bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bifurcations and limit cycles due to self‐excitation in nonlinear systems with joint friction: Initialization of isolated solution branches via homotopy methods
Authors: Kappauf Jonas , Hetzler Hartmut 
Published: November 2019

AbstractThe main objective of this contribution is finding isolated stationary solutions, e.g. equilibria or limit cycles, in dynamical systems. Usually, NEWTON‐type methods are applied for solving the resulting algebraic equation system. Here, the most difficult point is finding adequate initial conditions that are providing a solution on the isolated branch. So, there is a need for a more straight forward manner of initialising the continuation of isolated solutions. Within this contribution, homotopy methods are applied. The crucial point is to define a simplified version of the problem F(x; λ), which can be continuously transformed into the original one. As an example, limit cycles of a friction oscillator including COULOMB damping is discussed and two types of homotopy maps are addressed to obtain a starting point for their continuation.
Modeling and simulation of metal bellows in vacuum interrupters
Authors: Boyaci Aydin , Simonidis Christian , Gentsch Dietmar 
Published: November 2019

AbstractIn vacuum interrupters, metal bellows permit the motion of the moving contact with up to long contact strokes while maintaining the ultra‐high vacuum seal. In contrast to most other bellows applications, the opening and closing operation of the vacuum interrupter lead to high‐impulsive motions which additionally excite bellows oscillations. Future requirements of higher switching speeds and operations demand for a simulation‐driven optimization of the metal bellows to increase the mechanical lifetime of the vacuum interrupter.The damaging effect of the switching operations is investigated on the bellows. A static force is axially applied on the bellows to validate the mechanical model compared with experimental results. Furthermore, a modal analysis is performed to consider the bellows as a flexible body in a multibody simulation. To account for the multiple‐frequency oscillations during the switching operation, a transient simulation is carried out where the excitation of the bellows follows from a travel curve. The global hot spot of mechanical stress is identified for further lifetime evaluations by low‐cycle fatigue methods.
Validation of Finite Element Image Registration‐based Cardiac Strain Estimation from Magnetic Resonance Images
Authors: Berberoğlu Ezgi , Stoeck Christian , Moireau Philippe , Kozerke Sebastian , Genet Martin 
Published: November 2019

AbstractAccurate assessment of regional and global function of the heart is an important readout for the diagnosis and routine evaluation of cardiac patients. Indeed, recent clinical and experimental studies suggest that compared to global metrics, regional measures of function could allow for more accurate diagnosis and early intervention for many cardiac diseases. Although global strain measures derived from tagged magnetic resonance (MR) imaging have been shown to be reproducible for the majority of image registration techniques, the measurement of regional heterogeneity of strain is less robust. Moreover, radial strain is underestimated with the current techniques even globally. Finite element (FE)‐based techniques offer a mechanistic approach for the regularization of the ill‐posed registration problem. This paper presents the validation of a recently proposed FE‐based image registration method with mechanical regularization named equilibrated warping. For this purpose, synthetic 3D‐tagged MR images are generated from a reference biomechanical model of the left ventricle (LV). The performance of the registration algorithm is consequently tested on the images with different signal‐to‐noise ratios (SNRs), revealing the robustness of the method.
Large‐Scale Quasi‐DNS of Mixed‐Mode Turbulent Combustion
Authors: Zirwes Thorsten , Zhang Feichi , Habisreuther Peter , Bockhorn Henning , Trimis Dimosthenis 
Published: November 2019

AbstractIn many applications like gas turbines, the combustion process can take place in partially‐premixed environments, where fuel and oxidizer are not fully mixed before combustion. These partially‐premixed or mixed‐mode flames have become a focus of combustion research in the last few years. In this work, a quasi‐DNS of an experimentally measured burner configuration has been conducted. The simulation employs a complex reaction mechanism and detailed molecular diffusion coefficients for each chemical species. Due to the highly resolved numerical grids and the detailed thermo‐physical and chemical properties, the simulation results allow to characterize the flame with the help of flame markers in greater detail than the experiments can provide. The investigated flame exhibits characteristics of a premixed flame near the nozzle. Further downstream both premixed and non‐premixed combustion modes become equally important in terms of the heat release rate. The dataset from the simulation also allows to form joint probability density functions of commonly used control variables to study their correlations depending on the combustion regime.
Distributed sampling for rational approximation of the acoustic scattering of an airfoil
Authors: Bonizzoni Francesca , Pradovera Davide 
Published: November 2019

AbstractIn this paper we compute a reduced order model for a time‐harmonic external acoustic scattering problem with parametric frequency. The employed technique isminimal rational interpolation, an explicit moment‐matching method for Hilbert space‐valued meromorphic maps. We study the approximation and stability properties of this technique for different choices of the sample point set, namely fully distributed in the parameter range, and partially and fully confluent. The proposed technique is also compared with an implicit multi moment‐matching method based on Galerkin projection.
Parallel block–selective algebraic multigrid in foam‐extend
Authors: Uroić Tessa , Jasak Hrvoje 
Published: November 2019

AbstractWe present an extension of a well–known classic algebraic multigrid algorithm, where coarsening is based on selection of equations, for an implicitly coupled pressure–velocity system discretised by the finite volume (FV) method. The resulting coefficient matrix of the linear system is point–ordered, and there are 4 equations for each FV cell: three components of velocity and pressure. A significant challenge is posed in terms of parallelisation of the sequential coarsening process and calculation of coarse level matrix, using the Galerkin projection. In this paper we present the parallelisation strategy and performance of the block–selection AMG.
Symbolic Evaluation of hp‐FEM Element Matrices
Authors: Haubold Tim , Pillwein Veronika , Beuchler Sven 
Published: November 2019

AbstractIn this paper we consider higher order shape functions for finite elements on a triangle. On the reference element Dubiner‐like ansatz functions based on suitable integrated Jacobi polynomials are chosen. It can be proved that the corresponding mass and stiffness matrices are sparse for all polynomial degree p. Due to the orthogonal relations between Jacobi polynomials the exact values of the entries of mass and stiffness matrix can be determined. Using symbolic computation, we can find simple recurrence relations which allow us to compute the remaining nonzero entries in optimal arithmetic complexity.
Controlling Physical Properties on Interfaces Using Parametrised Level Set Methods and Extended Finite Element Method
Authors: Wohlgemuth Felix , Barthold Franz-Joseph 
Published: November 2019

AbstractThe stress field information states a main point of interest, when regarding structural optimisation of bimaterial structures. The introduction of stress criteria along the volume is crucial in the development of new designs. In the case of bimaterials, the stress field along the interface deserves additional attention e.g. to prevent delamination. Tracing the interface through shape optimisation in CAD‐based methods is rather expensive due to the high cost in remeshing techniques. Therefore, level set methods with fixed background meshes are used as in [1].In this work an approach for controlling strains and stresses on the interface in a framework of shape optimisation is introduced. The geometry description is managed by parametrised level set functions and a sub‐meshing technique is coupled with the extended finite element method. The parametrisation with superellipses allows to reduce the number of design variables to a minimum of six variables per introduced ellipse while holding up a sufficient precision in the geometry description (see [2]). Moreover, it simplifies the shape derivatives as it provides an implicit description for the moving interfaces. The sub‐meshing technique makes it possible to keep existing strategies from homogeneous structures and to transform them on a discontinuous material using enriched shape functions provided by the standard extended finite element method (see [3]). Shape sensitivities are evaluated on the sub‐elements and extrapolated to the interface introducing pseudo nodes. The sensitivity information of the stress field among these pseudo nodes can be used in the framework of stress minimisation as well as for a side condition in a volume minimisation setup.
A unified multiscale modelling approach for concrete fatigue with microscale damage‐mechanism implementations
Authors: Caggiano Antonio , Said Schicchi Diego , Yang Sha , Harenberg Stefan , Malarics-Pfaff Viktoria , Pahn Matthias , Dehn Frank , Koenders Eddie 
Published: November 2019

AbstractA micro‐scale‐based approach for the numerical analysis of cement‐based materials, subjected to low‐ and high‐cycle fatigue actions, is presented in this paper. The constitutive model is aimed at describing the evolving microstructural changes caused by cyclic loading protocols. The plastic‐damage‐based model is formulated combining the concepts of fracture‐energy theories and damage stiffness degradations, representing the key phenomena occurring in concrete under fatigue.
Evaluating Artificial Neural Networks and Quantum Computing for Mechanics
Authors: Mielke André , Ricken Tim 
Published: November 2019

AbstractThe popularization of Machine Learning (ML) and the advent of Noisy Intermediate‐Scale Quantum (NISQ) devices for Quantum Computing (QC) sparked new inspiration for the search for techniques reducing computation time in mechanics. We evaluate artificial neural networks (ANNs) as candidates for creating computationally fast surrogate models for otherwise time‐consuming simulations, using a multiscale and multiphase model describing processes in the human liver. We also give a short overview of interesting quantum‐enhanced algorithms capable of reducing computational cost in parts of complex simulations.
Modelling silica bilayers based on experimental data
Authors: Stratmann Jan , Ebrahem Firaz , Bamer Franz , Markert Bernd 
Published: November 2019

AbstractIn order to investigate the behavior of 2D silica glass subjected to mechanical loading, we develop an algorithm for the realization of 2D newtork glasses consisting of corner‐sharing SiO3 triangles that build rings of different shapes and sizes. Our algorithm extends the network ring by ring in circular manner around the existing configuration. A random engine generates the size of each new ring driven by experimentally evaluated ring statistics that depend on the current number of neighboring rings taken from real 2D silica layers. The method produces continuous random network models with ring size distribution observed in real 2D silica layers and provides the basis for the mechanical investigation of network glasses.
Small strain crystal plasticity based on the primal‐dual interior point method
Authors: Scheunemann Lisa , Nigro Paulo S.B. , Schröder Jörg , Pimenta Paulo M. 
Published: November 2019

AbstractThe paper presents a novel approach for rate‐independent single crystal plasticity based on the Infeasible Primal‐Dual Interior Point Method in a small strain framework. Therein, the principle of maximum dissipation together with the yield functions on the slip systems in the crystal are considered as the constrained optimization problem. The constraint conditions adapted using slack variables and a Lagrangian is formulated using barrier functions. The equations are linearized and solved using Newton's method. Numerical examples are presented for slip on the individual slip systems in a single crystal under global rotation.
Numerical analysis of the thermally induced damage in remote laser cut carbon fibre reinforced polymers
Authors: Schmidt Benjamin , Rose Michael , Zimmermann Martina , Kästner Markus 
Published: November 2019

AbstractRemote laser cutting in carbon fibre reinforce polymers is a promising machining technology which can reduce the main drawback in laser cutting, the heat affected zone. This contribution presents a two‐step modelling approach for the simulation of remote laser cut carbon fibre reinforce polymers, consisting of a damage model for the initially intact material and a model for the thermally damaged material.The static damage behaviour was modelled with the Pinho material model [1], which stands out due to its physically based failure criteria. Initial thermal damages caused by the heat input were modelled with the damage parameters of the Pinho model. The dimensions of the heat affected zone are taken from polished micro sections of the material around the cutting edge.As a numerical example, comparative tensile tests of milled and laser cut open hole specimens were simulated. The advantage of these specimens is the notch effect around the holes in the heat affected zone, which amplifies the differences between the two cutting technologies.
Effect of nitrogen plasma treatment on the crystallinity and self‐bonding of polyetheretherketone (PEEK) for biomedical applications
Authors: Fedel Mariangela , Micheli Victor , Thaler Martin , Awaja Firas 
Published: November 2019

Polyetheretherketone (PEEK) is a thermoplastic material with outstanding properties and high potential for biomedical applications, including hermetic encapsulation of active implantable devices. Different biomedical grade PEEK films with initial degree of crystallinity ranging from 8% to 32% (with or without mineral filling) were inspected. PEEK surfaces were treated with nitrogen RF plasma and the effects on materials crystallinity and self‐bonding were evaluated. In particular, the relationship between auto‐adhesive properties and crystalline content of PEEK before and after plasma treatment was examined.PEEK samples showed different bonding strength depending on their degree of crystallinity, with higher self‐bonding performance of mineral‐filled semi‐crystalline films. XRD did not show any modification of the PEEK microstructure as a result of plasma treatment, excluding a significant influence of crystallinity on the self‐bonding mechanisms. Nevertheless, plasma surface treatment successfully improved the self‐bonding strength of all the PEEK films tested, with larger increase in the case of semi‐crystalline unfilled materials. This could be interpreted to the increase in chain mobility that led to interfacial interpenetration of the amorphous phase.
Incidence and predictors of treatment‐related conjugated hyperbilirubinemia during early treatment phases for children with acute lymphoblastic leukemia
Authors: Hashmi Saman K. , Navai Shoba A. , Chambers Tiffany M. , Scheurer Michael E. , Hicks M. John , Rau Rachel E. , Gramatges Maria M. 
Published: November 2019

AbstractConjugated hyperbilirubinemia (CHB) and liver transaminase elevation are known complications of acute lymphoblastic leukemia (ALL) therapy, but host risk factors are poorly understood. Among 373 children diagnosed with ALL between 2011 and 2016, clinically significant CHB and transaminase elevation were observed in 15 (4.0%) and 12 (3.2%) children, respectively, during induction and consolidation. Body mass index ≥95th percentile (odds ratio 9.20, 95% confidence interval 2.56–32.96) was the only host factor independently associated with CHB, and no host factors were associated with transaminase elevation. Obese patients warrant closer monitoring of hepatic function to facilitate early intervention prior to the development of severe, adverse hepatic events.
Cognitive mediators of adaptive functioning outcomes in survivors of pediatric brain tumors treated with proton radiotherapy
Authors: Roth Alexandra K. , Ris M. Douglas , Orobio Jessica , Xue Judy , Mahajan Anita , Paulino Arnold C. , Grosshans David , Okcu M. Fatih , Chintagumpala Murali , Kahalley Lisa S. 
Published: November 2019

AbstractBackgroundCranial radiotherapy (RT) is associated with risk for cognitive and adaptive dysfunction. Proton RT (PRT) is a technique hypothesized to spare cognition by reducing exposure to nontarget brain tissue. However, little is known regarding functional outcomes in survivors of pediatric brain tumor (BT) treated with PRT. The present study examined the relationship between cognitive and adaptive outcomes in pediatric BT survivors post‐PRT.MethodsSurvivors treated with either focal (n = 33) or craniospinal irradiation (CSI; n = 37) PRT completed neurocognitive evaluations approximately 5 years post‐treatment. Results of intelligence testing and ratings of adaptive functioning are reported. Mediation models examined the relationship among radiation field, cognition, and adaptive functioning.ResultsThe PRT CSI group demonstrated worse cognitive outcomes than the PRT Focal group across each cognitive index (Cohen's d = 0.56–0.70). Parent ratings of adaptive functioning were also worse in the PRT CSI group than the PRT Focal group (Global Adaptive Composite, d = 0.53; conceptual skills, d = 0.67). Cognitive performance fully mediated the relationship between radiation field and adaptive outcomes, while controlling for group differences in tumor histology and RT dose.ConclusionsFocal PRT survivors demonstrated generally positive outcomes with weaknesses in processing speed and aspects of adaptive functioning. CSI exposure was associated with more consistently poor cognitive and adaptive outcomes. The increased risk for adaptive dysfunction in the PRT CSI group appeared due to the effects of CSI on cognition. Efforts to reduce the volume of tissue exposure to RT remain important.
Predictors of survival in patients with high‐risk neuroblastoma who failed tandem high‐dose chemotherapy and autologous stem cell transplantation
Authors: Yi Eun Sang , Son Meong Hi , Hyun Ju Kyung , Cho Hee Won , Ju Hee Young , Lee Ji Won , Yoo Keon Hee , Sung Ki Woong , Koo Hong Hoe 
Published: November 2019

AbstractObjectiveThis study aims to explore prognostic factors for high‐risk neuroblastoma patients with response failure to tandem high‐dose chemotherapy and autologous stem cell transplantation (HDCT/auto‐SCT).MethodsSurvival outcomes were compared according to characteristics at initial diagnosis, at relapse/progression, and after relapse/progression in patients who experienced relapse/progression after tandem HDCT/auto‐SCT from 2006 to 2018.ResultsForty‐nine patients experienced relapse/progression after tandem HDCT/auto‐SCT during the study period: 43 received salvage treatment and 30 underwent allogeneic SCT (allo‐SCT) after reinduction treatment. Although all six patients who did not undergo salvage treatment died, 13 of the 43 patients who did remain alive. The 3‐year probabilities of event‐free survival (EFS) and overall survival (OS) from initial relapse/progression among the 49 patients were 14.4% ± 5.2% and 21.2% ± 6.4%, respectively. A higher neuron‐specific enolase (NSE) level (>24 ng/mL) at relapse/progression was an independent prognostic factor for worse OS. Nine of 30 patients who underwent allo‐SCT remain alive, and the 3‐year probabilities of EFS and OS from allo‐SCT were 16.5% ± 7.2% and 21.6% ± 8.3%, respectively. A higher NSE level and no incorporation of high‐dose 131I‐metaiodobenzylguanidine (HD‐MIBG) treatment into allo‐SCT were independent prognostic factors for worse EFS and OS after allo‐SCT.ConclusionThe results suggest that a higher serum NSE level at relapse/progression is a predictor of worse prognosis in patients with response failure to tandem HDCT/auto‐SCT, and that incorporation of HD‐MIBG treatment into allo‐SCT may improve outcomes.
Omic approaches to pediatric bone sarcomas
Authors: Tirtei Elisa , Cereda Matteo , De Luna Elvira , Quarello Paola , Asaftei Sebastian Dorin , Fagioli Franca 
Published: November 2019

AbstractOver the last decade, next‐generation sequencing technologies have improved our ability to assess biological aspects, at genomic and transcriptomic levels, on a large scale— and have been increasingly used for the management of adult cancers. However, their efficacy and feasibility within pediatrics is still under investigation. “Omic” approaches represent an opportunity to understand the oncogenic mechanisms driving the onset and progression of bone sarcoma and improve the clinical management of young patients with bone sarcomas. This review focuses on the current genomic and transcriptomic characteristics of managing pediatric patients, affected by Ewing sarcoma and osteosarcoma.
Genome‐wide analysis of acute leukemia and clonally related histiocytic sarcoma in a series of three pediatric patients
Authors: Bleeke Matthias , Johann Pascal , Gröbner Susanne , Alten Julia , Cario Gunnar , Schäfer Hansjörg , Klapper Wolfram , Khoury Joseph , Pfister Stefan , Müller Ingo 
Published: November 2019

AbstractPediatric histiocytic sarcoma (HS) clonally related to anteceding leukemia is a rare malignancy with poor outcome. We performed a molecular characterization of HS and the corresponding leukemia by methylation arrays and whole‐exome sequencing and found a variety of aberrations in both entities with deletions of CDKN2A/B as a recurrent finding. Furthermore, data from genome‐wide mutation analysis from one patient allowed the reconstruction of a sequence of tumorigenesis of leukemia and HS lesions including the acquisition of a putatively activating KRAS frameshift deletion (p.A66fs). Our results provide an insight into the genetic landscape of pediatric HS clonally related to anteceding leukemia.
Malignancy and lymphoid proliferation in primary immune deficiencies; hard to define, hard to treat
Authors: Kiykim Ayca , Eker Nursah , Surekli Ozlem , Nain Ercan , Kasap Nurhan , Aktürk Hacer , Dogru Omer , Canbolat Aylin , Somer Ayper , Koc Ahmet , Tokuc Gulnur , Bozkurt Suheyla , Turkoz Kemal , Karakoc‐Aydiner Elif , Ozen Ahmet , Baris Safa 
Published: November 2019

AbstractBackgroundRegarding the difficulties in recognition and management of the malignancies in primary immune deficiencies (PIDs), we aimed to present the types, risk factors, treatment options, and prognosis of the cancers in this specific group.MethodsSeventeen patients with PID who developed malignancies or malignant‐like diseases were evaluated for demographics, clinical features, treatment, toxicity, and prognosis.ResultsThe median age of malignancy was 12.2 years (range, 2.2‐26). Lymphoma was the most frequent malignancy (n = 7), followed by adenocarcinoma (n = 3), squamous cell carcinoma (n = 2), cholangiocarcinoma (n = 1), Wilms tumor (n = 1), and acute myeloid leukemia (n = 1). Nonneoplastic lymphoproliferation mimicking lymphoma was observed in five patients. The total overall survival (OS) was 62.5% ± 12.1%. The OS for lymphoma was 62.2% ± 17.1% and found to be inferior to non‐PID patients with lymphoma (P = 0.001).ConclusionIn patients with PIDs, malignancy may occur and negatively affect the OS. The diagnosis can be challenging in the presence of nonneoplastic lymphoproliferative disease or bone marrow abnormalities. Awareness of susceptibility to malignant transformation and early diagnosis with multidisciplinary approach can save the patients’ lives.