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Distributed Strategy for Power Re-Allocation in High Performance Applications

Journal of Computer and Communications 2020年第12期8卷 142-158页

作者： Vaibhav Sundriyal Masha Sosonkina Department of Computational Modeling and Simulation Engineering Old Dominion University Norfolk Virginia USA

To improve the power consumption of parallel applications at the runtime, modern processors provide frequency scaling and power limiting capabilities. In this work, a runtime strategy is proposed to distribute a given power allocation among the cluster nodes assigned to the application while balancing their performance change. The strategy operates in a timeslice-based manner to estimate the current application performance and power usage per node followed by power redistribution across the nodes. Experiments, performed on four nodes (112 cores) of a modern computing platform interconnected with Infiniband showed that even a significant power budget reduction of 20% may result in a performance degradation of as low as 1% under the proposed strategy compared with the execution in the unlimited power case.

关键词： Multinode Power Allocation RAPL UFS DVFS Maximizing Performance Component Power

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Ab initio phonon transport across grain boundaries in graphene using machine learning based on small dataset

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Physical Review Materials 2022年第4期6卷 044004-044004页

作者： Amirreza Hashemi Ruiqiang Guo Keivan Esfarjani Sangyeop Lee Computational Modeling and Simulation Program University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical and Aerospace Engineering University of Virginia Charlottesville Virginia 22904 USA Department of Materials Science and Engineering University of Virginia Charlottesville Virginia 22904 USA Department of Physics University of Virginia Charlottesville Virginia 22904 USA Department of Physics and Astronomy University of Pittsburgh Pittsburgh Pennsylvania 15261 USA

Establishing the structure-property relationship for grain boundaries (GBs) is critical for developing next-generation functional materials but has been severely hampered due to its extremely large configurational space. Atomistic simulations with low computational cost and high predictive power are strongly desirable, but the conventional simulations using empirical interatomic potentials and density functional theory suffer from the lack of predictive power and high computational cost, respectively. A machine learning interatomic potential (MLIP) recently emerged but often requires extensive size of the training dataset, making it a less feasible approach. Here, we demonstrate that an MLIP trained with a rationally designed small training dataset can predict thermal transport across GBs in graphene with ab initio accuracy at an affordable computational cost. We employed a rational approach based on the structural unit model to find a small set of GBs that can represent the entire configurational space and thus can serve as a cost-effective training dataset for the MLIP. Only 5 GBs were found to be enough to represent the entire configurational space of graphene GBs. Using the atomistic Green's function approach and the MLIP, we revealed that the structure-thermal resistance relation in graphene does not follow the common understanding that large dislocation density causes larger thermal resistance. In fact, thermal resistance is nearly independent of dislocation density at room temperature and is higher when the dislocation density is small at sub-room temperature. We explain this intriguing behavior with the buckling near a GB causing a strong scattering of flexural phonon modes. In this paper, we show that a machine learning technique combined with conventional wisdom (e.g., structural unit model) can extend the recent success of ab initio thermal transport simulation, which has been mostly limited to single crystals, to complex yet practically important polycry

关键词： Phonons Graphene Landauer formula Machine learning

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Fatigue prediction for metallic additively manufactured lattice components using FCM based on average strain energy density approach

Fatigue prediction for metallic additively manufactured latt...

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International Congress on Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS)

作者： R. De Biasi O. Oztoprak F. Zanini S. Carmignato F. Berto S. Kollmannsberger M. Benedetti Department of Industrial Engineering Via Sommarive 9 University of Trento Trento Italy School of Engineering and Design Chair of Computational Modeling and Simulation Arcisstraße 21 Technical University of Munich Munich Germany Department of Management and Engineering Stradella San Nicola 3 University of Padova Vicenza Italy Department of Chemical Engineering Materials Environment Via Eudossiana 18 University of Rome Sapienza Roma Italy Faculty of Civil and Environmental Sciences Chair of Data Science in Engineering Coudraystraße 13b Bauhaus-Universität Weimar Weimar Germany

ISBN: (数字)9798350373493

ISBN: (纸本)9798350373509

An accurate prediction of the fatigue life of metallic additively manufactured lattice structures is still a challenging task. The proposed work addresses this challenge of industrial relevance through the computation of an as-built geometry of a lattice structure directly from its X-ray computed tomography reconstruction. The computation is carried out by taking advantage of the Finite Cell Method and applies the average strain energy density method to predict fatigue failure. The proof of concept provided in this work shows an excellent agreement in the fatigue prediction, paving the way for a computationally accurate fatigue life prediction of other types of metamaterials.

关键词： Geometry Accuracy Lattices Fatigue Metamaterials Topology X-ray imaging Stress Strain Testing

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Estimation of Aortic Valve Interstitial Cell-Induced 3D Remodeling of Poly(Ethylene Glycol) Hydrogel Environments Using an Inverse Finite Element Approach

SSRN

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SSRN 2022年

作者： Khang, Alex Steinman, John Tuscher, Robin Feng, Xinzeng Sacks, Michael S. James T. Willerson Center for Cardiovascular Modeling and Simulation Oden Institute for Computational Engineering and Sciences The Department of Biomedical Engineering The University of Texas at Austin 201 East 24th St Stop C0200 AustinTX78712-1229 United States

Aortic valve interstitial cells (AVICs) reside within the leaflet tissues of the aortic valve and function to replenish, restore, and remodel extracellular matrix components. AVIC contractility is brought about through the contractile properties of the underlying stress fibers and plays a crucial role in processes such as wound healing and mechanotransduction. Currently, it is technically challenging to directly investigate AVIC contractile behaviors within the dense leaflet tissues. As a result, optically clear poly (ethylene glycol) (PEG) hydrogel matrices have been used to study AVIC contractility through means of 3D traction force microscopy (3DTFM). However, the stiffness of the hydrogel material within the vicinity of the AVIC is difficult to measure directly and is further confounded by the remodeling activity of the AVIC. Ambiguity in the local hydrogel mechanical properties can lead to large errors in computed cellular tractions. Herein, we developed an inverse computational approach to estimate AVIC-induced remodeling of the hydrogel material. The capabilities of the model were validated with a ground truth data set generated via a test problem comprised of an experimentally measured AVIC geometry and a prescribed modulus field containing unmodified, stiffened, and degraded regions. The inverse model was able to estimate the ground truth data set with high accuracy. When applied to AVICs assessed via 3DTFM, the model estimated regions of significant stiffening and degradation local to the AVIC. We observed that stiffening was largely localized at AVIC protrusions and was likely a result of collagen deposition as confirmed by immunostaining for collagen type 1. Degradation was more spatially uniform and present in regions further away from the AVIC surface and likely a result of enzymatic activity. Our results indicate that AVICs substantially modify the local hydrogel mechanics, which were successfully quantified by our computational model. Looking forward

关键词： Tissue

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Parallel solution of saddle point systems with nested iterative solvers based on the Golub-Kahan Bidiagonalization

Parallel solution of saddle point systems with nested iterat...

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作者： Kruse, Carola Sosonkina, Masha Arioli, Mario Tardieu, Nicolas Rüde, Ulrich Cerfacs Toulouse France Department of Computational Modeling and Simulation Engineering Old Dominion University NorfolkVA United States Libera Universita Mediterranea Casamassima Italy IMSIA UMR 9219 EDF-CNRS-CEA-ENSTA Université Paris Saclay Paris France Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Germany

The Golub-Kahan bidiagonalization is widely used in the singular value decomposition of rectangular matrices and has been generalized to an iterative solver for symmetric indefinite linear systems with a two-by-two block structure. In this work, we present a scalability study of this generalized solver as implemented in a recent release of the parallel numerical library PETSc (Portable, Extensible Toolkit for Scientific Computation). We present an improved solver performance for the two-dimensional (2D) Stokes equations as compared to previous work. Furthermore, we investigate the performance of different parallel inner solvers in the outer Golub-Kahan iteration for a three-dimensional Stokes problem. The study includes parallel sparse direct solvers and multigrid methods. When increasing the number of cores for a fixed total problem size, the solver exhibits good speedups of up to 50% at the 1024 core count. For the tests in which the total problem size grows while the workload in each core stays constant, the parallel performance of the solver scales almost linearly with the increase in the core counts. In particular, the computation time increases only by about 15% when the number of cores increases from 80 to 1024 for a 2D test case. © 2020 John Wiley & Sons, Ltd.

关键词： Singular value decomposition

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A computational Pipeline for Patient-Specific Prediction of the Postoperative Mitral Valve Functional State

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Journal of Biomechanical engineering 2023年第11期145卷 111002-111002页

作者： Liu, Hao Simonian, Natalie T. Pouch, Alison M. Iaizzo, Paul A. Gorman, Joseph H. Gorman, Robert C. Sacks, Michael S. James T. Willerson Center for Cardiovascular Modeling and Simulation The Oden Institute for Computational Engineering and Sciences Department of Biomedical Engineering The University of Texas at Austin AustinTX78712-1229 United States Departments of Radiology and Bioengineering University of Pennsylvania PhiladelphiaPA19104 United States Visible Heart Laboratories Department of Surgery University of Minnesota MinneapolisMN55455 United States Gorman Cardiovascular Research Group Department of Surgery Smilow Center for Translational Research Perelman School of Medicine University of Pennsylvania PhiladelphiaPA United States

While mitral valve (MV) repair remains the preferred clinical option for mitral regurgitation (MR) treatment, long-term outcomes remain suboptimal and difficult to predict. Furthermore, pre-operative optimization is complicated by the heterogeneity of MR presentations and the multiplicity of potential repair configurations. In the present work, we established a patient-specific MV computational pipeline based strictly on standard-of-care pre-operative imaging data to quantitatively predict the post-repair MV functional state. First, we established human mitral valve chordae tendinae (MVCT) geometric characteristics obtained from five CT-imaged excised human hearts. From these data, we developed a finite-element model of the full patient-specific MV apparatus that included MVCT papillary muscle origins obtained from both the in vitro study and the pre-operative three-dimensional echocardiography images. To functionally tune the patient-specific MV mechanical behavior, we simulated pre-operative MV closure and iteratively updated the leaflet and MVCT prestrains to minimize the mismatch between the simulated and target end-systolic geometries. Using the resultant fully calibrated MV model, we simulated undersized ring annuloplasty (URA) by defining the annular geometry directly from the ring geometry. In three human cases, the postoperative geometries were predicted to 1 mm of the target, and the MV leaflet strain fields demonstrated close agreement with noninvasive strain estimation technique targets. Interestingly, our model predicted increased posterior leaflet tethering after URA in two recurrent patients, which is the likely driver of long-term MV repair failure. In summary, the present pipeline was able to predict postoperative outcomes from pre-operative clinical data alone. This approach can thus lay the foundation for optimal tailored surgical planning for more durable repair, as well as development of mitral valve digital twins. © 2023 American Society of Mec

关键词： Geometry

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Design and validation of a unity-based simulation to investigate gesture based control of semi-autonomous vehicles 12th

Design and validation of a unity-based simulation to investi...

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12th International Conference on Virtual, Augmented and Mixed Reality, VAMR 2020, held as part of the 22nd International Conference on Human-Computer Interaction, HCII 2020

作者： Sanders, Brian Shen, Yuzhong Vincenzi, Dennis Department of Engineering and Technology Embry-Riddle Aeronautical University Worldwide Daytona Beach United States Department of Computational Modeling and Simulation Engineering Old Dominion University NorfolkVA United States Department of Graduate Studies Embry-Riddle Aeronautical University Worldwide Daytona Beach United States

ISBN: (纸本)9783030496944

The objective of this investigation is to explore the use of hand gestures to control semi-autonomous vehicles. This was achieved through the use of simulations built in Unity and real-life demonstrations. Screen-spaced simulations modeled the control of a recreational quadcopter while Virtual Reality simulations followed by actual demonstrations used a small ground vehicle. The purpose of the actual demonstrations was to validate observations and lessons learned about vehicle control and human performance from the simulations. The investigative process involved identifying natural gestures to control basic functions of a vehicle, matching them to the selected gesture capture technology, developing algorithms to interpret those gestures for vehicle control, and arranging the appropriate visual environment using the Unity game engine to investigate preferred use of those gestures. Observations and participant feedback aided in refining the gesture algorithms for vehicle control and visual information, indicated the simulations provided suitable learning experiences and environments from which to assess human performance. Results indicate that the gesture-based approach holds promise given the availability of new technology. © Springer Nature Switzerland AG 2020.

关键词： Ground vehicles

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Scalability of Sensor simulation in ROS-Gazebo Platform with and without Using GPU

Scalability of Sensor Simulation in ROS-Gazebo Platform with...

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Spring simulation Conference (SpringSim)

作者： Ahmet Saglam Yiannis Papelis Department of Computational Modeling and Simulation Engineering Old Dominion University Norfolk VA USA Virginia Modeling Analysis and Simulation Center Old Dominion University Suffolk VA USA

ISBN: (数字)9781565553705

ISBN: (纸本)9781728163642

Autonomous mobile robots depend heavily on sensors for interpreting the external environment and planning their movement. Given the complexity of even simple environments, the use of simulation is necessary to test sensory perception and movement strategies efficiently. Accurate and efficient sensor simulation is key to the successful development and fielding of autonomous mobile robots. In this paper, we investigate the scalability of LIDAR-type sensor simulation in ROS-supported Gazebo, an open-source multi-robot simulator. Specifically, the performance and scalability of the simulator are assessed with and without support from GPU in two virtual worlds, one highly-complex in terms of the number of collision targets and one not-complex. In both cases, we increase the number of sensors and evaluate system performance. The results show that the use of GPU helps improve performance, providing better speedups in the complex scene. However, the number of sensors that can be used is limited when using GPU.

关键词： Robot sensing systems Graphics processing units computational modeling Complexity theory Scalability Analytical models

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Concrete Defect Classification Based on a Digital Twin Platform

SSRN

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SSRN 2024年

作者： Calcagni, Maria Teresa Salerno, Giovanni Martarelli, Milena Schlenger, Jonas Urs Hassan, Thomas Heinikainen, Rene Borrmann, André Fies, Bruno Revel, Gian Marco Department of Industrial Engineering and Mathematical Sciences Università Politecnica delle Marche Via Brecce Bianche 12 Ancona60131 Italy Computational Modeling and Simulation Technical University of Munich Arcisstraße 21 München80333 Germany Orange Rue Olivier de Serres 78 Paris75015 France Fira Group Oy Teknobulevardi 3-5 Vantaa01530 Finland Centre Scientifique et Technique du Batiment Avenue Jean Jaures 84 Champs sur Marne77420 France

Ensuring the durability of civil buildings is critical to preventing long-term structural failure. Traditional damage assessment methods, based on visual inspections, are labor-intensive and subjective. The adoption of Digital Building Twin (DBT) platforms emerges as a solution for comprehensive monitoring of the building throughout its life cycle. This study, part of the European BIM2TWIN project, focuses on concrete surface quality monitoring using vision techniques and deep learning algorithms. Four neural network models are created for cracks, honeycombing, pitting and exposed bars, collectively analyzing the images to identify and quantify defects. Project managers can assess the criticality of defects based on accurate pixel counts and geometric features, converting measurements from pixels to millimeters. The data are then stored in the DBT platform, providing a historical record for future reference and decision-making by project managers. © 2024, The Authors. All rights reserved.

关键词： Pixels

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Bending behavior of additively manufactured lattice structures: Numerical characterization and experimental validation

arXiv

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arXiv 2021年

作者： Korshunova, Nina Alaimo, Gianluca Hosseini, Seyyed Bahram Carraturo, Massimo Reali, Alessandro Niiranen, Jarkko Auricchio, Ferdinando Rank, Ernst Kollmannsberger, Stefan Chair of Computational Modeling and Simulation Technische Universität München Germany Department of Civil Engineering and Architecture University of Pavia Italy Institute for Advanced Study Technische Universität München Germany Department of Civil Engineering Aalto University Finland

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 dependent on the process-induced defects, raising the importance on the incorporation of as-manufactured geometries into the computational structural analysis. This, in turn, challenges the traditional mesh-conforming methods making the computational costs prohibitively large. In the present work, an immersed image-to-analysis framework is applied to efficiently evaluate the bending behavior of AM lattices. To this end, we employ the Finite Cell Method (FCM) to perform a three-dimensional numerical analysis of the three-point bending test of a lattice structure and compare the as-designed to as-manufactured effective properties. Furthermore, we undertake a comprehensive study on the applicability of dimensionally reduced beam models to the prediction of the bending behavior of lattice beams and validate classical and strain gradient beam theories applied in combination with the FCM. The numerical findings suggest that the SLM octet-truss lattices exhibit size effects, thus, requiring a flexible framework to incorporate high-order continuum theories. © 2021, CC BY-NC-ND.

关键词： Finite element method

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