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Predicting EHL film thickness parameters by machine learning approaches

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Friction 2023年第6期11卷 992-1013页

作者： Max MARIAN jonas MURSAK Marcel BARTZ Francisco j.PROFITO Andreas ROSENKRANZ Sandro WARTZACK Department of Mechanical and Metallurgical Engineering School of EngineeringPontificia Universidad Católica de ChileSantiago6904411Chile Engineering Design Friedrich-Alexander-University Erlangen-Nuremberg(FAU)Erlangen91058Germany Department of Mechanical Engineering Polytechnic School of the University of São PauloSão Paulo05508-030Brazil Department of Chemical Engineering Biotechnology and Materials(DIQBM)FCFMUniversidad de ChileSantiago8370456Chile

Non-dimensional similarity groups and analytically solvable proximity equations can be used to estimate integral fluid film parameters of elastohydrodynamically lubricated(EHL)contacts.In this contribution,we demonstrate that machine learning(ML)and artificial intelligence(AI)approaches(support vector machines,Gaussian process regressions,and artificial neural networks)can predict relevant film parameters more efficiently and with higher accuracy and flexibility compared to sophisticated EHL simulations and analytically solvable proximity equations,respectively.For this purpose,we use data from EHL simulations based upon the full-system finite element(FE)solution and a Latin hypercube sampling.We verify that the original input data are required to train ML approaches to achieve coefficients of determination above 0.99.It is revealed that the architecture of artificial neural networks(neurons per layer and number of hidden layers)and activation functions influence the prediction accuracy.The impact of the number of training data is exemplified,and recommendations for a minimum database size are given.We ultimately demonstrate that artificial neural networks can predict the locally-resolved film thickness values over the contact domain 25-times faster than FE-based EHL simulations(R^(2) values above 0.999).We assume that this will boost the use of ML approaches to predict EHL parameters and traction losses in multibody system dynamics simulations.

关键词： machine learning elastohydrodynamic lubrication film thickness support vector machine Gaussian process regression artificial neural network

Identity(ies)and Transnationalization of Brazilian Evangelical Churches in Portugal:Case study of World Cathedral of Hope and Victory in Christ Churches

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Cultural and Religious Studies 2024年第3期12卷 133-145页

作者： jonas Pereira de Oliveira júnior University of Porto PortoPortugal

The presence of evangelicals in Brazil is a social and religious phenomenon that has aroused interest of many scholars due to its rapid and significant expansion in recent decades and its projection beyond national borders.Among evangelical denominations that stand out in this scenario are Pentecostal churches,which have developed intense missionary activity in several countries,including Europe.In this article,we intend to analyze features and challenges of Brazilian evangelical churches:World Cathedral of Hope(CIME)(Catedral Mundial da Esperança-ICME)and Assembly of God Victory in Christ(ADVEC)(Assembleia de Deus Vitória em Cristo-ADVEC)that operate in Portugal,seeking to understand issues of identity and belonging of these communities,their models of transnationalization,its evangelization strategies and its adaptations to Portuguese context,in the period from 2000 to 2020.

关键词： identity transnationalization secularization Brazilian migration

A Low Mach Number IMEX Flux Splitting for the Level Set Ghost Fluid Method

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Communications on Applied Mathematics and Computation 2023年第2期5卷 722-750页

作者： jonas Zeifang Andrea Beck Faculty of Sciences Hasselt UniversityAgoralaan Gebouw DBE-3590 DiepenbeekBelgium Institute of Aerodynamics and Gas Dynamics University of StuttgartPfaffenwaldring 2170569 StuttgartGermany Laboratory of Fluid Dynamics and Technical Flows Otto von Guericke University MagdeburgUniversitatsplatz 239106 MagdeburgGermany

Considering droplet phenomena at low Mach numbers,large differences in the magnitude of the occurring characteristic waves are presented.As acoustic phenomena often play a minor role in such applications,classical explicit schemes which resolve these waves suffer from a very restrictive timestep restriction.In this work,a novel scheme based on a specific level set ghost fluid method and an implicit-explicit(IMEX)flux splitting is proposed to overcome this timestep restriction.A fully implicit narrow band around the sharp phase interface is combined with a splitting of the convective and acoustic phenomena away from the interface.In this part of the domain,the IMEX Runge-Kutta time discretization and the high order discontinuous Galerkin spectral element method are applied to achieve high accuracies in the bulk phases.It is shown that for low Mach numbers a significant gain in computational time can be achieved compared to a fully explicit method.Applica-tions to typical droplet dynamic phenomena validate the proposed method and illustrate its capabilities.

关键词： IMEX flux splitting Level set method Ghost fluid method Low Mach number flows

Accelerated flow softening and dynamic transformation of Ti-6Al-4V alloy in two-phase region during hot deformation via coarsening αgrain

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journal of Materials Science & Technology 2020年第1期36卷 160-166页

作者： Xiankun ji Baoqi Guo Fulin jiang Hong Yu Dingfa Fu jie Teng Hui Zhang john j.jonas College of Materials Science and Engineering Hunan UniversityChangsha 410082China Materials Engineering McGill University3610 University St.Montreal H3A 0C5Canada

The flow softening is an important phenomenon during hot deformation of metallic materials.In the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coarser a grain sample,which was attributed to an accelerated dynamic transformation from harder α phase into β phases.Notably,full β microstructure was observed in coarse grain samples at strain of 1.2,while retained a phase was observed in fine a grain specimens.In the views of thermodynamics and crystallographic analysis,the in-depth mechanisms of dynamic transformation were further investigated.

关键词： Titanium alloys Hot deformation Flow softening Dynamic transformation Grain size

Combining High-Resolution Imaging,Deep Learning,and Dynamic Modeling to Separate Disease and Senescence in Wheat Canopies

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Plant Phenomics 2023年第2期5卷 295-312页

作者： jonas Anderegg Radek Zenkl Achim Walter Andreas Hund Plant Pathology Group Institute of Integrative BiologyETH ZurichZurichSwitzerland Crop Science Group Institute of Agricultural SciencesETH ZurichZurichSwitzerland

Maintenance of sufficiently healthy green leaf area after anthesis is key to ensuring an adequate assimilate supply for grain filling.Tightly regulated age-related physiological senescence and various biotic and abiotic stressors drive overall greenness decay dynamics under field conditions.Besides direct effects on green leaf area in terms of leaf damage,stressors often anticipate or accelerate physiological senescence,which may multiply their negative impact on grain filling.Here,we present an image processing methodology that enables the monitoring of chlorosis and necrosis separately for ears and shoots(stems+leaves)based on deep learning models for semantic segmentation and color properties of vegetation.A vegetation segmentation model was trained using semisynthetic training data generated using image composition and generative adversarial neural networks,which greatly reduced the risk of annotation uncertainties and annotation effort.Application of the models to image time series revealed temporal patterns of greenness decay as well as the relative contributions of chlorosis and necrosis.Image-based estimation of greenness decay dynamics was highly correlated with scoring-based estimations(r≈0.9).Contrasting patterns were observed for plots with different levels of foliar diseases,particularly septoria tritici blotch.Our results suggest that tracking the chlorotic and necrotic fractions separately may enable(a)a separate quantification of the contribution of biotic stress and physiological senescence on overall green leaf area dynamics and(b)investigation of interactions between biotic stress and physiological senescence.The high-throughput nature of our methodology paves the way to conducting genetic studies of disease resistance and tolerance.

关键词： Wheat enable image

The interaction between a shaped charge jet and a single moving plate

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Defence Technology（防务技术） 2024年第1期31卷 1-13页

作者： Andreas Helte jonas Lundgren jonas Candle FOI WeaponsProtection and SecuritySE-16490StockholmSweden

Reactive armour is a very efficient add-on armour against shaped charge threats.Explosive reactive armour consists of one or several plates that are accelerated by an explosive.Similar but less violent acceleration of plates can also be achieved in a completely inert reactive armour.To be efficient against elongated jets,the motion of the plates needs to be inclined against the jet such that a sliding contact between the jet and the plates is established.This sliding contact causes a deflection and thinning of the jet.Under certain circumstances,the contact will become unstable,leading to severe disturbances on the jet.These disturbances will drastically reduce the jet penetration performance and it is therefore of interest to study the conditions that leads to an unstable contact.Previous studies on the interaction between shaped charge jets and flyer plates have shown that it is mainly the forward moving plate in an explosive reactive armour that is effective in disturbing the jet.This is usually attributed to the higher plate-to-jet mass flux ratio involved in the collision of the forward moving plate compared to the backward moving plate.For slow moving plates,as occurs in inert reactive armour,the difference in mass flux for the forward and backward moving plate is much lesser,and it is therefore of interest to study if other factors than the mass flux influences on the protection capability.In this work,experiments have been performed where a plate is accelerated along its length,interacting with a shaped charge jet that is fired at an oblique angle to the plate’s normal,either against or along the plate’s velocity.The arrangement corresponds to a jet interacting with a flyer plate from a reactive armour,with the exception that the collision velocity is the same for both types of obliquities in these experiments.The experiments show that disturbances on the jet are different in the two cases even though the collision velocities are the same.Numerical simulations of the interaction support the observation.Th

关键词： Reactive armour Flyer plate Shaped charge jet

STABLE BOUNDARY CONDITIONS AND DISCRETIZATION FOR P_(N) EQUATIONS

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journal of Computational Mathematics 2022年第6期40卷 977-1003页

作者： jonas Bunger Neeraj Sarna Manuel Torrilhon Applied and Computational Mathematics(ACoM) Department of MathematicsRWTH Aachen UniversitySchinkelstr 252062 AachenGermany

A solution to the linear Boltzmann equation satisfies an energy bound,which reflects a natural fact:The energy of particles in a finite volume is bounded in time by the energy of particles initially occupying the volume augmented by the energy transported into the volume by particles entering the volume over time.In this paper,we present boundary conditions(BCs)for the spherical harmonic(P_(N))approximation,which ensure that this fundamental energy bound is satisfied by the P_(N) approximation.Our BCs are compatible with the characteristic waves of P_(N) equations and determine the incoming waves uniquely.Both,energy bound and compatibility,are shown on abstract formulations of P_(N) equations and BCs to isolate the necessary structures and properties.The BCs are derived from a Marshak type formulation of BC and base on a non-classical even/odd-classification of spherical harmonic functions and a stabilization step,which is similar to the truncation of the series expansion in the P_(N) method.We show that summation by parts(SBP)finite differences on staggered grids in space and the method of simultaneous approximation terms(SAT)allows to maintain the energy bound also on the semi-discrete level.

关键词： Boundary conditions Energy stability Spherical harmonic(P_(N))approximation Kinetic theory Moment method Boltzmann Linear transport

Efficient transport pricing-why,what,and when?

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Communications in Transportation Research 2021年第1期1卷 31-38页

作者： jonas Eliasson Linköping University Swedish National Transport AdministrationSweden

Striking a balance between societal benefits and costs of transportation lies at the heart of transport planning and transport systems analysis.Increased transport and urbanization enable the many benefits of modern socieities through specialization of labour,production and lifestyles-but these trends simultaneously increase the drawbacks of transportation,such as carbon emissions,congestion,noise and air quality problems.Technical developments and improved infrastrastructure can help reduce these drawbacks,but they do not solve the fundamental problem that those reaping the benefits of transport-travellers,firms,customers-do not perceive the full social costs of transportation.To balance transport costs and benefits,efficient pricing is necessary.Despite a wealth of theoretical arguments,technical developments and substantial practical experience,efficient transport pricing is still rare.Focusing on the example of urban congestion pricing,this paper summarizes why transport pricing is needed,lessons learnt from practical experience,and what the main obstacles are.The two most important obstacles seem to be political power struggles between different levels of governments,and that even if total social gains vastly exceed total social losses,the losses tend to be more salient;losers tend to be easy to identify,while winners tend to be more dispersed and perhaps only exist in the future.

关键词： Congestion charges Road pricing Congestion pricing Intelligent transportation systems

Cytotoxic innate lymphoid cells sense tumor-derived IL-15: a novel mechanism of cancer immunosurveillance

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Signal Transduction and Targeted Therapy 2022年第10期7卷 3628-3629页

作者： Tobias Franz jonas Negele Sascha Kahlfuss Institute of Molecular and Clinical Immunology Medical FacultyOtto-von-Guericke University MagdeburgMagdeburgGermany Institute of Medical Microbiology and Hospital Hygiene Medical FacultyOtto-von-Guericke University MagdeburgMagdeburgGermany Health Campus Immunology Infectiology and Inflammation(GCI3)Medical FacultyOtto-Von-Guericke University MagdeburgMagdeburgGermany Center for Health and Medical Prevention(CHaMP) Otto-von-Guericke-UniversityMagdeburgGermany

Recently,Li and colleagues provided in Nature immunology1 a novel mechanism of immunosurveillance in epithelial tumors,in which cytotoxic innate lymphoid cells(ILCs)sense IL-15 secreted by the tumor itself.Both the adaptive immune system,including CD8+cytotoxic lymphocytes(CTLs),and innate immune cells such as Natural Killer(NK)cells are capable of providing antitumor immunity through the release of perforins and granzymes.In addition,also cytotoxic group 1 innate lymphoid cells(ILC1s)were reported to exert NK cell-like antitumor cell cytotoxicity.

关键词： lymphoid immunity mechanism