bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Korean Parkinson's disease family with the LRRK2 p.Tyr1699Cys mutation showing clinical heterogeneity
Authors: Kim Ji Sun , Cho Jin Whan , Shin Hyeeun , Lee Won Yong , Ki Chang‐Seok , Cho Ah Ra , Kim Hee‐Tae 
Published: December 2011

AbstractBackground:Although leucine‐rich repeat kinase 2 (LRRK2) is the gene most commonly linked to autosomal dominant inherited Parkinson's disease (PD), there have been few reports in Asia, probably because of population‐specific differences in allele frequencies.Methods:We identified a large Korean PD family with the p.Tyr1699Cys mutation in LRRK2 and analyzed genealogical, clinical, and genetic data from the family.Results:Although the clinical findings of these patients were indistinguishable from those of patients with sporadic PD, the patients with the p.Tyr1699Cys mutation demonstrated clinical heterogeneity including differences in age at onset, rate of disease progression, clinical phenotype, and prognosis.Conclusions:This is the first report describing an Asian PD family with the p.Tyr1699Cys mutation in LRRK2. The affected members of this family showed clinical heterogeneity. © 2011 Movement Disorder Society
Multi‐parametric approach to identify coffee components that regulate mechanisms of gastric acid secretion
Authors: Rubach Malte , Lang Roman , Seebach Elisabeth , Somoza Mark M. , Hofmann Thomas , Somoza Veronika 
Published: December 2011

ScopeChlorogenic acid (CA), caffeine (CAFF), pyrogallol (PYR), catechol (CAT), βN‐alkanoyl‐hydroxytryptamides (C5HT) and N‐methylpyridinium (N‐MP) were evaluated for their influence on mechanisms of gastric acid secretion as single compounds and in biomimetic mixtures.Methods and resultsCompounds were tested in coffee representative concentrations. Human gastric cancer cells (HGT‐1) were used to study the proton secretory activity by Ussing chamber experiments and FACS analysis. For activation of EGFr, Akt1, ERK1/2, ATF‐2 and cAMP levels, we performed pathway screening assays. Time‐dependent expression of related genes were determined by real‐time PCR. Part of the data was used for neural network modeling to identify the most relevant compounds. N‐MP increased the expression of the anti‐secretory somatostatin receptor by 114%, whereas C5HT decreased its expression by 52%. N‐MP down‐regulated the pro‐secretory CHRM3 receptor by 36% and the H+,K+‐ATPase by 36%. CAFF stimulated the secretory activity in the functional assays, whereas N‐MP and CA decreased proton secretion. After applying a pathway analysis, we were able to discriminate between CAFF, CA, CAT, C5HT, PYR and histamine‐activating EGFr signaling and N‐MP‐associated ERK1/2 signaling.ConclusionBy applying a multi‐parametric approach, N‐MP was shown to effectively down‐regulate mechanisms of gastric acid secretion in human parietal gastric cells.
An hp‐Adaptive FEM Procedure based on Continuous Sobolev Embeddings
Authors: Wihler Thomas 
Published: December 2011

AbstractSuitable continuous Sobolev embeddings are applied in order to derive smoothness estimators for adaptive hp‐refinements in the context of hp‐finite element methods. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation and feed‐forward control of a flexible parallel manipulator
Authors: Burkhardt Markus , Seifried Robert 
Published: December 2011

AbstractThe importance of lightweight constructions are steady increasing since they promise a low energy consumption together with higher movement speeds. However these demand modern, model‐based feed‐forward control designs. Especially the undesired vibrations due to the reduced overall stiffness of such manipulators have to be taken into account. A convenient way to model the dynamical behavior of systems that perform large, nonlinear motions superposed with small, elastic deformations is the floating frame of reference approach in a flexible multibody system. The application of the Newton‐Euler‐Formalism together with D'Alembert's principle to parallel manipulators results in a set of differential‐algebraic equations. Therefore, the consideration of the trajectory tracking problem with so‐called servo constraints appears to be promising. In case of a non‐flat system, the arising set of differential‐algebraic equations, which consists of the system dynamics, the holonomic loop closing constraint equations and the servo constraints embodies nontrivial dynamics. With an oblique projection, the embedded set of ordinary differential equations describing the internal dynamics can be obtained. The stability properties of these dynamics determines the complexity of the feed‐forward control design, as two‐point boundary value problems might have to be solved. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computation of bounded feed‐forward control for underactuated multibody systems using nonlinear optimization
Authors: Seifried Robert , Bastos Guaraci , Brüls Olivier 
Published: December 2011

AbstractUnderactuation occurs, when only some generalized coordinates have a control input. For end‐effector trajectory tracking a combined feed‐forward and feedback control is often a suitable approach. Feed‐forward control design based on an inverse model for underactuated multibody systems is presented. The starting point is the transformation of the multibody system into a nonlinear input‐output normal‐form. The inverse model follows from this and consists of chains of differentiators, driven internal dynamics and an algebraic part. Especially when using the end‐effector as system output the internal dynamics is often unbounded. In order to obtain a viable feed‐forward control, a bounded solution must be determined. For this task the internal dynamics is solved as a nonlinear optimization problem. Thereby, the coordinates of the internal dynamics define the objective function which is minimized. The equation of the internal dynamics must be fulfilled at each point of a discrete time grid. In addition continuity of the solution is achieved by adding as equality constraint an integration formula, e.g. trapezoidal rule. The optimization problem is then solved by a SQP‐method. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational Simulation of Bone Remodeling using Design Space Topology Optimization
Authors: Boyle Christopher , Kim Il Yong 
Published: December 2011

AbstractThe law of bone remodeling, commonly referred to as Wolff's Law, asserts that the internal trabecular bone adapts to external loadings, reorienting with the principal stress trajectories to optimize mechanical efficiency creating a naturally optimum structure. The current study utilized an advanced structural optimization algorithm, called design space toptimization (DSO), to perform a three‐dimensional computational bone remodeling simulation on the human proximal femur and analyse the results to determine the validity of Wolff's hypothesis. DSO optimizes the layout of material by iteratively distributing it into the areas of highest loading, while simultaneously changing the design domain to increase computational efficiency. The large‐scale simulation utilized a 175 µm mesh resolution with over 23.3 million elements. The resulting anisotropic trabecular architecture was compared to both Wolff's trajectory hypothesis and natural femur samples from literature using radiography. The results qualitatively showed several anisotropic trabecular regions that were comparable to the natural human femur. The realistic simulated trabecular geometry suggests that the DSO method can accurately predict bone adaptation due to mechanical loading and that the proximal femur is an optimum structure as Wolff hypothesized. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The linear mechanical model for hand‐arm system
Authors: Pop Aurora‐Felicia , Truţa Aurica , Bălcău Monica , Arghir Mariana 
Published: December 2011

AbstractThe paper presents a study regarding the linear mechanical models corresponding to hand‐arm system. These models was simplified unused the joint in wrist, elbow and shoulder. Also, for these mechanical models effectuated the equations system that would integrate, it obtained the solutions (displacements and velocities) finally. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and numerical investigation of different types of articular cartilage replacement materials
Authors: Zhou B. , Stoffel M. , Gavenis K. , Weichert D. 
Published: December 2011

AbstractThe aim of the presented work is to characterize the mechanical properties of different types of articular cartilage replacement materials. For this propose an elastic‐diffusion model is developed to identify the elastic and diffusion properties of the replacement materials. A set of unconfined compression tests were performed with several kinds of implants. By means of finite element simulation integrated with an user‐defined material model, the material parameters were identified. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Crack Propagation under Small‐Scale Yielding by means of a Non‐local GTN‐Model
Authors: Hütter Geralf , Linse Thomas , Mühlich Uwe , Kuna Meinhard 
Published: December 2011

AbstractToday, the local approach to fracture is widely applied to simulate the failure of specimens. For ductile damage processes the Gurson‐Tvergaard‐Needleman model is the quasi‐standard. In the last time non‐local extensions allowed a mesh‐size independent simulation of crack growth. However, most publications dealing with this subject focus upon the convergence regarding global quantities such as the load‐displacement relation. Minor attention is paid to the fields directly at the crack tip. Correspondingly, the interrelationship between the intrinsic length of the model and relevant microscopic damage processes at the crack tip is only partly established until now. In the present study the crack propagation is simulated for an implicitly gradient enriched GTN‐model within a boundary layer in order to overcome influences of the specimen geometry. The different stages of damage evolution are resolved by a fine mesh. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extended Finite Element Method for hygro‐mechanical analysis of crack propagation in porous materials
Authors: Leonhart Dirk , Meschke Günther 
Published: December 2011

AbstractIn computational structural analyses, strong discontinuities, such as propagating cracks in concrete structures, joints in rocks or shear bands in soft soils, the highly accelerated moisture transport in the opening discontinuities has to be taken into account. The paper is concerned with an Extended Finite Element model for the numerical representation of crack propagation in partially saturated porous materials. Based on an extended variational formulation for the simulation of moisture transport in cracks, enhanced approximations of the displacement field and the moisture flux across the discontinuity are adopted. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of fracture toughness of embrittled steels by means of the Small Punch Test
Authors: Rasche Stefan , Kuna Meinhard 
Published: December 2011

AbstractTo characterise the randomly distributed strength and fracture toughness of brittle steels, many specimens have to be destroyed. Since the Small Punch Test (SPT) needs only little material, it is a well suited experiment, when only a small volume of material is available. In this study the cleavage fracture of a ferritic steel at low temperature was investigated using the Beremin model. The failure probability is described with a 2‐parameter Weibull distribution in terms of the so‐called Weibull stress, which is calculated using an elastic‐plastic finite element stress analysis. While the transfer of Weibull parameters works well between similar geometries and loading conditions, it works bad in more general cases. Modifications of the Beremin model are necessary to overcome this problem. Recent publications consider a lower threshold value of the Weibull stress, which leads to a lower Weibull modulus and therefore to a stronger volume size effect of strength. The suitability of this approach to transfer cleavage fracture results from SPT to fracture mechanics specimens was investigated. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of crack formation in bonded lap joints using finite fracture mechanics on the basis of linear elasticity solutions.
Authors: Weißgraeber Philipp , Becker Wilfried 
Published: December 2011

AbstractIn this work, crack formation and the corresponding failure load of bonded lap joints is analyzed. The analysis is based on linear elasticity solutions for bonded lap joints and makes use of the finite fracture mechanics. A hybrid criterion is applied that states the spontaneous formation of a crack of finite size if a stress and an energy criterion are fulfilled simultaneously. The stress distribution of a linear elasticity solution is used for the stress criterion and for the calculation of the incremental energy release rate which is necessary for definition of the energy criterion. The resulting fracture criterion is compared to literature results and shows a good agreement. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy‐consistent time‐integration for dynamic finite deformation thermo‐viscoelasticity
Authors: Krüger Melanie , Groß Michael , Betsch Peter 
Published: December 2011

AbstractThe main goal of the present work is to develop two structure‐preserving time integrators, which are based on the works of Öttinger [1] (GENERIC formalism), Romero [2] (Thermodynamically consistent (TC) algorithm) and Groß [3] (enhanced hybrid Galerkin (ehG) method) and compare them with standard integrators considering a thermoviscoelastic double pendulum. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aspects on the Functional Optimization of an Industrial Robot Structure Implemented in Military Logistical Activities
Authors: Petrişor Silviu Mihai , Bârsan Ghiţă , Badea Dorel 
Published: December 2011

AbstractThe authors of the present paper outline aspects on the optimization of the a TR‐type industrial robot structure movements in order to generate the manipulation space to a flexible manufacturing cell with a parallel organization designed for the pallet and container operation of paint‐filled recipients. The paper contains the direct and inverted geometrical modelling of the robot structure using the 3*3 rotation matrix method and the algebra method. After knowing the characteristic point movement of the prehension device, graphics for the variation of the TR robot's general coordinates and for the trajectory of the prehension device's characteristic point of its work space were performed by using the Mathematica 6.0 soft. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Starting‐point strategy for interior‐point algorithms for lower‐bound shakedown analysis
Authors: Simon Jaan‐Willem , Weichert Dieter , Höwer Daniel 
Published: December 2011

AbstractShakedown analysis by using the lower‐bound theorem leads to computationally intensive nonlinear convex optimization problems with a large number of unknowns and constraints. Interior‐point algorithms such as recently developed by the authors have proven to be efficient for the solution of these problems. For convergence and efficiency of the iterative process of these algorithms the choice of the starting‐point is crucial. It should be inside of the feasible region and well‐centered for fast convergence.No general method exists for the construction of optimum starting‐points and only few investigations have been published on this issue. In this paper the physical meaning of the involved variables in shakedown problems is used to optimize starting‐points. The efficiency of the new method is illustrated by a numerical examples and comparison with an alternative approach. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Testing of screw joint hybrid composite materials
Authors: Żółkiewski Sławomir 
Published: December 2011

AbstractLaminate composite materials have excellent coefficient of stiffness to weight and because of this laminates are very widely applied often replacing raditional materials. A very interesting group of such a type materials are the hybrid ones. A main disadvantage of hybrid composite materials is the weak impact strength. The paper presents results of testing handmade screw joint hybrid composite materials. Results of testing are compared with numerical analysis based on the Finite Elements Method. Investigations were made on designed for this purpose the statical stresses laboratory stand. The testing specimens were made by a contact method (handmade laminating) and laminar mats or woven fabrics spreading (resin supersaturated). (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mode interactions and resonances of an elastic fluid‐conveying tube
Authors: Jurisits Richard , Steindl Alois 
Published: December 2011

AbstractWe consider the non‐linear two‐dimensional oscillations of a fluid conveying tube using dynamical bifurcation theory. The tube is clamped at the upper end, and at its free lower end a point mass is fixed. The tube is assumed to be slender and flexurally elastic, and its transversal motion is constrained by two symmetrically arranged springs. The flow rate of the incompressible fluid is used as a distinguished parameter in the problem. By determining the stability regions in parameter space, it is investigated whether Hopf and/or steady‐state bifurcations may occur, as it was found for similar cases in previous works [1,3]. The non‐linear behaviour close to the bifurcation points is analyzed. Of specific interest are low‐order resonances. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of interface effects in martensitic phase transformation
Authors: Goodarzi Mehdi , Hackl Klaus 
Published: December 2011

AbstractThis work is the succession of our micromechanical modeling of interface effects in martensite laminate microstructure based on energy methods. We augment our model with finite element implementation of a first‐order one‐dimensional laminate. The numerical results are in good agreement with observed morphology and accommodation patterns of microstructure. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of strain‐induced crystallization in natural rubbers
Authors: Poshtan Emad A. , Dargazany Roozbeh , Itskov Mikhail 
Published: December 2011

AbstractStrain‐Induced Crystallization (SIC) is a phenomenon characterized by a considerable increase in stiffness of natural rubbers. In this contribution, this phenomenon is studied in filled natural rubbers and a constitutive model of SIC is proposed. The influence of SIC on the mechanical behavior is described by means of the entropic strain energy subjected to a change due the crystallization. The distribution of crystallines is formulated on the basis of a statistical approach. Their contribution to the partial immobilization of polymer chains is accounted for by assuming the crystalline phase and the amorphous phase to be two separate networks. Finally, the model is compared with available experimental results of uniaxial tension tests. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FEM‐BEM coupling with non‐conforming interfaces
Authors: Rammerstorfer Franz , Schanz Martin 
Published: December 2011

AbstractIn order to treat wave propagation phenomena in coupled domains, a combined approach of Finite Element Methods (FEM) and Boundary Element Methods (BEM) is presented. The coupling is done within the framework of Tearing and Interconnecting methods (FETI/BETI), which are special non‐overlapping domain decomposition methods. The coupling conditions are incorporated in a weak sense, which allows non‐conforming interface discretization, i.e., the Mortar Method is used. A numerical example is given to verify the algorithm. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A solid shell finite element formulation to simulate the behaviour of thin dielectric elastomer structures
Authors: Zwecker Sandro , Klinkel Sven 
Published: December 2011

AbstractTo analyse the behaviour of thin structures of dielectric elastomer (DE) material a solid shell finite element is presented. The main characteristics of DEs are a non‐linear hyper elastic behaviour, the quasi‐incompressibility, and the ability to transform electric energy into mechanical work. Applying a voltage to thin DE structures may produce large elongation strains of 120‐380%. These large strains, the efficient electro‐mechanical coupling, and the light weight make DEs very attractive for the usage in actuators. Thus, there is a need for detailed research. With respect to the electro‐mechanical coupling a constitutive model is presented. An electric stress tensor and a total stress tensor are introduced by considering the electrical body force and couple in the balance of linear momentum and angular momentum, respectively. The governing equations are derived and embedded in the solid shell formulation. The element formulation is based on a Hu‐Washizu mixed variational principle using six independent fields: displacements, electric potential, strains, electric field, mechanical stresses, and dielectric displacements. It allows large deformations and accounts for physical nonlinearities to capture two of the main characteristics of DEs. The shell element could be applied for the modelling of arbitrary curved thin structures. The ability of the present element formulation is demonstrated in several examples. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization with uncertain input data
Authors: Kreuter Daniel , Sepahvand Kheirollah , Beitelschmidt Michael 
Published: December 2011

AbstractIn this paper a fast homogeniztaion technique is used to calculate effective material parameter if the input data are uncertain. The technique uses the Polynomial Chaos Expansion to approximate the distribution of the uncertain input data und the calculated output data. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical modeling of atomistic‐to‐continuum coupling based on bridging domain method
Authors: Marenić Eduard , Sorić Jurica , Tonković Zdenko 
Published: December 2011

AbstractNano‐submodeling is an approach that enables insertion of nano‐refined submodel (atomistic) in the global model (continuum). In this work analysis of the spurious effects that may arise in the concurrent atomistic‐to‐continuum coupling is performed. The coupling is based on the overlapping domain decomposition (ODD) method called bridging domain [1, 2] (similar is Arlequin [3] method) where different models are overlapped and the displacements compatibility is enforced via Lagrange multipliers (LM). Some coupling options such as energy weighting, coupling zone geometry and LM field interpolation are tested. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of Homogenization Techniques to a Seismic Problem
Authors: Moos Christoph , Hackl Klaus 
Published: December 2011

AbstractThe subduction channel is a concept to explain certain phenomena observed by geoscientists around subduciton zones. Although many theories concering this have been formulated, the proof of the existence of such a channel is still open. We use homogenization techniques for wave propagation properties of the material to account for the microstrucural effects on seismic waves in such a supposed subduction channel. In order to assist the search for it we want to reveal the effects that it would have on elastic waves propagating in the crust, which are observed via surface measurement. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Homogenization of Material Forces
Authors: Ricker Sarah , Mergheim Julia , Steinmann Paul , Müller Ralf 
Published: December 2011

AbstractThe work at hand treats the extension of the classical computational homogenization scheme towards the multi‐scale computation of material quantities like the Eshelby stresses and material forces. To this end, two approaches are elaborated and their consistency with respect to the virtual work principle, in terms of a Hill‐Mandel type condition, is checked. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)