bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation‐based optimisation of wastewater flow and composition for on‐site treatment in the food and beverage industry utilising reference nets in combination with genetic algorithms
Authors: Hubert Stefan , Pettigrew Liam , Helmers Thorben , Mießner Ulrich , Groß Frauke , Räbiger Norbert , Delgado Antonio 
Published: December 2014

AbstractThis study introduces the concept of computer modelling and simulation of complex bioprocesses and systems using an approach that combines the reference net formalism with machine learning and optimisation techniques. Reference nets are an extension of high level Petri Nets, which can be used as a central visualisation and modelling tool. The net‐in‐net paradigm used by reference nets makes it possible to model complex processes, such as those found in the food and beverage industry. A plugin/interface system based on the java programming language allows implementation of advanced mathematical modelling techniques at specific points in entire system simulations. Separate optimisation tools can also run and modify existing reference net models for fast solutions to efficiency problems. We present an example system that simulates a specific section of a beer brewery using the reference net formalism, which is optimised using a genetic algorithm. We show in detail how the different software packages can be combined for a simulation based optimisation approach. The optimisation technique specifically addresses the wastewater pollution load in regard to its chemical oxygen demand. A beer brewery was chosen as an example for this study due to the constantly increasing requirements to lower energy and water consumption in this industry. One possibility to lower the energy and water demands is to effectively treat wastewater produced by the brewery, which can introduce cost savings by providing recycled water and biogas. Most approaches to wastewater treatment are end‐of‐pipe solutions that do not consider the brewery as a whole. A brewery contains many processes that can be running concurrently and interacting with one another (e.g. brewing, clean‐in‐place and bottling) with each process producing varying amounts of wastewater with different pollution loads. Optimisation of the scheduling of the different processes with respect to the wastewater production will allow for more effective wastewater treatment, and therefore cost and energy savings. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improving robustness of the FEAST algorithm and solving eigenvalue problems from graphene nanoribbons
Authors: Galgon Martin , Krämer Lukas , Lang Bruno , Alvermann Andreas , Fehske Holger , Pieper Andreas 
Published: December 2014

AbstractWe consider the FEAST eigensolver, introduced by Polizzi in 2009 [5]. We describe an improvement concerning the reliability of the algorithm and discuss an application in the solution of eigenvalue problems from graphene modeling. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase Retrieval from 4N−4 Measurements: A Proof for Injectivity
Authors: Philipp Friedrich 
Published: December 2014

AbstractWe prove by means of elementary methods that phase retrieval of complex polynomials p of degree less than N is possible with 4N − 4 phaseless Fourier measurements of p and p′. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scalability of a FETI‐DP Method for Optimal Control Problems
Authors: Herzog Roland , Rheinbach Oliver 
Published: December 2014

AbstractA parallel FETI‐DP (Finite Element Tearing and Interconnecting) domain decomposition method is applied to optimal control problems with control constraints. We show parallel scalability for up to 1024 cores of a Cray XT6. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Error‐Controlled Model Order Reduction of Second Order Systems with Adaptive Choice of Shifts and Order
Authors: Panzer Heiko K. F. , Wolf Thomas , Lohmann Boris 
Published: December 2014

AbstractThis contribution summarizes a novel approach to error‐controlled model order reduction of second order systems, i. e. a new way to find a reduced order model of specified approximation quality. To this end, starting from a particular state space realization of the model, one performs multiple reduction steps and increments the reduced model until (computationally affordable) rigorous global error bounds fall below the prescribed limit. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some notes on monotonicity preserving schemes on adaptive grids
Authors: Shokina Nina 
Published: December 2014

AbstractBy the example of the 1D transport equation with constant coefficient and the 2D linear transport equation with variable coefficients, the monotonization approach for two‐step explicit finite‐difference schemes is presented, based on studying scheme differential approximations [1,2]. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bubble dynamics: Long‐time behavior and interaction in viscous liquids
Authors: Wolf Alexandre , Masood Rao M. A. , Delgado Antonio , Rauh Cornelia 
Published: December 2014

AbstractA mathematical two‐phase model is used to numerically investigate physical and rheological effects on small, individual bubbles in high‐viscosity liquids under pressure impact. It is found out that bubbles remain stable over time at high viscosity and surface tension. The steady case is considered and connected to the stability behavior of the bubble. An upper bound for the bubble radius is derived and the new equilibrium state of the bubble can be predicted by means of stability theorems of differential equations. Finally, the interaction of a limited number of well separated bubbles in an Hele‐Shaw flow is mathematically analyzed to visualize and physically interpret their trajectories. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability analysis of phase fitted variational integrators
Authors: Kosmas Odysseas , Leyendecker Sigrid 
Published: December 2014

AbstractIn the present work, we discuss the benefits, limitations and restrictions for the high order phase fitted variational integrators, derived specifically for the numerical integration of systems with oscillatory solutions. To do that, we study linear stability properties of these methods using the eigenvalues of the amplification matrix. The obtained stability region verifies their good behavior, when used for the numerical solution of highly oscillatory problems. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
TVD‐based Finite Volume Methods for Sound‐Advection‐Buyancy Systems
Authors: Knoth Oswald , Naumann Andreas , Wensch Jörg 
Published: December 2014

AbstractSplit‐explicit Runge‐Kutta methods provide an efficient integration procedure for hyperbolic systems with coupled slow and fast wave phenomena. They are generalized to multirate infinitesimal step methods (MIS) in order to develop an order to provide order conditions and to establish stability properties. The construction of MIS methods is based on an underlying Runge‐Kutta method. This method is choosen to be total variation diminishing (TVD) to improve the stability properties of the method. Here, the maximum Courant number is improved by a factor of 4. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hierarchical Constraint‐Based Singularity Avoidance for Multi‐Axis Robots
Authors: Nordheimer Eugen , Wagner Achim , Badreddin Esammedin 
Published: December 2014

AbstractA generalized reflexive approach for Hierarchical Constraint‐Based Singularity Avoidance (HCB‐SA) is proposed and demonstrated for the multi‐axis robot control of a six Degrees Of Freedom (DOF) hybrid manipulator system. The concept utilizes a dynamic adaptation of virtual constraints by introducing virtual damped actuation on the velocity control level and an anisotropic reflexive trajectory deflection depending on the robot constraints on the position control level. Redundant or low priority DOFs can be used to minimize the pose error in the more important DOFs reflexively without calculating new trajectories. Accordingly, the end‐effector can be safely controlled in the vicinity of singularities and all constraints in the task and joint space can be surely hold. Furthermore, the proposed cascaded feedback control with the generalized HCB‐SA algorithm is able to react on the presence of external disturbances which is validated using software‐in‐the‐loop simulation on the real‐time control system. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Motion planning for a piezo‐actuated structure modeling a wingsail
Authors: Kater Andreas , Meurer Thomas 
Published: December 2014

AbstractThis contribution presents the modeling and the motion planning of a flexible interconnected beam structure representing a wingsail. The structure is equipped with spatially distributed embedded actuators. The solution of the motion planning provides a feedforward control law to realize a desired spatial‐temporal out‐of‐plane deflection trajectory. For this, a systematic flatness‐based methodology is proposed, that allows for an efficient numerical solution exploiting, e.g., finite element approximations. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flatness‐based Feed‐forward Control for an Elastic Heavy Rope
Authors: Knüppel Torsten , Woittennek Frank 
Published: December 2014

AbstractConsidered is the feed‐forward control design for an elastic heavy rope that is model by a quasilinear partial differential equation of hyperbolic type. The problem is solved by means of a flatness‐based approach that involves the solution of a Cauchy problem associated with the model equation. Simulation results are given to illustrate the results. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Supply Chain Optimization via Distributed Model Predictive Control
Authors: Pannek Jürgen , Frazzon Enzo 
Published: December 2014

AbstractSupply chains networks describe the flow of material, energy and information from their sources to end costumers. Typically, such a network consists of several stages such as suppliers, manufacturers and retailers, which contribute to the completion of a product. Here, we restrict ourselves to one arc from supplier to costumer. Instead of known strategies such as postponement, we apply a model predictive control scheme to deal with the optimal steering problem of the considered arc in a distributed way. To this end, we assign one controller to each stage along the considered arc. Since the stages may represent different companies, local cost criteria are imposed, which are optimized subject to local and global constraints while communicating with neighbors. Additionally, we discuss the applicability of such an approach regarding information requirements and respective policies of companies. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Topology Based Discretization of PDAEs Describing Water Transportation Networks
Authors: Huck Christoph , Jansen Lennart , Tischendorf Caren 
Published: December 2014

AbstractWe consider partial differential algebraic systems (PDAEs) describing water transportation networks. Similar to the approach in [6], we follow the method of lines for the discretization. However, we do not consider free surface flow models but pressure flow models covering hydraulic shocks. Moreover, we include switching models reflecting the on/off state of pumpes and valves. Aiming at a stable numerical simulation of the PDAEs we present a topology based spatial discretization that results in a differential algebraic system (DAE) of index 1. Furthermore we show that the DAE index can be higher than 1 if the spatial discretization is not adapted to the position of reservoirs and demand nodes within the network. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some Remarks on High Gain Observer Design
Authors: Röbenack Klaus 
Published: December 2014

AbstractHigh gain observer design can be carried out for nonlinear systems, whose dynamics can be decomposed into a linear and a Lipschitz continuous nonlinear part. The observer uses a linear output injection, which is specified by a constant gain matrix. Due to this simple structure, high gain observers are frequently used in practical applications. The observer gain is often chosen via eigenvalue placement. However, the formal existence conditions are more complicated. In many cases, there is a finite bound on the maximum feasible Lipschitz constant of the nonlinear part for which the error dynamics can be stabilized. The existing results can be improved significantly, if the structure of the linear part is taken into account. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sobolev regularity of multipliers in multidimensional control problems of Dieudonné‐Rashevsky type
Authors: Wagner Marcus 
Published: December 2014

AbstractWithin Pontryagin's maximum principle for Dieudonné‐Rashevsky type problems with convex or polyconvex data, the multipliers associated with the state equation may be chosen from an appropriate Sobolev space. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low noise regimes for ℓ regularization : continuous and discrete settings
Authors: Duval Vincent , Peyré Gabriel 
Published: December 2014

AbstractWe focus on support recovery for signal deconvolution with sparsity assumption. We adopt the continuous setting defined by several recent works and we try to reconstruct a sum of Dirac masses from its low frequencies (possibly perturbed by some noise), by using a total variation prior for Radon measures (i.e. the generalization to measures of the ℓ1 norm). We show that, under a non degenerate source condition, there exists a small noise regime in which the model recovers exactly the same number of spikes as the original signal, and the spikes converge to those of the original signal as the noise vanishes. This continuous setting, by allowing the spikes to “move”, provides robust support recovery for signals composed of well separated spikes.In a discrete setting, where the spikes are reconstructed on a grid, similar low noise regimes which guarantee the exact recovery of the support also exist (see [3]). Yet, this property only concerns a small class of signals. Considering the asymptotics of the discrete problems as the size of the grid tends to zero, we show that the support of the original signal cannot be stable on thin grids, and that the discrete models actually reconstruct pairs of spikes near each original spike. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective discretization of the two‐dimensional wave equation
Authors: Görner Torsten , Kunis Stefan 
Published: December 2014

AbstractThe wave equation and associated spherical means are a widespread model in modern imaging modalities like photoacoustic tomography. We consider a discretization for the Cauchy problem of the two dimensional wave equation by plane waves. The considered frequencies lie on a Cartesian or on a polar grid which gives rise to efficient algorithms for the computation of the spherical means. The theoretical findings are illustrated by a some numerical experiments. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometry + Simulation Modules: Implementing Isogeometric Analysis
Authors: Jüttler Bert , Langer Ulrich , Mantzaflaris Angelos , Moore Stephen E. , Zulehner Walter 
Published: December 2014

AbstractIsogeometric analysis (IGA) is a recently developed simulation method that allows integration of finite element analysis (FEA) with conventional computer‐aided design (CAD) software [1,3]. This goal requires new software design strategies, in order to enable the use of CAD data in the analysis pipeline. To this end, we have initiated G+SMO (Geometry+Simulation Modules), an open‐source, C++ library for IGA. G+SMO is an object‐oriented, template library, that implements a generic concept for IGA, based on abstract classes for discretization basis, geometry map, assembler, solver and so on. It makes use of object polymorphism and inheritance techniques to provide a common framework for IGA, for a variety of different basis‐types which are available. A highlight of our design is the dimension independent code, realized by means of template meta‐programming. Some of the features already available include computing with B‐spline, Bernstein, NURBS bases, as well as hierarchical and truncated hierarchical bases of arbitrary polynomial order. These basis functions are used in continuous and discontinuous Galerkin approximation of PDEs over (non‐)conforming multi‐patch computational (physical) domains. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Achieving Portable High Performance for Iterative Solvers on Accelerators
Authors: Rupp Karl , Tillet Philippe , Jüngel Ansgar , Grasser Tibor 
Published: December 2014

AbstractWe propose performance enhancements for the implementation of the conjugate gradient method and the generalized minimum residual method for accelerators such as graphics processing units. Through a minimization of memory transfers from global memory via pipelining as well as a reduction of the number of compute kernels through kernel fusion, the performance is improved by up to two‐fold when compared to standard implementations based on vendor‐tuned routines. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Elastic Solids with Micro‐Structure.
Authors: Picard Rainer 
Published: December 2014

AbstractAbstract. Based on the general framework of evolutionary equations in the sense of [6,8] and referring to well‐posedness results in the context of evolutionary problems from mathematical physics we consider two problems from elasticity theory as particular applications. Our structural perspective is illustrated by showing that the theory of elastic solids with micro‐structure can be transparently embedded into the abstract solution theory. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Note on Exponential Stability for Evolutionary Equations.
Authors: Trostorff Sascha 
Published: December 2014

AbstractAn abstract notion of exponential stability within the framework of evolutionary equations is provided. Sufficient conditions for the exponential stability are given in terms of the so‐called material‐law operator, which is defined via an operator‐valued analytic function. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a class of Sturm‐Liouville operators which are connected to PT symmetric problems
Authors: Azizov Tomas Ya. , Trunk Carsten 
Published: December 2014

AbstractA prominent class of
$\cal PT$
‐symmetric Hamiltonians is

for some nonnegative number N. The associated eigenvalue problem is defined on a contour Γ in a specific area in the complex plane (Stokes wedges), see [3, 5]. In this short note we consider the case N = 2 only. Here we elaborate the relationship between Stokes lines and Stokes wedges and well‐known limit point/limit circle criteria from [6,10,11]. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hypocoercivity for degenerate Kolmogorov equations and applications to the Langevin dynamics
Authors: Grothaus Martin , Stilgenbauer Patrik 
Published: December 2014

AbstractWe present an extension of the powerful Hilbert space hypocoercivity method that was developed originally by Dolbeault, Mouhot and Schmeiser. We focus attention on including important domain issues that have not been considered before. The setting can be used to provide a complete elaboration of the hypocoercivity theorem for the degenerate Langevin dynamics. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A hypocoercivity related ergodicity method for Kolmogorov equations
Authors: Grothaus Martin , Stilgenbauer Patrik 
Published: December 2014

AbstractWe develop a new abstract strategy for proving ergodicity with explicit computable rate of convergence for diffusions associated with a degenerate Kolmogorov operator L. A crucial point is that the evolution operator L may have singular and nonsmooth coefficients. This allows the application of the method e.g. to the degenerate Nparticle Langevin dynamics. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dictionary Learning and Non‐Asymptotic Bounds for Geometric Multi‐Resolution Analysis
Authors: Maggioni Mauro , Minsker Stanislav , Strawn Nate 
Published: December 2014

AbstractData sets in high‐dimensional spaces are often concentrated near low‐dimensional sets. Geometric Multi‐Resolution Analysis (Allard, Chen, Maggioni, 2012) was introduced as a method for approximating (in a robust, multiscale fashion) a low‐dimensional set around which data may concentrated and also providing dictionary for sparse representation of the data. Moreover, the procedure is very computationally efficient. We introduce an estimator for low‐dimensional sets supporting the data constructed from the GMRA approximations. We exhibit (near optimal) finite sample bounds on its performance, and demonstrate the robustness of this estimator with respect to noise and model error. In particular, our results imply that, if the data is supported on a low‐dimensional manifold, the proposed sparse representations result in an error which depends only on the intrinsic dimension of the manifold. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of microscopic failure in heterogeneous materials
Authors: Müller Sebastian , Kästner Markus , Ulbricht Volker 
Published: December 2014

AbstractThe proper modeling of state‐of‐the‐art engineering materials requires a profound understanding of the nonlinear macroscopic material behavior. Especially for heterogeneous materials the effective macroscopic response is amongst others driven by damage effects and the inelastic material behavior of the individual constituents [1]. Since the macroscopic length scale of such materials is significantly larger than the fine‐scale structure, a direct modeling of the local structure in a component model is not convenient. Multiscale techniques can be used to predict the effective material behavior. To this end, the authors developed a modeling technique based on representative volume elements (RVE) to predict the effective material behavior on different length scales. The extended finite element method (XFEM) is used to model discontinuities within the material structure independent of the underlying FE mesh. A dual enrichment strategy allows for the combined modeling of kinks (material interfaces) and jumps (cracks) within the displacement field [2]. The gradual degradation of the interface is thereby controlled by a cohesive zone model. In addition to interface failure, a non‐local strain driven continuum damage model has been formulated to efficiently detect localization zones within the material phases. An integral formulation introduces a characteristic length scale and assures the convergence of the approach upon mesh refinement [3]. The proposed method allows for an efficient modeling of substantial failure mechanisms within a heterogeneous structure without the need of remeshing or element substitution. Due to the generality of the approach it can be used on different length scales. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
LMI‐based second‐order sliding set design using reduced order of derivatives
Authors: Márquez Raymundo , Tapia Alán , Bernal Miguel , Fridman Leonid 
Published: December 2014

SummarySliding mode control design for systems with relative degree r requires a number r − 1 of time‐derivatives of the system output, which usually leads to deterioration of the whole scheme; if the highest‐order derivative is spared, a better precision is ensured. This paper proposes a control algorithm that guarantees reaching a second‐order sliding manifold using only r − 2 derivatives of the system output. This objective is achieved at the price of yielding finite‐time convergence while preserving the essential feature of insensitivity to matched disturbances. The results take full advantage of convex representations and linear matrix inequalities, whose formulation easily allows dealing with unmatched disturbances by convex optimization techniques already implemented in commercially available software. Simulation examples are included to show the effectiveness of the proposed approach. Copyright © 2014 John Wiley & Sons, Ltd.