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An Advection-Diffusion based Filter for Machinable Designs in Topology Optimization arXiv.cs.CE Pub Date : 2021-02-25 Lukas Christian Høghøj; Erik Albert Träff
This paper introduces a simple formulation for topology optimization problems ensuring manufacturability by machining. The method distinguishes itself from existing methods by using the advection-diffusion equation with Robin boundary conditions to perform a filtering of the design variables. The proposed approach is less computationally expensive than the traditional methods used. Furthermore, the
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Machine Learning-Based Optimal Mesh Generation in Computational Fluid Dynamics arXiv.cs.CE Pub Date : 2021-02-25 Keefe Huang; Moritz Krügener; Alistair Brown; Friedrich Menhorn; Hans-Joachim Bungartz; Dirk Hartmann
Computational Fluid Dynamics (CFD) is a major sub-field of engineering. Corresponding flow simulations are typically characterized by heavy computational resource requirements. Often, very fine and complex meshes are required to resolve physical effects in an appropriate manner. Since all CFD algorithms scale at least linearly with the size of the underlying mesh discretization, finding an optimal
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Quantitative in vivo imaging to enable tumor forecasting and treatment optimization arXiv.cs.CE Pub Date : 2021-02-24 Guillermo Lorenzo; David A. Hormuth II; Angela M. Jarrett; Ernesto A. B. F. Lima; Shashank Subramanian; George Biros; J. Tinsley Oden; Thomas J. R. Hughes; Thomas E. Yankeelov
Current clinical decision-making in oncology relies on averages of large patient populations to both assess tumor status and treatment outcomes. However, cancers exhibit an inherent evolving heterogeneity that requires an individual approach based on rigorous and precise predictions of cancer growth and treatment response. To this end, we advocate the use of quantitative in vivo imaging data to calibrate
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Inferring temporal dynamics from cross-sectional data using Langevin dynamics arXiv.cs.CE Pub Date : 2021-02-23 Pritha Dutta; Rick Quax; Loes Crielaard; Peter M. A. Sloot
Cross-sectional studies are widely prevalent since they are more feasible to conduct compared to longitudinal studies. However, cross-sectional data lack the temporal information required to study the evolution of the underlying processes. Nevertheless, this is essential to develop predictive computational models which is the first step towards causal modelling. We propose a method for inferring computational
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Twelve Ways To Fool The Masses When Giving Parallel-In-Time Results arXiv.cs.CE Pub Date : 2021-02-23 Sebastian Goetschel; Michael Minion; Daniel Ruprecht; Robert Speck
Getting good speedup -- let alone high parallel efficiency -- for parallel-in-time (PinT) integration examples can be frustratingly difficult. The high complexity and large number of parameters in PinT methods can easily (and unintentionally) lead to numerical experiments that overestimate the algorithm's performance. In the tradition of Bailey's article "Twelve ways to fool the masses when giving
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Remote Renewable Hubs For Carbon-Neutral Synthetic Fuel Production arXiv.cs.CE Pub Date : 2021-02-22 Mathias Berger; David Radu; Ghislain Detienne; Thierry Deschuyteneer; Aurore Richel; Damien Ernst
This paper studies the economics of carbon-neutral synthetic fuel production from renewable electricity in remote areas where high-quality renewable resources are abundant. To this end, a graph-based optimisation modelling framework directly applicable to the strategic planning of remote renewable energy supply chains is proposed. More precisely, a graph abstraction of planning problems is introduced
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Phase-field modeling on the diffusion-driven processes in metallic conductors and lithium-ion batteries arXiv.cs.CE Pub Date : 2021-02-20 Jay Santoki
Diffusion-driven processes are important phenomena of materials science in the field of energy conversion and transmission. During the conversion from chemical energy to electrical energy, the species diffusion is generally linked to the rate of exchange, and hence to the performance of the conversion device. Alternatively, the transmission of the electric field diffuses the species when it passes
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Spectral formulation of the boundary integral equation method for antiplane problems arXiv.cs.CE Pub Date : 2021-02-16 Kunnath Ranjith
A spectral formulation of the boundary integral equation method for antiplane problems is presented. The boundary integral equation method relates the displacement discontinuity and the shear stress at an interface between two half-planes. It involves evaluating a space-time convolution of the shear stress or the displacement discontinuity at the interface. In the spectral formulation, the convolution
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Computational modeling of degradation process of biodegradable magnesium biomaterials arXiv.cs.CE Pub Date : 2021-02-19 Mojtaba Barzegari; Di Mei; Sviatlana V. Lamaka; Liesbet Geris
Despite the advantages of using biodegradable metals in implant design, their uncontrolled degradation and release remain a challenge in practical applications. A validated computational model of the degradation process can facilitate the tuning of implant biodegradation by changing design properties. In this study, a physicochemical model was developed by deriving a mathematical description of the
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Uncertainty Quantification for the 12-lead ECG: a Lead Field Approach arXiv.cs.CE Pub Date : 2021-02-19 Michael Multerer; Simone Pezzuto
The standard electrocardiogram (ECG) is a point-wise evaluation of the body potential at certain given locations. These locations are subject to uncertainty and may vary from patient to patient or even for a single patient. In this work, we estimate the uncertainty in the ECG induced by uncertain electrode positions when the ECG is derived from the bidomain model. In order to avoid the high computational
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Numerical study of COVID-19 spatial-temporal spreading in London arXiv.cs.CE Pub Date : 2021-02-19 J. Zheng; X. Wu; F. Fang; J. Li; Z. Wang; H. Xiao; J. Zhu; C. C. Pain; P. F. Linden; B. Xiang
Recent study reported that an aerosolised virus (COVID-19) can survive in the air for a few hours. It is highly possible that people get infected with the disease by breathing and contact with items contaminated by the aerosolised virus. However, the aerosolised virus transmission and trajectories in various meteorological environments remain unclear. This paper has investigated the movement of aerosolised
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Analysis of Growing Tumor on the Flow Velocity of Cerebrospinal Fluid in Human Brain Using Computational Modeling and Fluid-Structure Interaction arXiv.cs.CE Pub Date : 2021-02-19 Muhammad Uzair-Ul-Haq; Ali Ahmed; Zartasha Mustansar; Arslan Shaukat; Lee Margetts; Asim Waris; Faizan Nadeem
Cerebrospinal fluid (CSF) plays a pivotal role in normal functioning of Brain. Intracranial compartments such as blood, brain and CSF are incompressible in nature. Therefore, if a volume imbalance in one of the aforenoted compartments is observed, the other reaches out to maintain net change to zero. Whereas, CSF has higher compliance over long term. However, if the CSF flow is obstructed in the ventricles
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A matrix approach to detect temporal behavioral patterns at electric vehicle charging stations arXiv.cs.CE Pub Date : 2021-02-18 Milan Straka; Lucia Piatriková; Peter van Bokhoven; Ľuboš Buzna
Based on the electric vehicle (EV) arrival times and the duration of EV connection to the charging station, we identify charging patterns and derive groups of charging stations with similar charging patterns applying two approaches. The ruled based approach derives the charging patterns by specifying a set of time intervals and a threshold value. In the second approach, we combine the modified l-p
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Efficient and robust numerical treatment of a gradient-enhanced damage model at large deformations arXiv.cs.CE Pub Date : 2021-02-17 Philipp Junker; Johannes Riesselmann; Daniel Balzani
The modeling of damage processes in materials constitutes an ill-posed mathematical problem which manifests in mesh-dependent finite element results. The loss of ellipticity of the discrete system of equations is counteracted by regularization schemes of which the gradient enhancement of the strain energy density is often used. In this contribution, we present an extension of the efficient numerical
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Semi-linear Poisson-mediated Flocking in a Cucker-Smale Model arXiv.cs.CE Pub Date : 2021-02-11 Christos N. Mavridis; Amoolya Tirumalai; John S. Baras; Ion Matei
We propose a family of compactly supported parametric interaction functions in the general Cucker-Smale flocking dynamics such that the mean-field macroscopic system of mass and momentum balance equations with non-local damping terms can be converted from a system of partial integro-differential equations to an augmented system of partial differential equations in a compact set. We treat the interaction
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Validation and parameter optimization of a hybrid embedded/homogenized solid tumor perfusion model arXiv.cs.CE Pub Date : 2021-02-17 Johannes Kremheller; Sebastian Brandstaeter; Bernhard A. Schrefler; Wolfgang A. Wall
The goal of this paper is to investigate the validity of a hybrid embedded/homogenized in-silico approach for modeling perfusion through solid tumors. The rationale behind this novel idea is that only the larger blood vessels have to be explicitly resolved while the smaller scales of the vasculature are homogenized. As opposed to typical discrete or fully-resolved 1D-3D models, the required data can
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A Bayesian Approach for Inferring Sea Ice Loads arXiv.cs.CE Pub Date : 2021-02-16 Matthew Parno; Taylor Hodgdon; Brendan West; Devin O'Connor; Arnold Song
The Earth's climate is rapidly changing and some of the most drastic changes can be seen in the Arctic, where sea ice extent has diminished considerably in recent years. As the Arctic climate continues to change, gathering in situ sea ice measurements is increasingly important for understanding the complex evolution of the Arctic ice pack. To date, observations of ice stresses in the Arctic have been
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Accelerated Simulations of Molecular Systems through Learning of their Effective Dynamics arXiv.cs.CE Pub Date : 2021-02-17 Pantelis R. Vlachas; Julija Zavadlav; Matej Praprotnik; Petros Koumoutsakos
Simulations are vital for understanding and predicting the evolution of complex molecular systems. However, despite advances in algorithms and special purpose hardware, accessing the timescales necessary to capture the structural evolution of bio-molecules remains a daunting task. In this work we present a novel framework to advance simulation timescales by up to three orders of magnitude, by learning
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A three-dimensional hybrid finite element -- spectral boundary integral method for modeling earthquakes in complex unbounded domains arXiv.cs.CE Pub Date : 2021-02-15 Gabriele Albertini; Ahmed Elbanna; David S. Kammer
We present a 3D hybrid method which combines the Finite Element Method (FEM) and the Spectral Boundary Integral method (SBIM) to model nonlinear problems in unbounded domains. The flexibility of FEM is used to model the complex, heterogeneous, and nonlinear part -- such as the dynamic rupture along a fault with near fault plasticity -- and the high accuracy and computational efficiency of SBIM is used
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Efficient solvers for shallow-water Saint-Venant equations and debris transportation-deposition models arXiv.cs.CE Pub Date : 2021-02-15 Florian De Vuyst
This research is aimed at achieving an efficient digital infrastructure for evaluating risks and damages caused by tsunami flooding. It is mainly focused on the suitable modeling of debris dynamics for a simple (but accurate enough) assessment of damages. For different reasons including computational performance and Big Data management issues, we focus our research on Eulerian debris flow modeling
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Multimodal Mobility Systems: Joint Optimization of Transit Network Design and Pricing arXiv.cs.CE Pub Date : 2021-02-15 Qi Luo; Samitha Samaranayake; Siddhartha Banerjee
The performance of multimodal mobility systems relies on the seamless integration of conventional mass transit services and the advent of Mobility-on-Demand (MoD) services. Prior work is limited to individually improving various transport networks' operations or linking a new mode to an existing system. In this work, we attempt to solve transit network design and pricing problems of multimodal mobility
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Material absorption-based carrier generation model for modeling optoelectronic devices arXiv.cs.CE Pub Date : 2021-02-12 Liang Chen; Hakan Bagci
The generation rate of photocarriers in optoelectronic materials is commonly calculated using the Poynting vector in the frequency domain. In time-domain approaches where the nonlinear coupling between electromagnetic (EM) waves and photocarriers can be accounted for, the Poynting vector model is no longer applicable. One main reason is that the photocurrent radiates low-frequency EM waves out of the
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Full waveform inversion using extended and simultaneous sources arXiv.cs.CE Pub Date : 2021-02-11 Sagi Buchatsky; Eran Treister
PDE-constrained optimization problems are often treated using the reduced formulation where the PDE constraints are eliminated. This approach is known to be more computationally feasible than other alternatives at large scales. However, the elimination of the constraints forces the optimization process to fulfill the constraints at all times. In some problems this may lead to a highly non-linear objective
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Development of a Fully-Coupled Harmonic Balance Method and a Refined Energy Method for the Computation of Flutter-Induced Limit Cycle Oscillations of Bladed Disks with Nonlinear Friction Contacts arXiv.cs.CE Pub Date : 2021-02-11 Christian Berthold; Johann Gross; Christian Frey; Malte Krack
Flutter stability is a dominant design constraint of modern gas and steam turbines. To further increase the feasible design space, flutter-tolerant designs are currently explored, which may undergo Limit Cycle Oscillations (LCOs) of acceptable, yet not vanishing, level. Bounded self-excited oscillations are a priori a nonlinear phenomenon, and can thus only be explained by nonlinear interactions such
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Brain Modelling as a Service: The Virtual Brain on EBRAINS arXiv.cs.CE Pub Date : 2021-02-11 Michael Schirner; Lia Domide; Dionysios Perdikis; Paul Triebkorn; Leon Stefanovski; Roopa Pai; Paula Popa; Bogdan Valean; Jessica Palmer; Chloê Langford; André Blickensdörfer; Michiel van der Vlag; Sandra Diaz-Pier; Alexander Peyser; Wouter Klijn; Dirk Pleiter; Anne Nahm; Oliver Schmid; Marmaduke Woodman; Lyuba Zehl; Jan Fousek; Spase Petkoski; Lionel Kusch; Meysam Hashemi; Daniele Marinazzo; Jean-François
The Virtual Brain (TVB) is now available as open-source cloud ecosystem on EBRAINS, a shared digital research platform for brain science. It offers services for constructing, simulating and analysing brain network models (BNMs) including the TVB network simulator; magnetic resonance imaging (MRI) processing pipelines to extract structural and functional connectomes; multiscale co-simulation of spiking
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A fast algorithm for solving a three-dimensional inverse multiple frequency problems of scalar acoustics in a cylindrical region arXiv.cs.CE Pub Date : 2021-02-11 Anatoly B. Bakushinsky; Alexander S. Leonov
A new algorithm for the stable solution of a three-dimensional scalar inverse problem of acoustic sounding of an inhomogeneous medium in a cylindrical region is proposed. The data of the problem is the complex amplitude of the wave field, measured outside the region of acoustic inhomogeneities in a cylindrical layer. Using the Fourier transform and Fourier series, the inverse problem is reduced to
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A positivity-preserving high-order weighted compact nonlinear scheme for compressible gas-liquid flows arXiv.cs.CE Pub Date : 2021-02-10 Man Long Wong; Jordan B. Angel; Michael F. Barad; Cetin C. Kiris
We present a robust, highly accurate, and efficient positivity- and boundedness-preserving diffuse interface method for the simulations of compressible gas-liquid two-phase flows with the five-equation model by Allaire et al. using high-order finite difference weighted compact nonlinear scheme (WCNS) in the explicit form. The equation of states of gas and liquid are given by the ideal gas and stiffened
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Structure-preserving Model Reduction of Parametric Power Networks arXiv.cs.CE Pub Date : 2021-02-09 Bita Safaee; Serkan Gugercin
We develop a structure-preserving parametric model reduction approach for linearized swing equations where parametrization corresponds to variations in operating conditions. We employ a global basis approach to develop the parametric reduced model in which we concatenate the local bases obtained via $\mathcal{H}_2$-based interpolatory model reduction. The residue of the underlying dynamics corresponding
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Simulating dense granular flow using the $μ$($I$)-rheology within a space-time framework arXiv.cs.CE Pub Date : 2021-02-09 Linda Gesenhues; Marek Behr
A space-time framework is applied to simulate dense granular flow. Two different numerical experiments are performed: a column collapse and a dam break on an inclined plane. The experiments are modeled as two-phase flows. The dense granular material is represented by a constitutive model, the $\mu$($I$)-rheology, that is based on the Coulomb's friction law, such that the normal stress applied by the
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A simple artificial damping method for total Lagrangian smoothed particle hydrodynamics arXiv.cs.CE Pub Date : 2021-02-05 Chi Zhang; Yujie Zhu; Yongchuan Yu; Massoud Rezavand; Xiangyu Hu
In this paper, we present a simple artificial damping method to enhance the robustness of total Lagrangian smoothed particle hydrodynamics (TL-SPH). Specifically, an artificial damping stress based on the Kelvin-Voigt type damper with a scaling factor imitating a von Neumann-Richtmyer type artificial viscosity is introduced in the constitutive equation to alleviate the spurious oscillation in the vicinity
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Bayesian Poroelastic Aquifer Characterization from InSAR Surface Deformation Data Part II: Quantifying the Uncertainty arXiv.cs.CE Pub Date : 2021-02-08 Amal Alghamdi; Marc Hesse; Jingyi Chen; Umberto Villa; Omar Ghattas
Uncertainty quantification of groundwater (GW) aquifer parameters is critical for efficient management and sustainable extraction of GW resources. These uncertainties are introduced by the data, model, and prior information on the parameters. Here we develop a Bayesian inversion framework that uses Interferometric Synthetic Aperture Radar (InSAR) surface deformation data to infer the laterally heterogeneous
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Two-grid method on unstructured tetrahedra: Applying computational geometry to staggered solution of coupled flow and mechanics problems arXiv.cs.CE Pub Date : 2021-02-07 Saumik Dana; Xiaoxi Zhao; Birendra Jha
We develop a computational framework that leverages the features of sophisticated software tools and numerics to tackle some of the pressing issues in the realm of earth sciences. The algorithms to handle the physics of multiphase flow, concomitant geomechanics all the way to the surface of the earth and the complex geometries of field cases with surfaces of discontinuity are stacked on top of each
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A Data-Driven Approach to Violin Making arXiv.cs.CE Pub Date : 2021-02-03 Sebastian Gonzalez; Davide Salvi; Daniel Baeza; Fabio Antonacci; Augusto Sarti
Of all the characteristics of a violin, those that concern its shape are probably the most important ones, as the violin maker has complete control over them. Contemporary violin making, however, is still based more on tradition than understanding, and a definitive scientific study of the specific relations that exist between shape and vibrational properties is yet to come and sorely missed. In this
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Hierarchical a posteriori error estimation of Bank-Weiser type in the FEniCS Project arXiv.cs.CE Pub Date : 2021-02-08 Raphaël BulleUniversity of Luxembourg; Jack S. HaleUniversity of Luxembourg; Alexei LozinskiUniversité de Bourgogne Franche-Comté; Stéphane P. A. BordasUniversity of Luxembourg; Franz ChoulyUniversité de Bourgogne Franche-Comté
In the seminal paper of Bank and Weiser [Math. Comp., 44 (1985), pp.283-301] a new a posteriori estimator was introduced. This estimator requires the solution of a local Neumann problem on every cell of the finite element mesh. Despite the promise of Bank-Weiser type estimators, namely locality, computational efficiency, and asymptotic sharpness, they have seen little use in practical computational
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Correlated Bandits for Dynamic Pricing via the ARC algorithm arXiv.cs.CE Pub Date : 2021-02-08 Samuel Cohen; Tanut Treetanthiploet
The Asymptotic Randomised Control (ARC) algorithm provides a rigorous approximation to the optimal strategy for a wide class of Bayesian bandits, while retaining reasonable computational complexity. In particular, it allows a decision maker to observe signals in addition to their rewards, to incorporate correlations between the outcomes of different choices, and to have nontrivial dynamics for their
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An enhanced parametric nonlinear reduced order model for imperfect structures using Neumann expansion arXiv.cs.CE Pub Date : 2021-02-02 Jacopo Marconi; Paolo Tiso; Davide E. Quadrelli; Francesco Braghin
We present an enhanced version of the parametric nonlinear reduced order model for shape imperfections in structural dynamics we studied in a previous work [1]. The model is computed intrusively and with no training using information about the nominal geometry of the structure and some user-defined displacement fields representing shape defects, i.e. small deviations from the nominal geometry parametrized
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Deep Hedging under Rough Volatility arXiv.cs.CE Pub Date : 2021-02-03 Blanka Horvath; Josef Teichmann; Zan Zuric
We investigate the performance of the Deep Hedging framework under training paths beyond the (finite dimensional) Markovian setup. In particular we analyse the hedging performance of the original architecture under rough volatility models with view to existing theoretical results for those. Furthermore, we suggest parsimonious but suitable network architectures capable of capturing the non-Markoviantity
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A Novel Use of Discrete Wavelet Transform Features in the Prediction of Epileptic Seizures from EEG Data arXiv.cs.CE Pub Date : 2021-01-31 Cyrille Feudjio; Victoire Djimna Noyum; Younous Perieukeu Mofendjou; Rockefeller; Ernest Fokoué
This paper demonstrates the predictive superiority of discrete wavelet transform (DWT) over previously used methods of feature extraction in the diagnosis of epileptic seizures from EEG data. Classification accuracy, specificity, and sensitivity are used as evaluation metrics. We specifically show the immense potential of 2 combinations (DWT-db4 combined with SVM and DWT-db2 combined with RF) as compared
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On the periodicity of cardiovascular fluid dynamics simulations arXiv.cs.CE Pub Date : 2021-01-29 Martin R. Pfaller; Jonathan Pham; Nathan M. Wilson; David W. Parker; Alison L. Marsden
Three-dimensional cardiovascular fluid dynamics simulations typically require computation of several cardiac cycles before they reach a periodic solution, rendering them computationally expensive. Furthermore, there is currently no standardized method to determine whether a simulation has yet reached that periodic state. In this work, we propose use of the asymptotic error measure to quantify the difference
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High Resolution 3D Ultrasonic Breast Imaging by Time-Domain Full Waveform Inversion arXiv.cs.CE Pub Date : 2021-02-01 Felix Lucka; Mailyn Pérez-Liva; Bradley E. Treeby; Ben T. Cox
Ultrasound tomography (UST) scanners allow quantitative images of the human breast's acoustic properties to be derived with potential applications in screening, diagnosis and therapy planning. Time domain full waveform inversion (TD-FWI) is a promising UST image formation technique that fits the parameter fields of a wave physics model by gradient-based optimization. For high resolution 3D UST, it
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Integration of activation maps of epicardial veins in computational cardiac electrophysiology arXiv.cs.CE Pub Date : 2021-01-31 Simone Stella; Christian Vergara; Massimiliano Maines; Domenico Catanzariti; Pasquale C. Africa; Cristina Demattè; Maurizio Centonze; Fabio Nobile; Maurizio Del Greco; Alfio Quarteroni
In this work we address the issue of validating the monodomain equation used in combination with the Bueno-Orovio ionic model for the prediction of the activation times in cardiac electro-physiology of the left ventricle. To this aim, we consider our patients who suffered from Left Bundle Branch Block (LBBB). We use activation maps performed at the septum as input data for the model and maps at the
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A Momentum-Conserving Implicit Material Point Method for Surface Energies with Spatial Gradients arXiv.cs.CE Pub Date : 2021-01-29 Jingyu Chen; Victoria Kala; Alan Marquez-Razon; Elias Gueidon; David A. B. Hyde; Joseph Teran
We present a novel Material Point Method (MPM) discretization of surface tension forces that arise from spatially varying surface energies. These variations typically arise from surface energy dependence on temperature and/or concentration. Furthermore, since the surface energy is an interfacial property depending on the types of materials on either side of an interface, spatial variation is required
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Non-intrusive reduced order modeling of poroelasticity of heterogeneous media based on a discontinuous Galerkin approximation arXiv.cs.CE Pub Date : 2021-01-28 T. Kadeethum; F. Ballarin; N. Bouklas
We present a non-intrusive model reduction framework for linear poroelasticity problems in heterogeneous porous media using proper orthogonal decomposition (POD) and neural networks, based on the usual offline-online paradigm. As the conductivity of porous media can be highly heterogeneous and span several orders of magnitude, we utilize the interior penalty discontinuous Galerkin (DG) method as a
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Multigrid reduction preconditioning framework for coupled processes in porous and fractured media arXiv.cs.CE Pub Date : 2021-01-27 Quan M. Bui; Francois P. Hamon; Nicola Castelletto; Daniel Osei-Kuffuor; Randolph R. Settgast; Joshua A. White
Many subsurface engineering applications involve tight-coupling between fluid flow, solid deformation, fracturing, and similar processes. To better understand the complex interplay of different governing equations, and therefore design efficient and safe operations, numerical simulations are widely used. Given the relatively long time-scales of interest, fully-implicit time-stepping schemes are often
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Predicting the Mechanical Properties of Fibrin Using Neural Networks Trained on Discrete Fiber Network Data arXiv.cs.CE Pub Date : 2021-01-23 Yue Leng; Sarah Calve; Adrian Buganza Tepole
Fibrin is a structural protein key for processes such as wound healing and thrombus formation. At the macroscale, fibrin forms a gel and has a mechanical response that is dictated by the mechanics of a microscale fiber network. Hence, accurate description of fibrin gels can be achieved using representative volume elements (RVE) that explicitly model the discrete fiber networks of the microscale. These
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Accurate and Efficient Simulations of Hamiltonian Mechanical Systems with Discontinuous Potentials arXiv.cs.CE Pub Date : 2021-01-26 Molei Tao; Shi Jin
This article considers Hamiltonian mechanical systems with potential functions admitting jump discontinuities. The focus is on accurate and efficient numerical approximations of their solutions, which will be defined via the laws of reflection and refraction. Despite of the success of symplectic integrators for smooth mechanical systems, their construction for the discontinuous ones is nontrivial,
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Data-Driven simulation of inelastic materials using structured data sets, tangent space information and transition rules arXiv.cs.CE Pub Date : 2021-01-26 Kerem Ciftci; Klaus Hackl
Data-driven computational mechanics replaces phenomenological constitutive functions by performing numerical simulations based on data sets of representative samples in stress-strain space. The distance of modeling values, e.g. stresses and strains in integration points of a finite element calculation, from the data set is minimized with respect to an appropriate metric, subject to equilibrium and
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Propagation and reconstruction of re-entry uncertainties using continuity equation and simplicial interpolation arXiv.cs.CE Pub Date : 2021-01-22 Mirko Trisolini; Camilla Colombo
This work proposes a continuum-based approach for the propagation of uncertainties in the initial conditions and parameters for the analysis and prediction of spacecraft re-entries. Using the continuity equation together with the re-entry dynamics, the joint probability distribution of the uncertainties is propagated in time for specific sampled points. At each time instant, the joint probability distribution
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Modeling cardiac muscle fibers in ventricular and atrial electrophysiology simulations arXiv.cs.CE Pub Date : 2021-01-26 Roberto Piersanti; Pasquale C. Africa; Marco Fedele; Christian Vergara; Luca Dedè; Antonio F. Corno; Alfio Quarteroni
Since myocardial fibers drive the electric signal propagation throughout the myocardium, accurately modeling their arrangement is essential for simulating heart electrophysiology (EP). Rule-Based-Methods (RBMs) represent a commonly used strategy to include cardiac fibers in computational models. A particular class of such methods is known as Laplace-Dirichlet-Rule-Based-Methods (LDRBMs) since they
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On the Use of Computational Fluid Dynamics (CFD) Modelling to Design Improved Dry Powder Inhalers arXiv.cs.CE Pub Date : 2021-01-21 David F Fletcher; Vishal Chaugule; Larissa Gomes dos Reis; Paul M Young; Daniela Traini; Julio Soria
Purpose: Computational Fluid Dynamics (CFD) simulations are performed to investigate the impact of adding a grid to a two-inlet dry powder inhaler (DPI). The purpose of the paper is to show the importance of the correct choice of closure model and modeling approach, as well as to perform validation against particle dispersion data obtained from in-vitro studies and flow velocity data obtained from
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A continuum and computational framework for viscoelastodynamics: finite deformation linear model arXiv.cs.CE Pub Date : 2021-01-25 Ju Liu; Marcos Latorre
This work concerns the continuum basis and numerical formulation for deformable materials with viscous dissipative mechanisms. We derive a viscohyperelastic modeling framework based on fundamental thermomechanical principles. Since most large deformation problems exhibit the isochoric property, our modeling work is constructed based on the Gibbs free energy in order to develop a continuum theory using
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F3ORNITS: A Flexible Variable Step Size Non-Iterative Co-simulation Method handling Subsystems with Hybrid Advanced Capabilities arXiv.cs.CE Pub Date : 2021-01-22 Yohan Eguillon; Bruno Lacabanne; Damien Tromeur-Dervout
This paper introduces the F3ORNITS non-iterative co-simulation algorithm in which F3 stands for the 3 flexible aspects of the method: flexible polynomial order representation of coupling variables, flexible time-stepper applying variable co-simulation step size rules on subsystems allowing it and flexible scheduler orchestrating the meeting times among the subsystems and capable of asynchronousness
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An ensemble solver for segregated cardiovascular FSI arXiv.cs.CE Pub Date : 2021-01-22 X. Li; Daniele E. Schiavazzi
Computational models are increasingly used for diagnosis and treatment of cardiovascular disease. To provide a quantitative hemodynamic understanding that can be effectively used in the clinic, it is crucial to quantify the variability in the outputs from these models due to multiple sources of uncertainty. To quantify this variability, the analyst invariably needs to generate a large collection of
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Bending behavior of additively manufactured lattice structures: numerical characterization and experimental validation arXiv.cs.CE Pub Date : 2021-01-22 Nina Korshunova; Gianluca Alaimo; Seyyed Bahram Hosseini; Massimo Carraturo; Alessandro Reali; Jarkko Niiranen; Ferdinando Auricchio; Ernst Rank; Stefan Kollmannsberger
Selective Laser Melting (SLM) technology has undergone significant development in the past years providing unique flexibility for the fabrication of complex metamaterials such as octet-truss lattices. However, the microstructure of the final parts can exhibit significant variations due to the high complexity of the manufacturing process. Consequently, the mechanical behavior of these lattices is strongly
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Multi-Scale Games: Representing and Solving Games on Networks with Group Structure arXiv.cs.CE Pub Date : 2021-01-20 Kun Jin; Yevgeniy Vorobeychik; Mingyan Liu
Network games provide a natural machinery to compactly represent strategic interactions among agents whose payoffs exhibit sparsity in their dependence on the actions of others. Besides encoding interaction sparsity, however, real networks often exhibit a multi-scale structure, in which agents can be grouped into communities, those communities further grouped, and so on, and where interactions among
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Quadratic Residual Networks: A New Class of Neural Networks for Solving Forward and Inverse Problems in Physics Involving PDEs arXiv.cs.CE Pub Date : 2021-01-20 Jie Bu; Anuj Karpatne
We propose quadratic residual networks (QRes) as a new type of parameter-efficient neural network architecture, by adding a quadratic residual term to the weighted sum of inputs before applying activation functions. With sufficiently high functional capacity (or expressive power), we show that it is especially good for solving forward and inverse physics problems involving partial differential equations
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Fast formation and assembly of isogeometric Galerkin matrices for trimmed patches arXiv.cs.CE Pub Date : 2021-01-20 Benjamin Marussig
This work explores the application of the fast assembly and formation strategy from [8, 17] to trimmed bi-variate parameter spaces. Two concepts for the treatment of basis functions cut by the trimming curve are investigated: one employs a hybrid Gauss-point-based approach, and the other computes discontinuous weighted quadrature rules. The concepts' accuracy and efficiency are examined for the formation
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Multiobjective Multitasking Optimization Based on Decomposition with Dual Neighborhoods arXiv.cs.CE Pub Date : 2021-01-19 Xianpeng Wang; Zhiming Dong; Lixin Tang; Qingfu Zhang
This paper proposes a multiobjective multitasking optimization evolutionary algorithm based on decomposition with dual neighborhood. In our proposed algorithm, each subproblem not only maintains a neighborhood based on the Euclidean distance among weight vectors within its own task, but also keeps a neighborhood with subproblems of other tasks. Gray relation analysis is used to define neighborhood
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Cell division in deep material networks applied to multiscale strain localization modeling arXiv.cs.CE Pub Date : 2021-01-18 Zeliang Liu
Despite the increasing importance of strain localization modeling (e.g., failure analysis) in computer-aided engineering, there is a lack of effective approaches to consistently modeling related material behaviors across multiple length scales. We aim to address this gap within the framework of deep material networks (DMN) - a physics-based machine learning model with embedded mechanics in the building
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Optical Flow Method for Measuring Deformation of Soil Specimen Subjected to Torsional Shearing arXiv.cs.CE Pub Date : 2021-01-18 Piotr E. Srokosz; Marcin Bujko; Marta Bocheńska; Rafał Ossowski
In this study optical flow method is used for soil deformation measurement in laboratory tests. The main objective was to observe how the deformation distributes along the whole height of cylindrical soil sample subjected to torsional shearing (TS test). The experiments were conducted on dry non-cohesive soil samples under two different values of isotropic pressure. Samples were loaded with low-amplitude