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Multiscale Modeling of ElastoPlasticity in Heterogeneous Geomaterials Based on Continuum Micromechanics arXiv.cs.CE Pub Date : 20201124
Mahdad Eghbalian; Mehdi Pouragha; Richard WanIn this paper, we investigate some micromechanical aspects of elastoplasticity in heterogeneous geomaterials. The aim is to upscale the elastoplastic behavior for a representative volume of the material which is indeed a very challenging task due to the irreversible deformations involved. Considering the plastic strains as eigenstrains allows us to employ the powerful tools offered by Continuum

Blade Envelopes Part I: Concept and Methodology arXiv.cs.CE Pub Date : 20201122
Chun Yui Wong; Pranay Seshadri; Ashley Scillitoe; Andrew Duncan; Geoffrey ParksBlades manufactured through flank and point milling will likely exhibit geometric variability. Gauging the aerodynamic repercussions of such variability, prior to manufacturing a component, is challenging enough, let alone trying to predict what the amplified impact of any inservice degradation will be. While rules of thumb that govern the tolerance band can be devised based on expected boundary layer

Reduced order methods for parametric flow control problems and applications arXiv.cs.CE Pub Date : 20201124
Francesco Ballarin; Gianluigi Rozza; Maria StrazzulloIn this contribution we propose reduced order methods to fast and reliably solve parametrized optimal control problems governed by time dependent nonlinear partial differential equations. Our goal is to provide a general tool to deal with the time evolution of several nonlinear optimality systems in manyquery context, where a system must be analysed for various physical and geometrical features. Optimal

Model Order Reduction for Gas and Energy Networks arXiv.cs.CE Pub Date : 20201124
Christian Himpe; Sara Grundel; Peter BennerTo counter the volatile nature of renewable energy sources, gas networks take a vital role. But, to ensure fulfillment of contracts under these new circumstances, a vast number of possible scenarios, incorporating uncertain supply and demand, has to be simulated ahead of time. This manyquery task can be accelerated by model order reduction, yet, largescale, nonlinear, parametric, hyperbolic partial

An elastic framework for ensemblebased largescale data assimilation arXiv.cs.CE Pub Date : 20201121
Sebastian Friedemann; Bruno RaffinPrediction of chaotic systems relies on a floating fusion of sensor data (observations) with a numerical model to decide on a good system trajectory and to compensate nonlinear feedback effects. Ensemblebased data assimilation (DA) is a major method for this concern depending on propagating an ensemble of perturbed model realizations.In this paper we develop an elastic, online, faulttolerant and

A phase field formulation for dissolutiondriven stress corrosion cracking arXiv.cs.CE Pub Date : 20201124
Chuanjie Cui; Rujin Ma; Emilio MartínezPañedaWe present a new theoretical and numerical framework for modelling mechanicallyassisted corrosion in elasticplastic solids. Both pitting and stress corrosion cracking (SCC) can be captured, as well as the pittocrack transition. Localised corrosion is assumed to be dissolutiondriven and a formulation grounded upon the film rupturedissolutionrepassivation mechanism is presented to incorporate

Simulating an ObjectOriented Financial System in a Functional Language arXiv.cs.CE Pub Date : 20201123
Christopher Clack; Lee Braine; Keith Haviland; Owen SmithJaynes; Andy VautierThis paper summarises a successful application of functional programming within a commercial environment. We report on experience at Accenture's Financial Services Solution Centre in London with simulating an objectoriented financial system in order to assist analysis and design. The work was part of a large IT project for an international investment bank and provides a pragmatic case study.

A Geometrically Exact Continuum Framework for LightMatter Interaction in PhotoActive Polymers I. Variational Setting arXiv.cs.CE Pub Date : 20201123
M Mehnert; W Oates; P SteinmannMolecular photoswitches as, e.g., azobenzene molecules allow, when embedded into a polymeric matrix, for photoactive polymer compounds responding mechanically when exposed to light of certain wavelength. Photomechanics, i.e. lightmatter interaction in photoactive polymers holds great promise for, e.g., remote and contactfree activation of photodriven actuators. In a series of earlier contributions

Imperfect Oracles: The Effect of Strategic Information on Stock Markets arXiv.cs.CE Pub Date : 20201121
Miklos BorsiUniversity of BristolModern financial market dynamics warrant detailed analysis due to their significant impact on the world. This, however, often proves intractable; massive numbers of agents, strategies and their change over time in reaction to each other leads to difficulties in both theoretical and simulational approaches. Notable work has been done on strategy dominance in stock markets with respect to the ratios

An automaticadaptivity stabilized finite element method via residual minimization for heterogeneous, anisotropic advectiondiffusionreaction problems arXiv.cs.CE Pub Date : 20201123
Roberto J. Cier; Sergio Rojas; Victor M. CaloIn this paper, we describe a stable finite element formulation for advectiondiffusionreaction problems that allows for robust automatic adaptive strategies to be easily implemented. We consider locally vanishing, heterogeneous, and anisotropic diffusivities, as well as advectiondominated diffusion problems. The general stabilized finite element framework was described and analyzed in arXiv:1907

On the implementation of largescale integral operators with modern HPC solutions  Application to 3D Marchenko imaging by leastsquares inversion arXiv.cs.CE Pub Date : 20201122
Matteo Ravasi; Ivan VasconcelosNumerical integral operators of convolution type form the basis of most waveequationbased methods for processing and imaging of seismic data. As several of these methods require the solution of an inverse problem, multiple forward and adjoint passes of the modelling operator must be performed to converge to a satisfactory solution. This work highlights the challenges that arise when implementing

A modified bond model for describing isotropic linear elastic material behaviour with the particle method arXiv.cs.CE Pub Date : 20201120
Rahav Gowtham Venkateswaran; Ursula Kowalsky; Dieter DinklerParticle based methods such as the Discrete Element Method and the Lattice Spring Method may be used for describing the behaviour of isotropic linear elastic materials. However, the common bond models employed to describe the interaction between particles restrict the range of Poisson's ratio that can be represented. In this paper, to overcome the restriction, a modified bond model that includes the

Sequential Defaulting in Financial Networks arXiv.cs.CE Pub Date : 20201120
Pál András Papp; Roger WattenhoferWe consider financial networks, where banks are connected by contracts such as debts or credit default swaps. We study the clearing problem in these systems: we want to know which banks end up in a default, and what portion of their liabilities can these defaulting banks fulfill. We analyze these networks in a sequential model where banks announce their default one at a time, and the system evolves

PIFEPIC: Parallel ImmersedFiniteElement ParticleInCell For 3D Kinetic Simulations of PlasmaMaterial Interactions arXiv.cs.CE Pub Date : 20201120
Daoru Han; Xiaoming He; David Lund; Xu ZhangThis paper presents a recently developed particle simulation code package PIFEPIC, which is a novel threedimensional (3D) Parallel ImmersedFiniteElement (IFE) ParticleinCell (PIC) simulation model for particle simulations of plasmamaterial interactions. This framework is based on the recently developed nonhomogeneous electrostatic IFEPIC algorithm, which is designed to handle complex plasmamaterial

Data Driven Modeling of Interfacial Traction Separation Relations using Thermodynamic Consistent Neural Network (TCNN) arXiv.cs.CE Pub Date : 20201117
Congjie Wei; Jiaxin Zhang; Kenneth M. Liechti; Chenglin WuFor multilayer structures in thin substrate systems, the interfacial failure is one of the most important reliability issues. The tractionseparation relations (TSR) along fracture interface, which is often a complicated mixedmode problem, is usually adopted as a representative of the adhesive interactions of a biomaterial system. However, the existing theoretical models lack complexity and are not

Continuous calibration of a digital twin: comparison of particle filter and Bayesian calibration approaches arXiv.cs.CE Pub Date : 20201119
Rebecca Ward; Ruchi Choudhary; Alastair Gregory; Mark GirolamiAssimilation of continuously streamed monitored data is an essential component of a digital twin; the assimilated data are used to ensure the digital twin is a true representation of the monitored system. One way this is achieved is by calibration of simulation models, whether dataderived or physicsbased, or a combination of both. Traditional manual calibration is not possible in this context hence

Using simulation to incorporate dynamic criteria into multiple criteria decisionmaking arXiv.cs.CE Pub Date : 20201116
Uwe Aickelin; Jenna Marie Reps; PeerOlaf Siebers; Peng LiIn this paper, we present a case study demonstrating how dynamic and uncertain criteria can be incorporated into a multicriteria analysis with the help of discrete event simulation. The simulation guided multicriteria analysis can include both monetary and nonmonetary criteria that are static or dynamic, whereas standard multi criteria analysis only deals with static criteria and cost benefit analysis

Falling balls in a viscous fluid with contact: Comparing numerical simulations with experimental data arXiv.cs.CE Pub Date : 20201117
Henry von Wahl; Thomas Richter; Stefan Frei; Thomas HagemeierWe evaluate a number of different finite element approaches for fluidstructure (contact) interaction problems against data from physical experiments. For this we take the data from experiments by Hagemeier [Mendeley Data, doi: 10.17632/mf27c92nc3.1]. This consists of trajectories of single particles falling through a highly viscous fluid and rebounding off the bottom fluid tank wall. The resulting

A universal predictorcorrector type incremental algorithm for the construction of weighted straight skeletons based on the notion of deforming polygon arXiv.cs.CE Pub Date : 20201113
Baris IrhanA new predictorcorrector type incremental algorithm is proposed for the exact construction of weighted straight skeletons of 2D general planar polygons of arbitrary complexity based on the notion of deforming polygon. In the proposed algorithm, the raw input provided by the polygon itself is enough to resolve edge collapse and edge split events. Neither the construction of a kinetic triangulation

A Novel Numerical Method for Modeling Anisotropy in Discretized BondBased Peridynamics arXiv.cs.CE Pub Date : 20201116
Naveen PrakashThis work proposes a novel, general and robust method of determining bond micromoduli for anisotropic linear elastic bondbased peridynamics. The problem of finding a discrete distribution of bond micromoduli that reproduces an anisotropic peridynamic stiffness tensor is cast as a leastsquares problem. The proposed numerical method is able to find a distribution of bond micromoduli that is able to

Robust and Efficient MultilevelILU Preconditioned NewtonGMRES for Incompressible NavierStokes arXiv.cs.CE Pub Date : 20201114
Qiao Chen; Xiangmin JiaoWe introduce a new preconditioned NewtonGMRES method for solving the nonlinear systems arising from incompressible NavierStokes equations. When the Reynolds number is relatively high, these systems often involve millions of degrees of freedom (DOFs), and the nonlinear systems are difficult to converge, partially due to their saddlepoint structure. In this work, we propose to alleviate these issues

Discovery of the Hidden State in Ionic Models Using a DomainSpecific Recurrent Neural Network arXiv.cs.CE Pub Date : 20201114
Shahriar IravanianIonic models, the set of ordinary differential equations (ODEs) describing the time evolution of the state of excitable cells, are the cornerstone of modeling in neuro and cardiac electrophysiology. Modern ionic models can have tens of state variables and hundreds of tunable parameters. Fitting ionic models to experimental data, which usually covers only a limited subset of state variables, remains

Applications of phase field fracture in modelling hydrogen assisted failures arXiv.cs.CE Pub Date : 20201114
P. K. Kristensen; C. F. Niordson; E. MartínezPañedaThe phase field fracture method has emerged as a promising computational tool for modelling a variety of problems including, since recently, hydrogen embrittlement and stress corrosion cracking. In this work, we demonstrate the potential of phase fieldbased multiphysics models in transforming the engineering assessment and design of structural components in hydrogencontaining environments. First

Identifying and tracking bubbles and drops in simulations: a toolbox for obtaining sizes, lineages, and breakup and coalescence statistics arXiv.cs.CE Pub Date : 20201114
Wai Hong Ronald Chan; Michael S. Dodd; Perry L. Johnson; Parviz MoinKnowledge of bubble and drop size distributions in twophase flows is important for characterizing a wide range of phenomena, including combustor ignition, sonar communication, and cloud formation. The physical mechanisms driving the background flow also drive the time evolution of these distributions. Accurate and robust identification and tracking algorithms for the dispersed phase are necessary

BESS Optimal Sizing Methodology Degree of Impact of Several Influencing Factors arXiv.cs.CE Pub Date : 20201113
Benoît RichardDTS; Xavier Le PivertCEP; YvesMarie BourienBattery Energy Storage Systems (BESS) are more and more competitive due to their increasing performances and decreasing costs. Although certain battery storage technologies may be mature and reliable from a technological perspective, with further cost reductions expected, the economic concern of battery systems is still a major barrier to be overcome before BESS can be fully utilized as a mainstream

Stress Testing Method for Scenario Based Testing of Automated Driving Systems arXiv.cs.CE Pub Date : 20201112
Demin Nalic; Hexuan Li; Arno Eichberger; Christoph Wellershaus; Aleksa Pandurevic; Branko RogicClassical approaches and procedures for testing of automated vehicles of SAE levels 1 and 2 were based on defined scenarios with specific maneuvers, depending on the function under test. For automated driving systems (ADS) of SAE level 3+, the scenario space is infinite and calling for virtual testing and verification. However, even in simulation, the generation of safetyrelevant scenarios for ADS

A novel hydraulic fractures growth formulation arXiv.cs.CE Pub Date : 20201030
Francesca Fantoni; Alberto SalvadoriPropagation of a fluiddriven crack in an impermeable linear elastic medium under axissymmetric conditions is investigated in the present work. The fluid exerting the pressure inside the crack is an incompressible Newtonian one and its front is allowed to lag behind the propagating fracture tip. The tip cavity is considered as filled by fluid vapors under constant pressure having a negligible value

RealWorld Anomaly Detection by using Digital Twin Systems and WeaklySupervised Learning arXiv.cs.CE Pub Date : 20201112
Andrea Castellani; Sebastian Schmitt; Stefano SquartiniThe continuously growing amount of monitored data in the Industry 4.0 context requires strong and reliable anomaly detection techniques. The advancement of Digital Twin technologies allows for realistic simulations of complex machinery, therefore, it is ideally suited to generate synthetic datasets for the use in anomaly detection approaches when compared to actual measurement data. In this paper,

Inexact Methods for Sequential Fully Implicit (SFI) Reservoir Simulation arXiv.cs.CE Pub Date : 20201109
Jiamin Jiang; Pavel Tomin; Yifan ZhouThe sequential fully implicit (SFI) scheme was introduced (Jenny et al. 2006) for solving coupled flow and transport problems. Each time step for SFI consists of an outer loop, in which there are inner Newton loops to implicitly and sequentially solve the pressure and transport subproblems. In standard SFI, the subproblems are usually solved with tight tolerances at every outer iteration. This can

An application of an Embedded Model Estimator to a synthetic nonstationary reservoir model with multiple secondary variables arXiv.cs.CE Pub Date : 20201109
Colin DalyA method (Ember) for nonstationary spatial modelling with multiple secondary variables by combining Geostatistics with Random Forests is applied to a threedimensional Reservoir Model. It extends the Random Forest method to an interpolation algorithm retaining similar consistency properties to both Geostatistical algorithms and Random Forests. It allows embedding of simpler interpolation algorithms

Lattice meets lattice: Application of lattice cubature to models in lattice gauge theory arXiv.cs.CE Pub Date : 20201110
Tobias Hartung; Karl Jansen; Frances Y. Kuo; Hernan Leövey; Dirk Nuyens; Ian H. SloanHigh dimensional integrals are abundant in many fields of research including quantum physics. The aim of this paper is to develop efficient recursive strategies to tackle a class of high dimensional integrals having a special product structure with low order couplings, motivated by models in lattice gauge theory from quantum field theory. A novel element of this work is the potential benefit in using

Nonlinear Iterative Projection Methods with Multigrid in Photon Frequency for Thermal Radiative Transfer arXiv.cs.CE Pub Date : 20201110
Dmitriy Y. AnistratovThis paper presents nonlinear iterative methods for the fundamental thermal radiative transfer (TRT) model defined by the timedependent multifrequency radiative transfer (RT) equation and the material energy balance (MEB) equation. The iterative methods are based on the nonlinear projection approach and use multiple grids in photon frequency. They are formulated by the highorder RT equation on a

Interaction of void spacing and material size effect on intervoid flow localisation arXiv.cs.CE Pub Date : 20201110
I. Holte; A. Srivastava; E. MartínezPañeda; C. F. Niordson; K. L. NielsenThe ductile fracture process in porous metals due to growth and coalescence of micron scale voids is not only affected by the imposed stress state but also by the distribution of the voids and the material size effect. The objective of this work is to understand the interaction of the intervoid spacing (or ligaments) and the resultant gradient induced material size effect on void coalescence for a

NonEquilibrium Skewness, Market Crises, and Option Pricing: NonLinear Langevin Model of Markets with Supersymmetry arXiv.cs.CE Pub Date : 20201103
Igor HalperinThis paper presents a tractable model of nonlinear dynamics of market returns using a Langevin approach.Due to nonlinearity of an interaction potential, the model admits regimes of both small and large return fluctuations. Langevin dynamics are mapped onto an equivalent quantum mechanical (QM) system. Borrowing ideas from supersymmetric quantum mechanics (SUSY QM), we use a parameterized ground state

A dual adaptive explicit time integration algorithm for efficiently solving the cardiac monodomain equation arXiv.cs.CE Pub Date : 20201109
Konstantinos A Mountris; Esther PueyoThe monodomain model is widely used in insilico cardiology to describe excitation propagation in the myocardium. Frequently, operator splitting is used to decouple the stiff reaction term and the diffusion term in the monodomain model so that they can be solved separately. Commonly, the diffusion term is solved implicitly with a large time step while the reaction term is solved by using an explicit

Exploring market power using deep reinforcement learning for intelligent bidding strategies arXiv.cs.CE Pub Date : 20201108
Alexander J. M. Kell; Matthew Forshaw; A. Stephen McGoughDecentralized electricity markets are often dominated by a small set of generator companies who control the majority of the capacity. In this paper, we explore the effect of the total controlled electricity capacity by a single, or group, of generator companies can have on the average electricity price. We demonstrate this through the use of ElecSim, a simulation of a countrywide energy market. We

Multiscale ReducedOrder Modeling of a Titanium Skin Panel Subjected to ThermoMechanical Loading arXiv.cs.CE Pub Date : 20201108
Xiang Zhang; Yang Liu; Caglar OskayThis manuscript presents the formulation, implementation, calibration and application of a multiscale reducedorder model to simulate a titanium panel structure subjected to thermomechanical loading associated with highspeed flight. The formulation is based on the eigenstrainbased reducedorder homogenization model (EHM) and further considers thermal strain as well as temperature dependent material

Magnetic Field Simulations Using Explicit Time Integration With Higher Order Schemes arXiv.cs.CE Pub Date : 20201105
Bernhard Kähne; Markus Clemens; Sebastian SchöpsA transient magnetoquasistatic vector potential formulation involving nonlinear material is spatially discretized using the finite element method of first and second polynomial order. By applying a generalized Schur complement the resulting system of differential algebraic equations is reformulated into a system of ordinary differential equations (ODE). The ODE system is integrated in time using the

A DataDriven Machine Learning Approach for Consumer Modeling with Load Disaggregation arXiv.cs.CE Pub Date : 20201104
A. Khaled Zarabie; Sanjoy Das; Hongyu WuWhile nonparametric models, such as neural networks, are sufficient in the load forecasting, separate estimates of fixed and shiftable loads are beneficial to a wide range of applications such as distribution system operational planning, load scheduling, energy trading, and utility demand response programs. A semiparametric estimation model is usually required, where cost sensitivities of demands

Applying a Chebyshev collocation method based on domain decomposition for calculating underwater sound propagation in a horizontally stratified environment arXiv.cs.CE Pub Date : 20201105
Houwang Tu; Yongxian Wang; Qiang Lan; Wei Liu; Wenbin Xiao; Shuqing MaThe propagation of sound waves in a horizontally stratified environment, a classical problem in ocean acoustics, has traditionally been calculated using normal modes. Most programs based on the normal mode model are discretized using the finite difference method (FDM). This paper proposes a Chebyshev collocation method (CCM) based on domain decomposition to solve this problem. A set of collocation

A MultiStage Adaptive Sampling Scheme for Passivity Characterization of LargeScale Macromodels arXiv.cs.CE Pub Date : 20201105
Marco De Stefano; Stefano GrivetTalocia; Torben Wendt; Cheng Yang; Christian SchusterThis paper proposes a hierarchical adaptive sampling scheme for passivity characterization of largescale linear lumped macromodels. Here, largescale is intended both in terms of dynamic order and especially number of input/output ports. Standard passivity characterization approaches based on spectral properties of associated Hamiltonian matrices are either inefficient or nonapplicable for largescale

Accelerating numerical methods for nonlinear acoustics using nested meshes arXiv.cs.CE Pub Date : 20201105
Samuel P. Groth; Pierre Gelat; Seyyed R. Haqshenas; Nader Saffari; Elwin van't Wout; Timo Betcke; Garth N. WellsThe numerical simulation of nonlinear ultrasound is important in the treatment planning for highintensity focused ultrasound (HIFU) therapies in the abdomen. However, the large domain sizes and generation of higher harmonics at the focus make these problems extremely computationally demanding. Numerical methods typically employ a uniform mesh fine enough the resolve the highest harmonic present in

Fast Solver for QuasiPeriodic 2DHelmholtz Scattering in Layered Media arXiv.cs.CE Pub Date : 20201105
José Pinto; Rubén Aylwin; Carlos JerezHanckesWe present a fast spectral Galerkin scheme for the discretization of boundary integral equations arising from twodimensional Helmholtz transmission problems in multilayered periodic structures or gratings. Employing suitably parametrized Fourier basis and excluding RayleighWood anomalies, we rigorously establish the wellposedness of both continuous and discrete problems, and prove superalgebraic

Essential Scattering Applications for Everyone. Overview arXiv.cs.CE Pub Date : 20201028
Denis Korolkov; Stepan RakhimovESCAPE is a free python package and framework for creating applications for simulating and fitting of Xray and neutron scattering data with current support for specular reflectivity, polarized neutron reflectometry, high resolution Xray diffraction, small angle scattering with future support for offspecular scattering from structured samples with complicated morphology. Dedicated to professionals

Phase field predictions of microscopic fracture and Rcurve behaviour of fibrereinforced composites arXiv.cs.CE Pub Date : 20201102
Wei Tan; Emilio MartínezPañedaWe present a computational framework to explore the effect of microstructure and constituent properties upon the fracture toughness of fibrereinforced polymer composites. To capture microscopic matrix cracking and fibrematrix debonding, the framework couples the phase field fracture method and a cohesive zone model in the context of the finite element method. Virtual singlenotched three point bending

A multiscale model of terrain dynamics for realtime earthmoving simulation arXiv.cs.CE Pub Date : 20201101
Martin Servin; Tomas Berglund; Samuel NystedtA multiscale model for realtime simulation of terrain dynamics is explored. To represent the dynamics on different scales the model combines the description of soil as a continuous solid, as distinct particles and as rigid multibodies. The models are dynamically coupled to each other and to the earthmoving equipment. Agitated soil is represented by a hybrid of contacting particles and continuum solid

Handling Missing Data with Graph Representation Learning arXiv.cs.CE Pub Date : 20201030
Jiaxuan You; Xiaobai Ma; Daisy Yi Ding; Mykel Kochenderfer; Jure LeskovecMachine learning with missing data has been approached in two different ways, including feature imputation where missing feature values are estimated based on observed values, and label prediction where downstream labels are learned directly from incomplete data. However, existing imputation models tend to have strong prior assumptions and cannot learn from downstream tasks, while models targeting

Spacetime shape uncertainties in the forward and inverse problem of electrocardiography arXiv.cs.CE Pub Date : 20201030
Lia Gander; Rolf Krause; Michael Multerer; Simone PezzutoIn electrocardiography, the "classic" inverse problem consists of finding electric potentials on a surface enclosing the heart from remote recordings on the body surface and an accurate description of the anatomy. The latter being affected by noise and obtained with limited resolution due to clinical constraints, a possibly large uncertainty may be perpetuated in the inverse reconstruction. The purpose

Manifold learningbased feature extraction for structural defect reconstruction arXiv.cs.CE Pub Date : 20201026
Qi Li; Dianzi Liu; Zhenghua QianDatadriven quantitative defect reconstructions using ultrasonic guided waves has recently demonstrated great potential in the area of nondestructive testing. In this paper, we develop an efficient deep learningbased defect reconstruction framework, called NetInv, which recasts the inverse guided wave scattering problem as a datadriven supervised learning progress that realizes a mapping between

Physicsinformed deep learning for flow and deformation in poroelastic media arXiv.cs.CE Pub Date : 20201029
Yared W. BekeleA physicsinformed neural network is presented for poroelastic problems with coupled flow and deformation processes. The governing equilibrium and mass balance equations are discussed and specific derivations for twodimensional cases are presented. A fullyconnected deep neural network is used for training. Barry and Mercer's source problem with timedependent fluid injection/extraction in an idealized

Shape error modelling and simulation of 3D freeform surfaces during early design stage by morphing Gaussian Random Fields arXiv.cs.CE Pub Date : 20201028
Manoj Babu; Pasquale Franciosa; Darek Ceglarek3D freeform surfaces with high aesthetical and functional requirements are widely used in automotive and aerospace industry. Geometric and dimensional variations of these freeform surfaces caused by inevitable uncertainties in the manufacturing process often leads to product quality issues. Failing to model the effect of nonideal parts, i.e., parts with geometric and dimensional errors, during design

Internal contact modeling for finite strain topology optimization arXiv.cs.CE Pub Date : 20201027
Gore Lukas Bluhm; Ole Sigmund; Konstantinos PouliosThe present work proposes an extension of the third medium contact method for solving structural topology optimization problems that involve and exploit selfcontact. A new regularization of the void region, which acts as the contact medium, makes the method suitable for cases with very large deformations. The proposed contact method is implemented in a second order topology optimization framework

Impossibility of phylogeny reconstruction from $k$mer counts arXiv.cs.CE Pub Date : 20201027
WaiTong Louis Fan; Brandon Legried; Sebastien RochWe consider phylogeny estimation under a twostate model of sequence evolution by site substitution on a tree. In the asymptotic regime where the sequence lengths tend to infinity, we show that for any fixed $k$ no statistically consistent phylogeny estimation is possible from $k$mer counts of the leaf sequences alone. Formally, we establish that the joint leaf distributions of $k$mer counts on two

An isogeometric finite element formulation for geometrically exact Timoshenko beams with extensible directors arXiv.cs.CE Pub Date : 20201027
MyungJin Choi; Roger A. Sauer; Sven KlinkelAn isogeometric finite element formulation for geometrically and materially nonlinear Timoshenko beams is presented, which incorporates inplane deformation of the crosssection described by two extensible director vectors. Since those directors belong to the space ${\Bbb R}^3$, a configuration can be additively updated. The developed formulation allows direct application of nonlinear threedimensional

Scientific intuition inspired by machine learning generated hypotheses arXiv.cs.CE Pub Date : 20201027
Pascal Friederich; Mario Krenn; Isaac Tamblyn; Alan AspuruGuzikMachine learning with application to questions in the physical sciences has become a widely used tool, successfully applied to classification, regression and optimization tasks in many areas. Research focus mostly lies in improving the accuracy of the machine learning models in numerical predictions, while scientific understanding is still almost exclusively generated by human researchers analysing

A higherorder finite element method with unstructured anisotropic mesh adaption for two phase flows with surface tension arXiv.cs.CE Pub Date : 20201026
Modesar Shakoor; Chung Hae ParkA novel finite element framework is proposed for the numerical simulation of two phase flows with surface tension. The LevelSet (LS) method with piecewise quadratic (P2) interpolation for the liquidgas interface is used in order to reach higherorder convergence rates in regions with smooth interface. A balancedforce implementation of the continuum surface force model is used to take into account

Highorder maximumentropy collocation methods arXiv.cs.CE Pub Date : 20201026
F. Greco; M. ArroyoThis paper considers the approximation of partial differential equations with a point collocation framework based on highorder local maximumentropy schemes (HOLMES). In this approach, smooth basis functions are computed through an optimization procedure and the strong form of the problem is directly imposed at the collocation points, reducing significantly the computational times with respect to

Textbook efficiency: massively parallel matrixfree multigrid for the Stokes system arXiv.cs.CE Pub Date : 20201026
Nils Kohl; Ulrich RüdeWe employ textbook multigrid efficiency (TME), as introduced by Achi Brandt, to construct an asymptotically optimal monolithic multigrid solver for the Stokes system. The geometric multigrid solver builds upon the concept of hierarchical hybrid grids (HHG), which is extended to higherorder finiteelement discretizations, and a corresponding matrixfree implementation. The computational cost of the

Unsupervised discovery of interpretable hyperelastic constitutive laws arXiv.cs.CE Pub Date : 20201026
Moritz Flaschel; Siddhant Kumar; Laura De LorenzisWe propose a new approach for datadriven automated discovery of hyperelastic constitutive laws. The approach is unsupervised, i.e., it requires no stress data but only displacement and global force data, which are realistically available through mechanical testing and digital image correlation techniques; it delivers interpretable models, i.e., models that are embodied by parsimonious mathematical

Towards RealTime Magnetic Dosimetry Simulations for Inductive Charging Systems arXiv.cs.CE Pub Date : 20201024
Norman Haussmann; Martin Zang; Robin Mease; Markus Clemens; Benedikt Schmuelling; Matthias BoltenThe exposure of a human by magnetoquasistatic fields from wireless charging systems is to be determined from magnetic field measurements in near realtime. This requires a fast linear equations solver for the discrete Poisson system of the CoSimulation Scalar Potential Finite Difference (CoSim. SPFD) scheme. Here, the use of the AmgX library on NVIDIA GPUs is presented for this task. It enables