs were incubated with Hpt cells, a lower death rate of the cells was found compared with control treatment. Our results suggest that FLPs function as pattern recognition receptors in the immune response of crayfish.
Room‐temperature processing of π‐conjugated oligomers into uniaxially oriented monodomain films on coumarin‐based photoalignment layers
Authors: Wei Simon K.‐H. , Zeng Lichang , Marshall Kenneth L. , Chen Shaw H.
Published: March 2011

Photoalignment layers comprising Polymer 1 were prepared using linearly polarized UV‐irradiation for chloroform‐vapor annealing of π‐conjugated oligomer films, both processes conducted at room temperature. The resultant uniaxially oriented monodomain films exhibited S = 0.74 (at Pr = 0.90) and 0.82 (at Pr = 0.95) in OF and OF2T films, respectively, apparently limited by film dewetting in comparison to S = 0.82 ± 0.01 from thermal annealing on rubbed polyimide alignment and Polymer 1 photoalignment layers. The time to arrive at maximum S values varied from 5–10 s to 6–8 min on rubbed polyimide alignment layers and Polymer 1 photoalignment layer, respectively, because of favorable π–π interactions enhanced by rubbing. In contrast, PF2T could not be oriented on either type of alignment layers after annealing under saturated chloroform vapor up to 14 h. Annealing of an OF2T film under saturated chlorobenzene vapor at room temperature permitted lyotropic nematic mesomorphism to be observed in situ, which is equivalent to thermotropic nematic mesomorphism as the driving force behind thermal annealing. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Mechanical strength and water resistance of paperboard coated with long chain cellulose esters
Authors: Havimo M. , Jalomäki J. , Granström M. , Rissanen A. , Iivanainen T. , Kemell M. , Heikkilä M. , Sipi M. , Kilpeläinen I.
Published: March 2011

Long chain cellulose esters (LCCE) are bio‐based materials, which are biodegradable, can be prepared from renewable materials, and have relatively good mechanical and barrier properties. In this study, we tested the feasibility of various LCCEs as a coating material for paperboard. Cellulose hexanoates (C6) and cellulose palmitates (C12) of various degrees of substitution were synthesized and tested as barriers. Coating of paperboard was performed by dissolving the LCCE to chloroform or acetone, and levelling the coating with wire bar coater to the surface of the paperboard. The coating gave hydrophobic surface to the paperboard, and significantly improved the water vapour barrier properties. Cellulose palmitate coatings were better water vapour barriers than cellulose hexanoate. However, polyethylene‐coated paperboard had markedly lower water vapour transmission rate than LCCEs used in this study. The LCCE coatings slightly improved the tensile strength of the paperboard. In order to find out the suitability of LCCEs for extrusion coating, the thermal behaviour of LCCEs were also assessed. The cellulose hexanoate starts to degrade thermally at 280°C and cellulose palmitate at temperature 320°C. These materials do not have a clear melting point, but they behave as amorphous materials, and turn gradually to viscous form as temperature increases from 170°C to 200°C. This indicates possibilities to use them in extrusion coating, at least if the viscosity is improved with suitable additives. Copyright © 2011 John Wiley & Sons, Ltd.
THE EFFECTIVENESS OF TISSUE BIOPSY AS A MEANS OF ASSESSING THE PHYSIOLOGICAL CONSEQUENCES OF FISHWAY PASSAGE
Authors: Pon L. B. , Hinch S. G. , Suski C. D. , Patterson D. A. , Cooke S. J.
Published: March 2011

Beyond assessing passage efficiency of fishway structures, there is a need to examine the sublethal impacts of passage on the physiological condition of fish. Muscle and plasma samples were collected from pink salmon (Oncorhynchus gorbuscha) at four sites along a fishway and were compared in order to assess the effectiveness of these methods as they apply to fishway studies. Both plasma and muscle tissue revealed changes consistent with anaerobic activity when fish sampled from within the fishway were compared with field baseline estimates taken from fish sampled 50 m downstream of the fishway entrance. Plasma Cl−, osmolality and haematocrit increased significantly (all p < 0.01) during ascent, whereas muscle glycogen and phosphocreatine declined (both p < 0.03). Both plasma and muscle tissue collected from fish sampled at a site just upstream of the fishway showed physiological profiles that were consistent with metabolic recovery relative to physiological conditions during passage: plasma lactate, haematocrit and muscle lactate had decreased (all p < 0.01), and muscle phosphocreatine increased (p = 0.01). When examining the physiological changes that specifically occurred between the two sites within the fishway structure, we found no differences in plasma samples, but muscle lactate and water content both showed significant changes (both p < 0.05). These results are consistent with the greater sensitivity of muscle tissue than of blood to exercise‐related physiological changes and highlight the usefulness of sampling muscle tissue for assessing fishways that ascended in a short time. Fishway studies could benefit from greater inclusion of physiological tools and approaches to identify the costs of passage and areas of difficulty within a fishway. Copyright © 2011 John Wiley & Sons, Ltd.
Precipitation of Copper Sulfide and its effect on the Microstructure and Properties of Steel
Authors: Liu Z. Z. , Kuwabara M. , Li B. H. , Kobayashi Y. , Nagai K.
Published: March 2011

The precipitation behavior of copper sulfides in strip cast and isothermal heat treated low carbon steel were investigated by SEM and TEM. The copper sulfides were classified as duplex inclusion of oxide and sulfide (OS), plate‐like copper sulfide (PS), shell‐like copper sulfide (SS), and nano‐scale copper sulfide (NS). Based on the experimental results, the formation mechanisms of these copper sulfides, as well as the effects of cooling rate and constituentes of steel on the competitive precipitation between copper sulfide and manganese sulfide were discussed. The effects of coppers sulfides on the mechanical properties as well as the formation of acicular ferrite in steel were also introduced.
Peer educators in a theoretical context: Emerging adults
Authors: Dennett Carolyn G. , Azar James A.
Published: March 2011

The peer educator and the directing supervisor encounter a variety of challenges within a higher education organization. Both theory and examples of practice are provided to give a clear understanding of some of the issues they face.
Peer educators in critical campus discourse
Authors: Voorhees Rhondie , Petkas Steven N.
Published: March 2011

The Common Ground Dialogue Program is an innovative peer education program designed to teach skills for engagement through exploration of contemporary multicultural societal dilemmas. In this chapter, the authors describe their work with the program and lessons learned about strategies for effective peer leadership.
Peer educators responding to an institutional challenge: Off‐campus student services
Authors: Hintz James R.
Published: March 2011

Peer education programs have emerged at many institutions to address issues and challenges that off‐campus students face and cause while living in neighborhoods adjacent to colleges and universities.
The future of peer education: Broadening the landscape and assessing the benefits
Authors: Williams Lee Burdette
Published: March 2011

The Editor considers the opportunities presented by peer education for deeper learning, personal development, and strengthening campus community.
Hydrolytic Ring Opening Reactions of Pyromellitic Dianhydride for Divalent Transition Metal Carboxylate Complexes
Authors: Tao Bo , Xia Hua , Huang Chao‐Xin , Li Xiao‐Wei
Published: March 2011

The hydrolytic ring opening reactions of pyromellitic dianhydride is an effective method to prepare transition metal carboxylate complexes. In this paper, two dinuclear complexes [Ni2(2,2′‐bipy)2(btec)(H2O)6]·2H2O (1) and [Cd2 (phen)4(H2O)2(H2btec)]·H2btec·2H2O (2) (H4btec = 1,2,4,5‐benzenetetracarboxylic acid, phen = 1,10‐phenanthroline, and 2,2′‐bipy = 2,2′‐bipyridine) were synthesized by slow diffusion methods and their structures were determined byX‐ray structure analysis. In both structures metal atoms are in distorted octahedral environments and they are linked by bis‐monodentately coordinated 1,2,4,5‐benzentetracarboxylate ligands as bridging units. The crystalline compounds, which are insoluble in water as well as common organic solvents, have been characterized in the solid‐state by elemental analysis, thermogravimetric analysis, IR, and diffuse reflectance UV/Visspectroscopy. Moreover, the study of the physical properties of complex 2 demonstrates that it exhibits blue fluorescence emission in the solid state at room temperature.
Verallgemeinerte Luenberger‐Beobachter für lineare Deskriptorsysteme
Authors: Müller P. C.
Published: March 2011

Der Entwurf von Beobachtern für lineare Deskriptorsysteme beruht bisher entweder auf einem singulären Übertragungssystem oder auf einem regulären Luenberger‐Beobachter unter der scharfen Voraussetzung der R‐ und I‐Beobachtbarkeit. In diesem Beitrag wird aufgrund der Weierstrass‐Kronecker‐kanonischen Darstellung eines linearen Deskriptorsystems gezeigt, wie unter alleiniger Voraussetzung der R‐Beobachtbarkeit ein Luenberger‐Beobachter reduzierter Ordnung zur Schätzung der Deskriptorvariablen entworfen werden kann. Die Besonderheit dabei ist, daß in gewissen Fällen auch Ableitungen der Steuereingangsgrößen dem Beobachter aufgeschaltet werden müssen. Insgesamt liegt damit ein wesentlich einfacher vorzunehmender Beobachter‐Entwurf vor.
Ein Vorschlag für eine Normalform von Deskriptorsystemen
Authors: Kurt Schlacher , Werner Haas , Andreas Kugi
Published: March 2011

Dieser Beitrag behandelt geometrische Methoden für die Analyse und den Entwurf von Regelungssystemen, deren Regelstrecke durch implizite, gewöhnliche Differentialgleichungen beschrieben werden, die linear in den Zeitableitungen sind. Basierend auf Methoden der äußeren Differentialrechnung werden diese impliziten Systeme in eine spezielle Form so übergeführt, daß sich grundlegende Analyse‐ und Entwurfsmethoden expliziter Systeme auf diesen Fall erweitern lassen. Im speziellen wird dies für das Erreichbarkeits‐ und Beobachtbarkeitsproblem, sowie für die Methoden der Eingangs‐Ausgangs‐ und Eingangs‐Zustands‐Linearisierung gezeigt.
Transient Numerical Simulation of Combustion in Inert Porous Media
Authors: Knabner P. , De Neef M. J. , Summ G.
Published: March 2011

This paper presents methods for the time‐dependent numerical solution of a two‐dimensional model governing combustion an inert porous media. The spatial discretization is based on a mixed finite element method for the flow problem and a cell‐centered finite volume scheme for the transport equations. Some results of numerical simulations show the influence of a jump in the porosity of the solid matrix on the localization of the combustion zone.
Designs of experiments in a polynomial regression when there is uncertainty about the degree
Authors: Dette Holger
Published: March 2011

If an experimenter wants to determine the degree of a polynomial regression on the basis of a sample of observations, Anderson (1962) showed that the following method is optimal. Starting with the highest (specified) degree the procedure is to test in sequence whether the coefficients are 0. In this paper optimal designs for Anderson's procedure are described explicitly. The optimal design maximizes the minimum power of a given set of alternatives.
The Multi‐Point Approximation Method in a Parallel Computing Environment
Authors: Keulen Fred Van , Toropov Vassili V.
Published: March 2011

The Multi‐point Approximation Method (MAM) replaces an optimization problem by a sequence of approximate ones. The corresponding approximate response functions are sample and often explicit in terms of the design variables. Each step of the Optimization process involves several implicit function evaluations before identification of the approximation functions by weighted least‐squares fitting takes place. The present paper addresses alternative planning of implicit function evaluations in order to enhance both robustness and efficiency in parallel computer environments, especially heterogeneous networks.
New Method of Identification of Mechanical Properties of Composite Materials
Authors: Rikards R.
Published: March 2011

A new numerical‐experimental method for identification of mechanical properties of composite materials is outlined. For the first time it is proposed to use the design of experiments to solve the identification problems. The basic idea of the proposed approach is that a simple mathematical model is determined only by the information about the response of the material in the reference points of the design of experiments. Therefore, a significant reduction (about 50‐100 times) of calculations of identification functional can be achieved in comparison with using a conventional methods of minimization. Examples of identification of elastic properties of laminated composites from the measured eigenfrequencies of the rectangular plates are discussed.
Discussion of d'Alembert's Principle for Non‐Smooth Unilateral Constraints
Authors: Glocker C. H.
Published: March 2011

In optimization theory the tangent cone and the contingent cone are used to classify the regularity properties of sets at a given point. If both cones coincide the set is called tangentially regular, otherwise we speak of a reentrant corner. A third cone, the normal cone, is defined by the polarity with respect to the tangent cone, which is commonly egresses an terms of a variation inequality. This concept, directly applied to rigid body dynamics, allows an easy classification of possible Constraints. We define constraint forces to be the elements of the normal cone, whereas virtual displacements have to be taken from the contingent cone. A combination of both, the constraint forces and the virtual displacements, consitutes the Principle of d'Alembert as long as the constraints are tangentially regular. In the other case alternative formulations will be discussed.
Symmetries and scaling‐laws in turbulence
Authors: Oberlack M.
Published: March 2011

A new turbulence approach based on Lie‐group analysis is presented. It unifies a large set of self‐similar solutions for the mean velocity of stationary parallel turbulent shear flows. The theory is derived from the Reynolds averaged Navier‐Stokes equations, the fluctuation equations, and the velocity product equations, which are the dyad product of the velocity fluctuations with the equations for the velocity fluctuations. For the plane case the results include the logarithmic law of the wall, an algebraic law, the viscous sublayer, the linear region in the centre of a Couette flow and in the centre of a rotating channel flow, and a new exponential mean velocity profile that corresponds to the mid‐wake region of high Reynolds number flat‐plate boundary layers. The algebraic scaling law conforms to both the centre and the near wall regions of turbulent channel flows. For a non‐rotating and a moderately rotating pipe about its axis an algebraic law was found for the axial and the azimuthal velocity near the pipe‐axis with both laws having equal scaling exponents. In case of a rapidly rotating pipe a new logarithmic scaling law for the axial velocity is developed.
Multiscale Modeling of Highly Heterogeneous MMCs
Authors: Antretter T. , Fischer F. D. , Plankensteiner A. F. , Rammerstorfer F. G.
Published: March 2011

A hierarchical modeling concept incorporating different material descriptions at appropriate length scales is presented and applied to High Speed Steel (HSS) in order to quantify the overall thermomechanical behavior. Such materials can be viewed as particulate metal matrix composites (MMCs) with a strongly clustered arrangement of linear‐elastic carbidic particles in an elastic‐plastic martensitic‐austenitic matrix. On the mesoscale mean field methods are used to describe the effective material behavior of the mesophases depending on instantaneous constituent properties and local fields. Plastic strains in the matrix show a strongly inhomogeneous distribution which hardly can be predicted by standard micromechanics based methods neglecting the mesostructure. On the microscale the influence of the geometrical paramters describing the stress distribution inside the inclusions is studied by means of quasi‐random structure unit cells. Statistical methods are employed in order to quantify the relationship between particle size and their probability of fracture. The role of residual stresses due to quenching of the material prior to mechanical loading and their beneficial effect on the particles is emphasized.
A‐Posteriori Error Estimation and Adaptivity for the Finite Element Method Using Duality Principles
Authors: Cirak F. , Ramm E.
Published: March 2011

The present study introduces the concept of error estimation for locally and globally defined variables an structural mechanics. As a basic component of the formulation a dual problem specifically designed for the variables in mind is defined. The influence of the errors of the entire spatial or temporal domain on the local error of the specific variable is filtered out by the corresponding dual (influence) problem. The duality techniques are related to the principle of Betti ‐Maxwell and can be used for error estimation with respect to various locally or globally defined variables.
An Adaptive Finite Element Method for Problems in Perfect Plasticity
Authors: Rannacher R. , Suttmeier F. T.
Published: March 2011

We present recent progress in the development of an self‐adaptive finite element solver for problems in elastoplasticity. The adaptive mesh generation is based on a posteriori error estimates which are derived via duality arguments yielding bounds for functionals of the error. The application of this approach for the stationary Hencky model is well understood. Its formal extension to the non‐stationary Prandtl‐Reuss model within the context of an implicit load‐stepping process works surprisingly well. This effect is theoretically explained.
Adaptive Refinement of the Generalized Cell Mapping
Authors: Guder R. , Kreuzer E.
Published: March 2011

For the prediction of the long term behavior and global analysis of nonlinear dynamical systems the generalized cell mapping is an efficient and powerful numerical tool. The only drawback of this method is the enormous computational effort for higher‐dimensional systems. We overcome this problem by several adaptive refinement steps of a very rough starting cell grid, where the adaption is controlled by the long‐term dynamics of the system. We illustrate the efficiency by examples.
A Comparison of Various Methods for the Stability Analysis of the Relative Equilibria of a Rotating Pendulum
Authors: Krupa M. , Schagerl M. , Steindl A. , Steiner W. , Troger H.
Published: March 2011

With the example of a rotating pendulum four different methods for the stability analysis of its relative equilibria are compared. In particular new developments in the stability theory of symmetric Hamiltonian systems like the Reduced Energy Momentum method are compared with classical approaches such as Routh's method.
Gedächtniseffekte in zirkulierenden Strömungen
Authors: Böhme G.
Published: March 2011

Elastische Flüssigkeiten besitzen ein Gedächtnis für frühere Deformationszustände. Geeignete integrale Stoffmodelle verknüpfen den aktuellen Spannungszustand in der Flüssigkeit mit der materiellen Verzerrungsgeschichte, die längs der Bahnlinien erlebt wurde. Bei zirkulierenden Strömungen, die im Eulerschen Sinne stationär sand, genügt ein einziger Bahnlinienumlauf, um die gesamte Vergangenheit zu, “bewältigen”. Diese Erkenntnis und ihr Nutzen bei der numerischen Simulation mehrdimensionaler Strömungen werden hier näher erläutert. Beispielhaft werden Gedächtniseffekte anhand einer axialsymmetrischen Strömung diskutiert.
Strömungseigenschaften und Stoffeigenschaften von Polymerlösungen
Authors: Gampert B. , Hahn H. , Eich T.
Published: March 2011

In dieser Arbeit werden rheologische und rheooptische Untersuchungen zur Charakterisierung des Fließverhaltens von Polymerlösungen vorgestellt. Weiterhin wird das fluiddynamische Verhalten, der Polymerlösungen, in verschiedenen Strömungsfeldern untersucht. Die Auswertung der Experimente ergab, daß insbesondere die Lösungsstruktur sowie die viskoelastischen Materialeigenschaften, dos Fließverhalten, entscheidend beeinflussen können.
The Dissipation‐Inequality of Rate‐Independent Thermoplasticity
Authors: Bertram A.
Published: March 2011

In real processes involving large plastic deformations a major part of the stress power will be dissipated and involves thermodynamical changes that cannot be neglected. A framework for the description of thermoplastic processes based on the notion of isomorphic thermoelastic ranges is suggested. Within this framework, consistent flow and hardening rules as well as necessary and sufficient conditions for the second law to hold are derived for the rate‐independent case.
Some examples of Mathematical Modelling in Glass Industry
Authors: Mattheij R. M. M.
Published: March 2011

The evolution of viscous gobs is considered as they appear in glass morphology. It is shown how this can be modelled by a Stokes equation. Two applications are considered in more details. One is the densification process through sintering and the other the pressing of a glass in a mould.
Analysis and Simulation of Nonwoven Textures
Authors: Scholz Michael , Claus Bernhard
Published: March 2011

Nonwoven fabrics are widely used in a variety of different fields. They consist of bonded fibers which are more or less randomly distributed (in particular they are not woven), and in all applications the homogeneity of the fabric is an important feature which is critical to the quality of the fabric. We evaluate the homogeneity (cloudiness) by decomposing an image of a nonwoven into different scales, evaluating the homogeneity on each scale and combining these results into a single number which represents a measure of the overall „cloudiness”︁ of the fabric in the image. Simulation of images of nonwovens with a predefined degree of homogeneity (on each of the considered scales) is of importance because these images can be used to calibrate the image acquisition system. In particular we use Markov Random fields to generate the characteristic texture for each scale after first identifying the respective model parameters. We then combine these different images to yield an „artificial”︁ image of a nonwoven.
Biorthogonal wavelets and approximations of operators
Authors: Guichaoua M. , Liandrat J.
Published: March 2011

We present an explicit scheme, based on wavelets, for the approximation of evolution equations of type δU/δt/ + δ/δx (f(U)) = 0. It is constructed using a Taylor scheme for the time approximation and a wavelet method for spatial approximation. This scheme is shown to be stable and convergent under a specific stability condition and can be implemented fast on c‐structured wavelet spaces of approximation thanks to the introduction of scheme dependant biorthogonal multiresolution analyses.

A scale dependent time step version is presented that allows a strong reduction of complexity. For discontinuous solutions, a non linear version has been proposed and numerically tested.
Friction and Wear at Tractive Rolling of Cylinders
Authors: Deters L. , Engel St. , Proksch M.
Published: March 2011

Based on the fundamentals of tractive rolling contact mechanics, a method is described which is suited for calculating traction coefficients. Both the deformation and the adhesion component of friction are taken into consideration. It is demonstrated that the maximum traction coefficient is not a constant, but takes different values under various load conditions as a result of changes in the micro‐geometrical pattern. Using the load‐specific maximum traction coefficient it is possible to predict a fairly accurate value of the traction coefficient of the tractive rolling contact.

In addition, the results of wear investigations are reported, and an approach to apply test results to the real wheel/rail system is described. The tests were carried out with materials common in railway design; in particular, R7 wheel material and standard‐grade 900A rail material were used. During the tests the normal force and the creep were varied. Wear investigations conducted on the test machine revealed that the relationship between friction work and wear volume is an almost linear function.
Solid Friction studied via Non‐Equilibrium Molecular Dynamics Computer Simulations
Authors: Kröger M. , Hess S.
Published: March 2011

The embedded atom method is adapted to study solid friction and the mechanical behavior of a model metal. The elastic properties of real metals are reproduced by a set of basic model potentials as revealed by analytic considerations. Non Equilibrium Molecular Dynamics NEMD computer simulations are performed to study the dynamics and structural changes of the model metal undergoing a process of solid friction and an uniaxial compression, in order to analyze, e.g. plastic yield and transient friction coefficients.
Numerical simulation of the formation of short pitch corrugation
Authors: Müller S. , Knothe K.
Published: March 2011

The formation of periodic wear patterns on the running surface of the rail has been observed for more than a hundred years. These wear patterns are the reason for unwelcome effects like noise and damage to the track. A high number of publications was concerned with the problem and most rail corrugation types can be explained to date [3]. Only the mechanism which leads to so called short pitch corrugation is not understood yet. Therefore, based on previous work [2] [5] a linear wheel‐track model has been developed to understand the formation of short pitch corrugation on tangent track. Numerical simulations have been undertaken with this model to analyse the corrugation process. Based on numerical results it is tried to explain why the corrugation pitch observed in practice vary little with train speed and it is shown how wheel‐rail parameters influence the proneness to corrugation.
Control of jets expansion by impeding jets
Authors: Denis S. , Delville J. , Garem J‐H. , Bonnet J‐P.
Published: March 2011

The principle retained to control the expansion of a jet, is bused here on the generation of streamwise vorticity by impeding jets. Experiments are performed in the mixing layer of two coaxial jets. The rectangular control jets arc placed all around the main jet. A parametric study is curried out, taking into account the number of control jets, their orientation, and the mass flow injected. The deformation of the, main jet is analyzed from velocity and temperature fields. A particular configuration is detailed, in terms of turbulence, by using four hot wires probe measurements.
Application of linear and nonlinear adaptive filters for the compensation of disturbances in the laminar boundary layer
Authors: Evert F. , Ronneberger D. , Grosche‐R F.
Published: March 2011

In order to delay the laminar‐turbulent transition in the boundary layer of airfoils the compensation of instability waves by artificially excited disturbances is studied. It turns out that also nonlinear processes occur in the spatial development of disturbances. This can be modeled by different types of nonlinear filter structures.
Trailing‐edge separation control on an aerofoil in low‐speed flow
Authors: Siller H. A. , Fernholz H. H.
Published: March 2011

Low‐speed wind‐tunnel experiments have been performed with a laminar aerofoil. Loudspeakers mounted inside the wing generate an oscillating cross‐flow through a spanwise slot in the upper surface of the aerofoil. The interaction of the oscillating flow with the flow over the aerofoil generates spanwise vortices. They enhance mixing and thereby add momentum to the region near the wall, so that boundary layer separation can be delayed, or a separated flow can be forced to reattach. The experimental results show that the maximum angle of attack of the aerofoil can be increased and lift forces can be enhanced by 10%.
Reduction of the On‐line Measurement and Control Expenses by Adaptive Stochastic Path Planning
Authors: Marti K. , Aurnhammer A.
Published: March 2011

In the optimal control of dynamic systems, e.g., in the control of industrial or service robots, the standard procedure is to determine first off‐line an optimal open loop control, and correct then the inevitable deviation of the trajectory or performance of the system from the prescribed values by on‐line measurement and control actions which may be very expensive. By adaptive stochastic path planning and control (ASPPC), i.e. by incorporating the available a priori and statistical information on the unknown model parameters of the dynamic system and its working environment into the off‐line and on‐line control process by means of stochastic optimization methods, the deviation between the actual and prescribed trajectory can be reduced to a large extent.
Porous media theory: A survey
Authors: De Boer
Published: March 2011

Recently some important new findings in the porous media theory have been worked out and partly published, which has led to a widely consistent theory. Thus, the time seems to be ripe to give a survey of the current state of the porous media theory.
Modelling of light weight porous metal materials
Authors: Ehlers W. , Droste A.
Published: March 2011

The low density related to the high strength of the structure and the special features of metal foams make it possible to develop special components. To design the properties of such components, for example, the finite element method offers a cheap possibility for simulations. This requires the development of a model for foamed materials. In contrast to a microscopic approach, the Theory of Porous Media (TPM) allows a macroscopic continuum mechanical description for metal foams on the the basis of a real or a virtual homogenisation over the microstructure. In particular, a gas‐filled solid material is taken into consideration including finite elastic and finite elasto‐plastic constitutive equations for the solid matrix combined with convenient constitutive relations for the viscous pore‐fluid and the respective interaction mechanisms between the constituents.
Asymptotics for Strongly Nonlinear Dynamical Systems
Authors: Awrejcewicz J. , Andrianov I. V.
Published: March 2011

Strongly nonlinear dynamical systems are analysed using a new asymptotic approach. Periodic oscillations of the systems with a polynomial nonlinearity are considered and a period of strong nonlinear oscillations of the mathematical pendulum is estimated analytically.
Random vibrations of the frame foundation
Authors: Bryja D. , Mironowicz W.
Published: March 2011

The foundation for the machine in the form of the flat frame made of thick bars is examined in the paper. The frame is modelled by FEM with the application of the original Timoshenko beam element. The machine is treated as the nondeformable block viscoelastically supported on the frame. The dynamic load is random and has the form of the periodic series of short duration shocks. The solution of the problem is presented in the correlation theory sphere, using the influence response function of the multi‐degree‐of‐freedom system.
Freiheitsgradreduktion bei Finite Element Modellen mit Hilfe der dynamischen Steifigkeit
Authors: Eichel Dirk , Waller Heinz
Published: March 2011

Für ein mat der dynamischen Kondensation berechnetes Gleichungssystem
equation image
ward durch Abspaltung eines Teils der Eigenwerte von F(δ) eine Formulierung mit vom Grad minimalen Polynommatrazen angegeben.
Total strain energy density parameter for fatigue analysis
Authors: Golos K. M.
Published: March 2011

In the paper a new damage parameter‐total strain energy density for fatigue analysis has been examined. The parameter can be applied to both Masing and non‐Masing material description. The relationships of the proposed damage parameters for both types of material description have been shown. The parameter has been applied to fatigue experimental data for carbon steel St5, A516 steel and titanium alloy W13–1. Comparison has shown to be in good agreement.
Application of a New Regularization Technique to Localized Failure
Authors: Lambrecht M. , Miehe C.
Published: March 2011

The simulation of localized failure, e.g. in the form of shear bands, yields the typical mesh‐dependent post critical results within standard finite element formulations. We here propose a new regularization technique based on a micromechanically motivated approach which overcomes this problem. The key idea here is the introduction of a micro‐structure at a typical Gauss‐point of the finite element mesh which befits in the form of an assumed fluctuation field when macroscopic localization occurs. A regularization effect is obtained when the size of the micro‐structure is scaled to the volume associated with a Gauss‐point of the finite element mesh.
Improvements for finite‐element implementation of the Gurson Model
Authors: Mahnken R.
Published: March 2011

In this contribution three modifications for the plastic potential of the Gurson model are proposed, which give, from the numerical point of view, some improvements for the finite‐element implementation. Firsty a linear representation is used, which shows superior convergence property in the local iteration procedure compared to the original quadratic representation. Furthermore the cosh‐function appearing in the original formulation is replaced by a modified Cosh‐function, thus avoiding the overflow effect in the local iteration procedure for in‐between values. Additionally a smoothing technique is applied to the modified void volume function f*]f[ introduced by Tvergaare & Needleman ]3[. A numerical example illustrates the advantage of the proposed approach.
Non‐local Strength Conditions Based on Generalized δc Cohesive Models
Authors: Mikhailov S. E.
Published: March 2011

Generalization of the Leonov‐Panasyuk‐Dugdale δc cohesive model applicable not only for cocks tips but also for any internal or boundary point is described. These models are interpreted also as non‐local strength conditions and can be used for description of strength small scale effects, for stress fields with stress singularities other than the usual crack tip square root singularity (e.g. for corner points), for bodies with smooth and singular stress concentrators.
Remeshing Techniques and Data Transfer in the Adaptive FEM
Authors: Ehlers W. , Ellsiepen P. , Ammann M.
Published: March 2011

A major problem in using the finite element method (FEM) for solving numerous engineering problems is the assessment of discretisation errors and the design of a suitable mesh. To overcome this problem, adaptive finite element methods have been developed. In this paper, we illustrate a general h‐adaptive procedure and we present a comparison of the performance of three different density functions.
Elastically deformable mechanisms
Authors: Franitza D. , Landgraf G. , Modler‐H. K.
Published: March 2011

A large number of applications in engineering of mechanisms are geometrically non‐linear. A theory which deals with a rate‐field‐problem using the transfer matrix procedure based on macro elements is them fore developed. Velocities in connection with the integration procedure according to Runge‐Kutta 4‐th order for state variables of a prismatic beam are calculated. Element crossings were included and sliding joints were considered.
Finite Element Analysis of Piezothermoelastic Smart Structures
Authors: Andreas Görnandt , Ulrich Gabbert
Published: March 2011

In many applications of piezoelectrically controlled smart structures, the functionality of the system has to be guaranteed in extremely hot and cold thermal environments. Consequently, the thermal effect is very important and must be taken into account in the design process of such structures. This results in a fully coupled formulation of piezothermoelastic material behaviour. Based on a weak formulation of the equilibrium conditions and the coupled constitutive equations of this three field problem a general finite element concept is presented. Static as well as dynamic responses of combined thermal, electric and mechanical excitations are considered. An iterative solution strategy is proposed to solve the coupled field problem in an effective way.
Dynamics of shear frames with tuned liquid column dampers
Authors: Hochrainer M. J. , Adam C.
Published: March 2011

Tuned liquid column dampers (TLCD) are passive energy absorbing devices to control vibrations of buildings placed e.g. in an earthquake environment. The objective of this paper is the study of the influence of TLCD on the response of shear frames. For the analysis the TLCD are modeled as SDOF oscillators. For the linear system an analytical optimisation is given, bared on a decomposition into substructure modes of the shear frame. To determine the quality of the analytical solution a numerical optimisation is performed The results indicate a good agreement between the outcome of both optimization methods and indicate as well that TLCD reduce the response of earthquake excited buildings quite effectively.
On the theory of fourth‐order tensors and their application in large strain elasticity
Authors: Itskov M. , Basar Y.
Published: March 2011

This paper briefly presents some important aspects of the theory of fourth‐order tensors proposed in ]I[. The theory involves an operation algebra, differentiation rules, eigenvalue problems, an application to isotropic tensor functions and some other relevant problems. A most important application field the theory finds in large strain elasticity, where fourth‐order tensors appear as elastic moduli.
Simulation of Sheet Metal Forming on the Basis of the Deformation Theory and Optimization Techniques
Authors: John R. , Ulbricht V. , Brummund J.
Published: March 2011

The basic approach for the simulation of the sheet metal forming in this paper is a reduction of the whole process to a mapping between the undeformed and the deformed configuration. One major aim consists in a fast code that can be used in the design stage of a workpiece. The approach has to permit first statements to the producibility of the workpiece. Since the configurations are given, the central question raises is the placement of a material points in the deformed configuration. In this approximation the necessary consideration of plastic material behaviour is possible only on the basis of the deformation theory of plasticity. The present paper is restricted, for simplicity, to the membrane stress state in the shell and to isotropic material behaviour.
On local error estimators for non—self‐adjoint boundary value problems
Authors: Steeb Holger , Cirak Fehmi , Ramm Ekkehard
Published: March 2011

The study focuses on an adaptive finite element method for the stationary convection‐diffusion problem with dominant convection. A short review of the standard and stabilised finite element method will be given. The adaptivity scheme is based on an a posteriori error estimator for local quantities. In this error estimation strategy for a non‐self‐adjoint boundary value problem we introduce duality techniques or in engineering words we use an influence function related to the reciprocal theorem of Betti & Mmaxwell to estimate the local errors. With this type of error estimator, the pollution effect in the domain Ω caused by shock fronts or boundary layers could be captured.
Transient free surface flows via a stabilized ALE finite element method
Authors: Schmidt J. , Wall W. A. , Ramm E.
Published: March 2011

Free surface problems appear in a wide range of industrial and engineering applications, e.g. when modeling sloshing of fluid in a container or when tracking the free surface evolution in casting and molding processes. A finite element technique is presented to study time‐dependent large free surface motions of viscous, incompressible fluids. The approach is based upon an arbitrary Lagrangean‐Eulerian (ALE) representation of kinematics and field equations, i.e. continuum mechanical conservation laws. Both convective effects and equal‐order interpolation for velocities and pressure are stabilized in a Galerkin least‐squares sense. This leads to a fully stabilized finite element method (FEM) for the governing instationary incompressible Navier‐Stokes equations. The algorithmic setup is complemented by a combination of the stabilized FEM with direct time integration procedures and fixed point‐like iterative schemes. The performance of the overall algorithm is demonstrated with the help of selected two‐dimensional numerical examples.
Adaptive Mixed Finite Element Method for Reissner‐Mindlin Plates
Authors: Kerstin Weinberg , Carsten Carstensen
Published: March 2011

We use a modified mixed finite element method for the Reissner‐Mindlin plate model to study its numerical properties in practical use. We derive an a posteriori error estimate to control adaptive mesh‐refining algorithms and study the question of reliability. Numerical examples prove the new scheme efficient.
Transient Resonance Oscillations of a Turbine Blade with regard to Non‐Linear Damping Effects
Authors: Irretier H. , Balaschov D.
Published: March 2011

Transient, forced vibrations of a turbine blade are modelled. Dissipative effects such as material damping, aerodynamic damping and damping at interfaces are taken into account. For the modelling of these effects the set of isolated weakly non‐linear single degree of freedom oscillators with slowly varying natural frequencies and small non‐linear damping is used. The non‐linear damping law considers as a sum of elementary power functions with respect to the modal velocity. The Krylov‐Bogoljubov asymptotic method is applied for the investigation of the transient resonance response which is induced by the sweep of the excitation frequency through the system natural frequency during run‐up or run‐down. Numerical calculations are provided to demonstrate the validity of the first asymptotic approximation.
Hopf Bifurcation Generated by Small Nonlinear Terms
Authors: Krasnosel'skii A. , Mennicken R. , Rachinskii D.
Published: March 2011

We study the problem of generation of small cycles from the equilibrium in autonomous quasilinear systems depending on a parameter. In contrast to the usual situations, the linearized equation is degenerate for all parameter values (not only for the bifurcation point). Therefore the existence of small cycles is determined by small nonlinear terms. The main example is an equation where the principal degenerate linear part is independent of the parameter. We suggest sufficient conditions for the existence and stability of small cycles for higher‐order scalar equations. The results are based on topological methods and methods of monotone operators.
Comfort and Stability of Vehicles with Stochastic Excitation
Authors: Mehl V. , Pfister F.
Published: March 2011

An efficient method to determine comfort and road holding stability of vehicles is discussed. By using the frequency spectrum of the vertical excitation, modeling of a stochastic road becomes superfluous. In the case of a linearized model, the frequency response yields the acceleration of the chassis and the dynamic wheel forces. They are used as measures for comfort and stability, if applied to the spectrum of the road excitation. In order to include buffer effects with nonlinear characteristics, an approximation method is discussed to determine the equivalent stiffness coefficient of a, linear spring.