bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lumbosacral spinal segmental contributions to tibial and pudendal neuromodulation of bladder overactivity in cats
Authors: Bansal Utsav , Fuller Thomas W. , Jiang Xuewen , Bandari Jathin , Zhang Zhaocun , Shen Bing , Wang Jicheng , Roppolo James R. , de Groat William C. , Tai Changfeng 
Published: October 2016

AimsTo determine the spinal segmental afferent contributions to tibial and pudendal inhibition of bladder overactivity.MethodsIntravesical infusion of 0.5% acetic acid was used to irritate the bladder and induce bladder overactivity in anesthetized cats. Tibial or pudendal nerve stimulation was used to suppress the bladder overactivity and increase bladder capacity during cystometry. L5‐S3 dorsal roots ipsilateral to the stimulation were exposed by a laminectomy and transected sequentially during the experiments to determine the role of individual dorsal roots in tibial or pudendal neuromodulation.ResultsTransection of L5 dorsal root had no effect. Transection of L6 dorsal root in four cats produced an average 18% reduction in tibial inhibition, which is not a significant change when averaged in the group of 10 cats. Transection of L7 dorsal root completely removed the tibial inhibition without changing reflex bladder activity or pudendal inhibition. Transection of S1 dorsal root reduced the pudendal inhibition, after which transection of S2 dorsal root completely removed the pudendal inhibition. Transection of S3 dorsal root had no effect. The control bladder capacity was increased only by transection of S2 dorsal root.ConclusionsThis study in cats revealed that tibial and pudendal neuromodulation of reflex bladder overactivity depends on activation of primary afferent pathways that project into different spinal segments. This difference may be related to the recent observation in cats that the two types of neuromodulation have different mechanisms of action.
Detrusor overactivity increases bladder wall thickness in male patients: A urodynamic multicenter cohort study
Authors: De Nunzio Cosimo , Presicce Fabrizio , Lombardo Riccardo , Carter Simon , Vicentini Carlo , Tubaro Andrea 
Published: October 2016

AimsTo evaluate the role of Bladder wall thickness (BWT) as a predictor of Detrusor overactivity (DO) in patients with Lower urinary tract symptoms (LUTS)/Benign prostatic enlargement without Bladder Outlet Obstruction.MethodsFrom January 1996 to December 2000, each new patient, aged 45 years or older with LUTS, underwent standard diagnostic assessment, urodynamic studies (cystometry and pressure flow studies), and ultrasound measurements of the bladder wall thickness (BWT) in two centers. In order to exclude the possible effect of benign prostatic obstruction (BPO) on detrusor thickness, patients with a Schaefer class was ≥2 were excluded from the study. The area under the receiver operating characteristics curve (AUC) quantified the predictive accuracy (PA) of BWT for the diagnosis of DO.ResultsOverall 195 patients were enrolled. DO was observed in 98/195 patients (50%). The BWT presented an AUC of 0.70; 95% CI: 0.62‐0.77 for the diagnosis of DO. At the best cut‐off value of 3.85 mm sensitivity was 73%; specificity was 59%; positive predictive value (64%, PPV). Negative predictive value (69%, NPV).ConclusionsOur study firstly showed, how BWT in male patients may be a consequence of DO other than BPO. Our finding, if confirmed in further studies, could limit the accuracy of BWT in patients with DO and BPO.
Simultaneous detection of valine and lactate using MEGA‐PRESS editing in pyogenic brain abscess
Authors: Lange Thomas , Ko Cheng‐Wen , Lai Ping‐Hong , Dacko Michael , Tsai Shang‐Yueh , Buechert Martin 
Published: October 2016

AbstractValine and lactate have been recognized as important metabolic markers to diagnose brain abscess by means of MRS. However, in vivo unambiguous detection and quantification is hampered by macromolecular contamination. In this work, MEGA‐PRESS difference editing of valine and lactate is proposed. The method is validated in vitro and applied for quantitative in vivo experiments in one healthy subject and two brain abscess patients. It is demonstrated that with this technique the overlapping lipid signal can be reduced by more than an order of magnitude and thus the robustness of valine and lactate detection in vivo can be enhanced. Quantification of the two abscess MEGA‐PRESS spectra yielded valine/lactate concentration ratios of 0.10 and 0.27. These ratios agreed with the concentration ratios determined from concomitantly acquired short‐TE PRESS data and were in line with literature values. The quantification accuracy of lactate (as measured with Cramér‐Rao lower bounds in LCModel processing) was better for MEGA‐PRESS than for short‐TE PRESS in all acquired in vivo datasets. The Cramér‐Rao lower bounds of valine were only better for MEGA‐PRESS in one of the two abscess cases, while in the other case coediting of isoleucine confounded the quantification in the MEGA‐PRESS analysis. MEGA‐PRESS and short‐TE PRESS should be combined for unambiguous quantification of amino acids in abscess measurements. Simultaneous valine/lactate MEGA‐PRESS editing might benefit the distinction of brain abscesses from tumors, and further categorization of bacteria with reasonable sensitivity and specificity.
Influence of measurement data metrics on the identification of Interval Fields for the representation of spatial variability in finite element models
Authors: Faes Matthias , Cerneels Jasper , Vandepitte Dirk , Moens David 
Published: October 2016

AbstractDue to the exponential growth in computing power, numerical modelling techniques method have gained an increasing amount of interest for engineering and design applications. Nowadays, the deterministic finite element (FE) method, an efficient tool to accurately solve the Partial Differential Equations (PDE) that govern most real‐world problems, has become an indispensable tool for an engineer in various design stages. A more recent trend herein is to use the ever increasing computing power incorporate uncertainty and variability, which is omnipresent is all real‐live applications, into these FE models. Several advanced techniques for incorporating either variability between nominally identical parts or spatial variability within one part into the FE models, have been introduced in this context. For the representation of spatial variability on the parameters of an FE model in a possibilistic context, the theory of Interval Fields (IF) was proven to show promising results. Following this approach, variability in the input FE model is introduced as the superposition of base vectors, depicting the spatial ‘patterns’, which are scaled by interval factors, which represent the actual variability. Application of this concept, however, requires identification of the governing parameters of these interval fields, i. e. the base vectors and interval scalars. Recent work of the authors therefore was focussed on finding a solution to the inverse problem, where the spatial uncertainty on the output side of the model is known from measurement data, but the spatial variability on the input parameters is unknown. Based on an a priori knowledge on the constituting base vectors of the interval field, the simulated output of the IFFEM computation is compared to measured data, and the input parameters are iteratively adjusted in order to minimize the discrepancy between the variability in simulation and measurement data. This discrepancy is defined based on geometric properties of the convex sets of both measurement and simulation data. However, the robustness of this methodology with respect to the size of the measurement data set that is used for the identification, as yet remains unclear. This paper therefore is focussed on the investigation of this robustness, by performing the identification on different measurement sets, depicting the same variability in the dynamic response of a simple FE model, which contain a decreasing amount of measurement replica. It was found that accurate identification remains feasible, even under a limited amount of measurement replica, which is highly relevant in the context of a non‐probabilistic representation of variability in the FE model parameters. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development and experimental validation of a patient‐specific lumbar spine FE model to predict the effects of instrumentations
Authors: Beckmann Agnes , Mundt Marion , Herren Christian , Siewe Jan , Kobbe Philipp , Sobottke Rolf , Stoffel Marcus , Markert Bernd 
Published: October 2016

AbstractA lumbar spine model without instrumentations was created using CT data and validated with experimental results of the same specimen. The specimen was loaded with pure moments in a spine test rig. The material parameters were taken from literature and adapted for better simulation of the experiments. The results show that further calibration of the material parameters and the implementation of additional ligamentous structures are necessary to simulate the spine's motion reliably. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experiments and numerical simulations of new biaxially loaded specimens to characterize the behavior of thin metal sheets
Authors: Gerke Steffen , Schmidt Marco , Brünig Michael 
Published: October 2016

AbstractThe paper deals with the development of new biaxially loaded specimens to study the damage behavior of ductile metals under different loading conditions.Based on numerical simulations newly designed biaxial specimens are developed and numerically studied while an experimental program has been realized in continuation. The experimental results have been evaluated by digital image correlation (DIC) and compared with the results of finite element simulations. By concideration of different biaxial loading conditions it is possible to cover a wide range of stress triaxialities and Lode parameters in tension, shear and compression domains and consequently the newly proposed specimens facilitate a controlled study of damage and fracture at different stress states. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale damage analyis for steel structures
Authors: Heinrich Sven , Kowalsky Ursula , Dinkler Dieter 
Published: October 2016

AbstractAn approach to model the deterioration of steel structures is presented by transferring the results of a continuum damage mechanics analysis to an extended beam model which can account for the loss of structural integrity.Damage starts at the microscopic level by the initiation, growth and coalescence of voids with decreasing material resistance followed by the formation of microcracks at the mesoscale. Nevertheless, the material behavior can be sufficiently modelled on a phenomenological basis taking into account viscoplasticity, hardening effects and damage evolution. The associated model parameters are identified with the help of an evolutionary algorithm adapting numerical to experimental results. Using the finite element method a nonlocal formulation of the damage variable is required to obtain mesh‐independent results by structural analysis. The maximum element size is limited by the small magnitude of the internal length. Therefore, numerical analyses of large scale 3D steel structures are computationally expensive.To reduce the effort a beam element is proposed to account for the plastic hinges and the loss of resistance in the course of damage evolution. The corresponding relationship of bending moment and curvature bases on the continuum damage mechanics model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental characterization of dynamic properties of honeycomb sandwich joints and plates
Authors: Khosravani Mohammad Reza , Weinberg Kerstin 
Published: October 2016

AbstractIn lots of lightweight applications, constructions are also made by honeycomb sandwiches but little is known about failure and dynamic behavior of sandwich plate connections. In this research, an experimental and simulation study of the mechanical and failure behavior of honeycomb sandwich plates and joints are performed. In detail, series of tensile test have been conducted under quasi static conditions and failure behavior and resistance of the specimens are investigated. The specimens are made by phenolic resin‐impregnated aramid paper as core and two different layers of glass fiber reinforced plastic as face sheets in each side. In addition to the experimental tests, numerical simulation with finite element models are performed in Abaqus. Failure modes are investigated and finally a good agreement between test data and simulation results is achieved. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Poiseuille‐Type Fluid Transport in Poro‐Elastic Solids at Fracture
Authors: Kienle Daniel , Mauthe Steffen , Miehe Christian 
Published: October 2016

AbstractHydraulic fracturing has led to controversial public debates about its risks due to environmental issues, such as increased seismic activity or drinking water contamination. The technique is primarily used to gain crude oil or natural gas from unconventional wells. To this end, a high pressurized fracking fluid is injected into a wellbore to fracture deep‐rock formations, leading to growing cracks, a subsequent increase of permeability in these formations and thus to an increased flow of natural gas and crude oil. To weight the risks and the perspectives of hydraulic fracturing a profound understanding of the involved processes is crucial. Numerical simulations are the most cost efficient way for the required studies, but demand a reliable model with a stable implementation.We propose a canonical minimization principle for the Biot‐type fluid transport in porous media based on only two constitutive functions, that is the free energy function
$\hat{\psi}$,
and a dissipation potential
$\hat{\phi}$,
[1]. This formulation is coupled to a phase‐field approach for fracture which characterizes an intuitive and descriptive regularization of a crack surface that converges for vanishing length‐scale parameter to a sharp crack. The crack phase‐field allows for a distinct incorporation of an extra fluid flow within cracked regimes of the solid [2]. This extra fluid flow is modeled according to Poiseuille law for laminar flow, yielding an implementation via a change of the permeability tensor, i. e., making it a function of the crack opening width, formulated itself in terms of the strain and the gradient of the crack phase field. © 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of fracture in grain boundaries of nano‐coatings using cohesive zone elements
Authors: Rezaei Shahed , Wulfinghoff Stephan , Reese Stefanie 
Published: October 2016

AbstractA cohesive zone element technique (CZ) is applied to study grain boundary fracture in nano coating layers (see [1]). This goes along with the investigations of the delamination and fracture behavior of the coatings and the substrate interface. The main motivation is to investigate antiadhesive and wear resistant properties of coatings made of ceramics produced by the High Power Pulsed Magnetron Sputtering (HPPMS) technique [2]. Different physical conditions in HPPMS result into different grain morphologies with different mechanical properties. Therefore prediction of fracture and damage in such systems can lead to the optimum choice of process parameters in order to gain the best fracture resistance properties for the coatings. To illustrate the applicability of the model, several simulations with different mechanical and structural properties are performed. The developed CZ element model is capable of modeling the separation, the contact and also the irreversible reloading conditions in different directions [3]. The model is further developed to be applicable for geometrically complex interfaces including different bonding behaviors, with a high robustness. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessment of asymmetric crack initiation in open‐hole plates using a coupled stress and energy criterion
Authors: Rosendahl Philipp L. , Weißgraeber Philipp , Stein Nicolas , Becker Wilfried 
Published: October 2016

AbstractAn application of the finite fracture mechanics concept to open‐hole plates subject to combined tensile and bending loading is presented. In finite fracture mechanics, the simultaneous satisfaction of both, a stress and an energy criterion, is enforced as a condition for crack initiation. Efficient modeling and closed‐form expressions for the dependence of the stress and energy quantities on governing structural and material parameters allow for a comprehensive numerical analysis of the onset of asymmetric crack patterns. The obtained failure load predictions are found to agree well with a cohesive zone model and experimental data from literature. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A coupled stress and energy failure model for crack initiation in arbitrarily shaped adhesive lap joints
Authors: Stein Nicolas , Weißgraeber Philipp , Becker Wilfried 
Published: October 2016

AbstractIn this work, crack initiation in adhesive lap joints of arbitrary joint configuration is studied by means of a finite fracture mechanics approach. The analysis is based on a general stress solution for adhesive joints combined with a coupled stress and energy criterion. The instantaneous formation of a crack of finite size is predicted if a stress and energy criterion are satisfied simultaneously. The closed‐form analytical solution of the stress field allows for an efficient evaluation of the crack initiation load and corresponding finite crack length. A comparison to experimental results from literature and to numerical results obtained with a cohesive zone model approach shows a good agreement. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient numerical integration of arbitrarily broken cells using the moment fitting approach
Authors: Hubrich Simeon , Joulaian Meysam , Di Stolfo Paolo , Schröder Andreas , Düster Alexander 
Published: October 2016

AbstractThe finite cell method is based on a fictitious domain approach, providing a simple and fast mesh generation of structures with complex geometries. However, this simplification leads to intersected cells where the standard Gauss quadrature does not perform well. To perform the numerical integration of these cells, we use the moment fitting approach that generates an individual quadrature rule for every broken cell. In this paper, we will perform a non‐linear optimization approach to find the optimal position and number of the integration points. The findings show that the proposed method leads to efficient quadrature rules that require less integration points than other existing integration methods. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Post‐critical behaviour of delaminated composite struts
Authors: Köllner Anton , Völlmecke Christina 
Published: October 2016

AbstractPostbuckling responses of delaminated composite struts are semi‐analytically modelled. The model used allows to describe the postbuckling behaviour beyond the state where delamination growth is initiated. In the current work, a multi‐layered composite strut of differently stacked transversally isotropic unidirectional layers is investigated. A pre‐existing delamination is assigned in between two layers. By using only four generalized coordinates postbuckling responses incorporating delamination growth are determined. © 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The stresses in single lap joints with a functionally graded adhesive bondline: an efficient modelling approach
Authors: Mardani Houman , Stein Nicolas , Becker Wilfried 
Published: October 2016

AbstractIn this work, an efficient analytical model for the stress analysis of single lap joints with a functionally graded adhesive bondline is proposed which considers peel as well as shear stresses in the adhesive. The model takes into account the nonlinear geometric characteristics of a single lap joint under tensile loading and allows for the analysis of various adhesive Young's modulus variations. The obtained stress distributions are compared to results of detailed Finite Element analyses and show a good agreement for several single lap joint configurations. In addition, different adhesive Young's modulus distributions and their effect on the peel and shear stresses are studied and discussed in detail. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient nonlinear reanalysis for structural modifications
Authors: Materna Daniel 
Published: October 2016

AbstractIn this paper an approach for nonlinear reanalysis based on residual increment approximations (RIA) is presented. The method requires only the evaluation of residual vectors, which can be done very fast and efficient. Moreover, the results are improved by using a rational approximation method. The approach is general and can be applied to linear and nonlinear problems with different kind of design modifications. Furthermore, the proposed method is very efficient and easily to implement in existing finite element programs. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
p‐version finite elements and finite cells for finite strain elastoplastic problems
Authors: Taghipour Aliakbar , Parvizian Jamshid , Heinze Stephan , Düster Alexander 
Published: October 2016

AbstractIn this paper, the p‐version finite element method and its fictitious domain extension, the finite cell method, are extended to the finite strain J2 plasticity. High‐order shape functions are used for the finite element approximation of volume‐preserving plastic dominated deformations. The accuracy and efficiency of p‐version elements and cells in the finite plastic strain range are evaluated by the computation of two benchmark problems. It is shown that they provide locking free behavior and simplified meshing. These results are verified in comparison with the results of h‐version elements in F‐bar formulation. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Subspace‐Based Reduced‐Order Modeling Methods for Structural Dynamic Systems
Authors: Tegtmeyer Stefanie , Nackenhorst Udo 
Published: October 2016

AbstractComputational costs for detailed Finite Element approximations can be reduced by using reduced‐order models instead. In this contribution, four subspace‐based reduced‐order modeling methods are compared. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Eigenpath analysis of rotating mechanical systems based on ALE formulation
Authors: Weidauer Tim , Willner Kai 
Published: October 2016

AbstractWhen bodies rotate they are subjected to velocity‐dependent gyroscopic and inertia effects, which alter the dynamic behaviour of the structure. Analysing its eigenpairs consisting of eigenvalues and eigenvectors, these parameter‐dependent changes can be tracked as eigenpaths by means of a continuation algorithm as in [1]. For rotationally symmetric structures an ALE approach (ALE = Arbitrary LAGRANGIAN‐EULERIAN) for the finite element method as described in [2] can be employed. It allows simulating rotational influences on the body without actually having to rotate the mesh of the structure itself. This still‐standing mesh facilitates further steps like coupling of other, static components with the rotating body. The combination of ALE with eigenpath analysis including an example is described in the following. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of stiffness analysis of rubber material applied in resilient wheel
Authors: Zhang Le , Markert Bernd 
Published: October 2016

AbstractResilient wheels are well‐known for their contribution to prevent squealing, impact noise and dynamic stresses on unsprung masses. In this study, a FE model is established in ABAQUS to analyze the stiffness of resilient wheels based on the Mooney‐Rivlin hyperelastic material theory. The modes of each part in the resilient wheel and the whole wheel are calculated. The static and dynamic stiffness of the resilient wheel are analyzed. The simulation shows that the resilient wheel can reduce the dynamic loads both in the lateral and vertical directions between the vehicle and the track. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)