bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the calculation of Topological Derivatives considering an exemplary nonlinear material model
Authors: Weider Katrin , Schumacher Axel 
Published: October 2016

AbstractIn this contribution, a new approach for dealing with material nonlinearities in structural optimization is presented. The method combines the advantage of the calculation of the Topological Derivatives in elasticity problems with the use of meta‐modelling for capturing complex correlations. For an exemplary nonlinear material model, the calculation of the Topological Derivative and the resulting difference to the linear elastic material model is shown. An academic example shows the difference between the linear and the nonlinear material model. © 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Global Convergence of the Jacobi Method
Authors: Hari Vjeran , Begović Kovač Erna 
Published: October 2016

AbstractThe paper is concerned with the global convergence of the Jacobi method for symmetric matrices under a special class of cyclic pivot strategies. That class generalizes the well‐known class of serial strategies. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dual‐primal isogeometric tearing and interconnecting solvers for multipatch continuous and discontinuous Galerkin IgA equations
Authors: Hofer Christoph , Langer Ulrich 
Published: October 2016

AbstractWe present results regarding fast and robust solvers for equations arising from continuous and discontinuous Galerkin discretization of heterogeneous diffusion problems in the context of Isogeometric Analysis. The solvers considered belong to the class of non‐overlapping domain decomposition methods which use tearing and interconnection strategies. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multisymplectic variational integrators for PDEs of geometrically exact beam dynamics using algorithmic differentiation
Authors: Leitz Thomas , Leyendecker Sigrid 
Published: October 2016

AbstractFor the simulation of geometrically exact beam dynamics [4], a multisymplectic Lie‐group variational integrator [3] is derived. Based on the implementation of the discrete Lagrangian, algorithmic differentiation is used in the computation of both, the discrete Euler‐Lagrange equations, and the Jacobi matrix needed for the Newton‐Raphson iteration. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Discontinuous Galerkin Method for Fractional Differential Equations
Authors: Franz Sebastian , Rubisch Johanna 
Published: October 2016

AbstractWe investigate the numerical treatment of fractional derivatives using a discontinuous Galerkin approach. We consider fractional differential equations in one dimension.The most common definitions, the Riemann‐Liouville and Caputo derivatives, as well as a third definition are considered. Different types of initial condition statements are investigated for the extended discontinuous Galerkin method.We obtain numerical results on the order of convergence in the L2 and H1 norms. We compare the classical discontinuous Galerkin method with our adapted approach and show results for the different types of fractional derivatives.Further work was carried out on parabolic differential equations with fractional time derivatives, which is to be published cf. [2]. A keystone in the further research is the development of analytical tools for theoretical convergence results. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adjoint‐Based Optimal Boundary Control of a Stefan Problem System Fully Coupled with Navier‐Stokes Equations
Authors: Baran Björn , Heiland Jan 
Published: October 2016

AbstractFree boundary and moving boundary problems, that can be used to model crystal growth or the solidification and melting of pure materials, receive growing attention in science and technology. The optimal control of these problems appear even more interesting since certain desired shapes of the boundaries improve, e.g., the material quality in the case of crystal growth. We consider the so called two‐phase Stefan problem that models a solid and a liquid phase separated by a moving interface.In the work presented, we take a sharp interface model approach and define a quadratic tracking‐type cost functional that penalizes the deviation of the interface from the desired state at a final time as well as the control costs. Following the “optimize‐then‐discretize” paradigm, we formulate a first order optimality system using the formal Lagrange approach and derive the adjoint PDE system that provides the needed gradient of the cost functional.By means of an example setup of a container with an in‐ and outflow of water and a cooling unit at the bottom, we illustrate how the derived formulations can be used to achieve a desired interface between the solid and the fluid phase by controlling the flow at the inlet. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification and Tracking‐Control for an Optomechatronical Image Derotator Using Neural Networks
Authors: Altmann Bettina , Rohloff Benjamin , Pape Christian , Reithmeier Eduard 
Published: October 2016

AbstractIn this paper an optomechatronical image derotator is used for vibration measurements on rotating objects. First of all, the concept of the derotator is explained and it is shown that the phase position and the rotational velocity of the derotator and the measurement object have to be aligned. Therefore, a highly dynamic tracking‐control is needed. Considering the nonlinear friction of the synchronous motor, a model of the system which considers this non‐linearity is evolved. This is accomplished by using neural networks for the approximation of the friction term. In this case General Regression Neural Networks (GRNN) are used for the learning algorithm. Moreover, the system's parameters, eg. the friction term and the inertia, are identified based on the nonlinear model. Then a feedback control is designed by using the controllable canonical form through feedback linearization. Finally, the results of vibration measurements on a rotating blisk using the nonlinear control concept for the derotator are shown. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unimodular completion and direct flat representation in the context of differential flatness
Authors: Fritzsche Klemens , Knoll Carsten , Franke Matthias , Röbenack Klaus 
Published: October 2016

AbstractDespite its significance in nonlinear controller design, the verification of the property of differential flatness and the identification of so‐called flat outputs is a continuing research topic. However, the difficulty of both verification and identification heavily depends on the representation of the system. This contribution shows that flatness may be a far less complicated matter, depending on the choice of coordinates. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Newton‐Kleinman method for the optimal control of stable weakly regular linear systems
Authors: Massoudi Arash , Reis Timo 
Published: October 2016

AbstractWe give an algorithm to find the approximate solution of the linear‐quadratic optimal control problem for stable weakly regular linear systems. This algorithm can be understood as a generalization of the Newton‐Kleinman method known from the finite‐dimensional theory. The central characteristic of our approach is the possibility to solve problems with unbounded control and observation operators, which is motivated by partial differential equations with boundary control and observation. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control concepts for a parallel manipulator with flexible links
Authors: Morlock Merlin , Burkhardt Markus , Seifried Robert 
Published: October 2016

AbstractLight‐weight robots are advantageous considering the low energy consumption and the low material cost. However, in light‐weight structures significant oscillations can occur which make the control very challenging. Objective of this research is end‐effector trajectory tracking of a parallel manipulator with flexible links. Hereby, only the manipulator's drives are used, and no additional actuation on the flexible bodies is considered. For accurate trajectory tracking, feedforward control of the manipulator is used based on inverse dynamics and servo‐constraints, combined with feedback control of the drive positions. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Higher order variational integrators in optimal control theory
Authors: Ober‐Blöbaum Sina 
Published: October 2016

AbstractHigher order variational integrators are analyzed and applied to optimal control problems posed with mechanical systems. First, we derive two different kinds of high order variational integrators based on different dimensions of the underlying approximation space. While the first well‐known integrator is equivalent to a symplectic partitioned Runge‐Kutta method, the second integrator, denoted as symplectic Galerkin integrator, yields a method which in general, cannot be written as a standard symplectic Runge‐Kutta scheme [1]. Furthermore, we use these integrators for the discretization of optimal control problems. By analyzing the adjoint systems of the optimal control problem and its discretized counterpart, we prove that for these particular integrators optimization and discretization commute [2]. This property guarantees that the accuracy is preserved for the adjoint system which is also referred to as the Covector Mapping Principle. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stabilization of switched DAEs via fast switching
Authors: Trenn Stephan 
Published: October 2016

AbstractSwitched differential algebraic equations (switched DAEs) can model dynamical systems with state constraints together with sudden structural changes (switches). These switches may lead to induced jumps and can destabilize the system even in the case that each mode is stable. However, the opposite effect is also possible; in particular, the question of finding a stabilizing switching signal is of interest. Two approaches are presented how to stabilize a switched DAE via fast switching. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cascadic Multigrid in a Spectral‐Element Context
Authors: Huismann Immo , Stiller Jörg , Fröhlich Jochen 
Published: October 2016

AbstractCurrent research in computational fluid dynamics focuses on high‐order methods, which offer a significant reduction of the computational effort for a given error bound. In low‐order methods optimal complexity solvers for elliptic equations, e.g. the Helmholtz equation, are readily available, but for high‐order methods these are still an area of research. This work evaluates the effectiveness of the Cascadic Multigrid Method in the context of spectral elements, comparing it to a standard Krylov subspace solver. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Circular proofs for the modal mu‐calculus
Authors: Afshari Bahareh , Leigh Graham E. 
Published: October 2016

AbstractInspired by Stirling's tableau proofs [4] we introduce a finite, cut‐free sound and complete sequent calculus for the modal mu‐calculus. Proofs in this system are finite trees in which leaves are either axioms or assumptions that are discharged by a specific rule of the calculus. The discharge rules provide a way to unfold assumptions motivating the name circular proofs. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dimer models and Grassmannian cluster categories
Authors: Baur Karin 
Published: October 2016

AbstractA dimer model can be defined as a quiver embedded into a surface in such a way that the complement is a disjoint union of disks with oriented boundaries. Such models can also be considered in the case of a surface with boundary. The Postnikov diagrams used by J. Scott to describe the cluster structure of the homogeneous coordinate ring of the Grassmannian give rise to dimer models on a disk in this sense. We associate a natural algebra to such a dimer model. This algebra is a modified version of the corresponding Jacobian algebra, taking the boundary into account. Taking the sum of the idempotents corresponding to boundary vertices, we obtain an idempotent subalgebra, which we call the boundary algebra. We show that it is independent of the choice of dimer model and coincides with an algebra that B. Jensen, A. King and X. Su have used to model the cluster structure of the homogeneous coordinate ring of the Grassmannian categorically. This reports on joint work with A. King (Bath) and R. Marsh (Leeds) and with D. Bogdanic (Graz). (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards modelling skeletal muscle growth and adaptation
Authors: Altan Ekin , Zöllner Alexander , Avcı Okan , Röhrle Oliver 
Published: October 2016

AbstractDespite an increasing interest in modelling skeletal muscles adaptation, models that address the phenomena within a continuum‐mechanical framework using muscle‐specific material models are rare in literature. This work focuses on modelling one form of skeletal musle adaptation, namely sarcomerogenesis. Sarcomerogenesis occurs when a given stretch is sustained over a period of time and the number of basic contractile units, which are the sarcomeres, increase.To model sarcomerogenesis within a continuum‐mechanical setting, the growth framework based on a multiplicative split of the total deformation gradient is employed. An evolution equation that describes sarcomerogenesis is used and incorporated in a transversally isotropic material model that accounts for a skeletal muscle's active force production capabilities. The material tangent modulus is derived and implemented within the finite‐element analysis software. Using this model, one sees that increased number of sarcomeres results in a decreased force response of the muscle tissue over time. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the modelling of finite growth considering the mechanics of cell division
Authors: Bolea Albero Antonio , Böl Markus 
Published: October 2016

AbstractMitotic cells grow in volume and divide themselves into two identical cells producing at macroscopic scale a volume expansion in living bodies. Due to inhomogeneous distributions of the growth factors, growth occurs at different rates and directions. Focusing into the direction of growth, some living bodies alter their growing behaviour influenced by mechanical loads. If loads appear during the growth process, cell division is reorientated following the main direction of the elastic deformations. Therefore, new cells will be created in this direction while relaxing the stress state of the body at the same time. In this work, we present a modelling approach for growing bodies which change their growth direction depending on mechanical loads. The model is implemented into a finite element framework to be an useful tool for predicting morphological changes in growing bodies. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐Infrastructure Real‐Time Embedded Control via Variational Integrators
Authors: Schultz Jarvis , Murphey Todd 
Published: October 2016

AbstractThis paper presents a discrete time receding horizon control scheme that leverages the numerical properties of a variational integrator to facilitate real‐time control generation on an embedded system. The variational integrator employed is well‐suited to classical estimation and control algorithms, e.g. LQR, extended Kalman filters, and particle filters. The structure‐preserving properties of this variational integrator lead to increased performance of estimation and control routines, especially in low‐bandwidth applications. Several experimental examples are presented that illustrate the features of this receding horizon control scheme when leveraging the desirable numerical properties of the variational integrator. © 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flow structures and heat transfer characteristics in arrays of submerged laminar impinging jets
Authors: Rohlfs W. , Bieber M. , Ehrenpreis C. , Jörg J. , Sabelberg E. , Kneer R. 
Published: October 2016

AbstractThis study summarizes the scaling behavior of single laminar submerged jets with circular and planar cross sections. Unified correlations for the stagnation zone heat transfer of both configurations, based on the dominant dimensionless numbers, are presented. In technical applications, impinging jets are often applied in jet array configurations. Compared to single jet impingement, jet‐to‐jet interaction can have a substantial influence on local heat transfer. A distinct pattern of the heat transfer coefficient was observed experimentally. Numerical simulations revealed two counter‐rotating vortices in the interaction zone between two jets to be the causing mechanism of this pattern. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
swMATH – next steps
Authors: Chrapary Hagen 
Published: October 2016

AbstractMathematical software is of increasing importance in teaching activities, research, industry and daily life. But searching and finding information about relevant mathematical software is a non‐trivial task. swMATH [1] is a new and comprehensive information service on mathematical software and mathematical research data. It contains information on nearly 13.000 software packages with more than 120.000 references to scientific articles citing the software. It offers free access to information on software in all mathematical subjects from large general purpose systems to small packages and includes benchmarks, languages, data sets, and web services, too. The paper starts with a short description of our approach and addresses some open problems for the further development. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Risk Assessment of Sea Dumped Conventional Munitions
Authors: Voie Øyvind A. , Mariussen Espen 
Published: October 2016

AbstractEnergetic compounds from dumped ammunition are toxic to aquatic organisms. Leakage of ammunition residues will occur when the bombshells are broken and the energetic compounds come into contact with water. The munitions compounds have a complex behavior in the environment, particularly in the sediment‐water phase, and the calculation of safety levels are dependent on choice of methodology. Estimated sediment quality benchmark levels combined with multi‐increment sampling strategy provide the most proper tool for performing ecological risk assessment at a dump site. Dumped munitions may be located in areas, where shellfish, invertebrates, and benthic or pelagic fish are consumed by humans. A monitoring program for early warning of potential contaminants in the vicinity of fish farms could be conducted by passive samplers for explosives. Further development of both sample procedures and analytical methods to increase the quality of the chemical analyses are encouraged.
The UK Ministry of Defence Project Orientated Environmental Management System (POEMS)
Authors: Galante Erick , Temple Tracey , Ladyman Melissa , Gill Philip P. 
Published: October 2016

AbstractThe Project Orientated Environmental Management System (POEMS) is the UK Ministry of Defence (MoD) bespoke environmental management system for the acquisition and use of equipment. The full implementation of a site‐specific environmental management system is challenging for the MoD because there are many permanent MoD sites with transient populations, frequently changing site activities and diverse types of equipment. Nevertheless, MoD policy requires that all sites are covered by an environmental management system. POEMS is based on international standards ISO14001 and ISO14040, which focus on environmental management systems and life cycle assessment, respectively. The primary aim of POEMS is to identify and manage any environmental aspects (causes) and impacts (effects) by scrutinising MoD equipment and activities during acquisition, operation and disposal. This is achieved by drawing up a priority list of activities associated with the equipment based on anticipated environmental impact scores, resulting in an environmental management plan that spans the life cycle of the equipment and any corresponding activities. This article describes the POEMS procedure for both experts and non‐experts, and demonstrates the implementation of POEMS using a 105‐mm artillery round as a theoretical case study. The results anticipated at each stage of the POEMS procedure are discussed in detail, and the documentation necessary to verify the correct application of POEMS is demonstrated.
In situ X‐ray diffraction of GaAs/MnSb/Ga(In)As heterostructures
Authors: Mousley P. J. , Burrows C. W. , Ashwin M. J. , Takahasi M. , Sasaki T. , Bell G. R. 
Published: October 2016

AbstractWe have investigated the growth by molecular beam epitaxy (MBE) of GaAs on MnSb. MnSb epilayers on GaAs(111), GaAs(001) and of thickness 50 nm were used as substrates for GaAs films. The MBE growth of GaAs was monitored in situ using synchrotron X‐ray diffraction and reflection high energy electron diffraction. We show data on strain relaxation and growth mode, and discuss the epitaxial relationship between GaAs(001) and MnSb(101).Schematic of the molecular beam epitaxy/X‐ray diffraction in situ experiment and typical 2D detector data, with GaAs(111) and MnSb(0001) diffraction features.
Depth sensitive X‐ray diffraction as a probe of buried half‐metallic inclusions
Authors: Burrows C. W. , A. Hase T. P. , Ashwin M. J. , Mousley P. J. , Bell G. R. 
Published: October 2016

AbstractThe ferromagnetic material MnSb can exist in two polymorphs in epitaxial thin‐film form, namely niccolite n‐MnSb and cubic c‐MnSb. We investigate the behavior of these polymorphs using grazing incidence depth‐dependent in‐plane X‐ray diffraction. The in‐plane lattice parameter evolution of a nominal 3000 Å thin film reveals a small near‐surface compression of 0.1% in the majority n‐MnSb component. A similar effect is also observed for the cubic polymorph, suggesting that the local strain environment of these crystallites is dominated by the n‐MnSb matrix.Collated in‐plane X‐ray diffraction data from a GaAs/ heterostructure in the near‐surface region with probing depths ranging between 20 and 450 Å. Present are two of the polymorphs of MnSb: the niccolite (n‐) and cubic zincblende (c‐) phases.
Feedback sensitivity functions analysis of finite‐time stabilizing control system
Authors: Zimenko K. , Polyakov A. , Efimov D. , Kremlev A. 
Published: October 2016

SummaryThis paper presents feedback sensitivity functions analysis of implicit Lyapunov function‐based control system in case of finite‐time stabilization problem. The Gang of Four is chosen as a feedback sensitivity tool. The results can be used for parametric tuning of control algorithms in order to guarantee desired closed‐loop sensitivity specifications. The obtained results are supported by numerical examples. Copyright © 2016 John Wiley & Sons, Ltd.