bluuebunny/crossref_metadata_2025_split huggingface dataset:
Movement Disorders in Treatable Inborn Errors of Metabolism
Authors: Ebrahimi‐Fakhari Darius , Van Karnebeek Clara , Münchau Alexander 
Published: December 2018

ABSTRACTThere are several hundred single‐gene disorders that we classify as inborn errors of metabolism. Inborn errors of metabolism are often rare and highly heterogeneous multisystem diseases with non‐neurological and neurological manifestations, commonly with onset during childhood. Movement disorders are among the most common neurological problems in inborn errors of metabolism, but, in many cases, remain poorly defined. Although movement disorders are usually not the only and often not the presenting symptom, their recognition can facilitate a diagnosis. Movement disorders contribute substantially to the morbidity in inborn errors of metabolism and can have a significant impact on quality of life. Common metabolic movement disorders include the monoamine neurotransmitter disorders, disorders of amino and organic acid metabolism, metal storage disorders, lysosomal storage disorders, congenital disorders of autophagy, disorders of creatine metabolism, vitamin‐responsive disorders, and disorders of energy metabolism. Importantly, disease‐modifying therapies exist for a number of inborn errors of metabolism, and early recognition and treatment can prevent irreversible CNS damage and reduce morbidity and mortality. A phenomenology‐based approach, based on the predominant movement disorder, can facilitate a differential diagnosis and can guide biochemical, molecular, and imaging testing. The complexity of metabolic movement disorders demands an interdisciplinary approach and close collaboration of pediatric neurologists, neurologists, geneticists, and experts in metabolism. In this review, we develop a general framework for a phenomenology‐based approach to movement disorders in inborn errors of metabolism and discuss an approach to identifying the “top ten” of treatable inborn errors of metabolism that present with movement disorders—diagnoses that should never be missed. © 2018 International Parkinson and Movement Disorder Society
A complementary Sierpinski gasket fractal antenna array for wireless MIMO portable devices
Authors: Kaur Amanpreet , Gupta Sheifali 
Published: December 2018

AbstractThis research work reports the design and development of a novel complementary Sierpinski gasket fractal microstrip antenna array to achieve a good impedance bandwidth and hence support high data rates for 4G/5G MIMO applications. The proposed array is a compact structure (136 mm × 136 mm) designed with complimentary Sierpinski gasket fractal up to two iterations and has a defected ground to improve the antenna's performance. The antenna performance reports an 8.2% bandwidth at the center frequency of 4.94 GHz (4.7434‐5.1514 GHz), a simulated diversity gain of 9.99 allows the proposed array to be well suitable for proposed applications and a directivity of around 5.8 dBi suits good range characteristics. The array designing and optimization is carried out with 3D EM tool CST MWS V'14 using perfect boundary approximations. A simulated low value of envelope correlation coefficient (0.04) indicates that the two antennas in the array provide least interference to each other while radiating. The measured S11 results on a VNA E 5071C show a close match with the simulated results. Thus a compact array size with good bandwidth, radiation characteristics, low ECC and a high diversity gain allow the antenna array to be well suitable for portable MIMO 4G/5G wireless applications specifically for C band and military applications.
A system for profiling the IXPs in a region and monitoring their growth: Spotlight at the internet frontier
Authors: Fanou Rodérick , Sanchez‐Agüero Victor , Valera Francisco , Mwangi Michuki , Coffin Jane 
Published: December 2018

SummaryThis work aims at designing and implementing a system able to profile and help manage the set of Internet eXchange Points (IXPs) in an Internet region. As part of the Internet Society's strategy to help monitor and understand the evolution of IXPs in a particular region, a route‐collector data analyzer tool was developed before being deployed and tested in AfriNIC. In fact, traffic localization efforts in the African peering ecosystem would be more sustained, and their efficacy assessed if they were supported by a platform, which evaluates and reports in real time about their impact on the Internet. We, thus, built the “African” Route‐collectors Data Analyzer (ARDA), an open source web platform for analyzing publicly available routing information collected since 2005, by local route‐collectors. ARDA evaluates predefined metrics that picture the status of the interconnection at local, national, and regional levels. It shows that a small proportion of AfriNIC ASes (roughly 17%) are peering in the region. Through them, 58% of all African networks are visible at one IXP or more. These have been static from April to September 2017, and even February 2018, underlining the need for increased efforts to improve local interconnectivity. We show how ARDA can help detect the impact of policies on the growth of local IXPs or continually provide the community with up‐to‐date empirical data on the evolution of the IXP substrate. Given its features, this tool will be a helpful compass for stakeholders in the quest for better traffic localization and new interconnection opportunities in the targeted region.
A New Holistic Approach to the Local Buckling Behaviour of Open‐Profile Composite Laminated Beams
Authors: Schreiber Philip , Mittelstedt Christian 
Published: December 2018

AbstractThe present work deals with the local buckling of thin‐walled composite‐beams with I, Z, C, L and T‐cross‐sections under axial load. In this study the analysis of the buckling load of the complete composite‐beam is performed using the Ritz‐method. The individual webs and flanges of the beam are assembled by suitable continuity conditions in one system. In order to achieve that, new displacement shape functions for web and flange that fulfill all boundary conditions have been developed. The present closed‐form analytical method enables the explicit representation of the buckling load for the entire composite‐beam under axial load. The comparison between the present approach and finite element simulations shows a satisfactory conformity. The present method is highly efficient in terms of computational effort and its practical suitability.
Operator splitting for stiff chemical reaction systems
Authors: Lukassen Axel Ariaan , Kiehl Martin 
Published: December 2018

AbstractChemical reaction systems often result in high‐dimensional, stiff differential equations. Solving these differential equations is computational demanding. The computational effort can be reduced by the usage of an operator splitting scheme. The most frequently used splitting schemes are the Lie‐Trotter splitting [1] and the Strang splitting [2]. However, the usage of a splitting scheme results in an additional splitting error. The Lie‐Trotter splitting is a first order scheme, and the Strang splitting is a second order scheme. If the timescale of the fastest chemical reaction is smaller than the splitting time step, the Strang splitting suffers from order reduction. Therefore, the Lie‐Trotter splitting and the Strang splitting are first order schemes for reasonable step sizes. The Richardson extrapolation of the Lie‐Trotter splitting is a second order scheme. We show that the Richardson extrapolation does not suffer from order reduction for a splitting between a fast chemical source term and a slow transport term.
PIV Measurements and Numerical Simulations in a 2D‐Extruder
Authors: Hirschfeld Stefan , Wünsch Olaf 
Published: December 2018

AbstractThis work is concerned with the fluid flow in a special fully and partially filled 2D‐extruder model with a double flighted single‐screw and twin‐screw geometry. A shear‐thinning highly viscous silicone oil is used as model substance. The results of Particle Image Velocimetry (PIV) measurements are compared with numerical simulations.
Predicting Skeletal Muscle Force from Motor‐Unit Activity using a 3D FE Model
Authors: Saini Harnoor , Altan Ekin , Ramasamy Ellankavi , Klotz Thomas , Gizzi Leonardo , Röhrle Oliver 
Published: December 2018

AbstractHomogenised finite‐element (FE) skeletal muscle models provide a good trade‐off between computational efficiency and physiological realism. This trade‐off is in part due to the lack of explicit modelling of muscle fibres (MFs). As a consequence, the organisation of MFs into motor‐unit territories (MUTs) is particularly challenging. The current paper presents a possible technique to adress this issue by assigning MUTs in a homogenised sense in terms of muscle volume to FE skeletal muscle models. This method allows control of inter‐MUT distance, the amount of intermingling between MUTs and the order of MUT assignment. It was found that both assigning smaller MUTs first and allowing a moderate amount of intermingling significantly influence MUT distributions. This technique allows a simplified and straight‐forward way to introduce MUTs into 3D FE skeletal muscle models.
Time step estimates for explicit dynamics with reciprocal mass matrices
Authors: Tkachuk Anton , Schaeuble Anne‐Kathrin , Bischoff Manfred 
Published: December 2018

AbstractIn this contribution, a novel local, node‐based time step estimate for explicit dynamics with reciprocal mass matrices is presented. Reciprocal mass matrices are sparse matrices used in explicit dynamics that allow computation of nodal acceleration from the total force vector. They can be built algebraically and variationally and aim for higher critical time steps or/and accuracy than the lumped mass matrix approximation. Since the element eigenvalue inequality by Fried is not valid for reciprocal mass matrices, element‐based estimates may be not conservative and they are consequently inadequate. Therefore, the nodal time step estimate for diagonally lumped mass matrices based on Gershgorin's theorem is further developed for application to reciprocal mass matrices. Additionally, simplifications of the proposed time step estimate that improve computational efficiency, especially for contact problems with the penalty method, are discussed. These simplifications use subadditivity and submultiplicativity properties of expressions used in the estimate. Finally, efficiency of the proposed estimate is illustrated by a numerical example.
Effects of aging on the thermo‐mechanical response of a die casting alloy
Authors: Martinez Page Maria Angeles , Hartmann Stefan 
Published: December 2018

AbstractZamak alloys can be found in a wide variety of components of the automotive, building, electronic, and toy industry. They are preferred to other materials for die casting foundry due to their several advantages. For example, they exhibit a low melting point which allows an economic manufacturing process, they allow the production of components with tight tolerances and are characterized by good mechanical properties. Nonetheless, these alloys show a change in their mechanical behavior over time. This phenomenon is known as aging and it is associated to microstructural transformations such as diffusion and precipitation of alloying elements and phase transformations. In this work, the influence of natural aging on the thermo‐mechanical response is investigated with the help of tension, compression and torsion experiments and a model with aging as an internal variable is proposed.
Droplet deformation, oscillation and detachment on a vibrating plate by a controlled airflow
Authors: Barwari Beawer , Burgmann Sebastian , Janoske Uwe 
Published: December 2018

AbstractIn this work, a detailed experimental study on the influence of fluid properties on the droplet behavior subjected to a shear flow and harmonic surface vibration is conducted. The experiments were executed in a rectangular channel and an acrylic channel wall was utilized to analyze the droplet wetting behavior. Both the effect of shearing mechanism induced by airflow and harmonic vibration induced by an electromagnetic shaker for droplet volumes in the range of 5−40 µl are studied here. Furthermore, the effect of fluid viscosities on the motion of droplets is analyzed for a wide range of water and glycerine mixture ratios. Experiments show that the critical bulk velocity at which the droplet movement begins is a function of fluid properties and droplet sizes. Increasing the droplet volume results in a decrease of the critical bulk velocity, while the droplet deformation increases. On the contrary, increasing the glycerine content of the liquid droplets results in an increase in both the critical bulk velocity and droplet deformation. The droplet movement can be categorized into three motion patterns based on experimental observations: (i) the droplet shape is largely retained with a small tail formation at the rear end, (ii) small droplets detach from the tail at rear end of the main droplet, (iii) the droplet deforms over its entire length resulting in forming of a film.
On computational interdisciplinary modeling for reliability assessment of high‐speed train – bridge interaction
Authors: Adam Christoph , Hirzinger Benjamin , Oberguggenberger Michael , Salcher Patrick 
Published: December 2018

AbstractBridge and crossing high‐speed train represent an uncertain interacting dynamic system of high complexity with, in general, time‐dependent system matrices. Thus, full reliability assessment of this system can only be conducted efficiently in an interdisciplinary approach, bringing together the disciplines of structural mechanics, engineering mathematics, and high performance computing. This contribution gives a brief summary on computational modeling issues of uncertain bridge‐train interaction, its efficient stochastic simulation, and an outline of pros and cons of different strategies is provided.
Sensitivity Analysis of a Two‐Lens System for Positioning Feedback
Authors: Schindlbeck Christopher , Pape Christian , Reithmeier Eduard 
Published: December 2018

AbstractPrecise alignment of optical components is crucial for the assembly of optical system. Misaligned components (due to positioning tolerances) lead to a distorted wavefront that deviates from a desired wavefront given by an initial nominal design. Inferring the current poses of optical components solely from detector measurements is a difficult but necessary task in order to calculate corrections for feedback control without using external measurement devices. In this paper, we aim at deducing lens poses of a two‐lens system solely from wavefront measurements. The wavefront can be decomposed into a finite sequence of polynomials which are weighted by coefficients. Since pose deviations directly lead to deviations in the wavefront (and therefore in the wavefront coefficients), a sensitivity matrix can be established. The choice of lens poses and wavefront coefficients determines the sensitivity matrix which is often ill‐conditioned and may potentially suffer from rank loss. We conduct a sensitivity analysis and show how the sensitivity matrix can be utilized to generate a linear estimate of the optical component poses. This estimate can then be used to close the feedback loop. Validation is conducted by simulating an optical system consisting of a laser, two bi‐convex lenses, and a wavefront sensor.
Heuristic pressure profiles in hydraulic fracturing
Authors: Schätzer Markus , Fries Thomas‐Peter 
Published: December 2018

AbstractIn hydraulic fracturing, the pressure exerted by the fracking fluid onto the surrounding solid, is typically obtained from solving the Reynolds equation. This is not always robust and leads to a complex behaviour at the crack front (toughness or viscous regimes). In the presented work, the Reynolds equation is replaced by a simplified fluid model, where pre‐defined pressure distributions are assumed which lead to a simpler and robust coupled problem. The mapping of dimensionless prescribed pressure distributions onto the physical crack surface of the mesh is discussed based on a dimensionless distance function. This function is obtained by solving the Laplace‐Beltrami operator on the explicit representation of the manifold, i.e., the surface mesh, where distances are evaluated along streamlines which represent the fluid flow of the fracking fluid within the fracture.
Application and adaption of Dynamic Mode Decomposition to experimental and numerical data of turbomachinery flow
Authors: Walter Christian‐Henrik , Krieg Marinho 
Published: December 2018

AbstractUnsteady turbomachinery flows are challenging in terms of resolving turbulent characteristics and instability mechanisms like rotating stall, rotor‐stator interaction and von Karmán vortex streets. Furthermore, in part load conditions these flow phenoma can induce vibrations leading to resonance problems and high cycle fatigue. Flowfield measurements of a centrifugal fan were taken by high‐speed particle image velocimetry (PIV). CFD results, calculated as unsteady Reynolds averaged Navier Stokes (URANS) and based on Menter's shear‐stress transport (SST) model, are the source of numerical data. In former examinations discrepancies between experiment and simulation in time‐averaged velocity profil data for part load conditions have been stated. The source of theses discrepancies is still unknown. Hence, a new approach is needed for further examination of measured and calculated flowfields. The Dynamic Mode Decomosition is employed in order to compare experimental and numerical datasets. Information about coherent structures and the dynamical behaviour are contained in the eigenvalues and their associated eigenvectors offered by DMD. While the eigenvectors are describing the coherent structures, the associated eigenvalues describe the dynamic behaviour of the structure. The eigenvectors are denoted as DMD‐Modes. The results acquired by DMD based on experimental and numerical data are compared to investigate congruent behaviour and therefore if it is possible to obtain reliable information about dynamic behaviour of a system even with URANS simulations. Comparisons between singular value and eigenvalues are presented and discussed.
Efficient basis updating for parametric nonlinear model order reduction
Authors: Meyer Christian H. , Lerch Christopher , Karamooz Mahdiabadi Morteza , Rixen Daniel 
Published: December 2018

AbstractNonlinear model reduction is used to speed up the numerical solution of finite element models for vibration analysis of structures undergoing large deflections. This speed up is highly desired in design and optimization applications where parametric models are considered and the outcoming high‐dimensional differential equation must be solved multiple times. A first step is to approximate the solution vector i.e. the displacements of the nodes by a linear combination of some basis vectors. One common choice for these basis vectors is a combination of vibration modes and static modal derivatives. However, these vectors depend on parameter values of the parameterized system. This contribution shows how these basis vectors can be updated in an efficient manner. The vibration modes are updated by an inverse free preconditioned Krylov subspace method while the static derivatives are updated by a preconditioned conjugate gradient solver. A case study with a parametric beam gives a first insight into the performance of the proposed method.
Variational Integrators and Optimal Control for a Hybrid Pendulum‐on‐Cart‐System
Authors: Kern Dominik , Groß Michael 
Published: December 2018

AbstractHybrid systems combine continuous‐time and discrete‐time dynamics. They emerge in mechanical systems, inter alia, when collisions are modelled by impulse‐like contact forces. During collisions of two or more bodies, the positions of the latter evolve continuously, but their velocities experience jumps. On the one hand, this non‐smoothness significantly complicates the optimal control problem; on the other, it opens up opportunities for new numerical methods. This contribution uses a nested optimization in order to control the swinging up of a hybrid pendulum‐on‐cart‐system. Both, pendulum and cart, move in finite ranges which are bounded by limiters (elastic collisions). The outer layer optimizes the occurence and the momenta of the collisions, while the inner layer optimizes the smooth motions from start to collision, from collision to collision, and finally to the terminal state. The discretization and the optimal control of continuous‐time dynamics are based on the Discrete‐Mechanics‐and‐Optimal‐Control (DMOC) approach.
One‐dimensional turbulence investigation of incompressible and low Mach number variable density pipe‐flow
Authors: Medina Méndez Juan A. , Schmidt Heiko 
Published: December 2018

AbstractCylindrical pipe‐flow is evaluated by means of the One‐Dimensional Turbulence (ODT) model applying both an incompressible and a low Mach number variable density framework. In the variable density formulation, the velocity field is decomposed into density‐related (non‐divergence‐free) and density‐unrelated (divergence‐free) contributions, as detailed in Medina et al. [Combust. Flame 190 (2018) 388‐401]. Both contributions to the velocity field are subject to the effects of diffusion and turbulent transport, as it is normally the case for the incompressible velocity field in traditional ODT formulations. The turbulent transport is implemented by means of stochastic eddy events. These are influenced by the available kinetic energy given by the divergence‐free velocity contribution. An eddy may arise from the different regions of shear caused by varying velocity gradients in the 1‐D domain, but also as a consequence of the temperature‐varying dynamic viscosity. The cylindrical low Mach number variable density formulation is tested in a very low heat transfer regime and compared to the passive scalar results of the incompressible pipe‐flow formulation. ODT model parameters are assumed equal for both formulations. ODT results are compared to DNS results from Satake and Kunugi [Int. J. Numer. Methods Heat Fluid Flow 12 (2002) 958‐1008]. The passive scalar and variable density results show very good agreement with each other as well as with DNS data, respectively, thus suggesting new possible applications for ODT.
A task space admittance control algorithm for safe human robot interaction
Authors: Kaserer Dominik , Gattringer Hubert , Müller Andreas 
Published: December 2018

AbstractA recent development for programming industrial robotic manipulators is the interactive teaching of task motions where a human operator physically guides the end‐effector of a robot. Admittance control schemes are used to this end. Since the operator is in direct contact with the robot, it must be ensured that the velocities of the robot are within a safe range at any time. Thus, in order to guarantee safe operation, position and velocity limits must be respected within the admittance control. Existing admittance control schemes can either take task space limits or joint space limits into account. In this paper an extended admittance control scheme is presented which is capable of simultaneously taking task space limits as well as joint space limits into account. This is achieved by formulating the admittance control law in terms of a path parameter to account for task space limits and a subsequent determination of the path parameter dynamics with respect to the joint space limits. Admittance control requires an estimation of the interaction wrench to be available. Three different methods for obtaining such an estimation are presented: 1) A six‐axis force/torque sensor mounted on the robot end‐effector, 2) The generalized momentum, 3) A decoupled mechanical model of the motors. The performance of the algorithms is demonstrated by means of experimental results.